]>
Commit | Line | Data |
---|---|---|
9794d008 | 1 | /* $OpenBSD: canohost.c,v 1.54 2006/07/05 02:42:09 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 | |
9794d008 | 17 | #include <sys/socket.h> |
18 | ||
19 | #include <netinet/in.h> | |
20 | ||
b6438382 | 21 | #include <ctype.h> |
8efc0c15 | 22 | |
23 | #include "packet.h" | |
24 | #include "xmalloc.h" | |
42f11eb2 | 25 | #include "log.h" |
5ca51e19 | 26 | #include "canohost.h" |
8efc0c15 | 27 | |
396c147e | 28 | static void check_ip_options(int, char *); |
61e96248 | 29 | |
aa3378df | 30 | /* |
31 | * Return the canonical name of the host at the other end of the socket. The | |
32 | * caller should free the returned string with xfree. | |
33 | */ | |
8efc0c15 | 34 | |
396c147e | 35 | static char * |
ca75d7de | 36 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 37 | { |
48e671d5 | 38 | struct sockaddr_storage from; |
39 | int i; | |
40 | socklen_t fromlen; | |
41 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 42 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 43 | |
44 | /* Get IP address of client. */ | |
45 | fromlen = sizeof(from); | |
46 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 47 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 48 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 49 | cleanup_exit(255); |
5260325f | 50 | } |
1639bb8f | 51 | |
88680c8b | 52 | if (from.ss_family == AF_INET) |
53 | check_ip_options(sock, ntop); | |
54 | ||
1639bb8f | 55 | ipv64_normalise_mapped(&from, &fromlen); |
56 | ||
e7ccd20d | 57 | if (from.ss_family == AF_INET6) |
58 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 59 | |
48e671d5 | 60 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 61 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 62 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 63 | |
c5a7d788 | 64 | if (!use_dns) |
65 | return xstrdup(ntop); | |
66 | ||
3a83b819 | 67 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 68 | /* Map the IP address to a host name. */ |
69 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 70 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 71 | /* Host name not found. Use ip address. */ |
61e96248 | 72 | return xstrdup(ntop); |
8efc0c15 | 73 | } |
5260325f | 74 | |
c5a7d788 | 75 | /* |
76 | * if reverse lookup result looks like a numeric hostname, | |
77 | * someone is trying to trick us by PTR record like following: | |
78 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
79 | */ | |
80 | memset(&hints, 0, sizeof(hints)); | |
81 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 82 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 83 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
84 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
85 | name, ntop); | |
86 | freeaddrinfo(ai); | |
87 | return xstrdup(ntop); | |
88 | } | |
89 | ||
61e96248 | 90 | /* |
91 | * Convert it to all lowercase (which is expected by the rest | |
92 | * of this software). | |
93 | */ | |
94 | for (i = 0; name[i]; i++) | |
95 | if (isupper(name[i])) | |
9555d258 | 96 | name[i] = (char)tolower(name[i]); |
aa3378df | 97 | /* |
61e96248 | 98 | * Map it back to an IP address and check that the given |
99 | * address actually is an address of this host. This is | |
100 | * necessary because anyone with access to a name server can | |
101 | * define arbitrary names for an IP address. Mapping from | |
102 | * name to IP address can be trusted better (but can still be | |
103 | * fooled if the intruder has access to the name server of | |
104 | * the domain). | |
aa3378df | 105 | */ |
61e96248 | 106 | memset(&hints, 0, sizeof(hints)); |
107 | hints.ai_family = from.ss_family; | |
108 | hints.ai_socktype = SOCK_STREAM; | |
109 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 110 | logit("reverse mapping checking getaddrinfo for %.700s " |
22aa23f8 | 111 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
61e96248 | 112 | return xstrdup(ntop); |
113 | } | |
114 | /* Look for the address from the list of addresses. */ | |
115 | for (ai = aitop; ai; ai = ai->ai_next) { | |
116 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
117 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
118 | (strcmp(ntop, ntop2) == 0)) | |
119 | break; | |
120 | } | |
121 | freeaddrinfo(aitop); | |
122 | /* If we reached the end of the list, the address was not there. */ | |
123 | if (!ai) { | |
124 | /* Address not found for the host name. */ | |
bbe88b6d | 125 | logit("Address %.100s maps to %.600s, but this does not " |
1908529f | 126 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
61e96248 | 127 | ntop, name); |
128 | return xstrdup(ntop); | |
8efc0c15 | 129 | } |
5260325f | 130 | return xstrdup(name); |
8efc0c15 | 131 | } |
132 | ||
61e96248 | 133 | /* |
134 | * If IP options are supported, make sure there are none (log and | |
135 | * disconnect them if any are found). Basically we are worried about | |
136 | * source routing; it can be used to pretend you are somebody | |
137 | * (ip-address) you are not. That itself may be "almost acceptable" | |
138 | * under certain circumstances, but rhosts autentication is useless | |
139 | * if source routing is accepted. Notice also that if we just dropped | |
140 | * source routing here, the other side could use IP spoofing to do | |
141 | * rest of the interaction and could still bypass security. So we | |
142 | * exit here if we detect any IP options. | |
143 | */ | |
144 | /* IPv4 only */ | |
396c147e | 145 | static void |
ca75d7de | 146 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 147 | { |
97722976 | 148 | #ifdef IP_OPTIONS |
e6fa162e | 149 | u_char options[200]; |
150 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 151 | socklen_t option_size; |
2ceb8101 | 152 | u_int i; |
153 | int ipproto; | |
61e96248 | 154 | struct protoent *ip; |
155 | ||
156 | if ((ip = getprotobyname("ip")) != NULL) | |
157 | ipproto = ip->p_proto; | |
158 | else | |
159 | ipproto = IPPROTO_IP; | |
160 | option_size = sizeof(options); | |
ca75d7de | 161 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 162 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 163 | text[0] = '\0'; |
164 | for (i = 0; i < option_size; i++) | |
165 | snprintf(text + i*3, sizeof(text) - i*3, | |
166 | " %2.2x", options[i]); | |
3a85986d | 167 | fatal("Connection from %.100s with IP options:%.800s", |
61e96248 | 168 | ipaddr, text); |
169 | } | |
97722976 | 170 | #endif /* IP_OPTIONS */ |
61e96248 | 171 | } |
172 | ||
b6610e8f | 173 | void |
1639bb8f | 174 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
175 | { | |
176 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
177 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
178 | struct in_addr inaddr; | |
179 | u_int16_t port; | |
180 | ||
d1cf9a87 | 181 | if (addr->ss_family != AF_INET6 || |
1639bb8f | 182 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
183 | return; | |
184 | ||
185 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
186 | ||
187 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
188 | port = a6->sin6_port; | |
189 | ||
190 | memset(addr, 0, sizeof(*a4)); | |
191 | ||
192 | a4->sin_family = AF_INET; | |
193 | *len = sizeof(*a4); | |
194 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
195 | a4->sin_port = port; | |
196 | } | |
197 | ||
aa3378df | 198 | /* |
199 | * Return the canonical name of the host in the other side of the current | |
200 | * connection. The host name is cached, so it is efficient to call this | |
201 | * several times. | |
202 | */ | |
8efc0c15 | 203 | |
5260325f | 204 | const char * |
c5a7d788 | 205 | get_canonical_hostname(int use_dns) |
8efc0c15 | 206 | { |
0bbbf2a4 | 207 | char *host; |
48e671d5 | 208 | static char *canonical_host_name = NULL; |
0bbbf2a4 | 209 | static char *remote_ip = NULL; |
48e671d5 | 210 | |
61e96248 | 211 | /* Check if we have previously retrieved name with same option. */ |
0bbbf2a4 | 212 | if (use_dns && canonical_host_name != NULL) |
213 | return canonical_host_name; | |
214 | if (!use_dns && remote_ip != NULL) | |
215 | return remote_ip; | |
8efc0c15 | 216 | |
5260325f | 217 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 218 | if (packet_connection_is_on_socket()) |
0bbbf2a4 | 219 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
5260325f | 220 | else |
0bbbf2a4 | 221 | host = "UNKNOWN"; |
8efc0c15 | 222 | |
0bbbf2a4 | 223 | if (use_dns) |
224 | canonical_host_name = host; | |
225 | else | |
226 | remote_ip = host; | |
227 | return host; | |
8efc0c15 | 228 | } |
229 | ||
aa3378df | 230 | /* |
649bb60b | 231 | * Returns the local/remote IP-address/hostname of socket as a string. |
232 | * The returned string must be freed. | |
aa3378df | 233 | */ |
396c147e | 234 | static char * |
ca75d7de | 235 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 236 | { |
8002af61 | 237 | struct sockaddr_storage addr; |
238 | socklen_t addrlen; | |
48e671d5 | 239 | char ntop[NI_MAXHOST]; |
adc75586 | 240 | int r; |
5260325f | 241 | |
5260325f | 242 | /* Get IP address of client. */ |
8002af61 | 243 | addrlen = sizeof(addr); |
244 | memset(&addr, 0, sizeof(addr)); | |
245 | ||
246 | if (remote) { | |
ca75d7de | 247 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 248 | < 0) |
8002af61 | 249 | return NULL; |
8002af61 | 250 | } else { |
ca75d7de | 251 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 252 | < 0) |
8002af61 | 253 | return NULL; |
5260325f | 254 | } |
e7ccd20d | 255 | |
256 | /* Work around Linux IPv6 weirdness */ | |
257 | if (addr.ss_family == AF_INET6) | |
258 | addrlen = sizeof(struct sockaddr_in6); | |
259 | ||
a56cebd3 | 260 | ipv64_normalise_mapped(&addr, &addrlen); |
261 | ||
8002af61 | 262 | /* Get the address in ascii. */ |
adc75586 | 263 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
264 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
265 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
266 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
865ac82e | 267 | return NULL; |
268 | } | |
269 | return xstrdup(ntop); | |
270 | } | |
48e671d5 | 271 | |
8002af61 | 272 | char * |
ca75d7de | 273 | get_peer_ipaddr(int sock) |
8002af61 | 274 | { |
99443922 | 275 | char *p; |
276 | ||
ca75d7de | 277 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 278 | return p; |
279 | return xstrdup("UNKNOWN"); | |
8002af61 | 280 | } |
281 | ||
282 | char * | |
ca75d7de | 283 | get_local_ipaddr(int sock) |
8002af61 | 284 | { |
99443922 | 285 | char *p; |
286 | ||
ca75d7de | 287 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 288 | return p; |
289 | return xstrdup("UNKNOWN"); | |
8002af61 | 290 | } |
291 | ||
292 | char * | |
ca75d7de | 293 | get_local_name(int sock) |
8002af61 | 294 | { |
ca75d7de | 295 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 296 | } |
297 | ||
865ac82e | 298 | /* |
299 | * Returns the IP-address of the remote host as a string. The returned | |
300 | * string must not be freed. | |
301 | */ | |
5260325f | 302 | |
865ac82e | 303 | const char * |
d5bb9418 | 304 | get_remote_ipaddr(void) |
865ac82e | 305 | { |
306 | static char *canonical_host_ip = NULL; | |
307 | ||
308 | /* Check whether we have cached the ipaddr. */ | |
309 | if (canonical_host_ip == NULL) { | |
310 | if (packet_connection_is_on_socket()) { | |
311 | canonical_host_ip = | |
312 | get_peer_ipaddr(packet_get_connection_in()); | |
313 | if (canonical_host_ip == NULL) | |
2362db19 | 314 | cleanup_exit(255); |
865ac82e | 315 | } else { |
316 | /* If not on socket, return UNKNOWN. */ | |
317 | canonical_host_ip = xstrdup("UNKNOWN"); | |
318 | } | |
319 | } | |
5260325f | 320 | return canonical_host_ip; |
8efc0c15 | 321 | } |
322 | ||
46e3af7f | 323 | const char * |
c5a7d788 | 324 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 325 | { |
326 | static const char *remote = ""; | |
327 | if (utmp_len > 0) | |
c5a7d788 | 328 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 329 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
330 | remote = get_remote_ipaddr(); | |
331 | return remote; | |
332 | } | |
333 | ||
48e671d5 | 334 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 335 | |
396c147e | 336 | static int |
48e671d5 | 337 | get_sock_port(int sock, int local) |
8efc0c15 | 338 | { |
48e671d5 | 339 | struct sockaddr_storage from; |
340 | socklen_t fromlen; | |
341 | char strport[NI_MAXSERV]; | |
adc75586 | 342 | int r; |
5260325f | 343 | |
344 | /* Get IP address of client. */ | |
345 | fromlen = sizeof(from); | |
346 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 347 | if (local) { |
348 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
349 | error("getsockname failed: %.100s", strerror(errno)); | |
350 | return 0; | |
351 | } | |
352 | } else { | |
649bb60b | 353 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 354 | debug("getpeername failed: %.100s", strerror(errno)); |
29798ed0 | 355 | return -1; |
48e671d5 | 356 | } |
5260325f | 357 | } |
e7ccd20d | 358 | |
359 | /* Work around Linux IPv6 weirdness */ | |
360 | if (from.ss_family == AF_INET6) | |
361 | fromlen = sizeof(struct sockaddr_in6); | |
362 | ||
5260325f | 363 | /* Return port number. */ |
adc75586 | 364 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
365 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
366 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
367 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
48e671d5 | 368 | return atoi(strport); |
8efc0c15 | 369 | } |
370 | ||
48e671d5 | 371 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 372 | |
396c147e | 373 | static int |
48e671d5 | 374 | get_port(int local) |
8efc0c15 | 375 | { |
aa3378df | 376 | /* |
377 | * If the connection is not a socket, return 65535. This is | |
378 | * intentionally chosen to be an unprivileged port number. | |
379 | */ | |
48e671d5 | 380 | if (!packet_connection_is_on_socket()) |
5260325f | 381 | return 65535; |
8efc0c15 | 382 | |
48e671d5 | 383 | /* Get socket and return the port number. */ |
384 | return get_sock_port(packet_get_connection_in(), local); | |
385 | } | |
386 | ||
6ae2364d | 387 | int |
48e671d5 | 388 | get_peer_port(int sock) |
389 | { | |
390 | return get_sock_port(sock, 0); | |
391 | } | |
8efc0c15 | 392 | |
6ae2364d | 393 | int |
d5bb9418 | 394 | get_remote_port(void) |
48e671d5 | 395 | { |
13f2a382 | 396 | static int port = -1; |
397 | ||
398 | /* Cache to avoid getpeername() on a dead connection */ | |
399 | if (port == -1) | |
400 | port = get_port(0); | |
401 | ||
402 | return port; | |
48e671d5 | 403 | } |
404 | ||
405 | int | |
d5bb9418 | 406 | get_local_port(void) |
48e671d5 | 407 | { |
408 | return get_port(1); | |
8efc0c15 | 409 | } |