/* * 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 #include #include #include #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; }