GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: usr.bin/ssh/ssh/../sshconnect.c Lines: 0 691 0.0 %
Date: 2017-11-13 Branches: 0 422 0.0 %

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