shadow/libmisc/find_new_sub_uids.c
Stéphane Graber 65c2617140
Tweak uid/gid map default configuration
- Use an allocation of 65536 uids and gids to allow for POSIX-compliant
   user owned namespaces.
 - Don't allocate a uid/gid map to system users.
   Unfortunately checking for --system isn't quite enough as some
   distribution wrappers always call useradd without --system and take care
   of choosing a uid and gid themselves, so also check whether the
   requested uid/gid is in the user range.

This is taken from a patch I wrote for Ubuntu a couple years ago and
which somehow didn't make it upstream.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
2016-02-15 18:11:10 -05:00

87 lines
3.0 KiB
C

/*
* Copyright (c) 2012 Eric Biederman
*
* 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>
#ifdef ENABLE_SUBIDS
#include <assert.h>
#include <stdio.h>
#include <errno.h>
#include "prototypes.h"
#include "subordinateio.h"
#include "getdef.h"
/*
* find_new_sub_uids - Find a new unused range of UIDs.
*
* If successful, find_new_sub_uids provides a range of unused
* user IDs in the [SUB_UID_MIN:SUB_UID_MAX] range.
*
* Return 0 on success, -1 if no unused UIDs are available.
*/
int find_new_sub_uids (const char *owner,
uid_t *range_start, unsigned long *range_count)
{
unsigned long min, max;
unsigned long count;
uid_t start;
assert (range_start != NULL);
assert (range_count != NULL);
min = getdef_ulong ("SUB_UID_MIN", 100000UL);
max = getdef_ulong ("SUB_UID_MAX", 600100000UL);
count = getdef_ulong ("SUB_UID_COUNT", 65536);
if (min > max || count >= max || (min + count - 1) > max) {
(void) fprintf (stderr,
_("%s: Invalid configuration: SUB_UID_MIN (%lu),"
" SUB_UID_MAX (%lu), SUB_UID_COUNT (%lu)\n"),
Prog, min, max, count);
return -1;
}
start = sub_uid_find_free_range(min, max, count);
if (start == (uid_t)-1) {
fprintf (stderr,
_("%s: Can't get unique subordinate UID range\n"),
Prog);
SYSLOG ((LOG_WARN, "no more available subordinate UIDs on the system"));
return -1;
}
*range_start = start;
*range_count = count;
return 0;
}
#else /* !ENABLE_SUBIDS */
extern int errno; /* warning: ANSI C forbids an empty source file */
#endif /* !ENABLE_SUBIDS */