blob: 80b45c79ef32b5918f78b57e97050a8f7161ca64 [file] [log] [blame]
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11005 * Code to connect to a remote host, and to perform the client side of the
6 * login (authentication) dialog.
Damien Millere4340be2000-09-16 13:29:08 +11007 *
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".
Damien Miller95def091999-11-25 00:26:21 +110013 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100014
15#include "includes.h"
Damien Miller12c150e2003-12-17 16:31:10 +110016RCSID("$OpenBSD: sshconnect.c,v 1.155 2003/12/09 21:53:37 markus Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100017
Damien Miller1383bd82000-04-06 12:32:37 +100018#include <openssl/bn.h>
Damien Millereba71ba2000-04-29 23:57:08 +100019
Ben Lindstrom226cfa02001-01-22 05:34:40 +000020#include "ssh.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100021#include "xmalloc.h"
22#include "rsa.h"
Damien Miller1383bd82000-04-06 12:32:37 +100023#include "buffer.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100024#include "packet.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100025#include "uidswap.h"
26#include "compat.h"
Damien Miller450a7a12000-03-26 13:04:51 +100027#include "key.h"
Damien Millereba71ba2000-04-29 23:57:08 +100028#include "sshconnect.h"
Damien Miller450a7a12000-03-26 13:04:51 +100029#include "hostfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000030#include "log.h"
31#include "readconf.h"
32#include "atomicio.h"
33#include "misc.h"
Damien Miller49d795c2002-01-22 23:34:12 +110034#include "readpass.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100035
Damien Miller37876e92003-05-15 10:19:46 +100036#include "dns.h"
Damien Miller37876e92003-05-15 10:19:46 +100037
Damien Millereba71ba2000-04-29 23:57:08 +100038char *client_version_string = NULL;
39char *server_version_string = NULL;
Damien Miller1383bd82000-04-06 12:32:37 +100040
Damien Miller150b5572003-11-17 21:19:29 +110041int matching_host_key_dns = 0;
Damien Miller7392ae62003-06-11 22:05:25 +100042
Ben Lindstromf9c48842002-06-11 16:37:51 +000043/* import */
Damien Milleraae6c611999-12-06 11:47:28 +110044extern Options options;
Damien Miller34132e52000-01-14 15:45:46 +110045extern char *__progname;
Ben Lindstromf9c48842002-06-11 16:37:51 +000046extern uid_t original_real_uid;
47extern uid_t original_effective_uid;
Damien Miller8c4e18a2002-09-19 12:05:02 +100048extern pid_t proxy_command_pid;
Damien Milleraae6c611999-12-06 11:47:28 +110049
Tim Ricee991e3c2001-08-07 15:29:07 -070050#ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
51#define INET6_ADDRSTRLEN 46
52#endif
53
Ben Lindstrom3ed66402002-08-01 01:21:56 +000054static int show_other_keys(const char *, Key *);
Damien Miller5a388972003-11-17 21:10:47 +110055static void warn_changed_key(Key *);
Ben Lindstrom3ed66402002-08-01 01:21:56 +000056
Damien Miller95def091999-11-25 00:26:21 +110057/*
58 * Connect to the given ssh server using a proxy command.
59 */
Ben Lindstrombba81212001-06-25 05:01:22 +000060static int
Ben Lindstromf9c48842002-06-11 16:37:51 +000061ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100062{
Damien Miller95def091999-11-25 00:26:21 +110063 Buffer command;
64 const char *cp;
65 char *command_string;
66 int pin[2], pout[2];
Damien Miller166fca82000-04-20 07:42:21 +100067 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +110068 char strport[NI_MAXSERV];
Damien Millerd4a8b7e1999-10-27 13:42:43 +100069
Damien Miller95def091999-11-25 00:26:21 +110070 /* Convert the port number into a string. */
Damien Miller34132e52000-01-14 15:45:46 +110071 snprintf(strport, sizeof strport, "%hu", port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100072
Damien Miller8c4e18a2002-09-19 12:05:02 +100073 /*
74 * Build the final command string in the buffer by making the
75 * appropriate substitutions to the given proxy command.
76 *
Damien Millera8e06ce2003-11-21 23:48:55 +110077 * Use "exec" to avoid "sh -c" processes on some platforms
Damien Miller8c4e18a2002-09-19 12:05:02 +100078 * (e.g. Solaris)
79 */
Damien Miller95def091999-11-25 00:26:21 +110080 buffer_init(&command);
Damien Miller8c4e18a2002-09-19 12:05:02 +100081 buffer_append(&command, "exec ", 5);
82
Damien Miller95def091999-11-25 00:26:21 +110083 for (cp = proxy_command; *cp; cp++) {
84 if (cp[0] == '%' && cp[1] == '%') {
85 buffer_append(&command, "%", 1);
86 cp++;
87 continue;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100088 }
Damien Miller95def091999-11-25 00:26:21 +110089 if (cp[0] == '%' && cp[1] == 'h') {
90 buffer_append(&command, host, strlen(host));
91 cp++;
92 continue;
93 }
94 if (cp[0] == '%' && cp[1] == 'p') {
Damien Miller34132e52000-01-14 15:45:46 +110095 buffer_append(&command, strport, strlen(strport));
Damien Miller95def091999-11-25 00:26:21 +110096 cp++;
97 continue;
98 }
99 buffer_append(&command, cp, 1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000100 }
Damien Miller95def091999-11-25 00:26:21 +1100101 buffer_append(&command, "\0", 1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000102
Damien Miller95def091999-11-25 00:26:21 +1100103 /* Get the final command string. */
104 command_string = buffer_ptr(&command);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000105
Damien Miller95def091999-11-25 00:26:21 +1100106 /* Create pipes for communicating with the proxy. */
107 if (pipe(pin) < 0 || pipe(pout) < 0)
108 fatal("Could not create pipes to communicate with the proxy: %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +1100109 strerror(errno));
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000110
Damien Miller95def091999-11-25 00:26:21 +1100111 debug("Executing proxy command: %.500s", command_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000112
Damien Miller95def091999-11-25 00:26:21 +1100113 /* Fork and execute the proxy command. */
114 if ((pid = fork()) == 0) {
115 char *argv[10];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000116
Damien Miller95def091999-11-25 00:26:21 +1100117 /* Child. Permanently give up superuser privileges. */
Ben Lindstromf9c48842002-06-11 16:37:51 +0000118 seteuid(original_real_uid);
119 setuid(original_real_uid);
Damien Miller95def091999-11-25 00:26:21 +1100120
121 /* Redirect stdin and stdout. */
122 close(pin[1]);
123 if (pin[0] != 0) {
124 if (dup2(pin[0], 0) < 0)
125 perror("dup2 stdin");
126 close(pin[0]);
127 }
128 close(pout[0]);
129 if (dup2(pout[1], 1) < 0)
130 perror("dup2 stdout");
131 /* Cannot be 1 because pin allocated two descriptors. */
132 close(pout[1]);
133
134 /* Stderr is left as it is so that error messages get
135 printed on the user's terminal. */
Damien Miller7b413d22000-07-01 13:24:21 +1000136 argv[0] = _PATH_BSHELL;
Damien Miller95def091999-11-25 00:26:21 +1100137 argv[1] = "-c";
138 argv[2] = command_string;
139 argv[3] = NULL;
140
141 /* Execute the proxy command. Note that we gave up any
142 extra privileges above. */
Kevin Stevesfcd5d602001-01-07 11:45:22 +0000143 execv(argv[0], argv);
144 perror(argv[0]);
Damien Miller95def091999-11-25 00:26:21 +1100145 exit(1);
146 }
147 /* Parent. */
148 if (pid < 0)
149 fatal("fork failed: %.100s", strerror(errno));
Damien Miller8c4e18a2002-09-19 12:05:02 +1000150 else
151 proxy_command_pid = pid; /* save pid to clean up later */
Damien Miller95def091999-11-25 00:26:21 +1100152
153 /* Close child side of the descriptors. */
154 close(pin[0]);
155 close(pout[1]);
156
157 /* Free the command name. */
158 buffer_free(&command);
159
160 /* Set the connection file descriptors. */
161 packet_set_connection(pout[0], pin[1]);
162
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000163 /* Indicate OK return */
164 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000165}
166
Damien Miller95def091999-11-25 00:26:21 +1100167/*
168 * Creates a (possibly privileged) socket for use as the ssh connection.
169 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000170static int
Damien Miller2372ace2003-05-14 13:42:23 +1000171ssh_create_socket(int privileged, struct addrinfo *ai)
Damien Miller95def091999-11-25 00:26:21 +1100172{
Ben Lindstrome0f88042001-04-30 13:06:24 +0000173 int sock, gaierr;
174 struct addrinfo hints, *res;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000175
Damien Miller5428f641999-11-25 11:54:57 +1100176 /*
177 * If we are running as root and want to connect to a privileged
178 * port, bind our own socket to a privileged port.
179 */
Damien Miller95def091999-11-25 00:26:21 +1100180 if (privileged) {
181 int p = IPPORT_RESERVED - 1;
Ben Lindstromf9c48842002-06-11 16:37:51 +0000182 PRIV_START;
Damien Miller2372ace2003-05-14 13:42:23 +1000183 sock = rresvport_af(&p, ai->ai_family);
Ben Lindstromf9c48842002-06-11 16:37:51 +0000184 PRIV_END;
Damien Miller95def091999-11-25 00:26:21 +1100185 if (sock < 0)
Damien Miller2372ace2003-05-14 13:42:23 +1000186 error("rresvport: af=%d %.100s", ai->ai_family,
187 strerror(errno));
Damien Miller98c7ad62000-03-09 21:27:49 +1100188 else
189 debug("Allocated local port %d.", p);
Ben Lindstrome0f88042001-04-30 13:06:24 +0000190 return sock;
Damien Miller95def091999-11-25 00:26:21 +1100191 }
Damien Miller2372ace2003-05-14 13:42:23 +1000192 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
Ben Lindstrome0f88042001-04-30 13:06:24 +0000193 if (sock < 0)
194 error("socket: %.100s", strerror(errno));
Ben Lindstrome0f88042001-04-30 13:06:24 +0000195
196 /* Bind the socket to an alternative local IP address */
197 if (options.bind_address == NULL)
198 return sock;
199
200 memset(&hints, 0, sizeof(hints));
Damien Miller2372ace2003-05-14 13:42:23 +1000201 hints.ai_family = ai->ai_family;
202 hints.ai_socktype = ai->ai_socktype;
203 hints.ai_protocol = ai->ai_protocol;
Ben Lindstrome0f88042001-04-30 13:06:24 +0000204 hints.ai_flags = AI_PASSIVE;
205 gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
206 if (gaierr) {
207 error("getaddrinfo: %s: %s", options.bind_address,
208 gai_strerror(gaierr));
209 close(sock);
210 return -1;
211 }
212 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
213 error("bind: %s: %s", options.bind_address, strerror(errno));
214 close(sock);
215 freeaddrinfo(res);
216 return -1;
217 }
218 freeaddrinfo(res);
Damien Miller95def091999-11-25 00:26:21 +1100219 return sock;
220}
221
Damien Millerb78d5eb2003-05-16 11:39:04 +1000222static int
223timeout_connect(int sockfd, const struct sockaddr *serv_addr,
224 socklen_t addrlen, int timeout)
225{
226 fd_set *fdset;
227 struct timeval tv;
228 socklen_t optlen;
Damien Miller08293fa2003-05-23 18:44:41 +1000229 int fdsetsz, optval, rc, result = -1;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000230
231 if (timeout <= 0)
232 return (connect(sockfd, serv_addr, addrlen));
233
234 if (fcntl(sockfd, F_SETFL, O_NONBLOCK) < 0)
235 return (-1);
236
237 rc = connect(sockfd, serv_addr, addrlen);
238 if (rc == 0)
239 return (0);
240 if (errno != EINPROGRESS)
241 return (-1);
242
243 fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
244 fdset = (fd_set *)xmalloc(fdsetsz);
245
Darren Tuckeredeb1f72003-07-03 13:48:04 +1000246 memset(fdset, 0, fdsetsz);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000247 FD_SET(sockfd, fdset);
248 tv.tv_sec = timeout;
249 tv.tv_usec = 0;
250
251 for(;;) {
252 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
253 if (rc != -1 || errno != EINTR)
254 break;
255 }
256
257 switch(rc) {
258 case 0:
259 /* Timed out */
260 errno = ETIMEDOUT;
Damien Miller08293fa2003-05-23 18:44:41 +1000261 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000262 case -1:
263 /* Select error */
Damien Millera8e06ce2003-11-21 23:48:55 +1100264 debug("select: %s", strerror(errno));
Damien Miller08293fa2003-05-23 18:44:41 +1000265 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000266 case 1:
267 /* Completed or failed */
268 optval = 0;
269 optlen = sizeof(optval);
Damien Millera8e06ce2003-11-21 23:48:55 +1100270 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
Darren Tuckerbd5361b2003-09-22 20:59:16 +1000271 &optlen) == -1) {
Damien Millera8e06ce2003-11-21 23:48:55 +1100272 debug("getsockopt: %s", strerror(errno));
Damien Miller08293fa2003-05-23 18:44:41 +1000273 break;
Darren Tuckerbd5361b2003-09-22 20:59:16 +1000274 }
Damien Millerb78d5eb2003-05-16 11:39:04 +1000275 if (optval != 0) {
276 errno = optval;
Damien Miller08293fa2003-05-23 18:44:41 +1000277 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000278 }
Damien Miller08293fa2003-05-23 18:44:41 +1000279 result = 0;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000280 break;
281 default:
282 /* Should not occur */
283 fatal("Bogus return (%d) from select()", rc);
284 }
285
Damien Miller08293fa2003-05-23 18:44:41 +1000286 xfree(fdset);
287 return (result);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000288}
289
Damien Miller95def091999-11-25 00:26:21 +1100290/*
Damien Miller34132e52000-01-14 15:45:46 +1100291 * Opens a TCP/IP connection to the remote server on the given host.
292 * The address of the remote host will be returned in hostaddr.
Ben Lindstromf9c48842002-06-11 16:37:51 +0000293 * If port is 0, the default port will be used. If needpriv is true,
Damien Miller95def091999-11-25 00:26:21 +1100294 * a privileged port will be allocated to make the connection.
Ben Lindstromf9c48842002-06-11 16:37:51 +0000295 * This requires super-user privileges if needpriv is true.
Damien Miller95def091999-11-25 00:26:21 +1100296 * Connection_attempts specifies the maximum number of tries (one per
297 * second). If proxy_command is non-NULL, it specifies the command (with %h
298 * and %p substituted for host and port, respectively) to use to contact
299 * the daemon.
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000300 * Return values:
301 * 0 for OK
302 * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
303 * ECONNABORTED if we failed without a "Connection refused"
304 * Suitable error messages for the connection failure will already have been
305 * printed.
Damien Miller95def091999-11-25 00:26:21 +1100306 */
307int
Damien Miller34132e52000-01-14 15:45:46 +1100308ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
Damien Miller139d4cd2001-10-10 15:07:44 +1000309 u_short port, int family, int connection_attempts,
Ben Lindstromf9c48842002-06-11 16:37:51 +0000310 int needpriv, const char *proxy_command)
Damien Miller95def091999-11-25 00:26:21 +1100311{
Damien Miller34132e52000-01-14 15:45:46 +1100312 int gaierr;
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000313 int on = 1;
314 int sock = -1, attempt;
315 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
316 struct addrinfo hints, *ai, *aitop;
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000317 struct servent *sp;
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000318 /*
319 * Did we get only other errors than "Connection refused" (which
320 * should block fallback to rsh and similar), or did we get at least
321 * one "Connection refused"?
322 */
323 int full_failure = 1;
Damien Miller95def091999-11-25 00:26:21 +1100324
Ben Lindstrom064496f2002-12-23 02:04:22 +0000325 debug2("ssh_connect: needpriv %d", needpriv);
Damien Miller95def091999-11-25 00:26:21 +1100326
327 /* Get default port if port has not been set. */
328 if (port == 0) {
329 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
330 if (sp)
331 port = ntohs(sp->s_port);
332 else
333 port = SSH_DEFAULT_PORT;
334 }
335 /* If a proxy command is given, connect using it. */
336 if (proxy_command != NULL)
Ben Lindstromf9c48842002-06-11 16:37:51 +0000337 return ssh_proxy_connect(host, port, proxy_command);
Damien Miller95def091999-11-25 00:26:21 +1100338
339 /* No proxy command. */
340
Damien Miller34132e52000-01-14 15:45:46 +1100341 memset(&hints, 0, sizeof(hints));
Damien Miller139d4cd2001-10-10 15:07:44 +1000342 hints.ai_family = family;
Damien Miller34132e52000-01-14 15:45:46 +1100343 hints.ai_socktype = SOCK_STREAM;
Ben Lindstrom5c385522002-06-23 21:23:20 +0000344 snprintf(strport, sizeof strport, "%u", port);
Damien Miller34132e52000-01-14 15:45:46 +1100345 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
346 fatal("%s: %.100s: %s", __progname, host,
347 gai_strerror(gaierr));
Damien Miller95def091999-11-25 00:26:21 +1100348
Damien Millera34a28b1999-12-14 10:47:15 +1100349 /*
350 * Try to connect several times. On some machines, the first time
351 * will sometimes fail. In general socket code appears to behave
352 * quite magically on many machines.
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000353 */
354 for (attempt = 0; ;) {
Damien Miller95def091999-11-25 00:26:21 +1100355 if (attempt > 0)
356 debug("Trying again...");
357
Damien Miller34132e52000-01-14 15:45:46 +1100358 /* Loop through addresses for this host, and try each one in
Damien Miller4af51302000-04-16 11:18:38 +1000359 sequence until the connection succeeds. */
Damien Miller34132e52000-01-14 15:45:46 +1100360 for (ai = aitop; ai; ai = ai->ai_next) {
361 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
362 continue;
363 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
364 ntop, sizeof(ntop), strport, sizeof(strport),
365 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
366 error("ssh_connect: getnameinfo failed");
367 continue;
368 }
369 debug("Connecting to %.200s [%.100s] port %s.",
370 host, ntop, strport);
Damien Miller95def091999-11-25 00:26:21 +1100371
Damien Miller34132e52000-01-14 15:45:46 +1100372 /* Create a socket for connecting. */
Damien Miller2372ace2003-05-14 13:42:23 +1000373 sock = ssh_create_socket(needpriv, ai);
Damien Miller34132e52000-01-14 15:45:46 +1100374 if (sock < 0)
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000375 /* Any error is already output */
Damien Miller34132e52000-01-14 15:45:46 +1100376 continue;
Damien Miller95def091999-11-25 00:26:21 +1100377
Damien Millerb78d5eb2003-05-16 11:39:04 +1000378 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
379 options.connection_timeout) >= 0) {
Damien Miller34132e52000-01-14 15:45:46 +1100380 /* Successful connection. */
Ben Lindstroma3700052001-04-05 23:26:32 +0000381 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
Damien Miller95def091999-11-25 00:26:21 +1100382 break;
Damien Miller34132e52000-01-14 15:45:46 +1100383 } else {
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000384 if (errno == ECONNREFUSED)
385 full_failure = 0;
Ben Lindstrom728aa7e2002-07-15 17:48:11 +0000386 debug("connect to address %s port %s: %s",
387 ntop, strport, strerror(errno));
Damien Miller5428f641999-11-25 11:54:57 +1100388 /*
389 * Close the failed socket; there appear to
390 * be some problems when reusing a socket for
391 * which connect() has already returned an
392 * error.
393 */
Damien Miller95def091999-11-25 00:26:21 +1100394 close(sock);
395 }
Damien Miller95def091999-11-25 00:26:21 +1100396 }
Damien Miller34132e52000-01-14 15:45:46 +1100397 if (ai)
398 break; /* Successful connection. */
Damien Miller95def091999-11-25 00:26:21 +1100399
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000400 attempt++;
401 if (attempt >= connection_attempts)
402 break;
Damien Miller95def091999-11-25 00:26:21 +1100403 /* Sleep a moment before retrying. */
404 sleep(1);
405 }
Damien Miller34132e52000-01-14 15:45:46 +1100406
407 freeaddrinfo(aitop);
408
Damien Miller95def091999-11-25 00:26:21 +1100409 /* Return failure if we didn't get a successful connection. */
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000410 if (attempt >= connection_attempts) {
Damien Miller996acd22003-04-09 20:59:48 +1000411 logit("ssh: connect to host %s port %s: %s",
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000412 host, strport, strerror(errno));
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000413 return full_failure ? ECONNABORTED : ECONNREFUSED;
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000414 }
Damien Miller95def091999-11-25 00:26:21 +1100415
416 debug("Connection established.");
417
Damien Miller12c150e2003-12-17 16:31:10 +1100418 /* Set SO_KEEPALIVE if requested. */
419 if (options.tcp_keep_alive &&
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000420 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
421 sizeof(on)) < 0)
422 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100423
424 /* Set the connection. */
425 packet_set_connection(sock, sock);
426
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000427 return 0;
Damien Miller95def091999-11-25 00:26:21 +1100428}
429
Damien Milleraae6c611999-12-06 11:47:28 +1100430/*
Damien Miller95def091999-11-25 00:26:21 +1100431 * Waits for the server identification string, and sends our own
432 * identification string.
433 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000434static void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000435ssh_exchange_identification(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000436{
Damien Miller95def091999-11-25 00:26:21 +1100437 char buf[256], remote_version[256]; /* must be same size! */
Damien Miller78928792000-04-12 20:17:38 +1000438 int remote_major, remote_minor, i, mismatch;
Damien Miller95def091999-11-25 00:26:21 +1100439 int connection_in = packet_get_connection_in();
440 int connection_out = packet_get_connection_out();
Kevin Stevesef4eea92001-02-05 12:42:17 +0000441 int minor1 = PROTOCOL_MINOR_1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000442
Damien Miller95def091999-11-25 00:26:21 +1100443 /* Read other side\'s version identification. */
Damien Millerf6d9e222000-06-18 14:50:44 +1000444 for (;;) {
445 for (i = 0; i < sizeof(buf) - 1; i++) {
446 int len = atomicio(read, connection_in, &buf[i], 1);
447 if (len < 0)
448 fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
449 if (len != 1)
450 fatal("ssh_exchange_identification: Connection closed by remote host");
451 if (buf[i] == '\r') {
452 buf[i] = '\n';
453 buf[i + 1] = 0;
454 continue; /**XXX wait for \n */
455 }
456 if (buf[i] == '\n') {
457 buf[i + 1] = 0;
458 break;
459 }
Damien Miller95def091999-11-25 00:26:21 +1100460 }
Damien Millerf6d9e222000-06-18 14:50:44 +1000461 buf[sizeof(buf) - 1] = 0;
462 if (strncmp(buf, "SSH-", 4) == 0)
Damien Miller95def091999-11-25 00:26:21 +1100463 break;
Damien Millerf6d9e222000-06-18 14:50:44 +1000464 debug("ssh_exchange_identification: %s", buf);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000465 }
Damien Miller1383bd82000-04-06 12:32:37 +1000466 server_version_string = xstrdup(buf);
Damien Miller95def091999-11-25 00:26:21 +1100467
Damien Miller5428f641999-11-25 11:54:57 +1100468 /*
469 * Check that the versions match. In future this might accept
470 * several versions and set appropriate flags to handle them.
471 */
Damien Miller1383bd82000-04-06 12:32:37 +1000472 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
473 &remote_major, &remote_minor, remote_version) != 3)
Damien Miller95def091999-11-25 00:26:21 +1100474 fatal("Bad remote protocol version identification: '%.100s'", buf);
475 debug("Remote protocol version %d.%d, remote software version %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +1100476 remote_major, remote_minor, remote_version);
Damien Miller95def091999-11-25 00:26:21 +1100477
Damien Miller1383bd82000-04-06 12:32:37 +1000478 compat_datafellows(remote_version);
Damien Miller78928792000-04-12 20:17:38 +1000479 mismatch = 0;
Damien Miller1383bd82000-04-06 12:32:37 +1000480
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000481 switch (remote_major) {
Damien Miller78928792000-04-12 20:17:38 +1000482 case 1:
483 if (remote_minor == 99 &&
484 (options.protocol & SSH_PROTO_2) &&
485 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
486 enable_compat20();
487 break;
Damien Miller95def091999-11-25 00:26:21 +1100488 }
Damien Miller78928792000-04-12 20:17:38 +1000489 if (!(options.protocol & SSH_PROTO_1)) {
490 mismatch = 1;
491 break;
492 }
493 if (remote_minor < 3) {
494 fatal("Remote machine has too old SSH software version.");
Damien Miller0bc1bd82000-11-13 22:57:25 +1100495 } else if (remote_minor == 3 || remote_minor == 4) {
Damien Miller78928792000-04-12 20:17:38 +1000496 /* We speak 1.3, too. */
497 enable_compat13();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100498 minor1 = 3;
Damien Miller78928792000-04-12 20:17:38 +1000499 if (options.forward_agent) {
Damien Miller996acd22003-04-09 20:59:48 +1000500 logit("Agent forwarding disabled for protocol 1.3");
Damien Miller78928792000-04-12 20:17:38 +1000501 options.forward_agent = 0;
502 }
503 }
504 break;
505 case 2:
506 if (options.protocol & SSH_PROTO_2) {
507 enable_compat20();
508 break;
509 }
510 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000511 default:
Damien Miller78928792000-04-12 20:17:38 +1000512 mismatch = 1;
513 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000514 }
Damien Miller78928792000-04-12 20:17:38 +1000515 if (mismatch)
Damien Miller95def091999-11-25 00:26:21 +1100516 fatal("Protocol major versions differ: %d vs. %d",
Damien Miller78928792000-04-12 20:17:38 +1000517 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
518 remote_major);
Damien Miller95def091999-11-25 00:26:21 +1100519 /* Send our own protocol version identification. */
520 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
Damien Miller78928792000-04-12 20:17:38 +1000521 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
Damien Miller0bc1bd82000-11-13 22:57:25 +1100522 compat20 ? PROTOCOL_MINOR_2 : minor1,
Damien Miller1383bd82000-04-06 12:32:37 +1000523 SSH_VERSION);
Darren Tucker9f63f222003-07-03 13:46:56 +1000524 if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
Damien Miller95def091999-11-25 00:26:21 +1100525 fatal("write: %.100s", strerror(errno));
Damien Miller1383bd82000-04-06 12:32:37 +1000526 client_version_string = xstrdup(buf);
527 chop(client_version_string);
528 chop(server_version_string);
529 debug("Local version string %.100s", client_version_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000530}
531
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000532/* defaults to 'no' */
Ben Lindstrombba81212001-06-25 05:01:22 +0000533static int
Damien Millere3980042001-10-10 15:02:03 +1000534confirm(const char *prompt)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000535{
Damien Miller49d795c2002-01-22 23:34:12 +1100536 const char *msg, *again = "Please type 'yes' or 'no': ";
537 char *p;
538 int ret = -1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000539
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000540 if (options.batch_mode)
541 return 0;
Damien Miller49d795c2002-01-22 23:34:12 +1100542 for (msg = prompt;;msg = again) {
543 p = read_passphrase(msg, RP_ECHO);
544 if (p == NULL ||
545 (p[0] == '\0') || (p[0] == '\n') ||
546 strncasecmp(p, "no", 2) == 0)
547 ret = 0;
Ben Lindstrom04f9af72002-07-04 00:03:56 +0000548 if (p && strncasecmp(p, "yes", 3) == 0)
Damien Miller49d795c2002-01-22 23:34:12 +1100549 ret = 1;
550 if (p)
551 xfree(p);
552 if (ret != -1)
553 return ret;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000554 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000555}
556
Damien Miller95def091999-11-25 00:26:21 +1100557/*
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000558 * check whether the supplied host key is valid, return -1 if the key
559 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
Damien Miller95def091999-11-25 00:26:21 +1100560 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000561static int
Damien Millereba71ba2000-04-29 23:57:08 +1000562check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000563 int readonly, const char *user_hostfile, const char *system_hostfile)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000564{
Damien Miller450a7a12000-03-26 13:04:51 +1000565 Key *file_key;
Damien Millerf58b58c2003-11-17 21:18:23 +1100566 const char *type = key_type(host_key);
Damien Millera34a28b1999-12-14 10:47:15 +1100567 char *ip = NULL;
Ben Lindstromcfccef92001-03-13 04:57:58 +0000568 char hostline[1000], *hostp, *fp;
Damien Miller95def091999-11-25 00:26:21 +1100569 HostStatus host_status;
570 HostStatus ip_status;
Damien Miller34132e52000-01-14 15:45:46 +1100571 int local = 0, host_ip_differ = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100572 int salen;
Damien Miller34132e52000-01-14 15:45:46 +1100573 char ntop[NI_MAXHOST];
Damien Miller49d795c2002-01-22 23:34:12 +1100574 char msg[1024];
Damien Miller7392ae62003-06-11 22:05:25 +1000575 int len, host_line, ip_line;
Ben Lindstrom46c16222000-12-22 01:43:59 +0000576 const char *host_file = NULL, *ip_file = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100577
578 /*
579 * Force accepting of the host key for loopback/localhost. The
580 * problem is that if the home directory is NFS-mounted to multiple
581 * machines, localhost will refer to a different machine in each of
582 * them, and the user will get bogus HOST_CHANGED warnings. This
583 * essentially disables host authentication for localhost; however,
584 * this is probably not a real problem.
585 */
Damien Millereba71ba2000-04-29 23:57:08 +1000586 /** hostaddr == 0! */
Damien Miller34132e52000-01-14 15:45:46 +1100587 switch (hostaddr->sa_family) {
588 case AF_INET:
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000589 local = (ntohl(((struct sockaddr_in *)hostaddr)->
Kevin Steves399ec972002-03-05 18:59:45 +0000590 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
Damien Millereaf99942000-01-19 13:45:07 +1100591 salen = sizeof(struct sockaddr_in);
Damien Miller34132e52000-01-14 15:45:46 +1100592 break;
593 case AF_INET6:
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000594 local = IN6_IS_ADDR_LOOPBACK(
595 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
Damien Millereaf99942000-01-19 13:45:07 +1100596 salen = sizeof(struct sockaddr_in6);
Damien Miller34132e52000-01-14 15:45:46 +1100597 break;
598 default:
599 local = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100600 salen = sizeof(struct sockaddr_storage);
Damien Miller34132e52000-01-14 15:45:46 +1100601 break;
602 }
Ben Lindstrom3cecc9a2001-10-03 17:39:38 +0000603 if (options.no_host_authentication_for_localhost == 1 && local &&
604 options.host_key_alias == NULL) {
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000605 debug("Forcing accepting of host key for "
606 "loopback/localhost.");
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000607 return 0;
Damien Miller34132e52000-01-14 15:45:46 +1100608 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000609
Damien Milleraae6c611999-12-06 11:47:28 +1100610 /*
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000611 * We don't have the remote ip-address for connections
612 * using a proxy command
Damien Milleraae6c611999-12-06 11:47:28 +1100613 */
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000614 if (options.proxy_command == NULL) {
615 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
616 NULL, 0, NI_NUMERICHOST) != 0)
617 fatal("check_host_key: getnameinfo failed");
618 ip = xstrdup(ntop);
619 } else {
620 ip = xstrdup("<no hostip for proxy command>");
621 }
622 /*
623 * Turn off check_host_ip if the connection is to localhost, via proxy
624 * command or if we don't have a hostname to compare with
625 */
626 if (options.check_host_ip &&
627 (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
Damien Milleraae6c611999-12-06 11:47:28 +1100628 options.check_host_ip = 0;
629
Damien Millera34a28b1999-12-14 10:47:15 +1100630 /*
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000631 * Allow the user to record the key under a different name. This is
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000632 * useful for ssh tunneling over forwarded connections or if you run
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000633 * multiple sshd's on different ports on the same machine.
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000634 */
635 if (options.host_key_alias != NULL) {
636 host = options.host_key_alias;
637 debug("using hostkeyalias: %s", host);
638 }
639
640 /*
Damien Millera34a28b1999-12-14 10:47:15 +1100641 * Store the host key from the known host file in here so that we can
642 * compare it with the key for the IP address.
643 */
Damien Miller450a7a12000-03-26 13:04:51 +1000644 file_key = key_new(host_key->type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000645
Damien Miller5428f641999-11-25 11:54:57 +1100646 /*
647 * Check if the host key is present in the user\'s list of known
648 * hosts or in the systemwide list.
649 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000650 host_file = user_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000651 host_status = check_host_in_hostfile(host_file, host, host_key,
Damien Miller9f0f5c62001-12-21 14:45:46 +1100652 file_key, &host_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000653 if (host_status == HOST_NEW) {
654 host_file = system_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000655 host_status = check_host_in_hostfile(host_file, host, host_key,
656 file_key, &host_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000657 }
Damien Miller5428f641999-11-25 11:54:57 +1100658 /*
Damien Miller5428f641999-11-25 11:54:57 +1100659 * Also perform check for the ip address, skip the check if we are
660 * localhost or the hostname was an ip address to begin with
661 */
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000662 if (options.check_host_ip) {
Damien Miller450a7a12000-03-26 13:04:51 +1000663 Key *ip_key = key_new(host_key->type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000664
Ben Lindstrom46c16222000-12-22 01:43:59 +0000665 ip_file = user_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000666 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
667 ip_key, &ip_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000668 if (ip_status == HOST_NEW) {
669 ip_file = system_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000670 ip_status = check_host_in_hostfile(ip_file, ip,
671 host_key, ip_key, &ip_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000672 }
Damien Miller95def091999-11-25 00:26:21 +1100673 if (host_status == HOST_CHANGED &&
Damien Miller450a7a12000-03-26 13:04:51 +1000674 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
Damien Miller95def091999-11-25 00:26:21 +1100675 host_ip_differ = 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000676
Damien Miller450a7a12000-03-26 13:04:51 +1000677 key_free(ip_key);
Damien Miller95def091999-11-25 00:26:21 +1100678 } else
679 ip_status = host_status;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000680
Damien Miller450a7a12000-03-26 13:04:51 +1000681 key_free(file_key);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000682
Damien Miller95def091999-11-25 00:26:21 +1100683 switch (host_status) {
684 case HOST_OK:
685 /* The host is known and the key matches. */
Damien Millere247cc42000-05-07 12:03:14 +1000686 debug("Host '%.200s' is known and matches the %s host key.",
687 host, type);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000688 debug("Found key in %s:%d", host_file, host_line);
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000689 if (options.check_host_ip && ip_status == HOST_NEW) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000690 if (readonly)
Damien Miller996acd22003-04-09 20:59:48 +1000691 logit("%s host key for IP address "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000692 "'%.128s' not in list of known hosts.",
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000693 type, ip);
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000694 else if (!add_host_to_hostfile(user_hostfile, ip,
Damien Miller9f0f5c62001-12-21 14:45:46 +1100695 host_key))
Damien Miller996acd22003-04-09 20:59:48 +1000696 logit("Failed to add the %s host key for IP "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000697 "address '%.128s' to the list of known "
698 "hosts (%.30s).", type, ip, user_hostfile);
699 else
Damien Miller996acd22003-04-09 20:59:48 +1000700 logit("Warning: Permanently added the %s host "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000701 "key for IP address '%.128s' to the list "
702 "of known hosts.", type, ip);
Damien Miller95def091999-11-25 00:26:21 +1100703 }
704 break;
705 case HOST_NEW:
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000706 if (readonly)
707 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100708 /* The host is new. */
709 if (options.strict_host_key_checking == 1) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000710 /*
711 * User has requested strict host key checking. We
712 * will not add the host key automatically. The only
713 * alternative left is to abort.
714 */
715 error("No %s host key is known for %.200s and you "
716 "have requested strict checking.", type, host);
717 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100718 } else if (options.strict_host_key_checking == 2) {
Damien Miller7392ae62003-06-11 22:05:25 +1000719 char msg1[1024], msg2[1024];
720
721 if (show_other_keys(host, host_key))
722 snprintf(msg1, sizeof(msg1),
723 "\nbut keys of different type are already"
724 " known for this host.");
725 else
726 snprintf(msg1, sizeof(msg1), ".");
Damien Miller95def091999-11-25 00:26:21 +1100727 /* The default */
Ben Lindstromcfccef92001-03-13 04:57:58 +0000728 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
Damien Miller7392ae62003-06-11 22:05:25 +1000729 msg2[0] = '\0';
Damien Miller7392ae62003-06-11 22:05:25 +1000730 if (options.verify_host_key_dns) {
Damien Miller150b5572003-11-17 21:19:29 +1100731 if (matching_host_key_dns)
Damien Miller7392ae62003-06-11 22:05:25 +1000732 snprintf(msg2, sizeof(msg2),
733 "Matching host key fingerprint"
734 " found in DNS.\n");
735 else
736 snprintf(msg2, sizeof(msg2),
737 "No matching host key fingerprint"
738 " found in DNS.\n");
739 }
Damien Miller49d795c2002-01-22 23:34:12 +1100740 snprintf(msg, sizeof(msg),
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000741 "The authenticity of host '%.200s (%s)' can't be "
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000742 "established%s\n"
Damien Miller7392ae62003-06-11 22:05:25 +1000743 "%s key fingerprint is %s.\n%s"
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000744 "Are you sure you want to continue connecting "
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000745 "(yes/no)? ",
Damien Miller7392ae62003-06-11 22:05:25 +1000746 host, ip, msg1, type, fp, msg2);
Ben Lindstromcfccef92001-03-13 04:57:58 +0000747 xfree(fp);
Damien Miller49d795c2002-01-22 23:34:12 +1100748 if (!confirm(msg))
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000749 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100750 }
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000751 if (options.check_host_ip && ip_status == HOST_NEW) {
Damien Miller95def091999-11-25 00:26:21 +1100752 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
753 hostp = hostline;
754 } else
755 hostp = host;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000756
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000757 /*
758 * If not in strict mode, add the key automatically to the
759 * local known_hosts file.
760 */
Damien Millereba71ba2000-04-29 23:57:08 +1000761 if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
Damien Miller996acd22003-04-09 20:59:48 +1000762 logit("Failed to add the host to the list of known "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000763 "hosts (%.500s).", user_hostfile);
Damien Miller95def091999-11-25 00:26:21 +1100764 else
Damien Miller996acd22003-04-09 20:59:48 +1000765 logit("Warning: Permanently added '%.200s' (%s) to the "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000766 "list of known hosts.", hostp, type);
Damien Miller95def091999-11-25 00:26:21 +1100767 break;
768 case HOST_CHANGED:
769 if (options.check_host_ip && host_ip_differ) {
770 char *msg;
771 if (ip_status == HOST_NEW)
772 msg = "is unknown";
773 else if (ip_status == HOST_OK)
774 msg = "is unchanged";
775 else
776 msg = "has a different value";
777 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
778 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
779 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
Damien Millere247cc42000-05-07 12:03:14 +1000780 error("The %s host key for %s has changed,", type, host);
Damien Miller95def091999-11-25 00:26:21 +1100781 error("and the key for the according IP address %s", ip);
782 error("%s. This could either mean that", msg);
783 error("DNS SPOOFING is happening or the IP address for the host");
Ben Lindstrom46c16222000-12-22 01:43:59 +0000784 error("and its host key have changed at the same time.");
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000785 if (ip_status != HOST_NEW)
Ben Lindstrom46c16222000-12-22 01:43:59 +0000786 error("Offending key for IP in %s:%d", ip_file, ip_line);
Damien Miller95def091999-11-25 00:26:21 +1100787 }
788 /* The host key has changed. */
Damien Miller5a388972003-11-17 21:10:47 +1100789 warn_changed_key(host_key);
Damien Miller95def091999-11-25 00:26:21 +1100790 error("Add correct host key in %.100s to get rid of this message.",
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000791 user_hostfile);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000792 error("Offending key in %s:%d", host_file, host_line);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000793
Damien Miller5428f641999-11-25 11:54:57 +1100794 /*
795 * If strict host key checking is in use, the user will have
796 * to edit the key manually and we can only abort.
797 */
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000798 if (options.strict_host_key_checking) {
799 error("%s host key for %.200s has changed and you have "
800 "requested strict checking.", type, host);
801 goto fail;
802 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000803
Damien Miller5428f641999-11-25 11:54:57 +1100804 /*
805 * If strict host key checking has not been requested, allow
Damien Miller941ac452003-06-04 20:31:53 +1000806 * the connection but without MITM-able authentication or
Damien Miller5428f641999-11-25 11:54:57 +1100807 * agent forwarding.
808 */
Damien Miller95def091999-11-25 00:26:21 +1100809 if (options.password_authentication) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000810 error("Password authentication is disabled to avoid "
811 "man-in-the-middle attacks.");
Damien Miller95def091999-11-25 00:26:21 +1100812 options.password_authentication = 0;
813 }
Damien Miller941ac452003-06-04 20:31:53 +1000814 if (options.kbd_interactive_authentication) {
815 error("Keyboard-interactive authentication is disabled"
816 " to avoid man-in-the-middle attacks.");
817 options.kbd_interactive_authentication = 0;
818 options.challenge_response_authentication = 0;
819 }
820 if (options.challenge_response_authentication) {
821 error("Challenge/response authentication is disabled"
822 " to avoid man-in-the-middle attacks.");
823 options.challenge_response_authentication = 0;
824 }
Damien Miller95def091999-11-25 00:26:21 +1100825 if (options.forward_agent) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000826 error("Agent forwarding is disabled to avoid "
827 "man-in-the-middle attacks.");
Damien Miller95def091999-11-25 00:26:21 +1100828 options.forward_agent = 0;
829 }
Ben Lindstromc72745a2000-12-02 19:03:54 +0000830 if (options.forward_x11) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000831 error("X11 forwarding is disabled to avoid "
832 "man-in-the-middle attacks.");
Ben Lindstromc72745a2000-12-02 19:03:54 +0000833 options.forward_x11 = 0;
834 }
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000835 if (options.num_local_forwards > 0 ||
836 options.num_remote_forwards > 0) {
837 error("Port forwarding is disabled to avoid "
838 "man-in-the-middle attacks.");
839 options.num_local_forwards =
Damien Miller9f0f5c62001-12-21 14:45:46 +1100840 options.num_remote_forwards = 0;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000841 }
Damien Miller5428f641999-11-25 11:54:57 +1100842 /*
843 * XXX Should permit the user to change to use the new id.
844 * This could be done by converting the host key to an
845 * identifying sentence, tell that the host identifies itself
846 * by that sentence, and ask the user if he/she whishes to
847 * accept the authentication.
848 */
Damien Miller95def091999-11-25 00:26:21 +1100849 break;
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000850 case HOST_FOUND:
851 fatal("internal error");
852 break;
Damien Miller95def091999-11-25 00:26:21 +1100853 }
Ben Lindstromc72745a2000-12-02 19:03:54 +0000854
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000855 if (options.check_host_ip && host_status != HOST_CHANGED &&
856 ip_status == HOST_CHANGED) {
Damien Miller49d795c2002-01-22 23:34:12 +1100857 snprintf(msg, sizeof(msg),
858 "Warning: the %s host key for '%.200s' "
859 "differs from the key for the IP address '%.128s'"
860 "\nOffending key for IP in %s:%d",
861 type, host, ip, ip_file, ip_line);
862 if (host_status == HOST_OK) {
863 len = strlen(msg);
864 snprintf(msg + len, sizeof(msg) - len,
865 "\nMatching host key in %s:%d",
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000866 host_file, host_line);
Damien Miller49d795c2002-01-22 23:34:12 +1100867 }
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000868 if (options.strict_host_key_checking == 1) {
Damien Millerab2db412003-06-02 19:09:13 +1000869 logit("%s", msg);
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000870 error("Exiting, you have requested strict checking.");
871 goto fail;
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000872 } else if (options.strict_host_key_checking == 2) {
Damien Miller49d795c2002-01-22 23:34:12 +1100873 strlcat(msg, "\nAre you sure you want "
874 "to continue connecting (yes/no)? ", sizeof(msg));
875 if (!confirm(msg))
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000876 goto fail;
Damien Miller49d795c2002-01-22 23:34:12 +1100877 } else {
Damien Millerab2db412003-06-02 19:09:13 +1000878 logit("%s", msg);
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000879 }
880 }
881
Ben Lindstromc72745a2000-12-02 19:03:54 +0000882 xfree(ip);
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000883 return 0;
884
885fail:
886 xfree(ip);
887 return -1;
888}
889
Damien Miller37876e92003-05-15 10:19:46 +1000890/* returns 0 if key verifies or -1 if key does NOT verify */
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000891int
892verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
893{
894 struct stat st;
Damien Miller150b5572003-11-17 21:19:29 +1100895 int flags = 0;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000896
Damien Miller150b5572003-11-17 21:19:29 +1100897 if (options.verify_host_key_dns &&
898 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
899
900 if (flags & DNS_VERIFY_FOUND) {
901
902 if (options.verify_host_key_dns == 1 &&
903 flags & DNS_VERIFY_MATCH &&
904 flags & DNS_VERIFY_SECURE)
905 return 0;
906
907 if (flags & DNS_VERIFY_MATCH) {
908 matching_host_key_dns = 1;
909 } else {
910 warn_changed_key(host_key);
911 error("Update the SSHFP RR in DNS with the new "
912 "host key to get rid of this message.");
913 }
Damien Miller37876e92003-05-15 10:19:46 +1000914 }
915 }
Damien Miller37876e92003-05-15 10:19:46 +1000916
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000917 /* return ok if the key can be found in an old keyfile */
918 if (stat(options.system_hostfile2, &st) == 0 ||
919 stat(options.user_hostfile2, &st) == 0) {
920 if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
921 options.user_hostfile2, options.system_hostfile2) == 0)
922 return 0;
923 }
924 return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
925 options.user_hostfile, options.system_hostfile);
Damien Millera34a28b1999-12-14 10:47:15 +1100926}
Damien Miller037a0dc1999-12-07 15:38:31 +1100927
Damien Miller396691a2000-01-20 22:44:08 +1100928/*
929 * Starts a dialog with the server, and authenticates the current user on the
930 * server. This does not need any extra privileges. The basic connection
931 * to the server must already have been established before this is called.
932 * If login fails, this function prints an error and never returns.
933 * This function does not require super-user privileges.
934 */
935void
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000936ssh_login(Sensitive *sensitive, const char *orighost,
Ben Lindstrom3fcf1a22001-04-08 18:26:59 +0000937 struct sockaddr *hostaddr, struct passwd *pw)
Damien Miller396691a2000-01-20 22:44:08 +1100938{
939 char *host, *cp;
Damien Millereba71ba2000-04-29 23:57:08 +1000940 char *server_user, *local_user;
941
Damien Millereba71ba2000-04-29 23:57:08 +1000942 local_user = xstrdup(pw->pw_name);
943 server_user = options.user ? options.user : local_user;
Damien Miller396691a2000-01-20 22:44:08 +1100944
945 /* Convert the user-supplied hostname into all lowercase. */
946 host = xstrdup(orighost);
947 for (cp = host; *cp; cp++)
948 if (isupper(*cp))
949 *cp = tolower(*cp);
950
951 /* Exchange protocol version identification strings with the server. */
952 ssh_exchange_identification();
953
954 /* Put the connection into non-blocking mode. */
955 packet_set_nonblocking();
956
Damien Miller396691a2000-01-20 22:44:08 +1100957 /* key exchange */
Damien Miller396691a2000-01-20 22:44:08 +1100958 /* authenticate user */
Damien Miller1383bd82000-04-06 12:32:37 +1000959 if (compat20) {
960 ssh_kex2(host, hostaddr);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000961 ssh_userauth2(local_user, server_user, host, sensitive);
Damien Miller1383bd82000-04-06 12:32:37 +1000962 } else {
Damien Miller1383bd82000-04-06 12:32:37 +1000963 ssh_kex(host, hostaddr);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000964 ssh_userauth1(local_user, server_user, host, sensitive);
Damien Miller1383bd82000-04-06 12:32:37 +1000965 }
Damien Miller396691a2000-01-20 22:44:08 +1100966}
Damien Miller79438cc2001-02-16 12:34:57 +1100967
968void
969ssh_put_password(char *password)
970{
971 int size;
972 char *padded;
973
Ben Lindstromd20d0f32001-03-10 17:22:20 +0000974 if (datafellows & SSH_BUG_PASSWORDPAD) {
Ben Lindstrom664408d2001-06-09 01:42:01 +0000975 packet_put_cstring(password);
Ben Lindstromd20d0f32001-03-10 17:22:20 +0000976 return;
977 }
Damien Miller79438cc2001-02-16 12:34:57 +1100978 size = roundup(strlen(password) + 1, 32);
979 padded = xmalloc(size);
980 memset(padded, 0, size);
981 strlcpy(padded, password, size);
982 packet_put_string(padded, size);
983 memset(padded, 0, size);
984 xfree(padded);
985}
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000986
987static int
988show_key_from_file(const char *file, const char *host, int keytype)
989{
990 Key *found;
991 char *fp;
992 int line, ret;
993
994 found = key_new(keytype);
995 if ((ret = lookup_key_in_hostfile_by_type(file, host,
996 keytype, found, &line))) {
997 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
Damien Miller996acd22003-04-09 20:59:48 +1000998 logit("WARNING: %s key found for host %s\n"
Ben Lindstrom4b99be82002-08-01 01:26:29 +0000999 "in %s:%d\n"
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001000 "%s key fingerprint %s.",
1001 key_type(found), host, file, line,
1002 key_type(found), fp);
1003 xfree(fp);
1004 }
1005 key_free(found);
1006 return (ret);
1007}
1008
1009/* print all known host keys for a given host, but skip keys of given type */
1010static int
1011show_other_keys(const char *host, Key *key)
1012{
1013 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1014 int i, found = 0;
1015
1016 for (i = 0; type[i] != -1; i++) {
1017 if (type[i] == key->type)
1018 continue;
1019 if (type[i] != KEY_RSA1 &&
1020 show_key_from_file(options.user_hostfile2, host, type[i])) {
1021 found = 1;
1022 continue;
1023 }
1024 if (type[i] != KEY_RSA1 &&
1025 show_key_from_file(options.system_hostfile2, host, type[i])) {
1026 found = 1;
1027 continue;
1028 }
1029 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1030 found = 1;
1031 continue;
1032 }
1033 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1034 found = 1;
1035 continue;
1036 }
1037 debug2("no key of type %d for host %s", type[i], host);
1038 }
1039 return (found);
1040}
Damien Miller5a388972003-11-17 21:10:47 +11001041
1042static void
1043warn_changed_key(Key *host_key)
1044{
1045 char *fp;
Damien Miller8f746ec2003-11-17 21:11:15 +11001046 const char *type = key_type(host_key);
Damien Miller5a388972003-11-17 21:10:47 +11001047
1048 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1049
1050 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1051 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1052 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1053 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1054 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1055 error("It is also possible that the %s host key has just been changed.", type);
1056 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1057 type, fp);
1058 error("Please contact your system administrator.");
1059
1060 xfree(fp);
Damien Miller5a388972003-11-17 21:10:47 +11001061}