diff options
Diffstat (limited to 'src/login/pam_systemd.c')
| -rw-r--r-- | src/login/pam_systemd.c | 1266 |
1 files changed, 1266 insertions, 0 deletions
diff --git a/src/login/pam_systemd.c b/src/login/pam_systemd.c new file mode 100644 index 0000000..bf45974 --- /dev/null +++ b/src/login/pam_systemd.c @@ -0,0 +1,1266 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <endian.h> +#include <errno.h> +#include <fcntl.h> +#include <pwd.h> +#include <security/_pam_macros.h> +#include <security/pam_ext.h> +#include <security/pam_misc.h> +#include <security/pam_modules.h> +#include <security/pam_modutil.h> +#include <sys/file.h> +#include <sys/stat.h> +#include <sys/sysmacros.h> +#include <sys/types.h> +#include <unistd.h> + +#include "alloc-util.h" +#include "audit-util.h" +#include "bus-common-errors.h" +#include "bus-error.h" +#include "bus-internal.h" +#include "bus-locator.h" +#include "cap-list.h" +#include "capability-util.h" +#include "cgroup-setup.h" +#include "devnum-util.h" +#include "errno-util.h" +#include "fd-util.h" +#include "fileio.h" +#include "format-util.h" +#include "fs-util.h" +#include "hostname-util.h" +#include "locale-util.h" +#include "login-util.h" +#include "macro.h" +#include "missing_syscall.h" +#include "pam-util.h" +#include "parse-util.h" +#include "path-util.h" +#include "percent-util.h" +#include "process-util.h" +#include "rlimit-util.h" +#include "socket-util.h" +#include "stdio-util.h" +#include "strv.h" +#include "terminal-util.h" +#include "user-util.h" +#include "userdb.h" + +#define LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC (2*USEC_PER_MINUTE) + +static int parse_caps( + pam_handle_t *handle, + const char *value, + uint64_t *caps) { + + bool subtract; + int r; + + assert(handle); + assert(value); + + if (value[0] == '~') { + subtract = true; + value++; + } else + subtract = false; + + for (;;) { + _cleanup_free_ char *s = NULL; + uint64_t b, m; + int c; + + /* We can't use spaces as separators here, as PAM's simplistic argument parser doesn't allow + * spaces inside of arguments. We use commas instead (which is similar to cap_from_text(), + * which also uses commas). */ + r = extract_first_word(&value, &s, ",", EXTRACT_DONT_COALESCE_SEPARATORS); + if (r < 0) + return r; + if (r == 0) + break; + + c = capability_from_name(s); + if (c < 0) { + pam_syslog(handle, LOG_WARNING, "Unknown capability, ignoring: %s", s); + continue; + } + + m = UINT64_C(1) << c; + + if (!caps) + continue; + + if (*caps == UINT64_MAX) + b = subtract ? all_capabilities() : 0; + else + b = *caps; + + if (subtract) + *caps = b & ~m; + else + *caps = b | m; + } + + return 0; +} + +static int parse_argv( + pam_handle_t *handle, + int argc, const char **argv, + const char **class, + const char **type, + const char **desktop, + bool *debug, + uint64_t *default_capability_bounding_set, + uint64_t *default_capability_ambient_set) { + + int r; + + assert(handle); + assert(argc >= 0); + assert(argc == 0 || argv); + + for (int i = 0; i < argc; i++) { + const char *p; + + if ((p = startswith(argv[i], "class="))) { + if (class) + *class = p; + + } else if ((p = startswith(argv[i], "type="))) { + if (type) + *type = p; + + } else if ((p = startswith(argv[i], "desktop="))) { + if (desktop) + *desktop = p; + + } else if (streq(argv[i], "debug")) { + if (debug) + *debug = true; + + } else if ((p = startswith(argv[i], "debug="))) { + r = parse_boolean(p); + if (r < 0) + pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring: %s", p); + else if (debug) + *debug = r; + + } else if ((p = startswith(argv[i], "default-capability-bounding-set="))) { + r = parse_caps(handle, p, default_capability_bounding_set); + if (r < 0) + pam_syslog(handle, LOG_WARNING, "Failed to parse default-capability-bounding-set= argument, ignoring: %s", p); + + } else if ((p = startswith(argv[i], "default-capability-ambient-set="))) { + r = parse_caps(handle, p, default_capability_ambient_set); + if (r < 0) + pam_syslog(handle, LOG_WARNING, "Failed to parse default-capability-ambient-set= argument, ignoring: %s", p); + + } else + pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring.", argv[i]); + } + + return 0; +} + +static int acquire_user_record( + pam_handle_t *handle, + UserRecord **ret_record) { + + _cleanup_(user_record_unrefp) UserRecord *ur = NULL; + const char *username = NULL, *json = NULL; + _cleanup_free_ char *field = NULL; + int r; + + assert(handle); + + r = pam_get_user(handle, &username, NULL); + if (r != PAM_SUCCESS) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get user name: @PAMERR@"); + + if (isempty(username)) + return pam_syslog_pam_error(handle, LOG_ERR, PAM_SERVICE_ERR, "User name not valid."); + + /* If pam_systemd_homed (or some other module) already acquired the user record we can reuse it + * here. */ + field = strjoin("systemd-user-record-", username); + if (!field) + return pam_log_oom(handle); + + r = pam_get_data(handle, field, (const void**) &json); + if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM user record data: @PAMERR@"); + if (r == PAM_SUCCESS && json) { + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + + /* Parse cached record */ + r = json_parse(json, JSON_PARSE_SENSITIVE, &v, NULL, NULL); + if (r < 0) + return pam_syslog_errno(handle, LOG_ERR, r, "Failed to parse JSON user record: %m"); + + ur = user_record_new(); + if (!ur) + return pam_log_oom(handle); + + r = user_record_load(ur, v, USER_RECORD_LOAD_REFUSE_SECRET|USER_RECORD_PERMISSIVE); + if (r < 0) + return pam_syslog_errno(handle, LOG_ERR, r, "Failed to load user record: %m"); + + /* Safety check if cached record actually matches what we are looking for */ + if (!streq_ptr(username, ur->user_name)) + return pam_syslog_pam_error(handle, LOG_ERR, PAM_SERVICE_ERR, + "Acquired user record does not match user name."); + } else { + _cleanup_free_ char *formatted = NULL; + + /* Request the record ourselves */ + r = userdb_by_name(username, 0, &ur); + if (r < 0) { + pam_syslog_errno(handle, LOG_ERR, r, "Failed to get user record: %m"); + return PAM_USER_UNKNOWN; + } + + r = json_variant_format(ur->json, 0, &formatted); + if (r < 0) + return pam_syslog_errno(handle, LOG_ERR, r, "Failed to format user JSON: %m"); + + /* And cache it for everyone else */ + r = pam_set_data(handle, field, formatted, pam_cleanup_free); + if (r != PAM_SUCCESS) + return pam_syslog_pam_error(handle, LOG_ERR, r, + "Failed to set PAM user record data '%s': @PAMERR@", field); + TAKE_PTR(formatted); + } + + if (!uid_is_valid(ur->uid)) + return pam_syslog_pam_error(handle, LOG_ERR, PAM_SERVICE_ERR, + "Acquired user record does not have a UID."); + + if (ret_record) + *ret_record = TAKE_PTR(ur); + + return PAM_SUCCESS; +} + +static bool display_is_local(const char *display) { + assert(display); + + return + display[0] == ':' && + ascii_isdigit(display[1]); +} + +static int socket_from_display(const char *display) { + _cleanup_free_ char *f = NULL; + size_t k; + char *c; + union sockaddr_union sa; + socklen_t sa_len; + _cleanup_close_ int fd = -EBADF; + int r; + + assert(display); + + if (!display_is_local(display)) + return -EINVAL; + + k = strspn(display+1, "0123456789"); + + /* Try abstract socket first. */ + 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; + + r = sockaddr_un_set_path(&sa.un, f); + if (r < 0) + return r; + sa_len = r; + + fd = RET_NERRNO(socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)); + if (fd < 0) + return fd; + + r = RET_NERRNO(connect(fd, &sa.sa, sa_len)); + if (r >= 0) + return TAKE_FD(fd); + if (r != -ECONNREFUSED) + return r; + + /* Try also non-abstract socket. */ + r = sockaddr_un_set_path(&sa.un, f + 1); + if (r < 0) + return r; + sa_len = r; + + r = RET_NERRNO(connect(fd, &sa.sa, sa_len)); + if (r >= 0) + return TAKE_FD(fd); + return r; +} + +static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) { + _cleanup_free_ char *sys_path = NULL, *tty = NULL; + _cleanup_close_ int fd = -EBADF; + struct ucred ucred; + int v, r; + dev_t display_ctty; + + 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. */ + + fd = socket_from_display(display); + if (fd < 0) + return fd; + + r = getpeercred(fd, &ucred); + if (r < 0) + return r; + + r = get_ctty_devnr(ucred.pid, &display_ctty); + if (r < 0) + return r; + + if (asprintf(&sys_path, "/sys/dev/char/" DEVNUM_FORMAT_STR, DEVNUM_FORMAT_VAL(display_ctty)) < 0) + return -ENOMEM; + r = readlink_value(sys_path, &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, + 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) + return pam_log_oom(handle); + + r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", t, 0); + if (r != PAM_SUCCESS) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to set bus variable: @PAMERR@"); + + return PAM_SUCCESS; +} + +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 PAM_SUCCESS; + + if (streq(limit, "infinity")) { + r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", UINT64_MAX); + if (r < 0) + return pam_bus_log_create_error(handle, r); + + return PAM_SUCCESS; + } + + r = parse_permyriad(limit); + if (r >= 0) { + r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", UINT32_SCALE_FROM_PERMYRIAD(r)); + if (r < 0) + return pam_bus_log_create_error(handle, r); + + return PAM_SUCCESS; + } + + r = parse_size(limit, 1024, &val); + if (r >= 0) { + r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val); + if (r < 0) + return pam_bus_log_create_error(handle, r); + + return PAM_SUCCESS; + } + + pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.memory_max, ignoring: %s", limit); + return PAM_SUCCESS; +} + +static int append_session_runtime_max_sec(pam_handle_t *handle, sd_bus_message *m, const char *limit) { + usec_t val; + int r; + + /* No need to parse "infinity" here, it will be set by default later in scope_init() */ + if (isempty(limit) || streq(limit, "infinity")) + return PAM_SUCCESS; + + r = parse_sec(limit, &val); + if (r >= 0) { + r = sd_bus_message_append(m, "(sv)", "RuntimeMaxUSec", "t", (uint64_t) val); + if (r < 0) + return pam_bus_log_create_error(handle, r); + } else + pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.runtime_max_sec: %s, ignoring.", limit); + + return PAM_SUCCESS; +} + +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 PAM_SUCCESS; + + r = safe_atou64(limit, &val); + if (r >= 0) { + r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val); + if (r < 0) + return pam_bus_log_create_error(handle, r); + } else + pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.tasks_max, ignoring: %s", limit); + + return PAM_SUCCESS; +} + +static int append_session_cpu_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit) { + uint64_t val; + int r; + + if (isempty(limit)) + return PAM_SUCCESS; + + r = cg_cpu_weight_parse(limit, &val); + if (r < 0) + pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight, ignoring: %s", limit); + else { + r = sd_bus_message_append(m, "(sv)", "CPUWeight", "t", val); + if (r < 0) + return pam_bus_log_create_error(handle, r); + } + + return PAM_SUCCESS; +} + +static int append_session_io_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit) { + uint64_t val; + int r; + + if (isempty(limit)) + return PAM_SUCCESS; + + r = cg_weight_parse(limit, &val); + if (r < 0) + pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight, ignoring: %s", limit); + else { + r = sd_bus_message_append(m, "(sv)", "IOWeight", "t", val); + if (r < 0) + return pam_bus_log_create_error(handle, r); + } + + return PAM_SUCCESS; +} + +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) + return pam_syslog_pam_error(handle, LOG_ERR, r, + "Failed to set environment variable %s: @PAMERR@", key); + + return PAM_SUCCESS; +} + +static bool validate_runtime_directory(pam_handle_t *handle, const char *path, uid_t uid) { + struct stat st; + + assert(handle); + assert(path); + + /* 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. This is supposed to provide a careful safety net for supporting su/sudo + * type transitions: in that case the UID changes, but the session and thus the user owning it + * doesn't change. Since the $XDG_RUNTIME_DIR lifecycle is bound to the session's user being logged + * in at least once we should be particularly careful when setting the environment variable, since + * otherwise we might end up setting $XDG_RUNTIME_DIR to some directory owned by the wrong user. */ + + if (!path_is_absolute(path)) { + pam_syslog(handle, LOG_ERR, "Provided runtime directory '%s' is not absolute.", path); + goto fail; + } + + if (lstat(path, &st) < 0) { + pam_syslog_errno(handle, LOG_ERR, errno, "Failed to stat() runtime directory '%s': %m", path); + 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; +} + +static int pam_putenv_and_log(pam_handle_t *handle, const char *e, bool debug) { + int r; + + assert(handle); + assert(e); + + r = pam_putenv(handle, e); + if (r != PAM_SUCCESS) + return pam_syslog_pam_error(handle, LOG_ERR, r, + "Failed to set PAM environment variable %s: @PAMERR@", e); + + pam_debug_syslog(handle, debug, "PAM environment variable %s set based on user record.", e); + + return PAM_SUCCESS; +} + +static int apply_user_record_settings( + pam_handle_t *handle, + UserRecord *ur, + bool debug, + uint64_t default_capability_bounding_set, + uint64_t default_capability_ambient_set) { + int r; + + assert(handle); + assert(ur); + + if (ur->umask != MODE_INVALID) { + umask(ur->umask); + pam_debug_syslog(handle, debug, "Set user umask to %04o based on user record.", ur->umask); + } + + STRV_FOREACH(i, ur->environment) { + _cleanup_free_ char *n = NULL; + const char *e; + + assert_se(e = strchr(*i, '=')); /* environment was already validated while parsing JSON record, this thus must hold */ + + n = strndup(*i, e - *i); + if (!n) + return pam_log_oom(handle); + + if (pam_getenv(handle, n)) { + pam_debug_syslog(handle, debug, + "PAM environment variable $%s already set, not changing based on record.", *i); + continue; + } + + r = pam_putenv_and_log(handle, *i, debug); + if (r != PAM_SUCCESS) + return r; + } + + if (ur->email_address) { + if (pam_getenv(handle, "EMAIL")) + pam_debug_syslog(handle, debug, + "PAM environment variable $EMAIL already set, not changing based on user record."); + else { + _cleanup_free_ char *joined = NULL; + + joined = strjoin("EMAIL=", ur->email_address); + if (!joined) + return pam_log_oom(handle); + + r = pam_putenv_and_log(handle, joined, debug); + if (r != PAM_SUCCESS) + return r; + } + } + + if (ur->time_zone) { + if (pam_getenv(handle, "TZ")) + pam_debug_syslog(handle, debug, + "PAM environment variable $TZ already set, not changing based on user record."); + else if (!timezone_is_valid(ur->time_zone, LOG_DEBUG)) + pam_debug_syslog(handle, debug, + "Time zone specified in user record is not valid locally, not setting $TZ."); + else { + _cleanup_free_ char *joined = NULL; + + joined = strjoin("TZ=:", ur->time_zone); + if (!joined) + return pam_log_oom(handle); + + r = pam_putenv_and_log(handle, joined, debug); + if (r != PAM_SUCCESS) + return r; + } + } + + if (ur->preferred_language) { + if (pam_getenv(handle, "LANG")) + pam_debug_syslog(handle, debug, + "PAM environment variable $LANG already set, not changing based on user record."); + else if (locale_is_installed(ur->preferred_language) <= 0) + pam_debug_syslog(handle, debug, + "Preferred language specified in user record is not valid or not installed, not setting $LANG."); + else { + _cleanup_free_ char *joined = NULL; + + joined = strjoin("LANG=", ur->preferred_language); + if (!joined) + return pam_log_oom(handle); + + r = pam_putenv_and_log(handle, joined, debug); + if (r != PAM_SUCCESS) + return r; + } + } + + if (nice_is_valid(ur->nice_level)) { + if (nice(ur->nice_level) < 0) + pam_syslog_errno(handle, LOG_ERR, errno, + "Failed to set nice level to %i, ignoring: %m", ur->nice_level); + else + pam_debug_syslog(handle, debug, + "Nice level set to %i, based on user record.", ur->nice_level); + } + + for (int rl = 0; rl < _RLIMIT_MAX; rl++) { + + if (!ur->rlimits[rl]) + continue; + + r = setrlimit_closest(rl, ur->rlimits[rl]); + if (r < 0) + pam_syslog_errno(handle, LOG_ERR, r, + "Failed to set resource limit %s, ignoring: %m", rlimit_to_string(rl)); + else + pam_debug_syslog(handle, debug, + "Resource limit %s set, based on user record.", rlimit_to_string(rl)); + } + + uint64_t a, b; + a = user_record_capability_ambient_set(ur); + if (a == UINT64_MAX) + a = default_capability_ambient_set; + + b = user_record_capability_bounding_set(ur); + if (b == UINT64_MAX) + b = default_capability_bounding_set; + + if (a != UINT64_MAX && a != 0) { + a &= b; + + r = capability_ambient_set_apply(a, /* also_inherit= */ true); + if (r < 0) + pam_syslog_errno(handle, LOG_ERR, r, + "Failed to set ambient capabilities, ignoring: %m"); + } + + if (b != UINT64_MAX && !cap_test_all(b)) { + r = capability_bounding_set_drop(b, /* right_now= */ false); + if (r < 0) + pam_syslog_errno(handle, LOG_ERR, r, + "Failed to set bounding capabilities, ignoring: %m"); + } + + return PAM_SUCCESS; +} + +static int configure_runtime_directory( + pam_handle_t *handle, + UserRecord *ur, + const char *rt) { + + int r; + + assert(handle); + assert(ur); + assert(rt); + + if (!validate_runtime_directory(handle, rt, ur->uid)) + return PAM_SUCCESS; + + r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0); + if (r != PAM_SUCCESS) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to set runtime dir: @PAMERR@"); + + return export_legacy_dbus_address(handle, rt); +} + +static uint64_t pick_default_capability_ambient_set( + UserRecord *ur, + const char *service, + const char *seat) { + + /* If not configured otherwise, let's enable CAP_WAKE_ALARM for regular users when logging in on a + * seat (i.e. when they are present physically on the device), or when invoked for the systemd --user + * instances. This allows desktops to install CAP_WAKE_ALARM to implement alarm clock apps without + * much fuss. */ + + return ur && + user_record_disposition(ur) == USER_REGULAR && + (streq_ptr(service, "systemd-user") || !isempty(seat)) ? (UINT64_C(1) << CAP_WAKE_ALARM) : UINT64_MAX; +} + +typedef struct SessionContext { + const uid_t uid; + const pid_t pid; + const char *service; + const char *type; + const char *class; + const char *desktop; + const char *seat; + const uint32_t vtnr; + const char *tty; + const char *display; + const bool remote; + const char *remote_user; + const char *remote_host; + const char *memory_max; + const char *tasks_max; + const char *cpu_weight; + const char *io_weight; + const char *runtime_max_sec; +} SessionContext; + +static int create_session_message( + sd_bus *bus, + pam_handle_t *handle, + const SessionContext *context, + bool avoid_pidfd, + sd_bus_message **ret) { + + _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL; + _cleanup_close_ int pidfd = -EBADF; + int r; + + assert(bus); + assert(handle); + assert(context); + assert(ret); + + if (!avoid_pidfd) { + pidfd = pidfd_open(getpid_cached(), 0); + if (pidfd < 0 && !ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno)) + return -errno; + } + + r = bus_message_new_method_call(bus, &m, bus_login_mgr, pidfd >= 0 ? "CreateSessionWithPIDFD" : "CreateSession"); + if (r < 0) + return r; + + r = sd_bus_message_append(m, + pidfd >= 0 ? "uhsssssussbss" : "uusssssussbss", + (uint32_t) context->uid, + pidfd >= 0 ? pidfd : context->pid, + context->service, + context->type, + context->class, + context->desktop, + context->seat, + context->vtnr, + context->tty, + context->display, + context->remote, + context->remote_user, + context->remote_host); + if (r < 0) + return r; + + if (pidfd >= 0) { + r = sd_bus_message_append(m, "t", UINT64_C(0)); + if (r < 0) + return r; + } + + r = sd_bus_message_open_container(m, 'a', "(sv)"); + if (r < 0) + return r; + + r = append_session_memory_max(handle, m, context->memory_max); + if (r != PAM_SUCCESS) + return r; + + r = append_session_runtime_max_sec(handle, m, context->runtime_max_sec); + if (r != PAM_SUCCESS) + return r; + + r = append_session_tasks_max(handle, m, context->tasks_max); + if (r != PAM_SUCCESS) + return r; + + r = append_session_cpu_weight(handle, m, context->cpu_weight); + if (r != PAM_SUCCESS) + return r; + + r = append_session_io_weight(handle, m, context->io_weight); + if (r != PAM_SUCCESS) + return r; + + r = sd_bus_message_close_container(m); + if (r < 0) + return r; + + *ret = TAKE_PTR(m); + return 0; +} + +_public_ PAM_EXTERN int pam_sm_open_session( + pam_handle_t *handle, + int flags, + int argc, const char **argv) { + + /* Let's release the D-Bus connection once this function exits, after all the session might live + * quite a long time, and we are not going to process the bus connection in that time, so let's + * better close before the daemon kicks us off because we are not processing anything. */ + _cleanup_(pam_bus_data_disconnectp) PamBusData *d = NULL; + _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 + *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, *runtime_max_sec = NULL; + uint64_t default_capability_bounding_set = UINT64_MAX, default_capability_ambient_set = UINT64_MAX; + _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL; + _cleanup_(user_record_unrefp) UserRecord *ur = NULL; + int session_fd = -EBADF, existing, r; + bool debug = false, remote; + uint32_t vtnr = 0; + uid_t original_uid; + + assert(handle); + + if (parse_argv(handle, + argc, argv, + &class_pam, + &type_pam, + &desktop_pam, + &debug, + &default_capability_bounding_set, + &default_capability_ambient_set) < 0) + return PAM_SESSION_ERR; + + pam_debug_syslog(handle, debug, "pam-systemd initializing"); + + r = acquire_user_record(handle, &ur); + if (r != PAM_SUCCESS) + return r; + + /* Make most of this a NOP on non-logind systems */ + if (!logind_running()) + goto success; + + /* 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. */ + + r = pam_get_item(handle, PAM_SERVICE, (const void**) &service); + if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM service: @PAMERR@"); + if (streq_ptr(service, "systemd-user")) { + char rt[STRLEN("/run/user/") + DECIMAL_STR_MAX(uid_t)]; + + xsprintf(rt, "/run/user/"UID_FMT, ur->uid); + r = configure_runtime_directory(handle, ur, rt); + if (r != PAM_SUCCESS) + return r; + + goto success; + } + + /* Otherwise, we ask logind to create a session for us */ + + r = pam_get_item(handle, PAM_XDISPLAY, (const void**) &display); + if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM_XDISPLAY: @PAMERR@"); + r = pam_get_item(handle, PAM_TTY, (const void**) &tty); + if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM_TTY: @PAMERR@"); + r = pam_get_item(handle, PAM_RUSER, (const void**) &remote_user); + if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM_RUSER: @PAMERR@"); + r = pam_get_item(handle, PAM_RHOST, (const void**) &remote_host); + if (!IN_SET(r, PAM_BAD_ITEM, PAM_SUCCESS)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM_RHOST: @PAMERR@"); + + 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) { + pam_debug_syslog(handle, 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); + + r = pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max); + if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM systemd.memory_max data: @PAMERR@"); + r = pam_get_data(handle, "systemd.tasks_max", (const void **)&tasks_max); + if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM systemd.tasks_max data: @PAMERR@"); + r = pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight); + if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM systemd.cpu_weight data: @PAMERR@"); + r = pam_get_data(handle, "systemd.io_weight", (const void **)&io_weight); + if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM systemd.io_weight data: @PAMERR@"); + r = pam_get_data(handle, "systemd.runtime_max_sec", (const void **)&runtime_max_sec); + if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get PAM systemd.runtime_max_sec data: @PAMERR@"); + + /* Talk to logind over the message bus */ + r = pam_acquire_bus_connection(handle, "pam-systemd", &bus, &d); + if (r != PAM_SUCCESS) + return r; + + pam_debug_syslog(handle, 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", + ur->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_debug_syslog(handle, debug, + "Session limits: " + "memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s runtime_max_sec=%s", + strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight), strna(runtime_max_sec)); + + const SessionContext context = { + .uid = ur->uid, + .pid = 0, + .service = service, + .type = type, + .class = class, + .desktop = desktop, + .seat = seat, + .vtnr = vtnr, + .tty = tty, + .display = display, + .remote = remote, + .remote_user = remote_user, + .remote_host = remote_host, + .memory_max = memory_max, + .tasks_max = tasks_max, + .cpu_weight = cpu_weight, + .io_weight = io_weight, + .runtime_max_sec = runtime_max_sec, + }; + + r = create_session_message(bus, + handle, + &context, + /* avoid_pidfd = */ false, + &m); + if (r < 0) + return pam_bus_log_create_error(handle, r); + + r = sd_bus_call(bus, m, LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC, &error, &reply); + if (r < 0 && sd_bus_error_has_name(&error, SD_BUS_ERROR_UNKNOWN_METHOD)) { + sd_bus_error_free(&error); + pam_debug_syslog(handle, debug, + "CreateSessionWithPIDFD() API is not available, retrying with CreateSession()."); + + m = sd_bus_message_unref(m); + r = create_session_message(bus, + handle, + &context, + /* avoid_pidfd = */ true, + &m); + if (r < 0) + return pam_bus_log_create_error(handle, r); + + r = sd_bus_call(bus, m, LOGIN_SLOW_BUS_CALL_TIMEOUT_USEC, &error, &reply); + } + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) { + /* We are already in a session, don't do anything */ + pam_debug_syslog(handle, debug, + "Not creating session: %s", bus_error_message(&error, r)); + goto success; + } + + pam_syslog(handle, LOG_ERR, + "Failed to create session: %s", bus_error_message(&error, r)); + return PAM_SESSION_ERR; + } + + r = sd_bus_message_read(reply, + "soshusub", + &id, + &object_path, + &runtime_path, + &session_fd, + &original_uid, + &seat, + &vtnr, + &existing); + if (r < 0) + return pam_bus_log_parse_error(handle, r); + + pam_debug_syslog(handle, 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 == ur->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. */ + + r = configure_runtime_directory(handle, ur, 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) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to install existing flag: @PAMERR@"); + + if (session_fd >= 0) { + _cleanup_close_ int fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3); + if (fd < 0) + return pam_syslog_errno(handle, LOG_ERR, errno, "Failed to dup session fd: %m"); + + r = pam_set_data(handle, "systemd.session-fd", FD_TO_PTR(fd), NULL); + if (r != PAM_SUCCESS) + return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to install session fd: @PAMERR@"); + TAKE_FD(fd); + } + +success: + if (default_capability_ambient_set == UINT64_MAX) + default_capability_ambient_set = pick_default_capability_ambient_set(ur, service, seat); + + return apply_user_record_settings(handle, ur, debug, default_capability_bounding_set, default_capability_ambient_set); +} + +_public_ PAM_EXTERN int pam_sm_close_session( + pam_handle_t *handle, + int flags, + int argc, const char **argv) { + + const void *existing = NULL; + bool debug = false; + const char *id; + int r; + + assert(handle); + + if (parse_argv(handle, + argc, argv, + NULL, + NULL, + NULL, + &debug, + NULL, + NULL) < 0) + return PAM_SESSION_ERR; + + pam_debug_syslog(handle, debug, "pam-systemd shutting down"); + + /* Only release session if it wasn't pre-existing when we + * tried to create it */ + r = pam_get_data(handle, "systemd.existing", &existing); + if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA)) + return pam_syslog_pam_error(handle, LOG_ERR, r, + "Failed to get PAM systemd.existing data: @PAMERR@"); + + id = pam_getenv(handle, "XDG_SESSION_ID"); + if (id && !existing) { + _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL; + _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL; + + /* 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 = pam_acquire_bus_connection(handle, "pam-systemd", &bus, NULL); + if (r != PAM_SUCCESS) + return r; + + r = bus_call_method(bus, bus_login_mgr, "ReleaseSession", &error, NULL, "s", id); + if (r < 0) + return pam_syslog_pam_error(handle, LOG_ERR, PAM_SESSION_ERR, + "Failed to release session: %s", bus_error_message(&error, r)); + } + + /* 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; +} |