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00146caa | 1 | /* $OpenBSD: canohost.c,v 1.58 2006/07/22 20:48:22 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> |
00146caa | 25 | #include <string.h> |
8efc0c15 | 26 | |
27 | #include "packet.h" | |
28 | #include "xmalloc.h" | |
42f11eb2 | 29 | #include "log.h" |
5ca51e19 | 30 | #include "canohost.h" |
8efc0c15 | 31 | |
396c147e | 32 | static void check_ip_options(int, char *); |
61e96248 | 33 | |
aa3378df | 34 | /* |
35 | * Return the canonical name of the host at the other end of the socket. The | |
36 | * caller should free the returned string with xfree. | |
37 | */ | |
8efc0c15 | 38 | |
396c147e | 39 | static char * |
ca75d7de | 40 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 41 | { |
48e671d5 | 42 | struct sockaddr_storage from; |
43 | int i; | |
44 | socklen_t fromlen; | |
45 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 46 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 47 | |
48 | /* Get IP address of client. */ | |
49 | fromlen = sizeof(from); | |
50 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 51 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 52 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 53 | cleanup_exit(255); |
5260325f | 54 | } |
1639bb8f | 55 | |
88680c8b | 56 | if (from.ss_family == AF_INET) |
57 | check_ip_options(sock, ntop); | |
58 | ||
1639bb8f | 59 | ipv64_normalise_mapped(&from, &fromlen); |
60 | ||
e7ccd20d | 61 | if (from.ss_family == AF_INET6) |
62 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 63 | |
48e671d5 | 64 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 65 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 66 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 67 | |
c5a7d788 | 68 | if (!use_dns) |
69 | return xstrdup(ntop); | |
70 | ||
3a83b819 | 71 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 72 | /* Map the IP address to a host name. */ |
73 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 74 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 75 | /* Host name not found. Use ip address. */ |
61e96248 | 76 | return xstrdup(ntop); |
8efc0c15 | 77 | } |
5260325f | 78 | |
c5a7d788 | 79 | /* |
80 | * if reverse lookup result looks like a numeric hostname, | |
81 | * someone is trying to trick us by PTR record like following: | |
82 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
83 | */ | |
84 | memset(&hints, 0, sizeof(hints)); | |
85 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 86 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 87 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
88 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
89 | name, ntop); | |
90 | freeaddrinfo(ai); | |
91 | return xstrdup(ntop); | |
92 | } | |
93 | ||
61e96248 | 94 | /* |
95 | * Convert it to all lowercase (which is expected by the rest | |
96 | * of this software). | |
97 | */ | |
98 | for (i = 0; name[i]; i++) | |
99 | if (isupper(name[i])) | |
9555d258 | 100 | name[i] = (char)tolower(name[i]); |
aa3378df | 101 | /* |
61e96248 | 102 | * Map it back to an IP address and check that the given |
103 | * address actually is an address of this host. This is | |
104 | * necessary because anyone with access to a name server can | |
105 | * define arbitrary names for an IP address. Mapping from | |
106 | * name to IP address can be trusted better (but can still be | |
107 | * fooled if the intruder has access to the name server of | |
108 | * the domain). | |
aa3378df | 109 | */ |
61e96248 | 110 | memset(&hints, 0, sizeof(hints)); |
111 | hints.ai_family = from.ss_family; | |
112 | hints.ai_socktype = SOCK_STREAM; | |
113 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 114 | logit("reverse mapping checking getaddrinfo for %.700s " |
22aa23f8 | 115 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
61e96248 | 116 | return xstrdup(ntop); |
117 | } | |
118 | /* Look for the address from the list of addresses. */ | |
119 | for (ai = aitop; ai; ai = ai->ai_next) { | |
120 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
121 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
122 | (strcmp(ntop, ntop2) == 0)) | |
123 | break; | |
124 | } | |
125 | freeaddrinfo(aitop); | |
126 | /* If we reached the end of the list, the address was not there. */ | |
127 | if (!ai) { | |
128 | /* Address not found for the host name. */ | |
bbe88b6d | 129 | logit("Address %.100s maps to %.600s, but this does not " |
1908529f | 130 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
61e96248 | 131 | ntop, name); |
132 | return xstrdup(ntop); | |
8efc0c15 | 133 | } |
5260325f | 134 | return xstrdup(name); |
8efc0c15 | 135 | } |
136 | ||
61e96248 | 137 | /* |
138 | * If IP options are supported, make sure there are none (log and | |
139 | * disconnect them if any are found). Basically we are worried about | |
140 | * source routing; it can be used to pretend you are somebody | |
141 | * (ip-address) you are not. That itself may be "almost acceptable" | |
142 | * under certain circumstances, but rhosts autentication is useless | |
143 | * if source routing is accepted. Notice also that if we just dropped | |
144 | * source routing here, the other side could use IP spoofing to do | |
145 | * rest of the interaction and could still bypass security. So we | |
146 | * exit here if we detect any IP options. | |
147 | */ | |
148 | /* IPv4 only */ | |
396c147e | 149 | static void |
ca75d7de | 150 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 151 | { |
97722976 | 152 | #ifdef IP_OPTIONS |
e6fa162e | 153 | u_char options[200]; |
154 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 155 | socklen_t option_size; |
2ceb8101 | 156 | u_int i; |
157 | int ipproto; | |
61e96248 | 158 | struct protoent *ip; |
159 | ||
160 | if ((ip = getprotobyname("ip")) != NULL) | |
161 | ipproto = ip->p_proto; | |
162 | else | |
163 | ipproto = IPPROTO_IP; | |
164 | option_size = sizeof(options); | |
ca75d7de | 165 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 166 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 167 | text[0] = '\0'; |
168 | for (i = 0; i < option_size; i++) | |
169 | snprintf(text + i*3, sizeof(text) - i*3, | |
170 | " %2.2x", options[i]); | |
3a85986d | 171 | fatal("Connection from %.100s with IP options:%.800s", |
61e96248 | 172 | ipaddr, text); |
173 | } | |
97722976 | 174 | #endif /* IP_OPTIONS */ |
61e96248 | 175 | } |
176 | ||
b6610e8f | 177 | void |
1639bb8f | 178 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
179 | { | |
180 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
181 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
182 | struct in_addr inaddr; | |
183 | u_int16_t port; | |
184 | ||
d1cf9a87 | 185 | if (addr->ss_family != AF_INET6 || |
1639bb8f | 186 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
187 | return; | |
188 | ||
189 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
190 | ||
191 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
192 | port = a6->sin6_port; | |
193 | ||
194 | memset(addr, 0, sizeof(*a4)); | |
195 | ||
196 | a4->sin_family = AF_INET; | |
197 | *len = sizeof(*a4); | |
198 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
199 | a4->sin_port = port; | |
200 | } | |
201 | ||
aa3378df | 202 | /* |
203 | * Return the canonical name of the host in the other side of the current | |
204 | * connection. The host name is cached, so it is efficient to call this | |
205 | * several times. | |
206 | */ | |
8efc0c15 | 207 | |
5260325f | 208 | const char * |
c5a7d788 | 209 | get_canonical_hostname(int use_dns) |
8efc0c15 | 210 | { |
0bbbf2a4 | 211 | char *host; |
48e671d5 | 212 | static char *canonical_host_name = NULL; |
0bbbf2a4 | 213 | static char *remote_ip = NULL; |
48e671d5 | 214 | |
61e96248 | 215 | /* Check if we have previously retrieved name with same option. */ |
0bbbf2a4 | 216 | if (use_dns && canonical_host_name != NULL) |
217 | return canonical_host_name; | |
218 | if (!use_dns && remote_ip != NULL) | |
219 | return remote_ip; | |
8efc0c15 | 220 | |
5260325f | 221 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 222 | if (packet_connection_is_on_socket()) |
0bbbf2a4 | 223 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
5260325f | 224 | else |
0bbbf2a4 | 225 | host = "UNKNOWN"; |
8efc0c15 | 226 | |
0bbbf2a4 | 227 | if (use_dns) |
228 | canonical_host_name = host; | |
229 | else | |
230 | remote_ip = host; | |
231 | return host; | |
8efc0c15 | 232 | } |
233 | ||
aa3378df | 234 | /* |
649bb60b | 235 | * Returns the local/remote IP-address/hostname of socket as a string. |
236 | * The returned string must be freed. | |
aa3378df | 237 | */ |
396c147e | 238 | static char * |
ca75d7de | 239 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 240 | { |
8002af61 | 241 | struct sockaddr_storage addr; |
242 | socklen_t addrlen; | |
48e671d5 | 243 | char ntop[NI_MAXHOST]; |
adc75586 | 244 | int r; |
5260325f | 245 | |
5260325f | 246 | /* Get IP address of client. */ |
8002af61 | 247 | addrlen = sizeof(addr); |
248 | memset(&addr, 0, sizeof(addr)); | |
249 | ||
250 | if (remote) { | |
ca75d7de | 251 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 252 | < 0) |
8002af61 | 253 | return NULL; |
8002af61 | 254 | } else { |
ca75d7de | 255 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 256 | < 0) |
8002af61 | 257 | return NULL; |
5260325f | 258 | } |
e7ccd20d | 259 | |
260 | /* Work around Linux IPv6 weirdness */ | |
261 | if (addr.ss_family == AF_INET6) | |
262 | addrlen = sizeof(struct sockaddr_in6); | |
263 | ||
a56cebd3 | 264 | ipv64_normalise_mapped(&addr, &addrlen); |
265 | ||
8002af61 | 266 | /* Get the address in ascii. */ |
adc75586 | 267 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
268 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
269 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
270 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
865ac82e | 271 | return NULL; |
272 | } | |
273 | return xstrdup(ntop); | |
274 | } | |
48e671d5 | 275 | |
8002af61 | 276 | char * |
ca75d7de | 277 | get_peer_ipaddr(int sock) |
8002af61 | 278 | { |
99443922 | 279 | char *p; |
280 | ||
ca75d7de | 281 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 282 | return p; |
283 | return xstrdup("UNKNOWN"); | |
8002af61 | 284 | } |
285 | ||
286 | char * | |
ca75d7de | 287 | get_local_ipaddr(int sock) |
8002af61 | 288 | { |
99443922 | 289 | char *p; |
290 | ||
ca75d7de | 291 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 292 | return p; |
293 | return xstrdup("UNKNOWN"); | |
8002af61 | 294 | } |
295 | ||
296 | char * | |
ca75d7de | 297 | get_local_name(int sock) |
8002af61 | 298 | { |
ca75d7de | 299 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 300 | } |
301 | ||
865ac82e | 302 | /* |
303 | * Returns the IP-address of the remote host as a string. The returned | |
304 | * string must not be freed. | |
305 | */ | |
5260325f | 306 | |
865ac82e | 307 | const char * |
d5bb9418 | 308 | get_remote_ipaddr(void) |
865ac82e | 309 | { |
310 | static char *canonical_host_ip = NULL; | |
311 | ||
312 | /* Check whether we have cached the ipaddr. */ | |
313 | if (canonical_host_ip == NULL) { | |
314 | if (packet_connection_is_on_socket()) { | |
315 | canonical_host_ip = | |
316 | get_peer_ipaddr(packet_get_connection_in()); | |
317 | if (canonical_host_ip == NULL) | |
2362db19 | 318 | cleanup_exit(255); |
865ac82e | 319 | } else { |
320 | /* If not on socket, return UNKNOWN. */ | |
321 | canonical_host_ip = xstrdup("UNKNOWN"); | |
322 | } | |
323 | } | |
5260325f | 324 | return canonical_host_ip; |
8efc0c15 | 325 | } |
326 | ||
46e3af7f | 327 | const char * |
c5a7d788 | 328 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 329 | { |
330 | static const char *remote = ""; | |
331 | if (utmp_len > 0) | |
c5a7d788 | 332 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 333 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
334 | remote = get_remote_ipaddr(); | |
335 | return remote; | |
336 | } | |
337 | ||
48e671d5 | 338 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 339 | |
396c147e | 340 | static int |
48e671d5 | 341 | get_sock_port(int sock, int local) |
8efc0c15 | 342 | { |
48e671d5 | 343 | struct sockaddr_storage from; |
344 | socklen_t fromlen; | |
345 | char strport[NI_MAXSERV]; | |
adc75586 | 346 | int r; |
5260325f | 347 | |
348 | /* Get IP address of client. */ | |
349 | fromlen = sizeof(from); | |
350 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 351 | if (local) { |
352 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
353 | error("getsockname failed: %.100s", strerror(errno)); | |
354 | return 0; | |
355 | } | |
356 | } else { | |
649bb60b | 357 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 358 | debug("getpeername failed: %.100s", strerror(errno)); |
29798ed0 | 359 | return -1; |
48e671d5 | 360 | } |
5260325f | 361 | } |
e7ccd20d | 362 | |
363 | /* Work around Linux IPv6 weirdness */ | |
364 | if (from.ss_family == AF_INET6) | |
365 | fromlen = sizeof(struct sockaddr_in6); | |
366 | ||
5260325f | 367 | /* Return port number. */ |
adc75586 | 368 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
369 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
370 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
371 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
48e671d5 | 372 | return atoi(strport); |
8efc0c15 | 373 | } |
374 | ||
48e671d5 | 375 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 376 | |
396c147e | 377 | static int |
48e671d5 | 378 | get_port(int local) |
8efc0c15 | 379 | { |
aa3378df | 380 | /* |
381 | * If the connection is not a socket, return 65535. This is | |
382 | * intentionally chosen to be an unprivileged port number. | |
383 | */ | |
48e671d5 | 384 | if (!packet_connection_is_on_socket()) |
5260325f | 385 | return 65535; |
8efc0c15 | 386 | |
48e671d5 | 387 | /* Get socket and return the port number. */ |
388 | return get_sock_port(packet_get_connection_in(), local); | |
389 | } | |
390 | ||
6ae2364d | 391 | int |
48e671d5 | 392 | get_peer_port(int sock) |
393 | { | |
394 | return get_sock_port(sock, 0); | |
395 | } | |
8efc0c15 | 396 | |
6ae2364d | 397 | int |
d5bb9418 | 398 | get_remote_port(void) |
48e671d5 | 399 | { |
13f2a382 | 400 | static int port = -1; |
401 | ||
402 | /* Cache to avoid getpeername() on a dead connection */ | |
403 | if (port == -1) | |
404 | port = get_port(0); | |
405 | ||
406 | return port; | |
48e671d5 | 407 | } |
408 | ||
409 | int | |
d5bb9418 | 410 | get_local_port(void) |
48e671d5 | 411 | { |
412 | return get_port(1); | |
8efc0c15 | 413 | } |