1 /* Common capabilities, needed by capability.o.
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
10 #include <linux/capability.h>
11 #include <linux/audit.h>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/lsm_hooks.h>
16 #include <linux/file.h>
18 #include <linux/mman.h>
19 #include <linux/pagemap.h>
20 #include <linux/swap.h>
21 #include <linux/skbuff.h>
22 #include <linux/netlink.h>
23 #include <linux/ptrace.h>
24 #include <linux/xattr.h>
25 #include <linux/hugetlb.h>
26 #include <linux/mount.h>
27 #include <linux/sched.h>
28 #include <linux/prctl.h>
29 #include <linux/securebits.h>
30 #include <linux/user_namespace.h>
31 #include <linux/binfmts.h>
32 #include <linux/personality.h>
34 #ifdef CONFIG_ANDROID_PARANOID_NETWORK
35 #include <linux/android_aid.h>
39 * If a non-root user executes a setuid-root binary in
40 * !secure(SECURE_NOROOT) mode, then we raise capabilities.
41 * However if fE is also set, then the intent is for only
42 * the file capabilities to be applied, and the setuid-root
43 * bit is left on either to change the uid (plausible) or
44 * to get full privilege on a kernel without file capabilities
45 * support. So in that case we do not raise capabilities.
47 * Warn if that happens, once per boot.
49 static void warn_setuid_and_fcaps_mixed(const char *fname)
53 printk(KERN_INFO "warning: `%s' has both setuid-root and"
54 " effective capabilities. Therefore not raising all"
55 " capabilities.\n", fname);
61 * cap_capable - Determine whether a task has a particular effective capability
62 * @cred: The credentials to use
63 * @ns: The user namespace in which we need the capability
64 * @cap: The capability to check for
65 * @audit: Whether to write an audit message or not
67 * Determine whether the nominated task has the specified capability amongst
68 * its effective set, returning 0 if it does, -ve if it does not.
70 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
71 * and has_capability() functions. That is, it has the reverse semantics:
72 * cap_has_capability() returns 0 when a task has a capability, but the
73 * kernel's capable() and has_capability() returns 1 for this case.
75 int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
78 struct user_namespace *ns = targ_ns;
80 #ifdef CONFIG_ANDROID_PARANOID_NETWORK
81 if (cap == CAP_NET_RAW && in_egroup_p(AID_NET_RAW))
83 if (cap == CAP_NET_ADMIN && in_egroup_p(AID_NET_ADMIN))
87 /* See if cred has the capability in the target user namespace
88 * by examining the target user namespace and all of the target
89 * user namespace's parents.
92 /* Do we have the necessary capabilities? */
93 if (ns == cred->user_ns)
94 return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
96 /* Have we tried all of the parent namespaces? */
97 if (ns == &init_user_ns)
101 * The owner of the user namespace in the parent of the
102 * user namespace has all caps.
104 if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
108 * If you have a capability in a parent user ns, then you have
109 * it over all children user namespaces as well.
114 /* We never get here */
118 * cap_settime - Determine whether the current process may set the system clock
119 * @ts: The time to set
120 * @tz: The timezone to set
122 * Determine whether the current process may set the system clock and timezone
123 * information, returning 0 if permission granted, -ve if denied.
125 int cap_settime(const struct timespec *ts, const struct timezone *tz)
127 if (!capable(CAP_SYS_TIME))
133 * cap_ptrace_access_check - Determine whether the current process may access
135 * @child: The process to be accessed
136 * @mode: The mode of attachment.
138 * If we are in the same or an ancestor user_ns and have all the target
139 * task's capabilities, then ptrace access is allowed.
140 * If we have the ptrace capability to the target user_ns, then ptrace
144 * Determine whether a process may access another, returning 0 if permission
145 * granted, -ve if denied.
147 int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
150 const struct cred *cred, *child_cred;
153 cred = current_cred();
154 child_cred = __task_cred(child);
155 if (cred->user_ns == child_cred->user_ns &&
156 cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
158 if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
167 * cap_ptrace_traceme - Determine whether another process may trace the current
168 * @parent: The task proposed to be the tracer
170 * If parent is in the same or an ancestor user_ns and has all current's
171 * capabilities, then ptrace access is allowed.
172 * If parent has the ptrace capability to current's user_ns, then ptrace
176 * Determine whether the nominated task is permitted to trace the current
177 * process, returning 0 if permission is granted, -ve if denied.
179 int cap_ptrace_traceme(struct task_struct *parent)
182 const struct cred *cred, *child_cred;
185 cred = __task_cred(parent);
186 child_cred = current_cred();
187 if (cred->user_ns == child_cred->user_ns &&
188 cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
190 if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
199 * cap_capget - Retrieve a task's capability sets
200 * @target: The task from which to retrieve the capability sets
201 * @effective: The place to record the effective set
202 * @inheritable: The place to record the inheritable set
203 * @permitted: The place to record the permitted set
205 * This function retrieves the capabilities of the nominated task and returns
206 * them to the caller.
208 int cap_capget(struct task_struct *target, kernel_cap_t *effective,
209 kernel_cap_t *inheritable, kernel_cap_t *permitted)
211 const struct cred *cred;
213 /* Derived from kernel/capability.c:sys_capget. */
215 cred = __task_cred(target);
216 *effective = cred->cap_effective;
217 *inheritable = cred->cap_inheritable;
218 *permitted = cred->cap_permitted;
224 * Determine whether the inheritable capabilities are limited to the old
225 * permitted set. Returns 1 if they are limited, 0 if they are not.
227 static inline int cap_inh_is_capped(void)
230 /* they are so limited unless the current task has the CAP_SETPCAP
233 if (cap_capable(current_cred(), current_cred()->user_ns,
234 CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
240 * cap_capset - Validate and apply proposed changes to current's capabilities
241 * @new: The proposed new credentials; alterations should be made here
242 * @old: The current task's current credentials
243 * @effective: A pointer to the proposed new effective capabilities set
244 * @inheritable: A pointer to the proposed new inheritable capabilities set
245 * @permitted: A pointer to the proposed new permitted capabilities set
247 * This function validates and applies a proposed mass change to the current
248 * process's capability sets. The changes are made to the proposed new
249 * credentials, and assuming no error, will be committed by the caller of LSM.
251 int cap_capset(struct cred *new,
252 const struct cred *old,
253 const kernel_cap_t *effective,
254 const kernel_cap_t *inheritable,
255 const kernel_cap_t *permitted)
257 if (cap_inh_is_capped() &&
258 !cap_issubset(*inheritable,
259 cap_combine(old->cap_inheritable,
260 old->cap_permitted)))
261 /* incapable of using this inheritable set */
264 if (!cap_issubset(*inheritable,
265 cap_combine(old->cap_inheritable,
267 /* no new pI capabilities outside bounding set */
270 /* verify restrictions on target's new Permitted set */
271 if (!cap_issubset(*permitted, old->cap_permitted))
274 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
275 if (!cap_issubset(*effective, *permitted))
278 new->cap_effective = *effective;
279 new->cap_inheritable = *inheritable;
280 new->cap_permitted = *permitted;
283 * Mask off ambient bits that are no longer both permitted and
286 new->cap_ambient = cap_intersect(new->cap_ambient,
287 cap_intersect(*permitted,
289 if (WARN_ON(!cap_ambient_invariant_ok(new)))
295 * Clear proposed capability sets for execve().
297 static inline void bprm_clear_caps(struct linux_binprm *bprm)
299 cap_clear(bprm->cred->cap_permitted);
300 bprm->cap_effective = false;
304 * cap_inode_need_killpriv - Determine if inode change affects privileges
305 * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
307 * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
308 * affects the security markings on that inode, and if it is, should
309 * inode_killpriv() be invoked or the change rejected?
311 * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and
312 * -ve to deny the change.
314 int cap_inode_need_killpriv(struct dentry *dentry)
316 struct inode *inode = d_backing_inode(dentry);
319 if (!inode->i_op->getxattr)
322 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
329 * cap_inode_killpriv - Erase the security markings on an inode
330 * @dentry: The inode/dentry to alter
332 * Erase the privilege-enhancing security markings on an inode.
334 * Returns 0 if successful, -ve on error.
336 int cap_inode_killpriv(struct dentry *dentry)
338 struct inode *inode = d_backing_inode(dentry);
340 if (!inode->i_op->removexattr)
343 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
347 * Calculate the new process capability sets from the capability sets attached
350 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
351 struct linux_binprm *bprm,
355 struct cred *new = bprm->cred;
359 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
362 if (caps->magic_etc & VFS_CAP_REVISION_MASK)
365 CAP_FOR_EACH_U32(i) {
366 __u32 permitted = caps->permitted.cap[i];
367 __u32 inheritable = caps->inheritable.cap[i];
370 * pP' = (X & fP) | (pI & fI)
371 * The addition of pA' is handled later.
373 new->cap_permitted.cap[i] =
374 (new->cap_bset.cap[i] & permitted) |
375 (new->cap_inheritable.cap[i] & inheritable);
377 if (permitted & ~new->cap_permitted.cap[i])
378 /* insufficient to execute correctly */
383 * For legacy apps, with no internal support for recognizing they
384 * do not have enough capabilities, we return an error if they are
385 * missing some "forced" (aka file-permitted) capabilities.
387 return *effective ? ret : 0;
391 * Extract the on-exec-apply capability sets for an executable file.
393 int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
395 struct inode *inode = d_backing_inode(dentry);
399 struct vfs_cap_data caps;
401 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
403 if (!inode || !inode->i_op->getxattr)
406 size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
408 if (size == -ENODATA || size == -EOPNOTSUPP)
409 /* no data, that's ok */
414 if (size < sizeof(magic_etc))
417 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
419 switch (magic_etc & VFS_CAP_REVISION_MASK) {
420 case VFS_CAP_REVISION_1:
421 if (size != XATTR_CAPS_SZ_1)
423 tocopy = VFS_CAP_U32_1;
425 case VFS_CAP_REVISION_2:
426 if (size != XATTR_CAPS_SZ_2)
428 tocopy = VFS_CAP_U32_2;
434 CAP_FOR_EACH_U32(i) {
437 cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
438 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
441 cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
442 cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
448 * Attempt to get the on-exec apply capability sets for an executable file from
449 * its xattrs and, if present, apply them to the proposed credentials being
450 * constructed by execve().
452 static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_cap)
455 struct cpu_vfs_cap_data vcaps;
457 bprm_clear_caps(bprm);
459 if (!file_caps_enabled)
462 if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
465 rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
468 printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
469 __func__, rc, bprm->filename);
470 else if (rc == -ENODATA)
475 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap);
477 printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
478 __func__, rc, bprm->filename);
482 bprm_clear_caps(bprm);
488 * cap_bprm_set_creds - Set up the proposed credentials for execve().
489 * @bprm: The execution parameters, including the proposed creds
491 * Set up the proposed credentials for a new execution context being
492 * constructed by execve(). The proposed creds in @bprm->cred is altered,
493 * which won't take effect immediately. Returns 0 if successful, -ve on error.
495 int cap_bprm_set_creds(struct linux_binprm *bprm)
497 const struct cred *old = current_cred();
498 struct cred *new = bprm->cred;
499 bool effective, has_cap = false, is_setid;
503 if (WARN_ON(!cap_ambient_invariant_ok(old)))
507 ret = get_file_caps(bprm, &effective, &has_cap);
511 root_uid = make_kuid(new->user_ns, 0);
513 if (!issecure(SECURE_NOROOT)) {
515 * If the legacy file capability is set, then don't set privs
516 * for a setuid root binary run by a non-root user. Do set it
517 * for a root user just to cause least surprise to an admin.
519 if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) {
520 warn_setuid_and_fcaps_mixed(bprm->filename);
524 * To support inheritance of root-permissions and suid-root
525 * executables under compatibility mode, we override the
526 * capability sets for the file.
528 * If only the real uid is 0, we do not set the effective bit.
530 if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) {
531 /* pP' = (cap_bset & ~0) | (pI & ~0) */
532 new->cap_permitted = cap_combine(old->cap_bset,
533 old->cap_inheritable);
535 if (uid_eq(new->euid, root_uid))
540 /* if we have fs caps, clear dangerous personality flags */
541 if (!cap_issubset(new->cap_permitted, old->cap_permitted))
542 bprm->per_clear |= PER_CLEAR_ON_SETID;
545 /* Don't let someone trace a set[ug]id/setpcap binary with the revised
546 * credentials unless they have the appropriate permit.
548 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
550 is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid);
553 !cap_issubset(new->cap_permitted, old->cap_permitted)) &&
554 bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
555 /* downgrade; they get no more than they had, and maybe less */
556 if (!capable(CAP_SETUID) ||
557 (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
558 new->euid = new->uid;
559 new->egid = new->gid;
561 new->cap_permitted = cap_intersect(new->cap_permitted,
565 new->suid = new->fsuid = new->euid;
566 new->sgid = new->fsgid = new->egid;
568 /* File caps or setid cancels ambient. */
569 if (has_cap || is_setid)
570 cap_clear(new->cap_ambient);
573 * Now that we've computed pA', update pP' to give:
574 * pP' = (X & fP) | (pI & fI) | pA'
576 new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
579 * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set,
580 * this is the same as pE' = (fE ? pP' : 0) | pA'.
583 new->cap_effective = new->cap_permitted;
585 new->cap_effective = new->cap_ambient;
587 if (WARN_ON(!cap_ambient_invariant_ok(new)))
590 bprm->cap_effective = effective;
593 * Audit candidate if current->cap_effective is set
595 * We do not bother to audit if 3 things are true:
596 * 1) cap_effective has all caps
598 * 3) root is supposed to have all caps (SECURE_NOROOT)
599 * Since this is just a normal root execing a process.
601 * Number 1 above might fail if you don't have a full bset, but I think
602 * that is interesting information to audit.
604 if (!cap_issubset(new->cap_effective, new->cap_ambient)) {
605 if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
606 !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) ||
607 issecure(SECURE_NOROOT)) {
608 ret = audit_log_bprm_fcaps(bprm, new, old);
614 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
616 if (WARN_ON(!cap_ambient_invariant_ok(new)))
623 * cap_bprm_secureexec - Determine whether a secure execution is required
624 * @bprm: The execution parameters
626 * Determine whether a secure execution is required, return 1 if it is, and 0
629 * The credentials have been committed by this point, and so are no longer
630 * available through @bprm->cred.
632 int cap_bprm_secureexec(struct linux_binprm *bprm)
634 const struct cred *cred = current_cred();
635 kuid_t root_uid = make_kuid(cred->user_ns, 0);
637 if (!uid_eq(cred->uid, root_uid)) {
638 if (bprm->cap_effective)
640 if (!cap_issubset(cred->cap_permitted, cred->cap_ambient))
644 return (!uid_eq(cred->euid, cred->uid) ||
645 !gid_eq(cred->egid, cred->gid));
649 * cap_inode_setxattr - Determine whether an xattr may be altered
650 * @dentry: The inode/dentry being altered
651 * @name: The name of the xattr to be changed
652 * @value: The value that the xattr will be changed to
653 * @size: The size of value
654 * @flags: The replacement flag
656 * Determine whether an xattr may be altered or set on an inode, returning 0 if
657 * permission is granted, -ve if denied.
659 * This is used to make sure security xattrs don't get updated or set by those
660 * who aren't privileged to do so.
662 int cap_inode_setxattr(struct dentry *dentry, const char *name,
663 const void *value, size_t size, int flags)
665 if (!strcmp(name, XATTR_NAME_CAPS)) {
666 if (!capable(CAP_SETFCAP))
671 if (!strncmp(name, XATTR_SECURITY_PREFIX,
672 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
673 !capable(CAP_SYS_ADMIN))
679 * cap_inode_removexattr - Determine whether an xattr may be removed
680 * @dentry: The inode/dentry being altered
681 * @name: The name of the xattr to be changed
683 * Determine whether an xattr may be removed from an inode, returning 0 if
684 * permission is granted, -ve if denied.
686 * This is used to make sure security xattrs don't get removed by those who
687 * aren't privileged to remove them.
689 int cap_inode_removexattr(struct dentry *dentry, const char *name)
691 if (!strcmp(name, XATTR_NAME_CAPS)) {
692 if (!capable(CAP_SETFCAP))
697 if (!strncmp(name, XATTR_SECURITY_PREFIX,
698 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
699 !capable(CAP_SYS_ADMIN))
705 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
706 * a process after a call to setuid, setreuid, or setresuid.
708 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
709 * {r,e,s}uid != 0, the permitted and effective capabilities are
712 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
713 * capabilities of the process are cleared.
715 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
716 * capabilities are set to the permitted capabilities.
718 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
723 * cevans - New behaviour, Oct '99
724 * A process may, via prctl(), elect to keep its capabilities when it
725 * calls setuid() and switches away from uid==0. Both permitted and
726 * effective sets will be retained.
727 * Without this change, it was impossible for a daemon to drop only some
728 * of its privilege. The call to setuid(!=0) would drop all privileges!
729 * Keeping uid 0 is not an option because uid 0 owns too many vital
731 * Thanks to Olaf Kirch and Peter Benie for spotting this.
733 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
735 kuid_t root_uid = make_kuid(old->user_ns, 0);
737 if ((uid_eq(old->uid, root_uid) ||
738 uid_eq(old->euid, root_uid) ||
739 uid_eq(old->suid, root_uid)) &&
740 (!uid_eq(new->uid, root_uid) &&
741 !uid_eq(new->euid, root_uid) &&
742 !uid_eq(new->suid, root_uid))) {
743 if (!issecure(SECURE_KEEP_CAPS)) {
744 cap_clear(new->cap_permitted);
745 cap_clear(new->cap_effective);
749 * Pre-ambient programs expect setresuid to nonroot followed
750 * by exec to drop capabilities. We should make sure that
751 * this remains the case.
753 cap_clear(new->cap_ambient);
755 if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
756 cap_clear(new->cap_effective);
757 if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
758 new->cap_effective = new->cap_permitted;
762 * cap_task_fix_setuid - Fix up the results of setuid() call
763 * @new: The proposed credentials
764 * @old: The current task's current credentials
765 * @flags: Indications of what has changed
767 * Fix up the results of setuid() call before the credential changes are
768 * actually applied, returning 0 to grant the changes, -ve to deny them.
770 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
776 /* juggle the capabilities to follow [RES]UID changes unless
777 * otherwise suppressed */
778 if (!issecure(SECURE_NO_SETUID_FIXUP))
779 cap_emulate_setxuid(new, old);
783 /* juggle the capabilties to follow FSUID changes, unless
784 * otherwise suppressed
786 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
787 * if not, we might be a bit too harsh here.
789 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
790 kuid_t root_uid = make_kuid(old->user_ns, 0);
791 if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
793 cap_drop_fs_set(new->cap_effective);
795 if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
797 cap_raise_fs_set(new->cap_effective,
810 * Rationale: code calling task_setscheduler, task_setioprio, and
811 * task_setnice, assumes that
812 * . if capable(cap_sys_nice), then those actions should be allowed
813 * . if not capable(cap_sys_nice), but acting on your own processes,
814 * then those actions should be allowed
815 * This is insufficient now since you can call code without suid, but
816 * yet with increased caps.
817 * So we check for increased caps on the target process.
819 static int cap_safe_nice(struct task_struct *p)
821 int is_subset, ret = 0;
824 is_subset = cap_issubset(__task_cred(p)->cap_permitted,
825 current_cred()->cap_permitted);
826 if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
834 * cap_task_setscheduler - Detemine if scheduler policy change is permitted
835 * @p: The task to affect
837 * Detemine if the requested scheduler policy change is permitted for the
838 * specified task, returning 0 if permission is granted, -ve if denied.
840 int cap_task_setscheduler(struct task_struct *p)
842 return cap_safe_nice(p);
846 * cap_task_ioprio - Detemine if I/O priority change is permitted
847 * @p: The task to affect
848 * @ioprio: The I/O priority to set
850 * Detemine if the requested I/O priority change is permitted for the specified
851 * task, returning 0 if permission is granted, -ve if denied.
853 int cap_task_setioprio(struct task_struct *p, int ioprio)
855 return cap_safe_nice(p);
859 * cap_task_ioprio - Detemine if task priority change is permitted
860 * @p: The task to affect
861 * @nice: The nice value to set
863 * Detemine if the requested task priority change is permitted for the
864 * specified task, returning 0 if permission is granted, -ve if denied.
866 int cap_task_setnice(struct task_struct *p, int nice)
868 return cap_safe_nice(p);
872 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from
873 * the current task's bounding set. Returns 0 on success, -ve on error.
875 static int cap_prctl_drop(unsigned long cap)
879 if (!ns_capable(current_user_ns(), CAP_SETPCAP))
884 new = prepare_creds();
887 cap_lower(new->cap_bset, cap);
888 return commit_creds(new);
892 * cap_task_prctl - Implement process control functions for this security module
893 * @option: The process control function requested
894 * @arg2, @arg3, @arg4, @arg5: The argument data for this function
896 * Allow process control functions (sys_prctl()) to alter capabilities; may
897 * also deny access to other functions not otherwise implemented here.
899 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
900 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM
901 * modules will consider performing the function.
903 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
904 unsigned long arg4, unsigned long arg5)
906 const struct cred *old = current_cred();
910 case PR_CAPBSET_READ:
911 if (!cap_valid(arg2))
913 return !!cap_raised(old->cap_bset, arg2);
915 case PR_CAPBSET_DROP:
916 return cap_prctl_drop(arg2);
919 * The next four prctl's remain to assist with transitioning a
920 * system from legacy UID=0 based privilege (when filesystem
921 * capabilities are not in use) to a system using filesystem
922 * capabilities only - as the POSIX.1e draft intended.
926 * PR_SET_SECUREBITS =
927 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
928 * | issecure_mask(SECURE_NOROOT)
929 * | issecure_mask(SECURE_NOROOT_LOCKED)
930 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
931 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
933 * will ensure that the current process and all of its
934 * children will be locked into a pure
935 * capability-based-privilege environment.
937 case PR_SET_SECUREBITS:
938 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
939 & (old->securebits ^ arg2)) /*[1]*/
940 || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
941 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
942 || (cap_capable(current_cred(),
943 current_cred()->user_ns, CAP_SETPCAP,
944 SECURITY_CAP_AUDIT) != 0) /*[4]*/
946 * [1] no changing of bits that are locked
947 * [2] no unlocking of locks
948 * [3] no setting of unsupported bits
949 * [4] doing anything requires privilege (go read about
950 * the "sendmail capabilities bug")
953 /* cannot change a locked bit */
956 new = prepare_creds();
959 new->securebits = arg2;
960 return commit_creds(new);
962 case PR_GET_SECUREBITS:
963 return old->securebits;
965 case PR_GET_KEEPCAPS:
966 return !!issecure(SECURE_KEEP_CAPS);
968 case PR_SET_KEEPCAPS:
969 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
971 if (issecure(SECURE_KEEP_CAPS_LOCKED))
974 new = prepare_creds();
978 new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
980 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
981 return commit_creds(new);
984 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
985 if (arg3 | arg4 | arg5)
988 new = prepare_creds();
991 cap_clear(new->cap_ambient);
992 return commit_creds(new);
995 if (((!cap_valid(arg3)) | arg4 | arg5))
998 if (arg2 == PR_CAP_AMBIENT_IS_SET) {
999 return !!cap_raised(current_cred()->cap_ambient, arg3);
1000 } else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1001 arg2 != PR_CAP_AMBIENT_LOWER) {
1004 if (arg2 == PR_CAP_AMBIENT_RAISE &&
1005 (!cap_raised(current_cred()->cap_permitted, arg3) ||
1006 !cap_raised(current_cred()->cap_inheritable,
1008 issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
1011 new = prepare_creds();
1014 if (arg2 == PR_CAP_AMBIENT_RAISE)
1015 cap_raise(new->cap_ambient, arg3);
1017 cap_lower(new->cap_ambient, arg3);
1018 return commit_creds(new);
1022 /* No functionality available - continue with default */
1028 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1029 * @mm: The VM space in which the new mapping is to be made
1030 * @pages: The size of the mapping
1032 * Determine whether the allocation of a new virtual mapping by the current
1033 * task is permitted, returning 1 if permission is granted, 0 if not.
1035 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
1037 int cap_sys_admin = 0;
1039 if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
1040 SECURITY_CAP_NOAUDIT) == 0)
1042 return cap_sys_admin;
1046 * cap_mmap_addr - check if able to map given addr
1047 * @addr: address attempting to be mapped
1049 * If the process is attempting to map memory below dac_mmap_min_addr they need
1050 * CAP_SYS_RAWIO. The other parameters to this function are unused by the
1051 * capability security module. Returns 0 if this mapping should be allowed
1054 int cap_mmap_addr(unsigned long addr)
1058 if (addr < dac_mmap_min_addr) {
1059 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
1060 SECURITY_CAP_AUDIT);
1061 /* set PF_SUPERPRIV if it turns out we allow the low mmap */
1063 current->flags |= PF_SUPERPRIV;
1068 int cap_mmap_file(struct file *file, unsigned long reqprot,
1069 unsigned long prot, unsigned long flags)
1074 #ifdef CONFIG_SECURITY
1076 struct security_hook_list capability_hooks[] = {
1077 LSM_HOOK_INIT(capable, cap_capable),
1078 LSM_HOOK_INIT(settime, cap_settime),
1079 LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1080 LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1081 LSM_HOOK_INIT(capget, cap_capget),
1082 LSM_HOOK_INIT(capset, cap_capset),
1083 LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
1084 LSM_HOOK_INIT(bprm_secureexec, cap_bprm_secureexec),
1085 LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1086 LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
1087 LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1088 LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1089 LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1090 LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1091 LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1092 LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1093 LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1094 LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1097 void __init capability_add_hooks(void)
1099 security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks));
1102 #endif /* CONFIG_SECURITY */