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https://github.com/freebsd/freebsd-src
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pam: Add pam_xdg module
This is a module to setup the XDG directories and environment variables. For now the only usage is to have a XDG_RUNTIME_DIR environment setup at user login. All other environment variable have a default fallback so no need to export them in this module. The directory is created according to the XDG Base directory specification. The default base directory is /var/run/xdg/<username> but can be configured using the runtime_dir=<dir> module option. According to the spec the directory *must* not survive a reboot so adding var_run_enable="YES" to rc.conf is highly recommanded. Reviewed by: des, pauamma (manpages) Differential Revision: https://reviews.freebsd.org/D44011 Sponsored by: Beckhoff Automation GmbH & Co. KG
This commit is contained in:
Emmanuel Vadot
parent
1a56620b79
commit
6e69612d5d
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@ -30,3 +30,4 @@ MODULES += pam_ssh
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.endif
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MODULES += pam_tacplus
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MODULES += pam_unix
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MODULES += pam_xdg
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6
lib/libpam/modules/pam_xdg/Makefile
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6
lib/libpam/modules/pam_xdg/Makefile
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@ -0,0 +1,6 @@
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LIB= pam_xdg
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SRCS= pam_xdg.c
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MAN= pam_xdg.8
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.include <bsd.lib.mk>
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56
lib/libpam/modules/pam_xdg/pam_xdg.8
Normal file
56
lib/libpam/modules/pam_xdg/pam_xdg.8
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@ -0,0 +1,56 @@
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.\" * SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2024 Beckhoff Automation GmbH & Co. KG
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.\"
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.\" * Redistribution and use in source and binary forms, with or without
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.\" * modification, are permitted provided that the following conditions
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.\" * are met:
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.\" * 1. Redistributions of source code must retain the above copyright
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.\" * notice, this list of conditions and the following disclaimer.
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.\" * 2. Redistributions in binary form must reproduce the above copyright
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.\" * notice, this list of conditions and the following disclaimer in the
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.\" * documentation and/or other materials provided with the distribution.
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.\" *
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.\" * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" * SUCH DAMAGE.
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.Dd February 21, 2024
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.Dt PAM_XDG 8
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.Os
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.Sh NAME
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.Nm pam_xdg
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.Nd XDG PAM module
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.Sh SYNOPSIS
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.Op Ar service-name
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.Ar module-type
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.Ar control-flag
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.Pa pam_xdg
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.Op Ar arguments
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.Sh DESCRIPTION
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The xdg service module for PAM sets up the runtime directory according
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to the XDG specifications.
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.Pp
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By default the directory is created under
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.Pa /var/run/xdg/<username> .
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.Pp
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The following option may be passed to the authentication module:
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.Bl -tag -width ".Cm runtime_dir"
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.It Cm runtime_dir Ns = Ns Ar directory
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Use an alternate base directory
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.El
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.Sh SEE ALSO
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.Xr pam 3 ,
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.Xr pam.conf 5
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.Sh AUTHORS
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The
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.Nm
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module and this manual page were written by
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.An Emmanuel Vadot Aq Mt manu@FreeBSD.org .
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311
lib/libpam/modules/pam_xdg/pam_xdg.c
Normal file
311
lib/libpam/modules/pam_xdg/pam_xdg.c
Normal file
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@ -0,0 +1,311 @@
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/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2024 Beckhoff Automation GmbH & Co. KG
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/stat.h>
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <pwd.h>
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#define PAM_SM_SESSION
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#include <security/pam_appl.h>
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#include <security/pam_modules.h>
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#include <security/pam_mod_misc.h>
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#define BASE_RUNTIME_DIR_PREFIX "/var/run/xdg"
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#define RUNTIME_DIR_PREFIX runtime_dir_prefix != NULL ? runtime_dir_prefix : BASE_RUNTIME_DIR_PREFIX
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#define RUNTIME_DIR_PREFIX_MODE 0711
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#define RUNTIME_DIR_MODE 0700 /* XDG spec */
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#define XDG_MAX_SESSION 100 /* Arbitrary limit because we need one */
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static int
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_pam_xdg_open(pam_handle_t *pamh, int flags __unused,
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int argc __unused, const char *argv[] __unused)
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{
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struct passwd *passwd;
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const char *user;
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const char *runtime_dir_prefix;
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struct stat sb;
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char *runtime_dir = NULL;
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char *xdg_session_file;
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int rv, rt_dir_prefix, rt_dir, session_file, i;
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session_file = -1;
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rt_dir_prefix = -1;
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runtime_dir_prefix = openpam_get_option(pamh, "runtime_dir_prefix");
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/* Get user info */
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rv = pam_get_item(pamh, PAM_USER, (const void **)&user);
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if (rv != PAM_SUCCESS) {
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PAM_VERBOSE_ERROR("Can't get user information");
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goto out;
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}
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if ((passwd = getpwnam(user)) == NULL) {
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PAM_VERBOSE_ERROR("Can't get user information");
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Open or create the base xdg directory */
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rt_dir_prefix = open(RUNTIME_DIR_PREFIX, O_DIRECTORY | O_NOFOLLOW);
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if (rt_dir_prefix < 0) {
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rt_dir_prefix = mkdir(RUNTIME_DIR_PREFIX, RUNTIME_DIR_PREFIX_MODE);
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if (rt_dir_prefix != 0) {
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PAM_VERBOSE_ERROR("Can't mkdir %s", RUNTIME_DIR_PREFIX);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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rt_dir_prefix = open(RUNTIME_DIR_PREFIX, O_DIRECTORY | O_NOFOLLOW);
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}
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/* Open or create the user xdg directory */
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rt_dir = openat(rt_dir_prefix, user, O_DIRECTORY | O_NOFOLLOW);
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if (rt_dir < 0) {
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rt_dir = mkdirat(rt_dir_prefix, user, RUNTIME_DIR_MODE);
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if (rt_dir != 0) {
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PAM_VERBOSE_ERROR("mkdir: %s/%s (%d)", RUNTIME_DIR_PREFIX, user, rt_dir);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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rv = fchownat(rt_dir_prefix, user, passwd->pw_uid, passwd->pw_gid, 0);
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if (rv != 0) {
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PAM_VERBOSE_ERROR("fchownat: %s/%s (%d)", RUNTIME_DIR_PREFIX, user, rv);
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rv = unlinkat(rt_dir_prefix, user, AT_REMOVEDIR);
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if (rv == -1)
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PAM_VERBOSE_ERROR("unlinkat: %s/%s (%d)", RUNTIME_DIR_PREFIX, user, errno);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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} else {
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/* Check that the already create dir is correctly owned */
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rv = fstatat(rt_dir_prefix, user, &sb, 0);
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if (rv == -1) {
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PAM_VERBOSE_ERROR("fstatat %s/%s failed (%d)", RUNTIME_DIR_PREFIX, user, errno);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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if (sb.st_uid != passwd->pw_uid ||
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sb.st_gid != passwd->pw_gid) {
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PAM_VERBOSE_ERROR("%s/%s isn't owned by %d:%d\n", RUNTIME_DIR_PREFIX, user, passwd->pw_uid, passwd->pw_gid);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Test directory mode */
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if ((sb.st_mode & 0x1FF) != RUNTIME_DIR_MODE) {
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PAM_VERBOSE_ERROR("%s/%s have wrong mode\n", RUNTIME_DIR_PREFIX, user);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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}
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/* Setup the environment variable */
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asprintf(&runtime_dir, "XDG_RUNTIME_DIR=%s/%s", RUNTIME_DIR_PREFIX, user);
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rv = pam_putenv(pamh, runtime_dir);
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if (rv != PAM_SUCCESS) {
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PAM_VERBOSE_ERROR("pam_putenv: failed (%d)", rv);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Setup the session count file */
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for (i = 0; i < XDG_MAX_SESSION; i++) {
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asprintf(&xdg_session_file, "%s/xdg_session.%d", user, i);
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printf("Trying to open %s\n", xdg_session_file);
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session_file = openat(rt_dir_prefix, xdg_session_file, O_CREAT | O_EXCL, RUNTIME_DIR_MODE);
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free(xdg_session_file);
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if (session_file >= 0)
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break;
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}
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if (session_file < 0) {
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PAM_VERBOSE_ERROR("Too many sessions");
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rv = PAM_SESSION_ERR;
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goto out;
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}
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out:
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if (session_file >= 0)
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close(session_file);
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if (rt_dir_prefix >= 0)
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close(rt_dir_prefix);
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if (runtime_dir)
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free(runtime_dir);
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return (rv);
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}
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static int
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remove_dir(int fd)
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{
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DIR *dirp;
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struct dirent *dp;
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dirp = fdopendir(fd);
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if (dirp == NULL)
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return (-1);
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while ((dp = readdir(dirp)) != NULL) {
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if (dp->d_type == DT_DIR) {
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int dirfd;
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if (strcmp(dp->d_name, ".") == 0 ||
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strcmp(dp->d_name, "..") == 0)
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continue;
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dirfd = openat(fd, dp->d_name, 0);
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remove_dir(dirfd);
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close(dirfd);
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unlinkat(fd, dp->d_name, AT_REMOVEDIR);
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continue;
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}
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unlinkat(fd, dp->d_name, 0);
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}
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return (0);
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}
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static int
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_pam_xdg_close(pam_handle_t *pamh __unused, int flags __unused,
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int argc __unused, const char *argv[] __unused)
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{
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struct passwd *passwd;
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const char *user;
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const char *runtime_dir_prefix;
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struct stat sb;
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char *xdg_session_file;
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int rv, rt_dir_prefix, rt_dir, session_file, i;
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rt_dir = -1;
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rt_dir_prefix = -1;
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runtime_dir_prefix = openpam_get_option(pamh, "runtime_dir_prefix");
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/* Get user info */
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rv = pam_get_item(pamh, PAM_USER, (const void **)&user);
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if (rv != PAM_SUCCESS) {
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PAM_VERBOSE_ERROR("Can't get user information");
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goto out;
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}
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if ((passwd = getpwnam(user)) == NULL) {
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PAM_VERBOSE_ERROR("Can't get user information");
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Open the xdg base directory */
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rt_dir_prefix = open(RUNTIME_DIR_PREFIX, O_DIRECTORY | O_NOFOLLOW);
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if (rt_dir_prefix < 0) {
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PAM_VERBOSE_ERROR("open: %s failed (%d)\n", runtime_dir_prefix, rt_dir_prefix);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Check that the already created dir is correctly owned */
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rv = fstatat(rt_dir_prefix, user, &sb, 0);
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if (rv == -1) {
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PAM_VERBOSE_ERROR("fstatat %s/%s failed (%d)", RUNTIME_DIR_PREFIX, user, errno);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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if (sb.st_uid != passwd->pw_uid ||
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sb.st_gid != passwd->pw_gid) {
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PAM_VERBOSE_ERROR("%s/%s isn't owned by %d:%d\n", RUNTIME_DIR_PREFIX, user, passwd->pw_uid, passwd->pw_gid);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Test directory mode */
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if ((sb.st_mode & 0x1FF) != RUNTIME_DIR_MODE) {
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PAM_VERBOSE_ERROR("%s/%s have wrong mode\n", RUNTIME_DIR_PREFIX, user);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Open the user xdg directory */
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rt_dir = openat(rt_dir_prefix, user, O_DIRECTORY | O_NOFOLLOW);
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if (rt_dir < 0) {
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PAM_VERBOSE_ERROR("openat: %s/%s failed (%d)\n", RUNTIME_DIR_PREFIX, user, rt_dir_prefix);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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/* Get the last session file created */
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for (i = XDG_MAX_SESSION; i >= 0; i--) {
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asprintf(&xdg_session_file, "%s/xdg_session.%d", user, i);
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session_file = openat(rt_dir_prefix, xdg_session_file, 0);
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if (session_file >= 0) {
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unlinkat(rt_dir_prefix, xdg_session_file, 0);
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free(xdg_session_file);
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break;
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}
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free(xdg_session_file);
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}
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if (session_file < 0) {
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PAM_VERBOSE_ERROR("Can't find session number\n");
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rv = PAM_SESSION_ERR;
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goto out;
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}
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close(session_file);
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/* Final cleanup if last user session */
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if (i == 0) {
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remove_dir(rt_dir);
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if (unlinkat(rt_dir_prefix, user, AT_REMOVEDIR) != 0) {
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PAM_VERBOSE_ERROR("Can't cleanup %s/%s\n", runtime_dir_prefix, user);
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rv = PAM_SESSION_ERR;
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goto out;
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}
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}
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rv = PAM_SUCCESS;
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out:
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if (rt_dir >= 0)
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close(rt_dir);
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if (rt_dir_prefix >= 0)
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close(rt_dir_prefix);
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return (rv);
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}
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PAM_EXTERN int
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pam_sm_open_session(pam_handle_t *pamh, int flags,
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int argc, const char *argv[])
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{
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return (_pam_xdg_open(pamh, flags, argc, argv));
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}
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PAM_EXTERN int
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pam_sm_close_session(pam_handle_t *pamh, int flags,
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int argc, const char *argv[])
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{
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return (_pam_xdg_close(pamh, flags, argc, argv));
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}
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PAM_MODULE_ENTRY("pam_xdg");
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