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Diffstat (limited to 'libmisc/find_new_uid.c')
| -rw-r--r-- | libmisc/find_new_uid.c | 483 |
1 files changed, 0 insertions, 483 deletions
diff --git a/libmisc/find_new_uid.c b/libmisc/find_new_uid.c deleted file mode 100644 index 5f7e74b..0000000 --- a/libmisc/find_new_uid.c +++ /dev/null @@ -1,483 +0,0 @@ -/* - * SPDX-FileCopyrightText: 1991 - 1994, Julianne Frances Haugh - * SPDX-FileCopyrightText: 2008 - 2011, Nicolas François - * SPDX-FileCopyrightText: 2014, Red Hat, Inc. - * - * SPDX-License-Identifier: BSD-3-Clause - */ - -#include <config.h> - -#include <assert.h> -#include <stdio.h> -#include <errno.h> - -#include "prototypes.h" -#include "pwio.h" -#include "getdef.h" -#include "shadowlog.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 (log_get_logfd(), - _("%s: Invalid configuration: SYS_UID_MIN (%lu), " - "UID_MIN (%lu), SYS_UID_MAX (%lu)\n"), - log_get_progname(), (unsigned long) *min_id, - getdef_ulong ("UID_MIN", 1000UL), - (unsigned long) *max_id); - return EINVAL; - } - /* - * Zero is reserved for root and the allocation algorithm does not - * work right with it. - */ - if (*min_id == 0) { - *min_id = (uid_t) 1; - } - } 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 (log_get_logfd(), - _("%s: Invalid configuration: UID_MIN (%lu), " - "UID_MAX (%lu)\n"), - log_get_progname(), (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, - const 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 (prefix_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. - * - * 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) -{ - bool *used_uids; - const struct passwd *pwd; - uid_t uid_min, uid_max, preferred_min; - uid_t id; - uid_t lowest_found, highest_found; - int result; - int nospam = 0; - - assert (uid != NULL); - - /* - * 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 (log_get_logfd(), - _("%s: Encountered error attempting to use " - "preferred UID: %s\n"), - log_get_progname(), 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 (log_get_logfd(), - _("%s: failed to allocate memory: %s\n"), - log_get_progname(), strerror (errno)); - return -1; - } - memset (used_uids, false, sizeof (bool) * (uid_max + 1)); - - /* 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; - } - } - - if (sys_user) { - /* - * For system users, we want to start from the - * top of the range and work downwards. - */ - - /* - * 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; - } - - /* 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 (log_get_logfd(), - _("%s: Can't get unique system UID (%s). " - "Suppressing additional messages.\n"), - log_get_progname(), 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 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 (log_get_logfd(), - _("%s: Can't get unique system UID (%s). " - "Suppressing additional messages.\n"), - log_get_progname(), 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 { /* !sys_user */ - /* - * For non-system users, we want to start from the - * bottom of the range and work upwards. - */ - - /* - * 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; - } - - /* 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 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 (log_get_logfd(), - _("%s: Can't get unique UID (%s). " - "Suppressing additional messages.\n"), - log_get_progname(), 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 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 (log_get_logfd(), - _("%s: Can't get unique UID (%s). " - "Suppressing additional messages.\n"), - log_get_progname(), 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. - */ - } - } - } - } - - /* The code reached here and found no available IDs in the range */ - fprintf (log_get_logfd(), - _("%s: Can't get unique UID (no more available UIDs)\n"), - log_get_progname()); - SYSLOG ((LOG_WARN, "no more available UIDs on the system")); - free (used_uids); - return -1; -} - |