OpenSSH: Revert few local modifications.
[dragonfly.git] / crypto / openssh / sshconnect.c
CommitLineData
2c9c1408 1/* $OpenBSD: sshconnect.c,v 1.287 2017/09/14 04:32:21 djm Exp $ */
16c343f1
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2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
8 *
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".
14 */
15
16#include "includes.h"
17
18#include <sys/types.h>
19#include <sys/wait.h>
20#include <sys/stat.h>
21#include <sys/socket.h>
22#ifdef HAVE_SYS_TIME_H
23# include <sys/time.h>
24#endif
25
26#include <netinet/in.h>
27#include <arpa/inet.h>
28
29#include <ctype.h>
30#include <errno.h>
856ea928 31#include <fcntl.h>
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32#include <netdb.h>
33#ifdef HAVE_PATHS_H
34#include <paths.h>
35#endif
36#include <pwd.h>
2c9c1408
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37#ifdef HAVE_POLL_H
38#include <poll.h>
39#endif
9f304aaf 40#include <signal.h>
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41#include <stdarg.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <unistd.h>
46
47#include "xmalloc.h"
48#include "key.h"
49#include "hostfile.h"
50#include "ssh.h"
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51#include "buffer.h"
52#include "packet.h"
53#include "uidswap.h"
54#include "compat.h"
55#include "key.h"
56#include "sshconnect.h"
57#include "hostfile.h"
58#include "log.h"
36e94dc5 59#include "misc.h"
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60#include "readconf.h"
61#include "atomicio.h"
16c343f1 62#include "dns.h"
36e94dc5 63#include "monitor_fdpass.h"
856ea928 64#include "ssh2.h"
16c343f1 65#include "version.h"
e9778795
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66#include "authfile.h"
67#include "ssherr.h"
68#include "authfd.h"
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69
70char *client_version_string = NULL;
71char *server_version_string = NULL;
2c9c1408 72struct sshkey *previous_host_key = NULL;
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73
74static int matching_host_key_dns = 0;
75
9f304aaf
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76static pid_t proxy_command_pid = 0;
77
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78/* import */
79extern Options options;
80extern char *__progname;
81extern uid_t original_real_uid;
82extern uid_t original_effective_uid;
16c343f1 83
2c9c1408
MD
84static int show_other_keys(struct hostkeys *, struct sshkey *);
85static void warn_changed_key(struct sshkey *);
16c343f1 86
36e94dc5
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87/* Expand a proxy command */
88static char *
89expand_proxy_command(const char *proxy_command, const char *user,
90 const char *host, int port)
91{
92 char *tmp, *ret, strport[NI_MAXSERV];
93
94 snprintf(strport, sizeof strport, "%d", port);
95 xasprintf(&tmp, "exec %s", proxy_command);
96 ret = percent_expand(tmp, "h", host, "p", strport,
97 "r", options.user, (char *)NULL);
98 free(tmp);
99 return ret;
100}
101
102/*
103 * Connect to the given ssh server using a proxy command that passes a
104 * a connected fd back to us.
105 */
106static int
2c9c1408 107ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
36e94dc5
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108 const char *proxy_command)
109{
110 char *command_string;
111 int sp[2], sock;
112 pid_t pid;
113 char *shell;
114
115 if ((shell = getenv("SHELL")) == NULL)
116 shell = _PATH_BSHELL;
117
118 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
119 fatal("Could not create socketpair to communicate with "
120 "proxy dialer: %.100s", strerror(errno));
121
122 command_string = expand_proxy_command(proxy_command, options.user,
123 host, port);
124 debug("Executing proxy dialer command: %.500s", command_string);
125
126 /* Fork and execute the proxy command. */
127 if ((pid = fork()) == 0) {
128 char *argv[10];
129
130 /* Child. Permanently give up superuser privileges. */
131 permanently_drop_suid(original_real_uid);
132
133 close(sp[1]);
134 /* Redirect stdin and stdout. */
135 if (sp[0] != 0) {
136 if (dup2(sp[0], 0) < 0)
137 perror("dup2 stdin");
138 }
139 if (sp[0] != 1) {
140 if (dup2(sp[0], 1) < 0)
141 perror("dup2 stdout");
142 }
143 if (sp[0] >= 2)
144 close(sp[0]);
145
146 /*
147 * Stderr is left as it is so that error messages get
148 * printed on the user's terminal.
149 */
150 argv[0] = shell;
151 argv[1] = "-c";
152 argv[2] = command_string;
153 argv[3] = NULL;
154
155 /*
156 * Execute the proxy command.
157 * Note that we gave up any extra privileges above.
158 */
159 execv(argv[0], argv);
160 perror(argv[0]);
161 exit(1);
162 }
163 /* Parent. */
164 if (pid < 0)
165 fatal("fork failed: %.100s", strerror(errno));
166 close(sp[0]);
167 free(command_string);
168
169 if ((sock = mm_receive_fd(sp[1])) == -1)
170 fatal("proxy dialer did not pass back a connection");
e9778795 171 close(sp[1]);
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172
173 while (waitpid(pid, NULL, 0) == -1)
174 if (errno != EINTR)
175 fatal("Couldn't wait for child: %s", strerror(errno));
176
177 /* Set the connection file descriptors. */
2c9c1408
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178 if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
179 return -1; /* ssh_packet_set_connection logs error */
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180
181 return 0;
182}
183
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184/*
185 * Connect to the given ssh server using a proxy command.
186 */
187static int
2c9c1408
MD
188ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
189 const char *proxy_command)
16c343f1 190{
36e94dc5 191 char *command_string;
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192 int pin[2], pout[2];
193 pid_t pid;
36e94dc5 194 char *shell;
16c343f1 195
9f304aaf 196 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
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197 shell = _PATH_BSHELL;
198
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199 /* Create pipes for communicating with the proxy. */
200 if (pipe(pin) < 0 || pipe(pout) < 0)
201 fatal("Could not create pipes to communicate with the proxy: %.100s",
202 strerror(errno));
203
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204 command_string = expand_proxy_command(proxy_command, options.user,
205 host, port);
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206 debug("Executing proxy command: %.500s", command_string);
207
208 /* Fork and execute the proxy command. */
209 if ((pid = fork()) == 0) {
210 char *argv[10];
211
212 /* Child. Permanently give up superuser privileges. */
213 permanently_drop_suid(original_real_uid);
214
215 /* Redirect stdin and stdout. */
216 close(pin[1]);
217 if (pin[0] != 0) {
218 if (dup2(pin[0], 0) < 0)
219 perror("dup2 stdin");
220 close(pin[0]);
221 }
222 close(pout[0]);
223 if (dup2(pout[1], 1) < 0)
224 perror("dup2 stdout");
225 /* Cannot be 1 because pin allocated two descriptors. */
226 close(pout[1]);
227
228 /* Stderr is left as it is so that error messages get
229 printed on the user's terminal. */
230 argv[0] = shell;
231 argv[1] = "-c";
232 argv[2] = command_string;
233 argv[3] = NULL;
234
235 /* Execute the proxy command. Note that we gave up any
236 extra privileges above. */
9f304aaf 237 signal(SIGPIPE, SIG_DFL);
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238 execv(argv[0], argv);
239 perror(argv[0]);
240 exit(1);
241 }
242 /* Parent. */
243 if (pid < 0)
244 fatal("fork failed: %.100s", strerror(errno));
245 else
246 proxy_command_pid = pid; /* save pid to clean up later */
247
248 /* Close child side of the descriptors. */
249 close(pin[0]);
250 close(pout[1]);
251
252 /* Free the command name. */
36e94dc5 253 free(command_string);
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254
255 /* Set the connection file descriptors. */
2c9c1408
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256 if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
257 return -1; /* ssh_packet_set_connection logs error */
16c343f1 258
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259 return 0;
260}
261
9f304aaf
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262void
263ssh_kill_proxy_command(void)
264{
265 /*
266 * Send SIGHUP to proxy command if used. We don't wait() in
267 * case it hangs and instead rely on init to reap the child
268 */
269 if (proxy_command_pid > 1)
270 kill(proxy_command_pid, SIGHUP);
271}
272
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273/*
274 * Creates a (possibly privileged) socket for use as the ssh connection.
275 */
276static int
277ssh_create_socket(int privileged, struct addrinfo *ai)
278{
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279 int sock, r, gaierr;
280 struct addrinfo hints, *res = NULL;
c29cd1cc 281
16c343f1 282 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
856ea928 283 if (sock < 0) {
36e94dc5 284 error("socket: %s", strerror(errno));
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285 return -1;
286 }
287 fcntl(sock, F_SETFD, FD_CLOEXEC);
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288
289 /* Bind the socket to an alternative local IP address */
36e94dc5 290 if (options.bind_address == NULL && !privileged)
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291 return sock;
292
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293 if (options.bind_address) {
294 memset(&hints, 0, sizeof(hints));
295 hints.ai_family = ai->ai_family;
296 hints.ai_socktype = ai->ai_socktype;
297 hints.ai_protocol = ai->ai_protocol;
298 hints.ai_flags = AI_PASSIVE;
299 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
300 if (gaierr) {
301 error("getaddrinfo: %s: %s", options.bind_address,
302 ssh_gai_strerror(gaierr));
303 close(sock);
304 return -1;
305 }
16c343f1 306 }
36e94dc5
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307 /*
308 * If we are running as root and want to connect to a privileged
309 * port, bind our own socket to a privileged port.
310 */
311 if (privileged) {
312 PRIV_START;
313 r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
314 PRIV_END;
315 if (r < 0) {
316 error("bindresvport_sa: af=%d %s", ai->ai_family,
317 strerror(errno));
318 goto fail;
319 }
320 } else {
321 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
322 error("bind: %s: %s", options.bind_address,
323 strerror(errno));
324 fail:
325 close(sock);
326 freeaddrinfo(res);
327 return -1;
328 }
16c343f1 329 }
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330 if (res != NULL)
331 freeaddrinfo(res);
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332 return sock;
333}
334
2c9c1408
MD
335/*
336 * Wait up to *timeoutp milliseconds for fd to be readable. Updates
337 * *timeoutp with time remaining.
338 * Returns 0 if fd ready or -1 on timeout or error (see errno).
339 */
16c343f1 340static int
2c9c1408 341waitrfd(int fd, int *timeoutp)
16c343f1 342{
2c9c1408
MD
343 struct pollfd pfd;
344 struct timeval t_start;
345 int oerrno, r;
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346
347 gettimeofday(&t_start, NULL);
2c9c1408
MD
348 pfd.fd = fd;
349 pfd.events = POLLIN;
350 for (; *timeoutp >= 0;) {
351 r = poll(&pfd, 1, *timeoutp);
352 oerrno = errno;
353 ms_subtract_diff(&t_start, timeoutp);
354 errno = oerrno;
355 if (r > 0)
356 return 0;
357 else if (r == -1 && errno != EAGAIN)
358 return -1;
359 else if (r == 0)
360 break;
16c343f1 361 }
2c9c1408
MD
362 /* timeout */
363 errno = ETIMEDOUT;
364 return -1;
365}
16c343f1 366
2c9c1408
MD
367static int
368timeout_connect(int sockfd, const struct sockaddr *serv_addr,
369 socklen_t addrlen, int *timeoutp)
370{
371 int optval = 0;
372 socklen_t optlen = sizeof(optval);
16c343f1 373
2c9c1408
MD
374 /* No timeout: just do a blocking connect() */
375 if (*timeoutp <= 0)
376 return connect(sockfd, serv_addr, addrlen);
16c343f1 377
2c9c1408
MD
378 set_nonblock(sockfd);
379 if (connect(sockfd, serv_addr, addrlen) == 0) {
380 /* Succeeded already? */
16c343f1 381 unset_nonblock(sockfd);
2c9c1408
MD
382 return 0;
383 } else if (errno != EINPROGRESS)
384 return -1;
16c343f1 385
2c9c1408
MD
386 if (waitrfd(sockfd, timeoutp) == -1)
387 return -1;
16c343f1 388
2c9c1408
MD
389 /* Completed or failed */
390 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
391 debug("getsockopt: %s", strerror(errno));
392 return -1;
16c343f1 393 }
2c9c1408
MD
394 if (optval != 0) {
395 errno = optval;
396 return -1;
397 }
398 unset_nonblock(sockfd);
399 return 0;
16c343f1
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400}
401
402/*
403 * Opens a TCP/IP connection to the remote server on the given host.
404 * The address of the remote host will be returned in hostaddr.
405 * If port is 0, the default port will be used. If needpriv is true,
406 * a privileged port will be allocated to make the connection.
407 * This requires super-user privileges if needpriv is true.
408 * Connection_attempts specifies the maximum number of tries (one per
409 * second). If proxy_command is non-NULL, it specifies the command (with %h
410 * and %p substituted for host and port, respectively) to use to contact
411 * the daemon.
412 */
36e94dc5 413static int
2c9c1408 414ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
36e94dc5
PA
415 struct sockaddr_storage *hostaddr, u_short port, int family,
416 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
16c343f1 417{
16c343f1
PA
418 int on = 1;
419 int sock = -1, attempt;
420 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
36e94dc5 421 struct addrinfo *ai;
16c343f1 422
e9778795
PA
423 debug2("%s: needpriv %d", __func__, needpriv);
424 memset(ntop, 0, sizeof(ntop));
425 memset(strport, 0, sizeof(strport));
16c343f1 426
16c343f1
PA
427 for (attempt = 0; attempt < connection_attempts; attempt++) {
428 if (attempt > 0) {
429 /* Sleep a moment before retrying. */
430 sleep(1);
431 debug("Trying again...");
432 }
433 /*
434 * Loop through addresses for this host, and try each one in
435 * sequence until the connection succeeds.
436 */
437 for (ai = aitop; ai; ai = ai->ai_next) {
36e94dc5
PA
438 if (ai->ai_family != AF_INET &&
439 ai->ai_family != AF_INET6)
16c343f1
PA
440 continue;
441 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
442 ntop, sizeof(ntop), strport, sizeof(strport),
443 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
e9778795 444 error("%s: getnameinfo failed", __func__);
16c343f1
PA
445 continue;
446 }
447 debug("Connecting to %.200s [%.100s] port %s.",
448 host, ntop, strport);
449
450 /* Create a socket for connecting. */
451 sock = ssh_create_socket(needpriv, ai);
452 if (sock < 0)
453 /* Any error is already output */
454 continue;
455
456 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
457 timeout_ms) >= 0) {
458 /* Successful connection. */
459 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
460 break;
461 } else {
462 debug("connect to address %s port %s: %s",
463 ntop, strport, strerror(errno));
464 close(sock);
465 sock = -1;
466 }
467 }
468 if (sock != -1)
469 break; /* Successful connection. */
470 }
471
16c343f1
PA
472 /* Return failure if we didn't get a successful connection. */
473 if (sock == -1) {
474 error("ssh: connect to host %s port %s: %s",
475 host, strport, strerror(errno));
476 return (-1);
477 }
478
479 debug("Connection established.");
480
481 /* Set SO_KEEPALIVE if requested. */
482 if (want_keepalive &&
483 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
484 sizeof(on)) < 0)
485 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
486
487 /* Set the connection. */
2c9c1408
MD
488 if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
489 return -1; /* ssh_packet_set_connection logs error */
16c343f1 490
2c9c1408 491 return 0;
16c343f1
PA
492}
493
36e94dc5 494int
2c9c1408 495ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
36e94dc5
PA
496 struct sockaddr_storage *hostaddr, u_short port, int family,
497 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
498{
499 if (options.proxy_command == NULL) {
2c9c1408
MD
500 return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
501 family, connection_attempts, timeout_ms, want_keepalive,
502 needpriv);
36e94dc5 503 } else if (strcmp(options.proxy_command, "-") == 0) {
2c9c1408
MD
504 if ((ssh_packet_set_connection(ssh,
505 STDIN_FILENO, STDOUT_FILENO)) == NULL)
506 return -1; /* ssh_packet_set_connection logs error */
507 return 0;
36e94dc5 508 } else if (options.proxy_use_fdpass) {
2c9c1408 509 return ssh_proxy_fdpass_connect(ssh, host, port,
36e94dc5
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510 options.proxy_command);
511 }
2c9c1408 512 return ssh_proxy_connect(ssh, host, port, options.proxy_command);
36e94dc5
PA
513}
514
515static void
516send_client_banner(int connection_out, int minor1)
517{
518 /* Send our own protocol version identification. */
2c9c1408
MD
519 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
520 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
e9778795 521 if (atomicio(vwrite, connection_out, client_version_string,
36e94dc5
PA
522 strlen(client_version_string)) != strlen(client_version_string))
523 fatal("write: %.100s", strerror(errno));
524 chop(client_version_string);
525 debug("Local version string %.100s", client_version_string);
526}
527
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528/*
529 * Waits for the server identification string, and sends our own
530 * identification string.
531 */
40c002af 532void
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533ssh_exchange_identification(int timeout_ms)
534{
535 char buf[256], remote_version[256]; /* must be same size! */
536 int remote_major, remote_minor, mismatch;
537 int connection_in = packet_get_connection_in();
538 int connection_out = packet_get_connection_out();
16c343f1
PA
539 u_int i, n;
540 size_t len;
2c9c1408 541 int rc;
16c343f1 542
2c9c1408 543 send_client_banner(connection_out, 0);
36e94dc5 544
16c343f1 545 /* Read other side's version identification. */
16c343f1
PA
546 for (n = 0;;) {
547 for (i = 0; i < sizeof(buf) - 1; i++) {
548 if (timeout_ms > 0) {
2c9c1408
MD
549 rc = waitrfd(connection_in, &timeout_ms);
550 if (rc == -1 && errno == ETIMEDOUT) {
16c343f1
PA
551 fatal("Connection timed out during "
552 "banner exchange");
2c9c1408
MD
553 } else if (rc == -1) {
554 fatal("%s: %s",
555 __func__, strerror(errno));
16c343f1
PA
556 }
557 }
558
e9778795 559 len = atomicio(read, connection_in, &buf[i], 1);
16c343f1
PA
560 if (len != 1 && errno == EPIPE)
561 fatal("ssh_exchange_identification: "
562 "Connection closed by remote host");
563 else if (len != 1)
564 fatal("ssh_exchange_identification: "
565 "read: %.100s", strerror(errno));
566 if (buf[i] == '\r') {
567 buf[i] = '\n';
568 buf[i + 1] = 0;
569 continue; /**XXX wait for \n */
570 }
571 if (buf[i] == '\n') {
572 buf[i + 1] = 0;
573 break;
574 }
575 if (++n > 65536)
576 fatal("ssh_exchange_identification: "
577 "No banner received");
578 }
579 buf[sizeof(buf) - 1] = 0;
580 if (strncmp(buf, "SSH-", 4) == 0)
581 break;
582 debug("ssh_exchange_identification: %s", buf);
583 }
584 server_version_string = xstrdup(buf);
16c343f1
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585
586 /*
587 * Check that the versions match. In future this might accept
588 * several versions and set appropriate flags to handle them.
589 */
590 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
591 &remote_major, &remote_minor, remote_version) != 3)
592 fatal("Bad remote protocol version identification: '%.100s'", buf);
593 debug("Remote protocol version %d.%d, remote software version %.100s",
594 remote_major, remote_minor, remote_version);
595
e9778795 596 active_state->compat = compat_datafellows(remote_version);
16c343f1
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597 mismatch = 0;
598
599 switch (remote_major) {
2c9c1408
MD
600 case 2:
601 break;
16c343f1 602 case 1:
2c9c1408 603 if (remote_minor != 99)
16c343f1 604 mismatch = 1;
16c343f1 605 break;
16c343f1
PA
606 default:
607 mismatch = 1;
608 break;
609 }
610 if (mismatch)
611 fatal("Protocol major versions differ: %d vs. %d",
2c9c1408 612 PROTOCOL_MAJOR_2, remote_major);
36e94dc5
PA
613 if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
614 fatal("Server version \"%.100s\" uses unsafe key agreement; "
615 "refusing connection", remote_version);
616 if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
617 logit("Server version \"%.100s\" uses unsafe RSA signature "
618 "scheme; disabling use of RSA keys", remote_version);
16c343f1 619 chop(server_version_string);
16c343f1
PA
620}
621
622/* defaults to 'no' */
623static int
624confirm(const char *prompt)
625{
626 const char *msg, *again = "Please type 'yes' or 'no': ";
627 char *p;
628 int ret = -1;
629
630 if (options.batch_mode)
631 return 0;
632 for (msg = prompt;;msg = again) {
633 p = read_passphrase(msg, RP_ECHO);
634 if (p == NULL ||
635 (p[0] == '\0') || (p[0] == '\n') ||
636 strncasecmp(p, "no", 2) == 0)
637 ret = 0;
638 if (p && strncasecmp(p, "yes", 3) == 0)
639 ret = 1;
36e94dc5 640 free(p);
16c343f1
PA
641 if (ret != -1)
642 return ret;
643 }
644}
645
856ea928 646static int
2c9c1408 647check_host_cert(const char *host, const struct sshkey *host_key)
856ea928
PA
648{
649 const char *reason;
650
651 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
652 error("%s", reason);
653 return 0;
654 }
36e94dc5 655 if (buffer_len(host_key->cert->critical) != 0) {
856ea928
PA
656 error("Certificate for %s contains unsupported "
657 "critical options(s)", host);
658 return 0;
659 }
660 return 1;
661}
662
9f304aaf
PA
663static int
664sockaddr_is_local(struct sockaddr *hostaddr)
665{
666 switch (hostaddr->sa_family) {
667 case AF_INET:
668 return (ntohl(((struct sockaddr_in *)hostaddr)->
669 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
670 case AF_INET6:
671 return IN6_IS_ADDR_LOOPBACK(
672 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
673 default:
674 return 0;
675 }
676}
677
678/*
679 * Prepare the hostname and ip address strings that are used to lookup
680 * host keys in known_hosts files. These may have a port number appended.
681 */
682void
683get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
684 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
685{
686 char ntop[NI_MAXHOST];
687 socklen_t addrlen;
688
689 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
690 case -1:
691 addrlen = 0;
692 break;
693 case AF_INET:
694 addrlen = sizeof(struct sockaddr_in);
695 break;
696 case AF_INET6:
697 addrlen = sizeof(struct sockaddr_in6);
698 break;
699 default:
700 addrlen = sizeof(struct sockaddr);
701 break;
702 }
703
704 /*
705 * We don't have the remote ip-address for connections
706 * using a proxy command
707 */
708 if (hostfile_ipaddr != NULL) {
709 if (options.proxy_command == NULL) {
710 if (getnameinfo(hostaddr, addrlen,
711 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
e9778795 712 fatal("%s: getnameinfo failed", __func__);
9f304aaf
PA
713 *hostfile_ipaddr = put_host_port(ntop, port);
714 } else {
715 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
716 "command>");
717 }
718 }
719
720 /*
721 * Allow the user to record the key under a different name or
722 * differentiate a non-standard port. This is useful for ssh
723 * tunneling over forwarded connections or if you run multiple
724 * sshd's on different ports on the same machine.
725 */
726 if (hostfile_hostname != NULL) {
727 if (options.host_key_alias != NULL) {
728 *hostfile_hostname = xstrdup(options.host_key_alias);
729 debug("using hostkeyalias: %s", *hostfile_hostname);
730 } else {
731 *hostfile_hostname = put_host_port(hostname, port);
732 }
733 }
734}
735
16c343f1
PA
736/*
737 * check whether the supplied host key is valid, return -1 if the key
1c188a7f 738 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
16c343f1
PA
739 */
740#define RDRW 0
741#define RDONLY 1
742#define ROQUIET 2
743static int
744check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
2c9c1408 745 struct sshkey *host_key, int readonly,
1c188a7f
PA
746 char **user_hostfiles, u_int num_user_hostfiles,
747 char **system_hostfiles, u_int num_system_hostfiles)
16c343f1 748{
1c188a7f
PA
749 HostStatus host_status;
750 HostStatus ip_status;
2c9c1408 751 struct sshkey *raw_key = NULL;
16c343f1 752 char *ip = NULL, *host = NULL;
3b69e377 753 char hostline[1000], *hostp, *fp, *ra;
16c343f1 754 char msg[1024];
1c188a7f
PA
755 const char *type;
756 const struct hostkey_entry *host_found, *ip_found;
9f304aaf 757 int len, cancelled_forwarding = 0;
1c188a7f 758 int local = sockaddr_is_local(hostaddr);
2c9c1408 759 int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
e9778795 760 int hostkey_trusted = 0; /* Known or explicitly accepted by user */
9f304aaf 761 struct hostkeys *host_hostkeys, *ip_hostkeys;
1c188a7f 762 u_int i;
16c343f1
PA
763
764 /*
765 * Force accepting of the host key for loopback/localhost. The
766 * problem is that if the home directory is NFS-mounted to multiple
767 * machines, localhost will refer to a different machine in each of
768 * them, and the user will get bogus HOST_CHANGED warnings. This
769 * essentially disables host authentication for localhost; however,
770 * this is probably not a real problem.
771 */
16c343f1
PA
772 if (options.no_host_authentication_for_localhost == 1 && local &&
773 options.host_key_alias == NULL) {
774 debug("Forcing accepting of host key for "
775 "loopback/localhost.");
776 return 0;
777 }
778
779 /*
9f304aaf
PA
780 * Prepare the hostname and address strings used for hostkey lookup.
781 * In some cases, these will have a port number appended.
16c343f1 782 */
9f304aaf 783 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
3b69e377 784
16c343f1
PA
785 /*
786 * Turn off check_host_ip if the connection is to localhost, via proxy
787 * command or if we don't have a hostname to compare with
788 */
789 if (options.check_host_ip && (local ||
790 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
791 options.check_host_ip = 0;
792
9f304aaf 793 host_hostkeys = init_hostkeys();
1c188a7f
PA
794 for (i = 0; i < num_user_hostfiles; i++)
795 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
796 for (i = 0; i < num_system_hostfiles; i++)
797 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
9f304aaf
PA
798
799 ip_hostkeys = NULL;
800 if (!want_cert && options.check_host_ip) {
801 ip_hostkeys = init_hostkeys();
1c188a7f
PA
802 for (i = 0; i < num_user_hostfiles; i++)
803 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
804 for (i = 0; i < num_system_hostfiles; i++)
805 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
16c343f1
PA
806 }
807
856ea928 808 retry:
9f304aaf 809 /* Reload these as they may have changed on cert->key downgrade */
2c9c1408
MD
810 want_cert = sshkey_is_cert(host_key);
811 type = sshkey_type(host_key);
856ea928 812
16c343f1
PA
813 /*
814 * Check if the host key is present in the user's list of known
815 * hosts or in the systemwide list.
816 */
9f304aaf
PA
817 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
818 &host_found);
819
16c343f1
PA
820 /*
821 * Also perform check for the ip address, skip the check if we are
856ea928
PA
822 * localhost, looking for a certificate, or the hostname was an ip
823 * address to begin with.
16c343f1 824 */
9f304aaf
PA
825 if (!want_cert && ip_hostkeys != NULL) {
826 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
827 &ip_found);
16c343f1 828 if (host_status == HOST_CHANGED &&
9f304aaf
PA
829 (ip_status != HOST_CHANGED ||
830 (ip_found != NULL &&
2c9c1408 831 !sshkey_equal(ip_found->key, host_found->key))))
16c343f1 832 host_ip_differ = 1;
16c343f1
PA
833 } else
834 ip_status = host_status;
835
16c343f1
PA
836 switch (host_status) {
837 case HOST_OK:
838 /* The host is known and the key matches. */
856ea928
PA
839 debug("Host '%.200s' is known and matches the %s host %s.",
840 host, type, want_cert ? "certificate" : "key");
9f304aaf
PA
841 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
842 host_found->file, host_found->line);
2c9c1408
MD
843 if (want_cert &&
844 !check_host_cert(options.host_key_alias == NULL ?
845 hostname : options.host_key_alias, host_key))
856ea928 846 goto fail;
16c343f1 847 if (options.check_host_ip && ip_status == HOST_NEW) {
856ea928 848 if (readonly || want_cert)
16c343f1
PA
849 logit("%s host key for IP address "
850 "'%.128s' not in list of known hosts.",
851 type, ip);
1c188a7f 852 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
16c343f1
PA
853 host_key, options.hash_known_hosts))
854 logit("Failed to add the %s host key for IP "
855 "address '%.128s' to the list of known "
e9778795 856 "hosts (%.500s).", type, ip,
1c188a7f 857 user_hostfiles[0]);
16c343f1
PA
858 else
859 logit("Warning: Permanently added the %s host "
860 "key for IP address '%.128s' to the list "
861 "of known hosts.", type, ip);
3b69e377 862 } else if (options.visual_host_key) {
e9778795
PA
863 fp = sshkey_fingerprint(host_key,
864 options.fingerprint_hash, SSH_FP_DEFAULT);
865 ra = sshkey_fingerprint(host_key,
866 options.fingerprint_hash, SSH_FP_RANDOMART);
867 if (fp == NULL || ra == NULL)
868 fatal("%s: sshkey_fingerprint fail", __func__);
869 logit("Host key fingerprint is %s\n%s", fp, ra);
36e94dc5
PA
870 free(ra);
871 free(fp);
16c343f1 872 }
e9778795 873 hostkey_trusted = 1;
16c343f1
PA
874 break;
875 case HOST_NEW:
876 if (options.host_key_alias == NULL && port != 0 &&
877 port != SSH_DEFAULT_PORT) {
878 debug("checking without port identifier");
cb5eb4f1 879 if (check_host_key(hostname, hostaddr, 0, host_key,
1c188a7f
PA
880 ROQUIET, user_hostfiles, num_user_hostfiles,
881 system_hostfiles, num_system_hostfiles) == 0) {
16c343f1
PA
882 debug("found matching key w/out port");
883 break;
884 }
885 }
856ea928 886 if (readonly || want_cert)
16c343f1
PA
887 goto fail;
888 /* The host is new. */
2c9c1408
MD
889 if (options.strict_host_key_checking ==
890 SSH_STRICT_HOSTKEY_YES) {
16c343f1
PA
891 /*
892 * User has requested strict host key checking. We
893 * will not add the host key automatically. The only
894 * alternative left is to abort.
895 */
896 error("No %s host key is known for %.200s and you "
897 "have requested strict checking.", type, host);
898 goto fail;
2c9c1408
MD
899 } else if (options.strict_host_key_checking ==
900 SSH_STRICT_HOSTKEY_ASK) {
16c343f1
PA
901 char msg1[1024], msg2[1024];
902
9f304aaf 903 if (show_other_keys(host_hostkeys, host_key))
16c343f1
PA
904 snprintf(msg1, sizeof(msg1),
905 "\nbut keys of different type are already"
906 " known for this host.");
907 else
908 snprintf(msg1, sizeof(msg1), ".");
909 /* The default */
e9778795
PA
910 fp = sshkey_fingerprint(host_key,
911 options.fingerprint_hash, SSH_FP_DEFAULT);
912 ra = sshkey_fingerprint(host_key,
913 options.fingerprint_hash, SSH_FP_RANDOMART);
914 if (fp == NULL || ra == NULL)
915 fatal("%s: sshkey_fingerprint fail", __func__);
16c343f1
PA
916 msg2[0] = '\0';
917 if (options.verify_host_key_dns) {
918 if (matching_host_key_dns)
919 snprintf(msg2, sizeof(msg2),
920 "Matching host key fingerprint"
921 " found in DNS.\n");
922 else
923 snprintf(msg2, sizeof(msg2),
924 "No matching host key fingerprint"
925 " found in DNS.\n");
926 }
927 snprintf(msg, sizeof(msg),
928 "The authenticity of host '%.200s (%s)' can't be "
929 "established%s\n"
3b69e377 930 "%s key fingerprint is %s.%s%s\n%s"
16c343f1
PA
931 "Are you sure you want to continue connecting "
932 "(yes/no)? ",
3b69e377
PA
933 host, ip, msg1, type, fp,
934 options.visual_host_key ? "\n" : "",
935 options.visual_host_key ? ra : "",
936 msg2);
36e94dc5
PA
937 free(ra);
938 free(fp);
16c343f1
PA
939 if (!confirm(msg))
940 goto fail;
e9778795 941 hostkey_trusted = 1; /* user explicitly confirmed */
16c343f1
PA
942 }
943 /*
2c9c1408
MD
944 * If in "new" or "off" strict mode, add the key automatically
945 * to the local known_hosts file.
16c343f1
PA
946 */
947 if (options.check_host_ip && ip_status == HOST_NEW) {
9f304aaf 948 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
16c343f1
PA
949 hostp = hostline;
950 if (options.hash_known_hosts) {
951 /* Add hash of host and IP separately */
1c188a7f
PA
952 r = add_host_to_hostfile(user_hostfiles[0],
953 host, host_key, options.hash_known_hosts) &&
954 add_host_to_hostfile(user_hostfiles[0], ip,
16c343f1
PA
955 host_key, options.hash_known_hosts);
956 } else {
957 /* Add unhashed "host,ip" */
1c188a7f 958 r = add_host_to_hostfile(user_hostfiles[0],
16c343f1
PA
959 hostline, host_key,
960 options.hash_known_hosts);
961 }
962 } else {
1c188a7f
PA
963 r = add_host_to_hostfile(user_hostfiles[0], host,
964 host_key, options.hash_known_hosts);
16c343f1
PA
965 hostp = host;
966 }
967
968 if (!r)
969 logit("Failed to add the host to the list of known "
1c188a7f 970 "hosts (%.500s).", user_hostfiles[0]);
16c343f1
PA
971 else
972 logit("Warning: Permanently added '%.200s' (%s) to the "
973 "list of known hosts.", hostp, type);
974 break;
856ea928
PA
975 case HOST_REVOKED:
976 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
977 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
978 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
979 error("The %s host key for %s is marked as revoked.", type, host);
980 error("This could mean that a stolen key is being used to");
981 error("impersonate this host.");
982
983 /*
984 * If strict host key checking is in use, the user will have
985 * to edit the key manually and we can only abort.
986 */
2c9c1408
MD
987 if (options.strict_host_key_checking !=
988 SSH_STRICT_HOSTKEY_OFF) {
856ea928
PA
989 error("%s host key for %.200s was revoked and you have "
990 "requested strict checking.", type, host);
991 goto fail;
992 }
993 goto continue_unsafe;
994
16c343f1 995 case HOST_CHANGED:
856ea928
PA
996 if (want_cert) {
997 /*
998 * This is only a debug() since it is valid to have
999 * CAs with wildcard DNS matches that don't match
1000 * all hosts that one might visit.
1001 */
1002 debug("Host certificate authority does not "
9f304aaf
PA
1003 "match %s in %s:%lu", CA_MARKER,
1004 host_found->file, host_found->line);
856ea928
PA
1005 goto fail;
1006 }
16c343f1
PA
1007 if (readonly == ROQUIET)
1008 goto fail;
1009 if (options.check_host_ip && host_ip_differ) {
1010 char *key_msg;
1011 if (ip_status == HOST_NEW)
1012 key_msg = "is unknown";
1013 else if (ip_status == HOST_OK)
1014 key_msg = "is unchanged";
1015 else
1016 key_msg = "has a different value";
1017 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1018 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1019 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1020 error("The %s host key for %s has changed,", type, host);
3b69e377 1021 error("and the key for the corresponding IP address %s", ip);
16c343f1
PA
1022 error("%s. This could either mean that", key_msg);
1023 error("DNS SPOOFING is happening or the IP address for the host");
1024 error("and its host key have changed at the same time.");
1025 if (ip_status != HOST_NEW)
9f304aaf
PA
1026 error("Offending key for IP in %s:%lu",
1027 ip_found->file, ip_found->line);
16c343f1
PA
1028 }
1029 /* The host key has changed. */
1030 warn_changed_key(host_key);
1031 error("Add correct host key in %.100s to get rid of this message.",
1c188a7f 1032 user_hostfiles[0]);
2c9c1408
MD
1033 error("Offending %s key in %s:%lu",
1034 sshkey_type(host_found->key),
9f304aaf 1035 host_found->file, host_found->line);
16c343f1
PA
1036
1037 /*
1038 * If strict host key checking is in use, the user will have
1039 * to edit the key manually and we can only abort.
1040 */
2c9c1408
MD
1041 if (options.strict_host_key_checking !=
1042 SSH_STRICT_HOSTKEY_OFF) {
16c343f1
PA
1043 error("%s host key for %.200s has changed and you have "
1044 "requested strict checking.", type, host);
1045 goto fail;
1046 }
1047
856ea928 1048 continue_unsafe:
16c343f1
PA
1049 /*
1050 * If strict host key checking has not been requested, allow
1051 * the connection but without MITM-able authentication or
1052 * forwarding.
1053 */
1054 if (options.password_authentication) {
1055 error("Password authentication is disabled to avoid "
1056 "man-in-the-middle attacks.");
1057 options.password_authentication = 0;
3b69e377 1058 cancelled_forwarding = 1;
16c343f1
PA
1059 }
1060 if (options.kbd_interactive_authentication) {
1061 error("Keyboard-interactive authentication is disabled"
1062 " to avoid man-in-the-middle attacks.");
1063 options.kbd_interactive_authentication = 0;
1064 options.challenge_response_authentication = 0;
3b69e377 1065 cancelled_forwarding = 1;
16c343f1
PA
1066 }
1067 if (options.challenge_response_authentication) {
1068 error("Challenge/response authentication is disabled"
1069 " to avoid man-in-the-middle attacks.");
1070 options.challenge_response_authentication = 0;
3b69e377 1071 cancelled_forwarding = 1;
16c343f1
PA
1072 }
1073 if (options.forward_agent) {
1074 error("Agent forwarding is disabled to avoid "
1075 "man-in-the-middle attacks.");
1076 options.forward_agent = 0;
3b69e377 1077 cancelled_forwarding = 1;
16c343f1
PA
1078 }
1079 if (options.forward_x11) {
1080 error("X11 forwarding is disabled to avoid "
1081 "man-in-the-middle attacks.");
1082 options.forward_x11 = 0;
3b69e377 1083 cancelled_forwarding = 1;
16c343f1
PA
1084 }
1085 if (options.num_local_forwards > 0 ||
1086 options.num_remote_forwards > 0) {
1087 error("Port forwarding is disabled to avoid "
1088 "man-in-the-middle attacks.");
1089 options.num_local_forwards =
1090 options.num_remote_forwards = 0;
3b69e377 1091 cancelled_forwarding = 1;
16c343f1
PA
1092 }
1093 if (options.tun_open != SSH_TUNMODE_NO) {
1094 error("Tunnel forwarding is disabled to avoid "
1095 "man-in-the-middle attacks.");
1096 options.tun_open = SSH_TUNMODE_NO;
3b69e377 1097 cancelled_forwarding = 1;
16c343f1 1098 }
3b69e377
PA
1099 if (options.exit_on_forward_failure && cancelled_forwarding)
1100 fatal("Error: forwarding disabled due to host key "
1101 "check failure");
1102
16c343f1
PA
1103 /*
1104 * XXX Should permit the user to change to use the new id.
1105 * This could be done by converting the host key to an
1106 * identifying sentence, tell that the host identifies itself
856ea928 1107 * by that sentence, and ask the user if he/she wishes to
16c343f1
PA
1108 * accept the authentication.
1109 */
1110 break;
1111 case HOST_FOUND:
1112 fatal("internal error");
1113 break;
1114 }
1115
1116 if (options.check_host_ip && host_status != HOST_CHANGED &&
1117 ip_status == HOST_CHANGED) {
1118 snprintf(msg, sizeof(msg),
1119 "Warning: the %s host key for '%.200s' "
1120 "differs from the key for the IP address '%.128s'"
9f304aaf
PA
1121 "\nOffending key for IP in %s:%lu",
1122 type, host, ip, ip_found->file, ip_found->line);
16c343f1
PA
1123 if (host_status == HOST_OK) {
1124 len = strlen(msg);
1125 snprintf(msg + len, sizeof(msg) - len,
9f304aaf
PA
1126 "\nMatching host key in %s:%lu",
1127 host_found->file, host_found->line);
16c343f1 1128 }
2c9c1408
MD
1129 if (options.strict_host_key_checking ==
1130 SSH_STRICT_HOSTKEY_ASK) {
16c343f1
PA
1131 strlcat(msg, "\nAre you sure you want "
1132 "to continue connecting (yes/no)? ", sizeof(msg));
1133 if (!confirm(msg))
1134 goto fail;
2c9c1408
MD
1135 } else if (options.strict_host_key_checking !=
1136 SSH_STRICT_HOSTKEY_OFF) {
1137 logit("%s", msg);
1138 error("Exiting, you have requested strict checking.");
1139 goto fail;
16c343f1
PA
1140 } else {
1141 logit("%s", msg);
1142 }
1143 }
1144
e9778795
PA
1145 if (!hostkey_trusted && options.update_hostkeys) {
1146 debug("%s: hostkey not known or explicitly trusted: "
1147 "disabling UpdateHostkeys", __func__);
1148 options.update_hostkeys = 0;
1149 }
1150
36e94dc5
PA
1151 free(ip);
1152 free(host);
9f304aaf
PA
1153 if (host_hostkeys != NULL)
1154 free_hostkeys(host_hostkeys);
1155 if (ip_hostkeys != NULL)
1156 free_hostkeys(ip_hostkeys);
16c343f1
PA
1157 return 0;
1158
1159fail:
856ea928
PA
1160 if (want_cert && host_status != HOST_REVOKED) {
1161 /*
1162 * No matching certificate. Downgrade cert to raw key and
1163 * search normally.
1164 */
1165 debug("No matching CA found. Retry with plain key");
2c9c1408
MD
1166 if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1167 fatal("%s: sshkey_from_private: %s",
1168 __func__, ssh_err(r));
1169 if ((r = sshkey_drop_cert(raw_key)) != 0)
1170 fatal("Couldn't drop certificate: %s", ssh_err(r));
856ea928
PA
1171 host_key = raw_key;
1172 goto retry;
1173 }
1174 if (raw_key != NULL)
2c9c1408 1175 sshkey_free(raw_key);
36e94dc5
PA
1176 free(ip);
1177 free(host);
9f304aaf
PA
1178 if (host_hostkeys != NULL)
1179 free_hostkeys(host_hostkeys);
1180 if (ip_hostkeys != NULL)
1181 free_hostkeys(ip_hostkeys);
16c343f1
PA
1182 return -1;
1183}
1184
1185/* returns 0 if key verifies or -1 if key does NOT verify */
1186int
2c9c1408 1187verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
16c343f1 1188{
e9778795 1189 u_int i;
36e94dc5 1190 int r = -1, flags = 0;
e9778795
PA
1191 char valid[64], *fp = NULL, *cafp = NULL;
1192 struct sshkey *plain = NULL;
1193
1194 if ((fp = sshkey_fingerprint(host_key,
1195 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1196 error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1197 r = -1;
1198 goto out;
1199 }
9f304aaf 1200
e9778795
PA
1201 if (sshkey_is_cert(host_key)) {
1202 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1203 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1204 error("%s: fingerprint CA key: %s",
1205 __func__, ssh_err(r));
1206 r = -1;
1207 goto out;
1208 }
1209 sshkey_format_cert_validity(host_key->cert,
1210 valid, sizeof(valid));
1211 debug("Server host certificate: %s %s, serial %llu "
1212 "ID \"%s\" CA %s %s valid %s",
1213 sshkey_ssh_name(host_key), fp,
1214 (unsigned long long)host_key->cert->serial,
1215 host_key->cert->key_id,
1216 sshkey_ssh_name(host_key->cert->signature_key), cafp,
1217 valid);
1218 for (i = 0; i < host_key->cert->nprincipals; i++) {
1219 debug2("Server host certificate hostname: %s",
1220 host_key->cert->principals[i]);
1221 }
1222 } else {
2c9c1408 1223 debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
e9778795 1224 }
16c343f1 1225
e9778795
PA
1226 if (sshkey_equal(previous_host_key, host_key)) {
1227 debug2("%s: server host key %s %s matches cached key",
1228 __func__, sshkey_type(host_key), fp);
1229 r = 0;
1230 goto out;
1231 }
1232
1233 /* Check in RevokedHostKeys file if specified */
1234 if (options.revoked_host_keys != NULL) {
1235 r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1236 switch (r) {
1237 case 0:
1238 break; /* not revoked */
1239 case SSH_ERR_KEY_REVOKED:
1240 error("Host key %s %s revoked by file %s",
1241 sshkey_type(host_key), fp,
1242 options.revoked_host_keys);
1243 r = -1;
1244 goto out;
1245 default:
1246 error("Error checking host key %s %s in "
1247 "revoked keys file %s: %s", sshkey_type(host_key),
1248 fp, options.revoked_host_keys, ssh_err(r));
1249 r = -1;
1250 goto out;
1251 }
36e94dc5 1252 }
16c343f1 1253
36e94dc5
PA
1254 if (options.verify_host_key_dns) {
1255 /*
1256 * XXX certs are not yet supported for DNS, so downgrade
1257 * them and try the plain key.
1258 */
e9778795
PA
1259 if ((r = sshkey_from_private(host_key, &plain)) != 0)
1260 goto out;
1261 if (sshkey_is_cert(plain))
1262 sshkey_drop_cert(plain);
36e94dc5
PA
1263 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1264 if (flags & DNS_VERIFY_FOUND) {
1265 if (options.verify_host_key_dns == 1 &&
1266 flags & DNS_VERIFY_MATCH &&
1267 flags & DNS_VERIFY_SECURE) {
36e94dc5 1268 r = 0;
e9778795 1269 goto out;
36e94dc5
PA
1270 }
1271 if (flags & DNS_VERIFY_MATCH) {
1272 matching_host_key_dns = 1;
1273 } else {
1274 warn_changed_key(plain);
1275 error("Update the SSHFP RR in DNS "
1276 "with the new host key to get rid "
1277 "of this message.");
1278 }
16c343f1
PA
1279 }
1280 }
1281 }
36e94dc5 1282 r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1c188a7f
PA
1283 options.user_hostfiles, options.num_user_hostfiles,
1284 options.system_hostfiles, options.num_system_hostfiles);
36e94dc5 1285
e9778795
PA
1286out:
1287 sshkey_free(plain);
1288 free(fp);
1289 free(cafp);
36e94dc5 1290 if (r == 0 && host_key != NULL) {
2c9c1408
MD
1291 sshkey_free(previous_host_key);
1292 r = sshkey_from_private(host_key, &previous_host_key);
36e94dc5
PA
1293 }
1294
1295 return r;
16c343f1
PA
1296}
1297
1298/*
1299 * Starts a dialog with the server, and authenticates the current user on the
1300 * server. This does not need any extra privileges. The basic connection
1301 * to the server must already have been established before this is called.
1302 * If login fails, this function prints an error and never returns.
1303 * This function does not require super-user privileges.
1304 */
1305void
1306ssh_login(Sensitive *sensitive, const char *orighost,
9f304aaf 1307 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
16c343f1 1308{
36e94dc5 1309 char *host;
16c343f1
PA
1310 char *server_user, *local_user;
1311
1312 local_user = xstrdup(pw->pw_name);
1313 server_user = options.user ? options.user : local_user;
1314
1315 /* Convert the user-supplied hostname into all lowercase. */
1316 host = xstrdup(orighost);
36e94dc5 1317 lowercase(host);
16c343f1
PA
1318
1319 /* Exchange protocol version identification strings with the server. */
1320 ssh_exchange_identification(timeout_ms);
1321
1322 /* Put the connection into non-blocking mode. */
1323 packet_set_nonblocking();
1324
1325 /* key exchange */
1326 /* authenticate user */
e9778795 1327 debug("Authenticating to %s:%d as '%s'", host, port, server_user);
2c9c1408
MD
1328 ssh_kex2(host, hostaddr, port);
1329 ssh_userauth2(local_user, server_user, host, sensitive);
36e94dc5 1330 free(local_user);
16c343f1
PA
1331}
1332
1333void
1334ssh_put_password(char *password)
1335{
1336 int size;
1337 char *padded;
1338
1339 if (datafellows & SSH_BUG_PASSWORDPAD) {
1340 packet_put_cstring(password);
1341 return;
1342 }
2c9c1408 1343 size = ROUNDUP(strlen(password) + 1, 32);
16c343f1
PA
1344 padded = xcalloc(1, size);
1345 strlcpy(padded, password, size);
1346 packet_put_string(padded, size);
36e94dc5
PA
1347 explicit_bzero(padded, size);
1348 free(padded);
16c343f1
PA
1349}
1350
16c343f1
PA
1351/* print all known host keys for a given host, but skip keys of given type */
1352static int
2c9c1408 1353show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
16c343f1 1354{
36e94dc5 1355 int type[] = {
36e94dc5
PA
1356 KEY_RSA,
1357 KEY_DSA,
1358 KEY_ECDSA,
1359 KEY_ED25519,
1360 -1
1361 };
9f304aaf
PA
1362 int i, ret = 0;
1363 char *fp, *ra;
1364 const struct hostkey_entry *found;
16c343f1
PA
1365
1366 for (i = 0; type[i] != -1; i++) {
1367 if (type[i] == key->type)
1368 continue;
9f304aaf 1369 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
16c343f1 1370 continue;
e9778795
PA
1371 fp = sshkey_fingerprint(found->key,
1372 options.fingerprint_hash, SSH_FP_DEFAULT);
1373 ra = sshkey_fingerprint(found->key,
1374 options.fingerprint_hash, SSH_FP_RANDOMART);
1375 if (fp == NULL || ra == NULL)
1376 fatal("%s: sshkey_fingerprint fail", __func__);
9f304aaf
PA
1377 logit("WARNING: %s key found for host %s\n"
1378 "in %s:%lu\n"
1379 "%s key fingerprint %s.",
1380 key_type(found->key),
1381 found->host, found->file, found->line,
1382 key_type(found->key), fp);
1383 if (options.visual_host_key)
1384 logit("%s", ra);
36e94dc5
PA
1385 free(ra);
1386 free(fp);
9f304aaf 1387 ret = 1;
16c343f1 1388 }
9f304aaf 1389 return ret;
16c343f1
PA
1390}
1391
1392static void
2c9c1408 1393warn_changed_key(struct sshkey *host_key)
16c343f1
PA
1394{
1395 char *fp;
16c343f1 1396
e9778795
PA
1397 fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1398 SSH_FP_DEFAULT);
1399 if (fp == NULL)
1400 fatal("%s: sshkey_fingerprint fail", __func__);
16c343f1
PA
1401
1402 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1403 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1404 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1405 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1406 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
9f304aaf 1407 error("It is also possible that a host key has just been changed.");
16c343f1 1408 error("The fingerprint for the %s key sent by the remote host is\n%s.",
9f304aaf 1409 key_type(host_key), fp);
16c343f1
PA
1410 error("Please contact your system administrator.");
1411
36e94dc5 1412 free(fp);
16c343f1
PA
1413}
1414
1415/*
1416 * Execute a local command
1417 */
1418int
1419ssh_local_cmd(const char *args)
1420{
1421 char *shell;
1422 pid_t pid;
1423 int status;
9f304aaf 1424 void (*osighand)(int);
16c343f1
PA
1425
1426 if (!options.permit_local_command ||
1427 args == NULL || !*args)
1428 return (1);
1429
9f304aaf 1430 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
16c343f1
PA
1431 shell = _PATH_BSHELL;
1432
9f304aaf 1433 osighand = signal(SIGCHLD, SIG_DFL);
16c343f1
PA
1434 pid = fork();
1435 if (pid == 0) {
9f304aaf 1436 signal(SIGPIPE, SIG_DFL);
16c343f1
PA
1437 debug3("Executing %s -c \"%s\"", shell, args);
1438 execl(shell, shell, "-c", args, (char *)NULL);
1439 error("Couldn't execute %s -c \"%s\": %s",
1440 shell, args, strerror(errno));
1441 _exit(1);
1442 } else if (pid == -1)
1443 fatal("fork failed: %.100s", strerror(errno));
1444 while (waitpid(pid, &status, 0) == -1)
1445 if (errno != EINTR)
1446 fatal("Couldn't wait for child: %s", strerror(errno));
9f304aaf 1447 signal(SIGCHLD, osighand);
16c343f1
PA
1448
1449 if (!WIFEXITED(status))
1450 return (1);
1451
1452 return (WEXITSTATUS(status));
1453}
e9778795
PA
1454
1455void
2c9c1408 1456maybe_add_key_to_agent(char *authfile, struct sshkey *private, char *comment,
e9778795
PA
1457 char *passphrase)
1458{
1459 int auth_sock = -1, r;
1460
1461 if (options.add_keys_to_agent == 0)
1462 return;
1463
1464 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1465 debug3("no authentication agent, not adding key");
1466 return;
1467 }
1468
1469 if (options.add_keys_to_agent == 2 &&
1470 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1471 debug3("user denied adding this key");
2c9c1408 1472 close(auth_sock);
e9778795
PA
1473 return;
1474 }
1475
1476 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1477 (options.add_keys_to_agent == 3))) == 0)
1478 debug("identity added to agent: %s", authfile);
1479 else
1480 debug("could not add identity to agent: %s (%d)", authfile, r);
2c9c1408 1481 close(auth_sock);
e9778795 1482}