| /*-*- Mode: C; c-basic-offset: 8 -*-*/ |
| |
| /*** |
| This file is part of systemd. |
| |
| Copyright 2010 Lennart Poettering |
| |
| systemd is free software; you can redistribute it and/or modify it |
| under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or |
| (at your option) any later version. |
| |
| systemd is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with systemd; If not, see <http://www.gnu.org/licenses/>. |
| ***/ |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <sys/file.h> |
| #include <pwd.h> |
| #include <endian.h> |
| |
| #include <security/pam_modules.h> |
| #include <security/_pam_macros.h> |
| #include <security/pam_modutil.h> |
| #include <security/pam_ext.h> |
| #include <security/pam_misc.h> |
| |
| #include <libcgroup.h> |
| |
| #include "util.h" |
| #include "cgroup-util.h" |
| #include "macro.h" |
| #include "sd-daemon.h" |
| |
| static int parse_argv(pam_handle_t *handle, |
| int argc, const char **argv, |
| bool *create_session, |
| bool *kill_session, |
| bool *kill_user) { |
| |
| unsigned i; |
| |
| assert(argc >= 0); |
| assert(argc == 0 || argv); |
| |
| for (i = 0; i < (unsigned) argc; i++) { |
| int k; |
| |
| if (startswith(argv[i], "create-session=")) { |
| if ((k = parse_boolean(argv[i] + 15)) < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to parse create-session= argument."); |
| return k; |
| } |
| |
| if (create_session) |
| *create_session = k; |
| } else if (startswith(argv[i], "kill-session=")) { |
| if ((k = parse_boolean(argv[i] + 13)) < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument."); |
| return k; |
| } |
| |
| if (kill_session) |
| *kill_session = k; |
| |
| } else if (startswith(argv[i], "kill-user=")) { |
| if ((k = parse_boolean(argv[i] + 10)) < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to parse kill-user= argument."); |
| return k; |
| } |
| |
| if (kill_user) |
| *kill_user = k; |
| } else { |
| pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]); |
| return -EINVAL; |
| } |
| } |
| |
| if (kill_session && *kill_session && kill_user) |
| *kill_user = true; |
| |
| return 0; |
| } |
| |
| static int open_file_and_lock(const char *fn) { |
| int fd; |
| |
| assert(fn); |
| |
| if ((fd = open(fn, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_CREAT, 0600)) < 0) |
| return -errno; |
| |
| /* The BSD socket semantics are a lot nicer than those of |
| * POSIX locks. Which is why we use flock() here. BSD locking |
| * does not work across NFS which however is not needed here |
| * as the filesystems in question should be local, and only |
| * locally accessible, and most likely even tmpfs. */ |
| |
| if (flock(fd, LOCK_EX) < 0) |
| return -errno; |
| |
| return fd; |
| } |
| |
| enum { |
| SESSION_ID_AUDIT = 'a', |
| SESSION_ID_COUNTER = 'c', |
| SESSION_ID_RANDOM = 'r' |
| }; |
| |
| static uint64_t get_session_id(int *mode) { |
| char *s; |
| int fd; |
| |
| assert(mode); |
| |
| /* First attempt: let's use the session ID of the audit |
| * system, if it is available. */ |
| if (read_one_line_file("/proc/self/sessionid", &s) >= 0) { |
| uint32_t u; |
| int r; |
| |
| r = safe_atou32(s, &u); |
| free(s); |
| |
| if (r >= 0 && u != (uint32_t) -1) { |
| *mode = SESSION_ID_AUDIT; |
| return (uint64_t) u; |
| } |
| } |
| |
| /* Second attempt, use our own counter. */ |
| if ((fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-session")) >= 0) { |
| uint64_t counter; |
| ssize_t r; |
| |
| /* We do a bit of endianess swapping here, just to be |
| * sure. /var should be machine specific anyway, and |
| * /var/run even mounted from tmpfs, so this |
| * byteswapping should really not be necessary. But |
| * then again, you never know, so let's avoid any |
| * risk. */ |
| |
| if (loop_read(fd, &counter, sizeof(counter), false) != sizeof(counter)) |
| counter = 1; |
| else |
| counter = le64toh(counter) + 1; |
| |
| if (lseek(fd, 0, SEEK_SET) == 0) { |
| uint64_t swapped = htole64(counter); |
| |
| r = loop_write(fd, &swapped, sizeof(swapped), false); |
| |
| if (r != sizeof(swapped)) |
| r = -EIO; |
| } else |
| r = -errno; |
| |
| close_nointr_nofail(fd); |
| |
| if (r >= 0) { |
| *mode = SESSION_ID_COUNTER; |
| return counter; |
| } |
| } |
| |
| *mode = SESSION_ID_RANDOM; |
| |
| /* Last attempt, pick a random value */ |
| return (uint64_t) random_ull(); |
| } |
| static int get_user_data( |
| pam_handle_t *handle, |
| const char **ret_username, |
| struct passwd **ret_pw) { |
| |
| const char *username; |
| struct passwd *pw; |
| int r; |
| |
| assert(handle); |
| assert(ret_username); |
| assert(ret_pw); |
| |
| if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) { |
| pam_syslog(handle, LOG_ERR, "Failed to get user name."); |
| return r; |
| } |
| |
| if (!username || !*username) { |
| pam_syslog(handle, LOG_ERR, "User name not valid."); |
| return PAM_AUTH_ERR; |
| } |
| |
| if (!(pw = pam_modutil_getpwnam(handle, username))) { |
| pam_syslog(handle, LOG_ERR, "Failed to get user data."); |
| return PAM_USER_UNKNOWN; |
| } |
| |
| *ret_pw = pw; |
| *ret_username = username; |
| |
| return PAM_SUCCESS; |
| } |
| |
| static int create_user_group(pam_handle_t *handle, const char *group, struct passwd *pw, bool attach) { |
| int r; |
| |
| assert(handle); |
| assert(group); |
| |
| if (attach) |
| r = cg_create_and_attach("name=systemd", group, 0); |
| else |
| r = cg_create("name=systemd", group); |
| |
| if (r < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r)); |
| return PAM_SESSION_ERR; |
| } |
| |
| if ((r = cg_set_task_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0 || |
| (r = cg_set_group_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to change access modes: %s", strerror(-r)); |
| return PAM_SESSION_ERR; |
| } |
| |
| return PAM_SUCCESS; |
| } |
| |
| _public_ PAM_EXTERN int pam_sm_open_session( |
| pam_handle_t *handle, |
| int flags, |
| int argc, const char **argv) { |
| |
| const char *username = NULL; |
| struct passwd *pw; |
| int r; |
| char *buf = NULL; |
| int lock_fd = -1; |
| bool create_session = true; |
| |
| assert(handle); |
| |
| pam_syslog(handle, LOG_INFO, "pam-systemd initializing"); |
| |
| if (parse_argv(handle, argc, argv, &create_session, NULL, NULL) < 0) |
| return PAM_SESSION_ERR; |
| |
| /* Make this a NOP on non-systemd systems */ |
| if (sd_booted() <= 0) |
| return PAM_SUCCESS; |
| |
| if ((r = cgroup_init()) != 0) { |
| pam_syslog(handle, LOG_ERR, "libcgroup initialization failed: %s", cgroup_strerror(r)); |
| r = PAM_SESSION_ERR; |
| goto finish; |
| } |
| |
| if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS) |
| goto finish; |
| |
| if (safe_mkdir(RUNTIME_DIR "/user", 0755, 0, 0) < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to create runtime directory: %m"); |
| r = PAM_SYSTEM_ERR; |
| goto finish; |
| } |
| |
| if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m"); |
| r = PAM_SYSTEM_ERR; |
| goto finish; |
| } |
| |
| /* Create /var/run/$USER */ |
| free(buf); |
| if (asprintf(&buf, RUNTIME_DIR "/user/%s", username) < 0) { |
| r = PAM_BUF_ERR; |
| goto finish; |
| } |
| |
| if (safe_mkdir(buf, 0700, pw->pw_uid, pw->pw_gid) < 0) { |
| pam_syslog(handle, LOG_WARNING, "Failed to create runtime directory: %m"); |
| r = PAM_SYSTEM_ERR; |
| goto finish; |
| } else if ((r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", buf, 0)) != PAM_SUCCESS) { |
| pam_syslog(handle, LOG_ERR, "Failed to set runtime dir."); |
| goto finish; |
| } |
| |
| free(buf); |
| buf = NULL; |
| |
| if (create_session) { |
| const char *id; |
| |
| /* Reuse or create XDG session ID */ |
| if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) { |
| int mode; |
| |
| if (asprintf(&buf, "%llux", (unsigned long long) get_session_id(&mode)) < 0) { |
| r = PAM_BUF_ERR; |
| goto finish; |
| } |
| |
| /* To avoid id clashes we add the session id |
| * source to our session ids. Note that the |
| * session id source might change during |
| * runtime, because a filesystem became |
| * writable or the system reconfigured. */ |
| buf[strlen(buf)-1] = |
| mode != SESSION_ID_AUDIT ? (char) mode : 0; |
| |
| if ((r = pam_misc_setenv(handle, "XDG_SESSION_ID", buf, 0)) != PAM_SUCCESS) { |
| pam_syslog(handle, LOG_ERR, "Failed to set session id."); |
| goto finish; |
| } |
| |
| if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) { |
| pam_syslog(handle, LOG_ERR, "Failed to get session id."); |
| r = PAM_SESSION_ERR; |
| goto finish; |
| } |
| } |
| |
| r = asprintf(&buf, "/user/%s/%s", username, id); |
| } else |
| r = asprintf(&buf, "/user/%s/no-session", username); |
| |
| if (r < 0) { |
| r = PAM_BUF_ERR; |
| goto finish; |
| } |
| |
| if ((r = create_user_group(handle, buf, pw, true)) != PAM_SUCCESS) |
| goto finish; |
| |
| r = PAM_SUCCESS; |
| |
| finish: |
| free(buf); |
| |
| if (lock_fd >= 0) |
| close_nointr_nofail(lock_fd); |
| |
| return r; |
| } |
| |
| static int session_remains(pam_handle_t *handle, const char *user_path) { |
| struct cgroup_file_info info; |
| int level = 0, r; |
| void *iterator = NULL; |
| bool remains = false; |
| |
| zero(info); |
| |
| r = cgroup_walk_tree_begin("name=systemd", user_path, 0, &iterator, &info, &level); |
| while (r == 0) { |
| |
| if (info.type != CGROUP_FILE_TYPE_DIR) |
| goto next; |
| |
| if (streq(info.path, "")) |
| goto next; |
| |
| if (streq(info.path, "no-session")) |
| goto next; |
| |
| remains = true; |
| break; |
| |
| next: |
| |
| r = cgroup_walk_tree_next(0, &iterator, &info, level); |
| } |
| |
| |
| if (remains) |
| r = 1; |
| else if (r == 0 || r == ECGEOF) |
| r = 0; |
| else |
| r = cg_translate_error(r, errno); |
| |
| assert_se(cgroup_walk_tree_end(&iterator) == 0); |
| |
| return r; |
| } |
| |
| _public_ PAM_EXTERN int pam_sm_close_session( |
| pam_handle_t *handle, |
| int flags, |
| int argc, const char **argv) { |
| |
| const char *username = NULL; |
| bool kill_session = false; |
| bool kill_user = false; |
| int lock_fd = -1, r; |
| char *session_path = NULL, *nosession_path = NULL, *user_path = NULL; |
| const char *id; |
| struct passwd *pw; |
| |
| assert(handle); |
| |
| if (parse_argv(handle, argc, argv, NULL, &kill_session, &kill_user) < 0) |
| return PAM_SESSION_ERR; |
| |
| /* Make this a NOP on non-systemd systems */ |
| if (sd_booted() <= 0) |
| return PAM_SUCCESS; |
| |
| if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS) |
| goto finish; |
| |
| if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) { |
| pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m"); |
| r = PAM_SYSTEM_ERR; |
| goto finish; |
| } |
| |
| if (asprintf(&user_path, "/user/%s", username) < 0) { |
| r = PAM_BUF_ERR; |
| goto finish; |
| } |
| |
| if ((id = pam_getenv(handle, "XDG_SESSION_ID"))) { |
| |
| if (asprintf(&session_path, "/user/%s/%s", username, id) < 0 || |
| asprintf(&nosession_path, "/user/%s/no-session", username) < 0) { |
| r = PAM_BUF_ERR; |
| goto finish; |
| } |
| |
| if (kill_session) { |
| /* Kill processes in session cgroup */ |
| if ((r = cg_kill_recursive_and_wait("name=systemd", session_path)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r)); |
| |
| } else { |
| /* Migrate processes from session to |
| * no-session cgroup. First, try to create the |
| * no-session group in case it doesn't exist |
| * yet. */ |
| create_user_group(handle, nosession_path, pw, 0); |
| |
| if ((r = cg_migrate_recursive("name=systemd", session_path, nosession_path, false)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r)); |
| } |
| |
| /* Delete session cgroup */ |
| if (r < 0) |
| pam_syslog(handle, LOG_INFO, "Couldn't empty session cgroup, not deleting."); |
| else { |
| if ((r = cg_delete("name=systemd", session_path)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to delete session cgroup: %s", strerror(-r)); |
| } |
| } |
| |
| /* GC user tree */ |
| cg_trim("name=systemd", user_path, false); |
| |
| if ((r = session_remains(handle, user_path)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to determine whether a session remains: %s", strerror(-r)); |
| |
| /* Kill user processes not attached to any session */ |
| if (kill_user && r == 0) { |
| |
| /* Kill no-session cgroup */ |
| if ((r = cg_kill_recursive_and_wait("name=systemd", user_path)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r)); |
| } else { |
| |
| if ((r = cg_is_empty_recursive("name=systemd", user_path, true)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r)); |
| |
| /* If we managed to kill somebody, don't cleanup the cgroup. */ |
| if (r == 0) |
| r = -EBUSY; |
| } |
| |
| if (r >= 0) { |
| const char *runtime_dir; |
| |
| /* Remove user cgroup */ |
| if ((r = cg_delete("name=systemd", user_path)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r)); |
| |
| /* This will migrate us to the /user cgroup. */ |
| |
| if ((runtime_dir = pam_getenv(handle, "XDG_RUNTIME_DIR"))) |
| if ((r = rm_rf(runtime_dir, false, true)) < 0) |
| pam_syslog(handle, LOG_ERR, "Failed to remove runtime directory: %s", strerror(-r)); |
| } |
| |
| r = PAM_SUCCESS; |
| |
| finish: |
| if (lock_fd >= 0) |
| close_nointr_nofail(lock_fd); |
| |
| free(session_path); |
| free(nosession_path); |
| free(user_path); |
| |
| return r; |
| } |