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31652869 | 1 | /* $OpenBSD: canohost.c,v 1.61 2006/08/03 03:34:41 deraadt 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" |
8efc0c15 | 35 | |
396c147e | 36 | static void check_ip_options(int, char *); |
61e96248 | 37 | |
aa3378df | 38 | /* |
39 | * Return the canonical name of the host at the other end of the socket. The | |
40 | * caller should free the returned string with xfree. | |
41 | */ | |
8efc0c15 | 42 | |
396c147e | 43 | static char * |
ca75d7de | 44 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 45 | { |
48e671d5 | 46 | struct sockaddr_storage from; |
47 | int i; | |
48 | socklen_t fromlen; | |
49 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 50 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 51 | |
52 | /* Get IP address of client. */ | |
53 | fromlen = sizeof(from); | |
54 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 55 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 56 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 57 | cleanup_exit(255); |
5260325f | 58 | } |
1639bb8f | 59 | |
88680c8b | 60 | if (from.ss_family == AF_INET) |
61 | check_ip_options(sock, ntop); | |
62 | ||
1639bb8f | 63 | ipv64_normalise_mapped(&from, &fromlen); |
64 | ||
e7ccd20d | 65 | if (from.ss_family == AF_INET6) |
66 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 67 | |
48e671d5 | 68 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 69 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 70 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 71 | |
c5a7d788 | 72 | if (!use_dns) |
73 | return xstrdup(ntop); | |
74 | ||
3a83b819 | 75 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 76 | /* Map the IP address to a host name. */ |
77 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 78 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 79 | /* Host name not found. Use ip address. */ |
61e96248 | 80 | return xstrdup(ntop); |
8efc0c15 | 81 | } |
5260325f | 82 | |
c5a7d788 | 83 | /* |
84 | * if reverse lookup result looks like a numeric hostname, | |
85 | * someone is trying to trick us by PTR record like following: | |
86 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
87 | */ | |
88 | memset(&hints, 0, sizeof(hints)); | |
89 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 90 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 91 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
92 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
93 | name, ntop); | |
94 | freeaddrinfo(ai); | |
95 | return xstrdup(ntop); | |
96 | } | |
97 | ||
61e96248 | 98 | /* |
99 | * Convert it to all lowercase (which is expected by the rest | |
100 | * of this software). | |
101 | */ | |
102 | for (i = 0; name[i]; i++) | |
103 | if (isupper(name[i])) | |
9555d258 | 104 | name[i] = (char)tolower(name[i]); |
aa3378df | 105 | /* |
61e96248 | 106 | * Map it back to an IP address and check that the given |
107 | * address actually is an address of this host. This is | |
108 | * necessary because anyone with access to a name server can | |
109 | * define arbitrary names for an IP address. Mapping from | |
110 | * name to IP address can be trusted better (but can still be | |
111 | * fooled if the intruder has access to the name server of | |
112 | * the domain). | |
aa3378df | 113 | */ |
61e96248 | 114 | memset(&hints, 0, sizeof(hints)); |
115 | hints.ai_family = from.ss_family; | |
116 | hints.ai_socktype = SOCK_STREAM; | |
117 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 118 | logit("reverse mapping checking getaddrinfo for %.700s " |
22aa23f8 | 119 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
61e96248 | 120 | return xstrdup(ntop); |
121 | } | |
122 | /* Look for the address from the list of addresses. */ | |
123 | for (ai = aitop; ai; ai = ai->ai_next) { | |
124 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
125 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
126 | (strcmp(ntop, ntop2) == 0)) | |
127 | break; | |
128 | } | |
129 | freeaddrinfo(aitop); | |
130 | /* If we reached the end of the list, the address was not there. */ | |
131 | if (!ai) { | |
132 | /* Address not found for the host name. */ | |
bbe88b6d | 133 | logit("Address %.100s maps to %.600s, but this does not " |
1908529f | 134 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
61e96248 | 135 | ntop, name); |
136 | return xstrdup(ntop); | |
8efc0c15 | 137 | } |
5260325f | 138 | return xstrdup(name); |
8efc0c15 | 139 | } |
140 | ||
61e96248 | 141 | /* |
142 | * If IP options are supported, make sure there are none (log and | |
143 | * disconnect them if any are found). Basically we are worried about | |
144 | * source routing; it can be used to pretend you are somebody | |
145 | * (ip-address) you are not. That itself may be "almost acceptable" | |
146 | * under certain circumstances, but rhosts autentication is useless | |
147 | * if source routing is accepted. Notice also that if we just dropped | |
148 | * source routing here, the other side could use IP spoofing to do | |
149 | * rest of the interaction and could still bypass security. So we | |
150 | * exit here if we detect any IP options. | |
151 | */ | |
152 | /* IPv4 only */ | |
396c147e | 153 | static void |
ca75d7de | 154 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 155 | { |
97722976 | 156 | #ifdef IP_OPTIONS |
e6fa162e | 157 | u_char options[200]; |
158 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 159 | socklen_t option_size; |
2ceb8101 | 160 | u_int i; |
161 | int ipproto; | |
61e96248 | 162 | struct protoent *ip; |
163 | ||
164 | if ((ip = getprotobyname("ip")) != NULL) | |
165 | ipproto = ip->p_proto; | |
166 | else | |
167 | ipproto = IPPROTO_IP; | |
168 | option_size = sizeof(options); | |
ca75d7de | 169 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 170 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 171 | text[0] = '\0'; |
172 | for (i = 0; i < option_size; i++) | |
173 | snprintf(text + i*3, sizeof(text) - i*3, | |
174 | " %2.2x", options[i]); | |
3a85986d | 175 | fatal("Connection from %.100s with IP options:%.800s", |
61e96248 | 176 | ipaddr, text); |
177 | } | |
97722976 | 178 | #endif /* IP_OPTIONS */ |
61e96248 | 179 | } |
180 | ||
b6610e8f | 181 | void |
1639bb8f | 182 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
183 | { | |
184 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
185 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
186 | struct in_addr inaddr; | |
187 | u_int16_t port; | |
188 | ||
d1cf9a87 | 189 | if (addr->ss_family != AF_INET6 || |
1639bb8f | 190 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
191 | return; | |
192 | ||
193 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
194 | ||
195 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
196 | port = a6->sin6_port; | |
197 | ||
198 | memset(addr, 0, sizeof(*a4)); | |
199 | ||
200 | a4->sin_family = AF_INET; | |
201 | *len = sizeof(*a4); | |
202 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
203 | a4->sin_port = port; | |
204 | } | |
205 | ||
aa3378df | 206 | /* |
207 | * Return the canonical name of the host in the other side of the current | |
208 | * connection. The host name is cached, so it is efficient to call this | |
209 | * several times. | |
210 | */ | |
8efc0c15 | 211 | |
5260325f | 212 | const char * |
c5a7d788 | 213 | get_canonical_hostname(int use_dns) |
8efc0c15 | 214 | { |
0bbbf2a4 | 215 | char *host; |
48e671d5 | 216 | static char *canonical_host_name = NULL; |
0bbbf2a4 | 217 | static char *remote_ip = NULL; |
48e671d5 | 218 | |
61e96248 | 219 | /* Check if we have previously retrieved name with same option. */ |
0bbbf2a4 | 220 | if (use_dns && canonical_host_name != NULL) |
221 | return canonical_host_name; | |
222 | if (!use_dns && remote_ip != NULL) | |
223 | return remote_ip; | |
8efc0c15 | 224 | |
5260325f | 225 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 226 | if (packet_connection_is_on_socket()) |
0bbbf2a4 | 227 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
5260325f | 228 | else |
0bbbf2a4 | 229 | host = "UNKNOWN"; |
8efc0c15 | 230 | |
0bbbf2a4 | 231 | if (use_dns) |
232 | canonical_host_name = host; | |
233 | else | |
234 | remote_ip = host; | |
235 | return host; | |
8efc0c15 | 236 | } |
237 | ||
aa3378df | 238 | /* |
649bb60b | 239 | * Returns the local/remote IP-address/hostname of socket as a string. |
240 | * The returned string must be freed. | |
aa3378df | 241 | */ |
396c147e | 242 | static char * |
ca75d7de | 243 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 244 | { |
8002af61 | 245 | struct sockaddr_storage addr; |
246 | socklen_t addrlen; | |
48e671d5 | 247 | char ntop[NI_MAXHOST]; |
adc75586 | 248 | int r; |
5260325f | 249 | |
5260325f | 250 | /* Get IP address of client. */ |
8002af61 | 251 | addrlen = sizeof(addr); |
252 | memset(&addr, 0, sizeof(addr)); | |
253 | ||
254 | if (remote) { | |
ca75d7de | 255 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 256 | < 0) |
8002af61 | 257 | return NULL; |
8002af61 | 258 | } else { |
ca75d7de | 259 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 260 | < 0) |
8002af61 | 261 | return NULL; |
5260325f | 262 | } |
e7ccd20d | 263 | |
264 | /* Work around Linux IPv6 weirdness */ | |
265 | if (addr.ss_family == AF_INET6) | |
266 | addrlen = sizeof(struct sockaddr_in6); | |
267 | ||
a56cebd3 | 268 | ipv64_normalise_mapped(&addr, &addrlen); |
269 | ||
8002af61 | 270 | /* Get the address in ascii. */ |
adc75586 | 271 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
272 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
273 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
274 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
865ac82e | 275 | return NULL; |
276 | } | |
277 | return xstrdup(ntop); | |
278 | } | |
48e671d5 | 279 | |
8002af61 | 280 | char * |
ca75d7de | 281 | get_peer_ipaddr(int sock) |
8002af61 | 282 | { |
99443922 | 283 | char *p; |
284 | ||
ca75d7de | 285 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 286 | return p; |
287 | return xstrdup("UNKNOWN"); | |
8002af61 | 288 | } |
289 | ||
290 | char * | |
ca75d7de | 291 | get_local_ipaddr(int sock) |
8002af61 | 292 | { |
99443922 | 293 | char *p; |
294 | ||
ca75d7de | 295 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 296 | return p; |
297 | return xstrdup("UNKNOWN"); | |
8002af61 | 298 | } |
299 | ||
300 | char * | |
ca75d7de | 301 | get_local_name(int sock) |
8002af61 | 302 | { |
ca75d7de | 303 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 304 | } |
305 | ||
865ac82e | 306 | /* |
307 | * Returns the IP-address of the remote host as a string. The returned | |
308 | * string must not be freed. | |
309 | */ | |
5260325f | 310 | |
865ac82e | 311 | const char * |
d5bb9418 | 312 | get_remote_ipaddr(void) |
865ac82e | 313 | { |
314 | static char *canonical_host_ip = NULL; | |
315 | ||
316 | /* Check whether we have cached the ipaddr. */ | |
317 | if (canonical_host_ip == NULL) { | |
318 | if (packet_connection_is_on_socket()) { | |
319 | canonical_host_ip = | |
320 | get_peer_ipaddr(packet_get_connection_in()); | |
321 | if (canonical_host_ip == NULL) | |
2362db19 | 322 | cleanup_exit(255); |
865ac82e | 323 | } else { |
324 | /* If not on socket, return UNKNOWN. */ | |
325 | canonical_host_ip = xstrdup("UNKNOWN"); | |
326 | } | |
327 | } | |
5260325f | 328 | return canonical_host_ip; |
8efc0c15 | 329 | } |
330 | ||
46e3af7f | 331 | const char * |
c5a7d788 | 332 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 333 | { |
334 | static const char *remote = ""; | |
335 | if (utmp_len > 0) | |
c5a7d788 | 336 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 337 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
338 | remote = get_remote_ipaddr(); | |
339 | return remote; | |
340 | } | |
341 | ||
48e671d5 | 342 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 343 | |
396c147e | 344 | static int |
48e671d5 | 345 | get_sock_port(int sock, int local) |
8efc0c15 | 346 | { |
48e671d5 | 347 | struct sockaddr_storage from; |
348 | socklen_t fromlen; | |
349 | char strport[NI_MAXSERV]; | |
adc75586 | 350 | int r; |
5260325f | 351 | |
352 | /* Get IP address of client. */ | |
353 | fromlen = sizeof(from); | |
354 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 355 | if (local) { |
356 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
357 | error("getsockname failed: %.100s", strerror(errno)); | |
358 | return 0; | |
359 | } | |
360 | } else { | |
649bb60b | 361 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 362 | debug("getpeername failed: %.100s", strerror(errno)); |
29798ed0 | 363 | return -1; |
48e671d5 | 364 | } |
5260325f | 365 | } |
e7ccd20d | 366 | |
367 | /* Work around Linux IPv6 weirdness */ | |
368 | if (from.ss_family == AF_INET6) | |
369 | fromlen = sizeof(struct sockaddr_in6); | |
370 | ||
5260325f | 371 | /* Return port number. */ |
adc75586 | 372 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
373 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
374 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
375 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
48e671d5 | 376 | return atoi(strport); |
8efc0c15 | 377 | } |
378 | ||
48e671d5 | 379 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 380 | |
396c147e | 381 | static int |
48e671d5 | 382 | get_port(int local) |
8efc0c15 | 383 | { |
aa3378df | 384 | /* |
385 | * If the connection is not a socket, return 65535. This is | |
386 | * intentionally chosen to be an unprivileged port number. | |
387 | */ | |
48e671d5 | 388 | if (!packet_connection_is_on_socket()) |
5260325f | 389 | return 65535; |
8efc0c15 | 390 | |
48e671d5 | 391 | /* Get socket and return the port number. */ |
392 | return get_sock_port(packet_get_connection_in(), local); | |
393 | } | |
394 | ||
6ae2364d | 395 | int |
48e671d5 | 396 | get_peer_port(int sock) |
397 | { | |
398 | return get_sock_port(sock, 0); | |
399 | } | |
8efc0c15 | 400 | |
6ae2364d | 401 | int |
d5bb9418 | 402 | get_remote_port(void) |
48e671d5 | 403 | { |
13f2a382 | 404 | static int port = -1; |
405 | ||
406 | /* Cache to avoid getpeername() on a dead connection */ | |
407 | if (port == -1) | |
408 | port = get_port(0); | |
409 | ||
410 | return port; | |
48e671d5 | 411 | } |
412 | ||
413 | int | |
d5bb9418 | 414 | get_local_port(void) |
48e671d5 | 415 | { |
416 | return get_port(1); | |
8efc0c15 | 417 | } |