]>
Commit | Line | Data |
---|---|---|
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" | |
15 | RCSID("$OpenBSD: canohost.c,v 1.35 2002/11/26 02:38:54 stevesk Exp $"); | |
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 * | |
30 | get_remote_hostname(int socket, int verify_reverse_mapping) | |
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 | fromlen = sizeof(*from4); | |
63 | memcpy(&from4->sin_addr, &addr, sizeof(addr)); | |
64 | from4->sin_port = port; | |
65 | } | |
66 | } | |
67 | #endif | |
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 (from.ss_family == AF_INET) | |
76 | check_ip_options(socket, 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 | #if 0 | |
84 | log("Could not reverse map address %.100s.", ntop); | |
85 | #endif | |
86 | return xstrdup(ntop); | |
87 | } | |
88 | ||
89 | /* Got host name. */ | |
90 | name[sizeof(name) - 1] = '\0'; | |
91 | /* | |
92 | * Convert it to all lowercase (which is expected by the rest | |
93 | * of this software). | |
94 | */ | |
95 | for (i = 0; name[i]; i++) | |
96 | if (isupper(name[i])) | |
97 | name[i] = tolower(name[i]); | |
98 | ||
99 | if (!verify_reverse_mapping) | |
100 | return xstrdup(name); | |
101 | /* | |
102 | * Map it back to an IP address and check that the given | |
103 | * address actually is an address of this host. This is | |
104 | * necessary because anyone with access to a name server can | |
105 | * define arbitrary names for an IP address. Mapping from | |
106 | * name to IP address can be trusted better (but can still be | |
107 | * fooled if the intruder has access to the name server of | |
108 | * the domain). | |
109 | */ | |
110 | memset(&hints, 0, sizeof(hints)); | |
111 | hints.ai_family = from.ss_family; | |
112 | hints.ai_socktype = SOCK_STREAM; | |
113 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
114 | log("reverse mapping checking getaddrinfo for %.700s " | |
115 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); | |
116 | return xstrdup(ntop); | |
117 | } | |
118 | /* Look for the address from the list of addresses. */ | |
119 | for (ai = aitop; ai; ai = ai->ai_next) { | |
120 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
121 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
122 | (strcmp(ntop, ntop2) == 0)) | |
123 | break; | |
124 | } | |
125 | freeaddrinfo(aitop); | |
126 | /* If we reached the end of the list, the address was not there. */ | |
127 | if (!ai) { | |
128 | /* Address not found for the host name. */ | |
129 | log("Address %.100s maps to %.600s, but this does not " | |
130 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", | |
131 | ntop, name); | |
132 | return xstrdup(ntop); | |
133 | } | |
134 | return xstrdup(name); | |
135 | } | |
136 | ||
137 | /* | |
138 | * If IP options are supported, make sure there are none (log and | |
139 | * disconnect them if any are found). Basically we are worried about | |
140 | * source routing; it can be used to pretend you are somebody | |
141 | * (ip-address) you are not. That itself may be "almost acceptable" | |
142 | * under certain circumstances, but rhosts autentication is useless | |
143 | * if source routing is accepted. Notice also that if we just dropped | |
144 | * source routing here, the other side could use IP spoofing to do | |
145 | * rest of the interaction and could still bypass security. So we | |
146 | * exit here if we detect any IP options. | |
147 | */ | |
148 | /* IPv4 only */ | |
149 | static void | |
150 | check_ip_options(int socket, char *ipaddr) | |
151 | { | |
152 | u_char options[200]; | |
153 | char text[sizeof(options) * 3 + 1]; | |
154 | socklen_t option_size; | |
155 | int i, ipproto; | |
156 | struct protoent *ip; | |
157 | ||
158 | if ((ip = getprotobyname("ip")) != NULL) | |
159 | ipproto = ip->p_proto; | |
160 | else | |
161 | ipproto = IPPROTO_IP; | |
162 | option_size = sizeof(options); | |
163 | if (getsockopt(socket, ipproto, IP_OPTIONS, options, | |
164 | &option_size) >= 0 && option_size != 0) { | |
165 | text[0] = '\0'; | |
166 | for (i = 0; i < option_size; i++) | |
167 | snprintf(text + i*3, sizeof(text) - i*3, | |
168 | " %2.2x", options[i]); | |
169 | log("Connection from %.100s with IP options:%.800s", | |
170 | ipaddr, text); | |
171 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
172 | ipaddr, text); | |
173 | } | |
174 | } | |
175 | ||
176 | /* | |
177 | * Return the canonical name of the host in the other side of the current | |
178 | * connection. The host name is cached, so it is efficient to call this | |
179 | * several times. | |
180 | */ | |
181 | ||
182 | const char * | |
183 | get_canonical_hostname(int verify_reverse_mapping) | |
184 | { | |
185 | static char *canonical_host_name = NULL; | |
186 | static int verify_reverse_mapping_done = 0; | |
187 | ||
188 | /* Check if we have previously retrieved name with same option. */ | |
189 | if (canonical_host_name != NULL) { | |
190 | if (verify_reverse_mapping_done != verify_reverse_mapping) | |
191 | xfree(canonical_host_name); | |
192 | else | |
193 | return canonical_host_name; | |
194 | } | |
195 | ||
196 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ | |
197 | if (packet_connection_is_on_socket()) | |
198 | canonical_host_name = get_remote_hostname( | |
199 | packet_get_connection_in(), verify_reverse_mapping); | |
200 | else | |
201 | canonical_host_name = xstrdup("UNKNOWN"); | |
202 | ||
203 | verify_reverse_mapping_done = verify_reverse_mapping; | |
204 | return canonical_host_name; | |
205 | } | |
206 | ||
207 | /* | |
208 | * Returns the local/remote IP-address/hostname of socket as a string. | |
209 | * The returned string must be freed. | |
210 | */ | |
211 | static char * | |
212 | get_socket_address(int socket, int remote, int flags) | |
213 | { | |
214 | struct sockaddr_storage addr; | |
215 | socklen_t addrlen; | |
216 | char ntop[NI_MAXHOST]; | |
217 | ||
218 | /* Get IP address of client. */ | |
219 | addrlen = sizeof(addr); | |
220 | memset(&addr, 0, sizeof(addr)); | |
221 | ||
222 | if (remote) { | |
223 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
224 | < 0) | |
225 | return NULL; | |
226 | } else { | |
227 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
228 | < 0) | |
229 | return NULL; | |
230 | } | |
231 | ||
232 | /* Work around Linux IPv6 weirdness */ | |
233 | if (addr.ss_family == AF_INET6) | |
234 | addrlen = sizeof(struct sockaddr_in6); | |
235 | ||
236 | /* Get the address in ascii. */ | |
237 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
238 | NULL, 0, flags) != 0) { | |
239 | error("get_socket_address: getnameinfo %d failed", flags); | |
240 | return NULL; | |
241 | } | |
242 | return xstrdup(ntop); | |
243 | } | |
244 | ||
245 | char * | |
246 | get_peer_ipaddr(int socket) | |
247 | { | |
248 | char *p; | |
249 | ||
250 | if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL) | |
251 | return p; | |
252 | return xstrdup("UNKNOWN"); | |
253 | } | |
254 | ||
255 | char * | |
256 | get_local_ipaddr(int socket) | |
257 | { | |
258 | char *p; | |
259 | ||
260 | if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL) | |
261 | return p; | |
262 | return xstrdup("UNKNOWN"); | |
263 | } | |
264 | ||
265 | char * | |
266 | get_local_name(int socket) | |
267 | { | |
268 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
269 | } | |
270 | ||
271 | /* | |
272 | * Returns the IP-address of the remote host as a string. The returned | |
273 | * string must not be freed. | |
274 | */ | |
275 | ||
276 | const char * | |
277 | get_remote_ipaddr(void) | |
278 | { | |
279 | static char *canonical_host_ip = NULL; | |
280 | ||
281 | /* Check whether we have cached the ipaddr. */ | |
282 | if (canonical_host_ip == NULL) { | |
283 | if (packet_connection_is_on_socket()) { | |
284 | canonical_host_ip = | |
285 | get_peer_ipaddr(packet_get_connection_in()); | |
286 | if (canonical_host_ip == NULL) | |
287 | fatal_cleanup(); | |
288 | } else { | |
289 | /* If not on socket, return UNKNOWN. */ | |
290 | canonical_host_ip = xstrdup("UNKNOWN"); | |
291 | } | |
292 | } | |
293 | return canonical_host_ip; | |
294 | } | |
295 | ||
296 | const char * | |
297 | get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping) | |
298 | { | |
299 | static const char *remote = ""; | |
300 | if (utmp_len > 0) | |
301 | remote = get_canonical_hostname(verify_reverse_mapping); | |
302 | if (utmp_len == 0 || strlen(remote) > utmp_len) | |
303 | remote = get_remote_ipaddr(); | |
304 | return remote; | |
305 | } | |
306 | ||
307 | /* Returns the local/remote port for the socket. */ | |
308 | ||
309 | static int | |
310 | get_sock_port(int sock, int local) | |
311 | { | |
312 | struct sockaddr_storage from; | |
313 | socklen_t fromlen; | |
314 | char strport[NI_MAXSERV]; | |
315 | ||
316 | /* Get IP address of client. */ | |
317 | fromlen = sizeof(from); | |
318 | memset(&from, 0, sizeof(from)); | |
319 | if (local) { | |
320 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
321 | error("getsockname failed: %.100s", strerror(errno)); | |
322 | return 0; | |
323 | } | |
324 | } else { | |
325 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
326 | debug("getpeername failed: %.100s", strerror(errno)); | |
327 | fatal_cleanup(); | |
328 | } | |
329 | } | |
330 | ||
331 | /* Work around Linux IPv6 weirdness */ | |
332 | if (from.ss_family == AF_INET6) | |
333 | fromlen = sizeof(struct sockaddr_in6); | |
334 | ||
335 | /* Return port number. */ | |
336 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, | |
337 | strport, sizeof(strport), NI_NUMERICSERV) != 0) | |
338 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); | |
339 | return atoi(strport); | |
340 | } | |
341 | ||
342 | /* Returns remote/local port number for the current connection. */ | |
343 | ||
344 | static int | |
345 | get_port(int local) | |
346 | { | |
347 | /* | |
348 | * If the connection is not a socket, return 65535. This is | |
349 | * intentionally chosen to be an unprivileged port number. | |
350 | */ | |
351 | if (!packet_connection_is_on_socket()) | |
352 | return 65535; | |
353 | ||
354 | /* Get socket and return the port number. */ | |
355 | return get_sock_port(packet_get_connection_in(), local); | |
356 | } | |
357 | ||
358 | int | |
359 | get_peer_port(int sock) | |
360 | { | |
361 | return get_sock_port(sock, 0); | |
362 | } | |
363 | ||
364 | int | |
365 | get_remote_port(void) | |
366 | { | |
367 | return get_port(0); | |
368 | } | |
369 | ||
370 | int | |
371 | get_local_port(void) | |
372 | { | |
373 | return get_port(1); | |
374 | } |