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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
4 | * All rights reserved | |
5260325f | 5 | * Functions for returning the canonical host name of the remote site. |
6ae2364d | 6 | * |
bcbf86ec | 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". | |
5260325f | 12 | */ |
8efc0c15 | 13 | |
14 | #include "includes.h" | |
c5a7d788 | 15 | RCSID("$OpenBSD: canohost.c,v 1.37 2003/06/02 09:17:34 markus Exp $"); |
8efc0c15 | 16 | |
17 | #include "packet.h" | |
18 | #include "xmalloc.h" | |
42f11eb2 | 19 | #include "log.h" |
5ca51e19 | 20 | #include "canohost.h" |
8efc0c15 | 21 | |
396c147e | 22 | static void check_ip_options(int, char *); |
61e96248 | 23 | |
aa3378df | 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 | */ | |
8efc0c15 | 28 | |
396c147e | 29 | static char * |
c5a7d788 | 30 | get_remote_hostname(int socket, int use_dns) |
8efc0c15 | 31 | { |
48e671d5 | 32 | struct sockaddr_storage from; |
33 | int i; | |
34 | socklen_t fromlen; | |
35 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 36 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 37 | |
38 | /* Get IP address of client. */ | |
39 | fromlen = sizeof(from); | |
40 | memset(&from, 0, sizeof(from)); | |
649bb60b | 41 | if (getpeername(socket, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 42 | debug("getpeername failed: %.100s", strerror(errno)); |
43 | fatal_cleanup(); | |
44 | } | |
80faa19f | 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)); | |
2b87da3b | 60 | |
80faa19f | 61 | from4->sin_family = AF_INET; |
e7ccd20d | 62 | fromlen = sizeof(*from4); |
80faa19f | 63 | memcpy(&from4->sin_addr, &addr, sizeof(addr)); |
64 | from4->sin_port = port; | |
65 | } | |
66 | } | |
67 | #endif | |
e7ccd20d | 68 | if (from.ss_family == AF_INET6) |
69 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 70 | |
48e671d5 | 71 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 72 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 73 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 74 | |
c5a7d788 | 75 | if (!use_dns) |
76 | return xstrdup(ntop); | |
77 | ||
aa686c54 | 78 | if (from.ss_family == AF_INET) |
79 | check_ip_options(socket, ntop); | |
80 | ||
3a83b819 | 81 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 82 | /* Map the IP address to a host name. */ |
83 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 84 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 85 | /* Host name not found. Use ip address. */ |
61e96248 | 86 | return xstrdup(ntop); |
8efc0c15 | 87 | } |
5260325f | 88 | |
c5a7d788 | 89 | /* |
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*/ | |
96 | hints.ai_flags = AI_NUMERICHOST; | |
97 | 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 | ||
61e96248 | 104 | /* |
105 | * Convert it to all lowercase (which is expected by the rest | |
106 | * of this software). | |
107 | */ | |
108 | for (i = 0; name[i]; i++) | |
109 | if (isupper(name[i])) | |
110 | name[i] = tolower(name[i]); | |
aa3378df | 111 | /* |
61e96248 | 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). | |
aa3378df | 119 | */ |
61e96248 | 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) { | |
bbe88b6d | 124 | logit("reverse mapping checking getaddrinfo for %.700s " |
61e96248 | 125 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); |
126 | return xstrdup(ntop); | |
127 | } | |
128 | /* 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. */ | |
bbe88b6d | 139 | logit("Address %.100s maps to %.600s, but this does not " |
61e96248 | 140 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
141 | ntop, name); | |
142 | return xstrdup(ntop); | |
8efc0c15 | 143 | } |
5260325f | 144 | return xstrdup(name); |
8efc0c15 | 145 | } |
146 | ||
61e96248 | 147 | /* |
148 | * 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 */ | |
396c147e | 159 | static void |
61e96248 | 160 | check_ip_options(int socket, char *ipaddr) |
161 | { | |
e6fa162e | 162 | u_char options[200]; |
163 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 164 | socklen_t option_size; |
e6fa162e | 165 | int i, ipproto; |
61e96248 | 166 | struct protoent *ip; |
167 | ||
168 | if ((ip = getprotobyname("ip")) != NULL) | |
169 | ipproto = ip->p_proto; | |
170 | else | |
171 | ipproto = IPPROTO_IP; | |
172 | option_size = sizeof(options); | |
db518d9b | 173 | if (getsockopt(socket, ipproto, IP_OPTIONS, options, |
61e96248 | 174 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 175 | text[0] = '\0'; |
176 | for (i = 0; i < option_size; i++) | |
177 | snprintf(text + i*3, sizeof(text) - i*3, | |
178 | " %2.2x", options[i]); | |
bbe88b6d | 179 | logit("Connection from %.100s with IP options:%.800s", |
61e96248 | 180 | ipaddr, text); |
181 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
182 | ipaddr, text); | |
183 | } | |
184 | } | |
185 | ||
aa3378df | 186 | /* |
187 | * Return the canonical name of the host in the other side of the current | |
188 | * connection. The host name is cached, so it is efficient to call this | |
189 | * several times. | |
190 | */ | |
8efc0c15 | 191 | |
5260325f | 192 | const char * |
c5a7d788 | 193 | get_canonical_hostname(int use_dns) |
8efc0c15 | 194 | { |
48e671d5 | 195 | static char *canonical_host_name = NULL; |
c5a7d788 | 196 | static int use_dns_done = 0; |
48e671d5 | 197 | |
61e96248 | 198 | /* Check if we have previously retrieved name with same option. */ |
199 | if (canonical_host_name != NULL) { | |
c5a7d788 | 200 | if (use_dns_done != use_dns) |
61e96248 | 201 | xfree(canonical_host_name); |
202 | else | |
203 | return canonical_host_name; | |
204 | } | |
8efc0c15 | 205 | |
5260325f | 206 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 207 | if (packet_connection_is_on_socket()) |
61e96248 | 208 | canonical_host_name = get_remote_hostname( |
c5a7d788 | 209 | packet_get_connection_in(), use_dns); |
5260325f | 210 | else |
211 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 212 | |
c5a7d788 | 213 | use_dns_done = use_dns; |
5260325f | 214 | return canonical_host_name; |
8efc0c15 | 215 | } |
216 | ||
aa3378df | 217 | /* |
649bb60b | 218 | * Returns the local/remote IP-address/hostname of socket as a string. |
219 | * The returned string must be freed. | |
aa3378df | 220 | */ |
396c147e | 221 | static char * |
8002af61 | 222 | get_socket_address(int socket, int remote, int flags) |
8efc0c15 | 223 | { |
8002af61 | 224 | struct sockaddr_storage addr; |
225 | socklen_t addrlen; | |
48e671d5 | 226 | char ntop[NI_MAXHOST]; |
5260325f | 227 | |
5260325f | 228 | /* Get IP address of client. */ |
8002af61 | 229 | addrlen = sizeof(addr); |
230 | memset(&addr, 0, sizeof(addr)); | |
231 | ||
232 | if (remote) { | |
233 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
99443922 | 234 | < 0) |
8002af61 | 235 | return NULL; |
8002af61 | 236 | } else { |
237 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
99443922 | 238 | < 0) |
8002af61 | 239 | return NULL; |
5260325f | 240 | } |
e7ccd20d | 241 | |
242 | /* Work around Linux IPv6 weirdness */ | |
243 | if (addr.ss_family == AF_INET6) | |
244 | addrlen = sizeof(struct sockaddr_in6); | |
245 | ||
8002af61 | 246 | /* Get the address in ascii. */ |
247 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
184eed6a | 248 | NULL, 0, flags) != 0) { |
649bb60b | 249 | error("get_socket_address: getnameinfo %d failed", flags); |
865ac82e | 250 | return NULL; |
251 | } | |
252 | return xstrdup(ntop); | |
253 | } | |
48e671d5 | 254 | |
8002af61 | 255 | char * |
256 | get_peer_ipaddr(int socket) | |
257 | { | |
99443922 | 258 | char *p; |
259 | ||
260 | if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL) | |
261 | return p; | |
262 | return xstrdup("UNKNOWN"); | |
8002af61 | 263 | } |
264 | ||
265 | char * | |
266 | get_local_ipaddr(int socket) | |
267 | { | |
99443922 | 268 | char *p; |
269 | ||
270 | if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL) | |
271 | return p; | |
272 | return xstrdup("UNKNOWN"); | |
8002af61 | 273 | } |
274 | ||
275 | char * | |
276 | get_local_name(int socket) | |
277 | { | |
278 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
279 | } | |
280 | ||
865ac82e | 281 | /* |
282 | * Returns the IP-address of the remote host as a string. The returned | |
283 | * string must not be freed. | |
284 | */ | |
5260325f | 285 | |
865ac82e | 286 | const char * |
d5bb9418 | 287 | get_remote_ipaddr(void) |
865ac82e | 288 | { |
289 | static char *canonical_host_ip = NULL; | |
290 | ||
291 | /* Check whether we have cached the ipaddr. */ | |
292 | if (canonical_host_ip == NULL) { | |
293 | if (packet_connection_is_on_socket()) { | |
294 | canonical_host_ip = | |
295 | get_peer_ipaddr(packet_get_connection_in()); | |
296 | if (canonical_host_ip == NULL) | |
297 | fatal_cleanup(); | |
298 | } else { | |
299 | /* If not on socket, return UNKNOWN. */ | |
300 | canonical_host_ip = xstrdup("UNKNOWN"); | |
301 | } | |
302 | } | |
5260325f | 303 | return canonical_host_ip; |
8efc0c15 | 304 | } |
305 | ||
46e3af7f | 306 | const char * |
c5a7d788 | 307 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 308 | { |
309 | static const char *remote = ""; | |
310 | if (utmp_len > 0) | |
c5a7d788 | 311 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 312 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
313 | remote = get_remote_ipaddr(); | |
314 | return remote; | |
315 | } | |
316 | ||
48e671d5 | 317 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 318 | |
396c147e | 319 | static int |
48e671d5 | 320 | get_sock_port(int sock, int local) |
8efc0c15 | 321 | { |
48e671d5 | 322 | struct sockaddr_storage from; |
323 | socklen_t fromlen; | |
324 | char strport[NI_MAXSERV]; | |
5260325f | 325 | |
326 | /* Get IP address of client. */ | |
327 | fromlen = sizeof(from); | |
328 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 329 | if (local) { |
330 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
331 | error("getsockname failed: %.100s", strerror(errno)); | |
332 | return 0; | |
333 | } | |
334 | } else { | |
649bb60b | 335 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 336 | debug("getpeername failed: %.100s", strerror(errno)); |
337 | fatal_cleanup(); | |
338 | } | |
5260325f | 339 | } |
e7ccd20d | 340 | |
341 | /* Work around Linux IPv6 weirdness */ | |
342 | if (from.ss_family == AF_INET6) | |
343 | fromlen = sizeof(struct sockaddr_in6); | |
344 | ||
5260325f | 345 | /* Return port number. */ |
48e671d5 | 346 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
184eed6a | 347 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
48e671d5 | 348 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
349 | return atoi(strport); | |
8efc0c15 | 350 | } |
351 | ||
48e671d5 | 352 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 353 | |
396c147e | 354 | static int |
48e671d5 | 355 | get_port(int local) |
8efc0c15 | 356 | { |
aa3378df | 357 | /* |
358 | * If the connection is not a socket, return 65535. This is | |
359 | * intentionally chosen to be an unprivileged port number. | |
360 | */ | |
48e671d5 | 361 | if (!packet_connection_is_on_socket()) |
5260325f | 362 | return 65535; |
8efc0c15 | 363 | |
48e671d5 | 364 | /* Get socket and return the port number. */ |
365 | return get_sock_port(packet_get_connection_in(), local); | |
366 | } | |
367 | ||
6ae2364d | 368 | int |
48e671d5 | 369 | get_peer_port(int sock) |
370 | { | |
371 | return get_sock_port(sock, 0); | |
372 | } | |
8efc0c15 | 373 | |
6ae2364d | 374 | int |
d5bb9418 | 375 | get_remote_port(void) |
48e671d5 | 376 | { |
377 | return get_port(0); | |
378 | } | |
379 | ||
380 | int | |
d5bb9418 | 381 | get_local_port(void) |
48e671d5 | 382 | { |
383 | return get_port(1); | |
8efc0c15 | 384 | } |