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98870ab0 | 1 | /* Task credentials management - see Documentation/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 | */ | |
11 | #include <linux/module.h> | |
12 | #include <linux/cred.h> | |
13 | #include <linux/sched.h> | |
14 | #include <linux/key.h> | |
15 | #include <linux/keyctl.h> | |
16 | #include <linux/init_task.h> | |
17 | #include <linux/security.h> | |
d84f4f99 | 18 | #include <linux/cn_proc.h> |
d84f4f99 | 19 | |
e0e81739 DH |
20 | #if 0 |
21 | #define kdebug(FMT, ...) \ | |
22 | printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__) | |
23 | #else | |
24 | static inline __attribute__((format(printf, 1, 2))) | |
25 | void no_printk(const char *fmt, ...) | |
26 | { | |
27 | } | |
28 | #define kdebug(FMT, ...) \ | |
29 | no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__) | |
30 | #endif | |
31 | ||
d84f4f99 | 32 | static struct kmem_cache *cred_jar; |
f1752eec | 33 | |
bb952bb9 DH |
34 | /* |
35 | * The common credentials for the initial task's thread group | |
36 | */ | |
37 | #ifdef CONFIG_KEYS | |
38 | static struct thread_group_cred init_tgcred = { | |
39 | .usage = ATOMIC_INIT(2), | |
40 | .tgid = 0, | |
41 | .lock = SPIN_LOCK_UNLOCKED, | |
42 | }; | |
43 | #endif | |
44 | ||
f1752eec DH |
45 | /* |
46 | * The initial credentials for the initial task | |
47 | */ | |
48 | struct cred init_cred = { | |
3b11a1de | 49 | .usage = ATOMIC_INIT(4), |
e0e81739 DH |
50 | #ifdef CONFIG_DEBUG_CREDENTIALS |
51 | .subscribers = ATOMIC_INIT(2), | |
52 | .magic = CRED_MAGIC, | |
53 | #endif | |
f1752eec DH |
54 | .securebits = SECUREBITS_DEFAULT, |
55 | .cap_inheritable = CAP_INIT_INH_SET, | |
56 | .cap_permitted = CAP_FULL_SET, | |
57 | .cap_effective = CAP_INIT_EFF_SET, | |
58 | .cap_bset = CAP_INIT_BSET, | |
59 | .user = INIT_USER, | |
60 | .group_info = &init_groups, | |
bb952bb9 DH |
61 | #ifdef CONFIG_KEYS |
62 | .tgcred = &init_tgcred, | |
63 | #endif | |
f1752eec DH |
64 | }; |
65 | ||
e0e81739 DH |
66 | static inline void set_cred_subscribers(struct cred *cred, int n) |
67 | { | |
68 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
69 | atomic_set(&cred->subscribers, n); | |
70 | #endif | |
71 | } | |
72 | ||
73 | static inline int read_cred_subscribers(const struct cred *cred) | |
74 | { | |
75 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
76 | return atomic_read(&cred->subscribers); | |
77 | #else | |
78 | return 0; | |
79 | #endif | |
80 | } | |
81 | ||
82 | static inline void alter_cred_subscribers(const struct cred *_cred, int n) | |
83 | { | |
84 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
85 | struct cred *cred = (struct cred *) _cred; | |
86 | ||
87 | atomic_add(n, &cred->subscribers); | |
88 | #endif | |
89 | } | |
90 | ||
bb952bb9 DH |
91 | /* |
92 | * Dispose of the shared task group credentials | |
93 | */ | |
94 | #ifdef CONFIG_KEYS | |
95 | static void release_tgcred_rcu(struct rcu_head *rcu) | |
96 | { | |
97 | struct thread_group_cred *tgcred = | |
98 | container_of(rcu, struct thread_group_cred, rcu); | |
99 | ||
100 | BUG_ON(atomic_read(&tgcred->usage) != 0); | |
101 | ||
102 | key_put(tgcred->session_keyring); | |
103 | key_put(tgcred->process_keyring); | |
104 | kfree(tgcred); | |
105 | } | |
106 | #endif | |
107 | ||
108 | /* | |
109 | * Release a set of thread group credentials. | |
110 | */ | |
a6f76f23 | 111 | static void release_tgcred(struct cred *cred) |
bb952bb9 DH |
112 | { |
113 | #ifdef CONFIG_KEYS | |
114 | struct thread_group_cred *tgcred = cred->tgcred; | |
115 | ||
116 | if (atomic_dec_and_test(&tgcred->usage)) | |
117 | call_rcu(&tgcred->rcu, release_tgcred_rcu); | |
118 | #endif | |
119 | } | |
120 | ||
f1752eec DH |
121 | /* |
122 | * The RCU callback to actually dispose of a set of credentials | |
123 | */ | |
124 | static void put_cred_rcu(struct rcu_head *rcu) | |
125 | { | |
126 | struct cred *cred = container_of(rcu, struct cred, rcu); | |
127 | ||
e0e81739 DH |
128 | kdebug("put_cred_rcu(%p)", cred); |
129 | ||
130 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
131 | if (cred->magic != CRED_MAGIC_DEAD || | |
132 | atomic_read(&cred->usage) != 0 || | |
133 | read_cred_subscribers(cred) != 0) | |
134 | panic("CRED: put_cred_rcu() sees %p with" | |
135 | " mag %x, put %p, usage %d, subscr %d\n", | |
136 | cred, cred->magic, cred->put_addr, | |
137 | atomic_read(&cred->usage), | |
138 | read_cred_subscribers(cred)); | |
139 | #else | |
d84f4f99 DH |
140 | if (atomic_read(&cred->usage) != 0) |
141 | panic("CRED: put_cred_rcu() sees %p with usage %d\n", | |
142 | cred, atomic_read(&cred->usage)); | |
e0e81739 | 143 | #endif |
f1752eec | 144 | |
d84f4f99 | 145 | security_cred_free(cred); |
f1752eec DH |
146 | key_put(cred->thread_keyring); |
147 | key_put(cred->request_key_auth); | |
bb952bb9 | 148 | release_tgcred(cred); |
4a5d6ba1 DH |
149 | if (cred->group_info) |
150 | put_group_info(cred->group_info); | |
f1752eec | 151 | free_uid(cred->user); |
d84f4f99 | 152 | kmem_cache_free(cred_jar, cred); |
f1752eec DH |
153 | } |
154 | ||
155 | /** | |
156 | * __put_cred - Destroy a set of credentials | |
d84f4f99 | 157 | * @cred: The record to release |
f1752eec DH |
158 | * |
159 | * Destroy a set of credentials on which no references remain. | |
160 | */ | |
161 | void __put_cred(struct cred *cred) | |
162 | { | |
e0e81739 DH |
163 | kdebug("__put_cred(%p{%d,%d})", cred, |
164 | atomic_read(&cred->usage), | |
165 | read_cred_subscribers(cred)); | |
166 | ||
d84f4f99 | 167 | BUG_ON(atomic_read(&cred->usage) != 0); |
e0e81739 DH |
168 | #ifdef CONFIG_DEBUG_CREDENTIALS |
169 | BUG_ON(read_cred_subscribers(cred) != 0); | |
170 | cred->magic = CRED_MAGIC_DEAD; | |
171 | cred->put_addr = __builtin_return_address(0); | |
172 | #endif | |
173 | BUG_ON(cred == current->cred); | |
174 | BUG_ON(cred == current->real_cred); | |
d84f4f99 | 175 | |
f1752eec DH |
176 | call_rcu(&cred->rcu, put_cred_rcu); |
177 | } | |
178 | EXPORT_SYMBOL(__put_cred); | |
179 | ||
e0e81739 DH |
180 | /* |
181 | * Clean up a task's credentials when it exits | |
182 | */ | |
183 | void exit_creds(struct task_struct *tsk) | |
184 | { | |
185 | struct cred *cred; | |
186 | ||
187 | kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred, | |
188 | atomic_read(&tsk->cred->usage), | |
189 | read_cred_subscribers(tsk->cred)); | |
190 | ||
191 | cred = (struct cred *) tsk->real_cred; | |
192 | tsk->real_cred = NULL; | |
193 | validate_creds(cred); | |
194 | alter_cred_subscribers(cred, -1); | |
195 | put_cred(cred); | |
196 | ||
197 | cred = (struct cred *) tsk->cred; | |
198 | tsk->cred = NULL; | |
199 | validate_creds(cred); | |
200 | alter_cred_subscribers(cred, -1); | |
201 | put_cred(cred); | |
ee18d64c DH |
202 | |
203 | cred = (struct cred *) tsk->replacement_session_keyring; | |
204 | if (cred) { | |
205 | tsk->replacement_session_keyring = NULL; | |
206 | validate_creds(cred); | |
207 | put_cred(cred); | |
208 | } | |
209 | } | |
210 | ||
211 | /* | |
212 | * Allocate blank credentials, such that the credentials can be filled in at a | |
213 | * later date without risk of ENOMEM. | |
214 | */ | |
215 | struct cred *cred_alloc_blank(void) | |
216 | { | |
217 | struct cred *new; | |
218 | ||
219 | new = kmem_cache_zalloc(cred_jar, GFP_KERNEL); | |
220 | if (!new) | |
221 | return NULL; | |
222 | ||
223 | #ifdef CONFIG_KEYS | |
224 | new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL); | |
225 | if (!new->tgcred) { | |
b8a1d37c | 226 | kmem_cache_free(cred_jar, new); |
ee18d64c DH |
227 | return NULL; |
228 | } | |
229 | atomic_set(&new->tgcred->usage, 1); | |
230 | #endif | |
231 | ||
232 | atomic_set(&new->usage, 1); | |
233 | ||
234 | if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) | |
235 | goto error; | |
236 | ||
237 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
238 | new->magic = CRED_MAGIC; | |
239 | #endif | |
240 | return new; | |
241 | ||
242 | error: | |
243 | abort_creds(new); | |
244 | return NULL; | |
e0e81739 DH |
245 | } |
246 | ||
d84f4f99 DH |
247 | /** |
248 | * prepare_creds - Prepare a new set of credentials for modification | |
249 | * | |
250 | * Prepare a new set of task credentials for modification. A task's creds | |
251 | * shouldn't generally be modified directly, therefore this function is used to | |
252 | * prepare a new copy, which the caller then modifies and then commits by | |
253 | * calling commit_creds(). | |
254 | * | |
3b11a1de DH |
255 | * Preparation involves making a copy of the objective creds for modification. |
256 | * | |
d84f4f99 DH |
257 | * Returns a pointer to the new creds-to-be if successful, NULL otherwise. |
258 | * | |
259 | * Call commit_creds() or abort_creds() to clean up. | |
260 | */ | |
261 | struct cred *prepare_creds(void) | |
262 | { | |
263 | struct task_struct *task = current; | |
264 | const struct cred *old; | |
265 | struct cred *new; | |
266 | ||
e0e81739 | 267 | validate_process_creds(); |
d84f4f99 DH |
268 | |
269 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); | |
270 | if (!new) | |
271 | return NULL; | |
272 | ||
e0e81739 DH |
273 | kdebug("prepare_creds() alloc %p", new); |
274 | ||
d84f4f99 DH |
275 | old = task->cred; |
276 | memcpy(new, old, sizeof(struct cred)); | |
277 | ||
278 | atomic_set(&new->usage, 1); | |
e0e81739 | 279 | set_cred_subscribers(new, 0); |
d84f4f99 DH |
280 | get_group_info(new->group_info); |
281 | get_uid(new->user); | |
282 | ||
283 | #ifdef CONFIG_KEYS | |
284 | key_get(new->thread_keyring); | |
285 | key_get(new->request_key_auth); | |
286 | atomic_inc(&new->tgcred->usage); | |
287 | #endif | |
288 | ||
289 | #ifdef CONFIG_SECURITY | |
290 | new->security = NULL; | |
291 | #endif | |
292 | ||
293 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) | |
294 | goto error; | |
e0e81739 | 295 | validate_creds(new); |
d84f4f99 DH |
296 | return new; |
297 | ||
298 | error: | |
299 | abort_creds(new); | |
300 | return NULL; | |
301 | } | |
302 | EXPORT_SYMBOL(prepare_creds); | |
303 | ||
a6f76f23 DH |
304 | /* |
305 | * Prepare credentials for current to perform an execve() | |
5e751e99 | 306 | * - The caller must hold current->cred_guard_mutex |
a6f76f23 DH |
307 | */ |
308 | struct cred *prepare_exec_creds(void) | |
309 | { | |
310 | struct thread_group_cred *tgcred = NULL; | |
311 | struct cred *new; | |
312 | ||
313 | #ifdef CONFIG_KEYS | |
314 | tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); | |
315 | if (!tgcred) | |
316 | return NULL; | |
317 | #endif | |
318 | ||
319 | new = prepare_creds(); | |
320 | if (!new) { | |
321 | kfree(tgcred); | |
322 | return new; | |
323 | } | |
324 | ||
325 | #ifdef CONFIG_KEYS | |
326 | /* newly exec'd tasks don't get a thread keyring */ | |
327 | key_put(new->thread_keyring); | |
328 | new->thread_keyring = NULL; | |
329 | ||
330 | /* create a new per-thread-group creds for all this set of threads to | |
331 | * share */ | |
332 | memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred)); | |
333 | ||
334 | atomic_set(&tgcred->usage, 1); | |
335 | spin_lock_init(&tgcred->lock); | |
336 | ||
337 | /* inherit the session keyring; new process keyring */ | |
338 | key_get(tgcred->session_keyring); | |
339 | tgcred->process_keyring = NULL; | |
340 | ||
341 | release_tgcred(new); | |
342 | new->tgcred = tgcred; | |
343 | #endif | |
344 | ||
345 | return new; | |
346 | } | |
347 | ||
d84f4f99 DH |
348 | /* |
349 | * prepare new credentials for the usermode helper dispatcher | |
350 | */ | |
351 | struct cred *prepare_usermodehelper_creds(void) | |
352 | { | |
353 | #ifdef CONFIG_KEYS | |
354 | struct thread_group_cred *tgcred = NULL; | |
355 | #endif | |
356 | struct cred *new; | |
357 | ||
358 | #ifdef CONFIG_KEYS | |
359 | tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC); | |
360 | if (!tgcred) | |
361 | return NULL; | |
362 | #endif | |
363 | ||
364 | new = kmem_cache_alloc(cred_jar, GFP_ATOMIC); | |
365 | if (!new) | |
570b8fb5 | 366 | goto free_tgcred; |
d84f4f99 | 367 | |
e0e81739 DH |
368 | kdebug("prepare_usermodehelper_creds() alloc %p", new); |
369 | ||
d84f4f99 DH |
370 | memcpy(new, &init_cred, sizeof(struct cred)); |
371 | ||
372 | atomic_set(&new->usage, 1); | |
e0e81739 | 373 | set_cred_subscribers(new, 0); |
d84f4f99 DH |
374 | get_group_info(new->group_info); |
375 | get_uid(new->user); | |
376 | ||
377 | #ifdef CONFIG_KEYS | |
378 | new->thread_keyring = NULL; | |
379 | new->request_key_auth = NULL; | |
380 | new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT; | |
381 | ||
382 | atomic_set(&tgcred->usage, 1); | |
383 | spin_lock_init(&tgcred->lock); | |
384 | new->tgcred = tgcred; | |
385 | #endif | |
386 | ||
387 | #ifdef CONFIG_SECURITY | |
388 | new->security = NULL; | |
389 | #endif | |
390 | if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0) | |
391 | goto error; | |
e0e81739 | 392 | validate_creds(new); |
d84f4f99 DH |
393 | |
394 | BUG_ON(atomic_read(&new->usage) != 1); | |
395 | return new; | |
396 | ||
397 | error: | |
398 | put_cred(new); | |
570b8fb5 MD |
399 | free_tgcred: |
400 | #ifdef CONFIG_KEYS | |
401 | kfree(tgcred); | |
402 | #endif | |
d84f4f99 DH |
403 | return NULL; |
404 | } | |
405 | ||
f1752eec DH |
406 | /* |
407 | * Copy credentials for the new process created by fork() | |
d84f4f99 DH |
408 | * |
409 | * We share if we can, but under some circumstances we have to generate a new | |
410 | * set. | |
3b11a1de DH |
411 | * |
412 | * The new process gets the current process's subjective credentials as its | |
413 | * objective and subjective credentials | |
f1752eec DH |
414 | */ |
415 | int copy_creds(struct task_struct *p, unsigned long clone_flags) | |
416 | { | |
d84f4f99 DH |
417 | #ifdef CONFIG_KEYS |
418 | struct thread_group_cred *tgcred; | |
419 | #endif | |
420 | struct cred *new; | |
18b6e041 | 421 | int ret; |
d84f4f99 | 422 | |
5e751e99 | 423 | mutex_init(&p->cred_guard_mutex); |
f1752eec | 424 | |
d84f4f99 DH |
425 | if ( |
426 | #ifdef CONFIG_KEYS | |
427 | !p->cred->thread_keyring && | |
428 | #endif | |
429 | clone_flags & CLONE_THREAD | |
430 | ) { | |
3b11a1de | 431 | p->real_cred = get_cred(p->cred); |
d84f4f99 | 432 | get_cred(p->cred); |
e0e81739 DH |
433 | alter_cred_subscribers(p->cred, 2); |
434 | kdebug("share_creds(%p{%d,%d})", | |
435 | p->cred, atomic_read(&p->cred->usage), | |
436 | read_cred_subscribers(p->cred)); | |
d84f4f99 DH |
437 | atomic_inc(&p->cred->user->processes); |
438 | return 0; | |
439 | } | |
440 | ||
441 | new = prepare_creds(); | |
442 | if (!new) | |
f1752eec DH |
443 | return -ENOMEM; |
444 | ||
18b6e041 SH |
445 | if (clone_flags & CLONE_NEWUSER) { |
446 | ret = create_user_ns(new); | |
447 | if (ret < 0) | |
448 | goto error_put; | |
449 | } | |
450 | ||
bb952bb9 | 451 | #ifdef CONFIG_KEYS |
d84f4f99 DH |
452 | /* new threads get their own thread keyrings if their parent already |
453 | * had one */ | |
454 | if (new->thread_keyring) { | |
455 | key_put(new->thread_keyring); | |
456 | new->thread_keyring = NULL; | |
457 | if (clone_flags & CLONE_THREAD) | |
458 | install_thread_keyring_to_cred(new); | |
459 | } | |
460 | ||
461 | /* we share the process and session keyrings between all the threads in | |
462 | * a process - this is slightly icky as we violate COW credentials a | |
463 | * bit */ | |
464 | if (!(clone_flags & CLONE_THREAD)) { | |
465 | tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); | |
466 | if (!tgcred) { | |
18b6e041 SH |
467 | ret = -ENOMEM; |
468 | goto error_put; | |
bb952bb9 | 469 | } |
d84f4f99 DH |
470 | atomic_set(&tgcred->usage, 1); |
471 | spin_lock_init(&tgcred->lock); | |
472 | tgcred->process_keyring = NULL; | |
473 | tgcred->session_keyring = key_get(new->tgcred->session_keyring); | |
474 | ||
475 | release_tgcred(new); | |
476 | new->tgcred = tgcred; | |
bb952bb9 DH |
477 | } |
478 | #endif | |
479 | ||
d84f4f99 | 480 | atomic_inc(&new->user->processes); |
3b11a1de | 481 | p->cred = p->real_cred = get_cred(new); |
e0e81739 DH |
482 | alter_cred_subscribers(new, 2); |
483 | validate_creds(new); | |
d84f4f99 | 484 | return 0; |
18b6e041 SH |
485 | |
486 | error_put: | |
487 | put_cred(new); | |
488 | return ret; | |
d84f4f99 | 489 | } |
f1752eec | 490 | |
d84f4f99 DH |
491 | /** |
492 | * commit_creds - Install new credentials upon the current task | |
493 | * @new: The credentials to be assigned | |
494 | * | |
495 | * Install a new set of credentials to the current task, using RCU to replace | |
3b11a1de DH |
496 | * the old set. Both the objective and the subjective credentials pointers are |
497 | * updated. This function may not be called if the subjective credentials are | |
498 | * in an overridden state. | |
d84f4f99 DH |
499 | * |
500 | * This function eats the caller's reference to the new credentials. | |
501 | * | |
502 | * Always returns 0 thus allowing this function to be tail-called at the end | |
503 | * of, say, sys_setgid(). | |
504 | */ | |
505 | int commit_creds(struct cred *new) | |
506 | { | |
507 | struct task_struct *task = current; | |
e0e81739 | 508 | const struct cred *old = task->real_cred; |
d84f4f99 | 509 | |
e0e81739 DH |
510 | kdebug("commit_creds(%p{%d,%d})", new, |
511 | atomic_read(&new->usage), | |
512 | read_cred_subscribers(new)); | |
513 | ||
514 | BUG_ON(task->cred != old); | |
515 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
516 | BUG_ON(read_cred_subscribers(old) < 2); | |
517 | validate_creds(old); | |
518 | validate_creds(new); | |
519 | #endif | |
d84f4f99 | 520 | BUG_ON(atomic_read(&new->usage) < 1); |
d84f4f99 | 521 | |
d84f4f99 DH |
522 | security_commit_creds(new, old); |
523 | ||
3b11a1de DH |
524 | get_cred(new); /* we will require a ref for the subj creds too */ |
525 | ||
d84f4f99 DH |
526 | /* dumpability changes */ |
527 | if (old->euid != new->euid || | |
528 | old->egid != new->egid || | |
529 | old->fsuid != new->fsuid || | |
530 | old->fsgid != new->fsgid || | |
531 | !cap_issubset(new->cap_permitted, old->cap_permitted)) { | |
b9456371 DH |
532 | if (task->mm) |
533 | set_dumpable(task->mm, suid_dumpable); | |
d84f4f99 DH |
534 | task->pdeath_signal = 0; |
535 | smp_wmb(); | |
f1752eec DH |
536 | } |
537 | ||
d84f4f99 DH |
538 | /* alter the thread keyring */ |
539 | if (new->fsuid != old->fsuid) | |
540 | key_fsuid_changed(task); | |
541 | if (new->fsgid != old->fsgid) | |
542 | key_fsgid_changed(task); | |
543 | ||
544 | /* do it | |
545 | * - What if a process setreuid()'s and this brings the | |
546 | * new uid over his NPROC rlimit? We can check this now | |
547 | * cheaply with the new uid cache, so if it matters | |
548 | * we should be checking for it. -DaveM | |
549 | */ | |
e0e81739 | 550 | alter_cred_subscribers(new, 2); |
d84f4f99 DH |
551 | if (new->user != old->user) |
552 | atomic_inc(&new->user->processes); | |
3b11a1de | 553 | rcu_assign_pointer(task->real_cred, new); |
d84f4f99 DH |
554 | rcu_assign_pointer(task->cred, new); |
555 | if (new->user != old->user) | |
556 | atomic_dec(&old->user->processes); | |
e0e81739 | 557 | alter_cred_subscribers(old, -2); |
d84f4f99 | 558 | |
d84f4f99 DH |
559 | /* send notifications */ |
560 | if (new->uid != old->uid || | |
561 | new->euid != old->euid || | |
562 | new->suid != old->suid || | |
563 | new->fsuid != old->fsuid) | |
564 | proc_id_connector(task, PROC_EVENT_UID); | |
f1752eec | 565 | |
d84f4f99 DH |
566 | if (new->gid != old->gid || |
567 | new->egid != old->egid || | |
568 | new->sgid != old->sgid || | |
569 | new->fsgid != old->fsgid) | |
570 | proc_id_connector(task, PROC_EVENT_GID); | |
f1752eec | 571 | |
3b11a1de DH |
572 | /* release the old obj and subj refs both */ |
573 | put_cred(old); | |
d84f4f99 | 574 | put_cred(old); |
f1752eec DH |
575 | return 0; |
576 | } | |
d84f4f99 DH |
577 | EXPORT_SYMBOL(commit_creds); |
578 | ||
579 | /** | |
580 | * abort_creds - Discard a set of credentials and unlock the current task | |
581 | * @new: The credentials that were going to be applied | |
582 | * | |
583 | * Discard a set of credentials that were under construction and unlock the | |
584 | * current task. | |
585 | */ | |
586 | void abort_creds(struct cred *new) | |
587 | { | |
e0e81739 DH |
588 | kdebug("abort_creds(%p{%d,%d})", new, |
589 | atomic_read(&new->usage), | |
590 | read_cred_subscribers(new)); | |
591 | ||
592 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
593 | BUG_ON(read_cred_subscribers(new) != 0); | |
594 | #endif | |
d84f4f99 DH |
595 | BUG_ON(atomic_read(&new->usage) < 1); |
596 | put_cred(new); | |
597 | } | |
598 | EXPORT_SYMBOL(abort_creds); | |
599 | ||
600 | /** | |
3b11a1de | 601 | * override_creds - Override the current process's subjective credentials |
d84f4f99 DH |
602 | * @new: The credentials to be assigned |
603 | * | |
3b11a1de DH |
604 | * Install a set of temporary override subjective credentials on the current |
605 | * process, returning the old set for later reversion. | |
d84f4f99 DH |
606 | */ |
607 | const struct cred *override_creds(const struct cred *new) | |
608 | { | |
609 | const struct cred *old = current->cred; | |
610 | ||
e0e81739 DH |
611 | kdebug("override_creds(%p{%d,%d})", new, |
612 | atomic_read(&new->usage), | |
613 | read_cred_subscribers(new)); | |
614 | ||
615 | validate_creds(old); | |
616 | validate_creds(new); | |
617 | get_cred(new); | |
618 | alter_cred_subscribers(new, 1); | |
619 | rcu_assign_pointer(current->cred, new); | |
620 | alter_cred_subscribers(old, -1); | |
621 | ||
622 | kdebug("override_creds() = %p{%d,%d}", old, | |
623 | atomic_read(&old->usage), | |
624 | read_cred_subscribers(old)); | |
d84f4f99 DH |
625 | return old; |
626 | } | |
627 | EXPORT_SYMBOL(override_creds); | |
628 | ||
629 | /** | |
3b11a1de | 630 | * revert_creds - Revert a temporary subjective credentials override |
d84f4f99 DH |
631 | * @old: The credentials to be restored |
632 | * | |
3b11a1de DH |
633 | * Revert a temporary set of override subjective credentials to an old set, |
634 | * discarding the override set. | |
d84f4f99 DH |
635 | */ |
636 | void revert_creds(const struct cred *old) | |
637 | { | |
638 | const struct cred *override = current->cred; | |
639 | ||
e0e81739 DH |
640 | kdebug("revert_creds(%p{%d,%d})", old, |
641 | atomic_read(&old->usage), | |
642 | read_cred_subscribers(old)); | |
643 | ||
644 | validate_creds(old); | |
645 | validate_creds(override); | |
646 | alter_cred_subscribers(old, 1); | |
d84f4f99 | 647 | rcu_assign_pointer(current->cred, old); |
e0e81739 | 648 | alter_cred_subscribers(override, -1); |
d84f4f99 DH |
649 | put_cred(override); |
650 | } | |
651 | EXPORT_SYMBOL(revert_creds); | |
652 | ||
653 | /* | |
654 | * initialise the credentials stuff | |
655 | */ | |
656 | void __init cred_init(void) | |
657 | { | |
658 | /* allocate a slab in which we can store credentials */ | |
659 | cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), | |
660 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
661 | } | |
3a3b7ce9 DH |
662 | |
663 | /** | |
664 | * prepare_kernel_cred - Prepare a set of credentials for a kernel service | |
665 | * @daemon: A userspace daemon to be used as a reference | |
666 | * | |
667 | * Prepare a set of credentials for a kernel service. This can then be used to | |
668 | * override a task's own credentials so that work can be done on behalf of that | |
669 | * task that requires a different subjective context. | |
670 | * | |
671 | * @daemon is used to provide a base for the security record, but can be NULL. | |
672 | * If @daemon is supplied, then the security data will be derived from that; | |
673 | * otherwise they'll be set to 0 and no groups, full capabilities and no keys. | |
674 | * | |
675 | * The caller may change these controls afterwards if desired. | |
676 | * | |
677 | * Returns the new credentials or NULL if out of memory. | |
678 | * | |
679 | * Does not take, and does not return holding current->cred_replace_mutex. | |
680 | */ | |
681 | struct cred *prepare_kernel_cred(struct task_struct *daemon) | |
682 | { | |
683 | const struct cred *old; | |
684 | struct cred *new; | |
685 | ||
686 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); | |
687 | if (!new) | |
688 | return NULL; | |
689 | ||
e0e81739 DH |
690 | kdebug("prepare_kernel_cred() alloc %p", new); |
691 | ||
3a3b7ce9 DH |
692 | if (daemon) |
693 | old = get_task_cred(daemon); | |
694 | else | |
695 | old = get_cred(&init_cred); | |
696 | ||
e0e81739 DH |
697 | validate_creds(old); |
698 | ||
43529c97 | 699 | *new = *old; |
3a3b7ce9 DH |
700 | get_uid(new->user); |
701 | get_group_info(new->group_info); | |
702 | ||
703 | #ifdef CONFIG_KEYS | |
704 | atomic_inc(&init_tgcred.usage); | |
705 | new->tgcred = &init_tgcred; | |
706 | new->request_key_auth = NULL; | |
707 | new->thread_keyring = NULL; | |
708 | new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; | |
709 | #endif | |
710 | ||
711 | #ifdef CONFIG_SECURITY | |
712 | new->security = NULL; | |
713 | #endif | |
714 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) | |
715 | goto error; | |
716 | ||
717 | atomic_set(&new->usage, 1); | |
e0e81739 | 718 | set_cred_subscribers(new, 0); |
3a3b7ce9 | 719 | put_cred(old); |
e0e81739 | 720 | validate_creds(new); |
3a3b7ce9 DH |
721 | return new; |
722 | ||
723 | error: | |
724 | put_cred(new); | |
0de33681 | 725 | put_cred(old); |
3a3b7ce9 DH |
726 | return NULL; |
727 | } | |
728 | EXPORT_SYMBOL(prepare_kernel_cred); | |
729 | ||
730 | /** | |
731 | * set_security_override - Set the security ID in a set of credentials | |
732 | * @new: The credentials to alter | |
733 | * @secid: The LSM security ID to set | |
734 | * | |
735 | * Set the LSM security ID in a set of credentials so that the subjective | |
736 | * security is overridden when an alternative set of credentials is used. | |
737 | */ | |
738 | int set_security_override(struct cred *new, u32 secid) | |
739 | { | |
740 | return security_kernel_act_as(new, secid); | |
741 | } | |
742 | EXPORT_SYMBOL(set_security_override); | |
743 | ||
744 | /** | |
745 | * set_security_override_from_ctx - Set the security ID in a set of credentials | |
746 | * @new: The credentials to alter | |
747 | * @secctx: The LSM security context to generate the security ID from. | |
748 | * | |
749 | * Set the LSM security ID in a set of credentials so that the subjective | |
750 | * security is overridden when an alternative set of credentials is used. The | |
751 | * security ID is specified in string form as a security context to be | |
752 | * interpreted by the LSM. | |
753 | */ | |
754 | int set_security_override_from_ctx(struct cred *new, const char *secctx) | |
755 | { | |
756 | u32 secid; | |
757 | int ret; | |
758 | ||
759 | ret = security_secctx_to_secid(secctx, strlen(secctx), &secid); | |
760 | if (ret < 0) | |
761 | return ret; | |
762 | ||
763 | return set_security_override(new, secid); | |
764 | } | |
765 | EXPORT_SYMBOL(set_security_override_from_ctx); | |
766 | ||
767 | /** | |
768 | * set_create_files_as - Set the LSM file create context in a set of credentials | |
769 | * @new: The credentials to alter | |
770 | * @inode: The inode to take the context from | |
771 | * | |
772 | * Change the LSM file creation context in a set of credentials to be the same | |
773 | * as the object context of the specified inode, so that the new inodes have | |
774 | * the same MAC context as that inode. | |
775 | */ | |
776 | int set_create_files_as(struct cred *new, struct inode *inode) | |
777 | { | |
778 | new->fsuid = inode->i_uid; | |
779 | new->fsgid = inode->i_gid; | |
780 | return security_kernel_create_files_as(new, inode); | |
781 | } | |
782 | EXPORT_SYMBOL(set_create_files_as); | |
e0e81739 DH |
783 | |
784 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
785 | ||
74908a00 AM |
786 | bool creds_are_invalid(const struct cred *cred) |
787 | { | |
788 | if (cred->magic != CRED_MAGIC) | |
789 | return true; | |
790 | if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers)) | |
791 | return true; | |
792 | #ifdef CONFIG_SECURITY_SELINUX | |
793 | if (selinux_is_enabled()) { | |
794 | if ((unsigned long) cred->security < PAGE_SIZE) | |
795 | return true; | |
796 | if ((*(u32 *)cred->security & 0xffffff00) == | |
797 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)) | |
798 | return true; | |
799 | } | |
800 | #endif | |
801 | return false; | |
802 | } | |
764db03f | 803 | EXPORT_SYMBOL(creds_are_invalid); |
74908a00 | 804 | |
e0e81739 DH |
805 | /* |
806 | * dump invalid credentials | |
807 | */ | |
808 | static void dump_invalid_creds(const struct cred *cred, const char *label, | |
809 | const struct task_struct *tsk) | |
810 | { | |
811 | printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n", | |
812 | label, cred, | |
813 | cred == &init_cred ? "[init]" : "", | |
814 | cred == tsk->real_cred ? "[real]" : "", | |
815 | cred == tsk->cred ? "[eff]" : ""); | |
816 | printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n", | |
817 | cred->magic, cred->put_addr); | |
818 | printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n", | |
819 | atomic_read(&cred->usage), | |
820 | read_cred_subscribers(cred)); | |
821 | printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n", | |
822 | cred->uid, cred->euid, cred->suid, cred->fsuid); | |
823 | printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n", | |
824 | cred->gid, cred->egid, cred->sgid, cred->fsgid); | |
825 | #ifdef CONFIG_SECURITY | |
826 | printk(KERN_ERR "CRED: ->security is %p\n", cred->security); | |
827 | if ((unsigned long) cred->security >= PAGE_SIZE && | |
828 | (((unsigned long) cred->security & 0xffffff00) != | |
829 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))) | |
830 | printk(KERN_ERR "CRED: ->security {%x, %x}\n", | |
831 | ((u32*)cred->security)[0], | |
832 | ((u32*)cred->security)[1]); | |
833 | #endif | |
834 | } | |
835 | ||
836 | /* | |
837 | * report use of invalid credentials | |
838 | */ | |
839 | void __invalid_creds(const struct cred *cred, const char *file, unsigned line) | |
840 | { | |
841 | printk(KERN_ERR "CRED: Invalid credentials\n"); | |
842 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); | |
843 | dump_invalid_creds(cred, "Specified", current); | |
844 | BUG(); | |
845 | } | |
846 | EXPORT_SYMBOL(__invalid_creds); | |
847 | ||
848 | /* | |
849 | * check the credentials on a process | |
850 | */ | |
851 | void __validate_process_creds(struct task_struct *tsk, | |
852 | const char *file, unsigned line) | |
853 | { | |
854 | if (tsk->cred == tsk->real_cred) { | |
855 | if (unlikely(read_cred_subscribers(tsk->cred) < 2 || | |
856 | creds_are_invalid(tsk->cred))) | |
857 | goto invalid_creds; | |
858 | } else { | |
859 | if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 || | |
860 | read_cred_subscribers(tsk->cred) < 1 || | |
861 | creds_are_invalid(tsk->real_cred) || | |
862 | creds_are_invalid(tsk->cred))) | |
863 | goto invalid_creds; | |
864 | } | |
865 | return; | |
866 | ||
867 | invalid_creds: | |
868 | printk(KERN_ERR "CRED: Invalid process credentials\n"); | |
869 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); | |
870 | ||
871 | dump_invalid_creds(tsk->real_cred, "Real", tsk); | |
872 | if (tsk->cred != tsk->real_cred) | |
873 | dump_invalid_creds(tsk->cred, "Effective", tsk); | |
874 | else | |
875 | printk(KERN_ERR "CRED: Effective creds == Real creds\n"); | |
876 | BUG(); | |
877 | } | |
878 | EXPORT_SYMBOL(__validate_process_creds); | |
879 | ||
880 | /* | |
881 | * check creds for do_exit() | |
882 | */ | |
883 | void validate_creds_for_do_exit(struct task_struct *tsk) | |
884 | { | |
885 | kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})", | |
886 | tsk->real_cred, tsk->cred, | |
887 | atomic_read(&tsk->cred->usage), | |
888 | read_cred_subscribers(tsk->cred)); | |
889 | ||
890 | __validate_process_creds(tsk, __FILE__, __LINE__); | |
891 | } | |
892 | ||
893 | #endif /* CONFIG_DEBUG_CREDENTIALS */ |