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-rw-r--r--canohost.c262
1 files changed, 10 insertions, 252 deletions
diff --git a/canohost.c b/canohost.c
index 223964ea3..f71a08568 100644
--- a/canohost.c
+++ b/canohost.c
@@ -1,4 +1,4 @@
1/* $OpenBSD: canohost.c,v 1.72 2015/03/01 15:44:40 millert Exp $ */ 1/* $OpenBSD: canohost.c,v 1.73 2016/03/07 19:02:43 djm Exp $ */
2/* 2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -35,147 +35,6 @@
35#include "canohost.h" 35#include "canohost.h"
36#include "misc.h" 36#include "misc.h"
37 37
38static void check_ip_options(int, char *);
39static char *canonical_host_ip = NULL;
40static int cached_port = -1;
41
42/*
43 * Return the canonical name of the host at the other end of the socket. The
44 * caller should free the returned string.
45 */
46
47static char *
48get_remote_hostname(int sock, int use_dns)
49{
50 struct sockaddr_storage from;
51 socklen_t fromlen;
52 struct addrinfo hints, *ai, *aitop;
53 char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
54
55 /* Get IP address of client. */
56 fromlen = sizeof(from);
57 memset(&from, 0, sizeof(from));
58 if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
59 debug("getpeername failed: %.100s", strerror(errno));
60 cleanup_exit(255);
61 }
62
63 if (from.ss_family == AF_INET)
64 check_ip_options(sock, ntop);
65
66 ipv64_normalise_mapped(&from, &fromlen);
67
68 if (from.ss_family == AF_INET6)
69 fromlen = sizeof(struct sockaddr_in6);
70
71 if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
72 NULL, 0, NI_NUMERICHOST) != 0)
73 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
74
75 if (!use_dns)
76 return xstrdup(ntop);
77
78 debug3("Trying to reverse map address %.100s.", ntop);
79 /* Map the IP address to a host name. */
80 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
81 NULL, 0, NI_NAMEREQD) != 0) {
82 /* Host name not found. Use ip address. */
83 return xstrdup(ntop);
84 }
85
86 /*
87 * if reverse lookup result looks like a numeric hostname,
88 * someone is trying to trick us by PTR record like following:
89 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
90 */
91 memset(&hints, 0, sizeof(hints));
92 hints.ai_socktype = SOCK_DGRAM; /*dummy*/
93 hints.ai_flags = AI_NUMERICHOST;
94 if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
95 logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
96 name, ntop);
97 freeaddrinfo(ai);
98 return xstrdup(ntop);
99 }
100
101 /* Names are stores in lowercase. */
102 lowercase(name);
103
104 /*
105 * Map it back to an IP address and check that the given
106 * address actually is an address of this host. This is
107 * necessary because anyone with access to a name server can
108 * define arbitrary names for an IP address. Mapping from
109 * name to IP address can be trusted better (but can still be
110 * fooled if the intruder has access to the name server of
111 * the domain).
112 */
113 memset(&hints, 0, sizeof(hints));
114 hints.ai_family = from.ss_family;
115 hints.ai_socktype = SOCK_STREAM;
116 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
117 logit("reverse mapping checking getaddrinfo for %.700s "
118 "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop);
119 return xstrdup(ntop);
120 }
121 /* Look for the address from the list of addresses. */
122 for (ai = aitop; ai; ai = ai->ai_next) {
123 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
124 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
125 (strcmp(ntop, ntop2) == 0))
126 break;
127 }
128 freeaddrinfo(aitop);
129 /* If we reached the end of the list, the address was not there. */
130 if (!ai) {
131 /* Address not found for the host name. */
132 logit("Address %.100s maps to %.600s, but this does not "
133 "map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
134 ntop, name);
135 return xstrdup(ntop);
136 }
137 return xstrdup(name);
138}
139
140/*
141 * If IP options are supported, make sure there are none (log and
142 * disconnect them if any are found). Basically we are worried about
143 * source routing; it can be used to pretend you are somebody
144 * (ip-address) you are not. That itself may be "almost acceptable"
145 * under certain circumstances, but rhosts autentication is useless
146 * if source routing is accepted. Notice also that if we just dropped
147 * source routing here, the other side could use IP spoofing to do
148 * rest of the interaction and could still bypass security. So we
149 * exit here if we detect any IP options.
150 */
151/* IPv4 only */
152static void
153check_ip_options(int sock, char *ipaddr)
154{
155#ifdef IP_OPTIONS
156 u_char options[200];
157 char text[sizeof(options) * 3 + 1];
158 socklen_t option_size, i;
159 int ipproto;
160 struct protoent *ip;
161
162 if ((ip = getprotobyname("ip")) != NULL)
163 ipproto = ip->p_proto;
164 else
165 ipproto = IPPROTO_IP;
166 option_size = sizeof(options);
167 if (getsockopt(sock, ipproto, IP_OPTIONS, options,
168 &option_size) >= 0 && option_size != 0) {
169 text[0] = '\0';
170 for (i = 0; i < option_size; i++)
171 snprintf(text + i*3, sizeof(text) - i*3,
172 " %2.2x", options[i]);
173 fatal("Connection from %.100s with IP options:%.800s",
174 ipaddr, text);
175 }
176#endif /* IP_OPTIONS */
177}
178
179void 38void
180ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) 39ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len)
181{ 40{
@@ -202,38 +61,6 @@ ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len)
202} 61}
203 62
204/* 63/*
205 * Return the canonical name of the host in the other side of the current
206 * connection. The host name is cached, so it is efficient to call this
207 * several times.
208 */
209
210const char *
211get_canonical_hostname(int use_dns)
212{
213 char *host;
214 static char *canonical_host_name = NULL;
215 static char *remote_ip = NULL;
216
217 /* Check if we have previously retrieved name with same option. */
218 if (use_dns && canonical_host_name != NULL)
219 return canonical_host_name;
220 if (!use_dns && remote_ip != NULL)
221 return remote_ip;
222
223 /* Get the real hostname if socket; otherwise return UNKNOWN. */
224 if (packet_connection_is_on_socket())
225 host = get_remote_hostname(packet_get_connection_in(), use_dns);
226 else
227 host = "UNKNOWN";
228
229 if (use_dns)
230 canonical_host_name = host;
231 else
232 remote_ip = host;
233 return host;
234}
235
236/*
237 * Returns the local/remote IP-address/hostname of socket as a string. 64 * Returns the local/remote IP-address/hostname of socket as a string.
238 * The returned string must be freed. 65 * The returned string must be freed.
239 */ 66 */
@@ -250,12 +77,10 @@ get_socket_address(int sock, int remote, int flags)
250 memset(&addr, 0, sizeof(addr)); 77 memset(&addr, 0, sizeof(addr));
251 78
252 if (remote) { 79 if (remote) {
253 if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) 80 if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) != 0)
254 < 0)
255 return NULL; 81 return NULL;
256 } else { 82 } else {
257 if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) 83 if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) != 0)
258 < 0)
259 return NULL; 84 return NULL;
260 } 85 }
261 86
@@ -271,7 +96,7 @@ get_socket_address(int sock, int remote, int flags)
271 /* Get the address in ascii. */ 96 /* Get the address in ascii. */
272 if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, 97 if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
273 sizeof(ntop), NULL, 0, flags)) != 0) { 98 sizeof(ntop), NULL, 0, flags)) != 0) {
274 error("get_socket_address: getnameinfo %d failed: %s", 99 error("%s: getnameinfo %d failed: %s", __func__,
275 flags, ssh_gai_strerror(r)); 100 flags, ssh_gai_strerror(r));
276 return NULL; 101 return NULL;
277 } 102 }
@@ -316,7 +141,8 @@ get_local_name(int fd)
316 141
317 /* Handle the case where we were passed a pipe */ 142 /* Handle the case where we were passed a pipe */
318 if (gethostname(myname, sizeof(myname)) == -1) { 143 if (gethostname(myname, sizeof(myname)) == -1) {
319 verbose("get_local_name: gethostname: %s", strerror(errno)); 144 verbose("%s: gethostname: %s", __func__, strerror(errno));
145 host = xstrdup("UNKNOWN");
320 } else { 146 } else {
321 host = xstrdup(myname); 147 host = xstrdup(myname);
322 } 148 }
@@ -324,51 +150,9 @@ get_local_name(int fd)
324 return host; 150 return host;
325} 151}
326 152
327void
328clear_cached_addr(void)
329{
330 free(canonical_host_ip);
331 canonical_host_ip = NULL;
332 cached_port = -1;
333}
334
335/*
336 * Returns the IP-address of the remote host as a string. The returned
337 * string must not be freed.
338 */
339
340const char *
341get_remote_ipaddr(void)
342{
343 /* Check whether we have cached the ipaddr. */
344 if (canonical_host_ip == NULL) {
345 if (packet_connection_is_on_socket()) {
346 canonical_host_ip =
347 get_peer_ipaddr(packet_get_connection_in());
348 if (canonical_host_ip == NULL)
349 cleanup_exit(255);
350 } else {
351 /* If not on socket, return UNKNOWN. */
352 canonical_host_ip = xstrdup("UNKNOWN");
353 }
354 }
355 return canonical_host_ip;
356}
357
358const char *
359get_remote_name_or_ip(u_int utmp_len, int use_dns)
360{
361 static const char *remote = "";
362 if (utmp_len > 0)
363 remote = get_canonical_hostname(use_dns);
364 if (utmp_len == 0 || strlen(remote) > utmp_len)
365 remote = get_remote_ipaddr();
366 return remote;
367}
368
369/* Returns the local/remote port for the socket. */ 153/* Returns the local/remote port for the socket. */
370 154
371int 155static int
372get_sock_port(int sock, int local) 156get_sock_port(int sock, int local)
373{ 157{
374 struct sockaddr_storage from; 158 struct sockaddr_storage from;
@@ -402,27 +186,11 @@ get_sock_port(int sock, int local)
402 /* Return port number. */ 186 /* Return port number. */
403 if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, 187 if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
404 strport, sizeof(strport), NI_NUMERICSERV)) != 0) 188 strport, sizeof(strport), NI_NUMERICSERV)) != 0)
405 fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", 189 fatal("%s: getnameinfo NI_NUMERICSERV failed: %s", __func__,
406 ssh_gai_strerror(r)); 190 ssh_gai_strerror(r));
407 return atoi(strport); 191 return atoi(strport);
408} 192}
409 193
410/* Returns remote/local port number for the current connection. */
411
412static int
413get_port(int local)
414{
415 /*
416 * If the connection is not a socket, return 65535. This is
417 * intentionally chosen to be an unprivileged port number.
418 */
419 if (!packet_connection_is_on_socket())
420 return 65535;
421
422 /* Get socket and return the port number. */
423 return get_sock_port(packet_get_connection_in(), local);
424}
425
426int 194int
427get_peer_port(int sock) 195get_peer_port(int sock)
428{ 196{
@@ -430,17 +198,7 @@ get_peer_port(int sock)
430} 198}
431 199
432int 200int
433get_remote_port(void) 201get_local_port(int sock)
434{
435 /* Cache to avoid getpeername() on a dead connection */
436 if (cached_port == -1)
437 cached_port = get_port(0);
438
439 return cached_port;
440}
441
442int
443get_local_port(void)
444{ 202{
445 return get_port(1); 203 return get_sock_port(sock, 1);
446} 204}