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>
34 #include <libcgroup.h>
37 #include "cgroup-util.h"
39 #include "sd-daemon.h"
41 static int parse_argv(pam_handle_t *handle,
42 int argc, const char **argv,
50 assert(argc == 0 || argv);
52 for (i = 0; i < (unsigned) argc; i++) {
55 if (startswith(argv[i], "create-session=")) {
56 if ((k = parse_boolean(argv[i] + 15)) < 0) {
57 pam_syslog(handle, LOG_ERR, "Failed to parse create-session= argument.");
63 } else if (startswith(argv[i], "kill-session=")) {
64 if ((k = parse_boolean(argv[i] + 13)) < 0) {
65 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
72 } else if (startswith(argv[i], "kill-user=")) {
73 if ((k = parse_boolean(argv[i] + 10)) < 0) {
74 pam_syslog(handle, LOG_ERR, "Failed to parse kill-user= argument.");
81 pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
86 if (kill_session && *kill_session && kill_user)
92 static int open_file_and_lock(const char *fn) {
97 if ((fd = open(fn, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_CREAT, 0600)) < 0)
100 /* The BSD socket semantics are a lot nicer than those of
101 * POSIX locks. Which is why we use flock() here. BSD locking
102 * does not work across NFS which however is not needed here
103 * as the filesystems in question should be local, and only
104 * locally accessible, and most likely even tmpfs. */
106 if (flock(fd, LOCK_EX) < 0)
113 SESSION_ID_AUDIT = 'a',
114 SESSION_ID_COUNTER = 'c',
115 SESSION_ID_RANDOM = 'r'
118 static uint64_t get_session_id(int *mode) {
124 /* First attempt: let's use the session ID of the audit
125 * system, if it is available. */
126 if (read_one_line_file("/proc/self/sessionid", &s) >= 0) {
130 r = safe_atou32(s, &u);
133 if (r >= 0 && u != (uint32_t) -1) {
134 *mode = SESSION_ID_AUDIT;
139 /* Second attempt, use our own counter. */
140 if ((fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-session")) >= 0) {
144 /* We do a bit of endianess swapping here, just to be
145 * sure. /var should be machine specific anyway, and
146 * /var/run even mounted from tmpfs, so this
147 * byteswapping should really not be necessary. But
148 * then again, you never know, so let's avoid any
151 if (loop_read(fd, &counter, sizeof(counter), false) != sizeof(counter))
154 counter = le64toh(counter) + 1;
156 if (lseek(fd, 0, SEEK_SET) == 0) {
157 uint64_t swapped = htole64(counter);
159 r = loop_write(fd, &swapped, sizeof(swapped), false);
161 if (r != sizeof(swapped))
166 close_nointr_nofail(fd);
169 *mode = SESSION_ID_COUNTER;
174 *mode = SESSION_ID_RANDOM;
176 /* Last attempt, pick a random value */
177 return (uint64_t) random_ull();
179 static int get_user_data(
180 pam_handle_t *handle,
181 const char **ret_username,
182 struct passwd **ret_pw) {
184 const char *username;
189 assert(ret_username);
192 if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
193 pam_syslog(handle, LOG_ERR, "Failed to get user name.");
197 if (!username || !*username) {
198 pam_syslog(handle, LOG_ERR, "User name not valid.");
202 if (!(pw = pam_modutil_getpwnam(handle, username))) {
203 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
204 return PAM_USER_UNKNOWN;
208 *ret_username = username;
213 static int create_user_group(pam_handle_t *handle, const char *group, struct passwd *pw, bool attach) {
220 r = cg_create_and_attach("name=systemd", group, 0);
222 r = cg_create("name=systemd", group);
225 pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r));
226 return PAM_SESSION_ERR;
229 if ((r = cg_set_task_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0 ||
230 (r = cg_set_group_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0) {
231 pam_syslog(handle, LOG_ERR, "Failed to change access modes: %s", strerror(-r));
232 return PAM_SESSION_ERR;
238 _public_ PAM_EXTERN int pam_sm_open_session(
239 pam_handle_t *handle,
241 int argc, const char **argv) {
243 const char *username = NULL;
248 bool create_session = true;
252 pam_syslog(handle, LOG_INFO, "pam-systemd initializing");
254 if (parse_argv(handle, argc, argv, &create_session, NULL, NULL) < 0)
255 return PAM_SESSION_ERR;
257 /* Make this a NOP on non-systemd systems */
258 if (sd_booted() <= 0)
261 if ((r = cgroup_init()) != 0) {
262 pam_syslog(handle, LOG_ERR, "libcgroup initialization failed: %s", cgroup_strerror(r));
267 if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
270 if (safe_mkdir(RUNTIME_DIR "/user", 0755, 0, 0) < 0) {
271 pam_syslog(handle, LOG_ERR, "Failed to create runtime directory: %m");
276 if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
277 pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
282 /* Create /var/run/$USER */
284 if (asprintf(&buf, RUNTIME_DIR "/user/%s", username) < 0) {
289 if (safe_mkdir(buf, 0700, pw->pw_uid, pw->pw_gid) < 0) {
290 pam_syslog(handle, LOG_WARNING, "Failed to create runtime directory: %m");
293 } else if ((r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", buf, 0)) != PAM_SUCCESS) {
294 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
301 if (create_session) {
304 /* Reuse or create XDG session ID */
305 if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) {
308 if (asprintf(&buf, "%llux", (unsigned long long) get_session_id(&mode)) < 0) {
313 /* To avoid id clashes we add the session id
314 * source to our session ids. Note that the
315 * session id source might change during
316 * runtime, because a filesystem became
317 * writable or the system reconfigured. */
319 mode != SESSION_ID_AUDIT ? (char) mode : 0;
321 if ((r = pam_misc_setenv(handle, "XDG_SESSION_ID", buf, 0)) != PAM_SUCCESS) {
322 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
326 if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) {
327 pam_syslog(handle, LOG_ERR, "Failed to get session id.");
333 r = asprintf(&buf, "/user/%s/%s", username, id);
335 r = asprintf(&buf, "/user/%s/no-session", username);
342 if ((r = create_user_group(handle, buf, pw, true)) != PAM_SUCCESS)
351 close_nointr_nofail(lock_fd);
356 static int session_remains(pam_handle_t *handle, const char *user_path) {
357 struct cgroup_file_info info;
359 void *iterator = NULL;
360 bool remains = false;
364 r = cgroup_walk_tree_begin("name=systemd", user_path, 0, &iterator, &info, &level);
367 if (info.type != CGROUP_FILE_TYPE_DIR)
370 if (streq(info.path, ""))
373 if (streq(info.path, "no-session"))
381 r = cgroup_walk_tree_next(0, &iterator, &info, level);
387 else if (r == 0 || r == ECGEOF)
390 r = cg_translate_error(r, errno);
392 assert_se(cgroup_walk_tree_end(&iterator) == 0);
397 _public_ PAM_EXTERN int pam_sm_close_session(
398 pam_handle_t *handle,
400 int argc, const char **argv) {
402 const char *username = NULL;
403 bool kill_session = false;
404 bool kill_user = false;
406 char *session_path = NULL, *nosession_path = NULL, *user_path = NULL;
412 if (parse_argv(handle, argc, argv, NULL, &kill_session, &kill_user) < 0)
413 return PAM_SESSION_ERR;
415 /* Make this a NOP on non-systemd systems */
416 if (sd_booted() <= 0)
419 if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
422 if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
423 pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
428 if (asprintf(&user_path, "/user/%s", username) < 0) {
433 if ((id = pam_getenv(handle, "XDG_SESSION_ID"))) {
435 if (asprintf(&session_path, "/user/%s/%s", username, id) < 0 ||
436 asprintf(&nosession_path, "/user/%s/no-session", username) < 0) {
442 /* Kill processes in session cgroup */
443 if ((r = cg_kill_recursive_and_wait("name=systemd", session_path)) < 0)
444 pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r));
447 /* Migrate processes from session to
448 * no-session cgroup. First, try to create the
449 * no-session group in case it doesn't exist
451 create_user_group(handle, nosession_path, pw, 0);
453 if ((r = cg_migrate_recursive("name=systemd", session_path, nosession_path, false)) < 0)
454 pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r));
457 /* Delete session cgroup */
459 pam_syslog(handle, LOG_INFO, "Couldn't empty session cgroup, not deleting.");
461 if ((r = cg_delete("name=systemd", session_path)) < 0)
462 pam_syslog(handle, LOG_ERR, "Failed to delete session cgroup: %s", strerror(-r));
467 cg_trim("name=systemd", user_path, false);
469 if ((r = session_remains(handle, user_path)) < 0)
470 pam_syslog(handle, LOG_ERR, "Failed to determine whether a session remains: %s", strerror(-r));
472 /* Kill user processes not attached to any session */
473 if (kill_user && r == 0) {
475 /* Kill no-session cgroup */
476 if ((r = cg_kill_recursive_and_wait("name=systemd", user_path)) < 0)
477 pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r));
480 if ((r = cg_is_empty_recursive("name=systemd", user_path, true)) < 0)
481 pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r));
483 /* If we managed to kill somebody, don't cleanup the cgroup. */
489 const char *runtime_dir;
491 /* Remove user cgroup */
492 if ((r = cg_delete("name=systemd", user_path)) < 0)
493 pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r));
495 /* This will migrate us to the /user cgroup. */
497 if ((runtime_dir = pam_getenv(handle, "XDG_RUNTIME_DIR")))
498 if ((r = rm_rf(runtime_dir, false, true)) < 0)
499 pam_syslog(handle, LOG_ERR, "Failed to remove runtime directory: %s", strerror(-r));
506 close_nointr_nofail(lock_fd);
509 free(nosession_path);