shadow/src/grpunconv.c
Jakub Hrozek 4aaf05d72e Flush sssd caches in addition to nscd caches
Some distributions, notably Fedora, have the following order of nsswitch
modules by default:
    passwd: sss files
    group:  sss files

The advantage of serving local users through SSSD is that the nss_sss
module has a fast mmapped-cache that speeds up NSS lookups compared to
accessing the disk an opening the files on each NSS request.

Traditionally, this has been done with the help of nscd, but using nscd
in parallel with sssd is cumbersome, as both SSSD and nscd use their own
independent caching, so using nscd in setups where sssd is also serving
users from some remote domain (LDAP, AD, ...) can result in a bit of
unpredictability.

More details about why Fedora chose to use sss before files can be found
on e.g.:
    https://fedoraproject.org//wiki/Changes/SSSDCacheForLocalUsers
or:
    https://docs.pagure.org/SSSD.sssd/design_pages/files_provider.html

Now, even though sssd watches the passwd and group files with the help
of inotify, there can still be a small window where someone requests a
user or a group, finds that it doesn't exist, adds the entry and checks
again. Without some support in shadow-utils that would explicitly drop
the sssd caches, the inotify watch can fire a little late, so a
combination of commands like this:
    getent passwd user || useradd user; getent passwd user
can result in the second getent passwd not finding the newly added user
as the racy behaviour might still return the cached negative hit from
the first getent passwd.

This patch more or less copies the already existing support that
shadow-utils had for dropping nscd caches, except using the "sss_cache"
tool that sssd ships.
2018-09-13 14:20:02 +02:00

253 lines
6.6 KiB
C

/*
* Copyright (c) 1996 , Michael Meskes
* Copyright (c) 1996 - 2000, Marek Michałkiewicz
* Copyright (c) 2002 - 2006, Tomasz Kłoczko
* 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.
*/
/*
* grpunconv - update /etc/group with information from /etc/gshadow.
*
*/
#include <config.h>
#ident "$Id$"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <unistd.h>
#include <grp.h>
#include <getopt.h>
#include "nscd.h"
#include "sssd.h"
#include "prototypes.h"
/*@-exitarg@*/
#include "exitcodes.h"
#ifdef SHADOWGRP
#include "groupio.h"
#include "sgroupio.h"
/*
* Global variables
*/
const char *Prog;
static bool gr_locked = false;
static bool sgr_locked = false;
/* local function prototypes */
static void fail_exit (int status);
static void usage (int status);
static void process_flags (int argc, char **argv);
static void fail_exit (int status)
{
if (gr_locked) {
if (gr_unlock () == 0) {
fprintf (stderr, _("%s: failed to unlock %s\n"), Prog, gr_dbname ());
SYSLOG ((LOG_ERR, "failed to unlock %s", gr_dbname ()));
/* continue */
}
}
if (sgr_locked) {
if (sgr_unlock () == 0) {
fprintf (stderr, _("%s: failed to unlock %s\n"), Prog, sgr_dbname ());
SYSLOG ((LOG_ERR, "failed to unlock %s", sgr_dbname ()));
/* continue */
}
}
exit (status);
}
static void usage (int status)
{
FILE *usageout = (E_SUCCESS != status) ? stderr : stdout;
(void) fprintf (usageout,
_("Usage: %s [options]\n"
"\n"
"Options:\n"),
Prog);
(void) fputs (_(" -h, --help display this help message and exit\n"), usageout);
(void) fputs (_(" -R, --root CHROOT_DIR directory to chroot into\n"), usageout);
(void) fputs ("\n", usageout);
exit (status);
}
/*
* process_flags - parse the command line options
*
* It will not return if an error is encountered.
*/
static void process_flags (int argc, char **argv)
{
/*
* Parse the command line options.
*/
int c;
static struct option long_options[] = {
{"help", no_argument, NULL, 'h'},
{"root", required_argument, NULL, 'R'},
{NULL, 0, NULL, '\0'}
};
while ((c = getopt_long (argc, argv, "hR:",
long_options, NULL)) != -1) {
switch (c) {
case 'h':
usage (E_SUCCESS);
/*@notreached@*/break;
case 'R': /* no-op, handled in process_root_flag () */
break;
default:
usage (E_USAGE);
}
}
if (optind != argc) {
usage (E_USAGE);
}
}
int main (int argc, char **argv)
{
const struct group *gr;
struct group grent;
const struct sgrp *sg;
Prog = Basename (argv[0]);
(void) setlocale (LC_ALL, "");
(void) bindtextdomain (PACKAGE, LOCALEDIR);
(void) textdomain (PACKAGE);
process_root_flag ("-R", argc, argv);
OPENLOG ("grpunconv");
process_flags (argc, argv);
if (sgr_file_present () == 0) {
exit (0); /* no /etc/gshadow, nothing to do */
}
if (gr_lock () == 0) {
fprintf (stderr,
_("%s: cannot lock %s; try again later.\n"),
Prog, gr_dbname ());
fail_exit (5);
}
gr_locked = true;
if (gr_open (O_CREAT | O_RDWR) == 0) {
fprintf (stderr,
_("%s: cannot open %s\n"), Prog, gr_dbname ());
fail_exit (1);
}
if (sgr_lock () == 0) {
fprintf (stderr,
_("%s: cannot lock %s; try again later.\n"),
Prog, sgr_dbname ());
fail_exit (5);
}
sgr_locked = true;
if (sgr_open (O_RDONLY) == 0) {
fprintf (stderr,
_("%s: cannot open %s\n"), Prog, sgr_dbname ());
fail_exit (1);
}
/*
* Update group passwords if non-shadow password is "x".
*/
(void) gr_rewind ();
while ((gr = gr_next ()) != NULL) {
sg = sgr_locate (gr->gr_name);
if ( (NULL != sg)
&& (strcmp (gr->gr_passwd, SHADOW_PASSWD_STRING) == 0)) {
/* add password to /etc/group */
grent = *gr;
grent.gr_passwd = sg->sg_passwd;
if (gr_update (&grent) == 0) {
fprintf (stderr,
_("%s: failed to prepare the new %s entry '%s'\n"),
Prog, gr_dbname (), grent.gr_name);
fail_exit (3);
}
}
}
(void) sgr_close (); /* was only open O_RDONLY */
if (gr_close () == 0) {
fprintf (stderr,
_("%s: failure while writing changes to %s\n"),
Prog, gr_dbname ());
SYSLOG ((LOG_ERR, "failure while writing changes to %s", gr_dbname ()));
fail_exit (3);
}
if (unlink (SGROUP_FILE) != 0) {
fprintf (stderr,
_("%s: cannot delete %s\n"),
Prog, SGROUP_FILE);
SYSLOG ((LOG_ERR, "cannot delete %s", SGROUP_FILE));
fail_exit (3);
}
if (gr_unlock () == 0) {
fprintf (stderr, _("%s: failed to unlock %s\n"), Prog, gr_dbname ());
SYSLOG ((LOG_ERR, "failed to unlock %s", gr_dbname ()));
/* continue */
}
if (sgr_unlock () == 0) {
fprintf (stderr, _("%s: failed to unlock %s\n"), Prog, sgr_dbname ());
SYSLOG ((LOG_ERR, "failed to unlock %s", sgr_dbname ()));
/* continue */
}
nscd_flush_cache ("group");
sssd_flush_cache (SSSD_DB_GROUP);
return 0;
}
#else /* !SHADOWGRP */
int main (int unused(argc), char **argv)
{
fprintf (stderr,
"%s: not configured for shadow group support.\n", argv[0]);
exit (1);
}
#endif /* !SHADOWGRP */