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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" | |
d03f4262 | 15 | RCSID("$OpenBSD: canohost.c,v 1.34 2002/09/23 20:46:27 stevesk 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 * | |
dfe9414c | 30 | get_remote_hostname(int socket, int verify_reverse_mapping) |
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)); | |
41 | if (getpeername(socket, (struct sockaddr *) &from, &fromlen) < 0) { | |
42 | debug("getpeername failed: %.100s", strerror(errno)); | |
43 | fatal_cleanup(); | |
44 | } | |
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 | memcpy(&from4->sin_addr, &addr, sizeof(addr)); | |
63 | from4->sin_port = port; | |
64 | } | |
65 | } | |
66 | #endif | |
3c0ef626 | 67 | |
68 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), | |
dfe9414c | 69 | NULL, 0, NI_NUMERICHOST) != 0) |
3c0ef626 | 70 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
71 | ||
dfe9414c | 72 | if (from.ss_family == AF_INET) |
73 | check_ip_options(socket, 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), | |
dfe9414c | 78 | NULL, 0, NI_NAMEREQD) != 0) { |
3c0ef626 | 79 | /* Host name not found. Use ip address. */ |
d03f4262 | 80 | #if 0 |
3c0ef626 | 81 | log("Could not reverse map address %.100s.", ntop); |
d03f4262 | 82 | #endif |
3c0ef626 | 83 | return xstrdup(ntop); |
84 | } | |
85 | ||
86 | /* Got host name. */ | |
87 | name[sizeof(name) - 1] = '\0'; | |
88 | /* | |
89 | * Convert it to all lowercase (which is expected by the rest | |
90 | * of this software). | |
91 | */ | |
92 | for (i = 0; name[i]; i++) | |
93 | if (isupper(name[i])) | |
94 | name[i] = tolower(name[i]); | |
95 | ||
dfe9414c | 96 | if (!verify_reverse_mapping) |
3c0ef626 | 97 | return xstrdup(name); |
98 | /* | |
99 | * Map it back to an IP address and check that the given | |
100 | * address actually is an address of this host. This is | |
101 | * necessary because anyone with access to a name server can | |
102 | * define arbitrary names for an IP address. Mapping from | |
103 | * name to IP address can be trusted better (but can still be | |
104 | * fooled if the intruder has access to the name server of | |
105 | * the domain). | |
106 | */ | |
107 | memset(&hints, 0, sizeof(hints)); | |
108 | hints.ai_family = from.ss_family; | |
109 | hints.ai_socktype = SOCK_STREAM; | |
110 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
111 | log("reverse mapping checking getaddrinfo for %.700s " | |
112 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); | |
113 | return xstrdup(ntop); | |
114 | } | |
115 | /* Look for the address from the list of addresses. */ | |
116 | for (ai = aitop; ai; ai = ai->ai_next) { | |
117 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
118 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
119 | (strcmp(ntop, ntop2) == 0)) | |
120 | break; | |
121 | } | |
122 | freeaddrinfo(aitop); | |
123 | /* If we reached the end of the list, the address was not there. */ | |
124 | if (!ai) { | |
125 | /* Address not found for the host name. */ | |
126 | log("Address %.100s maps to %.600s, but this does not " | |
127 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", | |
128 | ntop, name); | |
129 | return xstrdup(ntop); | |
130 | } | |
131 | return xstrdup(name); | |
132 | } | |
133 | ||
134 | /* | |
135 | * If IP options are supported, make sure there are none (log and | |
136 | * disconnect them if any are found). Basically we are worried about | |
137 | * source routing; it can be used to pretend you are somebody | |
138 | * (ip-address) you are not. That itself may be "almost acceptable" | |
139 | * under certain circumstances, but rhosts autentication is useless | |
140 | * if source routing is accepted. Notice also that if we just dropped | |
141 | * source routing here, the other side could use IP spoofing to do | |
142 | * rest of the interaction and could still bypass security. So we | |
143 | * exit here if we detect any IP options. | |
144 | */ | |
145 | /* IPv4 only */ | |
146 | static void | |
147 | check_ip_options(int socket, char *ipaddr) | |
148 | { | |
149 | u_char options[200]; | |
150 | char text[sizeof(options) * 3 + 1]; | |
151 | socklen_t option_size; | |
152 | int i, ipproto; | |
153 | struct protoent *ip; | |
154 | ||
155 | if ((ip = getprotobyname("ip")) != NULL) | |
156 | ipproto = ip->p_proto; | |
157 | else | |
158 | ipproto = IPPROTO_IP; | |
159 | option_size = sizeof(options); | |
dfe9414c | 160 | if (getsockopt(socket, ipproto, IP_OPTIONS, options, |
3c0ef626 | 161 | &option_size) >= 0 && option_size != 0) { |
162 | text[0] = '\0'; | |
163 | for (i = 0; i < option_size; i++) | |
164 | snprintf(text + i*3, sizeof(text) - i*3, | |
165 | " %2.2x", options[i]); | |
166 | log("Connection from %.100s with IP options:%.800s", | |
167 | ipaddr, text); | |
168 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
169 | ipaddr, text); | |
170 | } | |
171 | } | |
172 | ||
173 | /* | |
174 | * Return the canonical name of the host in the other side of the current | |
175 | * connection. The host name is cached, so it is efficient to call this | |
176 | * several times. | |
177 | */ | |
178 | ||
179 | const char * | |
dfe9414c | 180 | get_canonical_hostname(int verify_reverse_mapping) |
3c0ef626 | 181 | { |
182 | static char *canonical_host_name = NULL; | |
dfe9414c | 183 | static int verify_reverse_mapping_done = 0; |
3c0ef626 | 184 | |
185 | /* Check if we have previously retrieved name with same option. */ | |
186 | if (canonical_host_name != NULL) { | |
dfe9414c | 187 | if (verify_reverse_mapping_done != verify_reverse_mapping) |
3c0ef626 | 188 | xfree(canonical_host_name); |
189 | else | |
190 | return canonical_host_name; | |
191 | } | |
192 | ||
193 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ | |
194 | if (packet_connection_is_on_socket()) | |
195 | canonical_host_name = get_remote_hostname( | |
dfe9414c | 196 | packet_get_connection_in(), verify_reverse_mapping); |
3c0ef626 | 197 | else |
198 | canonical_host_name = xstrdup("UNKNOWN"); | |
199 | ||
dfe9414c | 200 | verify_reverse_mapping_done = verify_reverse_mapping; |
3c0ef626 | 201 | return canonical_host_name; |
202 | } | |
203 | ||
204 | /* | |
205 | * Returns the remote IP-address of socket as a string. The returned | |
206 | * string must be freed. | |
207 | */ | |
208 | static char * | |
209 | get_socket_address(int socket, int remote, int flags) | |
210 | { | |
211 | struct sockaddr_storage addr; | |
212 | socklen_t addrlen; | |
213 | char ntop[NI_MAXHOST]; | |
214 | ||
215 | /* Get IP address of client. */ | |
216 | addrlen = sizeof(addr); | |
217 | memset(&addr, 0, sizeof(addr)); | |
218 | ||
219 | if (remote) { | |
220 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
d03f4262 | 221 | < 0) |
3c0ef626 | 222 | return NULL; |
3c0ef626 | 223 | } else { |
224 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
d03f4262 | 225 | < 0) |
3c0ef626 | 226 | return NULL; |
3c0ef626 | 227 | } |
228 | /* Get the address in ascii. */ | |
229 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
dfe9414c | 230 | NULL, 0, flags) != 0) { |
3c0ef626 | 231 | error("get_socket_ipaddr: getnameinfo %d failed", flags); |
232 | return NULL; | |
233 | } | |
234 | return xstrdup(ntop); | |
235 | } | |
236 | ||
237 | char * | |
238 | get_peer_ipaddr(int socket) | |
239 | { | |
d03f4262 | 240 | char *p; |
241 | ||
242 | if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL) | |
243 | return p; | |
244 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 245 | } |
246 | ||
247 | char * | |
248 | get_local_ipaddr(int socket) | |
249 | { | |
d03f4262 | 250 | char *p; |
251 | ||
252 | if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL) | |
253 | return p; | |
254 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 255 | } |
256 | ||
257 | char * | |
258 | get_local_name(int socket) | |
259 | { | |
260 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
261 | } | |
262 | ||
263 | /* | |
264 | * Returns the IP-address of the remote host as a string. The returned | |
265 | * string must not be freed. | |
266 | */ | |
267 | ||
268 | const char * | |
dfe9414c | 269 | get_remote_ipaddr(void) |
3c0ef626 | 270 | { |
271 | static char *canonical_host_ip = NULL; | |
272 | ||
273 | /* Check whether we have cached the ipaddr. */ | |
274 | if (canonical_host_ip == NULL) { | |
275 | if (packet_connection_is_on_socket()) { | |
276 | canonical_host_ip = | |
277 | get_peer_ipaddr(packet_get_connection_in()); | |
278 | if (canonical_host_ip == NULL) | |
279 | fatal_cleanup(); | |
280 | } else { | |
281 | /* If not on socket, return UNKNOWN. */ | |
282 | canonical_host_ip = xstrdup("UNKNOWN"); | |
283 | } | |
284 | } | |
285 | return canonical_host_ip; | |
286 | } | |
287 | ||
288 | const char * | |
dfe9414c | 289 | get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping) |
3c0ef626 | 290 | { |
291 | static const char *remote = ""; | |
292 | if (utmp_len > 0) | |
dfe9414c | 293 | remote = get_canonical_hostname(verify_reverse_mapping); |
3c0ef626 | 294 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
295 | remote = get_remote_ipaddr(); | |
296 | return remote; | |
297 | } | |
298 | ||
299 | /* Returns the local/remote port for the socket. */ | |
300 | ||
301 | static int | |
302 | get_sock_port(int sock, int local) | |
303 | { | |
304 | struct sockaddr_storage from; | |
305 | socklen_t fromlen; | |
306 | char strport[NI_MAXSERV]; | |
307 | ||
308 | /* Get IP address of client. */ | |
309 | fromlen = sizeof(from); | |
310 | memset(&from, 0, sizeof(from)); | |
311 | if (local) { | |
312 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
313 | error("getsockname failed: %.100s", strerror(errno)); | |
314 | return 0; | |
315 | } | |
316 | } else { | |
317 | if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) { | |
318 | debug("getpeername failed: %.100s", strerror(errno)); | |
319 | fatal_cleanup(); | |
320 | } | |
321 | } | |
322 | /* Return port number. */ | |
323 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, | |
dfe9414c | 324 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
3c0ef626 | 325 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
326 | return atoi(strport); | |
327 | } | |
328 | ||
329 | /* Returns remote/local port number for the current connection. */ | |
330 | ||
331 | static int | |
332 | get_port(int local) | |
333 | { | |
334 | /* | |
335 | * If the connection is not a socket, return 65535. This is | |
336 | * intentionally chosen to be an unprivileged port number. | |
337 | */ | |
338 | if (!packet_connection_is_on_socket()) | |
339 | return 65535; | |
340 | ||
341 | /* Get socket and return the port number. */ | |
342 | return get_sock_port(packet_get_connection_in(), local); | |
343 | } | |
344 | ||
345 | int | |
346 | get_peer_port(int sock) | |
347 | { | |
348 | return get_sock_port(sock, 0); | |
349 | } | |
350 | ||
351 | int | |
dfe9414c | 352 | get_remote_port(void) |
3c0ef626 | 353 | { |
354 | return get_port(0); | |
355 | } | |
356 | ||
357 | int | |
dfe9414c | 358 | get_local_port(void) |
3c0ef626 | 359 | { |
360 | return get_port(1); | |
361 | } | |
dfe9414c | 362 | |
dfe9414c | 363 | void |
1df48666 | 364 | resolve_localhost(char **host) |
dfe9414c | 365 | { |
366 | struct hostent *hostinfo; | |
367 | ||
368 | hostinfo = gethostbyname(*host); | |
890e8b9d | 369 | if (hostinfo == NULL || hostinfo->h_name == NULL) { |
370 | debug("gethostbyname(%s) failed", *host); | |
371 | return; | |
372 | } | |
1df48666 | 373 | if (hostinfo->h_addrtype == AF_INET) { |
dfe9414c | 374 | struct in_addr addr; |
375 | addr = *(struct in_addr *)(hostinfo->h_addr); | |
376 | if (ntohl(addr.s_addr) == INADDR_LOOPBACK) { | |
377 | char buf[MAXHOSTNAMELEN]; | |
890e8b9d | 378 | if (gethostname(buf, sizeof(buf)) < 0) { |
379 | debug("gethostname() failed"); | |
380 | return; | |
dfe9414c | 381 | } |
890e8b9d | 382 | hostinfo = gethostbyname(buf); |
1df48666 | 383 | xfree(*host); |
384 | *host = xstrdup(hostinfo->h_name); | |
dfe9414c | 385 | } |
386 | } | |
dfe9414c | 387 | } |