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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" | |
649bb60b | 15 | RCSID("$OpenBSD: canohost.c,v 1.35 2002/11/26 02:38:54 stevesk 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 * |
bf4c5edc | 30 | get_remote_hostname(int socket, int verify_reverse_mapping) |
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 | |
aa686c54 | 75 | if (from.ss_family == AF_INET) |
76 | check_ip_options(socket, ntop); | |
77 | ||
3a83b819 | 78 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 79 | /* Map the IP address to a host name. */ |
80 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 81 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 82 | /* Host name not found. Use ip address. */ |
59c825e1 | 83 | #if 0 |
bbe88b6d | 84 | logit("Could not reverse map address %.100s.", ntop); |
59c825e1 | 85 | #endif |
61e96248 | 86 | return xstrdup(ntop); |
8efc0c15 | 87 | } |
5260325f | 88 | |
61e96248 | 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]); | |
5260325f | 98 | |
bf4c5edc | 99 | if (!verify_reverse_mapping) |
61e96248 | 100 | return xstrdup(name); |
aa3378df | 101 | /* |
61e96248 | 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). | |
aa3378df | 109 | */ |
61e96248 | 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) { | |
bbe88b6d | 114 | logit("reverse mapping checking getaddrinfo for %.700s " |
61e96248 | 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. */ | |
bbe88b6d | 129 | logit("Address %.100s maps to %.600s, but this does not " |
61e96248 | 130 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
131 | ntop, name); | |
132 | return xstrdup(ntop); | |
8efc0c15 | 133 | } |
5260325f | 134 | return xstrdup(name); |
8efc0c15 | 135 | } |
136 | ||
61e96248 | 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 */ | |
396c147e | 149 | static void |
61e96248 | 150 | check_ip_options(int socket, char *ipaddr) |
151 | { | |
e6fa162e | 152 | u_char options[200]; |
153 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 154 | socklen_t option_size; |
e6fa162e | 155 | int i, ipproto; |
61e96248 | 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); | |
db518d9b | 163 | if (getsockopt(socket, ipproto, IP_OPTIONS, options, |
61e96248 | 164 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 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]); | |
bbe88b6d | 169 | logit("Connection from %.100s with IP options:%.800s", |
61e96248 | 170 | ipaddr, text); |
171 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
172 | ipaddr, text); | |
173 | } | |
174 | } | |
175 | ||
aa3378df | 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 | */ | |
8efc0c15 | 181 | |
5260325f | 182 | const char * |
bf4c5edc | 183 | get_canonical_hostname(int verify_reverse_mapping) |
8efc0c15 | 184 | { |
48e671d5 | 185 | static char *canonical_host_name = NULL; |
bf4c5edc | 186 | static int verify_reverse_mapping_done = 0; |
48e671d5 | 187 | |
61e96248 | 188 | /* Check if we have previously retrieved name with same option. */ |
189 | if (canonical_host_name != NULL) { | |
bf4c5edc | 190 | if (verify_reverse_mapping_done != verify_reverse_mapping) |
61e96248 | 191 | xfree(canonical_host_name); |
192 | else | |
193 | return canonical_host_name; | |
194 | } | |
8efc0c15 | 195 | |
5260325f | 196 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 197 | if (packet_connection_is_on_socket()) |
61e96248 | 198 | canonical_host_name = get_remote_hostname( |
bf4c5edc | 199 | packet_get_connection_in(), verify_reverse_mapping); |
5260325f | 200 | else |
201 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 202 | |
bf4c5edc | 203 | verify_reverse_mapping_done = verify_reverse_mapping; |
5260325f | 204 | return canonical_host_name; |
8efc0c15 | 205 | } |
206 | ||
aa3378df | 207 | /* |
649bb60b | 208 | * Returns the local/remote IP-address/hostname of socket as a string. |
209 | * The returned string must be freed. | |
aa3378df | 210 | */ |
396c147e | 211 | static char * |
8002af61 | 212 | get_socket_address(int socket, int remote, int flags) |
8efc0c15 | 213 | { |
8002af61 | 214 | struct sockaddr_storage addr; |
215 | socklen_t addrlen; | |
48e671d5 | 216 | char ntop[NI_MAXHOST]; |
5260325f | 217 | |
5260325f | 218 | /* Get IP address of client. */ |
8002af61 | 219 | addrlen = sizeof(addr); |
220 | memset(&addr, 0, sizeof(addr)); | |
221 | ||
222 | if (remote) { | |
223 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
99443922 | 224 | < 0) |
8002af61 | 225 | return NULL; |
8002af61 | 226 | } else { |
227 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
99443922 | 228 | < 0) |
8002af61 | 229 | return NULL; |
5260325f | 230 | } |
e7ccd20d | 231 | |
232 | /* Work around Linux IPv6 weirdness */ | |
233 | if (addr.ss_family == AF_INET6) | |
234 | addrlen = sizeof(struct sockaddr_in6); | |
235 | ||
8002af61 | 236 | /* Get the address in ascii. */ |
237 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
184eed6a | 238 | NULL, 0, flags) != 0) { |
649bb60b | 239 | error("get_socket_address: getnameinfo %d failed", flags); |
865ac82e | 240 | return NULL; |
241 | } | |
242 | return xstrdup(ntop); | |
243 | } | |
48e671d5 | 244 | |
8002af61 | 245 | char * |
246 | get_peer_ipaddr(int socket) | |
247 | { | |
99443922 | 248 | char *p; |
249 | ||
250 | if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL) | |
251 | return p; | |
252 | return xstrdup("UNKNOWN"); | |
8002af61 | 253 | } |
254 | ||
255 | char * | |
256 | get_local_ipaddr(int socket) | |
257 | { | |
99443922 | 258 | char *p; |
259 | ||
260 | if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL) | |
261 | return p; | |
262 | return xstrdup("UNKNOWN"); | |
8002af61 | 263 | } |
264 | ||
265 | char * | |
266 | get_local_name(int socket) | |
267 | { | |
268 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
269 | } | |
270 | ||
865ac82e | 271 | /* |
272 | * Returns the IP-address of the remote host as a string. The returned | |
273 | * string must not be freed. | |
274 | */ | |
5260325f | 275 | |
865ac82e | 276 | const char * |
d5bb9418 | 277 | get_remote_ipaddr(void) |
865ac82e | 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 | } | |
5260325f | 293 | return canonical_host_ip; |
8efc0c15 | 294 | } |
295 | ||
46e3af7f | 296 | const char * |
bf4c5edc | 297 | get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping) |
46e3af7f | 298 | { |
299 | static const char *remote = ""; | |
300 | if (utmp_len > 0) | |
bf4c5edc | 301 | remote = get_canonical_hostname(verify_reverse_mapping); |
46e3af7f | 302 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
303 | remote = get_remote_ipaddr(); | |
304 | return remote; | |
305 | } | |
306 | ||
48e671d5 | 307 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 308 | |
396c147e | 309 | static int |
48e671d5 | 310 | get_sock_port(int sock, int local) |
8efc0c15 | 311 | { |
48e671d5 | 312 | struct sockaddr_storage from; |
313 | socklen_t fromlen; | |
314 | char strport[NI_MAXSERV]; | |
5260325f | 315 | |
316 | /* Get IP address of client. */ | |
317 | fromlen = sizeof(from); | |
318 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 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 { | |
649bb60b | 325 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 326 | debug("getpeername failed: %.100s", strerror(errno)); |
327 | fatal_cleanup(); | |
328 | } | |
5260325f | 329 | } |
e7ccd20d | 330 | |
331 | /* Work around Linux IPv6 weirdness */ | |
332 | if (from.ss_family == AF_INET6) | |
333 | fromlen = sizeof(struct sockaddr_in6); | |
334 | ||
5260325f | 335 | /* Return port number. */ |
48e671d5 | 336 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
184eed6a | 337 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
48e671d5 | 338 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
339 | return atoi(strport); | |
8efc0c15 | 340 | } |
341 | ||
48e671d5 | 342 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 343 | |
396c147e | 344 | static int |
48e671d5 | 345 | get_port(int local) |
8efc0c15 | 346 | { |
aa3378df | 347 | /* |
348 | * If the connection is not a socket, return 65535. This is | |
349 | * intentionally chosen to be an unprivileged port number. | |
350 | */ | |
48e671d5 | 351 | if (!packet_connection_is_on_socket()) |
5260325f | 352 | return 65535; |
8efc0c15 | 353 | |
48e671d5 | 354 | /* Get socket and return the port number. */ |
355 | return get_sock_port(packet_get_connection_in(), local); | |
356 | } | |
357 | ||
6ae2364d | 358 | int |
48e671d5 | 359 | get_peer_port(int sock) |
360 | { | |
361 | return get_sock_port(sock, 0); | |
362 | } | |
8efc0c15 | 363 | |
6ae2364d | 364 | int |
d5bb9418 | 365 | get_remote_port(void) |
48e671d5 | 366 | { |
367 | return get_port(0); | |
368 | } | |
369 | ||
370 | int | |
d5bb9418 | 371 | get_local_port(void) |
48e671d5 | 372 | { |
373 | return get_port(1); | |
8efc0c15 | 374 | } |