1 /* Task credentials management - see Documentation/security/credentials.rst
2 *
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11 #include <linux/export.h>
12 #include <linux/cred.h>
13 #include <linux/slab.h>
14 #include <linux/sched.h>
15 #include <linux/sched/coredump.h>
16 #include <linux/key.h>
17 #include <linux/keyctl.h>
18 #include <linux/init_task.h>
19 #include <linux/security.h>
20 #include <linux/binfmts.h>
21 #include <linux/cn_proc.h>
22
23 #if 0
24 #define kdebug(FMT, ...) \
25 printk("[%-5.5s%5u] " FMT "\n", \
26 current->comm, current->pid, ##__VA_ARGS__)
27 #else
28 #define kdebug(FMT, ...) \
29 do { \
30 if (0) \
31 no_printk("[%-5.5s%5u] " FMT "\n", \
32 current->comm, current->pid, ##__VA_ARGS__); \
33 } while (0)
34 #endif
35
36 static struct kmem_cache *cred_jar;
37
38 /* init to 2 - one for init_task, one to ensure it is never freed */
39 struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
40
41 /*
42 * The initial credentials for the initial task
43 */
44 struct cred init_cred = {
45 .usage = ATOMIC_INIT(4),
46 #ifdef CONFIG_DEBUG_CREDENTIALS
47 .subscribers = ATOMIC_INIT(2),
48 .magic = CRED_MAGIC,
49 #endif
50 .uid = GLOBAL_ROOT_UID,
51 .gid = GLOBAL_ROOT_GID,
52 .suid = GLOBAL_ROOT_UID,
53 .sgid = GLOBAL_ROOT_GID,
54 .euid = GLOBAL_ROOT_UID,
55 .egid = GLOBAL_ROOT_GID,
56 .fsuid = GLOBAL_ROOT_UID,
57 .fsgid = GLOBAL_ROOT_GID,
58 .securebits = SECUREBITS_DEFAULT,
59 .cap_inheritable = CAP_EMPTY_SET,
60 .cap_permitted = CAP_FULL_SET,
61 .cap_effective = CAP_FULL_SET,
62 .cap_bset = CAP_FULL_SET,
63 .user = INIT_USER,
64 .user_ns = &init_user_ns,
65 .group_info = &init_groups,
66 };
67
set_cred_subscribers(struct cred * cred,int n)68 static inline void set_cred_subscribers(struct cred *cred, int n)
69 {
70 #ifdef CONFIG_DEBUG_CREDENTIALS
71 atomic_set(&cred->subscribers, n);
72 #endif
73 }
74
read_cred_subscribers(const struct cred * cred)75 static inline int read_cred_subscribers(const struct cred *cred)
76 {
77 #ifdef CONFIG_DEBUG_CREDENTIALS
78 return atomic_read(&cred->subscribers);
79 #else
80 return 0;
81 #endif
82 }
83
alter_cred_subscribers(const struct cred * _cred,int n)84 static inline void alter_cred_subscribers(const struct cred *_cred, int n)
85 {
86 #ifdef CONFIG_DEBUG_CREDENTIALS
87 struct cred *cred = (struct cred *) _cred;
88
89 atomic_add(n, &cred->subscribers);
90 #endif
91 }
92
93 /*
94 * The RCU callback to actually dispose of a set of credentials
95 */
put_cred_rcu(struct rcu_head * rcu)96 static void put_cred_rcu(struct rcu_head *rcu)
97 {
98 struct cred *cred = container_of(rcu, struct cred, rcu);
99
100 kdebug("put_cred_rcu(%p)", cred);
101
102 #ifdef CONFIG_DEBUG_CREDENTIALS
103 if (cred->magic != CRED_MAGIC_DEAD ||
104 atomic_read(&cred->usage) != 0 ||
105 read_cred_subscribers(cred) != 0)
106 panic("CRED: put_cred_rcu() sees %p with"
107 " mag %x, put %p, usage %d, subscr %d\n",
108 cred, cred->magic, cred->put_addr,
109 atomic_read(&cred->usage),
110 read_cred_subscribers(cred));
111 #else
112 if (atomic_read(&cred->usage) != 0)
113 panic("CRED: put_cred_rcu() sees %p with usage %d\n",
114 cred, atomic_read(&cred->usage));
115 #endif
116
117 security_cred_free(cred);
118 key_put(cred->session_keyring);
119 key_put(cred->process_keyring);
120 key_put(cred->thread_keyring);
121 key_put(cred->request_key_auth);
122 if (cred->group_info)
123 put_group_info(cred->group_info);
124 free_uid(cred->user);
125 put_user_ns(cred->user_ns);
126 kmem_cache_free(cred_jar, cred);
127 }
128
129 /**
130 * __put_cred - Destroy a set of credentials
131 * @cred: The record to release
132 *
133 * Destroy a set of credentials on which no references remain.
134 */
__put_cred(struct cred * cred)135 void __put_cred(struct cred *cred)
136 {
137 kdebug("__put_cred(%p{%d,%d})", cred,
138 atomic_read(&cred->usage),
139 read_cred_subscribers(cred));
140
141 BUG_ON(atomic_read(&cred->usage) != 0);
142 #ifdef CONFIG_DEBUG_CREDENTIALS
143 BUG_ON(read_cred_subscribers(cred) != 0);
144 cred->magic = CRED_MAGIC_DEAD;
145 cred->put_addr = __builtin_return_address(0);
146 #endif
147 BUG_ON(cred == current->cred);
148 BUG_ON(cred == current->real_cred);
149
150 call_rcu(&cred->rcu, put_cred_rcu);
151 }
152 EXPORT_SYMBOL(__put_cred);
153
154 /*
155 * Clean up a task's credentials when it exits
156 */
exit_creds(struct task_struct * tsk)157 void exit_creds(struct task_struct *tsk)
158 {
159 struct cred *cred;
160
161 kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
162 atomic_read(&tsk->cred->usage),
163 read_cred_subscribers(tsk->cred));
164
165 cred = (struct cred *) tsk->real_cred;
166 tsk->real_cred = NULL;
167 validate_creds(cred);
168 alter_cred_subscribers(cred, -1);
169 put_cred(cred);
170
171 cred = (struct cred *) tsk->cred;
172 tsk->cred = NULL;
173 validate_creds(cred);
174 alter_cred_subscribers(cred, -1);
175 put_cred(cred);
176 }
177
178 /**
179 * get_task_cred - Get another task's objective credentials
180 * @task: The task to query
181 *
182 * Get the objective credentials of a task, pinning them so that they can't go
183 * away. Accessing a task's credentials directly is not permitted.
184 *
185 * The caller must also make sure task doesn't get deleted, either by holding a
186 * ref on task or by holding tasklist_lock to prevent it from being unlinked.
187 */
get_task_cred(struct task_struct * task)188 const struct cred *get_task_cred(struct task_struct *task)
189 {
190 const struct cred *cred;
191
192 rcu_read_lock();
193
194 do {
195 cred = __task_cred((task));
196 BUG_ON(!cred);
197 } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage));
198
199 rcu_read_unlock();
200 return cred;
201 }
202
203 /*
204 * Allocate blank credentials, such that the credentials can be filled in at a
205 * later date without risk of ENOMEM.
206 */
cred_alloc_blank(void)207 struct cred *cred_alloc_blank(void)
208 {
209 struct cred *new;
210
211 new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
212 if (!new)
213 return NULL;
214
215 atomic_set(&new->usage, 1);
216 #ifdef CONFIG_DEBUG_CREDENTIALS
217 new->magic = CRED_MAGIC;
218 #endif
219
220 if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
221 goto error;
222
223 return new;
224
225 error:
226 abort_creds(new);
227 return NULL;
228 }
229
230 /**
231 * prepare_creds - Prepare a new set of credentials for modification
232 *
233 * Prepare a new set of task credentials for modification. A task's creds
234 * shouldn't generally be modified directly, therefore this function is used to
235 * prepare a new copy, which the caller then modifies and then commits by
236 * calling commit_creds().
237 *
238 * Preparation involves making a copy of the objective creds for modification.
239 *
240 * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
241 *
242 * Call commit_creds() or abort_creds() to clean up.
243 */
prepare_creds(void)244 struct cred *prepare_creds(void)
245 {
246 struct task_struct *task = current;
247 const struct cred *old;
248 struct cred *new;
249
250 validate_process_creds();
251
252 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
253 if (!new)
254 return NULL;
255
256 kdebug("prepare_creds() alloc %p", new);
257
258 old = task->cred;
259 memcpy(new, old, sizeof(struct cred));
260
261 atomic_set(&new->usage, 1);
262 set_cred_subscribers(new, 0);
263 get_group_info(new->group_info);
264 get_uid(new->user);
265 get_user_ns(new->user_ns);
266
267 #ifdef CONFIG_KEYS
268 key_get(new->session_keyring);
269 key_get(new->process_keyring);
270 key_get(new->thread_keyring);
271 key_get(new->request_key_auth);
272 #endif
273
274 #ifdef CONFIG_SECURITY
275 new->security = NULL;
276 #endif
277
278 if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
279 goto error;
280 validate_creds(new);
281 return new;
282
283 error:
284 abort_creds(new);
285 return NULL;
286 }
287 EXPORT_SYMBOL(prepare_creds);
288
289 /*
290 * Prepare credentials for current to perform an execve()
291 * - The caller must hold ->cred_guard_mutex
292 */
prepare_exec_creds(void)293 struct cred *prepare_exec_creds(void)
294 {
295 struct cred *new;
296
297 new = prepare_creds();
298 if (!new)
299 return new;
300
301 #ifdef CONFIG_KEYS
302 /* newly exec'd tasks don't get a thread keyring */
303 key_put(new->thread_keyring);
304 new->thread_keyring = NULL;
305
306 /* inherit the session keyring; new process keyring */
307 key_put(new->process_keyring);
308 new->process_keyring = NULL;
309 #endif
310
311 return new;
312 }
313
314 /*
315 * Copy credentials for the new process created by fork()
316 *
317 * We share if we can, but under some circumstances we have to generate a new
318 * set.
319 *
320 * The new process gets the current process's subjective credentials as its
321 * objective and subjective credentials
322 */
copy_creds(struct task_struct * p,unsigned long clone_flags)323 int copy_creds(struct task_struct *p, unsigned long clone_flags)
324 {
325 struct cred *new;
326 int ret;
327
328 if (
329 #ifdef CONFIG_KEYS
330 !p->cred->thread_keyring &&
331 #endif
332 clone_flags & CLONE_THREAD
333 ) {
334 p->real_cred = get_cred(p->cred);
335 get_cred(p->cred);
336 alter_cred_subscribers(p->cred, 2);
337 kdebug("share_creds(%p{%d,%d})",
338 p->cred, atomic_read(&p->cred->usage),
339 read_cred_subscribers(p->cred));
340 atomic_inc(&p->cred->user->processes);
341 return 0;
342 }
343
344 new = prepare_creds();
345 if (!new)
346 return -ENOMEM;
347
348 if (clone_flags & CLONE_NEWUSER) {
349 ret = create_user_ns(new);
350 if (ret < 0)
351 goto error_put;
352 }
353
354 #ifdef CONFIG_KEYS
355 /* new threads get their own thread keyrings if their parent already
356 * had one */
357 if (new->thread_keyring) {
358 key_put(new->thread_keyring);
359 new->thread_keyring = NULL;
360 if (clone_flags & CLONE_THREAD)
361 install_thread_keyring_to_cred(new);
362 }
363
364 /* The process keyring is only shared between the threads in a process;
365 * anything outside of those threads doesn't inherit.
366 */
367 if (!(clone_flags & CLONE_THREAD)) {
368 key_put(new->process_keyring);
369 new->process_keyring = NULL;
370 }
371 #endif
372
373 atomic_inc(&new->user->processes);
374 p->cred = p->real_cred = get_cred(new);
375 alter_cred_subscribers(new, 2);
376 validate_creds(new);
377 return 0;
378
379 error_put:
380 put_cred(new);
381 return ret;
382 }
383
cred_cap_issubset(const struct cred * set,const struct cred * subset)384 static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
385 {
386 const struct user_namespace *set_ns = set->user_ns;
387 const struct user_namespace *subset_ns = subset->user_ns;
388
389 /* If the two credentials are in the same user namespace see if
390 * the capabilities of subset are a subset of set.
391 */
392 if (set_ns == subset_ns)
393 return cap_issubset(subset->cap_permitted, set->cap_permitted);
394
395 /* The credentials are in a different user namespaces
396 * therefore one is a subset of the other only if a set is an
397 * ancestor of subset and set->euid is owner of subset or one
398 * of subsets ancestors.
399 */
400 for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
401 if ((set_ns == subset_ns->parent) &&
402 uid_eq(subset_ns->owner, set->euid))
403 return true;
404 }
405
406 return false;
407 }
408
409 /**
410 * commit_creds - Install new credentials upon the current task
411 * @new: The credentials to be assigned
412 *
413 * Install a new set of credentials to the current task, using RCU to replace
414 * the old set. Both the objective and the subjective credentials pointers are
415 * updated. This function may not be called if the subjective credentials are
416 * in an overridden state.
417 *
418 * This function eats the caller's reference to the new credentials.
419 *
420 * Always returns 0 thus allowing this function to be tail-called at the end
421 * of, say, sys_setgid().
422 */
commit_creds(struct cred * new)423 int commit_creds(struct cred *new)
424 {
425 struct task_struct *task = current;
426 const struct cred *old = task->real_cred;
427
428 kdebug("commit_creds(%p{%d,%d})", new,
429 atomic_read(&new->usage),
430 read_cred_subscribers(new));
431
432 BUG_ON(task->cred != old);
433 #ifdef CONFIG_DEBUG_CREDENTIALS
434 BUG_ON(read_cred_subscribers(old) < 2);
435 validate_creds(old);
436 validate_creds(new);
437 #endif
438 BUG_ON(atomic_read(&new->usage) < 1);
439
440 get_cred(new); /* we will require a ref for the subj creds too */
441
442 /* dumpability changes */
443 if (!uid_eq(old->euid, new->euid) ||
444 !gid_eq(old->egid, new->egid) ||
445 !uid_eq(old->fsuid, new->fsuid) ||
446 !gid_eq(old->fsgid, new->fsgid) ||
447 !cred_cap_issubset(old, new)) {
448 if (task->mm)
449 set_dumpable(task->mm, suid_dumpable);
450 task->pdeath_signal = 0;
451 smp_wmb();
452 }
453
454 /* alter the thread keyring */
455 if (!uid_eq(new->fsuid, old->fsuid))
456 key_fsuid_changed(task);
457 if (!gid_eq(new->fsgid, old->fsgid))
458 key_fsgid_changed(task);
459
460 /* do it
461 * RLIMIT_NPROC limits on user->processes have already been checked
462 * in set_user().
463 */
464 alter_cred_subscribers(new, 2);
465 if (new->user != old->user)
466 atomic_inc(&new->user->processes);
467 rcu_assign_pointer(task->real_cred, new);
468 rcu_assign_pointer(task->cred, new);
469 if (new->user != old->user)
470 atomic_dec(&old->user->processes);
471 alter_cred_subscribers(old, -2);
472
473 /* send notifications */
474 if (!uid_eq(new->uid, old->uid) ||
475 !uid_eq(new->euid, old->euid) ||
476 !uid_eq(new->suid, old->suid) ||
477 !uid_eq(new->fsuid, old->fsuid))
478 proc_id_connector(task, PROC_EVENT_UID);
479
480 if (!gid_eq(new->gid, old->gid) ||
481 !gid_eq(new->egid, old->egid) ||
482 !gid_eq(new->sgid, old->sgid) ||
483 !gid_eq(new->fsgid, old->fsgid))
484 proc_id_connector(task, PROC_EVENT_GID);
485
486 /* release the old obj and subj refs both */
487 put_cred(old);
488 put_cred(old);
489 return 0;
490 }
491 EXPORT_SYMBOL(commit_creds);
492
493 /**
494 * abort_creds - Discard a set of credentials and unlock the current task
495 * @new: The credentials that were going to be applied
496 *
497 * Discard a set of credentials that were under construction and unlock the
498 * current task.
499 */
abort_creds(struct cred * new)500 void abort_creds(struct cred *new)
501 {
502 kdebug("abort_creds(%p{%d,%d})", new,
503 atomic_read(&new->usage),
504 read_cred_subscribers(new));
505
506 #ifdef CONFIG_DEBUG_CREDENTIALS
507 BUG_ON(read_cred_subscribers(new) != 0);
508 #endif
509 BUG_ON(atomic_read(&new->usage) < 1);
510 put_cred(new);
511 }
512 EXPORT_SYMBOL(abort_creds);
513
514 /**
515 * override_creds - Override the current process's subjective credentials
516 * @new: The credentials to be assigned
517 *
518 * Install a set of temporary override subjective credentials on the current
519 * process, returning the old set for later reversion.
520 */
override_creds(const struct cred * new)521 const struct cred *override_creds(const struct cred *new)
522 {
523 const struct cred *old = current->cred;
524
525 kdebug("override_creds(%p{%d,%d})", new,
526 atomic_read(&new->usage),
527 read_cred_subscribers(new));
528
529 validate_creds(old);
530 validate_creds(new);
531 get_cred(new);
532 alter_cred_subscribers(new, 1);
533 rcu_assign_pointer(current->cred, new);
534 alter_cred_subscribers(old, -1);
535
536 kdebug("override_creds() = %p{%d,%d}", old,
537 atomic_read(&old->usage),
538 read_cred_subscribers(old));
539 return old;
540 }
541 EXPORT_SYMBOL(override_creds);
542
543 /**
544 * revert_creds - Revert a temporary subjective credentials override
545 * @old: The credentials to be restored
546 *
547 * Revert a temporary set of override subjective credentials to an old set,
548 * discarding the override set.
549 */
revert_creds(const struct cred * old)550 void revert_creds(const struct cred *old)
551 {
552 const struct cred *override = current->cred;
553
554 kdebug("revert_creds(%p{%d,%d})", old,
555 atomic_read(&old->usage),
556 read_cred_subscribers(old));
557
558 validate_creds(old);
559 validate_creds(override);
560 alter_cred_subscribers(old, 1);
561 rcu_assign_pointer(current->cred, old);
562 alter_cred_subscribers(override, -1);
563 put_cred(override);
564 }
565 EXPORT_SYMBOL(revert_creds);
566
567 /*
568 * initialise the credentials stuff
569 */
cred_init(void)570 void __init cred_init(void)
571 {
572 /* allocate a slab in which we can store credentials */
573 cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
574 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
575 }
576
577 /**
578 * prepare_kernel_cred - Prepare a set of credentials for a kernel service
579 * @daemon: A userspace daemon to be used as a reference
580 *
581 * Prepare a set of credentials for a kernel service. This can then be used to
582 * override a task's own credentials so that work can be done on behalf of that
583 * task that requires a different subjective context.
584 *
585 * @daemon is used to provide a base for the security record, but can be NULL.
586 * If @daemon is supplied, then the security data will be derived from that;
587 * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
588 *
589 * The caller may change these controls afterwards if desired.
590 *
591 * Returns the new credentials or NULL if out of memory.
592 *
593 * Does not take, and does not return holding current->cred_replace_mutex.
594 */
prepare_kernel_cred(struct task_struct * daemon)595 struct cred *prepare_kernel_cred(struct task_struct *daemon)
596 {
597 const struct cred *old;
598 struct cred *new;
599
600 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
601 if (!new)
602 return NULL;
603
604 kdebug("prepare_kernel_cred() alloc %p", new);
605
606 if (daemon)
607 old = get_task_cred(daemon);
608 else
609 old = get_cred(&init_cred);
610
611 validate_creds(old);
612
613 *new = *old;
614 atomic_set(&new->usage, 1);
615 set_cred_subscribers(new, 0);
616 get_uid(new->user);
617 get_user_ns(new->user_ns);
618 get_group_info(new->group_info);
619
620 #ifdef CONFIG_KEYS
621 new->session_keyring = NULL;
622 new->process_keyring = NULL;
623 new->thread_keyring = NULL;
624 new->request_key_auth = NULL;
625 new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
626 #endif
627
628 #ifdef CONFIG_SECURITY
629 new->security = NULL;
630 #endif
631 if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
632 goto error;
633
634 put_cred(old);
635 validate_creds(new);
636 return new;
637
638 error:
639 put_cred(new);
640 put_cred(old);
641 return NULL;
642 }
643 EXPORT_SYMBOL(prepare_kernel_cred);
644
645 /**
646 * set_security_override - Set the security ID in a set of credentials
647 * @new: The credentials to alter
648 * @secid: The LSM security ID to set
649 *
650 * Set the LSM security ID in a set of credentials so that the subjective
651 * security is overridden when an alternative set of credentials is used.
652 */
set_security_override(struct cred * new,u32 secid)653 int set_security_override(struct cred *new, u32 secid)
654 {
655 return security_kernel_act_as(new, secid);
656 }
657 EXPORT_SYMBOL(set_security_override);
658
659 /**
660 * set_security_override_from_ctx - Set the security ID in a set of credentials
661 * @new: The credentials to alter
662 * @secctx: The LSM security context to generate the security ID from.
663 *
664 * Set the LSM security ID in a set of credentials so that the subjective
665 * security is overridden when an alternative set of credentials is used. The
666 * security ID is specified in string form as a security context to be
667 * interpreted by the LSM.
668 */
set_security_override_from_ctx(struct cred * new,const char * secctx)669 int set_security_override_from_ctx(struct cred *new, const char *secctx)
670 {
671 u32 secid;
672 int ret;
673
674 ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
675 if (ret < 0)
676 return ret;
677
678 return set_security_override(new, secid);
679 }
680 EXPORT_SYMBOL(set_security_override_from_ctx);
681
682 /**
683 * set_create_files_as - Set the LSM file create context in a set of credentials
684 * @new: The credentials to alter
685 * @inode: The inode to take the context from
686 *
687 * Change the LSM file creation context in a set of credentials to be the same
688 * as the object context of the specified inode, so that the new inodes have
689 * the same MAC context as that inode.
690 */
set_create_files_as(struct cred * new,struct inode * inode)691 int set_create_files_as(struct cred *new, struct inode *inode)
692 {
693 if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
694 return -EINVAL;
695 new->fsuid = inode->i_uid;
696 new->fsgid = inode->i_gid;
697 return security_kernel_create_files_as(new, inode);
698 }
699 EXPORT_SYMBOL(set_create_files_as);
700
701 #ifdef CONFIG_DEBUG_CREDENTIALS
702
creds_are_invalid(const struct cred * cred)703 bool creds_are_invalid(const struct cred *cred)
704 {
705 if (cred->magic != CRED_MAGIC)
706 return true;
707 #ifdef CONFIG_SECURITY_SELINUX
708 /*
709 * cred->security == NULL if security_cred_alloc_blank() or
710 * security_prepare_creds() returned an error.
711 */
712 if (selinux_is_enabled() && cred->security) {
713 if ((unsigned long) cred->security < PAGE_SIZE)
714 return true;
715 if ((*(u32 *)cred->security & 0xffffff00) ==
716 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
717 return true;
718 }
719 #endif
720 return false;
721 }
722 EXPORT_SYMBOL(creds_are_invalid);
723
724 /*
725 * dump invalid credentials
726 */
dump_invalid_creds(const struct cred * cred,const char * label,const struct task_struct * tsk)727 static void dump_invalid_creds(const struct cred *cred, const char *label,
728 const struct task_struct *tsk)
729 {
730 printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
731 label, cred,
732 cred == &init_cred ? "[init]" : "",
733 cred == tsk->real_cred ? "[real]" : "",
734 cred == tsk->cred ? "[eff]" : "");
735 printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
736 cred->magic, cred->put_addr);
737 printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
738 atomic_read(&cred->usage),
739 read_cred_subscribers(cred));
740 printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
741 from_kuid_munged(&init_user_ns, cred->uid),
742 from_kuid_munged(&init_user_ns, cred->euid),
743 from_kuid_munged(&init_user_ns, cred->suid),
744 from_kuid_munged(&init_user_ns, cred->fsuid));
745 printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
746 from_kgid_munged(&init_user_ns, cred->gid),
747 from_kgid_munged(&init_user_ns, cred->egid),
748 from_kgid_munged(&init_user_ns, cred->sgid),
749 from_kgid_munged(&init_user_ns, cred->fsgid));
750 #ifdef CONFIG_SECURITY
751 printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
752 if ((unsigned long) cred->security >= PAGE_SIZE &&
753 (((unsigned long) cred->security & 0xffffff00) !=
754 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
755 printk(KERN_ERR "CRED: ->security {%x, %x}\n",
756 ((u32*)cred->security)[0],
757 ((u32*)cred->security)[1]);
758 #endif
759 }
760
761 /*
762 * report use of invalid credentials
763 */
__invalid_creds(const struct cred * cred,const char * file,unsigned line)764 void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
765 {
766 printk(KERN_ERR "CRED: Invalid credentials\n");
767 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
768 dump_invalid_creds(cred, "Specified", current);
769 BUG();
770 }
771 EXPORT_SYMBOL(__invalid_creds);
772
773 /*
774 * check the credentials on a process
775 */
__validate_process_creds(struct task_struct * tsk,const char * file,unsigned line)776 void __validate_process_creds(struct task_struct *tsk,
777 const char *file, unsigned line)
778 {
779 if (tsk->cred == tsk->real_cred) {
780 if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
781 creds_are_invalid(tsk->cred)))
782 goto invalid_creds;
783 } else {
784 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
785 read_cred_subscribers(tsk->cred) < 1 ||
786 creds_are_invalid(tsk->real_cred) ||
787 creds_are_invalid(tsk->cred)))
788 goto invalid_creds;
789 }
790 return;
791
792 invalid_creds:
793 printk(KERN_ERR "CRED: Invalid process credentials\n");
794 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
795
796 dump_invalid_creds(tsk->real_cred, "Real", tsk);
797 if (tsk->cred != tsk->real_cred)
798 dump_invalid_creds(tsk->cred, "Effective", tsk);
799 else
800 printk(KERN_ERR "CRED: Effective creds == Real creds\n");
801 BUG();
802 }
803 EXPORT_SYMBOL(__validate_process_creds);
804
805 /*
806 * check creds for do_exit()
807 */
validate_creds_for_do_exit(struct task_struct * tsk)808 void validate_creds_for_do_exit(struct task_struct *tsk)
809 {
810 kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
811 tsk->real_cred, tsk->cred,
812 atomic_read(&tsk->cred->usage),
813 read_cred_subscribers(tsk->cred));
814
815 __validate_process_creds(tsk, __FILE__, __LINE__);
816 }
817
818 #endif /* CONFIG_DEBUG_CREDENTIALS */
819
