1 /* -*- mode: C; c-file-style: "gnu" -*- */
2 /* dbus-keyring.c Store secret cookies in your homedir
3 *
4 * Copyright (C) 2003, 2004 Red Hat Inc.
5 *
6 * Licensed under the Academic Free License version 2.1
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 *
22 */
23
24 #include "dbus-keyring.h"
25 #include "dbus-userdb.h"
26 #include "dbus-protocol.h"
27 #include <dbus/dbus-string.h>
28 #include <dbus/dbus-list.h>
29 #include <dbus/dbus-sysdeps.h>
30
31 /**
32 * @defgroup DBusKeyring keyring class
33 * @ingroup DBusInternals
34 * @brief DBusKeyring data structure
35 *
36 * Types and functions related to DBusKeyring. DBusKeyring is intended
37 * to manage cookies used to authenticate clients to servers. This is
38 * essentially the "verify that client can read the user's homedir"
39 * authentication mechanism. Both client and server must have access
40 * to the homedir.
41 *
42 * The secret keys are not kept in locked memory, and are written to a
43 * file in the user's homedir. However they are transient (only used
44 * by a single server instance for a fixed period of time, then
45 * discarded). Also, the keys are not sent over the wire.
46 *
47 * @todo there's a memory leak on some codepath in here, I saw it once
48 * when running make check - probably some specific initial cookies
49 * present in the cookie file, then depending on what we do with them.
50 */
51
52 /**
53 * @defgroup DBusKeyringInternals DBusKeyring implementation details
54 * @ingroup DBusInternals
55 * @brief DBusKeyring implementation details
56 *
57 * The guts of DBusKeyring.
58 *
59 * @{
60 */
61
62 /** The maximum age of a key before we create a new key to use in
63 * challenges. This isn't super-reliably enforced, since system
64 * clocks can change or be wrong, but we make a best effort to only
65 * use keys for a short time.
66 */
67 #define NEW_KEY_TIMEOUT_SECONDS (60*5)
68 /**
69 * The time after which we drop a key from the secrets file.
70 * The EXPIRE_KEYS_TIMEOUT_SECONDS - NEW_KEY_TIMEOUT_SECONDS is the minimum
71 * time window a client has to complete authentication.
72 */
73 #define EXPIRE_KEYS_TIMEOUT_SECONDS (NEW_KEY_TIMEOUT_SECONDS + (60*2))
74 /**
75 * The maximum amount of time a key can be in the future.
76 */
77 #define MAX_TIME_TRAVEL_SECONDS (60*5)
78
79 /**
80 * Maximum number of keys in the keyring before
81 * we just ignore the rest
82 */
83 #ifdef DBUS_BUILD_TESTS
84 #define MAX_KEYS_IN_FILE 10
85 #else
86 #define MAX_KEYS_IN_FILE 256
87 #endif
88
89 /**
90 * A single key from the cookie file
91 */
92 typedef struct
93 {
94 dbus_int32_t id; /**< identifier used to refer to the key */
95
96 long creation_time; /**< when the key was generated,
97 * as unix timestamp. signed long
98 * matches struct timeval.
99 */
100
101 DBusString secret; /**< the actual key */
102
103 } DBusKey;
104
105 /**
106 * @brief Internals of DBusKeyring.
107 *
108 * DBusKeyring internals. DBusKeyring is an opaque object, it must be
109 * used via accessor functions.
110 */
111 struct DBusKeyring
112 {
113 int refcount; /**< Reference count */
114 DBusString username; /**< Username keyring is for */
115 DBusString directory; /**< Directory the below two items are inside */
116 DBusString filename; /**< Keyring filename */
117 DBusString filename_lock; /**< Name of lockfile */
118 DBusKey *keys; /**< Keys loaded from the file */
119 int n_keys; /**< Number of keys */
120 };
121
122 static DBusKeyring*
_dbus_keyring_new(void)123 _dbus_keyring_new (void)
124 {
125 DBusKeyring *keyring;
126
127 keyring = dbus_new0 (DBusKeyring, 1);
128 if (keyring == NULL)
129 goto out_0;
130
131 if (!_dbus_string_init (&keyring->directory))
132 goto out_1;
133
134 if (!_dbus_string_init (&keyring->filename))
135 goto out_2;
136
137 if (!_dbus_string_init (&keyring->filename_lock))
138 goto out_3;
139
140 if (!_dbus_string_init (&keyring->username))
141 goto out_4;
142
143 keyring->refcount = 1;
144 keyring->keys = NULL;
145 keyring->n_keys = 0;
146
147 return keyring;
148
149 out_4:
150 _dbus_string_free (&keyring->filename_lock);
151 out_3:
152 _dbus_string_free (&keyring->filename);
153 out_2:
154 _dbus_string_free (&keyring->directory);
155 out_1:
156 dbus_free (keyring);
157 out_0:
158 return NULL;
159 }
160
161 static void
free_keys(DBusKey * keys,int n_keys)162 free_keys (DBusKey *keys,
163 int n_keys)
164 {
165 int i;
166
167 /* should be safe for args NULL, 0 */
168
169 i = 0;
170 while (i < n_keys)
171 {
172 _dbus_string_free (&keys[i].secret);
173 ++i;
174 }
175
176 dbus_free (keys);
177 }
178
179 /* Our locking scheme is highly unreliable. However, there is
180 * unfortunately no reliable locking scheme in user home directories;
181 * between bugs in Linux NFS, people using Tru64 or other total crap
182 * NFS, AFS, random-file-system-of-the-week, and so forth, fcntl() in
183 * homedirs simply generates tons of bug reports. This has been
184 * learned through hard experience with GConf, unfortunately.
185 *
186 * This bad hack might work better for the kind of lock we have here,
187 * which we don't expect to hold for any length of time. Crashing
188 * while we hold it should be unlikely, and timing out such that we
189 * delete a stale lock should also be unlikely except when the
190 * filesystem is running really slowly. Stuff might break in corner
191 * cases but as long as it's not a security-level breakage it should
192 * be OK.
193 */
194
195 /** Maximum number of timeouts waiting for lock before we decide it's stale */
196 #define MAX_LOCK_TIMEOUTS 32
197 /** Length of each timeout while waiting for a lock */
198 #define LOCK_TIMEOUT_MILLISECONDS 250
199
200 static dbus_bool_t
_dbus_keyring_lock(DBusKeyring * keyring)201 _dbus_keyring_lock (DBusKeyring *keyring)
202 {
203 int n_timeouts;
204
205 n_timeouts = 0;
206 while (n_timeouts < MAX_LOCK_TIMEOUTS)
207 {
208 DBusError error;
209
210 dbus_error_init (&error);
211 if (_dbus_create_file_exclusively (&keyring->filename_lock,
212 &error))
213 break;
214
215 _dbus_verbose ("Did not get lock file, sleeping %d milliseconds (%s)\n",
216 LOCK_TIMEOUT_MILLISECONDS, error.message);
217 dbus_error_free (&error);
218
219 _dbus_sleep_milliseconds (LOCK_TIMEOUT_MILLISECONDS);
220
221 ++n_timeouts;
222 }
223
224 if (n_timeouts == MAX_LOCK_TIMEOUTS)
225 {
226 DBusError error;
227
228 _dbus_verbose ("Lock file timed out %d times, assuming stale\n",
229 n_timeouts);
230
231 dbus_error_init (&error);
232
233 if (!_dbus_delete_file (&keyring->filename_lock, &error))
234 {
235 _dbus_verbose ("Couldn't delete old lock file: %s\n",
236 error.message);
237 dbus_error_free (&error);
238 return FALSE;
239 }
240
241 if (!_dbus_create_file_exclusively (&keyring->filename_lock,
242 &error))
243 {
244 _dbus_verbose ("Couldn't create lock file after deleting stale one: %s\n",
245 error.message);
246 dbus_error_free (&error);
247 return FALSE;
248 }
249 }
250
251 return TRUE;
252 }
253
254 static void
_dbus_keyring_unlock(DBusKeyring * keyring)255 _dbus_keyring_unlock (DBusKeyring *keyring)
256 {
257 DBusError error;
258 dbus_error_init (&error);
259 if (!_dbus_delete_file (&keyring->filename_lock, &error))
260 {
261 _dbus_warn ("Failed to delete lock file: %s\n",
262 error.message);
263 dbus_error_free (&error);
264 }
265 }
266
267 static DBusKey*
find_key_by_id(DBusKey * keys,int n_keys,int id)268 find_key_by_id (DBusKey *keys,
269 int n_keys,
270 int id)
271 {
272 int i;
273
274 i = 0;
275 while (i < n_keys)
276 {
277 if (keys[i].id == id)
278 return &keys[i];
279
280 ++i;
281 }
282
283 return NULL;
284 }
285
286 static dbus_bool_t
add_new_key(DBusKey ** keys_p,int * n_keys_p,DBusError * error)287 add_new_key (DBusKey **keys_p,
288 int *n_keys_p,
289 DBusError *error)
290 {
291 DBusKey *new;
292 DBusString bytes;
293 int id;
294 long timestamp;
295 const unsigned char *s;
296 dbus_bool_t retval;
297 DBusKey *keys;
298 int n_keys;
299
300 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
301
302 if (!_dbus_string_init (&bytes))
303 {
304 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
305 return FALSE;
306 }
307
308 keys = *keys_p;
309 n_keys = *n_keys_p;
310 retval = FALSE;
311
312 /* Generate an integer ID and then the actual key. */
313 retry:
314
315 if (!_dbus_generate_random_bytes (&bytes, 4))
316 {
317 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
318 goto out;
319 }
320
321 s = (const unsigned char*) _dbus_string_get_const_data (&bytes);
322
323 id = s[0] | (s[1] << 8) | (s[2] << 16) | (s[3] << 24);
324 if (id < 0)
325 id = - id;
326 _dbus_assert (id >= 0);
327
328 if (find_key_by_id (keys, n_keys, id) != NULL)
329 {
330 _dbus_string_set_length (&bytes, 0);
331 _dbus_verbose ("Key ID %d already existed, trying another one\n",
332 id);
333 goto retry;
334 }
335
336 _dbus_verbose ("Creating key with ID %d\n", id);
337
338 #define KEY_LENGTH_BYTES 24
339 _dbus_string_set_length (&bytes, 0);
340 if (!_dbus_generate_random_bytes (&bytes, KEY_LENGTH_BYTES))
341 {
342 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
343 goto out;
344 }
345
346 new = dbus_realloc (keys, sizeof (DBusKey) * (n_keys + 1));
347 if (new == NULL)
348 {
349 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
350 goto out;
351 }
352
353 keys = new;
354 *keys_p = keys; /* otherwise *keys_p ends up invalid */
355 n_keys += 1;
356
357 if (!_dbus_string_init (&keys[n_keys-1].secret))
358 {
359 n_keys -= 1; /* we don't want to free the one we didn't init */
360 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
361 goto out;
362 }
363
364 _dbus_get_current_time (×tamp, NULL);
365
366 keys[n_keys-1].id = id;
367 keys[n_keys-1].creation_time = timestamp;
368 if (!_dbus_string_move (&bytes, 0,
369 &keys[n_keys-1].secret,
370 0))
371 {
372 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
373 _dbus_string_free (&keys[n_keys-1].secret);
374 n_keys -= 1;
375 goto out;
376 }
377
378 retval = TRUE;
379
380 out:
381 *n_keys_p = n_keys;
382
383 _dbus_string_free (&bytes);
384 return retval;
385 }
386
387 /**
388 * Reloads the keyring file, optionally adds one new key to the file,
389 * removes all expired keys from the file iff a key was added, then
390 * resaves the file. Stores the keys from the file in keyring->keys.
391 * Note that the file is only resaved (written to) if a key is added,
392 * this means that only servers ever write to the file and need to
393 * lock it, which avoids a lot of lock contention at login time and
394 * such.
395 *
396 * @param keyring the keyring
397 * @param add_new #TRUE to add a new key to the file, expire keys, and resave
398 * @param error return location for errors
399 * @returns #FALSE on failure
400 */
401 static dbus_bool_t
_dbus_keyring_reload(DBusKeyring * keyring,dbus_bool_t add_new,DBusError * error)402 _dbus_keyring_reload (DBusKeyring *keyring,
403 dbus_bool_t add_new,
404 DBusError *error)
405 {
406 DBusString contents;
407 DBusString line;
408 dbus_bool_t retval;
409 dbus_bool_t have_lock;
410 DBusKey *keys;
411 int n_keys;
412 int i;
413 long now;
414 DBusError tmp_error;
415
416 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
417
418 if (!_dbus_check_dir_is_private_to_user (&keyring->directory, error))
419 return FALSE;
420
421 if (!_dbus_string_init (&contents))
422 {
423 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
424 return FALSE;
425 }
426
427 if (!_dbus_string_init (&line))
428 {
429 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
430 _dbus_string_free (&contents);
431 return FALSE;
432 }
433
434 keys = NULL;
435 n_keys = 0;
436 retval = FALSE;
437 have_lock = FALSE;
438
439 _dbus_get_current_time (&now, NULL);
440
441 if (add_new)
442 {
443 if (!_dbus_keyring_lock (keyring))
444 {
445 dbus_set_error (error, DBUS_ERROR_FAILED,
446 "Could not lock keyring file to add to it");
447 goto out;
448 }
449
450 have_lock = TRUE;
451 }
452
453 dbus_error_init (&tmp_error);
454 if (!_dbus_file_get_contents (&contents,
455 &keyring->filename,
456 &tmp_error))
457 {
458 _dbus_verbose ("Failed to load keyring file: %s\n",
459 tmp_error.message);
460 /* continue with empty keyring file, so we recreate it */
461 dbus_error_free (&tmp_error);
462 }
463
464 if (!_dbus_string_validate_ascii (&contents, 0,
465 _dbus_string_get_length (&contents)))
466 {
467 _dbus_warn ("Secret keyring file contains non-ASCII! Ignoring existing contents\n");
468 _dbus_string_set_length (&contents, 0);
469 }
470
471 /* FIXME this is badly inefficient for large keyring files
472 * (not that large keyring files exist outside of test suites)
473 */
474 while (_dbus_string_pop_line (&contents, &line))
475 {
476 int next;
477 long val;
478 int id;
479 long timestamp;
480 int len;
481 int end;
482 DBusKey *new;
483
484 /* Don't load more than the max. */
485 if (n_keys >= (add_new ? MAX_KEYS_IN_FILE - 1 : MAX_KEYS_IN_FILE))
486 break;
487
488 next = 0;
489 if (!_dbus_string_parse_int (&line, 0, &val, &next))
490 {
491 _dbus_verbose ("could not parse secret key ID at start of line\n");
492 continue;
493 }
494
495 if (val > _DBUS_INT32_MAX || val < 0)
496 {
497 _dbus_verbose ("invalid secret key ID at start of line\n");
498 continue;
499 }
500
501 id = val;
502
503 _dbus_string_skip_blank (&line, next, &next);
504
505 if (!_dbus_string_parse_int (&line, next, ×tamp, &next))
506 {
507 _dbus_verbose ("could not parse secret key timestamp\n");
508 continue;
509 }
510
511 if (timestamp < 0 ||
512 (now + MAX_TIME_TRAVEL_SECONDS) < timestamp ||
513 (now - EXPIRE_KEYS_TIMEOUT_SECONDS) > timestamp)
514 {
515 _dbus_verbose ("dropping/ignoring %ld-seconds old key with timestamp %ld as current time is %ld\n",
516 now - timestamp, timestamp, now);
517 continue;
518 }
519
520 _dbus_string_skip_blank (&line, next, &next);
521
522 len = _dbus_string_get_length (&line);
523
524 if ((len - next) == 0)
525 {
526 _dbus_verbose ("no secret key after ID and timestamp\n");
527 continue;
528 }
529
530 /* We have all three parts */
531 new = dbus_realloc (keys, sizeof (DBusKey) * (n_keys + 1));
532 if (new == NULL)
533 {
534 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
535 goto out;
536 }
537
538 keys = new;
539 n_keys += 1;
540
541 if (!_dbus_string_init (&keys[n_keys-1].secret))
542 {
543 n_keys -= 1; /* we don't want to free the one we didn't init */
544 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
545 goto out;
546 }
547
548 keys[n_keys-1].id = id;
549 keys[n_keys-1].creation_time = timestamp;
550 if (!_dbus_string_hex_decode (&line, next, &end,
551 &keys[n_keys-1].secret, 0))
552 {
553 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
554 goto out;
555 }
556
557 if (_dbus_string_get_length (&line) != end)
558 {
559 _dbus_verbose ("invalid hex encoding in keyring file\n");
560 _dbus_string_free (&keys[n_keys - 1].secret);
561 n_keys -= 1;
562 continue;
563 }
564 }
565
566 _dbus_verbose ("Successfully loaded %d existing keys\n",
567 n_keys);
568
569 if (add_new)
570 {
571 if (!add_new_key (&keys, &n_keys, error))
572 {
573 _dbus_verbose ("Failed to generate new key: %s\n",
574 error ? error->message : "(unknown)");
575 goto out;
576 }
577
578 _dbus_string_set_length (&contents, 0);
579
580 i = 0;
581 while (i < n_keys)
582 {
583 if (!_dbus_string_append_int (&contents,
584 keys[i].id))
585 goto nomem;
586
587 if (!_dbus_string_append_byte (&contents, ' '))
588 goto nomem;
589
590 if (!_dbus_string_append_int (&contents,
591 keys[i].creation_time))
592 goto nomem;
593
594 if (!_dbus_string_append_byte (&contents, ' '))
595 goto nomem;
596
597 if (!_dbus_string_hex_encode (&keys[i].secret, 0,
598 &contents,
599 _dbus_string_get_length (&contents)))
600 goto nomem;
601
602 if (!_dbus_string_append_byte (&contents, '\n'))
603 goto nomem;
604
605 ++i;
606 continue;
607
608 nomem:
609 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
610 goto out;
611 }
612
613 if (!_dbus_string_save_to_file (&contents, &keyring->filename,
614 error))
615 goto out;
616 }
617
618 if (keyring->keys)
619 free_keys (keyring->keys, keyring->n_keys);
620 keyring->keys = keys;
621 keyring->n_keys = n_keys;
622 keys = NULL;
623 n_keys = 0;
624
625 retval = TRUE;
626
627 out:
628 if (have_lock)
629 _dbus_keyring_unlock (keyring);
630
631 if (! ((retval == TRUE && (error == NULL || error->name == NULL)) ||
632 (retval == FALSE && (error == NULL || error->name != NULL))))
633 {
634 if (error && error->name)
635 _dbus_verbose ("error is %s: %s\n", error->name, error->message);
636 _dbus_warn ("returning %d but error pointer %p name %s\n",
637 retval, error, error->name ? error->name : "(none)");
638 _dbus_assert_not_reached ("didn't handle errors properly");
639 }
640
641 if (keys != NULL)
642 {
643 i = 0;
644 while (i < n_keys)
645 {
646 _dbus_string_zero (&keys[i].secret);
647 _dbus_string_free (&keys[i].secret);
648 ++i;
649 }
650
651 dbus_free (keys);
652 }
653
654 _dbus_string_free (&contents);
655 _dbus_string_free (&line);
656
657 return retval;
658 }
659
660 /** @} */ /* end of internals */
661
662 /**
663 * @addtogroup DBusKeyring
664 *
665 * @{
666 */
667
668 /**
669 * Increments reference count of the keyring
670 *
671 * @param keyring the keyring
672 * @returns the keyring
673 */
674 DBusKeyring *
_dbus_keyring_ref(DBusKeyring * keyring)675 _dbus_keyring_ref (DBusKeyring *keyring)
676 {
677 keyring->refcount += 1;
678
679 return keyring;
680 }
681
682 /**
683 * Decrements refcount and finalizes if it reaches
684 * zero.
685 *
686 * @param keyring the keyring
687 */
688 void
_dbus_keyring_unref(DBusKeyring * keyring)689 _dbus_keyring_unref (DBusKeyring *keyring)
690 {
691 keyring->refcount -= 1;
692
693 if (keyring->refcount == 0)
694 {
695 _dbus_string_free (&keyring->username);
696 _dbus_string_free (&keyring->filename);
697 _dbus_string_free (&keyring->filename_lock);
698 _dbus_string_free (&keyring->directory);
699 free_keys (keyring->keys, keyring->n_keys);
700 dbus_free (keyring);
701 }
702 }
703
704 /**
705 * Creates a new keyring that lives in the ~/.dbus-keyrings
706 * directory of the given user. If the username is #NULL,
707 * uses the user owning the current process.
708 *
709 * @param username username to get keyring for, or #NULL
710 * @param context which keyring to get
711 * @param error return location for errors
712 * @returns the keyring or #NULL on error
713 */
714 DBusKeyring*
_dbus_keyring_new_homedir(const DBusString * username,const DBusString * context,DBusError * error)715 _dbus_keyring_new_homedir (const DBusString *username,
716 const DBusString *context,
717 DBusError *error)
718 {
719 DBusString homedir;
720 DBusKeyring *keyring;
721 dbus_bool_t error_set;
722 DBusString dotdir;
723 DBusError tmp_error;
724
725 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
726
727 keyring = NULL;
728 error_set = FALSE;
729
730 if (!_dbus_string_init (&homedir))
731 {
732 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
733 return NULL;
734 }
735
736 _dbus_string_init_const (&dotdir, ".dbus-keyrings");
737
738 if (username == NULL)
739 {
740 const DBusString *const_homedir;
741
742 if (!_dbus_username_from_current_process (&username) ||
743 !_dbus_homedir_from_current_process (&const_homedir))
744 goto failed;
745
746 if (!_dbus_string_copy (const_homedir, 0,
747 &homedir, 0))
748 goto failed;
749 }
750 else
751 {
752 if (!_dbus_homedir_from_username (username, &homedir))
753 goto failed;
754 }
755
756 #ifdef DBUS_BUILD_TESTS
757 {
758 const char *override;
759
760 override = _dbus_getenv ("DBUS_TEST_HOMEDIR");
761 if (override != NULL && *override != '\0')
762 {
763 _dbus_string_set_length (&homedir, 0);
764 if (!_dbus_string_append (&homedir, override))
765 goto failed;
766
767 _dbus_verbose ("Using fake homedir for testing: %s\n",
768 _dbus_string_get_const_data (&homedir));
769 }
770 else
771 {
772 static dbus_bool_t already_warned = FALSE;
773 if (!already_warned)
774 {
775 _dbus_warn ("Using your real home directory for testing, set DBUS_TEST_HOMEDIR to avoid\n");
776 already_warned = TRUE;
777 }
778 }
779 }
780 #endif
781
782 _dbus_assert (username != NULL);
783
784 keyring = _dbus_keyring_new ();
785 if (keyring == NULL)
786 goto failed;
787
788 /* should have been validated already, but paranoia check here */
789 if (!_dbus_keyring_validate_context (context))
790 {
791 error_set = TRUE;
792 dbus_set_error_const (error,
793 DBUS_ERROR_FAILED,
794 "Invalid context in keyring creation");
795 goto failed;
796 }
797
798 if (!_dbus_string_copy (username, 0,
799 &keyring->username, 0))
800 goto failed;
801
802 if (!_dbus_string_copy (&homedir, 0,
803 &keyring->directory, 0))
804 goto failed;
805
806 if (!_dbus_concat_dir_and_file (&keyring->directory,
807 &dotdir))
808 goto failed;
809
810 if (!_dbus_string_copy (&keyring->directory, 0,
811 &keyring->filename, 0))
812 goto failed;
813
814 if (!_dbus_concat_dir_and_file (&keyring->filename,
815 context))
816 goto failed;
817
818 if (!_dbus_string_copy (&keyring->filename, 0,
819 &keyring->filename_lock, 0))
820 goto failed;
821
822 if (!_dbus_string_append (&keyring->filename_lock, ".lock"))
823 goto failed;
824
825 dbus_error_init (&tmp_error);
826 if (!_dbus_keyring_reload (keyring, FALSE, &tmp_error))
827 {
828 _dbus_verbose ("didn't load an existing keyring: %s\n",
829 tmp_error.message);
830 dbus_error_free (&tmp_error);
831 }
832
833 /* We don't fail fatally if we can't create the directory,
834 * but the keyring will probably always be empty
835 * unless someone else manages to create it
836 */
837 dbus_error_init (&tmp_error);
838 if (!_dbus_create_directory (&keyring->directory,
839 &tmp_error))
840 {
841 _dbus_verbose ("Creating keyring directory: %s\n",
842 tmp_error.message);
843 dbus_error_free (&tmp_error);
844 }
845
846 _dbus_string_free (&homedir);
847
848 return keyring;
849
850 failed:
851 if (!error_set)
852 dbus_set_error_const (error,
853 DBUS_ERROR_NO_MEMORY,
854 NULL);
855 if (keyring)
856 _dbus_keyring_unref (keyring);
857 _dbus_string_free (&homedir);
858 return NULL;
859
860 }
861
862 /**
863 * Checks whether the context is a valid context.
864 * Contexts that might cause confusion when used
865 * in filenames are not allowed (contexts can't
866 * start with a dot or contain dir separators).
867 *
868 * @todo this is the most inefficient implementation
869 * imaginable.
870 *
871 * @param context the context
872 * @returns #TRUE if valid
873 */
874 dbus_bool_t
_dbus_keyring_validate_context(const DBusString * context)875 _dbus_keyring_validate_context (const DBusString *context)
876 {
877 if (_dbus_string_get_length (context) == 0)
878 {
879 _dbus_verbose ("context is zero-length\n");
880 return FALSE;
881 }
882
883 if (!_dbus_string_validate_ascii (context, 0,
884 _dbus_string_get_length (context)))
885 {
886 _dbus_verbose ("context not valid ascii\n");
887 return FALSE;
888 }
889
890 /* no directory separators */
891 if (_dbus_string_find (context, 0, "/", NULL))
892 {
893 _dbus_verbose ("context contains a slash\n");
894 return FALSE;
895 }
896
897 if (_dbus_string_find (context, 0, "\\", NULL))
898 {
899 _dbus_verbose ("context contains a backslash\n");
900 return FALSE;
901 }
902
903 /* prevent attempts to use dotfiles or ".." or ".lock"
904 * all of which might allow some kind of attack
905 */
906 if (_dbus_string_find (context, 0, ".", NULL))
907 {
908 _dbus_verbose ("context contains a dot\n");
909 return FALSE;
910 }
911
912 /* no spaces/tabs, those are used for separators in the protocol */
913 if (_dbus_string_find_blank (context, 0, NULL))
914 {
915 _dbus_verbose ("context contains a blank\n");
916 return FALSE;
917 }
918
919 if (_dbus_string_find (context, 0, "\n", NULL))
920 {
921 _dbus_verbose ("context contains a newline\n");
922 return FALSE;
923 }
924
925 if (_dbus_string_find (context, 0, "\r", NULL))
926 {
927 _dbus_verbose ("context contains a carriage return\n");
928 return FALSE;
929 }
930
931 return TRUE;
932 }
933
934 static DBusKey*
find_recent_key(DBusKeyring * keyring)935 find_recent_key (DBusKeyring *keyring)
936 {
937 int i;
938 long tv_sec, tv_usec;
939
940 _dbus_get_current_time (&tv_sec, &tv_usec);
941
942 i = 0;
943 while (i < keyring->n_keys)
944 {
945 DBusKey *key = &keyring->keys[i];
946
947 _dbus_verbose ("Key %d is %ld seconds old\n",
948 i, tv_sec - key->creation_time);
949
950 if ((tv_sec - NEW_KEY_TIMEOUT_SECONDS) < key->creation_time)
951 return key;
952
953 ++i;
954 }
955
956 return NULL;
957 }
958
959 /**
960 * Gets a recent key to use for authentication.
961 * If no recent key exists, creates one. Returns
962 * the key ID. If a key can't be written to the keyring
963 * file so no recent key can be created, returns -1.
964 * All valid keys are > 0.
965 *
966 * @param keyring the keyring
967 * @param error error on failure
968 * @returns key ID to use for auth, or -1 on failure
969 */
970 int
_dbus_keyring_get_best_key(DBusKeyring * keyring,DBusError * error)971 _dbus_keyring_get_best_key (DBusKeyring *keyring,
972 DBusError *error)
973 {
974 DBusKey *key;
975
976 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
977
978 key = find_recent_key (keyring);
979 if (key)
980 return key->id;
981
982 /* All our keys are too old, or we've never loaded the
983 * keyring. Create a new one.
984 */
985 if (!_dbus_keyring_reload (keyring, TRUE,
986 error))
987 return -1;
988
989 key = find_recent_key (keyring);
990 if (key)
991 return key->id;
992 else
993 {
994 dbus_set_error_const (error,
995 DBUS_ERROR_FAILED,
996 "No recent-enough key found in keyring, and unable to create a new key");
997 return -1;
998 }
999 }
1000
1001 /**
1002 * Checks whether the keyring is for the given username.
1003 *
1004 * @param keyring the keyring
1005 * @param username the username to check
1006 *
1007 * @returns #TRUE if the keyring belongs to the given user
1008 */
1009 dbus_bool_t
_dbus_keyring_is_for_user(DBusKeyring * keyring,const DBusString * username)1010 _dbus_keyring_is_for_user (DBusKeyring *keyring,
1011 const DBusString *username)
1012 {
1013 return _dbus_string_equal (&keyring->username,
1014 username);
1015 }
1016
1017 /**
1018 * Gets the hex-encoded secret key for the given ID.
1019 * Returns #FALSE if not enough memory. Returns #TRUE
1020 * but empty key on any other error such as unknown
1021 * key ID.
1022 *
1023 * @param keyring the keyring
1024 * @param key_id the key ID
1025 * @param hex_key string to append hex-encoded key to
1026 * @returns #TRUE if we had enough memory
1027 */
1028 dbus_bool_t
_dbus_keyring_get_hex_key(DBusKeyring * keyring,int key_id,DBusString * hex_key)1029 _dbus_keyring_get_hex_key (DBusKeyring *keyring,
1030 int key_id,
1031 DBusString *hex_key)
1032 {
1033 DBusKey *key;
1034
1035 key = find_key_by_id (keyring->keys,
1036 keyring->n_keys,
1037 key_id);
1038 if (key == NULL)
1039 return TRUE; /* had enough memory, so TRUE */
1040
1041 return _dbus_string_hex_encode (&key->secret, 0,
1042 hex_key,
1043 _dbus_string_get_length (hex_key));
1044 }
1045
1046 /** @} */ /* end of exposed API */
1047
1048 #ifdef DBUS_BUILD_TESTS
1049 #include "dbus-test.h"
1050 #include <stdio.h>
1051
1052 dbus_bool_t
_dbus_keyring_test(void)1053 _dbus_keyring_test (void)
1054 {
1055 DBusString context;
1056 DBusKeyring *ring1;
1057 DBusKeyring *ring2;
1058 int id;
1059 DBusError error;
1060 int i;
1061
1062 ring1 = NULL;
1063 ring2 = NULL;
1064
1065 /* Context validation */
1066
1067 _dbus_string_init_const (&context, "foo");
1068 _dbus_assert (_dbus_keyring_validate_context (&context));
1069 _dbus_string_init_const (&context, "org_freedesktop_blah");
1070 _dbus_assert (_dbus_keyring_validate_context (&context));
1071
1072 _dbus_string_init_const (&context, "");
1073 _dbus_assert (!_dbus_keyring_validate_context (&context));
1074 _dbus_string_init_const (&context, ".foo");
1075 _dbus_assert (!_dbus_keyring_validate_context (&context));
1076 _dbus_string_init_const (&context, "bar.foo");
1077 _dbus_assert (!_dbus_keyring_validate_context (&context));
1078 _dbus_string_init_const (&context, "bar/foo");
1079 _dbus_assert (!_dbus_keyring_validate_context (&context));
1080 _dbus_string_init_const (&context, "bar\\foo");
1081 _dbus_assert (!_dbus_keyring_validate_context (&context));
1082 _dbus_string_init_const (&context, "foo\xfa\xf0");
1083 _dbus_assert (!_dbus_keyring_validate_context (&context));
1084 _dbus_string_init_const (&context, "foo\x80");
1085 _dbus_assert (!_dbus_keyring_validate_context (&context));
1086 _dbus_string_init_const (&context, "foo\x7f");
1087 _dbus_assert (_dbus_keyring_validate_context (&context));
1088 _dbus_string_init_const (&context, "foo bar");
1089 _dbus_assert (!_dbus_keyring_validate_context (&context));
1090
1091 if (!_dbus_string_init (&context))
1092 _dbus_assert_not_reached ("no memory");
1093 if (!_dbus_string_append_byte (&context, '\0'))
1094 _dbus_assert_not_reached ("no memory");
1095 _dbus_assert (!_dbus_keyring_validate_context (&context));
1096 _dbus_string_free (&context);
1097
1098 /* Now verify that if we create a key in keyring 1,
1099 * it is properly loaded in keyring 2
1100 */
1101
1102 _dbus_string_init_const (&context, "org_freedesktop_dbus_testsuite");
1103 dbus_error_init (&error);
1104 ring1 = _dbus_keyring_new_homedir (NULL, &context,
1105 &error);
1106 _dbus_assert (ring1);
1107 _dbus_assert (error.name == NULL);
1108
1109 id = _dbus_keyring_get_best_key (ring1, &error);
1110 if (id < 0)
1111 {
1112 fprintf (stderr, "Could not load keyring: %s\n", error.message);
1113 dbus_error_free (&error);
1114 goto failure;
1115 }
1116
1117 ring2 = _dbus_keyring_new_homedir (NULL, &context, &error);
1118 _dbus_assert (ring2);
1119 _dbus_assert (error.name == NULL);
1120
1121 if (ring1->n_keys != ring2->n_keys)
1122 {
1123 fprintf (stderr, "Different number of keys in keyrings\n");
1124 goto failure;
1125 }
1126
1127 /* We guarantee we load and save keeping keys in a fixed
1128 * order
1129 */
1130 i = 0;
1131 while (i < ring1->n_keys)
1132 {
1133 if (ring1->keys[i].id != ring2->keys[i].id)
1134 {
1135 fprintf (stderr, "Keyring 1 has first key ID %d and keyring 2 has %d\n",
1136 ring1->keys[i].id, ring2->keys[i].id);
1137 goto failure;
1138 }
1139
1140 if (ring1->keys[i].creation_time != ring2->keys[i].creation_time)
1141 {
1142 fprintf (stderr, "Keyring 1 has first key time %ld and keyring 2 has %ld\n",
1143 ring1->keys[i].creation_time, ring2->keys[i].creation_time);
1144 goto failure;
1145 }
1146
1147 if (!_dbus_string_equal (&ring1->keys[i].secret,
1148 &ring2->keys[i].secret))
1149 {
1150 fprintf (stderr, "Keyrings 1 and 2 have different secrets for same ID/timestamp\n");
1151 goto failure;
1152 }
1153
1154 ++i;
1155 }
1156
1157 printf (" %d keys in test\n", ring1->n_keys);
1158
1159 /* Test ref/unref */
1160 _dbus_keyring_ref (ring1);
1161 _dbus_keyring_ref (ring2);
1162 _dbus_keyring_unref (ring1);
1163 _dbus_keyring_unref (ring2);
1164
1165
1166 /* really unref */
1167 _dbus_keyring_unref (ring1);
1168 _dbus_keyring_unref (ring2);
1169
1170 return TRUE;
1171
1172 failure:
1173 if (ring1)
1174 _dbus_keyring_unref (ring1);
1175 if (ring2)
1176 _dbus_keyring_unref (ring2);
1177
1178 return FALSE;
1179 }
1180
1181 #endif /* DBUS_BUILD_TESTS */
1182
1183