1 /* 2 * This module determines the type of socket (datagram, stream), the client 3 * socket address and port, the server socket address and port. In addition, 4 * it provides methods to map a transport address to a printable host name 5 * or address. Socket address information results are in static memory. 6 * 7 * The result from the hostname lookup method is STRING_PARANOID when a host 8 * pretends to have someone elses name, or when a host name is available but 9 * could not be verified. 10 * 11 * When lookup or conversion fails the result is set to STRING_UNKNOWN. 12 * 13 * Diagnostics are reported through syslog(3). 14 * 15 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. 16 * 17 * $FreeBSD$ 18 */ 19 20 #ifndef lint 21 static char sccsid[] = "@(#) socket.c 1.15 97/03/21 19:27:24"; 22 #endif 23 24 /* System libraries. */ 25 26 #include <sys/types.h> 27 #include <sys/param.h> 28 #include <sys/socket.h> 29 #include <netinet/in.h> 30 #include <netdb.h> 31 #include <stdio.h> 32 #include <syslog.h> 33 #include <string.h> 34 35 #ifdef INET6 36 #ifndef NI_WITHSCOPEID 37 #define NI_WITHSCOPEID 0 38 #endif 39 #else 40 extern char *inet_ntoa(); 41 #endif 42 43 /* Local stuff. */ 44 45 #include "tcpd.h" 46 47 /* Forward declarations. */ 48 49 static void sock_sink(); 50 51 #ifdef APPEND_DOT 52 53 /* 54 * Speed up DNS lookups by terminating the host name with a dot. Should be 55 * done with care. The speedup can give problems with lookups from sources 56 * that lack DNS-style trailing dot magic, such as local files or NIS maps. 57 */ 58 59 static struct hostent *gethostbyname_dot(name) 60 char *name; 61 { 62 char dot_name[MAXHOSTNAMELEN + 1]; 63 64 /* 65 * Don't append dots to unqualified names. Such names are likely to come 66 * from local hosts files or from NIS. 67 */ 68 69 if (strchr(name, '.') == 0 || strlen(name) >= MAXHOSTNAMELEN - 1) { 70 return (gethostbyname(name)); 71 } else { 72 sprintf(dot_name, "%s.", name); 73 return (gethostbyname(dot_name)); 74 } 75 } 76 77 #define gethostbyname gethostbyname_dot 78 #endif 79 80 /* sock_host - look up endpoint addresses and install conversion methods */ 81 82 void sock_host(request) 83 struct request_info *request; 84 { 85 #ifdef INET6 86 static struct sockaddr_storage client; 87 static struct sockaddr_storage server; 88 #else 89 static struct sockaddr_in client; 90 static struct sockaddr_in server; 91 #endif 92 int len; 93 char buf[BUFSIZ]; 94 int fd = request->fd; 95 96 sock_methods(request); 97 98 /* 99 * Look up the client host address. Hal R. Brand <BRAND@addvax.llnl.gov> 100 * suggested how to get the client host info in case of UDP connections: 101 * peek at the first message without actually looking at its contents. We 102 * really should verify that client.sin_family gets the value AF_INET, 103 * but this program has already caused too much grief on systems with 104 * broken library code. 105 */ 106 107 len = sizeof(client); 108 if (getpeername(fd, (struct sockaddr *) & client, &len) < 0) { 109 request->sink = sock_sink; 110 len = sizeof(client); 111 if (recvfrom(fd, buf, sizeof(buf), MSG_PEEK, 112 (struct sockaddr *) & client, &len) < 0) { 113 tcpd_warn("can't get client address: %m"); 114 return; /* give up */ 115 } 116 #ifdef really_paranoid 117 memset(buf, 0 sizeof(buf)); 118 #endif 119 } 120 #ifdef INET6 121 request->client->sin = (struct sockaddr *)&client; 122 #else 123 request->client->sin = &client; 124 #endif 125 126 /* 127 * Determine the server binding. This is used for client username 128 * lookups, and for access control rules that trigger on the server 129 * address or name. 130 */ 131 132 len = sizeof(server); 133 if (getsockname(fd, (struct sockaddr *) & server, &len) < 0) { 134 tcpd_warn("getsockname: %m"); 135 return; 136 } 137 #ifdef INET6 138 request->server->sin = (struct sockaddr *)&server; 139 #else 140 request->server->sin = &server; 141 #endif 142 } 143 144 /* sock_hostaddr - map endpoint address to printable form */ 145 146 void sock_hostaddr(host) 147 struct host_info *host; 148 { 149 #ifdef INET6 150 struct sockaddr *sin = host->sin; 151 int salen; 152 153 if (!sin) 154 return; 155 #ifdef SIN6_LEN 156 salen = sin->sa_len; 157 #else 158 salen = (sin->sa_family == AF_INET) ? sizeof(struct sockaddr_in) 159 : sizeof(struct sockaddr_in6); 160 #endif 161 getnameinfo(sin, salen, host->addr, sizeof(host->addr), 162 NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID); 163 #else 164 struct sockaddr_in *sin = host->sin; 165 166 if (sin != 0) 167 STRN_CPY(host->addr, inet_ntoa(sin->sin_addr), sizeof(host->addr)); 168 #endif 169 } 170 171 /* sock_hostname - map endpoint address to host name */ 172 173 void sock_hostname(host) 174 struct host_info *host; 175 { 176 #ifdef INET6 177 struct sockaddr *sin = host->sin; 178 struct sockaddr_in sin4; 179 struct addrinfo hints, *res, *res0 = NULL; 180 int salen, alen, err = 1; 181 char *ap = NULL, *rap, hname[NI_MAXHOST]; 182 183 if (sin != NULL) { 184 if (sin->sa_family == AF_INET6) { 185 struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sin; 186 187 if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) { 188 memset(&sin4, 0, sizeof(sin4)); 189 #ifdef SIN6_LEN 190 sin4.sin_len = sizeof(sin4); 191 #endif 192 sin4.sin_family = AF_INET; 193 sin4.sin_port = sin6->sin6_port; 194 sin4.sin_addr.s_addr = *(u_int32_t *)&sin6->sin6_addr.s6_addr[12]; 195 sin = (struct sockaddr *)&sin4; 196 } 197 } 198 switch (sin->sa_family) { 199 case AF_INET: 200 ap = (char *)&((struct sockaddr_in *)sin)->sin_addr; 201 alen = sizeof(struct in_addr); 202 salen = sizeof(struct sockaddr_in); 203 break; 204 case AF_INET6: 205 ap = (char *)&((struct sockaddr_in6 *)sin)->sin6_addr; 206 alen = sizeof(struct in6_addr); 207 salen = sizeof(struct sockaddr_in6); 208 break; 209 default: 210 break; 211 } 212 if (ap) 213 err = getnameinfo(sin, salen, hname, sizeof(hname), 214 NULL, 0, NI_WITHSCOPEID | NI_NAMEREQD); 215 } 216 if (!err) { 217 218 STRN_CPY(host->name, hname, sizeof(host->name)); 219 220 /* reject numeric addresses */ 221 memset(&hints, 0, sizeof(hints)); 222 hints.ai_family = sin->sa_family; 223 hints.ai_socktype = SOCK_STREAM; 224 hints.ai_flags = AI_PASSIVE | AI_CANONNAME | AI_NUMERICHOST; 225 if ((err = getaddrinfo(host->name, NULL, &hints, &res0)) == 0) { 226 freeaddrinfo(res0); 227 tcpd_warn("host name/name mismatch: " 228 "reverse lookup results in non-FQDN %s", 229 host->name); 230 strcpy(host->name, paranoid); /* name is bad, clobber it */ 231 } 232 err = !err; 233 } 234 if (!err) { 235 /* we are now sure that this is non-numeric */ 236 237 /* 238 * Verify that the address is a member of the address list returned 239 * by gethostbyname(hostname). 240 * 241 * Verify also that gethostbyaddr() and gethostbyname() return the same 242 * hostname, or rshd and rlogind may still end up being spoofed. 243 * 244 * On some sites, gethostbyname("localhost") returns "localhost.domain". 245 * This is a DNS artefact. We treat it as a special case. When we 246 * can't believe the address list from gethostbyname("localhost") 247 * we're in big trouble anyway. 248 */ 249 250 memset(&hints, 0, sizeof(hints)); 251 hints.ai_family = sin->sa_family; 252 hints.ai_socktype = SOCK_STREAM; 253 hints.ai_flags = AI_PASSIVE | AI_CANONNAME; 254 if (getaddrinfo(host->name, NULL, &hints, &res0) != 0) { 255 256 /* 257 * Unable to verify that the host name matches the address. This 258 * may be a transient problem or a botched name server setup. 259 */ 260 261 tcpd_warn("can't verify hostname: getaddrinfo(%s, %s) failed", 262 host->name, 263 (sin->sa_family == AF_INET) ? "AF_INET" : "AF_INET6"); 264 265 } else if ((res0->ai_canonname == NULL 266 || STR_NE(host->name, res0->ai_canonname)) 267 && STR_NE(host->name, "localhost")) { 268 269 /* 270 * The gethostbyaddr() and gethostbyname() calls did not return 271 * the same hostname. This could be a nameserver configuration 272 * problem. It could also be that someone is trying to spoof us. 273 */ 274 275 tcpd_warn("host name/name mismatch: %s != %.*s", 276 host->name, STRING_LENGTH, 277 (res0->ai_canonname == NULL) ? "" : res0->ai_canonname); 278 279 } else { 280 281 /* 282 * The address should be a member of the address list returned by 283 * gethostbyname(). We should first verify that the h_addrtype 284 * field is AF_INET, but this program has already caused too much 285 * grief on systems with broken library code. 286 */ 287 288 for (res = res0; res; res = res->ai_next) { 289 if (res->ai_family != sin->sa_family) 290 continue; 291 switch (res->ai_family) { 292 case AF_INET: 293 rap = (char *)&((struct sockaddr_in *)res->ai_addr)->sin_addr; 294 break; 295 case AF_INET6: 296 /* need to check scope_id */ 297 if (((struct sockaddr_in6 *)sin)->sin6_scope_id != 298 ((struct sockaddr_in6 *)res->ai_addr)->sin6_scope_id) { 299 continue; 300 } 301 rap = (char *)&((struct sockaddr_in6 *)res->ai_addr)->sin6_addr; 302 break; 303 default: 304 continue; 305 } 306 if (memcmp(rap, ap, alen) == 0) { 307 freeaddrinfo(res0); 308 return; /* name is good, keep it */ 309 } 310 } 311 312 /* 313 * The host name does not map to the initial address. Perhaps 314 * someone has messed up. Perhaps someone compromised a name 315 * server. 316 */ 317 318 getnameinfo(sin, salen, hname, sizeof(hname), 319 NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID); 320 tcpd_warn("host name/address mismatch: %s != %.*s", 321 hname, STRING_LENGTH, 322 (res0->ai_canonname == NULL) ? "" : res0->ai_canonname); 323 } 324 strcpy(host->name, paranoid); /* name is bad, clobber it */ 325 if (res0) 326 freeaddrinfo(res0); 327 } 328 #else /* INET6 */ 329 struct sockaddr_in *sin = host->sin; 330 struct hostent *hp; 331 int i; 332 333 /* 334 * On some systems, for example Solaris 2.3, gethostbyaddr(0.0.0.0) does 335 * not fail. Instead it returns "INADDR_ANY". Unfortunately, this does 336 * not work the other way around: gethostbyname("INADDR_ANY") fails. We 337 * have to special-case 0.0.0.0, in order to avoid false alerts from the 338 * host name/address checking code below. 339 */ 340 if (sin != 0 && sin->sin_addr.s_addr != 0 341 && (hp = gethostbyaddr((char *) &(sin->sin_addr), 342 sizeof(sin->sin_addr), AF_INET)) != 0) { 343 344 STRN_CPY(host->name, hp->h_name, sizeof(host->name)); 345 346 /* 347 * Verify that the address is a member of the address list returned 348 * by gethostbyname(hostname). 349 * 350 * Verify also that gethostbyaddr() and gethostbyname() return the same 351 * hostname, or rshd and rlogind may still end up being spoofed. 352 * 353 * On some sites, gethostbyname("localhost") returns "localhost.domain". 354 * This is a DNS artefact. We treat it as a special case. When we 355 * can't believe the address list from gethostbyname("localhost") 356 * we're in big trouble anyway. 357 */ 358 359 if ((hp = gethostbyname(host->name)) == 0) { 360 361 /* 362 * Unable to verify that the host name matches the address. This 363 * may be a transient problem or a botched name server setup. 364 */ 365 366 tcpd_warn("can't verify hostname: gethostbyname(%s) failed", 367 host->name); 368 369 } else if (STR_NE(host->name, hp->h_name) 370 && STR_NE(host->name, "localhost")) { 371 372 /* 373 * The gethostbyaddr() and gethostbyname() calls did not return 374 * the same hostname. This could be a nameserver configuration 375 * problem. It could also be that someone is trying to spoof us. 376 */ 377 378 tcpd_warn("host name/name mismatch: %s != %.*s", 379 host->name, STRING_LENGTH, hp->h_name); 380 381 } else { 382 383 /* 384 * The address should be a member of the address list returned by 385 * gethostbyname(). We should first verify that the h_addrtype 386 * field is AF_INET, but this program has already caused too much 387 * grief on systems with broken library code. 388 */ 389 390 for (i = 0; hp->h_addr_list[i]; i++) { 391 if (memcmp(hp->h_addr_list[i], 392 (char *) &sin->sin_addr, 393 sizeof(sin->sin_addr)) == 0) 394 return; /* name is good, keep it */ 395 } 396 397 /* 398 * The host name does not map to the initial address. Perhaps 399 * someone has messed up. Perhaps someone compromised a name 400 * server. 401 */ 402 403 tcpd_warn("host name/address mismatch: %s != %.*s", 404 inet_ntoa(sin->sin_addr), STRING_LENGTH, hp->h_name); 405 } 406 strcpy(host->name, paranoid); /* name is bad, clobber it */ 407 } 408 #endif /* INET6 */ 409 } 410 411 /* sock_sink - absorb unreceived IP datagram */ 412 413 static void sock_sink(fd) 414 int fd; 415 { 416 char buf[BUFSIZ]; 417 #ifdef INET6 418 struct sockaddr_storage sin; 419 #else 420 struct sockaddr_in sin; 421 #endif 422 int size = sizeof(sin); 423 424 /* 425 * Eat up the not-yet received datagram. Some systems insist on a 426 * non-zero source address argument in the recvfrom() call below. 427 */ 428 429 (void) recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *) & sin, &size); 430 } 431