477 lines
13 KiB
C
477 lines
13 KiB
C
/*
|
|
* 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 "groupio.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_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 (log_get_logfd(),
|
|
_("%s: Invalid configuration: SYS_GID_MIN (%lu), "
|
|
"GID_MIN (%lu), SYS_GID_MAX (%lu)\n"),
|
|
log_get_progname(), (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 (log_get_logfd(),
|
|
_("%s: Invalid configuration: GID_MIN (%lu), "
|
|
"GID_MAX (%lu)\n"),
|
|
log_get_progname(), (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,
|
|
const 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 (prefix_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.
|
|
*
|
|
* 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)
|
|
{
|
|
bool *used_gids;
|
|
const struct group *grp;
|
|
gid_t gid_min, gid_max, preferred_min;
|
|
gid_t id;
|
|
gid_t lowest_found, highest_found;
|
|
int result;
|
|
int nospam = 0;
|
|
|
|
assert(gid != NULL);
|
|
|
|
/*
|
|
* 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 (log_get_logfd(),
|
|
_("%s: Encountered error attempting to use "
|
|
"preferred GID: %s\n"),
|
|
log_get_progname(), 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 (log_get_logfd(),
|
|
_("%s: failed to allocate memory: %s\n"),
|
|
log_get_progname(), strerror (errno));
|
|
return -1;
|
|
}
|
|
memset (used_gids, false, sizeof (bool) * (gid_max + 1));
|
|
|
|
/* 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;
|
|
}
|
|
}
|
|
|
|
if (sys_group) {
|
|
/*
|
|
* For system groups, we want to start from the
|
|
* top of the range and work downwards.
|
|
*/
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
/* 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 (log_get_logfd(),
|
|
_("%s: Can't get unique system GID (%s). "
|
|
"Suppressing additional messages.\n"),
|
|
log_get_progname(), 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 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 (log_get_logfd(),
|
|
_("%s: Can't get unique system GID (%s). "
|
|
"Suppressing additional messages.\n"),
|
|
log_get_progname(), 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 { /* !sys_group */
|
|
/*
|
|
* For non-system groups, we want to start from the
|
|
* bottom of the range and work upwards.
|
|
*/
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
/* 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 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 (log_get_logfd(),
|
|
_("%s: Can't get unique GID (%s). "
|
|
"Suppressing additional messages.\n"),
|
|
log_get_progname(), 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 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 (log_get_logfd(),
|
|
_("%s: Can't get unique GID (%s). "
|
|
"Suppressing additional messages.\n"),
|
|
log_get_progname(), 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.
|
|
*/
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* The code reached here and found no available IDs in the range */
|
|
fprintf (log_get_logfd(),
|
|
_("%s: Can't get unique GID (no more available GIDs)\n"),
|
|
log_get_progname());
|
|
SYSLOG ((LOG_WARN, "no more available GIDs on the system"));
|
|
free (used_gids);
|
|
return -1;
|
|
}
|
|
|