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2e437378 | 1 | /* $OpenBSD: canohost.c,v 1.61 2006/08/03 03:34:41 deraadt Exp $ */ |
3c0ef626 | 2 | /* |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * Functions for returning the canonical host name of the remote site. | |
7 | * | |
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". | |
13 | */ | |
14 | ||
15 | #include "includes.h" | |
3c0ef626 | 16 | |
2e437378 | 17 | #include <sys/types.h> |
18 | #include <sys/socket.h> | |
19 | ||
20 | #include <netinet/in.h> | |
21 | #include <arpa/inet.h> | |
22 | ||
23 | #include <ctype.h> | |
24 | #include <errno.h> | |
25 | #include <netdb.h> | |
26 | #include <stdio.h> | |
27 | #include <stdlib.h> | |
28 | #include <string.h> | |
29 | #include <stdarg.h> | |
30 | #include <unistd.h> | |
31 | ||
3c0ef626 | 32 | #include "xmalloc.h" |
2e437378 | 33 | #include "packet.h" |
3c0ef626 | 34 | #include "log.h" |
35 | #include "canohost.h" | |
36 | ||
37 | static void check_ip_options(int, char *); | |
38 | ||
39 | /* | |
40 | * Return the canonical name of the host at the other end of the socket. The | |
41 | * caller should free the returned string with xfree. | |
42 | */ | |
43 | ||
44 | static char * | |
1b56ff3d | 45 | get_remote_hostname(int sock, int use_dns) |
3c0ef626 | 46 | { |
47 | struct sockaddr_storage from; | |
48 | int i; | |
49 | socklen_t fromlen; | |
50 | struct addrinfo hints, *ai, *aitop; | |
51 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; | |
52 | ||
53 | /* Get IP address of client. */ | |
54 | fromlen = sizeof(from); | |
55 | memset(&from, 0, sizeof(from)); | |
1b56ff3d | 56 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 57 | debug("getpeername failed: %.100s", strerror(errno)); |
416fd2a8 | 58 | cleanup_exit(255); |
3c0ef626 | 59 | } |
416fd2a8 | 60 | |
2e437378 | 61 | if (from.ss_family == AF_INET) |
62 | check_ip_options(sock, ntop); | |
63 | ||
416fd2a8 | 64 | ipv64_normalise_mapped(&from, &fromlen); |
65 | ||
1c14df9e | 66 | if (from.ss_family == AF_INET6) |
67 | fromlen = sizeof(struct sockaddr_in6); | |
3c0ef626 | 68 | |
69 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), | |
e9a17296 | 70 | NULL, 0, NI_NUMERICHOST) != 0) |
3c0ef626 | 71 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
72 | ||
70791e56 | 73 | if (!use_dns) |
74 | return xstrdup(ntop); | |
75 | ||
3c0ef626 | 76 | debug3("Trying to reverse map address %.100s.", ntop); |
77 | /* Map the IP address to a host name. */ | |
78 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
e9a17296 | 79 | NULL, 0, NI_NAMEREQD) != 0) { |
3c0ef626 | 80 | /* Host name not found. Use ip address. */ |
3c0ef626 | 81 | return xstrdup(ntop); |
82 | } | |
83 | ||
70791e56 | 84 | /* |
85 | * if reverse lookup result looks like a numeric hostname, | |
86 | * someone is trying to trick us by PTR record like following: | |
87 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
88 | */ | |
89 | memset(&hints, 0, sizeof(hints)); | |
90 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
91 | hints.ai_flags = AI_NUMERICHOST; | |
92 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { | |
93 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
94 | name, ntop); | |
95 | freeaddrinfo(ai); | |
96 | return xstrdup(ntop); | |
97 | } | |
98 | ||
3c0ef626 | 99 | /* |
100 | * Convert it to all lowercase (which is expected by the rest | |
101 | * of this software). | |
102 | */ | |
103 | for (i = 0; name[i]; i++) | |
104 | if (isupper(name[i])) | |
2e437378 | 105 | name[i] = (char)tolower(name[i]); |
3c0ef626 | 106 | /* |
107 | * Map it back to an IP address and check that the given | |
108 | * address actually is an address of this host. This is | |
109 | * necessary because anyone with access to a name server can | |
110 | * define arbitrary names for an IP address. Mapping from | |
111 | * name to IP address can be trusted better (but can still be | |
112 | * fooled if the intruder has access to the name server of | |
113 | * the domain). | |
114 | */ | |
115 | memset(&hints, 0, sizeof(hints)); | |
116 | hints.ai_family = from.ss_family; | |
117 | hints.ai_socktype = SOCK_STREAM; | |
118 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
70791e56 | 119 | logit("reverse mapping checking getaddrinfo for %.700s " |
2e437378 | 120 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
3c0ef626 | 121 | return xstrdup(ntop); |
122 | } | |
123 | /* Look for the address from the list of addresses. */ | |
124 | for (ai = aitop; ai; ai = ai->ai_next) { | |
125 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
126 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
127 | (strcmp(ntop, ntop2) == 0)) | |
128 | break; | |
129 | } | |
130 | freeaddrinfo(aitop); | |
131 | /* If we reached the end of the list, the address was not there. */ | |
132 | if (!ai) { | |
133 | /* Address not found for the host name. */ | |
70791e56 | 134 | logit("Address %.100s maps to %.600s, but this does not " |
e00da40d | 135 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
3c0ef626 | 136 | ntop, name); |
137 | return xstrdup(ntop); | |
138 | } | |
139 | return xstrdup(name); | |
140 | } | |
141 | ||
142 | /* | |
143 | * If IP options are supported, make sure there are none (log and | |
144 | * disconnect them if any are found). Basically we are worried about | |
145 | * source routing; it can be used to pretend you are somebody | |
146 | * (ip-address) you are not. That itself may be "almost acceptable" | |
147 | * under certain circumstances, but rhosts autentication is useless | |
148 | * if source routing is accepted. Notice also that if we just dropped | |
149 | * source routing here, the other side could use IP spoofing to do | |
150 | * rest of the interaction and could still bypass security. So we | |
151 | * exit here if we detect any IP options. | |
152 | */ | |
153 | /* IPv4 only */ | |
154 | static void | |
1b56ff3d | 155 | check_ip_options(int sock, char *ipaddr) |
3c0ef626 | 156 | { |
70791e56 | 157 | #ifdef IP_OPTIONS |
3c0ef626 | 158 | u_char options[200]; |
159 | char text[sizeof(options) * 3 + 1]; | |
160 | socklen_t option_size; | |
34fee935 | 161 | u_int i; |
162 | int ipproto; | |
3c0ef626 | 163 | struct protoent *ip; |
164 | ||
165 | if ((ip = getprotobyname("ip")) != NULL) | |
166 | ipproto = ip->p_proto; | |
167 | else | |
168 | ipproto = IPPROTO_IP; | |
169 | option_size = sizeof(options); | |
1b56ff3d | 170 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
3c0ef626 | 171 | &option_size) >= 0 && option_size != 0) { |
172 | text[0] = '\0'; | |
173 | for (i = 0; i < option_size; i++) | |
174 | snprintf(text + i*3, sizeof(text) - i*3, | |
175 | " %2.2x", options[i]); | |
e00da40d | 176 | fatal("Connection from %.100s with IP options:%.800s", |
3c0ef626 | 177 | ipaddr, text); |
178 | } | |
70791e56 | 179 | #endif /* IP_OPTIONS */ |
3c0ef626 | 180 | } |
181 | ||
34fee935 | 182 | void |
416fd2a8 | 183 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
184 | { | |
185 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
186 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
187 | struct in_addr inaddr; | |
188 | u_int16_t port; | |
189 | ||
34fee935 | 190 | if (addr->ss_family != AF_INET6 || |
416fd2a8 | 191 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
192 | return; | |
193 | ||
194 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
195 | ||
196 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
197 | port = a6->sin6_port; | |
198 | ||
199 | memset(addr, 0, sizeof(*a4)); | |
200 | ||
201 | a4->sin_family = AF_INET; | |
202 | *len = sizeof(*a4); | |
203 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
204 | a4->sin_port = port; | |
205 | } | |
206 | ||
3c0ef626 | 207 | /* |
208 | * Return the canonical name of the host in the other side of the current | |
209 | * connection. The host name is cached, so it is efficient to call this | |
210 | * several times. | |
211 | */ | |
212 | ||
213 | const char * | |
70791e56 | 214 | get_canonical_hostname(int use_dns) |
3c0ef626 | 215 | { |
e00da40d | 216 | char *host; |
3c0ef626 | 217 | static char *canonical_host_name = NULL; |
e00da40d | 218 | static char *remote_ip = NULL; |
3c0ef626 | 219 | |
220 | /* Check if we have previously retrieved name with same option. */ | |
e00da40d | 221 | if (use_dns && canonical_host_name != NULL) |
222 | return canonical_host_name; | |
223 | if (!use_dns && remote_ip != NULL) | |
224 | return remote_ip; | |
3c0ef626 | 225 | |
226 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ | |
227 | if (packet_connection_is_on_socket()) | |
e00da40d | 228 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
3c0ef626 | 229 | else |
e00da40d | 230 | host = "UNKNOWN"; |
3c0ef626 | 231 | |
e00da40d | 232 | if (use_dns) |
233 | canonical_host_name = host; | |
234 | else | |
235 | remote_ip = host; | |
236 | return host; | |
3c0ef626 | 237 | } |
238 | ||
239 | /* | |
1c14df9e | 240 | * Returns the local/remote IP-address/hostname of socket as a string. |
241 | * The returned string must be freed. | |
3c0ef626 | 242 | */ |
243 | static char * | |
1b56ff3d | 244 | get_socket_address(int sock, int remote, int flags) |
3c0ef626 | 245 | { |
246 | struct sockaddr_storage addr; | |
247 | socklen_t addrlen; | |
248 | char ntop[NI_MAXHOST]; | |
34fee935 | 249 | int r; |
3c0ef626 | 250 | |
251 | /* Get IP address of client. */ | |
252 | addrlen = sizeof(addr); | |
253 | memset(&addr, 0, sizeof(addr)); | |
254 | ||
255 | if (remote) { | |
1b56ff3d | 256 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
e54b3d7c | 257 | < 0) |
3c0ef626 | 258 | return NULL; |
3c0ef626 | 259 | } else { |
1b56ff3d | 260 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
e54b3d7c | 261 | < 0) |
3c0ef626 | 262 | return NULL; |
3c0ef626 | 263 | } |
1c14df9e | 264 | |
265 | /* Work around Linux IPv6 weirdness */ | |
266 | if (addr.ss_family == AF_INET6) | |
267 | addrlen = sizeof(struct sockaddr_in6); | |
268 | ||
34fee935 | 269 | ipv64_normalise_mapped(&addr, &addrlen); |
270 | ||
3c0ef626 | 271 | /* Get the address in ascii. */ |
34fee935 | 272 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
273 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
274 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
275 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
3c0ef626 | 276 | return NULL; |
277 | } | |
278 | return xstrdup(ntop); | |
279 | } | |
280 | ||
281 | char * | |
1b56ff3d | 282 | get_peer_ipaddr(int sock) |
3c0ef626 | 283 | { |
e54b3d7c | 284 | char *p; |
285 | ||
1b56ff3d | 286 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
e54b3d7c | 287 | return p; |
288 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 289 | } |
290 | ||
291 | char * | |
1b56ff3d | 292 | get_local_ipaddr(int sock) |
3c0ef626 | 293 | { |
e54b3d7c | 294 | char *p; |
295 | ||
1b56ff3d | 296 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
e54b3d7c | 297 | return p; |
298 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 299 | } |
300 | ||
301 | char * | |
1b56ff3d | 302 | get_local_name(int sock) |
3c0ef626 | 303 | { |
1b56ff3d | 304 | return get_socket_address(sock, 0, NI_NAMEREQD); |
3c0ef626 | 305 | } |
306 | ||
307 | /* | |
308 | * Returns the IP-address of the remote host as a string. The returned | |
309 | * string must not be freed. | |
310 | */ | |
311 | ||
312 | const char * | |
e9a17296 | 313 | get_remote_ipaddr(void) |
3c0ef626 | 314 | { |
315 | static char *canonical_host_ip = NULL; | |
316 | ||
317 | /* Check whether we have cached the ipaddr. */ | |
318 | if (canonical_host_ip == NULL) { | |
319 | if (packet_connection_is_on_socket()) { | |
320 | canonical_host_ip = | |
321 | get_peer_ipaddr(packet_get_connection_in()); | |
322 | if (canonical_host_ip == NULL) | |
416fd2a8 | 323 | cleanup_exit(255); |
3c0ef626 | 324 | } else { |
325 | /* If not on socket, return UNKNOWN. */ | |
326 | canonical_host_ip = xstrdup("UNKNOWN"); | |
327 | } | |
328 | } | |
329 | return canonical_host_ip; | |
330 | } | |
331 | ||
332 | const char * | |
70791e56 | 333 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
3c0ef626 | 334 | { |
335 | static const char *remote = ""; | |
336 | if (utmp_len > 0) | |
70791e56 | 337 | remote = get_canonical_hostname(use_dns); |
3c0ef626 | 338 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
339 | remote = get_remote_ipaddr(); | |
340 | return remote; | |
341 | } | |
342 | ||
343 | /* Returns the local/remote port for the socket. */ | |
344 | ||
345 | static int | |
346 | get_sock_port(int sock, int local) | |
347 | { | |
348 | struct sockaddr_storage from; | |
349 | socklen_t fromlen; | |
350 | char strport[NI_MAXSERV]; | |
34fee935 | 351 | int r; |
3c0ef626 | 352 | |
353 | /* Get IP address of client. */ | |
354 | fromlen = sizeof(from); | |
355 | memset(&from, 0, sizeof(from)); | |
356 | if (local) { | |
357 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
358 | error("getsockname failed: %.100s", strerror(errno)); | |
359 | return 0; | |
360 | } | |
361 | } else { | |
1c14df9e | 362 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 363 | debug("getpeername failed: %.100s", strerror(errno)); |
34fee935 | 364 | return -1; |
3c0ef626 | 365 | } |
366 | } | |
1c14df9e | 367 | |
368 | /* Work around Linux IPv6 weirdness */ | |
369 | if (from.ss_family == AF_INET6) | |
370 | fromlen = sizeof(struct sockaddr_in6); | |
371 | ||
3c0ef626 | 372 | /* Return port number. */ |
34fee935 | 373 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
374 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
375 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
376 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
3c0ef626 | 377 | return atoi(strport); |
378 | } | |
379 | ||
380 | /* Returns remote/local port number for the current connection. */ | |
381 | ||
382 | static int | |
383 | get_port(int local) | |
384 | { | |
385 | /* | |
386 | * If the connection is not a socket, return 65535. This is | |
387 | * intentionally chosen to be an unprivileged port number. | |
388 | */ | |
389 | if (!packet_connection_is_on_socket()) | |
390 | return 65535; | |
391 | ||
392 | /* Get socket and return the port number. */ | |
393 | return get_sock_port(packet_get_connection_in(), local); | |
394 | } | |
395 | ||
396 | int | |
397 | get_peer_port(int sock) | |
398 | { | |
399 | return get_sock_port(sock, 0); | |
400 | } | |
401 | ||
402 | int | |
e9a17296 | 403 | get_remote_port(void) |
3c0ef626 | 404 | { |
1b56ff3d | 405 | static int port = -1; |
406 | ||
407 | /* Cache to avoid getpeername() on a dead connection */ | |
408 | if (port == -1) | |
409 | port = get_port(0); | |
410 | ||
411 | return port; | |
3c0ef626 | 412 | } |
413 | ||
414 | int | |
e9a17296 | 415 | get_local_port(void) |
3c0ef626 | 416 | { |
417 | return get_port(1); | |
418 | } | |
c2397a66 | 419 | |
c2397a66 | 420 | void |
366115cd | 421 | resolve_localhost(char **host) |
c2397a66 | 422 | { |
423 | struct hostent *hostinfo; | |
424 | ||
425 | hostinfo = gethostbyname(*host); | |
f2fd21a2 | 426 | if (hostinfo == NULL || hostinfo->h_name == NULL) { |
427 | debug("gethostbyname(%s) failed", *host); | |
428 | return; | |
429 | } | |
366115cd | 430 | if (hostinfo->h_addrtype == AF_INET) { |
c2397a66 | 431 | struct in_addr addr; |
432 | addr = *(struct in_addr *)(hostinfo->h_addr); | |
433 | if (ntohl(addr.s_addr) == INADDR_LOOPBACK) { | |
434 | char buf[MAXHOSTNAMELEN]; | |
f2fd21a2 | 435 | if (gethostname(buf, sizeof(buf)) < 0) { |
436 | debug("gethostname() failed"); | |
437 | return; | |
c2397a66 | 438 | } |
f2fd21a2 | 439 | hostinfo = gethostbyname(buf); |
366115cd | 440 | xfree(*host); |
34fee935 | 441 | if (hostinfo == NULL || hostinfo->h_name == NULL) { |
442 | *host = xstrdup(buf); | |
443 | } else { | |
444 | *host = xstrdup(hostinfo->h_name); | |
445 | } | |
c2397a66 | 446 | } |
447 | } | |
c2397a66 | 448 | } |