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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"
Darren Tucker3e33cec2003-10-02 16:12:36 +100015RCSID("$OpenBSD: canohost.c,v 1.38 2003/09/23 20:17:11 markus 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 Miller3a961dc2003-06-03 10:25:48 +100030get_remote_hostname(int socket, int use_dns)
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));
Ben Lindstromacaac972002-12-23 02:13:37 +000041 if (getpeername(socket, (struct sockaddr *)&from, &fromlen) < 0) {
Damien Miller95def091999-11-25 00:26:21 +110042 debug("getpeername failed: %.100s", strerror(errno));
Darren Tucker3e33cec2003-10-02 16:12:36 +100043 cleanup_exit(255);
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;
Damien Miller5e4471e2003-01-07 10:51:23 +110062 fromlen = sizeof(*from4);
Damien Miller7bcb0892000-03-11 20:45:40 +110063 memcpy(&from4->sin_addr, &addr, sizeof(addr));
64 from4->sin_port = port;
65 }
66 }
67#endif
Damien Miller5e4471e2003-01-07 10:51:23 +110068 if (from.ss_family == AF_INET6)
69 fromlen = sizeof(struct sockaddr_in6);
Damien Miller7bcb0892000-03-11 20:45:40 +110070
Damien Miller34132e52000-01-14 15:45:46 +110071 if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
Damien Miller9f0f5c62001-12-21 14:45:46 +110072 NULL, 0, NI_NUMERICHOST) != 0)
Damien Miller34132e52000-01-14 15:45:46 +110073 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
Damien Miller95def091999-11-25 00:26:21 +110074
Damien Miller3a961dc2003-06-03 10:25:48 +100075 if (!use_dns)
76 return xstrdup(ntop);
77
Ben Lindstrom9a17c9a2002-06-11 16:47:22 +000078 if (from.ss_family == AF_INET)
79 check_ip_options(socket, ntop);
80
Ben Lindstrom121c7852001-04-18 15:32:44 +000081 debug3("Trying to reverse map address %.100s.", ntop);
Damien Miller34132e52000-01-14 15:45:46 +110082 /* Map the IP address to a host name. */
83 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
Damien Miller9f0f5c62001-12-21 14:45:46 +110084 NULL, 0, NI_NAMEREQD) != 0) {
Damien Miller33804262001-02-04 23:20:18 +110085 /* Host name not found. Use ip address. */
Damien Miller33804262001-02-04 23:20:18 +110086 return xstrdup(ntop);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100087 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +100088
Damien Miller3a961dc2003-06-03 10:25:48 +100089 /*
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*/
Darren Tucker0f684862003-06-05 09:52:42 +100096 hints.ai_flags = AI_NUMERICHOST;
Damien Miller3a961dc2003-06-03 10:25:48 +100097 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
Damien Miller5428f641999-11-25 11:54:57 +1100104 /*
Damien Miller33804262001-02-04 23:20:18 +1100105 * Convert it to all lowercase (which is expected by the rest
106 * of this software).
Damien Miller5428f641999-11-25 11:54:57 +1100107 */
Damien Miller33804262001-02-04 23:20:18 +1100108 for (i = 0; name[i]; i++)
109 if (isupper(name[i]))
110 name[i] = tolower(name[i]);
Damien Miller33804262001-02-04 23:20:18 +1100111 /*
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) {
Damien Miller996acd22003-04-09 20:59:48 +1000124 logit("reverse mapping checking getaddrinfo for %.700s "
Damien Miller33804262001-02-04 23:20:18 +1100125 "failed - POSSIBLE BREAKIN ATTEMPT!", name);
126 return xstrdup(ntop);
Damien Miller95def091999-11-25 00:26:21 +1100127 }
Damien Miller33804262001-02-04 23:20:18 +1100128 /* 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. */
Damien Miller996acd22003-04-09 20:59:48 +1000139 logit("Address %.100s maps to %.600s, but this does not "
Damien Miller33804262001-02-04 23:20:18 +1100140 "map back to the address - POSSIBLE BREAKIN ATTEMPT!",
141 ntop, name);
142 return xstrdup(ntop);
143 }
Damien Miller95def091999-11-25 00:26:21 +1100144 return xstrdup(name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000145}
146
Damien Miller5428f641999-11-25 11:54:57 +1100147/*
Damien Miller33804262001-02-04 23:20:18 +1100148 * 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 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000159static void
Damien Miller33804262001-02-04 23:20:18 +1100160check_ip_options(int socket, char *ipaddr)
161{
Darren Tucker89f4cf02003-08-07 13:29:04 +1000162#ifdef IP_OPTIONS
Ben Lindstrom075390a2001-02-10 21:34:46 +0000163 u_char options[200];
164 char text[sizeof(options) * 3 + 1];
Damien Miller33804262001-02-04 23:20:18 +1100165 socklen_t option_size;
Ben Lindstrom075390a2001-02-10 21:34:46 +0000166 int i, ipproto;
Damien Miller33804262001-02-04 23:20:18 +1100167 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);
Ben Lindstrom733a2352002-03-05 01:31:28 +0000174 if (getsockopt(socket, ipproto, IP_OPTIONS, options,
Damien Miller33804262001-02-04 23:20:18 +1100175 &option_size) >= 0 && option_size != 0) {
Ben Lindstrom075390a2001-02-10 21:34:46 +0000176 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]);
Damien Miller996acd22003-04-09 20:59:48 +1000180 logit("Connection from %.100s with IP options:%.800s",
Damien Miller33804262001-02-04 23:20:18 +1100181 ipaddr, text);
182 packet_disconnect("Connection from %.100s with IP options:%.800s",
183 ipaddr, text);
184 }
Darren Tucker89f4cf02003-08-07 13:29:04 +1000185#endif /* IP_OPTIONS */
Damien Miller33804262001-02-04 23:20:18 +1100186}
187
188/*
Damien Miller5428f641999-11-25 11:54:57 +1100189 * 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 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000193
Damien Miller95def091999-11-25 00:26:21 +1100194const char *
Damien Miller3a961dc2003-06-03 10:25:48 +1000195get_canonical_hostname(int use_dns)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000196{
Damien Miller34132e52000-01-14 15:45:46 +1100197 static char *canonical_host_name = NULL;
Damien Miller3a961dc2003-06-03 10:25:48 +1000198 static int use_dns_done = 0;
Damien Miller34132e52000-01-14 15:45:46 +1100199
Damien Miller33804262001-02-04 23:20:18 +1100200 /* Check if we have previously retrieved name with same option. */
201 if (canonical_host_name != NULL) {
Damien Miller3a961dc2003-06-03 10:25:48 +1000202 if (use_dns_done != use_dns)
Damien Miller33804262001-02-04 23:20:18 +1100203 xfree(canonical_host_name);
204 else
205 return canonical_host_name;
206 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000207
Damien Miller95def091999-11-25 00:26:21 +1100208 /* Get the real hostname if socket; otherwise return UNKNOWN. */
Damien Miller34132e52000-01-14 15:45:46 +1100209 if (packet_connection_is_on_socket())
Damien Miller33804262001-02-04 23:20:18 +1100210 canonical_host_name = get_remote_hostname(
Damien Miller3a961dc2003-06-03 10:25:48 +1000211 packet_get_connection_in(), use_dns);
Damien Miller95def091999-11-25 00:26:21 +1100212 else
213 canonical_host_name = xstrdup("UNKNOWN");
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000214
Damien Miller3a961dc2003-06-03 10:25:48 +1000215 use_dns_done = use_dns;
Damien Miller95def091999-11-25 00:26:21 +1100216 return canonical_host_name;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000217}
218
Damien Miller5428f641999-11-25 11:54:57 +1100219/*
Ben Lindstromacaac972002-12-23 02:13:37 +0000220 * Returns the local/remote IP-address/hostname of socket as a string.
221 * The returned string must be freed.
Damien Millerd83ff352001-01-30 09:19:34 +1100222 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000223static char *
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000224get_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)
Damien Millerb2f844d2002-09-25 12:19:08 +1000236 < 0)
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000237 return NULL;
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000238 } else {
239 if (getsockname(socket, (struct sockaddr *)&addr, &addrlen)
Damien Millerb2f844d2002-09-25 12:19:08 +1000240 < 0)
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000241 return NULL;
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000242 }
Damien Miller5e4471e2003-01-07 10:51:23 +1100243
244 /* Work around Linux IPv6 weirdness */
245 if (addr.ss_family == AF_INET6)
246 addrlen = sizeof(struct sockaddr_in6);
247
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000248 /* Get the address in ascii. */
249 if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop),
Damien Miller9f0f5c62001-12-21 14:45:46 +1100250 NULL, 0, flags) != 0) {
Ben Lindstromacaac972002-12-23 02:13:37 +0000251 error("get_socket_address: getnameinfo %d failed", flags);
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000252 return NULL;
253 }
254 return xstrdup(ntop);
255}
Damien Millerd83ff352001-01-30 09:19:34 +1100256
257char *
258get_peer_ipaddr(int socket)
259{
Damien Millerb2f844d2002-09-25 12:19:08 +1000260 char *p;
261
262 if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL)
263 return p;
264 return xstrdup("UNKNOWN");
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000265}
Damien Millerd83ff352001-01-30 09:19:34 +1100266
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000267char *
268get_local_ipaddr(int socket)
269{
Damien Millerb2f844d2002-09-25 12:19:08 +1000270 char *p;
271
272 if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL)
273 return p;
274 return xstrdup("UNKNOWN");
Ben Lindstrom5eabda32001-04-12 23:34:34 +0000275}
276
277char *
278get_local_name(int socket)
279{
280 return get_socket_address(socket, 0, NI_NAMEREQD);
Damien Millerd83ff352001-01-30 09:19:34 +1100281}
282
283/*
Damien Miller5428f641999-11-25 11:54:57 +1100284 * Returns the IP-address of the remote host as a string. The returned
Damien Miller34132e52000-01-14 15:45:46 +1100285 * string must not be freed.
Damien Miller5428f641999-11-25 11:54:57 +1100286 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000287
Damien Miller95def091999-11-25 00:26:21 +1100288const char *
Ben Lindstrom3c36bb22001-12-06 17:55:26 +0000289get_remote_ipaddr(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000290{
Damien Miller34132e52000-01-14 15:45:46 +1100291 static char *canonical_host_ip = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000292
Damien Millerd83ff352001-01-30 09:19:34 +1100293 /* 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)
Darren Tucker3e33cec2003-10-02 16:12:36 +1000299 cleanup_exit(255);
Damien Millerd83ff352001-01-30 09:19:34 +1100300 } else {
301 /* If not on socket, return UNKNOWN. */
302 canonical_host_ip = xstrdup("UNKNOWN");
303 }
Damien Miller95def091999-11-25 00:26:21 +1100304 }
Damien Miller95def091999-11-25 00:26:21 +1100305 return canonical_host_ip;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000306}
307
Ben Lindstromf15a3862001-04-05 23:32:17 +0000308const char *
Damien Miller3a961dc2003-06-03 10:25:48 +1000309get_remote_name_or_ip(u_int utmp_len, int use_dns)
Ben Lindstromf15a3862001-04-05 23:32:17 +0000310{
311 static const char *remote = "";
312 if (utmp_len > 0)
Damien Miller3a961dc2003-06-03 10:25:48 +1000313 remote = get_canonical_hostname(use_dns);
Ben Lindstromf15a3862001-04-05 23:32:17 +0000314 if (utmp_len == 0 || strlen(remote) > utmp_len)
315 remote = get_remote_ipaddr();
316 return remote;
317}
318
Damien Miller34132e52000-01-14 15:45:46 +1100319/* Returns the local/remote port for the socket. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000320
Ben Lindstrombba81212001-06-25 05:01:22 +0000321static int
Damien Miller34132e52000-01-14 15:45:46 +1100322get_sock_port(int sock, int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000323{
Damien Miller34132e52000-01-14 15:45:46 +1100324 struct sockaddr_storage from;
325 socklen_t fromlen;
326 char strport[NI_MAXSERV];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000327
Damien Miller95def091999-11-25 00:26:21 +1100328 /* Get IP address of client. */
329 fromlen = sizeof(from);
330 memset(&from, 0, sizeof(from));
Damien Miller34132e52000-01-14 15:45:46 +1100331 if (local) {
332 if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
333 error("getsockname failed: %.100s", strerror(errno));
334 return 0;
335 }
336 } else {
Ben Lindstromacaac972002-12-23 02:13:37 +0000337 if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
Damien Miller34132e52000-01-14 15:45:46 +1100338 debug("getpeername failed: %.100s", strerror(errno));
Darren Tucker3e33cec2003-10-02 16:12:36 +1000339 cleanup_exit(255);
Damien Miller34132e52000-01-14 15:45:46 +1100340 }
Damien Miller95def091999-11-25 00:26:21 +1100341 }
Damien Miller5e4471e2003-01-07 10:51:23 +1100342
343 /* Work around Linux IPv6 weirdness */
344 if (from.ss_family == AF_INET6)
345 fromlen = sizeof(struct sockaddr_in6);
346
Damien Miller95def091999-11-25 00:26:21 +1100347 /* Return port number. */
Damien Miller34132e52000-01-14 15:45:46 +1100348 if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
Damien Miller9f0f5c62001-12-21 14:45:46 +1100349 strport, sizeof(strport), NI_NUMERICSERV) != 0)
Damien Miller34132e52000-01-14 15:45:46 +1100350 fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
351 return atoi(strport);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000352}
353
Damien Miller34132e52000-01-14 15:45:46 +1100354/* Returns remote/local port number for the current connection. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000355
Ben Lindstrombba81212001-06-25 05:01:22 +0000356static int
Damien Miller34132e52000-01-14 15:45:46 +1100357get_port(int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000358{
Damien Miller5428f641999-11-25 11:54:57 +1100359 /*
360 * If the connection is not a socket, return 65535. This is
361 * intentionally chosen to be an unprivileged port number.
362 */
Damien Miller34132e52000-01-14 15:45:46 +1100363 if (!packet_connection_is_on_socket())
Damien Miller95def091999-11-25 00:26:21 +1100364 return 65535;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000365
Damien Miller34132e52000-01-14 15:45:46 +1100366 /* Get socket and return the port number. */
367 return get_sock_port(packet_get_connection_in(), local);
368}
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000369
Damien Miller4af51302000-04-16 11:18:38 +1000370int
Damien Miller34132e52000-01-14 15:45:46 +1100371get_peer_port(int sock)
372{
373 return get_sock_port(sock, 0);
374}
375
Damien Miller4af51302000-04-16 11:18:38 +1000376int
Ben Lindstrom3c36bb22001-12-06 17:55:26 +0000377get_remote_port(void)
Damien Miller34132e52000-01-14 15:45:46 +1100378{
379 return get_port(0);
380}
381
382int
Ben Lindstrom3c36bb22001-12-06 17:55:26 +0000383get_local_port(void)
Damien Miller34132e52000-01-14 15:45:46 +1100384{
385 return get_port(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000386}