diff options
Diffstat (limited to 'src/timesync/timesyncd.c')
| -rw-r--r-- | src/timesync/timesyncd.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/src/timesync/timesyncd.c b/src/timesync/timesyncd.c new file mode 100644 index 0000000..b4f70c0 --- /dev/null +++ b/src/timesync/timesyncd.c @@ -0,0 +1,175 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ + +#include "sd-daemon.h" +#include "sd-event.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.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" + +#define STATE_DIR "/var/lib/systemd/timesync" +#define CLOCK_FILE STATE_DIR "/clock" + +static int load_clock_timestamp(uid_t uid, gid_t gid) { + _cleanup_close_ int fd = -1; + usec_t min = TIME_EPOCH * USEC_PER_SEC; + usec_t ct; + 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) { + struct stat st; + usec_t stamp; + + /* check if the recorded time is later than the compiled-in one */ + r = fstat(fd, &st); + if (r >= 0) { + stamp = timespec_load(&st.st_mtim); + if (stamp > min) + min = stamp; + } + + if (geteuid() == 0) { + /* Try to fix the access mode, so that we can still + touch the file after dropping priviliges */ + r = fchmod_and_chown(fd, 0644, uid, gid); + if (r < 0) + log_warning_errno(r, "Failed to chmod or chown %s, ignoring: %m", CLOCK_FILE); + } + + } else { + 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"); + goto settime; + } + + /* create stamp file with the compiled-in date */ + r = touch_file(CLOCK_FILE, false, min, uid, gid, 0644); + if (r < 0) + log_debug_errno(r, "Failed to create %s, ignoring: %m", CLOCK_FILE); + } + +settime: + ct = now(CLOCK_REALTIME); + if (ct < min) { + struct timespec ts; + char date[FORMAT_TIMESTAMP_MAX]; + + log_info("System clock time unset or jumped backwards, restoring from recorded timestamp: %s", + format_timestamp(date, sizeof(date), min)); + + if (clock_settime(CLOCK_REALTIME, timespec_store(&ts, min)) < 0) + log_error_errno(errno, "Failed to restore system clock, ignoring: %m"); + } + + return 0; +} + +static int run(int argc, char *argv[]) { + _cleanup_(notify_on_cleanup) const char *notify_message = NULL; + _cleanup_(manager_freep) Manager *m = NULL; + const char *user = "systemd-timesync"; + uid_t uid, uid_current; + gid_t gid; + int r; + + log_set_facility(LOG_CRON); + log_setup_service(); + + 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); + + 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->sync) { + r = touch(CLOCK_FILE); + if (r < 0) + log_debug_errno(r, "Failed to touch %s, ignoring: %m", CLOCK_FILE); + } + + return 0; +} + +DEFINE_MAIN_FUNCTION(run); |