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deraadt@openbsd.orgce445b02015-08-20 22:32:42 +00001/* $OpenBSD: sshconnect.c,v 1.263 2015/08/20 22:32:42 deraadt Exp $ */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10002/*
Damien Miller95def091999-11-25 00:26:21 +11003 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11006 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
Damien Millere4340be2000-09-16 13:29:08 +11008 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
Damien Miller95def091999-11-25 00:26:21 +110014 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100015
16#include "includes.h"
Damien Miller9cf6d072006-03-15 11:29:24 +110017
deraadt@openbsd.org087266e2015-01-20 23:14:00 +000018#include <sys/param.h> /* roundup */
Damien Miller9cf6d072006-03-15 11:29:24 +110019#include <sys/types.h>
20#include <sys/wait.h>
Damien Millerf17883e2006-03-15 11:45:54 +110021#include <sys/stat.h>
Damien Miller8ec8c3e2006-07-10 20:35:38 +100022#include <sys/socket.h>
Damien Miller9aec9192006-08-05 10:57:45 +100023#ifdef HAVE_SYS_TIME_H
24# include <sys/time.h>
25#endif
Damien Miller8ec8c3e2006-07-10 20:35:38 +100026
27#include <netinet/in.h>
Darren Tucker46aa3e02006-09-02 15:32:40 +100028#include <arpa/inet.h>
Damien Miller03e20032006-03-15 11:16:59 +110029
Damien Millerc7b06362006-03-15 11:53:45 +110030#include <ctype.h>
Darren Tucker39972492006-07-12 22:22:46 +100031#include <errno.h>
Darren Tucker6e7fe1c2010-01-08 17:07:22 +110032#include <fcntl.h>
Damien Millerb8fe89c2006-07-24 14:51:00 +100033#include <netdb.h>
Damien Miller6645e7a2006-03-15 14:42:54 +110034#ifdef HAVE_PATHS_H
Damien Miller03e20032006-03-15 11:16:59 +110035#include <paths.h>
Damien Miller6645e7a2006-03-15 14:42:54 +110036#endif
Damien Miller9f2abc42006-07-10 20:53:08 +100037#include <pwd.h>
Damien Miller9c0c31d2010-10-12 13:30:44 +110038#include <signal.h>
Damien Millerded319c2006-09-01 15:38:36 +100039#include <stdarg.h>
Damien Millera7a73ee2006-08-05 11:37:59 +100040#include <stdio.h>
Damien Millere7a1e5c2006-08-05 11:34:19 +100041#include <stdlib.h>
Damien Millere3476ed2006-07-24 14:13:33 +100042#include <string.h>
Damien Millere6b3b612006-07-24 14:01:23 +100043#include <unistd.h>
Damien Millerd4a8b7e1999-10-27 13:42:43 +100044
Damien Millerd4a8b7e1999-10-27 13:42:43 +100045#include "xmalloc.h"
Damien Millerd7834352006-08-05 12:39:39 +100046#include "key.h"
47#include "hostfile.h"
48#include "ssh.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100049#include "rsa.h"
Damien Miller1383bd82000-04-06 12:32:37 +100050#include "buffer.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100051#include "packet.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100052#include "uidswap.h"
53#include "compat.h"
Damien Miller450a7a12000-03-26 13:04:51 +100054#include "key.h"
Damien Millereba71ba2000-04-29 23:57:08 +100055#include "sshconnect.h"
Damien Miller450a7a12000-03-26 13:04:51 +100056#include "hostfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000057#include "log.h"
Damien Miller7acefbb2014-07-18 14:11:24 +100058#include "misc.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000059#include "readconf.h"
60#include "atomicio.h"
Damien Miller37876e92003-05-15 10:19:46 +100061#include "dns.h"
Darren Tuckerc5564e12009-06-21 18:53:53 +100062#include "roaming.h"
Damien Miller1262b662013-08-21 02:44:24 +100063#include "monitor_fdpass.h"
Damien Miller0a80ca12010-02-27 07:55:05 +110064#include "ssh2.h"
Damien Millerb7576772006-07-10 20:23:39 +100065#include "version.h"
djm@openbsd.org5e39a492014-12-04 02:24:32 +000066#include "authfile.h"
67#include "ssherr.h"
Damien Miller37876e92003-05-15 10:19:46 +100068
Damien Millereba71ba2000-04-29 23:57:08 +100069char *client_version_string = NULL;
70char *server_version_string = NULL;
Damien Miller6b37fbb2014-07-04 08:59:24 +100071Key *previous_host_key = NULL;
Damien Miller1383bd82000-04-06 12:32:37 +100072
Damien Millerc1af1d52005-11-05 15:08:57 +110073static int matching_host_key_dns = 0;
Damien Miller7392ae62003-06-11 22:05:25 +100074
Damien Millera41ccca2010-10-07 22:07:32 +110075static pid_t proxy_command_pid = 0;
76
Ben Lindstromf9c48842002-06-11 16:37:51 +000077/* import */
Damien Milleraae6c611999-12-06 11:47:28 +110078extern Options options;
Damien Miller34132e52000-01-14 15:45:46 +110079extern char *__progname;
Ben Lindstromf9c48842002-06-11 16:37:51 +000080extern uid_t original_real_uid;
81extern uid_t original_effective_uid;
Damien Milleraae6c611999-12-06 11:47:28 +110082
Damien Millerd925dcd2010-12-01 12:21:51 +110083static int show_other_keys(struct hostkeys *, Key *);
Damien Miller5a388972003-11-17 21:10:47 +110084static void warn_changed_key(Key *);
Ben Lindstrom3ed66402002-08-01 01:21:56 +000085
Damien Miller1262b662013-08-21 02:44:24 +100086/* Expand a proxy command */
87static char *
88expand_proxy_command(const char *proxy_command, const char *user,
89 const char *host, int port)
90{
91 char *tmp, *ret, strport[NI_MAXSERV];
92
Damien Miller0faf7472013-10-17 11:47:23 +110093 snprintf(strport, sizeof strport, "%d", port);
Damien Miller1262b662013-08-21 02:44:24 +100094 xasprintf(&tmp, "exec %s", proxy_command);
95 ret = percent_expand(tmp, "h", host, "p", strport,
96 "r", options.user, (char *)NULL);
97 free(tmp);
98 return ret;
99}
100
101/*
102 * Connect to the given ssh server using a proxy command that passes a
103 * a connected fd back to us.
104 */
105static int
106ssh_proxy_fdpass_connect(const char *host, u_short port,
107 const char *proxy_command)
108{
109 char *command_string;
110 int sp[2], sock;
111 pid_t pid;
112 char *shell;
113
114 if ((shell = getenv("SHELL")) == NULL)
115 shell = _PATH_BSHELL;
116
117 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
118 fatal("Could not create socketpair to communicate with "
119 "proxy dialer: %.100s", strerror(errno));
120
121 command_string = expand_proxy_command(proxy_command, options.user,
122 host, port);
123 debug("Executing proxy dialer command: %.500s", command_string);
124
125 /* Fork and execute the proxy command. */
126 if ((pid = fork()) == 0) {
127 char *argv[10];
128
129 /* Child. Permanently give up superuser privileges. */
130 permanently_drop_suid(original_real_uid);
131
132 close(sp[1]);
133 /* Redirect stdin and stdout. */
134 if (sp[0] != 0) {
135 if (dup2(sp[0], 0) < 0)
136 perror("dup2 stdin");
137 }
138 if (sp[0] != 1) {
139 if (dup2(sp[0], 1) < 0)
140 perror("dup2 stdout");
141 }
142 if (sp[0] >= 2)
143 close(sp[0]);
144
145 /*
146 * Stderr is left as it is so that error messages get
147 * printed on the user's terminal.
148 */
149 argv[0] = shell;
150 argv[1] = "-c";
151 argv[2] = command_string;
152 argv[3] = NULL;
153
154 /*
155 * Execute the proxy command.
156 * Note that we gave up any extra privileges above.
157 */
158 execv(argv[0], argv);
159 perror(argv[0]);
160 exit(1);
161 }
162 /* Parent. */
163 if (pid < 0)
164 fatal("fork failed: %.100s", strerror(errno));
165 close(sp[0]);
166 free(command_string);
167
168 if ((sock = mm_receive_fd(sp[1])) == -1)
169 fatal("proxy dialer did not pass back a connection");
170
171 while (waitpid(pid, NULL, 0) == -1)
172 if (errno != EINTR)
173 fatal("Couldn't wait for child: %s", strerror(errno));
174
175 /* Set the connection file descriptors. */
176 packet_set_connection(sock, sock);
Damien Miller1262b662013-08-21 02:44:24 +1000177
178 return 0;
179}
180
Damien Miller95def091999-11-25 00:26:21 +1100181/*
182 * Connect to the given ssh server using a proxy command.
183 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000184static int
Ben Lindstromf9c48842002-06-11 16:37:51 +0000185ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000186{
Damien Miller1262b662013-08-21 02:44:24 +1000187 char *command_string;
Damien Miller95def091999-11-25 00:26:21 +1100188 int pin[2], pout[2];
Damien Miller166fca82000-04-20 07:42:21 +1000189 pid_t pid;
Damien Miller1262b662013-08-21 02:44:24 +1000190 char *shell;
Damien Miller1d824ab2007-09-17 11:58:04 +1000191
Damien Miller38d9a962010-10-07 22:07:11 +1100192 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
Damien Miller1d824ab2007-09-17 11:58:04 +1000193 shell = _PATH_BSHELL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000194
Damien Miller95def091999-11-25 00:26:21 +1100195 /* Create pipes for communicating with the proxy. */
196 if (pipe(pin) < 0 || pipe(pout) < 0)
197 fatal("Could not create pipes to communicate with the proxy: %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +1100198 strerror(errno));
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000199
Damien Miller1262b662013-08-21 02:44:24 +1000200 command_string = expand_proxy_command(proxy_command, options.user,
201 host, port);
Damien Miller95def091999-11-25 00:26:21 +1100202 debug("Executing proxy command: %.500s", command_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000203
Damien Miller95def091999-11-25 00:26:21 +1100204 /* Fork and execute the proxy command. */
205 if ((pid = fork()) == 0) {
206 char *argv[10];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000207
Damien Miller95def091999-11-25 00:26:21 +1100208 /* Child. Permanently give up superuser privileges. */
Damien Miller2e5fe882006-06-13 13:10:00 +1000209 permanently_drop_suid(original_real_uid);
Damien Miller95def091999-11-25 00:26:21 +1100210
211 /* Redirect stdin and stdout. */
212 close(pin[1]);
213 if (pin[0] != 0) {
214 if (dup2(pin[0], 0) < 0)
215 perror("dup2 stdin");
216 close(pin[0]);
217 }
218 close(pout[0]);
219 if (dup2(pout[1], 1) < 0)
220 perror("dup2 stdout");
221 /* Cannot be 1 because pin allocated two descriptors. */
222 close(pout[1]);
223
224 /* Stderr is left as it is so that error messages get
225 printed on the user's terminal. */
Damien Miller1d824ab2007-09-17 11:58:04 +1000226 argv[0] = shell;
Damien Miller95def091999-11-25 00:26:21 +1100227 argv[1] = "-c";
228 argv[2] = command_string;
229 argv[3] = NULL;
230
231 /* Execute the proxy command. Note that we gave up any
232 extra privileges above. */
Damien Miller6fb6fd52011-01-16 23:17:45 +1100233 signal(SIGPIPE, SIG_DFL);
Kevin Stevesfcd5d602001-01-07 11:45:22 +0000234 execv(argv[0], argv);
235 perror(argv[0]);
Damien Miller95def091999-11-25 00:26:21 +1100236 exit(1);
237 }
238 /* Parent. */
239 if (pid < 0)
240 fatal("fork failed: %.100s", strerror(errno));
Damien Miller8c4e18a2002-09-19 12:05:02 +1000241 else
242 proxy_command_pid = pid; /* save pid to clean up later */
Damien Miller95def091999-11-25 00:26:21 +1100243
244 /* Close child side of the descriptors. */
245 close(pin[0]);
246 close(pout[1]);
247
248 /* Free the command name. */
Darren Tuckera627d422013-06-02 07:31:17 +1000249 free(command_string);
Damien Miller95def091999-11-25 00:26:21 +1100250
251 /* Set the connection file descriptors. */
252 packet_set_connection(pout[0], pin[1]);
253
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000254 /* Indicate OK return */
255 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000256}
257
Damien Millera41ccca2010-10-07 22:07:32 +1100258void
259ssh_kill_proxy_command(void)
260{
261 /*
262 * Send SIGHUP to proxy command if used. We don't wait() in
263 * case it hangs and instead rely on init to reap the child
264 */
265 if (proxy_command_pid > 1)
Damien Miller45fcdaa2010-10-07 22:07:58 +1100266 kill(proxy_command_pid, SIGHUP);
Damien Millera41ccca2010-10-07 22:07:32 +1100267}
268
Damien Miller95def091999-11-25 00:26:21 +1100269/*
270 * Creates a (possibly privileged) socket for use as the ssh connection.
271 */
Ben Lindstrombba81212001-06-25 05:01:22 +0000272static int
Damien Miller2372ace2003-05-14 13:42:23 +1000273ssh_create_socket(int privileged, struct addrinfo *ai)
Damien Miller95def091999-11-25 00:26:21 +1100274{
Darren Tuckere6e52f82013-10-10 10:28:07 +1100275 int sock, r, gaierr;
Damien Millerd1a7a9c2014-02-07 09:24:33 +1100276 struct addrinfo hints, *res = NULL;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000277
Darren Tucker7bd98e72010-01-10 10:31:12 +1100278 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
Darren Tucker6e7fe1c2010-01-08 17:07:22 +1100279 if (sock < 0) {
Darren Tuckere6e52f82013-10-10 10:28:07 +1100280 error("socket: %s", strerror(errno));
Darren Tucker6e7fe1c2010-01-08 17:07:22 +1100281 return -1;
282 }
283 fcntl(sock, F_SETFD, FD_CLOEXEC);
Ben Lindstrome0f88042001-04-30 13:06:24 +0000284
285 /* Bind the socket to an alternative local IP address */
Darren Tuckere6e52f82013-10-10 10:28:07 +1100286 if (options.bind_address == NULL && !privileged)
Ben Lindstrome0f88042001-04-30 13:06:24 +0000287 return sock;
288
Damien Millerd1a7a9c2014-02-07 09:24:33 +1100289 if (options.bind_address) {
290 memset(&hints, 0, sizeof(hints));
291 hints.ai_family = ai->ai_family;
292 hints.ai_socktype = ai->ai_socktype;
293 hints.ai_protocol = ai->ai_protocol;
294 hints.ai_flags = AI_PASSIVE;
295 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
296 if (gaierr) {
297 error("getaddrinfo: %s: %s", options.bind_address,
298 ssh_gai_strerror(gaierr));
299 close(sock);
300 return -1;
301 }
Ben Lindstrome0f88042001-04-30 13:06:24 +0000302 }
Darren Tuckere6e52f82013-10-10 10:28:07 +1100303 /*
304 * If we are running as root and want to connect to a privileged
305 * port, bind our own socket to a privileged port.
306 */
307 if (privileged) {
308 PRIV_START;
Damien Millerd1a7a9c2014-02-07 09:24:33 +1100309 r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
Darren Tuckere6e52f82013-10-10 10:28:07 +1100310 PRIV_END;
311 if (r < 0) {
312 error("bindresvport_sa: af=%d %s", ai->ai_family,
313 strerror(errno));
314 goto fail;
315 }
316 } else {
317 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
318 error("bind: %s: %s", options.bind_address,
319 strerror(errno));
320 fail:
321 close(sock);
322 freeaddrinfo(res);
323 return -1;
324 }
Ben Lindstrome0f88042001-04-30 13:06:24 +0000325 }
Damien Millerd1a7a9c2014-02-07 09:24:33 +1100326 if (res != NULL)
327 freeaddrinfo(res);
Damien Miller95def091999-11-25 00:26:21 +1100328 return sock;
329}
330
Damien Millerb78d5eb2003-05-16 11:39:04 +1000331static int
332timeout_connect(int sockfd, const struct sockaddr *serv_addr,
Damien Miller67bd0622007-09-17 12:06:57 +1000333 socklen_t addrlen, int *timeoutp)
Damien Millerb78d5eb2003-05-16 11:39:04 +1000334{
335 fd_set *fdset;
Damien Miller67bd0622007-09-17 12:06:57 +1000336 struct timeval tv, t_start;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000337 socklen_t optlen;
Damien Miller07d86be2006-03-26 14:19:21 +1100338 int optval, rc, result = -1;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000339
Damien Miller67bd0622007-09-17 12:06:57 +1000340 gettimeofday(&t_start, NULL);
341
342 if (*timeoutp <= 0) {
343 result = connect(sockfd, serv_addr, addrlen);
344 goto done;
345 }
Damien Millerb78d5eb2003-05-16 11:39:04 +1000346
Damien Millerf6723f02004-01-27 21:21:27 +1100347 set_nonblock(sockfd);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000348 rc = connect(sockfd, serv_addr, addrlen);
Damien Millerf6723f02004-01-27 21:21:27 +1100349 if (rc == 0) {
350 unset_nonblock(sockfd);
Damien Miller67bd0622007-09-17 12:06:57 +1000351 result = 0;
352 goto done;
Damien Millerf6723f02004-01-27 21:21:27 +1100353 }
Damien Miller67bd0622007-09-17 12:06:57 +1000354 if (errno != EINPROGRESS) {
355 result = -1;
356 goto done;
357 }
Damien Millerb78d5eb2003-05-16 11:39:04 +1000358
deraadt@openbsd.orgce445b02015-08-20 22:32:42 +0000359 fdset = xcalloc(howmany(sockfd + 1, NFDBITS),
Damien Miller07d86be2006-03-26 14:19:21 +1100360 sizeof(fd_mask));
Damien Millerb78d5eb2003-05-16 11:39:04 +1000361 FD_SET(sockfd, fdset);
Damien Miller67bd0622007-09-17 12:06:57 +1000362 ms_to_timeval(&tv, *timeoutp);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000363
Darren Tucker47eede72005-03-14 23:08:12 +1100364 for (;;) {
Damien Millerb78d5eb2003-05-16 11:39:04 +1000365 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
366 if (rc != -1 || errno != EINTR)
367 break;
368 }
369
Darren Tucker47eede72005-03-14 23:08:12 +1100370 switch (rc) {
Damien Millerb78d5eb2003-05-16 11:39:04 +1000371 case 0:
372 /* Timed out */
373 errno = ETIMEDOUT;
Damien Miller08293fa2003-05-23 18:44:41 +1000374 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000375 case -1:
376 /* Select error */
Damien Millera8e06ce2003-11-21 23:48:55 +1100377 debug("select: %s", strerror(errno));
Damien Miller08293fa2003-05-23 18:44:41 +1000378 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000379 case 1:
380 /* Completed or failed */
381 optval = 0;
382 optlen = sizeof(optval);
Damien Millera8e06ce2003-11-21 23:48:55 +1100383 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
Darren Tuckerbd5361b2003-09-22 20:59:16 +1000384 &optlen) == -1) {
Damien Millera8e06ce2003-11-21 23:48:55 +1100385 debug("getsockopt: %s", strerror(errno));
Damien Miller08293fa2003-05-23 18:44:41 +1000386 break;
Darren Tuckerbd5361b2003-09-22 20:59:16 +1000387 }
Damien Millerb78d5eb2003-05-16 11:39:04 +1000388 if (optval != 0) {
389 errno = optval;
Damien Miller08293fa2003-05-23 18:44:41 +1000390 break;
Damien Millerb78d5eb2003-05-16 11:39:04 +1000391 }
Damien Miller08293fa2003-05-23 18:44:41 +1000392 result = 0;
Damien Millerf6723f02004-01-27 21:21:27 +1100393 unset_nonblock(sockfd);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000394 break;
395 default:
396 /* Should not occur */
397 fatal("Bogus return (%d) from select()", rc);
398 }
399
Darren Tuckera627d422013-06-02 07:31:17 +1000400 free(fdset);
Damien Miller67bd0622007-09-17 12:06:57 +1000401
402 done:
403 if (result == 0 && *timeoutp > 0) {
404 ms_subtract_diff(&t_start, timeoutp);
405 if (*timeoutp <= 0) {
406 errno = ETIMEDOUT;
407 result = -1;
408 }
409 }
410
Damien Miller08293fa2003-05-23 18:44:41 +1000411 return (result);
Damien Millerb78d5eb2003-05-16 11:39:04 +1000412}
413
Damien Miller95def091999-11-25 00:26:21 +1100414/*
Damien Miller34132e52000-01-14 15:45:46 +1100415 * Opens a TCP/IP connection to the remote server on the given host.
416 * The address of the remote host will be returned in hostaddr.
Ben Lindstromf9c48842002-06-11 16:37:51 +0000417 * If port is 0, the default port will be used. If needpriv is true,
Damien Miller95def091999-11-25 00:26:21 +1100418 * a privileged port will be allocated to make the connection.
Ben Lindstromf9c48842002-06-11 16:37:51 +0000419 * This requires super-user privileges if needpriv is true.
Damien Miller95def091999-11-25 00:26:21 +1100420 * Connection_attempts specifies the maximum number of tries (one per
421 * second). If proxy_command is non-NULL, it specifies the command (with %h
422 * and %p substituted for host and port, respectively) to use to contact
423 * the daemon.
424 */
Damien Miller0faf7472013-10-17 11:47:23 +1100425static int
426ssh_connect_direct(const char *host, struct addrinfo *aitop,
427 struct sockaddr_storage *hostaddr, u_short port, int family,
428 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
Damien Miller95def091999-11-25 00:26:21 +1100429{
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000430 int on = 1;
431 int sock = -1, attempt;
432 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
Damien Miller0faf7472013-10-17 11:47:23 +1100433 struct addrinfo *ai;
Damien Miller95def091999-11-25 00:26:21 +1100434
Ben Lindstrom064496f2002-12-23 02:04:22 +0000435 debug2("ssh_connect: needpriv %d", needpriv);
Damien Miller95def091999-11-25 00:26:21 +1100436
Damien Miller56e5e6a2006-04-23 12:08:59 +1000437 for (attempt = 0; attempt < connection_attempts; attempt++) {
Damien Millerf4bcd102006-10-24 03:02:23 +1000438 if (attempt > 0) {
439 /* Sleep a moment before retrying. */
440 sleep(1);
Damien Miller95def091999-11-25 00:26:21 +1100441 debug("Trying again...");
Damien Millerf4bcd102006-10-24 03:02:23 +1000442 }
Damien Miller56e5e6a2006-04-23 12:08:59 +1000443 /*
444 * Loop through addresses for this host, and try each one in
445 * sequence until the connection succeeds.
446 */
Damien Miller34132e52000-01-14 15:45:46 +1100447 for (ai = aitop; ai; ai = ai->ai_next) {
Damien Miller0faf7472013-10-17 11:47:23 +1100448 if (ai->ai_family != AF_INET &&
449 ai->ai_family != AF_INET6)
Damien Miller34132e52000-01-14 15:45:46 +1100450 continue;
451 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
452 ntop, sizeof(ntop), strport, sizeof(strport),
453 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
454 error("ssh_connect: getnameinfo failed");
455 continue;
456 }
457 debug("Connecting to %.200s [%.100s] port %s.",
458 host, ntop, strport);
Damien Miller95def091999-11-25 00:26:21 +1100459
Damien Miller34132e52000-01-14 15:45:46 +1100460 /* Create a socket for connecting. */
Damien Miller2372ace2003-05-14 13:42:23 +1000461 sock = ssh_create_socket(needpriv, ai);
Damien Miller34132e52000-01-14 15:45:46 +1100462 if (sock < 0)
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000463 /* Any error is already output */
Damien Miller34132e52000-01-14 15:45:46 +1100464 continue;
Damien Miller95def091999-11-25 00:26:21 +1100465
Damien Millerb78d5eb2003-05-16 11:39:04 +1000466 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
Damien Miller67bd0622007-09-17 12:06:57 +1000467 timeout_ms) >= 0) {
Damien Miller34132e52000-01-14 15:45:46 +1100468 /* Successful connection. */
Ben Lindstroma3700052001-04-05 23:26:32 +0000469 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
Damien Miller95def091999-11-25 00:26:21 +1100470 break;
Damien Miller34132e52000-01-14 15:45:46 +1100471 } else {
Ben Lindstrom728aa7e2002-07-15 17:48:11 +0000472 debug("connect to address %s port %s: %s",
473 ntop, strport, strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100474 close(sock);
Damien Miller56e5e6a2006-04-23 12:08:59 +1000475 sock = -1;
Damien Miller95def091999-11-25 00:26:21 +1100476 }
Damien Miller95def091999-11-25 00:26:21 +1100477 }
Damien Miller56e5e6a2006-04-23 12:08:59 +1000478 if (sock != -1)
Damien Miller34132e52000-01-14 15:45:46 +1100479 break; /* Successful connection. */
Damien Miller95def091999-11-25 00:26:21 +1100480 }
Damien Miller34132e52000-01-14 15:45:46 +1100481
Damien Miller95def091999-11-25 00:26:21 +1100482 /* Return failure if we didn't get a successful connection. */
Damien Miller56e5e6a2006-04-23 12:08:59 +1000483 if (sock == -1) {
Darren Tuckerb2161e32005-01-20 11:00:46 +1100484 error("ssh: connect to host %s port %s: %s",
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000485 host, strport, strerror(errno));
Darren Tuckerb2161e32005-01-20 11:00:46 +1100486 return (-1);
Ben Lindstroma6cd75c2002-07-11 04:00:19 +0000487 }
Damien Miller95def091999-11-25 00:26:21 +1100488
489 debug("Connection established.");
490
Damien Miller12c150e2003-12-17 16:31:10 +1100491 /* Set SO_KEEPALIVE if requested. */
Damien Miller67bd0622007-09-17 12:06:57 +1000492 if (want_keepalive &&
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000493 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
494 sizeof(on)) < 0)
495 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100496
497 /* Set the connection. */
498 packet_set_connection(sock, sock);
499
Ben Lindstromf9cedb92001-08-06 21:07:11 +0000500 return 0;
Damien Miller95def091999-11-25 00:26:21 +1100501}
502
Damien Miller0faf7472013-10-17 11:47:23 +1100503int
504ssh_connect(const char *host, struct addrinfo *addrs,
505 struct sockaddr_storage *hostaddr, u_short port, int family,
506 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
507{
508 if (options.proxy_command == NULL) {
509 return ssh_connect_direct(host, addrs, hostaddr, port, family,
510 connection_attempts, timeout_ms, want_keepalive, needpriv);
511 } else if (strcmp(options.proxy_command, "-") == 0) {
512 packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
513 return 0; /* Always succeeds */
514 } else if (options.proxy_use_fdpass) {
515 return ssh_proxy_fdpass_connect(host, port,
516 options.proxy_command);
517 }
518 return ssh_proxy_connect(host, port, options.proxy_command);
519}
520
Darren Tucker00c15182012-09-06 21:21:56 +1000521static void
522send_client_banner(int connection_out, int minor1)
523{
Darren Tucker00c15182012-09-06 21:21:56 +1000524 /* Send our own protocol version identification. */
525 if (compat20) {
526 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
527 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
528 } else {
529 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
530 PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
531 }
532 if (roaming_atomicio(vwrite, connection_out, client_version_string,
533 strlen(client_version_string)) != strlen(client_version_string))
534 fatal("write: %.100s", strerror(errno));
535 chop(client_version_string);
536 debug("Local version string %.100s", client_version_string);
537}
538
Damien Milleraae6c611999-12-06 11:47:28 +1100539/*
Damien Miller95def091999-11-25 00:26:21 +1100540 * Waits for the server identification string, and sends our own
541 * identification string.
542 */
Darren Tucker1cc55d72009-06-21 18:17:19 +1000543void
Damien Miller67bd0622007-09-17 12:06:57 +1000544ssh_exchange_identification(int timeout_ms)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000545{
Damien Miller95def091999-11-25 00:26:21 +1100546 char buf[256], remote_version[256]; /* must be same size! */
Damien Millereccb9de2005-06-17 12:59:34 +1000547 int remote_major, remote_minor, mismatch;
Damien Miller95def091999-11-25 00:26:21 +1100548 int connection_in = packet_get_connection_in();
549 int connection_out = packet_get_connection_out();
Darren Tucker00c15182012-09-06 21:21:56 +1000550 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
Damien Miller1e88ea62006-07-10 20:15:56 +1000551 u_int i, n;
Damien Miller67bd0622007-09-17 12:06:57 +1000552 size_t len;
553 int fdsetsz, remaining, rc;
554 struct timeval t_start, t_remaining;
555 fd_set *fdset;
556
557 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
558 fdset = xcalloc(1, fdsetsz);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000559
Darren Tucker00c15182012-09-06 21:21:56 +1000560 /*
561 * If we are SSH2-only then we can send the banner immediately and
562 * save a round-trip.
563 */
564 if (options.protocol == SSH_PROTO_2) {
565 enable_compat20();
566 send_client_banner(connection_out, 0);
567 client_banner_sent = 1;
568 }
569
Damien Millerb253cc42005-05-26 12:23:44 +1000570 /* Read other side's version identification. */
Damien Miller67bd0622007-09-17 12:06:57 +1000571 remaining = timeout_ms;
Damien Miller1e88ea62006-07-10 20:15:56 +1000572 for (n = 0;;) {
Damien Millerf6d9e222000-06-18 14:50:44 +1000573 for (i = 0; i < sizeof(buf) - 1; i++) {
Damien Miller67bd0622007-09-17 12:06:57 +1000574 if (timeout_ms > 0) {
575 gettimeofday(&t_start, NULL);
576 ms_to_timeval(&t_remaining, remaining);
577 FD_SET(connection_in, fdset);
578 rc = select(connection_in + 1, fdset, NULL,
579 fdset, &t_remaining);
580 ms_subtract_diff(&t_start, &remaining);
581 if (rc == 0 || remaining <= 0)
582 fatal("Connection timed out during "
583 "banner exchange");
584 if (rc == -1) {
585 if (errno == EINTR)
586 continue;
587 fatal("ssh_exchange_identification: "
588 "select: %s", strerror(errno));
589 }
590 }
591
Darren Tuckerc5564e12009-06-21 18:53:53 +1000592 len = roaming_atomicio(read, connection_in, &buf[i], 1);
Damien Millerb253cc42005-05-26 12:23:44 +1000593
Damien Miller46d38de2005-07-17 17:02:09 +1000594 if (len != 1 && errno == EPIPE)
Damien Miller67bd0622007-09-17 12:06:57 +1000595 fatal("ssh_exchange_identification: "
596 "Connection closed by remote host");
Damien Millerb253cc42005-05-26 12:23:44 +1000597 else if (len != 1)
Damien Miller67bd0622007-09-17 12:06:57 +1000598 fatal("ssh_exchange_identification: "
599 "read: %.100s", strerror(errno));
Damien Millerf6d9e222000-06-18 14:50:44 +1000600 if (buf[i] == '\r') {
601 buf[i] = '\n';
602 buf[i + 1] = 0;
603 continue; /**XXX wait for \n */
604 }
605 if (buf[i] == '\n') {
606 buf[i + 1] = 0;
607 break;
608 }
Damien Miller1e88ea62006-07-10 20:15:56 +1000609 if (++n > 65536)
Damien Miller67bd0622007-09-17 12:06:57 +1000610 fatal("ssh_exchange_identification: "
611 "No banner received");
Damien Miller95def091999-11-25 00:26:21 +1100612 }
Damien Millerf6d9e222000-06-18 14:50:44 +1000613 buf[sizeof(buf) - 1] = 0;
614 if (strncmp(buf, "SSH-", 4) == 0)
Damien Miller95def091999-11-25 00:26:21 +1100615 break;
Damien Millerf6d9e222000-06-18 14:50:44 +1000616 debug("ssh_exchange_identification: %s", buf);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000617 }
Damien Miller1383bd82000-04-06 12:32:37 +1000618 server_version_string = xstrdup(buf);
Darren Tuckera627d422013-06-02 07:31:17 +1000619 free(fdset);
Damien Miller95def091999-11-25 00:26:21 +1100620
Damien Miller5428f641999-11-25 11:54:57 +1100621 /*
622 * Check that the versions match. In future this might accept
623 * several versions and set appropriate flags to handle them.
624 */
Damien Miller1383bd82000-04-06 12:32:37 +1000625 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
626 &remote_major, &remote_minor, remote_version) != 3)
Damien Miller95def091999-11-25 00:26:21 +1100627 fatal("Bad remote protocol version identification: '%.100s'", buf);
628 debug("Remote protocol version %d.%d, remote software version %.100s",
Damien Miller9f0f5c62001-12-21 14:45:46 +1100629 remote_major, remote_minor, remote_version);
Damien Miller95def091999-11-25 00:26:21 +1100630
markus@openbsd.org48b3b2b2015-01-19 20:20:20 +0000631 active_state->compat = compat_datafellows(remote_version);
Damien Miller78928792000-04-12 20:17:38 +1000632 mismatch = 0;
Damien Miller1383bd82000-04-06 12:32:37 +1000633
Ben Lindstrom1c37c6a2001-12-06 18:00:18 +0000634 switch (remote_major) {
Damien Miller78928792000-04-12 20:17:38 +1000635 case 1:
636 if (remote_minor == 99 &&
637 (options.protocol & SSH_PROTO_2) &&
638 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
639 enable_compat20();
640 break;
Damien Miller95def091999-11-25 00:26:21 +1100641 }
Damien Miller78928792000-04-12 20:17:38 +1000642 if (!(options.protocol & SSH_PROTO_1)) {
643 mismatch = 1;
644 break;
645 }
646 if (remote_minor < 3) {
647 fatal("Remote machine has too old SSH software version.");
Damien Miller0bc1bd82000-11-13 22:57:25 +1100648 } else if (remote_minor == 3 || remote_minor == 4) {
Damien Miller78928792000-04-12 20:17:38 +1000649 /* We speak 1.3, too. */
650 enable_compat13();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100651 minor1 = 3;
Damien Miller78928792000-04-12 20:17:38 +1000652 if (options.forward_agent) {
Damien Miller996acd22003-04-09 20:59:48 +1000653 logit("Agent forwarding disabled for protocol 1.3");
Damien Miller78928792000-04-12 20:17:38 +1000654 options.forward_agent = 0;
655 }
656 }
657 break;
658 case 2:
659 if (options.protocol & SSH_PROTO_2) {
660 enable_compat20();
661 break;
662 }
663 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000664 default:
Damien Miller78928792000-04-12 20:17:38 +1000665 mismatch = 1;
666 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000667 }
Damien Miller78928792000-04-12 20:17:38 +1000668 if (mismatch)
Damien Miller95def091999-11-25 00:26:21 +1100669 fatal("Protocol major versions differ: %d vs. %d",
Damien Miller78928792000-04-12 20:17:38 +1000670 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
671 remote_major);
Damien Miller58cd63b2014-01-10 10:59:24 +1100672 if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
673 fatal("Server version \"%.100s\" uses unsafe key agreement; "
674 "refusing connection", remote_version);
Damien Miller324541e2013-12-31 12:25:40 +1100675 if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
676 logit("Server version \"%.100s\" uses unsafe RSA signature "
677 "scheme; disabling use of RSA keys", remote_version);
Darren Tucker00c15182012-09-06 21:21:56 +1000678 if (!client_banner_sent)
679 send_client_banner(connection_out, minor1);
Damien Miller1383bd82000-04-06 12:32:37 +1000680 chop(server_version_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000681}
682
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000683/* defaults to 'no' */
Ben Lindstrombba81212001-06-25 05:01:22 +0000684static int
Damien Millere3980042001-10-10 15:02:03 +1000685confirm(const char *prompt)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000686{
Damien Miller49d795c2002-01-22 23:34:12 +1100687 const char *msg, *again = "Please type 'yes' or 'no': ";
688 char *p;
689 int ret = -1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000690
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000691 if (options.batch_mode)
692 return 0;
Damien Miller49d795c2002-01-22 23:34:12 +1100693 for (msg = prompt;;msg = again) {
694 p = read_passphrase(msg, RP_ECHO);
695 if (p == NULL ||
696 (p[0] == '\0') || (p[0] == '\n') ||
697 strncasecmp(p, "no", 2) == 0)
698 ret = 0;
Ben Lindstrom04f9af72002-07-04 00:03:56 +0000699 if (p && strncasecmp(p, "yes", 3) == 0)
Damien Miller49d795c2002-01-22 23:34:12 +1100700 ret = 1;
Darren Tuckera627d422013-06-02 07:31:17 +1000701 free(p);
Damien Miller49d795c2002-01-22 23:34:12 +1100702 if (ret != -1)
703 return ret;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000704 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000705}
706
Damien Miller0a80ca12010-02-27 07:55:05 +1100707static int
708check_host_cert(const char *host, const Key *host_key)
709{
710 const char *reason;
711
712 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
713 error("%s", reason);
714 return 0;
715 }
Damien Miller86687062014-07-02 15:28:02 +1000716 if (buffer_len(host_key->cert->critical) != 0) {
Damien Miller4e270b02010-04-16 15:56:21 +1000717 error("Certificate for %s contains unsupported "
718 "critical options(s)", host);
Damien Miller0a80ca12010-02-27 07:55:05 +1100719 return 0;
720 }
721 return 1;
722}
723
Damien Millerd925dcd2010-12-01 12:21:51 +1100724static int
725sockaddr_is_local(struct sockaddr *hostaddr)
726{
727 switch (hostaddr->sa_family) {
728 case AF_INET:
729 return (ntohl(((struct sockaddr_in *)hostaddr)->
730 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
731 case AF_INET6:
732 return IN6_IS_ADDR_LOOPBACK(
733 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
734 default:
735 return 0;
736 }
737}
738
739/*
740 * Prepare the hostname and ip address strings that are used to lookup
741 * host keys in known_hosts files. These may have a port number appended.
742 */
743void
744get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
745 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
746{
747 char ntop[NI_MAXHOST];
748 socklen_t addrlen;
749
750 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
751 case -1:
752 addrlen = 0;
753 break;
754 case AF_INET:
755 addrlen = sizeof(struct sockaddr_in);
756 break;
757 case AF_INET6:
758 addrlen = sizeof(struct sockaddr_in6);
759 break;
760 default:
761 addrlen = sizeof(struct sockaddr);
762 break;
763 }
764
765 /*
766 * We don't have the remote ip-address for connections
767 * using a proxy command
768 */
769 if (hostfile_ipaddr != NULL) {
770 if (options.proxy_command == NULL) {
771 if (getnameinfo(hostaddr, addrlen,
772 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
djm@openbsd.org9ce86c92015-01-28 22:36:00 +0000773 fatal("%s: getnameinfo failed", __func__);
Damien Millerd925dcd2010-12-01 12:21:51 +1100774 *hostfile_ipaddr = put_host_port(ntop, port);
775 } else {
776 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
777 "command>");
778 }
779 }
780
781 /*
782 * Allow the user to record the key under a different name or
783 * differentiate a non-standard port. This is useful for ssh
784 * tunneling over forwarded connections or if you run multiple
785 * sshd's on different ports on the same machine.
786 */
787 if (hostfile_hostname != NULL) {
788 if (options.host_key_alias != NULL) {
789 *hostfile_hostname = xstrdup(options.host_key_alias);
790 debug("using hostkeyalias: %s", *hostfile_hostname);
791 } else {
792 *hostfile_hostname = put_host_port(hostname, port);
793 }
794 }
795}
796
Damien Miller95def091999-11-25 00:26:21 +1100797/*
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000798 * check whether the supplied host key is valid, return -1 if the key
Damien Miller295ee632011-05-29 21:42:31 +1000799 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
Damien Miller95def091999-11-25 00:26:21 +1100800 */
Damien Millerda828392006-08-05 11:35:45 +1000801#define RDRW 0
802#define RDONLY 1
803#define ROQUIET 2
Ben Lindstrombba81212001-06-25 05:01:22 +0000804static int
Damien Millerda828392006-08-05 11:35:45 +1000805check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
Damien Miller295ee632011-05-29 21:42:31 +1000806 Key *host_key, int readonly,
807 char **user_hostfiles, u_int num_user_hostfiles,
808 char **system_hostfiles, u_int num_system_hostfiles)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000809{
Damien Miller95def091999-11-25 00:26:21 +1100810 HostStatus host_status;
811 HostStatus ip_status;
Damien Miller295ee632011-05-29 21:42:31 +1000812 Key *raw_key = NULL;
813 char *ip = NULL, *host = NULL;
814 char hostline[1000], *hostp, *fp, *ra;
Damien Miller49d795c2002-01-22 23:34:12 +1100815 char msg[1024];
Damien Miller295ee632011-05-29 21:42:31 +1000816 const char *type;
Damien Millerd925dcd2010-12-01 12:21:51 +1100817 const struct hostkey_entry *host_found, *ip_found;
Damien Miller295ee632011-05-29 21:42:31 +1000818 int len, cancelled_forwarding = 0;
819 int local = sockaddr_is_local(hostaddr);
820 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
djm@openbsd.org8d4f8722015-01-26 03:04:45 +0000821 int hostkey_trusted = 0; /* Known or explicitly accepted by user */
Damien Miller295ee632011-05-29 21:42:31 +1000822 struct hostkeys *host_hostkeys, *ip_hostkeys;
823 u_int i;
Damien Miller34132e52000-01-14 15:45:46 +1100824
825 /*
826 * Force accepting of the host key for loopback/localhost. The
827 * problem is that if the home directory is NFS-mounted to multiple
828 * machines, localhost will refer to a different machine in each of
829 * them, and the user will get bogus HOST_CHANGED warnings. This
830 * essentially disables host authentication for localhost; however,
831 * this is probably not a real problem.
832 */
Ben Lindstrom3cecc9a2001-10-03 17:39:38 +0000833 if (options.no_host_authentication_for_localhost == 1 && local &&
834 options.host_key_alias == NULL) {
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000835 debug("Forcing accepting of host key for "
836 "loopback/localhost.");
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000837 return 0;
Damien Miller34132e52000-01-14 15:45:46 +1100838 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000839
Damien Milleraae6c611999-12-06 11:47:28 +1100840 /*
Damien Millerd925dcd2010-12-01 12:21:51 +1100841 * Prepare the hostname and address strings used for hostkey lookup.
842 * In some cases, these will have a port number appended.
Damien Milleraae6c611999-12-06 11:47:28 +1100843 */
Damien Millerd925dcd2010-12-01 12:21:51 +1100844 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
Darren Tucker78913e02008-06-13 04:47:34 +1000845
846 /*
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000847 * Turn off check_host_ip if the connection is to localhost, via proxy
848 * command or if we don't have a hostname to compare with
849 */
Darren Tuckerda345532006-07-10 23:04:19 +1000850 if (options.check_host_ip && (local ||
851 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
Damien Milleraae6c611999-12-06 11:47:28 +1100852 options.check_host_ip = 0;
853
Damien Millerd925dcd2010-12-01 12:21:51 +1100854 host_hostkeys = init_hostkeys();
Damien Miller295ee632011-05-29 21:42:31 +1000855 for (i = 0; i < num_user_hostfiles; i++)
856 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
857 for (i = 0; i < num_system_hostfiles; i++)
858 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
Damien Millerd925dcd2010-12-01 12:21:51 +1100859
860 ip_hostkeys = NULL;
861 if (!want_cert && options.check_host_ip) {
862 ip_hostkeys = init_hostkeys();
Damien Miller295ee632011-05-29 21:42:31 +1000863 for (i = 0; i < num_user_hostfiles; i++)
864 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
865 for (i = 0; i < num_system_hostfiles; i++)
866 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000867 }
868
Damien Miller0a80ca12010-02-27 07:55:05 +1100869 retry:
Damien Millerd925dcd2010-12-01 12:21:51 +1100870 /* Reload these as they may have changed on cert->key downgrade */
Damien Miller0a80ca12010-02-27 07:55:05 +1100871 want_cert = key_is_cert(host_key);
872 type = key_type(host_key);
873
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000874 /*
Damien Miller788f2122005-11-05 15:14:59 +1100875 * Check if the host key is present in the user's list of known
Damien Miller5428f641999-11-25 11:54:57 +1100876 * hosts or in the systemwide list.
877 */
Damien Millerd925dcd2010-12-01 12:21:51 +1100878 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
879 &host_found);
880
Damien Miller5428f641999-11-25 11:54:57 +1100881 /*
Damien Miller5428f641999-11-25 11:54:57 +1100882 * Also perform check for the ip address, skip the check if we are
Damien Miller0a80ca12010-02-27 07:55:05 +1100883 * localhost, looking for a certificate, or the hostname was an ip
884 * address to begin with.
Damien Miller5428f641999-11-25 11:54:57 +1100885 */
Damien Millerd925dcd2010-12-01 12:21:51 +1100886 if (!want_cert && ip_hostkeys != NULL) {
887 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
888 &ip_found);
Damien Miller95def091999-11-25 00:26:21 +1100889 if (host_status == HOST_CHANGED &&
Damien Millerd925dcd2010-12-01 12:21:51 +1100890 (ip_status != HOST_CHANGED ||
891 (ip_found != NULL &&
892 !key_equal(ip_found->key, host_found->key))))
Damien Miller95def091999-11-25 00:26:21 +1100893 host_ip_differ = 1;
Damien Miller95def091999-11-25 00:26:21 +1100894 } else
895 ip_status = host_status;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000896
Damien Miller95def091999-11-25 00:26:21 +1100897 switch (host_status) {
898 case HOST_OK:
899 /* The host is known and the key matches. */
Damien Miller0a80ca12010-02-27 07:55:05 +1100900 debug("Host '%.200s' is known and matches the %s host %s.",
901 host, type, want_cert ? "certificate" : "key");
Damien Millerd925dcd2010-12-01 12:21:51 +1100902 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
903 host_found->file, host_found->line);
Damien Miller0a80ca12010-02-27 07:55:05 +1100904 if (want_cert && !check_host_cert(hostname, host_key))
905 goto fail;
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000906 if (options.check_host_ip && ip_status == HOST_NEW) {
Damien Miller0a80ca12010-02-27 07:55:05 +1100907 if (readonly || want_cert)
Damien Miller996acd22003-04-09 20:59:48 +1000908 logit("%s host key for IP address "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000909 "'%.128s' not in list of known hosts.",
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000910 type, ip);
Damien Miller295ee632011-05-29 21:42:31 +1000911 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
Damien Millere1776152005-03-01 21:47:37 +1100912 host_key, options.hash_known_hosts))
Damien Miller996acd22003-04-09 20:59:48 +1000913 logit("Failed to add the %s host key for IP "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000914 "address '%.128s' to the list of known "
dtucker@openbsd.org496aeb22015-05-28 05:41:29 +0000915 "hosts (%.500s).", type, ip,
Damien Miller295ee632011-05-29 21:42:31 +1000916 user_hostfiles[0]);
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000917 else
Damien Miller996acd22003-04-09 20:59:48 +1000918 logit("Warning: Permanently added the %s host "
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000919 "key for IP address '%.128s' to the list "
920 "of known hosts.", type, ip);
Damien Miller10288242008-06-30 00:04:03 +1000921 } else if (options.visual_host_key) {
djm@openbsd.org9ce86c92015-01-28 22:36:00 +0000922 fp = sshkey_fingerprint(host_key,
djm@openbsd.org56d1c832014-12-21 22:27:55 +0000923 options.fingerprint_hash, SSH_FP_DEFAULT);
djm@openbsd.org9ce86c92015-01-28 22:36:00 +0000924 ra = sshkey_fingerprint(host_key,
djm@openbsd.org56d1c832014-12-21 22:27:55 +0000925 options.fingerprint_hash, SSH_FP_RANDOMART);
djm@openbsd.org9ce86c92015-01-28 22:36:00 +0000926 if (fp == NULL || ra == NULL)
927 fatal("%s: sshkey_fingerprint fail", __func__);
Darren Tucker9c16ac92008-06-13 04:40:35 +1000928 logit("Host key fingerprint is %s\n%s\n", fp, ra);
Darren Tuckera627d422013-06-02 07:31:17 +1000929 free(ra);
930 free(fp);
Damien Miller95def091999-11-25 00:26:21 +1100931 }
djm@openbsd.org8d4f8722015-01-26 03:04:45 +0000932 hostkey_trusted = 1;
Damien Miller95def091999-11-25 00:26:21 +1100933 break;
934 case HOST_NEW:
Damien Millerda828392006-08-05 11:35:45 +1000935 if (options.host_key_alias == NULL && port != 0 &&
936 port != SSH_DEFAULT_PORT) {
937 debug("checking without port identifier");
Damien Millerece92c82008-11-03 19:25:03 +1100938 if (check_host_key(hostname, hostaddr, 0, host_key,
Damien Miller295ee632011-05-29 21:42:31 +1000939 ROQUIET, user_hostfiles, num_user_hostfiles,
940 system_hostfiles, num_system_hostfiles) == 0) {
Damien Millerda828392006-08-05 11:35:45 +1000941 debug("found matching key w/out port");
942 break;
943 }
944 }
Damien Miller0a80ca12010-02-27 07:55:05 +1100945 if (readonly || want_cert)
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000946 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100947 /* The host is new. */
948 if (options.strict_host_key_checking == 1) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000949 /*
950 * User has requested strict host key checking. We
951 * will not add the host key automatically. The only
952 * alternative left is to abort.
953 */
954 error("No %s host key is known for %.200s and you "
955 "have requested strict checking.", type, host);
956 goto fail;
Damien Miller95def091999-11-25 00:26:21 +1100957 } else if (options.strict_host_key_checking == 2) {
Damien Miller7392ae62003-06-11 22:05:25 +1000958 char msg1[1024], msg2[1024];
959
Damien Millerd925dcd2010-12-01 12:21:51 +1100960 if (show_other_keys(host_hostkeys, host_key))
Damien Miller7392ae62003-06-11 22:05:25 +1000961 snprintf(msg1, sizeof(msg1),
Damien Miller0dc1bef2005-07-17 17:22:45 +1000962 "\nbut keys of different type are already"
963 " known for this host.");
Damien Miller7392ae62003-06-11 22:05:25 +1000964 else
965 snprintf(msg1, sizeof(msg1), ".");
Damien Miller95def091999-11-25 00:26:21 +1100966 /* The default */
djm@openbsd.org9ce86c92015-01-28 22:36:00 +0000967 fp = sshkey_fingerprint(host_key,
djm@openbsd.org56d1c832014-12-21 22:27:55 +0000968 options.fingerprint_hash, SSH_FP_DEFAULT);
djm@openbsd.org9ce86c92015-01-28 22:36:00 +0000969 ra = sshkey_fingerprint(host_key,
djm@openbsd.org56d1c832014-12-21 22:27:55 +0000970 options.fingerprint_hash, SSH_FP_RANDOMART);
djm@openbsd.org9ce86c92015-01-28 22:36:00 +0000971 if (fp == NULL || ra == NULL)
972 fatal("%s: sshkey_fingerprint fail", __func__);
Damien Miller7392ae62003-06-11 22:05:25 +1000973 msg2[0] = '\0';
Damien Miller7392ae62003-06-11 22:05:25 +1000974 if (options.verify_host_key_dns) {
Damien Miller150b5572003-11-17 21:19:29 +1100975 if (matching_host_key_dns)
Damien Miller7392ae62003-06-11 22:05:25 +1000976 snprintf(msg2, sizeof(msg2),
977 "Matching host key fingerprint"
978 " found in DNS.\n");
979 else
980 snprintf(msg2, sizeof(msg2),
981 "No matching host key fingerprint"
982 " found in DNS.\n");
983 }
Damien Miller49d795c2002-01-22 23:34:12 +1100984 snprintf(msg, sizeof(msg),
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000985 "The authenticity of host '%.200s (%s)' can't be "
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000986 "established%s\n"
Damien Miller10288242008-06-30 00:04:03 +1000987 "%s key fingerprint is %s.%s%s\n%s"
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000988 "Are you sure you want to continue connecting "
Ben Lindstrom3ed66402002-08-01 01:21:56 +0000989 "(yes/no)? ",
Damien Miller10288242008-06-30 00:04:03 +1000990 host, ip, msg1, type, fp,
991 options.visual_host_key ? "\n" : "",
992 options.visual_host_key ? ra : "",
993 msg2);
Darren Tuckera627d422013-06-02 07:31:17 +1000994 free(ra);
995 free(fp);
Damien Miller49d795c2002-01-22 23:34:12 +1100996 if (!confirm(msg))
Ben Lindstromd6481ea2001-06-25 04:37:41 +0000997 goto fail;
djm@openbsd.org8d4f8722015-01-26 03:04:45 +0000998 hostkey_trusted = 1; /* user explicitly confirmed */
Damien Miller95def091999-11-25 00:26:21 +1100999 }
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001000 /*
1001 * If not in strict mode, add the key automatically to the
1002 * local known_hosts file.
1003 */
Damien Miller1227d4c2005-03-02 12:06:51 +11001004 if (options.check_host_ip && ip_status == HOST_NEW) {
Damien Millerd925dcd2010-12-01 12:21:51 +11001005 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
Damien Miller1227d4c2005-03-02 12:06:51 +11001006 hostp = hostline;
1007 if (options.hash_known_hosts) {
1008 /* Add hash of host and IP separately */
Damien Miller295ee632011-05-29 21:42:31 +10001009 r = add_host_to_hostfile(user_hostfiles[0],
1010 host, host_key, options.hash_known_hosts) &&
1011 add_host_to_hostfile(user_hostfiles[0], ip,
Damien Miller1227d4c2005-03-02 12:06:51 +11001012 host_key, options.hash_known_hosts);
1013 } else {
1014 /* Add unhashed "host,ip" */
Damien Miller295ee632011-05-29 21:42:31 +10001015 r = add_host_to_hostfile(user_hostfiles[0],
Damien Miller1227d4c2005-03-02 12:06:51 +11001016 hostline, host_key,
1017 options.hash_known_hosts);
1018 }
1019 } else {
Damien Miller295ee632011-05-29 21:42:31 +10001020 r = add_host_to_hostfile(user_hostfiles[0], host,
1021 host_key, options.hash_known_hosts);
Damien Miller1227d4c2005-03-02 12:06:51 +11001022 hostp = host;
1023 }
1024
1025 if (!r)
Damien Miller996acd22003-04-09 20:59:48 +10001026 logit("Failed to add the host to the list of known "
Damien Miller295ee632011-05-29 21:42:31 +10001027 "hosts (%.500s).", user_hostfiles[0]);
Damien Miller95def091999-11-25 00:26:21 +11001028 else
Damien Miller996acd22003-04-09 20:59:48 +10001029 logit("Warning: Permanently added '%.200s' (%s) to the "
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001030 "list of known hosts.", hostp, type);
Damien Miller95def091999-11-25 00:26:21 +11001031 break;
Damien Miller1aed65e2010-03-04 21:53:35 +11001032 case HOST_REVOKED:
1033 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1034 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1035 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1036 error("The %s host key for %s is marked as revoked.", type, host);
1037 error("This could mean that a stolen key is being used to");
1038 error("impersonate this host.");
1039
1040 /*
1041 * If strict host key checking is in use, the user will have
1042 * to edit the key manually and we can only abort.
1043 */
1044 if (options.strict_host_key_checking) {
1045 error("%s host key for %.200s was revoked and you have "
1046 "requested strict checking.", type, host);
1047 goto fail;
1048 }
1049 goto continue_unsafe;
1050
Damien Miller95def091999-11-25 00:26:21 +11001051 case HOST_CHANGED:
Damien Miller0a80ca12010-02-27 07:55:05 +11001052 if (want_cert) {
1053 /*
1054 * This is only a debug() since it is valid to have
1055 * CAs with wildcard DNS matches that don't match
1056 * all hosts that one might visit.
1057 */
1058 debug("Host certificate authority does not "
Damien Millerd925dcd2010-12-01 12:21:51 +11001059 "match %s in %s:%lu", CA_MARKER,
1060 host_found->file, host_found->line);
Damien Miller0a80ca12010-02-27 07:55:05 +11001061 goto fail;
1062 }
Damien Millerda828392006-08-05 11:35:45 +10001063 if (readonly == ROQUIET)
1064 goto fail;
Damien Miller95def091999-11-25 00:26:21 +11001065 if (options.check_host_ip && host_ip_differ) {
Darren Tucker3f9fdc72004-06-22 12:56:01 +10001066 char *key_msg;
Damien Miller95def091999-11-25 00:26:21 +11001067 if (ip_status == HOST_NEW)
Darren Tucker3f9fdc72004-06-22 12:56:01 +10001068 key_msg = "is unknown";
Damien Miller95def091999-11-25 00:26:21 +11001069 else if (ip_status == HOST_OK)
Darren Tucker3f9fdc72004-06-22 12:56:01 +10001070 key_msg = "is unchanged";
Damien Miller95def091999-11-25 00:26:21 +11001071 else
Darren Tucker3f9fdc72004-06-22 12:56:01 +10001072 key_msg = "has a different value";
Damien Miller95def091999-11-25 00:26:21 +11001073 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1074 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1075 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
Damien Millere247cc42000-05-07 12:03:14 +10001076 error("The %s host key for %s has changed,", type, host);
Darren Tuckerff4454d2008-06-13 10:21:51 +10001077 error("and the key for the corresponding IP address %s", ip);
Darren Tucker3f9fdc72004-06-22 12:56:01 +10001078 error("%s. This could either mean that", key_msg);
Damien Miller95def091999-11-25 00:26:21 +11001079 error("DNS SPOOFING is happening or the IP address for the host");
Ben Lindstrom46c16222000-12-22 01:43:59 +00001080 error("and its host key have changed at the same time.");
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +00001081 if (ip_status != HOST_NEW)
Damien Millerd925dcd2010-12-01 12:21:51 +11001082 error("Offending key for IP in %s:%lu",
1083 ip_found->file, ip_found->line);
Damien Miller95def091999-11-25 00:26:21 +11001084 }
1085 /* The host key has changed. */
Damien Miller5a388972003-11-17 21:10:47 +11001086 warn_changed_key(host_key);
Damien Miller95def091999-11-25 00:26:21 +11001087 error("Add correct host key in %.100s to get rid of this message.",
Damien Miller295ee632011-05-29 21:42:31 +10001088 user_hostfiles[0]);
Damien Millerd925dcd2010-12-01 12:21:51 +11001089 error("Offending %s key in %s:%lu", key_type(host_found->key),
1090 host_found->file, host_found->line);
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001091
Damien Miller5428f641999-11-25 11:54:57 +11001092 /*
1093 * If strict host key checking is in use, the user will have
1094 * to edit the key manually and we can only abort.
1095 */
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001096 if (options.strict_host_key_checking) {
1097 error("%s host key for %.200s has changed and you have "
1098 "requested strict checking.", type, host);
1099 goto fail;
1100 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001101
Damien Miller1aed65e2010-03-04 21:53:35 +11001102 continue_unsafe:
Damien Miller5428f641999-11-25 11:54:57 +11001103 /*
1104 * If strict host key checking has not been requested, allow
Damien Miller941ac452003-06-04 20:31:53 +10001105 * the connection but without MITM-able authentication or
Damien Miller437edb92006-08-05 09:11:13 +10001106 * forwarding.
Damien Miller5428f641999-11-25 11:54:57 +11001107 */
Damien Miller95def091999-11-25 00:26:21 +11001108 if (options.password_authentication) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001109 error("Password authentication is disabled to avoid "
1110 "man-in-the-middle attacks.");
Damien Miller95def091999-11-25 00:26:21 +11001111 options.password_authentication = 0;
Darren Tucker068e01f2008-07-02 22:33:55 +10001112 cancelled_forwarding = 1;
Damien Miller95def091999-11-25 00:26:21 +11001113 }
Damien Miller941ac452003-06-04 20:31:53 +10001114 if (options.kbd_interactive_authentication) {
1115 error("Keyboard-interactive authentication is disabled"
1116 " to avoid man-in-the-middle attacks.");
1117 options.kbd_interactive_authentication = 0;
1118 options.challenge_response_authentication = 0;
Darren Tucker068e01f2008-07-02 22:33:55 +10001119 cancelled_forwarding = 1;
Damien Miller941ac452003-06-04 20:31:53 +10001120 }
1121 if (options.challenge_response_authentication) {
1122 error("Challenge/response authentication is disabled"
1123 " to avoid man-in-the-middle attacks.");
1124 options.challenge_response_authentication = 0;
Darren Tucker068e01f2008-07-02 22:33:55 +10001125 cancelled_forwarding = 1;
Damien Miller941ac452003-06-04 20:31:53 +10001126 }
Damien Miller95def091999-11-25 00:26:21 +11001127 if (options.forward_agent) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001128 error("Agent forwarding is disabled to avoid "
1129 "man-in-the-middle attacks.");
Damien Miller95def091999-11-25 00:26:21 +11001130 options.forward_agent = 0;
Darren Tucker068e01f2008-07-02 22:33:55 +10001131 cancelled_forwarding = 1;
Damien Miller95def091999-11-25 00:26:21 +11001132 }
Ben Lindstromc72745a2000-12-02 19:03:54 +00001133 if (options.forward_x11) {
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001134 error("X11 forwarding is disabled to avoid "
1135 "man-in-the-middle attacks.");
Ben Lindstromc72745a2000-12-02 19:03:54 +00001136 options.forward_x11 = 0;
Darren Tucker068e01f2008-07-02 22:33:55 +10001137 cancelled_forwarding = 1;
Ben Lindstromc72745a2000-12-02 19:03:54 +00001138 }
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001139 if (options.num_local_forwards > 0 ||
1140 options.num_remote_forwards > 0) {
1141 error("Port forwarding is disabled to avoid "
1142 "man-in-the-middle attacks.");
1143 options.num_local_forwards =
Damien Miller9f0f5c62001-12-21 14:45:46 +11001144 options.num_remote_forwards = 0;
Darren Tucker068e01f2008-07-02 22:33:55 +10001145 cancelled_forwarding = 1;
Ben Lindstromc72745a2000-12-02 19:03:54 +00001146 }
Damien Miller437edb92006-08-05 09:11:13 +10001147 if (options.tun_open != SSH_TUNMODE_NO) {
1148 error("Tunnel forwarding is disabled to avoid "
1149 "man-in-the-middle attacks.");
1150 options.tun_open = SSH_TUNMODE_NO;
Darren Tucker068e01f2008-07-02 22:33:55 +10001151 cancelled_forwarding = 1;
Damien Miller437edb92006-08-05 09:11:13 +10001152 }
Darren Tucker068e01f2008-07-02 22:33:55 +10001153 if (options.exit_on_forward_failure && cancelled_forwarding)
1154 fatal("Error: forwarding disabled due to host key "
1155 "check failure");
1156
Damien Miller5428f641999-11-25 11:54:57 +11001157 /*
1158 * XXX Should permit the user to change to use the new id.
1159 * This could be done by converting the host key to an
1160 * identifying sentence, tell that the host identifies itself
Darren Tuckere2b36742010-01-13 22:42:34 +11001161 * by that sentence, and ask the user if he/she wishes to
Damien Miller5428f641999-11-25 11:54:57 +11001162 * accept the authentication.
1163 */
Damien Miller95def091999-11-25 00:26:21 +11001164 break;
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001165 case HOST_FOUND:
1166 fatal("internal error");
1167 break;
Damien Miller95def091999-11-25 00:26:21 +11001168 }
Ben Lindstromc72745a2000-12-02 19:03:54 +00001169
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +00001170 if (options.check_host_ip && host_status != HOST_CHANGED &&
1171 ip_status == HOST_CHANGED) {
Damien Miller49d795c2002-01-22 23:34:12 +11001172 snprintf(msg, sizeof(msg),
1173 "Warning: the %s host key for '%.200s' "
1174 "differs from the key for the IP address '%.128s'"
Damien Millerd925dcd2010-12-01 12:21:51 +11001175 "\nOffending key for IP in %s:%lu",
1176 type, host, ip, ip_found->file, ip_found->line);
Damien Miller49d795c2002-01-22 23:34:12 +11001177 if (host_status == HOST_OK) {
1178 len = strlen(msg);
1179 snprintf(msg + len, sizeof(msg) - len,
Damien Millerd925dcd2010-12-01 12:21:51 +11001180 "\nMatching host key in %s:%lu",
1181 host_found->file, host_found->line);
Damien Miller49d795c2002-01-22 23:34:12 +11001182 }
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +00001183 if (options.strict_host_key_checking == 1) {
Damien Millerab2db412003-06-02 19:09:13 +10001184 logit("%s", msg);
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001185 error("Exiting, you have requested strict checking.");
1186 goto fail;
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +00001187 } else if (options.strict_host_key_checking == 2) {
Damien Miller49d795c2002-01-22 23:34:12 +11001188 strlcat(msg, "\nAre you sure you want "
1189 "to continue connecting (yes/no)? ", sizeof(msg));
1190 if (!confirm(msg))
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001191 goto fail;
Damien Miller49d795c2002-01-22 23:34:12 +11001192 } else {
Damien Millerab2db412003-06-02 19:09:13 +10001193 logit("%s", msg);
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +00001194 }
1195 }
1196
djm@openbsd.org8d4f8722015-01-26 03:04:45 +00001197 if (!hostkey_trusted && options.update_hostkeys) {
1198 debug("%s: hostkey not known or explicitly trusted: "
1199 "disabling UpdateHostkeys", __func__);
1200 options.update_hostkeys = 0;
1201 }
1202
Darren Tuckera627d422013-06-02 07:31:17 +10001203 free(ip);
1204 free(host);
Damien Millerd925dcd2010-12-01 12:21:51 +11001205 if (host_hostkeys != NULL)
1206 free_hostkeys(host_hostkeys);
1207 if (ip_hostkeys != NULL)
1208 free_hostkeys(ip_hostkeys);
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001209 return 0;
1210
1211fail:
Damien Miller1aed65e2010-03-04 21:53:35 +11001212 if (want_cert && host_status != HOST_REVOKED) {
Damien Miller0a80ca12010-02-27 07:55:05 +11001213 /*
1214 * No matching certificate. Downgrade cert to raw key and
1215 * search normally.
1216 */
1217 debug("No matching CA found. Retry with plain key");
1218 raw_key = key_from_private(host_key);
1219 if (key_drop_cert(raw_key) != 0)
1220 fatal("Couldn't drop certificate");
1221 host_key = raw_key;
1222 goto retry;
1223 }
1224 if (raw_key != NULL)
1225 key_free(raw_key);
Darren Tuckera627d422013-06-02 07:31:17 +10001226 free(ip);
1227 free(host);
Damien Millerd925dcd2010-12-01 12:21:51 +11001228 if (host_hostkeys != NULL)
1229 free_hostkeys(host_hostkeys);
1230 if (ip_hostkeys != NULL)
1231 free_hostkeys(ip_hostkeys);
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001232 return -1;
1233}
1234
Damien Miller37876e92003-05-15 10:19:46 +10001235/* returns 0 if key verifies or -1 if key does NOT verify */
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001236int
1237verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1238{
Damien Miller6b37fbb2014-07-04 08:59:24 +10001239 int r = -1, flags = 0;
djm@openbsd.org5e39a492014-12-04 02:24:32 +00001240 char *fp = NULL;
1241 struct sshkey *plain = NULL;
Damien Millerd925dcd2010-12-01 12:21:51 +11001242
djm@openbsd.org5e39a492014-12-04 02:24:32 +00001243 if ((fp = sshkey_fingerprint(host_key,
djm@openbsd.org56d1c832014-12-21 22:27:55 +00001244 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
djm@openbsd.org5e39a492014-12-04 02:24:32 +00001245 error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1246 r = -1;
1247 goto out;
1248 }
Ben Lindstromd6481ea2001-06-25 04:37:41 +00001249
djm@openbsd.org5104db72015-01-26 06:10:03 +00001250 debug("Server host key: %s %s",
1251 compat20 ? sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
djm@openbsd.org5e39a492014-12-04 02:24:32 +00001252
1253 if (sshkey_equal(previous_host_key, host_key)) {
1254 debug2("%s: server host key %s %s matches cached key",
1255 __func__, sshkey_type(host_key), fp);
1256 r = 0;
1257 goto out;
1258 }
1259
1260 /* Check in RevokedHostKeys file if specified */
1261 if (options.revoked_host_keys != NULL) {
1262 r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1263 switch (r) {
1264 case 0:
1265 break; /* not revoked */
1266 case SSH_ERR_KEY_REVOKED:
1267 error("Host key %s %s revoked by file %s",
1268 sshkey_type(host_key), fp,
1269 options.revoked_host_keys);
1270 r = -1;
1271 goto out;
1272 default:
1273 error("Error checking host key %s %s in "
1274 "revoked keys file %s: %s", sshkey_type(host_key),
1275 fp, options.revoked_host_keys, ssh_err(r));
1276 r = -1;
1277 goto out;
1278 }
Damien Miller6b37fbb2014-07-04 08:59:24 +10001279 }
1280
Damien Miller7d6a9fb2014-04-20 13:23:43 +10001281 if (options.verify_host_key_dns) {
1282 /*
1283 * XXX certs are not yet supported for DNS, so downgrade
1284 * them and try the plain key.
1285 */
djm@openbsd.org5e39a492014-12-04 02:24:32 +00001286 if ((r = sshkey_from_private(host_key, &plain)) != 0)
1287 goto out;
1288 if (sshkey_is_cert(plain))
1289 sshkey_drop_cert(plain);
Damien Miller7d6a9fb2014-04-20 13:23:43 +10001290 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1291 if (flags & DNS_VERIFY_FOUND) {
1292 if (options.verify_host_key_dns == 1 &&
1293 flags & DNS_VERIFY_MATCH &&
1294 flags & DNS_VERIFY_SECURE) {
Damien Miller6b37fbb2014-07-04 08:59:24 +10001295 r = 0;
djm@openbsd.org5e39a492014-12-04 02:24:32 +00001296 goto out;
Damien Miller7d6a9fb2014-04-20 13:23:43 +10001297 }
1298 if (flags & DNS_VERIFY_MATCH) {
1299 matching_host_key_dns = 1;
1300 } else {
1301 warn_changed_key(plain);
1302 error("Update the SSHFP RR in DNS "
1303 "with the new host key to get rid "
1304 "of this message.");
1305 }
Damien Miller150b5572003-11-17 21:19:29 +11001306 }
Damien Miller37876e92003-05-15 10:19:46 +10001307 }
1308 }
Damien Miller6b37fbb2014-07-04 08:59:24 +10001309 r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
Damien Miller295ee632011-05-29 21:42:31 +10001310 options.user_hostfiles, options.num_user_hostfiles,
1311 options.system_hostfiles, options.num_system_hostfiles);
Damien Miller6b37fbb2014-07-04 08:59:24 +10001312
djm@openbsd.org5e39a492014-12-04 02:24:32 +00001313out:
1314 sshkey_free(plain);
1315 free(fp);
Damien Miller6b37fbb2014-07-04 08:59:24 +10001316 if (r == 0 && host_key != NULL) {
1317 key_free(previous_host_key);
1318 previous_host_key = key_from_private(host_key);
1319 }
1320
1321 return r;
Damien Millera34a28b1999-12-14 10:47:15 +11001322}
Damien Miller037a0dc1999-12-07 15:38:31 +11001323
Damien Miller396691a2000-01-20 22:44:08 +11001324/*
1325 * Starts a dialog with the server, and authenticates the current user on the
1326 * server. This does not need any extra privileges. The basic connection
1327 * to the server must already have been established before this is called.
1328 * If login fails, this function prints an error and never returns.
1329 * This function does not require super-user privileges.
1330 */
1331void
Ben Lindstrom1bad2562002-06-06 19:57:33 +00001332ssh_login(Sensitive *sensitive, const char *orighost,
Damien Millerd925dcd2010-12-01 12:21:51 +11001333 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
Damien Miller396691a2000-01-20 22:44:08 +11001334{
Damien Miller0faf7472013-10-17 11:47:23 +11001335 char *host;
Damien Millereba71ba2000-04-29 23:57:08 +10001336 char *server_user, *local_user;
1337
Damien Millereba71ba2000-04-29 23:57:08 +10001338 local_user = xstrdup(pw->pw_name);
1339 server_user = options.user ? options.user : local_user;
Damien Miller396691a2000-01-20 22:44:08 +11001340
1341 /* Convert the user-supplied hostname into all lowercase. */
1342 host = xstrdup(orighost);
Damien Miller0faf7472013-10-17 11:47:23 +11001343 lowercase(host);
Damien Miller396691a2000-01-20 22:44:08 +11001344
1345 /* Exchange protocol version identification strings with the server. */
Damien Miller67bd0622007-09-17 12:06:57 +10001346 ssh_exchange_identification(timeout_ms);
Damien Miller396691a2000-01-20 22:44:08 +11001347
1348 /* Put the connection into non-blocking mode. */
1349 packet_set_nonblocking();
1350
Damien Miller396691a2000-01-20 22:44:08 +11001351 /* key exchange */
Damien Miller396691a2000-01-20 22:44:08 +11001352 /* authenticate user */
dtucker@openbsd.orgbb2289e2015-04-14 04:17:03 +00001353 debug("Authenticating to %s:%d as '%s'", host, port, server_user);
Damien Miller1383bd82000-04-06 12:32:37 +10001354 if (compat20) {
Damien Millerd925dcd2010-12-01 12:21:51 +11001355 ssh_kex2(host, hostaddr, port);
Ben Lindstrom1bad2562002-06-06 19:57:33 +00001356 ssh_userauth2(local_user, server_user, host, sensitive);
Damien Miller1383bd82000-04-06 12:32:37 +10001357 } else {
Damien Miller1f0311c2014-05-15 14:24:09 +10001358#ifdef WITH_SSH1
Damien Miller1383bd82000-04-06 12:32:37 +10001359 ssh_kex(host, hostaddr);
Ben Lindstrom1bad2562002-06-06 19:57:33 +00001360 ssh_userauth1(local_user, server_user, host, sensitive);
Damien Miller1f0311c2014-05-15 14:24:09 +10001361#else
djm@openbsd.org53097b22015-03-24 01:11:12 +00001362 fatal("ssh1 is not supported");
Damien Miller1f0311c2014-05-15 14:24:09 +10001363#endif
Damien Miller1383bd82000-04-06 12:32:37 +10001364 }
Darren Tuckera627d422013-06-02 07:31:17 +10001365 free(local_user);
Damien Miller396691a2000-01-20 22:44:08 +11001366}
Damien Miller79438cc2001-02-16 12:34:57 +11001367
1368void
1369ssh_put_password(char *password)
1370{
1371 int size;
1372 char *padded;
1373
Ben Lindstromd20d0f32001-03-10 17:22:20 +00001374 if (datafellows & SSH_BUG_PASSWORDPAD) {
Ben Lindstrom664408d2001-06-09 01:42:01 +00001375 packet_put_cstring(password);
Ben Lindstromd20d0f32001-03-10 17:22:20 +00001376 return;
1377 }
Damien Miller79438cc2001-02-16 12:34:57 +11001378 size = roundup(strlen(password) + 1, 32);
Damien Miller07d86be2006-03-26 14:19:21 +11001379 padded = xcalloc(1, size);
Damien Miller79438cc2001-02-16 12:34:57 +11001380 strlcpy(padded, password, size);
1381 packet_put_string(padded, size);
Damien Millera5103f42014-02-04 11:20:14 +11001382 explicit_bzero(padded, size);
Darren Tuckera627d422013-06-02 07:31:17 +10001383 free(padded);
Damien Miller79438cc2001-02-16 12:34:57 +11001384}
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001385
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001386/* print all known host keys for a given host, but skip keys of given type */
1387static int
Damien Millerd925dcd2010-12-01 12:21:51 +11001388show_other_keys(struct hostkeys *hostkeys, Key *key)
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001389{
Damien Miller106bf1c2013-12-29 17:54:03 +11001390 int type[] = {
1391 KEY_RSA1,
1392 KEY_RSA,
1393 KEY_DSA,
1394 KEY_ECDSA,
1395 KEY_ED25519,
1396 -1
1397 };
Damien Millerd925dcd2010-12-01 12:21:51 +11001398 int i, ret = 0;
1399 char *fp, *ra;
1400 const struct hostkey_entry *found;
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001401
1402 for (i = 0; type[i] != -1; i++) {
1403 if (type[i] == key->type)
1404 continue;
Damien Millerd925dcd2010-12-01 12:21:51 +11001405 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001406 continue;
djm@openbsd.org9ce86c92015-01-28 22:36:00 +00001407 fp = sshkey_fingerprint(found->key,
djm@openbsd.org56d1c832014-12-21 22:27:55 +00001408 options.fingerprint_hash, SSH_FP_DEFAULT);
djm@openbsd.org9ce86c92015-01-28 22:36:00 +00001409 ra = sshkey_fingerprint(found->key,
djm@openbsd.org56d1c832014-12-21 22:27:55 +00001410 options.fingerprint_hash, SSH_FP_RANDOMART);
djm@openbsd.org9ce86c92015-01-28 22:36:00 +00001411 if (fp == NULL || ra == NULL)
1412 fatal("%s: sshkey_fingerprint fail", __func__);
Damien Millerd925dcd2010-12-01 12:21:51 +11001413 logit("WARNING: %s key found for host %s\n"
1414 "in %s:%lu\n"
1415 "%s key fingerprint %s.",
1416 key_type(found->key),
1417 found->host, found->file, found->line,
1418 key_type(found->key), fp);
1419 if (options.visual_host_key)
1420 logit("%s", ra);
Darren Tuckera627d422013-06-02 07:31:17 +10001421 free(ra);
1422 free(fp);
Damien Millerd925dcd2010-12-01 12:21:51 +11001423 ret = 1;
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001424 }
Damien Millerd925dcd2010-12-01 12:21:51 +11001425 return ret;
Ben Lindstrom3ed66402002-08-01 01:21:56 +00001426}
Damien Miller5a388972003-11-17 21:10:47 +11001427
1428static void
1429warn_changed_key(Key *host_key)
1430{
1431 char *fp;
Damien Miller5a388972003-11-17 21:10:47 +11001432
djm@openbsd.org9ce86c92015-01-28 22:36:00 +00001433 fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
djm@openbsd.org56d1c832014-12-21 22:27:55 +00001434 SSH_FP_DEFAULT);
djm@openbsd.org9ce86c92015-01-28 22:36:00 +00001435 if (fp == NULL)
1436 fatal("%s: sshkey_fingerprint fail", __func__);
Damien Miller5a388972003-11-17 21:10:47 +11001437
1438 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1439 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1440 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1441 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1442 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
Damien Miller05c89972011-01-06 22:42:04 +11001443 error("It is also possible that a host key has just been changed.");
Damien Miller5a388972003-11-17 21:10:47 +11001444 error("The fingerprint for the %s key sent by the remote host is\n%s.",
Damien Miller05c89972011-01-06 22:42:04 +11001445 key_type(host_key), fp);
Damien Miller5a388972003-11-17 21:10:47 +11001446 error("Please contact your system administrator.");
1447
Darren Tuckera627d422013-06-02 07:31:17 +10001448 free(fp);
Damien Miller5a388972003-11-17 21:10:47 +11001449}
Damien Millerd27b9472005-12-13 19:29:02 +11001450
1451/*
1452 * Execute a local command
1453 */
1454int
1455ssh_local_cmd(const char *args)
1456{
1457 char *shell;
1458 pid_t pid;
1459 int status;
Damien Millered3a8eb2011-01-07 10:02:52 +11001460 void (*osighand)(int);
Damien Millerd27b9472005-12-13 19:29:02 +11001461
1462 if (!options.permit_local_command ||
1463 args == NULL || !*args)
1464 return (1);
1465
Damien Miller38d9a962010-10-07 22:07:11 +11001466 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
Damien Millerd27b9472005-12-13 19:29:02 +11001467 shell = _PATH_BSHELL;
1468
Damien Millered3a8eb2011-01-07 10:02:52 +11001469 osighand = signal(SIGCHLD, SIG_DFL);
Damien Millerd27b9472005-12-13 19:29:02 +11001470 pid = fork();
1471 if (pid == 0) {
Damien Miller6fb6fd52011-01-16 23:17:45 +11001472 signal(SIGPIPE, SIG_DFL);
Damien Millerd27b9472005-12-13 19:29:02 +11001473 debug3("Executing %s -c \"%s\"", shell, args);
1474 execl(shell, shell, "-c", args, (char *)NULL);
1475 error("Couldn't execute %s -c \"%s\": %s",
1476 shell, args, strerror(errno));
1477 _exit(1);
1478 } else if (pid == -1)
1479 fatal("fork failed: %.100s", strerror(errno));
1480 while (waitpid(pid, &status, 0) == -1)
1481 if (errno != EINTR)
1482 fatal("Couldn't wait for child: %s", strerror(errno));
Damien Millered3a8eb2011-01-07 10:02:52 +11001483 signal(SIGCHLD, osighand);
Damien Millerd27b9472005-12-13 19:29:02 +11001484
1485 if (!WIFEXITED(status))
1486 return (1);
1487
1488 return (WEXITSTATUS(status));
1489}