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#include <linux/uidgid.h>
23
24#if 0
25#define kdebug(FMT, ...) \
26 printk("[%-5.5s%5u] " FMT "\n", \
27 current->comm, current->pid, ##__VA_ARGS__)
28#else
29#define kdebug(FMT, ...) \
30do { \
31 if (0) \
32 no_printk("[%-5.5s%5u] " FMT "\n", \
33 current->comm, current->pid, ##__VA_ARGS__); \
34} while (0)
35#endif
36
37static struct kmem_cache *cred_jar;
38
39/* init to 2 - one for init_task, one to ensure it is never freed */
40struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
41
42/*
43 * The initial credentials for the initial task
44 */
45struct cred init_cred = {
46 .usage = ATOMIC_INIT(4),
47#ifdef CONFIG_DEBUG_CREDENTIALS
48 .subscribers = ATOMIC_INIT(2),
49 .magic = CRED_MAGIC,
50#endif
51 .uid = GLOBAL_ROOT_UID,
52 .gid = GLOBAL_ROOT_GID,
53 .suid = GLOBAL_ROOT_UID,
54 .sgid = GLOBAL_ROOT_GID,
55 .euid = GLOBAL_ROOT_UID,
56 .egid = GLOBAL_ROOT_GID,
57 .fsuid = GLOBAL_ROOT_UID,
58 .fsgid = GLOBAL_ROOT_GID,
59 .securebits = SECUREBITS_DEFAULT,
60 .cap_inheritable = CAP_EMPTY_SET,
61 .cap_permitted = CAP_FULL_SET,
62 .cap_effective = CAP_FULL_SET,
63 .cap_bset = CAP_FULL_SET,
64 .user = INIT_USER,
65 .user_ns = &init_user_ns,
66 .group_info = &init_groups,
67};
68
69static inline void set_cred_subscribers(struct cred *cred, int n)
70{
71#ifdef CONFIG_DEBUG_CREDENTIALS
72 atomic_set(&cred->subscribers, n);
73#endif
74}
75
76static inline int read_cred_subscribers(const struct cred *cred)
77{
78#ifdef CONFIG_DEBUG_CREDENTIALS
79 return atomic_read(&cred->subscribers);
80#else
81 return 0;
82#endif
83}
84
85static inline void alter_cred_subscribers(const struct cred *_cred, int n)
86{
87#ifdef CONFIG_DEBUG_CREDENTIALS
88 struct cred *cred = (struct cred *) _cred;
89
90 atomic_add(n, &cred->subscribers);
91#endif
92}
93
94/*
95 * The RCU callback to actually dispose of a set of credentials
96 */
97static void put_cred_rcu(struct rcu_head *rcu)
98{
99 struct cred *cred = container_of(rcu, struct cred, rcu);
100
101 kdebug("put_cred_rcu(%p)", cred);
102
103#ifdef CONFIG_DEBUG_CREDENTIALS
104 if (cred->magic != CRED_MAGIC_DEAD ||
105 atomic_read(&cred->usage) != 0 ||
106 read_cred_subscribers(cred) != 0)
107 panic("CRED: put_cred_rcu() sees %p with"
108 " mag %x, put %p, usage %d, subscr %d\n",
109 cred, cred->magic, cred->put_addr,
110 atomic_read(&cred->usage),
111 read_cred_subscribers(cred));
112#else
113 if (atomic_read(&cred->usage) != 0)
114 panic("CRED: put_cred_rcu() sees %p with usage %d\n",
115 cred, atomic_read(&cred->usage));
116#endif
117
118 security_cred_free(cred);
119 key_put(cred->session_keyring);
120 key_put(cred->process_keyring);
121 key_put(cred->thread_keyring);
122 key_put(cred->request_key_auth);
123 if (cred->group_info)
124 put_group_info(cred->group_info);
125 free_uid(cred->user);
126 put_user_ns(cred->user_ns);
127 kmem_cache_free(cred_jar, cred);
128}
129
130/**
131 * __put_cred - Destroy a set of credentials
132 * @cred: The record to release
133 *
134 * Destroy a set of credentials on which no references remain.
135 */
136void __put_cred(struct cred *cred)
137{
138 kdebug("__put_cred(%p{%d,%d})", cred,
139 atomic_read(&cred->usage),
140 read_cred_subscribers(cred));
141
142 BUG_ON(atomic_read(&cred->usage) != 0);
143#ifdef CONFIG_DEBUG_CREDENTIALS
144 BUG_ON(read_cred_subscribers(cred) != 0);
145 cred->magic = CRED_MAGIC_DEAD;
146 cred->put_addr = __builtin_return_address(0);
147#endif
148 BUG_ON(cred == current->cred);
149 BUG_ON(cred == current->real_cred);
150
151 call_rcu(&cred->rcu, put_cred_rcu);
152}
153EXPORT_SYMBOL(__put_cred);
154
155/*
156 * Clean up a task's credentials when it exits
157 */
158void exit_creds(struct task_struct *tsk)
159{
160 struct cred *cred;
161
162 kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
163 atomic_read(&tsk->cred->usage),
164 read_cred_subscribers(tsk->cred));
165
166 cred = (struct cred *) tsk->real_cred;
167 tsk->real_cred = NULL;
168 validate_creds(cred);
169 alter_cred_subscribers(cred, -1);
170 put_cred(cred);
171
172 cred = (struct cred *) tsk->cred;
173 tsk->cred = NULL;
174 validate_creds(cred);
175 alter_cred_subscribers(cred, -1);
176 put_cred(cred);
177}
178
179/**
180 * get_task_cred - Get another task's objective credentials
181 * @task: The task to query
182 *
183 * Get the objective credentials of a task, pinning them so that they can't go
184 * away. Accessing a task's credentials directly is not permitted.
185 *
186 * The caller must also make sure task doesn't get deleted, either by holding a
187 * ref on task or by holding tasklist_lock to prevent it from being unlinked.
188 */
189const struct cred *get_task_cred(struct task_struct *task)
190{
191 const struct cred *cred;
192
193 rcu_read_lock();
194
195 do {
196 cred = __task_cred((task));
197 BUG_ON(!cred);
198 } while (!get_cred_rcu(cred));
199
200 rcu_read_unlock();
201 return cred;
202}
203EXPORT_SYMBOL(get_task_cred);
204
205/*
206 * Allocate blank credentials, such that the credentials can be filled in at a
207 * later date without risk of ENOMEM.
208 */
209struct cred *cred_alloc_blank(void)
210{
211 struct cred *new;
212
213 new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
214 if (!new)
215 return NULL;
216
217 atomic_set(&new->usage, 1);
218#ifdef CONFIG_DEBUG_CREDENTIALS
219 new->magic = CRED_MAGIC;
220#endif
221
222 if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
223 goto error;
224
225 return new;
226
227error:
228 abort_creds(new);
229 return NULL;
230}
231
232/**
233 * prepare_creds - Prepare a new set of credentials for modification
234 *
235 * Prepare a new set of task credentials for modification. A task's creds
236 * shouldn't generally be modified directly, therefore this function is used to
237 * prepare a new copy, which the caller then modifies and then commits by
238 * calling commit_creds().
239 *
240 * Preparation involves making a copy of the objective creds for modification.
241 *
242 * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
243 *
244 * Call commit_creds() or abort_creds() to clean up.
245 */
246struct cred *prepare_creds(void)
247{
248 struct task_struct *task = current;
249 const struct cred *old;
250 struct cred *new;
251
252 validate_process_creds();
253
254 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
255 if (!new)
256 return NULL;
257
258 kdebug("prepare_creds() alloc %p", new);
259
260 old = task->cred;
261 memcpy(new, old, sizeof(struct cred));
262
263 atomic_set(&new->usage, 1);
264 set_cred_subscribers(new, 0);
265 get_group_info(new->group_info);
266 get_uid(new->user);
267 get_user_ns(new->user_ns);
268
269#ifdef CONFIG_KEYS
270 key_get(new->session_keyring);
271 key_get(new->process_keyring);
272 key_get(new->thread_keyring);
273 key_get(new->request_key_auth);
274#endif
275
276#ifdef CONFIG_SECURITY
277 new->security = NULL;
278#endif
279
280 if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
281 goto error;
282 validate_creds(new);
283 return new;
284
285error:
286 abort_creds(new);
287 return NULL;
288}
289EXPORT_SYMBOL(prepare_creds);
290
291/*
292 * Prepare credentials for current to perform an execve()
293 * - The caller must hold ->cred_guard_mutex
294 */
295struct cred *prepare_exec_creds(void)
296{
297 struct cred *new;
298
299 new = prepare_creds();
300 if (!new)
301 return new;
302
303#ifdef CONFIG_KEYS
304 /* newly exec'd tasks don't get a thread keyring */
305 key_put(new->thread_keyring);
306 new->thread_keyring = NULL;
307
308 /* inherit the session keyring; new process keyring */
309 key_put(new->process_keyring);
310 new->process_keyring = NULL;
311#endif
312
313 return new;
314}
315
316/*
317 * Copy credentials for the new process created by fork()
318 *
319 * We share if we can, but under some circumstances we have to generate a new
320 * set.
321 *
322 * The new process gets the current process's subjective credentials as its
323 * objective and subjective credentials
324 */
325int copy_creds(struct task_struct *p, unsigned long clone_flags)
326{
327 struct cred *new;
328 int ret;
329
330 if (
331#ifdef CONFIG_KEYS
332 !p->cred->thread_keyring &&
333#endif
334 clone_flags & CLONE_THREAD
335 ) {
336 p->real_cred = get_cred(p->cred);
337 get_cred(p->cred);
338 alter_cred_subscribers(p->cred, 2);
339 kdebug("share_creds(%p{%d,%d})",
340 p->cred, atomic_read(&p->cred->usage),
341 read_cred_subscribers(p->cred));
342 atomic_inc(&p->cred->user->processes);
343 return 0;
344 }
345
346 new = prepare_creds();
347 if (!new)
348 return -ENOMEM;
349
350 if (clone_flags & CLONE_NEWUSER) {
351 ret = create_user_ns(new);
352 if (ret < 0)
353 goto error_put;
354 }
355
356#ifdef CONFIG_KEYS
357 /* new threads get their own thread keyrings if their parent already
358 * had one */
359 if (new->thread_keyring) {
360 key_put(new->thread_keyring);
361 new->thread_keyring = NULL;
362 if (clone_flags & CLONE_THREAD)
363 install_thread_keyring_to_cred(new);
364 }
365
366 /* The process keyring is only shared between the threads in a process;
367 * anything outside of those threads doesn't inherit.
368 */
369 if (!(clone_flags & CLONE_THREAD)) {
370 key_put(new->process_keyring);
371 new->process_keyring = NULL;
372 }
373#endif
374
375 atomic_inc(&new->user->processes);
376 p->cred = p->real_cred = get_cred(new);
377 alter_cred_subscribers(new, 2);
378 validate_creds(new);
379 return 0;
380
381error_put:
382 put_cred(new);
383 return ret;
384}
385
386static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
387{
388 const struct user_namespace *set_ns = set->user_ns;
389 const struct user_namespace *subset_ns = subset->user_ns;
390
391 /* If the two credentials are in the same user namespace see if
392 * the capabilities of subset are a subset of set.
393 */
394 if (set_ns == subset_ns)
395 return cap_issubset(subset->cap_permitted, set->cap_permitted);
396
397 /* The credentials are in a different user namespaces
398 * therefore one is a subset of the other only if a set is an
399 * ancestor of subset and set->euid is owner of subset or one
400 * of subsets ancestors.
401 */
402 for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
403 if ((set_ns == subset_ns->parent) &&
404 uid_eq(subset_ns->owner, set->euid))
405 return true;
406 }
407
408 return false;
409}
410
411/**
412 * commit_creds - Install new credentials upon the current task
413 * @new: The credentials to be assigned
414 *
415 * Install a new set of credentials to the current task, using RCU to replace
416 * the old set. Both the objective and the subjective credentials pointers are
417 * updated. This function may not be called if the subjective credentials are
418 * in an overridden state.
419 *
420 * This function eats the caller's reference to the new credentials.
421 *
422 * Always returns 0 thus allowing this function to be tail-called at the end
423 * of, say, sys_setgid().
424 */
425int commit_creds(struct cred *new)
426{
427 struct task_struct *task = current;
428 const struct cred *old = task->real_cred;
429
430 kdebug("commit_creds(%p{%d,%d})", new,
431 atomic_read(&new->usage),
432 read_cred_subscribers(new));
433
434 BUG_ON(task->cred != old);
435#ifdef CONFIG_DEBUG_CREDENTIALS
436 BUG_ON(read_cred_subscribers(old) < 2);
437 validate_creds(old);
438 validate_creds(new);
439#endif
440 BUG_ON(atomic_read(&new->usage) < 1);
441
442 get_cred(new); /* we will require a ref for the subj creds too */
443
444 /* dumpability changes */
445 if (!uid_eq(old->euid, new->euid) ||
446 !gid_eq(old->egid, new->egid) ||
447 !uid_eq(old->fsuid, new->fsuid) ||
448 !gid_eq(old->fsgid, new->fsgid) ||
449 !cred_cap_issubset(old, new)) {
450 if (task->mm)
451 set_dumpable(task->mm, suid_dumpable);
452 task->pdeath_signal = 0;
453 smp_wmb();
454 }
455
456 /* alter the thread keyring */
457 if (!uid_eq(new->fsuid, old->fsuid))
458 key_fsuid_changed(task);
459 if (!gid_eq(new->fsgid, old->fsgid))
460 key_fsgid_changed(task);
461
462 /* do it
463 * RLIMIT_NPROC limits on user->processes have already been checked
464 * in set_user().
465 */
466 alter_cred_subscribers(new, 2);
467 if (new->user != old->user)
468 atomic_inc(&new->user->processes);
469 rcu_assign_pointer(task->real_cred, new);
470 rcu_assign_pointer(task->cred, new);
471 if (new->user != old->user)
472 atomic_dec(&old->user->processes);
473 alter_cred_subscribers(old, -2);
474
475 /* send notifications */
476 if (!uid_eq(new->uid, old->uid) ||
477 !uid_eq(new->euid, old->euid) ||
478 !uid_eq(new->suid, old->suid) ||
479 !uid_eq(new->fsuid, old->fsuid))
480 proc_id_connector(task, PROC_EVENT_UID);
481
482 if (!gid_eq(new->gid, old->gid) ||
483 !gid_eq(new->egid, old->egid) ||
484 !gid_eq(new->sgid, old->sgid) ||
485 !gid_eq(new->fsgid, old->fsgid))
486 proc_id_connector(task, PROC_EVENT_GID);
487
488 /* release the old obj and subj refs both */
489 put_cred(old);
490 put_cred(old);
491 return 0;
492}
493EXPORT_SYMBOL(commit_creds);
494
495/**
496 * abort_creds - Discard a set of credentials and unlock the current task
497 * @new: The credentials that were going to be applied
498 *
499 * Discard a set of credentials that were under construction and unlock the
500 * current task.
501 */
502void abort_creds(struct cred *new)
503{
504 kdebug("abort_creds(%p{%d,%d})", new,
505 atomic_read(&new->usage),
506 read_cred_subscribers(new));
507
508#ifdef CONFIG_DEBUG_CREDENTIALS
509 BUG_ON(read_cred_subscribers(new) != 0);
510#endif
511 BUG_ON(atomic_read(&new->usage) < 1);
512 put_cred(new);
513}
514EXPORT_SYMBOL(abort_creds);
515
516/**
517 * override_creds - Override the current process's subjective credentials
518 * @new: The credentials to be assigned
519 *
520 * Install a set of temporary override subjective credentials on the current
521 * process, returning the old set for later reversion.
522 */
523const struct cred *override_creds(const struct cred *new)
524{
525 const struct cred *old = current->cred;
526
527 kdebug("override_creds(%p{%d,%d})", new,
528 atomic_read(&new->usage),
529 read_cred_subscribers(new));
530
531 validate_creds(old);
532 validate_creds(new);
533 get_cred(new);
534 alter_cred_subscribers(new, 1);
535 rcu_assign_pointer(current->cred, new);
536 alter_cred_subscribers(old, -1);
537
538 kdebug("override_creds() = %p{%d,%d}", old,
539 atomic_read(&old->usage),
540 read_cred_subscribers(old));
541 return old;
542}
543EXPORT_SYMBOL(override_creds);
544
545/**
546 * revert_creds - Revert a temporary subjective credentials override
547 * @old: The credentials to be restored
548 *
549 * Revert a temporary set of override subjective credentials to an old set,
550 * discarding the override set.
551 */
552void revert_creds(const struct cred *old)
553{
554 const struct cred *override = current->cred;
555
556 kdebug("revert_creds(%p{%d,%d})", old,
557 atomic_read(&old->usage),
558 read_cred_subscribers(old));
559
560 validate_creds(old);
561 validate_creds(override);
562 alter_cred_subscribers(old, 1);
563 rcu_assign_pointer(current->cred, old);
564 alter_cred_subscribers(override, -1);
565 put_cred(override);
566}
567EXPORT_SYMBOL(revert_creds);
568
569/**
570 * cred_fscmp - Compare two credentials with respect to filesystem access.
571 * @a: The first credential
572 * @b: The second credential
573 *
574 * cred_cmp() will return zero if both credentials have the same
575 * fsuid, fsgid, and supplementary groups. That is, if they will both
576 * provide the same access to files based on mode/uid/gid.
577 * If the credentials are different, then either -1 or 1 will
578 * be returned depending on whether @a comes before or after @b
579 * respectively in an arbitrary, but stable, ordering of credentials.
580 *
581 * Return: -1, 0, or 1 depending on comparison
582 */
583int cred_fscmp(const struct cred *a, const struct cred *b)
584{
585 struct group_info *ga, *gb;
586 int g;
587
588 if (a == b)
589 return 0;
590 if (uid_lt(a->fsuid, b->fsuid))
591 return -1;
592 if (uid_gt(a->fsuid, b->fsuid))
593 return 1;
594
595 if (gid_lt(a->fsgid, b->fsgid))
596 return -1;
597 if (gid_gt(a->fsgid, b->fsgid))
598 return 1;
599
600 ga = a->group_info;
601 gb = b->group_info;
602 if (ga == gb)
603 return 0;
604 if (ga == NULL)
605 return -1;
606 if (gb == NULL)
607 return 1;
608 if (ga->ngroups < gb->ngroups)
609 return -1;
610 if (ga->ngroups > gb->ngroups)
611 return 1;
612
613 for (g = 0; g < ga->ngroups; g++) {
614 if (gid_lt(ga->gid[g], gb->gid[g]))
615 return -1;
616 if (gid_gt(ga->gid[g], gb->gid[g]))
617 return 1;
618 }
619 return 0;
620}
621EXPORT_SYMBOL(cred_fscmp);
622
623/*
624 * initialise the credentials stuff
625 */
626void __init cred_init(void)
627{
628 /* allocate a slab in which we can store credentials */
629 cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
630 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
631}
632
633/**
634 * prepare_kernel_cred - Prepare a set of credentials for a kernel service
635 * @daemon: A userspace daemon to be used as a reference
636 *
637 * Prepare a set of credentials for a kernel service. This can then be used to
638 * override a task's own credentials so that work can be done on behalf of that
639 * task that requires a different subjective context.
640 *
641 * @daemon is used to provide a base for the security record, but can be NULL.
642 * If @daemon is supplied, then the security data will be derived from that;
643 * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
644 *
645 * The caller may change these controls afterwards if desired.
646 *
647 * Returns the new credentials or NULL if out of memory.
648 *
649 * Does not take, and does not return holding current->cred_replace_mutex.
650 */
651struct cred *prepare_kernel_cred(struct task_struct *daemon)
652{
653 const struct cred *old;
654 struct cred *new;
655
656 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
657 if (!new)
658 return NULL;
659
660 kdebug("prepare_kernel_cred() alloc %p", new);
661
662 if (daemon)
663 old = get_task_cred(daemon);
664 else
665 old = get_cred(&init_cred);
666
667 validate_creds(old);
668
669 *new = *old;
670 atomic_set(&new->usage, 1);
671 set_cred_subscribers(new, 0);
672 get_uid(new->user);
673 get_user_ns(new->user_ns);
674 get_group_info(new->group_info);
675
676#ifdef CONFIG_KEYS
677 new->session_keyring = NULL;
678 new->process_keyring = NULL;
679 new->thread_keyring = NULL;
680 new->request_key_auth = NULL;
681 new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
682#endif
683
684#ifdef CONFIG_SECURITY
685 new->security = NULL;
686#endif
687 if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
688 goto error;
689
690 put_cred(old);
691 validate_creds(new);
692 return new;
693
694error:
695 put_cred(new);
696 put_cred(old);
697 return NULL;
698}
699EXPORT_SYMBOL(prepare_kernel_cred);
700
701/**
702 * set_security_override - Set the security ID in a set of credentials
703 * @new: The credentials to alter
704 * @secid: The LSM security ID to set
705 *
706 * Set the LSM security ID in a set of credentials so that the subjective
707 * security is overridden when an alternative set of credentials is used.
708 */
709int set_security_override(struct cred *new, u32 secid)
710{
711 return security_kernel_act_as(new, secid);
712}
713EXPORT_SYMBOL(set_security_override);
714
715/**
716 * set_security_override_from_ctx - Set the security ID in a set of credentials
717 * @new: The credentials to alter
718 * @secctx: The LSM security context to generate the security ID from.
719 *
720 * Set the LSM security ID in a set of credentials so that the subjective
721 * security is overridden when an alternative set of credentials is used. The
722 * security ID is specified in string form as a security context to be
723 * interpreted by the LSM.
724 */
725int set_security_override_from_ctx(struct cred *new, const char *secctx)
726{
727 u32 secid;
728 int ret;
729
730 ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
731 if (ret < 0)
732 return ret;
733
734 return set_security_override(new, secid);
735}
736EXPORT_SYMBOL(set_security_override_from_ctx);
737
738/**
739 * set_create_files_as - Set the LSM file create context in a set of credentials
740 * @new: The credentials to alter
741 * @inode: The inode to take the context from
742 *
743 * Change the LSM file creation context in a set of credentials to be the same
744 * as the object context of the specified inode, so that the new inodes have
745 * the same MAC context as that inode.
746 */
747int set_create_files_as(struct cred *new, struct inode *inode)
748{
749 if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
750 return -EINVAL;
751 new->fsuid = inode->i_uid;
752 new->fsgid = inode->i_gid;
753 return security_kernel_create_files_as(new, inode);
754}
755EXPORT_SYMBOL(set_create_files_as);
756
757#ifdef CONFIG_DEBUG_CREDENTIALS
758
759bool creds_are_invalid(const struct cred *cred)
760{
761 if (cred->magic != CRED_MAGIC)
762 return true;
763 return false;
764}
765EXPORT_SYMBOL(creds_are_invalid);
766
767/*
768 * dump invalid credentials
769 */
770static void dump_invalid_creds(const struct cred *cred, const char *label,
771 const struct task_struct *tsk)
772{
773 printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
774 label, cred,
775 cred == &init_cred ? "[init]" : "",
776 cred == tsk->real_cred ? "[real]" : "",
777 cred == tsk->cred ? "[eff]" : "");
778 printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
779 cred->magic, cred->put_addr);
780 printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
781 atomic_read(&cred->usage),
782 read_cred_subscribers(cred));
783 printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
784 from_kuid_munged(&init_user_ns, cred->uid),
785 from_kuid_munged(&init_user_ns, cred->euid),
786 from_kuid_munged(&init_user_ns, cred->suid),
787 from_kuid_munged(&init_user_ns, cred->fsuid));
788 printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
789 from_kgid_munged(&init_user_ns, cred->gid),
790 from_kgid_munged(&init_user_ns, cred->egid),
791 from_kgid_munged(&init_user_ns, cred->sgid),
792 from_kgid_munged(&init_user_ns, cred->fsgid));
793#ifdef CONFIG_SECURITY
794 printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
795 if ((unsigned long) cred->security >= PAGE_SIZE &&
796 (((unsigned long) cred->security & 0xffffff00) !=
797 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
798 printk(KERN_ERR "CRED: ->security {%x, %x}\n",
799 ((u32*)cred->security)[0],
800 ((u32*)cred->security)[1]);
801#endif
802}
803
804/*
805 * report use of invalid credentials
806 */
807void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
808{
809 printk(KERN_ERR "CRED: Invalid credentials\n");
810 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
811 dump_invalid_creds(cred, "Specified", current);
812 BUG();
813}
814EXPORT_SYMBOL(__invalid_creds);
815
816/*
817 * check the credentials on a process
818 */
819void __validate_process_creds(struct task_struct *tsk,
820 const char *file, unsigned line)
821{
822 if (tsk->cred == tsk->real_cred) {
823 if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
824 creds_are_invalid(tsk->cred)))
825 goto invalid_creds;
826 } else {
827 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
828 read_cred_subscribers(tsk->cred) < 1 ||
829 creds_are_invalid(tsk->real_cred) ||
830 creds_are_invalid(tsk->cred)))
831 goto invalid_creds;
832 }
833 return;
834
835invalid_creds:
836 printk(KERN_ERR "CRED: Invalid process credentials\n");
837 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
838
839 dump_invalid_creds(tsk->real_cred, "Real", tsk);
840 if (tsk->cred != tsk->real_cred)
841 dump_invalid_creds(tsk->cred, "Effective", tsk);
842 else
843 printk(KERN_ERR "CRED: Effective creds == Real creds\n");
844 BUG();
845}
846EXPORT_SYMBOL(__validate_process_creds);
847
848/*
849 * check creds for do_exit()
850 */
851void validate_creds_for_do_exit(struct task_struct *tsk)
852{
853 kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
854 tsk->real_cred, tsk->cred,
855 atomic_read(&tsk->cred->usage),
856 read_cred_subscribers(tsk->cred));
857
858 __validate_process_creds(tsk, __FILE__, __LINE__);
859}
860
861#endif /* CONFIG_DEBUG_CREDENTIALS */
862