/*-*- 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 "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, bool remember) { int r; assert(handle); assert(group); if (attach) r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, group, 0); else r = cg_create(SYSTEMD_CGROUP_CONTROLLER, group); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r)); return PAM_SESSION_ERR; } if (r > 0 && remember) { /* Remember that it was us who created this group, and * that hence we need to remove it too. This is a * protection against removing the cgroup when run * recursively. */ if ((r = pam_set_data(handle, "systemd.created", INT_TO_PTR(1), NULL)) != PAM_SUCCESS) { pam_syslog(handle, LOG_ERR, "Failed to install created variable."); return r; } } if ((r = cg_set_task_access(SYSTEMD_CGROUP_CONTROLLER, group, 0755, pw->pw_uid, pw->pw_gid)) < 0 || (r = cg_set_group_access(SYSTEMD_CGROUP_CONTROLLER, 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_DEBUG, "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 = 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; } pam_syslog(handle, LOG_INFO, "Moving new user session for %s into control group %s.", username, buf); if ((r = create_user_group(handle, buf, pw, true, 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) { int r; bool remains = false; DIR *d; char *subgroup; if ((r = cg_enumerate_subgroups(SYSTEMD_CGROUP_CONTROLLER, user_path, &d)) < 0) return r; while ((r = cg_read_subgroup(d, &subgroup)) > 0) { remains = !streq(subgroup, "no-session"); free(subgroup); if (remains) break; } closedir(d); if (r < 0) return r; return !!remains; } _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; const void *created = NULL; 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; } /* We are probably still in some session/no-session dir. Move ourselves out of the way as first step */ if ((r = cg_attach(SYSTEMD_CGROUP_CONTROLLER, "/user", 0)) < 0) pam_syslog(handle, LOG_ERR, "Failed to move us away: %s", strerror(-r)); if (asprintf(&user_path, "/user/%s", username) < 0) { r = PAM_BUF_ERR; goto finish; } pam_get_data(handle, "systemd.created", &created); if ((id = pam_getenv(handle, "XDG_SESSION_ID")) && created) { 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) { pam_syslog(handle, LOG_INFO, "Killing remaining processes of user session %s of %s.", id, username); /* Kill processes in session cgroup, and delete it */ if ((r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, session_path, true)) < 0) pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r)); } else { pam_syslog(handle, LOG_INFO, "Moving remaining processes of user session %s of %s into control group %s.", id, username, nosession_path); /* Migrate processes from session to * no-session cgroup. First, try to create the * no-session group in case it doesn't exist * yet. Also, delete the session group. */ create_user_group(handle, nosession_path, pw, false, false); if ((r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, session_path, nosession_path, false, true)) < 0) pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r)); } } /* GC user tree */ cg_trim(SYSTEMD_CGROUP_CONTROLLER, 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(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0) pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r)); } else { if ((r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0) pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r)); /* Remove user cgroup */ if (r > 0) { if ((r = cg_delete(SYSTEMD_CGROUP_CONTROLLER, user_path)) < 0) pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r)); /* If we managed to find somebody, don't cleanup the cgroup. */ } else if (r == 0) r = -EBUSY; } if (r >= 0) { const char *runtime_dir; 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)); } /* pam_syslog(handle, LOG_DEBUG, "pam-systemd done"); */ r = PAM_SUCCESS; finish: if (lock_fd >= 0) close_nointr_nofail(lock_fd); free(session_path); free(nosession_path); free(user_path); return r; }