contrib/ntpd/ntp.c

   1 /*      $OpenBSD: ntp.c,v 1.50 2005/02/02 19:03:52 henning Exp $ */
   2
   3 /*
   4  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
   5  * Copyright (c) 2004 Alexander Guy <alexander.guy@andern.org>
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
  16  * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
  17  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #include <sys/param.h>
  21 #include <sys/time.h>
  22 #include <sys/stat.h>
  23 #include <errno.h>
  24 #include <fcntl.h>
  25 #include <paths.h>
  26 #include <poll.h>
  27 #include <pwd.h>
  28 #include <signal.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <time.h>
  32 #include <unistd.h>
  33
  34 #include "ntpd.h"
  35 #include "ntp.h"
  36
  37 #define PFD_PIPE_MAIN   0
  38 #define PFD_MAX         1
  39
  40 volatile sig_atomic_t    ntp_quit = 0;
  41 struct imsgbuf          *ibuf_main;
  42 struct ntpd_conf        *conf;
  43 u_int                    peer_cnt;
  44
  45 void    ntp_sighdlr(int);
  46 int     ntp_dispatch_imsg(void);
  47 void    peer_add(struct ntp_peer *);
  48 void    peer_remove(struct ntp_peer *);
  49 int     offset_compare(const void *, const void *);
  50
  51 void
  52 ntp_sighdlr(int sig)
  53 {
  54         switch (sig) {
  55         case SIGINT:
  56         case SIGTERM:
  57                 ntp_quit = 1;
  58                 break;
  59         }
  60 }
  61
  62 pid_t
  63 ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
  64 {
  65         int                      a, b, nfds, i, j, idx_peers, timeout, nullfd;
  66         u_int                    pfd_elms = 0, idx2peer_elms = 0;
  67         u_int                    listener_cnt, new_cnt, sent_cnt;
  68         pid_t                    pid;
  69         struct pollfd           *pfd = NULL;
  70         struct passwd           *pw;
  71         struct servent          *se;
  72         struct listen_addr      *la;
  73         struct ntp_peer         *p;
  74         struct ntp_peer         **idx2peer = NULL;
  75         struct timespec          tp;
  76         struct stat              stb;
  77         time_t                   nextaction;
  78         void                    *newp;
  79
  80         switch (pid = fork()) {
  81         case -1:
  82                 fatal("cannot fork");
  83         case 0:
  84                 break;
  85         default:
  86                 return (pid);
  87         }
  88
  89         if ((se = getservbyname("ntp", "udp")) == NULL)
  90                 fatal("getservbyname");
  91
  92         if ((pw = getpwnam(NTPD_USER)) == NULL)
  93                 fatal("getpwnam");
  94
  95         if ((nullfd = open(_PATH_DEVNULL, O_RDWR, 0)) == -1)
  96                 fatal(NULL);
  97
  98         if (stat(pw->pw_dir, &stb) == -1)
  99                 fatal("stat");
 100         if (stb.st_uid != 0 || (stb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
 101                 fatal("bad privsep dir permissions");
 102         if (chroot(pw->pw_dir) == -1)
 103                 fatal("chroot");
 104         if (chdir("/") == -1)
 105                 fatal("chdir(\"/\")");
 106
 107         if (!nconf->debug) {
 108                 dup2(nullfd, STDIN_FILENO);
 109                 dup2(nullfd, STDOUT_FILENO);
 110                 dup2(nullfd, STDERR_FILENO);
 111         }
 112         close(nullfd);
 113
 114         setproctitle("ntp engine");
 115
 116         conf = nconf;
 117         setup_listeners(se, conf, &listener_cnt);
 118
 119         if (setgroups(1, &pw->pw_gid) ||
 120             setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 121             seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 122                 fatal("can't drop privileges");
 123
 124         endpwent();
 125         endservent();
 126
 127         signal(SIGTERM, ntp_sighdlr);
 128         signal(SIGINT, ntp_sighdlr);
 129         signal(SIGPIPE, SIG_IGN);
 130         signal(SIGHUP, SIG_IGN);
 131
 132         close(pipe_prnt[0]);
 133         if ((ibuf_main = malloc(sizeof(struct imsgbuf))) == NULL)
 134                 fatal(NULL);
 135         imsg_init(ibuf_main, pipe_prnt[1]);
 136
 137         TAILQ_FOREACH(p, &conf->ntp_peers, entry)
 138                 client_peer_init(p);
 139
 140         bzero(&conf->status, sizeof(conf->status));
 141         conf->status.leap = LI_ALARM;
 142         clock_getres(CLOCK_REALTIME, &tp);
 143         b = 1000000000 / tp.tv_nsec;    /* convert to Hz */
 144         for (a = 0; b > 1; a--, b >>= 1);
 145         conf->status.precision = a;
 146         conf->scale = 1;
 147
 148         log_info("ntp engine ready");
 149
 150         peer_cnt = 0;
 151         TAILQ_FOREACH(p, &conf->ntp_peers, entry)
 152                 peer_cnt++;
 153
 154         while (ntp_quit == 0) {
 155                 if (peer_cnt > idx2peer_elms) {
 156                         if ((newp = realloc(idx2peer, sizeof(void *) *
 157                             peer_cnt)) == NULL) {
 158                                 /* panic for now */
 159                                 log_warn("could not resize idx2peer from %u -> "
 160                                     "%u entries", idx2peer_elms, peer_cnt);
 161                                 fatalx("exiting");
 162                         }
 163                         idx2peer = newp;
 164                         idx2peer_elms = peer_cnt;
 165                 }
 166
 167                 new_cnt = PFD_MAX + peer_cnt + listener_cnt;
 168                 if (new_cnt > pfd_elms) {
 169                         if ((newp = realloc(pfd, sizeof(struct pollfd) *
 170                             new_cnt)) == NULL) {
 171                                 /* panic for now */
 172                                 log_warn("could not resize pfd from %u -> "
 173                                     "%u entries", pfd_elms, new_cnt);
 174                                 fatalx("exiting");
 175                         }
 176                         pfd = newp;
 177                         pfd_elms = new_cnt;
 178                 }
 179
 180                 bzero(pfd, sizeof(struct pollfd) * pfd_elms);
 181                 bzero(idx2peer, sizeof(void *) * idx2peer_elms);
 182                 nextaction = time(NULL) + 3600;
 183                 pfd[PFD_PIPE_MAIN].fd = ibuf_main->fd;
 184                 pfd[PFD_PIPE_MAIN].events = POLLIN;
 185
 186                 i = 1;
 187                 TAILQ_FOREACH(la, &conf->listen_addrs, entry) {
 188                         pfd[i].fd = la->fd;
 189                         pfd[i].events = POLLIN;
 190                         i++;
 191                 }
 192
 193                 idx_peers = i;
 194                 sent_cnt = 0;
 195                 TAILQ_FOREACH(p, &conf->ntp_peers, entry) {
 196                         if (p->next > 0 && p->next < nextaction)
 197                                 nextaction = p->next;
 198                         if (p->next > 0 && p->next <= time(NULL))
 199                                 if (client_query(p) == 0)
 200                                         sent_cnt++;
 201
 202                         if (p->deadline > 0 && p->deadline < nextaction)
 203                                 nextaction = p->deadline;
 204                         if (p->deadline > 0 && p->deadline <= time(NULL)) {
 205                                 timeout = error_interval();
 206                                 log_debug("no reply from %s received in time, "
 207                                     "next query %ds", log_sockaddr(
 208                                     (struct sockaddr *)&p->addr->ss), timeout);
 209                                 if (p->trustlevel >= TRUSTLEVEL_BADPEER &&
 210                                     (p->trustlevel /= 2) < TRUSTLEVEL_BADPEER)
 211                                         log_info("peer %s now invalid",
 212                                             log_sockaddr(
 213                                             (struct sockaddr *)&p->addr->ss));
 214                                 client_nextaddr(p);
 215                                 set_next(p, timeout);
 216                         }
 217
 218                         if (p->state == STATE_QUERY_SENT) {
 219                                 pfd[i].fd = p->query->fd;
 220                                 pfd[i].events = POLLIN;
 221                                 idx2peer[i - idx_peers] = p;
 222                                 i++;
 223                         }
 224                 }
 225
 226                 if (sent_cnt == 0 && conf->settime)
 227                         priv_settime(0);        /* no good peers, don't wait */
 228
 229                 if (ibuf_main->w.queued > 0)
 230                         pfd[PFD_PIPE_MAIN].events |= POLLOUT;
 231
 232                 timeout = nextaction - time(NULL);
 233                 if (timeout < 0)
 234                         timeout = 0;
 235
 236                 if ((nfds = poll(pfd, i, timeout * 1000)) == -1)
 237                         if (errno != EINTR) {
 238                                 log_warn("poll error");
 239                                 ntp_quit = 1;
 240                         }
 241
 242                 if (nfds > 0 && (pfd[PFD_PIPE_MAIN].revents & POLLOUT))
 243                         if (msgbuf_write(&ibuf_main->w) < 0) {
 244                                 log_warn("pipe write error (to parent)");
 245                                 ntp_quit = 1;
 246                         }
 247
 248                 if (nfds > 0 && pfd[PFD_PIPE_MAIN].revents & (POLLIN|POLLERR)) {
 249                         nfds--;
 250                         if (ntp_dispatch_imsg() == -1)
 251                                 ntp_quit = 1;
 252                 }
 253
 254                 for (j = 1; nfds > 0 && j < idx_peers; j++)
 255                         if (pfd[j].revents & (POLLIN|POLLERR)) {
 256                                 nfds--;
 257                                 if (server_dispatch(pfd[j].fd, conf) == -1)
 258                                         ntp_quit = 1;
 259                         }
 260
 261                 for (; nfds > 0 && j < i; j++)
 262                         if (pfd[j].revents & (POLLIN|POLLERR)) {
 263                                 nfds--;
 264                                 if (client_dispatch(idx2peer[j - idx_peers],
 265                                     conf->settime) == -1)
 266                                         ntp_quit = 1;
 267                         }
 268         }
 269
 270         msgbuf_write(&ibuf_main->w);
 271         msgbuf_clear(&ibuf_main->w);
 272         free(ibuf_main);
 273
 274         log_info("ntp engine exiting");
 275         _exit(0);
 276 }
 277
 278 int
 279 ntp_dispatch_imsg(void)
 280 {
 281         struct imsg              imsg;
 282         int                      n;
 283         struct ntp_peer         *peer, *npeer;
 284         u_int16_t                dlen;
 285         u_char                  *p;
 286         struct ntp_addr         *h;
 287
 288         if ((n = imsg_read(ibuf_main)) == -1)
 289                 return (-1);
 290
 291         if (n == 0) {   /* connection closed */
 292                 log_warnx("ntp_dispatch_imsg in ntp engine: pipe closed");
 293                 return (-1);
 294         }
 295
 296         for (;;) {
 297                 if ((n = imsg_get(ibuf_main, &imsg)) == -1)
 298                         return (-1);
 299
 300                 if (n == 0)
 301                         break;
 302
 303                 switch (imsg.hdr.type) {
 304                 case IMSG_HOST_DNS:
 305                         TAILQ_FOREACH(peer, &conf->ntp_peers, entry)
 306                                 if (peer->id == imsg.hdr.peerid)
 307                                         break;
 308                         if (peer == NULL) {
 309                                 log_warnx("IMSG_HOST_DNS with invalid peerID");
 310                                 break;
 311                         }
 312                         if (peer->addr != NULL) {
 313                                 log_warnx("IMSG_HOST_DNS but addr != NULL!");
 314                                 break;
 315                         }
 316                         dlen = imsg.hdr.len - IMSG_HEADER_SIZE;
 317                         p = (u_char *)imsg.data;
 318                         while (dlen >= sizeof(struct sockaddr_storage)) {
 319                                 if ((h = calloc(1, sizeof(struct ntp_addr))) ==
 320                                     NULL)
 321                                         fatal(NULL);
 322                                 memcpy(&h->ss, p, sizeof(h->ss));
 323                                 p += sizeof(h->ss);
 324                                 dlen -= sizeof(h->ss);
 325                                 if (peer->addr_head.pool) {
 326                                         npeer = new_peer();
 327                                         h->next = NULL;
 328                                         npeer->addr = h;
 329                                         npeer->addr_head.a = h;
 330                                         client_peer_init(npeer);
 331                                         peer_add(npeer);
 332                                 } else {
 333                                         h->next = peer->addr;
 334                                         peer->addr = h;
 335                                         peer->addr_head.a = peer->addr;
 336                                 }
 337                         }
 338                         if (dlen != 0)
 339                                 fatal("IMSG_HOST_DNS: dlen != 0");
 340                         if (peer->addr_head.pool)
 341                                 peer_remove(peer);
 342                         else
 343                                 client_addr_init(peer);
 344                         break;
 345                 default:
 346                         break;
 347                 }
 348                 imsg_free(&imsg);
 349         }
 350         return (0);
 351 }
 352
 353 void
 354 peer_add(struct ntp_peer *p)
 355 {
 356         TAILQ_INSERT_TAIL(&conf->ntp_peers, p, entry);
 357         peer_cnt++;
 358 }
 359
 360 void
 361 peer_remove(struct ntp_peer *p)
 362 {
 363         TAILQ_REMOVE(&conf->ntp_peers, p, entry);
 364         free(p);
 365         peer_cnt--;
 366 }
 367
 368 void
 369 priv_adjtime(void)
 370 {
 371         struct ntp_peer  *p;
 372         int               offset_cnt = 0, i = 0;
 373         struct ntp_peer **peers;
 374         double            offset_median;
 375
 376         TAILQ_FOREACH(p, &conf->ntp_peers, entry) {
 377                 if (p->trustlevel < TRUSTLEVEL_BADPEER)
 378                         continue;
 379                 if (!p->update.good)
 380                         return;
 381                 offset_cnt++;
 382         }
 383
 384         if ((peers = calloc(offset_cnt, sizeof(struct ntp_peer *))) == NULL)
 385                 fatal("calloc ntp_adjtime");
 386
 387         TAILQ_FOREACH(p, &conf->ntp_peers, entry) {
 388                 if (p->trustlevel < TRUSTLEVEL_BADPEER)
 389                         continue;
 390                 peers[i++] = p;
 391         }
 392
 393         qsort(peers, offset_cnt, sizeof(struct ntp_peer *), offset_compare);
 394
 395         if (offset_cnt > 0) {
 396                 if (offset_cnt > 1 && offset_cnt % 2 == 0) {
 397                         offset_median =
 398                             (peers[offset_cnt / 2 - 1]->update.offset +
 399                             peers[offset_cnt / 2]->update.offset) / 2;
 400                         conf->status.rootdelay =
 401                             (peers[offset_cnt / 2 - 1]->update.delay +
 402                             peers[offset_cnt / 2]->update.delay) / 2;
 403                         conf->status.stratum = MAX(
 404                             peers[offset_cnt / 2 - 1]->update.status.stratum,
 405                             peers[offset_cnt / 2]->update.status.stratum);
 406                 } else {
 407                         offset_median = peers[offset_cnt / 2]->update.offset;
 408                         conf->status.rootdelay =
 409                             peers[offset_cnt / 2]->update.delay;
 410                         conf->status.stratum =
 411                             peers[offset_cnt / 2]->update.status.stratum;
 412                 }
 413
 414                 imsg_compose(ibuf_main, IMSG_ADJTIME, 0, 0,
 415                     &offset_median, sizeof(offset_median));
 416
 417                 conf->status.reftime = gettime();
 418                 conf->status.leap = LI_NOWARNING;
 419                 conf->status.stratum++; /* one more than selected peer */
 420                 update_scale(offset_median);
 421
 422                 if (peers[offset_cnt / 2]->addr->ss.ss_family == AF_INET)
 423                         conf->status.refid = ((struct sockaddr_in *)
 424                             &peers[offset_cnt / 2]->addr->ss)->sin_addr.s_addr;
 425         }
 426
 427         free(peers);
 428
 429         TAILQ_FOREACH(p, &conf->ntp_peers, entry)
 430                 p->update.good = 0;
 431 }
 432
 433 int
 434 offset_compare(const void *aa, const void *bb)
 435 {
 436         const struct ntp_peer * const *a;
 437         const struct ntp_peer * const *b;
 438
 439         a = aa;
 440         b = bb;
 441
 442         if ((*a)->update.offset < (*b)->update.offset)
 443                 return (-1);
 444         else if ((*a)->update.offset > (*b)->update.offset)
 445                 return (1);
 446         else
 447                 return (0);
 448 }
 449
 450 void
 451 priv_settime(double offset)
 452 {
 453         imsg_compose(ibuf_main, IMSG_SETTIME, 0, 0, &offset, sizeof(offset));
 454         conf->settime = 0;
 455 }
 456
 457 void
 458 priv_host_dns(char *name, u_int32_t peerid)
 459 {
 460         u_int16_t       dlen;
 461
 462         dlen = strlen(name) + 1;
 463         imsg_compose(ibuf_main, IMSG_HOST_DNS, peerid, 0, name, dlen);
 464 }
 465
 466 void
 467 update_scale(double offset)
 468 {
 469         if (offset < 0)
 470                 offset = -offset;
 471
 472         if (offset > QSCALE_OFF_MAX)
 473                 conf->scale = 1;
 474         else if (offset < QSCALE_OFF_MIN)
 475                 conf->scale = QSCALE_OFF_MAX / QSCALE_OFF_MIN;
 476         else
 477                 conf->scale = QSCALE_OFF_MAX / offset;
 478 }
 479
 480 time_t
 481 scale_interval(time_t requested)
 482 {
 483         time_t interval, r;
 484
 485         interval = requested * conf->scale;
 486         r = arc4random() % MAX(5, interval / 10);
 487         return (interval + r);
 488 }
 489
 490 time_t
 491 error_interval(void)
 492 {
 493         time_t interval, r;
 494
 495         interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN;
 496         r = arc4random() % (interval / 10);
 497         return (interval + r);
 498 }
 499