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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 *); |
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 * |
ca75d7de | 30 | get_remote_hostname(int sock, 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)); | |
ca75d7de | 41 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
5260325f | 42 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 43 | cleanup_exit(255); |
5260325f | 44 | } |
1639bb8f | 45 | |
35087869 | 46 | if (from.ss_family == AF_INET) |
ca75d7de | 47 | check_ip_options(sock, ntop); |
35087869 | 48 | |
1639bb8f | 49 | ipv64_normalise_mapped(&from, &fromlen); |
50 | ||
e7ccd20d | 51 | if (from.ss_family == AF_INET6) |
52 | fromlen = sizeof(struct sockaddr_in6); | |
80faa19f | 53 | |
48e671d5 | 54 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 55 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 56 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 57 | |
c5a7d788 | 58 | if (!use_dns) |
59 | return xstrdup(ntop); | |
60 | ||
3a83b819 | 61 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 62 | /* Map the IP address to a host name. */ |
63 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 64 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 65 | /* Host name not found. Use ip address. */ |
61e96248 | 66 | return xstrdup(ntop); |
8efc0c15 | 67 | } |
5260325f | 68 | |
c5a7d788 | 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*/ | |
c44d7846 | 76 | hints.ai_flags = AI_NUMERICHOST; |
c5a7d788 | 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 | ||
61e96248 | 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]); | |
aa3378df | 91 | /* |
61e96248 | 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). | |
aa3378df | 99 | */ |
61e96248 | 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) { | |
bbe88b6d | 104 | logit("reverse mapping checking getaddrinfo for %.700s " |
61e96248 | 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. */ | |
bbe88b6d | 119 | logit("Address %.100s maps to %.600s, but this does not " |
61e96248 | 120 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
121 | ntop, name); | |
122 | return xstrdup(ntop); | |
8efc0c15 | 123 | } |
5260325f | 124 | return xstrdup(name); |
8efc0c15 | 125 | } |
126 | ||
61e96248 | 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 */ | |
396c147e | 139 | static void |
ca75d7de | 140 | check_ip_options(int sock, char *ipaddr) |
61e96248 | 141 | { |
97722976 | 142 | #ifdef IP_OPTIONS |
e6fa162e | 143 | u_char options[200]; |
144 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 145 | socklen_t option_size; |
e6fa162e | 146 | int i, ipproto; |
61e96248 | 147 | struct protoent *ip; |
148 | ||
149 | if ((ip = getprotobyname("ip")) != NULL) | |
150 | ipproto = ip->p_proto; | |
151 | else | |
152 | ipproto = IPPROTO_IP; | |
153 | option_size = sizeof(options); | |
ca75d7de | 154 | if (getsockopt(sock, ipproto, IP_OPTIONS, options, |
61e96248 | 155 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 156 | text[0] = '\0'; |
157 | for (i = 0; i < option_size; i++) | |
158 | snprintf(text + i*3, sizeof(text) - i*3, | |
159 | " %2.2x", options[i]); | |
bbe88b6d | 160 | logit("Connection from %.100s with IP options:%.800s", |
61e96248 | 161 | ipaddr, text); |
162 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
163 | ipaddr, text); | |
164 | } | |
97722976 | 165 | #endif /* IP_OPTIONS */ |
61e96248 | 166 | } |
167 | ||
b6610e8f | 168 | void |
1639bb8f | 169 | ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) |
170 | { | |
171 | struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr; | |
172 | struct sockaddr_in *a4 = (struct sockaddr_in *)addr; | |
173 | struct in_addr inaddr; | |
174 | u_int16_t port; | |
175 | ||
176 | if (addr->ss_family != AF_INET6 || | |
177 | !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr)) | |
178 | return; | |
179 | ||
180 | debug3("Normalising mapped IPv4 in IPv6 address"); | |
181 | ||
182 | memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr)); | |
183 | port = a6->sin6_port; | |
184 | ||
185 | memset(addr, 0, sizeof(*a4)); | |
186 | ||
187 | a4->sin_family = AF_INET; | |
188 | *len = sizeof(*a4); | |
189 | memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); | |
190 | a4->sin_port = port; | |
191 | } | |
192 | ||
aa3378df | 193 | /* |
194 | * Return the canonical name of the host in the other side of the current | |
195 | * connection. The host name is cached, so it is efficient to call this | |
196 | * several times. | |
197 | */ | |
8efc0c15 | 198 | |
5260325f | 199 | const char * |
c5a7d788 | 200 | get_canonical_hostname(int use_dns) |
8efc0c15 | 201 | { |
48e671d5 | 202 | static char *canonical_host_name = NULL; |
c5a7d788 | 203 | static int use_dns_done = 0; |
48e671d5 | 204 | |
61e96248 | 205 | /* Check if we have previously retrieved name with same option. */ |
206 | if (canonical_host_name != NULL) { | |
c5a7d788 | 207 | if (use_dns_done != use_dns) |
61e96248 | 208 | xfree(canonical_host_name); |
209 | else | |
210 | return canonical_host_name; | |
211 | } | |
8efc0c15 | 212 | |
5260325f | 213 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 214 | if (packet_connection_is_on_socket()) |
61e96248 | 215 | canonical_host_name = get_remote_hostname( |
c5a7d788 | 216 | packet_get_connection_in(), use_dns); |
5260325f | 217 | else |
218 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 219 | |
c5a7d788 | 220 | use_dns_done = use_dns; |
5260325f | 221 | return canonical_host_name; |
8efc0c15 | 222 | } |
223 | ||
aa3378df | 224 | /* |
649bb60b | 225 | * Returns the local/remote IP-address/hostname of socket as a string. |
226 | * The returned string must be freed. | |
aa3378df | 227 | */ |
396c147e | 228 | static char * |
ca75d7de | 229 | get_socket_address(int sock, int remote, int flags) |
8efc0c15 | 230 | { |
8002af61 | 231 | struct sockaddr_storage addr; |
232 | socklen_t addrlen; | |
48e671d5 | 233 | char ntop[NI_MAXHOST]; |
5260325f | 234 | |
5260325f | 235 | /* Get IP address of client. */ |
8002af61 | 236 | addrlen = sizeof(addr); |
237 | memset(&addr, 0, sizeof(addr)); | |
238 | ||
239 | if (remote) { | |
ca75d7de | 240 | if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 241 | < 0) |
8002af61 | 242 | return NULL; |
8002af61 | 243 | } else { |
ca75d7de | 244 | if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) |
99443922 | 245 | < 0) |
8002af61 | 246 | return NULL; |
5260325f | 247 | } |
e7ccd20d | 248 | |
249 | /* Work around Linux IPv6 weirdness */ | |
250 | if (addr.ss_family == AF_INET6) | |
251 | addrlen = sizeof(struct sockaddr_in6); | |
252 | ||
8002af61 | 253 | /* Get the address in ascii. */ |
254 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
184eed6a | 255 | NULL, 0, flags) != 0) { |
649bb60b | 256 | error("get_socket_address: getnameinfo %d failed", flags); |
865ac82e | 257 | return NULL; |
258 | } | |
259 | return xstrdup(ntop); | |
260 | } | |
48e671d5 | 261 | |
8002af61 | 262 | char * |
ca75d7de | 263 | get_peer_ipaddr(int sock) |
8002af61 | 264 | { |
99443922 | 265 | char *p; |
266 | ||
ca75d7de | 267 | if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) |
99443922 | 268 | return p; |
269 | return xstrdup("UNKNOWN"); | |
8002af61 | 270 | } |
271 | ||
272 | char * | |
ca75d7de | 273 | get_local_ipaddr(int sock) |
8002af61 | 274 | { |
99443922 | 275 | char *p; |
276 | ||
ca75d7de | 277 | if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) |
99443922 | 278 | return p; |
279 | return xstrdup("UNKNOWN"); | |
8002af61 | 280 | } |
281 | ||
282 | char * | |
ca75d7de | 283 | get_local_name(int sock) |
8002af61 | 284 | { |
ca75d7de | 285 | return get_socket_address(sock, 0, NI_NAMEREQD); |
8002af61 | 286 | } |
287 | ||
865ac82e | 288 | /* |
289 | * Returns the IP-address of the remote host as a string. The returned | |
290 | * string must not be freed. | |
291 | */ | |
5260325f | 292 | |
865ac82e | 293 | const char * |
d5bb9418 | 294 | get_remote_ipaddr(void) |
865ac82e | 295 | { |
296 | static char *canonical_host_ip = NULL; | |
297 | ||
298 | /* Check whether we have cached the ipaddr. */ | |
299 | if (canonical_host_ip == NULL) { | |
300 | if (packet_connection_is_on_socket()) { | |
301 | canonical_host_ip = | |
302 | get_peer_ipaddr(packet_get_connection_in()); | |
303 | if (canonical_host_ip == NULL) | |
2362db19 | 304 | cleanup_exit(255); |
865ac82e | 305 | } else { |
306 | /* If not on socket, return UNKNOWN. */ | |
307 | canonical_host_ip = xstrdup("UNKNOWN"); | |
308 | } | |
309 | } | |
5260325f | 310 | return canonical_host_ip; |
8efc0c15 | 311 | } |
312 | ||
46e3af7f | 313 | const char * |
c5a7d788 | 314 | get_remote_name_or_ip(u_int utmp_len, int use_dns) |
46e3af7f | 315 | { |
316 | static const char *remote = ""; | |
317 | if (utmp_len > 0) | |
c5a7d788 | 318 | remote = get_canonical_hostname(use_dns); |
46e3af7f | 319 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
320 | remote = get_remote_ipaddr(); | |
321 | return remote; | |
322 | } | |
323 | ||
48e671d5 | 324 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 325 | |
396c147e | 326 | static int |
48e671d5 | 327 | get_sock_port(int sock, int local) |
8efc0c15 | 328 | { |
48e671d5 | 329 | struct sockaddr_storage from; |
330 | socklen_t fromlen; | |
331 | char strport[NI_MAXSERV]; | |
5260325f | 332 | |
333 | /* Get IP address of client. */ | |
334 | fromlen = sizeof(from); | |
335 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 336 | if (local) { |
337 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
338 | error("getsockname failed: %.100s", strerror(errno)); | |
339 | return 0; | |
340 | } | |
341 | } else { | |
649bb60b | 342 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 343 | debug("getpeername failed: %.100s", strerror(errno)); |
2362db19 | 344 | cleanup_exit(255); |
48e671d5 | 345 | } |
5260325f | 346 | } |
e7ccd20d | 347 | |
348 | /* Work around Linux IPv6 weirdness */ | |
349 | if (from.ss_family == AF_INET6) | |
350 | fromlen = sizeof(struct sockaddr_in6); | |
351 | ||
5260325f | 352 | /* Return port number. */ |
48e671d5 | 353 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
184eed6a | 354 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
48e671d5 | 355 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
356 | return atoi(strport); | |
8efc0c15 | 357 | } |
358 | ||
48e671d5 | 359 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 360 | |
396c147e | 361 | static int |
48e671d5 | 362 | get_port(int local) |
8efc0c15 | 363 | { |
aa3378df | 364 | /* |
365 | * If the connection is not a socket, return 65535. This is | |
366 | * intentionally chosen to be an unprivileged port number. | |
367 | */ | |
48e671d5 | 368 | if (!packet_connection_is_on_socket()) |
5260325f | 369 | return 65535; |
8efc0c15 | 370 | |
48e671d5 | 371 | /* Get socket and return the port number. */ |
372 | return get_sock_port(packet_get_connection_in(), local); | |
373 | } | |
374 | ||
6ae2364d | 375 | int |
48e671d5 | 376 | get_peer_port(int sock) |
377 | { | |
378 | return get_sock_port(sock, 0); | |
379 | } | |
8efc0c15 | 380 | |
6ae2364d | 381 | int |
d5bb9418 | 382 | get_remote_port(void) |
48e671d5 | 383 | { |
13f2a382 | 384 | static int port = -1; |
385 | ||
386 | /* Cache to avoid getpeername() on a dead connection */ | |
387 | if (port == -1) | |
388 | port = get_port(0); | |
389 | ||
390 | return port; | |
48e671d5 | 391 | } |
392 | ||
393 | int | |
d5bb9418 | 394 | get_local_port(void) |
48e671d5 | 395 | { |
396 | return get_port(1); | |
8efc0c15 | 397 | } |