[MTD] [NAND] atmel_nand speedup via {read,write}s{b,w}()
[linux-ginger.git] / security / commoncap.c
blob33d34330841344f7329e1b1f313cc531c65aa7a9
1 /* Common capabilities, needed by capability.o and root_plug.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/module.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/security.h>
15 #include <linux/file.h>
16 #include <linux/mm.h>
17 #include <linux/mman.h>
18 #include <linux/pagemap.h>
19 #include <linux/swap.h>
20 #include <linux/skbuff.h>
21 #include <linux/netlink.h>
22 #include <linux/ptrace.h>
23 #include <linux/xattr.h>
24 #include <linux/hugetlb.h>
25 #include <linux/mount.h>
26 #include <linux/sched.h>
27 #include <linux/prctl.h>
28 #include <linux/securebits.h>
30 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
32 NETLINK_CB(skb).eff_cap = current->cap_effective;
33 return 0;
36 int cap_netlink_recv(struct sk_buff *skb, int cap)
38 if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
39 return -EPERM;
40 return 0;
43 EXPORT_SYMBOL(cap_netlink_recv);
46 * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
47 * function. That is, it has the reverse semantics: cap_capable()
48 * returns 0 when a task has a capability, but the kernel's capable()
49 * returns 1 for this case.
51 int cap_capable (struct task_struct *tsk, int cap)
53 /* Derived from include/linux/sched.h:capable. */
54 if (cap_raised(tsk->cap_effective, cap))
55 return 0;
56 return -EPERM;
59 int cap_settime(struct timespec *ts, struct timezone *tz)
61 if (!capable(CAP_SYS_TIME))
62 return -EPERM;
63 return 0;
66 int cap_ptrace (struct task_struct *parent, struct task_struct *child)
68 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
69 if (!cap_issubset(child->cap_permitted, parent->cap_permitted) &&
70 !__capable(parent, CAP_SYS_PTRACE))
71 return -EPERM;
72 return 0;
75 int cap_capget (struct task_struct *target, kernel_cap_t *effective,
76 kernel_cap_t *inheritable, kernel_cap_t *permitted)
78 /* Derived from kernel/capability.c:sys_capget. */
79 *effective = target->cap_effective;
80 *inheritable = target->cap_inheritable;
81 *permitted = target->cap_permitted;
82 return 0;
85 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
87 static inline int cap_block_setpcap(struct task_struct *target)
90 * No support for remote process capability manipulation with
91 * filesystem capability support.
93 return (target != current);
96 static inline int cap_inh_is_capped(void)
99 * Return 1 if changes to the inheritable set are limited
100 * to the old permitted set. That is, if the current task
101 * does *not* possess the CAP_SETPCAP capability.
103 return (cap_capable(current, CAP_SETPCAP) != 0);
106 static inline int cap_limit_ptraced_target(void) { return 1; }
108 #else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
110 static inline int cap_block_setpcap(struct task_struct *t) { return 0; }
111 static inline int cap_inh_is_capped(void) { return 1; }
112 static inline int cap_limit_ptraced_target(void)
114 return !capable(CAP_SETPCAP);
117 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
119 int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
120 kernel_cap_t *inheritable, kernel_cap_t *permitted)
122 if (cap_block_setpcap(target)) {
123 return -EPERM;
125 if (cap_inh_is_capped()
126 && !cap_issubset(*inheritable,
127 cap_combine(target->cap_inheritable,
128 current->cap_permitted))) {
129 /* incapable of using this inheritable set */
130 return -EPERM;
132 if (!cap_issubset(*inheritable,
133 cap_combine(target->cap_inheritable,
134 current->cap_bset))) {
135 /* no new pI capabilities outside bounding set */
136 return -EPERM;
139 /* verify restrictions on target's new Permitted set */
140 if (!cap_issubset (*permitted,
141 cap_combine (target->cap_permitted,
142 current->cap_permitted))) {
143 return -EPERM;
146 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
147 if (!cap_issubset (*effective, *permitted)) {
148 return -EPERM;
151 return 0;
154 void cap_capset_set (struct task_struct *target, kernel_cap_t *effective,
155 kernel_cap_t *inheritable, kernel_cap_t *permitted)
157 target->cap_effective = *effective;
158 target->cap_inheritable = *inheritable;
159 target->cap_permitted = *permitted;
162 static inline void bprm_clear_caps(struct linux_binprm *bprm)
164 cap_clear(bprm->cap_inheritable);
165 cap_clear(bprm->cap_permitted);
166 bprm->cap_effective = false;
169 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
171 int cap_inode_need_killpriv(struct dentry *dentry)
173 struct inode *inode = dentry->d_inode;
174 int error;
176 if (!inode->i_op || !inode->i_op->getxattr)
177 return 0;
179 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
180 if (error <= 0)
181 return 0;
182 return 1;
185 int cap_inode_killpriv(struct dentry *dentry)
187 struct inode *inode = dentry->d_inode;
189 if (!inode->i_op || !inode->i_op->removexattr)
190 return 0;
192 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
195 static inline int cap_from_disk(struct vfs_cap_data *caps,
196 struct linux_binprm *bprm, unsigned size)
198 __u32 magic_etc;
199 unsigned tocopy, i;
201 if (size < sizeof(magic_etc))
202 return -EINVAL;
204 magic_etc = le32_to_cpu(caps->magic_etc);
206 switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
207 case VFS_CAP_REVISION_1:
208 if (size != XATTR_CAPS_SZ_1)
209 return -EINVAL;
210 tocopy = VFS_CAP_U32_1;
211 break;
212 case VFS_CAP_REVISION_2:
213 if (size != XATTR_CAPS_SZ_2)
214 return -EINVAL;
215 tocopy = VFS_CAP_U32_2;
216 break;
217 default:
218 return -EINVAL;
221 if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) {
222 bprm->cap_effective = true;
223 } else {
224 bprm->cap_effective = false;
227 for (i = 0; i < tocopy; ++i) {
228 bprm->cap_permitted.cap[i] =
229 le32_to_cpu(caps->data[i].permitted);
230 bprm->cap_inheritable.cap[i] =
231 le32_to_cpu(caps->data[i].inheritable);
233 while (i < VFS_CAP_U32) {
234 bprm->cap_permitted.cap[i] = 0;
235 bprm->cap_inheritable.cap[i] = 0;
236 i++;
239 return 0;
242 /* Locate any VFS capabilities: */
243 static int get_file_caps(struct linux_binprm *bprm)
245 struct dentry *dentry;
246 int rc = 0;
247 struct vfs_cap_data vcaps;
248 struct inode *inode;
250 if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) {
251 bprm_clear_caps(bprm);
252 return 0;
255 dentry = dget(bprm->file->f_dentry);
256 inode = dentry->d_inode;
257 if (!inode->i_op || !inode->i_op->getxattr)
258 goto out;
260 rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &vcaps,
261 XATTR_CAPS_SZ);
262 if (rc == -ENODATA || rc == -EOPNOTSUPP) {
263 /* no data, that's ok */
264 rc = 0;
265 goto out;
267 if (rc < 0)
268 goto out;
270 rc = cap_from_disk(&vcaps, bprm, rc);
271 if (rc)
272 printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
273 __func__, rc, bprm->filename);
275 out:
276 dput(dentry);
277 if (rc)
278 bprm_clear_caps(bprm);
280 return rc;
283 #else
284 int cap_inode_need_killpriv(struct dentry *dentry)
286 return 0;
289 int cap_inode_killpriv(struct dentry *dentry)
291 return 0;
294 static inline int get_file_caps(struct linux_binprm *bprm)
296 bprm_clear_caps(bprm);
297 return 0;
299 #endif
301 int cap_bprm_set_security (struct linux_binprm *bprm)
303 int ret;
305 ret = get_file_caps(bprm);
306 if (ret)
307 printk(KERN_NOTICE "%s: get_file_caps returned %d for %s\n",
308 __func__, ret, bprm->filename);
310 /* To support inheritance of root-permissions and suid-root
311 * executables under compatibility mode, we raise all three
312 * capability sets for the file.
314 * If only the real uid is 0, we only raise the inheritable
315 * and permitted sets of the executable file.
318 if (!issecure (SECURE_NOROOT)) {
319 if (bprm->e_uid == 0 || current->uid == 0) {
320 cap_set_full (bprm->cap_inheritable);
321 cap_set_full (bprm->cap_permitted);
323 if (bprm->e_uid == 0)
324 bprm->cap_effective = true;
327 return ret;
330 void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
332 /* Derived from fs/exec.c:compute_creds. */
333 kernel_cap_t new_permitted, working;
335 new_permitted = cap_intersect(bprm->cap_permitted,
336 current->cap_bset);
337 working = cap_intersect(bprm->cap_inheritable,
338 current->cap_inheritable);
339 new_permitted = cap_combine(new_permitted, working);
341 if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
342 !cap_issubset (new_permitted, current->cap_permitted)) {
343 set_dumpable(current->mm, suid_dumpable);
344 current->pdeath_signal = 0;
346 if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
347 if (!capable(CAP_SETUID)) {
348 bprm->e_uid = current->uid;
349 bprm->e_gid = current->gid;
351 if (cap_limit_ptraced_target()) {
352 new_permitted =
353 cap_intersect(new_permitted,
354 current->cap_permitted);
359 current->suid = current->euid = current->fsuid = bprm->e_uid;
360 current->sgid = current->egid = current->fsgid = bprm->e_gid;
362 /* For init, we want to retain the capabilities set
363 * in the init_task struct. Thus we skip the usual
364 * capability rules */
365 if (!is_global_init(current)) {
366 current->cap_permitted = new_permitted;
367 if (bprm->cap_effective)
368 current->cap_effective = new_permitted;
369 else
370 cap_clear(current->cap_effective);
373 /* AUD: Audit candidate if current->cap_effective is set */
375 current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
378 int cap_bprm_secureexec (struct linux_binprm *bprm)
380 if (current->uid != 0) {
381 if (bprm->cap_effective)
382 return 1;
383 if (!cap_isclear(bprm->cap_permitted))
384 return 1;
385 if (!cap_isclear(bprm->cap_inheritable))
386 return 1;
389 return (current->euid != current->uid ||
390 current->egid != current->gid);
393 int cap_inode_setxattr(struct dentry *dentry, const char *name,
394 const void *value, size_t size, int flags)
396 if (!strcmp(name, XATTR_NAME_CAPS)) {
397 if (!capable(CAP_SETFCAP))
398 return -EPERM;
399 return 0;
400 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
401 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
402 !capable(CAP_SYS_ADMIN))
403 return -EPERM;
404 return 0;
407 int cap_inode_removexattr(struct dentry *dentry, const char *name)
409 if (!strcmp(name, XATTR_NAME_CAPS)) {
410 if (!capable(CAP_SETFCAP))
411 return -EPERM;
412 return 0;
413 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
414 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
415 !capable(CAP_SYS_ADMIN))
416 return -EPERM;
417 return 0;
420 /* moved from kernel/sys.c. */
422 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
423 * a process after a call to setuid, setreuid, or setresuid.
425 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
426 * {r,e,s}uid != 0, the permitted and effective capabilities are
427 * cleared.
429 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
430 * capabilities of the process are cleared.
432 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
433 * capabilities are set to the permitted capabilities.
435 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
436 * never happen.
438 * -astor
440 * cevans - New behaviour, Oct '99
441 * A process may, via prctl(), elect to keep its capabilities when it
442 * calls setuid() and switches away from uid==0. Both permitted and
443 * effective sets will be retained.
444 * Without this change, it was impossible for a daemon to drop only some
445 * of its privilege. The call to setuid(!=0) would drop all privileges!
446 * Keeping uid 0 is not an option because uid 0 owns too many vital
447 * files..
448 * Thanks to Olaf Kirch and Peter Benie for spotting this.
450 static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
451 int old_suid)
453 if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
454 (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
455 !issecure(SECURE_KEEP_CAPS)) {
456 cap_clear (current->cap_permitted);
457 cap_clear (current->cap_effective);
459 if (old_euid == 0 && current->euid != 0) {
460 cap_clear (current->cap_effective);
462 if (old_euid != 0 && current->euid == 0) {
463 current->cap_effective = current->cap_permitted;
467 int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
468 int flags)
470 switch (flags) {
471 case LSM_SETID_RE:
472 case LSM_SETID_ID:
473 case LSM_SETID_RES:
474 /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
475 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
476 cap_emulate_setxuid (old_ruid, old_euid, old_suid);
478 break;
479 case LSM_SETID_FS:
481 uid_t old_fsuid = old_ruid;
483 /* Copied from kernel/sys.c:setfsuid. */
486 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
487 * if not, we might be a bit too harsh here.
490 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
491 if (old_fsuid == 0 && current->fsuid != 0) {
492 current->cap_effective =
493 cap_drop_fs_set(
494 current->cap_effective);
496 if (old_fsuid != 0 && current->fsuid == 0) {
497 current->cap_effective =
498 cap_raise_fs_set(
499 current->cap_effective,
500 current->cap_permitted);
503 break;
505 default:
506 return -EINVAL;
509 return 0;
512 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
514 * Rationale: code calling task_setscheduler, task_setioprio, and
515 * task_setnice, assumes that
516 * . if capable(cap_sys_nice), then those actions should be allowed
517 * . if not capable(cap_sys_nice), but acting on your own processes,
518 * then those actions should be allowed
519 * This is insufficient now since you can call code without suid, but
520 * yet with increased caps.
521 * So we check for increased caps on the target process.
523 static inline int cap_safe_nice(struct task_struct *p)
525 if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
526 !__capable(current, CAP_SYS_NICE))
527 return -EPERM;
528 return 0;
531 int cap_task_setscheduler (struct task_struct *p, int policy,
532 struct sched_param *lp)
534 return cap_safe_nice(p);
537 int cap_task_setioprio (struct task_struct *p, int ioprio)
539 return cap_safe_nice(p);
542 int cap_task_setnice (struct task_struct *p, int nice)
544 return cap_safe_nice(p);
548 * called from kernel/sys.c for prctl(PR_CABSET_DROP)
549 * done without task_capability_lock() because it introduces
550 * no new races - i.e. only another task doing capget() on
551 * this task could get inconsistent info. There can be no
552 * racing writer bc a task can only change its own caps.
554 static long cap_prctl_drop(unsigned long cap)
556 if (!capable(CAP_SETPCAP))
557 return -EPERM;
558 if (!cap_valid(cap))
559 return -EINVAL;
560 cap_lower(current->cap_bset, cap);
561 return 0;
564 #else
565 int cap_task_setscheduler (struct task_struct *p, int policy,
566 struct sched_param *lp)
568 return 0;
570 int cap_task_setioprio (struct task_struct *p, int ioprio)
572 return 0;
574 int cap_task_setnice (struct task_struct *p, int nice)
576 return 0;
578 #endif
580 int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
581 unsigned long arg4, unsigned long arg5, long *rc_p)
583 long error = 0;
585 switch (option) {
586 case PR_CAPBSET_READ:
587 if (!cap_valid(arg2))
588 error = -EINVAL;
589 else
590 error = !!cap_raised(current->cap_bset, arg2);
591 break;
592 #ifdef CONFIG_SECURITY_FILE_CAPABILITIES
593 case PR_CAPBSET_DROP:
594 error = cap_prctl_drop(arg2);
595 break;
598 * The next four prctl's remain to assist with transitioning a
599 * system from legacy UID=0 based privilege (when filesystem
600 * capabilities are not in use) to a system using filesystem
601 * capabilities only - as the POSIX.1e draft intended.
603 * Note:
605 * PR_SET_SECUREBITS =
606 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
607 * | issecure_mask(SECURE_NOROOT)
608 * | issecure_mask(SECURE_NOROOT_LOCKED)
609 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
610 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
612 * will ensure that the current process and all of its
613 * children will be locked into a pure
614 * capability-based-privilege environment.
616 case PR_SET_SECUREBITS:
617 if ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
618 & (current->securebits ^ arg2)) /*[1]*/
619 || ((current->securebits & SECURE_ALL_LOCKS
620 & ~arg2)) /*[2]*/
621 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
622 || (cap_capable(current, CAP_SETPCAP) != 0)) { /*[4]*/
624 * [1] no changing of bits that are locked
625 * [2] no unlocking of locks
626 * [3] no setting of unsupported bits
627 * [4] doing anything requires privilege (go read about
628 * the "sendmail capabilities bug")
630 error = -EPERM; /* cannot change a locked bit */
631 } else {
632 current->securebits = arg2;
634 break;
635 case PR_GET_SECUREBITS:
636 error = current->securebits;
637 break;
639 #endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
641 case PR_GET_KEEPCAPS:
642 if (issecure(SECURE_KEEP_CAPS))
643 error = 1;
644 break;
645 case PR_SET_KEEPCAPS:
646 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
647 error = -EINVAL;
648 else if (issecure(SECURE_KEEP_CAPS_LOCKED))
649 error = -EPERM;
650 else if (arg2)
651 current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
652 else
653 current->securebits &=
654 ~issecure_mask(SECURE_KEEP_CAPS);
655 break;
657 default:
658 /* No functionality available - continue with default */
659 return 0;
662 /* Functionality provided */
663 *rc_p = error;
664 return 1;
667 void cap_task_reparent_to_init (struct task_struct *p)
669 cap_set_init_eff(p->cap_effective);
670 cap_clear(p->cap_inheritable);
671 cap_set_full(p->cap_permitted);
672 p->securebits = SECUREBITS_DEFAULT;
673 return;
676 int cap_syslog (int type)
678 if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
679 return -EPERM;
680 return 0;
683 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
685 int cap_sys_admin = 0;
687 if (cap_capable(current, CAP_SYS_ADMIN) == 0)
688 cap_sys_admin = 1;
689 return __vm_enough_memory(mm, pages, cap_sys_admin);