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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
4 | * All rights reserved | |
5260325f | 5 | * Functions for returning the canonical host name of the remote site. |
6ae2364d | 6 | * |
bcbf86ec | 7 | * As far as I am concerned, the code I have written for this software |
8 | * can be used freely for any purpose. Any derived versions of this | |
9 | * software must be clearly marked as such, and if the derived work is | |
10 | * incompatible with the protocol description in the RFC file, it must be | |
11 | * called by a name other than "ssh" or "Secure Shell". | |
5260325f | 12 | */ |
8efc0c15 | 13 | |
14 | #include "includes.h" | |
adc75586 | 15 | RCSID("$OpenBSD: canohost.c,v 1.42 2005/02/18 03:05:53 djm Exp $"); |
8efc0c15 | 16 | |
17 | #include "packet.h" | |
18 | #include "xmalloc.h" | |
42f11eb2 | 19 | #include "log.h" |
5ca51e19 | 20 | #include "canohost.h" |
8efc0c15 | 21 | |
396c147e | 22 | static void check_ip_options(int, char *); |
61e96248 | 23 | |
aa3378df | 24 | /* |
25 | * Return the canonical name of the host at the other end of the socket. The | |
26 | * caller should free the returned string with xfree. | |
27 | */ | |
8efc0c15 | 28 | |
396c147e | 29 | static char * |
ca75d7de | 30 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 31 | { |
48e671d5 | 32 | struct sockaddr_storage from; |
33 | int i; | |
34 | socklen_t fromlen; | |
35 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 36 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 37 | |
38 | /* Get IP address of client. */ | |
39 | fromlen = sizeof(from); | |
40 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 41 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 42 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 43 | cleanup_exit(255); |
5260325f | 44 | } |
1639bb8f | 45 | |
35087869 | 46 | if (from.ss_family == AF_INET) |
ca75d7de | 47 | check_ip_options(sock, ntop); |
35087869 | 48 | |
1639bb8f | 49 | ipv64_normalise_mapped(&from, &fromlen); |
50 | ||
e7ccd20d | 51 | if (from.ss_family == AF_INET6) |
52 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 53 | |
48e671d5 | 54 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 55 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 56 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 57 | |
c5a7d788 | 58 | if (!use_dns) |
59 | return xstrdup(ntop); | |
60 | ||
3a83b819 | 61 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 62 | /* Map the IP address to a host name. */ |
63 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 64 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 65 | /* Host name not found. Use ip address. */ |
61e96248 | 66 | return xstrdup(ntop); |
8efc0c15 | 67 | } |
5260325f | 68 | |
c5a7d788 | 69 | /* |
70 | * if reverse lookup result looks like a numeric hostname, | |
71 | * someone is trying to trick us by PTR record like following: | |
72 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
73 | */ | |
74 | memset(&hints, 0, sizeof(hints)); | |
75 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 76 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 77 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
78 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
79 | name, ntop); | |
80 | freeaddrinfo(ai); | |
81 | return xstrdup(ntop); | |
82 | } | |
83 | ||
61e96248 | 84 | /* |
85 | * Convert it to all lowercase (which is expected by the rest | |
86 | * of this software). | |
87 | */ | |
88 | for (i = 0; name[i]; i++) | |
89 | if (isupper(name[i])) | |
90 | name[i] = tolower(name[i]); | |
aa3378df | 91 | /* |
61e96248 | 92 | * Map it back to an IP address and check that the given |
93 | * address actually is an address of this host. This is | |
94 | * necessary because anyone with access to a name server can | |
95 | * define arbitrary names for an IP address. Mapping from | |
96 | * name to IP address can be trusted better (but can still be | |
97 | * fooled if the intruder has access to the name server of | |
98 | * the domain). | |
aa3378df | 99 | */ |
61e96248 | 100 | memset(&hints, 0, sizeof(hints)); |
101 | hints.ai_family = from.ss_family; | |
102 | hints.ai_socktype = SOCK_STREAM; | |
103 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 104 | logit("reverse mapping checking getaddrinfo for %.700s " |
61e96248 | 105 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); |
106 | return xstrdup(ntop); | |
107 | } | |
108 | /* Look for the address from the list of addresses. */ | |
109 | for (ai = aitop; ai; ai = ai->ai_next) { | |
110 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
111 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
112 | (strcmp(ntop, ntop2) == 0)) | |
113 | break; | |
114 | } | |
115 | freeaddrinfo(aitop); | |
116 | /* If we reached the end of the list, the address was not there. */ | |
117 | if (!ai) { | |
118 | /* Address not found for the host name. */ | |
bbe88b6d | 119 | logit("Address %.100s maps to %.600s, but this does not " |
61e96248 | 120 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
121 | ntop, name); | |
122 | return xstrdup(ntop); | |
8efc0c15 | 123 | } |
5260325f | 124 | return xstrdup(name); |
8efc0c15 | 125 | } |
126 | ||
61e96248 | 127 | /* |
128 | * If IP options are supported, make sure there are none (log and | |
129 | * disconnect them if any are found). Basically we are worried about | |
130 | * source routing; it can be used to pretend you are somebody | |
131 | * (ip-address) you are not. That itself may be "almost acceptable" | |
132 | * under certain circumstances, but rhosts autentication is useless | |
133 | * if source routing is accepted. Notice also that if we just dropped | |
134 | * source routing here, the other side could use IP spoofing to do | |
135 | * rest of the interaction and could still bypass security. So we | |
136 | * exit here if we detect any IP options. | |
137 | */ | |
138 | /* IPv4 only */ | |
396c147e | 139 | static void |
ca75d7de | 140 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 141 | { |
97722976 | 142 | #ifdef IP_OPTIONS |
e6fa162e | 143 | u_char options[200]; |
144 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 145 | socklen_t option_size; |
e6fa162e | 146 | int i, ipproto; |
61e96248 | 147 | struct protoent *ip; |
148 | ||
149 | if ((ip = getprotobyname("ip")) != NULL) | |
150 | ipproto = ip->p_proto; | |
151 | else | |
152 | ipproto = IPPROTO_IP; | |
153 | option_size = sizeof(options); | |
ca75d7de | 154 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 155 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 156 | text[0] = '\0'; |
157 | for (i = 0; i < option_size; i++) | |
158 | snprintf(text + i*3, sizeof(text) - i*3, | |
159 | " %2.2x", options[i]); | |
bbe88b6d | 160 | logit("Connection from %.100s with IP options:%.800s", |
61e96248 | 161 | ipaddr, text); |
162 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
163 | ipaddr, text); | |
164 | } | |
97722976 | 165 | #endif /* IP_OPTIONS */ |
61e96248 | 166 | } |
167 | ||
b6610e8f | 168 | void |
1639bb8f | 169 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
170 | { | |
171 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
172 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
173 | struct in_addr inaddr; | |
174 | u_int16_t port; | |
175 | ||
176 | if (addr->ss_family != AF_INET6 || | |
177 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) | |
178 | return; | |
179 | ||
180 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
181 | ||
182 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
183 | port = a6->sin6_port; | |
184 | ||
185 | memset(addr, 0, sizeof(*a4)); | |
186 | ||
187 | a4->sin_family = AF_INET; | |
188 | *len = sizeof(*a4); | |
189 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
190 | a4->sin_port = port; | |
191 | } | |
192 | ||
aa3378df | 193 | /* |
194 | * Return the canonical name of the host in the other side of the current | |
195 | * connection. The host name is cached, so it is efficient to call this | |
196 | * several times. | |
197 | */ | |
8efc0c15 | 198 | |
5260325f | 199 | const char * |
c5a7d788 | 200 | get_canonical_hostname(int use_dns) |
8efc0c15 | 201 | { |
48e671d5 | 202 | static char *canonical_host_name = NULL; |
c5a7d788 | 203 | static int use_dns_done = 0; |
48e671d5 | 204 | |
61e96248 | 205 | /* Check if we have previously retrieved name with same option. */ |
206 | if (canonical_host_name != NULL) { | |
c5a7d788 | 207 | if (use_dns_done != use_dns) |
61e96248 | 208 | xfree(canonical_host_name); |
209 | else | |
210 | return canonical_host_name; | |
211 | } | |
8efc0c15 | 212 | |
5260325f | 213 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 214 | if (packet_connection_is_on_socket()) |
61e96248 | 215 | canonical_host_name = get_remote_hostname( |
c5a7d788 | 216 | packet_get_connection_in(), use_dns); |
5260325f | 217 | else |
218 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 219 | |
c5a7d788 | 220 | use_dns_done = use_dns; |
5260325f | 221 | return canonical_host_name; |
8efc0c15 | 222 | } |
223 | ||
aa3378df | 224 | /* |
649bb60b | 225 | * Returns the local/remote IP-address/hostname of socket as a string. |
226 | * The returned string must be freed. | |
aa3378df | 227 | */ |
396c147e | 228 | static char * |
ca75d7de | 229 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 230 | { |
8002af61 | 231 | struct sockaddr_storage addr; |
232 | socklen_t addrlen; | |
48e671d5 | 233 | char ntop[NI_MAXHOST]; |
adc75586 | 234 | int r; |
5260325f | 235 | |
5260325f | 236 | /* Get IP address of client. */ |
8002af61 | 237 | addrlen = sizeof(addr); |
238 | memset(&addr, 0, sizeof(addr)); | |
239 | ||
240 | if (remote) { | |
ca75d7de | 241 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 242 | < 0) |
8002af61 | 243 | return NULL; |
8002af61 | 244 | } else { |
ca75d7de | 245 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 246 | < 0) |
8002af61 | 247 | return NULL; |
5260325f | 248 | } |
e7ccd20d | 249 | |
250 | /* Work around Linux IPv6 weirdness */ | |
251 | if (addr.ss_family == AF_INET6) | |
252 | addrlen = sizeof(struct sockaddr_in6); | |
253 | ||
a56cebd3 | 254 | ipv64_normalise_mapped(&addr, &addrlen); |
255 | ||
8002af61 | 256 | /* Get the address in ascii. */ |
adc75586 | 257 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
258 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
259 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
260 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
865ac82e | 261 | return NULL; |
262 | } | |
263 | return xstrdup(ntop); | |
264 | } | |
48e671d5 | 265 | |
8002af61 | 266 | char * |
ca75d7de | 267 | get_peer_ipaddr(int sock) |
8002af61 | 268 | { |
99443922 | 269 | char *p; |
270 | ||
ca75d7de | 271 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 272 | return p; |
273 | return xstrdup("UNKNOWN"); | |
8002af61 | 274 | } |
275 | ||
276 | char * | |
ca75d7de | 277 | get_local_ipaddr(int sock) |
8002af61 | 278 | { |
99443922 | 279 | char *p; |
280 | ||
ca75d7de | 281 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 282 | return p; |
283 | return xstrdup("UNKNOWN"); | |
8002af61 | 284 | } |
285 | ||
286 | char * | |
ca75d7de | 287 | get_local_name(int sock) |
8002af61 | 288 | { |
ca75d7de | 289 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 290 | } |
291 | ||
865ac82e | 292 | /* |
293 | * Returns the IP-address of the remote host as a string. The returned | |
294 | * string must not be freed. | |
295 | */ | |
5260325f | 296 | |
865ac82e | 297 | const char * |
d5bb9418 | 298 | get_remote_ipaddr(void) |
865ac82e | 299 | { |
300 | static char *canonical_host_ip = NULL; | |
301 | ||
302 | /* Check whether we have cached the ipaddr. */ | |
303 | if (canonical_host_ip == NULL) { | |
304 | if (packet_connection_is_on_socket()) { | |
305 | canonical_host_ip = | |
306 | get_peer_ipaddr(packet_get_connection_in()); | |
307 | if (canonical_host_ip == NULL) | |
2362db19 | 308 | cleanup_exit(255); |
865ac82e | 309 | } else { |
310 | /* If not on socket, return UNKNOWN. */ | |
311 | canonical_host_ip = xstrdup("UNKNOWN"); | |
312 | } | |
313 | } | |
5260325f | 314 | return canonical_host_ip; |
8efc0c15 | 315 | } |
316 | ||
46e3af7f | 317 | const char * |
c5a7d788 | 318 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 319 | { |
320 | static const char *remote = ""; | |
321 | if (utmp_len > 0) | |
c5a7d788 | 322 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 323 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
324 | remote = get_remote_ipaddr(); | |
325 | return remote; | |
326 | } | |
327 | ||
48e671d5 | 328 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 329 | |
396c147e | 330 | static int |
48e671d5 | 331 | get_sock_port(int sock, int local) |
8efc0c15 | 332 | { |
48e671d5 | 333 | struct sockaddr_storage from; |
334 | socklen_t fromlen; | |
335 | char strport[NI_MAXSERV]; | |
adc75586 | 336 | int r; |
5260325f | 337 | |
338 | /* Get IP address of client. */ | |
339 | fromlen = sizeof(from); | |
340 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 341 | if (local) { |
342 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
343 | error("getsockname failed: %.100s", strerror(errno)); | |
344 | return 0; | |
345 | } | |
346 | } else { | |
649bb60b | 347 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 348 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 349 | cleanup_exit(255); |
48e671d5 | 350 | } |
5260325f | 351 | } |
e7ccd20d | 352 | |
353 | /* Work around Linux IPv6 weirdness */ | |
354 | if (from.ss_family == AF_INET6) | |
355 | fromlen = sizeof(struct sockaddr_in6); | |
356 | ||
5260325f | 357 | /* Return port number. */ |
adc75586 | 358 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
359 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
360 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
361 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
48e671d5 | 362 | return atoi(strport); |
8efc0c15 | 363 | } |
364 | ||
48e671d5 | 365 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 366 | |
396c147e | 367 | static int |
48e671d5 | 368 | get_port(int local) |
8efc0c15 | 369 | { |
aa3378df | 370 | /* |
371 | * If the connection is not a socket, return 65535. This is | |
372 | * intentionally chosen to be an unprivileged port number. | |
373 | */ | |
48e671d5 | 374 | if (!packet_connection_is_on_socket()) |
5260325f | 375 | return 65535; |
8efc0c15 | 376 | |
48e671d5 | 377 | /* Get socket and return the port number. */ |
378 | return get_sock_port(packet_get_connection_in(), local); | |
379 | } | |
380 | ||
6ae2364d | 381 | int |
48e671d5 | 382 | get_peer_port(int sock) |
383 | { | |
384 | return get_sock_port(sock, 0); | |
385 | } | |
8efc0c15 | 386 | |
6ae2364d | 387 | int |
d5bb9418 | 388 | get_remote_port(void) |
48e671d5 | 389 | { |
13f2a382 | 390 | static int port = -1; |
391 | ||
392 | /* Cache to avoid getpeername() on a dead connection */ | |
393 | if (port == -1) | |
394 | port = get_port(0); | |
395 | ||
396 | return port; | |
48e671d5 | 397 | } |
398 | ||
399 | int | |
d5bb9418 | 400 | get_local_port(void) |
48e671d5 | 401 | { |
402 | return get_port(1); | |
8efc0c15 | 403 | } |