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/*
* 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;
}
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