Annotation of src/usr.bin/ssh/canohost.c, Revision 1.48
1.1 deraadt 1: /*
1.7 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Functions for returning the canonical host name of the remote site.
1.12 markus 6: *
1.14 deraadt 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".
1.7 deraadt 12: */
1.1 deraadt 13:
14: #include "includes.h"
1.48 ! stevesk 15: RCSID("$OpenBSD: canohost.c,v 1.47 2005/11/03 13:38:29 dtucker Exp $");
1.1 deraadt 16:
17: #include "packet.h"
18: #include "xmalloc.h"
1.18 markus 19: #include "log.h"
1.21 itojun 20: #include "canohost.h"
1.1 deraadt 21:
1.27 itojun 22: static void check_ip_options(int, char *);
1.20 markus 23:
1.8 markus 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: */
1.1 deraadt 28:
1.27 itojun 29: static char *
1.40 avsm 30: get_remote_hostname(int sock, int use_dns)
1.1 deraadt 31: {
1.10 markus 32: struct sockaddr_storage from;
33: int i;
34: socklen_t fromlen;
35: struct addrinfo hints, *ai, *aitop;
1.20 markus 36: char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
1.6 markus 37:
38: /* Get IP address of client. */
39: fromlen = sizeof(from);
40: memset(&from, 0, sizeof(from));
1.40 avsm 41: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.6 markus 42: debug("getpeername failed: %.100s", strerror(errno));
1.38 markus 43: cleanup_exit(255);
1.6 markus 44: }
1.20 markus 45:
1.10 markus 46: if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
1.29 deraadt 47: NULL, 0, NI_NUMERICHOST) != 0)
1.10 markus 48: fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
1.45 dtucker 49:
50: if (from.ss_family == AF_INET)
51: check_ip_options(sock, ntop);
1.32 itojun 52:
1.37 markus 53: if (!use_dns)
54: return xstrdup(ntop);
1.10 markus 55:
1.26 markus 56: debug3("Trying to reverse map address %.100s.", ntop);
1.6 markus 57: /* Map the IP address to a host name. */
1.10 markus 58: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
1.29 deraadt 59: NULL, 0, NI_NAMEREQD) != 0) {
1.20 markus 60: /* Host name not found. Use ip address. */
61: return xstrdup(ntop);
1.6 markus 62: }
63:
1.37 markus 64: /*
65: * if reverse lookup result looks like a numeric hostname,
66: * someone is trying to trick us by PTR record like following:
67: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
68: */
69: memset(&hints, 0, sizeof(hints));
70: hints.ai_socktype = SOCK_DGRAM; /*dummy*/
71: hints.ai_flags = AI_NUMERICHOST;
72: if (getaddrinfo(name, "0", &hints, &ai) == 0) {
73: logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
74: name, ntop);
75: freeaddrinfo(ai);
76: return xstrdup(ntop);
77: }
78:
1.20 markus 79: /*
80: * Convert it to all lowercase (which is expected by the rest
81: * of this software).
82: */
83: for (i = 0; name[i]; i++)
84: if (isupper(name[i]))
85: name[i] = tolower(name[i]);
1.8 markus 86: /*
1.20 markus 87: * Map it back to an IP address and check that the given
88: * address actually is an address of this host. This is
89: * necessary because anyone with access to a name server can
90: * define arbitrary names for an IP address. Mapping from
91: * name to IP address can be trusted better (but can still be
92: * fooled if the intruder has access to the name server of
93: * the domain).
1.8 markus 94: */
1.20 markus 95: memset(&hints, 0, sizeof(hints));
96: hints.ai_family = from.ss_family;
97: hints.ai_socktype = SOCK_STREAM;
98: if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
1.36 itojun 99: logit("reverse mapping checking getaddrinfo for %.700s "
1.48 ! stevesk 100: "failed - POSSIBLE BREAK-IN ATTEMPT!", name);
1.20 markus 101: return xstrdup(ntop);
102: }
103: /* Look for the address from the list of addresses. */
104: for (ai = aitop; ai; ai = ai->ai_next) {
105: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
106: sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
107: (strcmp(ntop, ntop2) == 0))
108: break;
109: }
110: freeaddrinfo(aitop);
111: /* If we reached the end of the list, the address was not there. */
112: if (!ai) {
113: /* Address not found for the host name. */
1.36 itojun 114: logit("Address %.100s maps to %.600s, but this does not "
1.48 ! stevesk 115: "map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
1.20 markus 116: ntop, name);
117: return xstrdup(ntop);
118: }
119: return xstrdup(name);
120: }
1.6 markus 121:
1.20 markus 122: /*
123: * If IP options are supported, make sure there are none (log and
124: * disconnect them if any are found). Basically we are worried about
125: * source routing; it can be used to pretend you are somebody
126: * (ip-address) you are not. That itself may be "almost acceptable"
127: * under certain circumstances, but rhosts autentication is useless
128: * if source routing is accepted. Notice also that if we just dropped
129: * source routing here, the other side could use IP spoofing to do
130: * rest of the interaction and could still bypass security. So we
131: * exit here if we detect any IP options.
132: */
133: /* IPv4 only */
1.27 itojun 134: static void
1.40 avsm 135: check_ip_options(int sock, char *ipaddr)
1.20 markus 136: {
1.22 markus 137: u_char options[200];
138: char text[sizeof(options) * 3 + 1];
1.20 markus 139: socklen_t option_size;
1.44 djm 140: u_int i;
141: int ipproto;
1.20 markus 142: struct protoent *ip;
143:
144: if ((ip = getprotobyname("ip")) != NULL)
145: ipproto = ip->p_proto;
146: else
147: ipproto = IPPROTO_IP;
148: option_size = sizeof(options);
1.40 avsm 149: if (getsockopt(sock, ipproto, IP_OPTIONS, options,
1.20 markus 150: &option_size) >= 0 && option_size != 0) {
1.22 markus 151: text[0] = '\0';
152: for (i = 0; i < option_size; i++)
153: snprintf(text + i*3, sizeof(text) - i*3,
154: " %2.2x", options[i]);
1.46 dtucker 155: fatal("Connection from %.100s with IP options:%.800s",
1.20 markus 156: ipaddr, text);
1.6 markus 157: }
1.1 deraadt 158: }
159:
1.8 markus 160: /*
161: * Return the canonical name of the host in the other side of the current
162: * connection. The host name is cached, so it is efficient to call this
163: * several times.
164: */
1.1 deraadt 165:
1.6 markus 166: const char *
1.37 markus 167: get_canonical_hostname(int use_dns)
1.1 deraadt 168: {
1.47 dtucker 169: char *host;
1.10 markus 170: static char *canonical_host_name = NULL;
1.47 dtucker 171: static char *remote_ip = NULL;
1.10 markus 172:
1.20 markus 173: /* Check if we have previously retrieved name with same option. */
1.47 dtucker 174: if (use_dns && canonical_host_name != NULL)
175: return canonical_host_name;
176: if (!use_dns && remote_ip != NULL)
177: return remote_ip;
1.6 markus 178:
179: /* Get the real hostname if socket; otherwise return UNKNOWN. */
1.10 markus 180: if (packet_connection_is_on_socket())
1.47 dtucker 181: host = get_remote_hostname(packet_get_connection_in(), use_dns);
1.6 markus 182: else
1.47 dtucker 183: host = "UNKNOWN";
1.1 deraadt 184:
1.47 dtucker 185: if (use_dns)
186: canonical_host_name = host;
187: else
188: remote_ip = host;
189: return host;
1.1 deraadt 190: }
191:
1.8 markus 192: /*
1.35 stevesk 193: * Returns the local/remote IP-address/hostname of socket as a string.
194: * The returned string must be freed.
1.8 markus 195: */
1.27 itojun 196: static char *
1.40 avsm 197: get_socket_address(int sock, int remote, int flags)
1.1 deraadt 198: {
1.25 markus 199: struct sockaddr_storage addr;
200: socklen_t addrlen;
1.10 markus 201: char ntop[NI_MAXHOST];
1.42 djm 202: int r;
1.1 deraadt 203:
1.6 markus 204: /* Get IP address of client. */
1.25 markus 205: addrlen = sizeof(addr);
206: memset(&addr, 0, sizeof(addr));
207:
208: if (remote) {
1.40 avsm 209: if (getpeername(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 210: < 0)
1.25 markus 211: return NULL;
212: } else {
1.40 avsm 213: if (getsockname(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 214: < 0)
1.25 markus 215: return NULL;
216: }
217: /* Get the address in ascii. */
1.42 djm 218: if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
219: sizeof(ntop), NULL, 0, flags)) != 0) {
220: error("get_socket_address: getnameinfo %d failed: %s", flags,
221: r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
1.19 markus 222: return NULL;
223: }
224: return xstrdup(ntop);
1.25 markus 225: }
226:
227: char *
1.40 avsm 228: get_peer_ipaddr(int sock)
1.25 markus 229: {
1.34 stevesk 230: char *p;
231:
1.40 avsm 232: if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL)
1.34 stevesk 233: return p;
234: return xstrdup("UNKNOWN");
1.25 markus 235: }
236:
237: char *
1.40 avsm 238: get_local_ipaddr(int sock)
1.25 markus 239: {
1.34 stevesk 240: char *p;
241:
1.40 avsm 242: if ((p = get_socket_address(sock, 0, 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_name(int sock)
1.25 markus 249: {
1.40 avsm 250: return get_socket_address(sock, 0, NI_NAMEREQD);
1.19 markus 251: }
252:
253: /*
254: * Returns the IP-address of the remote host as a string. The returned
255: * string must not be freed.
256: */
1.10 markus 257:
1.19 markus 258: const char *
1.28 itojun 259: get_remote_ipaddr(void)
1.19 markus 260: {
261: static char *canonical_host_ip = NULL;
1.1 deraadt 262:
1.19 markus 263: /* Check whether we have cached the ipaddr. */
264: if (canonical_host_ip == NULL) {
265: if (packet_connection_is_on_socket()) {
266: canonical_host_ip =
267: get_peer_ipaddr(packet_get_connection_in());
268: if (canonical_host_ip == NULL)
1.38 markus 269: cleanup_exit(255);
1.19 markus 270: } else {
271: /* If not on socket, return UNKNOWN. */
272: canonical_host_ip = xstrdup("UNKNOWN");
273: }
274: }
1.6 markus 275: return canonical_host_ip;
1.24 stevesk 276: }
277:
278: const char *
1.37 markus 279: get_remote_name_or_ip(u_int utmp_len, int use_dns)
1.24 stevesk 280: {
281: static const char *remote = "";
282: if (utmp_len > 0)
1.37 markus 283: remote = get_canonical_hostname(use_dns);
1.24 stevesk 284: if (utmp_len == 0 || strlen(remote) > utmp_len)
285: remote = get_remote_ipaddr();
286: return remote;
1.1 deraadt 287: }
288:
1.10 markus 289: /* Returns the local/remote port for the socket. */
1.1 deraadt 290:
1.27 itojun 291: static int
1.10 markus 292: get_sock_port(int sock, int local)
1.1 deraadt 293: {
1.10 markus 294: struct sockaddr_storage from;
295: socklen_t fromlen;
296: char strport[NI_MAXSERV];
1.42 djm 297: int r;
1.1 deraadt 298:
1.6 markus 299: /* Get IP address of client. */
300: fromlen = sizeof(from);
301: memset(&from, 0, sizeof(from));
1.10 markus 302: if (local) {
303: if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
304: error("getsockname failed: %.100s", strerror(errno));
305: return 0;
306: }
307: } else {
1.35 stevesk 308: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.10 markus 309: debug("getpeername failed: %.100s", strerror(errno));
1.43 markus 310: return -1;
1.10 markus 311: }
1.6 markus 312: }
313: /* Return port number. */
1.42 djm 314: if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
315: strport, sizeof(strport), NI_NUMERICSERV)) != 0)
316: fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s",
317: r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
1.10 markus 318: return atoi(strport);
1.1 deraadt 319: }
320:
1.10 markus 321: /* Returns remote/local port number for the current connection. */
1.1 deraadt 322:
1.27 itojun 323: static int
1.10 markus 324: get_port(int local)
1.1 deraadt 325: {
1.8 markus 326: /*
327: * If the connection is not a socket, return 65535. This is
328: * intentionally chosen to be an unprivileged port number.
329: */
1.10 markus 330: if (!packet_connection_is_on_socket())
1.6 markus 331: return 65535;
1.1 deraadt 332:
1.10 markus 333: /* Get socket and return the port number. */
334: return get_sock_port(packet_get_connection_in(), local);
335: }
336:
1.12 markus 337: int
1.10 markus 338: get_peer_port(int sock)
339: {
340: return get_sock_port(sock, 0);
341: }
342:
1.12 markus 343: int
1.28 itojun 344: get_remote_port(void)
1.10 markus 345: {
1.41 djm 346: static int port = -1;
347:
348: /* Cache to avoid getpeername() on a dead connection */
349: if (port == -1)
350: port = get_port(0);
351:
352: return port;
1.10 markus 353: }
1.1 deraadt 354:
1.10 markus 355: int
1.28 itojun 356: get_local_port(void)
1.10 markus 357: {
358: return get_port(1);
1.1 deraadt 359: }
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