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cf851879 | 1 | /* $OpenBSD: canohost.c,v 1.60 2006/08/01 23:22:47 stevesk 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> | |
21 | ||
b6438382 | 22 | #include <ctype.h> |
028094f4 | 23 | #include <errno.h> |
28cb0a43 | 24 | #include <netdb.h> |
cf851879 | 25 | #include <stdio.h> |
ffa517a8 | 26 | #include <stdlib.h> |
00146caa | 27 | #include <string.h> |
8efc0c15 | 28 | |
29 | #include "packet.h" | |
30 | #include "xmalloc.h" | |
42f11eb2 | 31 | #include "log.h" |
5ca51e19 | 32 | #include "canohost.h" |
8efc0c15 | 33 | |
396c147e | 34 | static void check_ip_options(int, char *); |
61e96248 | 35 | |
aa3378df | 36 | /* |
37 | * Return the canonical name of the host at the other end of the socket. The | |
38 | * caller should free the returned string with xfree. | |
39 | */ | |
8efc0c15 | 40 | |
396c147e | 41 | static char * |
ca75d7de | 42 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 43 | { |
48e671d5 | 44 | struct sockaddr_storage from; |
45 | int i; | |
46 | socklen_t fromlen; | |
47 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 48 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 49 | |
50 | /* Get IP address of client. */ | |
51 | fromlen = sizeof(from); | |
52 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 53 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 54 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 55 | cleanup_exit(255); |
5260325f | 56 | } |
1639bb8f | 57 | |
88680c8b | 58 | if (from.ss_family == AF_INET) |
59 | check_ip_options(sock, ntop); | |
60 | ||
1639bb8f | 61 | ipv64_normalise_mapped(&from, &fromlen); |
62 | ||
e7ccd20d | 63 | if (from.ss_family == AF_INET6) |
64 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 65 | |
48e671d5 | 66 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 67 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 68 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 69 | |
c5a7d788 | 70 | if (!use_dns) |
71 | return xstrdup(ntop); | |
72 | ||
3a83b819 | 73 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 74 | /* Map the IP address to a host name. */ |
75 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 76 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 77 | /* Host name not found. Use ip address. */ |
61e96248 | 78 | return xstrdup(ntop); |
8efc0c15 | 79 | } |
5260325f | 80 | |
c5a7d788 | 81 | /* |
82 | * if reverse lookup result looks like a numeric hostname, | |
83 | * someone is trying to trick us by PTR record like following: | |
84 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
85 | */ | |
86 | memset(&hints, 0, sizeof(hints)); | |
87 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 88 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 89 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
90 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
91 | name, ntop); | |
92 | freeaddrinfo(ai); | |
93 | return xstrdup(ntop); | |
94 | } | |
95 | ||
61e96248 | 96 | /* |
97 | * Convert it to all lowercase (which is expected by the rest | |
98 | * of this software). | |
99 | */ | |
100 | for (i = 0; name[i]; i++) | |
101 | if (isupper(name[i])) | |
9555d258 | 102 | name[i] = (char)tolower(name[i]); |
aa3378df | 103 | /* |
61e96248 | 104 | * Map it back to an IP address and check that the given |
105 | * address actually is an address of this host. This is | |
106 | * necessary because anyone with access to a name server can | |
107 | * define arbitrary names for an IP address. Mapping from | |
108 | * name to IP address can be trusted better (but can still be | |
109 | * fooled if the intruder has access to the name server of | |
110 | * the domain). | |
aa3378df | 111 | */ |
61e96248 | 112 | memset(&hints, 0, sizeof(hints)); |
113 | hints.ai_family = from.ss_family; | |
114 | hints.ai_socktype = SOCK_STREAM; | |
115 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 116 | logit("reverse mapping checking getaddrinfo for %.700s " |
22aa23f8 | 117 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
61e96248 | 118 | return xstrdup(ntop); |
119 | } | |
120 | /* Look for the address from the list of addresses. */ | |
121 | for (ai = aitop; ai; ai = ai->ai_next) { | |
122 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
123 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
124 | (strcmp(ntop, ntop2) == 0)) | |
125 | break; | |
126 | } | |
127 | freeaddrinfo(aitop); | |
128 | /* If we reached the end of the list, the address was not there. */ | |
129 | if (!ai) { | |
130 | /* Address not found for the host name. */ | |
bbe88b6d | 131 | logit("Address %.100s maps to %.600s, but this does not " |
1908529f | 132 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
61e96248 | 133 | ntop, name); |
134 | return xstrdup(ntop); | |
8efc0c15 | 135 | } |
5260325f | 136 | return xstrdup(name); |
8efc0c15 | 137 | } |
138 | ||
61e96248 | 139 | /* |
140 | * If IP options are supported, make sure there are none (log and | |
141 | * disconnect them if any are found). Basically we are worried about | |
142 | * source routing; it can be used to pretend you are somebody | |
143 | * (ip-address) you are not. That itself may be "almost acceptable" | |
144 | * under certain circumstances, but rhosts autentication is useless | |
145 | * if source routing is accepted. Notice also that if we just dropped | |
146 | * source routing here, the other side could use IP spoofing to do | |
147 | * rest of the interaction and could still bypass security. So we | |
148 | * exit here if we detect any IP options. | |
149 | */ | |
150 | /* IPv4 only */ | |
396c147e | 151 | static void |
ca75d7de | 152 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 153 | { |
97722976 | 154 | #ifdef IP_OPTIONS |
e6fa162e | 155 | u_char options[200]; |
156 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 157 | socklen_t option_size; |
2ceb8101 | 158 | u_int i; |
159 | int ipproto; | |
61e96248 | 160 | struct protoent *ip; |
161 | ||
162 | if ((ip = getprotobyname("ip")) != NULL) | |
163 | ipproto = ip->p_proto; | |
164 | else | |
165 | ipproto = IPPROTO_IP; | |
166 | option_size = sizeof(options); | |
ca75d7de | 167 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 168 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 169 | text[0] = '\0'; |
170 | for (i = 0; i < option_size; i++) | |
171 | snprintf(text + i*3, sizeof(text) - i*3, | |
172 | " %2.2x", options[i]); | |
3a85986d | 173 | fatal("Connection from %.100s with IP options:%.800s", |
61e96248 | 174 | ipaddr, text); |
175 | } | |
97722976 | 176 | #endif /* IP_OPTIONS */ |
61e96248 | 177 | } |
178 | ||
b6610e8f | 179 | void |
1639bb8f | 180 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
181 | { | |
182 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
183 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
184 | struct in_addr inaddr; | |
185 | u_int16_t port; | |
186 | ||
d1cf9a87 | 187 | if (addr->ss_family != AF_INET6 || |
1639bb8f | 188 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
189 | return; | |
190 | ||
191 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
192 | ||
193 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
194 | port = a6->sin6_port; | |
195 | ||
196 | memset(addr, 0, sizeof(*a4)); | |
197 | ||
198 | a4->sin_family = AF_INET; | |
199 | *len = sizeof(*a4); | |
200 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
201 | a4->sin_port = port; | |
202 | } | |
203 | ||
aa3378df | 204 | /* |
205 | * Return the canonical name of the host in the other side of the current | |
206 | * connection. The host name is cached, so it is efficient to call this | |
207 | * several times. | |
208 | */ | |
8efc0c15 | 209 | |
5260325f | 210 | const char * |
c5a7d788 | 211 | get_canonical_hostname(int use_dns) |
8efc0c15 | 212 | { |
0bbbf2a4 | 213 | char *host; |
48e671d5 | 214 | static char *canonical_host_name = NULL; |
0bbbf2a4 | 215 | static char *remote_ip = NULL; |
48e671d5 | 216 | |
61e96248 | 217 | /* Check if we have previously retrieved name with same option. */ |
0bbbf2a4 | 218 | if (use_dns && canonical_host_name != NULL) |
219 | return canonical_host_name; | |
220 | if (!use_dns && remote_ip != NULL) | |
221 | return remote_ip; | |
8efc0c15 | 222 | |
5260325f | 223 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 224 | if (packet_connection_is_on_socket()) |
0bbbf2a4 | 225 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
5260325f | 226 | else |
0bbbf2a4 | 227 | host = "UNKNOWN"; |
8efc0c15 | 228 | |
0bbbf2a4 | 229 | if (use_dns) |
230 | canonical_host_name = host; | |
231 | else | |
232 | remote_ip = host; | |
233 | return host; | |
8efc0c15 | 234 | } |
235 | ||
aa3378df | 236 | /* |
649bb60b | 237 | * Returns the local/remote IP-address/hostname of socket as a string. |
238 | * The returned string must be freed. | |
aa3378df | 239 | */ |
396c147e | 240 | static char * |
ca75d7de | 241 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 242 | { |
8002af61 | 243 | struct sockaddr_storage addr; |
244 | socklen_t addrlen; | |
48e671d5 | 245 | char ntop[NI_MAXHOST]; |
adc75586 | 246 | int r; |
5260325f | 247 | |
5260325f | 248 | /* Get IP address of client. */ |
8002af61 | 249 | addrlen = sizeof(addr); |
250 | memset(&addr, 0, sizeof(addr)); | |
251 | ||
252 | if (remote) { | |
ca75d7de | 253 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 254 | < 0) |
8002af61 | 255 | return NULL; |
8002af61 | 256 | } else { |
ca75d7de | 257 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 258 | < 0) |
8002af61 | 259 | return NULL; |
5260325f | 260 | } |
e7ccd20d | 261 | |
262 | /* Work around Linux IPv6 weirdness */ | |
263 | if (addr.ss_family == AF_INET6) | |
264 | addrlen = sizeof(struct sockaddr_in6); | |
265 | ||
a56cebd3 | 266 | ipv64_normalise_mapped(&addr, &addrlen); |
267 | ||
8002af61 | 268 | /* Get the address in ascii. */ |
adc75586 | 269 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
270 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
271 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
272 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
865ac82e | 273 | return NULL; |
274 | } | |
275 | return xstrdup(ntop); | |
276 | } | |
48e671d5 | 277 | |
8002af61 | 278 | char * |
ca75d7de | 279 | get_peer_ipaddr(int sock) |
8002af61 | 280 | { |
99443922 | 281 | char *p; |
282 | ||
ca75d7de | 283 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 284 | return p; |
285 | return xstrdup("UNKNOWN"); | |
8002af61 | 286 | } |
287 | ||
288 | char * | |
ca75d7de | 289 | get_local_ipaddr(int sock) |
8002af61 | 290 | { |
99443922 | 291 | char *p; |
292 | ||
ca75d7de | 293 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 294 | return p; |
295 | return xstrdup("UNKNOWN"); | |
8002af61 | 296 | } |
297 | ||
298 | char * | |
ca75d7de | 299 | get_local_name(int sock) |
8002af61 | 300 | { |
ca75d7de | 301 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 302 | } |
303 | ||
865ac82e | 304 | /* |
305 | * Returns the IP-address of the remote host as a string. The returned | |
306 | * string must not be freed. | |
307 | */ | |
5260325f | 308 | |
865ac82e | 309 | const char * |
d5bb9418 | 310 | get_remote_ipaddr(void) |
865ac82e | 311 | { |
312 | static char *canonical_host_ip = NULL; | |
313 | ||
314 | /* Check whether we have cached the ipaddr. */ | |
315 | if (canonical_host_ip == NULL) { | |
316 | if (packet_connection_is_on_socket()) { | |
317 | canonical_host_ip = | |
318 | get_peer_ipaddr(packet_get_connection_in()); | |
319 | if (canonical_host_ip == NULL) | |
2362db19 | 320 | cleanup_exit(255); |
865ac82e | 321 | } else { |
322 | /* If not on socket, return UNKNOWN. */ | |
323 | canonical_host_ip = xstrdup("UNKNOWN"); | |
324 | } | |
325 | } | |
5260325f | 326 | return canonical_host_ip; |
8efc0c15 | 327 | } |
328 | ||
46e3af7f | 329 | const char * |
c5a7d788 | 330 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 331 | { |
332 | static const char *remote = ""; | |
333 | if (utmp_len > 0) | |
c5a7d788 | 334 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 335 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
336 | remote = get_remote_ipaddr(); | |
337 | return remote; | |
338 | } | |
339 | ||
48e671d5 | 340 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 341 | |
396c147e | 342 | static int |
48e671d5 | 343 | get_sock_port(int sock, int local) |
8efc0c15 | 344 | { |
48e671d5 | 345 | struct sockaddr_storage from; |
346 | socklen_t fromlen; | |
347 | char strport[NI_MAXSERV]; | |
adc75586 | 348 | int r; |
5260325f | 349 | |
350 | /* Get IP address of client. */ | |
351 | fromlen = sizeof(from); | |
352 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 353 | if (local) { |
354 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
355 | error("getsockname failed: %.100s", strerror(errno)); | |
356 | return 0; | |
357 | } | |
358 | } else { | |
649bb60b | 359 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 360 | debug("getpeername failed: %.100s", strerror(errno)); |
29798ed0 | 361 | return -1; |
48e671d5 | 362 | } |
5260325f | 363 | } |
e7ccd20d | 364 | |
365 | /* Work around Linux IPv6 weirdness */ | |
366 | if (from.ss_family == AF_INET6) | |
367 | fromlen = sizeof(struct sockaddr_in6); | |
368 | ||
5260325f | 369 | /* Return port number. */ |
adc75586 | 370 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
371 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
372 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
373 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
48e671d5 | 374 | return atoi(strport); |
8efc0c15 | 375 | } |
376 | ||
48e671d5 | 377 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 378 | |
396c147e | 379 | static int |
48e671d5 | 380 | get_port(int local) |
8efc0c15 | 381 | { |
aa3378df | 382 | /* |
383 | * If the connection is not a socket, return 65535. This is | |
384 | * intentionally chosen to be an unprivileged port number. | |
385 | */ | |
48e671d5 | 386 | if (!packet_connection_is_on_socket()) |
5260325f | 387 | return 65535; |
8efc0c15 | 388 | |
48e671d5 | 389 | /* Get socket and return the port number. */ |
390 | return get_sock_port(packet_get_connection_in(), local); | |
391 | } | |
392 | ||
6ae2364d | 393 | int |
48e671d5 | 394 | get_peer_port(int sock) |
395 | { | |
396 | return get_sock_port(sock, 0); | |
397 | } | |
8efc0c15 | 398 | |
6ae2364d | 399 | int |
d5bb9418 | 400 | get_remote_port(void) |
48e671d5 | 401 | { |
13f2a382 | 402 | static int port = -1; |
403 | ||
404 | /* Cache to avoid getpeername() on a dead connection */ | |
405 | if (port == -1) | |
406 | port = get_port(0); | |
407 | ||
408 | return port; | |
48e671d5 | 409 | } |
410 | ||
411 | int | |
d5bb9418 | 412 | get_local_port(void) |
48e671d5 | 413 | { |
414 | return get_port(1); | |
8efc0c15 | 415 | } |