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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" | |
5ca51e19 | 15 | RCSID("$OpenBSD: canohost.c,v 1.21 2001/02/08 19:30:51 itojun Exp $"); |
8efc0c15 | 16 | |
17 | #include "packet.h" | |
18 | #include "xmalloc.h" | |
42f11eb2 | 19 | #include "log.h" |
5ca51e19 | 20 | #include "canohost.h" |
8efc0c15 | 21 | |
61e96248 | 22 | void check_ip_options(int socket, char *ipaddr); |
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 | |
5260325f | 29 | 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 | |
48e671d5 | 74 | /* Map the IP address to a host name. */ |
75 | if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), | |
61e96248 | 76 | NULL, 0, NI_NAMEREQD) != 0) { |
77 | /* Host name not found. Use ip address. */ | |
78 | log("Could not reverse map address %.100s.", ntop); | |
79 | return xstrdup(ntop); | |
8efc0c15 | 80 | } |
5260325f | 81 | |
61e96248 | 82 | /* Got host name. */ |
83 | name[sizeof(name) - 1] = '\0'; | |
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]); | |
5260325f | 91 | |
61e96248 | 92 | if (!reverse_mapping_check) |
93 | return xstrdup(name); | |
aa3378df | 94 | /* |
61e96248 | 95 | * Map it back to an IP address and check that the given |
96 | * address actually is an address of this host. This is | |
97 | * necessary because anyone with access to a name server can | |
98 | * define arbitrary names for an IP address. Mapping from | |
99 | * name to IP address can be trusted better (but can still be | |
100 | * fooled if the intruder has access to the name server of | |
101 | * the domain). | |
aa3378df | 102 | */ |
61e96248 | 103 | memset(&hints, 0, sizeof(hints)); |
104 | hints.ai_family = from.ss_family; | |
105 | hints.ai_socktype = SOCK_STREAM; | |
106 | if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { | |
107 | log("reverse mapping checking getaddrinfo for %.700s " | |
108 | "failed - POSSIBLE BREAKIN ATTEMPT!", name); | |
109 | return xstrdup(ntop); | |
110 | } | |
111 | /* Look for the address from the list of addresses. */ | |
112 | for (ai = aitop; ai; ai = ai->ai_next) { | |
113 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, | |
114 | sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && | |
115 | (strcmp(ntop, ntop2) == 0)) | |
116 | break; | |
117 | } | |
118 | freeaddrinfo(aitop); | |
119 | /* If we reached the end of the list, the address was not there. */ | |
120 | if (!ai) { | |
121 | /* Address not found for the host name. */ | |
122 | log("Address %.100s maps to %.600s, but this does not " | |
123 | "map back to the address - POSSIBLE BREAKIN ATTEMPT!", | |
124 | ntop, name); | |
125 | return xstrdup(ntop); | |
8efc0c15 | 126 | } |
5260325f | 127 | return xstrdup(name); |
8efc0c15 | 128 | } |
129 | ||
61e96248 | 130 | /* |
131 | * If IP options are supported, make sure there are none (log and | |
132 | * disconnect them if any are found). Basically we are worried about | |
133 | * source routing; it can be used to pretend you are somebody | |
134 | * (ip-address) you are not. That itself may be "almost acceptable" | |
135 | * under certain circumstances, but rhosts autentication is useless | |
136 | * if source routing is accepted. Notice also that if we just dropped | |
137 | * source routing here, the other side could use IP spoofing to do | |
138 | * rest of the interaction and could still bypass security. So we | |
139 | * exit here if we detect any IP options. | |
140 | */ | |
141 | /* IPv4 only */ | |
142 | void | |
143 | check_ip_options(int socket, char *ipaddr) | |
144 | { | |
145 | u_char options[200], *ucp; | |
146 | char text[1024], *cp; | |
147 | socklen_t option_size; | |
148 | int ipproto; | |
149 | struct protoent *ip; | |
150 | ||
151 | if ((ip = getprotobyname("ip")) != NULL) | |
152 | ipproto = ip->p_proto; | |
153 | else | |
154 | ipproto = IPPROTO_IP; | |
155 | option_size = sizeof(options); | |
156 | if (getsockopt(socket, ipproto, IP_OPTIONS, (void *)options, | |
157 | &option_size) >= 0 && option_size != 0) { | |
158 | cp = text; | |
159 | /* Note: "text" buffer must be at least 3x as big as options. */ | |
160 | for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3) | |
161 | sprintf(cp, " %2.2x", *ucp); | |
162 | log("Connection from %.100s with IP options:%.800s", | |
163 | ipaddr, text); | |
164 | packet_disconnect("Connection from %.100s with IP options:%.800s", | |
165 | ipaddr, text); | |
166 | } | |
167 | } | |
168 | ||
aa3378df | 169 | /* |
170 | * Return the canonical name of the host in the other side of the current | |
171 | * connection. The host name is cached, so it is efficient to call this | |
172 | * several times. | |
173 | */ | |
8efc0c15 | 174 | |
5260325f | 175 | const char * |
61e96248 | 176 | get_canonical_hostname(int reverse_mapping_check) |
8efc0c15 | 177 | { |
48e671d5 | 178 | static char *canonical_host_name = NULL; |
61e96248 | 179 | static int reverse_mapping_checked = 0; |
48e671d5 | 180 | |
61e96248 | 181 | /* Check if we have previously retrieved name with same option. */ |
182 | if (canonical_host_name != NULL) { | |
183 | if (reverse_mapping_checked != reverse_mapping_check) | |
184 | xfree(canonical_host_name); | |
185 | else | |
186 | return canonical_host_name; | |
187 | } | |
8efc0c15 | 188 | |
5260325f | 189 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 190 | if (packet_connection_is_on_socket()) |
61e96248 | 191 | canonical_host_name = get_remote_hostname( |
192 | packet_get_connection_in(), reverse_mapping_check); | |
5260325f | 193 | else |
194 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 195 | |
61e96248 | 196 | reverse_mapping_checked = reverse_mapping_check; |
5260325f | 197 | return canonical_host_name; |
8efc0c15 | 198 | } |
199 | ||
aa3378df | 200 | /* |
865ac82e | 201 | * Returns the remote IP-address of socket as a string. The returned |
202 | * string must be freed. | |
aa3378df | 203 | */ |
8efc0c15 | 204 | |
865ac82e | 205 | char * |
206 | get_peer_ipaddr(int socket) | |
8efc0c15 | 207 | { |
48e671d5 | 208 | struct sockaddr_storage from; |
209 | socklen_t fromlen; | |
48e671d5 | 210 | char ntop[NI_MAXHOST]; |
5260325f | 211 | |
5260325f | 212 | /* Get IP address of client. */ |
213 | fromlen = sizeof(from); | |
214 | memset(&from, 0, sizeof(from)); | |
215 | if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) { | |
865ac82e | 216 | debug("get_peer_ipaddr: getpeername failed: %.100s", strerror(errno)); |
217 | return NULL; | |
5260325f | 218 | } |
219 | /* Get the IP address in ascii. */ | |
48e671d5 | 220 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
865ac82e | 221 | NULL, 0, NI_NUMERICHOST) != 0) { |
222 | error("get_peer_ipaddr: getnameinfo NI_NUMERICHOST failed"); | |
223 | return NULL; | |
224 | } | |
225 | return xstrdup(ntop); | |
226 | } | |
48e671d5 | 227 | |
865ac82e | 228 | /* |
229 | * Returns the IP-address of the remote host as a string. The returned | |
230 | * string must not be freed. | |
231 | */ | |
5260325f | 232 | |
865ac82e | 233 | const char * |
234 | get_remote_ipaddr() | |
235 | { | |
236 | static char *canonical_host_ip = NULL; | |
237 | ||
238 | /* Check whether we have cached the ipaddr. */ | |
239 | if (canonical_host_ip == NULL) { | |
240 | if (packet_connection_is_on_socket()) { | |
241 | canonical_host_ip = | |
242 | get_peer_ipaddr(packet_get_connection_in()); | |
243 | if (canonical_host_ip == NULL) | |
244 | fatal_cleanup(); | |
245 | } else { | |
246 | /* If not on socket, return UNKNOWN. */ | |
247 | canonical_host_ip = xstrdup("UNKNOWN"); | |
248 | } | |
249 | } | |
5260325f | 250 | return canonical_host_ip; |
8efc0c15 | 251 | } |
252 | ||
48e671d5 | 253 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 254 | |
48e671d5 | 255 | int |
256 | get_sock_port(int sock, int local) | |
8efc0c15 | 257 | { |
48e671d5 | 258 | struct sockaddr_storage from; |
259 | socklen_t fromlen; | |
260 | char strport[NI_MAXSERV]; | |
5260325f | 261 | |
262 | /* Get IP address of client. */ | |
263 | fromlen = sizeof(from); | |
264 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 265 | if (local) { |
266 | if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) { | |
267 | error("getsockname failed: %.100s", strerror(errno)); | |
268 | return 0; | |
269 | } | |
270 | } else { | |
271 | if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) { | |
272 | debug("getpeername failed: %.100s", strerror(errno)); | |
273 | fatal_cleanup(); | |
274 | } | |
5260325f | 275 | } |
276 | /* Return port number. */ | |
48e671d5 | 277 | if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, |
278 | strport, sizeof(strport), NI_NUMERICSERV) != 0) | |
279 | fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed"); | |
280 | return atoi(strport); | |
8efc0c15 | 281 | } |
282 | ||
48e671d5 | 283 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 284 | |
6ae2364d | 285 | int |
48e671d5 | 286 | get_port(int local) |
8efc0c15 | 287 | { |
aa3378df | 288 | /* |
289 | * If the connection is not a socket, return 65535. This is | |
290 | * intentionally chosen to be an unprivileged port number. | |
291 | */ | |
48e671d5 | 292 | if (!packet_connection_is_on_socket()) |
5260325f | 293 | return 65535; |
8efc0c15 | 294 | |
48e671d5 | 295 | /* Get socket and return the port number. */ |
296 | return get_sock_port(packet_get_connection_in(), local); | |
297 | } | |
298 | ||
6ae2364d | 299 | int |
48e671d5 | 300 | get_peer_port(int sock) |
301 | { | |
302 | return get_sock_port(sock, 0); | |
303 | } | |
8efc0c15 | 304 | |
6ae2364d | 305 | int |
48e671d5 | 306 | get_remote_port() |
307 | { | |
308 | return get_port(0); | |
309 | } | |
310 | ||
311 | int | |
312 | get_local_port() | |
313 | { | |
314 | return get_port(1); | |
8efc0c15 | 315 | } |