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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" | |
d5bb9418 | 15 | RCSID("$OpenBSD: canohost.c,v 1.28 2001/12/05 03:56:39 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 * |
61e96248 | 30 | get_remote_hostname(int socket, int reverse_mapping_check) |
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 | |
61e96248 | 67 | if (from.ss_family == AF_INET) |
68 | check_ip_options(socket, ntop); | |
80faa19f | 69 | |
48e671d5 | 70 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
71 | NULL, 0, NI_NUMERICHOST) != 0) | |
72 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); | |
5260325f | 73 | |
3a83b819 | 74 | debug3("Trying to reverse map address %.100s.", ntop); |
48e671d5 | 75 | /* Map the IP address to a host name. */ |
76 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
61e96248 | 77 | NULL, 0, NI_NAMEREQD) != 0) { |
78 | /* Host name not found. Use ip address. */ | |
79 | log("Could not reverse map address %.100s.", ntop); | |
80 | return xstrdup(ntop); | |
8efc0c15 | 81 | } |
5260325f | 82 | |
61e96248 | 83 | /* Got host name. */ |
84 | name[sizeof(name) - 1] = '\0'; | |
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]); | |
5260325f | 92 | |
61e96248 | 93 | if (!reverse_mapping_check) |
94 | return xstrdup(name); | |
aa3378df | 95 | /* |
61e96248 | 96 | * Map it back to an IP address and check that the given |
97 | * address actually is an address of this host. This is | |
98 | * necessary because anyone with access to a name server can | |
99 | * define arbitrary names for an IP address. Mapping from | |
100 | * name to IP address can be trusted better (but can still be | |
101 | * fooled if the intruder has access to the name server of | |
102 | * the domain). | |
aa3378df | 103 | */ |
61e96248 | 104 | memset(&hints, 0, sizeof(hints)); |
105 | hints.ai_family = from.ss_family; | |
106 | hints.ai_socktype = SOCK_STREAM; | |
107 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
108 | log("reverse mapping checking getaddrinfo for %.700s " | |
109 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); | |
110 | return xstrdup(ntop); | |
111 | } | |
112 | /* Look for the address from the list of addresses. */ | |
113 | for (ai = aitop; ai; ai = ai->ai_next) { | |
114 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
115 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
116 | (strcmp(ntop, ntop2) == 0)) | |
117 | break; | |
118 | } | |
119 | freeaddrinfo(aitop); | |
120 | /* If we reached the end of the list, the address was not there. */ | |
121 | if (!ai) { | |
122 | /* Address not found for the host name. */ | |
123 | log("Address %.100s maps to %.600s, but this does not " | |
124 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", | |
125 | ntop, name); | |
126 | return xstrdup(ntop); | |
8efc0c15 | 127 | } |
5260325f | 128 | return xstrdup(name); |
8efc0c15 | 129 | } |
130 | ||
61e96248 | 131 | /* |
132 | * If IP options are supported, make sure there are none (log and | |
133 | * disconnect them if any are found). Basically we are worried about | |
134 | * source routing; it can be used to pretend you are somebody | |
135 | * (ip-address) you are not. That itself may be "almost acceptable" | |
136 | * under certain circumstances, but rhosts autentication is useless | |
137 | * if source routing is accepted. Notice also that if we just dropped | |
138 | * source routing here, the other side could use IP spoofing to do | |
139 | * rest of the interaction and could still bypass security. So we | |
140 | * exit here if we detect any IP options. | |
141 | */ | |
142 | /* IPv4 only */ | |
396c147e | 143 | static void |
61e96248 | 144 | check_ip_options(int socket, char *ipaddr) |
145 | { | |
e6fa162e | 146 | u_char options[200]; |
147 | char text[sizeof(options) * 3 + 1]; | |
61e96248 | 148 | socklen_t option_size; |
e6fa162e | 149 | int i, ipproto; |
61e96248 | 150 | struct protoent *ip; |
151 | ||
152 | if ((ip = getprotobyname("ip")) != NULL) | |
153 | ipproto = ip->p_proto; | |
154 | else | |
155 | ipproto = IPPROTO_IP; | |
156 | option_size = sizeof(options); | |
157 | if (getsockopt(socket, ipproto, IP_OPTIONS, (void *)options, | |
158 | &option_size) >= 0 && option_size != 0) { | |
e6fa162e | 159 | text[0] = '\0'; |
160 | for (i = 0; i < option_size; i++) | |
161 | snprintf(text + i*3, sizeof(text) - i*3, | |
162 | " %2.2x", options[i]); | |
61e96248 | 163 | log("Connection from %.100s with IP options:%.800s", |
164 | ipaddr, text); | |
165 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
166 | ipaddr, text); | |
167 | } | |
168 | } | |
169 | ||
aa3378df | 170 | /* |
171 | * Return the canonical name of the host in the other side of the current | |
172 | * connection. The host name is cached, so it is efficient to call this | |
173 | * several times. | |
174 | */ | |
8efc0c15 | 175 | |
5260325f | 176 | const char * |
61e96248 | 177 | get_canonical_hostname(int reverse_mapping_check) |
8efc0c15 | 178 | { |
48e671d5 | 179 | static char *canonical_host_name = NULL; |
61e96248 | 180 | static int reverse_mapping_checked = 0; |
48e671d5 | 181 | |
61e96248 | 182 | /* Check if we have previously retrieved name with same option. */ |
183 | if (canonical_host_name != NULL) { | |
184 | if (reverse_mapping_checked != reverse_mapping_check) | |
185 | xfree(canonical_host_name); | |
186 | else | |
187 | return canonical_host_name; | |
188 | } | |
8efc0c15 | 189 | |
5260325f | 190 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 191 | if (packet_connection_is_on_socket()) |
61e96248 | 192 | canonical_host_name = get_remote_hostname( |
193 | packet_get_connection_in(), reverse_mapping_check); | |
5260325f | 194 | else |
195 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 196 | |
61e96248 | 197 | reverse_mapping_checked = reverse_mapping_check; |
5260325f | 198 | return canonical_host_name; |
8efc0c15 | 199 | } |
200 | ||
aa3378df | 201 | /* |
865ac82e | 202 | * Returns the remote IP-address of socket as a string. The returned |
203 | * string must be freed. | |
aa3378df | 204 | */ |
396c147e | 205 | static char * |
8002af61 | 206 | get_socket_address(int socket, int remote, int flags) |
8efc0c15 | 207 | { |
8002af61 | 208 | struct sockaddr_storage addr; |
209 | socklen_t addrlen; | |
48e671d5 | 210 | char ntop[NI_MAXHOST]; |
5260325f | 211 | |
5260325f | 212 | /* Get IP address of client. */ |
8002af61 | 213 | addrlen = sizeof(addr); |
214 | memset(&addr, 0, sizeof(addr)); | |
215 | ||
216 | if (remote) { | |
217 | if (getpeername(socket, (struct sockaddr *)&addr, &addrlen) | |
218 | < 0) { | |
219 | debug("get_socket_ipaddr: getpeername failed: %.100s", | |
220 | strerror(errno)); | |
221 | return NULL; | |
222 | } | |
223 | } else { | |
224 | if (getsockname(socket, (struct sockaddr *)&addr, &addrlen) | |
225 | < 0) { | |
226 | debug("get_socket_ipaddr: getsockname failed: %.100s", | |
227 | strerror(errno)); | |
228 | return NULL; | |
229 | } | |
5260325f | 230 | } |
8002af61 | 231 | /* Get the address in ascii. */ |
232 | if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop), | |
233 | NULL, 0, flags) != 0) { | |
234 | error("get_socket_ipaddr: getnameinfo %d failed", flags); | |
865ac82e | 235 | return NULL; |
236 | } | |
237 | return xstrdup(ntop); | |
238 | } | |
48e671d5 | 239 | |
8002af61 | 240 | char * |
241 | get_peer_ipaddr(int socket) | |
242 | { | |
243 | return get_socket_address(socket, 1, NI_NUMERICHOST); | |
244 | } | |
245 | ||
246 | char * | |
247 | get_local_ipaddr(int socket) | |
248 | { | |
249 | return get_socket_address(socket, 0, NI_NUMERICHOST); | |
250 | } | |
251 | ||
252 | char * | |
253 | get_local_name(int socket) | |
254 | { | |
255 | return get_socket_address(socket, 0, NI_NAMEREQD); | |
256 | } | |
257 | ||
865ac82e | 258 | /* |
259 | * Returns the IP-address of the remote host as a string. The returned | |
260 | * string must not be freed. | |
261 | */ | |
5260325f | 262 | |
865ac82e | 263 | const char * |
d5bb9418 | 264 | get_remote_ipaddr(void) |
865ac82e | 265 | { |
266 | static char *canonical_host_ip = NULL; | |
267 | ||
268 | /* Check whether we have cached the ipaddr. */ | |
269 | if (canonical_host_ip == NULL) { | |
270 | if (packet_connection_is_on_socket()) { | |
271 | canonical_host_ip = | |
272 | get_peer_ipaddr(packet_get_connection_in()); | |
273 | if (canonical_host_ip == NULL) | |
274 | fatal_cleanup(); | |
275 | } else { | |
276 | /* If not on socket, return UNKNOWN. */ | |
277 | canonical_host_ip = xstrdup("UNKNOWN"); | |
278 | } | |
279 | } | |
5260325f | 280 | return canonical_host_ip; |
8efc0c15 | 281 | } |
282 | ||
46e3af7f | 283 | const char * |
284 | get_remote_name_or_ip(u_int utmp_len, int reverse_mapping_check) | |
285 | { | |
286 | static const char *remote = ""; | |
287 | if (utmp_len > 0) | |
288 | remote = get_canonical_hostname(reverse_mapping_check); | |
289 | if (utmp_len == 0 || strlen(remote) > utmp_len) | |
290 | remote = get_remote_ipaddr(); | |
291 | return remote; | |
292 | } | |
293 | ||
48e671d5 | 294 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 295 | |
396c147e | 296 | static int |
48e671d5 | 297 | get_sock_port(int sock, int local) |
8efc0c15 | 298 | { |
48e671d5 | 299 | struct sockaddr_storage from; |
300 | socklen_t fromlen; | |
301 | char strport[NI_MAXSERV]; | |
5260325f | 302 | |
303 | /* Get IP address of client. */ | |
304 | fromlen = sizeof(from); | |
305 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 306 | if (local) { |
307 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
308 | error("getsockname failed: %.100s", strerror(errno)); | |
309 | return 0; | |
310 | } | |
311 | } else { | |
312 | if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) { | |
313 | debug("getpeername failed: %.100s", strerror(errno)); | |
314 | fatal_cleanup(); | |
315 | } | |
5260325f | 316 | } |
317 | /* Return port number. */ | |
48e671d5 | 318 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
319 | strport, sizeof(strport), NI_NUMERICSERV) != 0) | |
320 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); | |
321 | return atoi(strport); | |
8efc0c15 | 322 | } |
323 | ||
48e671d5 | 324 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 325 | |
396c147e | 326 | static int |
48e671d5 | 327 | get_port(int local) |
8efc0c15 | 328 | { |
aa3378df | 329 | /* |
330 | * If the connection is not a socket, return 65535. This is | |
331 | * intentionally chosen to be an unprivileged port number. | |
332 | */ | |
48e671d5 | 333 | if (!packet_connection_is_on_socket()) |
5260325f | 334 | return 65535; |
8efc0c15 | 335 | |
48e671d5 | 336 | /* Get socket and return the port number. */ |
337 | return get_sock_port(packet_get_connection_in(), local); | |
338 | } | |
339 | ||
6ae2364d | 340 | int |
48e671d5 | 341 | get_peer_port(int sock) |
342 | { | |
343 | return get_sock_port(sock, 0); | |
344 | } | |
8efc0c15 | 345 | |
6ae2364d | 346 | int |
d5bb9418 | 347 | get_remote_port(void) |
48e671d5 | 348 | { |
349 | return get_port(0); | |
350 | } | |
351 | ||
352 | int | |
d5bb9418 | 353 | get_local_port(void) |
48e671d5 | 354 | { |
355 | return get_port(1); | |
8efc0c15 | 356 | } |