1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3 #include <sys/stat.h>
4 #include <sys/types.h>
5
6 #include "sd-daemon.h"
7 #include "sd-event.h"
8
9 #include "capability-util.h"
10 #include "clock-util.h"
11 #include "daemon-util.h"
12 #include "fd-util.h"
13 #include "fs-util.h"
14 #include "main-func.h"
15 #include "mkdir-label.h"
16 #include "network-util.h"
17 #include "process-util.h"
18 #include "signal-util.h"
19 #include "timesyncd-bus.h"
20 #include "timesyncd-conf.h"
21 #include "timesyncd-manager.h"
22 #include "user-util.h"
23
load_clock_timestamp(uid_t uid,gid_t gid)24 static int load_clock_timestamp(uid_t uid, gid_t gid) {
25 usec_t min = TIME_EPOCH * USEC_PER_SEC, ct;
26 _cleanup_close_ int fd = -1;
27 int r;
28
29 /* Let's try to make sure that the clock is always
30 * monotonically increasing, by saving the clock whenever we
31 * have a new NTP time, or when we shut down, and restoring it
32 * when we start again. This is particularly helpful on
33 * systems lacking a battery backed RTC. We also will adjust
34 * the time to at least the build time of systemd. */
35
36 fd = open(CLOCK_FILE, O_RDWR|O_CLOEXEC, 0644);
37 if (fd >= 0) {
38 struct stat st;
39 usec_t stamp;
40
41 /* check if the recorded time is later than the compiled-in one */
42 if (fstat(fd, &st) >= 0) {
43 stamp = timespec_load(&st.st_mtim);
44 if (stamp > min)
45 min = stamp;
46 }
47
48 if (geteuid() == 0) {
49 /* Try to fix the access mode, so that we can still
50 touch the file after dropping privileges */
51 r = fchmod_and_chown(fd, 0644, uid, gid);
52 if (r < 0)
53 log_warning_errno(r, "Failed to chmod or chown %s, ignoring: %m", CLOCK_FILE);
54 }
55
56 } else {
57 r = mkdir_safe_label(STATE_DIR, 0755, uid, gid,
58 MKDIR_FOLLOW_SYMLINK | MKDIR_WARN_MODE);
59 if (r < 0) {
60 log_debug_errno(r, "Failed to create state directory, ignoring: %m");
61 goto settime;
62 }
63
64 /* create stamp file with the compiled-in date */
65 r = touch_file(CLOCK_FILE, /* parents= */ false, min, uid, gid, 0644);
66 if (r < 0)
67 log_debug_errno(r, "Failed to create %s, ignoring: %m", CLOCK_FILE);
68 }
69
70 settime:
71 ct = now(CLOCK_REALTIME);
72 if (ct < min) {
73 char date[FORMAT_TIMESTAMP_MAX];
74
75 log_info("System clock time unset or jumped backwards, restoring from recorded timestamp: %s",
76 format_timestamp(date, sizeof(date), min));
77
78 if (clock_settime(CLOCK_REALTIME, TIMESPEC_STORE(min)) < 0)
79 log_error_errno(errno, "Failed to restore system clock, ignoring: %m");
80 }
81
82 return 0;
83 }
84
run(int argc,char * argv[])85 static int run(int argc, char *argv[]) {
86 _cleanup_(manager_freep) Manager *m = NULL;
87 _unused_ _cleanup_(notify_on_cleanup) const char *notify_message = NULL;
88 const char *user = "systemd-timesync";
89 uid_t uid, uid_current;
90 gid_t gid;
91 int r;
92
93 log_set_facility(LOG_CRON);
94 log_setup();
95
96 umask(0022);
97
98 if (argc != 1)
99 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "This program does not take arguments.");
100
101 uid = uid_current = geteuid();
102 gid = getegid();
103
104 if (uid_current == 0) {
105 r = get_user_creds(&user, &uid, &gid, NULL, NULL, 0);
106 if (r < 0)
107 return log_error_errno(r, "Cannot resolve user name %s: %m", user);
108 }
109
110 r = load_clock_timestamp(uid, gid);
111 if (r < 0)
112 return r;
113
114 /* Drop privileges, but only if we have been started as root. If we are not running as root we assume all
115 * privileges are already dropped. */
116 if (uid_current == 0) {
117 r = drop_privileges(uid, gid, (1ULL << CAP_SYS_TIME));
118 if (r < 0)
119 return log_error_errno(r, "Failed to drop privileges: %m");
120 }
121
122 assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0);
123
124 r = manager_new(&m);
125 if (r < 0)
126 return log_error_errno(r, "Failed to allocate manager: %m");
127
128 r = manager_connect_bus(m);
129 if (r < 0)
130 return log_error_errno(r, "Could not connect to bus: %m");
131
132 if (clock_is_localtime(NULL) > 0) {
133 log_info("The system is configured to read the RTC time in the local time zone. "
134 "This mode cannot be fully supported. All system time to RTC updates are disabled.");
135 m->rtc_local_time = true;
136 }
137
138 r = manager_parse_config_file(m);
139 if (r < 0)
140 log_warning_errno(r, "Failed to parse configuration file: %m");
141
142 r = manager_parse_fallback_string(m, NTP_SERVERS);
143 if (r < 0)
144 return log_error_errno(r, "Failed to parse fallback server strings: %m");
145
146 log_debug("systemd-timesyncd running as pid " PID_FMT, getpid_cached());
147
148 notify_message = notify_start("READY=1\n"
149 "STATUS=Daemon is running",
150 NOTIFY_STOPPING);
151
152 r = manager_setup_save_time_event(m);
153 if (r < 0)
154 return r;
155
156 if (network_is_online()) {
157 r = manager_connect(m);
158 if (r < 0)
159 return r;
160 }
161
162 r = sd_event_loop(m->event);
163 if (r < 0)
164 return log_error_errno(r, "Failed to run event loop: %m");
165
166 /* if we got an authoritative time, store it in the file system */
167 if (m->save_on_exit) {
168 r = touch(CLOCK_FILE);
169 if (r < 0)
170 log_debug_errno(r, "Failed to touch " CLOCK_FILE ", ignoring: %m");
171 }
172
173 return 0;
174 }
175
176 DEFINE_MAIN_FUNCTION(run);
177