Annotation of src/usr.bin/ssh/canohost.c, Revision 1.70
1.70 ! dtucker 1: /* $OpenBSD: canohost.c,v 1.69 2013/11/20 20:54:10 deraadt Exp $ */
1.1 deraadt 2: /*
1.7 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Functions for returning the canonical host name of the remote site.
1.12 markus 7: *
1.14 deraadt 8: * As far as I am concerned, the code I have written for this software
9: * can be used freely for any purpose. Any derived versions of this
10: * software must be clearly marked as such, and if the derived work is
11: * incompatible with the protocol description in the RFC file, it must be
12: * called by a name other than "ssh" or "Secure Shell".
1.7 deraadt 13: */
1.1 deraadt 14:
1.55 stevesk 15: #include <sys/types.h>
1.54 stevesk 16: #include <sys/socket.h>
17:
18: #include <netinet/in.h>
1.49 stevesk 19:
1.56 stevesk 20: #include <errno.h>
1.57 stevesk 21: #include <netdb.h>
1.60 stevesk 22: #include <stdio.h>
1.59 stevesk 23: #include <stdlib.h>
1.58 stevesk 24: #include <string.h>
1.61 deraadt 25: #include <stdarg.h>
1.66 dtucker 26: #include <unistd.h>
1.1 deraadt 27:
1.61 deraadt 28: #include "xmalloc.h"
1.1 deraadt 29: #include "packet.h"
1.18 markus 30: #include "log.h"
1.21 itojun 31: #include "canohost.h"
1.62 dtucker 32: #include "misc.h"
1.1 deraadt 33:
1.27 itojun 34: static void check_ip_options(int, char *);
1.65 andreas 35: static char *canonical_host_ip = NULL;
36: static int cached_port = -1;
1.20 markus 37:
1.8 markus 38: /*
39: * Return the canonical name of the host at the other end of the socket. The
1.67 djm 40: * caller should free the returned string.
1.8 markus 41: */
1.1 deraadt 42:
1.27 itojun 43: static char *
1.40 avsm 44: get_remote_hostname(int sock, int use_dns)
1.1 deraadt 45: {
1.10 markus 46: struct sockaddr_storage from;
47: socklen_t fromlen;
48: struct addrinfo hints, *ai, *aitop;
1.20 markus 49: char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
1.6 markus 50:
51: /* Get IP address of client. */
52: fromlen = sizeof(from);
53: memset(&from, 0, sizeof(from));
1.40 avsm 54: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.6 markus 55: debug("getpeername failed: %.100s", strerror(errno));
1.38 markus 56: cleanup_exit(255);
1.6 markus 57: }
1.20 markus 58:
1.10 markus 59: if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
1.29 deraadt 60: NULL, 0, NI_NUMERICHOST) != 0)
1.10 markus 61: fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
1.45 dtucker 62:
63: if (from.ss_family == AF_INET)
64: check_ip_options(sock, ntop);
1.32 itojun 65:
1.37 markus 66: if (!use_dns)
67: return xstrdup(ntop);
1.10 markus 68:
1.26 markus 69: debug3("Trying to reverse map address %.100s.", ntop);
1.6 markus 70: /* Map the IP address to a host name. */
1.10 markus 71: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
1.29 deraadt 72: NULL, 0, NI_NAMEREQD) != 0) {
1.20 markus 73: /* Host name not found. Use ip address. */
74: return xstrdup(ntop);
1.6 markus 75: }
76:
1.37 markus 77: /*
78: * if reverse lookup result looks like a numeric hostname,
79: * someone is trying to trick us by PTR record like following:
80: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
81: */
82: memset(&hints, 0, sizeof(hints));
83: hints.ai_socktype = SOCK_DGRAM; /*dummy*/
84: hints.ai_flags = AI_NUMERICHOST;
1.63 dtucker 85: if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
1.37 markus 86: logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
87: name, ntop);
88: freeaddrinfo(ai);
89: return xstrdup(ntop);
90: }
91:
1.68 djm 92: /* Names are stores in lowercase. */
93: lowercase(name);
94:
1.8 markus 95: /*
1.20 markus 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).
1.8 markus 103: */
1.20 markus 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) {
1.36 itojun 108: logit("reverse mapping checking getaddrinfo for %.700s "
1.50 djm 109: "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop);
1.20 markus 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. */
1.36 itojun 123: logit("Address %.100s maps to %.600s, but this does not "
1.48 stevesk 124: "map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
1.20 markus 125: ntop, name);
126: return xstrdup(ntop);
127: }
128: return xstrdup(name);
129: }
1.6 markus 130:
1.20 markus 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 */
1.27 itojun 143: static void
1.40 avsm 144: check_ip_options(int sock, char *ipaddr)
1.20 markus 145: {
1.22 markus 146: u_char options[200];
147: char text[sizeof(options) * 3 + 1];
1.70 ! dtucker 148: socklen_t option_size, i;
1.44 djm 149: int ipproto;
1.20 markus 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);
1.40 avsm 157: if (getsockopt(sock, ipproto, IP_OPTIONS, options,
1.20 markus 158: &option_size) >= 0 && option_size != 0) {
1.22 markus 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]);
1.46 dtucker 163: fatal("Connection from %.100s with IP options:%.800s",
1.20 markus 164: ipaddr, text);
1.6 markus 165: }
1.1 deraadt 166: }
167:
1.8 markus 168: /*
169: * Return the canonical name of the host in the other side of the current
170: * connection. The host name is cached, so it is efficient to call this
171: * several times.
172: */
1.1 deraadt 173:
1.6 markus 174: const char *
1.37 markus 175: get_canonical_hostname(int use_dns)
1.1 deraadt 176: {
1.47 dtucker 177: char *host;
1.10 markus 178: static char *canonical_host_name = NULL;
1.47 dtucker 179: static char *remote_ip = NULL;
1.10 markus 180:
1.20 markus 181: /* Check if we have previously retrieved name with same option. */
1.47 dtucker 182: if (use_dns && canonical_host_name != NULL)
183: return canonical_host_name;
184: if (!use_dns && remote_ip != NULL)
185: return remote_ip;
1.6 markus 186:
187: /* Get the real hostname if socket; otherwise return UNKNOWN. */
1.10 markus 188: if (packet_connection_is_on_socket())
1.47 dtucker 189: host = get_remote_hostname(packet_get_connection_in(), use_dns);
1.6 markus 190: else
1.47 dtucker 191: host = "UNKNOWN";
1.1 deraadt 192:
1.47 dtucker 193: if (use_dns)
194: canonical_host_name = host;
195: else
196: remote_ip = host;
197: return host;
1.1 deraadt 198: }
199:
1.8 markus 200: /*
1.35 stevesk 201: * Returns the local/remote IP-address/hostname of socket as a string.
202: * The returned string must be freed.
1.8 markus 203: */
1.27 itojun 204: static char *
1.40 avsm 205: get_socket_address(int sock, int remote, int flags)
1.1 deraadt 206: {
1.25 markus 207: struct sockaddr_storage addr;
208: socklen_t addrlen;
1.10 markus 209: char ntop[NI_MAXHOST];
1.42 djm 210: int r;
1.1 deraadt 211:
1.6 markus 212: /* Get IP address of client. */
1.25 markus 213: addrlen = sizeof(addr);
214: memset(&addr, 0, sizeof(addr));
215:
216: if (remote) {
1.40 avsm 217: if (getpeername(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 218: < 0)
1.25 markus 219: return NULL;
220: } else {
1.40 avsm 221: if (getsockname(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 222: < 0)
1.25 markus 223: return NULL;
224: }
225: /* Get the address in ascii. */
1.42 djm 226: if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
227: sizeof(ntop), NULL, 0, flags)) != 0) {
228: error("get_socket_address: getnameinfo %d failed: %s", flags,
1.62 dtucker 229: ssh_gai_strerror(r));
1.19 markus 230: return NULL;
231: }
232: return xstrdup(ntop);
1.25 markus 233: }
234:
235: char *
1.40 avsm 236: get_peer_ipaddr(int sock)
1.25 markus 237: {
1.34 stevesk 238: char *p;
239:
1.40 avsm 240: if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL)
1.34 stevesk 241: return p;
242: return xstrdup("UNKNOWN");
1.25 markus 243: }
244:
245: char *
1.40 avsm 246: get_local_ipaddr(int sock)
1.25 markus 247: {
1.34 stevesk 248: char *p;
249:
1.40 avsm 250: if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL)
1.34 stevesk 251: return p;
252: return xstrdup("UNKNOWN");
1.25 markus 253: }
254:
255: char *
1.66 dtucker 256: get_local_name(int fd)
1.25 markus 257: {
1.66 dtucker 258: char *host, myname[NI_MAXHOST];
259:
260: /* Assume we were passed a socket */
261: if ((host = get_socket_address(fd, 0, NI_NAMEREQD)) != NULL)
262: return host;
263:
264: /* Handle the case where we were passed a pipe */
265: if (gethostname(myname, sizeof(myname)) == -1) {
266: verbose("get_local_name: gethostname: %s", strerror(errno));
267: } else {
268: host = xstrdup(myname);
269: }
270:
271: return host;
1.19 markus 272: }
273:
1.65 andreas 274: void
275: clear_cached_addr(void)
276: {
1.67 djm 277: free(canonical_host_ip);
278: canonical_host_ip = NULL;
1.65 andreas 279: cached_port = -1;
280: }
281:
1.19 markus 282: /*
283: * Returns the IP-address of the remote host as a string. The returned
284: * string must not be freed.
285: */
1.10 markus 286:
1.19 markus 287: const char *
1.28 itojun 288: get_remote_ipaddr(void)
1.19 markus 289: {
290: /* Check whether we have cached the ipaddr. */
291: if (canonical_host_ip == NULL) {
292: if (packet_connection_is_on_socket()) {
293: canonical_host_ip =
294: get_peer_ipaddr(packet_get_connection_in());
295: if (canonical_host_ip == NULL)
1.38 markus 296: cleanup_exit(255);
1.19 markus 297: } else {
298: /* If not on socket, return UNKNOWN. */
299: canonical_host_ip = xstrdup("UNKNOWN");
300: }
301: }
1.6 markus 302: return canonical_host_ip;
1.24 stevesk 303: }
304:
305: const char *
1.37 markus 306: get_remote_name_or_ip(u_int utmp_len, int use_dns)
1.24 stevesk 307: {
308: static const char *remote = "";
309: if (utmp_len > 0)
1.37 markus 310: remote = get_canonical_hostname(use_dns);
1.24 stevesk 311: if (utmp_len == 0 || strlen(remote) > utmp_len)
312: remote = get_remote_ipaddr();
313: return remote;
1.1 deraadt 314: }
315:
1.10 markus 316: /* Returns the local/remote port for the socket. */
1.1 deraadt 317:
1.64 djm 318: int
1.10 markus 319: get_sock_port(int sock, int local)
1.1 deraadt 320: {
1.10 markus 321: struct sockaddr_storage from;
322: socklen_t fromlen;
323: char strport[NI_MAXSERV];
1.42 djm 324: int r;
1.1 deraadt 325:
1.6 markus 326: /* Get IP address of client. */
327: fromlen = sizeof(from);
328: memset(&from, 0, sizeof(from));
1.10 markus 329: if (local) {
330: if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
331: error("getsockname failed: %.100s", strerror(errno));
332: return 0;
333: }
334: } else {
1.35 stevesk 335: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.10 markus 336: debug("getpeername failed: %.100s", strerror(errno));
1.43 markus 337: return -1;
1.10 markus 338: }
1.6 markus 339: }
340: /* Return port number. */
1.42 djm 341: if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
342: strport, sizeof(strport), NI_NUMERICSERV)) != 0)
343: fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s",
1.62 dtucker 344: ssh_gai_strerror(r));
1.10 markus 345: return atoi(strport);
1.1 deraadt 346: }
347:
1.10 markus 348: /* Returns remote/local port number for the current connection. */
1.1 deraadt 349:
1.27 itojun 350: static int
1.10 markus 351: get_port(int local)
1.1 deraadt 352: {
1.8 markus 353: /*
354: * If the connection is not a socket, return 65535. This is
355: * intentionally chosen to be an unprivileged port number.
356: */
1.10 markus 357: if (!packet_connection_is_on_socket())
1.6 markus 358: return 65535;
1.1 deraadt 359:
1.10 markus 360: /* Get socket and return the port number. */
361: return get_sock_port(packet_get_connection_in(), local);
362: }
363:
1.12 markus 364: int
1.10 markus 365: get_peer_port(int sock)
366: {
367: return get_sock_port(sock, 0);
368: }
369:
1.12 markus 370: int
1.28 itojun 371: get_remote_port(void)
1.10 markus 372: {
1.41 djm 373: /* Cache to avoid getpeername() on a dead connection */
1.65 andreas 374: if (cached_port == -1)
375: cached_port = get_port(0);
1.41 djm 376:
1.65 andreas 377: return cached_port;
1.10 markus 378: }
1.1 deraadt 379:
1.10 markus 380: int
1.28 itojun 381: get_local_port(void)
1.10 markus 382: {
383: return get_port(1);
1.1 deraadt 384: }
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