#include <sys/timex.h>
#include <sys/socket.h>
#include <resolv.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <grp.h>
#include "missing.h"
#include "util.h"
#include "sd-network.h"
#include "event-util.h"
#include "network-util.h"
+#include "capability.h"
+#include "mkdir.h"
#include "timesyncd.h"
#define TIME_T_MAX (time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)
static int manager_connect(Manager *m);
static void manager_disconnect(Manager *m);
+static int load_clock(uid_t uid, gid_t gid) {
+ usec_t nt = TIME_EPOCH * USEC_PER_SEC, ct;
+ _cleanup_close_ int fd = -1;
+
+ /* 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. */
+
+ mkdir_p("/var/lib/systemd", 0755);
+
+ /* First, we try to create the clock file if it doesn't exist yet */
+ fd = open("/var/lib/systemd/clock", O_RDWR|O_CLOEXEC|O_EXCL, 0644);
+ if (fd < 0) {
+
+ fd = open("/var/lib/systemd/clock", O_RDWR|O_CLOEXEC|O_CREAT, 0644);
+ if (fd < 0) {
+ log_error("Failed to create /var/lib/systemd/clock: %m");
+ return -errno;
+ }
+
+ } else {
+ struct stat st;
+ usec_t ft;
+
+ if (fstat(fd, &st) < 0) {
+ log_error("fstat() failed: %m");
+ return -errno;
+ }
+
+ ft = timespec_load(&st.st_mtim);
+ if (ft > nt)
+ nt = ft;
+ }
+
+ ct = now(CLOCK_REALTIME);
+ if (nt > ct) {
+ struct timespec ts;
+ log_info("System clock time unset or jumped backwards, restoring.");
+
+ if (clock_settime(CLOCK_REALTIME, timespec_store(&ts, nt)) < 0)
+ log_error("Failed to restore system clock: %m");
+ }
+
+ /* Try to fix the access mode, so that we can still
+ touch the file after dropping priviliges */
+ fchmod(fd, 0644);
+ fchown(fd, uid, gid);
+
+ return 0;
+}
+
+static int save_clock(void) {
+
+ static const struct timespec ts[2] = {
+ { .tv_sec = 0, .tv_nsec = UTIME_NOW },
+ { .tv_sec = 0, .tv_nsec = UTIME_NOW },
+ };
+
+ int r;
+
+ r = utimensat(-1, "/var/lib/systemd/clock", ts, AT_SYMLINK_NOFOLLOW);
+ if (r < 0) {
+ log_warning("Failed to touch /var/lib/systemd/clock: %m");
+ return -errno;
+ }
+
+ return 0;
+}
+
static double ntp_ts_to_d(const struct ntp_ts *ts) {
return be32toh(ts->sec) + ((double)be32toh(ts->frac) / UINT_MAX);
}
return manager_connect(m);
}
- /* re-arm timer with incresing timeout, in case the packets never arrive back */
+ /* re-arm timer with increasing timeout, in case the packets never arrive back */
if (m->retry_interval > 0) {
if (m->retry_interval < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
m->retry_interval *= 2;
}
r = clock_adjtime(CLOCK_REALTIME, &tmx);
+
+ save_clock();
+
if (r < 0)
return r;
if (r < 0)
return r;
- sd_event_add_signal(m->event, &m->sigterm, SIGTERM, NULL, NULL);
- sd_event_add_signal(m->event, &m->sigint, SIGINT, NULL, NULL);
+ sd_event_set_watchdog(m->event, true);
+
+ sd_event_add_signal(m->event, NULL, SIGTERM, NULL, NULL);
+ sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
r = sd_resolve_default(&m->resolve);
if (r < 0)
manager_disconnect(m);
manager_flush_names(m);
- sd_event_source_unref(m->sigint);
- sd_event_source_unref(m->sigterm);
-
sd_event_source_unref(m->event_retry);
sd_event_source_unref(m->network_event_source);
int r;
r = sd_network_get_operational_state(&state);
- if (r >= 0 && streq("carrier", state))
+ if (r >= 0 && (streq("routable", state) || streq("degraded", state)))
return true;
else
return false;
return 0;
}
+static int drop_privileges(uid_t uid, gid_t gid) {
+
+ static const cap_value_t bits[] = {
+ CAP_SYS_TIME,
+ };
+
+ _cleanup_cap_free_ cap_t d = NULL;
+ int r;
+
+ /* Unfortunately we cannot leave privilege dropping to PID 1
+ * here, since we want to run as user but want to keep te
+ * CAP_SYS_TIME capability. Since file capabilities have been
+ * introduced this cannot be done across exec() anymore,
+ * unless our binary has the capability configured in the file
+ * system, which we want to avoid. */
+
+ if (setresgid(gid, gid, gid) < 0) {
+ log_error("Failed change group ID: %m");
+ return -errno;
+ }
+
+ if (setgroups(0, NULL) < 0) {
+ log_error("Failed to drop auxiliary groups list: %m");
+ return -errno;
+ }
+
+ if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
+ log_error("Failed to enable keep capabilities flag: %m");
+ return -errno;
+ }
+
+ r = setresuid(uid, uid, uid);
+ if (r < 0) {
+ log_error("Failed change user ID: %m");
+ return -errno;
+ }
+
+ if (prctl(PR_SET_KEEPCAPS, 0) < 0) {
+ log_error("Failed to disable keep capabilities flag: %m");
+ return -errno;
+ }
+
+ r = capability_bounding_set_drop(~(1ULL << CAP_SYS_TIME), true);
+ if (r < 0) {
+ log_error("Failed to drop capabilities: %s", strerror(-r));
+ return r;
+ }
+
+ d = cap_init();
+ if (!d)
+ return log_oom();
+
+ if (cap_set_flag(d, CAP_EFFECTIVE, ELEMENTSOF(bits), bits, CAP_SET) < 0 ||
+ cap_set_flag(d, CAP_PERMITTED, ELEMENTSOF(bits), bits, CAP_SET) < 0) {
+ log_error("Failed to enable capabilities bits: %m");
+ return -errno;
+ }
+
+ if (cap_set_proc(d) < 0) {
+ log_error("Failed to increase capabilities: %m");
+ return -errno;
+ }
+
+ return 0;
+}
+
int main(int argc, char *argv[]) {
+ const char *user = "systemd-timesync";
_cleanup_manager_free_ Manager *m = NULL;
+ uid_t uid;
+ gid_t gid;
int r;
if (argc > 1) {
umask(0022);
+ r = get_user_creds(&user, &uid, &gid, NULL, NULL);
+ if (r < 0) {
+ log_error("Cannot resolve user name %s: %s", user, strerror(-r));
+ return r;
+ }
+
+ r = load_clock(uid, gid);
+ if (r < 0)
+ goto out;
+
+ r = drop_privileges(uid, gid);
+ if (r < 0)
+ goto out;
+
assert_se(sigprocmask_many(SIG_BLOCK, SIGTERM, SIGINT, -1) == 0);
r = manager_new(&m);
}
sd_event_get_exit_code(m->event, &r);
+ save_clock();
out:
sd_notify(false, "STATUS=Shutting down...");
~ianmdlvl / elogind.git / blobdiff