1 /* $OpenBSD: client.c,v 1.105 2017/05/30 23:30:48 benno 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 USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 #include <sys/types.h> 21 #include <errno.h> 22 #include <md5.h> 23 #include <stdio.h> 24 #include <stdlib.h> 25 #include <string.h> 26 #include <time.h> 27 #include <unistd.h> 28 29 #include "ntpd.h" 30 31 int client_update(struct ntp_peer *); 32 void set_deadline(struct ntp_peer *, time_t); 33 34 void 35 set_next(struct ntp_peer *p, time_t t) 36 { 37 p->next = getmonotime() + t; 38 p->deadline = 0; 39 p->poll = t; 40 } 41 42 void 43 set_deadline(struct ntp_peer *p, time_t t) 44 { 45 p->deadline = getmonotime() + t; 46 p->next = 0; 47 } 48 49 int 50 client_peer_init(struct ntp_peer *p) 51 { 52 if ((p->query = calloc(1, sizeof(struct ntp_query))) == NULL) 53 fatal("client_peer_init calloc"); 54 p->query->fd = -1; 55 p->query->msg.status = MODE_CLIENT | (NTP_VERSION << 3); 56 p->state = STATE_NONE; 57 p->shift = 0; 58 p->trustlevel = TRUSTLEVEL_PATHETIC; 59 p->lasterror = 0; 60 p->senderrors = 0; 61 62 return (client_addr_init(p)); 63 } 64 65 int 66 client_addr_init(struct ntp_peer *p) 67 { 68 struct sockaddr_in *sa_in; 69 struct sockaddr_in6 *sa_in6; 70 struct ntp_addr *h; 71 72 for (h = p->addr; h != NULL; h = h->next) { 73 switch (h->ss.ss_family) { 74 case AF_INET: 75 sa_in = (struct sockaddr_in *)&h->ss; 76 if (ntohs(sa_in->sin_port) == 0) 77 sa_in->sin_port = htons(123); 78 p->state = STATE_DNS_DONE; 79 break; 80 case AF_INET6: 81 sa_in6 = (struct sockaddr_in6 *)&h->ss; 82 if (ntohs(sa_in6->sin6_port) == 0) 83 sa_in6->sin6_port = htons(123); 84 p->state = STATE_DNS_DONE; 85 break; 86 default: 87 fatalx("king bula sez: wrong AF in client_addr_init"); 88 /* NOTREACHED */ 89 } 90 } 91 92 p->query->fd = -1; 93 set_next(p, 0); 94 95 return (0); 96 } 97 98 int 99 client_nextaddr(struct ntp_peer *p) 100 { 101 if (p->query->fd != -1) { 102 close(p->query->fd); 103 p->query->fd = -1; 104 } 105 106 if (p->state == STATE_DNS_INPROGRESS) 107 return (-1); 108 109 if (p->addr_head.a == NULL) { 110 priv_dns(IMSG_HOST_DNS, p->addr_head.name, p->id); 111 p->state = STATE_DNS_INPROGRESS; 112 return (-1); 113 } 114 115 if (p->addr == NULL || (p->addr = p->addr->next) == NULL) 116 p->addr = p->addr_head.a; 117 118 p->shift = 0; 119 p->trustlevel = TRUSTLEVEL_PATHETIC; 120 121 return (0); 122 } 123 124 int 125 client_query(struct ntp_peer *p) 126 { 127 int val; 128 129 if (p->addr == NULL && client_nextaddr(p) == -1) { 130 set_next(p, MAXIMUM(SETTIME_TIMEOUT, 131 scale_interval(INTERVAL_QUERY_AGGRESSIVE))); 132 return (0); 133 } 134 135 if (p->state < STATE_DNS_DONE || p->addr == NULL) 136 return (-1); 137 138 if (p->query->fd == -1) { 139 struct sockaddr *sa = (struct sockaddr *)&p->addr->ss; 140 struct sockaddr *qa4 = (struct sockaddr *)&p->query_addr4; 141 struct sockaddr *qa6 = (struct sockaddr *)&p->query_addr6; 142 143 if ((p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM, 144 0)) == -1) 145 fatal("client_query socket"); 146 147 if (p->addr->ss.ss_family == qa4->sa_family) { 148 if (bind(p->query->fd, qa4, SA_LEN(qa4)) == -1) 149 fatal("couldn't bind to IPv4 query address: %s", 150 log_sockaddr(qa4)); 151 } else if (p->addr->ss.ss_family == qa6->sa_family) { 152 if (bind(p->query->fd, qa6, SA_LEN(qa6)) == -1) 153 fatal("couldn't bind to IPv6 query address: %s", 154 log_sockaddr(qa6)); 155 } 156 157 if (connect(p->query->fd, sa, SA_LEN(sa)) == -1) { 158 if (errno == ECONNREFUSED || errno == ENETUNREACH || 159 errno == EHOSTUNREACH || errno == EADDRNOTAVAIL) { 160 client_nextaddr(p); 161 set_next(p, MAXIMUM(SETTIME_TIMEOUT, 162 scale_interval(INTERVAL_QUERY_AGGRESSIVE))); 163 return (-1); 164 } else 165 fatal("client_query connect"); 166 } 167 val = IPTOS_LOWDELAY; 168 if (p->addr->ss.ss_family == AF_INET && setsockopt(p->query->fd, 169 IPPROTO_IP, IP_TOS, &val, sizeof(val)) == -1) 170 log_warn("setsockopt IPTOS_LOWDELAY"); 171 val = 1; 172 if (setsockopt(p->query->fd, SOL_SOCKET, SO_TIMESTAMP, 173 &val, sizeof(val)) == -1) 174 fatal("setsockopt SO_TIMESTAMP"); 175 } 176 177 /* 178 * Send out a random 64-bit number as our transmit time. The NTP 179 * server will copy said number into the originate field on the 180 * response that it sends us. This is totally legal per the SNTP spec. 181 * 182 * The impact of this is two fold: we no longer send out the current 183 * system time for the world to see (which may aid an attacker), and 184 * it gives us a (not very secure) way of knowing that we're not 185 * getting spoofed by an attacker that can't capture our traffic 186 * but can spoof packets from the NTP server we're communicating with. 187 * 188 * Save the real transmit timestamp locally. 189 */ 190 191 p->query->msg.xmttime.int_partl = arc4random(); 192 p->query->msg.xmttime.fractionl = arc4random(); 193 p->query->xmttime = gettime_corrected(); 194 195 if (ntp_sendmsg(p->query->fd, NULL, &p->query->msg) == -1) { 196 p->senderrors++; 197 set_next(p, INTERVAL_QUERY_PATHETIC); 198 p->trustlevel = TRUSTLEVEL_PATHETIC; 199 return (-1); 200 } 201 202 p->senderrors = 0; 203 p->state = STATE_QUERY_SENT; 204 set_deadline(p, QUERYTIME_MAX); 205 206 return (0); 207 } 208 209 int 210 client_dispatch(struct ntp_peer *p, u_int8_t settime) 211 { 212 struct ntp_msg msg; 213 struct msghdr somsg; 214 struct iovec iov[1]; 215 struct timeval tv; 216 char buf[NTP_MSGSIZE]; 217 union { 218 struct cmsghdr hdr; 219 char buf[CMSG_SPACE(sizeof(tv))]; 220 } cmsgbuf; 221 struct cmsghdr *cmsg; 222 ssize_t size; 223 double T1, T2, T3, T4; 224 time_t interval; 225 226 memset(&somsg, 0, sizeof(somsg)); 227 iov[0].iov_base = buf; 228 iov[0].iov_len = sizeof(buf); 229 somsg.msg_iov = iov; 230 somsg.msg_iovlen = 1; 231 somsg.msg_control = cmsgbuf.buf; 232 somsg.msg_controllen = sizeof(cmsgbuf.buf); 233 234 T4 = getoffset(); 235 if ((size = recvmsg(p->query->fd, &somsg, 0)) == -1) { 236 if (errno == EHOSTUNREACH || errno == EHOSTDOWN || 237 errno == ENETUNREACH || errno == ENETDOWN || 238 errno == ECONNREFUSED || errno == EADDRNOTAVAIL || 239 errno == ENOPROTOOPT || errno == ENOENT) { 240 client_log_error(p, "recvmsg", errno); 241 set_next(p, error_interval()); 242 return (0); 243 } else 244 fatal("recvfrom"); 245 } 246 247 if (somsg.msg_flags & MSG_TRUNC) { 248 client_log_error(p, "recvmsg packet", EMSGSIZE); 249 set_next(p, error_interval()); 250 return (0); 251 } 252 253 if (somsg.msg_flags & MSG_CTRUNC) { 254 client_log_error(p, "recvmsg control data", E2BIG); 255 set_next(p, error_interval()); 256 return (0); 257 } 258 259 for (cmsg = CMSG_FIRSTHDR(&somsg); cmsg != NULL; 260 cmsg = CMSG_NXTHDR(&somsg, cmsg)) { 261 if (cmsg->cmsg_level == SOL_SOCKET && 262 cmsg->cmsg_type == SCM_TIMESTAMP) { 263 memcpy(&tv, CMSG_DATA(cmsg), sizeof(tv)); 264 T4 += gettime_from_timeval(&tv); 265 break; 266 } 267 } 268 269 if (T4 < JAN_1970) { 270 client_log_error(p, "recvmsg control format", EBADF); 271 set_next(p, error_interval()); 272 return (0); 273 } 274 275 ntp_getmsg((struct sockaddr *)&p->addr->ss, buf, size, &msg); 276 277 if (msg.orgtime.int_partl != p->query->msg.xmttime.int_partl || 278 msg.orgtime.fractionl != p->query->msg.xmttime.fractionl) 279 return (0); 280 281 if ((msg.status & LI_ALARM) == LI_ALARM || msg.stratum == 0 || 282 msg.stratum > NTP_MAXSTRATUM) { 283 char s[16]; 284 285 if ((msg.status & LI_ALARM) == LI_ALARM) { 286 strlcpy(s, "alarm", sizeof(s)); 287 } else if (msg.stratum == 0) { 288 /* Kiss-o'-Death (KoD) packet */ 289 strlcpy(s, "KoD", sizeof(s)); 290 } else if (msg.stratum > NTP_MAXSTRATUM) { 291 snprintf(s, sizeof(s), "stratum %d", msg.stratum); 292 } 293 interval = error_interval(); 294 set_next(p, interval); 295 log_info("reply from %s: not synced (%s), next query %llds", 296 log_sockaddr((struct sockaddr *)&p->addr->ss), s, 297 (long long)interval); 298 return (0); 299 } 300 301 /* 302 * From RFC 2030 (with a correction to the delay math): 303 * 304 * Timestamp Name ID When Generated 305 * ------------------------------------------------------------ 306 * Originate Timestamp T1 time request sent by client 307 * Receive Timestamp T2 time request received by server 308 * Transmit Timestamp T3 time reply sent by server 309 * Destination Timestamp T4 time reply received by client 310 * 311 * The roundtrip delay d and local clock offset t are defined as 312 * 313 * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2. 314 */ 315 316 T1 = p->query->xmttime; 317 T2 = lfp_to_d(msg.rectime); 318 T3 = lfp_to_d(msg.xmttime); 319 320 /* 321 * XXX workaround: time_t / tv_sec must never wrap. 322 * around 2020 we will need a solution (64bit time_t / tv_sec). 323 * consider every answer with a timestamp beyond january 2030 bogus. 324 */ 325 if (T2 > JAN_2030 || T3 > JAN_2030) { 326 set_next(p, error_interval()); 327 return (0); 328 } 329 330 /* Detect liars */ 331 if (conf->constraint_median != 0 && 332 (constraint_check(T2) != 0 || constraint_check(T3) != 0)) { 333 log_info("reply from %s: constraint check failed", 334 log_sockaddr((struct sockaddr *)&p->addr->ss)); 335 set_next(p, error_interval()); 336 return (0); 337 } 338 339 p->reply[p->shift].offset = ((T2 - T1) + (T3 - T4)) / 2; 340 p->reply[p->shift].delay = (T4 - T1) - (T3 - T2); 341 p->reply[p->shift].status.stratum = msg.stratum; 342 if (p->reply[p->shift].delay < 0) { 343 interval = error_interval(); 344 set_next(p, interval); 345 log_info("reply from %s: negative delay %fs, " 346 "next query %llds", 347 log_sockaddr((struct sockaddr *)&p->addr->ss), 348 p->reply[p->shift].delay, (long long)interval); 349 return (0); 350 } 351 p->reply[p->shift].error = (T2 - T1) - (T3 - T4); 352 p->reply[p->shift].rcvd = getmonotime(); 353 p->reply[p->shift].good = 1; 354 355 p->reply[p->shift].status.leap = (msg.status & LIMASK); 356 p->reply[p->shift].status.precision = msg.precision; 357 p->reply[p->shift].status.rootdelay = sfp_to_d(msg.rootdelay); 358 p->reply[p->shift].status.rootdispersion = sfp_to_d(msg.dispersion); 359 p->reply[p->shift].status.refid = msg.refid; 360 p->reply[p->shift].status.reftime = lfp_to_d(msg.reftime); 361 p->reply[p->shift].status.poll = msg.ppoll; 362 363 if (p->addr->ss.ss_family == AF_INET) { 364 p->reply[p->shift].status.send_refid = 365 ((struct sockaddr_in *)&p->addr->ss)->sin_addr.s_addr; 366 } else if (p->addr->ss.ss_family == AF_INET6) { 367 MD5_CTX context; 368 u_int8_t digest[MD5_DIGEST_LENGTH]; 369 370 MD5Init(&context); 371 MD5Update(&context, ((struct sockaddr_in6 *)&p->addr->ss)-> 372 sin6_addr.s6_addr, sizeof(struct in6_addr)); 373 MD5Final(digest, &context); 374 memcpy((char *)&p->reply[p->shift].status.send_refid, digest, 375 sizeof(u_int32_t)); 376 } else 377 p->reply[p->shift].status.send_refid = msg.xmttime.fractionl; 378 379 if (p->trustlevel < TRUSTLEVEL_PATHETIC) 380 interval = scale_interval(INTERVAL_QUERY_PATHETIC); 381 else if (p->trustlevel < TRUSTLEVEL_AGGRESSIVE) 382 interval = scale_interval(INTERVAL_QUERY_AGGRESSIVE); 383 else 384 interval = scale_interval(INTERVAL_QUERY_NORMAL); 385 386 set_next(p, interval); 387 p->state = STATE_REPLY_RECEIVED; 388 389 /* every received reply which we do not discard increases trust */ 390 if (p->trustlevel < TRUSTLEVEL_MAX) { 391 if (p->trustlevel < TRUSTLEVEL_BADPEER && 392 p->trustlevel + 1 >= TRUSTLEVEL_BADPEER) 393 log_info("peer %s now valid", 394 log_sockaddr((struct sockaddr *)&p->addr->ss)); 395 p->trustlevel++; 396 } 397 398 log_debug("reply from %s: offset %f delay %f, " 399 "next query %llds", 400 log_sockaddr((struct sockaddr *)&p->addr->ss), 401 p->reply[p->shift].offset, p->reply[p->shift].delay, 402 (long long)interval); 403 404 client_update(p); 405 if (settime) 406 priv_settime(p->reply[p->shift].offset); 407 408 if (++p->shift >= OFFSET_ARRAY_SIZE) 409 p->shift = 0; 410 411 return (0); 412 } 413 414 int 415 client_update(struct ntp_peer *p) 416 { 417 int i, best = 0, good = 0; 418 419 /* 420 * clock filter 421 * find the offset which arrived with the lowest delay 422 * use that as the peer update 423 * invalidate it and all older ones 424 */ 425 426 for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++) 427 if (p->reply[i].good) { 428 good++; 429 best = i; 430 } 431 432 for (; i < OFFSET_ARRAY_SIZE; i++) 433 if (p->reply[i].good) { 434 good++; 435 if (p->reply[i].delay < p->reply[best].delay) 436 best = i; 437 } 438 439 if (good < 8) 440 return (-1); 441 442 memcpy(&p->update, &p->reply[best], sizeof(p->update)); 443 if (priv_adjtime() == 0) { 444 for (i = 0; i < OFFSET_ARRAY_SIZE; i++) 445 if (p->reply[i].rcvd <= p->reply[best].rcvd) 446 p->reply[i].good = 0; 447 } 448 return (0); 449 } 450 451 void 452 client_log_error(struct ntp_peer *peer, const char *operation, int error) 453 { 454 const char *address; 455 456 address = log_sockaddr((struct sockaddr *)&peer->addr->ss); 457 if (peer->lasterror == error) { 458 log_debug("%s %s: %s", operation, address, strerror(error)); 459 return; 460 } 461 peer->lasterror = error; 462 log_warn("%s %s", operation, address); 463 } 464