| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| |
| #include "sd-daemon.h" |
| #include "sd-event.h" |
| #include "sd-messages.h" |
| |
| #include "capability-util.h" |
| #include "clock-util.h" |
| #include "daemon-util.h" |
| #include "fd-util.h" |
| #include "fs-util.h" |
| #include "main-func.h" |
| #include "mkdir-label.h" |
| #include "network-util.h" |
| #include "process-util.h" |
| #include "signal-util.h" |
| #include "timesyncd-bus.h" |
| #include "timesyncd-conf.h" |
| #include "timesyncd-manager.h" |
| #include "user-util.h" |
| |
| static int advance_tstamp(int fd, const struct stat *st) { |
| assert_se(fd >= 0); |
| assert_se(st); |
| |
| /* So here's the problem: whenever we read the timestamp we'd like to ensure the next time we won't |
| * restore the exact same time again, but one at least one step further (so that comparing mtimes of |
| * the timestamp file is a reliable check that timesync did its thing). But file systems have |
| * different timestamp accuracy: traditional fat has 2s granularity, and even ext2 and friends expose |
| * different granularity depending on selected inode size during formatting! Hence, to ensure the |
| * timestamp definitely is increased, here's what we'll do: we'll first try to increase the timestamp |
| * by 1µs, write that and read it back. If it was updated, great. But if it was not, we'll instead |
| * increase the timestamp by 10µs, and do the same, then 100µs, then 1ms, and so on, until it works, |
| * or we reach 10s. If it still didn't work then, the fs is just broken and we give up. */ |
| |
| usec_t target = MAX3(now(CLOCK_REALTIME), |
| TIME_EPOCH * USEC_PER_SEC, |
| timespec_load(&st->st_mtim)); |
| |
| for (usec_t a = 1; a <= 10 * USEC_PER_SEC; a *= 10) { /* 1µs, 10µs, 100µs, 1ms, … 10s */ |
| struct timespec ts[2]; |
| struct stat new_st; |
| |
| /* Bump to the maximum of the old timestamp advanced by the specified unit, */ |
| usec_t c = usec_add(target, a); |
| |
| timespec_store(&ts[0], c); |
| ts[1] = ts[0]; |
| |
| if (futimens(fd, ts) < 0) { |
| /* If this doesn't work at all, log, don't fail but give up */ |
| log_warning_errno(errno, "Unable to update mtime of timestamp file, ignoring: %m"); |
| return 0; |
| } |
| |
| if (fstat(fd, &new_st) < 0) |
| return log_error_errno(errno, "Failed to stat timestamp file: %m"); |
| |
| if (timespec_load(&new_st.st_mtim) > target) { |
| log_debug("Successfully bumped timestamp file."); |
| return 1; |
| } |
| |
| log_debug("Tried to advance timestamp file by " USEC_FMT ", but this didn't work, file system timestamp granularity too coarse?", a); |
| } |
| |
| log_debug("Gave up trying to advance timestamp file."); |
| return 0; |
| } |
| |
| static int load_clock_timestamp(uid_t uid, gid_t gid) { |
| usec_t min = TIME_EPOCH * USEC_PER_SEC, ct; |
| _cleanup_close_ int fd = -EBADF; |
| int r; |
| |
| /* Let's try to make sure that the clock is always monotonically increasing, by saving the clock |
| * whenever we have a new NTP time, or when we shut down, and restoring it when we start again. This |
| * is particularly helpful on systems lacking a battery backed RTC. We also will adjust the time to |
| * at least the build time of systemd. */ |
| |
| fd = open(CLOCK_FILE, O_RDWR|O_CLOEXEC, 0644); |
| if (fd < 0) { |
| if (errno != ENOENT) |
| log_debug_errno(errno, "Unable to open timestamp file '" CLOCK_FILE "', ignoring: %m"); |
| |
| r = mkdir_safe_label(STATE_DIR, 0755, uid, gid, |
| MKDIR_FOLLOW_SYMLINK | MKDIR_WARN_MODE); |
| if (r < 0) |
| log_debug_errno(r, "Failed to create state directory, ignoring: %m"); |
| |
| /* create stamp file with the compiled-in date */ |
| r = touch_file(CLOCK_FILE, /* parents= */ false, min, uid, gid, 0644); |
| if (r < 0) |
| log_debug_errno(r, "Failed to create %s, ignoring: %m", CLOCK_FILE); |
| } else { |
| struct stat st; |
| usec_t stamp; |
| |
| /* check if the recorded time is later than the compiled-in one */ |
| if (fstat(fd, &st) < 0) |
| return log_error_errno(errno, "Unable to stat timestamp file '" CLOCK_FILE "': %m"); |
| |
| stamp = timespec_load(&st.st_mtim); |
| if (stamp > min) |
| min = stamp; |
| |
| /* Try to fix the access mode, so that we can still touch the file after dropping |
| * privileges */ |
| r = fchmod_and_chown(fd, 0644, uid, gid); |
| if (r < 0) |
| log_full_errno(ERRNO_IS_PRIVILEGE(r) ? LOG_DEBUG : LOG_WARNING, r, |
| "Failed to chmod or chown %s, ignoring: %m", CLOCK_FILE); |
| |
| (void) advance_tstamp(fd, &st); |
| } |
| |
| ct = now(CLOCK_REALTIME); |
| if (ct > min) |
| return 0; |
| |
| /* Not that it matters much, but we actually restore the clock to n+1 here rather than n, simply |
| * because we read n as time previously already and we want to progress here, i.e. not report the |
| * same time again. */ |
| if (clock_settime(CLOCK_REALTIME, TIMESPEC_STORE(min+1)) < 0) { |
| log_warning_errno(errno, "Failed to restore system clock, ignoring: %m"); |
| return 0; |
| } |
| |
| log_struct(LOG_INFO, |
| "MESSAGE_ID=" SD_MESSAGE_TIME_BUMP_STR, |
| "REALTIME_USEC=" USEC_FMT, min+1, |
| LOG_MESSAGE("System clock time unset or jumped backwards, restored from recorded timestamp: %s", |
| FORMAT_TIMESTAMP(min+1))); |
| return 0; |
| } |
| |
| static int run(int argc, char *argv[]) { |
| _cleanup_(manager_freep) Manager *m = NULL; |
| _unused_ _cleanup_(notify_on_cleanup) const char *notify_message = NULL; |
| const char *user = "systemd-timesync"; |
| uid_t uid, uid_current; |
| gid_t gid; |
| int r; |
| |
| log_set_facility(LOG_CRON); |
| log_setup(); |
| |
| umask(0022); |
| |
| if (argc != 1) |
| return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "This program does not take arguments."); |
| |
| uid = uid_current = geteuid(); |
| gid = getegid(); |
| |
| if (uid_current == 0) { |
| r = get_user_creds(&user, &uid, &gid, NULL, NULL, 0); |
| if (r < 0) |
| return log_error_errno(r, "Cannot resolve user name %s: %m", user); |
| } |
| |
| r = load_clock_timestamp(uid, gid); |
| if (r < 0) |
| return r; |
| |
| /* Drop privileges, but only if we have been started as root. If we are not running as root we assume all |
| * privileges are already dropped. */ |
| if (uid_current == 0) { |
| r = drop_privileges(uid, gid, (1ULL << CAP_SYS_TIME)); |
| if (r < 0) |
| return log_error_errno(r, "Failed to drop privileges: %m"); |
| } |
| |
| assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0); |
| |
| r = manager_new(&m); |
| if (r < 0) |
| return log_error_errno(r, "Failed to allocate manager: %m"); |
| |
| r = manager_connect_bus(m); |
| if (r < 0) |
| return log_error_errno(r, "Could not connect to bus: %m"); |
| |
| if (clock_is_localtime(NULL) > 0) { |
| log_info("The system is configured to read the RTC time in the local time zone. " |
| "This mode cannot be fully supported. All system time to RTC updates are disabled."); |
| m->rtc_local_time = true; |
| } |
| |
| r = manager_parse_config_file(m); |
| if (r < 0) |
| log_warning_errno(r, "Failed to parse configuration file: %m"); |
| |
| r = manager_parse_fallback_string(m, NTP_SERVERS); |
| if (r < 0) |
| return log_error_errno(r, "Failed to parse fallback server strings: %m"); |
| |
| log_debug("systemd-timesyncd running as pid " PID_FMT, getpid_cached()); |
| |
| notify_message = notify_start("READY=1\n" |
| "STATUS=Daemon is running", |
| NOTIFY_STOPPING); |
| |
| r = manager_setup_save_time_event(m); |
| if (r < 0) |
| return r; |
| |
| if (network_is_online()) { |
| r = manager_connect(m); |
| if (r < 0) |
| return r; |
| } |
| |
| r = sd_event_loop(m->event); |
| if (r < 0) |
| return log_error_errno(r, "Failed to run event loop: %m"); |
| |
| /* if we got an authoritative time, store it in the file system */ |
| if (m->save_on_exit) { |
| r = touch(CLOCK_FILE); |
| if (r < 0) |
| log_debug_errno(r, "Failed to touch " CLOCK_FILE ", ignoring: %m"); |
| } |
| |
| return 0; |
| } |
| |
| DEFINE_MAIN_FUNCTION(run); |
