diff options
Diffstat (limited to 'libmisc/find_new_gid.c')
| -rw-r--r-- | libmisc/find_new_gid.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/libmisc/find_new_gid.c b/libmisc/find_new_gid.c new file mode 100644 index 0000000..d3e51a4 --- /dev/null +++ b/libmisc/find_new_gid.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 "groupio.h" +#include "getdef.h" + +/* + * find_new_gid - Find a new unused GID. + * + * If successful, find_new_gid provides an unused group ID in the + * [GID_MIN:GID_MAX] range. + * This ID should be higher than all the used GID, but if not possible, + * the lowest unused ID in the range will be returned. + * + * Return 0 on success, -1 if no unused GIDs are available. + */ +int find_new_gid (bool sys_group, + gid_t *gid, + /*@null@*/gid_t const *preferred_gid) +{ + const struct group *grp; + gid_t gid_min, gid_max, group_id; + bool *used_gids; + + assert (gid != NULL); + + if (!sys_group) { + gid_min = (gid_t) getdef_ulong ("GID_MIN", 1000UL); + gid_max = (gid_t) getdef_ulong ("GID_MAX", 60000UL); + if (gid_max < gid_min) { + (void) fprintf (stderr, + _("%s: Invalid configuration: GID_MIN (%lu), GID_MAX (%lu)\n"), + Prog, (unsigned long) gid_min, (unsigned long) gid_max); + return -1; + } + } else { + gid_min = (gid_t) getdef_ulong ("SYS_GID_MIN", 101UL); + gid_max = (gid_t) getdef_ulong ("GID_MIN", 1000UL) - 1; + gid_max = (gid_t) getdef_ulong ("SYS_GID_MAX", (unsigned long) gid_max); + if (gid_max < gid_min) { + (void) fprintf (stderr, + _("%s: Invalid configuration: SYS_GID_MIN (%lu), GID_MIN (%lu), SYS_GID_MAX (%lu)\n"), + Prog, (unsigned long) gid_min, getdef_ulong ("GID_MIN", 1000UL), (unsigned long) gid_max); + return -1; + } + } + used_gids = malloc (sizeof (bool) * (gid_max +1)); + if (NULL == used_gids) { + fprintf (stderr, + _("%s: failed to allocate memory: %s\n"), + Prog, strerror (errno)); + return -1; + } + memset (used_gids, false, sizeof (bool) * (gid_max + 1)); + + if ( (NULL != preferred_gid) + && (*preferred_gid >= gid_min) + && (*preferred_gid <= gid_max) + /* Check if the user exists according to NSS */ + && (getgrgid (*preferred_gid) == NULL) + /* Check also the local database in case of uncommitted + * changes */ + && (gr_locate_gid (*preferred_gid) == NULL)) { + *gid = *preferred_gid; + free (used_gids); + return 0; + } + + + /* + * Search the entire group file, + * looking for the largest unused value. + * + * We check the list of groups according to NSS (setgrent/getgrent), + * but we also check the local database (gr_rewind/gr_next) in case + * some groups were created but the changes were not committed yet. + */ + if (sys_group) { + gid_t id; + /* setgrent / getgrent / endgrent 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 getgrgid. + */ + group_id = gid_max; + for (id = gid_max; id >= gid_min; id--) { + if (getgrgid (id) != NULL) { + group_id = id - 1; + used_gids[id] = true; + } + } + + (void) gr_rewind (); + while ((grp = gr_next ()) != NULL) { + if ((grp->gr_gid <= group_id) && (grp->gr_gid >= gid_min)) { + group_id = grp->gr_gid - 1; + } + /* create index of used GIDs */ + if (grp->gr_gid <= gid_max) { + used_gids[grp->gr_gid] = true; + } + } + } else { + group_id = gid_min; + setgrent (); + while ((grp = getgrent ()) != NULL) { + if ((grp->gr_gid >= group_id) && (grp->gr_gid <= gid_max)) { + group_id = grp->gr_gid + 1; + } + /* create index of used GIDs */ + if (grp->gr_gid <= gid_max) { + used_gids[grp->gr_gid] = true; + } + } + endgrent (); + + (void) gr_rewind (); + while ((grp = gr_next ()) != NULL) { + if ((grp->gr_gid >= group_id) && (grp->gr_gid <= gid_max)) { + group_id = grp->gr_gid + 1; + } + /* create index of used GIDs */ + if (grp->gr_gid <= gid_max) { + used_gids[grp->gr_gid] = true; + } + } + } + + /* + * If a group (resp. system group) with GID equal to GID_MAX (resp. + * GID_MIN) exists, the above algorithm will give us GID_MAX+1 + * (resp. GID_MIN-1) even if not unique. Search for the first free + * GID starting with GID_MIN (resp. GID_MAX). + */ + if (sys_group) { + if (group_id < gid_min) { + for (group_id = gid_max; group_id >= gid_min; group_id--) { + if (false == used_gids[group_id]) { + break; + } + } + if (group_id < gid_min) { + fprintf (stderr, + _("%s: Can't get unique system GID (no more available GIDs)\n"), + Prog); + SYSLOG ((LOG_WARN, + "no more available GID on the system")); + free (used_gids); + return -1; + } + } + } else { + if (group_id > gid_max) { + for (group_id = gid_min; group_id <= gid_max; group_id++) { + if (false == used_gids[group_id]) { + break; + } + } + if (group_id > gid_max) { + fprintf (stderr, + _("%s: Can't get unique GID (no more available GIDs)\n"), + Prog); + SYSLOG ((LOG_WARN, "no more available GID on the system")); + free (used_gids); + return -1; + } + } + } + + free (used_gids); + *gid = group_id; + return 0; +} + |