diff options
Diffstat (limited to 'src/pam-module.c')
| -rw-r--r-- | src/pam-module.c | 466 |
1 files changed, 466 insertions, 0 deletions
diff --git a/src/pam-module.c b/src/pam-module.c new file mode 100644 index 0000000000..5157897a71 --- /dev/null +++ b/src/pam-module.c @@ -0,0 +1,466 @@ +/*-*- 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 <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; + + if (flock(fd, LOCK_EX) < 0) + return -errno; + + return fd; +} + +static uint32_t combine32(unsigned long long u) { + uint32_t r = 0; + unsigned i; + + for (i = 0; i < sizeof(u)/4; i ++) + r ^= (uint32_t) ((u >> (i*32)) & 0xFFFFFFFFULL); + + return r; +} + +static char *generate_session_cookie(void) { + char *machine; + char *cookie; + unsigned long long r; + usec_t u; + int k; + + if (getmachineid_malloc(&machine) < 0) + if (!(machine = gethostname_malloc())) + return NULL; + + r = random_ull(); + u = now(CLOCK_REALTIME); + + k = asprintf(&cookie, "%s-%lu-%lu", + machine, + (unsigned long) combine32(r), + (unsigned long) combine32((unsigned long long) u)); + free(machine); + + return k < 0 ? NULL : cookie; +} + +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 *cookie; + + /* Reuse or create XDG session ID */ + if (!(cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) { + if (!(buf = generate_session_cookie())) { + r = PAM_BUF_ERR; + goto finish; + } + + if ((r = pam_misc_setenv(handle, "XDG_SESSION_COOKIE", buf, 0)) != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to set cookie."); + goto finish; + } + + if (!(cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) { + pam_syslog(handle, LOG_ERR, "Failed to get cookie."); + r = PAM_SESSION_ERR; + goto finish; + } + } + + r = asprintf(&buf, "/user/%s/%s", username, cookie); + } 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 *cookie; + 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 ((cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) { + + if (asprintf(&session_path, "/user/%s/%s", username, cookie) < 0 || + asprintf(&nosession_path, "/user/%s/no-session", username) < 0) { + r = PAM_BUF_ERR; + goto finish; + } + + if (kill_session) { + pam_syslog(handle, LOG_INFO, "KILLING ENTER"); + + /* 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)); + + pam_syslog(handle, LOG_INFO, "KILLING EXIT"); + + } 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; +} |