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9108f8d9 | 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 | |
9108f8d9 | 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 | ||
3c0ef626 | 31 | #include "xmalloc.h" |
9108f8d9 | 32 | #include "packet.h" |
3c0ef626 | 33 | #include "log.h" |
34 | #include "canohost.h" | |
35 | ||
36 | static void check_ip_options(int, char *); | |
37 | ||
38 | /* | |
39 | * Return the canonical name of the host at the other end of the socket. The | |
40 | * caller should free the returned string with xfree. | |
41 | */ | |
42 | ||
43 | static char * | |
c9f39d2c | 44 | get_remote_hostname(int sock, int use_dns) |
3c0ef626 | 45 | { |
46 | struct sockaddr_storage from; | |
47 | int i; | |
48 | socklen_t fromlen; | |
49 | struct addrinfo hints, *ai, *aitop; | |
50 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; | |
51 | ||
52 | /* Get IP address of client. */ | |
53 | fromlen = sizeof(from); | |
54 | memset(&from, 0, sizeof(from)); | |
c9f39d2c | 55 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 56 | debug("getpeername failed: %.100s", strerror(errno)); |
cdd66111 | 57 | cleanup_exit(255); |
3c0ef626 | 58 | } |
cdd66111 | 59 | |
9108f8d9 | 60 | if (from.ss_family == AF_INET) |
61 | check_ip_options(sock, ntop); | |
62 | ||
cdd66111 | 63 | ipv64_normalise_mapped(&from, &fromlen); |
64 | ||
6a9b3198 | 65 | if (from.ss_family == AF_INET6) |
66 | fromlen = sizeof(struct sockaddr_in6); | |
3c0ef626 | 67 | |
68 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), | |
e9a17296 | 69 | NULL, 0, NI_NUMERICHOST) != 0) |
3c0ef626 | 70 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
71 | ||
0fff78ff | 72 | if (!use_dns) |
73 | return xstrdup(ntop); | |
74 | ||
3c0ef626 | 75 | debug3("Trying to reverse map address %.100s.", ntop); |
76 | /* Map the IP address to a host name. */ | |
77 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
e9a17296 | 78 | NULL, 0, NI_NAMEREQD) != 0) { |
3c0ef626 | 79 | /* Host name not found. Use ip address. */ |
3c0ef626 | 80 | return xstrdup(ntop); |
81 | } | |
82 | ||
0fff78ff | 83 | /* |
84 | * if reverse lookup result looks like a numeric hostname, | |
85 | * someone is trying to trick us by PTR record like following: | |
86 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
87 | */ | |
88 | memset(&hints, 0, sizeof(hints)); | |
89 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
90 | hints.ai_flags = AI_NUMERICHOST; | |
91 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { | |
92 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
93 | name, ntop); | |
94 | freeaddrinfo(ai); | |
95 | return xstrdup(ntop); | |
96 | } | |
97 | ||
3c0ef626 | 98 | /* |
99 | * Convert it to all lowercase (which is expected by the rest | |
100 | * of this software). | |
101 | */ | |
102 | for (i = 0; name[i]; i++) | |
103 | if (isupper(name[i])) | |
9108f8d9 | 104 | name[i] = (char)tolower(name[i]); |
3c0ef626 | 105 | /* |
106 | * Map it back to an IP address and check that the given | |
107 | * address actually is an address of this host. This is | |
108 | * necessary because anyone with access to a name server can | |
109 | * define arbitrary names for an IP address. Mapping from | |
110 | * name to IP address can be trusted better (but can still be | |
111 | * fooled if the intruder has access to the name server of | |
112 | * the domain). | |
113 | */ | |
114 | memset(&hints, 0, sizeof(hints)); | |
115 | hints.ai_family = from.ss_family; | |
116 | hints.ai_socktype = SOCK_STREAM; | |
117 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
0fff78ff | 118 | logit("reverse mapping checking getaddrinfo for %.700s " |
9108f8d9 | 119 | "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); |
3c0ef626 | 120 | return xstrdup(ntop); |
121 | } | |
122 | /* Look for the address from the list of addresses. */ | |
123 | for (ai = aitop; ai; ai = ai->ai_next) { | |
124 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
125 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
126 | (strcmp(ntop, ntop2) == 0)) | |
127 | break; | |
128 | } | |
129 | freeaddrinfo(aitop); | |
130 | /* If we reached the end of the list, the address was not there. */ | |
131 | if (!ai) { | |
132 | /* Address not found for the host name. */ | |
0fff78ff | 133 | logit("Address %.100s maps to %.600s, but this does not " |
2c06c99b | 134 | "map back to the address - POSSIBLE BREAK-IN ATTEMPT!", |
3c0ef626 | 135 | ntop, name); |
136 | return xstrdup(ntop); | |
137 | } | |
138 | return xstrdup(name); | |
139 | } | |
140 | ||
141 | /* | |
142 | * If IP options are supported, make sure there are none (log and | |
143 | * disconnect them if any are found). Basically we are worried about | |
144 | * source routing; it can be used to pretend you are somebody | |
145 | * (ip-address) you are not. That itself may be "almost acceptable" | |
146 | * under certain circumstances, but rhosts autentication is useless | |
147 | * if source routing is accepted. Notice also that if we just dropped | |
148 | * source routing here, the other side could use IP spoofing to do | |
149 | * rest of the interaction and could still bypass security. So we | |
150 | * exit here if we detect any IP options. | |
151 | */ | |
152 | /* IPv4 only */ | |
153 | static void | |
c9f39d2c | 154 | check_ip_options(int sock, char *ipaddr) |
3c0ef626 | 155 | { |
0fff78ff | 156 | #ifdef IP_OPTIONS |
3c0ef626 | 157 | u_char options[200]; |
158 | char text[sizeof(options) * 3 + 1]; | |
159 | socklen_t option_size; | |
665a873d | 160 | u_int i; |
161 | int ipproto; | |
3c0ef626 | 162 | struct protoent *ip; |
163 | ||
164 | if ((ip = getprotobyname("ip")) != NULL) | |
165 | ipproto = ip->p_proto; | |
166 | else | |
167 | ipproto = IPPROTO_IP; | |
168 | option_size = sizeof(options); | |
c9f39d2c | 169 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
3c0ef626 | 170 | &option_size) >= 0 && option_size != 0) { |
171 | text[0] = '\0'; | |
172 | for (i = 0; i < option_size; i++) | |
173 | snprintf(text + i*3, sizeof(text) - i*3, | |
174 | " %2.2x", options[i]); | |
2c06c99b | 175 | fatal("Connection from %.100s with IP options:%.800s", |
3c0ef626 | 176 | ipaddr, text); |
177 | } | |
0fff78ff | 178 | #endif /* IP_OPTIONS */ |
3c0ef626 | 179 | } |
180 | ||
996d5e62 | 181 | void |
cdd66111 | 182 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
183 | { | |
184 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
185 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
186 | struct in_addr inaddr; | |
187 | u_int16_t port; | |
188 | ||
665a873d | 189 | if (addr->ss_family != AF_INET6 || |
cdd66111 | 190 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
191 | return; | |
192 | ||
193 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
194 | ||
195 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
196 | port = a6->sin6_port; | |
197 | ||
198 | memset(addr, 0, sizeof(*a4)); | |
199 | ||
200 | a4->sin_family = AF_INET; | |
201 | *len = sizeof(*a4); | |
202 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
203 | a4->sin_port = port; | |
204 | } | |
205 | ||
3c0ef626 | 206 | /* |
207 | * Return the canonical name of the host in the other side of the current | |
208 | * connection. The host name is cached, so it is efficient to call this | |
209 | * several times. | |
210 | */ | |
211 | ||
212 | const char * | |
0fff78ff | 213 | get_canonical_hostname(int use_dns) |
3c0ef626 | 214 | { |
2c06c99b | 215 | char *host; |
3c0ef626 | 216 | static char *canonical_host_name = NULL; |
2c06c99b | 217 | static char *remote_ip = NULL; |
3c0ef626 | 218 | |
219 | /* Check if we have previously retrieved name with same option. */ | |
2c06c99b | 220 | if (use_dns && canonical_host_name != NULL) |
221 | return canonical_host_name; | |
222 | if (!use_dns && remote_ip != NULL) | |
223 | return remote_ip; | |
3c0ef626 | 224 | |
225 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ | |
226 | if (packet_connection_is_on_socket()) | |
2c06c99b | 227 | host = get_remote_hostname(packet_get_connection_in(), use_dns); |
3c0ef626 | 228 | else |
2c06c99b | 229 | host = "UNKNOWN"; |
3c0ef626 | 230 | |
2c06c99b | 231 | if (use_dns) |
232 | canonical_host_name = host; | |
233 | else | |
234 | remote_ip = host; | |
235 | return host; | |
3c0ef626 | 236 | } |
237 | ||
238 | /* | |
6a9b3198 | 239 | * Returns the local/remote IP-address/hostname of socket as a string. |
240 | * The returned string must be freed. | |
3c0ef626 | 241 | */ |
242 | static char * | |
c9f39d2c | 243 | get_socket_address(int sock, int remote, int flags) |
3c0ef626 | 244 | { |
245 | struct sockaddr_storage addr; | |
246 | socklen_t addrlen; | |
247 | char ntop[NI_MAXHOST]; | |
996d5e62 | 248 | int r; |
3c0ef626 | 249 | |
250 | /* Get IP address of client. */ | |
251 | addrlen = sizeof(addr); | |
252 | memset(&addr, 0, sizeof(addr)); | |
253 | ||
254 | if (remote) { | |
c9f39d2c | 255 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
41b2f314 | 256 | < 0) |
3c0ef626 | 257 | return NULL; |
3c0ef626 | 258 | } else { |
c9f39d2c | 259 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
41b2f314 | 260 | < 0) |
3c0ef626 | 261 | return NULL; |
3c0ef626 | 262 | } |
6a9b3198 | 263 | |
264 | /* Work around Linux IPv6 weirdness */ | |
265 | if (addr.ss_family == AF_INET6) | |
266 | addrlen = sizeof(struct sockaddr_in6); | |
267 | ||
dec6d9fe | 268 | ipv64_normalise_mapped(&addr, &addrlen); |
269 | ||
3c0ef626 | 270 | /* Get the address in ascii. */ |
996d5e62 | 271 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
272 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
273 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
274 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
3c0ef626 | 275 | return NULL; |
276 | } | |
277 | return xstrdup(ntop); | |
278 | } | |
279 | ||
280 | char * | |
c9f39d2c | 281 | get_peer_ipaddr(int sock) |
3c0ef626 | 282 | { |
41b2f314 | 283 | char *p; |
284 | ||
c9f39d2c | 285 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
41b2f314 | 286 | return p; |
287 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 288 | } |
289 | ||
290 | char * | |
c9f39d2c | 291 | get_local_ipaddr(int sock) |
3c0ef626 | 292 | { |
41b2f314 | 293 | char *p; |
294 | ||
c9f39d2c | 295 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
41b2f314 | 296 | return p; |
297 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 298 | } |
299 | ||
300 | char * | |
c9f39d2c | 301 | get_local_name(int sock) |
3c0ef626 | 302 | { |
c9f39d2c | 303 | return get_socket_address(sock, 0, NI_NAMEREQD); |
3c0ef626 | 304 | } |
305 | ||
306 | /* | |
307 | * Returns the IP-address of the remote host as a string. The returned | |
308 | * string must not be freed. | |
309 | */ | |
310 | ||
311 | const char * | |
e9a17296 | 312 | get_remote_ipaddr(void) |
3c0ef626 | 313 | { |
314 | static char *canonical_host_ip = NULL; | |
315 | ||
316 | /* Check whether we have cached the ipaddr. */ | |
317 | if (canonical_host_ip == NULL) { | |
318 | if (packet_connection_is_on_socket()) { | |
319 | canonical_host_ip = | |
320 | get_peer_ipaddr(packet_get_connection_in()); | |
321 | if (canonical_host_ip == NULL) | |
cdd66111 | 322 | cleanup_exit(255); |
3c0ef626 | 323 | } else { |
324 | /* If not on socket, return UNKNOWN. */ | |
325 | canonical_host_ip = xstrdup("UNKNOWN"); | |
326 | } | |
327 | } | |
328 | return canonical_host_ip; | |
329 | } | |
330 | ||
331 | const char * | |
0fff78ff | 332 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
3c0ef626 | 333 | { |
334 | static const char *remote = ""; | |
335 | if (utmp_len > 0) | |
0fff78ff | 336 | remote = get_canonical_hostname(use_dns); |
3c0ef626 | 337 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
338 | remote = get_remote_ipaddr(); | |
339 | return remote; | |
340 | } | |
341 | ||
342 | /* Returns the local/remote port for the socket. */ | |
343 | ||
344 | static int | |
345 | get_sock_port(int sock, int local) | |
346 | { | |
347 | struct sockaddr_storage from; | |
348 | socklen_t fromlen; | |
349 | char strport[NI_MAXSERV]; | |
996d5e62 | 350 | int r; |
3c0ef626 | 351 | |
352 | /* Get IP address of client. */ | |
353 | fromlen = sizeof(from); | |
354 | memset(&from, 0, sizeof(from)); | |
355 | if (local) { | |
356 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
357 | error("getsockname failed: %.100s", strerror(errno)); | |
358 | return 0; | |
359 | } | |
360 | } else { | |
6a9b3198 | 361 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 362 | debug("getpeername failed: %.100s", strerror(errno)); |
665a873d | 363 | return -1; |
3c0ef626 | 364 | } |
365 | } | |
6a9b3198 | 366 | |
367 | /* Work around Linux IPv6 weirdness */ | |
368 | if (from.ss_family == AF_INET6) | |
369 | fromlen = sizeof(struct sockaddr_in6); | |
370 | ||
3c0ef626 | 371 | /* Return port number. */ |
996d5e62 | 372 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
373 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
374 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
375 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
3c0ef626 | 376 | return atoi(strport); |
377 | } | |
378 | ||
379 | /* Returns remote/local port number for the current connection. */ | |
380 | ||
381 | static int | |
382 | get_port(int local) | |
383 | { | |
384 | /* | |
385 | * If the connection is not a socket, return 65535. This is | |
386 | * intentionally chosen to be an unprivileged port number. | |
387 | */ | |
388 | if (!packet_connection_is_on_socket()) | |
389 | return 65535; | |
390 | ||
391 | /* Get socket and return the port number. */ | |
392 | return get_sock_port(packet_get_connection_in(), local); | |
393 | } | |
394 | ||
395 | int | |
396 | get_peer_port(int sock) | |
397 | { | |
398 | return get_sock_port(sock, 0); | |
399 | } | |
400 | ||
401 | int | |
e9a17296 | 402 | get_remote_port(void) |
3c0ef626 | 403 | { |
c9f39d2c | 404 | static int port = -1; |
405 | ||
406 | /* Cache to avoid getpeername() on a dead connection */ | |
407 | if (port == -1) | |
408 | port = get_port(0); | |
409 | ||
410 | return port; | |
3c0ef626 | 411 | } |
412 | ||
413 | int | |
e9a17296 | 414 | get_local_port(void) |
3c0ef626 | 415 | { |
416 | return get_port(1); | |
417 | } |