/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2014 Kay Sievers, Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see . ***/ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "missing.h" #include "util.h" #include "sparse-endian.h" #include "log.h" #include "socket-util.h" #include "list.h" #include "ratelimit.h" #include "strv.h" #include "conf-parser.h" #include "sd-event.h" #include "sd-resolve.h" #include "sd-daemon.h" #include "sd-network.h" #include "event-util.h" #include "network-util.h" #include "clock-util.h" #include "capability.h" #include "mkdir.h" #include "timesyncd.h" #define TIME_T_MAX (time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1) #ifndef ADJ_SETOFFSET #define ADJ_SETOFFSET 0x0100 /* add 'time' to current time */ #endif /* expected accuracy of time synchronization; used to adjust the poll interval */ #define NTP_ACCURACY_SEC 0.2 /* * "A client MUST NOT under any conditions use a poll interval less * than 15 seconds." */ #define NTP_POLL_INTERVAL_MIN_SEC 32 #define NTP_POLL_INTERVAL_MAX_SEC 2048 /* * Maximum delta in seconds which the system clock is gradually adjusted * (slew) to approach the network time. Deltas larger that this are set by * letting the system time jump. The kernel's limit for adjtime is 0.5s. */ #define NTP_MAX_ADJUST 0.4 /* NTP protocol, packet header */ #define NTP_LEAP_PLUSSEC 1 #define NTP_LEAP_MINUSSEC 2 #define NTP_LEAP_NOTINSYNC 3 #define NTP_MODE_CLIENT 3 #define NTP_MODE_SERVER 4 #define NTP_FIELD_LEAP(f) (((f) >> 6) & 3) #define NTP_FIELD_VERSION(f) (((f) >> 3) & 7) #define NTP_FIELD_MODE(f) ((f) & 7) #define NTP_FIELD(l, v, m) (((l) << 6) | ((v) << 3) | (m)) /* * "NTP timestamps are represented as a 64-bit unsigned fixed-point number, * in seconds relative to 0h on 1 January 1900." */ #define OFFSET_1900_1970 2208988800UL #define RETRY_USEC (30*USEC_PER_SEC) #define RATELIMIT_INTERVAL_USEC (10*USEC_PER_SEC) #define RATELIMIT_BURST 10 #define TIMEOUT_USEC (10*USEC_PER_SEC) struct ntp_ts { be32_t sec; be32_t frac; } _packed_; struct ntp_ts_short { be16_t sec; be16_t frac; } _packed_; struct ntp_msg { uint8_t field; uint8_t stratum; int8_t poll; int8_t precision; struct ntp_ts_short root_delay; struct ntp_ts_short root_dispersion; char refid[4]; struct ntp_ts reference_time; struct ntp_ts origin_time; struct ntp_ts recv_time; struct ntp_ts trans_time; } _packed_; static void manager_free(Manager *m); DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free); #define _cleanup_manager_free_ _cleanup_(manager_freep) static int manager_arm_timer(Manager *m, usec_t next); static int manager_clock_watch_setup(Manager *m); static int manager_connect(Manager *m); static void manager_disconnect(Manager *m); static double ntp_ts_to_d(const struct ntp_ts *ts) { return be32toh(ts->sec) + ((double)be32toh(ts->frac) / UINT_MAX); } static double ts_to_d(const struct timespec *ts) { return ts->tv_sec + (1.0e-9 * ts->tv_nsec); } static double tv_to_d(const struct timeval *tv) { return tv->tv_sec + (1.0e-6 * tv->tv_usec); } static double square(double d) { return d * d; } 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("/var/lib/systemd/clock", 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; } /* Try to fix the access mode, so that we can still touch the file after dropping priviliges */ fchmod(fd, 0644); fchown(fd, uid, gid); } else /* create stamp file with the compiled-in date */ touch_file("/var/lib/systemd/clock", true, min, uid, gid, 0644); 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("Failed to restore system clock: %m"); } return 0; } static int manager_timeout(sd_event_source *source, usec_t usec, void *userdata) { _cleanup_free_ char *pretty = NULL; Manager *m = userdata; assert(m); assert(m->current_server_name); assert(m->current_server_address); sockaddr_pretty(&m->current_server_address->sockaddr.sa, m->current_server_address->socklen, true, &pretty); log_info("Timed out waiting for reply from %s (%s).", strna(pretty), m->current_server_name->string); return manager_connect(m); } static int manager_send_request(Manager *m) { _cleanup_free_ char *pretty = NULL; struct ntp_msg ntpmsg = { /* * "The client initializes the NTP message header, sends the request * to the server, and strips the time of day from the Transmit * Timestamp field of the reply. For this purpose, all the NTP * header fields are set to 0, except the Mode, VN, and optional * Transmit Timestamp fields." */ .field = NTP_FIELD(0, 4, NTP_MODE_CLIENT), }; ssize_t len; int r; assert(m); assert(m->current_server_name); assert(m->current_server_address); m->event_timeout = sd_event_source_unref(m->event_timeout); /* * Set transmit timestamp, remember it; the server will send that back * as the origin timestamp and we have an indication that this is the * matching answer to our request. * * The actual value does not matter, We do not care about the correct * NTP UINT_MAX fraction; we just pass the plain nanosecond value. */ assert_se(clock_gettime(CLOCK_MONOTONIC, &m->trans_time_mon) >= 0); assert_se(clock_gettime(CLOCK_REALTIME, &m->trans_time) >= 0); ntpmsg.trans_time.sec = htobe32(m->trans_time.tv_sec + OFFSET_1900_1970); ntpmsg.trans_time.frac = htobe32(m->trans_time.tv_nsec); sockaddr_pretty(&m->current_server_address->sockaddr.sa, m->current_server_address->socklen, true, &pretty); len = sendto(m->server_socket, &ntpmsg, sizeof(ntpmsg), MSG_DONTWAIT, &m->current_server_address->sockaddr.sa, m->current_server_address->socklen); if (len == sizeof(ntpmsg)) { m->pending = true; log_debug("Sent NTP request to %s (%s).", strna(pretty), m->current_server_name->string); } else { log_debug("Sending NTP request to %s (%s) failed: %m", strna(pretty), m->current_server_name->string); return manager_connect(m); } /* 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; } else m->retry_interval = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC; r = manager_arm_timer(m, m->retry_interval); if (r < 0) { log_error("Failed to rearm timer: %s", strerror(-r)); return r; } r = sd_event_add_time( m->event, &m->event_timeout, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TIMEOUT_USEC, 0, manager_timeout, m); if (r < 0) { log_error("Failed to arm timeout timer: %s", strerror(-r)); return r; } return 0; } static int manager_timer(sd_event_source *source, usec_t usec, void *userdata) { Manager *m = userdata; assert(m); return manager_send_request(m); } static int manager_arm_timer(Manager *m, usec_t next) { int r; assert(m); assert(m->event_receive); if (next == 0) { m->event_timer = sd_event_source_unref(m->event_timer); return 0; } if (m->event_timer) { r = sd_event_source_set_time(m->event_timer, now(CLOCK_MONOTONIC) + next); if (r < 0) return r; return sd_event_source_set_enabled(m->event_timer, SD_EVENT_ONESHOT); } return sd_event_add_time( m->event, &m->event_timer, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + next, 0, manager_timer, m); } static int manager_clock_watch(sd_event_source *source, int fd, uint32_t revents, void *userdata) { Manager *m = userdata; assert(m); /* rearm timer */ manager_clock_watch_setup(m); /* skip our own jumps */ if (m->jumped) { m->jumped = false; return 0; } /* resync */ log_info("System time changed. Resyncing."); m->poll_resync = true; return manager_send_request(m); } /* wake up when the system time changes underneath us */ static int manager_clock_watch_setup(Manager *m) { struct itimerspec its = { .it_value.tv_sec = TIME_T_MAX }; int r; assert(m); m->event_clock_watch = sd_event_source_unref(m->event_clock_watch); safe_close(m->clock_watch_fd); m->clock_watch_fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC); if (m->clock_watch_fd < 0) { log_error("Failed to create timerfd: %m"); return -errno; } if (timerfd_settime(m->clock_watch_fd, TFD_TIMER_ABSTIME|TFD_TIMER_CANCEL_ON_SET, &its, NULL) < 0) { log_error("Failed to set up timerfd: %m"); return -errno; } r = sd_event_add_io(m->event, &m->event_clock_watch, m->clock_watch_fd, EPOLLIN, manager_clock_watch, m); if (r < 0) { log_error("Failed to create clock watch event source: %s", strerror(-r)); return r; } return 0; } static int manager_adjust_clock(Manager *m, double offset, int leap_sec) { struct timex tmx = {}; int r; assert(m); /* * For small deltas, tell the kernel to gradually adjust the system * clock to the NTP time, larger deltas are just directly set. * * Clear STA_UNSYNC, it will enable the kernel's 11-minute mode, which * syncs the system time periodically to the hardware clock. */ if (fabs(offset) < NTP_MAX_ADJUST) { tmx.modes = ADJ_STATUS | ADJ_NANO | ADJ_OFFSET | ADJ_TIMECONST | ADJ_MAXERROR | ADJ_ESTERROR; tmx.status = STA_PLL; tmx.offset = offset * NSEC_PER_SEC; tmx.constant = log2i(m->poll_interval_usec / USEC_PER_SEC) - 4; tmx.maxerror = 0; tmx.esterror = 0; log_debug(" adjust (slew): %+.3f sec\n", offset); } else { tmx.modes = ADJ_SETOFFSET | ADJ_NANO; /* ADJ_NANO uses nanoseconds in the microseconds field */ tmx.time.tv_sec = (long)offset; tmx.time.tv_usec = (offset - tmx.time.tv_sec) * NSEC_PER_SEC; /* the kernel expects -0.3s as {-1, 7000.000.000} */ if (tmx.time.tv_usec < 0) { tmx.time.tv_sec -= 1; tmx.time.tv_usec += NSEC_PER_SEC; } m->jumped = true; log_debug(" adjust (jump): %+.3f sec\n", offset); } switch (leap_sec) { case 1: tmx.status |= STA_INS; break; case -1: tmx.status |= STA_DEL; break; } r = clock_adjtime(CLOCK_REALTIME, &tmx); if (r < 0) return r; touch("/var/lib/systemd/clock"); m->drift_ppm = tmx.freq / 65536; log_debug(" status : %04i %s\n" " time now : %li.%03llu\n" " constant : %li\n" " offset : %+.3f sec\n" " freq offset : %+li (%i ppm)\n", tmx.status, tmx.status & STA_UNSYNC ? "" : "sync", tmx.time.tv_sec, (unsigned long long) (tmx.time.tv_usec / NSEC_PER_MSEC), tmx.constant, (double)tmx.offset / NSEC_PER_SEC, tmx.freq, m->drift_ppm); return 0; } static bool manager_sample_spike_detection(Manager *m, double offset, double delay) { unsigned int i, idx_cur, idx_new, idx_min; double jitter; double j; assert(m); m->packet_count++; /* ignore initial sample */ if (m->packet_count == 1) return false; /* store the current data in our samples array */ idx_cur = m->samples_idx; idx_new = (idx_cur + 1) % ELEMENTSOF(m->samples); m->samples_idx = idx_new; m->samples[idx_new].offset = offset; m->samples[idx_new].delay = delay; /* calculate new jitter value from the RMS differences relative to the lowest delay sample */ jitter = m->samples_jitter; for (idx_min = idx_cur, i = 0; i < ELEMENTSOF(m->samples); i++) if (m->samples[i].delay > 0 && m->samples[i].delay < m->samples[idx_min].delay) idx_min = i; j = 0; for (i = 0; i < ELEMENTSOF(m->samples); i++) j += square(m->samples[i].offset - m->samples[idx_min].offset); m->samples_jitter = sqrt(j / (ELEMENTSOF(m->samples) - 1)); /* ignore samples when resyncing */ if (m->poll_resync) return false; /* always accept offset if we are farther off than the round-trip delay */ if (fabs(offset) > delay) return false; /* we need a few samples before looking at them */ if (m->packet_count < 4) return false; /* do not accept anything worse than the maximum possible error of the best sample */ if (fabs(offset) > m->samples[idx_min].delay) return true; /* compare the difference between the current offset to the previous offset and jitter */ return fabs(offset - m->samples[idx_cur].offset) > 3 * jitter; } static void manager_adjust_poll(Manager *m, double offset, bool spike) { assert(m); if (m->poll_resync) { m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC; m->poll_resync = false; return; } /* set to minimal poll interval */ if (!spike && fabs(offset) > NTP_ACCURACY_SEC) { m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC; return; } /* increase polling interval */ if (fabs(offset) < NTP_ACCURACY_SEC * 0.25) { if (m->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC) m->poll_interval_usec *= 2; return; } /* decrease polling interval */ if (spike || fabs(offset) > NTP_ACCURACY_SEC * 0.75) { if (m->poll_interval_usec > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC) m->poll_interval_usec /= 2; return; } } static bool sockaddr_equal(union sockaddr_union *a, union sockaddr_union *b) { assert(a); assert(b); if (a->sa.sa_family != b->sa.sa_family) return false; if (a->sa.sa_family == AF_INET) return a->in.sin_addr.s_addr == b->in.sin_addr.s_addr; if (a->sa.sa_family == AF_INET6) return memcmp(&a->in6.sin6_addr, &b->in6.sin6_addr, sizeof(a->in6.sin6_addr)) == 0; return false; } static int manager_receive_response(sd_event_source *source, int fd, uint32_t revents, void *userdata) { Manager *m = userdata; struct ntp_msg ntpmsg; struct iovec iov = { .iov_base = &ntpmsg, .iov_len = sizeof(ntpmsg), }; union { struct cmsghdr cmsghdr; uint8_t buf[CMSG_SPACE(sizeof(struct timeval))]; } control; union sockaddr_union server_addr; struct msghdr msghdr = { .msg_iov = &iov, .msg_iovlen = 1, .msg_control = &control, .msg_controllen = sizeof(control), .msg_name = &server_addr, .msg_namelen = sizeof(server_addr), }; struct cmsghdr *cmsg; struct timespec now_ts; struct timeval *recv_time; ssize_t len; double origin, receive, trans, dest; double delay, offset; bool spike; int leap_sec; int r; assert(source); assert(m); if (revents & (EPOLLHUP|EPOLLERR)) { log_warning("Server connection returned error."); return manager_connect(m); } len = recvmsg(fd, &msghdr, MSG_DONTWAIT); if (len < 0) { if (errno == EAGAIN) return 0; log_warning("Error receiving message. Disconnecting."); return manager_connect(m); } if (iov.iov_len < sizeof(struct ntp_msg)) { log_warning("Invalid response from server. Disconnecting."); return manager_connect(m); } if (!m->current_server_name || !m->current_server_address || !sockaddr_equal(&server_addr, &m->current_server_address->sockaddr)) { log_debug("Response from unknown server."); return 0; } recv_time = NULL; for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) { if (cmsg->cmsg_level != SOL_SOCKET) continue; switch (cmsg->cmsg_type) { case SCM_TIMESTAMP: recv_time = (struct timeval *) CMSG_DATA(cmsg); break; } } if (!recv_time) { log_error("Invalid packet timestamp."); return -EINVAL; } if (!m->pending) { log_debug("Unexpected reply. Ignoring."); return 0; } /* check our "time cookie" (we just stored nanoseconds in the fraction field) */ if (be32toh(ntpmsg.origin_time.sec) != m->trans_time.tv_sec + OFFSET_1900_1970 || be32toh(ntpmsg.origin_time.frac) != m->trans_time.tv_nsec) { log_debug("Invalid reply; not our transmit time. Ignoring."); return 0; } m->event_timeout = sd_event_source_unref(m->event_timeout); if (be32toh(ntpmsg.recv_time.sec) < TIME_EPOCH + OFFSET_1900_1970 || be32toh(ntpmsg.trans_time.sec) < TIME_EPOCH + OFFSET_1900_1970) { log_debug("Invalid reply, returned times before epoch. Ignoring."); return manager_connect(m); } if (NTP_FIELD_LEAP(ntpmsg.field) == NTP_LEAP_NOTINSYNC) { log_debug("Server is not synchronized. Disconnecting."); return manager_connect(m); } if (!IN_SET(NTP_FIELD_VERSION(ntpmsg.field), 3, 4)) { log_debug("Response NTPv%d. Disconnecting.", NTP_FIELD_VERSION(ntpmsg.field)); return manager_connect(m); } if (NTP_FIELD_MODE(ntpmsg.field) != NTP_MODE_SERVER) { log_debug("Unsupported mode %d. Disconnecting.", NTP_FIELD_MODE(ntpmsg.field)); return manager_connect(m); } /* valid packet */ m->pending = false; m->retry_interval = 0; /* announce leap seconds */ if (NTP_FIELD_LEAP(ntpmsg.field) & NTP_LEAP_PLUSSEC) leap_sec = 1; else if (NTP_FIELD_LEAP(ntpmsg.field) & NTP_LEAP_MINUSSEC) leap_sec = -1; else leap_sec = 0; /* * "Timestamp Name ID When Generated * ------------------------------------------------------------ * Originate Timestamp T1 time request sent by client * Receive Timestamp T2 time request received by server * Transmit Timestamp T3 time reply sent by server * Destination Timestamp T4 time reply received by client * * The round-trip delay, d, and system clock offset, t, are defined as: * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2" */ assert_se(clock_gettime(CLOCK_MONOTONIC, &now_ts) >= 0); origin = tv_to_d(recv_time) - (ts_to_d(&now_ts) - ts_to_d(&m->trans_time_mon)) + OFFSET_1900_1970; receive = ntp_ts_to_d(&ntpmsg.recv_time); trans = ntp_ts_to_d(&ntpmsg.trans_time); dest = tv_to_d(recv_time) + OFFSET_1900_1970; offset = ((receive - origin) + (trans - dest)) / 2; delay = (dest - origin) - (trans - receive); spike = manager_sample_spike_detection(m, offset, delay); manager_adjust_poll(m, offset, spike); log_debug("NTP response:\n" " leap : %u\n" " version : %u\n" " mode : %u\n" " stratum : %u\n" " precision : %.6f sec (%d)\n" " reference : %.4s\n" " origin : %.3f\n" " receive : %.3f\n" " transmit : %.3f\n" " dest : %.3f\n" " offset : %+.3f sec\n" " delay : %+.3f sec\n" " packet count : %"PRIu64"\n" " jitter : %.3f%s\n" " poll interval: " USEC_FMT "\n", NTP_FIELD_LEAP(ntpmsg.field), NTP_FIELD_VERSION(ntpmsg.field), NTP_FIELD_MODE(ntpmsg.field), ntpmsg.stratum, exp2(ntpmsg.precision), ntpmsg.precision, ntpmsg.stratum == 1 ? ntpmsg.refid : "n/a", origin - OFFSET_1900_1970, receive - OFFSET_1900_1970, trans - OFFSET_1900_1970, dest - OFFSET_1900_1970, offset, delay, m->packet_count, m->samples_jitter, spike ? " spike" : "", m->poll_interval_usec / USEC_PER_SEC); if (!spike) { m->sync = true; r = manager_adjust_clock(m, offset, leap_sec); if (r < 0) log_error("Failed to call clock_adjtime(): %m"); } log_info("interval/delta/delay/jitter/drift " USEC_FMT "s/%+.3fs/%.3fs/%.3fs/%+ippm%s", m->poll_interval_usec / USEC_PER_SEC, offset, delay, m->samples_jitter, m->drift_ppm, spike ? " (ignored)" : ""); r = manager_arm_timer(m, m->poll_interval_usec); if (r < 0) { log_error("Failed to rearm timer: %s", strerror(-r)); return r; } return 0; } static int manager_listen_setup(Manager *m) { union sockaddr_union addr = {}; static const int tos = IPTOS_LOWDELAY; static const int on = 1; int r; assert(m); assert(m->server_socket < 0); assert(!m->event_receive); assert(m->current_server_address); addr.sa.sa_family = m->current_server_address->sockaddr.sa.sa_family; m->server_socket = socket(addr.sa.sa_family, SOCK_DGRAM | SOCK_CLOEXEC, 0); if (m->server_socket < 0) return -errno; r = bind(m->server_socket, &addr.sa, m->current_server_address->socklen); if (r < 0) return -errno; r = setsockopt(m->server_socket, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on)); if (r < 0) return -errno; setsockopt(m->server_socket, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)); return sd_event_add_io(m->event, &m->event_receive, m->server_socket, EPOLLIN, manager_receive_response, m); } static int manager_begin(Manager *m) { _cleanup_free_ char *pretty = NULL; int r; assert(m); assert_return(m->current_server_name, -EHOSTUNREACH); assert_return(m->current_server_address, -EHOSTUNREACH); m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC; sockaddr_pretty(&m->current_server_address->sockaddr.sa, m->current_server_address->socklen, true, &pretty); log_info("Using NTP server %s (%s).", strna(pretty), m->current_server_name->string); sd_notifyf(false, "STATUS=Using Time Server %s (%s).", strna(pretty), m->current_server_name->string); r = manager_listen_setup(m); if (r < 0) { log_warning("Failed to setup connection socket: %s", strerror(-r)); return r; } r = manager_clock_watch_setup(m); if (r < 0) return r; return manager_send_request(m); } static void server_name_flush_addresses(ServerName *n) { ServerAddress *a; assert(n); while ((a = n->addresses)) { LIST_REMOVE(addresses, n->addresses, a); free(a); } } static void manager_flush_names(Manager *m) { ServerName *n; assert(m); while ((n = m->servers)) { LIST_REMOVE(names, m->servers, n); free(n->string); server_name_flush_addresses(n); free(n); } } static int manager_resolve_handler(sd_resolve_query *q, int ret, const struct addrinfo *ai, void *userdata) { Manager *m = userdata; ServerAddress *a, *last = NULL; assert(q); assert(m); assert(m->current_server_name); m->resolve_query = sd_resolve_query_unref(m->resolve_query); if (ret != 0) { log_debug("Failed to resolve %s: %s", m->current_server_name->string, gai_strerror(ret)); /* Try next host */ return manager_connect(m); } server_name_flush_addresses(m->current_server_name); for (; ai; ai = ai->ai_next) { _cleanup_free_ char *pretty = NULL; assert(ai->ai_addr); assert(ai->ai_addrlen >= offsetof(struct sockaddr, sa_data)); assert(ai->ai_addrlen <= sizeof(union sockaddr_union)); if (!IN_SET(ai->ai_addr->sa_family, AF_INET, AF_INET6)) { log_warning("Unsuitable address protocol for %s", m->current_server_name->string); continue; } a = new0(ServerAddress, 1); if (!a) return log_oom(); memcpy(&a->sockaddr, ai->ai_addr, ai->ai_addrlen); a->socklen = ai->ai_addrlen; LIST_INSERT_AFTER(addresses, m->current_server_name->addresses, last, a); last = a; sockaddr_pretty(&a->sockaddr.sa, a->socklen, true, &pretty); log_debug("Resolved address %s for %s.", pretty, m->current_server_name->string); } if (!m->current_server_name->addresses) { log_error("Failed to find suitable address for host %s.", m->current_server_name->string); /* Try next host */ return manager_connect(m); } m->current_server_address = m->current_server_name->addresses; return manager_begin(m); } static int manager_retry(sd_event_source *source, usec_t usec, void *userdata) { Manager *m = userdata; assert(m); return manager_connect(m); } static int manager_connect(Manager *m) { struct addrinfo hints = { .ai_flags = AI_NUMERICSERV|AI_ADDRCONFIG, .ai_socktype = SOCK_DGRAM, }; int r; assert(m); manager_disconnect(m); m->event_retry = sd_event_source_unref(m->event_retry); if (!ratelimit_test(&m->ratelimit)) { log_debug("Slowing down attempts to contact servers."); r = sd_event_add_time(m->event, &m->event_retry, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + RETRY_USEC, 0, manager_retry, m); if (r < 0) { log_error("Failed to create retry timer: %s", strerror(-r)); return r; } return 0; } /* If we already are operating on some address, switch to the * next one. */ if (m->current_server_address && m->current_server_address->addresses_next) m->current_server_address = m->current_server_address->addresses_next; else { /* Hmm, we are through all addresses, let's look for the next host instead */ m->current_server_address = NULL; if (m->current_server_name && m->current_server_name->names_next) m->current_server_name = m->current_server_name->names_next; else { if (!m->servers) { m->current_server_name = NULL; log_debug("No server found."); return 0; } m->current_server_name = m->servers; } /* Tell the resolver to reread /etc/resolv.conf, in * case it changed. */ res_init(); r = sd_resolve_getaddrinfo(m->resolve, &m->resolve_query, m->current_server_name->string, "123", &hints, manager_resolve_handler, m); if (r < 0) { log_error("Failed to create resolver: %s", strerror(-r)); return r; } return 1; } r = manager_begin(m); if (r < 0) return r; return 1; } static int manager_add_server(Manager *m, const char *server) { ServerName *n, *tail; assert(m); assert(server); n = new0(ServerName, 1); if (!n) return -ENOMEM; n->string = strdup(server); if (!n->string) { free(n); return -ENOMEM; } LIST_FIND_TAIL(names, m->servers, tail); LIST_INSERT_AFTER(names, m->servers, tail, n); return 0; } static int manager_add_server_string(Manager *m, const char *string) { char *w, *state; size_t l; int r; assert(m); assert(string); FOREACH_WORD_QUOTED(w, l, string, state) { char t[l+1]; memcpy(t, w, l); t[l] = 0; r = manager_add_server(m, t); if (r < 0) log_error("Failed to add server %s to configuration, ignoring: %s", t, strerror(-r)); } return 0; } static void manager_disconnect(Manager *m) { assert(m); m->resolve_query = sd_resolve_query_unref(m->resolve_query); m->event_timer = sd_event_source_unref(m->event_timer); m->event_receive = sd_event_source_unref(m->event_receive); m->server_socket = safe_close(m->server_socket); m->event_clock_watch = sd_event_source_unref(m->event_clock_watch); m->clock_watch_fd = safe_close(m->clock_watch_fd); m->event_timeout = sd_event_source_unref(m->event_timeout); sd_notifyf(false, "STATUS=Idle."); } static int manager_new(Manager **ret) { _cleanup_manager_free_ Manager *m = NULL; int r; m = new0(Manager, 1); if (!m) return -ENOMEM; m->server_socket = m->clock_watch_fd = -1; RATELIMIT_INIT(m->ratelimit, RATELIMIT_INTERVAL_USEC, RATELIMIT_BURST); r = sd_event_default(&m->event); if (r < 0) return r; 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) return r; r = sd_resolve_attach_event(m->resolve, m->event, 0); if (r < 0) return r; r = manager_clock_watch_setup(m); if (r < 0) return r; *ret = m; m = NULL; return 0; } static void manager_free(Manager *m) { if (!m) return; manager_disconnect(m); manager_flush_names(m); sd_event_source_unref(m->event_retry); sd_event_source_unref(m->network_event_source); sd_network_monitor_unref(m->network_monitor); sd_resolve_unref(m->resolve); sd_event_unref(m->event); free(m); } int config_parse_servers( const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata) { Manager *m = userdata; assert(filename); assert(lvalue); assert(rvalue); manager_flush_names(m); manager_add_server_string(m, rvalue); return 0; } static int manager_parse_config_file(Manager *m) { static const char fn[] = "/etc/systemd/timesyncd.conf"; _cleanup_fclose_ FILE *f = NULL; int r; assert(m); f = fopen(fn, "re"); if (!f) { if (errno == ENOENT) return 0; log_warning("Failed to open configuration file %s: %m", fn); return -errno; } r = config_parse(NULL, fn, f, "Time\0", config_item_perf_lookup, (void*) timesyncd_gperf_lookup, false, false, m); if (r < 0) log_warning("Failed to parse configuration file: %s", strerror(-r)); return r; } static bool network_is_online(void) { _cleanup_free_ char *state = NULL; int r; r = sd_network_get_operational_state(&state); if (r >= 0 && STR_IN_SET(state, "routable", "degraded")) return true; return false; } static int manager_network_event_handler(sd_event_source *s, int fd, uint32_t revents, void *userdata) { Manager *m = userdata; bool connected, online; int r; assert(m); /* check if the machine is online */ online = network_is_online(); /* check if the client is currently connected */ connected = (m->server_socket != -1); if (connected && !online) { log_info("No network connectivity, watching for changes."); manager_disconnect(m); } else if (!connected && online) { log_info("Network configuration changed, trying to establish connection."); if (m->current_server_address) { r = manager_begin(m); if (r < 0) return r; } else { r = manager_connect(m); if (r < 0) return r; } } sd_network_monitor_flush(m->network_monitor); return 0; } static int manager_network_monitor_listen(Manager *m) { _cleanup_event_source_unref_ sd_event_source *event_source = NULL; _cleanup_network_monitor_unref_ sd_network_monitor *monitor = NULL; int r, fd, events; r = sd_network_monitor_new(NULL, &monitor); if (r < 0) return r; fd = sd_network_monitor_get_fd(monitor); if (fd < 0) return fd; events = sd_network_monitor_get_events(monitor); if (events < 0) return events; r = sd_event_add_io(m->event, &event_source, fd, events, &manager_network_event_handler, m); if (r < 0) return r; m->network_monitor = monitor; m->network_event_source = event_source; monitor = NULL; event_source = NULL; 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) { log_error("This program does not take arguments."); return EXIT_FAILURE; } log_set_target(LOG_TARGET_AUTO); log_set_facility(LOG_CRON); log_parse_environment(); log_open(); 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_timestamp(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); if (r < 0) { log_error("Failed to allocate manager: %s", strerror(-r)); goto out; } manager_add_server_string(m, NTP_SERVERS); manager_parse_config_file(m); r = manager_network_monitor_listen(m); if (r < 0) { log_error("Failed to listen to networkd events: %s", strerror(-r)); goto out; } log_debug("systemd-timesyncd running as pid %lu", (unsigned long) getpid()); sd_notify(false, "READY=1"); if (network_is_online()) { r = manager_connect(m); if (r < 0) goto out; } r = sd_event_loop(m->event); if (r < 0) { log_error("Failed to run event loop: %s", strerror(-r)); goto out; } sd_event_get_exit_code(m->event, &r); /* if we got an authoritative time, store it in the file system */ if (m->sync) touch("/var/lib/systemd/clock"); out: sd_notify(false, "STATUS=Shutting down..."); return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS; }