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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" | |
aa686c54 | 15 | RCSID("$OpenBSD: canohost.c,v 1.32 2002/06/11 08:11:45 itojun 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)); | |
61e96248 | 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; |
62 | memcpy(&from4->sin_addr, &addr, sizeof(addr)); | |
63 | from4->sin_port = port; | |
64 | } | |
65 | } | |
66 | #endif | |
67 | ||
48e671d5 | 68 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
184eed6a | 69 | NULL, 0, NI_NUMERICHOST) != 0) |
48e671d5 | 70 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); |
5260325f | 71 | |
aa686c54 | 72 | if (from.ss_family == AF_INET) |
73 | check_ip_options(socket, ntop); | |
74 | ||
3a83b819 | 75 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 76 | /* Map the IP address to a host name. */ |
77 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
184eed6a | 78 | NULL, 0, NI_NAMEREQD) != 0) { |
61e96248 | 79 | /* Host name not found. Use ip address. */ |
80 | log("Could not reverse map address %.100s.", ntop); | |
81 | return xstrdup(ntop); | |
8efc0c15 | 82 | } |
5260325f | 83 | |
61e96248 | 84 | /* Got host name. */ |
85 | name[sizeof(name) - 1] = '\0'; | |
86 | /* | |
87 | * Convert it to all lowercase (which is expected by the rest | |
88 | * of this software). | |
89 | */ | |
90 | for (i = 0; name[i]; i++) | |
91 | if (isupper(name[i])) | |
92 | name[i] = tolower(name[i]); | |
5260325f | 93 | |
bf4c5edc | 94 | if (!verify_reverse_mapping) |
61e96248 | 95 | return xstrdup(name); |
aa3378df | 96 | /* |
61e96248 | 97 | * Map it back to an IP address and check that the given |
98 | * address actually is an address of this host. This is | |
99 | * necessary because anyone with access to a name server can | |
100 | * define arbitrary names for an IP address. Mapping from | |
101 | * name to IP address can be trusted better (but can still be | |
102 | * fooled if the intruder has access to the name server of | |
103 | * the domain). | |
aa3378df | 104 | */ |
61e96248 | 105 | memset(&hints, 0, sizeof(hints)); |
106 | hints.ai_family = from.ss_family; | |
107 | hints.ai_socktype = SOCK_STREAM; | |
108 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
109 | log("reverse mapping checking getaddrinfo for %.700s " | |
110 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); | |
111 | return xstrdup(ntop); | |
112 | } | |
113 | /* Look for the address from the list of addresses. */ | |
114 | for (ai = aitop; ai; ai = ai->ai_next) { | |
115 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
116 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
117 | (strcmp(ntop, ntop2) == 0)) | |
118 | break; | |
119 | } | |
120 | freeaddrinfo(aitop); | |
121 | /* If we reached the end of the list, the address was not there. */ | |
122 | if (!ai) { | |
123 | /* Address not found for the host name. */ | |
124 | log("Address %.100s maps to %.600s, but this does not " | |
125 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", | |
126 | ntop, name); | |
127 | return xstrdup(ntop); | |
8efc0c15 | 128 | } |
5260325f | 129 | return xstrdup(name); |
8efc0c15 | 130 | } |
131 | ||
61e96248 | 132 | /* |
133 | * If IP options are supported, make sure there are none (log and | |
134 | * disconnect them if any are found). Basically we are worried about | |
135 | * source routing; it can be used to pretend you are somebody | |
136 | * (ip-address) you are not. That itself may be "almost acceptable" | |
137 | * under certain circumstances, but rhosts autentication is useless | |
138 | * if source routing is accepted. Notice also that if we just dropped | |
139 | * source routing here, the other side could use IP spoofing to do | |
140 | * rest of the interaction and could still bypass security. So we | |
141 | * exit here if we detect any IP options. | |
142 | */ | |
143 | /* IPv4 only */ | |
396c147e | 144 | static void |
61e96248 | 145 | check_ip_options(int socket, char *ipaddr) |
146 | { | |
e6fa162e | 147 | u_char options[200]; |
148 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 149 | socklen_t option_size; |
e6fa162e | 150 | int i, ipproto; |
61e96248 | 151 | struct protoent *ip; |
152 | ||
153 | if ((ip = getprotobyname("ip")) != NULL) | |
154 | ipproto = ip->p_proto; | |
155 | else | |
156 | ipproto = IPPROTO_IP; | |
157 | option_size = sizeof(options); | |
db518d9b | 158 | if (getsockopt(socket, ipproto, IP_OPTIONS, options, |
61e96248 | 159 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 160 | text[0] = '\0'; |
161 | for (i = 0; i < option_size; i++) | |
162 | snprintf(text + i*3, sizeof(text) - i*3, | |
163 | " %2.2x", options[i]); | |
61e96248 | 164 | log("Connection from %.100s with IP options:%.800s", |
165 | ipaddr, text); | |
166 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
167 | ipaddr, text); | |
168 | } | |
169 | } | |
170 | ||
aa3378df | 171 | /* |
172 | * Return the canonical name of the host in the other side of the current | |
173 | * connection. The host name is cached, so it is efficient to call this | |
174 | * several times. | |
175 | */ | |
8efc0c15 | 176 | |
5260325f | 177 | const char * |
bf4c5edc | 178 | get_canonical_hostname(int verify_reverse_mapping) |
8efc0c15 | 179 | { |
48e671d5 | 180 | static char *canonical_host_name = NULL; |
bf4c5edc | 181 | static int verify_reverse_mapping_done = 0; |
48e671d5 | 182 | |
61e96248 | 183 | /* Check if we have previously retrieved name with same option. */ |
184 | if (canonical_host_name != NULL) { | |
bf4c5edc | 185 | if (verify_reverse_mapping_done != verify_reverse_mapping) |
61e96248 | 186 | xfree(canonical_host_name); |
187 | else | |
188 | return canonical_host_name; | |
189 | } | |
8efc0c15 | 190 | |
5260325f | 191 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 192 | if (packet_connection_is_on_socket()) |
61e96248 | 193 | canonical_host_name = get_remote_hostname( |
bf4c5edc | 194 | packet_get_connection_in(), verify_reverse_mapping); |
5260325f | 195 | else |
196 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 197 | |
bf4c5edc | 198 | verify_reverse_mapping_done = verify_reverse_mapping; |
5260325f | 199 | return canonical_host_name; |
8efc0c15 | 200 | } |
201 | ||
aa3378df | 202 | /* |
865ac82e | 203 | * Returns the remote IP-address of socket as a string. The returned |
204 | * string must be freed. | |
aa3378df | 205 | */ |
396c147e | 206 | static char * |
8002af61 | 207 | get_socket_address(int socket, int remote, int flags) |
8efc0c15 | 208 | { |
8002af61 | 209 | struct sockaddr_storage addr; |
210 | socklen_t addrlen; | |
48e671d5 | 211 | char ntop[NI_MAXHOST]; |
5260325f | 212 | |
5260325f | 213 | /* Get IP address of client. */ |
8002af61 | 214 | addrlen = sizeof(addr); |
215 | memset(&addr, 0, sizeof(addr)); | |
216 | ||
217 | if (remote) { | |
218 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
219 | < 0) { | |
220 | debug("get_socket_ipaddr: getpeername failed: %.100s", | |
221 | strerror(errno)); | |
222 | return NULL; | |
223 | } | |
224 | } else { | |
225 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
226 | < 0) { | |
227 | debug("get_socket_ipaddr: getsockname failed: %.100s", | |
228 | strerror(errno)); | |
229 | return NULL; | |
230 | } | |
5260325f | 231 | } |
8002af61 | 232 | /* Get the address in ascii. */ |
233 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
184eed6a | 234 | NULL, 0, flags) != 0) { |
8002af61 | 235 | error("get_socket_ipaddr: getnameinfo %d failed", flags); |
865ac82e | 236 | return NULL; |
237 | } | |
238 | return xstrdup(ntop); | |
239 | } | |
48e671d5 | 240 | |
8002af61 | 241 | char * |
242 | get_peer_ipaddr(int socket) | |
243 | { | |
244 | return get_socket_address(socket, 1, NI_NUMERICHOST); | |
245 | } | |
246 | ||
247 | char * | |
248 | get_local_ipaddr(int socket) | |
249 | { | |
250 | return get_socket_address(socket, 0, NI_NUMERICHOST); | |
251 | } | |
252 | ||
253 | char * | |
254 | get_local_name(int socket) | |
255 | { | |
256 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
257 | } | |
258 | ||
865ac82e | 259 | /* |
260 | * Returns the IP-address of the remote host as a string. The returned | |
261 | * string must not be freed. | |
262 | */ | |
5260325f | 263 | |
865ac82e | 264 | const char * |
d5bb9418 | 265 | get_remote_ipaddr(void) |
865ac82e | 266 | { |
267 | static char *canonical_host_ip = NULL; | |
268 | ||
269 | /* Check whether we have cached the ipaddr. */ | |
270 | if (canonical_host_ip == NULL) { | |
271 | if (packet_connection_is_on_socket()) { | |
272 | canonical_host_ip = | |
273 | get_peer_ipaddr(packet_get_connection_in()); | |
274 | if (canonical_host_ip == NULL) | |
275 | fatal_cleanup(); | |
276 | } else { | |
277 | /* If not on socket, return UNKNOWN. */ | |
278 | canonical_host_ip = xstrdup("UNKNOWN"); | |
279 | } | |
280 | } | |
5260325f | 281 | return canonical_host_ip; |
8efc0c15 | 282 | } |
283 | ||
46e3af7f | 284 | const char * |
bf4c5edc | 285 | get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping) |
46e3af7f | 286 | { |
287 | static const char *remote = ""; | |
288 | if (utmp_len > 0) | |
bf4c5edc | 289 | remote = get_canonical_hostname(verify_reverse_mapping); |
46e3af7f | 290 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
291 | remote = get_remote_ipaddr(); | |
292 | return remote; | |
293 | } | |
294 | ||
48e671d5 | 295 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 296 | |
396c147e | 297 | static int |
48e671d5 | 298 | get_sock_port(int sock, int local) |
8efc0c15 | 299 | { |
48e671d5 | 300 | struct sockaddr_storage from; |
301 | socklen_t fromlen; | |
302 | char strport[NI_MAXSERV]; | |
5260325f | 303 | |
304 | /* Get IP address of client. */ | |
305 | fromlen = sizeof(from); | |
306 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 307 | if (local) { |
308 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
309 | error("getsockname failed: %.100s", strerror(errno)); | |
310 | return 0; | |
311 | } | |
312 | } else { | |
313 | if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) { | |
314 | debug("getpeername failed: %.100s", strerror(errno)); | |
315 | fatal_cleanup(); | |
316 | } | |
5260325f | 317 | } |
318 | /* Return port number. */ | |
48e671d5 | 319 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
184eed6a | 320 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
48e671d5 | 321 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
322 | return atoi(strport); | |
8efc0c15 | 323 | } |
324 | ||
48e671d5 | 325 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 326 | |
396c147e | 327 | static int |
48e671d5 | 328 | get_port(int local) |
8efc0c15 | 329 | { |
aa3378df | 330 | /* |
331 | * If the connection is not a socket, return 65535. This is | |
332 | * intentionally chosen to be an unprivileged port number. | |
333 | */ | |
48e671d5 | 334 | if (!packet_connection_is_on_socket()) |
5260325f | 335 | return 65535; |
8efc0c15 | 336 | |
48e671d5 | 337 | /* Get socket and return the port number. */ |
338 | return get_sock_port(packet_get_connection_in(), local); | |
339 | } | |
340 | ||
6ae2364d | 341 | int |
48e671d5 | 342 | get_peer_port(int sock) |
343 | { | |
344 | return get_sock_port(sock, 0); | |
345 | } | |
8efc0c15 | 346 | |
6ae2364d | 347 | int |
d5bb9418 | 348 | get_remote_port(void) |
48e671d5 | 349 | { |
350 | return get_port(0); | |
351 | } | |
352 | ||
353 | int | |
d5bb9418 | 354 | get_local_port(void) |
48e671d5 | 355 | { |
356 | return get_port(1); | |
8efc0c15 | 357 | } |