FreeBSD/Linux Kernel Cross Reference
sys/security/commoncap.c

     /* Common capabilities, needed by capability.o.
      *
      *      This program is free software; you can redistribute it and/or modify
      *      it under the terms of the GNU General Public License as published by
      *      the Free Software Foundation; either version 2 of the License, or
      *      (at your option) any later version.
      *
      */
     
    #include <linux/capability.h>
    #include <linux/audit.h>
    #include <linux/module.h>
    #include <linux/init.h>
    #include <linux/kernel.h>
    #include <linux/security.h>
    #include <linux/file.h>
    #include <linux/mm.h>
    #include <linux/mman.h>
    #include <linux/pagemap.h>
    #include <linux/swap.h>
    #include <linux/skbuff.h>
    #include <linux/netlink.h>
    #include <linux/ptrace.h>
    #include <linux/xattr.h>
    #include <linux/hugetlb.h>
    #include <linux/mount.h>
    #include <linux/sched.h>
    #include <linux/prctl.h>
    #include <linux/securebits.h>
    #include <linux/user_namespace.h>
    #include <linux/binfmts.h>
    #include <linux/personality.h>
    
    /*
     * If a non-root user executes a setuid-root binary in
     * !secure(SECURE_NOROOT) mode, then we raise capabilities.
     * However if fE is also set, then the intent is for only
     * the file capabilities to be applied, and the setuid-root
     * bit is left on either to change the uid (plausible) or
     * to get full privilege on a kernel without file capabilities
     * support.  So in that case we do not raise capabilities.
     *
     * Warn if that happens, once per boot.
     */
    static void warn_setuid_and_fcaps_mixed(const char *fname)
    {
            static int warned;
            if (!warned) {
                    printk(KERN_INFO "warning: `%s' has both setuid-root and"
                            " effective capabilities. Therefore not raising all"
                            " capabilities.\n", fname);
                    warned = 1;
            }
    }
    
    int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
    {
            return 0;
    }
    
    /**
     * cap_capable - Determine whether a task has a particular effective capability
     * @cred: The credentials to use
     * @ns:  The user namespace in which we need the capability
     * @cap: The capability to check for
     * @audit: Whether to write an audit message or not
     *
     * Determine whether the nominated task has the specified capability amongst
     * its effective set, returning 0 if it does, -ve if it does not.
     *
     * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
     * and has_capability() functions.  That is, it has the reverse semantics:
     * cap_has_capability() returns 0 when a task has a capability, but the
     * kernel's capable() and has_capability() returns 1 for this case.
     */
    int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
                    int cap, int audit)
    {
            struct user_namespace *ns = targ_ns;
    
            /* See if cred has the capability in the target user namespace
             * by examining the target user namespace and all of the target
             * user namespace's parents.
             */
            for (;;) {
                    /* Do we have the necessary capabilities? */
                    if (ns == cred->user_ns)
                            return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
    
                    /* Have we tried all of the parent namespaces? */
                    if (ns == &init_user_ns)
                            return -EPERM;
    
                    /* 
                     * The owner of the user namespace in the parent of the
                     * user namespace has all caps.
                     */
                    if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
                            return 0;
   
                   /*
                    * If you have a capability in a parent user ns, then you have
                    * it over all children user namespaces as well.
                    */
                   ns = ns->parent;
           }
   
           /* We never get here */
   }
   
   /**
    * cap_settime - Determine whether the current process may set the system clock
    * @ts: The time to set
    * @tz: The timezone to set
    *
    * Determine whether the current process may set the system clock and timezone
    * information, returning 0 if permission granted, -ve if denied.
    */
   int cap_settime(const struct timespec *ts, const struct timezone *tz)
   {
           if (!capable(CAP_SYS_TIME))
                   return -EPERM;
           return 0;
   }
   
   /**
    * cap_ptrace_access_check - Determine whether the current process may access
    *                         another
    * @child: The process to be accessed
    * @mode: The mode of attachment.
    *
    * If we are in the same or an ancestor user_ns and have all the target
    * task's capabilities, then ptrace access is allowed.
    * If we have the ptrace capability to the target user_ns, then ptrace
    * access is allowed.
    * Else denied.
    *
    * Determine whether a process may access another, returning 0 if permission
    * granted, -ve if denied.
    */
   int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
   {
           int ret = 0;
           const struct cred *cred, *child_cred;
   
           rcu_read_lock();
           cred = current_cred();
           child_cred = __task_cred(child);
           if (cred->user_ns == child_cred->user_ns &&
               cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
                   goto out;
           if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
                   goto out;
           ret = -EPERM;
   out:
           rcu_read_unlock();
           return ret;
   }
   
   /**
    * cap_ptrace_traceme - Determine whether another process may trace the current
    * @parent: The task proposed to be the tracer
    *
    * If parent is in the same or an ancestor user_ns and has all current's
    * capabilities, then ptrace access is allowed.
    * If parent has the ptrace capability to current's user_ns, then ptrace
    * access is allowed.
    * Else denied.
    *
    * Determine whether the nominated task is permitted to trace the current
    * process, returning 0 if permission is granted, -ve if denied.
    */
   int cap_ptrace_traceme(struct task_struct *parent)
   {
           int ret = 0;
           const struct cred *cred, *child_cred;
   
           rcu_read_lock();
           cred = __task_cred(parent);
           child_cred = current_cred();
           if (cred->user_ns == child_cred->user_ns &&
               cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
                   goto out;
           if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
                   goto out;
           ret = -EPERM;
   out:
           rcu_read_unlock();
           return ret;
   }
   
   /**
    * cap_capget - Retrieve a task's capability sets
    * @target: The task from which to retrieve the capability sets
    * @effective: The place to record the effective set
    * @inheritable: The place to record the inheritable set
    * @permitted: The place to record the permitted set
    *
    * This function retrieves the capabilities of the nominated task and returns
    * them to the caller.
    */
   int cap_capget(struct task_struct *target, kernel_cap_t *effective,
                  kernel_cap_t *inheritable, kernel_cap_t *permitted)
   {
           const struct cred *cred;
   
           /* Derived from kernel/capability.c:sys_capget. */
           rcu_read_lock();
           cred = __task_cred(target);
           *effective   = cred->cap_effective;
           *inheritable = cred->cap_inheritable;
           *permitted   = cred->cap_permitted;
           rcu_read_unlock();
           return 0;
   }
   
   /*
    * Determine whether the inheritable capabilities are limited to the old
    * permitted set.  Returns 1 if they are limited, 0 if they are not.
    */
   static inline int cap_inh_is_capped(void)
   {
   
           /* they are so limited unless the current task has the CAP_SETPCAP
            * capability
            */
           if (cap_capable(current_cred(), current_cred()->user_ns,
                           CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
                   return 0;
           return 1;
   }
   
   /**
    * cap_capset - Validate and apply proposed changes to current's capabilities
    * @new: The proposed new credentials; alterations should be made here
    * @old: The current task's current credentials
    * @effective: A pointer to the proposed new effective capabilities set
    * @inheritable: A pointer to the proposed new inheritable capabilities set
    * @permitted: A pointer to the proposed new permitted capabilities set
    *
    * This function validates and applies a proposed mass change to the current
    * process's capability sets.  The changes are made to the proposed new
    * credentials, and assuming no error, will be committed by the caller of LSM.
    */
   int cap_capset(struct cred *new,
                  const struct cred *old,
                  const kernel_cap_t *effective,
                  const kernel_cap_t *inheritable,
                  const kernel_cap_t *permitted)
   {
           if (cap_inh_is_capped() &&
               !cap_issubset(*inheritable,
                             cap_combine(old->cap_inheritable,
                                         old->cap_permitted)))
                   /* incapable of using this inheritable set */
                   return -EPERM;
   
           if (!cap_issubset(*inheritable,
                             cap_combine(old->cap_inheritable,
                                         old->cap_bset)))
                   /* no new pI capabilities outside bounding set */
                   return -EPERM;
   
           /* verify restrictions on target's new Permitted set */
           if (!cap_issubset(*permitted, old->cap_permitted))
                   return -EPERM;
   
           /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
           if (!cap_issubset(*effective, *permitted))
                   return -EPERM;
   
           new->cap_effective   = *effective;
           new->cap_inheritable = *inheritable;
           new->cap_permitted   = *permitted;
           return 0;
   }
   
   /*
    * Clear proposed capability sets for execve().
    */
   static inline void bprm_clear_caps(struct linux_binprm *bprm)
   {
           cap_clear(bprm->cred->cap_permitted);
           bprm->cap_effective = false;
   }
   
   /**
    * cap_inode_need_killpriv - Determine if inode change affects privileges
    * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
    *
    * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
    * affects the security markings on that inode, and if it is, should
    * inode_killpriv() be invoked or the change rejected?
    *
    * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and
    * -ve to deny the change.
    */
   int cap_inode_need_killpriv(struct dentry *dentry)
   {
           struct inode *inode = dentry->d_inode;
           int error;
   
           if (!inode->i_op->getxattr)
                  return 0;
   
           error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
           if (error <= 0)
                   return 0;
           return 1;
   }
   
   /**
    * cap_inode_killpriv - Erase the security markings on an inode
    * @dentry: The inode/dentry to alter
    *
    * Erase the privilege-enhancing security markings on an inode.
    *
    * Returns 0 if successful, -ve on error.
    */
   int cap_inode_killpriv(struct dentry *dentry)
   {
           struct inode *inode = dentry->d_inode;
   
           if (!inode->i_op->removexattr)
                  return 0;
   
           return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
   }
   
   /*
    * Calculate the new process capability sets from the capability sets attached
    * to a file.
    */
   static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
                                             struct linux_binprm *bprm,
                                             bool *effective,
                                             bool *has_cap)
   {
           struct cred *new = bprm->cred;
           unsigned i;
           int ret = 0;
   
           if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
                   *effective = true;
   
           if (caps->magic_etc & VFS_CAP_REVISION_MASK)
                   *has_cap = true;
   
           CAP_FOR_EACH_U32(i) {
                   __u32 permitted = caps->permitted.cap[i];
                   __u32 inheritable = caps->inheritable.cap[i];
   
                   /*
                    * pP' = (X & fP) | (pI & fI)
                    */
                   new->cap_permitted.cap[i] =
                           (new->cap_bset.cap[i] & permitted) |
                           (new->cap_inheritable.cap[i] & inheritable);
   
                   if (permitted & ~new->cap_permitted.cap[i])
                           /* insufficient to execute correctly */
                           ret = -EPERM;
           }
   
           /*
            * For legacy apps, with no internal support for recognizing they
            * do not have enough capabilities, we return an error if they are
            * missing some "forced" (aka file-permitted) capabilities.
            */
           return *effective ? ret : 0;
   }
   
   /*
    * Extract the on-exec-apply capability sets for an executable file.
    */
   int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
   {
           struct inode *inode = dentry->d_inode;
           __u32 magic_etc;
           unsigned tocopy, i;
           int size;
           struct vfs_cap_data caps;
   
           memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
   
           if (!inode || !inode->i_op->getxattr)
                   return -ENODATA;
   
           size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
                                      XATTR_CAPS_SZ);
           if (size == -ENODATA || size == -EOPNOTSUPP)
                   /* no data, that's ok */
                   return -ENODATA;
           if (size < 0)
                   return size;
   
           if (size < sizeof(magic_etc))
                   return -EINVAL;
   
           cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
   
           switch (magic_etc & VFS_CAP_REVISION_MASK) {
           case VFS_CAP_REVISION_1:
                   if (size != XATTR_CAPS_SZ_1)
                           return -EINVAL;
                   tocopy = VFS_CAP_U32_1;
                   break;
           case VFS_CAP_REVISION_2:
                   if (size != XATTR_CAPS_SZ_2)
                           return -EINVAL;
                   tocopy = VFS_CAP_U32_2;
                   break;
           default:
                   return -EINVAL;
           }
   
           CAP_FOR_EACH_U32(i) {
                   if (i >= tocopy)
                           break;
                   cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
                   cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
           }
   
           return 0;
   }
   
   /*
    * Attempt to get the on-exec apply capability sets for an executable file from
    * its xattrs and, if present, apply them to the proposed credentials being
    * constructed by execve().
    */
   static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_cap)
   {
           struct dentry *dentry;
           int rc = 0;
           struct cpu_vfs_cap_data vcaps;
   
           bprm_clear_caps(bprm);
   
           if (!file_caps_enabled)
                   return 0;
   
           if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
                   return 0;
   
           dentry = dget(bprm->file->f_dentry);
   
           rc = get_vfs_caps_from_disk(dentry, &vcaps);
           if (rc < 0) {
                   if (rc == -EINVAL)
                           printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
                                   __func__, rc, bprm->filename);
                   else if (rc == -ENODATA)
                           rc = 0;
                   goto out;
           }
   
           rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap);
           if (rc == -EINVAL)
                   printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
                          __func__, rc, bprm->filename);
   
   out:
           dput(dentry);
           if (rc)
                   bprm_clear_caps(bprm);
   
           return rc;
   }
   
   /**
    * cap_bprm_set_creds - Set up the proposed credentials for execve().
    * @bprm: The execution parameters, including the proposed creds
    *
    * Set up the proposed credentials for a new execution context being
    * constructed by execve().  The proposed creds in @bprm->cred is altered,
    * which won't take effect immediately.  Returns 0 if successful, -ve on error.
    */
   int cap_bprm_set_creds(struct linux_binprm *bprm)
   {
           const struct cred *old = current_cred();
           struct cred *new = bprm->cred;
           bool effective, has_cap = false;
           int ret;
           kuid_t root_uid;
   
           effective = false;
           ret = get_file_caps(bprm, &effective, &has_cap);
           if (ret < 0)
                   return ret;
   
           root_uid = make_kuid(new->user_ns, 0);
   
           if (!issecure(SECURE_NOROOT)) {
                   /*
                    * If the legacy file capability is set, then don't set privs
                    * for a setuid root binary run by a non-root user.  Do set it
                    * for a root user just to cause least surprise to an admin.
                    */
                   if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) {
                           warn_setuid_and_fcaps_mixed(bprm->filename);
                           goto skip;
                   }
                   /*
                    * To support inheritance of root-permissions and suid-root
                    * executables under compatibility mode, we override the
                    * capability sets for the file.
                    *
                    * If only the real uid is 0, we do not set the effective bit.
                    */
                   if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) {
                           /* pP' = (cap_bset & ~0) | (pI & ~0) */
                           new->cap_permitted = cap_combine(old->cap_bset,
                                                            old->cap_inheritable);
                   }
                   if (uid_eq(new->euid, root_uid))
                           effective = true;
           }
   skip:
   
           /* if we have fs caps, clear dangerous personality flags */
           if (!cap_issubset(new->cap_permitted, old->cap_permitted))
                   bprm->per_clear |= PER_CLEAR_ON_SETID;
   
   
           /* Don't let someone trace a set[ug]id/setpcap binary with the revised
            * credentials unless they have the appropriate permit.
            *
            * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
            */
           if ((!uid_eq(new->euid, old->uid) ||
                !gid_eq(new->egid, old->gid) ||
                !cap_issubset(new->cap_permitted, old->cap_permitted)) &&
               bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
                   /* downgrade; they get no more than they had, and maybe less */
                   if (!capable(CAP_SETUID) ||
                       (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
                           new->euid = new->uid;
                           new->egid = new->gid;
                   }
                   new->cap_permitted = cap_intersect(new->cap_permitted,
                                                      old->cap_permitted);
           }
   
           new->suid = new->fsuid = new->euid;
           new->sgid = new->fsgid = new->egid;
   
           if (effective)
                   new->cap_effective = new->cap_permitted;
           else
                   cap_clear(new->cap_effective);
           bprm->cap_effective = effective;
   
           /*
            * Audit candidate if current->cap_effective is set
            *
            * We do not bother to audit if 3 things are true:
            *   1) cap_effective has all caps
            *   2) we are root
            *   3) root is supposed to have all caps (SECURE_NOROOT)
            * Since this is just a normal root execing a process.
            *
            * Number 1 above might fail if you don't have a full bset, but I think
            * that is interesting information to audit.
            */
           if (!cap_isclear(new->cap_effective)) {
                   if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
                       !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) ||
                       issecure(SECURE_NOROOT)) {
                           ret = audit_log_bprm_fcaps(bprm, new, old);
                           if (ret < 0)
                                   return ret;
                   }
           }
   
           new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
           return 0;
   }
   
   /**
    * cap_bprm_secureexec - Determine whether a secure execution is required
    * @bprm: The execution parameters
    *
    * Determine whether a secure execution is required, return 1 if it is, and 0
    * if it is not.
    *
    * The credentials have been committed by this point, and so are no longer
    * available through @bprm->cred.
    */
   int cap_bprm_secureexec(struct linux_binprm *bprm)
   {
           const struct cred *cred = current_cred();
           kuid_t root_uid = make_kuid(cred->user_ns, 0);
   
           if (!uid_eq(cred->uid, root_uid)) {
                   if (bprm->cap_effective)
                           return 1;
                   if (!cap_isclear(cred->cap_permitted))
                           return 1;
           }
   
           return (!uid_eq(cred->euid, cred->uid) ||
                   !gid_eq(cred->egid, cred->gid));
   }
   
   /**
    * cap_inode_setxattr - Determine whether an xattr may be altered
    * @dentry: The inode/dentry being altered
    * @name: The name of the xattr to be changed
    * @value: The value that the xattr will be changed to
    * @size: The size of value
    * @flags: The replacement flag
    *
    * Determine whether an xattr may be altered or set on an inode, returning 0 if
    * permission is granted, -ve if denied.
    *
    * This is used to make sure security xattrs don't get updated or set by those
    * who aren't privileged to do so.
    */
   int cap_inode_setxattr(struct dentry *dentry, const char *name,
                          const void *value, size_t size, int flags)
   {
           if (!strcmp(name, XATTR_NAME_CAPS)) {
                   if (!capable(CAP_SETFCAP))
                           return -EPERM;
                   return 0;
           }
   
           if (!strncmp(name, XATTR_SECURITY_PREFIX,
                        sizeof(XATTR_SECURITY_PREFIX) - 1) &&
               !capable(CAP_SYS_ADMIN))
                   return -EPERM;
           return 0;
   }
   
   /**
    * cap_inode_removexattr - Determine whether an xattr may be removed
    * @dentry: The inode/dentry being altered
    * @name: The name of the xattr to be changed
    *
    * Determine whether an xattr may be removed from an inode, returning 0 if
    * permission is granted, -ve if denied.
    *
    * This is used to make sure security xattrs don't get removed by those who
    * aren't privileged to remove them.
    */
   int cap_inode_removexattr(struct dentry *dentry, const char *name)
   {
           if (!strcmp(name, XATTR_NAME_CAPS)) {
                   if (!capable(CAP_SETFCAP))
                           return -EPERM;
                   return 0;
           }
   
           if (!strncmp(name, XATTR_SECURITY_PREFIX,
                        sizeof(XATTR_SECURITY_PREFIX) - 1) &&
               !capable(CAP_SYS_ADMIN))
                   return -EPERM;
           return 0;
   }
   
   /*
    * cap_emulate_setxuid() fixes the effective / permitted capabilities of
    * a process after a call to setuid, setreuid, or setresuid.
    *
    *  1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
    *  {r,e,s}uid != 0, the permitted and effective capabilities are
    *  cleared.
    *
    *  2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
    *  capabilities of the process are cleared.
    *
    *  3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
    *  capabilities are set to the permitted capabilities.
    *
    *  fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
    *  never happen.
    *
    *  -astor
    *
    * cevans - New behaviour, Oct '99
    * A process may, via prctl(), elect to keep its capabilities when it
    * calls setuid() and switches away from uid==0. Both permitted and
    * effective sets will be retained.
    * Without this change, it was impossible for a daemon to drop only some
    * of its privilege. The call to setuid(!=0) would drop all privileges!
    * Keeping uid 0 is not an option because uid 0 owns too many vital
    * files..
    * Thanks to Olaf Kirch and Peter Benie for spotting this.
    */
   static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
   {
           kuid_t root_uid = make_kuid(old->user_ns, 0);
   
           if ((uid_eq(old->uid, root_uid) ||
                uid_eq(old->euid, root_uid) ||
                uid_eq(old->suid, root_uid)) &&
               (!uid_eq(new->uid, root_uid) &&
                !uid_eq(new->euid, root_uid) &&
                !uid_eq(new->suid, root_uid)) &&
               !issecure(SECURE_KEEP_CAPS)) {
                   cap_clear(new->cap_permitted);
                   cap_clear(new->cap_effective);
           }
           if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
                   cap_clear(new->cap_effective);
           if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
                   new->cap_effective = new->cap_permitted;
   }
   
   /**
    * cap_task_fix_setuid - Fix up the results of setuid() call
    * @new: The proposed credentials
    * @old: The current task's current credentials
    * @flags: Indications of what has changed
    *
    * Fix up the results of setuid() call before the credential changes are
    * actually applied, returning 0 to grant the changes, -ve to deny them.
    */
   int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
   {
           switch (flags) {
           case LSM_SETID_RE:
           case LSM_SETID_ID:
           case LSM_SETID_RES:
                   /* juggle the capabilities to follow [RES]UID changes unless
                    * otherwise suppressed */
                   if (!issecure(SECURE_NO_SETUID_FIXUP))
                           cap_emulate_setxuid(new, old);
                   break;
   
           case LSM_SETID_FS:
                   /* juggle the capabilties to follow FSUID changes, unless
                    * otherwise suppressed
                    *
                    * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
                    *          if not, we might be a bit too harsh here.
                    */
                   if (!issecure(SECURE_NO_SETUID_FIXUP)) {
                           kuid_t root_uid = make_kuid(old->user_ns, 0);
                           if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
                                   new->cap_effective =
                                           cap_drop_fs_set(new->cap_effective);
   
                           if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
                                   new->cap_effective =
                                           cap_raise_fs_set(new->cap_effective,
                                                            new->cap_permitted);
                   }
                   break;
   
           default:
                   return -EINVAL;
           }
   
           return 0;
   }
   
   /*
    * Rationale: code calling task_setscheduler, task_setioprio, and
    * task_setnice, assumes that
    *   . if capable(cap_sys_nice), then those actions should be allowed
    *   . if not capable(cap_sys_nice), but acting on your own processes,
    *      then those actions should be allowed
    * This is insufficient now since you can call code without suid, but
    * yet with increased caps.
    * So we check for increased caps on the target process.
    */
   static int cap_safe_nice(struct task_struct *p)
   {
           int is_subset;
   
           rcu_read_lock();
           is_subset = cap_issubset(__task_cred(p)->cap_permitted,
                                    current_cred()->cap_permitted);
           rcu_read_unlock();
   
           if (!is_subset && !capable(CAP_SYS_NICE))
                   return -EPERM;
           return 0;
   }
   
   /**
    * cap_task_setscheduler - Detemine if scheduler policy change is permitted
    * @p: The task to affect
    *
    * Detemine if the requested scheduler policy change is permitted for the
    * specified task, returning 0 if permission is granted, -ve if denied.
    */
   int cap_task_setscheduler(struct task_struct *p)
   {
           return cap_safe_nice(p);
   }
   
   /**
    * cap_task_ioprio - Detemine if I/O priority change is permitted
    * @p: The task to affect
    * @ioprio: The I/O priority to set
    *
    * Detemine if the requested I/O priority change is permitted for the specified
    * task, returning 0 if permission is granted, -ve if denied.
    */
   int cap_task_setioprio(struct task_struct *p, int ioprio)
   {
           return cap_safe_nice(p);
   }
   
   /**
    * cap_task_ioprio - Detemine if task priority change is permitted
    * @p: The task to affect
    * @nice: The nice value to set
    *
    * Detemine if the requested task priority change is permitted for the
    * specified task, returning 0 if permission is granted, -ve if denied.
    */
   int cap_task_setnice(struct task_struct *p, int nice)
   {
           return cap_safe_nice(p);
   }
   
   /*
    * Implement PR_CAPBSET_DROP.  Attempt to remove the specified capability from
    * the current task's bounding set.  Returns 0 on success, -ve on error.
    */
   static long cap_prctl_drop(struct cred *new, unsigned long cap)
   {
           if (!capable(CAP_SETPCAP))
                   return -EPERM;
           if (!cap_valid(cap))
                   return -EINVAL;
   
           cap_lower(new->cap_bset, cap);
           return 0;
   }
   
   /**
    * cap_task_prctl - Implement process control functions for this security module
    * @option: The process control function requested
    * @arg2, @arg3, @arg4, @arg5: The argument data for this function
    *
    * Allow process control functions (sys_prctl()) to alter capabilities; may
    * also deny access to other functions not otherwise implemented here.
    *
    * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
    * here, other -ve on error.  If -ENOSYS is returned, sys_prctl() and other LSM
    * modules will consider performing the function.
    */
   int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
                      unsigned long arg4, unsigned long arg5)
   {
           struct cred *new;
           long error = 0;
   
           new = prepare_creds();
           if (!new)
                   return -ENOMEM;
   
           switch (option) {
           case PR_CAPBSET_READ:
                   error = -EINVAL;
                   if (!cap_valid(arg2))
                           goto error;
                   error = !!cap_raised(new->cap_bset, arg2);
                   goto no_change;
   
           case PR_CAPBSET_DROP:
                   error = cap_prctl_drop(new, arg2);
                   if (error < 0)
                           goto error;
                   goto changed;
   
           /*
            * The next four prctl's remain to assist with transitioning a
            * system from legacy UID=0 based privilege (when filesystem
            * capabilities are not in use) to a system using filesystem
            * capabilities only - as the POSIX.1e draft intended.
            *
            * Note:
            *
            *  PR_SET_SECUREBITS =
            *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
            *    | issecure_mask(SECURE_NOROOT)
            *    | issecure_mask(SECURE_NOROOT_LOCKED)
            *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
            *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
            *
            * will ensure that the current process and all of its
            * children will be locked into a pure
            * capability-based-privilege environment.
            */
           case PR_SET_SECUREBITS:
                   error = -EPERM;
                   if ((((new->securebits & SECURE_ALL_LOCKS) >> 1)
                        & (new->securebits ^ arg2))                        /*[1]*/
                       || ((new->securebits & SECURE_ALL_LOCKS & ~arg2))   /*[2]*/
                       || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))   /*[3]*/
                       || (cap_capable(current_cred(),
                                       current_cred()->user_ns, CAP_SETPCAP,
                                       SECURITY_CAP_AUDIT) != 0)           /*[4]*/
                           /*
                            * [1] no changing of bits that are locked
                            * [2] no unlocking of locks
                            * [3] no setting of unsupported bits
                            * [4] doing anything requires privilege (go read about
                            *     the "sendmail capabilities bug")
                            */
                       )
                           /* cannot change a locked bit */
                           goto error;
                   new->securebits = arg2;
                   goto changed;
   
           case PR_GET_SECUREBITS:
                   error = new->securebits;
                   goto no_change;
   
           case PR_GET_KEEPCAPS:
                   if (issecure(SECURE_KEEP_CAPS))
                           error = 1;
                   goto no_change;
   
           case PR_SET_KEEPCAPS:
                   error = -EINVAL;
                   if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
                           goto error;
                   error = -EPERM;
                   if (issecure(SECURE_KEEP_CAPS_LOCKED))
                           goto error;
                   if (arg2)
                           new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
                   else
                           new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
                   goto changed;
   
           default:
                   /* No functionality available - continue with default */
                   error = -ENOSYS;
                   goto error;
           }
   
           /* Functionality provided */
   changed:
           return commit_creds(new);
   
   no_change:
   error:
           abort_creds(new);
           return error;
   }
   
   /**
    * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
    * @mm: The VM space in which the new mapping is to be made
    * @pages: The size of the mapping
    *
    * Determine whether the allocation of a new virtual mapping by the current
    * task is permitted, returning 0 if permission is granted, -ve if not.
    */
   int cap_vm_enough_memory(struct mm_struct *mm, long pages)
   {
           int cap_sys_admin = 0;
   
           if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
                           SECURITY_CAP_NOAUDIT) == 0)
                   cap_sys_admin = 1;
           return __vm_enough_memory(mm, pages, cap_sys_admin);
   }
   
   /*
    * cap_mmap_addr - check if able to map given addr
    * @addr: address attempting to be mapped
    *
    * If the process is attempting to map memory below dac_mmap_min_addr they need
    * CAP_SYS_RAWIO.  The other parameters to this function are unused by the
    * capability security module.  Returns 0 if this mapping should be allowed
    * -EPERM if not.
    */
   int cap_mmap_addr(unsigned long addr)
   {
           int ret = 0;
   
           if (addr < dac_mmap_min_addr) {
                   ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
                                     SECURITY_CAP_AUDIT);
                   /* set PF_SUPERPRIV if it turns out we allow the low mmap */
                   if (ret == 0)
                           current->flags |= PF_SUPERPRIV;
           }
           return ret;
   }
   
   int cap_mmap_file(struct file *file, unsigned long reqprot,
                     unsigned long prot, unsigned long flags)
   {
           return 0;
   }

Cache object: 8b8b7348ed527d8ce8ba3652ec375516