Commit | Line | Data |
---|---|---|
b4d0d230 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
af777cd1 | 2 | /* Task credentials management - see Documentation/security/credentials.rst |
f1752eec DH |
3 | * |
4 | * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
f1752eec | 6 | */ |
4099451a | 7 | |
8 | #define pr_fmt(fmt) "CRED: " fmt | |
9 | ||
9984de1a | 10 | #include <linux/export.h> |
f1752eec | 11 | #include <linux/cred.h> |
5a0e3ad6 | 12 | #include <linux/slab.h> |
f1752eec | 13 | #include <linux/sched.h> |
f7ccbae4 | 14 | #include <linux/sched/coredump.h> |
f1752eec DH |
15 | #include <linux/key.h> |
16 | #include <linux/keyctl.h> | |
17 | #include <linux/init_task.h> | |
18 | #include <linux/security.h> | |
40401530 | 19 | #include <linux/binfmts.h> |
d84f4f99 | 20 | #include <linux/cn_proc.h> |
d89b22d4 | 21 | #include <linux/uidgid.h> |
d84f4f99 | 22 | |
e0e81739 | 23 | #if 0 |
52aa8536 JP |
24 | #define kdebug(FMT, ...) \ |
25 | printk("[%-5.5s%5u] " FMT "\n", \ | |
26 | current->comm, current->pid, ##__VA_ARGS__) | |
e0e81739 | 27 | #else |
52aa8536 JP |
28 | #define kdebug(FMT, ...) \ |
29 | do { \ | |
30 | if (0) \ | |
31 | no_printk("[%-5.5s%5u] " FMT "\n", \ | |
32 | current->comm, current->pid, ##__VA_ARGS__); \ | |
33 | } while (0) | |
e0e81739 DH |
34 | #endif |
35 | ||
d84f4f99 | 36 | static struct kmem_cache *cred_jar; |
f1752eec | 37 | |
2813893f | 38 | /* init to 2 - one for init_task, one to ensure it is never freed */ |
32c93976 | 39 | static struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; |
2813893f | 40 | |
f1752eec DH |
41 | /* |
42 | * The initial credentials for the initial task | |
43 | */ | |
44 | struct cred init_cred = { | |
3b11a1de | 45 | .usage = ATOMIC_INIT(4), |
e0e81739 DH |
46 | #ifdef CONFIG_DEBUG_CREDENTIALS |
47 | .subscribers = ATOMIC_INIT(2), | |
48 | .magic = CRED_MAGIC, | |
49 | #endif | |
078de5f7 EB |
50 | .uid = GLOBAL_ROOT_UID, |
51 | .gid = GLOBAL_ROOT_GID, | |
52 | .suid = GLOBAL_ROOT_UID, | |
53 | .sgid = GLOBAL_ROOT_GID, | |
54 | .euid = GLOBAL_ROOT_UID, | |
55 | .egid = GLOBAL_ROOT_GID, | |
56 | .fsuid = GLOBAL_ROOT_UID, | |
57 | .fsgid = GLOBAL_ROOT_GID, | |
f1752eec | 58 | .securebits = SECUREBITS_DEFAULT, |
a3232d2f | 59 | .cap_inheritable = CAP_EMPTY_SET, |
f1752eec | 60 | .cap_permitted = CAP_FULL_SET, |
a3232d2f EP |
61 | .cap_effective = CAP_FULL_SET, |
62 | .cap_bset = CAP_FULL_SET, | |
f1752eec | 63 | .user = INIT_USER, |
47a150ed | 64 | .user_ns = &init_user_ns, |
f1752eec | 65 | .group_info = &init_groups, |
905ae01c | 66 | .ucounts = &init_ucounts, |
f1752eec DH |
67 | }; |
68 | ||
e0e81739 DH |
69 | static inline void set_cred_subscribers(struct cred *cred, int n) |
70 | { | |
71 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
72 | atomic_set(&cred->subscribers, n); | |
73 | #endif | |
74 | } | |
75 | ||
76 | static inline int read_cred_subscribers(const struct cred *cred) | |
77 | { | |
78 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
79 | return atomic_read(&cred->subscribers); | |
80 | #else | |
81 | return 0; | |
82 | #endif | |
83 | } | |
84 | ||
85 | static inline void alter_cred_subscribers(const struct cred *_cred, int n) | |
86 | { | |
87 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
88 | struct cred *cred = (struct cred *) _cred; | |
89 | ||
90 | atomic_add(n, &cred->subscribers); | |
91 | #endif | |
92 | } | |
93 | ||
f1752eec DH |
94 | /* |
95 | * The RCU callback to actually dispose of a set of credentials | |
96 | */ | |
97 | static void put_cred_rcu(struct rcu_head *rcu) | |
98 | { | |
99 | struct cred *cred = container_of(rcu, struct cred, rcu); | |
100 | ||
e0e81739 DH |
101 | kdebug("put_cred_rcu(%p)", cred); |
102 | ||
103 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
104 | if (cred->magic != CRED_MAGIC_DEAD || | |
105 | atomic_read(&cred->usage) != 0 || | |
106 | read_cred_subscribers(cred) != 0) | |
107 | panic("CRED: put_cred_rcu() sees %p with" | |
108 | " mag %x, put %p, usage %d, subscr %d\n", | |
109 | cred, cred->magic, cred->put_addr, | |
110 | atomic_read(&cred->usage), | |
111 | read_cred_subscribers(cred)); | |
112 | #else | |
d84f4f99 DH |
113 | if (atomic_read(&cred->usage) != 0) |
114 | panic("CRED: put_cred_rcu() sees %p with usage %d\n", | |
115 | cred, atomic_read(&cred->usage)); | |
e0e81739 | 116 | #endif |
f1752eec | 117 | |
d84f4f99 | 118 | security_cred_free(cred); |
3a50597d DH |
119 | key_put(cred->session_keyring); |
120 | key_put(cred->process_keyring); | |
f1752eec DH |
121 | key_put(cred->thread_keyring); |
122 | key_put(cred->request_key_auth); | |
4a5d6ba1 DH |
123 | if (cred->group_info) |
124 | put_group_info(cred->group_info); | |
f1752eec | 125 | free_uid(cred->user); |
905ae01c AG |
126 | if (cred->ucounts) |
127 | put_ucounts(cred->ucounts); | |
0093ccb6 | 128 | put_user_ns(cred->user_ns); |
d84f4f99 | 129 | kmem_cache_free(cred_jar, cred); |
f1752eec DH |
130 | } |
131 | ||
132 | /** | |
133 | * __put_cred - Destroy a set of credentials | |
d84f4f99 | 134 | * @cred: The record to release |
f1752eec DH |
135 | * |
136 | * Destroy a set of credentials on which no references remain. | |
137 | */ | |
138 | void __put_cred(struct cred *cred) | |
139 | { | |
e0e81739 DH |
140 | kdebug("__put_cred(%p{%d,%d})", cred, |
141 | atomic_read(&cred->usage), | |
142 | read_cred_subscribers(cred)); | |
143 | ||
d84f4f99 | 144 | BUG_ON(atomic_read(&cred->usage) != 0); |
e0e81739 DH |
145 | #ifdef CONFIG_DEBUG_CREDENTIALS |
146 | BUG_ON(read_cred_subscribers(cred) != 0); | |
147 | cred->magic = CRED_MAGIC_DEAD; | |
148 | cred->put_addr = __builtin_return_address(0); | |
149 | #endif | |
150 | BUG_ON(cred == current->cred); | |
151 | BUG_ON(cred == current->real_cred); | |
d84f4f99 | 152 | |
d7852fbd LT |
153 | if (cred->non_rcu) |
154 | put_cred_rcu(&cred->rcu); | |
155 | else | |
156 | call_rcu(&cred->rcu, put_cred_rcu); | |
f1752eec DH |
157 | } |
158 | EXPORT_SYMBOL(__put_cred); | |
159 | ||
e0e81739 DH |
160 | /* |
161 | * Clean up a task's credentials when it exits | |
162 | */ | |
163 | void exit_creds(struct task_struct *tsk) | |
164 | { | |
165 | struct cred *cred; | |
166 | ||
167 | kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred, | |
168 | atomic_read(&tsk->cred->usage), | |
169 | read_cred_subscribers(tsk->cred)); | |
170 | ||
171 | cred = (struct cred *) tsk->real_cred; | |
172 | tsk->real_cred = NULL; | |
173 | validate_creds(cred); | |
174 | alter_cred_subscribers(cred, -1); | |
175 | put_cred(cred); | |
176 | ||
177 | cred = (struct cred *) tsk->cred; | |
178 | tsk->cred = NULL; | |
179 | validate_creds(cred); | |
180 | alter_cred_subscribers(cred, -1); | |
181 | put_cred(cred); | |
7743c48e DH |
182 | |
183 | #ifdef CONFIG_KEYS_REQUEST_CACHE | |
8379bb84 DH |
184 | key_put(tsk->cached_requested_key); |
185 | tsk->cached_requested_key = NULL; | |
7743c48e | 186 | #endif |
ee18d64c DH |
187 | } |
188 | ||
de09a977 DH |
189 | /** |
190 | * get_task_cred - Get another task's objective credentials | |
191 | * @task: The task to query | |
192 | * | |
193 | * Get the objective credentials of a task, pinning them so that they can't go | |
194 | * away. Accessing a task's credentials directly is not permitted. | |
195 | * | |
196 | * The caller must also make sure task doesn't get deleted, either by holding a | |
197 | * ref on task or by holding tasklist_lock to prevent it from being unlinked. | |
198 | */ | |
199 | const struct cred *get_task_cred(struct task_struct *task) | |
200 | { | |
201 | const struct cred *cred; | |
202 | ||
203 | rcu_read_lock(); | |
204 | ||
205 | do { | |
206 | cred = __task_cred((task)); | |
207 | BUG_ON(!cred); | |
97d0fb23 | 208 | } while (!get_cred_rcu(cred)); |
de09a977 DH |
209 | |
210 | rcu_read_unlock(); | |
211 | return cred; | |
212 | } | |
a6d8e763 | 213 | EXPORT_SYMBOL(get_task_cred); |
de09a977 | 214 | |
ee18d64c DH |
215 | /* |
216 | * Allocate blank credentials, such that the credentials can be filled in at a | |
217 | * later date without risk of ENOMEM. | |
218 | */ | |
219 | struct cred *cred_alloc_blank(void) | |
220 | { | |
221 | struct cred *new; | |
222 | ||
223 | new = kmem_cache_zalloc(cred_jar, GFP_KERNEL); | |
224 | if (!new) | |
225 | return NULL; | |
226 | ||
ee18d64c | 227 | atomic_set(&new->usage, 1); |
2edeaa34 TH |
228 | #ifdef CONFIG_DEBUG_CREDENTIALS |
229 | new->magic = CRED_MAGIC; | |
230 | #endif | |
84029fd0 | 231 | if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0) |
ee18d64c DH |
232 | goto error; |
233 | ||
ee18d64c DH |
234 | return new; |
235 | ||
236 | error: | |
237 | abort_creds(new); | |
238 | return NULL; | |
e0e81739 DH |
239 | } |
240 | ||
d84f4f99 DH |
241 | /** |
242 | * prepare_creds - Prepare a new set of credentials for modification | |
243 | * | |
244 | * Prepare a new set of task credentials for modification. A task's creds | |
245 | * shouldn't generally be modified directly, therefore this function is used to | |
246 | * prepare a new copy, which the caller then modifies and then commits by | |
247 | * calling commit_creds(). | |
248 | * | |
3b11a1de DH |
249 | * Preparation involves making a copy of the objective creds for modification. |
250 | * | |
d84f4f99 DH |
251 | * Returns a pointer to the new creds-to-be if successful, NULL otherwise. |
252 | * | |
253 | * Call commit_creds() or abort_creds() to clean up. | |
254 | */ | |
255 | struct cred *prepare_creds(void) | |
256 | { | |
257 | struct task_struct *task = current; | |
258 | const struct cred *old; | |
259 | struct cred *new; | |
260 | ||
e0e81739 | 261 | validate_process_creds(); |
d84f4f99 DH |
262 | |
263 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); | |
264 | if (!new) | |
265 | return NULL; | |
266 | ||
e0e81739 DH |
267 | kdebug("prepare_creds() alloc %p", new); |
268 | ||
d84f4f99 DH |
269 | old = task->cred; |
270 | memcpy(new, old, sizeof(struct cred)); | |
271 | ||
d7852fbd | 272 | new->non_rcu = 0; |
d84f4f99 | 273 | atomic_set(&new->usage, 1); |
e0e81739 | 274 | set_cred_subscribers(new, 0); |
d84f4f99 DH |
275 | get_group_info(new->group_info); |
276 | get_uid(new->user); | |
0093ccb6 | 277 | get_user_ns(new->user_ns); |
d84f4f99 DH |
278 | |
279 | #ifdef CONFIG_KEYS | |
3a50597d DH |
280 | key_get(new->session_keyring); |
281 | key_get(new->process_keyring); | |
d84f4f99 DH |
282 | key_get(new->thread_keyring); |
283 | key_get(new->request_key_auth); | |
d84f4f99 DH |
284 | #endif |
285 | ||
286 | #ifdef CONFIG_SECURITY | |
287 | new->security = NULL; | |
288 | #endif | |
289 | ||
905ae01c AG |
290 | new->ucounts = get_ucounts(new->ucounts); |
291 | if (!new->ucounts) | |
292 | goto error; | |
293 | ||
bbb6d0f3 AG |
294 | if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0) |
295 | goto error; | |
296 | ||
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() | |
9b1bf12d | 308 | * - The caller must hold ->cred_guard_mutex |
a6f76f23 DH |
309 | */ |
310 | struct cred *prepare_exec_creds(void) | |
311 | { | |
a6f76f23 DH |
312 | struct cred *new; |
313 | ||
a6f76f23 | 314 | new = prepare_creds(); |
3a50597d | 315 | if (!new) |
a6f76f23 | 316 | return new; |
a6f76f23 DH |
317 | |
318 | #ifdef CONFIG_KEYS | |
319 | /* newly exec'd tasks don't get a thread keyring */ | |
320 | key_put(new->thread_keyring); | |
321 | new->thread_keyring = NULL; | |
322 | ||
a6f76f23 | 323 | /* inherit the session keyring; new process keyring */ |
3a50597d DH |
324 | key_put(new->process_keyring); |
325 | new->process_keyring = NULL; | |
a6f76f23 DH |
326 | #endif |
327 | ||
87b047d2 EB |
328 | new->suid = new->fsuid = new->euid; |
329 | new->sgid = new->fsgid = new->egid; | |
330 | ||
a6f76f23 DH |
331 | return new; |
332 | } | |
333 | ||
f1752eec DH |
334 | /* |
335 | * Copy credentials for the new process created by fork() | |
d84f4f99 DH |
336 | * |
337 | * We share if we can, but under some circumstances we have to generate a new | |
338 | * set. | |
3b11a1de DH |
339 | * |
340 | * The new process gets the current process's subjective credentials as its | |
341 | * objective and subjective credentials | |
f1752eec DH |
342 | */ |
343 | int copy_creds(struct task_struct *p, unsigned long clone_flags) | |
344 | { | |
d84f4f99 | 345 | struct cred *new; |
18b6e041 | 346 | int ret; |
d84f4f99 | 347 | |
7743c48e DH |
348 | #ifdef CONFIG_KEYS_REQUEST_CACHE |
349 | p->cached_requested_key = NULL; | |
350 | #endif | |
351 | ||
d84f4f99 DH |
352 | if ( |
353 | #ifdef CONFIG_KEYS | |
354 | !p->cred->thread_keyring && | |
355 | #endif | |
356 | clone_flags & CLONE_THREAD | |
357 | ) { | |
3b11a1de | 358 | p->real_cred = get_cred(p->cred); |
d84f4f99 | 359 | get_cred(p->cred); |
e0e81739 DH |
360 | alter_cred_subscribers(p->cred, 2); |
361 | kdebug("share_creds(%p{%d,%d})", | |
362 | p->cred, atomic_read(&p->cred->usage), | |
363 | read_cred_subscribers(p->cred)); | |
21d1c5e3 | 364 | inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
d84f4f99 DH |
365 | return 0; |
366 | } | |
367 | ||
368 | new = prepare_creds(); | |
369 | if (!new) | |
f1752eec DH |
370 | return -ENOMEM; |
371 | ||
18b6e041 SH |
372 | if (clone_flags & CLONE_NEWUSER) { |
373 | ret = create_user_ns(new); | |
374 | if (ret < 0) | |
375 | goto error_put; | |
5e6b8a50 YY |
376 | ret = set_cred_ucounts(new); |
377 | if (ret < 0) | |
905ae01c | 378 | goto error_put; |
18b6e041 SH |
379 | } |
380 | ||
bb952bb9 | 381 | #ifdef CONFIG_KEYS |
d84f4f99 DH |
382 | /* new threads get their own thread keyrings if their parent already |
383 | * had one */ | |
384 | if (new->thread_keyring) { | |
385 | key_put(new->thread_keyring); | |
386 | new->thread_keyring = NULL; | |
387 | if (clone_flags & CLONE_THREAD) | |
388 | install_thread_keyring_to_cred(new); | |
389 | } | |
390 | ||
3a50597d DH |
391 | /* The process keyring is only shared between the threads in a process; |
392 | * anything outside of those threads doesn't inherit. | |
393 | */ | |
d84f4f99 | 394 | if (!(clone_flags & CLONE_THREAD)) { |
3a50597d DH |
395 | key_put(new->process_keyring); |
396 | new->process_keyring = NULL; | |
bb952bb9 DH |
397 | } |
398 | #endif | |
399 | ||
3b11a1de | 400 | p->cred = p->real_cred = get_cred(new); |
21d1c5e3 | 401 | inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
e0e81739 DH |
402 | alter_cred_subscribers(new, 2); |
403 | validate_creds(new); | |
d84f4f99 | 404 | return 0; |
18b6e041 SH |
405 | |
406 | error_put: | |
407 | put_cred(new); | |
408 | return ret; | |
d84f4f99 | 409 | } |
f1752eec | 410 | |
aa6d054e EB |
411 | static bool cred_cap_issubset(const struct cred *set, const struct cred *subset) |
412 | { | |
413 | const struct user_namespace *set_ns = set->user_ns; | |
414 | const struct user_namespace *subset_ns = subset->user_ns; | |
415 | ||
416 | /* If the two credentials are in the same user namespace see if | |
417 | * the capabilities of subset are a subset of set. | |
418 | */ | |
419 | if (set_ns == subset_ns) | |
420 | return cap_issubset(subset->cap_permitted, set->cap_permitted); | |
421 | ||
422 | /* The credentials are in a different user namespaces | |
423 | * therefore one is a subset of the other only if a set is an | |
424 | * ancestor of subset and set->euid is owner of subset or one | |
425 | * of subsets ancestors. | |
426 | */ | |
427 | for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) { | |
428 | if ((set_ns == subset_ns->parent) && | |
429 | uid_eq(subset_ns->owner, set->euid)) | |
430 | return true; | |
431 | } | |
432 | ||
433 | return false; | |
434 | } | |
435 | ||
d84f4f99 DH |
436 | /** |
437 | * commit_creds - Install new credentials upon the current task | |
438 | * @new: The credentials to be assigned | |
439 | * | |
440 | * Install a new set of credentials to the current task, using RCU to replace | |
3b11a1de DH |
441 | * the old set. Both the objective and the subjective credentials pointers are |
442 | * updated. This function may not be called if the subjective credentials are | |
443 | * in an overridden state. | |
d84f4f99 DH |
444 | * |
445 | * This function eats the caller's reference to the new credentials. | |
446 | * | |
447 | * Always returns 0 thus allowing this function to be tail-called at the end | |
448 | * of, say, sys_setgid(). | |
449 | */ | |
450 | int commit_creds(struct cred *new) | |
451 | { | |
452 | struct task_struct *task = current; | |
e0e81739 | 453 | const struct cred *old = task->real_cred; |
d84f4f99 | 454 | |
e0e81739 DH |
455 | kdebug("commit_creds(%p{%d,%d})", new, |
456 | atomic_read(&new->usage), | |
457 | read_cred_subscribers(new)); | |
458 | ||
459 | BUG_ON(task->cred != old); | |
460 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
461 | BUG_ON(read_cred_subscribers(old) < 2); | |
462 | validate_creds(old); | |
463 | validate_creds(new); | |
464 | #endif | |
d84f4f99 | 465 | BUG_ON(atomic_read(&new->usage) < 1); |
d84f4f99 | 466 | |
3b11a1de DH |
467 | get_cred(new); /* we will require a ref for the subj creds too */ |
468 | ||
d84f4f99 | 469 | /* dumpability changes */ |
078de5f7 EB |
470 | if (!uid_eq(old->euid, new->euid) || |
471 | !gid_eq(old->egid, new->egid) || | |
472 | !uid_eq(old->fsuid, new->fsuid) || | |
473 | !gid_eq(old->fsgid, new->fsgid) || | |
aa6d054e | 474 | !cred_cap_issubset(old, new)) { |
b9456371 DH |
475 | if (task->mm) |
476 | set_dumpable(task->mm, suid_dumpable); | |
d84f4f99 | 477 | task->pdeath_signal = 0; |
f6581f5b JH |
478 | /* |
479 | * If a task drops privileges and becomes nondumpable, | |
480 | * the dumpability change must become visible before | |
481 | * the credential change; otherwise, a __ptrace_may_access() | |
482 | * racing with this change may be able to attach to a task it | |
483 | * shouldn't be able to attach to (as if the task had dropped | |
484 | * privileges without becoming nondumpable). | |
485 | * Pairs with a read barrier in __ptrace_may_access(). | |
486 | */ | |
d84f4f99 | 487 | smp_wmb(); |
f1752eec DH |
488 | } |
489 | ||
d84f4f99 | 490 | /* alter the thread keyring */ |
078de5f7 | 491 | if (!uid_eq(new->fsuid, old->fsuid)) |
2e21865f | 492 | key_fsuid_changed(new); |
078de5f7 | 493 | if (!gid_eq(new->fsgid, old->fsgid)) |
2e21865f | 494 | key_fsgid_changed(new); |
d84f4f99 DH |
495 | |
496 | /* do it | |
72fa5997 VK |
497 | * RLIMIT_NPROC limits on user->processes have already been checked |
498 | * in set_user(). | |
d84f4f99 | 499 | */ |
e0e81739 | 500 | alter_cred_subscribers(new, 2); |
21d1c5e3 AG |
501 | if (new->user != old->user || new->user_ns != old->user_ns) |
502 | inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1); | |
3b11a1de | 503 | rcu_assign_pointer(task->real_cred, new); |
d84f4f99 | 504 | rcu_assign_pointer(task->cred, new); |
629715ad | 505 | if (new->user != old->user || new->user_ns != old->user_ns) |
21d1c5e3 | 506 | dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1); |
e0e81739 | 507 | alter_cred_subscribers(old, -2); |
d84f4f99 | 508 | |
d84f4f99 | 509 | /* send notifications */ |
078de5f7 EB |
510 | if (!uid_eq(new->uid, old->uid) || |
511 | !uid_eq(new->euid, old->euid) || | |
512 | !uid_eq(new->suid, old->suid) || | |
513 | !uid_eq(new->fsuid, old->fsuid)) | |
d84f4f99 | 514 | proc_id_connector(task, PROC_EVENT_UID); |
f1752eec | 515 | |
078de5f7 EB |
516 | if (!gid_eq(new->gid, old->gid) || |
517 | !gid_eq(new->egid, old->egid) || | |
518 | !gid_eq(new->sgid, old->sgid) || | |
519 | !gid_eq(new->fsgid, old->fsgid)) | |
d84f4f99 | 520 | proc_id_connector(task, PROC_EVENT_GID); |
f1752eec | 521 | |
3b11a1de DH |
522 | /* release the old obj and subj refs both */ |
523 | put_cred(old); | |
d84f4f99 | 524 | put_cred(old); |
f1752eec DH |
525 | return 0; |
526 | } | |
d84f4f99 DH |
527 | EXPORT_SYMBOL(commit_creds); |
528 | ||
529 | /** | |
530 | * abort_creds - Discard a set of credentials and unlock the current task | |
531 | * @new: The credentials that were going to be applied | |
532 | * | |
533 | * Discard a set of credentials that were under construction and unlock the | |
534 | * current task. | |
535 | */ | |
536 | void abort_creds(struct cred *new) | |
537 | { | |
e0e81739 DH |
538 | kdebug("abort_creds(%p{%d,%d})", new, |
539 | atomic_read(&new->usage), | |
540 | read_cred_subscribers(new)); | |
541 | ||
542 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
543 | BUG_ON(read_cred_subscribers(new) != 0); | |
544 | #endif | |
d84f4f99 DH |
545 | BUG_ON(atomic_read(&new->usage) < 1); |
546 | put_cred(new); | |
547 | } | |
548 | EXPORT_SYMBOL(abort_creds); | |
549 | ||
550 | /** | |
3b11a1de | 551 | * override_creds - Override the current process's subjective credentials |
d84f4f99 DH |
552 | * @new: The credentials to be assigned |
553 | * | |
3b11a1de DH |
554 | * Install a set of temporary override subjective credentials on the current |
555 | * process, returning the old set for later reversion. | |
d84f4f99 DH |
556 | */ |
557 | const struct cred *override_creds(const struct cred *new) | |
558 | { | |
559 | const struct cred *old = current->cred; | |
560 | ||
e0e81739 DH |
561 | kdebug("override_creds(%p{%d,%d})", new, |
562 | atomic_read(&new->usage), | |
563 | read_cred_subscribers(new)); | |
564 | ||
565 | validate_creds(old); | |
566 | validate_creds(new); | |
d7852fbd LT |
567 | |
568 | /* | |
569 | * NOTE! This uses 'get_new_cred()' rather than 'get_cred()'. | |
570 | * | |
571 | * That means that we do not clear the 'non_rcu' flag, since | |
572 | * we are only installing the cred into the thread-synchronous | |
573 | * '->cred' pointer, not the '->real_cred' pointer that is | |
574 | * visible to other threads under RCU. | |
575 | * | |
576 | * Also note that we did validate_creds() manually, not depending | |
577 | * on the validation in 'get_cred()'. | |
578 | */ | |
579 | get_new_cred((struct cred *)new); | |
e0e81739 DH |
580 | alter_cred_subscribers(new, 1); |
581 | rcu_assign_pointer(current->cred, new); | |
582 | alter_cred_subscribers(old, -1); | |
583 | ||
584 | kdebug("override_creds() = %p{%d,%d}", old, | |
585 | atomic_read(&old->usage), | |
586 | read_cred_subscribers(old)); | |
d84f4f99 DH |
587 | return old; |
588 | } | |
589 | EXPORT_SYMBOL(override_creds); | |
590 | ||
591 | /** | |
3b11a1de | 592 | * revert_creds - Revert a temporary subjective credentials override |
d84f4f99 DH |
593 | * @old: The credentials to be restored |
594 | * | |
3b11a1de DH |
595 | * Revert a temporary set of override subjective credentials to an old set, |
596 | * discarding the override set. | |
d84f4f99 DH |
597 | */ |
598 | void revert_creds(const struct cred *old) | |
599 | { | |
600 | const struct cred *override = current->cred; | |
601 | ||
e0e81739 DH |
602 | kdebug("revert_creds(%p{%d,%d})", old, |
603 | atomic_read(&old->usage), | |
604 | read_cred_subscribers(old)); | |
605 | ||
606 | validate_creds(old); | |
607 | validate_creds(override); | |
608 | alter_cred_subscribers(old, 1); | |
d84f4f99 | 609 | rcu_assign_pointer(current->cred, old); |
e0e81739 | 610 | alter_cred_subscribers(override, -1); |
d84f4f99 DH |
611 | put_cred(override); |
612 | } | |
613 | EXPORT_SYMBOL(revert_creds); | |
614 | ||
d89b22d4 N |
615 | /** |
616 | * cred_fscmp - Compare two credentials with respect to filesystem access. | |
617 | * @a: The first credential | |
618 | * @b: The second credential | |
619 | * | |
620 | * cred_cmp() will return zero if both credentials have the same | |
621 | * fsuid, fsgid, and supplementary groups. That is, if they will both | |
622 | * provide the same access to files based on mode/uid/gid. | |
623 | * If the credentials are different, then either -1 or 1 will | |
624 | * be returned depending on whether @a comes before or after @b | |
625 | * respectively in an arbitrary, but stable, ordering of credentials. | |
626 | * | |
627 | * Return: -1, 0, or 1 depending on comparison | |
628 | */ | |
629 | int cred_fscmp(const struct cred *a, const struct cred *b) | |
630 | { | |
631 | struct group_info *ga, *gb; | |
632 | int g; | |
633 | ||
634 | if (a == b) | |
635 | return 0; | |
636 | if (uid_lt(a->fsuid, b->fsuid)) | |
637 | return -1; | |
638 | if (uid_gt(a->fsuid, b->fsuid)) | |
639 | return 1; | |
640 | ||
641 | if (gid_lt(a->fsgid, b->fsgid)) | |
642 | return -1; | |
643 | if (gid_gt(a->fsgid, b->fsgid)) | |
644 | return 1; | |
645 | ||
646 | ga = a->group_info; | |
647 | gb = b->group_info; | |
648 | if (ga == gb) | |
649 | return 0; | |
650 | if (ga == NULL) | |
651 | return -1; | |
652 | if (gb == NULL) | |
653 | return 1; | |
654 | if (ga->ngroups < gb->ngroups) | |
655 | return -1; | |
656 | if (ga->ngroups > gb->ngroups) | |
657 | return 1; | |
658 | ||
659 | for (g = 0; g < ga->ngroups; g++) { | |
660 | if (gid_lt(ga->gid[g], gb->gid[g])) | |
661 | return -1; | |
662 | if (gid_gt(ga->gid[g], gb->gid[g])) | |
663 | return 1; | |
664 | } | |
665 | return 0; | |
666 | } | |
667 | EXPORT_SYMBOL(cred_fscmp); | |
668 | ||
905ae01c AG |
669 | int set_cred_ucounts(struct cred *new) |
670 | { | |
34dc2fd6 | 671 | struct ucounts *new_ucounts, *old_ucounts = new->ucounts; |
905ae01c | 672 | |
905ae01c AG |
673 | /* |
674 | * This optimization is needed because alloc_ucounts() uses locks | |
675 | * for table lookups. | |
676 | */ | |
a55d0729 | 677 | if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->uid)) |
905ae01c AG |
678 | return 0; |
679 | ||
a55d0729 | 680 | if (!(new_ucounts = alloc_ucounts(new->user_ns, new->uid))) |
905ae01c AG |
681 | return -EAGAIN; |
682 | ||
34dc2fd6 | 683 | new->ucounts = new_ucounts; |
99c31f9f | 684 | put_ucounts(old_ucounts); |
905ae01c AG |
685 | |
686 | return 0; | |
687 | } | |
688 | ||
d84f4f99 DH |
689 | /* |
690 | * initialise the credentials stuff | |
691 | */ | |
692 | void __init cred_init(void) | |
693 | { | |
694 | /* allocate a slab in which we can store credentials */ | |
5d097056 VD |
695 | cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0, |
696 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL); | |
d84f4f99 | 697 | } |
3a3b7ce9 DH |
698 | |
699 | /** | |
700 | * prepare_kernel_cred - Prepare a set of credentials for a kernel service | |
701 | * @daemon: A userspace daemon to be used as a reference | |
702 | * | |
703 | * Prepare a set of credentials for a kernel service. This can then be used to | |
704 | * override a task's own credentials so that work can be done on behalf of that | |
705 | * task that requires a different subjective context. | |
706 | * | |
5a17f040 KC |
707 | * @daemon is used to provide a base cred, with the security data derived from |
708 | * that; if this is "&init_task", they'll be set to 0, no groups, full | |
709 | * capabilities, and no keys. | |
3a3b7ce9 DH |
710 | * |
711 | * The caller may change these controls afterwards if desired. | |
712 | * | |
713 | * Returns the new credentials or NULL if out of memory. | |
3a3b7ce9 DH |
714 | */ |
715 | struct cred *prepare_kernel_cred(struct task_struct *daemon) | |
716 | { | |
717 | const struct cred *old; | |
718 | struct cred *new; | |
719 | ||
5a17f040 KC |
720 | if (WARN_ON_ONCE(!daemon)) |
721 | return NULL; | |
722 | ||
3a3b7ce9 DH |
723 | new = kmem_cache_alloc(cred_jar, GFP_KERNEL); |
724 | if (!new) | |
725 | return NULL; | |
726 | ||
e0e81739 DH |
727 | kdebug("prepare_kernel_cred() alloc %p", new); |
728 | ||
5a17f040 | 729 | old = get_task_cred(daemon); |
e0e81739 DH |
730 | validate_creds(old); |
731 | ||
43529c97 | 732 | *new = *old; |
d7852fbd | 733 | new->non_rcu = 0; |
fb2b2a1d TH |
734 | atomic_set(&new->usage, 1); |
735 | set_cred_subscribers(new, 0); | |
3a3b7ce9 | 736 | get_uid(new->user); |
0093ccb6 | 737 | get_user_ns(new->user_ns); |
3a3b7ce9 DH |
738 | get_group_info(new->group_info); |
739 | ||
740 | #ifdef CONFIG_KEYS | |
3a50597d DH |
741 | new->session_keyring = NULL; |
742 | new->process_keyring = NULL; | |
3a3b7ce9 | 743 | new->thread_keyring = NULL; |
3a50597d | 744 | new->request_key_auth = NULL; |
3a3b7ce9 DH |
745 | new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; |
746 | #endif | |
747 | ||
748 | #ifdef CONFIG_SECURITY | |
749 | new->security = NULL; | |
750 | #endif | |
905ae01c AG |
751 | new->ucounts = get_ucounts(new->ucounts); |
752 | if (!new->ucounts) | |
753 | goto error; | |
754 | ||
bbb6d0f3 AG |
755 | if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0) |
756 | goto error; | |
757 | ||
3a3b7ce9 | 758 | put_cred(old); |
e0e81739 | 759 | validate_creds(new); |
3a3b7ce9 DH |
760 | return new; |
761 | ||
762 | error: | |
763 | put_cred(new); | |
0de33681 | 764 | put_cred(old); |
3a3b7ce9 DH |
765 | return NULL; |
766 | } | |
767 | EXPORT_SYMBOL(prepare_kernel_cred); | |
768 | ||
769 | /** | |
770 | * set_security_override - Set the security ID in a set of credentials | |
771 | * @new: The credentials to alter | |
772 | * @secid: The LSM security ID to set | |
773 | * | |
774 | * Set the LSM security ID in a set of credentials so that the subjective | |
775 | * security is overridden when an alternative set of credentials is used. | |
776 | */ | |
777 | int set_security_override(struct cred *new, u32 secid) | |
778 | { | |
779 | return security_kernel_act_as(new, secid); | |
780 | } | |
781 | EXPORT_SYMBOL(set_security_override); | |
782 | ||
783 | /** | |
784 | * set_security_override_from_ctx - Set the security ID in a set of credentials | |
785 | * @new: The credentials to alter | |
786 | * @secctx: The LSM security context to generate the security ID from. | |
787 | * | |
788 | * Set the LSM security ID in a set of credentials so that the subjective | |
789 | * security is overridden when an alternative set of credentials is used. The | |
790 | * security ID is specified in string form as a security context to be | |
791 | * interpreted by the LSM. | |
792 | */ | |
793 | int set_security_override_from_ctx(struct cred *new, const char *secctx) | |
794 | { | |
795 | u32 secid; | |
796 | int ret; | |
797 | ||
798 | ret = security_secctx_to_secid(secctx, strlen(secctx), &secid); | |
799 | if (ret < 0) | |
800 | return ret; | |
801 | ||
802 | return set_security_override(new, secid); | |
803 | } | |
804 | EXPORT_SYMBOL(set_security_override_from_ctx); | |
805 | ||
806 | /** | |
807 | * set_create_files_as - Set the LSM file create context in a set of credentials | |
808 | * @new: The credentials to alter | |
809 | * @inode: The inode to take the context from | |
810 | * | |
811 | * Change the LSM file creation context in a set of credentials to be the same | |
812 | * as the object context of the specified inode, so that the new inodes have | |
813 | * the same MAC context as that inode. | |
814 | */ | |
815 | int set_create_files_as(struct cred *new, struct inode *inode) | |
816 | { | |
5f65e5ca SF |
817 | if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) |
818 | return -EINVAL; | |
3a3b7ce9 DH |
819 | new->fsuid = inode->i_uid; |
820 | new->fsgid = inode->i_gid; | |
821 | return security_kernel_create_files_as(new, inode); | |
822 | } | |
823 | EXPORT_SYMBOL(set_create_files_as); | |
e0e81739 DH |
824 | |
825 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
826 | ||
74908a00 AM |
827 | bool creds_are_invalid(const struct cred *cred) |
828 | { | |
829 | if (cred->magic != CRED_MAGIC) | |
830 | return true; | |
74908a00 AM |
831 | return false; |
832 | } | |
764db03f | 833 | EXPORT_SYMBOL(creds_are_invalid); |
74908a00 | 834 | |
e0e81739 DH |
835 | /* |
836 | * dump invalid credentials | |
837 | */ | |
838 | static void dump_invalid_creds(const struct cred *cred, const char *label, | |
839 | const struct task_struct *tsk) | |
840 | { | |
4099451a | 841 | pr_err("%s credentials: %p %s%s%s\n", |
e0e81739 DH |
842 | label, cred, |
843 | cred == &init_cred ? "[init]" : "", | |
844 | cred == tsk->real_cred ? "[real]" : "", | |
845 | cred == tsk->cred ? "[eff]" : ""); | |
4099451a | 846 | pr_err("->magic=%x, put_addr=%p\n", |
e0e81739 | 847 | cred->magic, cred->put_addr); |
4099451a | 848 | pr_err("->usage=%d, subscr=%d\n", |
e0e81739 DH |
849 | atomic_read(&cred->usage), |
850 | read_cred_subscribers(cred)); | |
4099451a | 851 | pr_err("->*uid = { %d,%d,%d,%d }\n", |
c9235f48 EB |
852 | from_kuid_munged(&init_user_ns, cred->uid), |
853 | from_kuid_munged(&init_user_ns, cred->euid), | |
854 | from_kuid_munged(&init_user_ns, cred->suid), | |
855 | from_kuid_munged(&init_user_ns, cred->fsuid)); | |
4099451a | 856 | pr_err("->*gid = { %d,%d,%d,%d }\n", |
c9235f48 EB |
857 | from_kgid_munged(&init_user_ns, cred->gid), |
858 | from_kgid_munged(&init_user_ns, cred->egid), | |
859 | from_kgid_munged(&init_user_ns, cred->sgid), | |
860 | from_kgid_munged(&init_user_ns, cred->fsgid)); | |
e0e81739 | 861 | #ifdef CONFIG_SECURITY |
4099451a | 862 | pr_err("->security is %p\n", cred->security); |
e0e81739 DH |
863 | if ((unsigned long) cred->security >= PAGE_SIZE && |
864 | (((unsigned long) cred->security & 0xffffff00) != | |
865 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))) | |
4099451a | 866 | pr_err("->security {%x, %x}\n", |
e0e81739 DH |
867 | ((u32*)cred->security)[0], |
868 | ((u32*)cred->security)[1]); | |
869 | #endif | |
870 | } | |
871 | ||
872 | /* | |
873 | * report use of invalid credentials | |
874 | */ | |
105cd685 | 875 | void __noreturn __invalid_creds(const struct cred *cred, const char *file, unsigned line) |
e0e81739 | 876 | { |
4099451a | 877 | pr_err("Invalid credentials\n"); |
878 | pr_err("At %s:%u\n", file, line); | |
e0e81739 DH |
879 | dump_invalid_creds(cred, "Specified", current); |
880 | BUG(); | |
881 | } | |
882 | EXPORT_SYMBOL(__invalid_creds); | |
883 | ||
884 | /* | |
885 | * check the credentials on a process | |
886 | */ | |
887 | void __validate_process_creds(struct task_struct *tsk, | |
888 | const char *file, unsigned line) | |
889 | { | |
890 | if (tsk->cred == tsk->real_cred) { | |
891 | if (unlikely(read_cred_subscribers(tsk->cred) < 2 || | |
892 | creds_are_invalid(tsk->cred))) | |
893 | goto invalid_creds; | |
894 | } else { | |
895 | if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 || | |
896 | read_cred_subscribers(tsk->cred) < 1 || | |
897 | creds_are_invalid(tsk->real_cred) || | |
898 | creds_are_invalid(tsk->cred))) | |
899 | goto invalid_creds; | |
900 | } | |
901 | return; | |
902 | ||
903 | invalid_creds: | |
4099451a | 904 | pr_err("Invalid process credentials\n"); |
905 | pr_err("At %s:%u\n", file, line); | |
e0e81739 DH |
906 | |
907 | dump_invalid_creds(tsk->real_cred, "Real", tsk); | |
908 | if (tsk->cred != tsk->real_cred) | |
909 | dump_invalid_creds(tsk->cred, "Effective", tsk); | |
910 | else | |
4099451a | 911 | pr_err("Effective creds == Real creds\n"); |
e0e81739 DH |
912 | BUG(); |
913 | } | |
914 | EXPORT_SYMBOL(__validate_process_creds); | |
915 | ||
916 | /* | |
917 | * check creds for do_exit() | |
918 | */ | |
919 | void validate_creds_for_do_exit(struct task_struct *tsk) | |
920 | { | |
921 | kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})", | |
922 | tsk->real_cred, tsk->cred, | |
923 | atomic_read(&tsk->cred->usage), | |
924 | read_cred_subscribers(tsk->cred)); | |
925 | ||
926 | __validate_process_creds(tsk, __FILE__, __LINE__); | |
927 | } | |
928 | ||
929 | #endif /* CONFIG_DEBUG_CREDENTIALS */ |