regulator: Add WM8994 regulator support
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / security / commoncap.c
blobf800fdb3de94136a093f51b11d0ca5e9eaf686e8
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.
8 */
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/security.h>
16 #include <linux/file.h>
17 #include <linux/mm.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>
32 * If a non-root user executes a setuid-root binary in
33 * !secure(SECURE_NOROOT) mode, then we raise capabilities.
34 * However if fE is also set, then the intent is for only
35 * the file capabilities to be applied, and the setuid-root
36 * bit is left on either to change the uid (plausible) or
37 * to get full privilege on a kernel without file capabilities
38 * support. So in that case we do not raise capabilities.
40 * Warn if that happens, once per boot.
42 static void warn_setuid_and_fcaps_mixed(char *fname)
44 static int warned;
45 if (!warned) {
46 printk(KERN_INFO "warning: `%s' has both setuid-root and"
47 " effective capabilities. Therefore not raising all"
48 " capabilities.\n", fname);
49 warned = 1;
53 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
55 NETLINK_CB(skb).eff_cap = current_cap();
56 return 0;
59 int cap_netlink_recv(struct sk_buff *skb, int cap)
61 if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
62 return -EPERM;
63 return 0;
65 EXPORT_SYMBOL(cap_netlink_recv);
67 /**
68 * cap_capable - Determine whether a task has a particular effective capability
69 * @tsk: The task to query
70 * @cred: The credentials to use
71 * @cap: The capability to check for
72 * @audit: Whether to write an audit message or not
74 * Determine whether the nominated task has the specified capability amongst
75 * its effective set, returning 0 if it does, -ve if it does not.
77 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
78 * and has_capability() functions. That is, it has the reverse semantics:
79 * cap_has_capability() returns 0 when a task has a capability, but the
80 * kernel's capable() and has_capability() returns 1 for this case.
82 int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap,
83 int audit)
85 return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
88 /**
89 * cap_settime - Determine whether the current process may set the system clock
90 * @ts: The time to set
91 * @tz: The timezone to set
93 * Determine whether the current process may set the system clock and timezone
94 * information, returning 0 if permission granted, -ve if denied.
96 int cap_settime(struct timespec *ts, struct timezone *tz)
98 if (!capable(CAP_SYS_TIME))
99 return -EPERM;
100 return 0;
104 * cap_ptrace_access_check - Determine whether the current process may access
105 * another
106 * @child: The process to be accessed
107 * @mode: The mode of attachment.
109 * Determine whether a process may access another, returning 0 if permission
110 * granted, -ve if denied.
112 int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
114 int ret = 0;
116 rcu_read_lock();
117 if (!cap_issubset(__task_cred(child)->cap_permitted,
118 current_cred()->cap_permitted) &&
119 !capable(CAP_SYS_PTRACE))
120 ret = -EPERM;
121 rcu_read_unlock();
122 return ret;
126 * cap_ptrace_traceme - Determine whether another process may trace the current
127 * @parent: The task proposed to be the tracer
129 * Determine whether the nominated task is permitted to trace the current
130 * process, returning 0 if permission is granted, -ve if denied.
132 int cap_ptrace_traceme(struct task_struct *parent)
134 int ret = 0;
136 rcu_read_lock();
137 if (!cap_issubset(current_cred()->cap_permitted,
138 __task_cred(parent)->cap_permitted) &&
139 !has_capability(parent, CAP_SYS_PTRACE))
140 ret = -EPERM;
141 rcu_read_unlock();
142 return ret;
146 * cap_capget - Retrieve a task's capability sets
147 * @target: The task from which to retrieve the capability sets
148 * @effective: The place to record the effective set
149 * @inheritable: The place to record the inheritable set
150 * @permitted: The place to record the permitted set
152 * This function retrieves the capabilities of the nominated task and returns
153 * them to the caller.
155 int cap_capget(struct task_struct *target, kernel_cap_t *effective,
156 kernel_cap_t *inheritable, kernel_cap_t *permitted)
158 const struct cred *cred;
160 /* Derived from kernel/capability.c:sys_capget. */
161 rcu_read_lock();
162 cred = __task_cred(target);
163 *effective = cred->cap_effective;
164 *inheritable = cred->cap_inheritable;
165 *permitted = cred->cap_permitted;
166 rcu_read_unlock();
167 return 0;
171 * Determine whether the inheritable capabilities are limited to the old
172 * permitted set. Returns 1 if they are limited, 0 if they are not.
174 static inline int cap_inh_is_capped(void)
177 /* they are so limited unless the current task has the CAP_SETPCAP
178 * capability
180 if (cap_capable(current, current_cred(), CAP_SETPCAP,
181 SECURITY_CAP_AUDIT) == 0)
182 return 0;
183 return 1;
187 * cap_capset - Validate and apply proposed changes to current's capabilities
188 * @new: The proposed new credentials; alterations should be made here
189 * @old: The current task's current credentials
190 * @effective: A pointer to the proposed new effective capabilities set
191 * @inheritable: A pointer to the proposed new inheritable capabilities set
192 * @permitted: A pointer to the proposed new permitted capabilities set
194 * This function validates and applies a proposed mass change to the current
195 * process's capability sets. The changes are made to the proposed new
196 * credentials, and assuming no error, will be committed by the caller of LSM.
198 int cap_capset(struct cred *new,
199 const struct cred *old,
200 const kernel_cap_t *effective,
201 const kernel_cap_t *inheritable,
202 const kernel_cap_t *permitted)
204 if (cap_inh_is_capped() &&
205 !cap_issubset(*inheritable,
206 cap_combine(old->cap_inheritable,
207 old->cap_permitted)))
208 /* incapable of using this inheritable set */
209 return -EPERM;
211 if (!cap_issubset(*inheritable,
212 cap_combine(old->cap_inheritable,
213 old->cap_bset)))
214 /* no new pI capabilities outside bounding set */
215 return -EPERM;
217 /* verify restrictions on target's new Permitted set */
218 if (!cap_issubset(*permitted, old->cap_permitted))
219 return -EPERM;
221 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
222 if (!cap_issubset(*effective, *permitted))
223 return -EPERM;
225 new->cap_effective = *effective;
226 new->cap_inheritable = *inheritable;
227 new->cap_permitted = *permitted;
228 return 0;
232 * Clear proposed capability sets for execve().
234 static inline void bprm_clear_caps(struct linux_binprm *bprm)
236 cap_clear(bprm->cred->cap_permitted);
237 bprm->cap_effective = false;
241 * cap_inode_need_killpriv - Determine if inode change affects privileges
242 * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
244 * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
245 * affects the security markings on that inode, and if it is, should
246 * inode_killpriv() be invoked or the change rejected?
248 * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and
249 * -ve to deny the change.
251 int cap_inode_need_killpriv(struct dentry *dentry)
253 struct inode *inode = dentry->d_inode;
254 int error;
256 if (!inode->i_op->getxattr)
257 return 0;
259 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
260 if (error <= 0)
261 return 0;
262 return 1;
266 * cap_inode_killpriv - Erase the security markings on an inode
267 * @dentry: The inode/dentry to alter
269 * Erase the privilege-enhancing security markings on an inode.
271 * Returns 0 if successful, -ve on error.
273 int cap_inode_killpriv(struct dentry *dentry)
275 struct inode *inode = dentry->d_inode;
277 if (!inode->i_op->removexattr)
278 return 0;
280 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
284 * Calculate the new process capability sets from the capability sets attached
285 * to a file.
287 static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
288 struct linux_binprm *bprm,
289 bool *effective)
291 struct cred *new = bprm->cred;
292 unsigned i;
293 int ret = 0;
295 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
296 *effective = true;
298 CAP_FOR_EACH_U32(i) {
299 __u32 permitted = caps->permitted.cap[i];
300 __u32 inheritable = caps->inheritable.cap[i];
303 * pP' = (X & fP) | (pI & fI)
305 new->cap_permitted.cap[i] =
306 (new->cap_bset.cap[i] & permitted) |
307 (new->cap_inheritable.cap[i] & inheritable);
309 if (permitted & ~new->cap_permitted.cap[i])
310 /* insufficient to execute correctly */
311 ret = -EPERM;
315 * For legacy apps, with no internal support for recognizing they
316 * do not have enough capabilities, we return an error if they are
317 * missing some "forced" (aka file-permitted) capabilities.
319 return *effective ? ret : 0;
323 * Extract the on-exec-apply capability sets for an executable file.
325 int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
327 struct inode *inode = dentry->d_inode;
328 __u32 magic_etc;
329 unsigned tocopy, i;
330 int size;
331 struct vfs_cap_data caps;
333 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
335 if (!inode || !inode->i_op->getxattr)
336 return -ENODATA;
338 size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
339 XATTR_CAPS_SZ);
340 if (size == -ENODATA || size == -EOPNOTSUPP)
341 /* no data, that's ok */
342 return -ENODATA;
343 if (size < 0)
344 return size;
346 if (size < sizeof(magic_etc))
347 return -EINVAL;
349 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
351 switch (magic_etc & VFS_CAP_REVISION_MASK) {
352 case VFS_CAP_REVISION_1:
353 if (size != XATTR_CAPS_SZ_1)
354 return -EINVAL;
355 tocopy = VFS_CAP_U32_1;
356 break;
357 case VFS_CAP_REVISION_2:
358 if (size != XATTR_CAPS_SZ_2)
359 return -EINVAL;
360 tocopy = VFS_CAP_U32_2;
361 break;
362 default:
363 return -EINVAL;
366 CAP_FOR_EACH_U32(i) {
367 if (i >= tocopy)
368 break;
369 cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
370 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
373 return 0;
377 * Attempt to get the on-exec apply capability sets for an executable file from
378 * its xattrs and, if present, apply them to the proposed credentials being
379 * constructed by execve().
381 static int get_file_caps(struct linux_binprm *bprm, bool *effective)
383 struct dentry *dentry;
384 int rc = 0;
385 struct cpu_vfs_cap_data vcaps;
387 bprm_clear_caps(bprm);
389 if (!file_caps_enabled)
390 return 0;
392 if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
393 return 0;
395 dentry = dget(bprm->file->f_dentry);
397 rc = get_vfs_caps_from_disk(dentry, &vcaps);
398 if (rc < 0) {
399 if (rc == -EINVAL)
400 printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
401 __func__, rc, bprm->filename);
402 else if (rc == -ENODATA)
403 rc = 0;
404 goto out;
407 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective);
408 if (rc == -EINVAL)
409 printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
410 __func__, rc, bprm->filename);
412 out:
413 dput(dentry);
414 if (rc)
415 bprm_clear_caps(bprm);
417 return rc;
421 * cap_bprm_set_creds - Set up the proposed credentials for execve().
422 * @bprm: The execution parameters, including the proposed creds
424 * Set up the proposed credentials for a new execution context being
425 * constructed by execve(). The proposed creds in @bprm->cred is altered,
426 * which won't take effect immediately. Returns 0 if successful, -ve on error.
428 int cap_bprm_set_creds(struct linux_binprm *bprm)
430 const struct cred *old = current_cred();
431 struct cred *new = bprm->cred;
432 bool effective;
433 int ret;
435 effective = false;
436 ret = get_file_caps(bprm, &effective);
437 if (ret < 0)
438 return ret;
440 if (!issecure(SECURE_NOROOT)) {
442 * If the legacy file capability is set, then don't set privs
443 * for a setuid root binary run by a non-root user. Do set it
444 * for a root user just to cause least surprise to an admin.
446 if (effective && new->uid != 0 && new->euid == 0) {
447 warn_setuid_and_fcaps_mixed(bprm->filename);
448 goto skip;
451 * To support inheritance of root-permissions and suid-root
452 * executables under compatibility mode, we override the
453 * capability sets for the file.
455 * If only the real uid is 0, we do not set the effective bit.
457 if (new->euid == 0 || new->uid == 0) {
458 /* pP' = (cap_bset & ~0) | (pI & ~0) */
459 new->cap_permitted = cap_combine(old->cap_bset,
460 old->cap_inheritable);
462 if (new->euid == 0)
463 effective = true;
465 skip:
467 /* Don't let someone trace a set[ug]id/setpcap binary with the revised
468 * credentials unless they have the appropriate permit
470 if ((new->euid != old->uid ||
471 new->egid != old->gid ||
472 !cap_issubset(new->cap_permitted, old->cap_permitted)) &&
473 bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
474 /* downgrade; they get no more than they had, and maybe less */
475 if (!capable(CAP_SETUID)) {
476 new->euid = new->uid;
477 new->egid = new->gid;
479 new->cap_permitted = cap_intersect(new->cap_permitted,
480 old->cap_permitted);
483 new->suid = new->fsuid = new->euid;
484 new->sgid = new->fsgid = new->egid;
486 /* For init, we want to retain the capabilities set in the initial
487 * task. Thus we skip the usual capability rules
489 if (!is_global_init(current)) {
490 if (effective)
491 new->cap_effective = new->cap_permitted;
492 else
493 cap_clear(new->cap_effective);
495 bprm->cap_effective = effective;
498 * Audit candidate if current->cap_effective is set
500 * We do not bother to audit if 3 things are true:
501 * 1) cap_effective has all caps
502 * 2) we are root
503 * 3) root is supposed to have all caps (SECURE_NOROOT)
504 * Since this is just a normal root execing a process.
506 * Number 1 above might fail if you don't have a full bset, but I think
507 * that is interesting information to audit.
509 if (!cap_isclear(new->cap_effective)) {
510 if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
511 new->euid != 0 || new->uid != 0 ||
512 issecure(SECURE_NOROOT)) {
513 ret = audit_log_bprm_fcaps(bprm, new, old);
514 if (ret < 0)
515 return ret;
519 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
520 return 0;
524 * cap_bprm_secureexec - Determine whether a secure execution is required
525 * @bprm: The execution parameters
527 * Determine whether a secure execution is required, return 1 if it is, and 0
528 * if it is not.
530 * The credentials have been committed by this point, and so are no longer
531 * available through @bprm->cred.
533 int cap_bprm_secureexec(struct linux_binprm *bprm)
535 const struct cred *cred = current_cred();
537 if (cred->uid != 0) {
538 if (bprm->cap_effective)
539 return 1;
540 if (!cap_isclear(cred->cap_permitted))
541 return 1;
544 return (cred->euid != cred->uid ||
545 cred->egid != cred->gid);
549 * cap_inode_setxattr - Determine whether an xattr may be altered
550 * @dentry: The inode/dentry being altered
551 * @name: The name of the xattr to be changed
552 * @value: The value that the xattr will be changed to
553 * @size: The size of value
554 * @flags: The replacement flag
556 * Determine whether an xattr may be altered or set on an inode, returning 0 if
557 * permission is granted, -ve if denied.
559 * This is used to make sure security xattrs don't get updated or set by those
560 * who aren't privileged to do so.
562 int cap_inode_setxattr(struct dentry *dentry, const char *name,
563 const void *value, size_t size, int flags)
565 if (!strcmp(name, XATTR_NAME_CAPS)) {
566 if (!capable(CAP_SETFCAP))
567 return -EPERM;
568 return 0;
571 if (!strncmp(name, XATTR_SECURITY_PREFIX,
572 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
573 !capable(CAP_SYS_ADMIN))
574 return -EPERM;
575 return 0;
579 * cap_inode_removexattr - Determine whether an xattr may be removed
580 * @dentry: The inode/dentry being altered
581 * @name: The name of the xattr to be changed
583 * Determine whether an xattr may be removed from an inode, returning 0 if
584 * permission is granted, -ve if denied.
586 * This is used to make sure security xattrs don't get removed by those who
587 * aren't privileged to remove them.
589 int cap_inode_removexattr(struct dentry *dentry, const char *name)
591 if (!strcmp(name, XATTR_NAME_CAPS)) {
592 if (!capable(CAP_SETFCAP))
593 return -EPERM;
594 return 0;
597 if (!strncmp(name, XATTR_SECURITY_PREFIX,
598 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
599 !capable(CAP_SYS_ADMIN))
600 return -EPERM;
601 return 0;
605 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
606 * a process after a call to setuid, setreuid, or setresuid.
608 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
609 * {r,e,s}uid != 0, the permitted and effective capabilities are
610 * cleared.
612 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
613 * capabilities of the process are cleared.
615 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
616 * capabilities are set to the permitted capabilities.
618 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
619 * never happen.
621 * -astor
623 * cevans - New behaviour, Oct '99
624 * A process may, via prctl(), elect to keep its capabilities when it
625 * calls setuid() and switches away from uid==0. Both permitted and
626 * effective sets will be retained.
627 * Without this change, it was impossible for a daemon to drop only some
628 * of its privilege. The call to setuid(!=0) would drop all privileges!
629 * Keeping uid 0 is not an option because uid 0 owns too many vital
630 * files..
631 * Thanks to Olaf Kirch and Peter Benie for spotting this.
633 static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
635 if ((old->uid == 0 || old->euid == 0 || old->suid == 0) &&
636 (new->uid != 0 && new->euid != 0 && new->suid != 0) &&
637 !issecure(SECURE_KEEP_CAPS)) {
638 cap_clear(new->cap_permitted);
639 cap_clear(new->cap_effective);
641 if (old->euid == 0 && new->euid != 0)
642 cap_clear(new->cap_effective);
643 if (old->euid != 0 && new->euid == 0)
644 new->cap_effective = new->cap_permitted;
648 * cap_task_fix_setuid - Fix up the results of setuid() call
649 * @new: The proposed credentials
650 * @old: The current task's current credentials
651 * @flags: Indications of what has changed
653 * Fix up the results of setuid() call before the credential changes are
654 * actually applied, returning 0 to grant the changes, -ve to deny them.
656 int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
658 switch (flags) {
659 case LSM_SETID_RE:
660 case LSM_SETID_ID:
661 case LSM_SETID_RES:
662 /* juggle the capabilities to follow [RES]UID changes unless
663 * otherwise suppressed */
664 if (!issecure(SECURE_NO_SETUID_FIXUP))
665 cap_emulate_setxuid(new, old);
666 break;
668 case LSM_SETID_FS:
669 /* juggle the capabilties to follow FSUID changes, unless
670 * otherwise suppressed
672 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
673 * if not, we might be a bit too harsh here.
675 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
676 if (old->fsuid == 0 && new->fsuid != 0)
677 new->cap_effective =
678 cap_drop_fs_set(new->cap_effective);
680 if (old->fsuid != 0 && new->fsuid == 0)
681 new->cap_effective =
682 cap_raise_fs_set(new->cap_effective,
683 new->cap_permitted);
685 break;
687 default:
688 return -EINVAL;
691 return 0;
695 * Rationale: code calling task_setscheduler, task_setioprio, and
696 * task_setnice, assumes that
697 * . if capable(cap_sys_nice), then those actions should be allowed
698 * . if not capable(cap_sys_nice), but acting on your own processes,
699 * then those actions should be allowed
700 * This is insufficient now since you can call code without suid, but
701 * yet with increased caps.
702 * So we check for increased caps on the target process.
704 static int cap_safe_nice(struct task_struct *p)
706 int is_subset;
708 rcu_read_lock();
709 is_subset = cap_issubset(__task_cred(p)->cap_permitted,
710 current_cred()->cap_permitted);
711 rcu_read_unlock();
713 if (!is_subset && !capable(CAP_SYS_NICE))
714 return -EPERM;
715 return 0;
719 * cap_task_setscheduler - Detemine if scheduler policy change is permitted
720 * @p: The task to affect
721 * @policy: The policy to effect
722 * @lp: The parameters to the scheduling policy
724 * Detemine if the requested scheduler policy change is permitted for the
725 * specified task, returning 0 if permission is granted, -ve if denied.
727 int cap_task_setscheduler(struct task_struct *p, int policy,
728 struct sched_param *lp)
730 return cap_safe_nice(p);
734 * cap_task_ioprio - Detemine if I/O priority change is permitted
735 * @p: The task to affect
736 * @ioprio: The I/O priority to set
738 * Detemine if the requested I/O priority change is permitted for the specified
739 * task, returning 0 if permission is granted, -ve if denied.
741 int cap_task_setioprio(struct task_struct *p, int ioprio)
743 return cap_safe_nice(p);
747 * cap_task_ioprio - Detemine if task priority change is permitted
748 * @p: The task to affect
749 * @nice: The nice value to set
751 * Detemine if the requested task priority change is permitted for the
752 * specified task, returning 0 if permission is granted, -ve if denied.
754 int cap_task_setnice(struct task_struct *p, int nice)
756 return cap_safe_nice(p);
760 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from
761 * the current task's bounding set. Returns 0 on success, -ve on error.
763 static long cap_prctl_drop(struct cred *new, unsigned long cap)
765 if (!capable(CAP_SETPCAP))
766 return -EPERM;
767 if (!cap_valid(cap))
768 return -EINVAL;
770 cap_lower(new->cap_bset, cap);
771 return 0;
775 * cap_task_prctl - Implement process control functions for this security module
776 * @option: The process control function requested
777 * @arg2, @arg3, @arg4, @arg5: The argument data for this function
779 * Allow process control functions (sys_prctl()) to alter capabilities; may
780 * also deny access to other functions not otherwise implemented here.
782 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
783 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM
784 * modules will consider performing the function.
786 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
787 unsigned long arg4, unsigned long arg5)
789 struct cred *new;
790 long error = 0;
792 new = prepare_creds();
793 if (!new)
794 return -ENOMEM;
796 switch (option) {
797 case PR_CAPBSET_READ:
798 error = -EINVAL;
799 if (!cap_valid(arg2))
800 goto error;
801 error = !!cap_raised(new->cap_bset, arg2);
802 goto no_change;
804 case PR_CAPBSET_DROP:
805 error = cap_prctl_drop(new, arg2);
806 if (error < 0)
807 goto error;
808 goto changed;
811 * The next four prctl's remain to assist with transitioning a
812 * system from legacy UID=0 based privilege (when filesystem
813 * capabilities are not in use) to a system using filesystem
814 * capabilities only - as the POSIX.1e draft intended.
816 * Note:
818 * PR_SET_SECUREBITS =
819 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
820 * | issecure_mask(SECURE_NOROOT)
821 * | issecure_mask(SECURE_NOROOT_LOCKED)
822 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
823 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
825 * will ensure that the current process and all of its
826 * children will be locked into a pure
827 * capability-based-privilege environment.
829 case PR_SET_SECUREBITS:
830 error = -EPERM;
831 if ((((new->securebits & SECURE_ALL_LOCKS) >> 1)
832 & (new->securebits ^ arg2)) /*[1]*/
833 || ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
834 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
835 || (cap_capable(current, current_cred(), CAP_SETPCAP,
836 SECURITY_CAP_AUDIT) != 0) /*[4]*/
838 * [1] no changing of bits that are locked
839 * [2] no unlocking of locks
840 * [3] no setting of unsupported bits
841 * [4] doing anything requires privilege (go read about
842 * the "sendmail capabilities bug")
845 /* cannot change a locked bit */
846 goto error;
847 new->securebits = arg2;
848 goto changed;
850 case PR_GET_SECUREBITS:
851 error = new->securebits;
852 goto no_change;
854 case PR_GET_KEEPCAPS:
855 if (issecure(SECURE_KEEP_CAPS))
856 error = 1;
857 goto no_change;
859 case PR_SET_KEEPCAPS:
860 error = -EINVAL;
861 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
862 goto error;
863 error = -EPERM;
864 if (issecure(SECURE_KEEP_CAPS_LOCKED))
865 goto error;
866 if (arg2)
867 new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
868 else
869 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
870 goto changed;
872 default:
873 /* No functionality available - continue with default */
874 error = -ENOSYS;
875 goto error;
878 /* Functionality provided */
879 changed:
880 return commit_creds(new);
882 no_change:
883 error:
884 abort_creds(new);
885 return error;
889 * cap_syslog - Determine whether syslog function is permitted
890 * @type: Function requested
892 * Determine whether the current process is permitted to use a particular
893 * syslog function, returning 0 if permission is granted, -ve if not.
895 int cap_syslog(int type)
897 if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
898 return -EPERM;
899 return 0;
903 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
904 * @mm: The VM space in which the new mapping is to be made
905 * @pages: The size of the mapping
907 * Determine whether the allocation of a new virtual mapping by the current
908 * task is permitted, returning 0 if permission is granted, -ve if not.
910 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
912 int cap_sys_admin = 0;
914 if (cap_capable(current, current_cred(), CAP_SYS_ADMIN,
915 SECURITY_CAP_NOAUDIT) == 0)
916 cap_sys_admin = 1;
917 return __vm_enough_memory(mm, pages, cap_sys_admin);
921 * cap_file_mmap - check if able to map given addr
922 * @file: unused
923 * @reqprot: unused
924 * @prot: unused
925 * @flags: unused
926 * @addr: address attempting to be mapped
927 * @addr_only: unused
929 * If the process is attempting to map memory below mmap_min_addr they need
930 * CAP_SYS_RAWIO. The other parameters to this function are unused by the
931 * capability security module. Returns 0 if this mapping should be allowed
932 * -EPERM if not.
934 int cap_file_mmap(struct file *file, unsigned long reqprot,
935 unsigned long prot, unsigned long flags,
936 unsigned long addr, unsigned long addr_only)
938 int ret = 0;
940 if (addr < dac_mmap_min_addr) {
941 ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO,
942 SECURITY_CAP_AUDIT);
943 /* set PF_SUPERPRIV if it turns out we allow the low mmap */
944 if (ret == 0)
945 current->flags |= PF_SUPERPRIV;
947 return ret;