FreeBSD/Linux Kernel Cross Reference
sys/security/mac_policy.h

     /*
      * Copyright (c) 2007-2008 Apple Inc. All rights reserved.
      *
      * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
      * 
      * This file contains Original Code and/or Modifications of Original Code
      * as defined in and that are subject to the Apple Public Source License
      * Version 2.0 (the 'License'). You may not use this file except in
      * compliance with the License. The rights granted to you under the License
     * may not be used to create, or enable the creation or redistribution of,
     * unlawful or unlicensed copies of an Apple operating system, or to
     * circumvent, violate, or enable the circumvention or violation of, any
     * terms of an Apple operating system software license agreement.
     * 
     * Please obtain a copy of the License at
     * http://www.opensource.apple.com/apsl/ and read it before using this file.
     * 
     * The Original Code and all software distributed under the License are
     * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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     * Please see the License for the specific language governing rights and
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    /*-
     * Copyright (c) 1999-2002 Robert N. M. Watson
     * Copyright (c) 2001-2005 Networks Associates Technology, Inc.
     * Copyright (c) 2005-2007 SPARTA, Inc.
     * All rights reserved.
     *
     * This software was developed by Robert Watson for the TrustedBSD Project.
     *
     * This software was developed for the FreeBSD Project in part by Network
     * Associates Laboratories, the Security Research Division of Network
     * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
     * as part of the DARPA CHATS research program.
     *
     * This software was enhanced by SPARTA ISSO under SPAWAR contract
     * N66001-04-C-6019 ("SEFOS").
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD: src/sys/sys/mac_policy.h,v 1.39 2003/04/18 19:57:37 rwatson Exp $
     */
    
    /**
      @file mac_policy.h
      @brief Kernel Interfaces for MAC policy modules
    
      This header defines the list of operations that are defined by the
      TrustedBSD MAC Framwork on Darwin.  MAC Policy modules register
      with the framework to declare interest in a specific set of
      operations.  If interest in an entry point is not declared, then
      the policy will be ignored when the Framework evaluates that entry
      point.
    */
    
    #ifndef _SECURITY_MAC_POLICY_H_
    #define _SECURITY_MAC_POLICY_H_
    
    #include <security/_label.h>
    
    struct attrlist;
    struct auditinfo;
    struct bpf_d;
    struct devnode;
    struct fileglob;
    struct ifnet;
    struct inpcb;
    struct ipq;
    struct label;
    struct lctx;
    struct mac_module_data;
    struct mac_policy_conf;
    struct mbuf;
    struct mount;
    struct pipe;
   struct pseminfo;
   struct pshminfo;
   struct sbuf;
   struct semid_kernel;
   struct shmid_kernel;
   struct task;
   struct thread;
   struct ucred;
   struct vnode;
   /** @struct dummy */
   
   
   
   #ifndef _KAUTH_CRED_T
   #define _KAUTH_CRED_T
   typedef struct ucred *kauth_cred_t;
   #endif  /* !_KAUTH_CRED_T */
   
   
   /*-
    * MAC entry points are generally named using the following template:
    *
    *   mpo_<object>_<operation>()
    *
    * or:
    *
    *   mpo_<object>_check_<operation>()
    *
    * Entry points are sorted by object type.
    *
    * It may be desirable also to consider some subsystems as "objects", such
    * as system, iokit, etc.
    */
   
   /**
     @name Entry Points for Label Management
   
     These are the entry points corresponding to the life cycle events for
     kernel objects, such as initialization, creation, and destruction.
   
     Most policies (that use labels) will initialize labels by allocating
     space for policy-specific data.  In most cases, it is permitted to
     sleep during label initialization operations; it will be noted when
     it is not permitted.
   
     Initialization usually will not require doing more than allocating a
     generic label for the given object.  What follows initialization is
     creation, where a label is made specific to the object it is associated
     with.  Destruction occurs when the label is no longer needed, such as
     when the corresponding object is destroyed.  All necessary cleanup should
     be performed in label destroy operations.
   
     Where possible, the label entry points have identical parameters.  If
     the policy module does not require structure-specific label
     information, the same function may be registered in the policy
     operation vector.  Many policies will implement two such generic
     allocation calls: one to handle sleepable requests, and one to handle
     potentially non-sleepable requests.
   */
   
   
   /**
     @brief Audit event postselection
     @param cred Subject credential
     @param syscode Syscall number
     @param args Syscall arguments
     @param error Syscall errno
     @param retval Syscall return value
   
     This is the MAC Framework audit postselect, which is called before
     exiting a syscall to determine if an audit event should be committed.
     A return value of MAC_AUDIT_NO forces the audit record to be suppressed.
     Any other return value results in the audit record being committed.
   
     @warning The suppression behavior will probably go away in Apple's
     future version of the audit implementation.
   
     @return Return MAC_AUDIT_NO to force suppression of the audit record.
     Any other value results in the audit record being committed.
   
   */
   typedef int mpo_audit_check_postselect_t(
           kauth_cred_t cred,
           unsigned short syscode,
           void *args,
           int error,
           int retval
   );
   /**
     @brief Audit event preselection
     @param cred Subject credential
     @param syscode Syscall number
     @param args Syscall arguments
   
     This is the MAC Framework audit preselect, which is called before a
     syscall is entered to determine if an audit event should be created.
     If the MAC policy forces the syscall to be audited, MAC_AUDIT_YES should be
     returned. A return value of MAC_AUDIT_NO causes the audit record to
     be suppressed. Returning MAC_POLICY_DEFAULT indicates that the policy wants
     to defer to the system's existing preselection mechanism.
   
     When policies return different preferences, the Framework decides what action
     to take based on the following policy.  If any policy returns MAC_AUDIT_YES,
     then create an audit record, else if any policy returns MAC_AUDIT_NO, then
     suppress the creations of an audit record, else defer to the system's
     existing preselection mechanism.
   
     @warning The audit implementation in Apple's current version is
     incomplete, so the MAC policies have priority over the system's existing
     mechanisms. This will probably change in the future version where
     the audit implementation is more complete.
   
     @return Return MAC_AUDIT_YES to force auditing of the syscall,
     MAC_AUDIT_NO to force no auditing of the syscall, MAC_AUDIT_DEFAULT
     to allow auditing mechanisms to determine if the syscall is audited.
   
   */
   typedef int mpo_audit_check_preselect_t(
           kauth_cred_t cred,
           unsigned short syscode,
           void *args
   );
   /**
     @brief Initialize BPF descriptor label
     @param label New label to initialize
   
     Initialize the label for a newly instantiated BPF descriptor.
     Sleeping is permitted.
   */
   typedef void mpo_bpfdesc_label_init_t(
           struct label *label
   );
   /**
     @brief Destroy BPF descriptor label
     @param label The label to be destroyed
   
     Destroy a BPF descriptor label.  Since the BPF descriptor
     is going out of scope, policy modules should free any internal
     storage associated with the label so that it may be destroyed.
   */
   typedef void mpo_bpfdesc_label_destroy_t(
           struct label *label
   );
   /**
     @brief Associate a BPF descriptor with a label
     @param cred User credential creating the BPF descriptor
     @param bpf_d The BPF descriptor
     @param bpflabel The new label
   
     Set the label on a newly created BPF descriptor from the passed
     subject credential. This call will be made when a BPF device node
     is opened by a process with the passed subject credential.
   */
   typedef void mpo_bpfdesc_label_associate_t(
           kauth_cred_t cred,
           struct bpf_d *bpf_d,
           struct label *bpflabel
   );
   /**
     @brief Check whether BPF can read from a network interface
     @param bpf_d Subject; the BPF descriptor
     @param bpflabel Policy label for bpf_d 
     @param ifp Object; the network interface 
     @param ifnetlabel Policy label for ifp
   
     Determine whether the MAC framework should permit datagrams from
     the passed network interface to be delivered to the buffers of
     the passed BPF descriptor.  Return (0) for success, or an errno
     value for failure.  Suggested failure: EACCES for label mismatches,
     EPERM for lack of privilege.
   */
   typedef int mpo_bpfdesc_check_receive_t(
           struct bpf_d *bpf_d,
           struct label *bpflabel,
           struct ifnet *ifp,
           struct label *ifnetlabel
   );
   /**
     @brief Indicate desire to change the process label at exec time
     @param old Existing subject credential
     @param vp File being executed
     @param vnodelabel Label corresponding to vp
     @param scriptvnodelabel Script vnode label
     @param execlabel Userspace provided execution label
     @param proc Object process
     @see mac_execve
     @see mpo_cred_label_update_execve_t
     @see mpo_vnode_check_exec_t
   
     Indicate whether this policy intends to update the label of a newly
     created credential from the existing subject credential (old).  This
     call occurs when a process executes the passed vnode.  If a policy
     returns success from this entry point, the mpo_cred_label_update_execve
     entry point will later be called with the same parameters.  Access
     has already been checked via the mpo_vnode_check_exec entry point,
     this entry point is necessary to preserve kernel locking constraints
     during program execution.
   
     The supplied vnode and vnodelabel correspond with the file actually
     being executed; in the case that the file is interpreted (for
     example, a script), the label of the original exec-time vnode has
     been preserved in scriptvnodelabel.
   
     The final label, execlabel, corresponds to a label supplied by a
     user space application through the use of the mac_execve system call.
   
     The vnode lock is held during this operation.  No changes should be
     made to the old credential structure.
   
     @warning Even if a policy returns 0, it should behave correctly in
     the presence of an invocation of mpo_cred_label_update_execve, as that
     call may happen as a result of another policy requesting a transition.
   
     @return Non-zero if a transition is required, 0 otherwise.
   */
   typedef int mpo_cred_check_label_update_execve_t(
           kauth_cred_t old,
           struct vnode *vp,
           struct label *vnodelabel,
           struct label *scriptvnodelabel,
           struct label *execlabel,
           struct proc *proc
   );
   /**
     @brief Access control check for relabelling processes
     @param cred Subject credential
     @param newlabel New label to apply to the user credential
     @see mpo_cred_label_update_t
     @see mac_set_proc
   
     Determine whether the subject identified by the credential can relabel
     itself to the supplied new label (newlabel).  This access control check
     is called when the mac_set_proc system call is invoked.  A user space
     application will supply a new value, the value will be internalized
     and provided in newlabel.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   */
   typedef int mpo_cred_check_label_update_t(
           kauth_cred_t cred,
           struct label *newlabel
   );
   /**
     @brief Access control check for visibility of other subjects
     @param u1 Subject credential
     @param u2 Object credential
   
     Determine whether the subject identified by the credential u1 can
     "see" other subjects with the passed subject credential u2. This call
     may be made in a number of situations, including inter-process status
     sysctls used by ps, and in procfs lookups.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned. Suggested failure: EACCES for label mismatch,
     EPERM for lack of privilege, or ESRCH to hide visibility.
   */
   typedef int mpo_cred_check_visible_t(
           kauth_cred_t u1,
           kauth_cred_t u2
   );
   /**
     @brief Associate a credential with a new process at fork
     @param cred credential to inherited by new process
     @param proc the new process
   
     Allow a process to associate the credential with a new
     process for reference countng purposes.
     NOTE: the credential can be dis-associated in ways other
           than exit - so this strategy is flawed - should just
           catch label destroy callback.
   */
   typedef void mpo_cred_label_associate_fork_t(
           kauth_cred_t cred,
           proc_t proc
   );
   /**
     @brief Create the first process
     @param cred Subject credential to be labeled
   
     Create the subject credential of process 0, the parent of all BSD
     kernel processes.  Policies should update the label in the
     previously initialized credential structure.
   */
   typedef void mpo_cred_label_associate_kernel_t(
           kauth_cred_t cred
   );
   /**
     @brief Create a credential label
     @param parent_cred Parent credential
     @param child_cred Child credential
   
     Set the label of a newly created credential, most likely using the
     information in the supplied parent credential.
   
     @warning This call is made when crcopy or crdup is invoked on a
     newly created struct ucred, and should not be confused with a
     process fork or creation event.
   */
   typedef void mpo_cred_label_associate_t(
           kauth_cred_t parent_cred,
           kauth_cred_t child_cred
   );
   /**
     @brief Create the first process
     @param cred Subject credential to be labeled
   
     Create the subject credential of process 1, the parent of all BSD
     user processes.  Policies should update the label in the previously
     initialized credential structure.  This is the 'init' process.
   */
   typedef void mpo_cred_label_associate_user_t(
           kauth_cred_t cred
   );
   /**
     @brief Destroy credential label
     @param label The label to be destroyed
   
     Destroy a user credential label.  Since the user credential
     is going out of scope, policy modules should free any internal
     storage associated with the label so that it may be destroyed.
   */
   typedef void mpo_cred_label_destroy_t(
           struct label *label
   );
   /**
     @brief Externalize a user credential label for auditing
     @param label Label to be externalized
     @param element_name Name of the label namespace for which labels should be
     externalized
     @param sb String buffer to be filled with a text representation of the label
   
     Produce an external representation of the label on a user credential for
     inclusion in an audit record.  An externalized label consists of a text
     representation of the label contents that will be added to the audit record
     as part of a text token.  Policy-agnostic user space tools will display
     this externalized version.
   
     @return 0 on success, return non-zero if an error occurs while
     externalizing the label data.
   
   */
   typedef int mpo_cred_label_externalize_audit_t(
           struct label *label,
           char *element_name,
           struct sbuf *sb
   );
   /**
     @brief Externalize a user credential label
     @param label Label to be externalized
     @param element_name Name of the label namespace for which labels should be
     externalized
     @param sb String buffer to be filled with a text representation of the label
   
     Produce an external representation of the label on a user
     credential.  An externalized label consists of a text representation
     of the label contents that can be used with user applications.
     Policy-agnostic user space tools will display this externalized
     version.
   
     @return 0 on success, return non-zero if an error occurs while
     externalizing the label data.
   
   */
   typedef int mpo_cred_label_externalize_t(
           struct label *label,
           char *element_name,
           struct sbuf *sb
   );
   /**
     @brief Initialize user credential label
     @param label New label to initialize
   
     Initialize the label for a newly instantiated user credential.
     Sleeping is permitted.
   */
   typedef void mpo_cred_label_init_t(
           struct label *label
   );
   /**
     @brief Internalize a user credential label
     @param label Label to be internalized
     @param element_name Name of the label namespace for which the label should
     be internalized
     @param element_data Text data to be internalized
   
     Produce a user credential label from an external representation.  An
     externalized label consists of a text representation of the label
     contents that can be used with user applications.  Policy-agnostic
     user space tools will forward text version to the kernel for
     processing by individual policy modules.
   
     The policy's internalize entry points will be called only if the
     policy has registered interest in the label namespace.
   
     @return 0 on success, Otherwise, return non-zero if an error occurs
     while internalizing the label data.
   
   */
   typedef int mpo_cred_label_internalize_t(
           struct label *label,
           char *element_name,
           char *element_data
   );
   /**
     @brief Update credential at exec time
     @param old_cred Existing subject credential
     @param new_cred New subject credential to be labeled
     @param vp File being executed
     @param vnodelabel Label corresponding to vp
     @param scriptvnodelabel Script vnode label
     @param execlabel Userspace provided execution label
     @see mac_execve
     @see mpo_cred_check_label_update_execve_t
     @see mpo_vnode_check_exec_t
   
     Update the label of a newly created credential (new) from the
     existing subject credential (old).  This call occurs when a process
     executes the passed vnode and one of the loaded policy modules has
     returned success from the mpo_cred_check_label_update_execve entry point.
     Access has already been checked via the mpo_vnode_check_exec entry
     point, this entry point is only used to update any policy state.
   
     The supplied vnode and vnodelabel correspond with the file actually
     being executed; in the case that the file is interpreted (for
     example, a script), the label of the original exec-time vnode has
     been preserved in scriptvnodelabel.
   
     The final label, execlabel, corresponds to a label supplied by a
     user space application through the use of the mac_execve system call.
   
     If non-NULL, the value pointed to by disjointp will be set to 0 to
     indicate that the old and new credentials are not disjoint, or 1 to
     indicate that they are.
   
     The vnode lock is held during this operation.  No changes should be
     made to the old credential structure.
   */
   typedef void mpo_cred_label_update_execve_t(
           kauth_cred_t old_cred,
           kauth_cred_t new_cred,
           struct vnode *vp,
           struct label *vnodelabel,
           struct label *scriptvnodelabel,
           struct label *execlabel,
           int *disjointp
   );
   /**
     @brief Update a credential label
     @param cred The existing credential
     @param newlabel A new label to apply to the credential
     @see mpo_cred_check_label_update_t
     @see mac_set_proc
   
     Update the label on a user credential, using the supplied new label.
     This is called as a result of a process relabel operation.  Access
     control was already confirmed by mpo_cred_check_label_update.
   */
   typedef void mpo_cred_label_update_t(
           kauth_cred_t cred,
           struct label *newlabel
   );
   /**
     @brief Create a new devfs device
     @param dev Major and minor numbers of special file
     @param de "inode" of new device file
     @param label Destination label
     @param fullpath Path relative to mount (e.g. /dev) of new device file
   
     This entry point labels a new devfs device. The label will likely be based
     on the path to the device, or the major and minor numbers.
     The policy should store an appropriate label into 'label'.
   */
   typedef void mpo_devfs_label_associate_device_t(
           dev_t dev,
           struct devnode *de,
           struct label *label,
           const char *fullpath
   );
   /**
     @brief Create a new devfs directory
     @param dirname Name of new directory
     @param dirnamelen Length of 'dirname'
     @param de "inode" of new directory
     @param label Destination label
     @param fullpath Path relative to mount (e.g. /dev) of new directory
   
     This entry point labels a new devfs directory. The label will likely be
     based on the path of the new directory. The policy should store an appropriate
     label into 'label'. The devfs root directory is labelled in this way.
   */
   typedef void mpo_devfs_label_associate_directory_t(
           const char *dirname,
           int dirnamelen,
           struct devnode *de,
           struct label *label,
           const char *fullpath
   );
   /**
     @brief Copy a devfs label
     @param src Source devfs label
     @param dest Destination devfs label
   
     Copy the label information from src to dest.  The devfs file system
     often duplicates (splits) existing device nodes rather than creating
     new ones.
   */
   typedef void mpo_devfs_label_copy_t(
           struct label *src,
           struct label *dest
   );
   /**
     @brief Destroy devfs label
     @param label The label to be destroyed
   
     Destroy a devfs entry label.  Since the object is going out
     of scope, policy modules should free any internal storage associated
     with the label so that it may be destroyed.
   */
   typedef void mpo_devfs_label_destroy_t(
           struct label *label
   );
   /**
     @brief Initialize devfs label
     @param label New label to initialize
   
     Initialize the label for a newly instantiated devfs entry.  Sleeping
     is permitted.
   */
   typedef void mpo_devfs_label_init_t(
           struct label *label
   );
   /**
     @brief Update a devfs label after relabelling its vnode
     @param mp Devfs mount point
     @param de Affected devfs directory entry
     @param delabel Label of devfs directory entry
     @param vp Vnode associated with de
     @param vnodelabel New label of vnode
   
     Update a devfs label when its vnode is manually relabelled,
     for example with setfmac(1). Typically, this will simply copy
     the vnode label into the devfs label.
   */
   typedef void mpo_devfs_label_update_t(
           struct mount *mp,
           struct devnode *de,
           struct label *delabel,
           struct vnode *vp,
           struct label *vnodelabel
   );
   /**
     @brief Access control for changing the offset of a file descriptor
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
   
     Determine whether the subject identified by the credential can
     change the offset of the file represented by fg.
   
     @return Return 0 if access if granted, otherwise an appropriate
     value for errno should be returned.
   */
   typedef int mpo_file_check_change_offset_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label
   );
   /**
     @brief Access control for creating a file descriptor
     @param cred Subject credential
   
     Determine whether the subject identified by the credential can
     allocate a new file descriptor.
   
     @return Return 0 if access if granted, otherwise an appropriate
     value for errno should be returned.
   */
   typedef int mpo_file_check_create_t(
           kauth_cred_t cred
   );
   /**
     @brief Access control for duplicating a file descriptor
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
     @param newfd New file descriptor number
   
     Determine whether the subject identified by the credential can
     duplicate the fileglob structure represented by fg and as file
     descriptor number newfd.
   
     @return Return 0 if access if granted, otherwise an appropriate
     value for errno should be returned.
   */
   typedef int mpo_file_check_dup_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label,
           int newfd
   );
   /**
     @brief Access control check for fcntl
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
     @param cmd Control operation to be performed; see fcntl(2)
     @param arg fcnt arguments; see fcntl(2)
   
     Determine whether the subject identified by the credential can perform
     the file control operation indicated by cmd.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   */
   typedef int mpo_file_check_fcntl_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label,
           int cmd,
           user_long_t arg
   );
   /**
     @brief Access control check for mac_get_fd
     @param cred Subject credential
     @param fg Fileglob structure
     @param elements Element buffer
     @param len Length of buffer
   
     Determine whether the subject identified by the credential should be allowed
     to get an externalized version of the label on the object indicated by fd.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   */
   typedef int mpo_file_check_get_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           char *elements,
           int len
   );
   /**
     @brief Access control for getting the offset of a file descriptor
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
   
     Determine whether the subject identified by the credential can
     get the offset of the file represented by fg.
   
     @return Return 0 if access if granted, otherwise an appropriate
     value for errno should be returned.
   */
   typedef int mpo_file_check_get_offset_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label
   );
   /**
     @brief Access control for inheriting a file descriptor
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
   
     Determine whether the subject identified by the credential can
     inherit the fileglob structure represented by fg.
   
     @return Return 0 if access if granted, otherwise an appropriate
     value for errno should be returned.
   */
   typedef int mpo_file_check_inherit_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label
   );
   /**
     @brief Access control check for file ioctl
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
     @param cmd The ioctl command; see ioctl(2)
   
     Determine whether the subject identified by the credential can perform
     the ioctl operation indicated by cmd.
   
     @warning Since ioctl data is opaque from the standpoint of the MAC
     framework, policies must exercise extreme care when implementing
     access control checks.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   
   */
   typedef int mpo_file_check_ioctl_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label,
           unsigned int cmd
   );
   /**
     @brief Access control check for file locking
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
     @param op The lock operation (F_GETLK, F_SETLK, F_UNLK)
     @param fl The flock structure
   
     Determine whether the subject identified by the credential can perform
     the lock operation indicated by op and fl on the file represented by fg.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   
   */
   typedef int mpo_file_check_lock_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label,
           int op,
           struct flock *fl
   );
   /**
     @brief Access control check for mapping a file
     @param cred Subject credential
     @param fg fileglob representing file to map
     @param label Policy label associated with vp
     @param prot mmap protections; see mmap(2)
     @param flags Type of mapped object; see mmap(2)
     @param maxprot Maximum rights
   
     Determine whether the subject identified by the credential should be
     allowed to map the file represented by fg with the protections specified
     in prot.  The maxprot field holds the maximum permissions on the new
     mapping, a combination of VM_PROT_READ, VM_PROT_WRITE, and VM_PROT_EXECUTE.
     To avoid overriding prior access control checks, a policy should only
     remove flags from maxprot.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned. Suggested failure: EACCES for label mismatch or
     EPERM for lack of privilege.
   */
   typedef int mpo_file_check_mmap_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label,
           int prot,
           int flags,
           int *maxprot
   );
   /**
     @brief Downgrade the mmap protections
     @param cred Subject credential
     @param fg file to map
     @param label Policy label associated with vp
     @param prot mmap protections to be downgraded
   
     Downgrade the mmap protections based on the subject and object labels.
   */
   typedef void mpo_file_check_mmap_downgrade_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label,
           int *prot
   );
   /**
     @brief Access control for receiving a file descriptor
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
   
     Determine whether the subject identified by the credential can
     receive the fileglob structure represented by fg.
   
     @return Return 0 if access if granted, otherwise an appropriate
     value for errno should be returned.
   */
   typedef int mpo_file_check_receive_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label
   );
   /**
     @brief Access control check for mac_set_fd
     @param cred Subject credential
     @param fg Fileglob structure
     @param elements Elements buffer
     @param len Length of elements buffer
   
     Determine whether the subject identified by the credential can
     perform the mac_set_fd operation.  The mac_set_fd operation is used
     to associate a MAC label with a file.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   */
   typedef int mpo_file_check_set_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           char *elements,
           int len
   );
   /**
     @brief Create file label
     @param cred Subject credential
     @param fg Fileglob structure
     @param label Policy label for fg
   */
   typedef void mpo_file_label_associate_t(
           kauth_cred_t cred,
           struct fileglob *fg,
           struct label *label
   );
   /**
    @brief Destroy file label
    @param label The label to be destroyed
   
    Destroy the label on a file descriptor.  In this entry point, a
    policy module should free any internal storage associated with
    label so that it may be destroyed.
   */
   typedef void mpo_file_label_destroy_t(
           struct label *label
   );
   /**
     @brief Initialize file label
     @param label New label to initialize
   */
   typedef void mpo_file_label_init_t(
           struct label *label
   );
   /**
     @brief Access control check for relabeling network interfaces
     @param cred Subject credential
     @param ifp network interface being relabeled
     @param ifnetlabel Current label of the network interfaces
     @param newlabel New label to apply to the network interfaces
     @see mpo_ifnet_label_update_t
   
     Determine whether the subject identified by the credential can
     relabel the network interface represented by ifp to the supplied
     new label (newlabel).
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   */
   typedef int mpo_ifnet_check_label_update_t(
           kauth_cred_t cred,
           struct ifnet *ifp,
           struct label *ifnetlabel,
           struct label *newlabel
   );
   /**
     @brief Access control check for relabeling network interfaces
     @param ifp Network interface mbuf will be transmitted through
     @param ifnetlabel Label of the network interfaces
     @param m The mbuf to be transmitted
     @param mbuflabel Label of the mbuf to be transmitted
     @param family Address Family, AF_*
     @param type Type of socket, SOCK_{STREAM,DGRAM,RAW}
   
     Determine whether the mbuf with label mbuflabel may be transmitted
     through the network interface represented by ifp that has the
     label ifnetlabel.
   
     @return Return 0 if access is granted, otherwise an appropriate value for
     errno should be returned.
   */
   typedef int mpo_ifnet_check_transmit_t(
           struct ifnet *ifp,
           struct label *ifnetlabel,
           struct mbuf *m,
           struct label *mbuflabel,
           int family,
           int type
   );
   /**
     @brief Create a network interface label
     @param ifp Network interface labeled
     @param ifnetlabel Label for the network interface
   
     Set the label of a newly created network interface, most likely
     using the information in the supplied network interface struct.
   */
   typedef void mpo_ifnet_label_associate_t(
           struct ifnet *ifp,
           struct label *ifnetlabel
   );
   /**
     @brief Copy an ifnet label
     @param src Source ifnet label
     @param dest Destination ifnet label
   
     Copy the label information from src to dest.
   */
   typedef void mpo_ifnet_label_copy_t(
           struct label *src,
           struct label *dest
   );
   /**
    @brief Destroy ifnet label
   @param label The label to be destroyed
  
   Destroy the label on an ifnet label.  In this entry point, a
   policy module should free any internal storage associated with
   label so that it may be destroyed.
  */
  typedef void mpo_ifnet_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize an ifnet label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of the label
  
    Produce an external representation of the label on an interface.
    An externalized label consists of a text representation of the
    label contents that can be used with user applications.
    Policy-agnostic user space tools will display this externalized
    version.
  
    @return 0 on success, return non-zero if an error occurs while
    externalizing the label data.
  
  */
  typedef int mpo_ifnet_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize ifnet label
    @param label New label to initialize
  */
  typedef void mpo_ifnet_label_init_t(
          struct label *label
  );
  /**
    @brief Internalize an interface label
    @param label Label to be internalized
    @param element_name Name of the label namespace for which the label should
    be internalized
    @param element_data Text data to be internalized
  
    Produce an interface label from an external representation.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will forward text version to the kernel for
    processing by individual policy modules.
  
    The policy's internalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, Otherwise, return non-zero if an error occurs
    while internalizing the label data.
  
  */
  typedef int mpo_ifnet_label_internalize_t(
          struct label *label,
          char *element_name,
          char *element_data
  );
  /**
    @brief Recycle up a network interface label
    @param label The label to be recycled
  
    Recycle a network interface label.  Darwin caches the struct ifnet
    of detached ifnets in a "free pool".  Before ifnets are returned
    to the "free pool", policies can cleanup or overwrite any information
    present in the label.
  */
  typedef void mpo_ifnet_label_recycle_t(
          struct label *label
  );
  /**
    @brief Update a network interface label
    @param cred Subject credential
    @param ifp The network interface to be relabeled
    @param ifnetlabel The current label of the network interface
    @param newlabel A new label to apply to the network interface
    @see mpo_ifnet_check_label_update_t
  
    Update the label on a network interface, using the supplied new label.
  */
  typedef void mpo_ifnet_label_update_t(
          kauth_cred_t cred,
          struct ifnet *ifp,
          struct label *ifnetlabel,
          struct label *newlabel
  );
  /**
    @brief Access control check for delivering a packet to a socket
    @param inp inpcb the socket is associated with
    @param inplabel Label of the inpcb
    @param m The mbuf being received
    @param mbuflabel Label of the mbuf being received
    @param family Address family, AF_*
    @param type Type of socket, SOCK_{STREAM,DGRAM,RAW}
  
    Determine whether the mbuf with label mbuflabel may be received
    by the socket associated with inpcb that has the label inplabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_inpcb_check_deliver_t(
          struct inpcb *inp,
          struct label *inplabel,
          struct mbuf *m,
          struct label *mbuflabel,
          int family,
          int type
  );
  /**
    @brief Create an inpcb label
    @param so Socket containing the inpcb to be labeled
    @param solabel Label of the socket
    @param inp inpcb to be labeled
    @param inplabel Label for the inpcb
  
    Set the label of a newly created inpcb, most likely
    using the information in the socket and/or socket label.
  */
  typedef void mpo_inpcb_label_associate_t(
          struct socket *so,
          struct label *solabel,
          struct inpcb *inp,
          struct label *inplabel
  );
  /**
   @brief Destroy inpcb label
   @param label The label to be destroyed
  
   Destroy the label on an inpcb label.  In this entry point, a
   policy module should free any internal storage associated with
   label so that it may be destroyed.
  */
  typedef void mpo_inpcb_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize inpcb label
    @param label New label to initialize
    @param flag M_WAITOK or M_NOWAIT
  */
  typedef int mpo_inpcb_label_init_t(
          struct label *label,
          int flag
  );
  /**
    @brief Recycle up an inpcb label
    @param label The label to be recycled
  
    Recycle an inpcb label.  Darwin allocates the inpcb as part of
    the socket structure in some cases.  For this case we must recycle
    rather than destroy the inpcb as it will be reused later.
  */
  typedef void mpo_inpcb_label_recycle_t(
          struct label *label
  );
  /**
    @brief Update an inpcb label from a socket label
    @param so Socket containing the inpcb to be relabeled
    @param solabel New label of the socket
    @param inp inpcb to be labeled
    @param inplabel Label for the inpcb
  
    Set the label of a newly created inpcb due to a change in the
    underlying socket label.
  */
  typedef void mpo_inpcb_label_update_t(
          struct socket *so,
          struct label *solabel,
          struct inpcb *inp,
          struct label *inplabel
  );
  /**
    @brief Device hardware access control
    @param devtype Type of device connected
    @param properties XML-formatted property list
    @param proplen Length of the property list
  
    This is the MAC Framework device access control, which is called by the I/O
    Kit when a new device is connected to the system to determine whether that
    device should be trusted.  A list of properties associated with the device
    is passed as an XML-formatted string.  The routine should examine these
    properties to determine the trustworthiness of the device.  A return value
    of EPERM forces the device to be claimed by a special device driver that
    will prevent its operation.
  
    @warning This is an experimental interface and may change in the future.
  
    @return Return EPERM to indicate that the device is untrusted and should
    not be allowed to operate.  Return zero to indicate that the device is
    trusted and should be allowed to operate normally.
  
  */
  typedef int mpo_iokit_check_device_t(
          char *devtype,
          struct mac_module_data *mdata
  );
  /**
    @brief Create an IP reassembly queue label
    @param fragment First received IP fragment
    @param fragmentlabel Policy label for fragment
    @param ipq IP reassembly queue to be labeled
    @param ipqlabel Policy label to be filled in for ipq
  
    Set the label on a newly created IP reassembly queue from
    the mbuf header of the first received fragment.
  */
  typedef void mpo_ipq_label_associate_t(
          struct mbuf *fragment,
          struct label *fragmentlabel,
          struct ipq *ipq,
          struct label *ipqlabel
  );
  /**
    @brief Compare an mbuf header label to an ipq label
    @param fragment IP datagram fragment
    @param fragmentlabel Policy label for fragment
    @param ipq IP fragment reassembly queue
    @param ipqlabel Policy label for ipq
  
    Compare the label of the mbuf header containing an IP datagram
    (fragment) fragment with the label of the passed IP fragment
    reassembly queue (ipq). Return (1) for a successful match, or (0)
    for no match. This call is made when the IP stack attempts to
    find an existing fragment reassembly queue for a newly received
    fragment; if this fails, a new fragment reassembly queue may be
    instantiated for the fragment. Policies may use this entry point
    to prevent the reassembly of otherwise matching IP fragments if
    policy does not permit them to be reassembled based on the label
    or other information.
  */
  typedef int mpo_ipq_label_compare_t(
          struct mbuf *fragment,
          struct label *fragmentlabel,
          struct ipq *ipq,
          struct label *ipqlabel
  );
  /**
   @brief Destroy IP reassembly queue label
   @param label The label to be destroyed
  
   Destroy the label on an IP fragment queue.  In this entry point, a
   policy module should free any internal storage associated with
   label so that it may be destroyed.
  */
  typedef void mpo_ipq_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize IP reassembly queue label
    @param label New label to initialize
    @param flag M_WAITOK or M_NOWAIT
  
    Initialize the label on a newly instantiated IP fragment reassembly
    queue.  The flag field may be one of M_WAITOK and M_NOWAIT, and
    should be employed to avoid performing a sleeping malloc(9) during
    this initialization call. IP fragment reassembly queue allocation
    frequently occurs in performance sensitive environments, and the
    implementation should be careful to avoid sleeping or long-lived
    operations. This entry point is permitted to fail resulting in
    the failure to allocate the IP fragment reassembly queue.
  */
  typedef int mpo_ipq_label_init_t(
          struct label *label,
          int flag
  );
  /**
    @brief Update the label on an IP fragment reassembly queue
    @param fragment IP fragment
    @param fragmentlabel Policy label for fragment
    @param ipq IP fragment reassembly queue
    @param ipqlabel Policy label to be updated for ipq
  
    Update the label on an IP fragment reassembly queue (ipq) based
    on the acceptance of the passed IP fragment mbuf header (fragment).
  */
  typedef void mpo_ipq_label_update_t(
          struct mbuf *fragment,
          struct label *fragmentlabel,
          struct ipq *ipq,
          struct label *ipqlabel
  );
  /**
    @brief Access control check for relabelling Login Context
    @param l Subject credential
    @param newlabel New label to apply to the Login Context
    @see mpo_lctx_label_update_t
    @see mac_set_lcid
    @see mac_set_lctx
  
    Determine whether the subject identified by the credential can relabel
    itself to the supplied new label (newlabel).  This access control check
    is called when the mac_set_lctx/lcid system call is invoked.  A user space
    application will supply a new value, the value will be internalized
    and provided in newlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_lctx_check_label_update_t(
          struct lctx *l,
          struct label *newlabel
  );
  /**
   @brief Destroy Login Context label
   @param label The label to be destroyed
  */
  typedef void mpo_lctx_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize a Login Context label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of the label
  
    Produce an external representation of the label on a Login Context.
    An externalized label consists of a text representation
    of the label contents that can be used with user applications.
    Policy-agnostic user space tools will display this externalized
    version.
  
    @return 0 on success, return non-zero if an error occurs while
    externalizing the label data.
  
  */
  typedef int mpo_lctx_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize Login Context label
    @param label New label to initialize
  */
  typedef void mpo_lctx_label_init_t(
          struct label *label
  );
  /**
    @brief Internalize a Login Context label
    @param label Label to be internalized
    @param element_name Name of the label namespace for which the label should
    be internalized
    @param element_data Text data to be internalized
  
    Produce a Login Context label from an external representation.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will forward text version to the kernel for
    processing by individual policy modules.
  
    The policy's internalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, Otherwise, return non-zero if an error occurs
    while internalizing the label data.
  
  */
  typedef int mpo_lctx_label_internalize_t(
          struct label *label,
          char *element_name,
          char *element_data
  );
  /**
    @brief Update a Login Context label
    @param l
    @param newlabel A new label to apply to the Login Context
    @see mpo_lctx_check_label_update_t
    @see mac_set_lcid
    @see mac_set_lctx
  
    Update the label on a login context, using the supplied new label.
    This is called as a result of a login context relabel operation.  Access
    control was already confirmed by mpo_lctx_check_label_update.
  */
  typedef void mpo_lctx_label_update_t(
          struct lctx *l,
          struct label *newlabel
  );
  /**
    @brief A process has created a login context
    @param p Subject
    @param l Login Context
  
    When a process creates a login context (via setlcid()) this entrypoint
    is called to notify the policy that the process 'p' has created login
    context 'l'.
  */
  typedef void mpo_lctx_notify_create_t(
          struct proc *p,
          struct lctx *l
  );
  /**
    @brief A process has joined a login context
    @param p Subject
    @param l Login Context
  
    When a process joins a login context, either via setlcid() or via
    fork() this entrypoint is called to notify the policy that process
    'p' is now a member of login context 'l'.
  */
  typedef void mpo_lctx_notify_join_t(
          struct proc *p,
          struct lctx *l
  );
  /**
    @brief A process has left a login context
    @param p Subject
    @param l Login Context
  
    When a process leaves a login context either via setlcid() or as a
    result of the process exiting this entrypoint is called to notify
    the policy that the process 'p' is no longer a member of login context 'l'.
  */
  typedef void mpo_lctx_notify_leave_t(
          struct proc *p,
          struct lctx *l
  );
  /**
   @brief Assign a label to a new mbuf
   @param bpf_d BPF descriptor
   @param b_label Policy label for bpf_d
   @param m Object; mbuf
   @param m_label Policy label to fill in for m
  
   Set the label on the mbuf header of a newly created datagram
   generated using the passed BPF descriptor. This call is made when
   a write is performed to the BPF device associated with the passed
   BPF descriptor.
  */
  typedef void mpo_mbuf_label_associate_bpfdesc_t(
          struct bpf_d *bpf_d,
          struct label *b_label,
          struct mbuf *m,
          struct label *m_label
  );
  /**
   @brief Assign a label to a new mbuf
   @param ifp Interface descriptor
   @param i_label Existing label of ifp
   @param m Object; mbuf
   @param m_label Policy label to fill in for m
  
   Label an mbuf based on the interface from which it was received.
  */
  typedef void mpo_mbuf_label_associate_ifnet_t(
          struct ifnet *ifp,
          struct label *i_label,
          struct mbuf *m,
          struct label *m_label
  );
  /**
   @brief Assign a label to a new mbuf
   @param inp inpcb structure
   @param i_label Existing label of inp
   @param m Object; mbuf
   @param m_label Policy label to fill in for m
  
   Label an mbuf based on the inpcb from which it was derived.
  */
  typedef void mpo_mbuf_label_associate_inpcb_t(
          struct inpcb *inp,
          struct label *i_label,
          struct mbuf *m,
          struct label *m_label
  );
  /**
    @brief Set the label on a newly reassembled IP datagram
    @param ipq IP fragment reassembly queue
    @param ipqlabel Policy label for ipq
    @param mbuf IP datagram to be labeled
    @param mbuflabel Policy label to be filled in for mbuf
  
    Set the label on a newly reassembled IP datagram (mbuf) from the IP
    fragment reassembly queue (ipq) from which it was generated.
  */
  typedef void mpo_mbuf_label_associate_ipq_t(
          struct ipq *ipq,
          struct label *ipqlabel,
          struct mbuf *mbuf,
          struct label *mbuflabel
  );
  /**
   @brief Assign a label to a new mbuf
   @param ifp Subject; network interface
   @param i_label Existing label of ifp
   @param m Object; mbuf
   @param m_label Policy label to fill in for m
  
   Set the label on the mbuf header of a newly created datagram
   generated for the purposes of a link layer response for the passed
   interface. This call may be made in a number of situations, including
   for ARP or ND6 responses in the IPv4 and IPv6 stacks.
  */
  typedef void mpo_mbuf_label_associate_linklayer_t(
          struct ifnet *ifp,
          struct label *i_label,
          struct mbuf *m,
          struct label *m_label
  );
  /**
   @brief Assign a label to a new mbuf
   @param oldmbuf mbuf headerder for existing datagram for existing datagram
   @param oldmbuflabel Policy label for oldmbuf
   @param ifp Network interface
   @param ifplabel Policy label for ifp
   @param newmbuf mbuf header to be labeled for new datagram
   @param newmbuflabel Policy label for newmbuf
  
   Set the label on the mbuf header of a newly created datagram
   generated from the existing passed datagram when it is processed
   by the passed multicast encapsulation interface. This call is made
   when an mbuf is to be delivered using the virtual interface.
  */
  typedef void mpo_mbuf_label_associate_multicast_encap_t(
          struct mbuf *oldmbuf,
          struct label *oldmbuflabel,
          struct ifnet *ifp,
          struct label *ifplabel,
          struct mbuf *newmbuf,
          struct label *newmbuflabel
  );
  /**
   @brief Assign a label to a new mbuf
   @param oldmbuf Received datagram
   @param oldmbuflabel Policy label for oldmbuf
   @param newmbuf Newly created datagram
   @param newmbuflabel Policy label for newmbuf
  
   Set the label on the mbuf header of a newly created datagram generated
   by the IP stack in response to an existing received datagram (oldmbuf).
   This call may be made in a number of situations, including when responding
   to ICMP request datagrams.
  */
  typedef void mpo_mbuf_label_associate_netlayer_t(
          struct mbuf *oldmbuf,
          struct label *oldmbuflabel,
          struct mbuf *newmbuf,
          struct label *newmbuflabel
  );
  /**
    @brief Assign a label to a new mbuf
    @param so Socket to label
    @param so_label Policy label for socket
    @param m Object; mbuf
    @param m_label Policy label to fill in for m
  
    An mbuf structure is used to store network traffic in transit.
    When an application sends data to a socket or a pipe, it is wrapped
    in an mbuf first.  This function sets the label on a newly created mbuf header
    based on the socket sending the data.  The contents of the label should be
    suitable for performing an access check on the receiving side of the
    communication.
  
    Only labeled MBUFs will be presented to the policy via this entrypoint.
  */
  typedef void mpo_mbuf_label_associate_socket_t(
          socket_t so,
          struct label *so_label,
          struct mbuf *m,
          struct label *m_label
  );
  /**
    @brief Copy a mbuf label
    @param src Source label
    @param dest Destination label
  
    Copy the mbuf label information in src into dest.
  
    Only called when both source and destination mbufs have labels.
  */
  typedef void mpo_mbuf_label_copy_t(
          struct label *src,
          struct label *dest
  );
  /**
    @brief Destroy mbuf label
    @param label The label to be destroyed
  
    Destroy a mbuf label.  Since the
    object is going out of scope, policy modules should free any
    internal storage associated with the label so that it may be
    destroyed.
  */
  typedef void mpo_mbuf_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize mbuf label
    @param label New label to initialize
    @param flag Malloc flags
  
    Initialize the label for a newly instantiated mbuf.
  
    @warning Since it is possible for the flags to be set to
    M_NOWAIT, the malloc operation may fail.
  
    @return On success, 0, otherwise, an appropriate errno return value.
  */
  typedef int mpo_mbuf_label_init_t(
          struct label *label,
          int flag
  );
  /**
    @brief Access control check for fsctl
    @param cred Subject credential
    @param mp The mount point
    @param label Label associated with the mount point
    @param com Filesystem-dependent request code; see fsctl(2)
  
    Determine whether the subject identified by the credential can perform
    the volume operation indicated by com.
  
    @warning The fsctl() system call is directly analogous to ioctl(); since
    the associated data is opaque from the standpoint of the MAC framework
    and since these operations can affect many aspects of system operation,
    policies must exercise extreme care when implementing access control checks.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_mount_check_fsctl_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *label,
          unsigned int cmd
  );
  /**
    @brief Access control check for the retrieval of file system attributes
    @param cred Subject credential
    @param mp The mount structure of the file system
    @param vfa The attributes requested
  
    This entry point determines whether given subject can get information
    about the given file system.  This check happens during statfs() syscalls,
    but is also used by other parts within the kernel such as the audit system.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  
  typedef int mpo_mount_check_getattr_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mp_label,
          struct vfs_attr *vfa
  );
  /**
    @brief Access control check for mount point relabeling
    @param cred Subject credential
    @param mp Object file system mount point
    @param mntlabel Policy label for fle system mount point
  
    Determine whether the subject identified by the credential can relabel
    the mount point. This call is made when a file system mount is updated.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch
    or EPERM for lack of privilege.
  */
  typedef int mpo_mount_check_label_update_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mntlabel
  );
  /**
    @brief Access control check for mounting a file system
    @param cred Subject credential
    @param vp Vnode that is to be the mount point
    @param vlabel Label associated with the vnode
    @param cnp Component name for vp
    @param vfc_name Filesystem type name
  
    Determine whether the subject identified by the credential can perform
    the mount operation on the target vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_mount_check_mount_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vlabel,
          struct componentname *cnp,
          const char *vfc_name
  );
  /**
    @brief Access control check remounting a filesystem
    @param cred Subject credential
    @param mp The mount point
    @param mlabel Label currently associated with the mount point
  
    Determine whether the subject identified by the credential can perform
    the remount operation on the target vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_mount_check_remount_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mlabel
  );
  /**
    @brief Access control check for the settting of file system attributes
    @param cred Subject credential
    @param mp The mount structure of the file system
    @param vfa The attributes requested
  
    This entry point determines whether given subject can set information
    about the given file system, for example the volume name.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  
  typedef int mpo_mount_check_setattr_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mp_label,
          struct vfs_attr *vfa
  );
  /**
    @brief Access control check for file system statistics
    @param cred Subject credential
    @param mp Object file system mount
    @param mntlabel Policy label for mp
  
    Determine whether the subject identified by the credential can see
    the results of a statfs performed on the file system. This call may
    be made in a number of situations, including during invocations of
    statfs(2) and related calls, as well as to determine what file systems
    to exclude from listings of file systems, such as when getfsstat(2)
    is invoked.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch
    or EPERM for lack of privilege.
  */
  typedef int mpo_mount_check_stat_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mntlabel
  );
  /**
    @brief Access control check for unmounting a filesystem
    @param cred Subject credential
    @param mp The mount point
    @param mlabel Label associated with the mount point
  
    Determine whether the subject identified by the credential can perform
    the unmount operation on the target vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_mount_check_umount_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mlabel
  );
  /**
    @brief Create mount labels
    @param cred Subject credential
    @param mp Mount point of file system being mounted
    @param mntlabel Label to associate with the new mount point
    @see mpo_mount_label_init_t
  
    Fill out the labels on the mount point being created by the supplied
    user credential.  This call is made when file systems are first mounted.
  */
  typedef void mpo_mount_label_associate_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mntlabel
  );
  /**
    @brief Destroy mount label
    @param label The label to be destroyed
  
    Destroy a file system mount label.  Since the
    object is going out of scope, policy modules should free any
    internal storage associated with the label so that it may be
    destroyed.
  */
  typedef void mpo_mount_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize a mount point label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of the label
  
    Produce an external representation of the mount point label.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will display this externalized version.
  
    The policy's externalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, return non-zero if an error occurs while
    externalizing the label data.
  
  */
  typedef int mpo_mount_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize mount point label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated mount structure.
    This label is typically used to store a default label in the case
    that the file system has been mounted singlelabel.  Since some
    file systems do not support persistent labels (extended attributes)
    or are read-only (such as CD-ROMs), it is often necessary to store
    a default label separately from the label of the mount point
    itself.  Sleeping is permitted.
  */
  typedef void mpo_mount_label_init_t(
          struct label *label
  );
  /**
    @brief Internalize a mount point label
    @param label Label to be internalized
    @param element_name Name of the label namespace for which the label should
    be internalized
    @param element_data Text data to be internalized
  
    Produce a mount point file system label from an external representation.
    An externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will forward text version to the kernel for
    processing by individual policy modules.
  
    The policy's internalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, Otherwise, return non-zero if an error occurs
    while internalizing the label data.
  
  */
  typedef int mpo_mount_label_internalize_t(
          struct label *label,
          char *element_name,
          char *element_data
  );
  /**
    @brief Set the label on an IPv4 datagram fragment
    @param datagram Datagram being fragmented
    @param datagramlabel Policy label for datagram
    @param fragment New fragment
    @param fragmentlabel Policy label for fragment
  
    Called when an IPv4 datagram is fragmented into several smaller datagrams.
    Policies implementing mbuf labels will typically copy the label from the
    source datagram to the new fragment.
  */
  typedef void mpo_netinet_fragment_t(
          struct mbuf *datagram,
          struct label *datagramlabel,
          struct mbuf *fragment,
          struct label *fragmentlabel
  );
  /**
    @brief Set the label on an ICMP reply
    @param m mbuf containing the ICMP reply
    @param mlabel Policy label for m
  
    A policy may wish to update the label of an mbuf that refers to
    an ICMP packet being sent in response to an IP packet.  This may
    be called in response to a bad packet or an ICMP request.
  */
  typedef void mpo_netinet_icmp_reply_t(
          struct mbuf *m,
          struct label *mlabel
  );
  /**
    @brief Set the label on a TCP reply
    @param m mbuf containing the TCP reply
    @param mlabel Policy label for m
  
    Called for outgoing TCP packets not associated with an actual socket.
  */
  typedef void mpo_netinet_tcp_reply_t(
          struct mbuf *m,
          struct label *mlabel
  );
  /**
    @brief Access control check for pipe ioctl
    @param cred Subject credential
    @param cpipe Object to be accessed
    @param pipelabel The label on the pipe
    @param cmd The ioctl command; see ioctl(2)
  
    Determine whether the subject identified by the credential can perform
    the ioctl operation indicated by cmd.
  
    @warning Since ioctl data is opaque from the standpoint of the MAC
    framework, policies must exercise extreme care when implementing
    access control checks.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  
  */
  typedef int mpo_pipe_check_ioctl_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *pipelabel,
          unsigned int cmd
  );
  /**
    @brief Access control check for pipe kqfilter
    @param cred Subject credential
    @param kn Object knote
    @param cpipe Object to be accessed
    @param pipelabel Policy label for the pipe
  
    Determine whether the subject identified by the credential can
    receive the knote on the passed pipe.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_pipe_check_kqfilter_t(
          kauth_cred_t cred,
          struct knote *kn,
          struct pipe *cpipe,
          struct label *pipelabel
  );
  /**
    @brief Access control check for pipe relabel
    @param cred Subject credential
    @param cpipe Object to be accessed
    @param pipelabel The current label on the pipe
    @param newlabel The new label to be used
  
    Determine whether the subject identified by the credential can
    perform a relabel operation on the passed pipe.  The cred object holds
    the credentials of the subject performing the operation.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  
  */
  typedef int mpo_pipe_check_label_update_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *pipelabel,
          struct label *newlabel
  );
  /**
    @brief Access control check for pipe read
    @param cred Subject credential
    @param cpipe Object to be accessed
    @param pipelabel The label on the pipe
  
    Determine whether the subject identified by the credential can
    perform a read operation on the passed pipe.  The cred object holds
    the credentials of the subject performing the operation.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  
  */
  typedef int mpo_pipe_check_read_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *pipelabel
  );
  /**
    @brief Access control check for pipe select
    @param cred Subject credential
    @param cpipe Object to be accessed
    @param pipelabel The label on the pipe
    @param which The operation selected on: FREAD or FWRITE
  
    Determine whether the subject identified by the credential can
    perform a select operation on the passed pipe.  The cred object holds
    the credentials of the subject performing the operation.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  
  */
  typedef int mpo_pipe_check_select_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *pipelabel,
          int which
  );
  /**
    @brief Access control check for pipe stat
    @param cred Subject credential
    @param cpipe Object to be accessed
    @param pipelabel The label on the pipe
  
    Determine whether the subject identified by the credential can
    perform a stat operation on the passed pipe.  The cred object holds
    the credentials of the subject performing the operation.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  
  */
  typedef int mpo_pipe_check_stat_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *pipelabel
  );
  /**
    @brief Access control check for pipe write
    @param cred Subject credential
    @param cpipe Object to be accessed
    @param pipelabel The label on the pipe
  
    Determine whether the subject identified by the credential can
    perform a write operation on the passed pipe.  The cred object holds
    the credentials of the subject performing the operation.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  
  */
  typedef int mpo_pipe_check_write_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *pipelabel
  );
  /**
    @brief Create a pipe label
    @param cred Subject credential
    @param cpipe object to be labeled
    @param label Label for the pipe object
  
    Create a label for the pipe object being created by the supplied
    user credential. This call is made when the pipe is being created
    XXXPIPE(for one or both sides of the pipe?).
  
  */
  typedef void mpo_pipe_label_associate_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *pipelabel
  );
  /**
    @brief Copy a pipe label
    @param src Source pipe label
    @param dest Destination pipe label
  
    Copy the pipe label associated with src to dest.
    XXXPIPE Describe when this is used: most likely during pipe creation to
            copy from rpipe to wpipe.
  */
  typedef void mpo_pipe_label_copy_t(
          struct label *src,
          struct label *dest
  );
  /**
    @brief Destroy pipe label
    @param label The label to be destroyed
  
    Destroy a pipe label.  Since the object is going out of scope,
    policy modules should free any internal storage associated with the
    label so that it may be destroyed.
  */
  typedef void mpo_pipe_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize a pipe label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of the label
  
    Produce an external representation of the label on a pipe.
    An externalized label consists of a text representation
    of the label contents that can be used with user applications.
    Policy-agnostic user space tools will display this externalized
    version.
  
    The policy's externalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, return non-zero if an error occurs while
    externalizing the label data.
  
  */
  typedef int mpo_pipe_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize pipe label
    @param label New label to initialize
  
    Initialize label storage for use with a newly instantiated pipe object.
    Sleeping is permitted.
  */
  typedef void mpo_pipe_label_init_t(
          struct label *label
  );
  /**
    @brief Internalize a pipe label
    @param label Label to be internalized
    @param element_name Name of the label namespace for which the label should
    be internalized
    @param element_data Text data to be internalized
  
    Produce a pipe label from an external representation.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will forward text version to the kernel for
    processing by individual policy modules.
  
    The policy's internalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, Otherwise, return non-zero if an error occurs
    while internalizing the label data.
  
  */
  typedef int mpo_pipe_label_internalize_t(
          struct label *label,
          char *element_name,
          char *element_data
  );
  /**
    @brief Update a pipe label
    @param cred Subject credential
    @param cpipe Object to be labeled
    @param oldlabel Existing pipe label
    @param newlabel New label to replace existing label
    @see mpo_pipe_check_label_update_t
  
    The subject identified by the credential has previously requested
    and was authorized to relabel the pipe; this entry point allows
    policies to perform the actual relabel operation.  Policies should
    update oldlabel using the label stored in the newlabel parameter.
  
  */
  typedef void mpo_pipe_label_update_t(
          kauth_cred_t cred,
          struct pipe *cpipe,
          struct label *oldlabel,
          struct label *newlabel
  );
  /**
    @brief Policy unload event
    @param mpc MAC policy configuration
  
    This is the MAC Framework policy unload event.  This entry point will
    only be called if the module's policy configuration allows unload (if
    the MPC_LOADTIME_FLAG_UNLOADOK is set).  Most security policies won't
    want to be unloaded; they should set their flags to prevent this
    entry point from being called.
  
    @warning During this call, the mac policy list mutex is held, so
    sleep operations cannot be performed, and calls out to other kernel
    subsystems must be made with caution.
  
    @see MPC_LOADTIME_FLAG_UNLOADOK
  */
  typedef void mpo_policy_destroy_t(
          struct mac_policy_conf *mpc
  );
  /**
    @brief Policy initialization event
    @param mpc MAC policy configuration
    @see mac_policy_register
    @see mpo_policy_initbsd_t
  
    This is the MAC Framework policy initialization event.  This entry
    point is called during mac_policy_register, when the policy module
    is first registered with the MAC Framework.  This is often done very
    early in the boot process, after the kernel Mach subsystem has been
    initialized, but prior to the BSD subsystem being initialized.
    Since the kernel BSD services are not yet available, it is possible
    that some initialization must occur later, possibly in the
    mpo_policy_initbsd_t policy entry point, such as registering BSD system
    controls (sysctls).  Policy modules loaded at boot time will be
    registered and initialized before labeled Mach objects are created.
  
    @warning During this call, the mac policy list mutex is held, so
    sleep operations cannot be performed, and calls out to other kernel
    subsystems must be made with caution.
  */
  typedef void mpo_policy_init_t(
          struct mac_policy_conf *mpc
  );
  /**
    @brief Policy BSD initialization event
    @param mpc MAC policy configuration
    @see mpo_policy_init_t
  
    This entry point is called after the kernel BSD subsystem has been
    initialized.  By this point, the module should already be loaded,
    registered, and initialized.  Since policy modules are initialized
    before kernel BSD services are available, this second initialization
    phase is necessary.  At this point, BSD services (memory management,
    synchronization primitives, vfs, etc.) are available, but the first
    process has not yet been created.  Mach-related objects and tasks
    will already be fully initialized and may be in use--policies requiring
    ubiquitous labeling may also want to implement mpo_policy_init_t.
  
    @warning During this call, the mac policy list mutex is held, so
    sleep operations cannot be performed, and calls out to other kernel
    subsystems must be made with caution.
  */
  typedef void mpo_policy_initbsd_t(
          struct mac_policy_conf *mpc
  );
  /**
    @brief Policy extension service
    @param p Calling process
    @param call Policy-specific syscall number
    @param arg Pointer to syscall arguments
  
    This entry point provides a policy-multiplexed system call so that
    policies may provide additional services to user processes without
    registering specific system calls. The policy name provided during
    registration is used to demux calls from userland, and the arguments
    will be forwarded to this entry point.  When implementing new
    services, security modules should be sure to invoke appropriate
    access control checks from the MAC framework as needed.  For
    example, if a policy implements an augmented signal functionality,
    it should call the necessary signal access control checks to invoke
    the MAC framework and other registered policies.
  
    @warning Since the format and contents of the policy-specific
    arguments are unknown to the MAC Framework, modules must perform the
    required copyin() of the syscall data on their own.  No policy
    mediation is performed, so policies must perform any necessary
    access control checks themselves.  If multiple policies are loaded,
    they will currently be unable to mediate calls to other policies.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_policy_syscall_t(
          struct proc *p,
          int call,
          user_addr_t arg
  );
  /**
    @brief Access control check for copying a send right to another task
    @param task Label of the sender task
    @param port Label of the affected port
  
    Access control check for copying send rights to the port from the
    specified task. A complementary entry point, mpo_port_check_hold_send,
    handles the receiving task. port_check_copy_send is called as part of
    a group of policy invocations when messages with port rights are sent.
    All access control checks made for a particular message must be successful
    for the message to be sent.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_copy_send_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for obtaining a receive right
    @param task Label of the receiving task
    @param port Label of the affected port
  
    Access control check for a task obtaining receive rights to a
    port. Usually, these are port rights that were obtained with a call
    to mach_port_allocate.  This entry point is called as part of a
    group of policy invocations when messages with port rights are
    received.  All of these access control checks must succeed in order
    to receive the message.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_hold_receive_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for obtaining a send once right
    @param task Label of the receiving task
    @param port Label of the affected port
  
    Access control check for a task obtaining send once rights to a port. Usually,
    these are port rights that were part of a message sent by another userspace
    task. port_check_hold_send_once is called as part of a group of policy
    invocations when messages with port rights are received. All of these access
    control checks must succeed in order to receive the message.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_hold_send_once_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for obtaining a send right
    @param task Label of the receiving task
    @param port Label of the affected port
  
    Access control check for a task obtaining send rights to a port. Usually,
    these are port rights that were part of a message sent by another userspace
    task. port_check_hold_send is called as part of a group of policy
    invocations when messages with port rights are received. All of these access
    control checks must succeed in order to receive the message.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_hold_send_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for relabelling ports
    @param task Subject's task label
    @param oldlabel Original label of port
    @param newlabel New label for port
  
    Access control check for relabelling ports. The policy should
    indicate whether the subject is permitted to change the label
    of a port from oldlabel to newlabel. The port is locked, but
    the subject's task label is not locked.
  
    @warning XXX In future releases, the task label lock will likely
    also be held.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_label_update_t(
          struct label *task,
          struct label *oldlabel,
          struct label *newlabel
  );
  /**
    @brief Access control check for producing a send once right from a receive right
    @param task Label of the sender task
    @param port Label of the affected port
  
    Access control check for obtaining send once rights from receive rights.
    The new send once right may be destined for the calling task, or a different
    task.  In either case the mpo_port_check_hold_send_once entry point handles
    the receiving task. port_check_make_send_once may be called as part of a
    group of policy invocations when messages with port rights are sent.
    All access control checks made for a particular message must be successful
    for the message to be sent.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_make_send_once_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for producing a send right from a receive right
    @param task Label of the sender task
    @param port Label of the affected port
  
    Access control check for obtaining send rights from receive rights. The new
    send right may be destined for the calling task, or a different task.
    In either case the mpo_port_check_hold_send entry point
    handles the receiving task. port_check_make_send may be called as part of
    a group of policy invocations when messages with port rights are sent.
    All access control checks made for a particular message must be successful
    for the message to be sent.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_make_send_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Compute access control check for a Mach message-based service
    @param proc Sender's process structure (may be NULL)
    @param task Sender's task label
    @param port Destination port label
    @param msgid Message id
  
    Access control computation for message-based services. This entry point
    computes permission to the service requested by the specified port and message
    id, for example a single MiG server routine, and is unrelated to the access
    check for sending messages to ports (but that check must succeed for the
    message to be sent to the destination). The result of this access computation
    is stored in the message trailer field msgh_ad (only if requested by the
    recipient); it does not actually inhibit the message from being sent or
    received.
  
    @return 0 for access granted, nonzero for access denied.
  */
  
  typedef int mpo_port_check_method_t(
          struct proc *proc,
          struct label *task,
          struct label *port,
          int msgid
  );
  /**
    @brief Access control check for transferring a receive right
    @param task Label of the sender task
    @param port Label of the affected port
  
    Access control check for transferring the receive right to a port out
    of the specified task. A complementary entry point,
    mpo_port_check_hold_receive, handles the receiving task.
    port_check_move_receive is called as part of
    a group of policy invocations when messages with port rights are sent.
    All access control checks made for a particular message must be successful
    for the message to be sent.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_move_receive_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for transferring a send once right
    @param task Label of the sender task
    @param port Label of the affected port
  
    Access control check for transferring a send once right from one task to
    the task listening to the specified port. A complementary entry point,
    mpo_port_check_hold_send_once, handles the receiving task.
    port_check_move_send_once is called as part of a group of policy invocations
    when messages with port rights are sent.  All access control checks made
    for a particular message must be successful for the message to be sent.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_move_send_once_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for transferring a send right
    @param task Label of the sender task
    @param port Label of the affected port
  
    Access control check for transferring a send right from one task to the
    task listening to the specified port. A complementary entry point,
    mpo_port_check_hold_send, handles the receiving task.
    port_check_move_send is called as part of a group of policy invocations
    when messages with port rights are sent.  All access control checks made
    for a particular message must be successful for the message to be sent.
  
    The task label and the port are locked. Sleeping is permitted.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_move_send_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Access control check for receiving Mach messsages
    @param task Label of the receiving task
    @param sender Label of the sending task
  
    Access control check for receiving messages. The two labels are locked.
  
    @warning This entry point can be invoked from many places inside the
    kernel, with arbitrary other locks held. The implementation of this
    entry point must not cause page faults, as those are handled by mach
    messages.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_receive_t(
          struct label *task,
          struct label *sender
  );
  /**
    @brief Access control check for sending Mach messsages
    @param task Label of the sender task
    @param port Label of the destination port
  
    Access control check for sending messages. The task label and the
    port are locked.
  
    @warning This entry point can be invoked from many places inside the
    kernel, with arbitrary other locks held. The implementation of this
    entry point must not cause page faults, as those are handled by mach
    messages.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_send_t(
          struct label *task,
          struct label *port
  );
  /**
    @brief Generic access control check
    @param subj Caller-provided subject label
    @param obj Caller-provided object label
    @param serv Service or object class name
    @param perm Permission, or method, within the specified service
  
    This function provides a general way for a user process to query
    an arbitrary access control decision from the system's security policies.
    Currently, there are no standards for the format of the service and
    permission names. Labels may be either cred or port labels; the policy
    must accept either. The userspace interfaces to this entry point allow
    label strings or label handles (ports) to be provided.
  
    @return Return 0 if access is granted, non-zero otherwise.
  */
  typedef int mpo_port_check_service_t(
          struct label *subj,
          struct label *obj,
          const char *serv,
          const char *perm
  );
  /**
    @brief Assign a label to a new Mach port created by the kernel
    @param portlabel Label for the new port
    @param isreply True if the port is for a reply message from the kernel
  
    Assign a label to a new port created by the kernel. If the port is being
    used to reply to a message, isreply is 1 (0 otherwise). The port is locked.
  */
  typedef void mpo_port_label_associate_kernel_t(
          struct label *portlabel,
          int isreply
  );
  /**
    @brief Assign a label to a new Mach port
    @param it Task label of issuer
    @param st Task label of target
    @param portlabel Label for the new port
  
    Assign a label to a new port. The policy can base this label on
    the label of the calling task, as well as the label of the target task.
    The target task is the one which recieves the first right for this port.
    Both task labels and the port are locked.
  */
  typedef void mpo_port_label_associate_t(
          struct label *it,
          struct label *st,
          struct label *portlabel
  );
  /**
    @brief Request label for new (userspace) object
    @param subj Subject label
    @param obj Parent or existing object label
    @param serv Name of service
    @param out Computed label
  
    Ask the loaded policies to compute a label based on the two input labels
    and the service name. There is currently no standard for the service name,
    or even what the input labels represent (Subject and parent object are only
    a suggestion). If successful, the computed label is stored in out. All labels
    must be port (or task) labels. The userspace interfaces to this entry point
    allow label handles (ports) to be provided.
  
    @return 0 on success, or an errno value for failure.
  */
  typedef int mpo_port_label_compute_t(
          struct label *subj,
          struct label *obj,
          const char *serv,
          struct label *out
  );
  /**
    @brief Copy a Mach port label
    @param src Source port label
    @param dest Destination port label
  
    Copy the Mach port label information from src to dest.  This is used
    to copy user-suplied labels into an existing port.
  */
  typedef void mpo_port_label_copy_t(
          struct label *src,
          struct label *dest
  );
  /**
    @brief Destroy Mach port label
    @param label The label to be destroyed
  
    Destroy a Mach port label.  Since the object is going out of
    scope, policy modules should free any internal storage associated
    with the label so that it may be destroyed.
  */
  typedef void mpo_port_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize Mach port label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated Mach port.  Sleeping
    is permitted.
  */
  typedef void mpo_port_label_init_t(
          struct label *label
  );
  /**
    @brief Update a Mach task port label
    @param cred User credential label to be used as the source
    @param task Mach port label to be used as the destination
    @see mpo_cred_label_update_t
    @see mpo_cred_label_update_execve_t
  
    Update the label on a Mach task port, using the supplied user
    credential label. When a mac_cred_label_update_execve or a mac_cred_label_update
    operation causes the label on a user credential to change, the Mach
    task port label also needs to be updated to reflect the change.
    Both labels are already valid (initialized and created).
  */
  typedef void mpo_port_label_update_cred_t(
          struct label *cred,
          struct label *task
  );
  /**
    @brief Assign a label to a Mach port connected to a kernel object
    @param portlabel Label for the port
    @param kotype Type of kernel object
  
    Label a kernel port based on the type of object behind it. The
    kotype parameter is one of the IKOT constants in
    <kern/ipc_kobject.h>. The port already has a valid label from either
    mpo_port_label_associate_kernel, or because it is a task port and has a label
    derived from the process and task labels. The port is locked.
  */
  typedef void mpo_port_label_update_kobject_t(
          struct label *portlabel,
          int kotype
  );
  /**
    @brief Access control check for POSIX semaphore create
    @param cred Subject credential
    @param name String name of the semaphore
  
    Determine whether the subject identified by the credential can create
    a POSIX semaphore specified by name.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixsem_check_create_t(
          kauth_cred_t cred,
          const char *name
  );
  /**
    @brief Access control check for POSIX semaphore open
    @param cred Subject credential
    @param ps Pointer to semaphore information structure
    @param semlabel Label associated with the semaphore
  
    Determine whether the subject identified by the credential can open
    the named POSIX semaphore with label semlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixsem_check_open_t(
          kauth_cred_t cred,
          struct pseminfo *ps,
          struct label *semlabel
  );
  /**
    @brief Access control check for POSIX semaphore post
    @param cred Subject credential
    @param ps Pointer to semaphore information structure
    @param semlabel Label associated with the semaphore
  
    Determine whether the subject identified by the credential can unlock
    the named POSIX semaphore with label semlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixsem_check_post_t(
          kauth_cred_t cred,
          struct pseminfo *ps,
          struct label *semlabel
  );
  /**
    @brief Access control check for POSIX semaphore unlink
    @param cred Subject credential
    @param ps Pointer to semaphore information structure
    @param semlabel Label associated with the semaphore
    @param name String name of the semaphore
  
    Determine whether the subject identified by the credential can remove
    the named POSIX semaphore with label semlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixsem_check_unlink_t(
          kauth_cred_t cred,
          struct pseminfo *ps,
          struct label *semlabel,
          const char *name
  );
  /**
    @brief Access control check for POSIX semaphore wait
    @param cred Subject credential
    @param ps Pointer to semaphore information structure
    @param semlabel Label associated with the semaphore
  
    Determine whether the subject identified by the credential can lock
    the named POSIX semaphore with label semlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixsem_check_wait_t(
          kauth_cred_t cred,
          struct pseminfo *ps,
          struct label *semlabel
  );
  /**
    @brief Create a POSIX semaphore label
    @param cred Subject credential
    @param ps Pointer to semaphore information structure
    @param semlabel Label to associate with the new semaphore
    @param name String name of the semaphore
  
    Label a new POSIX semaphore.  The label was previously
    initialized and associated with the semaphore.  At this time, an
    appropriate initial label value should be assigned to the object and
    stored in semalabel.
  */
  typedef void mpo_posixsem_label_associate_t(
          kauth_cred_t cred,
          struct pseminfo *ps,
          struct label *semlabel,
          const char *name
  );
  /**
    @brief Destroy POSIX semaphore label
    @param label The label to be destroyed
  
    Destroy a POSIX semaphore label.  Since the object is
    going out of scope, policy modules should free any internal storage
    associated with the label so that it may be destroyed.
  */
  typedef void mpo_posixsem_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize POSIX semaphore label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated POSIX semaphore. Sleeping
    is permitted.
  */
  typedef void mpo_posixsem_label_init_t(
          struct label *label
  );
  /**
    @brief Access control check for POSIX shared memory region create
    @param cred Subject credential
    @param name String name of the shared memory region
  
    Determine whether the subject identified by the credential can create
    the POSIX shared memory region referenced by name.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixshm_check_create_t(
          kauth_cred_t cred,
          const char *name
  );
  /**
    @brief Access control check for mapping POSIX shared memory
    @param cred Subject credential
    @param ps Pointer to shared memory information structure
    @param shmlabel Label associated with the shared memory region
    @param prot mmap protections; see mmap(2)
    @param flags shmat flags; see shmat(2)
  
    Determine whether the subject identified by the credential can map
    the POSIX shared memory segment associated with shmlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixshm_check_mmap_t(
          kauth_cred_t cred,
          struct pshminfo *ps,
          struct label *shmlabel,
          int prot,
          int flags
  );
  /**
    @brief Access control check for POSIX shared memory region open
    @param cred Subject credential
    @param ps Pointer to shared memory information structure
    @param shmlabel Label associated with the shared memory region
  
    Determine whether the subject identified by the credential can open
    the POSIX shared memory region.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixshm_check_open_t(
          kauth_cred_t cred,
          struct pshminfo *ps,
          struct label *shmlabel
  );
  /**
    @brief Access control check for POSIX shared memory stat
    @param cred Subject credential
    @param ps Pointer to shared memory information structure
    @param shmlabel Label associated with the shared memory region
  
    Determine whether the subject identified by the credential can obtain
    status for the POSIX shared memory segment associated with shmlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixshm_check_stat_t(
          kauth_cred_t cred,
          struct pshminfo *ps,
          struct label *shmlabel
  );
  /**
    @brief Access control check for POSIX shared memory truncate
    @param cred Subject credential
    @param ps Pointer to shared memory information structure
    @param shmlabel Label associated with the shared memory region
    @param len Length to truncate or extend shared memory segment
  
    Determine whether the subject identified by the credential can truncate
    or extend (to len) the POSIX shared memory segment associated with shmlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixshm_check_truncate_t(
          kauth_cred_t cred,
          struct pshminfo *ps,
          struct label *shmlabel,
          size_t len
  );
  /**
    @brief Access control check for POSIX shared memory unlink
    @param cred Subject credential
    @param ps Pointer to shared memory information structure
    @param shmlabel Label associated with the shared memory region
    @param name String name of the shared memory region
  
    Determine whether the subject identified by the credential can delete
    the POSIX shared memory segment associated with shmlabel.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_posixshm_check_unlink_t(
          kauth_cred_t cred,
          struct pshminfo *ps,
          struct label *shmlabel,
          const char *name
  );
  /**
    @brief Create a POSIX shared memory region label
    @param cred Subject credential
    @param ps Pointer to shared memory information structure
    @param shmlabel Label to associate with the new shared memory region
    @param name String name of the shared memory region
  
    Label a new POSIX shared memory region.  The label was previously
    initialized and associated with the shared memory region.  At this
    time, an appropriate initial label value should be assigned to the
    object and stored in shmlabel.
  */
  typedef void mpo_posixshm_label_associate_t(
          kauth_cred_t cred,
          struct pshminfo *ps,
          struct label *shmlabel,
          const char *name
  );
  /**
    @brief Destroy POSIX shared memory label
    @param label The label to be destroyed
  
    Destroy a POSIX shared memory region label.  Since the
    object is going out of scope, policy modules should free any
    internal storage associated with the label so that it may be
    destroyed.
  */
  typedef void mpo_posixshm_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize POSIX Shared Memory region label
    @param label New label to initialize
  
    Initialize the label for newly a instantiated POSIX Shared Memory
    region. Sleeping is permitted.
  */
  typedef void mpo_posixshm_label_init_t(
          struct label *label
  );
  /**
    @brief Access control check for debugging process
    @param cred Subject credential
    @param proc Object process
  
    Determine whether the subject identified by the credential can debug
    the passed process. This call may be made in a number of situations,
    including use of the ptrace(2) and ktrace(2) APIs, as well as for some
    types of procfs operations.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch,
    EPERM for lack of privilege, or ESRCH to hide visibility of the target.
  */
  typedef int mpo_proc_check_debug_t(
          kauth_cred_t cred,
          struct proc *proc
  );
  /**
    @brief Access control over fork
    @param cred Subject credential
    @param proc Subject process trying to fork
  
    Determine whether the subject identified is allowed to fork.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_fork_t(
          kauth_cred_t cred,
          struct proc *proc
  );
  /**
    @brief Access control check for retrieving audit information
    @param cred Subject credential
  
    Determine whether the subject identified by the credential can get
    audit information such as the audit user ID, the preselection mask,
    the terminal ID and the audit session ID, using the getaudit() system call.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_getaudit_t(
          kauth_cred_t cred
  );
  /**
    @brief Access control check for retrieving audit user ID
    @param cred Subject credential
  
    Determine whether the subject identified by the credential can get
    the user identity being used by the auditing system, using the getauid()
    system call.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_getauid_t(
          kauth_cred_t cred
  );
  /**
    @brief Access control check for retrieving Login Context ID
    @param p0 Calling process
    @param p Effected process
    @param pid syscall PID argument
  
    Determine if getlcid(2) system call is permitted.
  
    Information returned by this system call is similar to that returned via
    process listings etc.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_getlcid_t(
          struct proc *p0,
          struct proc *p,
          pid_t pid
  );
  /**
    @brief Access control check for setting memory protections
    @param cred Subject credential
    @param proc User process requesting the change
    @param addr Start address of the memory range
    @param size Length address of the memory range
    @param prot Memory protections, see mmap(2)
  
    Determine whether the subject identified by the credential should
    be allowed to set the specified memory protections on memory mapped
    in the process proc.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_mprotect_t(
          kauth_cred_t cred,
          struct proc *proc,
          user_addr_t addr,
          user_size_t size,
          int prot
  );
  /**
    @brief Access control check for changing scheduling parameters
    @param cred Subject credential
    @param proc Object process
  
    Determine whether the subject identified by the credential can change
    the scheduling parameters of the passed process.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch,
    EPERM for lack of privilege, or ESRCH to limit visibility.
  */
  typedef int mpo_proc_check_sched_t(
          kauth_cred_t cred,
          struct proc *proc
  );
  /**
    @brief Access control check for setting audit information
    @param cred Subject credential
    @param ai Audit information
  
    Determine whether the subject identified by the credential can set
    audit information such as the the preselection mask, the terminal ID
    and the audit session ID, using the setaudit() system call.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_setaudit_t(
          kauth_cred_t cred,
          struct auditinfo_addr *ai
  );
  /**
    @brief Access control check for setting audit user ID
    @param cred Subject credential
    @param auid Audit user ID
  
    Determine whether the subject identified by the credential can set
    the user identity used by the auditing system, using the setauid()
    system call.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_setauid_t(
          kauth_cred_t cred,
          uid_t auid
  );
  /**
    @brief Access control check for setting the Login Context
    @param p0 Calling process
    @param p Effected process
    @param pid syscall PID argument
    @param lcid syscall LCID argument
  
    Determine if setlcid(2) system call is permitted.
  
    See xnu/bsd/kern/kern_prot.c:setlcid() implementation for example of
    decoding syscall arguments to determine action desired by caller.
  
    Five distinct actions are possible: CREATE JOIN LEAVE ADOPT ORPHAN
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_setlcid_t(
          struct proc *p0,
          struct proc *p,
          pid_t pid,
          pid_t lcid
  );
  /**
    @brief Access control check for delivering signal
    @param cred Subject credential
    @param proc Object process
    @param signum Signal number; see kill(2)
  
    Determine whether the subject identified by the credential can deliver
    the passed signal to the passed process.
  
    @warning Programs typically expect to be able to send and receive
    signals as part or their normal process lifecycle; caution should be
    exercised when implementing access controls over signal events.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch,
    EPERM for lack of privilege, or ESRCH to limit visibility.
  */
  typedef int mpo_proc_check_signal_t(
          kauth_cred_t cred,
          struct proc *proc,
          int signum
  );
  /**
    @brief Access control check for wait
    @param cred Subject credential
    @param proc Object process
  
    Determine whether the subject identified by the credential can wait
    for process termination.
  
    @warning Caution should be exercised when implementing access
    controls for wait, since programs often wait for child processes to
    exit.  Failure to be notified of a child process terminating may
    cause the parent process to hang, or may produce zombie processes.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_proc_check_wait_t(
          kauth_cred_t cred,
          struct proc *proc
  );
  /**
    @brief Destroy process label
    @param label The label to be destroyed
  
    Destroy a process label.  Since the object is going
    out of scope, policy modules should free any internal storage
    associated with the label so that it may be destroyed.
  */
  typedef void mpo_proc_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize process label
    @param label New label to initialize
    @see mpo_cred_label_init_t
  
    Initialize the label for a newly instantiated BSD process structure.
    Normally, security policies will store the process label in the user
    credential rather than here in the process structure.  However,
    there are some floating label policies that may need to temporarily
    store a label in the process structure until it is safe to update
    the user credential label.  Sleeping is permitted.
  */
  typedef void mpo_proc_label_init_t(
          struct label *label
  );
  /**
    @brief Access control check for socket accept
    @param cred Subject credential
    @param socket Object socket
    @param socklabel Policy label for socket
  
    Determine whether the subject identified by the credential can accept()
    a new connection on the socket from the host specified by addr.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_accept_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel
  );
  /**
    @brief Access control check for a pending socket accept
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for socket
    @param addr Address of the listening socket (coming soon)
  
    Determine whether the subject identified by the credential can accept()
    a pending connection on the socket from the host specified by addr.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_accepted_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel,
          struct sockaddr *addr
  );
  /**
    @brief Access control check for socket bind
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for socket
    @param addr Name to assign to the socket
  
    Determine whether the subject identified by the credential can bind()
    the name (addr) to the socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_bind_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel,
          struct sockaddr *addr
  );
  /**
    @brief Access control check for socket connect
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for socket
    @param addr Name to assign to the socket
  
    Determine whether the subject identified by the credential can
    connect() the passed socket to the remote host specified by addr.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_connect_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel,
          struct sockaddr *addr
  );
  /**
    @brief Access control check for socket() system call.
    @param cred Subject credential
    @param domain communication domain
    @param type socket type
    @param protocol socket protocol
  
    Determine whether the subject identified by the credential can
    make the socket() call.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_create_t(
          kauth_cred_t cred,
          int domain,
          int type,
          int protocol
  );
  /**
    @brief Access control check for delivering data to a user's receieve queue
    @param so The socket data is being delivered to
    @param so_label The label of so
    @param m The mbuf whose data will be deposited into the receive queue
    @param m_label The label of the sender of the data.
  
    A socket has a queue for receiving incoming data.  When a packet arrives
    on the wire, it eventually gets deposited into this queue, which the
    owner of the socket drains when they read from the socket's file descriptor.
  
    This function determines whether the socket can receive data from
    the sender specified by m_label.
  
    @warning There is an outstanding design issue surrounding the placement
    of this function.  The check must be placed either before or after the
    TCP sequence and ACK counters are updated.  Placing the check before
    the counters are updated causes the incoming packet to be resent by
    the remote if the check rejects it.  Placing the check after the counters
    are updated results in a completely silent drop.  As far as each TCP stack
    is concerned the packet was received, however, the data will not be in the
    socket's receive queue.  Another consideration is that the current design
    requires using the "failed label" occasionally.  In that case, on rejection,
    we want the remote TCP to resend the data.  Because of this, we chose to
    place this check before the counters are updated, so rejected packets will be
    resent by the remote host.
  
    If a policy keeps rejecting the same packet, eventually the connection will
    be dropped.  Policies have several options if this design causes problems.
    For example, one options is to sanitize the mbuf such that it is acceptable,
    then accept it.  That may require negotiation between policies as the
    Framework will not know to re-check the packet.
  
    The policy must handle NULL MBUF labels.  This will likely be the case
    for non-local TCP sockets for example.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_deliver_t(
          socket_t so,
          struct label *so_label,
          struct mbuf *m,
          struct label *m_label
  );
  /**
    @brief Access control check for socket kqfilter
    @param cred Subject credential
    @param kn Object knote
    @param so Object socket
    @param socklabel Policy label for socket
  
    Determine whether the subject identified by the credential can
    receive the knote on the passed socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_kqfilter_t(
          kauth_cred_t cred,
          struct knote *kn,
          socket_t so,
          struct label *socklabel
  );
  /**
    @brief Access control check for socket relabel
    @param cred Subject credential
    @param so Object socket
    @param so_label The current label of so
    @param newlabel The label to be assigned to so
  
    Determine whether the subject identified by the credential can
    change the label on the socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_label_update_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *so_label,
          struct label *newlabel
  );
  /**
    @brief Access control check for socket listen
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for socket
  
    Determine whether the subject identified by the credential can
    listen() on the passed socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_listen_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel
  );
  /**
    @brief Access control check for socket receive
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for socket
  
    Determine whether the subject identified by the credential can
    receive data from the socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_receive_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel
  );
  
  /**                                                                                               
    @brief Access control check for socket receive                                                  
    @param cred Subject credential                                                                  
    @param socket Object socket                                                                     
    @param socklabel Policy label for socket                                                        
    @param addr Name of the remote socket                                                           
                                                                                                    
    Determine whether the subject identified by the credential can                                  
    receive data from the remote host specified by addr.                                            
                                                                                                    
    @return Return 0 if access if granted, otherwise an appropriate                                 
    value for errno should be returned.                                                             
  */
  typedef int mpo_socket_check_received_t(
                                          kauth_cred_t cred,
                                          struct socket *sock,
                                          struct label *socklabel,
                                          struct sockaddr *saddr
                                          );
  
  
  /**
    @brief Access control check for socket select
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for socket
    @param which The operation selected on: FREAD or FWRITE
  
    Determine whether the subject identified by the credential can use the
    socket in a call to select().
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_select_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel,
          int which
  );
  /**
    @brief Access control check for socket send
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for socket
    @param addr Address being sent to
  
    Determine whether the subject identified by the credential can send
    data to the socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_send_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel,
          struct sockaddr *addr
  );
  /**
    @brief Access control check for retrieving socket status
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for so
  
    Determine whether the subject identified by the credential can
    execute the stat() system call on the given socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_stat_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel
  );
  /**
    @brief Access control check for setting socket options
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for so
    @param sopt The options being set
  
    Determine whether the subject identified by the credential can
    execute the setsockopt system call on the given socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_setsockopt_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel,
          struct sockopt *sopt
  );
  /**
    @brief Access control check for getting socket options
    @param cred Subject credential
    @param so Object socket
    @param socklabel Policy label for so
    @param sopt The options to get
  
    Determine whether the subject identified by the credential can
    execute the getsockopt system call on the given socket.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_socket_check_getsockopt_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *socklabel,
          struct sockopt *sopt
  );
  /**
    @brief Label a socket
    @param oldsock Listening socket
    @param oldlabel Policy label associated with oldsock
    @param newsock New socket
    @param newlabel Policy label associated with newsock
  
    A new socket is created when a connection is accept(2)ed.  This
    function labels the new socket based on the existing listen(2)ing
    socket.
  */
  typedef void mpo_socket_label_associate_accept_t(
          socket_t oldsock,
          struct label *oldlabel,
          socket_t newsock,
          struct label *newlabel
  );
  /**
    @brief Assign a label to a new socket
    @param cred Credential of the owning process
    @param so The socket being labeled
    @param solabel The label
    @warning cred can be NULL
  
    Set the label on a newly created socket from the passed subject
    credential.  This call is made when a socket is created.  The
    credentials may be null if the socket is being created by the
    kernel.
  */
  typedef void mpo_socket_label_associate_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *solabel
  );
  /**
    @brief Copy a socket label
    @param src Source label
    @param dest Destination label
  
    Copy the socket label information in src into dest.
  */
  typedef void mpo_socket_label_copy_t(
          struct label *src,
          struct label *dest
  );
  /**
    @brief Destroy socket label
    @param label The label to be destroyed
  
    Destroy a socket label.  Since the object is going out of
    scope, policy modules should free any internal storage associated
    with the label so that it may be destroyed.
  */
  typedef void mpo_socket_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize a socket label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of label
  
    Produce an externalized socket label based on the label structure passed.
    An externalized label consists of a text representation of the label
    contents that can be used with userland applications and read by the
    user.  If element_name does not match a namespace managed by the policy,
    simply return 0. Only return nonzero if an error occurs while externalizing
    the label data.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_socket_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize socket label
    @param label New label to initialize
    @param waitok Malloc flags
  
    Initialize the label of a newly instantiated socket.  The waitok
    field may be one of M_WAITOK and M_NOWAIT, and should be employed to
    avoid performing a sleeping malloc(9) during this initialization
    call.  It it not always safe to sleep during this entry point.
  
    @warning Since it is possible for the waitok flags to be set to
    M_NOWAIT, the malloc operation may fail.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_socket_label_init_t(
          struct label *label,
          int waitok
  );
  /**
    @brief Internalize a socket label
    @param label Label to be filled in
    @param element_name Name of the label namespace for which the label should
    be internalized
    @param element_data Text data to be internalized
  
    Produce an internal socket label structure based on externalized label
    data in text format.
  
    The policy's internalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_socket_label_internalize_t(
          struct label *label,
          char *element_name,
          char *element_data
  );
  /**
    @brief Relabel socket
    @param cred Subject credential
    @param so Object; socket
    @param so_label Current label of the socket
    @param newlabel The label to be assigned to so
  
    The subject identified by the credential has previously requested
    and was authorized to relabel the socket; this entry point allows
    policies to perform the actual label update operation.
  
    @warning XXX This entry point will likely change in future versions.
  */
  typedef void mpo_socket_label_update_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *so_label,
          struct label *newlabel
  );
  /**
    @brief Set the peer label on a socket from mbuf
    @param m Mbuf chain received on socket so
    @param m_label Label for m
    @param so Current label for the socket
    @param so_label Policy label to be filled out for the socket
  
    Set the peer label of a socket based on the label of the sender of the
    mbuf.
  
    This is called for every TCP/IP packet received.  The first call for a given
    socket operates on a newly initialized label, and subsequent calls operate
    on existing label data.
  
    @warning Because this can affect performance significantly, it has
    different sematics than other 'set' operations.  Typically, 'set' operations
    operate on newly initialzed labels and policies do not need to worry about
    clobbering existing values.  In this case, it is too inefficient to
    initialize and destroy a label every time data is received for the socket.
    Instead, it is up to the policies to determine how to replace the label data.
    Most policies should be able to replace the data inline.
  */
  typedef void mpo_socketpeer_label_associate_mbuf_t(
          struct mbuf *m,
          struct label *m_label,
          socket_t so,
          struct label *so_label
  );
  /**
    @brief Set the peer label on a socket from socket
    @param source Local socket
    @param sourcelabel Policy label for source
    @param target Peer socket
    @param targetlabel Policy label to fill in for target
  
    Set the peer label on a stream UNIX domain socket from the passed
    remote socket endpoint. This call will be made when the socket pair
    is connected, and will be made for both endpoints.
  
    Note that this call is only made on connection; it is currently not updated
    during communication.
  */
  typedef void mpo_socketpeer_label_associate_socket_t(
          socket_t source,
          struct label *sourcelabel,
          socket_t target,
          struct label *targetlabel
  );
  /**
    @brief Destroy socket peer label
    @param label The peer label to be destroyed
  
    Destroy a socket peer label.  Since the object is going out of
    scope, policy modules should free any internal storage associated
    with the label so that it may be destroyed.
  */
  typedef void mpo_socketpeer_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize a socket peer label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of label
  
    Produce an externalized socket peer label based on the label structure
    passed. An externalized label consists of a text representation of the
    label contents that can be used with userland applications and read by the
    user.  If element_name does not match a namespace managed by the policy,
    simply return 0. Only return nonzero if an error occurs while externalizing
    the label data.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_socketpeer_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize socket peer label
    @param label New label to initialize
    @param waitok Malloc flags
  
    Initialize the peer label of a newly instantiated socket.  The
    waitok field may be one of M_WAITOK and M_NOWAIT, and should be
    employed to avoid performing a sleeping malloc(9) during this
    initialization call.  It it not always safe to sleep during this
    entry point.
  
    @warning Since it is possible for the waitok flags to be set to
    M_NOWAIT, the malloc operation may fail.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_socketpeer_label_init_t(
          struct label *label,
          int waitok
  );
  /**
    @brief Access control check for enabling accounting
    @param cred Subject credential
    @param vp Accounting file
    @param vlabel Label associated with vp
  
    Determine whether the subject should be allowed to enable accounting,
    based on its label and the label of the accounting log file.  See
    acct(5) for more information.
  
    As accounting is disabled by passing NULL to the acct(2) system call,
    the policy should be prepared for both 'vp' and 'vlabel' to be NULL.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_acct_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Access control check for audit
    @param cred Subject credential
    @param record Audit record
    @param length Audit record length
  
    Determine whether the subject identified by the credential can submit
    an audit record for inclusion in the audit log via the audit() system call.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_audit_t(
          kauth_cred_t cred,
          void *record,
          int length
  );
  /**
    @brief Access control check for controlling audit
    @param cred Subject credential
    @param vp Audit file
    @param vl Label associated with vp
  
    Determine whether the subject should be allowed to enable auditing using
    the auditctl() system call, based on its label and the label of the proposed
    audit file.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_auditctl_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vl
  );
  /**
    @brief Access control check for manipulating auditing
    @param cred Subject credential
    @param cmd Audit control command
  
    Determine whether the subject identified by the credential can perform
    the audit subsystem control operation cmd via the auditon() system call.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_auditon_t(
          kauth_cred_t cred,
          int cmd
  );
  /**
    @brief Access control check for obtaining the host control port
    @param cred Subject credential
  
    Determine whether the subject identified by the credential can
    obtain the host control port.
  
    @return Return 0 if access is granted, or non-zero otherwise.
  */
  typedef int mpo_system_check_host_priv_t(
          kauth_cred_t cred
  );
  /**
    @brief Access control check for calling NFS services
    @param cred Subject credential
  
    Determine whether the subject identified by the credential should be
    allowed to call nfssrv(2).
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_nfsd_t(
          kauth_cred_t cred
  );
  /**
    @brief Access control check for reboot
    @param cred Subject credential
    @param howto howto parameter from reboot(2)
  
    Determine whether the subject identified by the credential should be
    allowed to reboot the system in the specified manner.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_reboot_t(
          kauth_cred_t cred,
          int howto
  );
  /**
    @brief Access control check for setting system clock
    @param cred Subject credential
  
    Determine whether the subject identified by the credential should be
    allowed to set the system clock.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_settime_t(
          kauth_cred_t cred
  );
  /**
    @brief Access control check for removing swap devices
    @param cred Subject credential
    @param vp Swap device
    @param label Label associated with vp
  
    Determine whether the subject identified by the credential should be
    allowed to remove vp as a swap device.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_swapoff_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for adding swap devices
    @param cred Subject credential
    @param vp Swap device
    @param label Label associated with vp
  
    Determine whether the subject identified by the credential should be
    allowed to add vp as a swap device.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_swapon_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for sysctl
    @param cred Subject credential
    @param name Integer name; see sysctl(3)
    @param namelen Length of name array of integers; see sysctl(3)
    @param old 0 or address where to store old value; see sysctl(3)
    @param oldlenp Pointer to length of old buffer; see sysctl(3)
    @param inkernel Boolean; 1 if called from kernel
    @param newvalue 0 or address of new value; see sysctl(3)
    @param newlen Length of new buffer; see sysctl(3)
  
    Determine whether the subject identified by the credential should be
    allowed to make the specified sysctl(3) transaction.
  
    The sysctl(3) call specifies that if the old value is not desired,
    oldp and oldlenp should be set to NULL.  Likewise, if a new value is
    not to be set, newp should be set to NULL and newlen set to 0.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_system_check_sysctl_t(
          kauth_cred_t cred,
          int *name,
          u_int namelen,
          user_addr_t old,        /* NULLOK */
          user_addr_t oldlenp,    /* NULLOK */
          int inkernel,
          user_addr_t newvalue,   /* NULLOK */
          size_t newlen
  );
  /**
    @brief Create a System V message label
    @param cred Subject credential
    @param msqkptr The message queue the message will be placed in
    @param msqlabel The label of the message queue
    @param msgptr The message
    @param msglabel The label of the message
  
    Label the message as its placed in the message queue.
  */
  typedef void mpo_sysvmsg_label_associate_t(
          kauth_cred_t cred,
          struct msqid_kernel *msqptr,
          struct label *msqlabel,
          struct msg *msgptr,
          struct label *msglabel
  );
  /**
    @brief Destroy System V message label
    @param label The label to be destroyed
  
    Destroy a System V message label.  Since the object is
    going out of scope, policy modules should free any internal storage
    associated with the label so that it may be destroyed.
  */
  typedef void mpo_sysvmsg_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize System V message label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated System V message.
  */
  typedef void mpo_sysvmsg_label_init_t(
          struct label *label
  );
  /**
    @brief Clean up a System V message label
    @param label The label to be destroyed
  
    Clean up a System V message label.  Darwin pre-allocates
    messages at system boot time and re-uses them rather than
    allocating new ones.  Before messages are returned to the "free
    pool", policies can cleanup or overwrite any information present in
    the label.
  */
  typedef void mpo_sysvmsg_label_recycle_t(
          struct label *label
  );
  /**
    @brief Access control check for System V message enqueuing
    @param cred Subject credential
    @param msgptr The message
    @param msglabel The message's label
    @param msqkptr The message queue
    @param msqlabel The message queue's label
  
    Determine whether the subject identified by the credential can add the
    given message to the given message queue.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvmsq_check_enqueue_t(
          kauth_cred_t cred,
          struct msg *msgptr,
          struct label *msglabel,
          struct msqid_kernel *msqptr,
          struct label *msqlabel
  );
  /**
    @brief Access control check for System V message reception
    @param cred The credential of the intended recipient
    @param msgptr The message
    @param msglabel The message's label
  
    Determine whether the subject identified by the credential can receive
    the given message.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvmsq_check_msgrcv_t(
          kauth_cred_t cred,
          struct msg *msgptr,
          struct label *msglabel
  );
  /**
    @brief Access control check for System V message queue removal
    @param cred The credential of the caller
    @param msgptr The message
    @param msglabel The message's label
  
    System V message queues are removed using the msgctl() system call.
    The system will iterate over each messsage in the queue, calling this
    function for each, to determine whether the caller has the appropriate
    credentials.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvmsq_check_msgrmid_t(
          kauth_cred_t cred,
          struct msg *msgptr,
          struct label *msglabel
  );
  /**
    @brief Access control check for msgctl()
    @param cred The credential of the caller
    @param msqptr The message queue
    @param msqlabel The message queue's label
  
    This access check is performed to validate calls to msgctl().
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvmsq_check_msqctl_t(
          kauth_cred_t cred,
          struct msqid_kernel *msqptr,
          struct label *msqlabel,
          int cmd
  );
  /**
    @brief Access control check to get a System V message queue
    @param cred The credential of the caller
    @param msqptr The message queue requested
    @param msqlabel The message queue's label
  
    On a call to msgget(), if the queue requested already exists,
    and it is a public queue, this check will be performed before the
    queue's ID is returned to the user.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvmsq_check_msqget_t(
          kauth_cred_t cred,
          struct msqid_kernel *msqptr,
          struct label *msqlabel
  );
  /**
    @brief Access control check to receive a System V message from the given queue
    @param cred The credential of the caller
    @param msqptr The message queue to receive from
    @param msqlabel The message queue's label
  
    On a call to msgrcv(), this check is performed to determine whether the
    caller has receive rights on the given queue.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvmsq_check_msqrcv_t(
          kauth_cred_t cred,
          struct msqid_kernel *msqptr,
          struct label *msqlabel
  );
  /**
    @brief Access control check to send a System V message to the given queue
    @param cred The credential of the caller
    @param msqptr The message queue to send to
    @param msqlabel The message queue's label
  
    On a call to msgsnd(), this check is performed to determine whether the
    caller has send rights on the given queue.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvmsq_check_msqsnd_t(
          kauth_cred_t cred,
          struct msqid_kernel *msqptr,
          struct label *msqlabel
  );
  /**
    @brief Create a System V message queue label
    @param cred Subject credential
    @param msqkptr The message queue
    @param msqlabel The label of the message queue
  
  */
  typedef void mpo_sysvmsq_label_associate_t(
          kauth_cred_t cred,
          struct msqid_kernel *msqptr,
          struct label *msqlabel
  );
  /**
    @brief Destroy System V message queue label
    @param label The label to be destroyed
  
    Destroy a System V message queue label.  Since the object is
    going out of scope, policy modules should free any internal storage
    associated with the label so that it may be destroyed.
  */
  typedef void mpo_sysvmsq_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize System V message queue label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated System V message queue.
  */
  typedef void mpo_sysvmsq_label_init_t(
          struct label *label
  );
  /**
    @brief Clean up a System V message queue label
    @param label The label to be destroyed
  
    Clean up a System V message queue label.  Darwin pre-allocates
    message queues at system boot time and re-uses them rather than
    allocating new ones.  Before message queues are returned to the "free
    pool", policies can cleanup or overwrite any information present in
    the label.
  */
  typedef void mpo_sysvmsq_label_recycle_t(
          struct label *label
  );
  /**
    @brief Access control check for System V semaphore control operation
    @param cred Subject credential
    @param semakptr Pointer to semaphore identifier
    @param semaklabel Label associated with semaphore
    @param cmd Control operation to be performed; see semctl(2)
  
    Determine whether the subject identified by the credential can perform
    the operation indicated by cmd on the System V semaphore semakptr.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvsem_check_semctl_t(
          kauth_cred_t cred,
          struct semid_kernel *semakptr,
          struct label *semaklabel,
          int cmd
  );
  /**
    @brief Access control check for obtaining a System V semaphore
    @param cred Subject credential
    @param semakptr Pointer to semaphore identifier
    @param semaklabel Label to associate with the semaphore
  
    Determine whether the subject identified by the credential can
    obtain a System V semaphore.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvsem_check_semget_t(
          kauth_cred_t cred,
          struct semid_kernel *semakptr,
          struct label *semaklabel
  );
  /**
    @brief Access control check for System V semaphore operations
    @param cred Subject credential
    @param semakptr Pointer to semaphore identifier
    @param semaklabel Label associated with the semaphore
    @param accesstype Flags to indicate access (read and/or write)
  
    Determine whether the subject identified by the credential can
    perform the operations on the System V semaphore indicated by
    semakptr.  The accesstype flags hold the maximum set of permissions
    from the sem_op array passed to the semop system call.  It may
    contain SEM_R for read-only operations or SEM_A for read/write
    operations.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvsem_check_semop_t(
          kauth_cred_t cred,
          struct semid_kernel *semakptr,
          struct label *semaklabel,
          size_t accesstype
  );
  /**
    @brief Create a System V semaphore label
    @param cred Subject credential
    @param semakptr The semaphore being created
    @param semalabel Label to associate with the new semaphore
  
    Label a new System V semaphore.  The label was previously
    initialized and associated with the semaphore.  At this time, an
    appropriate initial label value should be assigned to the object and
    stored in semalabel.
  */
  typedef void mpo_sysvsem_label_associate_t(
          kauth_cred_t cred,
          struct semid_kernel *semakptr,
          struct label *semalabel
  );
  /**
    @brief Destroy System V semaphore label
    @param label The label to be destroyed
  
    Destroy a System V semaphore label.  Since the object is
    going out of scope, policy modules should free any internal storage
    associated with the label so that it may be destroyed.
  */
  typedef void mpo_sysvsem_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize System V semaphore label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated System V semaphore.  Sleeping
    is permitted.
  */
  typedef void mpo_sysvsem_label_init_t(
          struct label *label
  );
  /**
    @brief Clean up a System V semaphore label
    @param label The label to be cleaned
  
    Clean up a System V semaphore label.  Darwin pre-allocates
    semaphores at system boot time and re-uses them rather than
    allocating new ones.  Before semaphores are returned to the "free
    pool", policies can cleanup or overwrite any information present in
    the label.
  */
  typedef void mpo_sysvsem_label_recycle_t(
          struct label *label
  );
  /**
    @brief Access control check for mapping System V shared memory
    @param cred Subject credential
    @param shmsegptr Pointer to shared memory segment identifier
    @param shmseglabel Label associated with the shared memory segment
    @param shmflg shmat flags; see shmat(2)
  
    Determine whether the subject identified by the credential can map
    the System V shared memory segment associated with shmsegptr.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvshm_check_shmat_t(
          kauth_cred_t cred,
          struct shmid_kernel *shmsegptr,
          struct label *shmseglabel,
          int shmflg
  );
  /**
    @brief Access control check for System V shared memory control operation
    @param cred Subject credential
    @param shmsegptr Pointer to shared memory segment identifier
    @param shmseglabel Label associated with the shared memory segment
    @param cmd Control operation to be performed; see shmctl(2)
  
    Determine whether the subject identified by the credential can perform
    the operation indicated by cmd on the System V shared memory segment
    shmsegptr.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvshm_check_shmctl_t(
          kauth_cred_t cred,
          struct shmid_kernel *shmsegptr,
          struct label *shmseglabel,
          int cmd
  );
  /**
    @brief Access control check for unmapping System V shared memory
    @param cred Subject credential
    @param shmsegptr Pointer to shared memory segment identifier
    @param shmseglabel Label associated with the shared memory segment
  
    Determine whether the subject identified by the credential can unmap
    the System V shared memory segment associated with shmsegptr.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvshm_check_shmdt_t(
          kauth_cred_t cred,
          struct shmid_kernel *shmsegptr,
          struct label *shmseglabel
  );
  /**
    @brief Access control check obtaining System V shared memory identifier
    @param cred Subject credential
    @param shmsegptr Pointer to shared memory segment identifier
    @param shmseglabel Label associated with the shared memory segment
    @param shmflg shmget flags; see shmget(2)
  
    Determine whether the subject identified by the credential can get
    the System V shared memory segment address.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_sysvshm_check_shmget_t(
          kauth_cred_t cred,
          struct shmid_kernel *shmsegptr,
          struct label *shmseglabel,
          int shmflg
  );
  /**
    @brief Create a System V shared memory region label
    @param cred Subject credential
    @param shmsegptr The shared memory region being created
    @param shmlabel Label to associate with the new shared memory region
  
    Label a new System V shared memory region.  The label was previously
    initialized and associated with the shared memory region.  At this
    time, an appropriate initial label value should be assigned to the
    object and stored in shmlabel.
  */
  typedef void mpo_sysvshm_label_associate_t(
          kauth_cred_t cred,
          struct shmid_kernel *shmsegptr,
          struct label *shmlabel
  );
  /**
    @brief Destroy System V shared memory label
    @param label The label to be destroyed
  
    Destroy a System V shared memory region label.  Since the
    object is going out of scope, policy modules should free any
    internal storage associated with the label so that it may be
    destroyed.
  */
  typedef void mpo_sysvshm_label_destroy_t(
          struct label *label
  );
  /**
    @brief Initialize System V Shared Memory region label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated System V Shared Memory
    region.  Sleeping is permitted.
  */
  typedef void mpo_sysvshm_label_init_t(
          struct label *label
  );
  /**
    @brief Clean up a System V Share Memory Region label
    @param shmlabel The label to be cleaned
  
    Clean up a System V Shared Memory Region label.  Darwin
    pre-allocates these objects at system boot time and re-uses them
    rather than allocating new ones.  Before the memory regions are
    returned to the "free pool", policies can cleanup or overwrite any
    information present in the label.
  */
  typedef void mpo_sysvshm_label_recycle_t(
          struct label *shmlabel
  );
  /**
    @brief Access control check for getting a process's task name
    @param cred Subject credential
    @param proc Object process
  
    Determine whether the subject identified by the credential can get
    the passed process's task name port.
    This call is used by the task_name_for_pid(2) API.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch,
    EPERM for lack of privilege, or ESRCH to hide visibility of the target.
  */
  typedef int mpo_proc_check_get_task_name_t(
          kauth_cred_t cred,
          struct proc *p
  );
  /**
    @brief Access control check for getting a process's task port
    @param cred Subject credential
    @param proc Object process
  
    Determine whether the subject identified by the credential can get
    the passed process's task control port.
    This call is used by the task_for_pid(2) API.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch,
    EPERM for lack of privilege, or ESRCH to hide visibility of the target.
  */
  typedef int mpo_proc_check_get_task_t(
          kauth_cred_t cred,
          struct proc *p
  );
  /**
   @brief Privilege check for a process to run invalid
   @param proc Object process
   
   Determine whether the process may execute even though the system determined
   that it is untrusted (eg unidentified / modified code).
   
   @return Return 0 if access is granted, otherwise an appropriate value for
   errno should be returned.
   */
  typedef int mac_proc_check_run_cs_invalid_t(
          struct proc *p
  );
  
  
  /**
    @brief Assign a label to a new kernelspace Mach task
    @param kproc New task
    @param tasklabel Label for new task
    @param portlabel Label for new task port
    @see mpo_cred_label_associate_kernel_t
  
    Assign labels to a new kernel task and its task port. Both the task and
    task port labels should be specified. Both new labels are initialized.
    If there is an associated BSD process structure, it will be labelled
    with calls to mpo_cred_label_associate_kernel.
  */
  typedef void mpo_task_label_associate_kernel_t(
          struct task *kproc,
          struct label *tasklabel,
          struct label *portlabel
  );
  /**
    @brief Assign a label to a new (userspace) Mach task
    @param parent Parent task
    @param child New (child) task
    @param parentlabel Label of parent task
    @param childlabel Label for new task
    @param childportlabel Label for new task's task port
  
    Assign labels to a new task and its task port. Both the task and task port
    labels should be specified. Both new labels are initialized.  If the task
    will have an associated BSD process, that information will be made available
    by the task_label_update and port_label_update_cred entry points.
  */
  typedef void mpo_task_label_associate_t(
          struct task *parent,
          struct task *child,
          struct label *parentlabel,
          struct label *childlabel,
          struct label *childportlabel
  );
  /**
    @brief Copy a Mach task label
    @param src Source task label
    @param dest Destination task label
  
    Copy the Mach task label information from src to dest.  This is used
    when duplicating label handles to implement copy-on-write semantics.
  */
  typedef void mpo_task_label_copy_t(
          struct label *src,
          struct label *dest
  );
  /**
    @brief Destroy Mach task label
    @param label The label to be destroyed
  
    Destroy a Mach task label.  Since the object is going out of
    scope, policy modules should free any internal storage associated
    with the label so that it may be destroyed.
  */
  typedef void mpo_task_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize a task label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of the label
  
    Produce an external representation of the label on a task.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will display this externalized version.
  
    @return 0 on success, return non-zero if an error occurs while
    externalizing the label data.
  
  */
  typedef int mpo_task_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize Mach task label
    @param label New label to initialize
  
    Initialize the label for a newly instantiated Mach task.  Sleeping
    is permitted.
  */
  typedef void mpo_task_label_init_t(
          struct label *label
  );
  /**
    @brief Internalize a task label
    @param label Label to be internalized
    @param element_name Name of the label namespace for which the label should
    be internalized
    @param element_data Text data to be internalized
  
    Produce a task label from an external representation.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will forward text version to the kernel for
    processing by individual policy modules.
  
    The policy's internalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, Otherwise, return non-zero if an error occurs
    while internalizing the label data.
  
  */
  typedef int mpo_task_label_internalize_t(
          struct label *label,
          char *element_name,
          char *element_data
  );
  /**
    @brief Update a Mach task label
    @param cred User credential label to be used as the source
    @param task Mach task label to be used as the destination
    @see mpo_cred_label_update_t
    @see mpo_cred_label_update_execve_t
  
    Update the label on a Mach task, using the supplied user credential
    label. When a mac_cred_label_update_execve or a mac_cred_label_update operation
    causes the label on a user credential to change, the Mach task label
    also needs to be updated to reflect the change.  Both labels are
    already valid (initialized and created).
  
    @warning XXX We may change the name of this entry point in a future
    version of the MAC framework.
  */
  typedef void mpo_task_label_update_t(
          struct label *cred,
          struct label *task
  );
  /**
    @brief Perform MAC-related events when a thread returns to user space
    @param code The number of the syscall/trap that has finished
    @param error The error code that will be returned to user space
    @param thread Mach (not BSD) thread that is returning
  
    This entry point permits policy modules to perform MAC-related
    events when a thread returns to user space, via a system call
    return, trap return, or otherwise.
  */
  typedef void mpo_thread_userret_t(
          int code,
          int error,
          struct thread *thread
  );
  /**
    @brief Check vnode access
    @param cred Subject credential
    @param vp Object vnode
    @param label Label for vp
    @param acc_mode access(2) flags
  
    Determine how invocations of access(2) and related calls by the
    subject identified by the credential should return when performed
    on the passed vnode using the passed access flags. This should
    generally be implemented using the same semantics used in
    mpo_vnode_check_open.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_access_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          int acc_mode
  );
  /**
    @brief Access control check for changing working directory
    @param cred Subject credential
    @param dvp Object; vnode to chdir(2) into
    @param dlabel Policy label for dvp
  
    Determine whether the subject identified by the credential can change
    the process working directory to the passed vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_chdir_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel
  );
  /**
    @brief Access control check for changing root directory
    @param cred Subject credential
    @param dvp Directory vnode
    @param dlabel Policy label associated with dvp
    @param cnp Component name for dvp
  
    Determine whether the subject identified by the credential should be
    allowed to chroot(2) into the specified directory (dvp).
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_vnode_check_chroot_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct componentname *cnp
  );
  /**
    @brief Access control check for creating vnode
    @param cred Subject credential
    @param dvp Directory vnode
    @param dlabel Policy label for dvp
    @param cnp Component name for dvp
    @param vap vnode attributes for vap
  
    Determine whether the subject identified by the credential can create
    a vnode with the passed parent directory, passed name information,
    and passed attribute information. This call may be made in a number of
    situations, including as a result of calls to open(2) with O_CREAT,
    mknod(2), mkfifo(2), and others.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_create_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct componentname *cnp,
          struct vnode_attr *vap
  );
  /**
    @brief Access control check for deleting extended attribute
    @param cred Subject credential
    @param vp Object vnode
    @param vlabel Label associated with vp
    @param name Extended attribute name
  
    Determine whether the subject identified by the credential can delete
    the extended attribute from the passed vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_deleteextattr_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vlabel,
          const char *name
  );
  /**
    @brief Access control check for exchanging file data
    @param cred Subject credential
    @param v1 vnode 1 to swap
    @param vl1 Policy label for v1
    @param v2 vnode 2 to swap
    @param vl2 Policy label for v2
  
    Determine whether the subject identified by the credential can swap the data
    in the two supplied vnodes.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_exchangedata_t(
          kauth_cred_t cred,
          struct vnode *v1,
          struct label *vl1,
          struct vnode *v2,
          struct label *vl2
  );
  /**
    @brief Access control check for executing the vnode
    @param cred Subject credential
    @param vp Object vnode to execute
    @param label Policy label for vp
    @param execlabel Userspace provided execution label
    @param cnp Component name for file being executed
  
    Determine whether the subject identified by the credential can execute
    the passed vnode. Determination of execute privilege is made separately
    from decisions about any process label transitioning event.
  
    The final label, execlabel, corresponds to a label supplied by a
    user space application through the use of the mac_execve system call.
    This label will be NULL if the user application uses the the vendor
    execve(2) call instead of the MAC Framework mac_execve() call.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_exec_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          struct label *execlabel,        /* NULLOK */
          struct componentname *cnp,
          u_int *csflags
  );
  /**
    @brief Access control check after determining the code directory hash
   */
  typedef int mpo_vnode_check_signature_t(struct vnode *vp,  struct label *label, 
                                          unsigned char *sha1, void *signature, 
                                          int size);
  
  /**
    @brief Access control check for retrieving file attributes
    @param cred Subject credential
    @param vp Object vnode
    @param vlabel Policy label for vp
    @param alist List of attributes to retrieve
  
    Determine whether the subject identified by the credential can read
    various attributes of the specified vnode, or the filesystem or volume on
    which that vnode resides. See <sys/attr.h> for definitions of the
    attributes.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege. Access control covers all attributes requested
    with this call; the security policy is not permitted to change the set of
    attributes requested.
  */
  typedef int mpo_vnode_check_getattrlist_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vlabel,
          struct attrlist *alist
  );
  /**
    @brief Access control check for retrieving an extended attribute
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param name Extended attribute name
    @param uio I/O structure pointer
  
    Determine whether the subject identified by the credential can retrieve
    the extended attribute from the passed vnode.  The uio parameter
    will be NULL when the getxattr(2) call has been made with a NULL data
    value; this is done to request the size of the data only.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_getextattr_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,            /* NULLOK */
          const char *name,
          struct uio *uio                 /* NULLOK */
  );
  /**
    @brief Access control check for ioctl
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param com Device-dependent request code; see ioctl(2)
  
    Determine whether the subject identified by the credential can perform
    the ioctl operation indicated by com.
  
    @warning Since ioctl data is opaque from the standpoint of the MAC
    framework, and since ioctls can affect many aspects of system
    operation, policies must exercise extreme care when implementing
    access control checks.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_vnode_check_ioctl_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          unsigned int cmd
  );
  /**
    @brief Access control check for vnode kqfilter
    @param cred Subject credential
    @param kn Object knote
    @param vp Object vnode
    @param label Policy label for vp
  
    Determine whether the subject identified by the credential can
    receive the knote on the passed vnode.
  
    @return Return 0 if access if granted, otherwise an appropriate
    value for errno should be returned.
  */
  typedef int mpo_vnode_check_kqfilter_t(
          kauth_cred_t active_cred,
          kauth_cred_t file_cred,         /* NULLOK */
          struct knote *kn,
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for relabel
    @param cred Subject credential
    @param vp Object vnode
    @param vnodelabel Existing policy label for vp
    @param newlabel Policy label update to later be applied to vp
    @see mpo_relable_vnode_t
  
    Determine whether the subject identified by the credential can relabel
    the passed vnode to the passed label update.  If all policies permit
    the label change, the actual relabel entry point (mpo_vnode_label_update)
    will follow.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_vnode_check_label_update_t(
          struct ucred *cred,
          struct vnode *vp,
          struct label *vnodelabel,
          struct label *newlabel
  );
  /**
    @brief Access control check for creating link
    @param cred Subject credential
    @param dvp Directory vnode
    @param dlabel Policy label associated with dvp
    @param vp Link destination vnode
    @param label Policy label associated with vp
    @param cnp Component name for the link being created
  
    Determine whether the subject identified by the credential should be
    allowed to create a link to the vnode vp with the name specified by cnp.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_vnode_check_link_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct vnode *vp,
          struct label *label,
          struct componentname *cnp
  );
  /**
    @brief Access control check for listing extended attributes
    @param cred Subject credential
    @param vp Object vnode
    @param vlabel Policy label associated with vp
  
    Determine whether the subject identified by the credential can retrieve
    a list of named extended attributes from a vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_vnode_check_listextattr_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Access control check for lookup
    @param cred Subject credential
    @param dvp Object vnode
    @param dlabel Policy label for dvp
    @param cnp Component name being looked up
  
    Determine whether the subject identified by the credential can perform
    a lookup in the passed directory vnode for the passed name (cnp).
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_lookup_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct componentname *cnp
  );
  /**
    @brief Access control check for open
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label associated with vp
    @param acc_mode open(2) access mode
  
    Determine whether the subject identified by the credential can perform
    an open operation on the passed vnode with the passed access mode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_open_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          int acc_mode
  );
  /**
    @brief Access control check for read
    @param active_cred Subject credential
    @param file_cred Credential associated with the struct fileproc
    @param vp Object vnode
    @param label Policy label for vp
  
    Determine whether the subject identified by the credential can perform
    a read operation on the passed vnode.  The active_cred hold the credentials
    of the subject performing the operation, and file_cred holds the
    credentials of the subject that originally opened the file.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_read_t(
          kauth_cred_t active_cred,       /* SUBJECT */
          kauth_cred_t file_cred, /* NULLOK */
          struct vnode *vp,               /* OBJECT */
          struct label *label             /* LABEL */
  );
  /**
    @brief Access control check for read directory
    @param cred Subject credential
    @param dvp Object directory vnode
    @param dlabel Policy label for dvp
  
    Determine whether the subject identified by the credential can
    perform a readdir operation on the passed directory vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_readdir_t(
          kauth_cred_t cred,              /* SUBJECT */
          struct vnode *dvp,              /* OBJECT */
          struct label *dlabel            /* LABEL */
  );
  /**
    @brief Access control check for read link
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
  
    Determine whether the subject identified by the credential can perform
    a readlink operation on the passed symlink vnode.  This call can be made
    in a number of situations, including an explicit readlink call by the
    user process, or as a result of an implicit readlink during a name
    lookup by the process.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_readlink_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for rename from
    @param cred Subject credential
    @param dvp Directory vnode
    @param dlabel Policy label associated with dvp
    @param vp vnode to be renamed
    @param label Policy label associated with vp
    @param cnp Component name for vp
    @see mpo_vnode_check_rename_to_t
  
    Determine whether the subject identified by the credential should be
    allowed to rename the vnode vp to something else.
  
    Due to VFS locking constraints (to make sure proper vnode locks are
    held during this entry point), the vnode relabel checks had to be
    split into two parts: relabel_from and relabel to.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_vnode_check_rename_from_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct vnode *vp,
          struct label *label,
          struct componentname *cnp
  );
  /**
    @brief Access control check for rename to
    @param cred Subject credential
    @param dvp Directory vnode
    @param dlabel Policy label associated with dvp
    @param vp Overwritten vnode
    @param label Policy label associated with vp
    @param samedir Boolean; 1 if the source and destination directories are the same
    @param cnp Destination component name
    @see mpo_vnode_check_rename_from_t
  
    Determine whether the subject identified by the credential should be
    allowed to rename to the vnode vp, into the directory dvp, or to the
    name represented by cnp. If there is no existing file to overwrite,
    vp and label will be NULL.
  
    Due to VFS locking constraints (to make sure proper vnode locks are
    held during this entry point), the vnode relabel checks had to be
    split into two parts: relabel_from and relabel to.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_vnode_check_rename_to_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct vnode *vp,                       /* NULLOK */
          struct label *label,                    /* NULLOK */
          int samedir,
          struct componentname *cnp
  );
  /**
    @brief Access control check for revoke
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
  
    Determine whether the subject identified by the credential can revoke
    access to the passed vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_revoke_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for select
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param which The operation selected on: FREAD or FWRITE
  
    Determine whether the subject identified by the credential can select
    the vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned.
  */
  typedef int mpo_vnode_check_select_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          int which
  );
  /**
    @brief Access control check for setting file attributes
    @param cred Subject credential
    @param vp Object vnode
    @param vlabel Policy label for vp
    @param alist List of attributes to set
  
    Determine whether the subject identified by the credential can set
    various attributes of the specified vnode, or the filesystem or volume on
    which that vnode resides. See <sys/attr.h> for definitions of the
    attributes.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege. Access control covers all attributes requested
    with this call.
  */
  typedef int mpo_vnode_check_setattrlist_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vlabel,
          struct attrlist *alist
  );
  /**
    @brief Access control check for setting extended attribute
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param name Extended attribute name
    @param uio I/O structure pointer
  
    Determine whether the subject identified by the credential can set the
    extended attribute of passed name and passed namespace on the passed
    vnode. Policies implementing security labels backed into extended
    attributes may want to provide additional protections for those
    attributes. Additionally, policies should avoid making decisions based
    on the data referenced from uio, as there is a potential race condition
    between this check and the actual operation. The uio may also be NULL
    if a delete operation is being performed.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_setextattr_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          const char *name,
          struct uio *uio
  );
  /**
    @brief Access control check for setting flags
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param flags File flags; see chflags(2)
  
    Determine whether the subject identified by the credential can set
    the passed flags on the passed vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_setflags_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          u_long flags
  );
  /**
    @brief Access control check for setting mode
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param mode File mode; see chmod(2)
  
    Determine whether the subject identified by the credential can set
    the passed mode on the passed vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_setmode_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          mode_t mode
  );
  /**
    @brief Access control check for setting uid and gid
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param uid User ID
    @param gid Group ID
  
    Determine whether the subject identified by the credential can set
    the passed uid and passed gid as file uid and file gid on the passed
    vnode. The IDs may be set to (-1) to request no update.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_setowner_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          uid_t uid,
          gid_t gid
  );
  /**
    @brief Access control check for setting timestamps
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label for vp
    @param atime Access time; see utimes(2)
    @param mtime Modification time; see utimes(2)
  
    Determine whether the subject identified by the credential can set
    the passed access timestamps on the passed vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_setutimes_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label,
          struct timespec atime,
          struct timespec mtime
  );
  /**
    @brief Access control check for stat
    @param active_cred Subject credential
    @param file_cred Credential associated with the struct fileproc
    @param vp Object vnode
    @param label Policy label for vp
  
    Determine whether the subject identified by the credential can stat
    the passed vnode. See stat(2) for more information.  The active_cred
    hold the credentials of the subject performing the operation, and
    file_cred holds the credentials of the subject that originally
    opened the file.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_stat_t(
          struct ucred *active_cred,
          struct ucred *file_cred,        /* NULLOK */
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for truncate/ftruncate
    @param active_cred Subject credential
    @param file_cred Credential associated with the struct fileproc
    @param vp Object vnode
    @param label Policy label for vp
  
    Determine whether the subject identified by the credential can
    perform a truncate operation on the passed vnode.  The active_cred hold
    the credentials of the subject performing the operation, and
    file_cred holds the credentials of the subject that originally
    opened the file.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_truncate_t(
          kauth_cred_t active_cred,
          kauth_cred_t file_cred, /* NULLOK */
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for binding UNIX domain socket
    @param cred Subject credential
    @param dvp Directory vnode
    @param dlabel Policy label for dvp
    @param cnp Component name for dvp
    @param vap vnode attributes for vap
  
    Determine whether the subject identified by the credential can perform a
    bind operation on a UNIX domain socket with the passed parent directory,
    passed name information, and passed attribute information.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_uipc_bind_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct componentname *cnp,
          struct vnode_attr *vap
  );
  /**
    @brief Access control check for connecting UNIX domain socket
    @param cred Subject credential
    @param vp Object vnode
    @param label Policy label associated with vp
  
    Determine whether the subject identified by the credential can perform a
    connect operation on the passed UNIX domain socket vnode.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_uipc_connect_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Access control check for deleting vnode
    @param cred Subject credential
    @param dvp Parent directory vnode
    @param dlabel Policy label for dvp
    @param vp Object vnode to delete
    @param label Policy label for vp
    @param cnp Component name for vp
    @see mpo_check_rename_to_t
  
    Determine whether the subject identified by the credential can delete
    a vnode from the passed parent directory and passed name information.
    This call may be made in a number of situations, including as a
    results of calls to unlink(2) and rmdir(2). Policies implementing
    this entry point should also implement mpo_check_rename_to to
    authorize deletion of objects as a result of being the target of a rename.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_unlink_t(
          kauth_cred_t cred,
          struct vnode *dvp,
          struct label *dlabel,
          struct vnode *vp,
          struct label *label,
          struct componentname *cnp
  );
  /**
    @brief Access control check for write
    @param active_cred Subject credential
    @param file_cred Credential associated with the struct fileproc
    @param vp Object vnode
    @param label Policy label for vp
  
    Determine whether the subject identified by the credential can
    perform a write operation on the passed vnode.  The active_cred hold
    the credentials of the subject performing the operation, and
    file_cred holds the credentials of the subject that originally
    opened the file.
  
    @return Return 0 if access is granted, otherwise an appropriate value for
    errno should be returned. Suggested failure: EACCES for label mismatch or
    EPERM for lack of privilege.
  */
  typedef int mpo_vnode_check_write_t(
          kauth_cred_t active_cred,
          kauth_cred_t file_cred, /* NULLOK */
          struct vnode *vp,
          struct label *label
  );
  /**
    @brief Associate a vnode with a devfs entry
    @param mp Devfs mount point
    @param mntlabel Devfs mount point label
    @param de Devfs directory entry
    @param delabel Label associated with de
    @param vp vnode associated with de
    @param vlabel Label associated with vp
  
    Fill in the label (vlabel) for a newly created devfs vnode.  The
    label is typically derived from the label on the devfs directory
    entry or the label on the filesystem, supplied as parameters.
  */
  typedef void mpo_vnode_label_associate_devfs_t(
          struct mount *mp,
          struct label *mntlabel,
          struct devnode *de,
          struct label *delabel,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Associate a label with a vnode
    @param mp File system mount point
    @param mntlabel File system mount point label
    @param vp Vnode to label
    @param vlabel Label associated with vp
  
    Attempt to retrieve label information for the vnode, vp, from the
    file system extended attribute store.  The label should be stored in
    the supplied vlabel parameter.  If a policy cannot retrieve an
    extended attribute, sometimes it is acceptible to fallback to using
    the mntlabel.
  
    If the policy requires vnodes to have a valid label elsewhere it
    MUST NOT return other than temporary errors, and must always provide
    a valid label of some sort.  Returning an error will cause vnode
    labeling to be retried at a later access.  Failure to handle policy
    centric errors internally (corrupt labels etc.) will result in
    inaccessible files.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  */
  typedef int mpo_vnode_label_associate_extattr_t(
          struct mount *mp,
          struct label *mntlabel,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Associate a file label with a vnode
    @param cred User credential
    @param mp Fdesc mount point
    @param mntlabel Fdesc mount point label
    @param fg Fileglob structure
    @param label Policy label for fg
    @param vp Vnode to label
    @param vlabel Label associated with vp
  
    Associate label information for the vnode, vp, with the label of
    the open file descriptor described by fg.
    The label should be stored in the supplied vlabel parameter.
  */
  typedef void mpo_vnode_label_associate_file_t(
          struct ucred *cred,
          struct mount *mp,
          struct label *mntlabel,
          struct fileglob *fg,
          struct label *label,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Associate a pipe label with a vnode
    @param cred User credential for the process that opened the pipe
    @param cpipe Pipe structure
    @param pipelabel Label associated with pipe
    @param vp Vnode to label
    @param vlabel Label associated with vp
  
    Associate label information for the vnode, vp, with the label of
    the pipe described by the pipe structure cpipe.
    The label should be stored in the supplied vlabel parameter.
  */
  typedef void mpo_vnode_label_associate_pipe_t(
          struct ucred *cred,
          struct pipe *cpipe,
          struct label *pipelabel,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Associate a POSIX semaphore label with a vnode
    @param cred User credential for the process that create psem
    @param psem POSIX semaphore structure
    @param psemlabel Label associated with psem
    @param vp Vnode to label
    @param vlabel Label associated with vp
  
    Associate label information for the vnode, vp, with the label of
    the POSIX semaphore described by psem.
    The label should be stored in the supplied vlabel parameter.
  */
  typedef void mpo_vnode_label_associate_posixsem_t(
          struct ucred *cred,
          struct pseminfo *psem,
          struct label *psemlabel,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Associate a POSIX shared memory label with a vnode
    @param cred User credential for the process that created pshm
    @param pshm POSIX shared memory structure
    @param pshmlabel Label associated with pshm
    @param vp Vnode to label
    @param vlabel Label associated with vp
  
    Associate label information for the vnode, vp, with the label of
    the POSIX shared memory region described by pshm.
    The label should be stored in the supplied vlabel parameter.
  */
  typedef void mpo_vnode_label_associate_posixshm_t(
          struct ucred *cred,
          struct pshminfo *pshm,
          struct label *pshmlabel,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Associate a label with a vnode
    @param mp File system mount point
    @param mntlabel File system mount point label
    @param vp Vnode to label
    @param vlabel Label associated with vp
  
    On non-multilabel file systems, set the label for a vnode.  The
    label will most likely be based on the file system label.
  */
  typedef void mpo_vnode_label_associate_singlelabel_t(
          struct mount *mp,
          struct label *mntlabel,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Associate a socket label with a vnode
    @param cred User credential for the process that opened the socket
    @param so Socket structure
    @param solabel Label associated with so
    @param vp Vnode to label
    @param vlabel Label associated with vp
  
    Associate label information for the vnode, vp, with the label of
    the open socket described by the socket structure so.
    The label should be stored in the supplied vlabel parameter.
  */
  typedef void mpo_vnode_label_associate_socket_t(
          kauth_cred_t cred,
          socket_t so,
          struct label *solabel,
          struct vnode *vp,
          struct label *vlabel
  );
  /**
    @brief Copy a vnode label
    @param src Source vnode label
    @param dest Destination vnode label
  
    Copy the vnode label information from src to dest.  On Darwin, this
    is currently only necessary when executing interpreted scripts, but
    will later be used if vnode label externalization cannot be an
    atomic operation.
  */
  typedef void mpo_vnode_label_copy_t(
          struct label *src,
          struct label *dest
  );
  /**
    @brief Destroy vnode label
    @param label The label to be destroyed
  
    Destroy a vnode label.  Since the object is going out of scope,
    policy modules should free any internal storage associated with the
    label so that it may be destroyed.
  */
  typedef void mpo_vnode_label_destroy_t(
          struct label *label
  );
  /**
    @brief Externalize a vnode label for auditing
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of the label
  
    Produce an external representation of the label on a vnode suitable for
    inclusion in an audit record.  An externalized label consists of a text
    representation of the label contents that will be added to the audit record
    as part of a text token.  Policy-agnostic user space tools will display
    this externalized version.
  
    @return 0 on success, return non-zero if an error occurs while
    externalizing the label data.
  
  */
  typedef int mpo_vnode_label_externalize_audit_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Externalize a vnode label
    @param label Label to be externalized
    @param element_name Name of the label namespace for which labels should be
    externalized
    @param sb String buffer to be filled with a text representation of the label
  
    Produce an external representation of the label on a vnode.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will display this externalized version.
  
    @return 0 on success, return non-zero if an error occurs while
    externalizing the label data.
  
  */
  typedef int mpo_vnode_label_externalize_t(
          struct label *label,
          char *element_name,
          struct sbuf *sb
  );
  /**
    @brief Initialize vnode label
    @param label New label to initialize
  
    Initialize label storage for use with a newly instantiated vnode, or
    for temporary storage associated with the copying in or out of a
    vnode label.  While it is necessary to allocate space for a
    kernel-resident vnode label, it is not yet necessary to link this vnode
    with persistent label storage facilities, such as extended attributes.
    Sleeping is permitted.
  */
  typedef void mpo_vnode_label_init_t(
          struct label *label
  );
  /**
    @brief Internalize a vnode label
    @param label Label to be internalized
    @param element_name Name of the label namespace for which the label should
    be internalized
    @param element_data Text data to be internalized
  
    Produce a vnode label from an external representation.  An
    externalized label consists of a text representation of the label
    contents that can be used with user applications.  Policy-agnostic
    user space tools will forward text version to the kernel for
    processing by individual policy modules.
  
    The policy's internalize entry points will be called only if the
    policy has registered interest in the label namespace.
  
    @return 0 on success, Otherwise, return non-zero if an error occurs
    while internalizing the label data.
  */
  typedef int mpo_vnode_label_internalize_t(
          struct label *label,
          char *element_name,
          char *element_data
  );
  /**
    @brief Clean up a vnode label
    @param label The label to be cleaned for re-use
  
    Clean up a vnode label.  Darwin (Tiger, 8.x) allocates vnodes on demand, but
    typically never frees them.  Before vnodes are placed back on free lists for
    re-use, policies can cleanup or overwrite any information present in the label.
  */
  typedef void mpo_vnode_label_recycle_t(
          struct label *label
  );
  /**
    @brief Write a label to a extended attribute
    @param cred Subject credential
    @param vp The vnode for which the label is being stored
    @param vlabel Label associated with vp
    @param intlabel The new label to store
  
    Store a new label in the extended attribute corresponding to the
    supplied vnode.  The policy has already authorized the operation;
    this call must be implemented in order to perform the actual
    operation.
  
    @return In the event of an error, an appropriate value for errno
    should be returned, otherwise return 0 upon success.
  
    @warning XXX After examining the extended attribute implementation on
    Apple's future release, this entry point may be changed.
  */
  typedef int mpo_vnode_label_store_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vlabel,
          struct label *intlabel
  );
  /**
    @brief Update vnode label from extended attributes
    @param mp File system mount point
    @param mntlabel Mount point label
    @param vp Vnode to label
    @param vlabel Label associated with vp
    @param name Name of the xattr
    @see mpo_vnode_check_setextattr_t
  
    When an extended attribute is updated via the Vendor attribute management
    functions, the MAC vnode label might also require an update.
    Policies should first determine if 'name' matches their xattr label
    name.  If it does, the kernel is has either replaced or removed the
    named extended attribute that was previously associated with the
    vnode.  Normally labels should only be modified via MAC Framework label
    management calls, but sometimes the user space components will directly
    modify extended attributes.  For example, 'cp', 'tar', etc. manage
    extended attributes in userspace, not the kernel.
  
    This entry point is called after the label update has occurred, so
    it cannot return a failure.  However, the operation is preceded by
    the mpo_vnode_check_setextattr() access control check.
  
    If the vnode label needs to be updated the policy should return
    a non-zero value.  The vnode label will be marked for re-association
    by the framework.
  */
  typedef int mpo_vnode_label_update_extattr_t(
          struct mount *mp,
          struct label *mntlabel,
          struct vnode *vp,
          struct label *vlabel,
          const char *name
  );
  /**
    @brief Update a vnode label
    @param cred Subject credential
    @param vp The vnode to relabel
    @param vnodelabel Existing vnode label
    @param label New label to replace existing label
    @see mpo_vnode_check_label_update_t
  
    The subject identified by the credential has previously requested
    and was authorized to relabel the vnode; this entry point allows
    policies to perform the actual relabel operation.  Policies should
    update vnodelabel using the label stored in the label parameter.
  */
  typedef void mpo_vnode_label_update_t(
          kauth_cred_t cred,
          struct vnode *vp,
          struct label *vnodelabel,
          struct label *label
  );
  /**
    @brief Create a new vnode, backed by extended attributes
    @param cred User credential for the creating process
    @param mp File system mount point
    @param mntlabel File system mount point label
    @param dvp Parent directory vnode
    @param dlabel Parent directory vnode label
    @param vp Newly created vnode
    @param vlabel Label to associate with the new vnode
    @param cnp Component name for vp
  
    Write out the label for the newly created vnode, most likely storing
    the results in a file system extended attribute.  Most policies will
    derive the new vnode label using information from a combination
    of the subject (user) credential, the file system label, the parent
    directory label, and potentially the path name component.
  
    @return If the operation succeeds, store the new label in vlabel and
    return 0.  Otherwise, return an appropriate errno value.
  */
  typedef int mpo_vnode_notify_create_t(
          kauth_cred_t cred,
          struct mount *mp,
          struct label *mntlabel,
          struct vnode *dvp,
          struct label *dlabel,
          struct vnode *vp,
          struct label *vlabel,
          struct componentname *cnp
  );
  
  /*
   * Placeholder for future events that may need mac hooks.
   */
  typedef void mpo_reserved_hook_t(void);
  
  /*!
    \struct mac_policy_ops
  */
  struct mac_policy_ops {
          mpo_audit_check_postselect_t            *mpo_audit_check_postselect;
          mpo_audit_check_preselect_t             *mpo_audit_check_preselect;
          mpo_bpfdesc_label_associate_t           *mpo_bpfdesc_label_associate;
          mpo_bpfdesc_label_destroy_t             *mpo_bpfdesc_label_destroy;
          mpo_bpfdesc_label_init_t                *mpo_bpfdesc_label_init;
          mpo_bpfdesc_check_receive_t             *mpo_bpfdesc_check_receive;
          mpo_cred_check_label_update_execve_t    *mpo_cred_check_label_update_execve;
          mpo_cred_check_label_update_t           *mpo_cred_check_label_update;
          mpo_cred_check_visible_t                *mpo_cred_check_visible;
          mpo_cred_label_associate_fork_t         *mpo_cred_label_associate_fork;
          mpo_cred_label_associate_kernel_t       *mpo_cred_label_associate_kernel;
          mpo_cred_label_associate_t              *mpo_cred_label_associate;
          mpo_cred_label_associate_user_t         *mpo_cred_label_associate_user;
          mpo_cred_label_destroy_t                *mpo_cred_label_destroy;
          mpo_cred_label_externalize_audit_t      *mpo_cred_label_externalize_audit;
          mpo_cred_label_externalize_t            *mpo_cred_label_externalize;
          mpo_cred_label_init_t                   *mpo_cred_label_init;
          mpo_cred_label_internalize_t            *mpo_cred_label_internalize;
          mpo_cred_label_update_execve_t          *mpo_cred_label_update_execve;
          mpo_cred_label_update_t                 *mpo_cred_label_update;
          mpo_devfs_label_associate_device_t      *mpo_devfs_label_associate_device;
          mpo_devfs_label_associate_directory_t   *mpo_devfs_label_associate_directory;
          mpo_devfs_label_copy_t                  *mpo_devfs_label_copy;
          mpo_devfs_label_destroy_t               *mpo_devfs_label_destroy;
          mpo_devfs_label_init_t                  *mpo_devfs_label_init;
          mpo_devfs_label_update_t                *mpo_devfs_label_update;
          mpo_file_check_change_offset_t          *mpo_file_check_change_offset;
          mpo_file_check_create_t                 *mpo_file_check_create;
          mpo_file_check_dup_t                    *mpo_file_check_dup;
          mpo_file_check_fcntl_t                  *mpo_file_check_fcntl;
          mpo_file_check_get_offset_t             *mpo_file_check_get_offset;
          mpo_file_check_get_t                    *mpo_file_check_get;
          mpo_file_check_inherit_t                *mpo_file_check_inherit;
          mpo_file_check_ioctl_t                  *mpo_file_check_ioctl;
          mpo_file_check_lock_t                   *mpo_file_check_lock;
          mpo_file_check_mmap_downgrade_t         *mpo_file_check_mmap_downgrade;
          mpo_file_check_mmap_t                   *mpo_file_check_mmap;
          mpo_file_check_receive_t                *mpo_file_check_receive;
          mpo_file_check_set_t                    *mpo_file_check_set;
          mpo_file_label_init_t                   *mpo_file_label_init;
          mpo_file_label_destroy_t                *mpo_file_label_destroy;
          mpo_file_label_associate_t              *mpo_file_label_associate;
          mpo_ifnet_check_label_update_t          *mpo_ifnet_check_label_update;
          mpo_ifnet_check_transmit_t              *mpo_ifnet_check_transmit;
          mpo_ifnet_label_associate_t             *mpo_ifnet_label_associate;
          mpo_ifnet_label_copy_t                  *mpo_ifnet_label_copy;
          mpo_ifnet_label_destroy_t               *mpo_ifnet_label_destroy;
          mpo_ifnet_label_externalize_t           *mpo_ifnet_label_externalize;
          mpo_ifnet_label_init_t                  *mpo_ifnet_label_init;
          mpo_ifnet_label_internalize_t           *mpo_ifnet_label_internalize;
          mpo_ifnet_label_update_t                *mpo_ifnet_label_update;
          mpo_ifnet_label_recycle_t               *mpo_ifnet_label_recycle;
          mpo_inpcb_check_deliver_t               *mpo_inpcb_check_deliver;
          mpo_inpcb_label_associate_t             *mpo_inpcb_label_associate;
          mpo_inpcb_label_destroy_t               *mpo_inpcb_label_destroy;
          mpo_inpcb_label_init_t                  *mpo_inpcb_label_init;
          mpo_inpcb_label_recycle_t               *mpo_inpcb_label_recycle;
          mpo_inpcb_label_update_t                *mpo_inpcb_label_update;
          mpo_iokit_check_device_t                *mpo_iokit_check_device;
          mpo_ipq_label_associate_t               *mpo_ipq_label_associate;
          mpo_ipq_label_compare_t                 *mpo_ipq_label_compare;
          mpo_ipq_label_destroy_t                 *mpo_ipq_label_destroy;
          mpo_ipq_label_init_t                    *mpo_ipq_label_init;
          mpo_ipq_label_update_t                  *mpo_ipq_label_update;
          mpo_lctx_check_label_update_t           *mpo_lctx_check_label_update;
          mpo_lctx_label_destroy_t                *mpo_lctx_label_destroy;
          mpo_lctx_label_externalize_t            *mpo_lctx_label_externalize;
          mpo_lctx_label_init_t                   *mpo_lctx_label_init;
          mpo_lctx_label_internalize_t            *mpo_lctx_label_internalize;
          mpo_lctx_label_update_t                 *mpo_lctx_label_update;
          mpo_lctx_notify_create_t                *mpo_lctx_notify_create;
          mpo_lctx_notify_join_t                  *mpo_lctx_notify_join;
          mpo_lctx_notify_leave_t                 *mpo_lctx_notify_leave;
          mpo_mbuf_label_associate_bpfdesc_t      *mpo_mbuf_label_associate_bpfdesc;
          mpo_mbuf_label_associate_ifnet_t        *mpo_mbuf_label_associate_ifnet;
          mpo_mbuf_label_associate_inpcb_t        *mpo_mbuf_label_associate_inpcb;
          mpo_mbuf_label_associate_ipq_t          *mpo_mbuf_label_associate_ipq;
          mpo_mbuf_label_associate_linklayer_t    *mpo_mbuf_label_associate_linklayer;
          mpo_mbuf_label_associate_multicast_encap_t *mpo_mbuf_label_associate_multicast_encap;
          mpo_mbuf_label_associate_netlayer_t     *mpo_mbuf_label_associate_netlayer;
          mpo_mbuf_label_associate_socket_t       *mpo_mbuf_label_associate_socket;
          mpo_mbuf_label_copy_t                   *mpo_mbuf_label_copy;
          mpo_mbuf_label_destroy_t                *mpo_mbuf_label_destroy;
          mpo_mbuf_label_init_t                   *mpo_mbuf_label_init;
          mpo_mount_check_fsctl_t                 *mpo_mount_check_fsctl;
          mpo_mount_check_getattr_t               *mpo_mount_check_getattr;
          mpo_mount_check_label_update_t          *mpo_mount_check_label_update;
          mpo_mount_check_mount_t                 *mpo_mount_check_mount;
          mpo_mount_check_remount_t               *mpo_mount_check_remount;
          mpo_mount_check_setattr_t               *mpo_mount_check_setattr;
          mpo_mount_check_stat_t                  *mpo_mount_check_stat;
          mpo_mount_check_umount_t                *mpo_mount_check_umount;
          mpo_mount_label_associate_t             *mpo_mount_label_associate;
          mpo_mount_label_destroy_t               *mpo_mount_label_destroy;
          mpo_mount_label_externalize_t           *mpo_mount_label_externalize;
          mpo_mount_label_init_t                  *mpo_mount_label_init;
          mpo_mount_label_internalize_t           *mpo_mount_label_internalize;
          mpo_netinet_fragment_t                  *mpo_netinet_fragment;
          mpo_netinet_icmp_reply_t                *mpo_netinet_icmp_reply;
          mpo_netinet_tcp_reply_t                 *mpo_netinet_tcp_reply;
          mpo_pipe_check_ioctl_t                  *mpo_pipe_check_ioctl;
          mpo_pipe_check_kqfilter_t               *mpo_pipe_check_kqfilter;
          mpo_pipe_check_label_update_t           *mpo_pipe_check_label_update;
          mpo_pipe_check_read_t                   *mpo_pipe_check_read;
          mpo_pipe_check_select_t                 *mpo_pipe_check_select;
          mpo_pipe_check_stat_t                   *mpo_pipe_check_stat;
          mpo_pipe_check_write_t                  *mpo_pipe_check_write;
          mpo_pipe_label_associate_t              *mpo_pipe_label_associate;
          mpo_pipe_label_copy_t                   *mpo_pipe_label_copy;
          mpo_pipe_label_destroy_t                *mpo_pipe_label_destroy;
          mpo_pipe_label_externalize_t            *mpo_pipe_label_externalize;
          mpo_pipe_label_init_t                   *mpo_pipe_label_init;
          mpo_pipe_label_internalize_t            *mpo_pipe_label_internalize;
          mpo_pipe_label_update_t                 *mpo_pipe_label_update;
          mpo_policy_destroy_t                    *mpo_policy_destroy;
          mpo_policy_init_t                       *mpo_policy_init;
          mpo_policy_initbsd_t                    *mpo_policy_initbsd;
          mpo_policy_syscall_t                    *mpo_policy_syscall;
          mpo_port_check_copy_send_t              *mpo_port_check_copy_send;
          mpo_port_check_hold_receive_t           *mpo_port_check_hold_receive;
          mpo_port_check_hold_send_once_t         *mpo_port_check_hold_send_once;
          mpo_port_check_hold_send_t              *mpo_port_check_hold_send;
          mpo_port_check_label_update_t           *mpo_port_check_label_update;
          mpo_port_check_make_send_once_t         *mpo_port_check_make_send_once;
          mpo_port_check_make_send_t              *mpo_port_check_make_send;
          mpo_port_check_method_t                 *mpo_port_check_method;
          mpo_port_check_move_receive_t           *mpo_port_check_move_receive;
          mpo_port_check_move_send_once_t         *mpo_port_check_move_send_once;
          mpo_port_check_move_send_t              *mpo_port_check_move_send;
          mpo_port_check_receive_t                *mpo_port_check_receive;
          mpo_port_check_send_t                   *mpo_port_check_send;
          mpo_port_check_service_t                *mpo_port_check_service;
          mpo_port_label_associate_kernel_t       *mpo_port_label_associate_kernel;
          mpo_port_label_associate_t              *mpo_port_label_associate;
          mpo_port_label_compute_t                *mpo_port_label_compute;
          mpo_port_label_copy_t                   *mpo_port_label_copy;
          mpo_port_label_destroy_t                *mpo_port_label_destroy;
          mpo_port_label_init_t                   *mpo_port_label_init;
          mpo_port_label_update_cred_t            *mpo_port_label_update_cred;
          mpo_port_label_update_kobject_t         *mpo_port_label_update_kobject;
          mpo_posixsem_check_create_t             *mpo_posixsem_check_create;
          mpo_posixsem_check_open_t               *mpo_posixsem_check_open;
          mpo_posixsem_check_post_t               *mpo_posixsem_check_post;
          mpo_posixsem_check_unlink_t             *mpo_posixsem_check_unlink;
          mpo_posixsem_check_wait_t               *mpo_posixsem_check_wait;
          mpo_posixsem_label_associate_t          *mpo_posixsem_label_associate;
          mpo_posixsem_label_destroy_t            *mpo_posixsem_label_destroy;
          mpo_posixsem_label_init_t               *mpo_posixsem_label_init;
          mpo_posixshm_check_create_t             *mpo_posixshm_check_create;
          mpo_posixshm_check_mmap_t               *mpo_posixshm_check_mmap;
          mpo_posixshm_check_open_t               *mpo_posixshm_check_open;
          mpo_posixshm_check_stat_t               *mpo_posixshm_check_stat;
          mpo_posixshm_check_truncate_t           *mpo_posixshm_check_truncate;
          mpo_posixshm_check_unlink_t             *mpo_posixshm_check_unlink;
          mpo_posixshm_label_associate_t          *mpo_posixshm_label_associate;
          mpo_posixshm_label_destroy_t            *mpo_posixshm_label_destroy;
          mpo_posixshm_label_init_t               *mpo_posixshm_label_init;
          mpo_proc_check_debug_t                  *mpo_proc_check_debug;
          mpo_proc_check_fork_t                   *mpo_proc_check_fork;
          mpo_proc_check_get_task_name_t          *mpo_proc_check_get_task_name;
          mpo_proc_check_get_task_t               *mpo_proc_check_get_task;
          mpo_proc_check_getaudit_t               *mpo_proc_check_getaudit;
          mpo_proc_check_getauid_t                *mpo_proc_check_getauid;
          mpo_proc_check_getlcid_t                *mpo_proc_check_getlcid;
          mpo_proc_check_mprotect_t               *mpo_proc_check_mprotect;
          mpo_proc_check_sched_t                  *mpo_proc_check_sched;
          mpo_proc_check_setaudit_t               *mpo_proc_check_setaudit;
          mpo_proc_check_setauid_t                *mpo_proc_check_setauid;
          mpo_proc_check_setlcid_t                *mpo_proc_check_setlcid;
          mpo_proc_check_signal_t                 *mpo_proc_check_signal;
          mpo_proc_check_wait_t                   *mpo_proc_check_wait;
          mpo_proc_label_destroy_t                *mpo_proc_label_destroy;
          mpo_proc_label_init_t                   *mpo_proc_label_init;
          mpo_socket_check_accept_t               *mpo_socket_check_accept;
          mpo_socket_check_accepted_t             *mpo_socket_check_accepted;
          mpo_socket_check_bind_t                 *mpo_socket_check_bind;
          mpo_socket_check_connect_t              *mpo_socket_check_connect;
          mpo_socket_check_create_t               *mpo_socket_check_create;
          mpo_socket_check_deliver_t              *mpo_socket_check_deliver;
          mpo_socket_check_kqfilter_t             *mpo_socket_check_kqfilter;
          mpo_socket_check_label_update_t         *mpo_socket_check_label_update;
          mpo_socket_check_listen_t               *mpo_socket_check_listen;
          mpo_socket_check_receive_t              *mpo_socket_check_receive;
          mpo_socket_check_received_t             *mpo_socket_check_received;
          mpo_socket_check_select_t               *mpo_socket_check_select;
          mpo_socket_check_send_t                 *mpo_socket_check_send;
          mpo_socket_check_stat_t                 *mpo_socket_check_stat;
          mpo_socket_check_setsockopt_t           *mpo_socket_check_setsockopt;
          mpo_socket_check_getsockopt_t           *mpo_socket_check_getsockopt;
          mpo_socket_label_associate_accept_t     *mpo_socket_label_associate_accept;
          mpo_socket_label_associate_t            *mpo_socket_label_associate;
          mpo_socket_label_copy_t                 *mpo_socket_label_copy;
          mpo_socket_label_destroy_t              *mpo_socket_label_destroy;
          mpo_socket_label_externalize_t          *mpo_socket_label_externalize;
          mpo_socket_label_init_t                 *mpo_socket_label_init;
          mpo_socket_label_internalize_t          *mpo_socket_label_internalize;
          mpo_socket_label_update_t               *mpo_socket_label_update;
          mpo_socketpeer_label_associate_mbuf_t   *mpo_socketpeer_label_associate_mbuf;
          mpo_socketpeer_label_associate_socket_t *mpo_socketpeer_label_associate_socket;
          mpo_socketpeer_label_destroy_t          *mpo_socketpeer_label_destroy;
          mpo_socketpeer_label_externalize_t      *mpo_socketpeer_label_externalize;
          mpo_socketpeer_label_init_t             *mpo_socketpeer_label_init;
          mpo_system_check_acct_t                 *mpo_system_check_acct;
          mpo_system_check_audit_t                *mpo_system_check_audit;
          mpo_system_check_auditctl_t             *mpo_system_check_auditctl;
          mpo_system_check_auditon_t              *mpo_system_check_auditon;
          mpo_system_check_host_priv_t            *mpo_system_check_host_priv;
          mpo_system_check_nfsd_t                 *mpo_system_check_nfsd;
          mpo_system_check_reboot_t               *mpo_system_check_reboot;
          mpo_system_check_settime_t              *mpo_system_check_settime;
          mpo_system_check_swapoff_t              *mpo_system_check_swapoff;
          mpo_system_check_swapon_t               *mpo_system_check_swapon;
          mpo_system_check_sysctl_t               *mpo_system_check_sysctl;
          mpo_sysvmsg_label_associate_t           *mpo_sysvmsg_label_associate;
          mpo_sysvmsg_label_destroy_t             *mpo_sysvmsg_label_destroy;
          mpo_sysvmsg_label_init_t                *mpo_sysvmsg_label_init;
          mpo_sysvmsg_label_recycle_t             *mpo_sysvmsg_label_recycle;
          mpo_sysvmsq_check_enqueue_t             *mpo_sysvmsq_check_enqueue;
          mpo_sysvmsq_check_msgrcv_t              *mpo_sysvmsq_check_msgrcv;
          mpo_sysvmsq_check_msgrmid_t             *mpo_sysvmsq_check_msgrmid;
          mpo_sysvmsq_check_msqctl_t              *mpo_sysvmsq_check_msqctl;
          mpo_sysvmsq_check_msqget_t              *mpo_sysvmsq_check_msqget;
          mpo_sysvmsq_check_msqrcv_t              *mpo_sysvmsq_check_msqrcv;
          mpo_sysvmsq_check_msqsnd_t              *mpo_sysvmsq_check_msqsnd;
          mpo_sysvmsq_label_associate_t           *mpo_sysvmsq_label_associate;
          mpo_sysvmsq_label_destroy_t             *mpo_sysvmsq_label_destroy;
          mpo_sysvmsq_label_init_t                *mpo_sysvmsq_label_init;
          mpo_sysvmsq_label_recycle_t             *mpo_sysvmsq_label_recycle;
          mpo_sysvsem_check_semctl_t              *mpo_sysvsem_check_semctl;
          mpo_sysvsem_check_semget_t              *mpo_sysvsem_check_semget;
          mpo_sysvsem_check_semop_t               *mpo_sysvsem_check_semop;
          mpo_sysvsem_label_associate_t           *mpo_sysvsem_label_associate;
          mpo_sysvsem_label_destroy_t             *mpo_sysvsem_label_destroy;
          mpo_sysvsem_label_init_t                *mpo_sysvsem_label_init;
          mpo_sysvsem_label_recycle_t             *mpo_sysvsem_label_recycle;
          mpo_sysvshm_check_shmat_t               *mpo_sysvshm_check_shmat;
          mpo_sysvshm_check_shmctl_t              *mpo_sysvshm_check_shmctl;
          mpo_sysvshm_check_shmdt_t               *mpo_sysvshm_check_shmdt;
          mpo_sysvshm_check_shmget_t              *mpo_sysvshm_check_shmget;
          mpo_sysvshm_label_associate_t           *mpo_sysvshm_label_associate;
          mpo_sysvshm_label_destroy_t             *mpo_sysvshm_label_destroy;
          mpo_sysvshm_label_init_t                *mpo_sysvshm_label_init;
          mpo_sysvshm_label_recycle_t             *mpo_sysvshm_label_recycle;
          mpo_task_label_associate_kernel_t       *mpo_task_label_associate_kernel;
          mpo_task_label_associate_t              *mpo_task_label_associate;
          mpo_task_label_copy_t                   *mpo_task_label_copy;
          mpo_task_label_destroy_t                *mpo_task_label_destroy;
          mpo_task_label_externalize_t            *mpo_task_label_externalize;
          mpo_task_label_init_t                   *mpo_task_label_init;
          mpo_task_label_internalize_t            *mpo_task_label_internalize;
          mpo_task_label_update_t                 *mpo_task_label_update;
          mpo_thread_userret_t                    *mpo_thread_userret;
          mpo_vnode_check_access_t                *mpo_vnode_check_access;
          mpo_vnode_check_chdir_t                 *mpo_vnode_check_chdir;
          mpo_vnode_check_chroot_t                *mpo_vnode_check_chroot;
          mpo_vnode_check_create_t                *mpo_vnode_check_create;
          mpo_vnode_check_deleteextattr_t         *mpo_vnode_check_deleteextattr;
          mpo_vnode_check_exchangedata_t          *mpo_vnode_check_exchangedata;
          mpo_vnode_check_exec_t                  *mpo_vnode_check_exec;
          mpo_vnode_check_getattrlist_t           *mpo_vnode_check_getattrlist;
          mpo_vnode_check_getextattr_t            *mpo_vnode_check_getextattr;
          mpo_vnode_check_ioctl_t                 *mpo_vnode_check_ioctl;
          mpo_vnode_check_kqfilter_t              *mpo_vnode_check_kqfilter;
          mpo_vnode_check_label_update_t          *mpo_vnode_check_label_update;
          mpo_vnode_check_link_t                  *mpo_vnode_check_link;
          mpo_vnode_check_listextattr_t           *mpo_vnode_check_listextattr;
          mpo_vnode_check_lookup_t                *mpo_vnode_check_lookup;
          mpo_vnode_check_open_t                  *mpo_vnode_check_open;
          mpo_vnode_check_read_t                  *mpo_vnode_check_read;
          mpo_vnode_check_readdir_t               *mpo_vnode_check_readdir;
          mpo_vnode_check_readlink_t              *mpo_vnode_check_readlink;
          mpo_vnode_check_rename_from_t           *mpo_vnode_check_rename_from;
          mpo_vnode_check_rename_to_t             *mpo_vnode_check_rename_to;
          mpo_vnode_check_revoke_t                *mpo_vnode_check_revoke;
          mpo_vnode_check_select_t                *mpo_vnode_check_select;
          mpo_vnode_check_setattrlist_t           *mpo_vnode_check_setattrlist;
          mpo_vnode_check_setextattr_t            *mpo_vnode_check_setextattr;
          mpo_vnode_check_setflags_t              *mpo_vnode_check_setflags;
          mpo_vnode_check_setmode_t               *mpo_vnode_check_setmode;
          mpo_vnode_check_setowner_t              *mpo_vnode_check_setowner;
          mpo_vnode_check_setutimes_t             *mpo_vnode_check_setutimes;
          mpo_vnode_check_stat_t                  *mpo_vnode_check_stat;
          mpo_vnode_check_truncate_t              *mpo_vnode_check_truncate;
          mpo_vnode_check_unlink_t                *mpo_vnode_check_unlink;
          mpo_vnode_check_write_t                 *mpo_vnode_check_write;
          mpo_vnode_label_associate_devfs_t       *mpo_vnode_label_associate_devfs;
          mpo_vnode_label_associate_extattr_t     *mpo_vnode_label_associate_extattr;
          mpo_vnode_label_associate_file_t        *mpo_vnode_label_associate_file;
          mpo_vnode_label_associate_pipe_t        *mpo_vnode_label_associate_pipe;
          mpo_vnode_label_associate_posixsem_t    *mpo_vnode_label_associate_posixsem;
          mpo_vnode_label_associate_posixshm_t    *mpo_vnode_label_associate_posixshm;
          mpo_vnode_label_associate_singlelabel_t *mpo_vnode_label_associate_singlelabel;
          mpo_vnode_label_associate_socket_t      *mpo_vnode_label_associate_socket;
          mpo_vnode_label_copy_t                  *mpo_vnode_label_copy;
          mpo_vnode_label_destroy_t               *mpo_vnode_label_destroy;
          mpo_vnode_label_externalize_audit_t     *mpo_vnode_label_externalize_audit;
          mpo_vnode_label_externalize_t           *mpo_vnode_label_externalize;
          mpo_vnode_label_init_t                  *mpo_vnode_label_init;
          mpo_vnode_label_internalize_t           *mpo_vnode_label_internalize;
          mpo_vnode_label_recycle_t               *mpo_vnode_label_recycle;
          mpo_vnode_label_store_t                 *mpo_vnode_label_store;
          mpo_vnode_label_update_extattr_t        *mpo_vnode_label_update_extattr;
          mpo_vnode_label_update_t                *mpo_vnode_label_update;
          mpo_vnode_notify_create_t               *mpo_vnode_notify_create;
          mpo_vnode_check_signature_t             *mpo_vnode_check_signature;
          mpo_vnode_check_uipc_bind_t             *mpo_vnode_check_uipc_bind;
          mpo_vnode_check_uipc_connect_t          *mpo_vnode_check_uipc_connect;
          mac_proc_check_run_cs_invalid_t         *mpo_proc_check_run_cs_invalid;
          mpo_reserved_hook_t                     *mpo_reserved4;
          mpo_reserved_hook_t                     *mpo_reserved5;
          mpo_reserved_hook_t                     *mpo_reserved6;
          mpo_reserved_hook_t                     *mpo_reserved7;
          mpo_reserved_hook_t                     *mpo_reserved8;
          mpo_reserved_hook_t                     *mpo_reserved9;
  };
  
  /**
     @brief MAC policy handle type
  
     The MAC handle is used to uniquely identify a loaded policy within
     the MAC Framework.
  
     A variable of this type is set by mac_policy_register().
   */
  typedef unsigned int mac_policy_handle_t;
  
  #define mpc_t   struct mac_policy_conf *
  
  /**
    @brief Mac policy configuration
  
    This structure specifies the configuration information for a
    MAC policy module.  A policy module developer must supply
    a short unique policy name, a more descriptive full name, a list of label
    namespaces and count, a pointer to the registered enty point operations,
    any load time flags, and optionally, a pointer to a label slot identifier.
  
    The Framework will update the runtime flags (mpc_runtime_flags) to
    indicate that the module has been registered.
  
    If the label slot identifier (mpc_field_off) is NULL, the Framework
    will not provide label storage for the policy.  Otherwise, the
    Framework will store the label location (slot) in this field.
  
    The mpc_list field is used by the Framework and should not be
    modified by policies.
  */
  /* XXX - reorder these for better aligment on 64bit platforms */
  struct mac_policy_conf {
          const char              *mpc_name;              /** policy name */
          const char              *mpc_fullname;          /** full name */
          const char              **mpc_labelnames;       /** managed label namespaces */
          unsigned int             mpc_labelname_count;   /** number of managed label namespaces */
          struct mac_policy_ops   *mpc_ops;               /** operation vector */
          int                      mpc_loadtime_flags;    /** load time flags */
          int                     *mpc_field_off;         /** label slot */
          int                      mpc_runtime_flags;     /** run time flags */
          mpc_t                    mpc_list;              /** List reference */
          void                    *mpc_data;              /** module data */
  };
  
  /**
     @brief MAC policy module registration routine
  
     This function is called to register a policy with the
     MAC framework.  A policy module will typically call this from the
     Darwin KEXT registration routine.
   */
  int     mac_policy_register(struct mac_policy_conf *mpc,
      mac_policy_handle_t *handlep, void *xd);
  
  /**
     @brief MAC policy module de-registration routine
  
     This function is called to de-register a policy with theD
     MAC framework.  A policy module will typically call this from the
     Darwin KEXT de-registration routine.
   */
  int     mac_policy_unregister(mac_policy_handle_t handle);
  
  /*
   * Framework entry points for the policies to add audit data.
   */
  int     mac_audit_text(char *text, mac_policy_handle_t handle);
  
  /*
   * Calls to assist with use of Apple XATTRs within policy modules.
   */
  int     mac_vnop_setxattr(struct vnode *, const char *, char *, size_t);
  int     mac_vnop_getxattr(struct vnode *, const char *, char *, size_t,
                            size_t *);
  int     mac_vnop_removexattr(struct vnode *, const char *);
  
  /*
   * Arbitrary limit on how much data will be logged by the audit
   * entry points above.
   */
  #define MAC_AUDIT_DATA_LIMIT    1024
  
  /*
   * Values returned by mac_audit_{pre,post}select. To combine the responses
   * of the security policies into a single decision,
   * mac_audit_{pre,post}select() choose the greatest value returned.
   */
  #define MAC_AUDIT_DEFAULT       0       /* use system behavior */
  #define MAC_AUDIT_NO            1       /* force not auditing this event */
  #define MAC_AUDIT_YES           2       /* force auditing this event */
  
  //  \defgroup mpc_loadtime_flags Flags for the mpc_loadtime_flags field
  
  /**
    @name Flags for the mpc_loadtime_flags field
    @see mac_policy_conf
  
    This is the complete list of flags that are supported by the
    mpc_loadtime_flags field of the mac_policy_conf structure.  These
    flags specify the load time behavior of MAC Framework policy
    modules.
  */
  
  /*@{*/
  
  /**
    @brief Flag to indicate registration preference
  
    This flag indicates that the policy module must be loaded and
    initialized early in the boot process. If the flag is specified,
    attempts to register the module following boot will be rejected. The
    flag may be used by policies that require pervasive labeling of all
    system objects, and cannot handle objects that have not been
    properly initialized by the policy.
   */
  #define MPC_LOADTIME_FLAG_NOTLATE       0x00000001
  
  /**
    @brief Flag to indicate unload preference
  
    This flag indicates that the policy module may be unloaded. If this
    flag is not set, then the policy framework will reject requests to
    unload the module. This flag might be used by modules that allocate
    label state and are unable to free that state at runtime, or for
    modules that simply do not want to permit unload operations.
  */
  #define MPC_LOADTIME_FLAG_UNLOADOK      0x00000002
  
  /**
    @brief Unsupported
  
    XXX This flag is not yet supported.
  */
  #define MPC_LOADTIME_FLAG_LABELMBUFS    0x00000004
  
  /**
    @brief Flag to indicate a base policy
  
    This flag indicates that the policy module is a base policy. Only
    one module can declare itself as base, otherwise the boot process
    will be halted.
   */
  #define MPC_LOADTIME_BASE_POLICY        0x00000008
  
  /*@}*/
  
  /**
    @brief Policy registration flag
    @see mac_policy_conf
  
    This flag indicates that the policy module has been successfully
    registered with the TrustedBSD MAC Framework.  The Framework will
    set this flag in the mpc_runtime_flags field of the policy's
    mac_policy_conf structure after registering the policy.
   */
  #define MPC_RUNTIME_FLAG_REGISTERED     0x00000001
  
  /*
   * Depends on POLICY_VER
   */
  
  #ifndef POLICY_VER
  #define POLICY_VER      1.0
  #endif
  
  #define MAC_POLICY_SET(handle, mpops, mpname, mpfullname, lnames, lcount, slot, lflags, rflags) \
          static struct mac_policy_conf mpname##_mac_policy_conf = {      \
                  .mpc_name               = #mpname,                      \
                  .mpc_fullname           = mpfullname,                   \
                  .mpc_labelnames         = lnames,                       \
                  .mpc_labelname_count    = lcount,                       \
                  .mpc_ops                = mpops,                        \
                  .mpc_loadtime_flags     = lflags,                       \
                  .mpc_field_off          = slot,                         \
                  .mpc_runtime_flags      = rflags                        \
          };                                                              \
                                                                          \
          static kern_return_t                                            \
          kmod_start(kmod_info_t *ki, void *xd)                           \
          {                                                               \
                  return mac_policy_register(&mpname##_mac_policy_conf,   \
                      &handle, xd);                                       \
          }                                                               \
                                                                          \
          static kern_return_t                                            \
          kmod_stop(kmod_info_t *ki, void *xd)                            \
          {                                                               \
                  return mac_policy_unregister(handle);                   \
          }                                                               \
                                                                          \
          extern kern_return_t _start(kmod_info_t *ki, void *data);       \
          extern kern_return_t _stop(kmod_info_t *ki, void *data);        \
                                                                          \
          KMOD_EXPLICIT_DECL(security.mpname, POLICY_VER, _start, _stop)  \
          kmod_start_func_t *_realmain = kmod_start;                      \
          kmod_stop_func_t *_antimain = kmod_stop;                        \
          int _kext_apple_cc = __APPLE_CC__
  
  
  #define LABEL_TO_SLOT(l, s)     (l)->l_perpolicy[s]
  
  /*
   * Policy interface to map a struct label pointer to per-policy data.
   * Typically, policies wrap this in their own accessor macro that casts an
   * intptr_t to a policy-specific data type.
   */
  intptr_t        mac_label_get(struct label *l, int slot);
  void            mac_label_set(struct label *l, int slot, intptr_t v);
  
  #define mac_get_mpc(h)          (mac_policy_list.entries[h].mpc)
  
  /**
    @name Flags for MAC allocator interfaces
  
    These flags are passed to the Darwin kernel allocator routines to
    indicate whether the allocation is permitted to block or not.
    Caution should be taken; some operations are not permitted to sleep,
    and some types of locks cannot be held when sleeping.
   */
  
  /*@{*/
  
  /**
      @brief Allocation operations may block
  
      If memory is not immediately available, the allocation routine
      will block (typically sleeping) until memory is available.
  
      @warning Inappropriate use of this flag may cause kernel panics.
   */
  #define MAC_WAITOK  0
  
  /**
      @brief Allocation operations may not block
  
      Rather than blocking, the allocator may return an error if memory
      is not immediately available.  This type of allocation will not
      sleep, preserving locking semantics.
   */
  #define MAC_NOWAIT  1
  
  /*@}*/
  
  #endif /* !_SECURITY_MAC_POLICY_H_ */