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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" | |
665a873d | 15 | RCSID("$OpenBSD: canohost.c,v 1.44 2005/06/17 02:44:32 djm 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 * | |
c9f39d2c | 30 | get_remote_hostname(int sock, int use_dns) |
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)); | |
c9f39d2c | 41 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 42 | debug("getpeername failed: %.100s", strerror(errno)); |
cdd66111 | 43 | cleanup_exit(255); |
3c0ef626 | 44 | } |
cdd66111 | 45 | |
99be0775 | 46 | if (from.ss_family == AF_INET) |
c9f39d2c | 47 | check_ip_options(sock, ntop); |
99be0775 | 48 | |
cdd66111 | 49 | ipv64_normalise_mapped(&from, &fromlen); |
50 | ||
6a9b3198 | 51 | if (from.ss_family == AF_INET6) |
52 | fromlen = sizeof(struct sockaddr_in6); | |
3c0ef626 | 53 | |
54 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), | |
e9a17296 | 55 | NULL, 0, NI_NUMERICHOST) != 0) |
3c0ef626 | 56 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
57 | ||
0fff78ff | 58 | if (!use_dns) |
59 | return xstrdup(ntop); | |
60 | ||
3c0ef626 | 61 | debug3("Trying to reverse map address %.100s.", ntop); |
62 | /* Map the IP address to a host name. */ | |
63 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
e9a17296 | 64 | NULL, 0, NI_NAMEREQD) != 0) { |
3c0ef626 | 65 | /* Host name not found. Use ip address. */ |
3c0ef626 | 66 | return xstrdup(ntop); |
67 | } | |
68 | ||
0fff78ff | 69 | /* |
70 | * if reverse lookup result looks like a numeric hostname, | |
71 | * someone is trying to trick us by PTR record like following: | |
72 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
73 | */ | |
74 | memset(&hints, 0, sizeof(hints)); | |
75 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
76 | hints.ai_flags = AI_NUMERICHOST; | |
77 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { | |
78 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
79 | name, ntop); | |
80 | freeaddrinfo(ai); | |
81 | return xstrdup(ntop); | |
82 | } | |
83 | ||
3c0ef626 | 84 | /* |
85 | * Convert it to all lowercase (which is expected by the rest | |
86 | * of this software). | |
87 | */ | |
88 | for (i = 0; name[i]; i++) | |
89 | if (isupper(name[i])) | |
90 | name[i] = tolower(name[i]); | |
3c0ef626 | 91 | /* |
92 | * Map it back to an IP address and check that the given | |
93 | * address actually is an address of this host. This is | |
94 | * necessary because anyone with access to a name server can | |
95 | * define arbitrary names for an IP address. Mapping from | |
96 | * name to IP address can be trusted better (but can still be | |
97 | * fooled if the intruder has access to the name server of | |
98 | * the domain). | |
99 | */ | |
100 | memset(&hints, 0, sizeof(hints)); | |
101 | hints.ai_family = from.ss_family; | |
102 | hints.ai_socktype = SOCK_STREAM; | |
103 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
0fff78ff | 104 | logit("reverse mapping checking getaddrinfo for %.700s " |
3c0ef626 | 105 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); |
106 | return xstrdup(ntop); | |
107 | } | |
108 | /* Look for the address from the list of addresses. */ | |
109 | for (ai = aitop; ai; ai = ai->ai_next) { | |
110 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
111 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
112 | (strcmp(ntop, ntop2) == 0)) | |
113 | break; | |
114 | } | |
115 | freeaddrinfo(aitop); | |
116 | /* If we reached the end of the list, the address was not there. */ | |
117 | if (!ai) { | |
118 | /* Address not found for the host name. */ | |
0fff78ff | 119 | logit("Address %.100s maps to %.600s, but this does not " |
3c0ef626 | 120 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
121 | ntop, name); | |
122 | return xstrdup(ntop); | |
123 | } | |
124 | return xstrdup(name); | |
125 | } | |
126 | ||
127 | /* | |
128 | * If IP options are supported, make sure there are none (log and | |
129 | * disconnect them if any are found). Basically we are worried about | |
130 | * source routing; it can be used to pretend you are somebody | |
131 | * (ip-address) you are not. That itself may be "almost acceptable" | |
132 | * under certain circumstances, but rhosts autentication is useless | |
133 | * if source routing is accepted. Notice also that if we just dropped | |
134 | * source routing here, the other side could use IP spoofing to do | |
135 | * rest of the interaction and could still bypass security. So we | |
136 | * exit here if we detect any IP options. | |
137 | */ | |
138 | /* IPv4 only */ | |
139 | static void | |
c9f39d2c | 140 | check_ip_options(int sock, char *ipaddr) |
3c0ef626 | 141 | { |
0fff78ff | 142 | #ifdef IP_OPTIONS |
3c0ef626 | 143 | u_char options[200]; |
144 | char text[sizeof(options) * 3 + 1]; | |
145 | socklen_t option_size; | |
665a873d | 146 | u_int i; |
147 | int ipproto; | |
3c0ef626 | 148 | struct protoent *ip; |
149 | ||
150 | if ((ip = getprotobyname("ip")) != NULL) | |
151 | ipproto = ip->p_proto; | |
152 | else | |
153 | ipproto = IPPROTO_IP; | |
154 | option_size = sizeof(options); | |
c9f39d2c | 155 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
3c0ef626 | 156 | &option_size) >= 0 && option_size != 0) { |
157 | text[0] = '\0'; | |
158 | for (i = 0; i < option_size; i++) | |
159 | snprintf(text + i*3, sizeof(text) - i*3, | |
160 | " %2.2x", options[i]); | |
0fff78ff | 161 | logit("Connection from %.100s with IP options:%.800s", |
3c0ef626 | 162 | ipaddr, text); |
163 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
164 | ipaddr, text); | |
165 | } | |
0fff78ff | 166 | #endif /* IP_OPTIONS */ |
3c0ef626 | 167 | } |
168 | ||
996d5e62 | 169 | void |
cdd66111 | 170 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
171 | { | |
172 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
173 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
174 | struct in_addr inaddr; | |
175 | u_int16_t port; | |
176 | ||
665a873d | 177 | if (addr->ss_family != AF_INET6 || |
cdd66111 | 178 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) |
179 | return; | |
180 | ||
181 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
182 | ||
183 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
184 | port = a6->sin6_port; | |
185 | ||
186 | memset(addr, 0, sizeof(*a4)); | |
187 | ||
188 | a4->sin_family = AF_INET; | |
189 | *len = sizeof(*a4); | |
190 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
191 | a4->sin_port = port; | |
192 | } | |
193 | ||
3c0ef626 | 194 | /* |
195 | * Return the canonical name of the host in the other side of the current | |
196 | * connection. The host name is cached, so it is efficient to call this | |
197 | * several times. | |
198 | */ | |
199 | ||
200 | const char * | |
0fff78ff | 201 | get_canonical_hostname(int use_dns) |
3c0ef626 | 202 | { |
203 | static char *canonical_host_name = NULL; | |
0fff78ff | 204 | static int use_dns_done = 0; |
3c0ef626 | 205 | |
206 | /* Check if we have previously retrieved name with same option. */ | |
207 | if (canonical_host_name != NULL) { | |
0fff78ff | 208 | if (use_dns_done != use_dns) |
3c0ef626 | 209 | xfree(canonical_host_name); |
210 | else | |
211 | return canonical_host_name; | |
212 | } | |
213 | ||
214 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ | |
215 | if (packet_connection_is_on_socket()) | |
216 | canonical_host_name = get_remote_hostname( | |
0fff78ff | 217 | packet_get_connection_in(), use_dns); |
3c0ef626 | 218 | else |
219 | canonical_host_name = xstrdup("UNKNOWN"); | |
220 | ||
0fff78ff | 221 | use_dns_done = use_dns; |
3c0ef626 | 222 | return canonical_host_name; |
223 | } | |
224 | ||
225 | /* | |
6a9b3198 | 226 | * Returns the local/remote IP-address/hostname of socket as a string. |
227 | * The returned string must be freed. | |
3c0ef626 | 228 | */ |
229 | static char * | |
c9f39d2c | 230 | get_socket_address(int sock, int remote, int flags) |
3c0ef626 | 231 | { |
232 | struct sockaddr_storage addr; | |
233 | socklen_t addrlen; | |
234 | char ntop[NI_MAXHOST]; | |
996d5e62 | 235 | int r; |
3c0ef626 | 236 | |
237 | /* Get IP address of client. */ | |
238 | addrlen = sizeof(addr); | |
239 | memset(&addr, 0, sizeof(addr)); | |
240 | ||
241 | if (remote) { | |
c9f39d2c | 242 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
41b2f314 | 243 | < 0) |
3c0ef626 | 244 | return NULL; |
3c0ef626 | 245 | } else { |
c9f39d2c | 246 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
41b2f314 | 247 | < 0) |
3c0ef626 | 248 | return NULL; |
3c0ef626 | 249 | } |
6a9b3198 | 250 | |
251 | /* Work around Linux IPv6 weirdness */ | |
252 | if (addr.ss_family == AF_INET6) | |
253 | addrlen = sizeof(struct sockaddr_in6); | |
254 | ||
dec6d9fe | 255 | ipv64_normalise_mapped(&addr, &addrlen); |
256 | ||
3c0ef626 | 257 | /* Get the address in ascii. */ |
996d5e62 | 258 | if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, |
259 | sizeof(ntop), NULL, 0, flags)) != 0) { | |
260 | error("get_socket_address: getnameinfo %d failed: %s", flags, | |
261 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
3c0ef626 | 262 | return NULL; |
263 | } | |
264 | return xstrdup(ntop); | |
265 | } | |
266 | ||
267 | char * | |
c9f39d2c | 268 | get_peer_ipaddr(int sock) |
3c0ef626 | 269 | { |
41b2f314 | 270 | char *p; |
271 | ||
c9f39d2c | 272 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
41b2f314 | 273 | return p; |
274 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 275 | } |
276 | ||
277 | char * | |
c9f39d2c | 278 | get_local_ipaddr(int sock) |
3c0ef626 | 279 | { |
41b2f314 | 280 | char *p; |
281 | ||
c9f39d2c | 282 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
41b2f314 | 283 | return p; |
284 | return xstrdup("UNKNOWN"); | |
3c0ef626 | 285 | } |
286 | ||
287 | char * | |
c9f39d2c | 288 | get_local_name(int sock) |
3c0ef626 | 289 | { |
c9f39d2c | 290 | return get_socket_address(sock, 0, NI_NAMEREQD); |
3c0ef626 | 291 | } |
292 | ||
293 | /* | |
294 | * Returns the IP-address of the remote host as a string. The returned | |
295 | * string must not be freed. | |
296 | */ | |
297 | ||
298 | const char * | |
e9a17296 | 299 | get_remote_ipaddr(void) |
3c0ef626 | 300 | { |
301 | static char *canonical_host_ip = NULL; | |
302 | ||
303 | /* Check whether we have cached the ipaddr. */ | |
304 | if (canonical_host_ip == NULL) { | |
305 | if (packet_connection_is_on_socket()) { | |
306 | canonical_host_ip = | |
307 | get_peer_ipaddr(packet_get_connection_in()); | |
308 | if (canonical_host_ip == NULL) | |
cdd66111 | 309 | cleanup_exit(255); |
3c0ef626 | 310 | } else { |
311 | /* If not on socket, return UNKNOWN. */ | |
312 | canonical_host_ip = xstrdup("UNKNOWN"); | |
313 | } | |
314 | } | |
315 | return canonical_host_ip; | |
316 | } | |
317 | ||
318 | const char * | |
0fff78ff | 319 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
3c0ef626 | 320 | { |
321 | static const char *remote = ""; | |
322 | if (utmp_len > 0) | |
0fff78ff | 323 | remote = get_canonical_hostname(use_dns); |
3c0ef626 | 324 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
325 | remote = get_remote_ipaddr(); | |
326 | return remote; | |
327 | } | |
328 | ||
329 | /* Returns the local/remote port for the socket. */ | |
330 | ||
331 | static int | |
332 | get_sock_port(int sock, int local) | |
333 | { | |
334 | struct sockaddr_storage from; | |
335 | socklen_t fromlen; | |
336 | char strport[NI_MAXSERV]; | |
996d5e62 | 337 | int r; |
3c0ef626 | 338 | |
339 | /* Get IP address of client. */ | |
340 | fromlen = sizeof(from); | |
341 | memset(&from, 0, sizeof(from)); | |
342 | if (local) { | |
343 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
344 | error("getsockname failed: %.100s", strerror(errno)); | |
345 | return 0; | |
346 | } | |
347 | } else { | |
6a9b3198 | 348 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
3c0ef626 | 349 | debug("getpeername failed: %.100s", strerror(errno)); |
665a873d | 350 | return -1; |
3c0ef626 | 351 | } |
352 | } | |
6a9b3198 | 353 | |
354 | /* Work around Linux IPv6 weirdness */ | |
355 | if (from.ss_family == AF_INET6) | |
356 | fromlen = sizeof(struct sockaddr_in6); | |
357 | ||
3c0ef626 | 358 | /* Return port number. */ |
996d5e62 | 359 | if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
360 | strport, sizeof(strport), NI_NUMERICSERV)) != 0) | |
361 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", | |
362 | r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r)); | |
3c0ef626 | 363 | return atoi(strport); |
364 | } | |
365 | ||
366 | /* Returns remote/local port number for the current connection. */ | |
367 | ||
368 | static int | |
369 | get_port(int local) | |
370 | { | |
371 | /* | |
372 | * If the connection is not a socket, return 65535. This is | |
373 | * intentionally chosen to be an unprivileged port number. | |
374 | */ | |
375 | if (!packet_connection_is_on_socket()) | |
376 | return 65535; | |
377 | ||
378 | /* Get socket and return the port number. */ | |
379 | return get_sock_port(packet_get_connection_in(), local); | |
380 | } | |
381 | ||
382 | int | |
383 | get_peer_port(int sock) | |
384 | { | |
385 | return get_sock_port(sock, 0); | |
386 | } | |
387 | ||
388 | int | |
e9a17296 | 389 | get_remote_port(void) |
3c0ef626 | 390 | { |
c9f39d2c | 391 | static int port = -1; |
392 | ||
393 | /* Cache to avoid getpeername() on a dead connection */ | |
394 | if (port == -1) | |
395 | port = get_port(0); | |
396 | ||
397 | return port; | |
3c0ef626 | 398 | } |
399 | ||
400 | int | |
e9a17296 | 401 | get_local_port(void) |
3c0ef626 | 402 | { |
403 | return get_port(1); | |
404 | } |