/* SPDX-License-Identifier: LGPL-2.1+ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include "alloc-util.h" #include "audit-util.h" #include "bus-common-errors.h" #include "bus-error.h" #include "bus-internal.h" #include "bus-util.h" #include "cgroup-util.h" #include "errno-util.h" #include "fd-util.h" #include "fileio.h" #include "format-util.h" #include "hostname-util.h" #include "login-util.h" #include "macro.h" #include "parse-util.h" #include "path-util.h" #include "process-util.h" #include "socket-util.h" #include "stdio-util.h" #include "strv.h" #include "terminal-util.h" static int parse_argv( pam_handle_t *handle, int argc, const char **argv, const char **class, const char **type, const char **desktop, bool *debug) { unsigned i; assert(argc >= 0); assert(argc == 0 || argv); for (i = 0; i < (unsigned) argc; i++) { if (startswith(argv[i], "class=")) { if (class) *class = argv[i] + 6; } else if (startswith(argv[i], "type=")) { if (type) *type = argv[i] + 5; } else if (startswith(argv[i], "desktop=")) { if (desktop) *desktop = argv[i] + 8; } else if (streq(argv[i], "debug")) { if (debug) *debug = true; } else if (startswith(argv[i], "debug=")) { int k; k = parse_boolean(argv[i] + 6); if (k < 0) pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring."); else if (debug) *debug = k; } else pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]); } return 0; } static int get_user_data( pam_handle_t *handle, const char **ret_username, struct passwd **ret_pw) { const char *username = NULL; struct passwd *pw = NULL; int r; assert(handle); assert(ret_username); assert(ret_pw); r = pam_get_user(handle, &username, NULL); if (r != PAM_SUCCESS) { pam_syslog(handle, LOG_ERR, "Failed to get user name."); return r; } if (isempty(username)) { pam_syslog(handle, LOG_ERR, "User name not valid."); return PAM_AUTH_ERR; } pw = pam_modutil_getpwnam(handle, username); if (!pw) { pam_syslog(handle, LOG_ERR, "Failed to get user data."); return PAM_USER_UNKNOWN; } *ret_pw = pw; *ret_username = username; return PAM_SUCCESS; } static bool display_is_local(const char *display) { assert(display); return display[0] == ':' && display[1] >= '0' && display[1] <= '9'; } static int socket_from_display(const char *display, char **path) { size_t k; char *f, *c; assert(display); assert(path); if (!display_is_local(display)) return -EINVAL; k = strspn(display+1, "0123456789"); f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1); if (!f) return -ENOMEM; c = stpcpy(f, "/tmp/.X11-unix/X"); memcpy(c, display+1, k); c[k] = 0; *path = f; return 0; } static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) { union sockaddr_union sa = {}; _cleanup_free_ char *p = NULL, *tty = NULL; _cleanup_close_ int fd = -1; struct ucred ucred; int v, r, salen; assert(display); assert(vtnr); /* We deduce the X11 socket from the display name, then use * SO_PEERCRED to determine the X11 server process, ask for * the controlling tty of that and if it's a VC then we know * the seat and the virtual terminal. Sounds ugly, is only * semi-ugly. */ r = socket_from_display(display, &p); if (r < 0) return r; salen = sockaddr_un_set_path(&sa.un, p); if (salen < 0) return salen; fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0); if (fd < 0) return -errno; if (connect(fd, &sa.sa, salen) < 0) return -errno; r = getpeercred(fd, &ucred); if (r < 0) return r; r = get_ctty(ucred.pid, NULL, &tty); if (r < 0) return r; v = vtnr_from_tty(tty); if (v < 0) return v; else if (v == 0) return -ENOENT; if (seat) *seat = "seat0"; *vtnr = (uint32_t) v; return 0; } static int export_legacy_dbus_address( pam_handle_t *handle, uid_t uid, const char *runtime) { const char *s; _cleanup_free_ char *t = NULL; int r = PAM_BUF_ERR; /* We need to export $DBUS_SESSION_BUS_ADDRESS because various applications will not connect * correctly to the bus without it. This setting matches what dbus.socket does for the user * session using 'systemctl --user set-environment'. We want to have the same configuration * in processes started from the PAM session. * * The setting of the address is guarded by the access() check because it is also possible to compile * dbus without --enable-user-session, in which case this socket is not used, and * $DBUS_SESSION_BUS_ADDRESS should not be set. An alternative approach would to not do the access() * check here, and let applications try on their own, by using "unix:path=%s/bus;autolaunch:". But we * expect the socket to be present by the time we do this check, so we can just as well check once * here. */ s = strjoina(runtime, "/bus"); if (access(s, F_OK) < 0) return PAM_SUCCESS; if (asprintf(&t, DEFAULT_USER_BUS_ADDRESS_FMT, runtime) < 0) goto error; r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0); if (r != PAM_SUCCESS) goto error; return PAM_SUCCESS; error: pam_syslog(handle, LOG_ERR, "Failed to set bus variable."); return r; } static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) { uint64_t val; int r; if (isempty(limit)) return 0; if (streq(limit, "infinity")) { r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r)); return r; } } else { r = parse_permille(limit); if (r >= 0) { r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) r * UINT32_MAX) / 1000U)); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r)); return r; } } else { r = parse_size(limit, 1024, &val); if (r >= 0) { r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r)); return r; } } else pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.memory_max: %s, ignoring.", limit); } } return 0; } static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) { uint64_t val; int r; /* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */ if (isempty(limit) || streq(limit, "infinity")) return 0; r = safe_atou64(limit, &val); if (r >= 0) { r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r)); return r; } } else pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.tasks_max: %s, ignoring.", limit); return 0; } static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) { uint64_t val; int r; if (isempty(limit)) return 0; r = cg_weight_parse(limit, &val); if (r >= 0) { r = sd_bus_message_append(m, "(sv)", field, "t", val); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r)); return r; } } else if (streq(field, "CPUWeight")) pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit); else pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit); return 0; } static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) { const char *v; assert(handle); assert(key); /* Looks for an environment variable, preferably in the environment block associated with the * specified PAM handle, falling back to the process' block instead. Why check both? Because we want * to permit configuration of session properties from unit files that invoke PAM services, so that * PAM services don't have to be reworked to set systemd-specific properties, but these properties * can still be set from the unit file Environment= block. */ v = pam_getenv(handle, key); if (!isempty(v)) return v; /* We use secure_getenv() here, since we might get loaded into su/sudo, which are SUID. Ideally * they'd clean up the environment before invoking foreign code (such as PAM modules), but alas they * currently don't (to be precise, they clean up the environment they pass to their children, but * not their own environ[]). */ v = secure_getenv(key); if (!isempty(v)) return v; return fallback; } static int update_environment(pam_handle_t *handle, const char *key, const char *value) { int r; assert(handle); assert(key); /* Updates the environment, but only if there's actually a value set. Also, log about errors */ if (isempty(value)) return PAM_SUCCESS; r = pam_misc_setenv(handle, key, value, 0); if (r != PAM_SUCCESS) pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key); return r; } static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) { struct stat st; assert(path); /* Just some extra paranoia: let's not set $XDG_RUNTIME_DIR if the directory we'd set it to isn't actually set * up properly for us. */ if (lstat(path, &st) < 0) { pam_syslog(handle, LOG_ERR, "Failed to stat() runtime directory '%s': %s", path, strerror_safe(errno)); goto fail; } if (!S_ISDIR(st.st_mode)) { pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not actually a directory.", path); goto fail; } if (st.st_uid != uid) { pam_syslog(handle, LOG_ERR, "Runtime directory '%s' is not owned by UID " UID_FMT ", as it should.", path, uid); goto fail; } return true; fail: pam_syslog(handle, LOG_WARNING, "Not setting $XDG_RUNTIME_DIR, as the directory is not in order."); return false; } _public_ PAM_EXTERN int pam_sm_open_session( pam_handle_t *handle, int flags, int argc, const char **argv) { _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL; _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL; const char *username, *id, *object_path, *runtime_path, *service = NULL, *tty = NULL, *display = NULL, *remote_user = NULL, *remote_host = NULL, *seat = NULL, *type = NULL, *class = NULL, *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL, *memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL; _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL; int session_fd = -1, existing, r; bool debug = false, remote; struct passwd *pw; uint32_t vtnr = 0; uid_t original_uid; assert(handle); /* Make this a NOP on non-logind systems */ if (!logind_running()) return PAM_SUCCESS; if (parse_argv(handle, argc, argv, &class_pam, &type_pam, &desktop_pam, &debug) < 0) return PAM_SESSION_ERR; if (debug) pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing"); r = get_user_data(handle, &username, &pw); if (r != PAM_SUCCESS) { pam_syslog(handle, LOG_ERR, "Failed to get user data."); return r; } /* Make sure we don't enter a loop by talking to * systemd-logind when it is actually waiting for the * background to finish start-up. If the service is * "systemd-user" we simply set XDG_RUNTIME_DIR and * leave. */ pam_get_item(handle, PAM_SERVICE, (const void**) &service); if (streq_ptr(service, "systemd-user")) { char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)]; xsprintf(rt, "/run/user/"UID_FMT, pw->pw_uid); if (validate_runtime_directory(handle, rt, pw->pw_uid)) { r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0); if (r != PAM_SUCCESS) { pam_syslog(handle, LOG_ERR, "Failed to set runtime dir."); return r; } } r = export_legacy_dbus_address(handle, pw->pw_uid, rt); if (r != PAM_SUCCESS) return r; return PAM_SUCCESS; } /* Otherwise, we ask logind to create a session for us */ pam_get_item(handle, PAM_XDISPLAY, (const void**) &display); pam_get_item(handle, PAM_TTY, (const void**) &tty); pam_get_item(handle, PAM_RUSER, (const void**) &remote_user); pam_get_item(handle, PAM_RHOST, (const void**) &remote_host); seat = getenv_harder(handle, "XDG_SEAT", NULL); cvtnr = getenv_harder(handle, "XDG_VTNR", NULL); type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam); class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam); desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam); tty = strempty(tty); if (strchr(tty, ':')) { /* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things * and don't pretend that an X display was a tty. */ if (isempty(display)) display = tty; tty = NULL; } else if (streq(tty, "cron")) { /* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but * probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set * (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked * off processes.) */ type = "unspecified"; class = "background"; tty = NULL; } else if (streq(tty, "ssh")) { /* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further * details look for "PAM_TTY_KLUDGE" in the openssh sources). */ type ="tty"; class = "user"; tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually * associated with a pty — won't be tracked by their tty in logind. This is because ssh * does the PAM session registration early for new connections, and registers a pty only * much later (this is because it doesn't know yet if it needs one at all, as whether to * register a pty or not is negotiated much later in the protocol). */ } else /* Chop off leading /dev prefix that some clients specify, but others do not. */ tty = skip_dev_prefix(tty); /* If this fails vtnr will be 0, that's intended */ if (!isempty(cvtnr)) (void) safe_atou32(cvtnr, &vtnr); if (!isempty(display) && !vtnr) { if (isempty(seat)) (void) get_seat_from_display(display, &seat, &vtnr); else if (streq(seat, "seat0")) (void) get_seat_from_display(display, NULL, &vtnr); } if (seat && !streq(seat, "seat0") && vtnr != 0) { if (debug) pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat); vtnr = 0; } if (isempty(type)) type = !isempty(display) ? "x11" : !isempty(tty) ? "tty" : "unspecified"; if (isempty(class)) class = streq(type, "unspecified") ? "background" : "user"; remote = !isempty(remote_host) && !is_localhost(remote_host); (void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max); (void) pam_get_data(handle, "systemd.tasks_max", (const void **)&tasks_max); (void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight); (void) pam_get_data(handle, "systemd.io_weight", (const void **)&io_weight); /* Talk to logind over the message bus */ r = sd_bus_open_system(&bus); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror_safe(r)); return PAM_SESSION_ERR; } if (debug) { pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: " "uid="UID_FMT" pid="PID_FMT" service=%s type=%s class=%s desktop=%s seat=%s vtnr=%"PRIu32" tty=%s display=%s remote=%s remote_user=%s remote_host=%s", pw->pw_uid, getpid_cached(), strempty(service), type, class, strempty(desktop), strempty(seat), vtnr, strempty(tty), strempty(display), yes_no(remote), strempty(remote_user), strempty(remote_host)); pam_syslog(handle, LOG_DEBUG, "Session limits: " "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s", strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight)); } r = sd_bus_message_new_method_call( bus, &m, "org.freedesktop.login1", "/org/freedesktop/login1", "org.freedesktop.login1.Manager", "CreateSession"); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror_safe(r)); return PAM_SESSION_ERR; } r = sd_bus_message_append(m, "uusssssussbss", (uint32_t) pw->pw_uid, 0, service, type, class, desktop, seat, vtnr, tty, display, remote, remote_user, remote_host); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror_safe(r)); return PAM_SESSION_ERR; } r = sd_bus_message_open_container(m, 'a', "(sv)"); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror_safe(r)); return PAM_SYSTEM_ERR; } r = append_session_memory_max(handle, m, memory_max); if (r < 0) return PAM_SESSION_ERR; r = append_session_tasks_max(handle, m, tasks_max); if (r < 0) return PAM_SESSION_ERR; r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight"); if (r < 0) return PAM_SESSION_ERR; r = append_session_cg_weight(handle, m, io_weight, "IOWeight"); if (r < 0) return PAM_SESSION_ERR; r = sd_bus_message_close_container(m); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror_safe(r)); return PAM_SYSTEM_ERR; } r = sd_bus_call(bus, m, 0, &error, &reply); if (r < 0) { if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) { if (debug) pam_syslog(handle, LOG_DEBUG, "Not creating session: %s", bus_error_message(&error, r)); return PAM_SUCCESS; } else { pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r)); return PAM_SYSTEM_ERR; } } r = sd_bus_message_read(reply, "soshusub", &id, &object_path, &runtime_path, &session_fd, &original_uid, &seat, &vtnr, &existing); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror_safe(r)); return PAM_SESSION_ERR; } if (debug) pam_syslog(handle, LOG_DEBUG, "Reply from logind: " "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u", id, object_path, runtime_path, session_fd, seat, vtnr, original_uid); r = update_environment(handle, "XDG_SESSION_ID", id); if (r != PAM_SUCCESS) return r; if (original_uid == pw->pw_uid) { /* Don't set $XDG_RUNTIME_DIR if the user we now * authenticated for does not match the original user * of the session. We do this in order not to result * in privileged apps clobbering the runtime directory * unnecessarily. */ if (validate_runtime_directory(handle, runtime_path, pw->pw_uid)) { r = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path); if (r != PAM_SUCCESS) return r; } r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path); if (r != PAM_SUCCESS) return r; } /* Most likely we got the session/type/class from environment variables, but might have gotten the data * somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this * data is inherited into the session processes, and programs can rely on them to be initialized. */ r = update_environment(handle, "XDG_SESSION_TYPE", type); if (r != PAM_SUCCESS) return r; r = update_environment(handle, "XDG_SESSION_CLASS", class); if (r != PAM_SUCCESS) return r; r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop); if (r != PAM_SUCCESS) return r; r = update_environment(handle, "XDG_SEAT", seat); if (r != PAM_SUCCESS) return r; if (vtnr > 0) { char buf[DECIMAL_STR_MAX(vtnr)]; sprintf(buf, "%u", vtnr); r = update_environment(handle, "XDG_VTNR", buf); if (r != PAM_SUCCESS) return r; } r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL); if (r != PAM_SUCCESS) { pam_syslog(handle, LOG_ERR, "Failed to install existing flag."); return r; } if (session_fd >= 0) { session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3); if (session_fd < 0) { pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m"); return PAM_SESSION_ERR; } r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(session_fd), NULL); if (r != PAM_SUCCESS) { pam_syslog(handle, LOG_ERR, "Failed to install session fd."); safe_close(session_fd); return r; } } return PAM_SUCCESS; } _public_ PAM_EXTERN int pam_sm_close_session( pam_handle_t *handle, int flags, int argc, const char **argv) { _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL; _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL; const void *existing = NULL; const char *id; int r; assert(handle); /* Only release session if it wasn't pre-existing when we * tried to create it */ (void) pam_get_data(handle, "systemd.existing", &existing); id = pam_getenv(handle, "XDG_SESSION_ID"); if (id && !existing) { /* Before we go and close the FIFO we need to tell * logind that this is a clean session shutdown, so * that it doesn't just go and slaughter us * immediately after closing the fd */ r = sd_bus_open_system(&bus); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror_safe(r)); return PAM_SESSION_ERR; } r = sd_bus_call_method(bus, "org.freedesktop.login1", "/org/freedesktop/login1", "org.freedesktop.login1.Manager", "ReleaseSession", &error, NULL, "s", id); if (r < 0) { pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r)); return PAM_SESSION_ERR; } } /* Note that we are knowingly leaking the FIFO fd here. This * way, logind can watch us die. If we closed it here it would * not have any clue when that is completed. Given that one * cannot really have multiple PAM sessions open from the same * process this means we will leak one FD at max. */ return PAM_SUCCESS; }