Commit | Line | Data |
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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> | |
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> | |
d84f4f99 DH |
19 | #include <linux/cn_proc.h> |
20 | #include "cred-internals.h" | |
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 | |
26 | static inline __attribute__((format(printf, 1, 2))) | |
27 | void no_printk(const char *fmt, ...) | |
28 | { | |
29 | } | |
30 | #define kdebug(FMT, ...) \ | |
31 | no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__) | |
32 | #endif | |
33 | ||
d84f4f99 | 34 | static struct kmem_cache *cred_jar; |
f1752eec | 35 | |
bb952bb9 DH |
36 | /* |
37 | * The common credentials for the initial task's thread group | |
38 | */ | |
39 | #ifdef CONFIG_KEYS | |
40 | static struct thread_group_cred init_tgcred = { | |
41 | .usage = ATOMIC_INIT(2), | |
42 | .tgid = 0, | |
43 | .lock = SPIN_LOCK_UNLOCKED, | |
44 | }; | |
45 | #endif | |
46 | ||
f1752eec DH |
47 | /* |
48 | * The initial credentials for the initial task | |
49 | */ | |
50 | struct cred init_cred = { | |
3b11a1de | 51 | .usage = ATOMIC_INIT(4), |
e0e81739 DH |
52 | #ifdef CONFIG_DEBUG_CREDENTIALS |
53 | .subscribers = ATOMIC_INIT(2), | |
54 | .magic = CRED_MAGIC, | |
55 | #endif | |
f1752eec DH |
56 | .securebits = SECUREBITS_DEFAULT, |
57 | .cap_inheritable = CAP_INIT_INH_SET, | |
58 | .cap_permitted = CAP_FULL_SET, | |
59 | .cap_effective = CAP_INIT_EFF_SET, | |
60 | .cap_bset = CAP_INIT_BSET, | |
61 | .user = INIT_USER, | |
62 | .group_info = &init_groups, | |
bb952bb9 DH |
63 | #ifdef CONFIG_KEYS |
64 | .tgcred = &init_tgcred, | |
65 | #endif | |
f1752eec DH |
66 | }; |
67 | ||
e0e81739 DH |
68 | static inline void set_cred_subscribers(struct cred *cred, int n) |
69 | { | |
70 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
71 | atomic_set(&cred->subscribers, n); | |
72 | #endif | |
73 | } | |
74 | ||
75 | static inline int read_cred_subscribers(const struct cred *cred) | |
76 | { | |
77 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
78 | return atomic_read(&cred->subscribers); | |
79 | #else | |
80 | return 0; | |
81 | #endif | |
82 | } | |
83 | ||
84 | static inline void alter_cred_subscribers(const struct cred *_cred, int n) | |
85 | { | |
86 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
87 | struct cred *cred = (struct cred *) _cred; | |
88 | ||
89 | atomic_add(n, &cred->subscribers); | |
90 | #endif | |
91 | } | |
92 | ||
bb952bb9 DH |
93 | /* |
94 | * Dispose of the shared task group credentials | |
95 | */ | |
96 | #ifdef CONFIG_KEYS | |
97 | static void release_tgcred_rcu(struct rcu_head *rcu) | |
98 | { | |
99 | struct thread_group_cred *tgcred = | |
100 | container_of(rcu, struct thread_group_cred, rcu); | |
101 | ||
102 | BUG_ON(atomic_read(&tgcred->usage) != 0); | |
103 | ||
104 | key_put(tgcred->session_keyring); | |
105 | key_put(tgcred->process_keyring); | |
106 | kfree(tgcred); | |
107 | } | |
108 | #endif | |
109 | ||
110 | /* | |
111 | * Release a set of thread group credentials. | |
112 | */ | |
a6f76f23 | 113 | static void release_tgcred(struct cred *cred) |
bb952bb9 DH |
114 | { |
115 | #ifdef CONFIG_KEYS | |
116 | struct thread_group_cred *tgcred = cred->tgcred; | |
117 | ||
118 | if (atomic_dec_and_test(&tgcred->usage)) | |
119 | call_rcu(&tgcred->rcu, release_tgcred_rcu); | |
120 | #endif | |
121 | } | |
122 | ||
f1752eec DH |
123 | /* |
124 | * The RCU callback to actually dispose of a set of credentials | |
125 | */ | |
126 | static void put_cred_rcu(struct rcu_head *rcu) | |
127 | { | |
128 | struct cred *cred = container_of(rcu, struct cred, rcu); | |
129 | ||
e0e81739 DH |
130 | kdebug("put_cred_rcu(%p)", cred); |
131 | ||
132 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
133 | if (cred->magic != CRED_MAGIC_DEAD || | |
134 | atomic_read(&cred->usage) != 0 || | |
135 | read_cred_subscribers(cred) != 0) | |
136 | panic("CRED: put_cred_rcu() sees %p with" | |
137 | " mag %x, put %p, usage %d, subscr %d\n", | |
138 | cred, cred->magic, cred->put_addr, | |
139 | atomic_read(&cred->usage), | |
140 | read_cred_subscribers(cred)); | |
141 | #else | |
d84f4f99 DH |
142 | if (atomic_read(&cred->usage) != 0) |
143 | panic("CRED: put_cred_rcu() sees %p with usage %d\n", | |
144 | cred, atomic_read(&cred->usage)); | |
e0e81739 | 145 | #endif |
f1752eec | 146 | |
d84f4f99 | 147 | security_cred_free(cred); |
f1752eec DH |
148 | key_put(cred->thread_keyring); |
149 | key_put(cred->request_key_auth); | |
bb952bb9 | 150 | release_tgcred(cred); |
4a5d6ba1 DH |
151 | if (cred->group_info) |
152 | put_group_info(cred->group_info); | |
f1752eec | 153 | free_uid(cred->user); |
d84f4f99 | 154 | kmem_cache_free(cred_jar, cred); |
f1752eec DH |
155 | } |
156 | ||
157 | /** | |
158 | * __put_cred - Destroy a set of credentials | |
d84f4f99 | 159 | * @cred: The record to release |
f1752eec DH |
160 | * |
161 | * Destroy a set of credentials on which no references remain. | |
162 | */ | |
163 | void __put_cred(struct cred *cred) | |
164 | { | |
e0e81739 DH |
165 | kdebug("__put_cred(%p{%d,%d})", cred, |
166 | atomic_read(&cred->usage), | |
167 | read_cred_subscribers(cred)); | |
168 | ||
d84f4f99 | 169 | BUG_ON(atomic_read(&cred->usage) != 0); |
e0e81739 DH |
170 | #ifdef CONFIG_DEBUG_CREDENTIALS |
171 | BUG_ON(read_cred_subscribers(cred) != 0); | |
172 | cred->magic = CRED_MAGIC_DEAD; | |
173 | cred->put_addr = __builtin_return_address(0); | |
174 | #endif | |
175 | BUG_ON(cred == current->cred); | |
176 | BUG_ON(cred == current->real_cred); | |
d84f4f99 | 177 | |
f1752eec DH |
178 | call_rcu(&cred->rcu, put_cred_rcu); |
179 | } | |
180 | EXPORT_SYMBOL(__put_cred); | |
181 | ||
e0e81739 DH |
182 | /* |
183 | * Clean up a task's credentials when it exits | |
184 | */ | |
185 | void exit_creds(struct task_struct *tsk) | |
186 | { | |
187 | struct cred *cred; | |
188 | ||
189 | kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred, | |
190 | atomic_read(&tsk->cred->usage), | |
191 | read_cred_subscribers(tsk->cred)); | |
192 | ||
193 | cred = (struct cred *) tsk->real_cred; | |
194 | tsk->real_cred = NULL; | |
195 | validate_creds(cred); | |
196 | alter_cred_subscribers(cred, -1); | |
197 | put_cred(cred); | |
198 | ||
199 | cred = (struct cred *) tsk->cred; | |
200 | tsk->cred = NULL; | |
201 | validate_creds(cred); | |
202 | alter_cred_subscribers(cred, -1); | |
203 | put_cred(cred); | |
ee18d64c DH |
204 | |
205 | cred = (struct cred *) tsk->replacement_session_keyring; | |
206 | if (cred) { | |
207 | tsk->replacement_session_keyring = NULL; | |
208 | validate_creds(cred); | |
209 | put_cred(cred); | |
210 | } | |
211 | } | |
212 | ||
213 | /* | |
214 | * Allocate blank credentials, such that the credentials can be filled in at a | |
215 | * later date without risk of ENOMEM. | |
216 | */ | |
217 | struct cred *cred_alloc_blank(void) | |
218 | { | |
219 | struct cred *new; | |
220 | ||
221 | new = kmem_cache_zalloc(cred_jar, GFP_KERNEL); | |
222 | if (!new) | |
223 | return NULL; | |
224 | ||
225 | #ifdef CONFIG_KEYS | |
226 | new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL); | |
227 | if (!new->tgcred) { | |
b8a1d37c | 228 | kmem_cache_free(cred_jar, new); |
ee18d64c DH |
229 | return NULL; |
230 | } | |
231 | atomic_set(&new->tgcred->usage, 1); | |
232 | #endif | |
233 | ||
234 | atomic_set(&new->usage, 1); | |
235 | ||
236 | if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) | |
237 | goto error; | |
238 | ||
239 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
240 | new->magic = CRED_MAGIC; | |
241 | #endif | |
242 | return new; | |
243 | ||
244 | error: | |
245 | abort_creds(new); | |
246 | return NULL; | |
e0e81739 DH |
247 | } |
248 | ||
d84f4f99 DH |
249 | /** |
250 | * prepare_creds - Prepare a new set of credentials for modification | |
251 | * | |
252 | * Prepare a new set of task credentials for modification. A task's creds | |
253 | * shouldn't generally be modified directly, therefore this function is used to | |
254 | * prepare a new copy, which the caller then modifies and then commits by | |
255 | * calling commit_creds(). | |
256 | * | |
3b11a1de DH |
257 | * Preparation involves making a copy of the objective creds for modification. |
258 | * | |
d84f4f99 DH |
259 | * Returns a pointer to the new creds-to-be if successful, NULL otherwise. |
260 | * | |
261 | * Call commit_creds() or abort_creds() to clean up. | |
262 | */ | |
263 | struct cred *prepare_creds(void) | |
264 | { | |
265 | struct task_struct *task = current; | |
266 | const struct cred *old; | |
267 | struct cred *new; | |
268 | ||
e0e81739 | 269 | validate_process_creds(); |
d84f4f99 DH |
270 | |
271 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); | |
272 | if (!new) | |
273 | return NULL; | |
274 | ||
e0e81739 DH |
275 | kdebug("prepare_creds() alloc %p", new); |
276 | ||
d84f4f99 DH |
277 | old = task->cred; |
278 | memcpy(new, old, sizeof(struct cred)); | |
279 | ||
280 | atomic_set(&new->usage, 1); | |
e0e81739 | 281 | set_cred_subscribers(new, 0); |
d84f4f99 DH |
282 | get_group_info(new->group_info); |
283 | get_uid(new->user); | |
284 | ||
285 | #ifdef CONFIG_KEYS | |
286 | key_get(new->thread_keyring); | |
287 | key_get(new->request_key_auth); | |
288 | atomic_inc(&new->tgcred->usage); | |
289 | #endif | |
290 | ||
291 | #ifdef CONFIG_SECURITY | |
292 | new->security = NULL; | |
293 | #endif | |
294 | ||
295 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) | |
296 | goto error; | |
e0e81739 | 297 | validate_creds(new); |
d84f4f99 DH |
298 | return new; |
299 | ||
300 | error: | |
301 | abort_creds(new); | |
302 | return NULL; | |
303 | } | |
304 | EXPORT_SYMBOL(prepare_creds); | |
305 | ||
a6f76f23 DH |
306 | /* |
307 | * Prepare credentials for current to perform an execve() | |
5e751e99 | 308 | * - The caller must hold current->cred_guard_mutex |
a6f76f23 DH |
309 | */ |
310 | struct cred *prepare_exec_creds(void) | |
311 | { | |
312 | struct thread_group_cred *tgcred = NULL; | |
313 | struct cred *new; | |
314 | ||
315 | #ifdef CONFIG_KEYS | |
316 | tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); | |
317 | if (!tgcred) | |
318 | return NULL; | |
319 | #endif | |
320 | ||
321 | new = prepare_creds(); | |
322 | if (!new) { | |
323 | kfree(tgcred); | |
324 | return new; | |
325 | } | |
326 | ||
327 | #ifdef CONFIG_KEYS | |
328 | /* newly exec'd tasks don't get a thread keyring */ | |
329 | key_put(new->thread_keyring); | |
330 | new->thread_keyring = NULL; | |
331 | ||
332 | /* create a new per-thread-group creds for all this set of threads to | |
333 | * share */ | |
334 | memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred)); | |
335 | ||
336 | atomic_set(&tgcred->usage, 1); | |
337 | spin_lock_init(&tgcred->lock); | |
338 | ||
339 | /* inherit the session keyring; new process keyring */ | |
340 | key_get(tgcred->session_keyring); | |
341 | tgcred->process_keyring = NULL; | |
342 | ||
343 | release_tgcred(new); | |
344 | new->tgcred = tgcred; | |
345 | #endif | |
346 | ||
347 | return new; | |
348 | } | |
349 | ||
d84f4f99 DH |
350 | /* |
351 | * prepare new credentials for the usermode helper dispatcher | |
352 | */ | |
353 | struct cred *prepare_usermodehelper_creds(void) | |
354 | { | |
355 | #ifdef CONFIG_KEYS | |
356 | struct thread_group_cred *tgcred = NULL; | |
357 | #endif | |
358 | struct cred *new; | |
359 | ||
360 | #ifdef CONFIG_KEYS | |
361 | tgcred = kzalloc(sizeof(*new->tgcred), GFP_ATOMIC); | |
362 | if (!tgcred) | |
363 | return NULL; | |
364 | #endif | |
365 | ||
366 | new = kmem_cache_alloc(cred_jar, GFP_ATOMIC); | |
367 | if (!new) | |
570b8fb5 | 368 | goto free_tgcred; |
d84f4f99 | 369 | |
e0e81739 DH |
370 | kdebug("prepare_usermodehelper_creds() alloc %p", new); |
371 | ||
d84f4f99 DH |
372 | memcpy(new, &init_cred, sizeof(struct cred)); |
373 | ||
374 | atomic_set(&new->usage, 1); | |
e0e81739 | 375 | set_cred_subscribers(new, 0); |
d84f4f99 DH |
376 | get_group_info(new->group_info); |
377 | get_uid(new->user); | |
378 | ||
379 | #ifdef CONFIG_KEYS | |
380 | new->thread_keyring = NULL; | |
381 | new->request_key_auth = NULL; | |
382 | new->jit_keyring = KEY_REQKEY_DEFL_DEFAULT; | |
383 | ||
384 | atomic_set(&tgcred->usage, 1); | |
385 | spin_lock_init(&tgcred->lock); | |
386 | new->tgcred = tgcred; | |
387 | #endif | |
388 | ||
389 | #ifdef CONFIG_SECURITY | |
390 | new->security = NULL; | |
391 | #endif | |
392 | if (security_prepare_creds(new, &init_cred, GFP_ATOMIC) < 0) | |
393 | goto error; | |
e0e81739 | 394 | validate_creds(new); |
d84f4f99 DH |
395 | |
396 | BUG_ON(atomic_read(&new->usage) != 1); | |
397 | return new; | |
398 | ||
399 | error: | |
400 | put_cred(new); | |
570b8fb5 MD |
401 | free_tgcred: |
402 | #ifdef CONFIG_KEYS | |
403 | kfree(tgcred); | |
404 | #endif | |
d84f4f99 DH |
405 | return NULL; |
406 | } | |
407 | ||
f1752eec DH |
408 | /* |
409 | * Copy credentials for the new process created by fork() | |
d84f4f99 DH |
410 | * |
411 | * We share if we can, but under some circumstances we have to generate a new | |
412 | * set. | |
3b11a1de DH |
413 | * |
414 | * The new process gets the current process's subjective credentials as its | |
415 | * objective and subjective credentials | |
f1752eec DH |
416 | */ |
417 | int copy_creds(struct task_struct *p, unsigned long clone_flags) | |
418 | { | |
d84f4f99 DH |
419 | #ifdef CONFIG_KEYS |
420 | struct thread_group_cred *tgcred; | |
421 | #endif | |
422 | struct cred *new; | |
18b6e041 | 423 | int ret; |
d84f4f99 | 424 | |
5e751e99 | 425 | mutex_init(&p->cred_guard_mutex); |
f1752eec | 426 | |
d84f4f99 DH |
427 | if ( |
428 | #ifdef CONFIG_KEYS | |
429 | !p->cred->thread_keyring && | |
430 | #endif | |
431 | clone_flags & CLONE_THREAD | |
432 | ) { | |
3b11a1de | 433 | p->real_cred = get_cred(p->cred); |
d84f4f99 | 434 | get_cred(p->cred); |
e0e81739 DH |
435 | alter_cred_subscribers(p->cred, 2); |
436 | kdebug("share_creds(%p{%d,%d})", | |
437 | p->cred, atomic_read(&p->cred->usage), | |
438 | read_cred_subscribers(p->cred)); | |
d84f4f99 DH |
439 | atomic_inc(&p->cred->user->processes); |
440 | return 0; | |
441 | } | |
442 | ||
443 | new = prepare_creds(); | |
444 | if (!new) | |
f1752eec DH |
445 | return -ENOMEM; |
446 | ||
18b6e041 SH |
447 | if (clone_flags & CLONE_NEWUSER) { |
448 | ret = create_user_ns(new); | |
449 | if (ret < 0) | |
450 | goto error_put; | |
451 | } | |
452 | ||
bb952bb9 | 453 | #ifdef CONFIG_KEYS |
d84f4f99 DH |
454 | /* new threads get their own thread keyrings if their parent already |
455 | * had one */ | |
456 | if (new->thread_keyring) { | |
457 | key_put(new->thread_keyring); | |
458 | new->thread_keyring = NULL; | |
459 | if (clone_flags & CLONE_THREAD) | |
460 | install_thread_keyring_to_cred(new); | |
461 | } | |
462 | ||
463 | /* we share the process and session keyrings between all the threads in | |
464 | * a process - this is slightly icky as we violate COW credentials a | |
465 | * bit */ | |
466 | if (!(clone_flags & CLONE_THREAD)) { | |
467 | tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL); | |
468 | if (!tgcred) { | |
18b6e041 SH |
469 | ret = -ENOMEM; |
470 | goto error_put; | |
bb952bb9 | 471 | } |
d84f4f99 DH |
472 | atomic_set(&tgcred->usage, 1); |
473 | spin_lock_init(&tgcred->lock); | |
474 | tgcred->process_keyring = NULL; | |
475 | tgcred->session_keyring = key_get(new->tgcred->session_keyring); | |
476 | ||
477 | release_tgcred(new); | |
478 | new->tgcred = tgcred; | |
bb952bb9 DH |
479 | } |
480 | #endif | |
481 | ||
d84f4f99 | 482 | atomic_inc(&new->user->processes); |
3b11a1de | 483 | p->cred = p->real_cred = get_cred(new); |
e0e81739 DH |
484 | alter_cred_subscribers(new, 2); |
485 | validate_creds(new); | |
d84f4f99 | 486 | return 0; |
18b6e041 SH |
487 | |
488 | error_put: | |
489 | put_cred(new); | |
490 | return ret; | |
d84f4f99 | 491 | } |
f1752eec | 492 | |
d84f4f99 DH |
493 | /** |
494 | * commit_creds - Install new credentials upon the current task | |
495 | * @new: The credentials to be assigned | |
496 | * | |
497 | * Install a new set of credentials to the current task, using RCU to replace | |
3b11a1de DH |
498 | * the old set. Both the objective and the subjective credentials pointers are |
499 | * updated. This function may not be called if the subjective credentials are | |
500 | * in an overridden state. | |
d84f4f99 DH |
501 | * |
502 | * This function eats the caller's reference to the new credentials. | |
503 | * | |
504 | * Always returns 0 thus allowing this function to be tail-called at the end | |
505 | * of, say, sys_setgid(). | |
506 | */ | |
507 | int commit_creds(struct cred *new) | |
508 | { | |
509 | struct task_struct *task = current; | |
e0e81739 | 510 | const struct cred *old = task->real_cred; |
d84f4f99 | 511 | |
e0e81739 DH |
512 | kdebug("commit_creds(%p{%d,%d})", new, |
513 | atomic_read(&new->usage), | |
514 | read_cred_subscribers(new)); | |
515 | ||
516 | BUG_ON(task->cred != old); | |
517 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
518 | BUG_ON(read_cred_subscribers(old) < 2); | |
519 | validate_creds(old); | |
520 | validate_creds(new); | |
521 | #endif | |
d84f4f99 | 522 | BUG_ON(atomic_read(&new->usage) < 1); |
d84f4f99 | 523 | |
d84f4f99 DH |
524 | security_commit_creds(new, old); |
525 | ||
3b11a1de DH |
526 | get_cred(new); /* we will require a ref for the subj creds too */ |
527 | ||
d84f4f99 DH |
528 | /* dumpability changes */ |
529 | if (old->euid != new->euid || | |
530 | old->egid != new->egid || | |
531 | old->fsuid != new->fsuid || | |
532 | old->fsgid != new->fsgid || | |
533 | !cap_issubset(new->cap_permitted, old->cap_permitted)) { | |
b9456371 DH |
534 | if (task->mm) |
535 | set_dumpable(task->mm, suid_dumpable); | |
d84f4f99 DH |
536 | task->pdeath_signal = 0; |
537 | smp_wmb(); | |
f1752eec DH |
538 | } |
539 | ||
d84f4f99 DH |
540 | /* alter the thread keyring */ |
541 | if (new->fsuid != old->fsuid) | |
542 | key_fsuid_changed(task); | |
543 | if (new->fsgid != old->fsgid) | |
544 | key_fsgid_changed(task); | |
545 | ||
546 | /* do it | |
547 | * - What if a process setreuid()'s and this brings the | |
548 | * new uid over his NPROC rlimit? We can check this now | |
549 | * cheaply with the new uid cache, so if it matters | |
550 | * we should be checking for it. -DaveM | |
551 | */ | |
e0e81739 | 552 | alter_cred_subscribers(new, 2); |
d84f4f99 DH |
553 | if (new->user != old->user) |
554 | atomic_inc(&new->user->processes); | |
3b11a1de | 555 | rcu_assign_pointer(task->real_cred, new); |
d84f4f99 DH |
556 | rcu_assign_pointer(task->cred, new); |
557 | if (new->user != old->user) | |
558 | atomic_dec(&old->user->processes); | |
e0e81739 | 559 | alter_cred_subscribers(old, -2); |
d84f4f99 DH |
560 | |
561 | sched_switch_user(task); | |
562 | ||
563 | /* send notifications */ | |
564 | if (new->uid != old->uid || | |
565 | new->euid != old->euid || | |
566 | new->suid != old->suid || | |
567 | new->fsuid != old->fsuid) | |
568 | proc_id_connector(task, PROC_EVENT_UID); | |
f1752eec | 569 | |
d84f4f99 DH |
570 | if (new->gid != old->gid || |
571 | new->egid != old->egid || | |
572 | new->sgid != old->sgid || | |
573 | new->fsgid != old->fsgid) | |
574 | proc_id_connector(task, PROC_EVENT_GID); | |
f1752eec | 575 | |
3b11a1de DH |
576 | /* release the old obj and subj refs both */ |
577 | put_cred(old); | |
d84f4f99 | 578 | put_cred(old); |
f1752eec DH |
579 | return 0; |
580 | } | |
d84f4f99 DH |
581 | EXPORT_SYMBOL(commit_creds); |
582 | ||
583 | /** | |
584 | * abort_creds - Discard a set of credentials and unlock the current task | |
585 | * @new: The credentials that were going to be applied | |
586 | * | |
587 | * Discard a set of credentials that were under construction and unlock the | |
588 | * current task. | |
589 | */ | |
590 | void abort_creds(struct cred *new) | |
591 | { | |
e0e81739 DH |
592 | kdebug("abort_creds(%p{%d,%d})", new, |
593 | atomic_read(&new->usage), | |
594 | read_cred_subscribers(new)); | |
595 | ||
596 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
597 | BUG_ON(read_cred_subscribers(new) != 0); | |
598 | #endif | |
d84f4f99 DH |
599 | BUG_ON(atomic_read(&new->usage) < 1); |
600 | put_cred(new); | |
601 | } | |
602 | EXPORT_SYMBOL(abort_creds); | |
603 | ||
604 | /** | |
3b11a1de | 605 | * override_creds - Override the current process's subjective credentials |
d84f4f99 DH |
606 | * @new: The credentials to be assigned |
607 | * | |
3b11a1de DH |
608 | * Install a set of temporary override subjective credentials on the current |
609 | * process, returning the old set for later reversion. | |
d84f4f99 DH |
610 | */ |
611 | const struct cred *override_creds(const struct cred *new) | |
612 | { | |
613 | const struct cred *old = current->cred; | |
614 | ||
e0e81739 DH |
615 | kdebug("override_creds(%p{%d,%d})", new, |
616 | atomic_read(&new->usage), | |
617 | read_cred_subscribers(new)); | |
618 | ||
619 | validate_creds(old); | |
620 | validate_creds(new); | |
621 | get_cred(new); | |
622 | alter_cred_subscribers(new, 1); | |
623 | rcu_assign_pointer(current->cred, new); | |
624 | alter_cred_subscribers(old, -1); | |
625 | ||
626 | kdebug("override_creds() = %p{%d,%d}", old, | |
627 | atomic_read(&old->usage), | |
628 | read_cred_subscribers(old)); | |
d84f4f99 DH |
629 | return old; |
630 | } | |
631 | EXPORT_SYMBOL(override_creds); | |
632 | ||
633 | /** | |
3b11a1de | 634 | * revert_creds - Revert a temporary subjective credentials override |
d84f4f99 DH |
635 | * @old: The credentials to be restored |
636 | * | |
3b11a1de DH |
637 | * Revert a temporary set of override subjective credentials to an old set, |
638 | * discarding the override set. | |
d84f4f99 DH |
639 | */ |
640 | void revert_creds(const struct cred *old) | |
641 | { | |
642 | const struct cred *override = current->cred; | |
643 | ||
e0e81739 DH |
644 | kdebug("revert_creds(%p{%d,%d})", old, |
645 | atomic_read(&old->usage), | |
646 | read_cred_subscribers(old)); | |
647 | ||
648 | validate_creds(old); | |
649 | validate_creds(override); | |
650 | alter_cred_subscribers(old, 1); | |
d84f4f99 | 651 | rcu_assign_pointer(current->cred, old); |
e0e81739 | 652 | alter_cred_subscribers(override, -1); |
d84f4f99 DH |
653 | put_cred(override); |
654 | } | |
655 | EXPORT_SYMBOL(revert_creds); | |
656 | ||
657 | /* | |
658 | * initialise the credentials stuff | |
659 | */ | |
660 | void __init cred_init(void) | |
661 | { | |
662 | /* allocate a slab in which we can store credentials */ | |
663 | cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), | |
664 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
665 | } | |
3a3b7ce9 DH |
666 | |
667 | /** | |
668 | * prepare_kernel_cred - Prepare a set of credentials for a kernel service | |
669 | * @daemon: A userspace daemon to be used as a reference | |
670 | * | |
671 | * Prepare a set of credentials for a kernel service. This can then be used to | |
672 | * override a task's own credentials so that work can be done on behalf of that | |
673 | * task that requires a different subjective context. | |
674 | * | |
675 | * @daemon is used to provide a base for the security record, but can be NULL. | |
676 | * If @daemon is supplied, then the security data will be derived from that; | |
677 | * otherwise they'll be set to 0 and no groups, full capabilities and no keys. | |
678 | * | |
679 | * The caller may change these controls afterwards if desired. | |
680 | * | |
681 | * Returns the new credentials or NULL if out of memory. | |
682 | * | |
683 | * Does not take, and does not return holding current->cred_replace_mutex. | |
684 | */ | |
685 | struct cred *prepare_kernel_cred(struct task_struct *daemon) | |
686 | { | |
687 | const struct cred *old; | |
688 | struct cred *new; | |
689 | ||
690 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); | |
691 | if (!new) | |
692 | return NULL; | |
693 | ||
e0e81739 DH |
694 | kdebug("prepare_kernel_cred() alloc %p", new); |
695 | ||
3a3b7ce9 DH |
696 | if (daemon) |
697 | old = get_task_cred(daemon); | |
698 | else | |
699 | old = get_cred(&init_cred); | |
700 | ||
e0e81739 DH |
701 | validate_creds(old); |
702 | ||
43529c97 | 703 | *new = *old; |
3a3b7ce9 DH |
704 | get_uid(new->user); |
705 | get_group_info(new->group_info); | |
706 | ||
707 | #ifdef CONFIG_KEYS | |
708 | atomic_inc(&init_tgcred.usage); | |
709 | new->tgcred = &init_tgcred; | |
710 | new->request_key_auth = NULL; | |
711 | new->thread_keyring = NULL; | |
712 | new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; | |
713 | #endif | |
714 | ||
715 | #ifdef CONFIG_SECURITY | |
716 | new->security = NULL; | |
717 | #endif | |
718 | if (security_prepare_creds(new, old, GFP_KERNEL) < 0) | |
719 | goto error; | |
720 | ||
721 | atomic_set(&new->usage, 1); | |
e0e81739 | 722 | set_cred_subscribers(new, 0); |
3a3b7ce9 | 723 | put_cred(old); |
e0e81739 | 724 | validate_creds(new); |
3a3b7ce9 DH |
725 | return new; |
726 | ||
727 | error: | |
728 | put_cred(new); | |
0de33681 | 729 | put_cred(old); |
3a3b7ce9 DH |
730 | return NULL; |
731 | } | |
732 | EXPORT_SYMBOL(prepare_kernel_cred); | |
733 | ||
734 | /** | |
735 | * set_security_override - Set the security ID in a set of credentials | |
736 | * @new: The credentials to alter | |
737 | * @secid: The LSM security ID to set | |
738 | * | |
739 | * Set the LSM security ID in a set of credentials so that the subjective | |
740 | * security is overridden when an alternative set of credentials is used. | |
741 | */ | |
742 | int set_security_override(struct cred *new, u32 secid) | |
743 | { | |
744 | return security_kernel_act_as(new, secid); | |
745 | } | |
746 | EXPORT_SYMBOL(set_security_override); | |
747 | ||
748 | /** | |
749 | * set_security_override_from_ctx - Set the security ID in a set of credentials | |
750 | * @new: The credentials to alter | |
751 | * @secctx: The LSM security context to generate the security ID from. | |
752 | * | |
753 | * Set the LSM security ID in a set of credentials so that the subjective | |
754 | * security is overridden when an alternative set of credentials is used. The | |
755 | * security ID is specified in string form as a security context to be | |
756 | * interpreted by the LSM. | |
757 | */ | |
758 | int set_security_override_from_ctx(struct cred *new, const char *secctx) | |
759 | { | |
760 | u32 secid; | |
761 | int ret; | |
762 | ||
763 | ret = security_secctx_to_secid(secctx, strlen(secctx), &secid); | |
764 | if (ret < 0) | |
765 | return ret; | |
766 | ||
767 | return set_security_override(new, secid); | |
768 | } | |
769 | EXPORT_SYMBOL(set_security_override_from_ctx); | |
770 | ||
771 | /** | |
772 | * set_create_files_as - Set the LSM file create context in a set of credentials | |
773 | * @new: The credentials to alter | |
774 | * @inode: The inode to take the context from | |
775 | * | |
776 | * Change the LSM file creation context in a set of credentials to be the same | |
777 | * as the object context of the specified inode, so that the new inodes have | |
778 | * the same MAC context as that inode. | |
779 | */ | |
780 | int set_create_files_as(struct cred *new, struct inode *inode) | |
781 | { | |
782 | new->fsuid = inode->i_uid; | |
783 | new->fsgid = inode->i_gid; | |
784 | return security_kernel_create_files_as(new, inode); | |
785 | } | |
786 | EXPORT_SYMBOL(set_create_files_as); | |
e0e81739 DH |
787 | |
788 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
789 | ||
74908a00 AM |
790 | bool creds_are_invalid(const struct cred *cred) |
791 | { | |
792 | if (cred->magic != CRED_MAGIC) | |
793 | return true; | |
794 | if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers)) | |
795 | return true; | |
796 | #ifdef CONFIG_SECURITY_SELINUX | |
797 | if (selinux_is_enabled()) { | |
798 | if ((unsigned long) cred->security < PAGE_SIZE) | |
799 | return true; | |
800 | if ((*(u32 *)cred->security & 0xffffff00) == | |
801 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)) | |
802 | return true; | |
803 | } | |
804 | #endif | |
805 | return false; | |
806 | } | |
764db03f | 807 | EXPORT_SYMBOL(creds_are_invalid); |
74908a00 | 808 | |
e0e81739 DH |
809 | /* |
810 | * dump invalid credentials | |
811 | */ | |
812 | static void dump_invalid_creds(const struct cred *cred, const char *label, | |
813 | const struct task_struct *tsk) | |
814 | { | |
815 | printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n", | |
816 | label, cred, | |
817 | cred == &init_cred ? "[init]" : "", | |
818 | cred == tsk->real_cred ? "[real]" : "", | |
819 | cred == tsk->cred ? "[eff]" : ""); | |
820 | printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n", | |
821 | cred->magic, cred->put_addr); | |
822 | printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n", | |
823 | atomic_read(&cred->usage), | |
824 | read_cred_subscribers(cred)); | |
825 | printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n", | |
826 | cred->uid, cred->euid, cred->suid, cred->fsuid); | |
827 | printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n", | |
828 | cred->gid, cred->egid, cred->sgid, cred->fsgid); | |
829 | #ifdef CONFIG_SECURITY | |
830 | printk(KERN_ERR "CRED: ->security is %p\n", cred->security); | |
831 | if ((unsigned long) cred->security >= PAGE_SIZE && | |
832 | (((unsigned long) cred->security & 0xffffff00) != | |
833 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))) | |
834 | printk(KERN_ERR "CRED: ->security {%x, %x}\n", | |
835 | ((u32*)cred->security)[0], | |
836 | ((u32*)cred->security)[1]); | |
837 | #endif | |
838 | } | |
839 | ||
840 | /* | |
841 | * report use of invalid credentials | |
842 | */ | |
843 | void __invalid_creds(const struct cred *cred, const char *file, unsigned line) | |
844 | { | |
845 | printk(KERN_ERR "CRED: Invalid credentials\n"); | |
846 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); | |
847 | dump_invalid_creds(cred, "Specified", current); | |
848 | BUG(); | |
849 | } | |
850 | EXPORT_SYMBOL(__invalid_creds); | |
851 | ||
852 | /* | |
853 | * check the credentials on a process | |
854 | */ | |
855 | void __validate_process_creds(struct task_struct *tsk, | |
856 | const char *file, unsigned line) | |
857 | { | |
858 | if (tsk->cred == tsk->real_cred) { | |
859 | if (unlikely(read_cred_subscribers(tsk->cred) < 2 || | |
860 | creds_are_invalid(tsk->cred))) | |
861 | goto invalid_creds; | |
862 | } else { | |
863 | if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 || | |
864 | read_cred_subscribers(tsk->cred) < 1 || | |
865 | creds_are_invalid(tsk->real_cred) || | |
866 | creds_are_invalid(tsk->cred))) | |
867 | goto invalid_creds; | |
868 | } | |
869 | return; | |
870 | ||
871 | invalid_creds: | |
872 | printk(KERN_ERR "CRED: Invalid process credentials\n"); | |
873 | printk(KERN_ERR "CRED: At %s:%u\n", file, line); | |
874 | ||
875 | dump_invalid_creds(tsk->real_cred, "Real", tsk); | |
876 | if (tsk->cred != tsk->real_cred) | |
877 | dump_invalid_creds(tsk->cred, "Effective", tsk); | |
878 | else | |
879 | printk(KERN_ERR "CRED: Effective creds == Real creds\n"); | |
880 | BUG(); | |
881 | } | |
882 | EXPORT_SYMBOL(__validate_process_creds); | |
883 | ||
884 | /* | |
885 | * check creds for do_exit() | |
886 | */ | |
887 | void validate_creds_for_do_exit(struct task_struct *tsk) | |
888 | { | |
889 | kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})", | |
890 | tsk->real_cred, tsk->cred, | |
891 | atomic_read(&tsk->cred->usage), | |
892 | read_cred_subscribers(tsk->cred)); | |
893 | ||
894 | __validate_process_creds(tsk, __FILE__, __LINE__); | |
895 | } | |
896 | ||
897 | #endif /* CONFIG_DEBUG_CREDENTIALS */ |