D-Bus  1.16.2
dbus-userdb.c
1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2 /* dbus-userdb.c User database abstraction
3  *
4  * Copyright (C) 2003, 2004 Red Hat, Inc.
5  *
6  * SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
7  *
8  * Licensed under the Academic Free License version 2.1
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  *
24  */
25 #include <config.h>
26 #define DBUS_USERDB_INCLUDES_PRIVATE 1
27 #include "dbus-userdb.h"
28 #include "dbus-hash.h"
29 #include "dbus-test.h"
30 #include "dbus-internals.h"
31 #include "dbus-protocol.h"
32 #include "dbus-credentials.h"
33 #include <string.h>
34 
35 /* It isn't obvious from its name, but this file is part of the Unix
36  * system-dependent part of libdbus. Windows has a parallel
37  * implementation of some of it in dbus-sysdeps-win.c. */
38 #if defined(DBUS_WIN) || !defined(DBUS_UNIX)
39 #error "This file only makes sense on Unix OSs"
40 #endif
41 
47 static DBusUserInfo *
48 _dbus_user_info_ref (DBusUserInfo *info)
49 {
50  _dbus_assert (info->refcount > 0);
51  _dbus_assert (info->refcount < SIZE_MAX);
52  info->refcount++;
53  return info;
54 }
55 
63 void
65 {
66  if (info == NULL) /* hash table will pass NULL */
67  return;
68 
69  _dbus_assert (info->refcount > 0);
70  _dbus_assert (info->refcount < SIZE_MAX);
71 
72  if (--info->refcount > 0)
73  return;
74 
75  _dbus_user_info_free (info);
76  dbus_free (info);
77 }
78 
86 void
88 {
89  if (info == NULL) /* hash table will pass NULL */
90  return;
91 
92  _dbus_assert (info->refcount > 0);
93  _dbus_assert (info->refcount < SIZE_MAX);
94 
95  if (--info->refcount > 0)
96  return;
97 
98  _dbus_group_info_free (info);
99  dbus_free (info);
100 }
101 
107 void
109 {
110  dbus_free (info->group_ids);
111  dbus_free (info->username);
112  dbus_free (info->homedir);
113 }
114 
120 void
122 {
123  dbus_free (info->groupname);
124 }
125 
136  unsigned long *num)
137 {
138  int end;
139 
140  if (_dbus_string_parse_uint (str, 0, num, &end) &&
141  end == _dbus_string_get_length (str))
142  return TRUE;
143  else
144  return FALSE;
145 }
146 
159 const DBusUserInfo *
160 _dbus_user_database_lookup (DBusUserDatabase *db,
161  dbus_uid_t uid,
162  const DBusString *username,
163  DBusError *error)
164 {
165  DBusUserInfo *info;
166 
167  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
168  _dbus_assert (uid != DBUS_UID_UNSET || username != NULL);
169 
170  /* See if the username is really a number */
171  if (uid == DBUS_UID_UNSET)
172  {
173  unsigned long n;
174 
175  if (_dbus_is_a_number (username, &n))
176  uid = n;
177  }
178 
179  if (uid != DBUS_UID_UNSET)
180  info = _dbus_hash_table_lookup_uintptr (db->users, uid);
181  else
182  info = _dbus_hash_table_lookup_string (db->users_by_name, _dbus_string_get_const_data (username));
183 
184  if (info)
185  {
186  _dbus_verbose ("Using cache for UID "DBUS_UID_FORMAT" information\n",
187  info->uid);
188  return info;
189  }
190  else
191  {
192  if (uid != DBUS_UID_UNSET)
193  _dbus_verbose ("No cache for UID "DBUS_UID_FORMAT"\n",
194  uid);
195  else
196  _dbus_verbose ("No cache for user \"%s\"\n",
197  _dbus_string_get_const_data (username));
198 
199  info = dbus_new0 (DBusUserInfo, 1);
200  if (info == NULL)
201  {
203  return NULL;
204  }
205  info->refcount = 1;
206 
207  if (uid != DBUS_UID_UNSET)
208  {
209  if (!_dbus_user_info_fill_uid (info, uid, error))
210  {
211  _DBUS_ASSERT_ERROR_IS_SET (error);
212  _dbus_user_info_unref (info);
213  return NULL;
214  }
215  }
216  else
217  {
218  if (!_dbus_user_info_fill (info, username, error))
219  {
220  _DBUS_ASSERT_ERROR_IS_SET (error);
221  _dbus_user_info_unref (info);
222  return NULL;
223  }
224  }
225 
226  /* be sure we don't use these after here */
227  uid = DBUS_UID_UNSET;
228  username = NULL;
229 
230  /* insert into hash */
231  if (_dbus_hash_table_insert_uintptr (db->users, info->uid, info))
232  {
233  _dbus_user_info_ref (info);
234  }
235  else
236  {
238  _dbus_user_info_unref (info);
239  return NULL;
240  }
241 
242  if (_dbus_hash_table_insert_string (db->users_by_name,
243  info->username,
244  info))
245  {
246  _dbus_user_info_ref (info);
247  }
248  else
249  {
250  _dbus_hash_table_remove_uintptr (db->users, info->uid);
252  _dbus_user_info_unref (info);
253  return NULL;
254  }
255 
256  _dbus_user_info_unref (info);
257 
258  /* Return a borrowed pointer to the DBusUserInfo owned by the
259  * hash tables */
260  return info;
261  }
262 }
263 
264 /* Protected by _DBUS_LOCK_system_users */
265 static dbus_bool_t database_locked = FALSE;
266 static DBusUserDatabase *system_db = NULL;
267 static DBusString process_username;
268 static DBusString process_homedir;
269 
270 static void
271 shutdown_system_db (void *data)
272 {
273  if (system_db != NULL)
274  _dbus_user_database_unref (system_db);
275  system_db = NULL;
276  _dbus_string_free (&process_username);
277  _dbus_string_free (&process_homedir);
278 }
279 
280 static dbus_bool_t
281 init_system_db (void)
282 {
283  _dbus_assert (database_locked);
284 
285  if (system_db == NULL)
286  {
287  DBusError error = DBUS_ERROR_INIT;
288  const DBusUserInfo *info;
289 
290  system_db = _dbus_user_database_new ();
291  if (system_db == NULL)
292  return FALSE;
293 
294  if (!_dbus_user_database_get_uid (system_db,
295  _dbus_getuid (),
296  &info,
297  &error))
298  {
299  _dbus_user_database_unref (system_db);
300  system_db = NULL;
301 
303  {
304  dbus_error_free (&error);
305  return FALSE;
306  }
307  else
308  {
309  /* This really should not happen. */
310  _dbus_warn ("Could not get password database information for UID of current process: %s",
311  error.message);
312  dbus_error_free (&error);
313  return FALSE;
314  }
315  }
316 
317  if (!_dbus_string_init (&process_username))
318  {
319  _dbus_user_database_unref (system_db);
320  system_db = NULL;
321  return FALSE;
322  }
323 
324  if (!_dbus_string_init (&process_homedir))
325  {
326  _dbus_string_free (&process_username);
327  _dbus_user_database_unref (system_db);
328  system_db = NULL;
329  return FALSE;
330  }
331 
332  if (!_dbus_string_append (&process_username,
333  info->username) ||
334  !_dbus_string_append (&process_homedir,
335  info->homedir) ||
336  !_dbus_register_shutdown_func (shutdown_system_db, NULL))
337  {
338  _dbus_string_free (&process_username);
339  _dbus_string_free (&process_homedir);
340  _dbus_user_database_unref (system_db);
341  system_db = NULL;
342  return FALSE;
343  }
344  }
345 
346  return TRUE;
347 }
348 
354 {
355  if (_DBUS_LOCK (system_users))
356  {
357  database_locked = TRUE;
358  return TRUE;
359  }
360  else
361  {
362  return FALSE;
363  }
364 }
365 
369 void
371 {
372  database_locked = FALSE;
373  _DBUS_UNLOCK (system_users);
374 }
375 
382 DBusUserDatabase*
384 {
385  _dbus_assert (database_locked);
386 
387  init_system_db ();
388 
389  return system_db;
390 }
391 
395 void
397 {
399  {
400  /* nothing to flush */
401  return;
402  }
403 
404  if (system_db != NULL)
405  _dbus_user_database_flush (system_db);
406 
408 }
409 
419 {
421  return FALSE;
422 
423  if (!init_system_db ())
424  {
426  return FALSE;
427  }
428  *username = &process_username;
430 
431  return TRUE;
432 }
433 
443 {
445  return FALSE;
446 
447  if (!init_system_db ())
448  {
450  return FALSE;
451  }
452  *homedir = &process_homedir;
454 
455  return TRUE;
456 }
457 
467  DBusString *homedir)
468 {
469  DBusUserDatabase *db;
470  const DBusUserInfo *info;
471 
472  if (uid == _dbus_getuid () && uid == _dbus_geteuid ())
473  {
474  const char *from_environment;
475 
476  from_environment = _dbus_getenv ("HOME");
477 
478  if (from_environment != NULL)
479  return _dbus_string_append (homedir, from_environment);
480  }
481 
482  /* FIXME: this can't distinguish ENOMEM from other errors */
484  return FALSE;
485 
487  if (db == NULL)
488  {
490  return FALSE;
491  }
492 
493  if (!_dbus_user_database_get_uid (db, uid,
494  &info, NULL))
495  {
497  return FALSE;
498  }
499 
500  if (!_dbus_string_append (homedir, info->homedir))
501  {
503  return FALSE;
504  }
505 
507  return TRUE;
508 }
509 
526  const DBusString *username,
527  DBusCredentialsAddFlags flags,
528  DBusError *error)
529 {
530  DBusUserDatabase *db;
531  const DBusUserInfo *info;
532  unsigned long uid = DBUS_UID_UNSET;
533 
534  /* Fast-path for the common case: if the "username" is all-numeric,
535  * then it's a Unix uid. This is true regardless of whether that uid
536  * exists in NSS or /etc/passwd or equivalent. */
537  if (_dbus_is_a_number (username, &uid))
538  {
539  _DBUS_STATIC_ASSERT (sizeof (uid) == sizeof (dbus_uid_t));
540 
541  if (_dbus_credentials_add_unix_uid (credentials, uid))
542  {
543  return TRUE;
544  }
545  else
546  {
547  _DBUS_SET_OOM (error);
548  return FALSE;
549  }
550  }
551 
552  /* If we aren't allowed to look in NSS or /etc/passwd, fail now. */
553  if (!(flags & DBUS_CREDENTIALS_ADD_FLAGS_USER_DATABASE))
554  {
556  "Expected a numeric Unix uid");
557  return FALSE;
558  }
559 
561  {
562  _DBUS_SET_OOM (error);
563  return FALSE;
564  }
565 
567  if (db == NULL)
568  {
570  _DBUS_SET_OOM (error);
571  return FALSE;
572  }
573 
574  if (!_dbus_user_database_get_username (db, username,
575  &info, error))
576  {
578  return FALSE;
579  }
580 
581  if (!_dbus_credentials_add_unix_uid(credentials, info->uid))
582  {
584  _DBUS_SET_OOM (error);
585  return FALSE;
586  }
587 
589  return TRUE;
590 }
591 
597 DBusUserDatabase*
599 {
600  DBusUserDatabase *db;
601 
602  db = dbus_new0 (DBusUserDatabase, 1);
603  if (db == NULL)
604  return NULL;
605 
606  db->refcount = 1;
607 
610 
611  if (db->users == NULL)
612  goto failed;
613 
616 
617  if (db->groups == NULL)
618  goto failed;
619 
620  db->users_by_name = _dbus_hash_table_new (DBUS_HASH_STRING,
621  NULL, (DBusFreeFunction) _dbus_user_info_unref);
622  if (db->users_by_name == NULL)
623  goto failed;
624 
625  db->groups_by_name = _dbus_hash_table_new (DBUS_HASH_STRING,
626  NULL, (DBusFreeFunction) _dbus_group_info_unref);
627  if (db->groups_by_name == NULL)
628  goto failed;
629 
630  return db;
631 
632  failed:
634  return NULL;
635 }
636 
640 void
641 _dbus_user_database_flush (DBusUserDatabase *db)
642 {
643  _dbus_hash_table_remove_all(db->users_by_name);
644  _dbus_hash_table_remove_all(db->groups_by_name);
645  _dbus_hash_table_remove_all(db->users);
646  _dbus_hash_table_remove_all(db->groups);
647 }
648 
649 #ifdef DBUS_ENABLE_EMBEDDED_TESTS
650 
655 DBusUserDatabase *
656 _dbus_user_database_ref (DBusUserDatabase *db)
657 {
658  _dbus_assert (db->refcount > 0);
659 
660  db->refcount += 1;
661 
662  return db;
663 }
664 #endif /* DBUS_ENABLE_EMBEDDED_TESTS */
665 
670 void
671 _dbus_user_database_unref (DBusUserDatabase *db)
672 {
673  _dbus_assert (db->refcount > 0);
674 
675  db->refcount -= 1;
676  if (db->refcount == 0)
677  {
678  if (db->users)
679  _dbus_hash_table_unref (db->users);
680 
681  if (db->groups)
682  _dbus_hash_table_unref (db->groups);
683 
684  if (db->users_by_name)
685  _dbus_hash_table_unref (db->users_by_name);
686 
687  if (db->groups_by_name)
688  _dbus_hash_table_unref (db->groups_by_name);
689 
690  dbus_free (db);
691  }
692 }
693 
705 _dbus_user_database_get_uid (DBusUserDatabase *db,
706  dbus_uid_t uid,
707  const DBusUserInfo **info,
708  DBusError *error)
709 {
710  *info = _dbus_user_database_lookup (db, uid, NULL, error);
711  return *info != NULL;
712 }
713 
724 _dbus_user_database_get_username (DBusUserDatabase *db,
725  const DBusString *username,
726  const DBusUserInfo **info,
727  DBusError *error)
728 {
729  *info = _dbus_user_database_lookup (db, DBUS_UID_UNSET, username, error);
730  return *info != NULL;
731 }
732 
735 /* Tests in dbus-userdb-util.c */
dbus_bool_t dbus_error_has_name(const DBusError *error, const char *name)
Checks whether the error is set and has the given name.
Definition: dbus-errors.c:304
dbus_bool_t _dbus_string_append(DBusString *str, const char *buffer)
Appends a nul-terminated C-style string to a DBusString.
Definition: dbus-string.c:980
void * _dbus_hash_table_lookup_uintptr(DBusHashTable *table, uintptr_t key)
Looks up the value for a given integer in a hash table of type DBUS_HASH_UINTPTR. ...
Definition: dbus-hash.c:1163
const char * message
public error message field
Definition: dbus-errors.h:53
char * username
Username.
#define NULL
A null pointer, defined appropriately for C or C++.
void(* DBusFreeFunction)(void *memory)
The type of a function which frees a block of memory.
Definition: dbus-memory.h:65
void dbus_free(void *memory)
Frees a block of memory previously allocated by dbus_malloc() or dbus_malloc0().
Definition: dbus-memory.c:710
void _dbus_user_info_free(DBusUserInfo *info)
Frees the members of info (but not info itself)
Definition: dbus-userdb.c:108
dbus_bool_t _dbus_user_database_lock_system(void)
Locks global system user database.
Definition: dbus-userdb.c:353
#define DBUS_ERROR_INIT
Expands to a suitable initializer for a DBusError on the stack.
Definition: dbus-errors.h:64
void _dbus_user_database_flush_system(void)
Flushes the system global user database;.
Definition: dbus-userdb.c:396
void dbus_error_free(DBusError *error)
Frees an error that's been set (or just initialized), then reinitializes the error as in dbus_error_i...
Definition: dbus-errors.c:213
dbus_bool_t _dbus_hash_table_insert_uintptr(DBusHashTable *table, uintptr_t key, void *value)
Creates a hash entry with the given key and value.
Definition: dbus-hash.c:1353
void _dbus_hash_table_unref(DBusHashTable *table)
Decrements the reference count for a hash table, freeing the hash table if the count reaches zero...
Definition: dbus-hash.c:368
void _dbus_user_database_flush(DBusUserDatabase *db)
Flush all information out of the user database.
Definition: dbus-userdb.c:641
dbus_bool_t _dbus_user_database_get_uid(DBusUserDatabase *db, dbus_uid_t uid, const DBusUserInfo **info, DBusError *error)
Gets the user information for the given UID, returned user info should not be freed.
Definition: dbus-userdb.c:705
void _dbus_user_database_unlock_system(void)
Unlocks global system user database.
Definition: dbus-userdb.c:370
dbus_bool_t _dbus_string_init(DBusString *str)
Initializes a string.
Definition: dbus-string.c:182
Hash keys are strings.
Definition: dbus-hash.h:69
Hash keys are integer capable to hold a pointer.
Definition: dbus-hash.h:71
void _dbus_hash_table_remove_all(DBusHashTable *table)
Removed all entries from a hash table.
Definition: dbus-hash.c:425
char * groupname
Group name.
#define DBUS_UID_UNSET
an invalid UID used to represent an uninitialized dbus_uid_t field
Definition: dbus-sysdeps.h:148
dbus_bool_t _dbus_user_info_fill(DBusUserInfo *info, const DBusString *username, DBusError *error)
Gets user info for the given username.
void _dbus_group_info_free(DBusGroupInfo *info)
Frees the members of info (but not info itself).
Definition: dbus-userdb.c:121
DBusUserDatabase * _dbus_user_database_get_system(void)
Gets the system global user database; must be called with lock held (_dbus_user_database_lock_system(...
Definition: dbus-userdb.c:383
dbus_bool_t _dbus_homedir_from_uid(dbus_uid_t uid, DBusString *homedir)
Gets the home directory for the given user.
Definition: dbus-userdb.c:466
dbus_gid_t * group_ids
Groups IDs, including above primary group.
dbus_bool_t _dbus_is_a_number(const DBusString *str, unsigned long *num)
Checks if a given string is actually a number and converts it if it is.
Definition: dbus-userdb.c:135
#define dbus_new0(type, count)
Safe macro for using dbus_malloc0().
Definition: dbus-memory.h:60
dbus_uint32_t dbus_bool_t
A boolean, valid values are TRUE and FALSE.
Definition: dbus-types.h:37
void _dbus_warn(const char *format,...)
Prints a warning message to stderr.
dbus_bool_t _dbus_hash_table_insert_string(DBusHashTable *table, char *key, void *value)
Creates a hash entry with the given key and value.
Definition: dbus-hash.c:1278
dbus_uid_t uid
UID.
void _dbus_user_info_unref(DBusUserInfo *info)
Decrements the reference count.
Definition: dbus-userdb.c:64
Object representing an exception.
Definition: dbus-errors.h:50
void dbus_set_error(DBusError *error, const char *name, const char *format,...)
Assigns an error name and message to a DBusError.
Definition: dbus-errors.c:356
DBusUserDatabase * _dbus_user_database_new(void)
Creates a new user database object used to look up and cache user information.
Definition: dbus-userdb.c:598
void _dbus_string_free(DBusString *str)
Frees a string created by _dbus_string_init(), and fills it with the same contents as #_DBUS_STRING_I...
Definition: dbus-string.c:278
dbus_uid_t _dbus_geteuid(void)
Gets our effective UID.
#define TRUE
Expands to "1".
#define _dbus_assert(condition)
Aborts with an error message if the condition is false.
#define DBUS_UID_FORMAT
an appropriate printf format for dbus_uid_t
Definition: dbus-sysdeps.h:155
char * homedir
Home directory.
dbus_bool_t _dbus_homedir_from_current_process(const DBusString **homedir)
Gets homedir of user owning current process.
Definition: dbus-userdb.c:442
Information about a UNIX group.
dbus_bool_t _dbus_credentials_add_from_user(DBusCredentials *credentials, const DBusString *username, DBusCredentialsAddFlags flags, DBusError *error)
Adds the credentials corresponding to the given username.
Definition: dbus-userdb.c:525
size_t refcount
Reference count.
DBUS_PRIVATE_EXPORT dbus_bool_t _dbus_string_parse_uint(const DBusString *str, int start, unsigned long *value_return, int *end_return)
Parses an unsigned integer contained in a DBusString.
Definition: dbus-sysdeps.c:410
#define _DBUS_UNLOCK(name)
Unlocks a global lock.
dbus_uid_t _dbus_getuid(void)
Gets our UID.
dbus_bool_t _dbus_user_info_fill_uid(DBusUserInfo *info, dbus_uid_t uid, DBusError *error)
Gets user info for the given user ID.
void * _dbus_hash_table_lookup_string(DBusHashTable *table, const char *key)
Looks up the value for a given string in a hash table of type DBUS_HASH_STRING.
Definition: dbus-hash.c:1113
#define DBUS_ERROR_NO_MEMORY
There was not enough memory to complete an operation.
#define FALSE
Expands to "0".
DBusCredentials * credentials
Credentials of other end read from the socket.
DBUS_PRIVATE_EXPORT dbus_bool_t _dbus_register_shutdown_func(DBusShutdownFunction function, void *data)
Register a cleanup function to be called exactly once the next time dbus_shutdown() is called...
Definition: dbus-memory.c:819
dbus_bool_t _dbus_user_database_get_username(DBusUserDatabase *db, const DBusString *username, const DBusUserInfo **info, DBusError *error)
Gets the user information for the given username.
Definition: dbus-userdb.c:724
dbus_bool_t _dbus_credentials_add_unix_uid(DBusCredentials *credentials, dbus_uid_t uid)
Add a UNIX user ID to the credentials.
const char * _dbus_getenv(const char *varname)
Wrapper for getenv().
Definition: dbus-sysdeps.c:197
void _dbus_user_database_unref(DBusUserDatabase *db)
Decrements refcount of user database.
Definition: dbus-userdb.c:671
#define DBUS_ERROR_INVALID_ARGS
Invalid arguments passed to a method call.
unsigned long dbus_uid_t
A user ID.
Definition: dbus-sysdeps.h:141
void _dbus_group_info_unref(DBusGroupInfo *info)
Decrements the reference count.
Definition: dbus-userdb.c:87
dbus_bool_t _dbus_hash_table_remove_uintptr(DBusHashTable *table, uintptr_t key)
Removes the hash entry for the given key.
Definition: dbus-hash.c:1243
#define _DBUS_LOCK(name)
Locks a global lock, initializing it first if necessary.
size_t refcount
Reference count.
dbus_bool_t _dbus_username_from_current_process(const DBusString **username)
Gets username of user owning current process.
Definition: dbus-userdb.c:418
DBusHashTable * _dbus_hash_table_new(DBusHashType type, DBusFreeFunction key_free_function, DBusFreeFunction value_free_function)
Constructs a new hash table.
Definition: dbus-hash.c:292
Information about a UNIX user.
const DBusUserInfo * _dbus_user_database_lookup(DBusUserDatabase *db, dbus_uid_t uid, const DBusString *username, DBusError *error)
Looks up a uid or username in the user database.
Definition: dbus-userdb.c:160