diff options
| -rw-r--r-- | src/timesync/timesyncd.c | 104 | ||||
| -rw-r--r-- | units/systemd-timesyncd.service.in | 10 |
2 files changed, 100 insertions, 14 deletions
diff --git a/src/timesync/timesyncd.c b/src/timesync/timesyncd.c index 6dcd942ec1..6935635a5e 100644 --- a/src/timesync/timesyncd.c +++ b/src/timesync/timesyncd.c @@ -53,6 +53,7 @@ #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) @@ -134,6 +135,78 @@ static int manager_clock_watch_setup(Manager *m); 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 jumed 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); } @@ -373,6 +446,9 @@ static int manager_adjust_clock(Manager *m, double offset, int leap_sec) { } r = clock_adjtime(CLOCK_REALTIME, &tmx); + + save_clock(); + if (r < 0) return r; @@ -1141,15 +1217,13 @@ static int manager_network_monitor_listen(Manager *m) { return 0; } -static int drop_privileges(void) { +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; - const char *name = "systemd-timesync"; - uid_t uid; - gid_t gid; int r; /* Unfortunately we cannot leave privilege dropping to PID 1 @@ -1159,12 +1233,6 @@ static int drop_privileges(void) { * unless our binary has the capability configured in the file * system, which we want to avoid. */ - r = get_user_creds(&name, &uid, &gid, NULL, NULL); - if (r < 0) { - log_error("Cannot resolve user name %s: %s", name, strerror(-r)); - return r; - } - if (setresgid(gid, gid, gid) < 0) { log_error("Failed change group ID: %m"); return -errno; @@ -1216,7 +1284,10 @@ static int drop_privileges(void) { } 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) { @@ -1231,7 +1302,17 @@ int main(int argc, char *argv[]) { umask(0022); - r = drop_privileges(); + 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; @@ -1268,6 +1349,7 @@ int main(int argc, char *argv[]) { } sd_event_get_exit_code(m->event, &r); + save_clock(); out: sd_notify(false, "STATUS=Shutting down..."); diff --git a/units/systemd-timesyncd.service.in b/units/systemd-timesyncd.service.in index 1d1f4860a8..ec2871455e 100644 --- a/units/systemd-timesyncd.service.in +++ b/units/systemd-timesyncd.service.in @@ -9,17 +9,21 @@ Description=Network Time Synchronization Documentation=man:systemd-timesyncd.service(8) ConditionCapability=CAP_SYS_TIME -After=systemd-networkd.service +DefaultDependencies=off +RequiresMountsFor=/var/lib/systemd/clock +After=systemd-remount-fs.service +Before=sysinit.target shutdown.target +Conflicts=shutdown.target [Service] Type=notify Restart=always RestartSec=0 ExecStart=@rootlibexecdir@/systemd-timesyncd -CapabilityBoundingSet=CAP_SYS_TIME CAP_SETUID CAP_SETGID CAP_SETPCAP +CapabilityBoundingSet=CAP_SYS_TIME CAP_SETUID CAP_SETGID CAP_SETPCAP CAP_CHOWN CAP_DAC_OVERRIDE PrivateTmp=yes PrivateDevices=yes WatchdogSec=1min [Install] -WantedBy=multi-user.target +WantedBy=sysinit.target |