Commit | Line | Data |
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d410fa4e | 1 | /* Task credentials management - see Documentation/security/credentials.txt |
f1752eec DH |
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 | */ | |
9984de1a | 11 | #include <linux/export.h> |
f1752eec | 12 | #include <linux/cred.h> |
5a0e3ad6 | 13 | #include <linux/slab.h> |
f1752eec DH |
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> | |
40401530 | 19 | #include <linux/binfmts.h> |
d84f4f99 | 20 | #include <linux/cn_proc.h> |
d84f4f99 | 21 | |
e0e81739 DH |
22 | #if 0 |
23 | #define kdebug(FMT, ...) \ | |
24 | printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__) | |
25 | #else | |
e0e81739 DH |
26 | #define kdebug(FMT, ...) \ |
27 | no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__) | |
28 | #endif | |
29 | ||
d84f4f99 | 30 | static struct kmem_cache *cred_jar; |
f1752eec | 31 | |
bb952bb9 DH |
32 | /* |
33 | * The common credentials for the initial task's thread group | |
34 | */ | |
35 | #ifdef CONFIG_KEYS | |
36 | static struct thread_group_cred init_tgcred = { | |
37 | .usage = ATOMIC_INIT(2), | |
38 | .tgid = 0, | |
10389a15 | 39 | .lock = __SPIN_LOCK_UNLOCKED(init_cred.tgcred.lock), |
bb952bb9 DH |
40 | }; |
41 | #endif | |
42 | ||
f1752eec DH |
43 | /* |
44 | * The initial credentials for the initial task | |
45 | */ | |
46 | struct cred init_cred = { | |
3b11a1de | 47 | .usage = ATOMIC_INIT(4), |
e0e81739 DH |
48 | #ifdef CONFIG_DEBUG_CREDENTIALS |
49 | .subscribers = ATOMIC_INIT(2), | |
50 | .magic = CRED_MAGIC, | |
51 | #endif | |
f1752eec | 52 | .securebits = SECUREBITS_DEFAULT, |
a3232d2f | 53 | .cap_inheritable = CAP_EMPTY_SET, |
f1752eec | 54 | .cap_permitted = CAP_FULL_SET, |
a3232d2f EP |
55 | .cap_effective = CAP_FULL_SET, |
56 | .cap_bset = CAP_FULL_SET, | |
f1752eec | 57 | .user = INIT_USER, |
47a150ed | 58 | .user_ns = &init_user_ns, |
f1752eec | 59 | .group_info = &init_groups, |
bb952bb9 DH |
60 | #ifdef CONFIG_KEYS |
61 | .tgcred = &init_tgcred, | |
62 | #endif | |
f1752eec DH |
63 | }; |
64 | ||
e0e81739 DH |
65 | static inline void set_cred_subscribers(struct cred *cred, int n) |
66 | { | |
67 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
68 | atomic_set(&cred->subscribers, n); | |
69 | #endif | |
70 | } | |
71 | ||
72 | static inline int read_cred_subscribers(const struct cred *cred) | |
73 | { | |
74 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
75 | return atomic_read(&cred->subscribers); | |
76 | #else | |
77 | return 0; | |
78 | #endif | |
79 | } | |
80 | ||
81 | static inline void alter_cred_subscribers(const struct cred *_cred, int n) | |
82 | { | |
83 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
84 | struct cred *cred = (struct cred *) _cred; | |
85 | ||
86 | atomic_add(n, &cred->subscribers); | |
87 | #endif | |
88 | } | |
89 | ||
bb952bb9 DH |
90 | /* |
91 | * Dispose of the shared task group credentials | |
92 | */ | |
93 | #ifdef CONFIG_KEYS | |
94 | static void release_tgcred_rcu(struct rcu_head *rcu) | |
95 | { | |
96 | struct thread_group_cred *tgcred = | |
97 | container_of(rcu, struct thread_group_cred, rcu); | |
98 | ||
99 | BUG_ON(atomic_read(&tgcred->usage) != 0); | |
100 | ||
101 | key_put(tgcred->session_keyring); | |
102 | key_put(tgcred->process_keyring); | |
103 | kfree(tgcred); | |
104 | } | |
105 | #endif | |
106 | ||
107 | /* | |
108 | * Release a set of thread group credentials. | |
109 | */ | |
a6f76f23 | 110 | static void release_tgcred(struct cred *cred) |
bb952bb9 DH |
111 | { |
112 | #ifdef CONFIG_KEYS | |
113 | struct thread_group_cred *tgcred = cred->tgcred; | |
114 | ||
115 | if (atomic_dec_and_test(&tgcred->usage)) | |
116 | call_rcu(&tgcred->rcu, release_tgcred_rcu); | |
117 | #endif | |
118 | } | |
119 | ||
f1752eec DH |
120 | /* |
121 | * The RCU callback to actually dispose of a set of credentials | |
122 | */ | |
123 | static void put_cred_rcu(struct rcu_head *rcu) | |
124 | { | |
125 | struct cred *cred = container_of(rcu, struct cred, rcu); | |
126 | ||
e0e81739 DH |
127 | kdebug("put_cred_rcu(%p)", cred); |
128 | ||
129 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
130 | if (cred->magic != CRED_MAGIC_DEAD || | |
131 | atomic_read(&cred->usage) != 0 || | |
132 | read_cred_subscribers(cred) != 0) | |
133 | panic("CRED: put_cred_rcu() sees %p with" | |
134 | " mag %x, put %p, usage %d, subscr %d\n", | |
135 | cred, cred->magic, cred->put_addr, | |
136 | atomic_read(&cred->usage), | |
137 | read_cred_subscribers(cred)); | |
138 | #else | |
d84f4f99 DH |
139 | if (atomic_read(&cred->usage) != 0) |
140 | panic("CRED: put_cred_rcu() sees %p with usage %d\n", | |
141 | cred, atomic_read(&cred->usage)); | |
e0e81739 | 142 | #endif |
f1752eec | 143 | |
d84f4f99 | 144 | security_cred_free(cred); |
f1752eec DH |
145 | key_put(cred->thread_keyring); |
146 | key_put(cred->request_key_auth); | |
bb952bb9 | 147 | release_tgcred(cred); |
4a5d6ba1 DH |
148 | if (cred->group_info) |
149 | put_group_info(cred->group_info); | |
f1752eec | 150 | free_uid(cred->user); |
d84f4f99 | 151 | kmem_cache_free(cred_jar, cred); |
f1752eec DH |
152 | } |
153 | ||
154 | /** | |
155 | * __put_cred - Destroy a set of credentials | |
d84f4f99 | 156 | * @cred: The record to release |
f1752eec DH |
157 | * |
158 | * Destroy a set of credentials on which no references remain. | |
159 | */ | |
160 | void __put_cred(struct cred *cred) | |
161 | { | |
e0e81739 DH |
162 | kdebug("__put_cred(%p{%d,%d})", cred, |
163 | atomic_read(&cred->usage), | |
164 | read_cred_subscribers(cred)); | |
165 | ||
d84f4f99 | 166 | BUG_ON(atomic_read(&cred->usage) != 0); |
e0e81739 DH |
167 | #ifdef CONFIG_DEBUG_CREDENTIALS |
168 | BUG_ON(read_cred_subscribers(cred) != 0); | |
169 | cred->magic = CRED_MAGIC_DEAD; | |
170 | cred->put_addr = __builtin_return_address(0); | |
171 | #endif | |
172 | BUG_ON(cred == current->cred); | |
173 | BUG_ON(cred == current->real_cred); | |
d84f4f99 | 174 | |
f1752eec DH |
175 | call_rcu(&cred->rcu, put_cred_rcu); |
176 | } | |
177 | EXPORT_SYMBOL(__put_cred); | |
178 | ||
e0e81739 DH |
179 | /* |
180 | * Clean up a task's credentials when it exits | |
181 | */ | |
182 | void exit_creds(struct task_struct *tsk) | |
183 | { | |
184 | struct cred *cred; | |
185 | ||
186 | kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred, | |
187 | atomic_read(&tsk->cred->usage), | |
188 | read_cred_subscribers(tsk->cred)); | |
189 | ||
190 | cred = (struct cred *) tsk->real_cred; | |
191 | tsk->real_cred = NULL; | |
192 | validate_creds(cred); | |
193 | alter_cred_subscribers(cred, -1); | |
194 | put_cred(cred); | |
195 | ||
196 | cred = (struct cred *) tsk->cred; | |
197 | tsk->cred = NULL; | |
198 | validate_creds(cred); | |
199 | alter_cred_subscribers(cred, -1); | |
200 | put_cred(cred); | |
ee18d64c DH |
201 | |
202 | cred = (struct cred *) tsk->replacement_session_keyring; | |
203 | if (cred) { | |
204 | tsk->replacement_session_keyring = NULL; | |
205 | validate_creds(cred); | |
206 | put_cred(cred); | |
207 | } | |
208 | } | |
209 | ||
de09a977 DH |
210 | /** |
211 | * get_task_cred - Get another task's objective credentials | |
212 | * @task: The task to query | |
213 | * | |
214 | * Get the objective credentials of a task, pinning them so that they can't go | |
215 | * away. Accessing a task's credentials directly is not permitted. | |
216 | * | |
217 | * The caller must also make sure task doesn't get deleted, either by holding a | |
218 | * ref on task or by holding tasklist_lock to prevent it from being unlinked. | |
219 | */ | |
220 | const struct cred *get_task_cred(struct task_struct *task) | |
221 | { | |
222 | const struct cred *cred; | |
223 | ||
224 | rcu_read_lock(); | |
225 | ||
226 | do { | |
227 | cred = __task_cred((task)); | |
228 | BUG_ON(!cred); | |
229 | } while (!atomic_inc_not_zero(&((struct cred *)cred)->usage)); | |
230 | ||
231 | rcu_read_unlock(); | |
232 | return cred; | |
233 | } | |
234 | ||
ee18d64c DH |
235 | /* |
236 | * Allocate blank credentials, such that the credentials can be filled in at a | |
237 | * later date without risk of ENOMEM. | |
238 | */ | |
239 | struct cred *cred_alloc_blank(void) | |
240 | { | |
241 | struct cred *new; | |
242 | ||
243 | new = kmem_cache_zalloc(cred_jar, GFP_KERNEL); | |
244 | if (!new) | |
245 | return NULL; | |
246 | ||
247 | #ifdef CONFIG_KEYS | |
248 | new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL); | |
249 | if (!new->tgcred) { | |
b8a1d37c | 250 | kmem_cache_free(cred_jar, new); |
ee18d64c DH |
251 | return NULL; |
252 | } | |
253 | atomic_set(&new->tgcred->usage, 1); | |
254 | #endif | |
255 | ||
256 | atomic_set(&new->usage, 1); | |
2edeaa34 TH |
257 | #ifdef CONFIG_DEBUG_CREDENTIALS |
258 | new->magic = CRED_MAGIC; | |
259 | #endif | |
ee18d64c DH |
260 | |
261 | if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) | |
262 | goto error; | |
263 | ||
ee18d64c DH |
264 | return new; |
265 | ||
266 | error: | |
267 | abort_creds(new); | |
268 | return NULL; | |
e0e81739 DH |
269 | } |
270 | ||
d84f4f99 DH |
271 | /** |
272 | * prepare_creds - Prepare a new set of credentials for modification | |
273 | * | |
274 | * Prepare a new set of task credentials for modification. A task's creds | |
275 | * shouldn't generally be modified directly, therefore this function is used to | |
276 | * prepare a new copy, which the caller then modifies and then commits by | |
277 | * calling commit_creds(). | |
278 | * | |
3b11a1de DH |
279 | * Preparation involves making a copy of the objective creds for modification. |
280 | * | |
d84f4f99 DH |
281 | * Returns a pointer to the new creds-to-be if successful, NULL otherwise. |
282 | * | |
283 | * Call commit_creds() or abort_creds() to clean up. | |
284 | */ | |
285 | struct cred *prepare_creds(void) | |
286 | { | |
287 | struct task_struct *task = current; | |
288 | const struct cred *old; | |
289 | struct cred *new; | |
290 | ||
e0e81739 | 291 | validate_process_creds(); |
d84f4f99 DH |
292 | |
293 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); | |
294 | if (!new) | |
295 | return NULL; | |
296 | ||
e0e81739 DH |
297 | kdebug("prepare_creds() alloc %p", new); |
298 | ||
d84f4f99 DH |
299 | old = task->cred; |
300 | memcpy(new, old, sizeof(struct cred)); | |
301 | ||
302 | atomic_set(&new->usage, 1); | |
e0e81739 | 303 | set_cred_subscribers(new, 0); |
d84f4f99 DH |
304 | get_group_info(new->group_info); |
305 | get_uid(new->user); | |
306 | ||
307 | #ifdef CONFIG_KEYS | |
308 | key_get(new->thread_keyring); | |
309 | key_get(new->request_key_auth); | |
310 | atomic_inc(&new->tgcred->usage); | |
311 | #endif | |
312 | ||
313 | #ifdef CONFIG_SECURITY | |
314 | new->security = NULL; | |
315 | #endif | |
316 | ||
317 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) | |
318 | goto error; | |
e0e81739 | 319 | validate_creds(new); |
d84f4f99 DH |
320 | return new; |
321 | ||
322 | error: | |
323 | abort_creds(new); | |
324 | return NULL; | |
325 | } | |
326 | EXPORT_SYMBOL(prepare_creds); | |
327 | ||
a6f76f23 DH |
328 | /* |
329 | * Prepare credentials for current to perform an execve() | |
9b1bf12d | 330 | * - The caller must hold ->cred_guard_mutex |
a6f76f23 DH |
331 | */ |
332 | struct cred *prepare_exec_creds(void) | |
333 | { | |
334 | struct thread_group_cred *tgcred = NULL; | |
335 | struct cred *new; | |
336 | ||
337 | #ifdef CONFIG_KEYS | |
338 | tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); | |
339 | if (!tgcred) | |
340 | return NULL; | |
341 | #endif | |
342 | ||
343 | new = prepare_creds(); | |
344 | if (!new) { | |
345 | kfree(tgcred); | |
346 | return new; | |
347 | } | |
348 | ||
349 | #ifdef CONFIG_KEYS | |
350 | /* newly exec'd tasks don't get a thread keyring */ | |
351 | key_put(new->thread_keyring); | |
352 | new->thread_keyring = NULL; | |
353 | ||
354 | /* create a new per-thread-group creds for all this set of threads to | |
355 | * share */ | |
356 | memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred)); | |
357 | ||
358 | atomic_set(&tgcred->usage, 1); | |
359 | spin_lock_init(&tgcred->lock); | |
360 | ||
361 | /* inherit the session keyring; new process keyring */ | |
362 | key_get(tgcred->session_keyring); | |
363 | tgcred->process_keyring = NULL; | |
364 | ||
365 | release_tgcred(new); | |
366 | new->tgcred = tgcred; | |
367 | #endif | |
368 | ||
369 | return new; | |
370 | } | |
371 | ||
f1752eec DH |
372 | /* |
373 | * Copy credentials for the new process created by fork() | |
d84f4f99 DH |
374 | * |
375 | * We share if we can, but under some circumstances we have to generate a new | |
376 | * set. | |
3b11a1de DH |
377 | * |
378 | * The new process gets the current process's subjective credentials as its | |
379 | * objective and subjective credentials | |
f1752eec DH |
380 | */ |
381 | int copy_creds(struct task_struct *p, unsigned long clone_flags) | |
382 | { | |
d84f4f99 DH |
383 | #ifdef CONFIG_KEYS |
384 | struct thread_group_cred *tgcred; | |
385 | #endif | |
386 | struct cred *new; | |
18b6e041 | 387 | int ret; |
d84f4f99 | 388 | |
d84f4f99 DH |
389 | if ( |
390 | #ifdef CONFIG_KEYS | |
391 | !p->cred->thread_keyring && | |
392 | #endif | |
393 | clone_flags & CLONE_THREAD | |
394 | ) { | |
3b11a1de | 395 | p->real_cred = get_cred(p->cred); |
d84f4f99 | 396 | get_cred(p->cred); |
e0e81739 DH |
397 | alter_cred_subscribers(p->cred, 2); |
398 | kdebug("share_creds(%p{%d,%d})", | |
399 | p->cred, atomic_read(&p->cred->usage), | |
400 | read_cred_subscribers(p->cred)); | |
d84f4f99 DH |
401 | atomic_inc(&p->cred->user->processes); |
402 | return 0; | |
403 | } | |
404 | ||
405 | new = prepare_creds(); | |
406 | if (!new) | |
f1752eec DH |
407 | return -ENOMEM; |
408 | ||
18b6e041 SH |
409 | if (clone_flags & CLONE_NEWUSER) { |
410 | ret = create_user_ns(new); | |
411 | if (ret < 0) | |
412 | goto error_put; | |
413 | } | |
414 | ||
47a150ed SH |
415 | /* cache user_ns in cred. Doesn't need a refcount because it will |
416 | * stay pinned by cred->user | |
417 | */ | |
418 | new->user_ns = new->user->user_ns; | |
419 | ||
bb952bb9 | 420 | #ifdef CONFIG_KEYS |
d84f4f99 DH |
421 | /* new threads get their own thread keyrings if their parent already |
422 | * had one */ | |
423 | if (new->thread_keyring) { | |
424 | key_put(new->thread_keyring); | |
425 | new->thread_keyring = NULL; | |
426 | if (clone_flags & CLONE_THREAD) | |
427 | install_thread_keyring_to_cred(new); | |
428 | } | |
429 | ||
430 | /* we share the process and session keyrings between all the threads in | |
431 | * a process - this is slightly icky as we violate COW credentials a | |
432 | * bit */ | |
433 | if (!(clone_flags & CLONE_THREAD)) { | |
434 | tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); | |
435 | if (!tgcred) { | |
18b6e041 SH |
436 | ret = -ENOMEM; |
437 | goto error_put; | |
bb952bb9 | 438 | } |
d84f4f99 DH |
439 | atomic_set(&tgcred->usage, 1); |
440 | spin_lock_init(&tgcred->lock); | |
441 | tgcred->process_keyring = NULL; | |
442 | tgcred->session_keyring = key_get(new->tgcred->session_keyring); | |
443 | ||
444 | release_tgcred(new); | |
445 | new->tgcred = tgcred; | |
bb952bb9 DH |
446 | } |
447 | #endif | |
448 | ||
d84f4f99 | 449 | atomic_inc(&new->user->processes); |
3b11a1de | 450 | p->cred = p->real_cred = get_cred(new); |
e0e81739 DH |
451 | alter_cred_subscribers(new, 2); |
452 | validate_creds(new); | |
d84f4f99 | 453 | return 0; |
18b6e041 SH |
454 | |
455 | error_put: | |
456 | put_cred(new); | |
457 | return ret; | |
d84f4f99 | 458 | } |
f1752eec | 459 | |
d84f4f99 DH |
460 | /** |
461 | * commit_creds - Install new credentials upon the current task | |
462 | * @new: The credentials to be assigned | |
463 | * | |
464 | * Install a new set of credentials to the current task, using RCU to replace | |
3b11a1de DH |
465 | * the old set. Both the objective and the subjective credentials pointers are |
466 | * updated. This function may not be called if the subjective credentials are | |
467 | * in an overridden state. | |
d84f4f99 DH |
468 | * |
469 | * This function eats the caller's reference to the new credentials. | |
470 | * | |
471 | * Always returns 0 thus allowing this function to be tail-called at the end | |
472 | * of, say, sys_setgid(). | |
473 | */ | |
474 | int commit_creds(struct cred *new) | |
475 | { | |
476 | struct task_struct *task = current; | |
e0e81739 | 477 | const struct cred *old = task->real_cred; |
d84f4f99 | 478 | |
e0e81739 DH |
479 | kdebug("commit_creds(%p{%d,%d})", new, |
480 | atomic_read(&new->usage), | |
481 | read_cred_subscribers(new)); | |
482 | ||
483 | BUG_ON(task->cred != old); | |
484 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
485 | BUG_ON(read_cred_subscribers(old) < 2); | |
486 | validate_creds(old); | |
487 | validate_creds(new); | |
488 | #endif | |
d84f4f99 | 489 | BUG_ON(atomic_read(&new->usage) < 1); |
d84f4f99 | 490 | |
3b11a1de DH |
491 | get_cred(new); /* we will require a ref for the subj creds too */ |
492 | ||
d84f4f99 DH |
493 | /* dumpability changes */ |
494 | if (old->euid != new->euid || | |
495 | old->egid != new->egid || | |
496 | old->fsuid != new->fsuid || | |
497 | old->fsgid != new->fsgid || | |
498 | !cap_issubset(new->cap_permitted, old->cap_permitted)) { | |
b9456371 DH |
499 | if (task->mm) |
500 | set_dumpable(task->mm, suid_dumpable); | |
d84f4f99 DH |
501 | task->pdeath_signal = 0; |
502 | smp_wmb(); | |
f1752eec DH |
503 | } |
504 | ||
d84f4f99 DH |
505 | /* alter the thread keyring */ |
506 | if (new->fsuid != old->fsuid) | |
507 | key_fsuid_changed(task); | |
508 | if (new->fsgid != old->fsgid) | |
509 | key_fsgid_changed(task); | |
510 | ||
511 | /* do it | |
72fa5997 VK |
512 | * RLIMIT_NPROC limits on user->processes have already been checked |
513 | * in set_user(). | |
d84f4f99 | 514 | */ |
e0e81739 | 515 | alter_cred_subscribers(new, 2); |
d84f4f99 DH |
516 | if (new->user != old->user) |
517 | atomic_inc(&new->user->processes); | |
3b11a1de | 518 | rcu_assign_pointer(task->real_cred, new); |
d84f4f99 DH |
519 | rcu_assign_pointer(task->cred, new); |
520 | if (new->user != old->user) | |
521 | atomic_dec(&old->user->processes); | |
e0e81739 | 522 | alter_cred_subscribers(old, -2); |
d84f4f99 | 523 | |
d84f4f99 DH |
524 | /* send notifications */ |
525 | if (new->uid != old->uid || | |
526 | new->euid != old->euid || | |
527 | new->suid != old->suid || | |
528 | new->fsuid != old->fsuid) | |
529 | proc_id_connector(task, PROC_EVENT_UID); | |
f1752eec | 530 | |
d84f4f99 DH |
531 | if (new->gid != old->gid || |
532 | new->egid != old->egid || | |
533 | new->sgid != old->sgid || | |
534 | new->fsgid != old->fsgid) | |
535 | proc_id_connector(task, PROC_EVENT_GID); | |
f1752eec | 536 | |
3b11a1de DH |
537 | /* release the old obj and subj refs both */ |
538 | put_cred(old); | |
d84f4f99 | 539 | put_cred(old); |
f1752eec DH |
540 | return 0; |
541 | } | |
d84f4f99 DH |
542 | EXPORT_SYMBOL(commit_creds); |
543 | ||
544 | /** | |
545 | * abort_creds - Discard a set of credentials and unlock the current task | |
546 | * @new: The credentials that were going to be applied | |
547 | * | |
548 | * Discard a set of credentials that were under construction and unlock the | |
549 | * current task. | |
550 | */ | |
551 | void abort_creds(struct cred *new) | |
552 | { | |
e0e81739 DH |
553 | kdebug("abort_creds(%p{%d,%d})", new, |
554 | atomic_read(&new->usage), | |
555 | read_cred_subscribers(new)); | |
556 | ||
557 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
558 | BUG_ON(read_cred_subscribers(new) != 0); | |
559 | #endif | |
d84f4f99 DH |
560 | BUG_ON(atomic_read(&new->usage) < 1); |
561 | put_cred(new); | |
562 | } | |
563 | EXPORT_SYMBOL(abort_creds); | |
564 | ||
565 | /** | |
3b11a1de | 566 | * override_creds - Override the current process's subjective credentials |
d84f4f99 DH |
567 | * @new: The credentials to be assigned |
568 | * | |
3b11a1de DH |
569 | * Install a set of temporary override subjective credentials on the current |
570 | * process, returning the old set for later reversion. | |
d84f4f99 DH |
571 | */ |
572 | const struct cred *override_creds(const struct cred *new) | |
573 | { | |
574 | const struct cred *old = current->cred; | |
575 | ||
e0e81739 DH |
576 | kdebug("override_creds(%p{%d,%d})", new, |
577 | atomic_read(&new->usage), | |
578 | read_cred_subscribers(new)); | |
579 | ||
580 | validate_creds(old); | |
581 | validate_creds(new); | |
582 | get_cred(new); | |
583 | alter_cred_subscribers(new, 1); | |
584 | rcu_assign_pointer(current->cred, new); | |
585 | alter_cred_subscribers(old, -1); | |
586 | ||
587 | kdebug("override_creds() = %p{%d,%d}", old, | |
588 | atomic_read(&old->usage), | |
589 | read_cred_subscribers(old)); | |
d84f4f99 DH |
590 | return old; |
591 | } | |
592 | EXPORT_SYMBOL(override_creds); | |
593 | ||
594 | /** | |
3b11a1de | 595 | * revert_creds - Revert a temporary subjective credentials override |
d84f4f99 DH |
596 | * @old: The credentials to be restored |
597 | * | |
3b11a1de DH |
598 | * Revert a temporary set of override subjective credentials to an old set, |
599 | * discarding the override set. | |
d84f4f99 DH |
600 | */ |
601 | void revert_creds(const struct cred *old) | |
602 | { | |
603 | const struct cred *override = current->cred; | |
604 | ||
e0e81739 DH |
605 | kdebug("revert_creds(%p{%d,%d})", old, |
606 | atomic_read(&old->usage), | |
607 | read_cred_subscribers(old)); | |
608 | ||
609 | validate_creds(old); | |
610 | validate_creds(override); | |
611 | alter_cred_subscribers(old, 1); | |
d84f4f99 | 612 | rcu_assign_pointer(current->cred, old); |
e0e81739 | 613 | alter_cred_subscribers(override, -1); |
d84f4f99 DH |
614 | put_cred(override); |
615 | } | |
616 | EXPORT_SYMBOL(revert_creds); | |
617 | ||
618 | /* | |
619 | * initialise the credentials stuff | |
620 | */ | |
621 | void __init cred_init(void) | |
622 | { | |
623 | /* allocate a slab in which we can store credentials */ | |
624 | cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), | |
625 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
626 | } | |
3a3b7ce9 DH |
627 | |
628 | /** | |
629 | * prepare_kernel_cred - Prepare a set of credentials for a kernel service | |
630 | * @daemon: A userspace daemon to be used as a reference | |
631 | * | |
632 | * Prepare a set of credentials for a kernel service. This can then be used to | |
633 | * override a task's own credentials so that work can be done on behalf of that | |
634 | * task that requires a different subjective context. | |
635 | * | |
636 | * @daemon is used to provide a base for the security record, but can be NULL. | |
637 | * If @daemon is supplied, then the security data will be derived from that; | |
638 | * otherwise they'll be set to 0 and no groups, full capabilities and no keys. | |
639 | * | |
640 | * The caller may change these controls afterwards if desired. | |
641 | * | |
642 | * Returns the new credentials or NULL if out of memory. | |
643 | * | |
644 | * Does not take, and does not return holding current->cred_replace_mutex. | |
645 | */ | |
646 | struct cred *prepare_kernel_cred(struct task_struct *daemon) | |
647 | { | |
012146d0 DH |
648 | #ifdef CONFIG_KEYS |
649 | struct thread_group_cred *tgcred; | |
650 | #endif | |
3a3b7ce9 DH |
651 | const struct cred *old; |
652 | struct cred *new; | |
653 | ||
654 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); | |
655 | if (!new) | |
656 | return NULL; | |
657 | ||
8ad346c6 | 658 | #ifdef CONFIG_KEYS |
012146d0 DH |
659 | tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); |
660 | if (!tgcred) { | |
661 | kmem_cache_free(cred_jar, new); | |
662 | return NULL; | |
663 | } | |
8ad346c6 | 664 | #endif |
012146d0 | 665 | |
e0e81739 DH |
666 | kdebug("prepare_kernel_cred() alloc %p", new); |
667 | ||
3a3b7ce9 DH |
668 | if (daemon) |
669 | old = get_task_cred(daemon); | |
670 | else | |
671 | old = get_cred(&init_cred); | |
672 | ||
e0e81739 DH |
673 | validate_creds(old); |
674 | ||
43529c97 | 675 | *new = *old; |
fb2b2a1d TH |
676 | atomic_set(&new->usage, 1); |
677 | set_cred_subscribers(new, 0); | |
3a3b7ce9 DH |
678 | get_uid(new->user); |
679 | get_group_info(new->group_info); | |
680 | ||
681 | #ifdef CONFIG_KEYS | |
012146d0 DH |
682 | atomic_set(&tgcred->usage, 1); |
683 | spin_lock_init(&tgcred->lock); | |
684 | tgcred->process_keyring = NULL; | |
685 | tgcred->session_keyring = NULL; | |
686 | new->tgcred = tgcred; | |
3a3b7ce9 DH |
687 | new->request_key_auth = NULL; |
688 | new->thread_keyring = NULL; | |
689 | new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; | |
690 | #endif | |
691 | ||
692 | #ifdef CONFIG_SECURITY | |
693 | new->security = NULL; | |
694 | #endif | |
695 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) | |
696 | goto error; | |
697 | ||
3a3b7ce9 | 698 | put_cred(old); |
e0e81739 | 699 | validate_creds(new); |
3a3b7ce9 DH |
700 | return new; |
701 | ||
702 | error: | |
703 | put_cred(new); | |
0de33681 | 704 | put_cred(old); |
3a3b7ce9 DH |
705 | return NULL; |
706 | } | |
707 | EXPORT_SYMBOL(prepare_kernel_cred); | |
708 | ||
709 | /** | |
710 | * set_security_override - Set the security ID in a set of credentials | |
711 | * @new: The credentials to alter | |
712 | * @secid: The LSM security ID to set | |
713 | * | |
714 | * Set the LSM security ID in a set of credentials so that the subjective | |
715 | * security is overridden when an alternative set of credentials is used. | |
716 | */ | |
717 | int set_security_override(struct cred *new, u32 secid) | |
718 | { | |
719 | return security_kernel_act_as(new, secid); | |
720 | } | |
721 | EXPORT_SYMBOL(set_security_override); | |
722 | ||
723 | /** | |
724 | * set_security_override_from_ctx - Set the security ID in a set of credentials | |
725 | * @new: The credentials to alter | |
726 | * @secctx: The LSM security context to generate the security ID from. | |
727 | * | |
728 | * Set the LSM security ID in a set of credentials so that the subjective | |
729 | * security is overridden when an alternative set of credentials is used. The | |
730 | * security ID is specified in string form as a security context to be | |
731 | * interpreted by the LSM. | |
732 | */ | |
733 | int set_security_override_from_ctx(struct cred *new, const char *secctx) | |
734 | { | |
735 | u32 secid; | |
736 | int ret; | |
737 | ||
738 | ret = security_secctx_to_secid(secctx, strlen(secctx), &secid); | |
739 | if (ret < 0) | |
740 | return ret; | |
741 | ||
742 | return set_security_override(new, secid); | |
743 | } | |
744 | EXPORT_SYMBOL(set_security_override_from_ctx); | |
745 | ||
746 | /** | |
747 | * set_create_files_as - Set the LSM file create context in a set of credentials | |
748 | * @new: The credentials to alter | |
749 | * @inode: The inode to take the context from | |
750 | * | |
751 | * Change the LSM file creation context in a set of credentials to be the same | |
752 | * as the object context of the specified inode, so that the new inodes have | |
753 | * the same MAC context as that inode. | |
754 | */ | |
755 | int set_create_files_as(struct cred *new, struct inode *inode) | |
756 | { | |
757 | new->fsuid = inode->i_uid; | |
758 | new->fsgid = inode->i_gid; | |
759 | return security_kernel_create_files_as(new, inode); | |
760 | } | |
761 | EXPORT_SYMBOL(set_create_files_as); | |
e0e81739 DH |
762 | |
763 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
764 | ||
74908a00 AM |
765 | bool creds_are_invalid(const struct cred *cred) |
766 | { | |
767 | if (cred->magic != CRED_MAGIC) | |
768 | return true; | |
74908a00 | 769 | #ifdef CONFIG_SECURITY_SELINUX |
2edeaa34 TH |
770 | /* |
771 | * cred->security == NULL if security_cred_alloc_blank() or | |
772 | * security_prepare_creds() returned an error. | |
773 | */ | |
774 | if (selinux_is_enabled() && cred->security) { | |
74908a00 AM |
775 | if ((unsigned long) cred->security < PAGE_SIZE) |
776 | return true; | |
777 | if ((*(u32 *)cred->security & 0xffffff00) == | |
778 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)) | |
779 | return true; | |
780 | } | |
781 | #endif | |
782 | return false; | |
783 | } | |
764db03f | 784 | EXPORT_SYMBOL(creds_are_invalid); |
74908a00 | 785 | |
e0e81739 DH |
786 | /* |
787 | * dump invalid credentials | |
788 | */ | |
789 | static void dump_invalid_creds(const struct cred *cred, const char *label, | |
790 | const struct task_struct *tsk) | |
791 | { | |
792 | printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n", | |
793 | label, cred, | |
794 | cred == &init_cred ? "[init]" : "", | |
795 | cred == tsk->real_cred ? "[real]" : "", | |
796 | cred == tsk->cred ? "[eff]" : ""); | |
797 | printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n", | |
798 | cred->magic, cred->put_addr); | |
799 | printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n", | |
800 | atomic_read(&cred->usage), | |
801 | read_cred_subscribers(cred)); | |
802 | printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n", | |
803 | cred->uid, cred->euid, cred->suid, cred->fsuid); | |
804 | printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n", | |
805 | cred->gid, cred->egid, cred->sgid, cred->fsgid); | |
806 | #ifdef CONFIG_SECURITY | |
807 | printk(KERN_ERR "CRED: ->security is %p\n", cred->security); | |
808 | if ((unsigned long) cred->security >= PAGE_SIZE && | |
809 | (((unsigned long) cred->security & 0xffffff00) != | |
810 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))) | |
811 | printk(KERN_ERR "CRED: ->security {%x, %x}\n", | |
812 | ((u32*)cred->security)[0], | |
813 | ((u32*)cred->security)[1]); | |
814 | #endif | |
815 | } | |
816 | ||
817 | /* | |
818 | * report use of invalid credentials | |
819 | */ | |
820 | void __invalid_creds(const struct cred *cred, const char *file, unsigned line) | |
821 | { | |
822 | printk(KERN_ERR "CRED: Invalid credentials\n"); | |
823 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); | |
824 | dump_invalid_creds(cred, "Specified", current); | |
825 | BUG(); | |
826 | } | |
827 | EXPORT_SYMBOL(__invalid_creds); | |
828 | ||
829 | /* | |
830 | * check the credentials on a process | |
831 | */ | |
832 | void __validate_process_creds(struct task_struct *tsk, | |
833 | const char *file, unsigned line) | |
834 | { | |
835 | if (tsk->cred == tsk->real_cred) { | |
836 | if (unlikely(read_cred_subscribers(tsk->cred) < 2 || | |
837 | creds_are_invalid(tsk->cred))) | |
838 | goto invalid_creds; | |
839 | } else { | |
840 | if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 || | |
841 | read_cred_subscribers(tsk->cred) < 1 || | |
842 | creds_are_invalid(tsk->real_cred) || | |
843 | creds_are_invalid(tsk->cred))) | |
844 | goto invalid_creds; | |
845 | } | |
846 | return; | |
847 | ||
848 | invalid_creds: | |
849 | printk(KERN_ERR "CRED: Invalid process credentials\n"); | |
850 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); | |
851 | ||
852 | dump_invalid_creds(tsk->real_cred, "Real", tsk); | |
853 | if (tsk->cred != tsk->real_cred) | |
854 | dump_invalid_creds(tsk->cred, "Effective", tsk); | |
855 | else | |
856 | printk(KERN_ERR "CRED: Effective creds == Real creds\n"); | |
857 | BUG(); | |
858 | } | |
859 | EXPORT_SYMBOL(__validate_process_creds); | |
860 | ||
861 | /* | |
862 | * check creds for do_exit() | |
863 | */ | |
864 | void validate_creds_for_do_exit(struct task_struct *tsk) | |
865 | { | |
866 | kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})", | |
867 | tsk->real_cred, tsk->cred, | |
868 | atomic_read(&tsk->cred->usage), | |
869 | read_cred_subscribers(tsk->cred)); | |
870 | ||
871 | __validate_process_creds(tsk, __FILE__, __LINE__); | |
872 | } | |
873 | ||
874 | #endif /* CONFIG_DEBUG_CREDENTIALS */ |