FreeBSD/Linux Kernel Cross Reference
sys/security/mac/mac_vfs.c

     /*-
      * Copyright (c) 1999-2002 Robert N. M. Watson
      * Copyright (c) 2001 Ilmar S. Habibulin
      * Copyright (c) 2001-2005 McAfee, Inc.
      * Copyright (c) 2005-2006 SPARTA, Inc.
      * All rights reserved.
      *
      * This software was developed by Robert Watson and Ilmar Habibulin for the
      * TrustedBSD Project.
     *
     * This software was developed for the FreeBSD Project in part by McAfee
     * Research, the Security Research Division of McAfee, 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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_mac.h"
    
    #include <sys/param.h>
    #include <sys/condvar.h>
    #include <sys/extattr.h>
    #include <sys/imgact.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/sbuf.h>
    #include <sys/systm.h>
    #include <sys/vnode.h>
    #include <sys/mount.h>
    #include <sys/file.h>
    #include <sys/namei.h>
    #include <sys/sysctl.h>
    
    #include <vm/vm.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_object.h>
    
    #include <fs/devfs/devfs.h>
    
    #include <security/mac/mac_framework.h>
    #include <security/mac/mac_internal.h>
    #include <security/mac/mac_policy.h>
    
    /*
     * Warn about EA transactions only the first time they happen.  No locking on
     * this variable.
     */
    static int      ea_warn_once = 0;
    
    static int      mac_setlabel_vnode_extattr(struct ucred *cred,
                        struct vnode *vp, struct label *intlabel);
    
    static struct label *
    mac_devfs_label_alloc(void)
    {
            struct label *label;
    
            label = mac_labelzone_alloc(M_WAITOK);
            MAC_PERFORM(init_devfs_label, label);
            return (label);
    }
    
    void
    mac_init_devfs(struct devfs_dirent *de)
    {
    
            de->de_label = mac_devfs_label_alloc();
    }
    
   static struct label *
   mac_mount_label_alloc(void)
   {
           struct label *label;
   
           label = mac_labelzone_alloc(M_WAITOK);
           MAC_PERFORM(init_mount_label, label);
           return (label);
   }
   
   void
   mac_init_mount(struct mount *mp)
   {
   
           mp->mnt_label = mac_mount_label_alloc();
   }
   
   struct label *
   mac_vnode_label_alloc(void)
   {
           struct label *label;
   
           label = mac_labelzone_alloc(M_WAITOK);
           MAC_PERFORM(init_vnode_label, label);
           return (label);
   }
   
   void
   mac_init_vnode(struct vnode *vp)
   {
   
           vp->v_label = mac_vnode_label_alloc();
   }
   
   static void
   mac_devfs_label_free(struct label *label)
   {
   
           MAC_PERFORM(destroy_devfs_label, label);
           mac_labelzone_free(label);
   }
   
   void
   mac_destroy_devfs(struct devfs_dirent *de)
   {
   
           mac_devfs_label_free(de->de_label);
           de->de_label = NULL;
   }
   
   static void
   mac_mount_label_free(struct label *label)
   {
   
           MAC_PERFORM(destroy_mount_label, label);
           mac_labelzone_free(label);
   }
   
   void
   mac_destroy_mount(struct mount *mp)
   {
   
           mac_mount_label_free(mp->mnt_label);
           mp->mnt_label = NULL;
   }
   
   void
   mac_vnode_label_free(struct label *label)
   {
   
           MAC_PERFORM(destroy_vnode_label, label);
           mac_labelzone_free(label);
   }
   
   void
   mac_destroy_vnode(struct vnode *vp)
   {
   
           mac_vnode_label_free(vp->v_label);
           vp->v_label = NULL;
   }
   
   void
   mac_copy_vnode_label(struct label *src, struct label *dest)
   {
   
           MAC_PERFORM(copy_vnode_label, src, dest);
   }
   
   int
   mac_externalize_vnode_label(struct label *label, char *elements,
       char *outbuf, size_t outbuflen)
   {
           int error;
   
           MAC_EXTERNALIZE(vnode, label, elements, outbuf, outbuflen);
   
           return (error);
   }
   
   int
   mac_internalize_vnode_label(struct label *label, char *string)
   {
           int error;
   
           MAC_INTERNALIZE(vnode, label, string);
   
           return (error);
   }
   
   void
   mac_update_devfs(struct mount *mp, struct devfs_dirent *de, struct vnode *vp)
   {
   
           MAC_PERFORM(update_devfs, mp, de, de->de_label, vp, vp->v_label);
   }
   
   void
   mac_associate_vnode_devfs(struct mount *mp, struct devfs_dirent *de,
       struct vnode *vp)
   {
   
           MAC_PERFORM(associate_vnode_devfs, mp, mp->mnt_label, de,
               de->de_label, vp, vp->v_label);
   }
   
   int
   mac_associate_vnode_extattr(struct mount *mp, struct vnode *vp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_associate_vnode_extattr");
   
           MAC_CHECK(associate_vnode_extattr, mp, mp->mnt_label, vp,
               vp->v_label);
   
           return (error);
   }
   
   void
   mac_associate_vnode_singlelabel(struct mount *mp, struct vnode *vp)
   {
   
           MAC_PERFORM(associate_vnode_singlelabel, mp, mp->mnt_label, vp,
               vp->v_label);
   }
   
   /*
    * Functions implementing extended-attribute backed labels for file systems
    * that support it.
    *
    * Where possible, we use EA transactions to make writes to multiple
    * attributes across difference policies mutually atomic.  We allow work to
    * continue on file systems not supporting EA transactions, but generate a
    * printf warning.
    */
   int
   mac_create_vnode_extattr(struct ucred *cred, struct mount *mp,
       struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_create_vnode_extattr");
           ASSERT_VOP_LOCKED(vp, "mac_create_vnode_extattr");
   
           error = VOP_OPENEXTATTR(vp, cred, curthread);
           if (error == EOPNOTSUPP) {
                   if (ea_warn_once == 0) {
                           printf("Warning: transactions not supported "
                               "in EA write.\n");
                           ea_warn_once = 1;
                   }
           } else if (error)
                   return (error);
   
           MAC_CHECK(create_vnode_extattr, cred, mp, mp->mnt_label, dvp,
               dvp->v_label, vp, vp->v_label, cnp);
   
           if (error) {
                   VOP_CLOSEEXTATTR(vp, 0, NOCRED, curthread);
                   return (error);
           }
   
           error = VOP_CLOSEEXTATTR(vp, 1, NOCRED, curthread);
           if (error == EOPNOTSUPP)
                   error = 0;
   
           return (error);
   }
   
   static int
   mac_setlabel_vnode_extattr(struct ucred *cred, struct vnode *vp,
       struct label *intlabel)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_setlabel_vnode_extattr");
   
           error = VOP_OPENEXTATTR(vp, cred, curthread);
           if (error == EOPNOTSUPP) {
                   if (ea_warn_once == 0) {
                           printf("Warning: transactions not supported "
                               "in EA write.\n");
                           ea_warn_once = 1;
                   }
           } else if (error)
                   return (error);
   
           MAC_CHECK(setlabel_vnode_extattr, cred, vp, vp->v_label, intlabel);
   
           if (error) {
                   VOP_CLOSEEXTATTR(vp, 0, NOCRED, curthread);
                   return (error);
           }
   
           error = VOP_CLOSEEXTATTR(vp, 1, NOCRED, curthread);
           if (error == EOPNOTSUPP)
                   error = 0;
   
           return (error);
   }
   
   void
   mac_execve_transition(struct ucred *old, struct ucred *new, struct vnode *vp,
       struct label *interpvnodelabel, struct image_params *imgp)
   {
   
           ASSERT_VOP_LOCKED(vp, "mac_execve_transition");
   
           MAC_PERFORM(execve_transition, old, new, vp, vp->v_label,
               interpvnodelabel, imgp, imgp->execlabel);
   }
   
   int
   mac_execve_will_transition(struct ucred *old, struct vnode *vp,
       struct label *interpvnodelabel, struct image_params *imgp)
   {
           int result;
   
           ASSERT_VOP_LOCKED(vp, "mac_execve_will_transition");
   
           result = 0;
           MAC_BOOLEAN(execve_will_transition, ||, old, vp, vp->v_label,
               interpvnodelabel, imgp, imgp->execlabel);
   
           return (result);
   }
   
   int
   mac_check_vnode_access(struct ucred *cred, struct vnode *vp, int acc_mode)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_access");
   
           MAC_CHECK(check_vnode_access, cred, vp, vp->v_label, acc_mode);
           return (error);
   }
   
   int
   mac_check_vnode_chdir(struct ucred *cred, struct vnode *dvp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_chdir");
   
           MAC_CHECK(check_vnode_chdir, cred, dvp, dvp->v_label);
           return (error);
   }
   
   int
   mac_check_vnode_chroot(struct ucred *cred, struct vnode *dvp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_chroot");
   
           MAC_CHECK(check_vnode_chroot, cred, dvp, dvp->v_label);
           return (error);
   }
   
   int
   mac_check_vnode_create(struct ucred *cred, struct vnode *dvp,
       struct componentname *cnp, struct vattr *vap)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_create");
   
           MAC_CHECK(check_vnode_create, cred, dvp, dvp->v_label, cnp, vap);
           return (error);
   }
   
   int
   mac_check_vnode_deleteacl(struct ucred *cred, struct vnode *vp,
       acl_type_t type)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_deleteacl");
   
           MAC_CHECK(check_vnode_deleteacl, cred, vp, vp->v_label, type);
           return (error);
   }
   
   int
   mac_check_vnode_deleteextattr(struct ucred *cred, struct vnode *vp,
       int attrnamespace, const char *name)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_deleteextattr");
   
           MAC_CHECK(check_vnode_deleteextattr, cred, vp, vp->v_label,
               attrnamespace, name);
           return (error);
   }
   
   int
   mac_check_vnode_exec(struct ucred *cred, struct vnode *vp,
       struct image_params *imgp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_exec");
   
           MAC_CHECK(check_vnode_exec, cred, vp, vp->v_label, imgp,
               imgp->execlabel);
   
           return (error);
   }
   
   int
   mac_check_vnode_getacl(struct ucred *cred, struct vnode *vp, acl_type_t type)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_getacl");
   
           MAC_CHECK(check_vnode_getacl, cred, vp, vp->v_label, type);
           return (error);
   }
   
   int
   mac_check_vnode_getextattr(struct ucred *cred, struct vnode *vp,
       int attrnamespace, const char *name, struct uio *uio)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_getextattr");
   
           MAC_CHECK(check_vnode_getextattr, cred, vp, vp->v_label,
               attrnamespace, name, uio);
           return (error);
   }
   
   int
   mac_check_vnode_link(struct ucred *cred, struct vnode *dvp,
       struct vnode *vp, struct componentname *cnp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_link");
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_link");
   
           MAC_CHECK(check_vnode_link, cred, dvp, dvp->v_label, vp,
               vp->v_label, cnp);
           return (error);
   }
   
   int
   mac_check_vnode_listextattr(struct ucred *cred, struct vnode *vp,
       int attrnamespace)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_listextattr");
   
           MAC_CHECK(check_vnode_listextattr, cred, vp, vp->v_label,
               attrnamespace);
           return (error);
   }
   
   int
   mac_check_vnode_lookup(struct ucred *cred, struct vnode *dvp,
       struct componentname *cnp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_lookup");
   
           MAC_CHECK(check_vnode_lookup, cred, dvp, dvp->v_label, cnp);
           return (error);
   }
   
   int
   mac_check_vnode_mmap(struct ucred *cred, struct vnode *vp,
       int prot, int flags)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_mmap");
   
           MAC_CHECK(check_vnode_mmap, cred, vp, vp->v_label, prot, flags);
           return (error);
   }
   
   void
   mac_check_vnode_mmap_downgrade(struct ucred *cred, struct vnode *vp, int *prot)
   {
           int result = *prot;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_mmap_downgrade");
   
           MAC_PERFORM(check_vnode_mmap_downgrade, cred, vp, vp->v_label,
               &result);
   
           *prot = result;
   }
   
   int
   mac_check_vnode_mprotect(struct ucred *cred, struct vnode *vp, int prot)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_mprotect");
   
           MAC_CHECK(check_vnode_mprotect, cred, vp, vp->v_label, prot);
           return (error);
   }
   
   int
   mac_check_vnode_open(struct ucred *cred, struct vnode *vp, int acc_mode)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_open");
   
           MAC_CHECK(check_vnode_open, cred, vp, vp->v_label, acc_mode);
           return (error);
   }
   
   int
   mac_check_vnode_poll(struct ucred *active_cred, struct ucred *file_cred,
       struct vnode *vp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_poll");
   
           MAC_CHECK(check_vnode_poll, active_cred, file_cred, vp,
               vp->v_label);
   
           return (error);
   }
   
   int
   mac_check_vnode_read(struct ucred *active_cred, struct ucred *file_cred,
       struct vnode *vp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_read");
   
           MAC_CHECK(check_vnode_read, active_cred, file_cred, vp,
               vp->v_label);
   
           return (error);
   }
   
   int
   mac_check_vnode_readdir(struct ucred *cred, struct vnode *dvp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_readdir");
   
           MAC_CHECK(check_vnode_readdir, cred, dvp, dvp->v_label);
           return (error);
   }
   
   int
   mac_check_vnode_readlink(struct ucred *cred, struct vnode *vp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_readlink");
   
           MAC_CHECK(check_vnode_readlink, cred, vp, vp->v_label);
           return (error);
   }
   
   static int
   mac_check_vnode_relabel(struct ucred *cred, struct vnode *vp,
       struct label *newlabel)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_relabel");
   
           MAC_CHECK(check_vnode_relabel, cred, vp, vp->v_label, newlabel);
   
           return (error);
   }
   
   int
   mac_check_vnode_rename_from(struct ucred *cred, struct vnode *dvp,
       struct vnode *vp, struct componentname *cnp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_rename_from");
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_rename_from");
   
           MAC_CHECK(check_vnode_rename_from, cred, dvp, dvp->v_label, vp,
               vp->v_label, cnp);
           return (error);
   }
   
   int
   mac_check_vnode_rename_to(struct ucred *cred, struct vnode *dvp,
       struct vnode *vp, int samedir, struct componentname *cnp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_rename_to");
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_rename_to");
   
           MAC_CHECK(check_vnode_rename_to, cred, dvp, dvp->v_label, vp,
               vp != NULL ? vp->v_label : NULL, samedir, cnp);
           return (error);
   }
   
   int
   mac_check_vnode_revoke(struct ucred *cred, struct vnode *vp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_revoke");
   
           MAC_CHECK(check_vnode_revoke, cred, vp, vp->v_label);
           return (error);
   }
   
   int
   mac_check_vnode_setacl(struct ucred *cred, struct vnode *vp, acl_type_t type,
       struct acl *acl)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_setacl");
   
           MAC_CHECK(check_vnode_setacl, cred, vp, vp->v_label, type, acl);
           return (error);
   }
   
   int
   mac_check_vnode_setextattr(struct ucred *cred, struct vnode *vp,
       int attrnamespace, const char *name, struct uio *uio)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_setextattr");
   
           MAC_CHECK(check_vnode_setextattr, cred, vp, vp->v_label,
               attrnamespace, name, uio);
           return (error);
   }
   
   int
   mac_check_vnode_setflags(struct ucred *cred, struct vnode *vp, u_long flags)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_setflags");
   
           MAC_CHECK(check_vnode_setflags, cred, vp, vp->v_label, flags);
           return (error);
   }
   
   int
   mac_check_vnode_setmode(struct ucred *cred, struct vnode *vp, mode_t mode)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_setmode");
   
           MAC_CHECK(check_vnode_setmode, cred, vp, vp->v_label, mode);
           return (error);
   }
   
   int
   mac_check_vnode_setowner(struct ucred *cred, struct vnode *vp, uid_t uid,
       gid_t gid)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_setowner");
   
           MAC_CHECK(check_vnode_setowner, cred, vp, vp->v_label, uid, gid);
           return (error);
   }
   
   int
   mac_check_vnode_setutimes(struct ucred *cred, struct vnode *vp,
       struct timespec atime, struct timespec mtime)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_setutimes");
   
           MAC_CHECK(check_vnode_setutimes, cred, vp, vp->v_label, atime,
               mtime);
           return (error);
   }
   
   int
   mac_check_vnode_stat(struct ucred *active_cred, struct ucred *file_cred,
       struct vnode *vp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_stat");
   
           MAC_CHECK(check_vnode_stat, active_cred, file_cred, vp,
               vp->v_label);
           return (error);
   }
   
   int
   mac_check_vnode_unlink(struct ucred *cred, struct vnode *dvp, struct vnode *vp,
       struct componentname *cnp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(dvp, "mac_check_vnode_unlink");
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_unlink");
   
           MAC_CHECK(check_vnode_unlink, cred, dvp, dvp->v_label, vp,
               vp->v_label, cnp);
           return (error);
   }
   
   int
   mac_check_vnode_write(struct ucred *active_cred, struct ucred *file_cred,
       struct vnode *vp)
   {
           int error;
   
           ASSERT_VOP_LOCKED(vp, "mac_check_vnode_write");
   
           MAC_CHECK(check_vnode_write, active_cred, file_cred, vp,
               vp->v_label);
   
           return (error);
   }
   
   void
   mac_relabel_vnode(struct ucred *cred, struct vnode *vp, struct label *newlabel)
   {
   
           MAC_PERFORM(relabel_vnode, cred, vp, vp->v_label, newlabel);
   }
   
   void
   mac_create_mount(struct ucred *cred, struct mount *mp)
   {
   
           MAC_PERFORM(create_mount, cred, mp, mp->mnt_label);
   }
   
   int
   mac_check_mount_stat(struct ucred *cred, struct mount *mount)
   {
           int error;
   
           MAC_CHECK(check_mount_stat, cred, mount, mount->mnt_label);
   
           return (error);
   }
   
   void
   mac_create_devfs_device(struct ucred *cred, struct mount *mp,
       struct cdev *dev, struct devfs_dirent *de)
   {
   
           MAC_PERFORM(create_devfs_device, cred, mp, dev, de, de->de_label);
   }
   
   void
   mac_create_devfs_symlink(struct ucred *cred, struct mount *mp,
       struct devfs_dirent *dd, struct devfs_dirent *de)
   {
   
           MAC_PERFORM(create_devfs_symlink, cred, mp, dd, dd->de_label, de,
               de->de_label);
   }
   
   void
   mac_create_devfs_directory(struct mount *mp, char *dirname, int dirnamelen,
       struct devfs_dirent *de)
   {
   
           MAC_PERFORM(create_devfs_directory, mp, dirname, dirnamelen, de,
               de->de_label);
   }
   
   /*
    * Implementation of VOP_SETLABEL() that relies on extended attributes
    * to store label data.  Can be referenced by filesystems supporting
    * extended attributes.
    */
   int
   vop_stdsetlabel_ea(struct vop_setlabel_args *ap)
   {
           struct vnode *vp = ap->a_vp;
           struct label *intlabel = ap->a_label;
           int error;
   
           ASSERT_VOP_LOCKED(vp, "vop_stdsetlabel_ea");
   
           if ((vp->v_mount->mnt_flag & MNT_MULTILABEL) == 0)
                   return (EOPNOTSUPP);
   
           error = mac_setlabel_vnode_extattr(ap->a_cred, vp, intlabel);
           if (error)
                   return (error);
   
           mac_relabel_vnode(ap->a_cred, vp, intlabel);
   
           return (0);
   }
   
   int
   vn_setlabel(struct vnode *vp, struct label *intlabel, struct ucred *cred)
   {
           int error;
   
           if (vp->v_mount == NULL) {
                   /* printf("vn_setlabel: null v_mount\n"); */
                   if (vp->v_type != VNON)
                           printf("vn_setlabel: null v_mount with non-VNON\n");
                   return (EBADF);
           }
   
           if ((vp->v_mount->mnt_flag & MNT_MULTILABEL) == 0)
                   return (EOPNOTSUPP);
   
           /*
            * Multi-phase commit.  First check the policies to confirm the
            * change is OK.  Then commit via the filesystem.  Finally, update
            * the actual vnode label.
            *
            * Question: maybe the filesystem should update the vnode at the end
            * as part of VOP_SETLABEL()?
            */
           error = mac_check_vnode_relabel(cred, vp, intlabel);
           if (error)
                   return (error);
   
           /*
            * VADMIN provides the opportunity for the filesystem to make
            * decisions about who is and is not able to modify labels and
            * protections on files.  This might not be right.  We can't assume
            * VOP_SETLABEL() will do it, because we might implement that as
            * part of vop_stdsetlabel_ea().
            */
           error = VOP_ACCESS(vp, VADMIN, cred, curthread);
           if (error)
                   return (error);
   
           error = VOP_SETLABEL(vp, intlabel, cred, curthread);
           if (error)
                   return (error);
   
           return (0);
   }
   
   /*
    * When a thread becomes an NFS server daemon, its credential may need to be
    * updated to reflect this so that policies can recognize when file system
    * operations originate from the network.
    *
    * At some point, it would be desirable if the credential used for each NFS
    * RPC could be set based on the RPC context (i.e., source system, etc) to
    * provide more fine-grained access control.
    */
   void
   mac_associate_nfsd_label(struct ucred *cred)
   {
   
           MAC_PERFORM(associate_nfsd_label, cred);
   }

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