fsnotify: store struct file not struct path
[sfrench/cifs-2.6.git] / security / keys / request_key.c
1 /* Request a key from userspace
2  *
3  * Copyright (C) 2004-2007 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 License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  *
11  * See Documentation/keys-request-key.txt
12  */
13
14 #include <linux/module.h>
15 #include <linux/sched.h>
16 #include <linux/kmod.h>
17 #include <linux/err.h>
18 #include <linux/keyctl.h>
19 #include <linux/slab.h>
20 #include "internal.h"
21
22 #define key_negative_timeout    60      /* default timeout on a negative key's existence */
23
24 /*
25  * wait_on_bit() sleep function for uninterruptible waiting
26  */
27 static int key_wait_bit(void *flags)
28 {
29         schedule();
30         return 0;
31 }
32
33 /*
34  * wait_on_bit() sleep function for interruptible waiting
35  */
36 static int key_wait_bit_intr(void *flags)
37 {
38         schedule();
39         return signal_pending(current) ? -ERESTARTSYS : 0;
40 }
41
42 /*
43  * call to complete the construction of a key
44  */
45 void complete_request_key(struct key_construction *cons, int error)
46 {
47         kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error);
48
49         if (error < 0)
50                 key_negate_and_link(cons->key, key_negative_timeout, NULL,
51                                     cons->authkey);
52         else
53                 key_revoke(cons->authkey);
54
55         key_put(cons->key);
56         key_put(cons->authkey);
57         kfree(cons);
58 }
59 EXPORT_SYMBOL(complete_request_key);
60
61 static int umh_keys_init(struct subprocess_info *info)
62 {
63         struct cred *cred = (struct cred*)current_cred();
64         struct key *keyring = info->data;
65         /*
66          * This is called in context of freshly forked kthread before
67          * kernel_execve(), we can just change our ->session_keyring.
68          */
69         return install_session_keyring_to_cred(cred, keyring);
70 }
71
72 static void umh_keys_cleanup(struct subprocess_info *info)
73 {
74         struct key *keyring = info->data;
75         key_put(keyring);
76 }
77
78 static int call_usermodehelper_keys(char *path, char **argv, char **envp,
79                          struct key *session_keyring, enum umh_wait wait)
80 {
81         gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
82         struct subprocess_info *info =
83                 call_usermodehelper_setup(path, argv, envp, gfp_mask);
84
85         if (!info)
86                 return -ENOMEM;
87
88         call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
89                                         key_get(session_keyring));
90         return call_usermodehelper_exec(info, wait);
91 }
92
93 /*
94  * request userspace finish the construction of a key
95  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
96  */
97 static int call_sbin_request_key(struct key_construction *cons,
98                                  const char *op,
99                                  void *aux)
100 {
101         const struct cred *cred = current_cred();
102         key_serial_t prkey, sskey;
103         struct key *key = cons->key, *authkey = cons->authkey, *keyring,
104                 *session;
105         char *argv[9], *envp[3], uid_str[12], gid_str[12];
106         char key_str[12], keyring_str[3][12];
107         char desc[20];
108         int ret, i;
109
110         kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
111
112         ret = install_user_keyrings();
113         if (ret < 0)
114                 goto error_alloc;
115
116         /* allocate a new session keyring */
117         sprintf(desc, "_req.%u", key->serial);
118
119         cred = get_current_cred();
120         keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
121                                 KEY_ALLOC_QUOTA_OVERRUN, NULL);
122         put_cred(cred);
123         if (IS_ERR(keyring)) {
124                 ret = PTR_ERR(keyring);
125                 goto error_alloc;
126         }
127
128         /* attach the auth key to the session keyring */
129         ret = key_link(keyring, authkey);
130         if (ret < 0)
131                 goto error_link;
132
133         /* record the UID and GID */
134         sprintf(uid_str, "%d", cred->fsuid);
135         sprintf(gid_str, "%d", cred->fsgid);
136
137         /* we say which key is under construction */
138         sprintf(key_str, "%d", key->serial);
139
140         /* we specify the process's default keyrings */
141         sprintf(keyring_str[0], "%d",
142                 cred->thread_keyring ? cred->thread_keyring->serial : 0);
143
144         prkey = 0;
145         if (cred->tgcred->process_keyring)
146                 prkey = cred->tgcred->process_keyring->serial;
147
148         rcu_read_lock();
149         session = rcu_dereference(cred->tgcred->session_keyring);
150         if (!session)
151                 session = cred->user->session_keyring;
152         sskey = session->serial;
153         rcu_read_unlock();
154
155         sprintf(keyring_str[2], "%d", sskey);
156
157         /* set up a minimal environment */
158         i = 0;
159         envp[i++] = "HOME=/";
160         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
161         envp[i] = NULL;
162
163         /* set up the argument list */
164         i = 0;
165         argv[i++] = "/sbin/request-key";
166         argv[i++] = (char *) op;
167         argv[i++] = key_str;
168         argv[i++] = uid_str;
169         argv[i++] = gid_str;
170         argv[i++] = keyring_str[0];
171         argv[i++] = keyring_str[1];
172         argv[i++] = keyring_str[2];
173         argv[i] = NULL;
174
175         /* do it */
176         ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
177                                        UMH_WAIT_PROC);
178         kdebug("usermode -> 0x%x", ret);
179         if (ret >= 0) {
180                 /* ret is the exit/wait code */
181                 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
182                     key_validate(key) < 0)
183                         ret = -ENOKEY;
184                 else
185                         /* ignore any errors from userspace if the key was
186                          * instantiated */
187                         ret = 0;
188         }
189
190 error_link:
191         key_put(keyring);
192
193 error_alloc:
194         complete_request_key(cons, ret);
195         kleave(" = %d", ret);
196         return ret;
197 }
198
199 /*
200  * call out to userspace for key construction
201  * - we ignore program failure and go on key status instead
202  */
203 static int construct_key(struct key *key, const void *callout_info,
204                          size_t callout_len, void *aux,
205                          struct key *dest_keyring)
206 {
207         struct key_construction *cons;
208         request_key_actor_t actor;
209         struct key *authkey;
210         int ret;
211
212         kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
213
214         cons = kmalloc(sizeof(*cons), GFP_KERNEL);
215         if (!cons)
216                 return -ENOMEM;
217
218         /* allocate an authorisation key */
219         authkey = request_key_auth_new(key, callout_info, callout_len,
220                                        dest_keyring);
221         if (IS_ERR(authkey)) {
222                 kfree(cons);
223                 ret = PTR_ERR(authkey);
224                 authkey = NULL;
225         } else {
226                 cons->authkey = key_get(authkey);
227                 cons->key = key_get(key);
228
229                 /* make the call */
230                 actor = call_sbin_request_key;
231                 if (key->type->request_key)
232                         actor = key->type->request_key;
233
234                 ret = actor(cons, "create", aux);
235
236                 /* check that the actor called complete_request_key() prior to
237                  * returning an error */
238                 WARN_ON(ret < 0 &&
239                         !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
240                 key_put(authkey);
241         }
242
243         kleave(" = %d", ret);
244         return ret;
245 }
246
247 /*
248  * get the appropriate destination keyring for the request
249  * - we return whatever keyring we select with an extra reference upon it which
250  *   the caller must release
251  */
252 static void construct_get_dest_keyring(struct key **_dest_keyring)
253 {
254         struct request_key_auth *rka;
255         const struct cred *cred = current_cred();
256         struct key *dest_keyring = *_dest_keyring, *authkey;
257
258         kenter("%p", dest_keyring);
259
260         /* find the appropriate keyring */
261         if (dest_keyring) {
262                 /* the caller supplied one */
263                 key_get(dest_keyring);
264         } else {
265                 /* use a default keyring; falling through the cases until we
266                  * find one that we actually have */
267                 switch (cred->jit_keyring) {
268                 case KEY_REQKEY_DEFL_DEFAULT:
269                 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
270                         if (cred->request_key_auth) {
271                                 authkey = cred->request_key_auth;
272                                 down_read(&authkey->sem);
273                                 rka = authkey->payload.data;
274                                 if (!test_bit(KEY_FLAG_REVOKED,
275                                               &authkey->flags))
276                                         dest_keyring =
277                                                 key_get(rka->dest_keyring);
278                                 up_read(&authkey->sem);
279                                 if (dest_keyring)
280                                         break;
281                         }
282
283                 case KEY_REQKEY_DEFL_THREAD_KEYRING:
284                         dest_keyring = key_get(cred->thread_keyring);
285                         if (dest_keyring)
286                                 break;
287
288                 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
289                         dest_keyring = key_get(cred->tgcred->process_keyring);
290                         if (dest_keyring)
291                                 break;
292
293                 case KEY_REQKEY_DEFL_SESSION_KEYRING:
294                         rcu_read_lock();
295                         dest_keyring = key_get(
296                                 rcu_dereference(cred->tgcred->session_keyring));
297                         rcu_read_unlock();
298
299                         if (dest_keyring)
300                                 break;
301
302                 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
303                         dest_keyring =
304                                 key_get(cred->user->session_keyring);
305                         break;
306
307                 case KEY_REQKEY_DEFL_USER_KEYRING:
308                         dest_keyring = key_get(cred->user->uid_keyring);
309                         break;
310
311                 case KEY_REQKEY_DEFL_GROUP_KEYRING:
312                 default:
313                         BUG();
314                 }
315         }
316
317         *_dest_keyring = dest_keyring;
318         kleave(" [dk %d]", key_serial(dest_keyring));
319         return;
320 }
321
322 /*
323  * allocate a new key in under-construction state and attempt to link it in to
324  * the requested place
325  * - may return a key that's already under construction instead
326  */
327 static int construct_alloc_key(struct key_type *type,
328                                const char *description,
329                                struct key *dest_keyring,
330                                unsigned long flags,
331                                struct key_user *user,
332                                struct key **_key)
333 {
334         struct keyring_list *prealloc;
335         const struct cred *cred = current_cred();
336         struct key *key;
337         key_ref_t key_ref;
338         int ret;
339
340         kenter("%s,%s,,,", type->name, description);
341
342         *_key = NULL;
343         mutex_lock(&user->cons_lock);
344
345         key = key_alloc(type, description, cred->fsuid, cred->fsgid, cred,
346                         KEY_POS_ALL, flags);
347         if (IS_ERR(key))
348                 goto alloc_failed;
349
350         set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
351
352         if (dest_keyring) {
353                 ret = __key_link_begin(dest_keyring, type, description,
354                                        &prealloc);
355                 if (ret < 0)
356                         goto link_prealloc_failed;
357         }
358
359         /* attach the key to the destination keyring under lock, but we do need
360          * to do another check just in case someone beat us to it whilst we
361          * waited for locks */
362         mutex_lock(&key_construction_mutex);
363
364         key_ref = search_process_keyrings(type, description, type->match, cred);
365         if (!IS_ERR(key_ref))
366                 goto key_already_present;
367
368         if (dest_keyring)
369                 __key_link(dest_keyring, key, &prealloc);
370
371         mutex_unlock(&key_construction_mutex);
372         if (dest_keyring)
373                 __key_link_end(dest_keyring, type, prealloc);
374         mutex_unlock(&user->cons_lock);
375         *_key = key;
376         kleave(" = 0 [%d]", key_serial(key));
377         return 0;
378
379         /* the key is now present - we tell the caller that we found it by
380          * returning -EINPROGRESS  */
381 key_already_present:
382         key_put(key);
383         mutex_unlock(&key_construction_mutex);
384         key = key_ref_to_ptr(key_ref);
385         if (dest_keyring) {
386                 ret = __key_link_check_live_key(dest_keyring, key);
387                 if (ret == 0)
388                         __key_link(dest_keyring, key, &prealloc);
389                 __key_link_end(dest_keyring, type, prealloc);
390                 if (ret < 0)
391                         goto link_check_failed;
392         }
393         mutex_unlock(&user->cons_lock);
394         *_key = key;
395         kleave(" = -EINPROGRESS [%d]", key_serial(key));
396         return -EINPROGRESS;
397
398 link_check_failed:
399         mutex_unlock(&user->cons_lock);
400         key_put(key);
401         kleave(" = %d [linkcheck]", ret);
402         return ret;
403
404 link_prealloc_failed:
405         up_write(&dest_keyring->sem);
406         mutex_unlock(&user->cons_lock);
407         kleave(" = %d [prelink]", ret);
408         return ret;
409
410 alloc_failed:
411         mutex_unlock(&user->cons_lock);
412         kleave(" = %ld", PTR_ERR(key));
413         return PTR_ERR(key);
414 }
415
416 /*
417  * commence key construction
418  */
419 static struct key *construct_key_and_link(struct key_type *type,
420                                           const char *description,
421                                           const char *callout_info,
422                                           size_t callout_len,
423                                           void *aux,
424                                           struct key *dest_keyring,
425                                           unsigned long flags)
426 {
427         struct key_user *user;
428         struct key *key;
429         int ret;
430
431         kenter("");
432
433         user = key_user_lookup(current_fsuid(), current_user_ns());
434         if (!user)
435                 return ERR_PTR(-ENOMEM);
436
437         construct_get_dest_keyring(&dest_keyring);
438
439         ret = construct_alloc_key(type, description, dest_keyring, flags, user,
440                                   &key);
441         key_user_put(user);
442
443         if (ret == 0) {
444                 ret = construct_key(key, callout_info, callout_len, aux,
445                                     dest_keyring);
446                 if (ret < 0) {
447                         kdebug("cons failed");
448                         goto construction_failed;
449                 }
450         } else if (ret == -EINPROGRESS) {
451                 ret = 0;
452         } else {
453                 key = ERR_PTR(ret);
454         }
455
456         key_put(dest_keyring);
457         kleave(" = key %d", key_serial(key));
458         return key;
459
460 construction_failed:
461         key_negate_and_link(key, key_negative_timeout, NULL, NULL);
462         key_put(key);
463         key_put(dest_keyring);
464         kleave(" = %d", ret);
465         return ERR_PTR(ret);
466 }
467
468 /*
469  * request a key
470  * - search the process's keyrings
471  * - check the list of keys being created or updated
472  * - call out to userspace for a key if supplementary info was provided
473  * - cache the key in an appropriate keyring
474  */
475 struct key *request_key_and_link(struct key_type *type,
476                                  const char *description,
477                                  const void *callout_info,
478                                  size_t callout_len,
479                                  void *aux,
480                                  struct key *dest_keyring,
481                                  unsigned long flags)
482 {
483         const struct cred *cred = current_cred();
484         struct key *key;
485         key_ref_t key_ref;
486         int ret;
487
488         kenter("%s,%s,%p,%zu,%p,%p,%lx",
489                type->name, description, callout_info, callout_len, aux,
490                dest_keyring, flags);
491
492         /* search all the process keyrings for a key */
493         key_ref = search_process_keyrings(type, description, type->match,
494                                           cred);
495
496         if (!IS_ERR(key_ref)) {
497                 key = key_ref_to_ptr(key_ref);
498                 if (dest_keyring) {
499                         construct_get_dest_keyring(&dest_keyring);
500                         ret = key_link(dest_keyring, key);
501                         key_put(dest_keyring);
502                         if (ret < 0) {
503                                 key_put(key);
504                                 key = ERR_PTR(ret);
505                                 goto error;
506                         }
507                 }
508         } else if (PTR_ERR(key_ref) != -EAGAIN) {
509                 key = ERR_CAST(key_ref);
510         } else  {
511                 /* the search failed, but the keyrings were searchable, so we
512                  * should consult userspace if we can */
513                 key = ERR_PTR(-ENOKEY);
514                 if (!callout_info)
515                         goto error;
516
517                 key = construct_key_and_link(type, description, callout_info,
518                                              callout_len, aux, dest_keyring,
519                                              flags);
520         }
521
522 error:
523         kleave(" = %p", key);
524         return key;
525 }
526
527 /*
528  * wait for construction of a key to complete
529  */
530 int wait_for_key_construction(struct key *key, bool intr)
531 {
532         int ret;
533
534         ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
535                           intr ? key_wait_bit_intr : key_wait_bit,
536                           intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
537         if (ret < 0)
538                 return ret;
539         return key_validate(key);
540 }
541 EXPORT_SYMBOL(wait_for_key_construction);
542
543 /*
544  * request a key
545  * - search the process's keyrings
546  * - check the list of keys being created or updated
547  * - call out to userspace for a key if supplementary info was provided
548  * - waits uninterruptible for creation to complete
549  */
550 struct key *request_key(struct key_type *type,
551                         const char *description,
552                         const char *callout_info)
553 {
554         struct key *key;
555         size_t callout_len = 0;
556         int ret;
557
558         if (callout_info)
559                 callout_len = strlen(callout_info);
560         key = request_key_and_link(type, description, callout_info, callout_len,
561                                    NULL, NULL, KEY_ALLOC_IN_QUOTA);
562         if (!IS_ERR(key)) {
563                 ret = wait_for_key_construction(key, false);
564                 if (ret < 0) {
565                         key_put(key);
566                         return ERR_PTR(ret);
567                 }
568         }
569         return key;
570 }
571 EXPORT_SYMBOL(request_key);
572
573 /*
574  * request a key with auxiliary data for the upcaller
575  * - search the process's keyrings
576  * - check the list of keys being created or updated
577  * - call out to userspace for a key if supplementary info was provided
578  * - waits uninterruptible for creation to complete
579  */
580 struct key *request_key_with_auxdata(struct key_type *type,
581                                      const char *description,
582                                      const void *callout_info,
583                                      size_t callout_len,
584                                      void *aux)
585 {
586         struct key *key;
587         int ret;
588
589         key = request_key_and_link(type, description, callout_info, callout_len,
590                                    aux, NULL, KEY_ALLOC_IN_QUOTA);
591         if (!IS_ERR(key)) {
592                 ret = wait_for_key_construction(key, false);
593                 if (ret < 0) {
594                         key_put(key);
595                         return ERR_PTR(ret);
596                 }
597         }
598         return key;
599 }
600 EXPORT_SYMBOL(request_key_with_auxdata);
601
602 /*
603  * request a key (allow async construction)
604  * - search the process's keyrings
605  * - check the list of keys being created or updated
606  * - call out to userspace for a key if supplementary info was provided
607  */
608 struct key *request_key_async(struct key_type *type,
609                               const char *description,
610                               const void *callout_info,
611                               size_t callout_len)
612 {
613         return request_key_and_link(type, description, callout_info,
614                                     callout_len, NULL, NULL,
615                                     KEY_ALLOC_IN_QUOTA);
616 }
617 EXPORT_SYMBOL(request_key_async);
618
619 /*
620  * request a key with auxiliary data for the upcaller (allow async construction)
621  * - search the process's keyrings
622  * - check the list of keys being created or updated
623  * - call out to userspace for a key if supplementary info was provided
624  */
625 struct key *request_key_async_with_auxdata(struct key_type *type,
626                                            const char *description,
627                                            const void *callout_info,
628                                            size_t callout_len,
629                                            void *aux)
630 {
631         return request_key_and_link(type, description, callout_info,
632                                     callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
633 }
634 EXPORT_SYMBOL(request_key_async_with_auxdata);