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db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
bcdbbd7e | 2 | |
ca78ad1d ZJS |
3 | #include <sys/stat.h> |
4 | #include <sys/types.h> | |
5 | ||
687ed123 | 6 | #include "sd-daemon.h" |
3ffd4af2 | 7 | #include "sd-event.h" |
29920c5b | 8 | #include "sd-messages.h" |
3ffd4af2 | 9 | |
430f0182 | 10 | #include "capability-util.h" |
84e51726 | 11 | #include "clock-util.h" |
82310c79 | 12 | #include "daemon-util.h" |
3ffd4af2 | 13 | #include "fd-util.h" |
f4f15635 | 14 | #include "fs-util.h" |
82310c79 | 15 | #include "main-func.h" |
35cd0ba5 | 16 | #include "mkdir-label.h" |
84e51726 | 17 | #include "network-util.h" |
df0ff127 | 18 | #include "process-util.h" |
24882e06 | 19 | #include "signal-util.h" |
e7dd3947 | 20 | #include "timesyncd-bus.h" |
84e51726 | 21 | #include "timesyncd-conf.h" |
3ffd4af2 | 22 | #include "timesyncd-manager.h" |
b1d4f8e1 | 23 | #include "user-util.h" |
d636d376 | 24 | |
1acb4f61 LP |
25 | static int advance_tstamp(int fd, const struct stat *st) { |
26 | assert_se(fd >= 0); | |
27 | assert_se(st); | |
28 | ||
29 | /* So here's the problem: whenever we read the timestamp we'd like to ensure the next time we won't | |
30 | * restore the exact same time again, but one at least one step further (so that comparing mtimes of | |
31 | * the timestamp file is a reliable check that timesync did its thing). But file systems have | |
32 | * different timestamp accuracy: traditional fat has 2s granularity, and even ext2 and friends expose | |
33 | * different granularity depending on selected inode size during formatting! Hence, to ensure the | |
34 | * timestamp definitely is increased, here's what we'll do: we'll first try to increase the timestamp | |
e503019b LP |
35 | * by 1μs, write that and read it back. If it was updated, great. But if it was not, we'll instead |
36 | * increase the timestamp by 10μs, and do the same, then 100μs, then 1ms, and so on, until it works, | |
1acb4f61 LP |
37 | * or we reach 10s. If it still didn't work then, the fs is just broken and we give up. */ |
38 | ||
39 | usec_t target = MAX3(now(CLOCK_REALTIME), | |
40 | TIME_EPOCH * USEC_PER_SEC, | |
41 | timespec_load(&st->st_mtim)); | |
42 | ||
e503019b | 43 | for (usec_t a = 1; a <= 10 * USEC_PER_SEC; a *= 10) { /* 1μs, 10μs, 100μs, 1ms, … 10s */ |
1acb4f61 LP |
44 | struct timespec ts[2]; |
45 | struct stat new_st; | |
46 | ||
47 | /* Bump to the maximum of the old timestamp advanced by the specified unit, */ | |
48 | usec_t c = usec_add(target, a); | |
49 | ||
50 | timespec_store(&ts[0], c); | |
51 | ts[1] = ts[0]; | |
52 | ||
53 | if (futimens(fd, ts) < 0) { | |
54 | /* If this doesn't work at all, log, don't fail but give up */ | |
55 | log_warning_errno(errno, "Unable to update mtime of timestamp file, ignoring: %m"); | |
56 | return 0; | |
57 | } | |
58 | ||
59 | if (fstat(fd, &new_st) < 0) | |
60 | return log_error_errno(errno, "Failed to stat timestamp file: %m"); | |
61 | ||
62 | if (timespec_load(&new_st.st_mtim) > target) { | |
63 | log_debug("Successfully bumped timestamp file."); | |
64 | return 1; | |
65 | } | |
66 | ||
67 | log_debug("Tried to advance timestamp file by " USEC_FMT ", but this didn't work, file system timestamp granularity too coarse?", a); | |
68 | } | |
69 | ||
70 | log_debug("Gave up trying to advance timestamp file."); | |
71 | return 0; | |
72 | } | |
73 | ||
d636d376 | 74 | static int load_clock_timestamp(uid_t uid, gid_t gid) { |
5ba674cc | 75 | usec_t min = TIME_EPOCH * USEC_PER_SEC, ct; |
254d1313 | 76 | _cleanup_close_ int fd = -EBADF; |
d636d376 | 77 | int r; |
ece6e766 | 78 | |
84447fe7 LP |
79 | /* Let's try to make sure that the clock is always monotonically increasing, by saving the clock |
80 | * whenever we have a new NTP time, or when we shut down, and restoring it when we start again. This | |
81 | * is particularly helpful on systems lacking a battery backed RTC. We also will adjust the time to | |
82 | * at least the build time of systemd. */ | |
ece6e766 | 83 | |
86aaccb0 | 84 | fd = open(CLOCK_FILE, O_RDWR|O_CLOEXEC, 0644); |
84447fe7 LP |
85 | if (fd < 0) { |
86 | if (errno != ENOENT) | |
87 | log_debug_errno(errno, "Unable to open timestamp file '" CLOCK_FILE "', ignoring: %m"); | |
ece6e766 | 88 | |
86aaccb0 | 89 | r = mkdir_safe_label(STATE_DIR, 0755, uid, gid, |
37c1d5e9 | 90 | MKDIR_FOLLOW_SYMLINK | MKDIR_WARN_MODE); |
84447fe7 | 91 | if (r < 0) |
86aaccb0 | 92 | log_debug_errno(r, "Failed to create state directory, ignoring: %m"); |
d636d376 | 93 | |
d636d376 | 94 | /* create stamp file with the compiled-in date */ |
0fd08026 | 95 | r = touch_file(CLOCK_FILE, /* parents= */ false, min, uid, gid, 0644); |
86aaccb0 YW |
96 | if (r < 0) |
97 | log_debug_errno(r, "Failed to create %s, ignoring: %m", CLOCK_FILE); | |
84447fe7 LP |
98 | } else { |
99 | struct stat st; | |
100 | usec_t stamp; | |
101 | ||
102 | /* check if the recorded time is later than the compiled-in one */ | |
103 | if (fstat(fd, &st) < 0) | |
104 | return log_error_errno(errno, "Unable to stat timestamp file '" CLOCK_FILE "': %m"); | |
105 | ||
106 | stamp = timespec_load(&st.st_mtim); | |
107 | if (stamp > min) | |
108 | min = stamp; | |
109 | ||
110 | /* Try to fix the access mode, so that we can still touch the file after dropping | |
111 | * privileges */ | |
112 | r = fchmod_and_chown(fd, 0644, uid, gid); | |
113 | if (r < 0) | |
114 | log_full_errno(ERRNO_IS_PRIVILEGE(r) ? LOG_DEBUG : LOG_WARNING, r, | |
115 | "Failed to chmod or chown %s, ignoring: %m", CLOCK_FILE); | |
1acb4f61 LP |
116 | |
117 | (void) advance_tstamp(fd, &st); | |
53d133ea | 118 | } |
ece6e766 LP |
119 | |
120 | ct = now(CLOCK_REALTIME); | |
29920c5b LP |
121 | if (ct > min) |
122 | return 0; | |
ece6e766 | 123 | |
29920c5b LP |
124 | /* Not that it matters much, but we actually restore the clock to n+1 here rather than n, simply |
125 | * because we read n as time previously already and we want to progress here, i.e. not report the | |
126 | * same time again. */ | |
127 | if (clock_settime(CLOCK_REALTIME, TIMESPEC_STORE(min+1)) < 0) { | |
128 | log_warning_errno(errno, "Failed to restore system clock, ignoring: %m"); | |
129 | return 0; | |
ece6e766 LP |
130 | } |
131 | ||
29920c5b LP |
132 | log_struct(LOG_INFO, |
133 | "MESSAGE_ID=" SD_MESSAGE_TIME_BUMP_STR, | |
134 | "REALTIME_USEC=" USEC_FMT, min+1, | |
135 | LOG_MESSAGE("System clock time unset or jumped backwards, restored from recorded timestamp: %s", | |
136 | FORMAT_TIMESTAMP(min+1))); | |
ece6e766 LP |
137 | return 0; |
138 | } | |
139 | ||
82310c79 | 140 | static int run(int argc, char *argv[]) { |
84e51726 | 141 | _cleanup_(manager_freep) Manager *m = NULL; |
d7ac0952 | 142 | _unused_ _cleanup_(notify_on_cleanup) const char *notify_message = NULL; |
cedc8c44 | 143 | const char *user = "systemd-timesync"; |
444c1915 | 144 | uid_t uid, uid_current; |
ece6e766 | 145 | gid_t gid; |
687ed123 KS |
146 | int r; |
147 | ||
e8af6973 | 148 | log_set_facility(LOG_CRON); |
d2acb93d | 149 | log_setup(); |
687ed123 | 150 | |
e8af6973 LP |
151 | umask(0022); |
152 | ||
82310c79 YW |
153 | if (argc != 1) |
154 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "This program does not take arguments."); | |
84e51726 | 155 | |
444c1915 YW |
156 | uid = uid_current = geteuid(); |
157 | gid = getegid(); | |
158 | ||
159 | if (uid_current == 0) { | |
fafff8f1 | 160 | r = get_user_creds(&user, &uid, &gid, NULL, NULL, 0); |
82310c79 YW |
161 | if (r < 0) |
162 | return log_error_errno(r, "Cannot resolve user name %s: %m", user); | |
ece6e766 LP |
163 | } |
164 | ||
d636d376 | 165 | r = load_clock_timestamp(uid, gid); |
ece6e766 | 166 | if (r < 0) |
82310c79 | 167 | return r; |
ece6e766 | 168 | |
87a85e25 YW |
169 | /* Drop privileges, but only if we have been started as root. If we are not running as root we assume all |
170 | * privileges are already dropped. */ | |
444c1915 | 171 | if (uid_current == 0) { |
87a85e25 YW |
172 | r = drop_privileges(uid, gid, (1ULL << CAP_SYS_TIME)); |
173 | if (r < 0) | |
82310c79 | 174 | return log_error_errno(r, "Failed to drop privileges: %m"); |
87a85e25 | 175 | } |
a349eb10 | 176 | |
db7136ec | 177 | assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGRTMIN+18) >= 0); |
856a5a7d | 178 | |
687ed123 | 179 | r = manager_new(&m); |
82310c79 YW |
180 | if (r < 0) |
181 | return log_error_errno(r, "Failed to allocate manager: %m"); | |
687ed123 | 182 | |
e7dd3947 | 183 | r = manager_connect_bus(m); |
82310c79 YW |
184 | if (r < 0) |
185 | return log_error_errno(r, "Could not connect to bus: %m"); | |
e7dd3947 | 186 | |
6369641d | 187 | if (clock_is_localtime(NULL) > 0) { |
c264aeab | 188 | log_info("The system is configured to read the RTC time in the local time zone. " |
87ac8d99 | 189 | "This mode cannot be fully supported. All system time to RTC updates are disabled."); |
c264aeab KS |
190 | m->rtc_local_time = true; |
191 | } | |
192 | ||
84e51726 LP |
193 | r = manager_parse_config_file(m); |
194 | if (r < 0) | |
da927ba9 | 195 | log_warning_errno(r, "Failed to parse configuration file: %m"); |
e0e5ce23 | 196 | |
c4c06912 | 197 | r = manager_parse_fallback_string(m, NTP_SERVERS); |
82310c79 YW |
198 | if (r < 0) |
199 | return log_error_errno(r, "Failed to parse fallback server strings: %m"); | |
3745770a | 200 | |
df0ff127 | 201 | log_debug("systemd-timesyncd running as pid " PID_FMT, getpid_cached()); |
82310c79 YW |
202 | |
203 | notify_message = notify_start("READY=1\n" | |
204 | "STATUS=Daemon is running", | |
205 | NOTIFY_STOPPING); | |
39594d49 | 206 | |
33e82f3e DI |
207 | r = manager_setup_save_time_event(m); |
208 | if (r < 0) | |
209 | return r; | |
210 | ||
e0e5ce23 TG |
211 | if (network_is_online()) { |
212 | r = manager_connect(m); | |
213 | if (r < 0) | |
82310c79 | 214 | return r; |
e0e5ce23 | 215 | } |
678522cf | 216 | |
687ed123 | 217 | r = sd_event_loop(m->event); |
82310c79 YW |
218 | if (r < 0) |
219 | return log_error_errno(r, "Failed to run event loop: %m"); | |
856a5a7d | 220 | |
d636d376 | 221 | /* if we got an authoritative time, store it in the file system */ |
33e82f3e | 222 | if (m->save_on_exit) { |
86aaccb0 YW |
223 | r = touch(CLOCK_FILE); |
224 | if (r < 0) | |
33e82f3e | 225 | log_debug_errno(r, "Failed to touch " CLOCK_FILE ", ignoring: %m"); |
86aaccb0 | 226 | } |
687ed123 | 227 | |
690f02f4 | 228 | return 0; |
bcdbbd7e | 229 | } |
82310c79 YW |
230 | |
231 | DEFINE_MAIN_FUNCTION(run); |