Annotation of src/usr.bin/ssh/canohost.c, Revision 1.38
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"
1.38 ! markus 15: RCSID("$OpenBSD: canohost.c,v 1.37 2003/06/02 09:17:34 markus 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 *
1.37 markus 30: get_remote_hostname(int socket, 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));
1.35 stevesk 41: if (getpeername(socket, (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");
1.32 itojun 49:
1.37 markus 50: if (!use_dns)
51: return xstrdup(ntop);
52:
1.32 itojun 53: if (from.ss_family == AF_INET)
54: check_ip_options(socket, 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 "
1.20 markus 100: "failed - POSSIBLE BREAKIN ATTEMPT!", name);
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 "
1.20 markus 115: "map back to the address - POSSIBLE BREAKIN ATTEMPT!",
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
1.20 markus 135: check_ip_options(int socket, char *ipaddr)
136: {
1.22 markus 137: u_char options[200];
138: char text[sizeof(options) * 3 + 1];
1.20 markus 139: socklen_t option_size;
1.22 markus 140: int i, ipproto;
1.20 markus 141: struct protoent *ip;
142:
143: if ((ip = getprotobyname("ip")) != NULL)
144: ipproto = ip->p_proto;
145: else
146: ipproto = IPPROTO_IP;
147: option_size = sizeof(options);
1.31 stevesk 148: if (getsockopt(socket, ipproto, IP_OPTIONS, options,
1.20 markus 149: &option_size) >= 0 && option_size != 0) {
1.22 markus 150: text[0] = '\0';
151: for (i = 0; i < option_size; i++)
152: snprintf(text + i*3, sizeof(text) - i*3,
153: " %2.2x", options[i]);
1.36 itojun 154: logit("Connection from %.100s with IP options:%.800s",
1.20 markus 155: ipaddr, text);
156: packet_disconnect("Connection from %.100s with IP options:%.800s",
157: ipaddr, text);
1.6 markus 158: }
1.1 deraadt 159: }
160:
1.8 markus 161: /*
162: * Return the canonical name of the host in the other side of the current
163: * connection. The host name is cached, so it is efficient to call this
164: * several times.
165: */
1.1 deraadt 166:
1.6 markus 167: const char *
1.37 markus 168: get_canonical_hostname(int use_dns)
1.1 deraadt 169: {
1.10 markus 170: static char *canonical_host_name = NULL;
1.37 markus 171: static int use_dns_done = 0;
1.10 markus 172:
1.20 markus 173: /* Check if we have previously retrieved name with same option. */
174: if (canonical_host_name != NULL) {
1.37 markus 175: if (use_dns_done != use_dns)
1.20 markus 176: xfree(canonical_host_name);
177: else
178: return canonical_host_name;
179: }
1.6 markus 180:
181: /* Get the real hostname if socket; otherwise return UNKNOWN. */
1.10 markus 182: if (packet_connection_is_on_socket())
1.20 markus 183: canonical_host_name = get_remote_hostname(
1.37 markus 184: packet_get_connection_in(), use_dns);
1.6 markus 185: else
186: canonical_host_name = xstrdup("UNKNOWN");
1.1 deraadt 187:
1.37 markus 188: use_dns_done = use_dns;
1.6 markus 189: return canonical_host_name;
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 *
1.25 markus 197: get_socket_address(int socket, 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];
1.1 deraadt 202:
1.6 markus 203: /* Get IP address of client. */
1.25 markus 204: addrlen = sizeof(addr);
205: memset(&addr, 0, sizeof(addr));
206:
207: if (remote) {
208: if (getpeername(socket, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 209: < 0)
1.25 markus 210: return NULL;
211: } else {
212: if (getsockname(socket, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 213: < 0)
1.25 markus 214: return NULL;
215: }
216: /* Get the address in ascii. */
217: if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop),
1.29 deraadt 218: NULL, 0, flags) != 0) {
1.35 stevesk 219: error("get_socket_address: getnameinfo %d failed", flags);
1.19 markus 220: return NULL;
221: }
222: return xstrdup(ntop);
1.25 markus 223: }
224:
225: char *
226: get_peer_ipaddr(int socket)
227: {
1.34 stevesk 228: char *p;
229:
230: if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL)
231: return p;
232: return xstrdup("UNKNOWN");
1.25 markus 233: }
234:
235: char *
236: get_local_ipaddr(int socket)
237: {
1.34 stevesk 238: char *p;
239:
240: if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL)
241: return p;
242: return xstrdup("UNKNOWN");
1.25 markus 243: }
244:
245: char *
246: get_local_name(int socket)
247: {
248: return get_socket_address(socket, 0, NI_NAMEREQD);
1.19 markus 249: }
250:
251: /*
252: * Returns the IP-address of the remote host as a string. The returned
253: * string must not be freed.
254: */
1.10 markus 255:
1.19 markus 256: const char *
1.28 itojun 257: get_remote_ipaddr(void)
1.19 markus 258: {
259: static char *canonical_host_ip = NULL;
1.1 deraadt 260:
1.19 markus 261: /* Check whether we have cached the ipaddr. */
262: if (canonical_host_ip == NULL) {
263: if (packet_connection_is_on_socket()) {
264: canonical_host_ip =
265: get_peer_ipaddr(packet_get_connection_in());
266: if (canonical_host_ip == NULL)
1.38 ! markus 267: cleanup_exit(255);
1.19 markus 268: } else {
269: /* If not on socket, return UNKNOWN. */
270: canonical_host_ip = xstrdup("UNKNOWN");
271: }
272: }
1.6 markus 273: return canonical_host_ip;
1.24 stevesk 274: }
275:
276: const char *
1.37 markus 277: get_remote_name_or_ip(u_int utmp_len, int use_dns)
1.24 stevesk 278: {
279: static const char *remote = "";
280: if (utmp_len > 0)
1.37 markus 281: remote = get_canonical_hostname(use_dns);
1.24 stevesk 282: if (utmp_len == 0 || strlen(remote) > utmp_len)
283: remote = get_remote_ipaddr();
284: return remote;
1.1 deraadt 285: }
286:
1.10 markus 287: /* Returns the local/remote port for the socket. */
1.1 deraadt 288:
1.27 itojun 289: static int
1.10 markus 290: get_sock_port(int sock, int local)
1.1 deraadt 291: {
1.10 markus 292: struct sockaddr_storage from;
293: socklen_t fromlen;
294: char strport[NI_MAXSERV];
1.1 deraadt 295:
1.6 markus 296: /* Get IP address of client. */
297: fromlen = sizeof(from);
298: memset(&from, 0, sizeof(from));
1.10 markus 299: if (local) {
300: if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
301: error("getsockname failed: %.100s", strerror(errno));
302: return 0;
303: }
304: } else {
1.35 stevesk 305: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.10 markus 306: debug("getpeername failed: %.100s", strerror(errno));
1.38 ! markus 307: cleanup_exit(255);
1.10 markus 308: }
1.6 markus 309: }
310: /* Return port number. */
1.10 markus 311: if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
1.29 deraadt 312: strport, sizeof(strport), NI_NUMERICSERV) != 0)
1.10 markus 313: fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
314: return atoi(strport);
1.1 deraadt 315: }
316:
1.10 markus 317: /* Returns remote/local port number for the current connection. */
1.1 deraadt 318:
1.27 itojun 319: static int
1.10 markus 320: get_port(int local)
1.1 deraadt 321: {
1.8 markus 322: /*
323: * If the connection is not a socket, return 65535. This is
324: * intentionally chosen to be an unprivileged port number.
325: */
1.10 markus 326: if (!packet_connection_is_on_socket())
1.6 markus 327: return 65535;
1.1 deraadt 328:
1.10 markus 329: /* Get socket and return the port number. */
330: return get_sock_port(packet_get_connection_in(), local);
331: }
332:
1.12 markus 333: int
1.10 markus 334: get_peer_port(int sock)
335: {
336: return get_sock_port(sock, 0);
337: }
338:
1.12 markus 339: int
1.28 itojun 340: get_remote_port(void)
1.10 markus 341: {
342: return get_port(0);
343: }
1.1 deraadt 344:
1.10 markus 345: int
1.28 itojun 346: get_local_port(void)
1.10 markus 347: {
348: return get_port(1);
1.1 deraadt 349: }
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