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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" | |
13f2a382 | 15 | RCSID("$OpenBSD: canohost.c,v 1.41 2004/07/21 11:51:29 djm 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 *); |
1639bb8f | 23 | static void ipv64_normalise_mapped(struct sockaddr_storage *, socklen_t *); |
61e96248 | 24 | |
aa3378df | 25 | /* |
26 | * Return the canonical name of the host at the other end of the socket. The | |
27 | * caller should free the returned string with xfree. | |
28 | */ | |
8efc0c15 | 29 | |
396c147e | 30 | static char * |
ca75d7de | 31 | get_remote_hostname(int sock, int use_dns) |
8efc0c15 | 32 | { |
48e671d5 | 33 | struct sockaddr_storage from; |
34 | int i; | |
35 | socklen_t fromlen; | |
36 | struct addrinfo hints, *ai, *aitop; | |
61e96248 | 37 | char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 38 | |
39 | /* Get IP address of client. */ | |
40 | fromlen = sizeof(from); | |
41 | memset(&from, 0, sizeof(from)); | |
ca75d7de | 42 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 43 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 44 | cleanup_exit(255); |
5260325f | 45 | } |
1639bb8f | 46 | |
35087869 | 47 | if (from.ss_family == AF_INET) |
ca75d7de | 48 | check_ip_options(sock, ntop); |
35087869 | 49 | |
1639bb8f | 50 | ipv64_normalise_mapped(&from, &fromlen); |
51 | ||
e7ccd20d | 52 | if (from.ss_family == AF_INET6) |
53 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 54 | |
48e671d5 | 55 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 56 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 57 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 58 | |
c5a7d788 | 59 | if (!use_dns) |
60 | return xstrdup(ntop); | |
61 | ||
3a83b819 | 62 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 63 | /* Map the IP address to a host name. */ |
64 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 65 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 66 | /* Host name not found. Use ip address. */ |
61e96248 | 67 | return xstrdup(ntop); |
8efc0c15 | 68 | } |
5260325f | 69 | |
c5a7d788 | 70 | /* |
71 | * if reverse lookup result looks like a numeric hostname, | |
72 | * someone is trying to trick us by PTR record like following: | |
73 | * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 | |
74 | */ | |
75 | memset(&hints, 0, sizeof(hints)); | |
76 | hints.ai_socktype = SOCK_DGRAM; /*dummy*/ | |
c44d7846 | 77 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 78 | if (getaddrinfo(name, "0", &hints, &ai) == 0) { |
79 | logit("Nasty PTR record \"%s\" is set up for %s, ignoring", | |
80 | name, ntop); | |
81 | freeaddrinfo(ai); | |
82 | return xstrdup(ntop); | |
83 | } | |
84 | ||
61e96248 | 85 | /* |
86 | * Convert it to all lowercase (which is expected by the rest | |
87 | * of this software). | |
88 | */ | |
89 | for (i = 0; name[i]; i++) | |
90 | if (isupper(name[i])) | |
91 | name[i] = tolower(name[i]); | |
aa3378df | 92 | /* |
61e96248 | 93 | * Map it back to an IP address and check that the given |
94 | * address actually is an address of this host. This is | |
95 | * necessary because anyone with access to a name server can | |
96 | * define arbitrary names for an IP address. Mapping from | |
97 | * name to IP address can be trusted better (but can still be | |
98 | * fooled if the intruder has access to the name server of | |
99 | * the domain). | |
aa3378df | 100 | */ |
61e96248 | 101 | memset(&hints, 0, sizeof(hints)); |
102 | hints.ai_family = from.ss_family; | |
103 | hints.ai_socktype = SOCK_STREAM; | |
104 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
bbe88b6d | 105 | logit("reverse mapping checking getaddrinfo for %.700s " |
61e96248 | 106 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); |
107 | return xstrdup(ntop); | |
108 | } | |
109 | /* Look for the address from the list of addresses. */ | |
110 | for (ai = aitop; ai; ai = ai->ai_next) { | |
111 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
112 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
113 | (strcmp(ntop, ntop2) == 0)) | |
114 | break; | |
115 | } | |
116 | freeaddrinfo(aitop); | |
117 | /* If we reached the end of the list, the address was not there. */ | |
118 | if (!ai) { | |
119 | /* Address not found for the host name. */ | |
bbe88b6d | 120 | logit("Address %.100s maps to %.600s, but this does not " |
61e96248 | 121 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
122 | ntop, name); | |
123 | return xstrdup(ntop); | |
8efc0c15 | 124 | } |
5260325f | 125 | return xstrdup(name); |
8efc0c15 | 126 | } |
127 | ||
61e96248 | 128 | /* |
129 | * If IP options are supported, make sure there are none (log and | |
130 | * disconnect them if any are found). Basically we are worried about | |
131 | * source routing; it can be used to pretend you are somebody | |
132 | * (ip-address) you are not. That itself may be "almost acceptable" | |
133 | * under certain circumstances, but rhosts autentication is useless | |
134 | * if source routing is accepted. Notice also that if we just dropped | |
135 | * source routing here, the other side could use IP spoofing to do | |
136 | * rest of the interaction and could still bypass security. So we | |
137 | * exit here if we detect any IP options. | |
138 | */ | |
139 | /* IPv4 only */ | |
396c147e | 140 | static void |
ca75d7de | 141 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 142 | { |
97722976 | 143 | #ifdef IP_OPTIONS |
e6fa162e | 144 | u_char options[200]; |
145 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 146 | socklen_t option_size; |
e6fa162e | 147 | int i, ipproto; |
61e96248 | 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); | |
ca75d7de | 155 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 156 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 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]); | |
bbe88b6d | 161 | logit("Connection from %.100s with IP options:%.800s", |
61e96248 | 162 | ipaddr, text); |
163 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
164 | ipaddr, text); | |
165 | } | |
97722976 | 166 | #endif /* IP_OPTIONS */ |
61e96248 | 167 | } |
168 | ||
1639bb8f | 169 | static void |
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 | ||
177 | if (addr->ss_family != AF_INET6 || | |
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 | ||
aa3378df | 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 | */ | |
8efc0c15 | 199 | |
5260325f | 200 | const char * |
c5a7d788 | 201 | get_canonical_hostname(int use_dns) |
8efc0c15 | 202 | { |
48e671d5 | 203 | static char *canonical_host_name = NULL; |
c5a7d788 | 204 | static int use_dns_done = 0; |
48e671d5 | 205 | |
61e96248 | 206 | /* Check if we have previously retrieved name with same option. */ |
207 | if (canonical_host_name != NULL) { | |
c5a7d788 | 208 | if (use_dns_done != use_dns) |
61e96248 | 209 | xfree(canonical_host_name); |
210 | else | |
211 | return canonical_host_name; | |
212 | } | |
8efc0c15 | 213 | |
5260325f | 214 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 215 | if (packet_connection_is_on_socket()) |
61e96248 | 216 | canonical_host_name = get_remote_hostname( |
c5a7d788 | 217 | packet_get_connection_in(), use_dns); |
5260325f | 218 | else |
219 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 220 | |
c5a7d788 | 221 | use_dns_done = use_dns; |
5260325f | 222 | return canonical_host_name; |
8efc0c15 | 223 | } |
224 | ||
aa3378df | 225 | /* |
649bb60b | 226 | * Returns the local/remote IP-address/hostname of socket as a string. |
227 | * The returned string must be freed. | |
aa3378df | 228 | */ |
396c147e | 229 | static char * |
ca75d7de | 230 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 231 | { |
8002af61 | 232 | struct sockaddr_storage addr; |
233 | socklen_t addrlen; | |
48e671d5 | 234 | char ntop[NI_MAXHOST]; |
5260325f | 235 | |
5260325f | 236 | /* Get IP address of client. */ |
8002af61 | 237 | addrlen = sizeof(addr); |
238 | memset(&addr, 0, sizeof(addr)); | |
239 | ||
240 | if (remote) { | |
ca75d7de | 241 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 242 | < 0) |
8002af61 | 243 | return NULL; |
8002af61 | 244 | } else { |
ca75d7de | 245 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 246 | < 0) |
8002af61 | 247 | return NULL; |
5260325f | 248 | } |
e7ccd20d | 249 | |
250 | /* Work around Linux IPv6 weirdness */ | |
251 | if (addr.ss_family == AF_INET6) | |
252 | addrlen = sizeof(struct sockaddr_in6); | |
253 | ||
8002af61 | 254 | /* Get the address in ascii. */ |
255 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
184eed6a | 256 | NULL, 0, flags) != 0) { |
649bb60b | 257 | error("get_socket_address: getnameinfo %d failed", flags); |
865ac82e | 258 | return NULL; |
259 | } | |
260 | return xstrdup(ntop); | |
261 | } | |
48e671d5 | 262 | |
8002af61 | 263 | char * |
ca75d7de | 264 | get_peer_ipaddr(int sock) |
8002af61 | 265 | { |
99443922 | 266 | char *p; |
267 | ||
ca75d7de | 268 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 269 | return p; |
270 | return xstrdup("UNKNOWN"); | |
8002af61 | 271 | } |
272 | ||
273 | char * | |
ca75d7de | 274 | get_local_ipaddr(int sock) |
8002af61 | 275 | { |
99443922 | 276 | char *p; |
277 | ||
ca75d7de | 278 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 279 | return p; |
280 | return xstrdup("UNKNOWN"); | |
8002af61 | 281 | } |
282 | ||
283 | char * | |
ca75d7de | 284 | get_local_name(int sock) |
8002af61 | 285 | { |
ca75d7de | 286 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 287 | } |
288 | ||
865ac82e | 289 | /* |
290 | * Returns the IP-address of the remote host as a string. The returned | |
291 | * string must not be freed. | |
292 | */ | |
5260325f | 293 | |
865ac82e | 294 | const char * |
d5bb9418 | 295 | get_remote_ipaddr(void) |
865ac82e | 296 | { |
297 | static char *canonical_host_ip = NULL; | |
298 | ||
299 | /* Check whether we have cached the ipaddr. */ | |
300 | if (canonical_host_ip == NULL) { | |
301 | if (packet_connection_is_on_socket()) { | |
302 | canonical_host_ip = | |
303 | get_peer_ipaddr(packet_get_connection_in()); | |
304 | if (canonical_host_ip == NULL) | |
2362db19 | 305 | cleanup_exit(255); |
865ac82e | 306 | } else { |
307 | /* If not on socket, return UNKNOWN. */ | |
308 | canonical_host_ip = xstrdup("UNKNOWN"); | |
309 | } | |
310 | } | |
5260325f | 311 | return canonical_host_ip; |
8efc0c15 | 312 | } |
313 | ||
46e3af7f | 314 | const char * |
c5a7d788 | 315 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 316 | { |
317 | static const char *remote = ""; | |
318 | if (utmp_len > 0) | |
c5a7d788 | 319 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 320 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
321 | remote = get_remote_ipaddr(); | |
322 | return remote; | |
323 | } | |
324 | ||
48e671d5 | 325 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 326 | |
396c147e | 327 | static int |
48e671d5 | 328 | get_sock_port(int sock, int local) |
8efc0c15 | 329 | { |
48e671d5 | 330 | struct sockaddr_storage from; |
331 | socklen_t fromlen; | |
332 | char strport[NI_MAXSERV]; | |
5260325f | 333 | |
334 | /* Get IP address of client. */ | |
335 | fromlen = sizeof(from); | |
336 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 337 | if (local) { |
338 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
339 | error("getsockname failed: %.100s", strerror(errno)); | |
340 | return 0; | |
341 | } | |
342 | } else { | |
649bb60b | 343 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 344 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 345 | cleanup_exit(255); |
48e671d5 | 346 | } |
5260325f | 347 | } |
e7ccd20d | 348 | |
349 | /* Work around Linux IPv6 weirdness */ | |
350 | if (from.ss_family == AF_INET6) | |
351 | fromlen = sizeof(struct sockaddr_in6); | |
352 | ||
5260325f | 353 | /* Return port number. */ |
48e671d5 | 354 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
184eed6a | 355 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
48e671d5 | 356 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
357 | return atoi(strport); | |
8efc0c15 | 358 | } |
359 | ||
48e671d5 | 360 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 361 | |
396c147e | 362 | static int |
48e671d5 | 363 | get_port(int local) |
8efc0c15 | 364 | { |
aa3378df | 365 | /* |
366 | * If the connection is not a socket, return 65535. This is | |
367 | * intentionally chosen to be an unprivileged port number. | |
368 | */ | |
48e671d5 | 369 | if (!packet_connection_is_on_socket()) |
5260325f | 370 | return 65535; |
8efc0c15 | 371 | |
48e671d5 | 372 | /* Get socket and return the port number. */ |
373 | return get_sock_port(packet_get_connection_in(), local); | |
374 | } | |
375 | ||
6ae2364d | 376 | int |
48e671d5 | 377 | get_peer_port(int sock) |
378 | { | |
379 | return get_sock_port(sock, 0); | |
380 | } | |
8efc0c15 | 381 | |
6ae2364d | 382 | int |
d5bb9418 | 383 | get_remote_port(void) |
48e671d5 | 384 | { |
13f2a382 | 385 | static int port = -1; |
386 | ||
387 | /* Cache to avoid getpeername() on a dead connection */ | |
388 | if (port == -1) | |
389 | port = get_port(0); | |
390 | ||
391 | return port; | |
48e671d5 | 392 | } |
393 | ||
394 | int | |
d5bb9418 | 395 | get_local_port(void) |
48e671d5 | 396 | { |
397 | return get_port(1); | |
8efc0c15 | 398 | } |