1 /* $OpenBSD: client.c,v 1.103 2015/10/23 14:52:20 phessler 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/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; 140 141 if ((p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM, 142 0)) == -1) 143 fatal("client_query socket"); 144 145 if (connect(p->query->fd, sa, SA_LEN(sa)) == -1) { 146 if (errno == ECONNREFUSED || errno == ENETUNREACH || 147 errno == EHOSTUNREACH || errno == EADDRNOTAVAIL) { 148 client_nextaddr(p); 149 set_next(p, MAXIMUM(SETTIME_TIMEOUT, 150 scale_interval(INTERVAL_QUERY_AGGRESSIVE))); 151 return (-1); 152 } else 153 fatal("client_query connect"); 154 } 155 val = IPTOS_LOWDELAY; 156 if (p->addr->ss.ss_family == AF_INET && setsockopt(p->query->fd, 157 IPPROTO_IP, IP_TOS, &val, sizeof(val)) == -1) 158 log_warn("setsockopt IPTOS_LOWDELAY"); 159 val = 1; 160 if (setsockopt(p->query->fd, SOL_SOCKET, SO_TIMESTAMP, 161 &val, sizeof(val)) == -1) 162 fatal("setsockopt SO_TIMESTAMP"); 163 } 164 165 /* 166 * Send out a random 64-bit number as our transmit time. The NTP 167 * server will copy said number into the originate field on the 168 * response that it sends us. This is totally legal per the SNTP spec. 169 * 170 * The impact of this is two fold: we no longer send out the current 171 * system time for the world to see (which may aid an attacker), and 172 * it gives us a (not very secure) way of knowing that we're not 173 * getting spoofed by an attacker that can't capture our traffic 174 * but can spoof packets from the NTP server we're communicating with. 175 * 176 * Save the real transmit timestamp locally. 177 */ 178 179 p->query->msg.xmttime.int_partl = arc4random(); 180 p->query->msg.xmttime.fractionl = arc4random(); 181 p->query->xmttime = gettime_corrected(); 182 183 if (ntp_sendmsg(p->query->fd, NULL, &p->query->msg) == -1) { 184 p->senderrors++; 185 set_next(p, INTERVAL_QUERY_PATHETIC); 186 p->trustlevel = TRUSTLEVEL_PATHETIC; 187 return (-1); 188 } 189 190 p->senderrors = 0; 191 p->state = STATE_QUERY_SENT; 192 set_deadline(p, QUERYTIME_MAX); 193 194 return (0); 195 } 196 197 int 198 client_dispatch(struct ntp_peer *p, u_int8_t settime) 199 { 200 struct ntp_msg msg; 201 struct msghdr somsg; 202 struct iovec iov[1]; 203 struct timeval tv; 204 char buf[NTP_MSGSIZE]; 205 union { 206 struct cmsghdr hdr; 207 char buf[CMSG_SPACE(sizeof(tv))]; 208 } cmsgbuf; 209 struct cmsghdr *cmsg; 210 ssize_t size; 211 double T1, T2, T3, T4; 212 time_t interval; 213 214 memset(&somsg, 0, sizeof(somsg)); 215 iov[0].iov_base = buf; 216 iov[0].iov_len = sizeof(buf); 217 somsg.msg_iov = iov; 218 somsg.msg_iovlen = 1; 219 somsg.msg_control = cmsgbuf.buf; 220 somsg.msg_controllen = sizeof(cmsgbuf.buf); 221 222 T4 = getoffset(); 223 if ((size = recvmsg(p->query->fd, &somsg, 0)) == -1) { 224 if (errno == EHOSTUNREACH || errno == EHOSTDOWN || 225 errno == ENETUNREACH || errno == ENETDOWN || 226 errno == ECONNREFUSED || errno == EADDRNOTAVAIL || 227 errno == ENOPROTOOPT || errno == ENOENT) { 228 client_log_error(p, "recvmsg", errno); 229 set_next(p, error_interval()); 230 return (0); 231 } else 232 fatal("recvfrom"); 233 } 234 235 if (somsg.msg_flags & MSG_TRUNC) { 236 client_log_error(p, "recvmsg packet", EMSGSIZE); 237 set_next(p, error_interval()); 238 return (0); 239 } 240 241 if (somsg.msg_flags & MSG_CTRUNC) { 242 client_log_error(p, "recvmsg control data", E2BIG); 243 set_next(p, error_interval()); 244 return (0); 245 } 246 247 for (cmsg = CMSG_FIRSTHDR(&somsg); cmsg != NULL; 248 cmsg = CMSG_NXTHDR(&somsg, cmsg)) { 249 if (cmsg->cmsg_level == SOL_SOCKET && 250 cmsg->cmsg_type == SCM_TIMESTAMP) { 251 memcpy(&tv, CMSG_DATA(cmsg), sizeof(tv)); 252 T4 += gettime_from_timeval(&tv); 253 break; 254 } 255 } 256 257 if (T4 < JAN_1970) { 258 client_log_error(p, "recvmsg control format", EBADF); 259 set_next(p, error_interval()); 260 return (0); 261 } 262 263 ntp_getmsg((struct sockaddr *)&p->addr->ss, buf, size, &msg); 264 265 if (msg.orgtime.int_partl != p->query->msg.xmttime.int_partl || 266 msg.orgtime.fractionl != p->query->msg.xmttime.fractionl) 267 return (0); 268 269 if ((msg.status & LI_ALARM) == LI_ALARM || msg.stratum == 0 || 270 msg.stratum > NTP_MAXSTRATUM) { 271 char s[16]; 272 273 if ((msg.status & LI_ALARM) == LI_ALARM) { 274 strlcpy(s, "alarm", sizeof(s)); 275 } else if (msg.stratum == 0) { 276 /* Kiss-o'-Death (KoD) packet */ 277 strlcpy(s, "KoD", sizeof(s)); 278 } else if (msg.stratum > NTP_MAXSTRATUM) { 279 snprintf(s, sizeof(s), "stratum %d", msg.stratum); 280 } 281 interval = error_interval(); 282 set_next(p, interval); 283 log_info("reply from %s: not synced (%s), next query %llds", 284 log_sockaddr((struct sockaddr *)&p->addr->ss), s, 285 (long long)interval); 286 return (0); 287 } 288 289 /* 290 * From RFC 2030 (with a correction to the delay math): 291 * 292 * Timestamp Name ID When Generated 293 * ------------------------------------------------------------ 294 * Originate Timestamp T1 time request sent by client 295 * Receive Timestamp T2 time request received by server 296 * Transmit Timestamp T3 time reply sent by server 297 * Destination Timestamp T4 time reply received by client 298 * 299 * The roundtrip delay d and local clock offset t are defined as 300 * 301 * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2. 302 */ 303 304 T1 = p->query->xmttime; 305 T2 = lfp_to_d(msg.rectime); 306 T3 = lfp_to_d(msg.xmttime); 307 308 /* 309 * XXX workaround: time_t / tv_sec must never wrap. 310 * around 2020 we will need a solution (64bit time_t / tv_sec). 311 * consider every answer with a timestamp beyond january 2030 bogus. 312 */ 313 if (T2 > JAN_2030 || T3 > JAN_2030) { 314 set_next(p, error_interval()); 315 return (0); 316 } 317 318 /* Detect liars */ 319 if (conf->constraint_median != 0 && 320 (constraint_check(T2) != 0 || constraint_check(T3) != 0)) { 321 log_info("reply from %s: constraint check failed", 322 log_sockaddr((struct sockaddr *)&p->addr->ss)); 323 set_next(p, error_interval()); 324 return (0); 325 } 326 327 p->reply[p->shift].offset = ((T2 - T1) + (T3 - T4)) / 2; 328 p->reply[p->shift].delay = (T4 - T1) - (T3 - T2); 329 p->reply[p->shift].status.stratum = msg.stratum; 330 if (p->reply[p->shift].delay < 0) { 331 interval = error_interval(); 332 set_next(p, interval); 333 log_info("reply from %s: negative delay %fs, " 334 "next query %llds", 335 log_sockaddr((struct sockaddr *)&p->addr->ss), 336 p->reply[p->shift].delay, (long long)interval); 337 return (0); 338 } 339 p->reply[p->shift].error = (T2 - T1) - (T3 - T4); 340 p->reply[p->shift].rcvd = getmonotime(); 341 p->reply[p->shift].good = 1; 342 343 p->reply[p->shift].status.leap = (msg.status & LIMASK); 344 p->reply[p->shift].status.precision = msg.precision; 345 p->reply[p->shift].status.rootdelay = sfp_to_d(msg.rootdelay); 346 p->reply[p->shift].status.rootdispersion = sfp_to_d(msg.dispersion); 347 p->reply[p->shift].status.refid = msg.refid; 348 p->reply[p->shift].status.reftime = lfp_to_d(msg.reftime); 349 p->reply[p->shift].status.poll = msg.ppoll; 350 351 if (p->addr->ss.ss_family == AF_INET) { 352 p->reply[p->shift].status.send_refid = 353 ((struct sockaddr_in *)&p->addr->ss)->sin_addr.s_addr; 354 } else if (p->addr->ss.ss_family == AF_INET6) { 355 MD5_CTX context; 356 u_int8_t digest[MD5_DIGEST_LENGTH]; 357 358 MD5Init(&context); 359 MD5Update(&context, ((struct sockaddr_in6 *)&p->addr->ss)-> 360 sin6_addr.s6_addr, sizeof(struct in6_addr)); 361 MD5Final(digest, &context); 362 memcpy((char *)&p->reply[p->shift].status.send_refid, digest, 363 sizeof(u_int32_t)); 364 } else 365 p->reply[p->shift].status.send_refid = msg.xmttime.fractionl; 366 367 if (p->trustlevel < TRUSTLEVEL_PATHETIC) 368 interval = scale_interval(INTERVAL_QUERY_PATHETIC); 369 else if (p->trustlevel < TRUSTLEVEL_AGGRESSIVE) 370 interval = scale_interval(INTERVAL_QUERY_AGGRESSIVE); 371 else 372 interval = scale_interval(INTERVAL_QUERY_NORMAL); 373 374 set_next(p, interval); 375 p->state = STATE_REPLY_RECEIVED; 376 377 /* every received reply which we do not discard increases trust */ 378 if (p->trustlevel < TRUSTLEVEL_MAX) { 379 if (p->trustlevel < TRUSTLEVEL_BADPEER && 380 p->trustlevel + 1 >= TRUSTLEVEL_BADPEER) 381 log_info("peer %s now valid", 382 log_sockaddr((struct sockaddr *)&p->addr->ss)); 383 p->trustlevel++; 384 } 385 386 log_debug("reply from %s: offset %f delay %f, " 387 "next query %llds", 388 log_sockaddr((struct sockaddr *)&p->addr->ss), 389 p->reply[p->shift].offset, p->reply[p->shift].delay, 390 (long long)interval); 391 392 client_update(p); 393 if (settime) 394 priv_settime(p->reply[p->shift].offset); 395 396 if (++p->shift >= OFFSET_ARRAY_SIZE) 397 p->shift = 0; 398 399 return (0); 400 } 401 402 int 403 client_update(struct ntp_peer *p) 404 { 405 int i, best = 0, good = 0; 406 407 /* 408 * clock filter 409 * find the offset which arrived with the lowest delay 410 * use that as the peer update 411 * invalidate it and all older ones 412 */ 413 414 for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++) 415 if (p->reply[i].good) { 416 good++; 417 best = i; 418 } 419 420 for (; i < OFFSET_ARRAY_SIZE; i++) 421 if (p->reply[i].good) { 422 good++; 423 if (p->reply[i].delay < p->reply[best].delay) 424 best = i; 425 } 426 427 if (good < 8) 428 return (-1); 429 430 memcpy(&p->update, &p->reply[best], sizeof(p->update)); 431 if (priv_adjtime() == 0) { 432 for (i = 0; i < OFFSET_ARRAY_SIZE; i++) 433 if (p->reply[i].rcvd <= p->reply[best].rcvd) 434 p->reply[i].good = 0; 435 } 436 return (0); 437 } 438 439 void 440 client_log_error(struct ntp_peer *peer, const char *operation, int error) 441 { 442 const char *address; 443 444 address = log_sockaddr((struct sockaddr *)&peer->addr->ss); 445 if (peer->lasterror == error) { 446 log_debug("%s %s: %s", operation, address, strerror(error)); 447 return; 448 } 449 peer->lasterror = error; 450 log_warn("%s %s", operation, address); 451 } 452