Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 1 | /* |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 2 | * |
| 3 | * canohost.c |
| 4 | * |
| 5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 6 | * |
| 7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 8 | * All rights reserved |
| 9 | * |
| 10 | * Created: Sun Jul 2 17:52:22 1995 ylo |
| 11 | * |
| 12 | * Functions for returning the canonical host name of the remote site. |
| 13 | * |
| 14 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 15 | |
| 16 | #include "includes.h" |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 17 | RCSID("$Id: canohost.c,v 1.4 1999/11/25 00:54:58 damien Exp $"); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 18 | |
| 19 | #include "packet.h" |
| 20 | #include "xmalloc.h" |
| 21 | #include "ssh.h" |
| 22 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 23 | /* |
| 24 | * Return the canonical name of the host at the other end of the socket. The |
| 25 | * caller should free the returned string with xfree. |
| 26 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 27 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 28 | char * |
| 29 | get_remote_hostname(int socket) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 30 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 31 | struct sockaddr_in from; |
| 32 | int fromlen, i; |
| 33 | struct hostent *hp; |
| 34 | char name[MAXHOSTNAMELEN]; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 35 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 36 | /* Get IP address of client. */ |
| 37 | fromlen = sizeof(from); |
| 38 | memset(&from, 0, sizeof(from)); |
| 39 | if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) { |
| 40 | debug("getpeername failed: %.100s", strerror(errno)); |
| 41 | fatal_cleanup(); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 42 | } |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 43 | /* Map the IP address to a host name. */ |
| 44 | hp = gethostbyaddr((char *) &from.sin_addr, sizeof(struct in_addr), |
| 45 | from.sin_family); |
| 46 | if (hp) { |
| 47 | /* Got host name, find canonic host name. */ |
| 48 | if (strchr(hp->h_name, '.') != 0) |
| 49 | strlcpy(name, hp->h_name, sizeof(name)); |
| 50 | else if (hp->h_aliases != 0 |
| 51 | && hp->h_aliases[0] != 0 |
| 52 | && strchr(hp->h_aliases[0], '.') != 0) |
| 53 | strlcpy(name, hp->h_aliases[0], sizeof(name)); |
| 54 | else |
| 55 | strlcpy(name, hp->h_name, sizeof(name)); |
| 56 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 57 | /* |
| 58 | * Convert it to all lowercase (which is expected by the rest |
| 59 | * of this software). |
| 60 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 61 | for (i = 0; name[i]; i++) |
| 62 | if (isupper(name[i])) |
| 63 | name[i] = tolower(name[i]); |
| 64 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 65 | /* |
| 66 | * Map it back to an IP address and check that the given |
| 67 | * address actually is an address of this host. This is |
| 68 | * necessary because anyone with access to a name server can |
| 69 | * define arbitrary names for an IP address. Mapping from |
| 70 | * name to IP address can be trusted better (but can still be |
| 71 | * fooled if the intruder has access to the name server of |
| 72 | * the domain). |
| 73 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 74 | hp = gethostbyname(name); |
| 75 | if (!hp) { |
| 76 | log("reverse mapping checking gethostbyname for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name); |
| 77 | strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); |
| 78 | goto check_ip_options; |
| 79 | } |
| 80 | /* Look for the address from the list of addresses. */ |
| 81 | for (i = 0; hp->h_addr_list[i]; i++) |
| 82 | if (memcmp(hp->h_addr_list[i], &from.sin_addr, sizeof(from.sin_addr)) |
| 83 | == 0) |
| 84 | break; |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 85 | /* |
| 86 | * If we reached the end of the list, the address was not |
| 87 | * there. |
| 88 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 89 | if (!hp->h_addr_list[i]) { |
| 90 | /* Address not found for the host name. */ |
| 91 | log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!", |
| 92 | inet_ntoa(from.sin_addr), name); |
| 93 | strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); |
| 94 | goto check_ip_options; |
| 95 | } |
| 96 | /* Address was found for the host name. We accept the host name. */ |
| 97 | } else { |
| 98 | /* Host name not found. Use ascii representation of the address. */ |
| 99 | strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); |
| 100 | log("Could not reverse map address %.100s.", name); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 101 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 102 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 103 | check_ip_options: |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 104 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 105 | /* |
| 106 | * If IP options are supported, make sure there are none (log and |
| 107 | * disconnect them if any are found). Basically we are worried about |
| 108 | * source routing; it can be used to pretend you are somebody |
| 109 | * (ip-address) you are not. That itself may be "almost acceptable" |
| 110 | * under certain circumstances, but rhosts autentication is useless |
| 111 | * if source routing is accepted. Notice also that if we just dropped |
| 112 | * source routing here, the other side could use IP spoofing to do |
| 113 | * rest of the interaction and could still bypass security. So we |
| 114 | * exit here if we detect any IP options. |
| 115 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 116 | { |
| 117 | unsigned char options[200], *ucp; |
| 118 | char text[1024], *cp; |
| 119 | int option_size, ipproto; |
| 120 | struct protoent *ip; |
| 121 | |
| 122 | if ((ip = getprotobyname("ip")) != NULL) |
| 123 | ipproto = ip->p_proto; |
| 124 | else |
| 125 | ipproto = IPPROTO_IP; |
| 126 | option_size = sizeof(options); |
| 127 | if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options, |
| 128 | &option_size) >= 0 && option_size != 0) { |
| 129 | cp = text; |
| 130 | /* Note: "text" buffer must be at least 3x as big as options. */ |
| 131 | for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3) |
| 132 | sprintf(cp, " %2.2x", *ucp); |
| 133 | log("Connection from %.100s with IP options:%.800s", |
| 134 | inet_ntoa(from.sin_addr), text); |
| 135 | packet_disconnect("Connection from %.100s with IP options:%.800s", |
| 136 | inet_ntoa(from.sin_addr), text); |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | return xstrdup(name); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 141 | } |
| 142 | |
| 143 | static char *canonical_host_name = NULL; |
| 144 | static char *canonical_host_ip = NULL; |
| 145 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 146 | /* |
| 147 | * Return the canonical name of the host in the other side of the current |
| 148 | * connection. The host name is cached, so it is efficient to call this |
| 149 | * several times. |
| 150 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 151 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 152 | const char * |
| 153 | get_canonical_hostname() |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 154 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 155 | /* Check if we have previously retrieved this same name. */ |
| 156 | if (canonical_host_name != NULL) |
| 157 | return canonical_host_name; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 158 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 159 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
| 160 | if (packet_get_connection_in() == packet_get_connection_out()) |
| 161 | canonical_host_name = get_remote_hostname(packet_get_connection_in()); |
| 162 | else |
| 163 | canonical_host_name = xstrdup("UNKNOWN"); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 164 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 165 | return canonical_host_name; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 166 | } |
| 167 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 168 | /* |
| 169 | * Returns the IP-address of the remote host as a string. The returned |
| 170 | * string need not be freed. |
| 171 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 172 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 173 | const char * |
| 174 | get_remote_ipaddr() |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 175 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 176 | struct sockaddr_in from; |
| 177 | int fromlen, socket; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 178 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 179 | /* Check whether we have chached the name. */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 180 | if (canonical_host_ip != NULL) |
| 181 | return canonical_host_ip; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 182 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 183 | /* If not a socket, return UNKNOWN. */ |
| 184 | if (packet_get_connection_in() != packet_get_connection_out()) { |
| 185 | canonical_host_ip = xstrdup("UNKNOWN"); |
| 186 | return canonical_host_ip; |
| 187 | } |
| 188 | /* Get client socket. */ |
| 189 | socket = packet_get_connection_in(); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 190 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 191 | /* Get IP address of client. */ |
| 192 | fromlen = sizeof(from); |
| 193 | memset(&from, 0, sizeof(from)); |
| 194 | if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) { |
| 195 | debug("getpeername failed: %.100s", strerror(errno)); |
| 196 | fatal_cleanup(); |
| 197 | } |
| 198 | /* Get the IP address in ascii. */ |
| 199 | canonical_host_ip = xstrdup(inet_ntoa(from.sin_addr)); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 200 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 201 | /* Return ip address string. */ |
| 202 | return canonical_host_ip; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 203 | } |
| 204 | |
| 205 | /* Returns the port of the peer of the socket. */ |
| 206 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 207 | int |
| 208 | get_peer_port(int sock) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 209 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 210 | struct sockaddr_in from; |
| 211 | int fromlen; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 212 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 213 | /* Get IP address of client. */ |
| 214 | fromlen = sizeof(from); |
| 215 | memset(&from, 0, sizeof(from)); |
| 216 | if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) { |
| 217 | debug("getpeername failed: %.100s", strerror(errno)); |
| 218 | fatal_cleanup(); |
| 219 | } |
| 220 | /* Return port number. */ |
| 221 | return ntohs(from.sin_port); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 222 | } |
| 223 | |
| 224 | /* Returns the port number of the remote host. */ |
| 225 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 226 | int |
| 227 | get_remote_port() |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 228 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 229 | int socket; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 230 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame^] | 231 | /* |
| 232 | * If the connection is not a socket, return 65535. This is |
| 233 | * intentionally chosen to be an unprivileged port number. |
| 234 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 235 | if (packet_get_connection_in() != packet_get_connection_out()) |
| 236 | return 65535; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 237 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 238 | /* Get client socket. */ |
| 239 | socket = packet_get_connection_in(); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 240 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 241 | /* Get and return the peer port number. */ |
| 242 | return get_peer_port(socket); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 243 | } |