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/* SPDX-License-Identifier: LGPL-2.1+ */
#include "sd-daemon.h"
#include "sd-event.h"
#include "capability-util.h"
#include "clock-util.h"
#include "fd-util.h"
#include "fs-util.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;
}
int main(int argc, char *argv[]) {
_cleanup_(manager_freep) Manager *m = NULL;
const char *user = "systemd-timesync";
uid_t uid, uid_current;
gid_t gid;
int r;
log_set_target(LOG_TARGET_AUTO);
log_set_facility(LOG_CRON);
log_parse_environment();
log_open();
umask(0022);
if (argc != 1) {
log_error("This program does not take arguments.");
r = -EINVAL;
goto finish;
}
uid = uid_current = geteuid();
gid = getegid();
if (uid_current == 0) {
r = get_user_creds(&user, &uid, &gid, NULL, NULL);
if (r < 0) {
log_error_errno(r, "Cannot resolve user name %s: %m", user);
goto finish;
}
}
r = load_clock_timestamp(uid, gid);
if (r < 0)
goto finish;
/* 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)
goto finish;
}
assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0);
r = manager_new(&m);
if (r < 0) {
log_error_errno(r, "Failed to allocate manager: %m");
goto finish;
}
r = manager_connect_bus(m);
if (r < 0) {
log_error_errno(r, "Could not connect to bus: %m");
goto finish;
}
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) {
log_error_errno(r, "Failed to parse fallback server strings: %m");
goto finish;
}
log_debug("systemd-timesyncd running as pid " PID_FMT, getpid_cached());
sd_notify(false,
"READY=1\n"
"STATUS=Daemon is running");
if (network_is_online()) {
r = manager_connect(m);
if (r < 0)
goto finish;
}
r = sd_event_loop(m->event);
if (r < 0) {
log_error_errno(r, "Failed to run event loop: %m");
goto finish;
}
/* 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);
}
sd_event_get_exit_code(m->event, &r);
finish:
sd_notify(false,
"STOPPING=1\n"
"STATUS=Shutting down...");
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
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