diff options
Diffstat (limited to 'libmisc/find_new_uid.c')
| -rw-r--r-- | libmisc/find_new_uid.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/libmisc/find_new_uid.c b/libmisc/find_new_uid.c new file mode 100644 index 0000000..aac1909 --- /dev/null +++ b/libmisc/find_new_uid.c @@ -0,0 +1,209 @@ +/* + * Copyright (c) 1991 - 1994, Julianne Frances Haugh + * Copyright (c) 2008 - 2011, Nicolas François + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the copyright holders or contributors may not be used to + * endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A + * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include <config.h> + +#include <assert.h> +#include <stdio.h> +#include <errno.h> + +#include "prototypes.h" +#include "pwio.h" +#include "getdef.h" + +/* + * find_new_uid - Find a new unused UID. + * + * If successful, find_new_uid provides an unused user ID in the + * [UID_MIN:UID_MAX] range. + * This ID should be higher than all the used UID, but if not possible, + * the lowest unused ID in the range will be returned. + * + * Return 0 on success, -1 if no unused UIDs are available. + */ +int find_new_uid (bool sys_user, + uid_t *uid, + /*@null@*/uid_t const *preferred_uid) +{ + const struct passwd *pwd; + uid_t uid_min, uid_max, user_id; + bool *used_uids; + + assert (uid != NULL); + + if (!sys_user) { + uid_min = (uid_t) getdef_ulong ("UID_MIN", 1000UL); + uid_max = (uid_t) getdef_ulong ("UID_MAX", 60000UL); + if (uid_max < uid_min) { + (void) fprintf (stderr, + _("%s: Invalid configuration: UID_MIN (%lu), UID_MAX (%lu)\n"), + Prog, (unsigned long) uid_min, (unsigned long) uid_max); + return -1; + } + } else { + uid_min = (uid_t) getdef_ulong ("SYS_UID_MIN", 101UL); + uid_max = (uid_t) getdef_ulong ("UID_MIN", 1000UL) - 1; + uid_max = (uid_t) getdef_ulong ("SYS_UID_MAX", (unsigned long) uid_max); + if (uid_max < uid_min) { + (void) fprintf (stderr, + _("%s: Invalid configuration: SYS_UID_MIN (%lu), UID_MIN (%lu), SYS_UID_MAX (%lu)\n"), + Prog, (unsigned long) uid_min, getdef_ulong ("UID_MIN", 1000UL), (unsigned long) uid_max); + return -1; + } + } + used_uids = malloc (sizeof (bool) * (uid_max +1)); + if (NULL == used_uids) { + fprintf (stderr, + _("%s: failed to allocate memory: %s\n"), + Prog, strerror (errno)); + return -1; + } + memset (used_uids, false, sizeof (bool) * (uid_max + 1)); + + if ( (NULL != preferred_uid) + && (*preferred_uid >= uid_min) + && (*preferred_uid <= uid_max) + /* Check if the user exists according to NSS */ + && (getpwuid (*preferred_uid) == NULL) + /* Check also the local database in case of uncommitted + * changes */ + && (pw_locate_uid (*preferred_uid) == NULL)) { + *uid = *preferred_uid; + free (used_uids); + return 0; + } + + + /* + * Search the entire password file, + * looking for the largest unused value. + * + * We check the list of users according to NSS (setpwent/getpwent), + * but we also check the local database (pw_rewind/pw_next) in case + * some users were created but the changes were not committed yet. + */ + if (sys_user) { + uid_t id; + /* setpwent / getpwent / endpwent can be very slow with + * LDAP configurations (and many accounts). + * Since there is a limited amount of IDs to be tested + * for system accounts, we just check the existence + * of IDs with getpwuid. + */ + user_id = uid_max; + for (id = uid_max; id >= uid_min; id--) { + if (getpwuid (id) != NULL) { + user_id = id - 1; + used_uids[id] = true; + } + } + + (void) pw_rewind (); + while ((pwd = pw_next ()) != NULL) { + if ((pwd->pw_uid <= user_id) && (pwd->pw_uid >= uid_min)) { + user_id = pwd->pw_uid - 1; + } + /* create index of used UIDs */ + if (pwd->pw_uid <= uid_max) { + used_uids[pwd->pw_uid] = true; + } + } + } else { + user_id = uid_min; + setpwent (); + while ((pwd = getpwent ()) != NULL) { + if ((pwd->pw_uid >= user_id) && (pwd->pw_uid <= uid_max)) { + user_id = pwd->pw_uid + 1; + } + /* create index of used UIDs */ + if (pwd->pw_uid <= uid_max) { + used_uids[pwd->pw_uid] = true; + } + } + endpwent (); + + (void) pw_rewind (); + while ((pwd = pw_next ()) != NULL) { + if ((pwd->pw_uid >= user_id) && (pwd->pw_uid <= uid_max)) { + user_id = pwd->pw_uid + 1; + } + /* create index of used UIDs */ + if (pwd->pw_uid <= uid_max) { + used_uids[pwd->pw_uid] = true; + } + } + } + + /* + * If a user (resp. system user) with UID equal to UID_MAX (resp. + * UID_MIN) exists, the above algorithm will give us UID_MAX+1 + * (resp. UID_MIN-1) even if not unique. Search for the first free + * UID starting with UID_MIN (resp. UID_MAX). + */ + if (sys_user) { + if (user_id < uid_min) { + for (user_id = uid_max; user_id >= uid_min; user_id--) { + if (false == used_uids[user_id]) { + break; + } + } + if (user_id < uid_min ) { + fprintf (stderr, + _("%s: Can't get unique system UID (no more available UIDs)\n"), + Prog); + SYSLOG ((LOG_WARN, + "no more available UID on the system")); + free (used_uids); + return -1; + } + } + } else { + if (user_id > uid_max) { + for (user_id = uid_min; user_id <= uid_max; user_id++) { + if (false == used_uids[user_id]) { + break; + } + } + if (user_id > uid_max) { + fprintf (stderr, + _("%s: Can't get unique UID (no more available UIDs)\n"), + Prog); + SYSLOG ((LOG_WARN, "no more available UID on the system")); + free (used_uids); + return -1; + } + } + } + + free (used_uids); + *uid = user_id; + return 0; +} + |