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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; |
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. */ |
59c825e1 | 80 | #if 0 |
61e96248 | 81 | log("Could not reverse map address %.100s.", ntop); |
59c825e1 | 82 | #endif |
61e96248 | 83 | return xstrdup(ntop); |
8efc0c15 | 84 | } |
5260325f | 85 | |
61e96248 | 86 | /* Got host name. */ |
87 | name[sizeof(name) - 1] = '\0'; | |
88 | /* | |
89 | * Convert it to all lowercase (which is expected by the rest | |
90 | * of this software). | |
91 | */ | |
92 | for (i = 0; name[i]; i++) | |
93 | if (isupper(name[i])) | |
94 | name[i] = tolower(name[i]); | |
5260325f | 95 | |
bf4c5edc | 96 | if (!verify_reverse_mapping) |
61e96248 | 97 | return xstrdup(name); |
aa3378df | 98 | /* |
61e96248 | 99 | * Map it back to an IP address and check that the given |
100 | * address actually is an address of this host. This is | |
101 | * necessary because anyone with access to a name server can | |
102 | * define arbitrary names for an IP address. Mapping from | |
103 | * name to IP address can be trusted better (but can still be | |
104 | * fooled if the intruder has access to the name server of | |
105 | * the domain). | |
aa3378df | 106 | */ |
61e96248 | 107 | memset(&hints, 0, sizeof(hints)); |
108 | hints.ai_family = from.ss_family; | |
109 | hints.ai_socktype = SOCK_STREAM; | |
110 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
111 | log("reverse mapping checking getaddrinfo for %.700s " | |
112 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); | |
113 | return xstrdup(ntop); | |
114 | } | |
115 | /* Look for the address from the list of addresses. */ | |
116 | for (ai = aitop; ai; ai = ai->ai_next) { | |
117 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
118 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
119 | (strcmp(ntop, ntop2) == 0)) | |
120 | break; | |
121 | } | |
122 | freeaddrinfo(aitop); | |
123 | /* If we reached the end of the list, the address was not there. */ | |
124 | if (!ai) { | |
125 | /* Address not found for the host name. */ | |
126 | log("Address %.100s maps to %.600s, but this does not " | |
127 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", | |
128 | ntop, name); | |
129 | return xstrdup(ntop); | |
8efc0c15 | 130 | } |
5260325f | 131 | return xstrdup(name); |
8efc0c15 | 132 | } |
133 | ||
61e96248 | 134 | /* |
135 | * If IP options are supported, make sure there are none (log and | |
136 | * disconnect them if any are found). Basically we are worried about | |
137 | * source routing; it can be used to pretend you are somebody | |
138 | * (ip-address) you are not. That itself may be "almost acceptable" | |
139 | * under certain circumstances, but rhosts autentication is useless | |
140 | * if source routing is accepted. Notice also that if we just dropped | |
141 | * source routing here, the other side could use IP spoofing to do | |
142 | * rest of the interaction and could still bypass security. So we | |
143 | * exit here if we detect any IP options. | |
144 | */ | |
145 | /* IPv4 only */ | |
396c147e | 146 | static void |
61e96248 | 147 | check_ip_options(int socket, char *ipaddr) |
148 | { | |
e6fa162e | 149 | u_char options[200]; |
150 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 151 | socklen_t option_size; |
e6fa162e | 152 | int i, ipproto; |
61e96248 | 153 | struct protoent *ip; |
154 | ||
155 | if ((ip = getprotobyname("ip")) != NULL) | |
156 | ipproto = ip->p_proto; | |
157 | else | |
158 | ipproto = IPPROTO_IP; | |
159 | option_size = sizeof(options); | |
db518d9b | 160 | if (getsockopt(socket, ipproto, IP_OPTIONS, options, |
61e96248 | 161 | &option_size) >= 0 && option_size != 0) { |
e6fa162e | 162 | text[0] = '\0'; |
163 | for (i = 0; i < option_size; i++) | |
164 | snprintf(text + i*3, sizeof(text) - i*3, | |
165 | " %2.2x", options[i]); | |
61e96248 | 166 | log("Connection from %.100s with IP options:%.800s", |
167 | ipaddr, text); | |
168 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
169 | ipaddr, text); | |
170 | } | |
171 | } | |
172 | ||
aa3378df | 173 | /* |
174 | * Return the canonical name of the host in the other side of the current | |
175 | * connection. The host name is cached, so it is efficient to call this | |
176 | * several times. | |
177 | */ | |
8efc0c15 | 178 | |
5260325f | 179 | const char * |
bf4c5edc | 180 | get_canonical_hostname(int verify_reverse_mapping) |
8efc0c15 | 181 | { |
48e671d5 | 182 | static char *canonical_host_name = NULL; |
bf4c5edc | 183 | static int verify_reverse_mapping_done = 0; |
48e671d5 | 184 | |
61e96248 | 185 | /* Check if we have previously retrieved name with same option. */ |
186 | if (canonical_host_name != NULL) { | |
bf4c5edc | 187 | if (verify_reverse_mapping_done != verify_reverse_mapping) |
61e96248 | 188 | xfree(canonical_host_name); |
189 | else | |
190 | return canonical_host_name; | |
191 | } | |
8efc0c15 | 192 | |
5260325f | 193 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 194 | if (packet_connection_is_on_socket()) |
61e96248 | 195 | canonical_host_name = get_remote_hostname( |
bf4c5edc | 196 | packet_get_connection_in(), verify_reverse_mapping); |
5260325f | 197 | else |
198 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 199 | |
bf4c5edc | 200 | verify_reverse_mapping_done = verify_reverse_mapping; |
5260325f | 201 | return canonical_host_name; |
8efc0c15 | 202 | } |
203 | ||
aa3378df | 204 | /* |
649bb60b | 205 | * Returns the local/remote IP-address/hostname of socket as a string. |
206 | * The returned string must be freed. | |
aa3378df | 207 | */ |
396c147e | 208 | static char * |
8002af61 | 209 | get_socket_address(int socket, int remote, int flags) |
8efc0c15 | 210 | { |
8002af61 | 211 | struct sockaddr_storage addr; |
212 | socklen_t addrlen; | |
48e671d5 | 213 | char ntop[NI_MAXHOST]; |
5260325f | 214 | |
5260325f | 215 | /* Get IP address of client. */ |
8002af61 | 216 | addrlen = sizeof(addr); |
217 | memset(&addr, 0, sizeof(addr)); | |
218 | ||
219 | if (remote) { | |
220 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
99443922 | 221 | < 0) |
8002af61 | 222 | return NULL; |
8002af61 | 223 | } else { |
224 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
99443922 | 225 | < 0) |
8002af61 | 226 | return NULL; |
5260325f | 227 | } |
8002af61 | 228 | /* Get the address in ascii. */ |
229 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
184eed6a | 230 | NULL, 0, flags) != 0) { |
649bb60b | 231 | error("get_socket_address: getnameinfo %d failed", flags); |
865ac82e | 232 | return NULL; |
233 | } | |
234 | return xstrdup(ntop); | |
235 | } | |
48e671d5 | 236 | |
8002af61 | 237 | char * |
238 | get_peer_ipaddr(int socket) | |
239 | { | |
99443922 | 240 | char *p; |
241 | ||
242 | if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL) | |
243 | return p; | |
244 | return xstrdup("UNKNOWN"); | |
8002af61 | 245 | } |
246 | ||
247 | char * | |
248 | get_local_ipaddr(int socket) | |
249 | { | |
99443922 | 250 | char *p; |
251 | ||
252 | if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL) | |
253 | return p; | |
254 | return xstrdup("UNKNOWN"); | |
8002af61 | 255 | } |
256 | ||
257 | char * | |
258 | get_local_name(int socket) | |
259 | { | |
260 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
261 | } | |
262 | ||
865ac82e | 263 | /* |
264 | * Returns the IP-address of the remote host as a string. The returned | |
265 | * string must not be freed. | |
266 | */ | |
5260325f | 267 | |
865ac82e | 268 | const char * |
d5bb9418 | 269 | get_remote_ipaddr(void) |
865ac82e | 270 | { |
271 | static char *canonical_host_ip = NULL; | |
272 | ||
273 | /* Check whether we have cached the ipaddr. */ | |
274 | if (canonical_host_ip == NULL) { | |
275 | if (packet_connection_is_on_socket()) { | |
276 | canonical_host_ip = | |
277 | get_peer_ipaddr(packet_get_connection_in()); | |
278 | if (canonical_host_ip == NULL) | |
279 | fatal_cleanup(); | |
280 | } else { | |
281 | /* If not on socket, return UNKNOWN. */ | |
282 | canonical_host_ip = xstrdup("UNKNOWN"); | |
283 | } | |
284 | } | |
5260325f | 285 | return canonical_host_ip; |
8efc0c15 | 286 | } |
287 | ||
46e3af7f | 288 | const char * |
bf4c5edc | 289 | get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping) |
46e3af7f | 290 | { |
291 | static const char *remote = ""; | |
292 | if (utmp_len > 0) | |
bf4c5edc | 293 | remote = get_canonical_hostname(verify_reverse_mapping); |
46e3af7f | 294 | if (utmp_len == 0 || strlen(remote) > utmp_len) |
295 | remote = get_remote_ipaddr(); | |
296 | return remote; | |
297 | } | |
298 | ||
48e671d5 | 299 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 300 | |
396c147e | 301 | static int |
48e671d5 | 302 | get_sock_port(int sock, int local) |
8efc0c15 | 303 | { |
48e671d5 | 304 | struct sockaddr_storage from; |
305 | socklen_t fromlen; | |
306 | char strport[NI_MAXSERV]; | |
5260325f | 307 | |
308 | /* Get IP address of client. */ | |
309 | fromlen = sizeof(from); | |
310 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 311 | if (local) { |
312 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
313 | error("getsockname failed: %.100s", strerror(errno)); | |
314 | return 0; | |
315 | } | |
316 | } else { | |
649bb60b | 317 | if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { |
48e671d5 | 318 | debug("getpeername failed: %.100s", strerror(errno)); |
319 | fatal_cleanup(); | |
320 | } | |
5260325f | 321 | } |
322 | /* Return port number. */ | |
48e671d5 | 323 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
184eed6a | 324 | strport, sizeof(strport), NI_NUMERICSERV) != 0) |
48e671d5 | 325 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); |
326 | return atoi(strport); | |
8efc0c15 | 327 | } |
328 | ||
48e671d5 | 329 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 330 | |
396c147e | 331 | static int |
48e671d5 | 332 | get_port(int local) |
8efc0c15 | 333 | { |
aa3378df | 334 | /* |
335 | * If the connection is not a socket, return 65535. This is | |
336 | * intentionally chosen to be an unprivileged port number. | |
337 | */ | |
48e671d5 | 338 | if (!packet_connection_is_on_socket()) |
5260325f | 339 | return 65535; |
8efc0c15 | 340 | |
48e671d5 | 341 | /* Get socket and return the port number. */ |
342 | return get_sock_port(packet_get_connection_in(), local); | |
343 | } | |
344 | ||
6ae2364d | 345 | int |
48e671d5 | 346 | get_peer_port(int sock) |
347 | { | |
348 | return get_sock_port(sock, 0); | |
349 | } | |
8efc0c15 | 350 | |
6ae2364d | 351 | int |
d5bb9418 | 352 | get_remote_port(void) |
48e671d5 | 353 | { |
354 | return get_port(0); | |
355 | } | |
356 | ||
357 | int | |
d5bb9418 | 358 | get_local_port(void) |
48e671d5 | 359 | { |
360 | return get_port(1); | |
8efc0c15 | 361 | } |