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f936c5d4 | 1 | /* $OpenBSD: canohost.c,v 1.65 2009/05/27 06:31:25 andreas Exp $ */ |
8efc0c15 | 2 | /* |
5260325f | 3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
5 | * All rights reserved | |
5260325f | 6 | * Functions for returning the canonical host name of the remote site. |
6ae2364d | 7 | * |
bcbf86ec | 8 | * As far as I am concerned, the code I have written for this software |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
5260325f | 13 | */ |
8efc0c15 | 14 | |
15 | #include "includes.h" | |
b6438382 | 16 | |
5b04a8bf | 17 | #include <sys/types.h> |
9794d008 | 18 | #include <sys/socket.h> |
19 | ||
20 | #include <netinet/in.h> | |
c5bca5d4 | 21 | #include <arpa/inet.h> |
9794d008 | 22 | |
b6438382 | 23 | #include <ctype.h> |
028094f4 | 24 | #include <errno.h> |
28cb0a43 | 25 | #include <netdb.h> |
cf851879 | 26 | #include <stdio.h> |
ffa517a8 | 27 | #include <stdlib.h> |
00146caa | 28 | #include <string.h> |
31652869 | 29 | #include <stdarg.h> |
8efc0c15 | 30 | |
8efc0c15 | 31 | #include "xmalloc.h" |
31652869 | 32 | #include "packet.h" |
42f11eb2 | 33 | #include "log.h" |
5ca51e19 | 34 | #include "canohost.h" |
bb4626fe | 35 | #include "misc.h" |
8efc0c15 | 36 | |
396c147e | 37 | static void check_ip_options(int, char *); |
f936c5d4 | 38 | static char *canonical_host_ip = NULL; |
39 | static int cached_port = -1; | |
61e96248 | 40 | |
aa3378df | 41 | /* |
42 | * Return the canonical name of the host at the other end of the socket. The | |
43 | * caller should free the returned string with xfree. | |
44 | */ | |
8efc0c15 | 45 | |
396c147e | 46 | static char * |
ca75d7de | 47 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 48 | { |
48e671d5 | 49 | struct sockaddr_storage from; |
50 | int i; | |
51 | socklen_t fromlen; | |
52 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 53 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 54 | |
55 | /* Get IP address of client. */ | |
56 | fromlen = sizeof(from); | |
57 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 58 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 59 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 60 | cleanup_exit(255); |
5260325f | 61 | } |
1639bb8f | 62 | |
88680c8b | 63 | if (from.ss_family == AF_INET) |
64 | check_ip_options(sock, ntop); | |
65 | ||
1639bb8f | 66 | ipv64_normalise_mapped(&from, &fromlen); |
67 | ||
e7ccd20d | 68 | if (from.ss_family == AF_INET6) |
69 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 70 | |
48e671d5 | 71 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 72 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 73 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 74 | |
c5a7d788 | 75 | if (!use_dns) |
76 | return xstrdup(ntop); | |
77 | ||
3a83b819 | 78 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 79 | /* Map the IP address to a host name. */ |
80 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 81 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 82 | /* Host name not found. Use ip address. */ |
61e96248 | 83 | return xstrdup(ntop); |
8efc0c15 | 84 | } |
5260325f | 85 | |
c5a7d788 | 86 | /* |
87 | * if reverse lookup result looks like a numeric hostname, | |
88 | * someone is trying to trick us by PTR record like following: | |
89 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
90 | */ | |
91 | memset(&hints, 0, sizeof(hints)); | |
92 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 93 | hints.ai_flags = AI_NUMERICHOST; |
c5daf22b | 94 | if (getaddrinfo(name, NULL, &hints, &ai) == 0) { |
c5a7d788 | 95 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", |
96 | name, ntop); | |
97 | freeaddrinfo(ai); | |
98 | return xstrdup(ntop); | |
99 | } | |
100 | ||
61e96248 | 101 | /* |
102 | * Convert it to all lowercase (which is expected by the rest | |
103 | * of this software). | |
104 | */ | |
105 | for (i = 0; name[i]; i++) | |
106 | if (isupper(name[i])) | |
9555d258 | 107 | name[i] = (char)tolower(name[i]); |
aa3378df | 108 | /* |
61e96248 | 109 | * Map it back to an IP address and check that the given |
110 | * address actually is an address of this host. This is | |
111 | * necessary because anyone with access to a name server can | |
112 | * define arbitrary names for an IP address. Mapping from | |
113 | * name to IP address can be trusted better (but can still be | |
114 | * fooled if the intruder has access to the name server of | |
115 | * the domain). | |
aa3378df | 116 | */ |
61e96248 | 117 | memset(&hints, 0, sizeof(hints)); |
118 | hints.ai_family = from.ss_family; | |
119 | hints.ai_socktype = SOCK_STREAM; | |
120 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 121 | logit("reverse mapping checking getaddrinfo for %.700s " |
22aa23f8 | 122 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
61e96248 | 123 | return xstrdup(ntop); |
124 | } | |
125 | /* Look for the address from the list of addresses. */ | |
126 | for (ai = aitop; ai; ai = ai->ai_next) { | |
127 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
128 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
129 | (strcmp(ntop, ntop2) == 0)) | |
130 | break; | |
131 | } | |
132 | freeaddrinfo(aitop); | |
133 | /* If we reached the end of the list, the address was not there. */ | |
134 | if (!ai) { | |
135 | /* Address not found for the host name. */ | |
bbe88b6d | 136 | logit("Address %.100s maps to %.600s, but this does not " |
1908529f | 137 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
61e96248 | 138 | ntop, name); |
139 | return xstrdup(ntop); | |
8efc0c15 | 140 | } |
5260325f | 141 | return xstrdup(name); |
8efc0c15 | 142 | } |
143 | ||
61e96248 | 144 | /* |
145 | * If IP options are supported, make sure there are none (log and | |
146 | * disconnect them if any are found). Basically we are worried about | |
147 | * source routing; it can be used to pretend you are somebody | |
148 | * (ip-address) you are not. That itself may be "almost acceptable" | |
149 | * under certain circumstances, but rhosts autentication is useless | |
150 | * if source routing is accepted. Notice also that if we just dropped | |
151 | * source routing here, the other side could use IP spoofing to do | |
152 | * rest of the interaction and could still bypass security. So we | |
153 | * exit here if we detect any IP options. | |
154 | */ | |
155 | /* IPv4 only */ | |
396c147e | 156 | static void |
ca75d7de | 157 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 158 | { |
97722976 | 159 | #ifdef IP_OPTIONS |
e6fa162e | 160 | u_char options[200]; |
161 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 162 | socklen_t option_size; |
2ceb8101 | 163 | u_int i; |
164 | int ipproto; | |
61e96248 | 165 | struct protoent *ip; |
166 | ||
167 | if ((ip = getprotobyname("ip")) != NULL) | |
168 | ipproto = ip->p_proto; | |
169 | else | |
170 | ipproto = IPPROTO_IP; | |
171 | option_size = sizeof(options); | |
ca75d7de | 172 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 173 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 174 | text[0] = '\0'; |
175 | for (i = 0; i < option_size; i++) | |
176 | snprintf(text + i*3, sizeof(text) - i*3, | |
177 | " %2.2x", options[i]); | |
3a85986d | 178 | fatal("Connection from %.100s with IP options:%.800s", |
61e96248 | 179 | ipaddr, text); |
180 | } | |
97722976 | 181 | #endif /* IP_OPTIONS */ |
61e96248 | 182 | } |
183 | ||
b6610e8f | 184 | void |
1639bb8f | 185 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
186 | { | |
187 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
188 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
189 | struct in_addr inaddr; | |
190 | u_int16_t port; | |
191 | ||
d1cf9a87 | 192 | if (addr->ss_family != AF_INET6 || |
1639bb8f | 193 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
194 | return; | |
195 | ||
196 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
197 | ||
198 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
199 | port = a6->sin6_port; | |
200 | ||
201 | memset(addr, 0, sizeof(*a4)); | |
202 | ||
203 | a4->sin_family = AF_INET; | |
204 | *len = sizeof(*a4); | |
205 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
206 | a4->sin_port = port; | |
207 | } | |
208 | ||
aa3378df | 209 | /* |
210 | * Return the canonical name of the host in the other side of the current | |
211 | * connection. The host name is cached, so it is efficient to call this | |
212 | * several times. | |
213 | */ | |
8efc0c15 | 214 | |
5260325f | 215 | const char * |
c5a7d788 | 216 | get_canonical_hostname(int use_dns) |
8efc0c15 | 217 | { |
0bbbf2a4 | 218 | char *host; |
48e671d5 | 219 | static char *canonical_host_name = NULL; |
0bbbf2a4 | 220 | static char *remote_ip = NULL; |
48e671d5 | 221 | |
61e96248 | 222 | /* Check if we have previously retrieved name with same option. */ |
0bbbf2a4 | 223 | if (use_dns && canonical_host_name != NULL) |
224 | return canonical_host_name; | |
225 | if (!use_dns && remote_ip != NULL) | |
226 | return remote_ip; | |
8efc0c15 | 227 | |
5260325f | 228 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 229 | if (packet_connection_is_on_socket()) |
0bbbf2a4 | 230 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
5260325f | 231 | else |
0bbbf2a4 | 232 | host = "UNKNOWN"; |
8efc0c15 | 233 | |
0bbbf2a4 | 234 | if (use_dns) |
235 | canonical_host_name = host; | |
236 | else | |
237 | remote_ip = host; | |
238 | return host; | |
8efc0c15 | 239 | } |
240 | ||
aa3378df | 241 | /* |
649bb60b | 242 | * Returns the local/remote IP-address/hostname of socket as a string. |
243 | * The returned string must be freed. | |
aa3378df | 244 | */ |
396c147e | 245 | static char * |
ca75d7de | 246 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 247 | { |
8002af61 | 248 | struct sockaddr_storage addr; |
249 | socklen_t addrlen; | |
48e671d5 | 250 | char ntop[NI_MAXHOST]; |
adc75586 | 251 | int r; |
5260325f | 252 | |
5260325f | 253 | /* Get IP address of client. */ |
8002af61 | 254 | addrlen = sizeof(addr); |
255 | memset(&addr, 0, sizeof(addr)); | |
256 | ||
257 | if (remote) { | |
ca75d7de | 258 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 259 | < 0) |
8002af61 | 260 | return NULL; |
8002af61 | 261 | } else { |
ca75d7de | 262 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 263 | < 0) |
8002af61 | 264 | return NULL; |
5260325f | 265 | } |
e7ccd20d | 266 | |
267 | /* Work around Linux IPv6 weirdness */ | |
268 | if (addr.ss_family == AF_INET6) | |
269 | addrlen = sizeof(struct sockaddr_in6); | |
270 | ||
a56cebd3 | 271 | ipv64_normalise_mapped(&addr, &addrlen); |
272 | ||
8002af61 | 273 | /* Get the address in ascii. */ |
adc75586 | 274 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
275 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
276 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
bb4626fe | 277 | ssh_gai_strerror(r)); |
865ac82e | 278 | return NULL; |
279 | } | |
280 | return xstrdup(ntop); | |
281 | } | |
48e671d5 | 282 | |
8002af61 | 283 | char * |
ca75d7de | 284 | get_peer_ipaddr(int sock) |
8002af61 | 285 | { |
99443922 | 286 | char *p; |
287 | ||
ca75d7de | 288 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 289 | return p; |
290 | return xstrdup("UNKNOWN"); | |
8002af61 | 291 | } |
292 | ||
293 | char * | |
ca75d7de | 294 | get_local_ipaddr(int sock) |
8002af61 | 295 | { |
99443922 | 296 | char *p; |
297 | ||
ca75d7de | 298 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 299 | return p; |
300 | return xstrdup("UNKNOWN"); | |
8002af61 | 301 | } |
302 | ||
303 | char * | |
ca75d7de | 304 | get_local_name(int sock) |
8002af61 | 305 | { |
ca75d7de | 306 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 307 | } |
308 | ||
f936c5d4 | 309 | void |
310 | clear_cached_addr(void) | |
311 | { | |
312 | if (canonical_host_ip != NULL) { | |
313 | xfree(canonical_host_ip); | |
314 | canonical_host_ip = NULL; | |
315 | } | |
316 | cached_port = -1; | |
317 | } | |
318 | ||
865ac82e | 319 | /* |
320 | * Returns the IP-address of the remote host as a string. The returned | |
321 | * string must not be freed. | |
322 | */ | |
5260325f | 323 | |
865ac82e | 324 | const char * |
d5bb9418 | 325 | get_remote_ipaddr(void) |
865ac82e | 326 | { |
865ac82e | 327 | /* Check whether we have cached the ipaddr. */ |
328 | if (canonical_host_ip == NULL) { | |
329 | if (packet_connection_is_on_socket()) { | |
330 | canonical_host_ip = | |
331 | get_peer_ipaddr(packet_get_connection_in()); | |
332 | if (canonical_host_ip == NULL) | |
2362db19 | 333 | cleanup_exit(255); |
865ac82e | 334 | } else { |
335 | /* If not on socket, return UNKNOWN. */ | |
336 | canonical_host_ip = xstrdup("UNKNOWN"); | |
337 | } | |
338 | } | |
5260325f | 339 | return canonical_host_ip; |
8efc0c15 | 340 | } |
341 | ||
46e3af7f | 342 | const char * |
c5a7d788 | 343 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 344 | { |
345 | static const char *remote = ""; | |
346 | if (utmp_len > 0) | |
c5a7d788 | 347 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 348 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
349 | remote = get_remote_ipaddr(); | |
350 | return remote; | |
351 | } | |
352 | ||
48e671d5 | 353 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 354 | |
17525a70 | 355 | int |
48e671d5 | 356 | get_sock_port(int sock, int local) |
8efc0c15 | 357 | { |
48e671d5 | 358 | struct sockaddr_storage from; |
359 | socklen_t fromlen; | |
360 | char strport[NI_MAXSERV]; | |
adc75586 | 361 | int r; |
5260325f | 362 | |
363 | /* Get IP address of client. */ | |
364 | fromlen = sizeof(from); | |
365 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 366 | if (local) { |
367 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
368 | error("getsockname failed: %.100s", strerror(errno)); | |
369 | return 0; | |
370 | } | |
371 | } else { | |
649bb60b | 372 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 373 | debug("getpeername failed: %.100s", strerror(errno)); |
29798ed0 | 374 | return -1; |
48e671d5 | 375 | } |
5260325f | 376 | } |
e7ccd20d | 377 | |
378 | /* Work around Linux IPv6 weirdness */ | |
379 | if (from.ss_family == AF_INET6) | |
380 | fromlen = sizeof(struct sockaddr_in6); | |
381 | ||
5260325f | 382 | /* Return port number. */ |
adc75586 | 383 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
384 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
385 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
bb4626fe | 386 | ssh_gai_strerror(r)); |
48e671d5 | 387 | return atoi(strport); |
8efc0c15 | 388 | } |
389 | ||
48e671d5 | 390 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 391 | |
396c147e | 392 | static int |
48e671d5 | 393 | get_port(int local) |
8efc0c15 | 394 | { |
aa3378df | 395 | /* |
396 | * If the connection is not a socket, return 65535. This is | |
397 | * intentionally chosen to be an unprivileged port number. | |
398 | */ | |
48e671d5 | 399 | if (!packet_connection_is_on_socket()) |
5260325f | 400 | return 65535; |
8efc0c15 | 401 | |
48e671d5 | 402 | /* Get socket and return the port number. */ |
403 | return get_sock_port(packet_get_connection_in(), local); | |
404 | } | |
405 | ||
6ae2364d | 406 | int |
48e671d5 | 407 | get_peer_port(int sock) |
408 | { | |
409 | return get_sock_port(sock, 0); | |
410 | } | |
8efc0c15 | 411 | |
6ae2364d | 412 | int |
d5bb9418 | 413 | get_remote_port(void) |
48e671d5 | 414 | { |
13f2a382 | 415 | /* Cache to avoid getpeername() on a dead connection */ |
f936c5d4 | 416 | if (cached_port == -1) |
417 | cached_port = get_port(0); | |
13f2a382 | 418 | |
f936c5d4 | 419 | return cached_port; |
48e671d5 | 420 | } |
421 | ||
422 | int | |
d5bb9418 | 423 | get_local_port(void) |
48e671d5 | 424 | { |
425 | return get_port(1); | |
8efc0c15 | 426 | } |