blob: 53b5200ff16b9a88eec9aabd360900e5fc545caa [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 Miller9cf6d072006-03-15 11:29:24 +110016
17#include <sys/types.h>
18#include <sys/wait.h>
Damien Millerf17883e2006-03-15 11:45:54 +110019#include <sys/stat.h>
Damien Miller03e20032006-03-15 11:16:59 +110020
Damien Millerc7b06362006-03-15 11:53:45 +110021#include <ctype.h>
Damien Miller6645e7a2006-03-15 14:42:54 +110022#ifdef HAVE_PATHS_H
Damien Miller03e20032006-03-15 11:16:59 +110023#include <paths.h>
Damien Miller6645e7a2006-03-15 14:42:54 +110024#endif
Damien Millerd4a8b7e1999-10-27 13:42:43 +100025
Ben Lindstrom226cfa02001-01-22 05:34:40 +000026#include "ssh.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100027#include "xmalloc.h"
28#include "rsa.h"
Damien Miller1383bd82000-04-06 12:32:37 +100029#include "buffer.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100030#include "packet.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100031#include "uidswap.h"
32#include "compat.h"
Damien Miller450a7a12000-03-26 13:04:51 +100033#include "key.h"
Damien Millereba71ba2000-04-29 23:57:08 +100034#include "sshconnect.h"
Damien Miller450a7a12000-03-26 13:04:51 +100035#include "hostfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000036#include "log.h"
37#include "readconf.h"
38#include "atomicio.h"
39#include "misc.h"
Damien Miller37876e92003-05-15 10:19:46 +100040#include "dns.h"
Damien Miller37876e92003-05-15 10:19:46 +100041
Damien Millereba71ba2000-04-29 23:57:08 +100042char *client_version_string = NULL;
43char *server_version_string = NULL;
Damien Miller1383bd82000-04-06 12:32:37 +100044
Damien Millerc1af1d52005-11-05 15:08:57 +110045static int matching_host_key_dns = 0;
Damien Miller7392ae62003-06-11 22:05:25 +100046
Ben Lindstromf9c48842002-06-11 16:37:51 +000047/* import */
Damien Milleraae6c611999-12-06 11:47:28 +110048extern Options options;
Damien Miller34132e52000-01-14 15:45:46 +110049extern char *__progname;
Ben Lindstromf9c48842002-06-11 16:37:51 +000050extern uid_t original_real_uid;
51extern uid_t original_effective_uid;
Damien Miller8c4e18a2002-09-19 12:05:02 +100052extern pid_t proxy_command_pid;
Damien Milleraae6c611999-12-06 11:47:28 +110053
Tim Ricee991e3c2001-08-07 15:29:07 -070054#ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
55#define INET6_ADDRSTRLEN 46
56#endif
57
Ben Lindstrom3ed66402002-08-01 01:21:56 +000058static int show_other_keys(const char *, Key *);
Damien Miller5a388972003-11-17 21:10:47 +110059static void warn_changed_key(Key *);
Ben Lindstrom3ed66402002-08-01 01:21:56 +000060
Damien Miller95def091999-11-25 00:26:21 +110061/*
62 * Connect to the given ssh server using a proxy command.
63 */
Ben Lindstrombba81212001-06-25 05:01:22 +000064static int
Ben Lindstromf9c48842002-06-11 16:37:51 +000065ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100066{
Damien Miller6476cad2005-06-16 13:18:34 +100067 char *command_string, *tmp;
Damien Miller95def091999-11-25 00:26:21 +110068 int pin[2], pout[2];
Damien Miller166fca82000-04-20 07:42:21 +100069 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +110070 char strport[NI_MAXSERV];
Damien Miller6476cad2005-06-16 13:18:34 +100071 size_t len;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100072
Damien Miller95def091999-11-25 00:26:21 +110073 /* Convert the port number into a string. */
Damien Miller34132e52000-01-14 15:45:46 +110074 snprintf(strport, sizeof strport, "%hu", port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100075
Damien Miller8c4e18a2002-09-19 12:05:02 +100076 /*
77 * Build the final command string in the buffer by making the
78 * appropriate substitutions to the given proxy command.
79 *
Damien Millera8e06ce2003-11-21 23:48:55 +110080 * Use "exec" to avoid "sh -c" processes on some platforms
Damien Miller8c4e18a2002-09-19 12:05:02 +100081 * (e.g. Solaris)
82 */
Damien Miller6476cad2005-06-16 13:18:34 +100083 len = strlen(proxy_command) + 6;
84 tmp = xmalloc(len);
85 strlcpy(tmp, "exec ", len);
86 strlcat(tmp, proxy_command, len);
87 command_string = percent_expand(tmp, "h", host,
88 "p", strport, (char *)NULL);
89 xfree(tmp);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100090
Damien Miller95def091999-11-25 00:26:21 +110091 /* Create pipes for communicating with the proxy. */
92 if (pipe(pin) < 0 || pipe(pout) < 0)
93 fatal("Could not create pipes to communicate with the proxy: %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +110094 strerror(errno));
Damien Millerd4a8b7e1999-10-27 13:42:43 +100095
Damien Miller95def091999-11-25 00:26:21 +110096 debug("Executing proxy command: %.500s", command_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100097
Damien Miller95def091999-11-25 00:26:21 +110098 /* Fork and execute the proxy command. */
99 if ((pid = fork()) == 0) {
100 char *argv[10];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000101
Damien Miller95def091999-11-25 00:26:21 +1100102 /* Child. Permanently give up superuser privileges. */
Ben Lindstromf9c48842002-06-11 16:37:51 +0000103 seteuid(original_real_uid);
104 setuid(original_real_uid);
Damien Miller95def091999-11-25 00:26:21 +1100105
106 /* Redirect stdin and stdout. */
107 close(pin[1]);
108 if (pin[0] != 0) {
109 if (dup2(pin[0], 0) < 0)
110 perror("dup2 stdin");
111 close(pin[0]);
112 }
113 close(pout[0]);
114 if (dup2(pout[1], 1) < 0)
115 perror("dup2 stdout");
116 /* Cannot be 1 because pin allocated two descriptors. */
117 close(pout[1]);
118
119 /* Stderr is left as it is so that error messages get
120 printed on the user's terminal. */
Damien Miller7b413d22000-07-01 13:24:21 +1000121 argv[0] = _PATH_BSHELL;
Damien Miller95def091999-11-25 00:26:21 +1100122 argv[1] = "-c";
123 argv[2] = command_string;
124 argv[3] = NULL;
125
126 /* Execute the proxy command. Note that we gave up any
127 extra privileges above. */
Kevin Stevesfcd5d602001-01-07 11:45:22 +0000128 execv(argv[0], argv);
129 perror(argv[0]);
Damien Miller95def091999-11-25 00:26:21 +1100130 exit(1);
131 }
132 /* Parent. */
133 if (pid < 0)
134 fatal("fork failed: %.100s", strerror(errno));
Damien Miller8c4e18a2002-09-19 12:05:02 +1000135 else
136 proxy_command_pid = pid; /* save pid to clean up later */
Damien Miller95def091999-11-25 00:26:21 +1100137
138 /* Close child side of the descriptors. */
139 close(pin[0]);
140 close(pout[1]);
141
142 /* Free the command name. */
Damien Miller6476cad2005-06-16 13:18:34 +1000143 xfree(command_string);
Damien Miller95def091999-11-25 00:26:21 +1100144
145 /* Set the connection file descriptors. */
146 packet_set_connection(pout[0], pin[1]);
147
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000148 /* Indicate OK return */
149 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000150}
151
Damien Miller95def091999-11-25 00:26:21 +1100152/*
153 * Creates a (possibly privileged) socket for use as the ssh connection.
154 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000155static int
Damien Miller2372ace2003-05-14 13:42:23 +1000156ssh_create_socket(int privileged, struct addrinfo *ai)
Damien Miller95def091999-11-25 00:26:21 +1100157{
Ben Lindstrome0f88042001-04-30 13:06:24 +0000158 int sock, gaierr;
159 struct addrinfo hints, *res;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000160
Damien Miller5428f641999-11-25 11:54:57 +1100161 /*
162 * If we are running as root and want to connect to a privileged
163 * port, bind our own socket to a privileged port.
164 */
Damien Miller95def091999-11-25 00:26:21 +1100165 if (privileged) {
166 int p = IPPORT_RESERVED - 1;
Ben Lindstromf9c48842002-06-11 16:37:51 +0000167 PRIV_START;
Damien Miller2372ace2003-05-14 13:42:23 +1000168 sock = rresvport_af(&p, ai->ai_family);
Ben Lindstromf9c48842002-06-11 16:37:51 +0000169 PRIV_END;
Damien Miller95def091999-11-25 00:26:21 +1100170 if (sock < 0)
Damien Miller2372ace2003-05-14 13:42:23 +1000171 error("rresvport: af=%d %.100s", ai->ai_family,
172 strerror(errno));
Damien Miller98c7ad62000-03-09 21:27:49 +1100173 else
174 debug("Allocated local port %d.", p);
Ben Lindstrome0f88042001-04-30 13:06:24 +0000175 return sock;
Damien Miller95def091999-11-25 00:26:21 +1100176 }
Damien Miller2372ace2003-05-14 13:42:23 +1000177 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
Ben Lindstrome0f88042001-04-30 13:06:24 +0000178 if (sock < 0)
179 error("socket: %.100s", strerror(errno));
Ben Lindstrome0f88042001-04-30 13:06:24 +0000180
181 /* Bind the socket to an alternative local IP address */
182 if (options.bind_address == NULL)
183 return sock;
184
185 memset(&hints, 0, sizeof(hints));
Damien Miller2372ace2003-05-14 13:42:23 +1000186 hints.ai_family = ai->ai_family;
187 hints.ai_socktype = ai->ai_socktype;
188 hints.ai_protocol = ai->ai_protocol;
Ben Lindstrome0f88042001-04-30 13:06:24 +0000189 hints.ai_flags = AI_PASSIVE;
190 gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
191 if (gaierr) {
192 error("getaddrinfo: %s: %s", options.bind_address,
193 gai_strerror(gaierr));
194 close(sock);
195 return -1;
196 }
197 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
198 error("bind: %s: %s", options.bind_address, strerror(errno));
199 close(sock);
200 freeaddrinfo(res);
201 return -1;
202 }
203 freeaddrinfo(res);
Damien Miller95def091999-11-25 00:26:21 +1100204 return sock;
205}
206
Damien Millerb78d5eb2003-05-16 11:39:04 +1000207static int
208timeout_connect(int sockfd, const struct sockaddr *serv_addr,
209 socklen_t addrlen, int timeout)
210{
211 fd_set *fdset;
212 struct timeval tv;
213 socklen_t optlen;
Damien Miller08293fa2003-05-23 18:44:41 +1000214 int fdsetsz, optval, rc, result = -1;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000215
216 if (timeout <= 0)
217 return (connect(sockfd, serv_addr, addrlen));
218
Damien Millerf6723f02004-01-27 21:21:27 +1100219 set_nonblock(sockfd);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000220 rc = connect(sockfd, serv_addr, addrlen);
Damien Millerf6723f02004-01-27 21:21:27 +1100221 if (rc == 0) {
222 unset_nonblock(sockfd);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000223 return (0);
Damien Millerf6723f02004-01-27 21:21:27 +1100224 }
Damien Millerb78d5eb2003-05-16 11:39:04 +1000225 if (errno != EINPROGRESS)
226 return (-1);
227
228 fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
229 fdset = (fd_set *)xmalloc(fdsetsz);
230
Darren Tuckeredeb1f72003-07-03 13:48:04 +1000231 memset(fdset, 0, fdsetsz);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000232 FD_SET(sockfd, fdset);
233 tv.tv_sec = timeout;
234 tv.tv_usec = 0;
235
Darren Tucker47eede72005-03-14 23:08:12 +1100236 for (;;) {
Damien Millerb78d5eb2003-05-16 11:39:04 +1000237 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
238 if (rc != -1 || errno != EINTR)
239 break;
240 }
241
Darren Tucker47eede72005-03-14 23:08:12 +1100242 switch (rc) {
Damien Millerb78d5eb2003-05-16 11:39:04 +1000243 case 0:
244 /* Timed out */
245 errno = ETIMEDOUT;
Damien Miller08293fa2003-05-23 18:44:41 +1000246 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000247 case -1:
248 /* Select error */
Damien Millera8e06ce2003-11-21 23:48:55 +1100249 debug("select: %s", strerror(errno));
Damien Miller08293fa2003-05-23 18:44:41 +1000250 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000251 case 1:
252 /* Completed or failed */
253 optval = 0;
254 optlen = sizeof(optval);
Damien Millera8e06ce2003-11-21 23:48:55 +1100255 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
Darren Tuckerbd5361b2003-09-22 20:59:16 +1000256 &optlen) == -1) {
Damien Millera8e06ce2003-11-21 23:48:55 +1100257 debug("getsockopt: %s", strerror(errno));
Damien Miller08293fa2003-05-23 18:44:41 +1000258 break;
Darren Tuckerbd5361b2003-09-22 20:59:16 +1000259 }
Damien Millerb78d5eb2003-05-16 11:39:04 +1000260 if (optval != 0) {
261 errno = optval;
Damien Miller08293fa2003-05-23 18:44:41 +1000262 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000263 }
Damien Miller08293fa2003-05-23 18:44:41 +1000264 result = 0;
Damien Millerf6723f02004-01-27 21:21:27 +1100265 unset_nonblock(sockfd);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000266 break;
267 default:
268 /* Should not occur */
269 fatal("Bogus return (%d) from select()", rc);
270 }
271
Damien Miller08293fa2003-05-23 18:44:41 +1000272 xfree(fdset);
273 return (result);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000274}
275
Damien Miller95def091999-11-25 00:26:21 +1100276/*
Damien Miller34132e52000-01-14 15:45:46 +1100277 * Opens a TCP/IP connection to the remote server on the given host.
278 * The address of the remote host will be returned in hostaddr.
Ben Lindstromf9c48842002-06-11 16:37:51 +0000279 * If port is 0, the default port will be used. If needpriv is true,
Damien Miller95def091999-11-25 00:26:21 +1100280 * a privileged port will be allocated to make the connection.
Ben Lindstromf9c48842002-06-11 16:37:51 +0000281 * This requires super-user privileges if needpriv is true.
Damien Miller95def091999-11-25 00:26:21 +1100282 * Connection_attempts specifies the maximum number of tries (one per
283 * second). If proxy_command is non-NULL, it specifies the command (with %h
284 * and %p substituted for host and port, respectively) to use to contact
285 * the daemon.
286 */
287int
Damien Miller34132e52000-01-14 15:45:46 +1100288ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
Damien Miller139d4cd2001-10-10 15:07:44 +1000289 u_short port, int family, int connection_attempts,
Ben Lindstromf9c48842002-06-11 16:37:51 +0000290 int needpriv, const char *proxy_command)
Damien Miller95def091999-11-25 00:26:21 +1100291{
Damien Miller34132e52000-01-14 15:45:46 +1100292 int gaierr;
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000293 int on = 1;
294 int sock = -1, attempt;
295 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
296 struct addrinfo hints, *ai, *aitop;
Damien Miller95def091999-11-25 00:26:21 +1100297
Ben Lindstrom064496f2002-12-23 02:04:22 +0000298 debug2("ssh_connect: needpriv %d", needpriv);
Damien Miller95def091999-11-25 00:26:21 +1100299
Damien Miller95def091999-11-25 00:26:21 +1100300 /* If a proxy command is given, connect using it. */
301 if (proxy_command != NULL)
Ben Lindstromf9c48842002-06-11 16:37:51 +0000302 return ssh_proxy_connect(host, port, proxy_command);
Damien Miller95def091999-11-25 00:26:21 +1100303
304 /* No proxy command. */
305
Damien Miller34132e52000-01-14 15:45:46 +1100306 memset(&hints, 0, sizeof(hints));
Damien Miller139d4cd2001-10-10 15:07:44 +1000307 hints.ai_family = family;
Damien Miller34132e52000-01-14 15:45:46 +1100308 hints.ai_socktype = SOCK_STREAM;
Ben Lindstrom5c385522002-06-23 21:23:20 +0000309 snprintf(strport, sizeof strport, "%u", port);
Damien Miller34132e52000-01-14 15:45:46 +1100310 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
311 fatal("%s: %.100s: %s", __progname, host,
312 gai_strerror(gaierr));
Damien Miller95def091999-11-25 00:26:21 +1100313
Damien Millera34a28b1999-12-14 10:47:15 +1100314 /*
315 * Try to connect several times. On some machines, the first time
316 * will sometimes fail. In general socket code appears to behave
317 * quite magically on many machines.
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000318 */
319 for (attempt = 0; ;) {
Damien Miller95def091999-11-25 00:26:21 +1100320 if (attempt > 0)
321 debug("Trying again...");
322
Damien Miller34132e52000-01-14 15:45:46 +1100323 /* Loop through addresses for this host, and try each one in
Damien Miller4af51302000-04-16 11:18:38 +1000324 sequence until the connection succeeds. */
Damien Miller34132e52000-01-14 15:45:46 +1100325 for (ai = aitop; ai; ai = ai->ai_next) {
326 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
327 continue;
328 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
329 ntop, sizeof(ntop), strport, sizeof(strport),
330 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
331 error("ssh_connect: getnameinfo failed");
332 continue;
333 }
334 debug("Connecting to %.200s [%.100s] port %s.",
335 host, ntop, strport);
Damien Miller95def091999-11-25 00:26:21 +1100336
Damien Miller34132e52000-01-14 15:45:46 +1100337 /* Create a socket for connecting. */
Damien Miller2372ace2003-05-14 13:42:23 +1000338 sock = ssh_create_socket(needpriv, ai);
Damien Miller34132e52000-01-14 15:45:46 +1100339 if (sock < 0)
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000340 /* Any error is already output */
Damien Miller34132e52000-01-14 15:45:46 +1100341 continue;
Damien Miller95def091999-11-25 00:26:21 +1100342
Damien Millerb78d5eb2003-05-16 11:39:04 +1000343 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
344 options.connection_timeout) >= 0) {
Damien Miller34132e52000-01-14 15:45:46 +1100345 /* Successful connection. */
Ben Lindstroma3700052001-04-05 23:26:32 +0000346 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
Damien Miller95def091999-11-25 00:26:21 +1100347 break;
Damien Miller34132e52000-01-14 15:45:46 +1100348 } else {
Ben Lindstrom728aa7e2002-07-15 17:48:11 +0000349 debug("connect to address %s port %s: %s",
350 ntop, strport, strerror(errno));
Damien Miller5428f641999-11-25 11:54:57 +1100351 /*
352 * Close the failed socket; there appear to
353 * be some problems when reusing a socket for
354 * which connect() has already returned an
355 * error.
356 */
Damien Miller95def091999-11-25 00:26:21 +1100357 close(sock);
358 }
Damien Miller95def091999-11-25 00:26:21 +1100359 }
Damien Miller34132e52000-01-14 15:45:46 +1100360 if (ai)
361 break; /* Successful connection. */
Damien Miller95def091999-11-25 00:26:21 +1100362
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000363 attempt++;
364 if (attempt >= connection_attempts)
365 break;
Damien Miller95def091999-11-25 00:26:21 +1100366 /* Sleep a moment before retrying. */
367 sleep(1);
368 }
Damien Miller34132e52000-01-14 15:45:46 +1100369
370 freeaddrinfo(aitop);
371
Damien Miller95def091999-11-25 00:26:21 +1100372 /* Return failure if we didn't get a successful connection. */
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000373 if (attempt >= connection_attempts) {
Darren Tuckerb2161e32005-01-20 11:00:46 +1100374 error("ssh: connect to host %s port %s: %s",
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000375 host, strport, strerror(errno));
Darren Tuckerb2161e32005-01-20 11:00:46 +1100376 return (-1);
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000377 }
Damien Miller95def091999-11-25 00:26:21 +1100378
379 debug("Connection established.");
380
Damien Miller12c150e2003-12-17 16:31:10 +1100381 /* Set SO_KEEPALIVE if requested. */
382 if (options.tcp_keep_alive &&
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000383 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
384 sizeof(on)) < 0)
385 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100386
387 /* Set the connection. */
388 packet_set_connection(sock, sock);
389
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000390 return 0;
Damien Miller95def091999-11-25 00:26:21 +1100391}
392
Damien Milleraae6c611999-12-06 11:47:28 +1100393/*
Damien Miller95def091999-11-25 00:26:21 +1100394 * Waits for the server identification string, and sends our own
395 * identification string.
396 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000397static void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000398ssh_exchange_identification(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000399{
Damien Miller95def091999-11-25 00:26:21 +1100400 char buf[256], remote_version[256]; /* must be same size! */
Damien Millereccb9de2005-06-17 12:59:34 +1000401 int remote_major, remote_minor, mismatch;
Damien Miller95def091999-11-25 00:26:21 +1100402 int connection_in = packet_get_connection_in();
403 int connection_out = packet_get_connection_out();
Kevin Stevesef4eea92001-02-05 12:42:17 +0000404 int minor1 = PROTOCOL_MINOR_1;
Damien Millereccb9de2005-06-17 12:59:34 +1000405 u_int i;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000406
Damien Millerb253cc42005-05-26 12:23:44 +1000407 /* Read other side's version identification. */
Damien Millerf6d9e222000-06-18 14:50:44 +1000408 for (;;) {
409 for (i = 0; i < sizeof(buf) - 1; i++) {
Damien Millerb253cc42005-05-26 12:23:44 +1000410 size_t len = atomicio(read, connection_in, &buf[i], 1);
411
Damien Miller46d38de2005-07-17 17:02:09 +1000412 if (len != 1 && errno == EPIPE)
Damien Millerf6d9e222000-06-18 14:50:44 +1000413 fatal("ssh_exchange_identification: Connection closed by remote host");
Damien Millerb253cc42005-05-26 12:23:44 +1000414 else if (len != 1)
415 fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
Damien Millerf6d9e222000-06-18 14:50:44 +1000416 if (buf[i] == '\r') {
417 buf[i] = '\n';
418 buf[i + 1] = 0;
419 continue; /**XXX wait for \n */
420 }
421 if (buf[i] == '\n') {
422 buf[i + 1] = 0;
423 break;
424 }
Damien Miller95def091999-11-25 00:26:21 +1100425 }
Damien Millerf6d9e222000-06-18 14:50:44 +1000426 buf[sizeof(buf) - 1] = 0;
427 if (strncmp(buf, "SSH-", 4) == 0)
Damien Miller95def091999-11-25 00:26:21 +1100428 break;
Damien Millerf6d9e222000-06-18 14:50:44 +1000429 debug("ssh_exchange_identification: %s", buf);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000430 }
Damien Miller1383bd82000-04-06 12:32:37 +1000431 server_version_string = xstrdup(buf);
Damien Miller95def091999-11-25 00:26:21 +1100432
Damien Miller5428f641999-11-25 11:54:57 +1100433 /*
434 * Check that the versions match. In future this might accept
435 * several versions and set appropriate flags to handle them.
436 */
Damien Miller1383bd82000-04-06 12:32:37 +1000437 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
438 &remote_major, &remote_minor, remote_version) != 3)
Damien Miller95def091999-11-25 00:26:21 +1100439 fatal("Bad remote protocol version identification: '%.100s'", buf);
440 debug("Remote protocol version %d.%d, remote software version %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +1100441 remote_major, remote_minor, remote_version);
Damien Miller95def091999-11-25 00:26:21 +1100442
Damien Miller1383bd82000-04-06 12:32:37 +1000443 compat_datafellows(remote_version);
Damien Miller78928792000-04-12 20:17:38 +1000444 mismatch = 0;
Damien Miller1383bd82000-04-06 12:32:37 +1000445
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000446 switch (remote_major) {
Damien Miller78928792000-04-12 20:17:38 +1000447 case 1:
448 if (remote_minor == 99 &&
449 (options.protocol & SSH_PROTO_2) &&
450 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
451 enable_compat20();
452 break;
Damien Miller95def091999-11-25 00:26:21 +1100453 }
Damien Miller78928792000-04-12 20:17:38 +1000454 if (!(options.protocol & SSH_PROTO_1)) {
455 mismatch = 1;
456 break;
457 }
458 if (remote_minor < 3) {
459 fatal("Remote machine has too old SSH software version.");
Damien Miller0bc1bd82000-11-13 22:57:25 +1100460 } else if (remote_minor == 3 || remote_minor == 4) {
Damien Miller78928792000-04-12 20:17:38 +1000461 /* We speak 1.3, too. */
462 enable_compat13();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100463 minor1 = 3;
Damien Miller78928792000-04-12 20:17:38 +1000464 if (options.forward_agent) {
Damien Miller996acd22003-04-09 20:59:48 +1000465 logit("Agent forwarding disabled for protocol 1.3");
Damien Miller78928792000-04-12 20:17:38 +1000466 options.forward_agent = 0;
467 }
468 }
469 break;
470 case 2:
471 if (options.protocol & SSH_PROTO_2) {
472 enable_compat20();
473 break;
474 }
475 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000476 default:
Damien Miller78928792000-04-12 20:17:38 +1000477 mismatch = 1;
478 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000479 }
Damien Miller78928792000-04-12 20:17:38 +1000480 if (mismatch)
Damien Miller95def091999-11-25 00:26:21 +1100481 fatal("Protocol major versions differ: %d vs. %d",
Damien Miller78928792000-04-12 20:17:38 +1000482 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
483 remote_major);
Damien Miller95def091999-11-25 00:26:21 +1100484 /* Send our own protocol version identification. */
485 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
Damien Miller78928792000-04-12 20:17:38 +1000486 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
Damien Miller0bc1bd82000-11-13 22:57:25 +1100487 compat20 ? PROTOCOL_MINOR_2 : minor1,
Damien Miller1383bd82000-04-06 12:32:37 +1000488 SSH_VERSION);
Darren Tucker9f63f222003-07-03 13:46:56 +1000489 if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
Damien Miller95def091999-11-25 00:26:21 +1100490 fatal("write: %.100s", strerror(errno));
Damien Miller1383bd82000-04-06 12:32:37 +1000491 client_version_string = xstrdup(buf);
492 chop(client_version_string);
493 chop(server_version_string);
494 debug("Local version string %.100s", client_version_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000495}
496
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000497/* defaults to 'no' */
Ben Lindstrombba81212001-06-25 05:01:22 +0000498static int
Damien Millere3980042001-10-10 15:02:03 +1000499confirm(const char *prompt)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000500{
Damien Miller49d795c2002-01-22 23:34:12 +1100501 const char *msg, *again = "Please type 'yes' or 'no': ";
502 char *p;
503 int ret = -1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000504
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000505 if (options.batch_mode)
506 return 0;
Damien Miller49d795c2002-01-22 23:34:12 +1100507 for (msg = prompt;;msg = again) {
508 p = read_passphrase(msg, RP_ECHO);
509 if (p == NULL ||
510 (p[0] == '\0') || (p[0] == '\n') ||
511 strncasecmp(p, "no", 2) == 0)
512 ret = 0;
Ben Lindstrom04f9af72002-07-04 00:03:56 +0000513 if (p && strncasecmp(p, "yes", 3) == 0)
Damien Miller49d795c2002-01-22 23:34:12 +1100514 ret = 1;
515 if (p)
516 xfree(p);
517 if (ret != -1)
518 return ret;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000519 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000520}
521
Damien Miller95def091999-11-25 00:26:21 +1100522/*
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000523 * check whether the supplied host key is valid, return -1 if the key
524 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
Damien Miller95def091999-11-25 00:26:21 +1100525 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000526static int
Damien Millereba71ba2000-04-29 23:57:08 +1000527check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000528 int readonly, const char *user_hostfile, const char *system_hostfile)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000529{
Damien Miller450a7a12000-03-26 13:04:51 +1000530 Key *file_key;
Damien Millerf58b58c2003-11-17 21:18:23 +1100531 const char *type = key_type(host_key);
Damien Millera34a28b1999-12-14 10:47:15 +1100532 char *ip = NULL;
Ben Lindstromcfccef92001-03-13 04:57:58 +0000533 char hostline[1000], *hostp, *fp;
Damien Miller95def091999-11-25 00:26:21 +1100534 HostStatus host_status;
535 HostStatus ip_status;
Damien Miller1227d4c2005-03-02 12:06:51 +1100536 int r, local = 0, host_ip_differ = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100537 int salen;
Damien Miller34132e52000-01-14 15:45:46 +1100538 char ntop[NI_MAXHOST];
Damien Miller49d795c2002-01-22 23:34:12 +1100539 char msg[1024];
Damien Miller7392ae62003-06-11 22:05:25 +1000540 int len, host_line, ip_line;
Ben Lindstrom46c16222000-12-22 01:43:59 +0000541 const char *host_file = NULL, *ip_file = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100542
543 /*
544 * Force accepting of the host key for loopback/localhost. The
545 * problem is that if the home directory is NFS-mounted to multiple
546 * machines, localhost will refer to a different machine in each of
547 * them, and the user will get bogus HOST_CHANGED warnings. This
548 * essentially disables host authentication for localhost; however,
549 * this is probably not a real problem.
550 */
Damien Millereba71ba2000-04-29 23:57:08 +1000551 /** hostaddr == 0! */
Damien Miller34132e52000-01-14 15:45:46 +1100552 switch (hostaddr->sa_family) {
553 case AF_INET:
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000554 local = (ntohl(((struct sockaddr_in *)hostaddr)->
Damien Miller0dc1bef2005-07-17 17:22:45 +1000555 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
Damien Millereaf99942000-01-19 13:45:07 +1100556 salen = sizeof(struct sockaddr_in);
Damien Miller34132e52000-01-14 15:45:46 +1100557 break;
558 case AF_INET6:
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000559 local = IN6_IS_ADDR_LOOPBACK(
560 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
Damien Millereaf99942000-01-19 13:45:07 +1100561 salen = sizeof(struct sockaddr_in6);
Damien Miller34132e52000-01-14 15:45:46 +1100562 break;
563 default:
564 local = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100565 salen = sizeof(struct sockaddr_storage);
Damien Miller34132e52000-01-14 15:45:46 +1100566 break;
567 }
Ben Lindstrom3cecc9a2001-10-03 17:39:38 +0000568 if (options.no_host_authentication_for_localhost == 1 && local &&
569 options.host_key_alias == NULL) {
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000570 debug("Forcing accepting of host key for "
571 "loopback/localhost.");
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000572 return 0;
Damien Miller34132e52000-01-14 15:45:46 +1100573 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000574
Damien Milleraae6c611999-12-06 11:47:28 +1100575 /*
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000576 * We don't have the remote ip-address for connections
577 * using a proxy command
Damien Milleraae6c611999-12-06 11:47:28 +1100578 */
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000579 if (options.proxy_command == NULL) {
580 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
581 NULL, 0, NI_NUMERICHOST) != 0)
582 fatal("check_host_key: getnameinfo failed");
583 ip = xstrdup(ntop);
584 } else {
585 ip = xstrdup("<no hostip for proxy command>");
586 }
587 /*
588 * Turn off check_host_ip if the connection is to localhost, via proxy
589 * command or if we don't have a hostname to compare with
590 */
591 if (options.check_host_ip &&
592 (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
Damien Milleraae6c611999-12-06 11:47:28 +1100593 options.check_host_ip = 0;
594
Damien Millera34a28b1999-12-14 10:47:15 +1100595 /*
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000596 * Allow the user to record the key under a different name. This is
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000597 * useful for ssh tunneling over forwarded connections or if you run
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000598 * multiple sshd's on different ports on the same machine.
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000599 */
600 if (options.host_key_alias != NULL) {
601 host = options.host_key_alias;
602 debug("using hostkeyalias: %s", host);
603 }
604
605 /*
Damien Millera34a28b1999-12-14 10:47:15 +1100606 * Store the host key from the known host file in here so that we can
607 * compare it with the key for the IP address.
608 */
Damien Miller450a7a12000-03-26 13:04:51 +1000609 file_key = key_new(host_key->type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000610
Damien Miller5428f641999-11-25 11:54:57 +1100611 /*
Damien Miller788f2122005-11-05 15:14:59 +1100612 * Check if the host key is present in the user's list of known
Damien Miller5428f641999-11-25 11:54:57 +1100613 * hosts or in the systemwide list.
614 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000615 host_file = user_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000616 host_status = check_host_in_hostfile(host_file, host, host_key,
Damien Miller9f0f5c62001-12-21 14:45:46 +1100617 file_key, &host_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000618 if (host_status == HOST_NEW) {
619 host_file = system_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000620 host_status = check_host_in_hostfile(host_file, host, host_key,
621 file_key, &host_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000622 }
Damien Miller5428f641999-11-25 11:54:57 +1100623 /*
Damien Miller5428f641999-11-25 11:54:57 +1100624 * Also perform check for the ip address, skip the check if we are
625 * localhost or the hostname was an ip address to begin with
626 */
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000627 if (options.check_host_ip) {
Damien Miller450a7a12000-03-26 13:04:51 +1000628 Key *ip_key = key_new(host_key->type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000629
Ben Lindstrom46c16222000-12-22 01:43:59 +0000630 ip_file = user_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000631 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
632 ip_key, &ip_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000633 if (ip_status == HOST_NEW) {
634 ip_file = system_hostfile;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000635 ip_status = check_host_in_hostfile(ip_file, ip,
636 host_key, ip_key, &ip_line);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000637 }
Damien Miller95def091999-11-25 00:26:21 +1100638 if (host_status == HOST_CHANGED &&
Damien Miller450a7a12000-03-26 13:04:51 +1000639 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
Damien Miller95def091999-11-25 00:26:21 +1100640 host_ip_differ = 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000641
Damien Miller450a7a12000-03-26 13:04:51 +1000642 key_free(ip_key);
Damien Miller95def091999-11-25 00:26:21 +1100643 } else
644 ip_status = host_status;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000645
Damien Miller450a7a12000-03-26 13:04:51 +1000646 key_free(file_key);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000647
Damien Miller95def091999-11-25 00:26:21 +1100648 switch (host_status) {
649 case HOST_OK:
650 /* The host is known and the key matches. */
Damien Millere247cc42000-05-07 12:03:14 +1000651 debug("Host '%.200s' is known and matches the %s host key.",
652 host, type);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000653 debug("Found key in %s:%d", host_file, host_line);
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000654 if (options.check_host_ip && ip_status == HOST_NEW) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000655 if (readonly)
Damien Miller996acd22003-04-09 20:59:48 +1000656 logit("%s host key for IP address "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000657 "'%.128s' not in list of known hosts.",
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000658 type, ip);
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000659 else if (!add_host_to_hostfile(user_hostfile, ip,
Damien Millere1776152005-03-01 21:47:37 +1100660 host_key, options.hash_known_hosts))
Damien Miller996acd22003-04-09 20:59:48 +1000661 logit("Failed to add the %s host key for IP "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000662 "address '%.128s' to the list of known "
663 "hosts (%.30s).", type, ip, user_hostfile);
664 else
Damien Miller996acd22003-04-09 20:59:48 +1000665 logit("Warning: Permanently added the %s host "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000666 "key for IP address '%.128s' to the list "
667 "of known hosts.", type, ip);
Damien Miller95def091999-11-25 00:26:21 +1100668 }
669 break;
670 case HOST_NEW:
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000671 if (readonly)
672 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100673 /* The host is new. */
674 if (options.strict_host_key_checking == 1) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000675 /*
676 * User has requested strict host key checking. We
677 * will not add the host key automatically. The only
678 * alternative left is to abort.
679 */
680 error("No %s host key is known for %.200s and you "
681 "have requested strict checking.", type, host);
682 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100683 } else if (options.strict_host_key_checking == 2) {
Damien Miller7392ae62003-06-11 22:05:25 +1000684 char msg1[1024], msg2[1024];
685
686 if (show_other_keys(host, host_key))
687 snprintf(msg1, sizeof(msg1),
Damien Miller0dc1bef2005-07-17 17:22:45 +1000688 "\nbut keys of different type are already"
689 " known for this host.");
Damien Miller7392ae62003-06-11 22:05:25 +1000690 else
691 snprintf(msg1, sizeof(msg1), ".");
Damien Miller95def091999-11-25 00:26:21 +1100692 /* The default */
Ben Lindstromcfccef92001-03-13 04:57:58 +0000693 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
Damien Miller7392ae62003-06-11 22:05:25 +1000694 msg2[0] = '\0';
Damien Miller7392ae62003-06-11 22:05:25 +1000695 if (options.verify_host_key_dns) {
Damien Miller150b5572003-11-17 21:19:29 +1100696 if (matching_host_key_dns)
Damien Miller7392ae62003-06-11 22:05:25 +1000697 snprintf(msg2, sizeof(msg2),
698 "Matching host key fingerprint"
699 " found in DNS.\n");
700 else
701 snprintf(msg2, sizeof(msg2),
702 "No matching host key fingerprint"
703 " found in DNS.\n");
704 }
Damien Miller49d795c2002-01-22 23:34:12 +1100705 snprintf(msg, sizeof(msg),
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000706 "The authenticity of host '%.200s (%s)' can't be "
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000707 "established%s\n"
Damien Miller7392ae62003-06-11 22:05:25 +1000708 "%s key fingerprint is %s.\n%s"
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000709 "Are you sure you want to continue connecting "
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000710 "(yes/no)? ",
Damien Miller7392ae62003-06-11 22:05:25 +1000711 host, ip, msg1, type, fp, msg2);
Ben Lindstromcfccef92001-03-13 04:57:58 +0000712 xfree(fp);
Damien Miller49d795c2002-01-22 23:34:12 +1100713 if (!confirm(msg))
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000714 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100715 }
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000716 /*
717 * If not in strict mode, add the key automatically to the
718 * local known_hosts file.
719 */
Damien Miller1227d4c2005-03-02 12:06:51 +1100720 if (options.check_host_ip && ip_status == HOST_NEW) {
721 snprintf(hostline, sizeof(hostline), "%s,%s",
722 host, ip);
723 hostp = hostline;
724 if (options.hash_known_hosts) {
725 /* Add hash of host and IP separately */
726 r = add_host_to_hostfile(user_hostfile, host,
727 host_key, options.hash_known_hosts) &&
728 add_host_to_hostfile(user_hostfile, ip,
729 host_key, options.hash_known_hosts);
730 } else {
731 /* Add unhashed "host,ip" */
732 r = add_host_to_hostfile(user_hostfile,
733 hostline, host_key,
734 options.hash_known_hosts);
735 }
736 } else {
737 r = add_host_to_hostfile(user_hostfile, host, host_key,
738 options.hash_known_hosts);
739 hostp = host;
740 }
741
742 if (!r)
Damien Miller996acd22003-04-09 20:59:48 +1000743 logit("Failed to add the host to the list of known "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000744 "hosts (%.500s).", user_hostfile);
Damien Miller95def091999-11-25 00:26:21 +1100745 else
Damien Miller996acd22003-04-09 20:59:48 +1000746 logit("Warning: Permanently added '%.200s' (%s) to the "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000747 "list of known hosts.", hostp, type);
Damien Miller95def091999-11-25 00:26:21 +1100748 break;
749 case HOST_CHANGED:
750 if (options.check_host_ip && host_ip_differ) {
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000751 char *key_msg;
Damien Miller95def091999-11-25 00:26:21 +1100752 if (ip_status == HOST_NEW)
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000753 key_msg = "is unknown";
Damien Miller95def091999-11-25 00:26:21 +1100754 else if (ip_status == HOST_OK)
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000755 key_msg = "is unchanged";
Damien Miller95def091999-11-25 00:26:21 +1100756 else
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000757 key_msg = "has a different value";
Damien Miller95def091999-11-25 00:26:21 +1100758 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
759 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
760 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
Damien Millere247cc42000-05-07 12:03:14 +1000761 error("The %s host key for %s has changed,", type, host);
Damien Miller95def091999-11-25 00:26:21 +1100762 error("and the key for the according IP address %s", ip);
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000763 error("%s. This could either mean that", key_msg);
Damien Miller95def091999-11-25 00:26:21 +1100764 error("DNS SPOOFING is happening or the IP address for the host");
Ben Lindstrom46c16222000-12-22 01:43:59 +0000765 error("and its host key have changed at the same time.");
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000766 if (ip_status != HOST_NEW)
Ben Lindstrom46c16222000-12-22 01:43:59 +0000767 error("Offending key for IP in %s:%d", ip_file, ip_line);
Damien Miller95def091999-11-25 00:26:21 +1100768 }
769 /* The host key has changed. */
Damien Miller5a388972003-11-17 21:10:47 +1100770 warn_changed_key(host_key);
Damien Miller95def091999-11-25 00:26:21 +1100771 error("Add correct host key in %.100s to get rid of this message.",
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000772 user_hostfile);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000773 error("Offending key in %s:%d", host_file, host_line);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000774
Damien Miller5428f641999-11-25 11:54:57 +1100775 /*
776 * If strict host key checking is in use, the user will have
777 * to edit the key manually and we can only abort.
778 */
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000779 if (options.strict_host_key_checking) {
780 error("%s host key for %.200s has changed and you have "
781 "requested strict checking.", type, host);
782 goto fail;
783 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000784
Damien Miller5428f641999-11-25 11:54:57 +1100785 /*
786 * If strict host key checking has not been requested, allow
Damien Miller941ac452003-06-04 20:31:53 +1000787 * the connection but without MITM-able authentication or
Damien Miller5428f641999-11-25 11:54:57 +1100788 * agent forwarding.
789 */
Damien Miller95def091999-11-25 00:26:21 +1100790 if (options.password_authentication) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000791 error("Password authentication is disabled to avoid "
792 "man-in-the-middle attacks.");
Damien Miller95def091999-11-25 00:26:21 +1100793 options.password_authentication = 0;
794 }
Damien Miller941ac452003-06-04 20:31:53 +1000795 if (options.kbd_interactive_authentication) {
796 error("Keyboard-interactive authentication is disabled"
797 " to avoid man-in-the-middle attacks.");
798 options.kbd_interactive_authentication = 0;
799 options.challenge_response_authentication = 0;
800 }
801 if (options.challenge_response_authentication) {
802 error("Challenge/response authentication is disabled"
803 " to avoid man-in-the-middle attacks.");
804 options.challenge_response_authentication = 0;
805 }
Damien Miller95def091999-11-25 00:26:21 +1100806 if (options.forward_agent) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000807 error("Agent forwarding is disabled to avoid "
808 "man-in-the-middle attacks.");
Damien Miller95def091999-11-25 00:26:21 +1100809 options.forward_agent = 0;
810 }
Ben Lindstromc72745a2000-12-02 19:03:54 +0000811 if (options.forward_x11) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000812 error("X11 forwarding is disabled to avoid "
813 "man-in-the-middle attacks.");
Ben Lindstromc72745a2000-12-02 19:03:54 +0000814 options.forward_x11 = 0;
815 }
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000816 if (options.num_local_forwards > 0 ||
817 options.num_remote_forwards > 0) {
818 error("Port forwarding is disabled to avoid "
819 "man-in-the-middle attacks.");
820 options.num_local_forwards =
Damien Miller9f0f5c62001-12-21 14:45:46 +1100821 options.num_remote_forwards = 0;
Ben Lindstromc72745a2000-12-02 19:03:54 +0000822 }
Damien Miller5428f641999-11-25 11:54:57 +1100823 /*
824 * XXX Should permit the user to change to use the new id.
825 * This could be done by converting the host key to an
826 * identifying sentence, tell that the host identifies itself
827 * by that sentence, and ask the user if he/she whishes to
828 * accept the authentication.
829 */
Damien Miller95def091999-11-25 00:26:21 +1100830 break;
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000831 case HOST_FOUND:
832 fatal("internal error");
833 break;
Damien Miller95def091999-11-25 00:26:21 +1100834 }
Ben Lindstromc72745a2000-12-02 19:03:54 +0000835
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000836 if (options.check_host_ip && host_status != HOST_CHANGED &&
837 ip_status == HOST_CHANGED) {
Damien Miller49d795c2002-01-22 23:34:12 +1100838 snprintf(msg, sizeof(msg),
839 "Warning: the %s host key for '%.200s' "
840 "differs from the key for the IP address '%.128s'"
841 "\nOffending key for IP in %s:%d",
842 type, host, ip, ip_file, ip_line);
843 if (host_status == HOST_OK) {
844 len = strlen(msg);
845 snprintf(msg + len, sizeof(msg) - len,
846 "\nMatching host key in %s:%d",
Ben Lindstromcb72e4f2002-06-21 00:41:51 +0000847 host_file, host_line);
Damien Miller49d795c2002-01-22 23:34:12 +1100848 }
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000849 if (options.strict_host_key_checking == 1) {
Damien Millerab2db412003-06-02 19:09:13 +1000850 logit("%s", msg);
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000851 error("Exiting, you have requested strict checking.");
852 goto fail;
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000853 } else if (options.strict_host_key_checking == 2) {
Damien Miller49d795c2002-01-22 23:34:12 +1100854 strlcat(msg, "\nAre you sure you want "
855 "to continue connecting (yes/no)? ", sizeof(msg));
856 if (!confirm(msg))
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000857 goto fail;
Damien Miller49d795c2002-01-22 23:34:12 +1100858 } else {
Damien Millerab2db412003-06-02 19:09:13 +1000859 logit("%s", msg);
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000860 }
861 }
862
Ben Lindstromc72745a2000-12-02 19:03:54 +0000863 xfree(ip);
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000864 return 0;
865
866fail:
867 xfree(ip);
868 return -1;
869}
870
Damien Miller37876e92003-05-15 10:19:46 +1000871/* returns 0 if key verifies or -1 if key does NOT verify */
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000872int
873verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
874{
875 struct stat st;
Damien Miller150b5572003-11-17 21:19:29 +1100876 int flags = 0;
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000877
Damien Miller150b5572003-11-17 21:19:29 +1100878 if (options.verify_host_key_dns &&
879 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
880
881 if (flags & DNS_VERIFY_FOUND) {
882
883 if (options.verify_host_key_dns == 1 &&
884 flags & DNS_VERIFY_MATCH &&
885 flags & DNS_VERIFY_SECURE)
886 return 0;
887
888 if (flags & DNS_VERIFY_MATCH) {
889 matching_host_key_dns = 1;
890 } else {
891 warn_changed_key(host_key);
892 error("Update the SSHFP RR in DNS with the new "
893 "host key to get rid of this message.");
894 }
Damien Miller37876e92003-05-15 10:19:46 +1000895 }
896 }
Damien Miller37876e92003-05-15 10:19:46 +1000897
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000898 /* return ok if the key can be found in an old keyfile */
899 if (stat(options.system_hostfile2, &st) == 0 ||
900 stat(options.user_hostfile2, &st) == 0) {
901 if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
902 options.user_hostfile2, options.system_hostfile2) == 0)
903 return 0;
904 }
905 return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
906 options.user_hostfile, options.system_hostfile);
Damien Millera34a28b1999-12-14 10:47:15 +1100907}
Damien Miller037a0dc1999-12-07 15:38:31 +1100908
Damien Miller396691a2000-01-20 22:44:08 +1100909/*
910 * Starts a dialog with the server, and authenticates the current user on the
911 * server. This does not need any extra privileges. The basic connection
912 * to the server must already have been established before this is called.
913 * If login fails, this function prints an error and never returns.
914 * This function does not require super-user privileges.
915 */
916void
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000917ssh_login(Sensitive *sensitive, const char *orighost,
Ben Lindstrom3fcf1a22001-04-08 18:26:59 +0000918 struct sockaddr *hostaddr, struct passwd *pw)
Damien Miller396691a2000-01-20 22:44:08 +1100919{
920 char *host, *cp;
Damien Millereba71ba2000-04-29 23:57:08 +1000921 char *server_user, *local_user;
922
Damien Millereba71ba2000-04-29 23:57:08 +1000923 local_user = xstrdup(pw->pw_name);
924 server_user = options.user ? options.user : local_user;
Damien Miller396691a2000-01-20 22:44:08 +1100925
926 /* Convert the user-supplied hostname into all lowercase. */
927 host = xstrdup(orighost);
928 for (cp = host; *cp; cp++)
929 if (isupper(*cp))
930 *cp = tolower(*cp);
931
932 /* Exchange protocol version identification strings with the server. */
933 ssh_exchange_identification();
934
935 /* Put the connection into non-blocking mode. */
936 packet_set_nonblocking();
937
Damien Miller396691a2000-01-20 22:44:08 +1100938 /* key exchange */
Damien Miller396691a2000-01-20 22:44:08 +1100939 /* authenticate user */
Damien Miller1383bd82000-04-06 12:32:37 +1000940 if (compat20) {
941 ssh_kex2(host, hostaddr);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000942 ssh_userauth2(local_user, server_user, host, sensitive);
Damien Miller1383bd82000-04-06 12:32:37 +1000943 } else {
Damien Miller1383bd82000-04-06 12:32:37 +1000944 ssh_kex(host, hostaddr);
Ben Lindstrom1bad2562002-06-06 19:57:33 +0000945 ssh_userauth1(local_user, server_user, host, sensitive);
Damien Miller1383bd82000-04-06 12:32:37 +1000946 }
Damien Miller396691a2000-01-20 22:44:08 +1100947}
Damien Miller79438cc2001-02-16 12:34:57 +1100948
949void
950ssh_put_password(char *password)
951{
952 int size;
953 char *padded;
954
Ben Lindstromd20d0f32001-03-10 17:22:20 +0000955 if (datafellows & SSH_BUG_PASSWORDPAD) {
Ben Lindstrom664408d2001-06-09 01:42:01 +0000956 packet_put_cstring(password);
Ben Lindstromd20d0f32001-03-10 17:22:20 +0000957 return;
958 }
Damien Miller79438cc2001-02-16 12:34:57 +1100959 size = roundup(strlen(password) + 1, 32);
960 padded = xmalloc(size);
961 memset(padded, 0, size);
962 strlcpy(padded, password, size);
963 packet_put_string(padded, size);
964 memset(padded, 0, size);
965 xfree(padded);
966}
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000967
968static int
969show_key_from_file(const char *file, const char *host, int keytype)
970{
971 Key *found;
972 char *fp;
973 int line, ret;
974
975 found = key_new(keytype);
976 if ((ret = lookup_key_in_hostfile_by_type(file, host,
977 keytype, found, &line))) {
978 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
Damien Miller996acd22003-04-09 20:59:48 +1000979 logit("WARNING: %s key found for host %s\n"
Ben Lindstrom4b99be82002-08-01 01:26:29 +0000980 "in %s:%d\n"
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000981 "%s key fingerprint %s.",
982 key_type(found), host, file, line,
983 key_type(found), fp);
984 xfree(fp);
985 }
986 key_free(found);
987 return (ret);
988}
989
990/* print all known host keys for a given host, but skip keys of given type */
991static int
992show_other_keys(const char *host, Key *key)
993{
994 int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
995 int i, found = 0;
996
997 for (i = 0; type[i] != -1; i++) {
998 if (type[i] == key->type)
999 continue;
1000 if (type[i] != KEY_RSA1 &&
1001 show_key_from_file(options.user_hostfile2, host, type[i])) {
1002 found = 1;
1003 continue;
1004 }
1005 if (type[i] != KEY_RSA1 &&
1006 show_key_from_file(options.system_hostfile2, host, type[i])) {
1007 found = 1;
1008 continue;
1009 }
1010 if (show_key_from_file(options.user_hostfile, host, type[i])) {
1011 found = 1;
1012 continue;
1013 }
1014 if (show_key_from_file(options.system_hostfile, host, type[i])) {
1015 found = 1;
1016 continue;
1017 }
1018 debug2("no key of type %d for host %s", type[i], host);
1019 }
1020 return (found);
1021}
Damien Miller5a388972003-11-17 21:10:47 +11001022
1023static void
1024warn_changed_key(Key *host_key)
1025{
1026 char *fp;
Damien Miller8f746ec2003-11-17 21:11:15 +11001027 const char *type = key_type(host_key);
Damien Miller5a388972003-11-17 21:10:47 +11001028
1029 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1030
1031 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1032 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1033 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1034 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1035 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1036 error("It is also possible that the %s host key has just been changed.", type);
1037 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1038 type, fp);
1039 error("Please contact your system administrator.");
1040
1041 xfree(fp);
Damien Miller5a388972003-11-17 21:10:47 +11001042}
Damien Millerd27b9472005-12-13 19:29:02 +11001043
1044/*
1045 * Execute a local command
1046 */
1047int
1048ssh_local_cmd(const char *args)
1049{
1050 char *shell;
1051 pid_t pid;
1052 int status;
1053
1054 if (!options.permit_local_command ||
1055 args == NULL || !*args)
1056 return (1);
1057
1058 if ((shell = getenv("SHELL")) == NULL)
1059 shell = _PATH_BSHELL;
1060
1061 pid = fork();
1062 if (pid == 0) {
1063 debug3("Executing %s -c \"%s\"", shell, args);
1064 execl(shell, shell, "-c", args, (char *)NULL);
1065 error("Couldn't execute %s -c \"%s\": %s",
1066 shell, args, strerror(errno));
1067 _exit(1);
1068 } else if (pid == -1)
1069 fatal("fork failed: %.100s", strerror(errno));
1070 while (waitpid(pid, &status, 0) == -1)
1071 if (errno != EINTR)
1072 fatal("Couldn't wait for child: %s", strerror(errno));
1073
1074 if (!WIFEXITED(status))
1075 return (1);
1076
1077 return (WEXITSTATUS(status));
1078}