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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 : 0 : static void put_cred_rcu(struct rcu_head *rcu)
88 : : {
89 : 1746607 : 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 [ - + ]: 1746607 : 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 : 1746607 : security_cred_free(cred);
109 : 1748181 : key_put(cred->session_keyring);
110 : 1748257 : key_put(cred->process_keyring);
111 : 1748305 : key_put(cred->thread_keyring);
112 : 1748286 : key_put(cred->request_key_auth);
113 [ + ]: 1748233 : if (cred->group_info)
114 [ + + ]: 1748223 : put_group_info(cred->group_info);
115 : 1748214 : free_uid(cred->user);
116 : : put_user_ns(cred->user_ns);
117 : 1748417 : kmem_cache_free(cred_jar, cred);
118 : 1748307 : }
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 : 0 : void __put_cred(struct cred *cred)
127 : : {
128 : 1748285 : kdebug("__put_cred(%p{%d,%d})", cred,
129 : : atomic_read(&cred->usage),
130 : : read_cred_subscribers(cred));
131 : :
132 [ - + ]: 1748285 : 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 [ - + ]: 1748285 : BUG_ON(cred == current->cred);
139 [ - + ]: 1748285 : BUG_ON(cred == current->real_cred);
140 : :
141 : 1748285 : call_rcu(&cred->rcu, put_cred_rcu);
142 : 1748332 : }
143 : : EXPORT_SYMBOL(__put_cred);
144 : :
145 : : /*
146 : : * Clean up a task's credentials when it exits
147 : : */
148 : 0 : void exit_creds(struct task_struct *tsk)
149 : : {
150 : : struct cred *cred;
151 : :
152 : 1151621 : 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 : 1151621 : cred = (struct cred *) tsk->real_cred;
157 : 1151621 : tsk->real_cred = NULL;
158 : : validate_creds(cred);
159 : : alter_cred_subscribers(cred, -1);
160 : : put_cred(cred);
161 : :
162 : 1151662 : cred = (struct cred *) tsk->cred;
163 : 1151662 : tsk->cred = NULL;
164 : : validate_creds(cred);
165 : : alter_cred_subscribers(cred, -1);
166 : : put_cred(cred);
167 : 1151780 : }
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 : 0 : 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 : 13249 : cred = __task_cred((task));
187 [ - + ]: 13249 : BUG_ON(!cred);
188 [ # # ]: 13249 : } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage));
189 : :
190 : : rcu_read_unlock();
191 : 13249 : 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 [ # # ]: 0 : if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
212 : : goto error;
213 : :
214 : : return new;
215 : :
216 : : error:
217 : 0 : abort_creds(new);
218 : 0 : 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 : 0 : struct cred *prepare_creds(void)
236 : : {
237 : 1748318 : struct task_struct *task = current;
238 : : const struct cred *old;
239 : : struct cred *new;
240 : :
241 : : validate_process_creds();
242 : :
243 : 1748318 : new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
244 [ + ]: 1748312 : if (!new)
245 : : return NULL;
246 : :
247 : : kdebug("prepare_creds() alloc %p", new);
248 : :
249 : 1748318 : old = task->cred;
250 : 1748318 : memcpy(new, old, sizeof(struct cred));
251 : :
252 : 1748318 : atomic_set(&new->usage, 1);
253 : : set_cred_subscribers(new, 0);
254 : 1748318 : get_group_info(new->group_info);
255 : 1748325 : get_uid(new->user);
256 : : get_user_ns(new->user_ns);
257 : :
258 : : #ifdef CONFIG_KEYS
259 : 1748323 : key_get(new->session_keyring);
260 : 1748339 : key_get(new->process_keyring);
261 : 1748339 : key_get(new->thread_keyring);
262 : 1748339 : key_get(new->request_key_auth);
263 : : #endif
264 : :
265 : : #ifdef CONFIG_SECURITY
266 : 1748339 : new->security = NULL;
267 : : #endif
268 : :
269 [ - + ]: 1748339 : if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
270 : : goto error;
271 : : validate_creds(new);
272 : : return new;
273 : :
274 : : error:
275 : 0 : abort_creds(new);
276 : 0 : 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 : 0 : struct cred *prepare_exec_creds(void)
285 : : {
286 : : struct cred *new;
287 : :
288 : 98474 : new = prepare_creds();
289 [ + ]: 98467 : if (!new)
290 : : return new;
291 : :
292 : : #ifdef CONFIG_KEYS
293 : : /* newly exec'd tasks don't get a thread keyring */
294 : 98469 : key_put(new->thread_keyring);
295 : 98473 : new->thread_keyring = NULL;
296 : :
297 : : /* inherit the session keyring; new process keyring */
298 : 98473 : key_put(new->process_keyring);
299 : 98474 : new->process_keyring = NULL;
300 : : #endif
301 : :
302 : 98474 : 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 : 0 : int copy_creds(struct task_struct *p, unsigned long clone_flags)
315 : : {
316 : : struct cred *new;
317 : : int ret;
318 : :
319 [ + + ]: 1151928 : if (
320 : : #ifdef CONFIG_KEYS
321 [ + + ]: 1151914 : !p->cred->thread_keyring &&
322 : : #endif
323 : 1151914 : clone_flags & CLONE_THREAD
324 : : ) {
325 : 2316 : p->real_cred = get_cred(p->cred);
326 : 2316 : get_cred(p->cred);
327 : : alter_cred_subscribers(p->cred, 2);
328 : 2316 : kdebug("share_creds(%p{%d,%d})",
329 : : p->cred, atomic_read(&p->cred->usage),
330 : : read_cred_subscribers(p->cred));
331 : 2316 : atomic_inc(&p->cred->user->processes);
332 : 2316 : return 0;
333 : : }
334 : :
335 : 1149612 : new = prepare_creds();
336 [ + ]: 1149607 : if (!new)
337 : : return -ENOMEM;
338 : :
339 [ + - ]: 1149608 : 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 [ - + ]: 1149608 : 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 [ + - ]: 1149613 : if (!(clone_flags & CLONE_THREAD)) {
359 : 1149613 : key_put(new->process_keyring);
360 : 1149593 : new->process_keyring = NULL;
361 : : }
362 : : #endif
363 : :
364 : 1149593 : atomic_inc(&new->user->processes);
365 : 1149598 : p->cred = p->real_cred = get_cred(new);
366 : : alter_cred_subscribers(new, 2);
367 : : validate_creds(new);
368 : 1149598 : return 0;
369 : :
370 : : error_put:
371 : : put_cred(new);
372 : : return ret;
373 : : }
374 : :
375 : 0 : static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
376 : : {
377 : 69440 : const struct user_namespace *set_ns = set->user_ns;
378 : 69440 : 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 [ - + ]: 69440 : if (set_ns == subset_ns)
384 : 69440 : 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 : 0 : 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 : 0 : int commit_creds(struct cred *new)
415 : : {
416 : 74561 : struct task_struct *task = current;
417 : 74561 : const struct cred *old = task->real_cred;
418 : :
419 : 74561 : kdebug("commit_creds(%p{%d,%d})", new,
420 : : atomic_read(&new->usage),
421 : : read_cred_subscribers(new));
422 : :
423 [ - + ]: 74561 : 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 [ - + ]: 74561 : 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 [ + + ][ + + ]: 74561 : if (!uid_eq(old->euid, new->euid) ||
435 [ + + ]: 69451 : !gid_eq(old->egid, new->egid) ||
436 [ + + ]: 69443 : !uid_eq(old->fsuid, new->fsuid) ||
437 [ - + ]: 69441 : !gid_eq(old->fsgid, new->fsgid) ||
438 : 69441 : !cred_cap_issubset(old, new)) {
439 [ + ]: 5120 : if (task->mm)
440 : 5120 : set_dumpable(task->mm, suid_dumpable);
441 : 0 : task->pdeath_signal = 0;
442 : 0 : smp_wmb();
443 : : }
444 : :
445 : : /* alter the thread keyring */
446 [ + + ]: 74561 : if (!uid_eq(new->fsuid, old->fsuid))
447 : 3750 : key_fsuid_changed(task);
448 [ + + ]: 74561 : if (!gid_eq(new->fsgid, old->fsgid))
449 : 1370 : 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 [ + + ]: 74561 : if (new->user != old->user)
457 : 331 : atomic_inc(&new->user->processes);
458 : 74561 : rcu_assign_pointer(task->real_cred, new);
459 : 74560 : rcu_assign_pointer(task->cred, new);
460 [ + + ]: 74560 : if (new->user != old->user)
461 : 331 : atomic_dec(&old->user->processes);
462 : : alter_cred_subscribers(old, -2);
463 : :
464 : : /* send notifications */
465 [ + + ][ + + ]: 74560 : if (!uid_eq(new->uid, old->uid) ||
466 [ + + ]: 70798 : !uid_eq(new->euid, old->euid) ||
467 [ + + ]: 70791 : !uid_eq(new->suid, old->suid) ||
468 : 70791 : !uid_eq(new->fsuid, old->fsuid))
469 : 3777 : proc_id_connector(task, PROC_EVENT_UID);
470 : :
471 [ + + ][ + + ]: 74561 : if (!gid_eq(new->gid, old->gid) ||
472 [ + + ]: 73183 : !gid_eq(new->egid, old->egid) ||
473 [ + + ]: 73179 : !gid_eq(new->sgid, old->sgid) ||
474 : 73179 : !gid_eq(new->fsgid, old->fsgid))
475 : 1384 : 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 : 74561 : 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 : 0 : void abort_creds(struct cred *new)
492 : : {
493 : 58080 : 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 [ - + ]: 58080 : BUG_ON(atomic_read(&new->usage) < 1);
501 : : put_cred(new);
502 : 0 : }
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 : 0 : const struct cred *override_creds(const struct cred *new)
513 : : {
514 : 466220 : const struct cred *old = current->cred;
515 : :
516 : 466220 : 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 : 466215 : rcu_assign_pointer(current->cred, new);
525 : : alter_cred_subscribers(old, -1);
526 : :
527 : 466213 : kdebug("override_creds() = %p{%d,%d}", old,
528 : : atomic_read(&old->usage),
529 : : read_cred_subscribers(old));
530 : 466213 : 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 : 0 : void revert_creds(const struct cred *old)
542 : : {
543 : 466223 : const struct cred *override = current->cred;
544 : :
545 : 466223 : 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 : 466223 : rcu_assign_pointer(current->cred, old);
553 : : alter_cred_subscribers(override, -1);
554 : : put_cred(override);
555 : 0 : }
556 : : EXPORT_SYMBOL(revert_creds);
557 : :
558 : : /*
559 : : * initialise the credentials stuff
560 : : */
561 : 0 : void __init cred_init(void)
562 : : {
563 : : /* allocate a slab in which we can store credentials */
564 : 0 : cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred),
565 : : 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
566 : 0 : }
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 : 0 : struct cred *prepare_kernel_cred(struct task_struct *daemon)
587 : : {
588 : : const struct cred *old;
589 : : struct cred *new;
590 : :
591 : 136 : new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
592 [ + - ]: 136 : if (!new)
593 : : return NULL;
594 : :
595 : : kdebug("prepare_kernel_cred() alloc %p", new);
596 : :
597 [ + - ]: 136 : if (daemon)
598 : 136 : old = get_task_cred(daemon);
599 : : else
600 : : old = get_cred(&init_cred);
601 : :
602 : : validate_creds(old);
603 : :
604 : 136 : *new = *old;
605 : 136 : atomic_set(&new->usage, 1);
606 : : set_cred_subscribers(new, 0);
607 : 136 : get_uid(new->user);
608 : : get_user_ns(new->user_ns);
609 : 136 : get_group_info(new->group_info);
610 : :
611 : : #ifdef CONFIG_KEYS
612 : 136 : new->session_keyring = NULL;
613 : 136 : new->process_keyring = NULL;
614 : 136 : new->thread_keyring = NULL;
615 : 136 : new->request_key_auth = NULL;
616 : 136 : new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
617 : : #endif
618 : :
619 : : #ifdef CONFIG_SECURITY
620 : 136 : new->security = NULL;
621 : : #endif
622 [ + - ]: 136 : if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
623 : : goto error;
624 : :
625 : : put_cred(old);
626 : : validate_creds(new);
627 : 136 : 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 : 0 : ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
666 [ # # ]: 0 : if (ret < 0)
667 : : return ret;
668 : :
669 : 0 : 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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