1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
28 #include <security/pam_modules.h>
29 #include <security/_pam_macros.h>
30 #include <security/pam_modutil.h>
31 #include <security/pam_ext.h>
32 #include <security/pam_misc.h>
35 #include "cgroup-util.h"
37 #include "sd-daemon.h"
39 static int parse_argv(pam_handle_t *handle,
40 int argc, const char **argv,
48 assert(argc == 0 || argv);
50 for (i = 0; i < (unsigned) argc; i++) {
53 if (startswith(argv[i], "create-session=")) {
54 if ((k = parse_boolean(argv[i] + 15)) < 0) {
55 pam_syslog(handle, LOG_ERR, "Failed to parse create-session= argument.");
61 } else if (startswith(argv[i], "kill-session=")) {
62 if ((k = parse_boolean(argv[i] + 13)) < 0) {
63 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
70 } else if (startswith(argv[i], "kill-user=")) {
71 if ((k = parse_boolean(argv[i] + 10)) < 0) {
72 pam_syslog(handle, LOG_ERR, "Failed to parse kill-user= argument.");
79 pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
84 if (kill_session && *kill_session && kill_user)
90 static int open_file_and_lock(const char *fn) {
95 if ((fd = open(fn, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_CREAT, 0600)) < 0)
98 /* The BSD socket semantics are a lot nicer than those of
99 * POSIX locks. Which is why we use flock() here. BSD locking
100 * does not work across NFS which however is not needed here
101 * as the filesystems in question should be local, and only
102 * locally accessible, and most likely even tmpfs. */
104 if (flock(fd, LOCK_EX) < 0)
111 SESSION_ID_AUDIT = 'a',
112 SESSION_ID_COUNTER = 'c',
113 SESSION_ID_RANDOM = 'r'
116 static uint64_t get_session_id(int *mode) {
122 /* First attempt: let's use the session ID of the audit
123 * system, if it is available. */
124 if (read_one_line_file("/proc/self/sessionid", &s) >= 0) {
128 r = safe_atou32(s, &u);
131 if (r >= 0 && u != (uint32_t) -1) {
132 *mode = SESSION_ID_AUDIT;
137 /* Second attempt, use our own counter. */
138 if ((fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-session")) >= 0) {
142 /* We do a bit of endianess swapping here, just to be
143 * sure. /var should be machine specific anyway, and
144 * /var/run even mounted from tmpfs, so this
145 * byteswapping should really not be necessary. But
146 * then again, you never know, so let's avoid any
149 if (loop_read(fd, &counter, sizeof(counter), false) != sizeof(counter))
152 counter = le64toh(counter) + 1;
154 if (lseek(fd, 0, SEEK_SET) == 0) {
155 uint64_t swapped = htole64(counter);
157 r = loop_write(fd, &swapped, sizeof(swapped), false);
159 if (r != sizeof(swapped))
164 close_nointr_nofail(fd);
167 *mode = SESSION_ID_COUNTER;
172 *mode = SESSION_ID_RANDOM;
174 /* Last attempt, pick a random value */
175 return (uint64_t) random_ull();
177 static int get_user_data(
178 pam_handle_t *handle,
179 const char **ret_username,
180 struct passwd **ret_pw) {
182 const char *username;
187 assert(ret_username);
190 if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
191 pam_syslog(handle, LOG_ERR, "Failed to get user name.");
195 if (!username || !*username) {
196 pam_syslog(handle, LOG_ERR, "User name not valid.");
200 if (!(pw = pam_modutil_getpwnam(handle, username))) {
201 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
202 return PAM_USER_UNKNOWN;
206 *ret_username = username;
211 static int create_user_group(pam_handle_t *handle, const char *group, struct passwd *pw, bool attach) {
218 r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, group, 0);
220 r = cg_create(SYSTEMD_CGROUP_CONTROLLER, group);
223 pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r));
224 return PAM_SESSION_ERR;
227 if ((r = cg_set_task_access(SYSTEMD_CGROUP_CONTROLLER, group, 0755, pw->pw_uid, pw->pw_gid)) < 0 ||
228 (r = cg_set_group_access(SYSTEMD_CGROUP_CONTROLLER, group, 0755, pw->pw_uid, pw->pw_gid)) < 0) {
229 pam_syslog(handle, LOG_ERR, "Failed to change access modes: %s", strerror(-r));
230 return PAM_SESSION_ERR;
236 _public_ PAM_EXTERN int pam_sm_open_session(
237 pam_handle_t *handle,
239 int argc, const char **argv) {
241 const char *username = NULL;
246 bool create_session = true;
250 pam_syslog(handle, LOG_INFO, "pam-systemd initializing");
252 if (parse_argv(handle, argc, argv, &create_session, NULL, NULL) < 0)
253 return PAM_SESSION_ERR;
255 /* Make this a NOP on non-systemd systems */
256 if (sd_booted() <= 0)
259 if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
262 if (safe_mkdir(RUNTIME_DIR "/user", 0755, 0, 0) < 0) {
263 pam_syslog(handle, LOG_ERR, "Failed to create runtime directory: %m");
268 if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
269 pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
274 /* Create /var/run/$USER */
276 if (asprintf(&buf, RUNTIME_DIR "/user/%s", username) < 0) {
281 if (safe_mkdir(buf, 0700, pw->pw_uid, pw->pw_gid) < 0) {
282 pam_syslog(handle, LOG_WARNING, "Failed to create runtime directory: %m");
285 } else if ((r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", buf, 0)) != PAM_SUCCESS) {
286 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
293 if (create_session) {
296 /* Reuse or create XDG session ID */
297 if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) {
300 if (asprintf(&buf, "%llux", (unsigned long long) get_session_id(&mode)) < 0) {
305 /* To avoid id clashes we add the session id
306 * source to our session ids. Note that the
307 * session id source might change during
308 * runtime, because a filesystem became
309 * writable or the system reconfigured. */
311 mode != SESSION_ID_AUDIT ? (char) mode : 0;
313 if ((r = pam_misc_setenv(handle, "XDG_SESSION_ID", buf, 0)) != PAM_SUCCESS) {
314 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
318 if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) {
319 pam_syslog(handle, LOG_ERR, "Failed to get session id.");
325 r = asprintf(&buf, "/user/%s/%s", username, id);
327 r = asprintf(&buf, "/user/%s/no-session", username);
334 if ((r = create_user_group(handle, buf, pw, true)) != PAM_SUCCESS)
343 close_nointr_nofail(lock_fd);
348 static int session_remains(pam_handle_t *handle, const char *user_path) {
350 bool remains = false;
354 if ((r = cg_enumerate_subgroups(SYSTEMD_CGROUP_CONTROLLER, user_path, &d)) < 0)
357 while ((r = cg_read_subgroup(d, &subgroup)) > 0) {
359 remains = !streq(subgroup, "no-session");
374 _public_ PAM_EXTERN int pam_sm_close_session(
375 pam_handle_t *handle,
377 int argc, const char **argv) {
379 const char *username = NULL;
380 bool kill_session = false;
381 bool kill_user = false;
383 char *session_path = NULL, *nosession_path = NULL, *user_path = NULL;
389 if (parse_argv(handle, argc, argv, NULL, &kill_session, &kill_user) < 0)
390 return PAM_SESSION_ERR;
392 /* Make this a NOP on non-systemd systems */
393 if (sd_booted() <= 0)
396 if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
399 if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
400 pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
405 /* We are probably still in some session/no-session dir. Move ourselves out of the way as first step */
406 if ((r = cg_attach(SYSTEMD_CGROUP_CONTROLLER, "/user", 0)) < 0)
407 pam_syslog(handle, LOG_ERR, "Failed to move us away: %s", strerror(-r));
409 if (asprintf(&user_path, "/user/%s", username) < 0) {
414 if ((id = pam_getenv(handle, "XDG_SESSION_ID"))) {
416 if (asprintf(&session_path, "/user/%s/%s", username, id) < 0 ||
417 asprintf(&nosession_path, "/user/%s/no-session", username) < 0) {
423 /* Kill processes in session cgroup, and delete it */
424 if ((r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, session_path, true)) < 0)
425 pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r));
427 /* Migrate processes from session to
428 * no-session cgroup. First, try to create the
429 * no-session group in case it doesn't exist
430 * yet. Also, delete the session group. */
431 create_user_group(handle, nosession_path, pw, 0);
433 if ((r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, session_path, nosession_path, false, true)) < 0)
434 pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r));
439 cg_trim(SYSTEMD_CGROUP_CONTROLLER, user_path, false);
441 if ((r = session_remains(handle, user_path)) < 0)
442 pam_syslog(handle, LOG_ERR, "Failed to determine whether a session remains: %s", strerror(-r));
444 /* Kill user processes not attached to any session */
445 if (kill_user && r == 0) {
447 /* Kill no-session cgroup */
448 if ((r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0)
449 pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r));
452 if ((r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0)
453 pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r));
455 /* Remove user cgroup */
457 if ((r = cg_delete(SYSTEMD_CGROUP_CONTROLLER, user_path)) < 0)
458 pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r));
460 /* If we managed to find somebody, don't cleanup the cgroup. */
466 const char *runtime_dir;
468 /* This will migrate us to the /user cgroup. */
470 if ((runtime_dir = pam_getenv(handle, "XDG_RUNTIME_DIR")))
471 if ((r = rm_rf(runtime_dir, false, true)) < 0)
472 pam_syslog(handle, LOG_ERR, "Failed to remove runtime directory: %s", strerror(-r));
479 close_nointr_nofail(lock_fd);
482 free(nosession_path);