/*
* Copyright (c) 1991 - 1994, Julianne Frances Haugh
* Copyright (c) 2008 - 2011, Nicolas François
+ * Copyright (c) 2014, Red Hat, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
#include "groupio.h"
#include "getdef.h"
+/*
+ * get_ranges - Get the minimum and maximum ID ranges for the search
+ *
+ * This function will return the minimum and maximum ranges for IDs
+ *
+ * 0: The function completed successfully
+ * EINVAL: The provided ranges are impossible (such as maximum < minimum)
+ *
+ * preferred_min: The special-case minimum value for a specifically-
+ * requested ID, which may be lower than the standard min_id
+ */
+static int get_ranges (bool sys_group, gid_t *min_id, gid_t *max_id,
+ gid_t *preferred_min)
+{
+ gid_t gid_def_max = 0;
+
+ if (sys_group) {
+ /* System groups */
+
+ /* A requested ID is allowed to be below the autoselect range */
+ *preferred_min = (gid_t) 1;
+
+ /* Get the minimum ID range from login.defs or default to 101 */
+ *min_id = (gid_t) getdef_ulong ("SYS_GID_MIN", 101UL);
+
+ /*
+ * If SYS_GID_MAX is unspecified, we should assume it to be one
+ * less than the GID_MIN (which is reserved for non-system accounts)
+ */
+ gid_def_max = (gid_t) getdef_ulong ("GID_MIN", 1000UL) - 1;
+ *max_id = (gid_t) getdef_ulong ("SYS_GID_MAX",
+ (unsigned long) gid_def_max);
+
+ /* Check that the ranges make sense */
+ if (*max_id < *min_id) {
+ (void) fprintf (stderr,
+ _("%s: Invalid configuration: SYS_GID_MIN (%lu), "
+ "GID_MIN (%lu), SYS_GID_MAX (%lu)\n"),
+ Prog, (unsigned long) *min_id,
+ getdef_ulong ("GID_MIN", 1000UL),
+ (unsigned long) *max_id);
+ return EINVAL;
+ }
+ } else {
+ /* Non-system groups */
+
+ /* Get the values from login.defs or use reasonable defaults */
+ *min_id = (gid_t) getdef_ulong ("GID_MIN", 1000UL);
+ *max_id = (gid_t) getdef_ulong ("GID_MAX", 60000UL);
+
+ /*
+ * The preferred minimum should match the standard ID minimum
+ * for non-system groups.
+ */
+ *preferred_min = *min_id;
+
+ /* Check that the ranges make sense */
+ if (*max_id < *min_id) {
+ (void) fprintf (stderr,
+ _("%s: Invalid configuration: GID_MIN (%lu), "
+ "GID_MAX (%lu)\n"),
+ Prog, (unsigned long) *min_id,
+ (unsigned long) *max_id);
+ return EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * check_gid - See if the requested GID is available
+ *
+ * On success, return 0
+ * If the ID is in use, return EEXIST
+ * If the ID is outside the range, return ERANGE
+ * In other cases, return errno from getgrgid()
+ */
+static int check_gid (const gid_t gid,
+ const gid_t gid_min,
+ const gid_t gid_max,
+ bool *used_gids)
+{
+ /* First test that the preferred ID is in the range */
+ if (gid < gid_min || gid > gid_max) {
+ return ERANGE;
+ }
+
+ /*
+ * Check whether we already detected this GID
+ * using the gr_next() loop
+ */
+ if (used_gids != NULL && used_gids[gid]) {
+ return EEXIST;
+ }
+ /* Check if the GID exists according to NSS */
+ errno = 0;
+ if (getgrgid (gid) != NULL) {
+ return EEXIST;
+ } else {
+ /* getgrgid() was NULL
+ * we have to ignore errors as temporary
+ * failures of remote user identity services
+ * would completely block user/group creation
+ */
+ }
+
+ /* If we've made it here, the GID must be available */
+ return 0;
+}
+
/*
* find_new_gid - Find a new unused GID.
*
* 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)
+ gid_t *gid,
+ /*@null@*/gid_t const *preferred_gid)
{
- const struct group *grp;
- gid_t gid_min, gid_max, group_id;
bool *used_gids;
+ const struct group *grp;
+ gid_t gid_min, gid_max, preferred_min;
+ gid_t group_id, id;
+ gid_t lowest_found, highest_found;
+ int result;
+ int nospam = 0;
- assert (gid != NULL);
+ 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);
+ /*
+ * First, figure out what ID range is appropriate for
+ * automatic assignment
+ */
+ result = get_ranges (sys_group, &gid_min, &gid_max, &preferred_min);
+ if (result == EINVAL) {
+ return -1;
+ }
+
+ /* Check if the preferred GID is available */
+ if (preferred_gid) {
+ result = check_gid (*preferred_gid, preferred_min, gid_max, NULL);
+ if (result == 0) {
+ /*
+ * Make sure the GID isn't queued for use already
+ */
+ if (gr_locate_gid (*preferred_gid) == NULL) {
+ *gid = *preferred_gid;
+ return 0;
+ }
+ /*
+ * gr_locate_gid() found the GID in an as-yet uncommitted
+ * entry. We'll proceed below and auto-set a GID.
+ */
+ } else if (result == EEXIST || result == ERANGE) {
+ /*
+ * Continue on below. At this time, we won't
+ * treat these two cases differently.
+ */
+ } else {
+ /*
+ * An unexpected error occurred. We should report
+ * this and fail the group creation.
+ * This differs from the automatic creation
+ * behavior below, since if a specific GID was
+ * requested and generated an error, the user is
+ * more likely to want to stop and address the
+ * issue.
+ */
+ fprintf (stderr,
+ _("%s: Encountered error attempting to use "
+ "preferred GID: %s\n"),
+ Prog, strerror (result));
return -1;
}
}
+
+ /*
+ * Search the entire group file,
+ * looking for the next unused value.
+ *
+ * We first check the local database with gr_rewind/gr_next to find
+ * all local values that are in use.
+ *
+ * We then compare the next free value to all databases (local and
+ * remote) and iterate until we find a free one. If there are free
+ * values beyond the lowest (system groups) or highest (non-system
+ * groups), we will prefer those and avoid potentially reclaiming a
+ * deleted group (which can be a security issue, since it may grant
+ * access to files belonging to that former group).
+ *
+ * If there are no GIDs available at the end of the search, we will
+ * have no choice but to iterate through the range looking for gaps.
+ *
+ */
+
+ /* Create an array to hold all of the discovered GIDs */
used_gids = malloc (sizeof (bool) * (gid_max +1));
if (NULL == used_gids) {
fprintf (stderr,
- _("%s: failed to allocate memory: %s\n"),
- Prog, strerror (errno));
+ _("%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;
- }
+ /* First look for the lowest and highest value in the local database */
+ (void) gr_rewind ();
+ highest_found = gid_min;
+ lowest_found = gid_max;
+ while ((grp = gr_next ()) != NULL) {
+ /*
+ * Does this entry have a lower GID than the lowest we've found
+ * so far?
+ */
+ if ((grp->gr_gid <= lowest_found) && (grp->gr_gid >= gid_min)) {
+ lowest_found = grp->gr_gid - 1;
+ }
+ /*
+ * Does this entry have a higher GID than the highest we've found
+ * so far?
+ */
+ if ((grp->gr_gid >= highest_found) && (grp->gr_gid <= gid_max)) {
+ highest_found = grp->gr_gid + 1;
+ }
+
+ /* create index of used GIDs */
+ if (grp->gr_gid >= gid_min
+ && grp->gr_gid <= gid_max) {
+
+ used_gids[grp->gr_gid] = true;
+ }
+ }
- /*
- * 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.
+ /*
+ * For system groups, we want to start from the
+ * top of the range and work downwards.
*/
- group_id = gid_max;
- for (id = gid_max; id >= gid_min; id--) {
- if (getgrgid (id) != NULL) {
- group_id = id - 1;
- used_gids[id] = true;
- }
+
+ /*
+ * At the conclusion of the gr_next() search, we will either
+ * have a presumed-free GID or we will be at GID_MIN - 1.
+ */
+ if (lowest_found < gid_min) {
+ /*
+ * In this case, a GID is in use at GID_MIN.
+ *
+ * We will reset the search to GID_MAX and proceed down
+ * through all the GIDs (skipping those we detected with
+ * used_gids) for a free one. It is a known issue that
+ * this may result in reusing a previously-deleted GID,
+ * so administrators should be instructed to use this
+ * auto-detection with care (and prefer to assign GIDs
+ * explicitly).
+ */
+ lowest_found = gid_max;
}
- (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;
+ /* Search through all of the IDs in the range */
+ for (id = lowest_found; id >= gid_min; id--) {
+ result = check_gid (id, gid_min, gid_max, used_gids);
+ if (result == 0) {
+ /* This GID is available. Return it. */
+ *gid = id;
+ free (used_gids);
+ return 0;
+ } else if (result == EEXIST) {
+ /* This GID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique system GID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG ((LOG_ERR,
+ "Error checking available GIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later GID
+ * will work properly.
+ */
}
}
- } 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;
+
+ /*
+ * If we get all the way through the loop, try again from GID_MAX,
+ * unless that was where we previously started. (NOTE: the worst-case
+ * scenario here is that we will run through (GID_MAX - GID_MIN - 1)
+ * cycles *again* if we fall into this case with lowest_found as
+ * GID_MAX - 1, all groups in the range in use and maintained by
+ * network services such as LDAP.)
+ */
+ if (lowest_found != gid_max) {
+ for (id = gid_max; id >= gid_min; id--) {
+ result = check_gid (id, gid_min, gid_max, used_gids);
+ if (result == 0) {
+ /* This GID is available. Return it. */
+ *gid = id;
+ free (used_gids);
+ return 0;
+ } else if (result == EEXIST) {
+ /* This GID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique system GID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG ((LOG_ERR,
+ "Error checking available GIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later GID
+ * will work properly.
+ */
+ }
}
}
- endgrent ();
+ } else { /* !sys_group */
+ /*
+ * For non-system groups, we want to start from the
+ * bottom of the range and work upwards.
+ */
- (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;
- }
+ /*
+ * At the conclusion of the gr_next() search, we will either
+ * have a presumed-free GID or we will be at GID_MAX + 1.
+ */
+ if (highest_found > gid_max) {
+ /*
+ * In this case, a GID is in use at GID_MAX.
+ *
+ * We will reset the search to GID_MIN and proceed up
+ * through all the GIDs (skipping those we detected with
+ * used_gids) for a free one. It is a known issue that
+ * this may result in reusing a previously-deleted GID,
+ * so administrators should be instructed to use this
+ * auto-detection with care (and prefer to assign GIDs
+ * explicitly).
+ */
+ highest_found = gid_min;
}
- }
- /*
- * 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"));
+ /* Search through all of the IDs in the range */
+ for (id = highest_found; id <= gid_max; id++) {
+ result = check_gid (id, gid_min, gid_max, used_gids);
+ if (result == 0) {
+ /* This GID is available. Return it. */
+ *gid = id;
free (used_gids);
- return -1;
+ return 0;
+ } else if (result == EEXIST) {
+ /* This GID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique GID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG ((LOG_ERR,
+ "Error checking available GIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later GID
+ * will work properly.
+ */
}
}
- } 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 we get all the way through the loop, try again from GID_MIN,
+ * unless that was where we previously started. (NOTE: the worst-case
+ * scenario here is that we will run through (GID_MAX - GID_MIN - 1)
+ * cycles *again* if we fall into this case with highest_found as
+ * GID_MIN + 1, all groups in the range in use and maintained by
+ * network services such as LDAP.)
+ */
+ if (highest_found != gid_min) {
+ for (id = gid_min; id <= gid_max; id++) {
+ result = check_gid (id, gid_min, gid_max, used_gids);
+ if (result == 0) {
+ /* This GID is available. Return it. */
+ *gid = id;
+ free (used_gids);
+ return 0;
+ } else if (result == EEXIST) {
+ /* This GID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique GID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG ((LOG_ERR,
+ "Error checking available GIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later GID
+ * will work properly.
+ */
}
}
- 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;
- }
}
}
+ /* The code reached here and found no available IDs in the range */
+ fprintf (stderr,
+ _("%s: Can't get unique GID (no more available GIDs)\n"),
+ Prog);
+ SYSLOG ((LOG_WARN, "no more available GIDs on the system"));
free (used_gids);
- *gid = group_id;
- return 0;
+ return -1;
}
/*
* Copyright (c) 1991 - 1994, Julianne Frances Haugh
* Copyright (c) 2008 - 2011, Nicolas François
+ * Copyright (c) 2014, Red Hat, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
#include "pwio.h"
#include "getdef.h"
+/*
+ * get_ranges - Get the minimum and maximum ID ranges for the search
+ *
+ * This function will return the minimum and maximum ranges for IDs
+ *
+ * 0: The function completed successfully
+ * EINVAL: The provided ranges are impossible (such as maximum < minimum)
+ *
+ * preferred_min: The special-case minimum value for a specifically-
+ * requested ID, which may be lower than the standard min_id
+ */
+static int get_ranges (bool sys_user, uid_t *min_id, uid_t *max_id,
+ uid_t *preferred_min)
+{
+ uid_t uid_def_max = 0;
+
+ if (sys_user) {
+ /* System users */
+
+ /* A requested ID is allowed to be below the autoselect range */
+ *preferred_min = (uid_t) 1;
+
+ /* Get the minimum ID range from login.defs or default to 101 */
+ *min_id = (uid_t) getdef_ulong ("SYS_UID_MIN", 101UL);
+
+ /*
+ * If SYS_UID_MAX is unspecified, we should assume it to be one
+ * less than the UID_MIN (which is reserved for non-system accounts)
+ */
+ uid_def_max = (uid_t) getdef_ulong ("UID_MIN", 1000UL) - 1;
+ *max_id = (uid_t) getdef_ulong ("SYS_UID_MAX",
+ (unsigned long) uid_def_max);
+
+ /* Check that the ranges make sense */
+ if (*max_id < *min_id) {
+ (void) fprintf (stderr,
+ _("%s: Invalid configuration: SYS_UID_MIN (%lu), "
+ "UID_MIN (%lu), SYS_UID_MAX (%lu)\n"),
+ Prog, (unsigned long) *min_id,
+ getdef_ulong ("UID_MIN", 1000UL),
+ (unsigned long) *max_id);
+ return EINVAL;
+ }
+ } else {
+ /* Non-system users */
+
+ /* Get the values from login.defs or use reasonable defaults */
+ *min_id = (uid_t) getdef_ulong ("UID_MIN", 1000UL);
+ *max_id = (uid_t) getdef_ulong ("UID_MAX", 60000UL);
+
+ /*
+ * The preferred minimum should match the standard ID minimum
+ * for non-system users.
+ */
+ *preferred_min = *min_id;
+
+ /* Check that the ranges make sense */
+ if (*max_id < *min_id) {
+ (void) fprintf (stderr,
+ _("%s: Invalid configuration: UID_MIN (%lu), "
+ "UID_MAX (%lu)\n"),
+ Prog, (unsigned long) *min_id,
+ (unsigned long) *max_id);
+ return EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * check_uid - See if the requested UID is available
+ *
+ * On success, return 0
+ * If the ID is in use, return EEXIST
+ * If the ID is outside the range, return ERANGE
+ * In other cases, return errno from getpwuid()
+ */
+static int check_uid(const uid_t uid,
+ const uid_t uid_min,
+ const uid_t uid_max,
+ bool *used_uids)
+{
+ /* First test that the preferred ID is in the range */
+ if (uid < uid_min || uid > uid_max) {
+ return ERANGE;
+ }
+
+ /*
+ * Check whether we already detected this UID
+ * using the pw_next() loop
+ */
+ if (used_uids != NULL && used_uids[uid]) {
+ return EEXIST;
+ }
+ /* Check if the UID exists according to NSS */
+ errno = 0;
+ if (getpwuid(uid) != NULL) {
+ return EEXIST;
+ } else {
+ /* getpwuid() was NULL
+ * we have to ignore errors as temporary
+ * failures of remote user identity services
+ * would completely block user/group creation
+ */
+ }
+
+ /* If we've made it here, the UID must be available */
+ return 0;
+}
+
/*
* find_new_uid - Find a new unused UID.
*
*
* 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)
+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;
+ const struct passwd *pwd;
+ uid_t uid_min, uid_max, preferred_min;
+ uid_t user_id, id;
+ uid_t lowest_found, highest_found;
+ int result;
+ int nospam = 0;
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);
+ /*
+ * First, figure out what ID range is appropriate for
+ * automatic assignment
+ */
+ result = get_ranges (sys_user, &uid_min, &uid_max, &preferred_min);
+ if (result == EINVAL) {
+ return -1;
+ }
+
+ /* Check if the preferred UID is available */
+ if (preferred_uid) {
+ result = check_uid (*preferred_uid, preferred_min, uid_max, NULL);
+ if (result == 0) {
+ /*
+ * Make sure the UID isn't queued for use already
+ */
+ if (pw_locate_uid (*preferred_uid) == NULL) {
+ *uid = *preferred_uid;
+ return 0;
+ }
+ /*
+ * pw_locate_uid() found the UID in an as-yet uncommitted
+ * entry. We'll proceed below and auto-set an UID.
+ */
+ } else if (result == EEXIST || result == ERANGE) {
+ /*
+ * Continue on below. At this time, we won't
+ * treat these two cases differently.
+ */
+ } else {
+ /*
+ * An unexpected error occurred. We should report
+ * this and fail the user creation.
+ * This differs from the automatic creation
+ * behavior below, since if a specific UID was
+ * requested and generated an error, the user is
+ * more likely to want to stop and address the
+ * issue.
+ */
+ fprintf (stderr,
+ _("%s: Encountered error attempting to use "
+ "preferred UID: %s\n"),
+ Prog, strerror (result));
return -1;
}
}
+
+ /*
+ * Search the entire passwd file,
+ * looking for the next unused value.
+ *
+ * We first check the local database with pw_rewind/pw_next to find
+ * all local values that are in use.
+ *
+ * We then compare the next free value to all databases (local and
+ * remote) and iterate until we find a free one. If there are free
+ * values beyond the lowest (system users) or highest (non-system
+ * users), we will prefer those and avoid potentially reclaiming a
+ * deleted user (which can be a security issue, since it may grant
+ * access to files belonging to that former user).
+ *
+ * If there are no UIDs available at the end of the search, we will
+ * have no choice but to iterate through the range looking for gaps.
+ *
+ */
+
+ /* Create an array to hold all of the discovered UIDs */
used_uids = malloc (sizeof (bool) * (uid_max +1));
if (NULL == used_uids) {
fprintf (stderr,
- _("%s: failed to allocate memory: %s\n"),
- Prog, strerror (errno));
+ _("%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;
- }
+ /* First look for the lowest and highest value in the local database */
+ (void) pw_rewind ();
+ highest_found = uid_min;
+ lowest_found = uid_max;
+ while ((pwd = pw_next ()) != NULL) {
+ /*
+ * Does this entry have a lower UID than the lowest we've found
+ * so far?
+ */
+ if ((pwd->pw_uid <= lowest_found) && (pwd->pw_uid >= uid_min)) {
+ lowest_found = pwd->pw_uid - 1;
+ }
+ /*
+ * Does this entry have a higher UID than the highest we've found
+ * so far?
+ */
+ if ((pwd->pw_uid >= highest_found) && (pwd->pw_uid <= uid_max)) {
+ highest_found = pwd->pw_uid + 1;
+ }
+
+ /* create index of used UIDs */
+ if (pwd->pw_uid >= uid_min
+ && pwd->pw_uid <= uid_max) {
+
+ used_uids[pwd->pw_uid] = true;
+ }
+ }
- /*
- * 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.
+ /*
+ * For system users, we want to start from the
+ * top of the range and work downwards.
*/
- user_id = uid_max;
- for (id = uid_max; id >= uid_min; id--) {
- if (getpwuid (id) != NULL) {
- user_id = id - 1;
- used_uids[id] = true;
- }
+
+ /*
+ * At the conclusion of the pw_next() search, we will either
+ * have a presumed-free UID or we will be at UID_MIN - 1.
+ */
+ if (lowest_found < uid_min) {
+ /*
+ * In this case, an UID is in use at UID_MIN.
+ *
+ * We will reset the search to UID_MAX and proceed down
+ * through all the UIDs (skipping those we detected with
+ * used_uids) for a free one. It is a known issue that
+ * this may result in reusing a previously-deleted UID,
+ * so administrators should be instructed to use this
+ * auto-detection with care (and prefer to assign UIDs
+ * explicitly).
+ */
+ lowest_found = uid_max;
}
- (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;
+ /* Search through all of the IDs in the range */
+ for (id = lowest_found; id >= uid_min; id--) {
+ result = check_uid (id, uid_min, uid_max, used_uids);
+ if (result == 0) {
+ /* This UID is available. Return it. */
+ *uid = id;
+ free (used_uids);
+ return 0;
+ } else if (result == EEXIST) {
+ /* This UID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique system UID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG ((LOG_ERR,
+ "Error checking available UIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later UID
+ * will work properly.
+ */
}
}
- } 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;
+
+ /*
+ * If we get all the way through the loop, try again from UID_MAX,
+ * unless that was where we previously started. (NOTE: the worst-case
+ * scenario here is that we will run through (UID_MAX - UID_MIN - 1)
+ * cycles *again* if we fall into this case with lowest_found as
+ * UID_MAX - 1, all users in the range in use and maintained by
+ * network services such as LDAP.)
+ */
+ if (lowest_found != uid_max) {
+ for (id = uid_max; id >= uid_min; id--) {
+ result = check_uid (id, uid_min, uid_max, used_uids);
+ if (result == 0) {
+ /* This UID is available. Return it. */
+ *uid = id;
+ free (used_uids);
+ return 0;
+ } else if (result == EEXIST) {
+ /* This UID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique system UID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG((LOG_ERR,
+ "Error checking available UIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later UID
+ * will work properly.
+ */
+ }
}
}
- endpwent ();
+ } else { /* !sys_user */
+ /*
+ * For non-system users, we want to start from the
+ * bottom of the range and work upwards.
+ */
- (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;
- }
+ /*
+ * At the conclusion of the pw_next() search, we will either
+ * have a presumed-free UID or we will be at UID_MAX + 1.
+ */
+ if (highest_found > uid_max) {
+ /*
+ * In this case, a UID is in use at UID_MAX.
+ *
+ * We will reset the search to UID_MIN and proceed up
+ * through all the UIDs (skipping those we detected with
+ * used_uids) for a free one. It is a known issue that
+ * this may result in reusing a previously-deleted UID,
+ * so administrators should be instructed to use this
+ * auto-detection with care (and prefer to assign UIDs
+ * explicitly).
+ */
+ highest_found = uid_min;
}
- }
- /*
- * 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"));
+ /* Search through all of the IDs in the range */
+ for (id = highest_found; id <= uid_max; id++) {
+ result = check_uid (id, uid_min, uid_max, used_uids);
+ if (result == 0) {
+ /* This UID is available. Return it. */
+ *uid = id;
free (used_uids);
- return -1;
+ return 0;
+ } else if (result == EEXIST) {
+ /* This UID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique UID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG ((LOG_ERR,
+ "Error checking available UIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later UID
+ * will work properly.
+ */
}
}
- } 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 we get all the way through the loop, try again from UID_MIN,
+ * unless that was where we previously started. (NOTE: the worst-case
+ * scenario here is that we will run through (UID_MAX - UID_MIN - 1)
+ * cycles *again* if we fall into this case with highest_found as
+ * UID_MIN + 1, all users in the range in use and maintained by
+ * network services such as LDAP.)
+ */
+ if (highest_found != uid_min) {
+ for (id = uid_min; id <= uid_max; id++) {
+ result = check_uid (id, uid_min, uid_max, used_uids);
+ if (result == 0) {
+ /* This UID is available. Return it. */
+ *uid = id;
+ free (used_uids);
+ return 0;
+ } else if (result == EEXIST) {
+ /* This UID is in use, we'll continue to the next */
+ } else {
+ /*
+ * An unexpected error occurred.
+ *
+ * Only report it the first time to avoid spamming
+ * the logs
+ *
+ */
+ if (!nospam) {
+ fprintf (stderr,
+ _("%s: Can't get unique UID (%s). "
+ "Suppressing additional messages.\n"),
+ Prog, strerror (result));
+ SYSLOG ((LOG_ERR,
+ "Error checking available UIDs: %s",
+ strerror (result)));
+ nospam = 1;
+ }
+ /*
+ * We will continue anyway. Hopefully a later UID
+ * will work properly.
+ */
}
}
- 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;
- }
}
}
+ /* The code reached here and found no available IDs in the range */
+ fprintf (stderr,
+ _("%s: Can't get unique UID (no more available UIDs)\n"),
+ Prog);
+ SYSLOG ((LOG_WARN, "no more available UIDs on the system"));
free (used_uids);
- *uid = user_id;
- return 0;
+ return -1;
}
projects / thirdparty / shadow.git / commitdiff
