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1da177e4 LT |
1 | /* request_key.c: request a key from userspace |
2 | * | |
3e30148c | 3 | * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved. |
1da177e4 LT |
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 License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
f1a9badc DH |
10 | * |
11 | * See Documentation/keys-request-key.txt | |
1da177e4 LT |
12 | */ |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/kmod.h> | |
17 | #include <linux/err.h> | |
3e30148c | 18 | #include <linux/keyctl.h> |
1da177e4 LT |
19 | #include "internal.h" |
20 | ||
21 | struct key_construction { | |
22 | struct list_head link; /* link in construction queue */ | |
23 | struct key *key; /* key being constructed */ | |
24 | }; | |
25 | ||
26 | /* when waiting for someone else's keys, you get added to this */ | |
27 | DECLARE_WAIT_QUEUE_HEAD(request_key_conswq); | |
28 | ||
29 | /*****************************************************************************/ | |
30 | /* | |
31 | * request userspace finish the construction of a key | |
32 | * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring> <info>" | |
1da177e4 LT |
33 | */ |
34 | static int call_request_key(struct key *key, | |
35 | const char *op, | |
36 | const char *callout_info) | |
37 | { | |
38 | struct task_struct *tsk = current; | |
1da177e4 | 39 | key_serial_t prkey, sskey; |
3e30148c | 40 | struct key *session_keyring, *rkakey; |
1da177e4 LT |
41 | char *argv[10], *envp[3], uid_str[12], gid_str[12]; |
42 | char key_str[12], keyring_str[3][12]; | |
3e30148c DH |
43 | int ret, i; |
44 | ||
45 | kenter("{%d},%s,%s", key->serial, op, callout_info); | |
46 | ||
47 | /* generate a new session keyring with an auth key in it */ | |
48 | session_keyring = request_key_auth_new(key, &rkakey); | |
49 | if (IS_ERR(session_keyring)) { | |
50 | ret = PTR_ERR(session_keyring); | |
51 | goto error; | |
52 | } | |
1da177e4 LT |
53 | |
54 | /* record the UID and GID */ | |
55 | sprintf(uid_str, "%d", current->fsuid); | |
56 | sprintf(gid_str, "%d", current->fsgid); | |
57 | ||
58 | /* we say which key is under construction */ | |
59 | sprintf(key_str, "%d", key->serial); | |
60 | ||
61 | /* we specify the process's default keyrings */ | |
62 | sprintf(keyring_str[0], "%d", | |
63 | tsk->thread_keyring ? tsk->thread_keyring->serial : 0); | |
64 | ||
65 | prkey = 0; | |
66 | if (tsk->signal->process_keyring) | |
67 | prkey = tsk->signal->process_keyring->serial; | |
68 | ||
3e30148c | 69 | sprintf(keyring_str[1], "%d", prkey); |
1da177e4 | 70 | |
3e30148c DH |
71 | if (tsk->signal->session_keyring) { |
72 | rcu_read_lock(); | |
73 | sskey = rcu_dereference(tsk->signal->session_keyring)->serial; | |
74 | rcu_read_unlock(); | |
75 | } | |
76 | else { | |
1da177e4 | 77 | sskey = tsk->user->session_keyring->serial; |
3e30148c | 78 | } |
1da177e4 | 79 | |
1da177e4 LT |
80 | sprintf(keyring_str[2], "%d", sskey); |
81 | ||
82 | /* set up a minimal environment */ | |
83 | i = 0; | |
84 | envp[i++] = "HOME=/"; | |
85 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
86 | envp[i] = NULL; | |
87 | ||
88 | /* set up the argument list */ | |
89 | i = 0; | |
90 | argv[i++] = "/sbin/request-key"; | |
91 | argv[i++] = (char *) op; | |
92 | argv[i++] = key_str; | |
93 | argv[i++] = uid_str; | |
94 | argv[i++] = gid_str; | |
95 | argv[i++] = keyring_str[0]; | |
96 | argv[i++] = keyring_str[1]; | |
97 | argv[i++] = keyring_str[2]; | |
3e30148c | 98 | argv[i++] = (char *) callout_info; |
1da177e4 LT |
99 | argv[i] = NULL; |
100 | ||
101 | /* do it */ | |
3e30148c DH |
102 | ret = call_usermodehelper_keys(argv[0], argv, envp, session_keyring, 1); |
103 | ||
104 | /* dispose of the special keys */ | |
105 | key_revoke(rkakey); | |
106 | key_put(rkakey); | |
107 | key_put(session_keyring); | |
108 | ||
109 | error: | |
110 | kleave(" = %d", ret); | |
111 | return ret; | |
1da177e4 LT |
112 | |
113 | } /* end call_request_key() */ | |
114 | ||
115 | /*****************************************************************************/ | |
116 | /* | |
117 | * call out to userspace for the key | |
118 | * - called with the construction sem held, but the sem is dropped here | |
119 | * - we ignore program failure and go on key status instead | |
120 | */ | |
121 | static struct key *__request_key_construction(struct key_type *type, | |
122 | const char *description, | |
123 | const char *callout_info) | |
124 | { | |
125 | struct key_construction cons; | |
126 | struct timespec now; | |
127 | struct key *key; | |
76d8aeab | 128 | int ret, negated; |
1da177e4 | 129 | |
3e30148c DH |
130 | kenter("%s,%s,%s", type->name, description, callout_info); |
131 | ||
1da177e4 LT |
132 | /* create a key and add it to the queue */ |
133 | key = key_alloc(type, description, | |
664cceb0 | 134 | current->fsuid, current->fsgid, KEY_POS_ALL, 0); |
1da177e4 LT |
135 | if (IS_ERR(key)) |
136 | goto alloc_failed; | |
137 | ||
76d8aeab | 138 | set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags); |
1da177e4 LT |
139 | |
140 | cons.key = key; | |
141 | list_add_tail(&cons.link, &key->user->consq); | |
142 | ||
143 | /* we drop the construction sem here on behalf of the caller */ | |
144 | up_write(&key_construction_sem); | |
145 | ||
146 | /* make the call */ | |
147 | ret = call_request_key(key, "create", callout_info); | |
148 | if (ret < 0) | |
149 | goto request_failed; | |
150 | ||
151 | /* if the key wasn't instantiated, then we want to give an error */ | |
152 | ret = -ENOKEY; | |
76d8aeab | 153 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) |
1da177e4 LT |
154 | goto request_failed; |
155 | ||
156 | down_write(&key_construction_sem); | |
157 | list_del(&cons.link); | |
158 | up_write(&key_construction_sem); | |
159 | ||
160 | /* also give an error if the key was negatively instantiated */ | |
161 | check_not_negative: | |
76d8aeab | 162 | if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) { |
1da177e4 LT |
163 | key_put(key); |
164 | key = ERR_PTR(-ENOKEY); | |
165 | } | |
166 | ||
167 | out: | |
3e30148c | 168 | kleave(" = %p", key); |
1da177e4 LT |
169 | return key; |
170 | ||
171 | request_failed: | |
172 | /* it wasn't instantiated | |
173 | * - remove from construction queue | |
174 | * - mark the key as dead | |
175 | */ | |
76d8aeab | 176 | negated = 0; |
1da177e4 LT |
177 | down_write(&key_construction_sem); |
178 | ||
179 | list_del(&cons.link); | |
180 | ||
1da177e4 | 181 | /* check it didn't get instantiated between the check and the down */ |
76d8aeab DH |
182 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { |
183 | set_bit(KEY_FLAG_NEGATIVE, &key->flags); | |
184 | set_bit(KEY_FLAG_INSTANTIATED, &key->flags); | |
185 | negated = 1; | |
1da177e4 LT |
186 | } |
187 | ||
76d8aeab DH |
188 | clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags); |
189 | ||
1da177e4 LT |
190 | up_write(&key_construction_sem); |
191 | ||
76d8aeab | 192 | if (!negated) |
1da177e4 LT |
193 | goto check_not_negative; /* surprisingly, the key got |
194 | * instantiated */ | |
195 | ||
196 | /* set the timeout and store in the session keyring if we can */ | |
197 | now = current_kernel_time(); | |
198 | key->expiry = now.tv_sec + key_negative_timeout; | |
199 | ||
200 | if (current->signal->session_keyring) { | |
1da177e4 LT |
201 | struct key *keyring; |
202 | ||
8589b4e0 DH |
203 | rcu_read_lock(); |
204 | keyring = rcu_dereference(current->signal->session_keyring); | |
1da177e4 | 205 | atomic_inc(&keyring->usage); |
8589b4e0 | 206 | rcu_read_unlock(); |
1da177e4 LT |
207 | |
208 | key_link(keyring, key); | |
209 | key_put(keyring); | |
210 | } | |
211 | ||
212 | key_put(key); | |
213 | ||
214 | /* notify anyone who was waiting */ | |
215 | wake_up_all(&request_key_conswq); | |
216 | ||
217 | key = ERR_PTR(ret); | |
218 | goto out; | |
219 | ||
220 | alloc_failed: | |
221 | up_write(&key_construction_sem); | |
222 | goto out; | |
223 | ||
224 | } /* end __request_key_construction() */ | |
225 | ||
226 | /*****************************************************************************/ | |
227 | /* | |
228 | * call out to userspace to request the key | |
229 | * - we check the construction queue first to see if an appropriate key is | |
230 | * already being constructed by userspace | |
231 | */ | |
232 | static struct key *request_key_construction(struct key_type *type, | |
233 | const char *description, | |
234 | struct key_user *user, | |
235 | const char *callout_info) | |
236 | { | |
237 | struct key_construction *pcons; | |
238 | struct key *key, *ckey; | |
239 | ||
240 | DECLARE_WAITQUEUE(myself, current); | |
241 | ||
3e30148c DH |
242 | kenter("%s,%s,{%d},%s", |
243 | type->name, description, user->uid, callout_info); | |
244 | ||
1da177e4 LT |
245 | /* see if there's such a key under construction already */ |
246 | down_write(&key_construction_sem); | |
247 | ||
248 | list_for_each_entry(pcons, &user->consq, link) { | |
249 | ckey = pcons->key; | |
250 | ||
251 | if (ckey->type != type) | |
252 | continue; | |
253 | ||
254 | if (type->match(ckey, description)) | |
255 | goto found_key_under_construction; | |
256 | } | |
257 | ||
258 | /* see about getting userspace to construct the key */ | |
259 | key = __request_key_construction(type, description, callout_info); | |
260 | error: | |
3e30148c | 261 | kleave(" = %p", key); |
1da177e4 LT |
262 | return key; |
263 | ||
264 | /* someone else has the same key under construction | |
265 | * - we want to keep an eye on their key | |
266 | */ | |
267 | found_key_under_construction: | |
268 | atomic_inc(&ckey->usage); | |
269 | up_write(&key_construction_sem); | |
270 | ||
271 | /* wait for the key to be completed one way or another */ | |
272 | add_wait_queue(&request_key_conswq, &myself); | |
273 | ||
274 | for (;;) { | |
3e30148c | 275 | set_current_state(TASK_INTERRUPTIBLE); |
76d8aeab | 276 | if (!test_bit(KEY_FLAG_USER_CONSTRUCT, &ckey->flags)) |
1da177e4 | 277 | break; |
3e30148c DH |
278 | if (signal_pending(current)) |
279 | break; | |
1da177e4 LT |
280 | schedule(); |
281 | } | |
282 | ||
283 | set_current_state(TASK_RUNNING); | |
284 | remove_wait_queue(&request_key_conswq, &myself); | |
285 | ||
286 | /* we'll need to search this process's keyrings to see if the key is | |
287 | * now there since we can't automatically assume it's also available | |
288 | * there */ | |
289 | key_put(ckey); | |
290 | ckey = NULL; | |
291 | ||
292 | key = NULL; /* request a retry */ | |
293 | goto error; | |
294 | ||
295 | } /* end request_key_construction() */ | |
296 | ||
3e30148c DH |
297 | /*****************************************************************************/ |
298 | /* | |
299 | * link a freshly minted key to an appropriate destination keyring | |
300 | */ | |
301 | static void request_key_link(struct key *key, struct key *dest_keyring) | |
302 | { | |
303 | struct task_struct *tsk = current; | |
304 | struct key *drop = NULL; | |
305 | ||
306 | kenter("{%d},%p", key->serial, dest_keyring); | |
307 | ||
308 | /* find the appropriate keyring */ | |
309 | if (!dest_keyring) { | |
310 | switch (tsk->jit_keyring) { | |
311 | case KEY_REQKEY_DEFL_DEFAULT: | |
312 | case KEY_REQKEY_DEFL_THREAD_KEYRING: | |
313 | dest_keyring = tsk->thread_keyring; | |
314 | if (dest_keyring) | |
315 | break; | |
316 | ||
317 | case KEY_REQKEY_DEFL_PROCESS_KEYRING: | |
318 | dest_keyring = tsk->signal->process_keyring; | |
319 | if (dest_keyring) | |
320 | break; | |
321 | ||
322 | case KEY_REQKEY_DEFL_SESSION_KEYRING: | |
323 | rcu_read_lock(); | |
324 | dest_keyring = key_get( | |
325 | rcu_dereference(tsk->signal->session_keyring)); | |
326 | rcu_read_unlock(); | |
327 | drop = dest_keyring; | |
328 | ||
329 | if (dest_keyring) | |
330 | break; | |
331 | ||
332 | case KEY_REQKEY_DEFL_USER_SESSION_KEYRING: | |
333 | dest_keyring = current->user->session_keyring; | |
334 | break; | |
335 | ||
336 | case KEY_REQKEY_DEFL_USER_KEYRING: | |
337 | dest_keyring = current->user->uid_keyring; | |
338 | break; | |
339 | ||
340 | case KEY_REQKEY_DEFL_GROUP_KEYRING: | |
341 | default: | |
342 | BUG(); | |
343 | } | |
344 | } | |
345 | ||
346 | /* and attach the key to it */ | |
347 | key_link(dest_keyring, key); | |
348 | ||
349 | key_put(drop); | |
350 | ||
351 | kleave(""); | |
352 | ||
353 | } /* end request_key_link() */ | |
354 | ||
1da177e4 LT |
355 | /*****************************************************************************/ |
356 | /* | |
357 | * request a key | |
358 | * - search the process's keyrings | |
359 | * - check the list of keys being created or updated | |
3e30148c DH |
360 | * - call out to userspace for a key if supplementary info was provided |
361 | * - cache the key in an appropriate keyring | |
1da177e4 | 362 | */ |
3e30148c DH |
363 | struct key *request_key_and_link(struct key_type *type, |
364 | const char *description, | |
365 | const char *callout_info, | |
366 | struct key *dest_keyring) | |
1da177e4 LT |
367 | { |
368 | struct key_user *user; | |
369 | struct key *key; | |
664cceb0 | 370 | key_ref_t key_ref; |
1da177e4 | 371 | |
3e30148c DH |
372 | kenter("%s,%s,%s,%p", |
373 | type->name, description, callout_info, dest_keyring); | |
374 | ||
1da177e4 | 375 | /* search all the process keyrings for a key */ |
664cceb0 DH |
376 | key_ref = search_process_keyrings(type, description, type->match, |
377 | current); | |
1da177e4 | 378 | |
664cceb0 DH |
379 | kdebug("search 1: %p", key_ref); |
380 | ||
381 | if (!IS_ERR(key_ref)) { | |
382 | key = key_ref_to_ptr(key_ref); | |
383 | } | |
384 | else if (PTR_ERR(key_ref) != -EAGAIN) { | |
385 | key = ERR_PTR(PTR_ERR(key_ref)); | |
386 | } | |
387 | else { | |
1da177e4 LT |
388 | /* the search failed, but the keyrings were searchable, so we |
389 | * should consult userspace if we can */ | |
390 | key = ERR_PTR(-ENOKEY); | |
391 | if (!callout_info) | |
392 | goto error; | |
393 | ||
394 | /* - get hold of the user's construction queue */ | |
395 | user = key_user_lookup(current->fsuid); | |
3e30148c DH |
396 | if (!user) |
397 | goto nomem; | |
398 | ||
664cceb0 | 399 | for (;;) { |
3e30148c DH |
400 | if (signal_pending(current)) |
401 | goto interrupted; | |
1da177e4 | 402 | |
1da177e4 LT |
403 | /* ask userspace (returns NULL if it waited on a key |
404 | * being constructed) */ | |
405 | key = request_key_construction(type, description, | |
406 | user, callout_info); | |
407 | if (key) | |
408 | break; | |
409 | ||
410 | /* someone else made the key we want, so we need to | |
411 | * search again as it might now be available to us */ | |
664cceb0 DH |
412 | key_ref = search_process_keyrings(type, description, |
413 | type->match, | |
414 | current); | |
415 | ||
416 | kdebug("search 2: %p", key_ref); | |
3e30148c | 417 | |
664cceb0 DH |
418 | if (!IS_ERR(key_ref)) { |
419 | key = key_ref_to_ptr(key_ref); | |
420 | break; | |
421 | } | |
422 | ||
423 | if (PTR_ERR(key_ref) != -EAGAIN) { | |
424 | key = ERR_PTR(PTR_ERR(key_ref)); | |
425 | break; | |
426 | } | |
427 | } | |
1da177e4 LT |
428 | |
429 | key_user_put(user); | |
3e30148c DH |
430 | |
431 | /* link the new key into the appropriate keyring */ | |
1260f801 | 432 | if (!IS_ERR(key)) |
3e30148c | 433 | request_key_link(key, dest_keyring); |
1da177e4 LT |
434 | } |
435 | ||
3e30148c DH |
436 | error: |
437 | kleave(" = %p", key); | |
1da177e4 LT |
438 | return key; |
439 | ||
3e30148c DH |
440 | nomem: |
441 | key = ERR_PTR(-ENOMEM); | |
442 | goto error; | |
443 | ||
444 | interrupted: | |
445 | key_user_put(user); | |
446 | key = ERR_PTR(-EINTR); | |
447 | goto error; | |
448 | ||
449 | } /* end request_key_and_link() */ | |
450 | ||
451 | /*****************************************************************************/ | |
452 | /* | |
453 | * request a key | |
454 | * - search the process's keyrings | |
455 | * - check the list of keys being created or updated | |
456 | * - call out to userspace for a key if supplementary info was provided | |
457 | */ | |
458 | struct key *request_key(struct key_type *type, | |
459 | const char *description, | |
460 | const char *callout_info) | |
461 | { | |
462 | return request_key_and_link(type, description, callout_info, NULL); | |
463 | ||
1da177e4 LT |
464 | } /* end request_key() */ |
465 | ||
466 | EXPORT_SYMBOL(request_key); | |
467 | ||
468 | /*****************************************************************************/ | |
469 | /* | |
470 | * validate a key | |
471 | */ | |
472 | int key_validate(struct key *key) | |
473 | { | |
474 | struct timespec now; | |
475 | int ret = 0; | |
476 | ||
477 | if (key) { | |
478 | /* check it's still accessible */ | |
479 | ret = -EKEYREVOKED; | |
76d8aeab DH |
480 | if (test_bit(KEY_FLAG_REVOKED, &key->flags) || |
481 | test_bit(KEY_FLAG_DEAD, &key->flags)) | |
1da177e4 LT |
482 | goto error; |
483 | ||
484 | /* check it hasn't expired */ | |
485 | ret = 0; | |
486 | if (key->expiry) { | |
487 | now = current_kernel_time(); | |
488 | if (now.tv_sec >= key->expiry) | |
489 | ret = -EKEYEXPIRED; | |
490 | } | |
491 | } | |
492 | ||
493 | error: | |
494 | return ret; | |
495 | ||
496 | } /* end key_validate() */ | |
497 | ||
498 | EXPORT_SYMBOL(key_validate); |