blob: bf67871173efbabbe2ad47a04ba1f24cbc6d3eeb [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* Common capabilities, needed by capability.o and root_plug.o
2 *
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.
7 *
8 */
9
Randy.Dunlapc59ede72006-01-11 12:17:46 -080010#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/skbuff.h>
21#include <linux/netlink.h>
22#include <linux/ptrace.h>
23#include <linux/xattr.h>
24#include <linux/hugetlb.h>
Serge E. Hallynb5376772007-10-16 23:31:36 -070025#include <linux/mount.h>
Serge E. Hallynb460cbc2007-10-18 23:39:52 -070026#include <linux/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
Andrew Morgan72c2d582007-10-18 03:05:59 -070028#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
29/*
30 * Because of the reduced scope of CAP_SETPCAP when filesystem
31 * capabilities are in effect, it is safe to allow this capability to
32 * be available in the default configuration.
33 */
34# define CAP_INIT_BSET CAP_FULL_SET
35#else /* ie. ndef CONFIG_SECURITY_FILE_CAPABILITIES */
36# define CAP_INIT_BSET CAP_INIT_EFF_SET
37#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
38
39kernel_cap_t cap_bset = CAP_INIT_BSET; /* systemwide capability bound */
40EXPORT_SYMBOL(cap_bset);
41
42/* Global security state */
43
44unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
45EXPORT_SYMBOL(securebits);
46
Linus Torvalds1da177e2005-04-16 15:20:36 -070047int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
48{
49 NETLINK_CB(skb).eff_cap = current->cap_effective;
50 return 0;
51}
52
Darrel Goeddelc7bdb542006-06-27 13:26:11 -070053int cap_netlink_recv(struct sk_buff *skb, int cap)
Linus Torvalds1da177e2005-04-16 15:20:36 -070054{
Darrel Goeddelc7bdb542006-06-27 13:26:11 -070055 if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 return -EPERM;
57 return 0;
58}
59
60EXPORT_SYMBOL(cap_netlink_recv);
61
62int cap_capable (struct task_struct *tsk, int cap)
63{
64 /* Derived from include/linux/sched.h:capable. */
65 if (cap_raised(tsk->cap_effective, cap))
66 return 0;
67 return -EPERM;
68}
69
70int cap_settime(struct timespec *ts, struct timezone *tz)
71{
72 if (!capable(CAP_SYS_TIME))
73 return -EPERM;
74 return 0;
75}
76
77int cap_ptrace (struct task_struct *parent, struct task_struct *child)
78{
79 /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
Chris Wrightd4eb82c2006-03-25 03:07:41 -080080 if (!cap_issubset(child->cap_permitted, parent->cap_permitted) &&
81 !__capable(parent, CAP_SYS_PTRACE))
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 return -EPERM;
83 return 0;
84}
85
86int cap_capget (struct task_struct *target, kernel_cap_t *effective,
87 kernel_cap_t *inheritable, kernel_cap_t *permitted)
88{
89 /* Derived from kernel/capability.c:sys_capget. */
90 *effective = cap_t (target->cap_effective);
91 *inheritable = cap_t (target->cap_inheritable);
92 *permitted = cap_t (target->cap_permitted);
93 return 0;
94}
95
Andrew Morgan72c2d582007-10-18 03:05:59 -070096#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
97
98static inline int cap_block_setpcap(struct task_struct *target)
99{
100 /*
101 * No support for remote process capability manipulation with
102 * filesystem capability support.
103 */
104 return (target != current);
105}
106
107static inline int cap_inh_is_capped(void)
108{
109 /*
110 * return 1 if changes to the inheritable set are limited
111 * to the old permitted set.
112 */
113 return !cap_capable(current, CAP_SETPCAP);
114}
115
116#else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
117
118static inline int cap_block_setpcap(struct task_struct *t) { return 0; }
119static inline int cap_inh_is_capped(void) { return 1; }
120
121#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
122
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
124 kernel_cap_t *inheritable, kernel_cap_t *permitted)
125{
Andrew Morgan72c2d582007-10-18 03:05:59 -0700126 if (cap_block_setpcap(target)) {
127 return -EPERM;
128 }
129 if (cap_inh_is_capped()
130 && !cap_issubset(*inheritable,
131 cap_combine(target->cap_inheritable,
132 current->cap_permitted))) {
133 /* incapable of using this inheritable set */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 return -EPERM;
135 }
136
137 /* verify restrictions on target's new Permitted set */
138 if (!cap_issubset (*permitted,
139 cap_combine (target->cap_permitted,
140 current->cap_permitted))) {
141 return -EPERM;
142 }
143
144 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
145 if (!cap_issubset (*effective, *permitted)) {
146 return -EPERM;
147 }
148
149 return 0;
150}
151
152void cap_capset_set (struct task_struct *target, kernel_cap_t *effective,
153 kernel_cap_t *inheritable, kernel_cap_t *permitted)
154{
155 target->cap_effective = *effective;
156 target->cap_inheritable = *inheritable;
157 target->cap_permitted = *permitted;
158}
159
Serge E. Hallynb5376772007-10-16 23:31:36 -0700160static inline void bprm_clear_caps(struct linux_binprm *bprm)
161{
162 cap_clear(bprm->cap_inheritable);
163 cap_clear(bprm->cap_permitted);
164 bprm->cap_effective = false;
165}
166
167#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
168
169int cap_inode_need_killpriv(struct dentry *dentry)
170{
171 struct inode *inode = dentry->d_inode;
172 int error;
173
174 if (!inode->i_op || !inode->i_op->getxattr)
175 return 0;
176
177 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
178 if (error <= 0)
179 return 0;
180 return 1;
181}
182
183int cap_inode_killpriv(struct dentry *dentry)
184{
185 struct inode *inode = dentry->d_inode;
186
187 if (!inode->i_op || !inode->i_op->removexattr)
188 return 0;
189
190 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
191}
192
Serge E. Hallynb68680e2007-10-21 16:41:38 -0700193static inline int cap_from_disk(struct vfs_cap_data *caps,
194 struct linux_binprm *bprm,
Serge E. Hallynb5376772007-10-16 23:31:36 -0700195 int size)
196{
197 __u32 magic_etc;
198
199 if (size != XATTR_CAPS_SZ)
200 return -EINVAL;
201
Serge E. Hallynb68680e2007-10-21 16:41:38 -0700202 magic_etc = le32_to_cpu(caps->magic_etc);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700203
204 switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
205 case VFS_CAP_REVISION:
206 if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
207 bprm->cap_effective = true;
208 else
209 bprm->cap_effective = false;
Serge E. Hallynb68680e2007-10-21 16:41:38 -0700210 bprm->cap_permitted = to_cap_t(le32_to_cpu(caps->permitted));
211 bprm->cap_inheritable = to_cap_t(le32_to_cpu(caps->inheritable));
Serge E. Hallynb5376772007-10-16 23:31:36 -0700212 return 0;
213 default:
214 return -EINVAL;
215 }
216}
217
218/* Locate any VFS capabilities: */
219static int get_file_caps(struct linux_binprm *bprm)
220{
221 struct dentry *dentry;
222 int rc = 0;
Serge E. Hallynb68680e2007-10-21 16:41:38 -0700223 struct vfs_cap_data incaps;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700224 struct inode *inode;
225
226 if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) {
227 bprm_clear_caps(bprm);
228 return 0;
229 }
230
231 dentry = dget(bprm->file->f_dentry);
232 inode = dentry->d_inode;
233 if (!inode->i_op || !inode->i_op->getxattr)
234 goto out;
235
Serge E. Hallynb68680e2007-10-21 16:41:38 -0700236 rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
237 if (rc > 0) {
238 if (rc == XATTR_CAPS_SZ)
239 rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS,
240 &incaps, XATTR_CAPS_SZ);
241 else
242 rc = -EINVAL;
243 }
Serge E. Hallynb5376772007-10-16 23:31:36 -0700244 if (rc == -ENODATA || rc == -EOPNOTSUPP) {
245 /* no data, that's ok */
246 rc = 0;
247 goto out;
248 }
249 if (rc < 0)
250 goto out;
251
Serge E. Hallynb68680e2007-10-21 16:41:38 -0700252 rc = cap_from_disk(&incaps, bprm, rc);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700253 if (rc)
254 printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
255 __FUNCTION__, rc, bprm->filename);
256
257out:
258 dput(dentry);
259 if (rc)
260 bprm_clear_caps(bprm);
261
262 return rc;
263}
264
265#else
266int cap_inode_need_killpriv(struct dentry *dentry)
267{
268 return 0;
269}
270
271int cap_inode_killpriv(struct dentry *dentry)
272{
273 return 0;
274}
275
276static inline int get_file_caps(struct linux_binprm *bprm)
277{
278 bprm_clear_caps(bprm);
279 return 0;
280}
281#endif
282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283int cap_bprm_set_security (struct linux_binprm *bprm)
284{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700285 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286
Serge E. Hallynb5376772007-10-16 23:31:36 -0700287 ret = get_file_caps(bprm);
288 if (ret)
289 printk(KERN_NOTICE "%s: get_file_caps returned %d for %s\n",
290 __FUNCTION__, ret, bprm->filename);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
292 /* To support inheritance of root-permissions and suid-root
293 * executables under compatibility mode, we raise all three
294 * capability sets for the file.
295 *
296 * If only the real uid is 0, we only raise the inheritable
297 * and permitted sets of the executable file.
298 */
299
300 if (!issecure (SECURE_NOROOT)) {
301 if (bprm->e_uid == 0 || current->uid == 0) {
302 cap_set_full (bprm->cap_inheritable);
303 cap_set_full (bprm->cap_permitted);
304 }
305 if (bprm->e_uid == 0)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700306 bprm->cap_effective = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 }
Serge E. Hallynb5376772007-10-16 23:31:36 -0700308
309 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310}
311
312void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
313{
314 /* Derived from fs/exec.c:compute_creds. */
315 kernel_cap_t new_permitted, working;
316
317 new_permitted = cap_intersect (bprm->cap_permitted, cap_bset);
318 working = cap_intersect (bprm->cap_inheritable,
319 current->cap_inheritable);
320 new_permitted = cap_combine (new_permitted, working);
321
322 if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
323 !cap_issubset (new_permitted, current->cap_permitted)) {
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -0700324 set_dumpable(current->mm, suid_dumpable);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700325 current->pdeath_signal = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326
327 if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
328 if (!capable(CAP_SETUID)) {
329 bprm->e_uid = current->uid;
330 bprm->e_gid = current->gid;
331 }
332 if (!capable (CAP_SETPCAP)) {
333 new_permitted = cap_intersect (new_permitted,
334 current->cap_permitted);
335 }
336 }
337 }
338
339 current->suid = current->euid = current->fsuid = bprm->e_uid;
340 current->sgid = current->egid = current->fsgid = bprm->e_gid;
341
342 /* For init, we want to retain the capabilities set
343 * in the init_task struct. Thus we skip the usual
344 * capability rules */
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700345 if (!is_global_init(current)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 current->cap_permitted = new_permitted;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700347 current->cap_effective = bprm->cap_effective ?
348 new_permitted : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 }
350
351 /* AUD: Audit candidate if current->cap_effective is set */
352
353 current->keep_capabilities = 0;
354}
355
356int cap_bprm_secureexec (struct linux_binprm *bprm)
357{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700358 if (current->uid != 0) {
359 if (bprm->cap_effective)
360 return 1;
361 if (!cap_isclear(bprm->cap_permitted))
362 return 1;
363 if (!cap_isclear(bprm->cap_inheritable))
364 return 1;
365 }
366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 return (current->euid != current->uid ||
368 current->egid != current->gid);
369}
370
371int cap_inode_setxattr(struct dentry *dentry, char *name, void *value,
372 size_t size, int flags)
373{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700374 if (!strcmp(name, XATTR_NAME_CAPS)) {
375 if (!capable(CAP_SETFCAP))
376 return -EPERM;
377 return 0;
378 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
380 !capable(CAP_SYS_ADMIN))
381 return -EPERM;
382 return 0;
383}
384
385int cap_inode_removexattr(struct dentry *dentry, char *name)
386{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700387 if (!strcmp(name, XATTR_NAME_CAPS)) {
388 if (!capable(CAP_SETFCAP))
389 return -EPERM;
390 return 0;
391 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
393 !capable(CAP_SYS_ADMIN))
394 return -EPERM;
395 return 0;
396}
397
398/* moved from kernel/sys.c. */
399/*
400 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
401 * a process after a call to setuid, setreuid, or setresuid.
402 *
403 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
404 * {r,e,s}uid != 0, the permitted and effective capabilities are
405 * cleared.
406 *
407 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
408 * capabilities of the process are cleared.
409 *
410 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
411 * capabilities are set to the permitted capabilities.
412 *
413 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
414 * never happen.
415 *
416 * -astor
417 *
418 * cevans - New behaviour, Oct '99
419 * A process may, via prctl(), elect to keep its capabilities when it
420 * calls setuid() and switches away from uid==0. Both permitted and
421 * effective sets will be retained.
422 * Without this change, it was impossible for a daemon to drop only some
423 * of its privilege. The call to setuid(!=0) would drop all privileges!
424 * Keeping uid 0 is not an option because uid 0 owns too many vital
425 * files..
426 * Thanks to Olaf Kirch and Peter Benie for spotting this.
427 */
428static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
429 int old_suid)
430{
431 if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
432 (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
433 !current->keep_capabilities) {
434 cap_clear (current->cap_permitted);
435 cap_clear (current->cap_effective);
436 }
437 if (old_euid == 0 && current->euid != 0) {
438 cap_clear (current->cap_effective);
439 }
440 if (old_euid != 0 && current->euid == 0) {
441 current->cap_effective = current->cap_permitted;
442 }
443}
444
445int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
446 int flags)
447{
448 switch (flags) {
449 case LSM_SETID_RE:
450 case LSM_SETID_ID:
451 case LSM_SETID_RES:
452 /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
453 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
454 cap_emulate_setxuid (old_ruid, old_euid, old_suid);
455 }
456 break;
457 case LSM_SETID_FS:
458 {
459 uid_t old_fsuid = old_ruid;
460
461 /* Copied from kernel/sys.c:setfsuid. */
462
463 /*
464 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
465 * if not, we might be a bit too harsh here.
466 */
467
468 if (!issecure (SECURE_NO_SETUID_FIXUP)) {
469 if (old_fsuid == 0 && current->fsuid != 0) {
470 cap_t (current->cap_effective) &=
471 ~CAP_FS_MASK;
472 }
473 if (old_fsuid != 0 && current->fsuid == 0) {
474 cap_t (current->cap_effective) |=
475 (cap_t (current->cap_permitted) &
476 CAP_FS_MASK);
477 }
478 }
479 break;
480 }
481 default:
482 return -EINVAL;
483 }
484
485 return 0;
486}
487
Serge E. Hallynb5376772007-10-16 23:31:36 -0700488#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
489/*
490 * Rationale: code calling task_setscheduler, task_setioprio, and
491 * task_setnice, assumes that
492 * . if capable(cap_sys_nice), then those actions should be allowed
493 * . if not capable(cap_sys_nice), but acting on your own processes,
494 * then those actions should be allowed
495 * This is insufficient now since you can call code without suid, but
496 * yet with increased caps.
497 * So we check for increased caps on the target process.
498 */
499static inline int cap_safe_nice(struct task_struct *p)
500{
501 if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
502 !__capable(current, CAP_SYS_NICE))
503 return -EPERM;
504 return 0;
505}
506
507int cap_task_setscheduler (struct task_struct *p, int policy,
508 struct sched_param *lp)
509{
510 return cap_safe_nice(p);
511}
512
513int cap_task_setioprio (struct task_struct *p, int ioprio)
514{
515 return cap_safe_nice(p);
516}
517
518int cap_task_setnice (struct task_struct *p, int nice)
519{
520 return cap_safe_nice(p);
521}
522
523int cap_task_kill(struct task_struct *p, struct siginfo *info,
524 int sig, u32 secid)
525{
526 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
527 return 0;
528
529 if (secid)
530 /*
531 * Signal sent as a particular user.
532 * Capabilities are ignored. May be wrong, but it's the
533 * only thing we can do at the moment.
534 * Used only by usb drivers?
535 */
536 return 0;
537 if (cap_issubset(p->cap_permitted, current->cap_permitted))
538 return 0;
539 if (capable(CAP_KILL))
540 return 0;
541
542 return -EPERM;
543}
544#else
545int cap_task_setscheduler (struct task_struct *p, int policy,
546 struct sched_param *lp)
547{
548 return 0;
549}
550int cap_task_setioprio (struct task_struct *p, int ioprio)
551{
552 return 0;
553}
554int cap_task_setnice (struct task_struct *p, int nice)
555{
556 return 0;
557}
558int cap_task_kill(struct task_struct *p, struct siginfo *info,
559 int sig, u32 secid)
560{
561 return 0;
562}
563#endif
564
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565void cap_task_reparent_to_init (struct task_struct *p)
566{
567 p->cap_effective = CAP_INIT_EFF_SET;
568 p->cap_inheritable = CAP_INIT_INH_SET;
569 p->cap_permitted = CAP_FULL_SET;
570 p->keep_capabilities = 0;
571 return;
572}
573
574int cap_syslog (int type)
575{
576 if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
577 return -EPERM;
578 return 0;
579}
580
Alan Cox34b4e4a2007-08-22 14:01:28 -0700581int cap_vm_enough_memory(struct mm_struct *mm, long pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582{
583 int cap_sys_admin = 0;
584
585 if (cap_capable(current, CAP_SYS_ADMIN) == 0)
586 cap_sys_admin = 1;
Alan Cox34b4e4a2007-08-22 14:01:28 -0700587 return __vm_enough_memory(mm, pages, cap_sys_admin);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588}
589