467 lines
15 KiB
C
467 lines
15 KiB
C
/*-*- Mode: C; c-basic-offset: 8 -*-*/
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/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/file.h>
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#include <pwd.h>
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#include <security/pam_modules.h>
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#include <security/_pam_macros.h>
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#include <security/pam_modutil.h>
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#include <security/pam_ext.h>
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#include <security/pam_misc.h>
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#include <libcgroup.h>
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#include "util.h"
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#include "cgroup-util.h"
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#include "macro.h"
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#include "sd-daemon.h"
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static int parse_argv(pam_handle_t *handle,
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int argc, const char **argv,
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bool *create_session,
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bool *kill_session,
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bool *kill_user) {
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unsigned i;
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assert(argc >= 0);
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assert(argc == 0 || argv);
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for (i = 0; i < (unsigned) argc; i++) {
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int k;
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if (startswith(argv[i], "create-session=")) {
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if ((k = parse_boolean(argv[i] + 15)) < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to parse create-session= argument.");
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return k;
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}
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if (create_session)
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*create_session = k;
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} else if (startswith(argv[i], "kill-session=")) {
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if ((k = parse_boolean(argv[i] + 13)) < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
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return k;
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}
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if (kill_session)
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*kill_session = k;
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} else if (startswith(argv[i], "kill-user=")) {
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if ((k = parse_boolean(argv[i] + 10)) < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to parse kill-user= argument.");
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return k;
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}
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if (kill_user)
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*kill_user = k;
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} else {
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pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
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return -EINVAL;
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}
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}
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if (kill_session && *kill_session && kill_user)
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*kill_user = true;
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return 0;
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}
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static int open_file_and_lock(const char *fn) {
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int fd;
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assert(fn);
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if ((fd = open(fn, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_CREAT, 0600)) < 0)
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return -errno;
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if (flock(fd, LOCK_EX) < 0)
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return -errno;
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return fd;
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}
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static uint32_t combine32(unsigned long long u) {
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uint32_t r = 0;
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unsigned i;
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for (i = 0; i < sizeof(u)/4; i ++)
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r ^= (uint32_t) ((u >> (i*32)) & 0xFFFFFFFFULL);
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return r;
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}
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static char *generate_session_cookie(void) {
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char *machine;
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char *cookie;
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unsigned long long r;
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usec_t u;
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int k;
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if (getmachineid_malloc(&machine) < 0)
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if (!(machine = gethostname_malloc()))
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return NULL;
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r = random_ull();
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u = now(CLOCK_REALTIME);
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k = asprintf(&cookie, "%s-%lu-%lu",
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machine,
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(unsigned long) combine32(r),
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(unsigned long) combine32((unsigned long long) u));
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free(machine);
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return k < 0 ? NULL : cookie;
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}
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static int get_user_data(
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pam_handle_t *handle,
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const char **ret_username,
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struct passwd **ret_pw) {
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const char *username;
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struct passwd *pw;
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int r;
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assert(handle);
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assert(ret_username);
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assert(ret_pw);
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if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
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pam_syslog(handle, LOG_ERR, "Failed to get user name.");
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return r;
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}
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if (!username || !*username) {
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pam_syslog(handle, LOG_ERR, "User name not valid.");
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return PAM_AUTH_ERR;
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}
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if (!(pw = pam_modutil_getpwnam(handle, username))) {
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pam_syslog(handle, LOG_ERR, "Failed to get user data.");
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return PAM_USER_UNKNOWN;
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}
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*ret_pw = pw;
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*ret_username = username;
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return PAM_SUCCESS;
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}
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static int create_user_group(pam_handle_t *handle, const char *group, struct passwd *pw, bool attach) {
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int r;
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assert(handle);
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assert(group);
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if (attach)
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r = cg_create_and_attach("name=systemd", group, 0);
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else
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r = cg_create("name=systemd", group);
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r));
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return PAM_SESSION_ERR;
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}
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if ((r = cg_set_task_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0 ||
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(r = cg_set_group_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to change access modes: %s", strerror(-r));
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return PAM_SESSION_ERR;
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}
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return PAM_SUCCESS;
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}
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_public_ PAM_EXTERN int pam_sm_open_session(
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pam_handle_t *handle,
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int flags,
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int argc, const char **argv) {
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const char *username = NULL;
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struct passwd *pw;
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int r;
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char *buf = NULL;
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int lock_fd = -1;
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bool create_session = true;
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assert(handle);
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pam_syslog(handle, LOG_INFO, "pam-systemd initializing");
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if (parse_argv(handle, argc, argv, &create_session, NULL, NULL) < 0)
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return PAM_SESSION_ERR;
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/* Make this a NOP on non-systemd systems */
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if (sd_booted() <= 0)
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return PAM_SUCCESS;
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if ((r = cgroup_init()) != 0) {
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pam_syslog(handle, LOG_ERR, "libcgroup initialization failed: %s", cgroup_strerror(r));
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r = PAM_SESSION_ERR;
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goto finish;
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}
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if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
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goto finish;
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if (safe_mkdir(RUNTIME_DIR "/user", 0755, 0, 0) < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to create runtime directory: %m");
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r = PAM_SYSTEM_ERR;
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goto finish;
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}
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if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
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r = PAM_SYSTEM_ERR;
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goto finish;
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}
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/* Create /var/run/$USER */
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free(buf);
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if (asprintf(&buf, RUNTIME_DIR "/user/%s", username) < 0) {
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r = PAM_BUF_ERR;
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goto finish;
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}
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if (safe_mkdir(buf, 0700, pw->pw_uid, pw->pw_gid) < 0) {
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pam_syslog(handle, LOG_WARNING, "Failed to create runtime directory: %m");
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r = PAM_SYSTEM_ERR;
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goto finish;
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} else if ((r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", buf, 0)) != PAM_SUCCESS) {
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pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
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goto finish;
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}
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free(buf);
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buf = NULL;
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if (create_session) {
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const char *cookie;
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/* Reuse or create XDG session ID */
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if (!(cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) {
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if (!(buf = generate_session_cookie())) {
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r = PAM_BUF_ERR;
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goto finish;
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}
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if ((r = pam_misc_setenv(handle, "XDG_SESSION_COOKIE", buf, 0)) != PAM_SUCCESS) {
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pam_syslog(handle, LOG_ERR, "Failed to set cookie.");
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goto finish;
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}
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if (!(cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) {
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pam_syslog(handle, LOG_ERR, "Failed to get cookie.");
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r = PAM_SESSION_ERR;
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goto finish;
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}
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}
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r = asprintf(&buf, "/user/%s/%s", username, cookie);
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} else
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r = asprintf(&buf, "/user/%s/no-session", username);
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if (r < 0) {
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r = PAM_BUF_ERR;
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goto finish;
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}
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if ((r = create_user_group(handle, buf, pw, true)) != PAM_SUCCESS)
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goto finish;
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r = PAM_SUCCESS;
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finish:
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free(buf);
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if (lock_fd >= 0)
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close_nointr_nofail(lock_fd);
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return r;
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}
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static int session_remains(pam_handle_t *handle, const char *user_path) {
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struct cgroup_file_info info;
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int level = 0, r;
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void *iterator = NULL;
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bool remains = false;
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zero(info);
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r = cgroup_walk_tree_begin("name=systemd", user_path, 0, &iterator, &info, &level);
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while (r == 0) {
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if (info.type != CGROUP_FILE_TYPE_DIR)
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goto next;
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if (streq(info.path, ""))
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goto next;
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if (streq(info.path, "no-session"))
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goto next;
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remains = true;
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break;
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next:
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r = cgroup_walk_tree_next(0, &iterator, &info, level);
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}
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if (remains)
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r = 1;
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else if (r == 0 || r == ECGEOF)
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r = 0;
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else
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r = cg_translate_error(r, errno);
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assert_se(cgroup_walk_tree_end(&iterator) == 0);
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return r;
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}
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_public_ PAM_EXTERN int pam_sm_close_session(
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pam_handle_t *handle,
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int flags,
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int argc, const char **argv) {
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const char *username = NULL;
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bool kill_session = false;
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bool kill_user = false;
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int lock_fd = -1, r;
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char *session_path = NULL, *nosession_path = NULL, *user_path = NULL;
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const char *cookie;
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struct passwd *pw;
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assert(handle);
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if (parse_argv(handle, argc, argv, NULL, &kill_session, &kill_user) < 0)
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return PAM_SESSION_ERR;
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/* Make this a NOP on non-systemd systems */
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if (sd_booted() <= 0)
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return PAM_SUCCESS;
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if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
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goto finish;
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if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
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r = PAM_SYSTEM_ERR;
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goto finish;
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}
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if (asprintf(&user_path, "/user/%s", username) < 0) {
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r = PAM_BUF_ERR;
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goto finish;
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}
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if ((cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) {
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if (asprintf(&session_path, "/user/%s/%s", username, cookie) < 0 ||
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asprintf(&nosession_path, "/user/%s/no-session", username) < 0) {
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r = PAM_BUF_ERR;
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goto finish;
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}
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if (kill_session) {
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pam_syslog(handle, LOG_INFO, "KILLING ENTER");
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/* Kill processes in session cgroup */
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if ((r = cg_kill_recursive_and_wait("name=systemd", session_path)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r));
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pam_syslog(handle, LOG_INFO, "KILLING EXIT");
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} else {
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/* Migrate processes from session to
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* no-session cgroup. First, try to create the
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* no-session group in case it doesn't exist
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* yet. */
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create_user_group(handle, nosession_path, pw, 0);
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if ((r = cg_migrate_recursive("name=systemd", session_path, nosession_path, false)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r));
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}
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/* Delete session cgroup */
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if (r < 0)
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pam_syslog(handle, LOG_INFO, "Couldn't empty session cgroup, not deleting.");
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else {
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if ((r = cg_delete("name=systemd", session_path)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to delete session cgroup: %s", strerror(-r));
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}
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}
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/* GC user tree */
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cg_trim("name=systemd", user_path, false);
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if ((r = session_remains(handle, user_path)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to determine whether a session remains: %s", strerror(-r));
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/* Kill user processes not attached to any session */
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if (kill_user && r == 0) {
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/* Kill no-session cgroup */
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if ((r = cg_kill_recursive_and_wait("name=systemd", user_path)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r));
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} else {
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if ((r = cg_is_empty_recursive("name=systemd", user_path, true)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r));
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/* If we managed to kill somebody, don't cleanup the cgroup. */
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if (r == 0)
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r = -EBUSY;
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}
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if (r >= 0) {
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const char *runtime_dir;
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/* Remove user cgroup */
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if ((r = cg_delete("name=systemd", user_path)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r));
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/* This will migrate us to the /user cgroup. */
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if ((runtime_dir = pam_getenv(handle, "XDG_RUNTIME_DIR")))
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if ((r = rm_rf(runtime_dir, false, true)) < 0)
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pam_syslog(handle, LOG_ERR, "Failed to remove runtime directory: %s", strerror(-r));
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}
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r = PAM_SUCCESS;
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finish:
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if (lock_fd >= 0)
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close_nointr_nofail(lock_fd);
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free(session_path);
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free(nosession_path);
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free(user_path);
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return r;
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}
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