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