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c8dfff33 | 1 | /* $OpenBSD: canohost.c,v 1.57 2006/07/12 22:28:51 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> |
c8dfff33 | 24 | #if defined(HAVE_NETDB_H) |
25 | # include <netdb.h> | |
26 | #endif | |
8efc0c15 | 27 | |
28 | #include "packet.h" | |
29 | #include "xmalloc.h" | |
42f11eb2 | 30 | #include "log.h" |
5ca51e19 | 31 | #include "canohost.h" |
8efc0c15 | 32 | |
396c147e | 33 | static void check_ip_options(int, char *); |
61e96248 | 34 | |
aa3378df | 35 | /* |
36 | * Return the canonical name of the host at the other end of the socket. The | |
37 | * caller should free the returned string with xfree. | |
38 | */ | |
8efc0c15 | 39 | |
396c147e | 40 | static char * |
ca75d7de | 41 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 42 | { |
48e671d5 | 43 | struct sockaddr_storage from; |
44 | int i; | |
45 | socklen_t fromlen; | |
46 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 47 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 48 | |
49 | /* Get IP address of client. */ | |
50 | fromlen = sizeof(from); | |
51 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 52 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 53 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 54 | cleanup_exit(255); |
5260325f | 55 | } |
1639bb8f | 56 | |
88680c8b | 57 | if (from.ss_family == AF_INET) |
58 | check_ip_options(sock, ntop); | |
59 | ||
1639bb8f | 60 | ipv64_normalise_mapped(&from, &fromlen); |
61 | ||
e7ccd20d | 62 | if (from.ss_family == AF_INET6) |
63 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 64 | |
48e671d5 | 65 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 66 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 67 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 68 | |
c5a7d788 | 69 | if (!use_dns) |
70 | return xstrdup(ntop); | |
71 | ||
3a83b819 | 72 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 73 | /* Map the IP address to a host name. */ |
74 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 75 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 76 | /* Host name not found. Use ip address. */ |
61e96248 | 77 | return xstrdup(ntop); |
8efc0c15 | 78 | } |
5260325f | 79 | |
c5a7d788 | 80 | /* |
81 | * if reverse lookup result looks like a numeric hostname, | |
82 | * someone is trying to trick us by PTR record like following: | |
83 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
84 | */ | |
85 | memset(&hints, 0, sizeof(hints)); | |
86 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 87 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 88 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
89 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
90 | name, ntop); | |
91 | freeaddrinfo(ai); | |
92 | return xstrdup(ntop); | |
93 | } | |
94 | ||
61e96248 | 95 | /* |
96 | * Convert it to all lowercase (which is expected by the rest | |
97 | * of this software). | |
98 | */ | |
99 | for (i = 0; name[i]; i++) | |
100 | if (isupper(name[i])) | |
9555d258 | 101 | name[i] = (char)tolower(name[i]); |
aa3378df | 102 | /* |
61e96248 | 103 | * Map it back to an IP address and check that the given |
104 | * address actually is an address of this host. This is | |
105 | * necessary because anyone with access to a name server can | |
106 | * define arbitrary names for an IP address. Mapping from | |
107 | * name to IP address can be trusted better (but can still be | |
108 | * fooled if the intruder has access to the name server of | |
109 | * the domain). | |
aa3378df | 110 | */ |
61e96248 | 111 | memset(&hints, 0, sizeof(hints)); |
112 | hints.ai_family = from.ss_family; | |
113 | hints.ai_socktype = SOCK_STREAM; | |
114 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 115 | logit("reverse mapping checking getaddrinfo for %.700s " |
22aa23f8 | 116 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
61e96248 | 117 | return xstrdup(ntop); |
118 | } | |
119 | /* Look for the address from the list of addresses. */ | |
120 | for (ai = aitop; ai; ai = ai->ai_next) { | |
121 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
122 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
123 | (strcmp(ntop, ntop2) == 0)) | |
124 | break; | |
125 | } | |
126 | freeaddrinfo(aitop); | |
127 | /* If we reached the end of the list, the address was not there. */ | |
128 | if (!ai) { | |
129 | /* Address not found for the host name. */ | |
bbe88b6d | 130 | logit("Address %.100s maps to %.600s, but this does not " |
1908529f | 131 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
61e96248 | 132 | ntop, name); |
133 | return xstrdup(ntop); | |
8efc0c15 | 134 | } |
5260325f | 135 | return xstrdup(name); |
8efc0c15 | 136 | } |
137 | ||
61e96248 | 138 | /* |
139 | * If IP options are supported, make sure there are none (log and | |
140 | * disconnect them if any are found). Basically we are worried about | |
141 | * source routing; it can be used to pretend you are somebody | |
142 | * (ip-address) you are not. That itself may be "almost acceptable" | |
143 | * under certain circumstances, but rhosts autentication is useless | |
144 | * if source routing is accepted. Notice also that if we just dropped | |
145 | * source routing here, the other side could use IP spoofing to do | |
146 | * rest of the interaction and could still bypass security. So we | |
147 | * exit here if we detect any IP options. | |
148 | */ | |
149 | /* IPv4 only */ | |
396c147e | 150 | static void |
ca75d7de | 151 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 152 | { |
97722976 | 153 | #ifdef IP_OPTIONS |
e6fa162e | 154 | u_char options[200]; |
155 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 156 | socklen_t option_size; |
2ceb8101 | 157 | u_int i; |
158 | int ipproto; | |
61e96248 | 159 | struct protoent *ip; |
160 | ||
161 | if ((ip = getprotobyname("ip")) != NULL) | |
162 | ipproto = ip->p_proto; | |
163 | else | |
164 | ipproto = IPPROTO_IP; | |
165 | option_size = sizeof(options); | |
ca75d7de | 166 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 167 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 168 | text[0] = '\0'; |
169 | for (i = 0; i < option_size; i++) | |
170 | snprintf(text + i*3, sizeof(text) - i*3, | |
171 | " %2.2x", options[i]); | |
3a85986d | 172 | fatal("Connection from %.100s with IP options:%.800s", |
61e96248 | 173 | ipaddr, text); |
174 | } | |
97722976 | 175 | #endif /* IP_OPTIONS */ |
61e96248 | 176 | } |
177 | ||
b6610e8f | 178 | void |
1639bb8f | 179 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
180 | { | |
181 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
182 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
183 | struct in_addr inaddr; | |
184 | u_int16_t port; | |
185 | ||
d1cf9a87 | 186 | if (addr->ss_family != AF_INET6 || |
1639bb8f | 187 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
188 | return; | |
189 | ||
190 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
191 | ||
192 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
193 | port = a6->sin6_port; | |
194 | ||
195 | memset(addr, 0, sizeof(*a4)); | |
196 | ||
197 | a4->sin_family = AF_INET; | |
198 | *len = sizeof(*a4); | |
199 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
200 | a4->sin_port = port; | |
201 | } | |
202 | ||
aa3378df | 203 | /* |
204 | * Return the canonical name of the host in the other side of the current | |
205 | * connection. The host name is cached, so it is efficient to call this | |
206 | * several times. | |
207 | */ | |
8efc0c15 | 208 | |
5260325f | 209 | const char * |
c5a7d788 | 210 | get_canonical_hostname(int use_dns) |
8efc0c15 | 211 | { |
0bbbf2a4 | 212 | char *host; |
48e671d5 | 213 | static char *canonical_host_name = NULL; |
0bbbf2a4 | 214 | static char *remote_ip = NULL; |
48e671d5 | 215 | |
61e96248 | 216 | /* Check if we have previously retrieved name with same option. */ |
0bbbf2a4 | 217 | if (use_dns && canonical_host_name != NULL) |
218 | return canonical_host_name; | |
219 | if (!use_dns && remote_ip != NULL) | |
220 | return remote_ip; | |
8efc0c15 | 221 | |
5260325f | 222 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 223 | if (packet_connection_is_on_socket()) |
0bbbf2a4 | 224 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
5260325f | 225 | else |
0bbbf2a4 | 226 | host = "UNKNOWN"; |
8efc0c15 | 227 | |
0bbbf2a4 | 228 | if (use_dns) |
229 | canonical_host_name = host; | |
230 | else | |
231 | remote_ip = host; | |
232 | return host; | |
8efc0c15 | 233 | } |
234 | ||
aa3378df | 235 | /* |
649bb60b | 236 | * Returns the local/remote IP-address/hostname of socket as a string. |
237 | * The returned string must be freed. | |
aa3378df | 238 | */ |
396c147e | 239 | static char * |
ca75d7de | 240 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 241 | { |
8002af61 | 242 | struct sockaddr_storage addr; |
243 | socklen_t addrlen; | |
48e671d5 | 244 | char ntop[NI_MAXHOST]; |
adc75586 | 245 | int r; |
5260325f | 246 | |
5260325f | 247 | /* Get IP address of client. */ |
8002af61 | 248 | addrlen = sizeof(addr); |
249 | memset(&addr, 0, sizeof(addr)); | |
250 | ||
251 | if (remote) { | |
ca75d7de | 252 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 253 | < 0) |
8002af61 | 254 | return NULL; |
8002af61 | 255 | } else { |
ca75d7de | 256 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 257 | < 0) |
8002af61 | 258 | return NULL; |
5260325f | 259 | } |
e7ccd20d | 260 | |
261 | /* Work around Linux IPv6 weirdness */ | |
262 | if (addr.ss_family == AF_INET6) | |
263 | addrlen = sizeof(struct sockaddr_in6); | |
264 | ||
a56cebd3 | 265 | ipv64_normalise_mapped(&addr, &addrlen); |
266 | ||
8002af61 | 267 | /* Get the address in ascii. */ |
adc75586 | 268 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
269 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
270 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
271 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
865ac82e | 272 | return NULL; |
273 | } | |
274 | return xstrdup(ntop); | |
275 | } | |
48e671d5 | 276 | |
8002af61 | 277 | char * |
ca75d7de | 278 | get_peer_ipaddr(int sock) |
8002af61 | 279 | { |
99443922 | 280 | char *p; |
281 | ||
ca75d7de | 282 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 283 | return p; |
284 | return xstrdup("UNKNOWN"); | |
8002af61 | 285 | } |
286 | ||
287 | char * | |
ca75d7de | 288 | get_local_ipaddr(int sock) |
8002af61 | 289 | { |
99443922 | 290 | char *p; |
291 | ||
ca75d7de | 292 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 293 | return p; |
294 | return xstrdup("UNKNOWN"); | |
8002af61 | 295 | } |
296 | ||
297 | char * | |
ca75d7de | 298 | get_local_name(int sock) |
8002af61 | 299 | { |
ca75d7de | 300 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 301 | } |
302 | ||
865ac82e | 303 | /* |
304 | * Returns the IP-address of the remote host as a string. The returned | |
305 | * string must not be freed. | |
306 | */ | |
5260325f | 307 | |
865ac82e | 308 | const char * |
d5bb9418 | 309 | get_remote_ipaddr(void) |
865ac82e | 310 | { |
311 | static char *canonical_host_ip = NULL; | |
312 | ||
313 | /* Check whether we have cached the ipaddr. */ | |
314 | if (canonical_host_ip == NULL) { | |
315 | if (packet_connection_is_on_socket()) { | |
316 | canonical_host_ip = | |
317 | get_peer_ipaddr(packet_get_connection_in()); | |
318 | if (canonical_host_ip == NULL) | |
2362db19 | 319 | cleanup_exit(255); |
865ac82e | 320 | } else { |
321 | /* If not on socket, return UNKNOWN. */ | |
322 | canonical_host_ip = xstrdup("UNKNOWN"); | |
323 | } | |
324 | } | |
5260325f | 325 | return canonical_host_ip; |
8efc0c15 | 326 | } |
327 | ||
46e3af7f | 328 | const char * |
c5a7d788 | 329 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 330 | { |
331 | static const char *remote = ""; | |
332 | if (utmp_len > 0) | |
c5a7d788 | 333 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 334 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
335 | remote = get_remote_ipaddr(); | |
336 | return remote; | |
337 | } | |
338 | ||
48e671d5 | 339 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 340 | |
396c147e | 341 | static int |
48e671d5 | 342 | get_sock_port(int sock, int local) |
8efc0c15 | 343 | { |
48e671d5 | 344 | struct sockaddr_storage from; |
345 | socklen_t fromlen; | |
346 | char strport[NI_MAXSERV]; | |
adc75586 | 347 | int r; |
5260325f | 348 | |
349 | /* Get IP address of client. */ | |
350 | fromlen = sizeof(from); | |
351 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 352 | if (local) { |
353 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
354 | error("getsockname failed: %.100s", strerror(errno)); | |
355 | return 0; | |
356 | } | |
357 | } else { | |
649bb60b | 358 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 359 | debug("getpeername failed: %.100s", strerror(errno)); |
29798ed0 | 360 | return -1; |
48e671d5 | 361 | } |
5260325f | 362 | } |
e7ccd20d | 363 | |
364 | /* Work around Linux IPv6 weirdness */ | |
365 | if (from.ss_family == AF_INET6) | |
366 | fromlen = sizeof(struct sockaddr_in6); | |
367 | ||
5260325f | 368 | /* Return port number. */ |
adc75586 | 369 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
370 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
371 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
372 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
48e671d5 | 373 | return atoi(strport); |
8efc0c15 | 374 | } |
375 | ||
48e671d5 | 376 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 377 | |
396c147e | 378 | static int |
48e671d5 | 379 | get_port(int local) |
8efc0c15 | 380 | { |
aa3378df | 381 | /* |
382 | * If the connection is not a socket, return 65535. This is | |
383 | * intentionally chosen to be an unprivileged port number. | |
384 | */ | |
48e671d5 | 385 | if (!packet_connection_is_on_socket()) |
5260325f | 386 | return 65535; |
8efc0c15 | 387 | |
48e671d5 | 388 | /* Get socket and return the port number. */ |
389 | return get_sock_port(packet_get_connection_in(), local); | |
390 | } | |
391 | ||
6ae2364d | 392 | int |
48e671d5 | 393 | get_peer_port(int sock) |
394 | { | |
395 | return get_sock_port(sock, 0); | |
396 | } | |
8efc0c15 | 397 | |
6ae2364d | 398 | int |
d5bb9418 | 399 | get_remote_port(void) |
48e671d5 | 400 | { |
13f2a382 | 401 | static int port = -1; |
402 | ||
403 | /* Cache to avoid getpeername() on a dead connection */ | |
404 | if (port == -1) | |
405 | port = get_port(0); | |
406 | ||
407 | return port; | |
48e671d5 | 408 | } |
409 | ||
410 | int | |
d5bb9418 | 411 | get_local_port(void) |
48e671d5 | 412 | { |
413 | return get_port(1); | |
8efc0c15 | 414 | } |