Line data Source code
1 : /* Task credentials management - see Documentation/security/credentials.txt
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/key.h>
16 : #include <linux/keyctl.h>
17 : #include <linux/init_task.h>
18 : #include <linux/security.h>
19 : #include <linux/binfmts.h>
20 : #include <linux/cn_proc.h>
21 :
22 : #if 0
23 : #define kdebug(FMT, ...) \
24 : printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
25 : #else
26 : #define kdebug(FMT, ...) \
27 : no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
28 : #endif
29 :
30 : static struct kmem_cache *cred_jar;
31 :
32 : /*
33 : * The initial credentials for the initial task
34 : */
35 : struct cred init_cred = {
36 : .usage = ATOMIC_INIT(4),
37 : #ifdef CONFIG_DEBUG_CREDENTIALS
38 : .subscribers = ATOMIC_INIT(2),
39 : .magic = CRED_MAGIC,
40 : #endif
41 : .uid = GLOBAL_ROOT_UID,
42 : .gid = GLOBAL_ROOT_GID,
43 : .suid = GLOBAL_ROOT_UID,
44 : .sgid = GLOBAL_ROOT_GID,
45 : .euid = GLOBAL_ROOT_UID,
46 : .egid = GLOBAL_ROOT_GID,
47 : .fsuid = GLOBAL_ROOT_UID,
48 : .fsgid = GLOBAL_ROOT_GID,
49 : .securebits = SECUREBITS_DEFAULT,
50 : .cap_inheritable = CAP_EMPTY_SET,
51 : .cap_permitted = CAP_FULL_SET,
52 : .cap_effective = CAP_FULL_SET,
53 : .cap_bset = CAP_FULL_SET,
54 : .user = INIT_USER,
55 : .user_ns = &init_user_ns,
56 : .group_info = &init_groups,
57 : };
58 :
59 : static inline void set_cred_subscribers(struct cred *cred, int n)
60 : {
61 : #ifdef CONFIG_DEBUG_CREDENTIALS
62 : atomic_set(&cred->subscribers, n);
63 : #endif
64 : }
65 :
66 : static inline int read_cred_subscribers(const struct cred *cred)
67 : {
68 : #ifdef CONFIG_DEBUG_CREDENTIALS
69 : return atomic_read(&cred->subscribers);
70 : #else
71 : return 0;
72 : #endif
73 : }
74 :
75 : static inline void alter_cred_subscribers(const struct cred *_cred, int n)
76 : {
77 : #ifdef CONFIG_DEBUG_CREDENTIALS
78 : struct cred *cred = (struct cred *) _cred;
79 :
80 : atomic_add(n, &cred->subscribers);
81 : #endif
82 : }
83 :
84 : /*
85 : * The RCU callback to actually dispose of a set of credentials
86 : */
87 20096 : static void put_cred_rcu(struct rcu_head *rcu)
88 : {
89 20096 : struct cred *cred = container_of(rcu, struct cred, rcu);
90 :
91 : kdebug("put_cred_rcu(%p)", cred);
92 :
93 : #ifdef CONFIG_DEBUG_CREDENTIALS
94 : if (cred->magic != CRED_MAGIC_DEAD ||
95 : atomic_read(&cred->usage) != 0 ||
96 : read_cred_subscribers(cred) != 0)
97 : panic("CRED: put_cred_rcu() sees %p with"
98 : " mag %x, put %p, usage %d, subscr %d\n",
99 : cred, cred->magic, cred->put_addr,
100 : atomic_read(&cred->usage),
101 : read_cred_subscribers(cred));
102 : #else
103 20096 : if (atomic_read(&cred->usage) != 0)
104 0 : panic("CRED: put_cred_rcu() sees %p with usage %d\n",
105 : cred, atomic_read(&cred->usage));
106 : #endif
107 :
108 : security_cred_free(cred);
109 20096 : key_put(cred->session_keyring);
110 20096 : key_put(cred->process_keyring);
111 20096 : key_put(cred->thread_keyring);
112 20096 : key_put(cred->request_key_auth);
113 20096 : if (cred->group_info)
114 40192 : put_group_info(cred->group_info);
115 20096 : free_uid(cred->user);
116 : put_user_ns(cred->user_ns);
117 20096 : kmem_cache_free(cred_jar, cred);
118 20096 : }
119 :
120 : /**
121 : * __put_cred - Destroy a set of credentials
122 : * @cred: The record to release
123 : *
124 : * Destroy a set of credentials on which no references remain.
125 : */
126 20096 : void __put_cred(struct cred *cred)
127 : {
128 20096 : kdebug("__put_cred(%p{%d,%d})", cred,
129 : atomic_read(&cred->usage),
130 : read_cred_subscribers(cred));
131 :
132 20096 : BUG_ON(atomic_read(&cred->usage) != 0);
133 : #ifdef CONFIG_DEBUG_CREDENTIALS
134 : BUG_ON(read_cred_subscribers(cred) != 0);
135 : cred->magic = CRED_MAGIC_DEAD;
136 : cred->put_addr = __builtin_return_address(0);
137 : #endif
138 : BUG_ON(cred == current->cred);
139 : BUG_ON(cred == current->real_cred);
140 :
141 20096 : call_rcu(&cred->rcu, put_cred_rcu);
142 20096 : }
143 : EXPORT_SYMBOL(__put_cred);
144 :
145 : /*
146 : * Clean up a task's credentials when it exits
147 : */
148 2915 : void exit_creds(struct task_struct *tsk)
149 : {
150 : struct cred *cred;
151 :
152 2915 : kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
153 : atomic_read(&tsk->cred->usage),
154 : read_cred_subscribers(tsk->cred));
155 :
156 2915 : cred = (struct cred *) tsk->real_cred;
157 2915 : tsk->real_cred = NULL;
158 : validate_creds(cred);
159 : alter_cred_subscribers(cred, -1);
160 : put_cred(cred);
161 :
162 2915 : cred = (struct cred *) tsk->cred;
163 2915 : tsk->cred = NULL;
164 : validate_creds(cred);
165 : alter_cred_subscribers(cred, -1);
166 : put_cred(cred);
167 2915 : }
168 :
169 : /**
170 : * get_task_cred - Get another task's objective credentials
171 : * @task: The task to query
172 : *
173 : * Get the objective credentials of a task, pinning them so that they can't go
174 : * away. Accessing a task's credentials directly is not permitted.
175 : *
176 : * The caller must also make sure task doesn't get deleted, either by holding a
177 : * ref on task or by holding tasklist_lock to prevent it from being unlinked.
178 : */
179 214 : const struct cred *get_task_cred(struct task_struct *task)
180 : {
181 : const struct cred *cred;
182 :
183 : rcu_read_lock();
184 :
185 : do {
186 214 : cred = __task_cred((task));
187 : BUG_ON(!cred);
188 428 : } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage));
189 :
190 : rcu_read_unlock();
191 214 : return cred;
192 : }
193 :
194 : /*
195 : * Allocate blank credentials, such that the credentials can be filled in at a
196 : * later date without risk of ENOMEM.
197 : */
198 0 : struct cred *cred_alloc_blank(void)
199 : {
200 : struct cred *new;
201 :
202 0 : new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
203 0 : if (!new)
204 : return NULL;
205 :
206 0 : atomic_set(&new->usage, 1);
207 : #ifdef CONFIG_DEBUG_CREDENTIALS
208 : new->magic = CRED_MAGIC;
209 : #endif
210 :
211 : if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
212 : goto error;
213 :
214 0 : return new;
215 :
216 : error:
217 : abort_creds(new);
218 : return NULL;
219 : }
220 :
221 : /**
222 : * prepare_creds - Prepare a new set of credentials for modification
223 : *
224 : * Prepare a new set of task credentials for modification. A task's creds
225 : * shouldn't generally be modified directly, therefore this function is used to
226 : * prepare a new copy, which the caller then modifies and then commits by
227 : * calling commit_creds().
228 : *
229 : * Preparation involves making a copy of the objective creds for modification.
230 : *
231 : * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
232 : *
233 : * Call commit_creds() or abort_creds() to clean up.
234 : */
235 20214 : struct cred *prepare_creds(void)
236 : {
237 20214 : struct task_struct *task = current;
238 : const struct cred *old;
239 : struct cred *new;
240 :
241 : validate_process_creds();
242 :
243 20214 : new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
244 20214 : if (!new)
245 : return NULL;
246 :
247 : kdebug("prepare_creds() alloc %p", new);
248 :
249 20214 : old = task->cred;
250 20214 : memcpy(new, old, sizeof(struct cred));
251 :
252 20214 : atomic_set(&new->usage, 1);
253 : set_cred_subscribers(new, 0);
254 20214 : get_group_info(new->group_info);
255 20213 : get_uid(new->user);
256 : get_user_ns(new->user_ns);
257 :
258 : #ifdef CONFIG_KEYS
259 20214 : key_get(new->session_keyring);
260 20211 : key_get(new->process_keyring);
261 20211 : key_get(new->thread_keyring);
262 20211 : key_get(new->request_key_auth);
263 : #endif
264 :
265 : #ifdef CONFIG_SECURITY
266 : new->security = NULL;
267 : #endif
268 :
269 : if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
270 : goto error;
271 : validate_creds(new);
272 20211 : return new;
273 :
274 : error:
275 : abort_creds(new);
276 : return NULL;
277 : }
278 : EXPORT_SYMBOL(prepare_creds);
279 :
280 : /*
281 : * Prepare credentials for current to perform an execve()
282 : * - The caller must hold ->cred_guard_mutex
283 : */
284 2247 : struct cred *prepare_exec_creds(void)
285 : {
286 : struct cred *new;
287 :
288 2247 : new = prepare_creds();
289 2247 : if (!new)
290 : return new;
291 :
292 : #ifdef CONFIG_KEYS
293 : /* newly exec'd tasks don't get a thread keyring */
294 2247 : key_put(new->thread_keyring);
295 2247 : new->thread_keyring = NULL;
296 :
297 : /* inherit the session keyring; new process keyring */
298 2247 : key_put(new->process_keyring);
299 2247 : new->process_keyring = NULL;
300 : #endif
301 :
302 2247 : return new;
303 : }
304 :
305 : /*
306 : * Copy credentials for the new process created by fork()
307 : *
308 : * We share if we can, but under some circumstances we have to generate a new
309 : * set.
310 : *
311 : * The new process gets the current process's subjective credentials as its
312 : * objective and subjective credentials
313 : */
314 2993 : int copy_creds(struct task_struct *p, unsigned long clone_flags)
315 : {
316 : struct cred *new;
317 : int ret;
318 :
319 2993 : if (
320 : #ifdef CONFIG_KEYS
321 5986 : !p->cred->thread_keyring &&
322 : #endif
323 2993 : clone_flags & CLONE_THREAD
324 : ) {
325 6 : p->real_cred = get_cred(p->cred);
326 6 : get_cred(p->cred);
327 : alter_cred_subscribers(p->cred, 2);
328 6 : kdebug("share_creds(%p{%d,%d})",
329 : p->cred, atomic_read(&p->cred->usage),
330 : read_cred_subscribers(p->cred));
331 6 : atomic_inc(&p->cred->user->processes);
332 6 : return 0;
333 : }
334 :
335 2987 : new = prepare_creds();
336 2987 : if (!new)
337 : return -ENOMEM;
338 :
339 2987 : if (clone_flags & CLONE_NEWUSER) {
340 : ret = create_user_ns(new);
341 : if (ret < 0)
342 : goto error_put;
343 : }
344 :
345 : #ifdef CONFIG_KEYS
346 : /* new threads get their own thread keyrings if their parent already
347 : * had one */
348 2987 : if (new->thread_keyring) {
349 0 : key_put(new->thread_keyring);
350 0 : new->thread_keyring = NULL;
351 0 : if (clone_flags & CLONE_THREAD)
352 0 : install_thread_keyring_to_cred(new);
353 : }
354 :
355 : /* The process keyring is only shared between the threads in a process;
356 : * anything outside of those threads doesn't inherit.
357 : */
358 2987 : if (!(clone_flags & CLONE_THREAD)) {
359 2987 : key_put(new->process_keyring);
360 2987 : new->process_keyring = NULL;
361 : }
362 : #endif
363 :
364 2987 : atomic_inc(&new->user->processes);
365 2987 : p->cred = p->real_cred = get_cred(new);
366 : alter_cred_subscribers(new, 2);
367 : validate_creds(new);
368 2987 : return 0;
369 :
370 : error_put:
371 : put_cred(new);
372 : return ret;
373 : }
374 :
375 2969 : static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
376 : {
377 2969 : const struct user_namespace *set_ns = set->user_ns;
378 2969 : const struct user_namespace *subset_ns = subset->user_ns;
379 :
380 : /* If the two credentials are in the same user namespace see if
381 : * the capabilities of subset are a subset of set.
382 : */
383 2969 : if (set_ns == subset_ns)
384 2969 : return cap_issubset(subset->cap_permitted, set->cap_permitted);
385 :
386 : /* The credentials are in a different user namespaces
387 : * therefore one is a subset of the other only if a set is an
388 : * ancestor of subset and set->euid is owner of subset or one
389 : * of subsets ancestors.
390 : */
391 0 : for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
392 0 : if ((set_ns == subset_ns->parent) &&
393 : uid_eq(subset_ns->owner, set->euid))
394 : return true;
395 : }
396 :
397 : return false;
398 : }
399 :
400 : /**
401 : * commit_creds - Install new credentials upon the current task
402 : * @new: The credentials to be assigned
403 : *
404 : * Install a new set of credentials to the current task, using RCU to replace
405 : * the old set. Both the objective and the subjective credentials pointers are
406 : * updated. This function may not be called if the subjective credentials are
407 : * in an overridden state.
408 : *
409 : * This function eats the caller's reference to the new credentials.
410 : *
411 : * Always returns 0 thus allowing this function to be tail-called at the end
412 : * of, say, sys_setgid().
413 : */
414 3503 : int commit_creds(struct cred *new)
415 : {
416 3503 : struct task_struct *task = current;
417 3503 : const struct cred *old = task->real_cred;
418 :
419 3503 : kdebug("commit_creds(%p{%d,%d})", new,
420 : atomic_read(&new->usage),
421 : read_cred_subscribers(new));
422 :
423 : BUG_ON(task->cred != old);
424 : #ifdef CONFIG_DEBUG_CREDENTIALS
425 : BUG_ON(read_cred_subscribers(old) < 2);
426 : validate_creds(old);
427 : validate_creds(new);
428 : #endif
429 3503 : BUG_ON(atomic_read(&new->usage) < 1);
430 :
431 : get_cred(new); /* we will require a ref for the subj creds too */
432 :
433 : /* dumpability changes */
434 3503 : if (!uid_eq(old->euid, new->euid) ||
435 3005 : !gid_eq(old->egid, new->egid) ||
436 2987 : !uid_eq(old->fsuid, new->fsuid) ||
437 2969 : !gid_eq(old->fsgid, new->fsgid) ||
438 2969 : !cred_cap_issubset(old, new)) {
439 534 : if (task->mm)
440 534 : set_dumpable(task->mm, suid_dumpable);
441 534 : task->pdeath_signal = 0;
442 534 : smp_wmb();
443 : }
444 :
445 : /* alter the thread keyring */
446 3503 : if (!uid_eq(new->fsuid, old->fsuid))
447 207 : key_fsuid_changed(task);
448 3503 : if (!gid_eq(new->fsgid, old->fsgid))
449 327 : key_fsgid_changed(task);
450 :
451 : /* do it
452 : * RLIMIT_NPROC limits on user->processes have already been checked
453 : * in set_user().
454 : */
455 : alter_cred_subscribers(new, 2);
456 3503 : if (new->user != old->user)
457 117 : atomic_inc(&new->user->processes);
458 3503 : rcu_assign_pointer(task->real_cred, new);
459 3503 : rcu_assign_pointer(task->cred, new);
460 3503 : if (new->user != old->user)
461 117 : atomic_dec(&old->user->processes);
462 : alter_cred_subscribers(old, -2);
463 :
464 : /* send notifications */
465 : if (!uid_eq(new->uid, old->uid) ||
466 : !uid_eq(new->euid, old->euid) ||
467 : !uid_eq(new->suid, old->suid) ||
468 : !uid_eq(new->fsuid, old->fsuid))
469 : proc_id_connector(task, PROC_EVENT_UID);
470 :
471 : if (!gid_eq(new->gid, old->gid) ||
472 : !gid_eq(new->egid, old->egid) ||
473 : !gid_eq(new->sgid, old->sgid) ||
474 : !gid_eq(new->fsgid, old->fsgid))
475 : proc_id_connector(task, PROC_EVENT_GID);
476 :
477 : /* release the old obj and subj refs both */
478 : put_cred(old);
479 : put_cred(old);
480 3503 : return 0;
481 : }
482 : EXPORT_SYMBOL(commit_creds);
483 :
484 : /**
485 : * abort_creds - Discard a set of credentials and unlock the current task
486 : * @new: The credentials that were going to be applied
487 : *
488 : * Discard a set of credentials that were under construction and unlock the
489 : * current task.
490 : */
491 192 : void abort_creds(struct cred *new)
492 : {
493 192 : kdebug("abort_creds(%p{%d,%d})", new,
494 : atomic_read(&new->usage),
495 : read_cred_subscribers(new));
496 :
497 : #ifdef CONFIG_DEBUG_CREDENTIALS
498 : BUG_ON(read_cred_subscribers(new) != 0);
499 : #endif
500 192 : BUG_ON(atomic_read(&new->usage) < 1);
501 : put_cred(new);
502 192 : }
503 : EXPORT_SYMBOL(abort_creds);
504 :
505 : /**
506 : * override_creds - Override the current process's subjective credentials
507 : * @new: The credentials to be assigned
508 : *
509 : * Install a set of temporary override subjective credentials on the current
510 : * process, returning the old set for later reversion.
511 : */
512 13542 : const struct cred *override_creds(const struct cred *new)
513 : {
514 13542 : const struct cred *old = current->cred;
515 :
516 13542 : kdebug("override_creds(%p{%d,%d})", new,
517 : atomic_read(&new->usage),
518 : read_cred_subscribers(new));
519 :
520 : validate_creds(old);
521 : validate_creds(new);
522 : get_cred(new);
523 : alter_cred_subscribers(new, 1);
524 27108 : rcu_assign_pointer(current->cred, new);
525 : alter_cred_subscribers(old, -1);
526 :
527 13554 : kdebug("override_creds() = %p{%d,%d}", old,
528 : atomic_read(&old->usage),
529 : read_cred_subscribers(old));
530 13554 : return old;
531 : }
532 : EXPORT_SYMBOL(override_creds);
533 :
534 : /**
535 : * revert_creds - Revert a temporary subjective credentials override
536 : * @old: The credentials to be restored
537 : *
538 : * Revert a temporary set of override subjective credentials to an old set,
539 : * discarding the override set.
540 : */
541 13554 : void revert_creds(const struct cred *old)
542 : {
543 13554 : const struct cred *override = current->cred;
544 :
545 13554 : kdebug("revert_creds(%p{%d,%d})", old,
546 : atomic_read(&old->usage),
547 : read_cred_subscribers(old));
548 :
549 : validate_creds(old);
550 : validate_creds(override);
551 : alter_cred_subscribers(old, 1);
552 27108 : rcu_assign_pointer(current->cred, old);
553 : alter_cred_subscribers(override, -1);
554 : put_cred(override);
555 13554 : }
556 : EXPORT_SYMBOL(revert_creds);
557 :
558 : /*
559 : * initialise the credentials stuff
560 : */
561 1 : void __init cred_init(void)
562 : {
563 : /* allocate a slab in which we can store credentials */
564 1 : cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred),
565 : 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
566 1 : }
567 :
568 : /**
569 : * prepare_kernel_cred - Prepare a set of credentials for a kernel service
570 : * @daemon: A userspace daemon to be used as a reference
571 : *
572 : * Prepare a set of credentials for a kernel service. This can then be used to
573 : * override a task's own credentials so that work can be done on behalf of that
574 : * task that requires a different subjective context.
575 : *
576 : * @daemon is used to provide a base for the security record, but can be NULL.
577 : * If @daemon is supplied, then the security data will be derived from that;
578 : * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
579 : *
580 : * The caller may change these controls afterwards if desired.
581 : *
582 : * Returns the new credentials or NULL if out of memory.
583 : *
584 : * Does not take, and does not return holding current->cred_replace_mutex.
585 : */
586 24 : struct cred *prepare_kernel_cred(struct task_struct *daemon)
587 : {
588 : const struct cred *old;
589 : struct cred *new;
590 :
591 24 : new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
592 24 : if (!new)
593 : return NULL;
594 :
595 : kdebug("prepare_kernel_cred() alloc %p", new);
596 :
597 24 : if (daemon)
598 22 : old = get_task_cred(daemon);
599 : else
600 : old = get_cred(&init_cred);
601 :
602 : validate_creds(old);
603 :
604 24 : *new = *old;
605 24 : atomic_set(&new->usage, 1);
606 : set_cred_subscribers(new, 0);
607 24 : get_uid(new->user);
608 : get_user_ns(new->user_ns);
609 24 : get_group_info(new->group_info);
610 :
611 : #ifdef CONFIG_KEYS
612 24 : new->session_keyring = NULL;
613 24 : new->process_keyring = NULL;
614 24 : new->thread_keyring = NULL;
615 24 : new->request_key_auth = NULL;
616 24 : new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
617 : #endif
618 :
619 : #ifdef CONFIG_SECURITY
620 : new->security = NULL;
621 : #endif
622 : if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
623 : goto error;
624 :
625 : put_cred(old);
626 : validate_creds(new);
627 24 : return new;
628 :
629 : error:
630 : put_cred(new);
631 : put_cred(old);
632 : return NULL;
633 : }
634 : EXPORT_SYMBOL(prepare_kernel_cred);
635 :
636 : /**
637 : * set_security_override - Set the security ID in a set of credentials
638 : * @new: The credentials to alter
639 : * @secid: The LSM security ID to set
640 : *
641 : * Set the LSM security ID in a set of credentials so that the subjective
642 : * security is overridden when an alternative set of credentials is used.
643 : */
644 0 : int set_security_override(struct cred *new, u32 secid)
645 : {
646 0 : return security_kernel_act_as(new, secid);
647 : }
648 : EXPORT_SYMBOL(set_security_override);
649 :
650 : /**
651 : * set_security_override_from_ctx - Set the security ID in a set of credentials
652 : * @new: The credentials to alter
653 : * @secctx: The LSM security context to generate the security ID from.
654 : *
655 : * Set the LSM security ID in a set of credentials so that the subjective
656 : * security is overridden when an alternative set of credentials is used. The
657 : * security ID is specified in string form as a security context to be
658 : * interpreted by the LSM.
659 : */
660 0 : int set_security_override_from_ctx(struct cred *new, const char *secctx)
661 : {
662 : u32 secid;
663 : int ret;
664 :
665 : ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
666 : if (ret < 0)
667 : return ret;
668 :
669 : return set_security_override(new, secid);
670 : }
671 : EXPORT_SYMBOL(set_security_override_from_ctx);
672 :
673 : /**
674 : * set_create_files_as - Set the LSM file create context in a set of credentials
675 : * @new: The credentials to alter
676 : * @inode: The inode to take the context from
677 : *
678 : * Change the LSM file creation context in a set of credentials to be the same
679 : * as the object context of the specified inode, so that the new inodes have
680 : * the same MAC context as that inode.
681 : */
682 0 : int set_create_files_as(struct cred *new, struct inode *inode)
683 : {
684 0 : new->fsuid = inode->i_uid;
685 0 : new->fsgid = inode->i_gid;
686 0 : return security_kernel_create_files_as(new, inode);
687 : }
688 : EXPORT_SYMBOL(set_create_files_as);
689 :
690 : #ifdef CONFIG_DEBUG_CREDENTIALS
691 :
692 : bool creds_are_invalid(const struct cred *cred)
693 : {
694 : if (cred->magic != CRED_MAGIC)
695 : return true;
696 : #ifdef CONFIG_SECURITY_SELINUX
697 : /*
698 : * cred->security == NULL if security_cred_alloc_blank() or
699 : * security_prepare_creds() returned an error.
700 : */
701 : if (selinux_is_enabled() && cred->security) {
702 : if ((unsigned long) cred->security < PAGE_SIZE)
703 : return true;
704 : if ((*(u32 *)cred->security & 0xffffff00) ==
705 : (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
706 : return true;
707 : }
708 : #endif
709 : return false;
710 : }
711 : EXPORT_SYMBOL(creds_are_invalid);
712 :
713 : /*
714 : * dump invalid credentials
715 : */
716 : static void dump_invalid_creds(const struct cred *cred, const char *label,
717 : const struct task_struct *tsk)
718 : {
719 : printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
720 : label, cred,
721 : cred == &init_cred ? "[init]" : "",
722 : cred == tsk->real_cred ? "[real]" : "",
723 : cred == tsk->cred ? "[eff]" : "");
724 : printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
725 : cred->magic, cred->put_addr);
726 : printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
727 : atomic_read(&cred->usage),
728 : read_cred_subscribers(cred));
729 : printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
730 : from_kuid_munged(&init_user_ns, cred->uid),
731 : from_kuid_munged(&init_user_ns, cred->euid),
732 : from_kuid_munged(&init_user_ns, cred->suid),
733 : from_kuid_munged(&init_user_ns, cred->fsuid));
734 : printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
735 : from_kgid_munged(&init_user_ns, cred->gid),
736 : from_kgid_munged(&init_user_ns, cred->egid),
737 : from_kgid_munged(&init_user_ns, cred->sgid),
738 : from_kgid_munged(&init_user_ns, cred->fsgid));
739 : #ifdef CONFIG_SECURITY
740 : printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
741 : if ((unsigned long) cred->security >= PAGE_SIZE &&
742 : (((unsigned long) cred->security & 0xffffff00) !=
743 : (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
744 : printk(KERN_ERR "CRED: ->security {%x, %x}\n",
745 : ((u32*)cred->security)[0],
746 : ((u32*)cred->security)[1]);
747 : #endif
748 : }
749 :
750 : /*
751 : * report use of invalid credentials
752 : */
753 : void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
754 : {
755 : printk(KERN_ERR "CRED: Invalid credentials\n");
756 : printk(KERN_ERR "CRED: At %s:%u\n", file, line);
757 : dump_invalid_creds(cred, "Specified", current);
758 : BUG();
759 : }
760 : EXPORT_SYMBOL(__invalid_creds);
761 :
762 : /*
763 : * check the credentials on a process
764 : */
765 : void __validate_process_creds(struct task_struct *tsk,
766 : const char *file, unsigned line)
767 : {
768 : if (tsk->cred == tsk->real_cred) {
769 : if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
770 : creds_are_invalid(tsk->cred)))
771 : goto invalid_creds;
772 : } else {
773 : if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
774 : read_cred_subscribers(tsk->cred) < 1 ||
775 : creds_are_invalid(tsk->real_cred) ||
776 : creds_are_invalid(tsk->cred)))
777 : goto invalid_creds;
778 : }
779 : return;
780 :
781 : invalid_creds:
782 : printk(KERN_ERR "CRED: Invalid process credentials\n");
783 : printk(KERN_ERR "CRED: At %s:%u\n", file, line);
784 :
785 : dump_invalid_creds(tsk->real_cred, "Real", tsk);
786 : if (tsk->cred != tsk->real_cred)
787 : dump_invalid_creds(tsk->cred, "Effective", tsk);
788 : else
789 : printk(KERN_ERR "CRED: Effective creds == Real creds\n");
790 : BUG();
791 : }
792 : EXPORT_SYMBOL(__validate_process_creds);
793 :
794 : /*
795 : * check creds for do_exit()
796 : */
797 : void validate_creds_for_do_exit(struct task_struct *tsk)
798 : {
799 : kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
800 : tsk->real_cred, tsk->cred,
801 : atomic_read(&tsk->cred->usage),
802 : read_cred_subscribers(tsk->cred));
803 :
804 : __validate_process_creds(tsk, __FILE__, __LINE__);
805 : }
806 :
807 : #endif /* CONFIG_DEBUG_CREDENTIALS */
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