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