Annotation of src/usr.bin/ssh/canohost.c, Revision 1.58
1.58 ! stevesk 1: /* $OpenBSD: canohost.c,v 1.57 2006/07/12 22:28:51 stevesk 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:
15: #include "includes.h"
1.54 stevesk 16:
1.55 stevesk 17: #include <sys/types.h>
1.54 stevesk 18: #include <sys/socket.h>
19:
20: #include <netinet/in.h>
1.49 stevesk 21:
22: #include <ctype.h>
1.56 stevesk 23: #include <errno.h>
1.57 stevesk 24: #include <netdb.h>
1.58 ! stevesk 25: #include <string.h>
1.1 deraadt 26:
27: #include "packet.h"
28: #include "xmalloc.h"
1.18 markus 29: #include "log.h"
1.21 itojun 30: #include "canohost.h"
1.1 deraadt 31:
1.27 itojun 32: static void check_ip_options(int, char *);
1.20 markus 33:
1.8 markus 34: /*
35: * Return the canonical name of the host at the other end of the socket. The
36: * caller should free the returned string with xfree.
37: */
1.1 deraadt 38:
1.27 itojun 39: static char *
1.40 avsm 40: get_remote_hostname(int sock, int use_dns)
1.1 deraadt 41: {
1.10 markus 42: struct sockaddr_storage from;
43: int i;
44: socklen_t fromlen;
45: struct addrinfo hints, *ai, *aitop;
1.20 markus 46: char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
1.6 markus 47:
48: /* Get IP address of client. */
49: fromlen = sizeof(from);
50: memset(&from, 0, sizeof(from));
1.40 avsm 51: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.6 markus 52: debug("getpeername failed: %.100s", strerror(errno));
1.38 markus 53: cleanup_exit(255);
1.6 markus 54: }
1.20 markus 55:
1.10 markus 56: if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
1.29 deraadt 57: NULL, 0, NI_NUMERICHOST) != 0)
1.10 markus 58: fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
1.45 dtucker 59:
60: if (from.ss_family == AF_INET)
61: check_ip_options(sock, ntop);
1.32 itojun 62:
1.37 markus 63: if (!use_dns)
64: return xstrdup(ntop);
1.10 markus 65:
1.26 markus 66: debug3("Trying to reverse map address %.100s.", ntop);
1.6 markus 67: /* Map the IP address to a host name. */
1.10 markus 68: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
1.29 deraadt 69: NULL, 0, NI_NAMEREQD) != 0) {
1.20 markus 70: /* Host name not found. Use ip address. */
71: return xstrdup(ntop);
1.6 markus 72: }
73:
1.37 markus 74: /*
75: * if reverse lookup result looks like a numeric hostname,
76: * someone is trying to trick us by PTR record like following:
77: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
78: */
79: memset(&hints, 0, sizeof(hints));
80: hints.ai_socktype = SOCK_DGRAM; /*dummy*/
81: hints.ai_flags = AI_NUMERICHOST;
82: if (getaddrinfo(name, "0", &hints, &ai) == 0) {
83: logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
84: name, ntop);
85: freeaddrinfo(ai);
86: return xstrdup(ntop);
87: }
88:
1.20 markus 89: /*
90: * Convert it to all lowercase (which is expected by the rest
91: * of this software).
92: */
93: for (i = 0; name[i]; i++)
94: if (isupper(name[i]))
1.52 deraadt 95: name[i] = (char)tolower(name[i]);
1.8 markus 96: /*
1.20 markus 97: * Map it back to an IP address and check that the given
98: * address actually is an address of this host. This is
99: * necessary because anyone with access to a name server can
100: * define arbitrary names for an IP address. Mapping from
101: * name to IP address can be trusted better (but can still be
102: * fooled if the intruder has access to the name server of
103: * the domain).
1.8 markus 104: */
1.20 markus 105: memset(&hints, 0, sizeof(hints));
106: hints.ai_family = from.ss_family;
107: hints.ai_socktype = SOCK_STREAM;
108: if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
1.36 itojun 109: logit("reverse mapping checking getaddrinfo for %.700s "
1.50 djm 110: "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop);
1.20 markus 111: return xstrdup(ntop);
112: }
113: /* Look for the address from the list of addresses. */
114: for (ai = aitop; ai; ai = ai->ai_next) {
115: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
116: sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
117: (strcmp(ntop, ntop2) == 0))
118: break;
119: }
120: freeaddrinfo(aitop);
121: /* If we reached the end of the list, the address was not there. */
122: if (!ai) {
123: /* Address not found for the host name. */
1.36 itojun 124: logit("Address %.100s maps to %.600s, but this does not "
1.48 stevesk 125: "map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
1.20 markus 126: ntop, name);
127: return xstrdup(ntop);
128: }
129: return xstrdup(name);
130: }
1.6 markus 131:
1.20 markus 132: /*
133: * If IP options are supported, make sure there are none (log and
134: * disconnect them if any are found). Basically we are worried about
135: * source routing; it can be used to pretend you are somebody
136: * (ip-address) you are not. That itself may be "almost acceptable"
137: * under certain circumstances, but rhosts autentication is useless
138: * if source routing is accepted. Notice also that if we just dropped
139: * source routing here, the other side could use IP spoofing to do
140: * rest of the interaction and could still bypass security. So we
141: * exit here if we detect any IP options.
142: */
143: /* IPv4 only */
1.27 itojun 144: static void
1.40 avsm 145: check_ip_options(int sock, char *ipaddr)
1.20 markus 146: {
1.22 markus 147: u_char options[200];
148: char text[sizeof(options) * 3 + 1];
1.20 markus 149: socklen_t option_size;
1.44 djm 150: u_int i;
151: int ipproto;
1.20 markus 152: struct protoent *ip;
153:
154: if ((ip = getprotobyname("ip")) != NULL)
155: ipproto = ip->p_proto;
156: else
157: ipproto = IPPROTO_IP;
158: option_size = sizeof(options);
1.40 avsm 159: if (getsockopt(sock, ipproto, IP_OPTIONS, options,
1.20 markus 160: &option_size) >= 0 && option_size != 0) {
1.22 markus 161: text[0] = '\0';
162: for (i = 0; i < option_size; i++)
163: snprintf(text + i*3, sizeof(text) - i*3,
164: " %2.2x", options[i]);
1.46 dtucker 165: fatal("Connection from %.100s with IP options:%.800s",
1.20 markus 166: ipaddr, text);
1.6 markus 167: }
1.1 deraadt 168: }
169:
1.8 markus 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: */
1.1 deraadt 175:
1.6 markus 176: const char *
1.37 markus 177: get_canonical_hostname(int use_dns)
1.1 deraadt 178: {
1.47 dtucker 179: char *host;
1.10 markus 180: static char *canonical_host_name = NULL;
1.47 dtucker 181: static char *remote_ip = NULL;
1.10 markus 182:
1.20 markus 183: /* Check if we have previously retrieved name with same option. */
1.47 dtucker 184: if (use_dns && canonical_host_name != NULL)
185: return canonical_host_name;
186: if (!use_dns && remote_ip != NULL)
187: return remote_ip;
1.6 markus 188:
189: /* Get the real hostname if socket; otherwise return UNKNOWN. */
1.10 markus 190: if (packet_connection_is_on_socket())
1.47 dtucker 191: host = get_remote_hostname(packet_get_connection_in(), use_dns);
1.6 markus 192: else
1.47 dtucker 193: host = "UNKNOWN";
1.1 deraadt 194:
1.47 dtucker 195: if (use_dns)
196: canonical_host_name = host;
197: else
198: remote_ip = host;
199: return host;
1.1 deraadt 200: }
201:
1.8 markus 202: /*
1.35 stevesk 203: * Returns the local/remote IP-address/hostname of socket as a string.
204: * The returned string must be freed.
1.8 markus 205: */
1.27 itojun 206: static char *
1.40 avsm 207: get_socket_address(int sock, int remote, int flags)
1.1 deraadt 208: {
1.25 markus 209: struct sockaddr_storage addr;
210: socklen_t addrlen;
1.10 markus 211: char ntop[NI_MAXHOST];
1.42 djm 212: int r;
1.1 deraadt 213:
1.6 markus 214: /* Get IP address of client. */
1.25 markus 215: addrlen = sizeof(addr);
216: memset(&addr, 0, sizeof(addr));
217:
218: if (remote) {
1.40 avsm 219: if (getpeername(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 220: < 0)
1.25 markus 221: return NULL;
222: } else {
1.40 avsm 223: if (getsockname(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 224: < 0)
1.25 markus 225: return NULL;
226: }
227: /* Get the address in ascii. */
1.42 djm 228: if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
229: sizeof(ntop), NULL, 0, flags)) != 0) {
230: error("get_socket_address: getnameinfo %d failed: %s", flags,
231: r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
1.19 markus 232: return NULL;
233: }
234: return xstrdup(ntop);
1.25 markus 235: }
236:
237: char *
1.40 avsm 238: get_peer_ipaddr(int sock)
1.25 markus 239: {
1.34 stevesk 240: char *p;
241:
1.40 avsm 242: if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL)
1.34 stevesk 243: return p;
244: return xstrdup("UNKNOWN");
1.25 markus 245: }
246:
247: char *
1.40 avsm 248: get_local_ipaddr(int sock)
1.25 markus 249: {
1.34 stevesk 250: char *p;
251:
1.40 avsm 252: if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL)
1.34 stevesk 253: return p;
254: return xstrdup("UNKNOWN");
1.25 markus 255: }
256:
257: char *
1.40 avsm 258: get_local_name(int sock)
1.25 markus 259: {
1.40 avsm 260: return get_socket_address(sock, 0, NI_NAMEREQD);
1.19 markus 261: }
262:
263: /*
264: * Returns the IP-address of the remote host as a string. The returned
265: * string must not be freed.
266: */
1.10 markus 267:
1.19 markus 268: const char *
1.28 itojun 269: get_remote_ipaddr(void)
1.19 markus 270: {
271: static char *canonical_host_ip = NULL;
1.1 deraadt 272:
1.19 markus 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)
1.38 markus 279: cleanup_exit(255);
1.19 markus 280: } else {
281: /* If not on socket, return UNKNOWN. */
282: canonical_host_ip = xstrdup("UNKNOWN");
283: }
284: }
1.6 markus 285: return canonical_host_ip;
1.24 stevesk 286: }
287:
288: const char *
1.37 markus 289: get_remote_name_or_ip(u_int utmp_len, int use_dns)
1.24 stevesk 290: {
291: static const char *remote = "";
292: if (utmp_len > 0)
1.37 markus 293: remote = get_canonical_hostname(use_dns);
1.24 stevesk 294: if (utmp_len == 0 || strlen(remote) > utmp_len)
295: remote = get_remote_ipaddr();
296: return remote;
1.1 deraadt 297: }
298:
1.10 markus 299: /* Returns the local/remote port for the socket. */
1.1 deraadt 300:
1.27 itojun 301: static int
1.10 markus 302: get_sock_port(int sock, int local)
1.1 deraadt 303: {
1.10 markus 304: struct sockaddr_storage from;
305: socklen_t fromlen;
306: char strport[NI_MAXSERV];
1.42 djm 307: int r;
1.1 deraadt 308:
1.6 markus 309: /* Get IP address of client. */
310: fromlen = sizeof(from);
311: memset(&from, 0, sizeof(from));
1.10 markus 312: if (local) {
313: if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
314: error("getsockname failed: %.100s", strerror(errno));
315: return 0;
316: }
317: } else {
1.35 stevesk 318: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.10 markus 319: debug("getpeername failed: %.100s", strerror(errno));
1.43 markus 320: return -1;
1.10 markus 321: }
1.6 markus 322: }
323: /* Return port number. */
1.42 djm 324: if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
325: strport, sizeof(strport), NI_NUMERICSERV)) != 0)
326: fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s",
327: r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
1.10 markus 328: return atoi(strport);
1.1 deraadt 329: }
330:
1.10 markus 331: /* Returns remote/local port number for the current connection. */
1.1 deraadt 332:
1.27 itojun 333: static int
1.10 markus 334: get_port(int local)
1.1 deraadt 335: {
1.8 markus 336: /*
337: * If the connection is not a socket, return 65535. This is
338: * intentionally chosen to be an unprivileged port number.
339: */
1.10 markus 340: if (!packet_connection_is_on_socket())
1.6 markus 341: return 65535;
1.1 deraadt 342:
1.10 markus 343: /* Get socket and return the port number. */
344: return get_sock_port(packet_get_connection_in(), local);
345: }
346:
1.12 markus 347: int
1.10 markus 348: get_peer_port(int sock)
349: {
350: return get_sock_port(sock, 0);
351: }
352:
1.12 markus 353: int
1.28 itojun 354: get_remote_port(void)
1.10 markus 355: {
1.41 djm 356: static int port = -1;
357:
358: /* Cache to avoid getpeername() on a dead connection */
359: if (port == -1)
360: port = get_port(0);
361:
362: return port;
1.10 markus 363: }
1.1 deraadt 364:
1.10 markus 365: int
1.28 itojun 366: get_local_port(void)
1.10 markus 367: {
368: return get_port(1);
1.1 deraadt 369: }
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