xref: /freebsd/crypto/openssh/sshconnect.c (revision 7661de35d15f582ab33e3bd6b8d909601557e436)
1 /* $OpenBSD: sshconnect.c,v 1.244 2014/01/09 23:26:48 djm Exp $ */
2 /* $FreeBSD$ */
3 /*
4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6  *                    All rights reserved
7  * Code to connect to a remote host, and to perform the client side of the
8  * login (authentication) dialog.
9  *
10  * As far as I am concerned, the code I have written for this software
11  * can be used freely for any purpose.  Any derived versions of this
12  * software must be clearly marked as such, and if the derived work is
13  * incompatible with the protocol description in the RFC file, it must be
14  * called by a name other than "ssh" or "Secure Shell".
15  */
16 
17 #include "includes.h"
18 
19 #include <sys/types.h>
20 #include <sys/wait.h>
21 #include <sys/stat.h>
22 #include <sys/socket.h>
23 #ifdef HAVE_SYS_TIME_H
24 # include <sys/time.h>
25 #endif
26 
27 #include <netinet/in.h>
28 #include <arpa/inet.h>
29 #include <rpc/rpc.h>
30 
31 #include <ctype.h>
32 #include <errno.h>
33 #include <fcntl.h>
34 #include <netdb.h>
35 #ifdef HAVE_PATHS_H
36 #include <paths.h>
37 #endif
38 #include <pwd.h>
39 #include <signal.h>
40 #include <stdarg.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <unistd.h>
45 
46 #include "xmalloc.h"
47 #include "key.h"
48 #include "hostfile.h"
49 #include "ssh.h"
50 #include "rsa.h"
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"
59 #include "readconf.h"
60 #include "atomicio.h"
61 #include "misc.h"
62 #include "dns.h"
63 #include "roaming.h"
64 #include "monitor_fdpass.h"
65 #include "ssh2.h"
66 #include "version.h"
67 
68 char *client_version_string = NULL;
69 char *server_version_string = NULL;
70 
71 static int matching_host_key_dns = 0;
72 
73 static pid_t proxy_command_pid = 0;
74 
75 /* import */
76 extern Options options;
77 extern char *__progname;
78 extern uid_t original_real_uid;
79 extern uid_t original_effective_uid;
80 
81 static int show_other_keys(struct hostkeys *, Key *);
82 static void warn_changed_key(Key *);
83 
84 /* Expand a proxy command */
85 static char *
86 expand_proxy_command(const char *proxy_command, const char *user,
87     const char *host, int port)
88 {
89 	char *tmp, *ret, strport[NI_MAXSERV];
90 
91 	snprintf(strport, sizeof strport, "%d", port);
92 	xasprintf(&tmp, "exec %s", proxy_command);
93 	ret = percent_expand(tmp, "h", host, "p", strport,
94 	    "r", options.user, (char *)NULL);
95 	free(tmp);
96 	return ret;
97 }
98 
99 /*
100  * Connect to the given ssh server using a proxy command that passes a
101  * a connected fd back to us.
102  */
103 static int
104 ssh_proxy_fdpass_connect(const char *host, u_short port,
105     const char *proxy_command)
106 {
107 	char *command_string;
108 	int sp[2], sock;
109 	pid_t pid;
110 	char *shell;
111 
112 	if ((shell = getenv("SHELL")) == NULL)
113 		shell = _PATH_BSHELL;
114 
115 	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
116 		fatal("Could not create socketpair to communicate with "
117 		    "proxy dialer: %.100s", strerror(errno));
118 
119 	command_string = expand_proxy_command(proxy_command, options.user,
120 	    host, port);
121 	debug("Executing proxy dialer command: %.500s", command_string);
122 
123 	/* Fork and execute the proxy command. */
124 	if ((pid = fork()) == 0) {
125 		char *argv[10];
126 
127 		/* Child.  Permanently give up superuser privileges. */
128 		permanently_drop_suid(original_real_uid);
129 
130 		close(sp[1]);
131 		/* Redirect stdin and stdout. */
132 		if (sp[0] != 0) {
133 			if (dup2(sp[0], 0) < 0)
134 				perror("dup2 stdin");
135 		}
136 		if (sp[0] != 1) {
137 			if (dup2(sp[0], 1) < 0)
138 				perror("dup2 stdout");
139 		}
140 		if (sp[0] >= 2)
141 			close(sp[0]);
142 
143 		/*
144 		 * Stderr is left as it is so that error messages get
145 		 * printed on the user's terminal.
146 		 */
147 		argv[0] = shell;
148 		argv[1] = "-c";
149 		argv[2] = command_string;
150 		argv[3] = NULL;
151 
152 		/*
153 		 * Execute the proxy command.
154 		 * Note that we gave up any extra privileges above.
155 		 */
156 		execv(argv[0], argv);
157 		perror(argv[0]);
158 		exit(1);
159 	}
160 	/* Parent. */
161 	if (pid < 0)
162 		fatal("fork failed: %.100s", strerror(errno));
163 	close(sp[0]);
164 	free(command_string);
165 
166 	if ((sock = mm_receive_fd(sp[1])) == -1)
167 		fatal("proxy dialer did not pass back a connection");
168 
169 	while (waitpid(pid, NULL, 0) == -1)
170 		if (errno != EINTR)
171 			fatal("Couldn't wait for child: %s", strerror(errno));
172 
173 	/* Set the connection file descriptors. */
174 	packet_set_connection(sock, sock);
175 
176 	return 0;
177 }
178 
179 /*
180  * Connect to the given ssh server using a proxy command.
181  */
182 static int
183 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
184 {
185 	char *command_string;
186 	int pin[2], pout[2];
187 	pid_t pid;
188 	char *shell;
189 
190 	if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
191 		shell = _PATH_BSHELL;
192 
193 	/* Create pipes for communicating with the proxy. */
194 	if (pipe(pin) < 0 || pipe(pout) < 0)
195 		fatal("Could not create pipes to communicate with the proxy: %.100s",
196 		    strerror(errno));
197 
198 	command_string = expand_proxy_command(proxy_command, options.user,
199 	    host, port);
200 	debug("Executing proxy command: %.500s", command_string);
201 
202 	/* Fork and execute the proxy command. */
203 	if ((pid = fork()) == 0) {
204 		char *argv[10];
205 
206 		/* Child.  Permanently give up superuser privileges. */
207 		permanently_drop_suid(original_real_uid);
208 
209 		/* Redirect stdin and stdout. */
210 		close(pin[1]);
211 		if (pin[0] != 0) {
212 			if (dup2(pin[0], 0) < 0)
213 				perror("dup2 stdin");
214 			close(pin[0]);
215 		}
216 		close(pout[0]);
217 		if (dup2(pout[1], 1) < 0)
218 			perror("dup2 stdout");
219 		/* Cannot be 1 because pin allocated two descriptors. */
220 		close(pout[1]);
221 
222 		/* Stderr is left as it is so that error messages get
223 		   printed on the user's terminal. */
224 		argv[0] = shell;
225 		argv[1] = "-c";
226 		argv[2] = command_string;
227 		argv[3] = NULL;
228 
229 		/* Execute the proxy command.  Note that we gave up any
230 		   extra privileges above. */
231 		signal(SIGPIPE, SIG_DFL);
232 		execv(argv[0], argv);
233 		perror(argv[0]);
234 		exit(1);
235 	}
236 	/* Parent. */
237 	if (pid < 0)
238 		fatal("fork failed: %.100s", strerror(errno));
239 	else
240 		proxy_command_pid = pid; /* save pid to clean up later */
241 
242 	/* Close child side of the descriptors. */
243 	close(pin[0]);
244 	close(pout[1]);
245 
246 	/* Free the command name. */
247 	free(command_string);
248 
249 	/* Set the connection file descriptors. */
250 	packet_set_connection(pout[0], pin[1]);
251 
252 	/* Indicate OK return */
253 	return 0;
254 }
255 
256 void
257 ssh_kill_proxy_command(void)
258 {
259 	/*
260 	 * Send SIGHUP to proxy command if used. We don't wait() in
261 	 * case it hangs and instead rely on init to reap the child
262 	 */
263 	if (proxy_command_pid > 1)
264 		kill(proxy_command_pid, SIGHUP);
265 }
266 
267 /*
268  * Set TCP receive buffer if requested.
269  * Note: tuning needs to happen after the socket is created but before the
270  * connection happens so winscale is negotiated properly.
271  */
272 static void
273 ssh_set_socket_recvbuf(int sock)
274 {
275 	void *buf = (void *)&options.tcp_rcv_buf;
276 	int socksize, sz = sizeof(options.tcp_rcv_buf);
277 	socklen_t len = sizeof(int);
278 
279 	debug("setsockopt attempting to set SO_RCVBUF to %d",
280 	    options.tcp_rcv_buf);
281 	if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) {
282 		getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
283 		debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno),
284 		    socksize);
285 	} else
286 		error("Couldn't set socket receive buffer to %d: %.100s",
287 		    options.tcp_rcv_buf, strerror(errno));
288 }
289 
290 /*
291  * Creates a (possibly privileged) socket for use as the ssh connection.
292  */
293 static int
294 ssh_create_socket(int privileged, struct addrinfo *ai)
295 {
296 	int sock, r, gaierr;
297 	struct addrinfo hints, *res;
298 
299 	sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
300 	if (sock < 0) {
301 		error("socket: %s", strerror(errno));
302 		return -1;
303 	}
304 	fcntl(sock, F_SETFD, FD_CLOEXEC);
305 
306 	if (options.tcp_rcv_buf > 0)
307 		ssh_set_socket_recvbuf(sock);
308 
309 	/* Bind the socket to an alternative local IP address */
310 	if (options.bind_address == NULL && !privileged)
311 		return sock;
312 
313 	memset(&hints, 0, sizeof(hints));
314 	hints.ai_family = ai->ai_family;
315 	hints.ai_socktype = ai->ai_socktype;
316 	hints.ai_protocol = ai->ai_protocol;
317 	hints.ai_flags = AI_PASSIVE;
318 	gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
319 	if (gaierr) {
320 		error("getaddrinfo: %s: %s", options.bind_address,
321 		    ssh_gai_strerror(gaierr));
322 		close(sock);
323 		return -1;
324 	}
325 	/*
326 	 * If we are running as root and want to connect to a privileged
327 	 * port, bind our own socket to a privileged port.
328 	 */
329 	if (privileged) {
330 		PRIV_START;
331 		r = bindresvport_sa(sock, res->ai_addr);
332 		PRIV_END;
333 		if (r < 0) {
334 			error("bindresvport_sa: af=%d %s", ai->ai_family,
335 			    strerror(errno));
336 			goto fail;
337 		}
338 	} else {
339 		if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
340 			error("bind: %s: %s", options.bind_address,
341 			    strerror(errno));
342  fail:
343 			close(sock);
344 			freeaddrinfo(res);
345 			return -1;
346 		}
347 	}
348 	freeaddrinfo(res);
349 	return sock;
350 }
351 
352 static int
353 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
354     socklen_t addrlen, int *timeoutp)
355 {
356 	fd_set *fdset;
357 	struct timeval tv, t_start;
358 	socklen_t optlen;
359 	int optval, rc, result = -1;
360 
361 	gettimeofday(&t_start, NULL);
362 
363 	if (*timeoutp <= 0) {
364 		result = connect(sockfd, serv_addr, addrlen);
365 		goto done;
366 	}
367 
368 	set_nonblock(sockfd);
369 	rc = connect(sockfd, serv_addr, addrlen);
370 	if (rc == 0) {
371 		unset_nonblock(sockfd);
372 		result = 0;
373 		goto done;
374 	}
375 	if (errno != EINPROGRESS) {
376 		result = -1;
377 		goto done;
378 	}
379 
380 	fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
381 	    sizeof(fd_mask));
382 	FD_SET(sockfd, fdset);
383 	ms_to_timeval(&tv, *timeoutp);
384 
385 	for (;;) {
386 		rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
387 		if (rc != -1 || errno != EINTR)
388 			break;
389 	}
390 
391 	switch (rc) {
392 	case 0:
393 		/* Timed out */
394 		errno = ETIMEDOUT;
395 		break;
396 	case -1:
397 		/* Select error */
398 		debug("select: %s", strerror(errno));
399 		break;
400 	case 1:
401 		/* Completed or failed */
402 		optval = 0;
403 		optlen = sizeof(optval);
404 		if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
405 		    &optlen) == -1) {
406 			debug("getsockopt: %s", strerror(errno));
407 			break;
408 		}
409 		if (optval != 0) {
410 			errno = optval;
411 			break;
412 		}
413 		result = 0;
414 		unset_nonblock(sockfd);
415 		break;
416 	default:
417 		/* Should not occur */
418 		fatal("Bogus return (%d) from select()", rc);
419 	}
420 
421 	free(fdset);
422 
423  done:
424  	if (result == 0 && *timeoutp > 0) {
425 		ms_subtract_diff(&t_start, timeoutp);
426 		if (*timeoutp <= 0) {
427 			errno = ETIMEDOUT;
428 			result = -1;
429 		}
430 	}
431 
432 	return (result);
433 }
434 
435 /*
436  * Opens a TCP/IP connection to the remote server on the given host.
437  * The address of the remote host will be returned in hostaddr.
438  * If port is 0, the default port will be used.  If needpriv is true,
439  * a privileged port will be allocated to make the connection.
440  * This requires super-user privileges if needpriv is true.
441  * Connection_attempts specifies the maximum number of tries (one per
442  * second).  If proxy_command is non-NULL, it specifies the command (with %h
443  * and %p substituted for host and port, respectively) to use to contact
444  * the daemon.
445  */
446 static int
447 ssh_connect_direct(const char *host, struct addrinfo *aitop,
448     struct sockaddr_storage *hostaddr, u_short port, int family,
449     int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
450 {
451 	int on = 1;
452 	int sock = -1, attempt;
453 	char ntop[NI_MAXHOST], strport[NI_MAXSERV];
454 	struct addrinfo *ai;
455 
456 	debug2("ssh_connect: needpriv %d", needpriv);
457 
458 	for (attempt = 0; attempt < connection_attempts; attempt++) {
459 		if (attempt > 0) {
460 			/* Sleep a moment before retrying. */
461 			sleep(1);
462 			debug("Trying again...");
463 		}
464 		/*
465 		 * Loop through addresses for this host, and try each one in
466 		 * sequence until the connection succeeds.
467 		 */
468 		for (ai = aitop; ai; ai = ai->ai_next) {
469 			if (ai->ai_family != AF_INET &&
470 			    ai->ai_family != AF_INET6)
471 				continue;
472 			if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
473 			    ntop, sizeof(ntop), strport, sizeof(strport),
474 			    NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
475 				error("ssh_connect: getnameinfo failed");
476 				continue;
477 			}
478 			debug("Connecting to %.200s [%.100s] port %s.",
479 				host, ntop, strport);
480 
481 			/* Create a socket for connecting. */
482 			sock = ssh_create_socket(needpriv, ai);
483 			if (sock < 0)
484 				/* Any error is already output */
485 				continue;
486 
487 			if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
488 			    timeout_ms) >= 0) {
489 				/* Successful connection. */
490 				memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
491 				break;
492 			} else {
493 				debug("connect to address %s port %s: %s",
494 				    ntop, strport, strerror(errno));
495 				close(sock);
496 				sock = -1;
497 			}
498 		}
499 		if (sock != -1)
500 			break;	/* Successful connection. */
501 	}
502 
503 	/* Return failure if we didn't get a successful connection. */
504 	if (sock == -1) {
505 		error("ssh: connect to host %s port %s: %s",
506 		    host, strport, strerror(errno));
507 		return (-1);
508 	}
509 
510 	debug("Connection established.");
511 
512 	/* Set SO_KEEPALIVE if requested. */
513 	if (want_keepalive &&
514 	    setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
515 	    sizeof(on)) < 0)
516 		error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
517 
518 	/* Set the connection. */
519 	packet_set_connection(sock, sock);
520 
521 	return 0;
522 }
523 
524 int
525 ssh_connect(const char *host, struct addrinfo *addrs,
526     struct sockaddr_storage *hostaddr, u_short port, int family,
527     int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
528 {
529 	if (options.proxy_command == NULL) {
530 		return ssh_connect_direct(host, addrs, hostaddr, port, family,
531 		    connection_attempts, timeout_ms, want_keepalive, needpriv);
532 	} else if (strcmp(options.proxy_command, "-") == 0) {
533 		packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
534 		return 0; /* Always succeeds */
535 	} else if (options.proxy_use_fdpass) {
536 		return ssh_proxy_fdpass_connect(host, port,
537 		    options.proxy_command);
538 	}
539 	return ssh_proxy_connect(host, port, options.proxy_command);
540 }
541 
542 static void
543 send_client_banner(int connection_out, int minor1)
544 {
545 	/* Send our own protocol version identification. */
546 	xasprintf(&client_version_string, "SSH-%d.%d-%.100s%s%s%s%s",
547 	    compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
548 	    compat20 ? PROTOCOL_MINOR_2 : minor1,
549 	    SSH_VERSION, options.hpn_disabled ? "" : SSH_VERSION_HPN,
550 	    *options.version_addendum == '\0' ? "" : " ",
551 	    options.version_addendum, compat20 ? "\r\n" : "\n");
552 	if (roaming_atomicio(vwrite, connection_out, client_version_string,
553 	    strlen(client_version_string)) != strlen(client_version_string))
554 		fatal("write: %.100s", strerror(errno));
555 	chop(client_version_string);
556 	debug("Local version string %.100s", client_version_string);
557 }
558 
559 /*
560  * Waits for the server identification string, and sends our own
561  * identification string.
562  */
563 void
564 ssh_exchange_identification(int timeout_ms)
565 {
566 	char buf[256], remote_version[256];	/* must be same size! */
567 	int remote_major, remote_minor, mismatch;
568 	int connection_in = packet_get_connection_in();
569 	int connection_out = packet_get_connection_out();
570 	int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
571 	u_int i, n;
572 	size_t len;
573 	int fdsetsz, remaining, rc;
574 	struct timeval t_start, t_remaining;
575 	fd_set *fdset;
576 
577 	fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
578 	fdset = xcalloc(1, fdsetsz);
579 
580 	/*
581 	 * If we are SSH2-only then we can send the banner immediately and
582 	 * save a round-trip.
583 	 */
584 	if (options.protocol == SSH_PROTO_2) {
585 		enable_compat20();
586 		send_client_banner(connection_out, 0);
587 		client_banner_sent = 1;
588 	}
589 
590 	/* Read other side's version identification. */
591 	remaining = timeout_ms;
592 	for (n = 0;;) {
593 		for (i = 0; i < sizeof(buf) - 1; i++) {
594 			if (timeout_ms > 0) {
595 				gettimeofday(&t_start, NULL);
596 				ms_to_timeval(&t_remaining, remaining);
597 				FD_SET(connection_in, fdset);
598 				rc = select(connection_in + 1, fdset, NULL,
599 				    fdset, &t_remaining);
600 				ms_subtract_diff(&t_start, &remaining);
601 				if (rc == 0 || remaining <= 0)
602 					fatal("Connection timed out during "
603 					    "banner exchange");
604 				if (rc == -1) {
605 					if (errno == EINTR)
606 						continue;
607 					fatal("ssh_exchange_identification: "
608 					    "select: %s", strerror(errno));
609 				}
610 			}
611 
612 			len = roaming_atomicio(read, connection_in, &buf[i], 1);
613 
614 			if (len != 1 && errno == EPIPE)
615 				fatal("ssh_exchange_identification: "
616 				    "Connection closed by remote host");
617 			else if (len != 1)
618 				fatal("ssh_exchange_identification: "
619 				    "read: %.100s", strerror(errno));
620 			if (buf[i] == '\r') {
621 				buf[i] = '\n';
622 				buf[i + 1] = 0;
623 				continue;		/**XXX wait for \n */
624 			}
625 			if (buf[i] == '\n') {
626 				buf[i + 1] = 0;
627 				break;
628 			}
629 			if (++n > 65536)
630 				fatal("ssh_exchange_identification: "
631 				    "No banner received");
632 		}
633 		buf[sizeof(buf) - 1] = 0;
634 		if (strncmp(buf, "SSH-", 4) == 0)
635 			break;
636 		debug("ssh_exchange_identification: %s", buf);
637 	}
638 	server_version_string = xstrdup(buf);
639 	free(fdset);
640 
641 	/*
642 	 * Check that the versions match.  In future this might accept
643 	 * several versions and set appropriate flags to handle them.
644 	 */
645 	if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
646 	    &remote_major, &remote_minor, remote_version) != 3)
647 		fatal("Bad remote protocol version identification: '%.100s'", buf);
648 	debug("Remote protocol version %d.%d, remote software version %.100s",
649 	    remote_major, remote_minor, remote_version);
650 
651 	compat_datafellows(remote_version);
652 	mismatch = 0;
653 
654 	switch (remote_major) {
655 	case 1:
656 		if (remote_minor == 99 &&
657 		    (options.protocol & SSH_PROTO_2) &&
658 		    !(options.protocol & SSH_PROTO_1_PREFERRED)) {
659 			enable_compat20();
660 			break;
661 		}
662 		if (!(options.protocol & SSH_PROTO_1)) {
663 			mismatch = 1;
664 			break;
665 		}
666 		if (remote_minor < 3) {
667 			fatal("Remote machine has too old SSH software version.");
668 		} else if (remote_minor == 3 || remote_minor == 4) {
669 			/* We speak 1.3, too. */
670 			enable_compat13();
671 			minor1 = 3;
672 			if (options.forward_agent) {
673 				logit("Agent forwarding disabled for protocol 1.3");
674 				options.forward_agent = 0;
675 			}
676 		}
677 		break;
678 	case 2:
679 		if (options.protocol & SSH_PROTO_2) {
680 			enable_compat20();
681 			break;
682 		}
683 		/* FALLTHROUGH */
684 	default:
685 		mismatch = 1;
686 		break;
687 	}
688 	if (mismatch)
689 		fatal("Protocol major versions differ: %d vs. %d",
690 		    (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
691 		    remote_major);
692 	if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
693 		fatal("Server version \"%.100s\" uses unsafe key agreement; "
694 		    "refusing connection", remote_version);
695 	if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
696 		logit("Server version \"%.100s\" uses unsafe RSA signature "
697 		    "scheme; disabling use of RSA keys", remote_version);
698 	if (!client_banner_sent)
699 		send_client_banner(connection_out, minor1);
700 	chop(server_version_string);
701 }
702 
703 /* defaults to 'no' */
704 static int
705 confirm(const char *prompt)
706 {
707 	const char *msg, *again = "Please type 'yes' or 'no': ";
708 	char *p;
709 	int ret = -1;
710 
711 	if (options.batch_mode)
712 		return 0;
713 	for (msg = prompt;;msg = again) {
714 		p = read_passphrase(msg, RP_ECHO);
715 		if (p == NULL ||
716 		    (p[0] == '\0') || (p[0] == '\n') ||
717 		    strncasecmp(p, "no", 2) == 0)
718 			ret = 0;
719 		if (p && strncasecmp(p, "yes", 3) == 0)
720 			ret = 1;
721 		free(p);
722 		if (ret != -1)
723 			return ret;
724 	}
725 }
726 
727 static int
728 check_host_cert(const char *host, const Key *host_key)
729 {
730 	const char *reason;
731 
732 	if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
733 		error("%s", reason);
734 		return 0;
735 	}
736 	if (buffer_len(&host_key->cert->critical) != 0) {
737 		error("Certificate for %s contains unsupported "
738 		    "critical options(s)", host);
739 		return 0;
740 	}
741 	return 1;
742 }
743 
744 static int
745 sockaddr_is_local(struct sockaddr *hostaddr)
746 {
747 	switch (hostaddr->sa_family) {
748 	case AF_INET:
749 		return (ntohl(((struct sockaddr_in *)hostaddr)->
750 		    sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
751 	case AF_INET6:
752 		return IN6_IS_ADDR_LOOPBACK(
753 		    &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
754 	default:
755 		return 0;
756 	}
757 }
758 
759 /*
760  * Prepare the hostname and ip address strings that are used to lookup
761  * host keys in known_hosts files. These may have a port number appended.
762  */
763 void
764 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
765     u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
766 {
767 	char ntop[NI_MAXHOST];
768 	socklen_t addrlen;
769 
770 	switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
771 	case -1:
772 		addrlen = 0;
773 		break;
774 	case AF_INET:
775 		addrlen = sizeof(struct sockaddr_in);
776 		break;
777 	case AF_INET6:
778 		addrlen = sizeof(struct sockaddr_in6);
779 		break;
780 	default:
781 		addrlen = sizeof(struct sockaddr);
782 		break;
783 	}
784 
785 	/*
786 	 * We don't have the remote ip-address for connections
787 	 * using a proxy command
788 	 */
789 	if (hostfile_ipaddr != NULL) {
790 		if (options.proxy_command == NULL) {
791 			if (getnameinfo(hostaddr, addrlen,
792 			    ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
793 			fatal("check_host_key: getnameinfo failed");
794 			*hostfile_ipaddr = put_host_port(ntop, port);
795 		} else {
796 			*hostfile_ipaddr = xstrdup("<no hostip for proxy "
797 			    "command>");
798 		}
799 	}
800 
801 	/*
802 	 * Allow the user to record the key under a different name or
803 	 * differentiate a non-standard port.  This is useful for ssh
804 	 * tunneling over forwarded connections or if you run multiple
805 	 * sshd's on different ports on the same machine.
806 	 */
807 	if (hostfile_hostname != NULL) {
808 		if (options.host_key_alias != NULL) {
809 			*hostfile_hostname = xstrdup(options.host_key_alias);
810 			debug("using hostkeyalias: %s", *hostfile_hostname);
811 		} else {
812 			*hostfile_hostname = put_host_port(hostname, port);
813 		}
814 	}
815 }
816 
817 /*
818  * check whether the supplied host key is valid, return -1 if the key
819  * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
820  */
821 #define RDRW	0
822 #define RDONLY	1
823 #define ROQUIET	2
824 static int
825 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
826     Key *host_key, int readonly,
827     char **user_hostfiles, u_int num_user_hostfiles,
828     char **system_hostfiles, u_int num_system_hostfiles)
829 {
830 	HostStatus host_status;
831 	HostStatus ip_status;
832 	Key *raw_key = NULL;
833 	char *ip = NULL, *host = NULL;
834 	char hostline[1000], *hostp, *fp, *ra;
835 	char msg[1024];
836 	const char *type;
837 	const struct hostkey_entry *host_found, *ip_found;
838 	int len, cancelled_forwarding = 0;
839 	int local = sockaddr_is_local(hostaddr);
840 	int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
841 	struct hostkeys *host_hostkeys, *ip_hostkeys;
842 	u_int i;
843 
844 	/*
845 	 * Force accepting of the host key for loopback/localhost. The
846 	 * problem is that if the home directory is NFS-mounted to multiple
847 	 * machines, localhost will refer to a different machine in each of
848 	 * them, and the user will get bogus HOST_CHANGED warnings.  This
849 	 * essentially disables host authentication for localhost; however,
850 	 * this is probably not a real problem.
851 	 */
852 	if (options.no_host_authentication_for_localhost == 1 && local &&
853 	    options.host_key_alias == NULL) {
854 		debug("Forcing accepting of host key for "
855 		    "loopback/localhost.");
856 		return 0;
857 	}
858 
859 	/*
860 	 * Prepare the hostname and address strings used for hostkey lookup.
861 	 * In some cases, these will have a port number appended.
862 	 */
863 	get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
864 
865 	/*
866 	 * Turn off check_host_ip if the connection is to localhost, via proxy
867 	 * command or if we don't have a hostname to compare with
868 	 */
869 	if (options.check_host_ip && (local ||
870 	    strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
871 		options.check_host_ip = 0;
872 
873 	host_hostkeys = init_hostkeys();
874 	for (i = 0; i < num_user_hostfiles; i++)
875 		load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
876 	for (i = 0; i < num_system_hostfiles; i++)
877 		load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
878 
879 	ip_hostkeys = NULL;
880 	if (!want_cert && options.check_host_ip) {
881 		ip_hostkeys = init_hostkeys();
882 		for (i = 0; i < num_user_hostfiles; i++)
883 			load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
884 		for (i = 0; i < num_system_hostfiles; i++)
885 			load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
886 	}
887 
888  retry:
889 	/* Reload these as they may have changed on cert->key downgrade */
890 	want_cert = key_is_cert(host_key);
891 	type = key_type(host_key);
892 
893 	/*
894 	 * Check if the host key is present in the user's list of known
895 	 * hosts or in the systemwide list.
896 	 */
897 	host_status = check_key_in_hostkeys(host_hostkeys, host_key,
898 	    &host_found);
899 
900 	/*
901 	 * Also perform check for the ip address, skip the check if we are
902 	 * localhost, looking for a certificate, or the hostname was an ip
903 	 * address to begin with.
904 	 */
905 	if (!want_cert && ip_hostkeys != NULL) {
906 		ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
907 		    &ip_found);
908 		if (host_status == HOST_CHANGED &&
909 		    (ip_status != HOST_CHANGED ||
910 		    (ip_found != NULL &&
911 		    !key_equal(ip_found->key, host_found->key))))
912 			host_ip_differ = 1;
913 	} else
914 		ip_status = host_status;
915 
916 	switch (host_status) {
917 	case HOST_OK:
918 		/* The host is known and the key matches. */
919 		debug("Host '%.200s' is known and matches the %s host %s.",
920 		    host, type, want_cert ? "certificate" : "key");
921 		debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
922 		    host_found->file, host_found->line);
923 		if (want_cert && !check_host_cert(hostname, host_key))
924 			goto fail;
925 		if (options.check_host_ip && ip_status == HOST_NEW) {
926 			if (readonly || want_cert)
927 				logit("%s host key for IP address "
928 				    "'%.128s' not in list of known hosts.",
929 				    type, ip);
930 			else if (!add_host_to_hostfile(user_hostfiles[0], ip,
931 			    host_key, options.hash_known_hosts))
932 				logit("Failed to add the %s host key for IP "
933 				    "address '%.128s' to the list of known "
934 				    "hosts (%.30s).", type, ip,
935 				    user_hostfiles[0]);
936 			else
937 				logit("Warning: Permanently added the %s host "
938 				    "key for IP address '%.128s' to the list "
939 				    "of known hosts.", type, ip);
940 		} else if (options.visual_host_key) {
941 			fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
942 			ra = key_fingerprint(host_key, SSH_FP_MD5,
943 			    SSH_FP_RANDOMART);
944 			logit("Host key fingerprint is %s\n%s\n", fp, ra);
945 			free(ra);
946 			free(fp);
947 		}
948 		break;
949 	case HOST_NEW:
950 		if (options.host_key_alias == NULL && port != 0 &&
951 		    port != SSH_DEFAULT_PORT) {
952 			debug("checking without port identifier");
953 			if (check_host_key(hostname, hostaddr, 0, host_key,
954 			    ROQUIET, user_hostfiles, num_user_hostfiles,
955 			    system_hostfiles, num_system_hostfiles) == 0) {
956 				debug("found matching key w/out port");
957 				break;
958 			}
959 		}
960 		if (readonly || want_cert)
961 			goto fail;
962 		/* The host is new. */
963 		if (options.strict_host_key_checking == 1) {
964 			/*
965 			 * User has requested strict host key checking.  We
966 			 * will not add the host key automatically.  The only
967 			 * alternative left is to abort.
968 			 */
969 			error("No %s host key is known for %.200s and you "
970 			    "have requested strict checking.", type, host);
971 			goto fail;
972 		} else if (options.strict_host_key_checking == 2) {
973 			char msg1[1024], msg2[1024];
974 
975 			if (show_other_keys(host_hostkeys, host_key))
976 				snprintf(msg1, sizeof(msg1),
977 				    "\nbut keys of different type are already"
978 				    " known for this host.");
979 			else
980 				snprintf(msg1, sizeof(msg1), ".");
981 			/* The default */
982 			fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
983 			ra = key_fingerprint(host_key, SSH_FP_MD5,
984 			    SSH_FP_RANDOMART);
985 			msg2[0] = '\0';
986 			if (options.verify_host_key_dns) {
987 				if (matching_host_key_dns)
988 					snprintf(msg2, sizeof(msg2),
989 					    "Matching host key fingerprint"
990 					    " found in DNS.\n");
991 				else
992 					snprintf(msg2, sizeof(msg2),
993 					    "No matching host key fingerprint"
994 					    " found in DNS.\n");
995 			}
996 			snprintf(msg, sizeof(msg),
997 			    "The authenticity of host '%.200s (%s)' can't be "
998 			    "established%s\n"
999 			    "%s key fingerprint is %s.%s%s\n%s"
1000 			    "Are you sure you want to continue connecting "
1001 			    "(yes/no)? ",
1002 			    host, ip, msg1, type, fp,
1003 			    options.visual_host_key ? "\n" : "",
1004 			    options.visual_host_key ? ra : "",
1005 			    msg2);
1006 			free(ra);
1007 			free(fp);
1008 			if (!confirm(msg))
1009 				goto fail;
1010 		}
1011 		/*
1012 		 * If not in strict mode, add the key automatically to the
1013 		 * local known_hosts file.
1014 		 */
1015 		if (options.check_host_ip && ip_status == HOST_NEW) {
1016 			snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1017 			hostp = hostline;
1018 			if (options.hash_known_hosts) {
1019 				/* Add hash of host and IP separately */
1020 				r = add_host_to_hostfile(user_hostfiles[0],
1021 				    host, host_key, options.hash_known_hosts) &&
1022 				    add_host_to_hostfile(user_hostfiles[0], ip,
1023 				    host_key, options.hash_known_hosts);
1024 			} else {
1025 				/* Add unhashed "host,ip" */
1026 				r = add_host_to_hostfile(user_hostfiles[0],
1027 				    hostline, host_key,
1028 				    options.hash_known_hosts);
1029 			}
1030 		} else {
1031 			r = add_host_to_hostfile(user_hostfiles[0], host,
1032 			    host_key, options.hash_known_hosts);
1033 			hostp = host;
1034 		}
1035 
1036 		if (!r)
1037 			logit("Failed to add the host to the list of known "
1038 			    "hosts (%.500s).", user_hostfiles[0]);
1039 		else
1040 			logit("Warning: Permanently added '%.200s' (%s) to the "
1041 			    "list of known hosts.", hostp, type);
1042 		break;
1043 	case HOST_REVOKED:
1044 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1045 		error("@       WARNING: REVOKED HOST KEY DETECTED!               @");
1046 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1047 		error("The %s host key for %s is marked as revoked.", type, host);
1048 		error("This could mean that a stolen key is being used to");
1049 		error("impersonate this host.");
1050 
1051 		/*
1052 		 * If strict host key checking is in use, the user will have
1053 		 * to edit the key manually and we can only abort.
1054 		 */
1055 		if (options.strict_host_key_checking) {
1056 			error("%s host key for %.200s was revoked and you have "
1057 			    "requested strict checking.", type, host);
1058 			goto fail;
1059 		}
1060 		goto continue_unsafe;
1061 
1062 	case HOST_CHANGED:
1063 		if (want_cert) {
1064 			/*
1065 			 * This is only a debug() since it is valid to have
1066 			 * CAs with wildcard DNS matches that don't match
1067 			 * all hosts that one might visit.
1068 			 */
1069 			debug("Host certificate authority does not "
1070 			    "match %s in %s:%lu", CA_MARKER,
1071 			    host_found->file, host_found->line);
1072 			goto fail;
1073 		}
1074 		if (readonly == ROQUIET)
1075 			goto fail;
1076 		if (options.check_host_ip && host_ip_differ) {
1077 			char *key_msg;
1078 			if (ip_status == HOST_NEW)
1079 				key_msg = "is unknown";
1080 			else if (ip_status == HOST_OK)
1081 				key_msg = "is unchanged";
1082 			else
1083 				key_msg = "has a different value";
1084 			error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1085 			error("@       WARNING: POSSIBLE DNS SPOOFING DETECTED!          @");
1086 			error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1087 			error("The %s host key for %s has changed,", type, host);
1088 			error("and the key for the corresponding IP address %s", ip);
1089 			error("%s. This could either mean that", key_msg);
1090 			error("DNS SPOOFING is happening or the IP address for the host");
1091 			error("and its host key have changed at the same time.");
1092 			if (ip_status != HOST_NEW)
1093 				error("Offending key for IP in %s:%lu",
1094 				    ip_found->file, ip_found->line);
1095 		}
1096 		/* The host key has changed. */
1097 		warn_changed_key(host_key);
1098 		error("Add correct host key in %.100s to get rid of this message.",
1099 		    user_hostfiles[0]);
1100 		error("Offending %s key in %s:%lu", key_type(host_found->key),
1101 		    host_found->file, host_found->line);
1102 
1103 		/*
1104 		 * If strict host key checking is in use, the user will have
1105 		 * to edit the key manually and we can only abort.
1106 		 */
1107 		if (options.strict_host_key_checking) {
1108 			error("%s host key for %.200s has changed and you have "
1109 			    "requested strict checking.", type, host);
1110 			goto fail;
1111 		}
1112 
1113  continue_unsafe:
1114 		/*
1115 		 * If strict host key checking has not been requested, allow
1116 		 * the connection but without MITM-able authentication or
1117 		 * forwarding.
1118 		 */
1119 		if (options.password_authentication) {
1120 			error("Password authentication is disabled to avoid "
1121 			    "man-in-the-middle attacks.");
1122 			options.password_authentication = 0;
1123 			cancelled_forwarding = 1;
1124 		}
1125 		if (options.kbd_interactive_authentication) {
1126 			error("Keyboard-interactive authentication is disabled"
1127 			    " to avoid man-in-the-middle attacks.");
1128 			options.kbd_interactive_authentication = 0;
1129 			options.challenge_response_authentication = 0;
1130 			cancelled_forwarding = 1;
1131 		}
1132 		if (options.challenge_response_authentication) {
1133 			error("Challenge/response authentication is disabled"
1134 			    " to avoid man-in-the-middle attacks.");
1135 			options.challenge_response_authentication = 0;
1136 			cancelled_forwarding = 1;
1137 		}
1138 		if (options.forward_agent) {
1139 			error("Agent forwarding is disabled to avoid "
1140 			    "man-in-the-middle attacks.");
1141 			options.forward_agent = 0;
1142 			cancelled_forwarding = 1;
1143 		}
1144 		if (options.forward_x11) {
1145 			error("X11 forwarding is disabled to avoid "
1146 			    "man-in-the-middle attacks.");
1147 			options.forward_x11 = 0;
1148 			cancelled_forwarding = 1;
1149 		}
1150 		if (options.num_local_forwards > 0 ||
1151 		    options.num_remote_forwards > 0) {
1152 			error("Port forwarding is disabled to avoid "
1153 			    "man-in-the-middle attacks.");
1154 			options.num_local_forwards =
1155 			    options.num_remote_forwards = 0;
1156 			cancelled_forwarding = 1;
1157 		}
1158 		if (options.tun_open != SSH_TUNMODE_NO) {
1159 			error("Tunnel forwarding is disabled to avoid "
1160 			    "man-in-the-middle attacks.");
1161 			options.tun_open = SSH_TUNMODE_NO;
1162 			cancelled_forwarding = 1;
1163 		}
1164 		if (options.exit_on_forward_failure && cancelled_forwarding)
1165 			fatal("Error: forwarding disabled due to host key "
1166 			    "check failure");
1167 
1168 		/*
1169 		 * XXX Should permit the user to change to use the new id.
1170 		 * This could be done by converting the host key to an
1171 		 * identifying sentence, tell that the host identifies itself
1172 		 * by that sentence, and ask the user if he/she wishes to
1173 		 * accept the authentication.
1174 		 */
1175 		break;
1176 	case HOST_FOUND:
1177 		fatal("internal error");
1178 		break;
1179 	}
1180 
1181 	if (options.check_host_ip && host_status != HOST_CHANGED &&
1182 	    ip_status == HOST_CHANGED) {
1183 		snprintf(msg, sizeof(msg),
1184 		    "Warning: the %s host key for '%.200s' "
1185 		    "differs from the key for the IP address '%.128s'"
1186 		    "\nOffending key for IP in %s:%lu",
1187 		    type, host, ip, ip_found->file, ip_found->line);
1188 		if (host_status == HOST_OK) {
1189 			len = strlen(msg);
1190 			snprintf(msg + len, sizeof(msg) - len,
1191 			    "\nMatching host key in %s:%lu",
1192 			    host_found->file, host_found->line);
1193 		}
1194 		if (options.strict_host_key_checking == 1) {
1195 			logit("%s", msg);
1196 			error("Exiting, you have requested strict checking.");
1197 			goto fail;
1198 		} else if (options.strict_host_key_checking == 2) {
1199 			strlcat(msg, "\nAre you sure you want "
1200 			    "to continue connecting (yes/no)? ", sizeof(msg));
1201 			if (!confirm(msg))
1202 				goto fail;
1203 		} else {
1204 			logit("%s", msg);
1205 		}
1206 	}
1207 
1208 	free(ip);
1209 	free(host);
1210 	if (host_hostkeys != NULL)
1211 		free_hostkeys(host_hostkeys);
1212 	if (ip_hostkeys != NULL)
1213 		free_hostkeys(ip_hostkeys);
1214 	return 0;
1215 
1216 fail:
1217 	if (want_cert && host_status != HOST_REVOKED) {
1218 		/*
1219 		 * No matching certificate. Downgrade cert to raw key and
1220 		 * search normally.
1221 		 */
1222 		debug("No matching CA found. Retry with plain key");
1223 		raw_key = key_from_private(host_key);
1224 		if (key_drop_cert(raw_key) != 0)
1225 			fatal("Couldn't drop certificate");
1226 		host_key = raw_key;
1227 		goto retry;
1228 	}
1229 	if (raw_key != NULL)
1230 		key_free(raw_key);
1231 	free(ip);
1232 	free(host);
1233 	if (host_hostkeys != NULL)
1234 		free_hostkeys(host_hostkeys);
1235 	if (ip_hostkeys != NULL)
1236 		free_hostkeys(ip_hostkeys);
1237 	return -1;
1238 }
1239 
1240 /* returns 0 if key verifies or -1 if key does NOT verify */
1241 int
1242 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1243 {
1244 	int flags = 0;
1245 	char *fp;
1246 
1247 	fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1248 	debug("Server host key: %s %s", key_type(host_key), fp);
1249 	free(fp);
1250 
1251 	/* XXX certs are not yet supported for DNS */
1252 	if (!key_is_cert(host_key) && options.verify_host_key_dns &&
1253 	    verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1254 		if (flags & DNS_VERIFY_FOUND) {
1255 
1256 			if (options.verify_host_key_dns == 1 &&
1257 			    flags & DNS_VERIFY_MATCH &&
1258 			    flags & DNS_VERIFY_SECURE)
1259 				return 0;
1260 
1261 			if (flags & DNS_VERIFY_MATCH) {
1262 				matching_host_key_dns = 1;
1263 			} else {
1264 				warn_changed_key(host_key);
1265 				error("Update the SSHFP RR in DNS with the new "
1266 				    "host key to get rid of this message.");
1267 			}
1268 		}
1269 	}
1270 
1271 	return check_host_key(host, hostaddr, options.port, host_key, RDRW,
1272 	    options.user_hostfiles, options.num_user_hostfiles,
1273 	    options.system_hostfiles, options.num_system_hostfiles);
1274 }
1275 
1276 /*
1277  * Starts a dialog with the server, and authenticates the current user on the
1278  * server.  This does not need any extra privileges.  The basic connection
1279  * to the server must already have been established before this is called.
1280  * If login fails, this function prints an error and never returns.
1281  * This function does not require super-user privileges.
1282  */
1283 void
1284 ssh_login(Sensitive *sensitive, const char *orighost,
1285     struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1286 {
1287 	char *host;
1288 	char *server_user, *local_user;
1289 
1290 	local_user = xstrdup(pw->pw_name);
1291 	server_user = options.user ? options.user : local_user;
1292 
1293 	/* Convert the user-supplied hostname into all lowercase. */
1294 	host = xstrdup(orighost);
1295 	lowercase(host);
1296 
1297 	/* Exchange protocol version identification strings with the server. */
1298 	ssh_exchange_identification(timeout_ms);
1299 
1300 	/* Put the connection into non-blocking mode. */
1301 	packet_set_nonblocking();
1302 
1303 	/* key exchange */
1304 	/* authenticate user */
1305 	if (compat20) {
1306 		ssh_kex2(host, hostaddr, port);
1307 		ssh_userauth2(local_user, server_user, host, sensitive);
1308 	} else {
1309 		ssh_kex(host, hostaddr);
1310 		ssh_userauth1(local_user, server_user, host, sensitive);
1311 	}
1312 	free(local_user);
1313 }
1314 
1315 void
1316 ssh_put_password(char *password)
1317 {
1318 	int size;
1319 	char *padded;
1320 
1321 	if (datafellows & SSH_BUG_PASSWORDPAD) {
1322 		packet_put_cstring(password);
1323 		return;
1324 	}
1325 	size = roundup(strlen(password) + 1, 32);
1326 	padded = xcalloc(1, size);
1327 	strlcpy(padded, password, size);
1328 	packet_put_string(padded, size);
1329 	memset(padded, 0, size);
1330 	free(padded);
1331 }
1332 
1333 /* print all known host keys for a given host, but skip keys of given type */
1334 static int
1335 show_other_keys(struct hostkeys *hostkeys, Key *key)
1336 {
1337 	int type[] = {
1338 		KEY_RSA1,
1339 		KEY_RSA,
1340 		KEY_DSA,
1341 		KEY_ECDSA,
1342 		KEY_ED25519,
1343 		-1
1344 	};
1345 	int i, ret = 0;
1346 	char *fp, *ra;
1347 	const struct hostkey_entry *found;
1348 
1349 	for (i = 0; type[i] != -1; i++) {
1350 		if (type[i] == key->type)
1351 			continue;
1352 		if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1353 			continue;
1354 		fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1355 		ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1356 		logit("WARNING: %s key found for host %s\n"
1357 		    "in %s:%lu\n"
1358 		    "%s key fingerprint %s.",
1359 		    key_type(found->key),
1360 		    found->host, found->file, found->line,
1361 		    key_type(found->key), fp);
1362 		if (options.visual_host_key)
1363 			logit("%s", ra);
1364 		free(ra);
1365 		free(fp);
1366 		ret = 1;
1367 	}
1368 	return ret;
1369 }
1370 
1371 static void
1372 warn_changed_key(Key *host_key)
1373 {
1374 	char *fp;
1375 
1376 	fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1377 
1378 	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1379 	error("@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @");
1380 	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1381 	error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1382 	error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1383 	error("It is also possible that a host key has just been changed.");
1384 	error("The fingerprint for the %s key sent by the remote host is\n%s.",
1385 	    key_type(host_key), fp);
1386 	error("Please contact your system administrator.");
1387 
1388 	free(fp);
1389 }
1390 
1391 /*
1392  * Execute a local command
1393  */
1394 int
1395 ssh_local_cmd(const char *args)
1396 {
1397 	char *shell;
1398 	pid_t pid;
1399 	int status;
1400 	void (*osighand)(int);
1401 
1402 	if (!options.permit_local_command ||
1403 	    args == NULL || !*args)
1404 		return (1);
1405 
1406 	if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1407 		shell = _PATH_BSHELL;
1408 
1409 	osighand = signal(SIGCHLD, SIG_DFL);
1410 	pid = fork();
1411 	if (pid == 0) {
1412 		signal(SIGPIPE, SIG_DFL);
1413 		debug3("Executing %s -c \"%s\"", shell, args);
1414 		execl(shell, shell, "-c", args, (char *)NULL);
1415 		error("Couldn't execute %s -c \"%s\": %s",
1416 		    shell, args, strerror(errno));
1417 		_exit(1);
1418 	} else if (pid == -1)
1419 		fatal("fork failed: %.100s", strerror(errno));
1420 	while (waitpid(pid, &status, 0) == -1)
1421 		if (errno != EINTR)
1422 			fatal("Couldn't wait for child: %s", strerror(errno));
1423 	signal(SIGCHLD, osighand);
1424 
1425 	if (!WIFEXITED(status))
1426 		return (1);
1427 
1428 	return (WEXITSTATUS(status));
1429 }
1430