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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller95def091999-11-25 00:26:21 +11003 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11005 * Functions for returning the canonical host name of the remote site.
Damien Miller4af51302000-04-16 11:18:38 +10006 *
Damien Millere4340be2000-09-16 13:29:08 +11007 * 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".
Damien Miller95def091999-11-25 00:26:21 +110012 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100013
14#include "includes.h"
Ben Lindstrome9827732002-07-11 03:56:46 +000015RCSID("$OpenBSD: canohost.c,v 1.33 2002/07/09 11:56:27 itojun Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100016
17#include "packet.h"
18#include "xmalloc.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000019#include "log.h"
Ben Lindstrom31ca54a2001-02-09 02:11:24 +000020#include "canohost.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100021
Ben Lindstrombba81212001-06-25 05:01:22 +000022static void check_ip_options(int, char *);
Damien Miller33804262001-02-04 23:20:18 +110023
Damien Miller5428f641999-11-25 11:54:57 +110024/*
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 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100028
Ben Lindstrombba81212001-06-25 05:01:22 +000029static char *
Damien Millerc5d86352002-02-05 12:13:41 +110030get_remote_hostname(int socket, int verify_reverse_mapping)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100031{
Damien Miller34132e52000-01-14 15:45:46 +110032 struct sockaddr_storage from;
33 int i;
34 socklen_t fromlen;
35 struct addrinfo hints, *ai, *aitop;
Damien Miller33804262001-02-04 23:20:18 +110036 char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
Damien Millerd4a8b7e1999-10-27 13:42:43 +100037
Damien Miller95def091999-11-25 00:26:21 +110038 /* Get IP address of client. */
39 fromlen = sizeof(from);
40 memset(&from, 0, sizeof(from));
Damien Miller33804262001-02-04 23:20:18 +110041 if (getpeername(socket, (struct sockaddr *) &from, &fromlen) < 0) {
Damien Miller95def091999-11-25 00:26:21 +110042 debug("getpeername failed: %.100s", strerror(errno));
43 fatal_cleanup();
Damien Millerd4a8b7e1999-10-27 13:42:43 +100044 }
Damien Miller7bcb0892000-03-11 20:45:40 +110045#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));
Kevin Stevesef4eea92001-02-05 12:42:17 +000060
Damien Miller7bcb0892000-03-11 20:45:40 +110061 from4->sin_family = AF_INET;
62 memcpy(&from4->sin_addr, &addr, sizeof(addr));
63 from4->sin_port = port;
64 }
65 }
66#endif
67
Damien Miller34132e52000-01-14 15:45:46 +110068 if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
Damien Miller9f0f5c62001-12-21 14:45:46 +110069 NULL, 0, NI_NUMERICHOST) != 0)
Damien Miller34132e52000-01-14 15:45:46 +110070 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
Damien Miller95def091999-11-25 00:26:21 +110071
Ben Lindstrom9a17c9a2002-06-11 16:47:22 +000072 if (from.ss_family == AF_INET)
73 check_ip_options(socket, ntop);
74
Ben Lindstrom121c7852001-04-18 15:32:44 +000075 debug3("Trying to reverse map address %.100s.", ntop);
Damien Miller34132e52000-01-14 15:45:46 +110076 /* Map the IP address to a host name. */
77 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
Damien Miller9f0f5c62001-12-21 14:45:46 +110078 NULL, 0, NI_NAMEREQD) != 0) {
Damien Miller33804262001-02-04 23:20:18 +110079 /* Host name not found. Use ip address. */
Ben Lindstrome9827732002-07-11 03:56:46 +000080#if 0
Damien Miller33804262001-02-04 23:20:18 +110081 log("Could not reverse map address %.100s.", ntop);
Ben Lindstrome9827732002-07-11 03:56:46 +000082#endif
Damien Miller33804262001-02-04 23:20:18 +110083 return xstrdup(ntop);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100084 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +100085
Damien Miller33804262001-02-04 23:20:18 +110086 /* Got host name. */
87 name[sizeof(name) - 1] = '\0';
Damien Miller5428f641999-11-25 11:54:57 +110088 /*
Damien Miller33804262001-02-04 23:20:18 +110089 * Convert it to all lowercase (which is expected by the rest
90 * of this software).
Damien Miller5428f641999-11-25 11:54:57 +110091 */
Damien Miller33804262001-02-04 23:20:18 +110092 for (i = 0; name[i]; i++)
93 if (isupper(name[i]))
94 name[i] = tolower(name[i]);
Damien Miller95def091999-11-25 00:26:21 +110095
Damien Millerc5d86352002-02-05 12:13:41 +110096 if (!verify_reverse_mapping)
Damien Miller33804262001-02-04 23:20:18 +110097 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);
Damien Miller95def091999-11-25 00:26:21 +1100114 }
Damien Miller33804262001-02-04 23:20:18 +1100115 /* 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 }
Damien Miller95def091999-11-25 00:26:21 +1100131 return xstrdup(name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000132}
133
Damien Miller5428f641999-11-25 11:54:57 +1100134/*
Damien Miller33804262001-02-04 23:20:18 +1100135 * 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 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000146static void
Damien Miller33804262001-02-04 23:20:18 +1100147check_ip_options(int socket, char *ipaddr)
148{
Ben Lindstrom075390a2001-02-10 21:34:46 +0000149 u_char options[200];
150 char text[sizeof(options) * 3 + 1];
Damien Miller33804262001-02-04 23:20:18 +1100151 socklen_t option_size;
Ben Lindstrom075390a2001-02-10 21:34:46 +0000152 int i, ipproto;
Damien Miller33804262001-02-04 23:20:18 +1100153 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);
Ben Lindstrom733a2352002-03-05 01:31:28 +0000160 if (getsockopt(socket, ipproto, IP_OPTIONS, options,
Damien Miller33804262001-02-04 23:20:18 +1100161 &option_size) >= 0 && option_size != 0) {
Ben Lindstrom075390a2001-02-10 21:34:46 +0000162 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]);
Damien Miller33804262001-02-04 23:20:18 +1100166 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/*
Damien Miller5428f641999-11-25 11:54:57 +1100174 * 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 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000178
Damien Miller95def091999-11-25 00:26:21 +1100179const char *
Damien Millerc5d86352002-02-05 12:13:41 +1100180get_canonical_hostname(int verify_reverse_mapping)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000181{
Damien Miller34132e52000-01-14 15:45:46 +1100182 static char *canonical_host_name = NULL;
Damien Millerc5d86352002-02-05 12:13:41 +1100183 static int verify_reverse_mapping_done = 0;
Damien Miller34132e52000-01-14 15:45:46 +1100184
Damien Miller33804262001-02-04 23:20:18 +1100185 /* Check if we have previously retrieved name with same option. */
186 if (canonical_host_name != NULL) {
Damien Millerc5d86352002-02-05 12:13:41 +1100187 if (verify_reverse_mapping_done != verify_reverse_mapping)
Damien Miller33804262001-02-04 23:20:18 +1100188 xfree(canonical_host_name);
189 else
190 return canonical_host_name;
191 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000192
Damien Miller95def091999-11-25 00:26:21 +1100193 /* Get the real hostname if socket; otherwise return UNKNOWN. */
Damien Miller34132e52000-01-14 15:45:46 +1100194 if (packet_connection_is_on_socket())
Damien Miller33804262001-02-04 23:20:18 +1100195 canonical_host_name = get_remote_hostname(
Damien Millerc5d86352002-02-05 12:13:41 +1100196 packet_get_connection_in(), verify_reverse_mapping);
Damien Miller95def091999-11-25 00:26:21 +1100197 else
198 canonical_host_name = xstrdup("UNKNOWN");
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000199
Damien Millerc5d86352002-02-05 12:13:41 +1100200 verify_reverse_mapping_done = verify_reverse_mapping;
Damien Miller95def091999-11-25 00:26:21 +1100201 return canonical_host_name;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000202}
203
Damien Miller5428f641999-11-25 11:54:57 +1100204/*
Damien Millerd83ff352001-01-30 09:19:34 +1100205 * Returns the remote IP-address of socket as a string. The returned
206 * string must be freed.
207 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000208static char *
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000209get_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)
221 < 0) {
222 debug("get_socket_ipaddr: getpeername failed: %.100s",
223 strerror(errno));
224 return NULL;
225 }
226 } else {
227 if (getsockname(socket, (struct sockaddr *)&addr, &addrlen)
228 < 0) {
229 debug("get_socket_ipaddr: getsockname failed: %.100s",
230 strerror(errno));
231 return NULL;
232 }
233 }
234 /* Get the address in ascii. */
235 if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop),
Damien Miller9f0f5c62001-12-21 14:45:46 +1100236 NULL, 0, flags) != 0) {
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000237 error("get_socket_ipaddr: getnameinfo %d failed", flags);
238 return NULL;
239 }
240 return xstrdup(ntop);
241}
Damien Millerd83ff352001-01-30 09:19:34 +1100242
243char *
244get_peer_ipaddr(int socket)
245{
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000246 return get_socket_address(socket, 1, NI_NUMERICHOST);
247}
Damien Millerd83ff352001-01-30 09:19:34 +1100248
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000249char *
250get_local_ipaddr(int socket)
251{
252 return get_socket_address(socket, 0, NI_NUMERICHOST);
253}
254
255char *
256get_local_name(int socket)
257{
258 return get_socket_address(socket, 0, NI_NAMEREQD);
Damien Millerd83ff352001-01-30 09:19:34 +1100259}
260
261/*
Damien Miller5428f641999-11-25 11:54:57 +1100262 * Returns the IP-address of the remote host as a string. The returned
Damien Miller34132e52000-01-14 15:45:46 +1100263 * string must not be freed.
Damien Miller5428f641999-11-25 11:54:57 +1100264 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000265
Damien Miller95def091999-11-25 00:26:21 +1100266const char *
Ben Lindstrom3c36bb22001-12-06 17:55:26 +0000267get_remote_ipaddr(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000268{
Damien Miller34132e52000-01-14 15:45:46 +1100269 static char *canonical_host_ip = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000270
Damien Millerd83ff352001-01-30 09:19:34 +1100271 /* Check whether we have cached the ipaddr. */
272 if (canonical_host_ip == NULL) {
273 if (packet_connection_is_on_socket()) {
274 canonical_host_ip =
275 get_peer_ipaddr(packet_get_connection_in());
276 if (canonical_host_ip == NULL)
277 fatal_cleanup();
278 } else {
279 /* If not on socket, return UNKNOWN. */
280 canonical_host_ip = xstrdup("UNKNOWN");
281 }
Damien Miller95def091999-11-25 00:26:21 +1100282 }
Damien Miller95def091999-11-25 00:26:21 +1100283 return canonical_host_ip;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000284}
285
Ben Lindstromf15a3862001-04-05 23:32:17 +0000286const char *
Damien Millerc5d86352002-02-05 12:13:41 +1100287get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping)
Ben Lindstromf15a3862001-04-05 23:32:17 +0000288{
289 static const char *remote = "";
290 if (utmp_len > 0)
Damien Millerc5d86352002-02-05 12:13:41 +1100291 remote = get_canonical_hostname(verify_reverse_mapping);
Ben Lindstromf15a3862001-04-05 23:32:17 +0000292 if (utmp_len == 0 || strlen(remote) > utmp_len)
293 remote = get_remote_ipaddr();
294 return remote;
295}
296
Damien Miller34132e52000-01-14 15:45:46 +1100297/* Returns the local/remote port for the socket. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000298
Ben Lindstrombba81212001-06-25 05:01:22 +0000299static int
Damien Miller34132e52000-01-14 15:45:46 +1100300get_sock_port(int sock, int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000301{
Damien Miller34132e52000-01-14 15:45:46 +1100302 struct sockaddr_storage from;
303 socklen_t fromlen;
304 char strport[NI_MAXSERV];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000305
Damien Miller95def091999-11-25 00:26:21 +1100306 /* Get IP address of client. */
307 fromlen = sizeof(from);
308 memset(&from, 0, sizeof(from));
Damien Miller34132e52000-01-14 15:45:46 +1100309 if (local) {
310 if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
311 error("getsockname failed: %.100s", strerror(errno));
312 return 0;
313 }
314 } else {
315 if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
316 debug("getpeername failed: %.100s", strerror(errno));
317 fatal_cleanup();
318 }
Damien Miller95def091999-11-25 00:26:21 +1100319 }
320 /* Return port number. */
Damien Miller34132e52000-01-14 15:45:46 +1100321 if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
Damien Miller9f0f5c62001-12-21 14:45:46 +1100322 strport, sizeof(strport), NI_NUMERICSERV) != 0)
Damien Miller34132e52000-01-14 15:45:46 +1100323 fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
324 return atoi(strport);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000325}
326
Damien Miller34132e52000-01-14 15:45:46 +1100327/* Returns remote/local port number for the current connection. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000328
Ben Lindstrombba81212001-06-25 05:01:22 +0000329static int
Damien Miller34132e52000-01-14 15:45:46 +1100330get_port(int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000331{
Damien Miller5428f641999-11-25 11:54:57 +1100332 /*
333 * If the connection is not a socket, return 65535. This is
334 * intentionally chosen to be an unprivileged port number.
335 */
Damien Miller34132e52000-01-14 15:45:46 +1100336 if (!packet_connection_is_on_socket())
Damien Miller95def091999-11-25 00:26:21 +1100337 return 65535;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000338
Damien Miller34132e52000-01-14 15:45:46 +1100339 /* Get socket and return the port number. */
340 return get_sock_port(packet_get_connection_in(), local);
341}
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000342
Damien Miller4af51302000-04-16 11:18:38 +1000343int
Damien Miller34132e52000-01-14 15:45:46 +1100344get_peer_port(int sock)
345{
346 return get_sock_port(sock, 0);
347}
348
Damien Miller4af51302000-04-16 11:18:38 +1000349int
Ben Lindstrom3c36bb22001-12-06 17:55:26 +0000350get_remote_port(void)
Damien Miller34132e52000-01-14 15:45:46 +1100351{
352 return get_port(0);
353}
354
355int
Ben Lindstrom3c36bb22001-12-06 17:55:26 +0000356get_local_port(void)
Damien Miller34132e52000-01-14 15:45:46 +1100357{
358 return get_port(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000359}