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c1cb7bae | 1 | /* $OpenBSD: canohost.c,v 1.53 2006/03/25 13:17:01 djm 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 | |
17 | #include <ctype.h> | |
8efc0c15 | 18 | |
19 | #include "packet.h" | |
20 | #include "xmalloc.h" | |
42f11eb2 | 21 | #include "log.h" |
5ca51e19 | 22 | #include "canohost.h" |
8efc0c15 | 23 | |
396c147e | 24 | static void check_ip_options(int, char *); |
61e96248 | 25 | |
aa3378df | 26 | /* |
27 | * Return the canonical name of the host at the other end of the socket. The | |
28 | * caller should free the returned string with xfree. | |
29 | */ | |
8efc0c15 | 30 | |
396c147e | 31 | static char * |
ca75d7de | 32 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 33 | { |
48e671d5 | 34 | struct sockaddr_storage from; |
35 | int i; | |
36 | socklen_t fromlen; | |
37 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 38 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 39 | |
40 | /* Get IP address of client. */ | |
41 | fromlen = sizeof(from); | |
42 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 43 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 44 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 45 | cleanup_exit(255); |
5260325f | 46 | } |
1639bb8f | 47 | |
48 | ipv64_normalise_mapped(&from, &fromlen); | |
49 | ||
e7ccd20d | 50 | if (from.ss_family == AF_INET6) |
51 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 52 | |
48e671d5 | 53 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 54 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 55 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 56 | |
d2130e1f | 57 | if (from.ss_family == AF_INET) |
58 | check_ip_options(sock, ntop); | |
59 | ||
c5a7d788 | 60 | if (!use_dns) |
61 | return xstrdup(ntop); | |
62 | ||
3a83b819 | 63 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 64 | /* Map the IP address to a host name. */ |
65 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 66 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 67 | /* Host name not found. Use ip address. */ |
61e96248 | 68 | return xstrdup(ntop); |
8efc0c15 | 69 | } |
5260325f | 70 | |
c5a7d788 | 71 | /* |
72 | * if reverse lookup result looks like a numeric hostname, | |
73 | * someone is trying to trick us by PTR record like following: | |
74 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
75 | */ | |
76 | memset(&hints, 0, sizeof(hints)); | |
77 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 78 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 79 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
80 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
81 | name, ntop); | |
82 | freeaddrinfo(ai); | |
83 | return xstrdup(ntop); | |
84 | } | |
85 | ||
61e96248 | 86 | /* |
87 | * Convert it to all lowercase (which is expected by the rest | |
88 | * of this software). | |
89 | */ | |
90 | for (i = 0; name[i]; i++) | |
91 | if (isupper(name[i])) | |
9555d258 | 92 | name[i] = (char)tolower(name[i]); |
aa3378df | 93 | /* |
61e96248 | 94 | * Map it back to an IP address and check that the given |
95 | * address actually is an address of this host. This is | |
96 | * necessary because anyone with access to a name server can | |
97 | * define arbitrary names for an IP address. Mapping from | |
98 | * name to IP address can be trusted better (but can still be | |
99 | * fooled if the intruder has access to the name server of | |
100 | * the domain). | |
aa3378df | 101 | */ |
61e96248 | 102 | memset(&hints, 0, sizeof(hints)); |
103 | hints.ai_family = from.ss_family; | |
104 | hints.ai_socktype = SOCK_STREAM; | |
105 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 106 | logit("reverse mapping checking getaddrinfo for %.700s " |
22aa23f8 | 107 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
61e96248 | 108 | return xstrdup(ntop); |
109 | } | |
110 | /* Look for the address from the list of addresses. */ | |
111 | for (ai = aitop; ai; ai = ai->ai_next) { | |
112 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
113 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
114 | (strcmp(ntop, ntop2) == 0)) | |
115 | break; | |
116 | } | |
117 | freeaddrinfo(aitop); | |
118 | /* If we reached the end of the list, the address was not there. */ | |
119 | if (!ai) { | |
120 | /* Address not found for the host name. */ | |
bbe88b6d | 121 | logit("Address %.100s maps to %.600s, but this does not " |
1908529f | 122 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
61e96248 | 123 | ntop, name); |
124 | return xstrdup(ntop); | |
8efc0c15 | 125 | } |
5260325f | 126 | return xstrdup(name); |
8efc0c15 | 127 | } |
128 | ||
61e96248 | 129 | /* |
130 | * If IP options are supported, make sure there are none (log and | |
131 | * disconnect them if any are found). Basically we are worried about | |
132 | * source routing; it can be used to pretend you are somebody | |
133 | * (ip-address) you are not. That itself may be "almost acceptable" | |
134 | * under certain circumstances, but rhosts autentication is useless | |
135 | * if source routing is accepted. Notice also that if we just dropped | |
136 | * source routing here, the other side could use IP spoofing to do | |
137 | * rest of the interaction and could still bypass security. So we | |
138 | * exit here if we detect any IP options. | |
139 | */ | |
140 | /* IPv4 only */ | |
396c147e | 141 | static void |
ca75d7de | 142 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 143 | { |
97722976 | 144 | #ifdef IP_OPTIONS |
e6fa162e | 145 | u_char options[200]; |
146 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 147 | socklen_t option_size; |
2ceb8101 | 148 | u_int i; |
149 | int ipproto; | |
61e96248 | 150 | struct protoent *ip; |
151 | ||
152 | if ((ip = getprotobyname("ip")) != NULL) | |
153 | ipproto = ip->p_proto; | |
154 | else | |
155 | ipproto = IPPROTO_IP; | |
156 | option_size = sizeof(options); | |
ca75d7de | 157 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 158 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 159 | text[0] = '\0'; |
160 | for (i = 0; i < option_size; i++) | |
161 | snprintf(text + i*3, sizeof(text) - i*3, | |
162 | " %2.2x", options[i]); | |
3a85986d | 163 | fatal("Connection from %.100s with IP options:%.800s", |
61e96248 | 164 | ipaddr, text); |
165 | } | |
97722976 | 166 | #endif /* IP_OPTIONS */ |
61e96248 | 167 | } |
168 | ||
b6610e8f | 169 | void |
1639bb8f | 170 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
171 | { | |
172 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
173 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
174 | struct in_addr inaddr; | |
175 | u_int16_t port; | |
176 | ||
d1cf9a87 | 177 | if (addr->ss_family != AF_INET6 || |
1639bb8f | 178 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
179 | return; | |
180 | ||
181 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
182 | ||
183 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
184 | port = a6->sin6_port; | |
185 | ||
186 | memset(addr, 0, sizeof(*a4)); | |
187 | ||
188 | a4->sin_family = AF_INET; | |
189 | *len = sizeof(*a4); | |
190 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
191 | a4->sin_port = port; | |
192 | } | |
193 | ||
aa3378df | 194 | /* |
195 | * Return the canonical name of the host in the other side of the current | |
196 | * connection. The host name is cached, so it is efficient to call this | |
197 | * several times. | |
198 | */ | |
8efc0c15 | 199 | |
5260325f | 200 | const char * |
c5a7d788 | 201 | get_canonical_hostname(int use_dns) |
8efc0c15 | 202 | { |
0bbbf2a4 | 203 | char *host; |
48e671d5 | 204 | static char *canonical_host_name = NULL; |
0bbbf2a4 | 205 | static char *remote_ip = NULL; |
48e671d5 | 206 | |
61e96248 | 207 | /* Check if we have previously retrieved name with same option. */ |
0bbbf2a4 | 208 | if (use_dns && canonical_host_name != NULL) |
209 | return canonical_host_name; | |
210 | if (!use_dns && remote_ip != NULL) | |
211 | return remote_ip; | |
8efc0c15 | 212 | |
5260325f | 213 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 214 | if (packet_connection_is_on_socket()) |
0bbbf2a4 | 215 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
5260325f | 216 | else |
0bbbf2a4 | 217 | host = "UNKNOWN"; |
8efc0c15 | 218 | |
0bbbf2a4 | 219 | if (use_dns) |
220 | canonical_host_name = host; | |
221 | else | |
222 | remote_ip = host; | |
223 | return host; | |
8efc0c15 | 224 | } |
225 | ||
aa3378df | 226 | /* |
649bb60b | 227 | * Returns the local/remote IP-address/hostname of socket as a string. |
228 | * The returned string must be freed. | |
aa3378df | 229 | */ |
396c147e | 230 | static char * |
ca75d7de | 231 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 232 | { |
8002af61 | 233 | struct sockaddr_storage addr; |
234 | socklen_t addrlen; | |
48e671d5 | 235 | char ntop[NI_MAXHOST]; |
adc75586 | 236 | int r; |
5260325f | 237 | |
5260325f | 238 | /* Get IP address of client. */ |
8002af61 | 239 | addrlen = sizeof(addr); |
240 | memset(&addr, 0, sizeof(addr)); | |
241 | ||
242 | if (remote) { | |
ca75d7de | 243 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 244 | < 0) |
8002af61 | 245 | return NULL; |
8002af61 | 246 | } else { |
ca75d7de | 247 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 248 | < 0) |
8002af61 | 249 | return NULL; |
5260325f | 250 | } |
e7ccd20d | 251 | |
252 | /* Work around Linux IPv6 weirdness */ | |
253 | if (addr.ss_family == AF_INET6) | |
254 | addrlen = sizeof(struct sockaddr_in6); | |
255 | ||
a56cebd3 | 256 | ipv64_normalise_mapped(&addr, &addrlen); |
257 | ||
8002af61 | 258 | /* Get the address in ascii. */ |
adc75586 | 259 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
260 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
261 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
262 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
865ac82e | 263 | return NULL; |
264 | } | |
265 | return xstrdup(ntop); | |
266 | } | |
48e671d5 | 267 | |
8002af61 | 268 | char * |
ca75d7de | 269 | get_peer_ipaddr(int sock) |
8002af61 | 270 | { |
99443922 | 271 | char *p; |
272 | ||
ca75d7de | 273 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 274 | return p; |
275 | return xstrdup("UNKNOWN"); | |
8002af61 | 276 | } |
277 | ||
278 | char * | |
ca75d7de | 279 | get_local_ipaddr(int sock) |
8002af61 | 280 | { |
99443922 | 281 | char *p; |
282 | ||
ca75d7de | 283 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 284 | return p; |
285 | return xstrdup("UNKNOWN"); | |
8002af61 | 286 | } |
287 | ||
288 | char * | |
ca75d7de | 289 | get_local_name(int sock) |
8002af61 | 290 | { |
ca75d7de | 291 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 292 | } |
293 | ||
865ac82e | 294 | /* |
295 | * Returns the IP-address of the remote host as a string. The returned | |
296 | * string must not be freed. | |
297 | */ | |
5260325f | 298 | |
865ac82e | 299 | const char * |
d5bb9418 | 300 | get_remote_ipaddr(void) |
865ac82e | 301 | { |
302 | static char *canonical_host_ip = NULL; | |
303 | ||
304 | /* Check whether we have cached the ipaddr. */ | |
305 | if (canonical_host_ip == NULL) { | |
306 | if (packet_connection_is_on_socket()) { | |
307 | canonical_host_ip = | |
308 | get_peer_ipaddr(packet_get_connection_in()); | |
309 | if (canonical_host_ip == NULL) | |
2362db19 | 310 | cleanup_exit(255); |
865ac82e | 311 | } else { |
312 | /* If not on socket, return UNKNOWN. */ | |
313 | canonical_host_ip = xstrdup("UNKNOWN"); | |
314 | } | |
315 | } | |
5260325f | 316 | return canonical_host_ip; |
8efc0c15 | 317 | } |
318 | ||
46e3af7f | 319 | const char * |
c5a7d788 | 320 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 321 | { |
322 | static const char *remote = ""; | |
323 | if (utmp_len > 0) | |
c5a7d788 | 324 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 325 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
326 | remote = get_remote_ipaddr(); | |
327 | return remote; | |
328 | } | |
329 | ||
48e671d5 | 330 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 331 | |
396c147e | 332 | static int |
48e671d5 | 333 | get_sock_port(int sock, int local) |
8efc0c15 | 334 | { |
48e671d5 | 335 | struct sockaddr_storage from; |
336 | socklen_t fromlen; | |
337 | char strport[NI_MAXSERV]; | |
adc75586 | 338 | int r; |
5260325f | 339 | |
340 | /* Get IP address of client. */ | |
341 | fromlen = sizeof(from); | |
342 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 343 | if (local) { |
344 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
345 | error("getsockname failed: %.100s", strerror(errno)); | |
346 | return 0; | |
347 | } | |
348 | } else { | |
649bb60b | 349 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 350 | debug("getpeername failed: %.100s", strerror(errno)); |
29798ed0 | 351 | return -1; |
48e671d5 | 352 | } |
5260325f | 353 | } |
e7ccd20d | 354 | |
355 | /* Work around Linux IPv6 weirdness */ | |
356 | if (from.ss_family == AF_INET6) | |
357 | fromlen = sizeof(struct sockaddr_in6); | |
358 | ||
5260325f | 359 | /* Return port number. */ |
adc75586 | 360 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
361 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
362 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
363 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
48e671d5 | 364 | return atoi(strport); |
8efc0c15 | 365 | } |
366 | ||
48e671d5 | 367 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 368 | |
396c147e | 369 | static int |
48e671d5 | 370 | get_port(int local) |
8efc0c15 | 371 | { |
aa3378df | 372 | /* |
373 | * If the connection is not a socket, return 65535. This is | |
374 | * intentionally chosen to be an unprivileged port number. | |
375 | */ | |
48e671d5 | 376 | if (!packet_connection_is_on_socket()) |
5260325f | 377 | return 65535; |
8efc0c15 | 378 | |
48e671d5 | 379 | /* Get socket and return the port number. */ |
380 | return get_sock_port(packet_get_connection_in(), local); | |
381 | } | |
382 | ||
6ae2364d | 383 | int |
48e671d5 | 384 | get_peer_port(int sock) |
385 | { | |
386 | return get_sock_port(sock, 0); | |
387 | } | |
8efc0c15 | 388 | |
6ae2364d | 389 | int |
d5bb9418 | 390 | get_remote_port(void) |
48e671d5 | 391 | { |
13f2a382 | 392 | static int port = -1; |
393 | ||
394 | /* Cache to avoid getpeername() on a dead connection */ | |
395 | if (port == -1) | |
396 | port = get_port(0); | |
397 | ||
398 | return port; | |
48e671d5 | 399 | } |
400 | ||
401 | int | |
d5bb9418 | 402 | get_local_port(void) |
48e671d5 | 403 | { |
404 | return get_port(1); | |
8efc0c15 | 405 | } |