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3c0ef626 | 1 | /* |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Functions for returning the canonical host name of the remote site. | |
6 | * | |
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". | |
12 | */ | |
13 | ||
14 | #include "includes.h" | |
9cb1827b | 15 | RCSID("$OpenBSD: canohost.c,v 1.37 2003/06/02 09:17:34 markus Exp $"); |
3c0ef626 | 16 | |
17 | #include "packet.h" | |
18 | #include "xmalloc.h" | |
19 | #include "log.h" | |
20 | #include "canohost.h" | |
21 | ||
22 | static void check_ip_options(int, char *); | |
23 | ||
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 | */ | |
28 | ||
29 | static char * | |
0fff78ff | 30 | get_remote_hostname(int socket, int use_dns) |
3c0ef626 | 31 | { |
32 | struct sockaddr_storage from; | |
33 | int i; | |
34 | socklen_t fromlen; | |
35 | struct addrinfo hints, *ai, *aitop; | |
36 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; | |
37 | ||
38 | /* Get IP address of client. */ | |
39 | fromlen = sizeof(from); | |
40 | memset(&from, 0, sizeof(from)); | |
6a9b3198 | 41 | if (getpeername(socket, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 42 | debug("getpeername failed: %.100s", strerror(errno)); |
9cb1827b | 43 | fatal_cleanup(); |
3c0ef626 | 44 | } |
9cb1827b | 45 | #ifdef IPV4_IN_IPV6 |
46 | if (from.ss_family == AF_INET6) { | |
47 | struct sockaddr_in6 *from6 = (struct sockaddr_in6 *)&from; | |
48 | ||
49 | /* Detect IPv4 in IPv6 mapped address and convert it to */ | |
50 | /* plain (AF_INET) IPv4 address */ | |
51 | if (IN6_IS_ADDR_V4MAPPED(&from6->sin6_addr)) { | |
52 | struct sockaddr_in *from4 = (struct sockaddr_in *)&from; | |
53 | struct in_addr addr; | |
54 | u_int16_t port; | |
55 | ||
56 | memcpy(&addr, ((char *)&from6->sin6_addr) + 12, sizeof(addr)); | |
57 | port = from6->sin6_port; | |
58 | ||
59 | memset(&from, 0, sizeof(from)); | |
60 | ||
61 | from4->sin_family = AF_INET; | |
62 | fromlen = sizeof(*from4); | |
63 | memcpy(&from4->sin_addr, &addr, sizeof(addr)); | |
64 | from4->sin_port = port; | |
65 | } | |
66 | } | |
67 | #endif | |
6a9b3198 | 68 | if (from.ss_family == AF_INET6) |
69 | fromlen = sizeof(struct sockaddr_in6); | |
3c0ef626 | 70 | |
71 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), | |
e9a17296 | 72 | NULL, 0, NI_NUMERICHOST) != 0) |
3c0ef626 | 73 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
74 | ||
0fff78ff | 75 | if (!use_dns) |
76 | return xstrdup(ntop); | |
77 | ||
f5799ae1 | 78 | if (from.ss_family == AF_INET) |
79 | check_ip_options(socket, ntop); | |
80 | ||
3c0ef626 | 81 | debug3("Trying to reverse map address %.100s.", ntop); |
82 | /* Map the IP address to a host name. */ | |
83 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
e9a17296 | 84 | NULL, 0, NI_NAMEREQD) != 0) { |
3c0ef626 | 85 | /* Host name not found. Use ip address. */ |
3c0ef626 | 86 | return xstrdup(ntop); |
87 | } | |
88 | ||
0fff78ff | 89 | /* |
90 | * if reverse lookup result looks like a numeric hostname, | |
91 | * someone is trying to trick us by PTR record like following: | |
92 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
93 | */ | |
94 | memset(&hints, 0, sizeof(hints)); | |
95 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
96 | hints.ai_flags = AI_NUMERICHOST; | |
97 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { | |
98 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
99 | name, ntop); | |
100 | freeaddrinfo(ai); | |
101 | return xstrdup(ntop); | |
102 | } | |
103 | ||
3c0ef626 | 104 | /* |
105 | * Convert it to all lowercase (which is expected by the rest | |
106 | * of this software). | |
107 | */ | |
108 | for (i = 0; name[i]; i++) | |
109 | if (isupper(name[i])) | |
110 | name[i] = tolower(name[i]); | |
3c0ef626 | 111 | /* |
112 | * Map it back to an IP address and check that the given | |
113 | * address actually is an address of this host. This is | |
114 | * necessary because anyone with access to a name server can | |
115 | * define arbitrary names for an IP address. Mapping from | |
116 | * name to IP address can be trusted better (but can still be | |
117 | * fooled if the intruder has access to the name server of | |
118 | * the domain). | |
119 | */ | |
120 | memset(&hints, 0, sizeof(hints)); | |
121 | hints.ai_family = from.ss_family; | |
122 | hints.ai_socktype = SOCK_STREAM; | |
123 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
0fff78ff | 124 | logit("reverse mapping checking getaddrinfo for %.700s " |
3c0ef626 | 125 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); |
126 | return xstrdup(ntop); | |
127 | } | |
128 | /* Look for the address from the list of addresses. */ | |
129 | for (ai = aitop; ai; ai = ai->ai_next) { | |
130 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
131 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
132 | (strcmp(ntop, ntop2) == 0)) | |
133 | break; | |
134 | } | |
135 | freeaddrinfo(aitop); | |
136 | /* If we reached the end of the list, the address was not there. */ | |
137 | if (!ai) { | |
138 | /* Address not found for the host name. */ | |
0fff78ff | 139 | logit("Address %.100s maps to %.600s, but this does not " |
3c0ef626 | 140 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
141 | ntop, name); | |
142 | return xstrdup(ntop); | |
143 | } | |
144 | return xstrdup(name); | |
145 | } | |
146 | ||
147 | /* | |
148 | * If IP options are supported, make sure there are none (log and | |
149 | * disconnect them if any are found). Basically we are worried about | |
150 | * source routing; it can be used to pretend you are somebody | |
151 | * (ip-address) you are not. That itself may be "almost acceptable" | |
152 | * under certain circumstances, but rhosts autentication is useless | |
153 | * if source routing is accepted. Notice also that if we just dropped | |
154 | * source routing here, the other side could use IP spoofing to do | |
155 | * rest of the interaction and could still bypass security. So we | |
156 | * exit here if we detect any IP options. | |
157 | */ | |
158 | /* IPv4 only */ | |
159 | static void | |
160 | check_ip_options(int socket, char *ipaddr) | |
161 | { | |
0fff78ff | 162 | #ifdef IP_OPTIONS |
3c0ef626 | 163 | u_char options[200]; |
164 | char text[sizeof(options) * 3 + 1]; | |
165 | socklen_t option_size; | |
166 | int i, ipproto; | |
167 | struct protoent *ip; | |
168 | ||
169 | if ((ip = getprotobyname("ip")) != NULL) | |
170 | ipproto = ip->p_proto; | |
171 | else | |
172 | ipproto = IPPROTO_IP; | |
173 | option_size = sizeof(options); | |
e9a17296 | 174 | if (getsockopt(socket, ipproto, IP_OPTIONS, options, |
3c0ef626 | 175 | &option_size) >= 0 && option_size != 0) { |
176 | text[0] = '\0'; | |
177 | for (i = 0; i < option_size; i++) | |
178 | snprintf(text + i*3, sizeof(text) - i*3, | |
179 | " %2.2x", options[i]); | |
0fff78ff | 180 | logit("Connection from %.100s with IP options:%.800s", |
3c0ef626 | 181 | ipaddr, text); |
182 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
183 | ipaddr, text); | |
184 | } | |
0fff78ff | 185 | #endif /* IP_OPTIONS */ |
3c0ef626 | 186 | } |
187 | ||
188 | /* | |
189 | * Return the canonical name of the host in the other side of the current | |
190 | * connection. The host name is cached, so it is efficient to call this | |
191 | * several times. | |
192 | */ | |
193 | ||
194 | const char * | |
0fff78ff | 195 | get_canonical_hostname(int use_dns) |
3c0ef626 | 196 | { |
197 | static char *canonical_host_name = NULL; | |
0fff78ff | 198 | static int use_dns_done = 0; |
3c0ef626 | 199 | |
200 | /* Check if we have previously retrieved name with same option. */ | |
201 | if (canonical_host_name != NULL) { | |
0fff78ff | 202 | if (use_dns_done != use_dns) |
3c0ef626 | 203 | xfree(canonical_host_name); |
204 | else | |
205 | return canonical_host_name; | |
206 | } | |
207 | ||
208 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ | |
209 | if (packet_connection_is_on_socket()) | |
210 | canonical_host_name = get_remote_hostname( | |
0fff78ff | 211 | packet_get_connection_in(), use_dns); |
3c0ef626 | 212 | else |
213 | canonical_host_name = xstrdup("UNKNOWN"); | |
214 | ||
0fff78ff | 215 | use_dns_done = use_dns; |
3c0ef626 | 216 | return canonical_host_name; |
217 | } | |
218 | ||
219 | /* | |
6a9b3198 | 220 | * Returns the local/remote IP-address/hostname of socket as a string. |
221 | * The returned string must be freed. | |
3c0ef626 | 222 | */ |
223 | static char * | |
224 | get_socket_address(int socket, int remote, int flags) | |
225 | { | |
226 | struct sockaddr_storage addr; | |
227 | socklen_t addrlen; | |
228 | char ntop[NI_MAXHOST]; | |
229 | ||
230 | /* Get IP address of client. */ | |
231 | addrlen = sizeof(addr); | |
232 | memset(&addr, 0, sizeof(addr)); | |
233 | ||
234 | if (remote) { | |
235 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
41b2f314 | 236 | < 0) |
3c0ef626 | 237 | return NULL; |
3c0ef626 | 238 | } else { |
239 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
41b2f314 | 240 | < 0) |
3c0ef626 | 241 | return NULL; |
3c0ef626 | 242 | } |
6a9b3198 | 243 | |
244 | /* Work around Linux IPv6 weirdness */ | |
245 | if (addr.ss_family == AF_INET6) | |
246 | addrlen = sizeof(struct sockaddr_in6); | |
247 | ||
3c0ef626 | 248 | /* Get the address in ascii. */ |
249 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
e9a17296 | 250 | NULL, 0, flags) != 0) { |
6a9b3198 | 251 | error("get_socket_address: getnameinfo %d failed", flags); |
3c0ef626 | 252 | return NULL; |
253 | } | |
254 | return xstrdup(ntop); | |
255 | } | |
256 | ||
257 | char * | |
258 | get_peer_ipaddr(int socket) | |
259 | { | |
41b2f314 | 260 | char *p; |
261 | ||
262 | if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL) | |
263 | return p; | |
264 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 265 | } |
266 | ||
267 | char * | |
268 | get_local_ipaddr(int socket) | |
269 | { | |
41b2f314 | 270 | char *p; |
271 | ||
272 | if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL) | |
273 | return p; | |
274 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 275 | } |
276 | ||
277 | char * | |
278 | get_local_name(int socket) | |
279 | { | |
280 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
281 | } | |
282 | ||
283 | /* | |
284 | * Returns the IP-address of the remote host as a string. The returned | |
285 | * string must not be freed. | |
286 | */ | |
287 | ||
288 | const char * | |
e9a17296 | 289 | get_remote_ipaddr(void) |
3c0ef626 | 290 | { |
291 | static char *canonical_host_ip = NULL; | |
292 | ||
293 | /* Check whether we have cached the ipaddr. */ | |
294 | if (canonical_host_ip == NULL) { | |
295 | if (packet_connection_is_on_socket()) { | |
296 | canonical_host_ip = | |
297 | get_peer_ipaddr(packet_get_connection_in()); | |
298 | if (canonical_host_ip == NULL) | |
9cb1827b | 299 | fatal_cleanup(); |
3c0ef626 | 300 | } else { |
301 | /* If not on socket, return UNKNOWN. */ | |
302 | canonical_host_ip = xstrdup("UNKNOWN"); | |
303 | } | |
304 | } | |
305 | return canonical_host_ip; | |
306 | } | |
307 | ||
308 | const char * | |
0fff78ff | 309 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
3c0ef626 | 310 | { |
311 | static const char *remote = ""; | |
312 | if (utmp_len > 0) | |
0fff78ff | 313 | remote = get_canonical_hostname(use_dns); |
3c0ef626 | 314 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
315 | remote = get_remote_ipaddr(); | |
316 | return remote; | |
317 | } | |
318 | ||
319 | /* Returns the local/remote port for the socket. */ | |
320 | ||
321 | static int | |
322 | get_sock_port(int sock, int local) | |
323 | { | |
324 | struct sockaddr_storage from; | |
325 | socklen_t fromlen; | |
326 | char strport[NI_MAXSERV]; | |
327 | ||
328 | /* Get IP address of client. */ | |
329 | fromlen = sizeof(from); | |
330 | memset(&from, 0, sizeof(from)); | |
331 | if (local) { | |
332 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
333 | error("getsockname failed: %.100s", strerror(errno)); | |
334 | return 0; | |
335 | } | |
336 | } else { | |
6a9b3198 | 337 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 338 | debug("getpeername failed: %.100s", strerror(errno)); |
9cb1827b | 339 | fatal_cleanup(); |
3c0ef626 | 340 | } |
341 | } | |
6a9b3198 | 342 | |
343 | /* Work around Linux IPv6 weirdness */ | |
344 | if (from.ss_family == AF_INET6) | |
345 | fromlen = sizeof(struct sockaddr_in6); | |
346 | ||
3c0ef626 | 347 | /* Return port number. */ |
348 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, | |
e9a17296 | 349 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
3c0ef626 | 350 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
351 | return atoi(strport); | |
352 | } | |
353 | ||
354 | /* Returns remote/local port number for the current connection. */ | |
355 | ||
356 | static int | |
357 | get_port(int local) | |
358 | { | |
359 | /* | |
360 | * If the connection is not a socket, return 65535. This is | |
361 | * intentionally chosen to be an unprivileged port number. | |
362 | */ | |
363 | if (!packet_connection_is_on_socket()) | |
364 | return 65535; | |
365 | ||
366 | /* Get socket and return the port number. */ | |
367 | return get_sock_port(packet_get_connection_in(), local); | |
368 | } | |
369 | ||
370 | int | |
371 | get_peer_port(int sock) | |
372 | { | |
373 | return get_sock_port(sock, 0); | |
374 | } | |
375 | ||
376 | int | |
e9a17296 | 377 | get_remote_port(void) |
3c0ef626 | 378 | { |
379 | return get_port(0); | |
380 | } | |
381 | ||
382 | int | |
e9a17296 | 383 | get_local_port(void) |
3c0ef626 | 384 | { |
385 | return get_port(1); | |
386 | } |