1 /* $OpenBSD: sshconnect.c,v 1.259 2015/01/28 22:36:00 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 "includes.h"
17
18 #include <sys/param.h> /* roundup */
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
30 #include <ctype.h>
31 #include <errno.h>
32 #include <fcntl.h>
33 #include <netdb.h>
34 #ifdef HAVE_PATHS_H
35 #include <paths.h>
36 #endif
37 #include <pwd.h>
38 #include <signal.h>
39 #include <stdarg.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <unistd.h>
44
45 #include "xmalloc.h"
46 #include "key.h"
47 #include "hostfile.h"
48 #include "ssh.h"
49 #include "rsa.h"
50 #include "buffer.h"
51 #include "packet.h"
52 #include "uidswap.h"
53 #include "compat.h"
54 #include "key.h"
55 #include "sshconnect.h"
56 #include "hostfile.h"
57 #include "log.h"
58 #include "misc.h"
59 #include "readconf.h"
60 #include "atomicio.h"
61 #include "dns.h"
62 #include "roaming.h"
63 #include "monitor_fdpass.h"
64 #include "ssh2.h"
65 #include "version.h"
66 #include "authfile.h"
67 #include "ssherr.h"
68
69 char *client_version_string = NULL;
70 char *server_version_string = NULL;
71 Key *previous_host_key = NULL;
72
73 static int matching_host_key_dns = 0;
74
75 static pid_t proxy_command_pid = 0;
76
77 /* import */
78 extern Options options;
79 extern char *__progname;
80 extern uid_t original_real_uid;
81 extern uid_t original_effective_uid;
82
83 static int show_other_keys(struct hostkeys *, Key *);
84 static void warn_changed_key(Key *);
85
86 /* Expand a proxy command */
87 static char *
expand_proxy_command(const char * proxy_command,const char * user,const char * host,int port)88 expand_proxy_command(const char *proxy_command, const char *user,
89 const char *host, int port)
90 {
91 char *tmp, *ret, strport[NI_MAXSERV];
92
93 snprintf(strport, sizeof strport, "%d", port);
94 xasprintf(&tmp, "exec %s", proxy_command);
95 ret = percent_expand(tmp, "h", host, "p", strport,
96 "r", options.user, (char *)NULL);
97 free(tmp);
98 return ret;
99 }
100
101 /*
102 * Connect to the given ssh server using a proxy command that passes a
103 * a connected fd back to us.
104 */
105 static int
ssh_proxy_fdpass_connect(const char * host,u_short port,const char * proxy_command)106 ssh_proxy_fdpass_connect(const char *host, u_short port,
107 const char *proxy_command)
108 {
109 char *command_string;
110 int sp[2], sock;
111 pid_t pid;
112 char *shell;
113
114 if ((shell = getenv("SHELL")) == NULL)
115 shell = _PATH_BSHELL;
116
117 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
118 fatal("Could not create socketpair to communicate with "
119 "proxy dialer: %.100s", strerror(errno));
120
121 command_string = expand_proxy_command(proxy_command, options.user,
122 host, port);
123 debug("Executing proxy dialer command: %.500s", command_string);
124
125 /* Fork and execute the proxy command. */
126 if ((pid = fork()) == 0) {
127 char *argv[10];
128
129 /* Child. Permanently give up superuser privileges. */
130 permanently_drop_suid(original_real_uid);
131
132 close(sp[1]);
133 /* Redirect stdin and stdout. */
134 if (sp[0] != 0) {
135 if (dup2(sp[0], 0) < 0)
136 perror("dup2 stdin");
137 }
138 if (sp[0] != 1) {
139 if (dup2(sp[0], 1) < 0)
140 perror("dup2 stdout");
141 }
142 if (sp[0] >= 2)
143 close(sp[0]);
144
145 /*
146 * Stderr is left as it is so that error messages get
147 * printed on the user's terminal.
148 */
149 argv[0] = shell;
150 argv[1] = "-c";
151 argv[2] = command_string;
152 argv[3] = NULL;
153
154 /*
155 * Execute the proxy command.
156 * Note that we gave up any extra privileges above.
157 */
158 execv(argv[0], argv);
159 perror(argv[0]);
160 exit(1);
161 }
162 /* Parent. */
163 if (pid < 0)
164 fatal("fork failed: %.100s", strerror(errno));
165 close(sp[0]);
166 free(command_string);
167
168 if ((sock = mm_receive_fd(sp[1])) == -1)
169 fatal("proxy dialer did not pass back a connection");
170
171 while (waitpid(pid, NULL, 0) == -1)
172 if (errno != EINTR)
173 fatal("Couldn't wait for child: %s", strerror(errno));
174
175 /* Set the connection file descriptors. */
176 packet_set_connection(sock, sock);
177
178 return 0;
179 }
180
181 /*
182 * Connect to the given ssh server using a proxy command.
183 */
184 static int
ssh_proxy_connect(const char * host,u_short port,const char * proxy_command)185 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
186 {
187 char *command_string;
188 int pin[2], pout[2];
189 pid_t pid;
190 char *shell;
191
192 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
193 shell = _PATH_BSHELL;
194
195 /* Create pipes for communicating with the proxy. */
196 if (pipe(pin) < 0 || pipe(pout) < 0)
197 fatal("Could not create pipes to communicate with the proxy: %.100s",
198 strerror(errno));
199
200 command_string = expand_proxy_command(proxy_command, options.user,
201 host, port);
202 debug("Executing proxy command: %.500s", command_string);
203
204 /* Fork and execute the proxy command. */
205 if ((pid = fork()) == 0) {
206 char *argv[10];
207
208 /* Child. Permanently give up superuser privileges. */
209 permanently_drop_suid(original_real_uid);
210
211 /* Redirect stdin and stdout. */
212 close(pin[1]);
213 if (pin[0] != 0) {
214 if (dup2(pin[0], 0) < 0)
215 perror("dup2 stdin");
216 close(pin[0]);
217 }
218 close(pout[0]);
219 if (dup2(pout[1], 1) < 0)
220 perror("dup2 stdout");
221 /* Cannot be 1 because pin allocated two descriptors. */
222 close(pout[1]);
223
224 /* Stderr is left as it is so that error messages get
225 printed on the user's terminal. */
226 argv[0] = shell;
227 argv[1] = "-c";
228 argv[2] = command_string;
229 argv[3] = NULL;
230
231 /* Execute the proxy command. Note that we gave up any
232 extra privileges above. */
233 signal(SIGPIPE, SIG_DFL);
234 execv(argv[0], argv);
235 perror(argv[0]);
236 exit(1);
237 }
238 /* Parent. */
239 if (pid < 0)
240 fatal("fork failed: %.100s", strerror(errno));
241 else
242 proxy_command_pid = pid; /* save pid to clean up later */
243
244 /* Close child side of the descriptors. */
245 close(pin[0]);
246 close(pout[1]);
247
248 /* Free the command name. */
249 free(command_string);
250
251 /* Set the connection file descriptors. */
252 packet_set_connection(pout[0], pin[1]);
253
254 /* Indicate OK return */
255 return 0;
256 }
257
258 void
ssh_kill_proxy_command(void)259 ssh_kill_proxy_command(void)
260 {
261 /*
262 * Send SIGHUP to proxy command if used. We don't wait() in
263 * case it hangs and instead rely on init to reap the child
264 */
265 if (proxy_command_pid > 1)
266 kill(proxy_command_pid, SIGHUP);
267 }
268
269 /*
270 * Creates a (possibly privileged) socket for use as the ssh connection.
271 */
272 static int
ssh_create_socket(int privileged,struct addrinfo * ai)273 ssh_create_socket(int privileged, struct addrinfo *ai)
274 {
275 int sock, r, gaierr;
276 struct addrinfo hints, *res = NULL;
277
278 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
279 if (sock < 0) {
280 error("socket: %s", strerror(errno));
281 return -1;
282 }
283 fcntl(sock, F_SETFD, FD_CLOEXEC);
284
285 /* Bind the socket to an alternative local IP address */
286 if (options.bind_address == NULL && !privileged)
287 return sock;
288
289 if (options.bind_address) {
290 memset(&hints, 0, sizeof(hints));
291 hints.ai_family = ai->ai_family;
292 hints.ai_socktype = ai->ai_socktype;
293 hints.ai_protocol = ai->ai_protocol;
294 hints.ai_flags = AI_PASSIVE;
295 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
296 if (gaierr) {
297 error("getaddrinfo: %s: %s", options.bind_address,
298 ssh_gai_strerror(gaierr));
299 close(sock);
300 return -1;
301 }
302 }
303 /*
304 * If we are running as root and want to connect to a privileged
305 * port, bind our own socket to a privileged port.
306 */
307 if (privileged) {
308 PRIV_START;
309 r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
310 PRIV_END;
311 if (r < 0) {
312 error("bindresvport_sa: af=%d %s", ai->ai_family,
313 strerror(errno));
314 goto fail;
315 }
316 } else {
317 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
318 error("bind: %s: %s", options.bind_address,
319 strerror(errno));
320 fail:
321 close(sock);
322 freeaddrinfo(res);
323 return -1;
324 }
325 }
326 if (res != NULL)
327 freeaddrinfo(res);
328 return sock;
329 }
330
331 static int
timeout_connect(int sockfd,const struct sockaddr * serv_addr,socklen_t addrlen,int * timeoutp)332 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
333 socklen_t addrlen, int *timeoutp)
334 {
335 fd_set *fdset;
336 struct timeval tv, t_start;
337 socklen_t optlen;
338 int optval, rc, result = -1;
339
340 gettimeofday(&t_start, NULL);
341
342 if (*timeoutp <= 0) {
343 result = connect(sockfd, serv_addr, addrlen);
344 goto done;
345 }
346
347 set_nonblock(sockfd);
348 rc = connect(sockfd, serv_addr, addrlen);
349 if (rc == 0) {
350 unset_nonblock(sockfd);
351 result = 0;
352 goto done;
353 }
354 if (errno != EINPROGRESS) {
355 result = -1;
356 goto done;
357 }
358
359 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
360 sizeof(fd_mask));
361 FD_SET(sockfd, fdset);
362 ms_to_timeval(&tv, *timeoutp);
363
364 for (;;) {
365 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
366 if (rc != -1 || errno != EINTR)
367 break;
368 }
369
370 switch (rc) {
371 case 0:
372 /* Timed out */
373 errno = ETIMEDOUT;
374 break;
375 case -1:
376 /* Select error */
377 debug("select: %s", strerror(errno));
378 break;
379 case 1:
380 /* Completed or failed */
381 optval = 0;
382 optlen = sizeof(optval);
383 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
384 &optlen) == -1) {
385 debug("getsockopt: %s", strerror(errno));
386 break;
387 }
388 if (optval != 0) {
389 errno = optval;
390 break;
391 }
392 result = 0;
393 unset_nonblock(sockfd);
394 break;
395 default:
396 /* Should not occur */
397 fatal("Bogus return (%d) from select()", rc);
398 }
399
400 free(fdset);
401
402 done:
403 if (result == 0 && *timeoutp > 0) {
404 ms_subtract_diff(&t_start, timeoutp);
405 if (*timeoutp <= 0) {
406 errno = ETIMEDOUT;
407 result = -1;
408 }
409 }
410
411 return (result);
412 }
413
414 /*
415 * Opens a TCP/IP connection to the remote server on the given host.
416 * The address of the remote host will be returned in hostaddr.
417 * If port is 0, the default port will be used. If needpriv is true,
418 * a privileged port will be allocated to make the connection.
419 * This requires super-user privileges if needpriv is true.
420 * Connection_attempts specifies the maximum number of tries (one per
421 * second). If proxy_command is non-NULL, it specifies the command (with %h
422 * and %p substituted for host and port, respectively) to use to contact
423 * the daemon.
424 */
425 static int
ssh_connect_direct(const char * host,struct addrinfo * aitop,struct sockaddr_storage * hostaddr,u_short port,int family,int connection_attempts,int * timeout_ms,int want_keepalive,int needpriv)426 ssh_connect_direct(const char *host, struct addrinfo *aitop,
427 struct sockaddr_storage *hostaddr, u_short port, int family,
428 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
429 {
430 int on = 1;
431 int sock = -1, attempt;
432 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
433 struct addrinfo *ai;
434
435 debug2("ssh_connect: needpriv %d", needpriv);
436
437 for (attempt = 0; attempt < connection_attempts; attempt++) {
438 if (attempt > 0) {
439 /* Sleep a moment before retrying. */
440 sleep(1);
441 debug("Trying again...");
442 }
443 /*
444 * Loop through addresses for this host, and try each one in
445 * sequence until the connection succeeds.
446 */
447 for (ai = aitop; ai; ai = ai->ai_next) {
448 if (ai->ai_family != AF_INET &&
449 ai->ai_family != AF_INET6)
450 continue;
451 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
452 ntop, sizeof(ntop), strport, sizeof(strport),
453 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
454 error("ssh_connect: getnameinfo failed");
455 continue;
456 }
457 debug("Connecting to %.200s [%.100s] port %s.",
458 host, ntop, strport);
459
460 /* Create a socket for connecting. */
461 sock = ssh_create_socket(needpriv, ai);
462 if (sock < 0)
463 /* Any error is already output */
464 continue;
465
466 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
467 timeout_ms) >= 0) {
468 /* Successful connection. */
469 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
470 break;
471 } else {
472 debug("connect to address %s port %s: %s",
473 ntop, strport, strerror(errno));
474 close(sock);
475 sock = -1;
476 }
477 }
478 if (sock != -1)
479 break; /* Successful connection. */
480 }
481
482 /* Return failure if we didn't get a successful connection. */
483 if (sock == -1) {
484 error("ssh: connect to host %s port %s: %s",
485 host, strport, strerror(errno));
486 return (-1);
487 }
488
489 debug("Connection established.");
490
491 /* Set SO_KEEPALIVE if requested. */
492 if (want_keepalive &&
493 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
494 sizeof(on)) < 0)
495 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
496
497 /* Set the connection. */
498 packet_set_connection(sock, sock);
499
500 return 0;
501 }
502
503 int
ssh_connect(const char * host,struct addrinfo * addrs,struct sockaddr_storage * hostaddr,u_short port,int family,int connection_attempts,int * timeout_ms,int want_keepalive,int needpriv)504 ssh_connect(const char *host, struct addrinfo *addrs,
505 struct sockaddr_storage *hostaddr, u_short port, int family,
506 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
507 {
508 if (options.proxy_command == NULL) {
509 return ssh_connect_direct(host, addrs, hostaddr, port, family,
510 connection_attempts, timeout_ms, want_keepalive, needpriv);
511 } else if (strcmp(options.proxy_command, "-") == 0) {
512 packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
513 return 0; /* Always succeeds */
514 } else if (options.proxy_use_fdpass) {
515 return ssh_proxy_fdpass_connect(host, port,
516 options.proxy_command);
517 }
518 return ssh_proxy_connect(host, port, options.proxy_command);
519 }
520
521 static void
send_client_banner(int connection_out,int minor1)522 send_client_banner(int connection_out, int minor1)
523 {
524 /* Send our own protocol version identification. */
525 if (compat20) {
526 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
527 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
528 } else {
529 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
530 PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
531 }
532 if (roaming_atomicio(vwrite, connection_out, client_version_string,
533 strlen(client_version_string)) != strlen(client_version_string))
534 fatal("write: %.100s", strerror(errno));
535 chop(client_version_string);
536 debug("Local version string %.100s", client_version_string);
537 }
538
539 /*
540 * Waits for the server identification string, and sends our own
541 * identification string.
542 */
543 void
ssh_exchange_identification(int timeout_ms)544 ssh_exchange_identification(int timeout_ms)
545 {
546 char buf[256], remote_version[256]; /* must be same size! */
547 int remote_major, remote_minor, mismatch;
548 int connection_in = packet_get_connection_in();
549 int connection_out = packet_get_connection_out();
550 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
551 u_int i, n;
552 size_t len;
553 int fdsetsz, remaining, rc;
554 struct timeval t_start, t_remaining;
555 fd_set *fdset;
556
557 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
558 fdset = xcalloc(1, fdsetsz);
559
560 /*
561 * If we are SSH2-only then we can send the banner immediately and
562 * save a round-trip.
563 */
564 if (options.protocol == SSH_PROTO_2) {
565 enable_compat20();
566 send_client_banner(connection_out, 0);
567 client_banner_sent = 1;
568 }
569
570 /* Read other side's version identification. */
571 remaining = timeout_ms;
572 for (n = 0;;) {
573 for (i = 0; i < sizeof(buf) - 1; i++) {
574 if (timeout_ms > 0) {
575 gettimeofday(&t_start, NULL);
576 ms_to_timeval(&t_remaining, remaining);
577 FD_SET(connection_in, fdset);
578 rc = select(connection_in + 1, fdset, NULL,
579 fdset, &t_remaining);
580 ms_subtract_diff(&t_start, &remaining);
581 if (rc == 0 || remaining <= 0)
582 fatal("Connection timed out during "
583 "banner exchange");
584 if (rc == -1) {
585 if (errno == EINTR)
586 continue;
587 fatal("ssh_exchange_identification: "
588 "select: %s", strerror(errno));
589 }
590 }
591
592 len = roaming_atomicio(read, connection_in, &buf[i], 1);
593
594 if (len != 1 && errno == EPIPE)
595 fatal("ssh_exchange_identification: "
596 "Connection closed by remote host");
597 else if (len != 1)
598 fatal("ssh_exchange_identification: "
599 "read: %.100s", strerror(errno));
600 if (buf[i] == '\r') {
601 buf[i] = '\n';
602 buf[i + 1] = 0;
603 continue; /**XXX wait for \n */
604 }
605 if (buf[i] == '\n') {
606 buf[i + 1] = 0;
607 break;
608 }
609 if (++n > 65536)
610 fatal("ssh_exchange_identification: "
611 "No banner received");
612 }
613 buf[sizeof(buf) - 1] = 0;
614 if (strncmp(buf, "SSH-", 4) == 0)
615 break;
616 debug("ssh_exchange_identification: %s", buf);
617 }
618 server_version_string = xstrdup(buf);
619 free(fdset);
620
621 /*
622 * Check that the versions match. In future this might accept
623 * several versions and set appropriate flags to handle them.
624 */
625 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
626 &remote_major, &remote_minor, remote_version) != 3)
627 fatal("Bad remote protocol version identification: '%.100s'", buf);
628 debug("Remote protocol version %d.%d, remote software version %.100s",
629 remote_major, remote_minor, remote_version);
630
631 active_state->compat = compat_datafellows(remote_version);
632 mismatch = 0;
633
634 switch (remote_major) {
635 case 1:
636 if (remote_minor == 99 &&
637 (options.protocol & SSH_PROTO_2) &&
638 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
639 enable_compat20();
640 break;
641 }
642 if (!(options.protocol & SSH_PROTO_1)) {
643 mismatch = 1;
644 break;
645 }
646 if (remote_minor < 3) {
647 fatal("Remote machine has too old SSH software version.");
648 } else if (remote_minor == 3 || remote_minor == 4) {
649 /* We speak 1.3, too. */
650 enable_compat13();
651 minor1 = 3;
652 if (options.forward_agent) {
653 logit("Agent forwarding disabled for protocol 1.3");
654 options.forward_agent = 0;
655 }
656 }
657 break;
658 case 2:
659 if (options.protocol & SSH_PROTO_2) {
660 enable_compat20();
661 break;
662 }
663 /* FALLTHROUGH */
664 default:
665 mismatch = 1;
666 break;
667 }
668 if (mismatch)
669 fatal("Protocol major versions differ: %d vs. %d",
670 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
671 remote_major);
672 if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
673 fatal("Server version \"%.100s\" uses unsafe key agreement; "
674 "refusing connection", remote_version);
675 if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
676 logit("Server version \"%.100s\" uses unsafe RSA signature "
677 "scheme; disabling use of RSA keys", remote_version);
678 if (!client_banner_sent)
679 send_client_banner(connection_out, minor1);
680 chop(server_version_string);
681 }
682
683 /* defaults to 'no' */
684 static int
confirm(const char * prompt)685 confirm(const char *prompt)
686 {
687 const char *msg, *again = "Please type 'yes' or 'no': ";
688 char *p;
689 int ret = -1;
690
691 if (options.batch_mode)
692 return 0;
693 for (msg = prompt;;msg = again) {
694 p = read_passphrase(msg, RP_ECHO);
695 if (p == NULL ||
696 (p[0] == '\0') || (p[0] == '\n') ||
697 strncasecmp(p, "no", 2) == 0)
698 ret = 0;
699 if (p && strncasecmp(p, "yes", 3) == 0)
700 ret = 1;
701 free(p);
702 if (ret != -1)
703 return ret;
704 }
705 }
706
707 static int
check_host_cert(const char * host,const Key * host_key)708 check_host_cert(const char *host, const Key *host_key)
709 {
710 const char *reason;
711
712 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
713 error("%s", reason);
714 return 0;
715 }
716 if (buffer_len(host_key->cert->critical) != 0) {
717 error("Certificate for %s contains unsupported "
718 "critical options(s)", host);
719 return 0;
720 }
721 return 1;
722 }
723
724 static int
sockaddr_is_local(struct sockaddr * hostaddr)725 sockaddr_is_local(struct sockaddr *hostaddr)
726 {
727 switch (hostaddr->sa_family) {
728 case AF_INET:
729 return (ntohl(((struct sockaddr_in *)hostaddr)->
730 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
731 case AF_INET6:
732 return IN6_IS_ADDR_LOOPBACK(
733 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
734 default:
735 return 0;
736 }
737 }
738
739 /*
740 * Prepare the hostname and ip address strings that are used to lookup
741 * host keys in known_hosts files. These may have a port number appended.
742 */
743 void
get_hostfile_hostname_ipaddr(char * hostname,struct sockaddr * hostaddr,u_short port,char ** hostfile_hostname,char ** hostfile_ipaddr)744 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
745 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
746 {
747 char ntop[NI_MAXHOST];
748 socklen_t addrlen;
749
750 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
751 case -1:
752 addrlen = 0;
753 break;
754 case AF_INET:
755 addrlen = sizeof(struct sockaddr_in);
756 break;
757 case AF_INET6:
758 addrlen = sizeof(struct sockaddr_in6);
759 break;
760 default:
761 addrlen = sizeof(struct sockaddr);
762 break;
763 }
764
765 /*
766 * We don't have the remote ip-address for connections
767 * using a proxy command
768 */
769 if (hostfile_ipaddr != NULL) {
770 if (options.proxy_command == NULL) {
771 if (getnameinfo(hostaddr, addrlen,
772 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
773 fatal("%s: getnameinfo failed", __func__);
774 *hostfile_ipaddr = put_host_port(ntop, port);
775 } else {
776 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
777 "command>");
778 }
779 }
780
781 /*
782 * Allow the user to record the key under a different name or
783 * differentiate a non-standard port. This is useful for ssh
784 * tunneling over forwarded connections or if you run multiple
785 * sshd's on different ports on the same machine.
786 */
787 if (hostfile_hostname != NULL) {
788 if (options.host_key_alias != NULL) {
789 *hostfile_hostname = xstrdup(options.host_key_alias);
790 debug("using hostkeyalias: %s", *hostfile_hostname);
791 } else {
792 *hostfile_hostname = put_host_port(hostname, port);
793 }
794 }
795 }
796
797 /*
798 * check whether the supplied host key is valid, return -1 if the key
799 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
800 */
801 #define RDRW 0
802 #define RDONLY 1
803 #define ROQUIET 2
804 static int
check_host_key(char * hostname,struct sockaddr * hostaddr,u_short port,Key * host_key,int readonly,char ** user_hostfiles,u_int num_user_hostfiles,char ** system_hostfiles,u_int num_system_hostfiles)805 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
806 Key *host_key, int readonly,
807 char **user_hostfiles, u_int num_user_hostfiles,
808 char **system_hostfiles, u_int num_system_hostfiles)
809 {
810 HostStatus host_status;
811 HostStatus ip_status;
812 Key *raw_key = NULL;
813 char *ip = NULL, *host = NULL;
814 char hostline[1000], *hostp, *fp, *ra;
815 char msg[1024];
816 const char *type;
817 const struct hostkey_entry *host_found, *ip_found;
818 int len, cancelled_forwarding = 0;
819 int local = sockaddr_is_local(hostaddr);
820 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
821 int hostkey_trusted = 0; /* Known or explicitly accepted by user */
822 struct hostkeys *host_hostkeys, *ip_hostkeys;
823 u_int i;
824
825 /*
826 * Force accepting of the host key for loopback/localhost. The
827 * problem is that if the home directory is NFS-mounted to multiple
828 * machines, localhost will refer to a different machine in each of
829 * them, and the user will get bogus HOST_CHANGED warnings. This
830 * essentially disables host authentication for localhost; however,
831 * this is probably not a real problem.
832 */
833 if (options.no_host_authentication_for_localhost == 1 && local &&
834 options.host_key_alias == NULL) {
835 debug("Forcing accepting of host key for "
836 "loopback/localhost.");
837 return 0;
838 }
839
840 /*
841 * Prepare the hostname and address strings used for hostkey lookup.
842 * In some cases, these will have a port number appended.
843 */
844 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
845
846 /*
847 * Turn off check_host_ip if the connection is to localhost, via proxy
848 * command or if we don't have a hostname to compare with
849 */
850 if (options.check_host_ip && (local ||
851 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
852 options.check_host_ip = 0;
853
854 host_hostkeys = init_hostkeys();
855 for (i = 0; i < num_user_hostfiles; i++)
856 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
857 for (i = 0; i < num_system_hostfiles; i++)
858 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
859
860 ip_hostkeys = NULL;
861 if (!want_cert && options.check_host_ip) {
862 ip_hostkeys = init_hostkeys();
863 for (i = 0; i < num_user_hostfiles; i++)
864 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
865 for (i = 0; i < num_system_hostfiles; i++)
866 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
867 }
868
869 retry:
870 /* Reload these as they may have changed on cert->key downgrade */
871 want_cert = key_is_cert(host_key);
872 type = key_type(host_key);
873
874 /*
875 * Check if the host key is present in the user's list of known
876 * hosts or in the systemwide list.
877 */
878 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
879 &host_found);
880
881 /*
882 * Also perform check for the ip address, skip the check if we are
883 * localhost, looking for a certificate, or the hostname was an ip
884 * address to begin with.
885 */
886 if (!want_cert && ip_hostkeys != NULL) {
887 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
888 &ip_found);
889 if (host_status == HOST_CHANGED &&
890 (ip_status != HOST_CHANGED ||
891 (ip_found != NULL &&
892 !key_equal(ip_found->key, host_found->key))))
893 host_ip_differ = 1;
894 } else
895 ip_status = host_status;
896
897 switch (host_status) {
898 case HOST_OK:
899 /* The host is known and the key matches. */
900 debug("Host '%.200s' is known and matches the %s host %s.",
901 host, type, want_cert ? "certificate" : "key");
902 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
903 host_found->file, host_found->line);
904 if (want_cert && !check_host_cert(hostname, host_key))
905 goto fail;
906 if (options.check_host_ip && ip_status == HOST_NEW) {
907 if (readonly || want_cert)
908 logit("%s host key for IP address "
909 "'%.128s' not in list of known hosts.",
910 type, ip);
911 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
912 host_key, options.hash_known_hosts))
913 logit("Failed to add the %s host key for IP "
914 "address '%.128s' to the list of known "
915 "hosts (%.30s).", type, ip,
916 user_hostfiles[0]);
917 else
918 logit("Warning: Permanently added the %s host "
919 "key for IP address '%.128s' to the list "
920 "of known hosts.", type, ip);
921 } else if (options.visual_host_key) {
922 fp = sshkey_fingerprint(host_key,
923 options.fingerprint_hash, SSH_FP_DEFAULT);
924 ra = sshkey_fingerprint(host_key,
925 options.fingerprint_hash, SSH_FP_RANDOMART);
926 if (fp == NULL || ra == NULL)
927 fatal("%s: sshkey_fingerprint fail", __func__);
928 logit("Host key fingerprint is %s\n%s\n", fp, ra);
929 free(ra);
930 free(fp);
931 }
932 hostkey_trusted = 1;
933 break;
934 case HOST_NEW:
935 if (options.host_key_alias == NULL && port != 0 &&
936 port != SSH_DEFAULT_PORT) {
937 debug("checking without port identifier");
938 if (check_host_key(hostname, hostaddr, 0, host_key,
939 ROQUIET, user_hostfiles, num_user_hostfiles,
940 system_hostfiles, num_system_hostfiles) == 0) {
941 debug("found matching key w/out port");
942 break;
943 }
944 }
945 if (readonly || want_cert)
946 goto fail;
947 /* The host is new. */
948 if (options.strict_host_key_checking == 1) {
949 /*
950 * User has requested strict host key checking. We
951 * will not add the host key automatically. The only
952 * alternative left is to abort.
953 */
954 error("No %s host key is known for %.200s and you "
955 "have requested strict checking.", type, host);
956 goto fail;
957 } else if (options.strict_host_key_checking == 2) {
958 char msg1[1024], msg2[1024];
959
960 if (show_other_keys(host_hostkeys, host_key))
961 snprintf(msg1, sizeof(msg1),
962 "\nbut keys of different type are already"
963 " known for this host.");
964 else
965 snprintf(msg1, sizeof(msg1), ".");
966 /* The default */
967 fp = sshkey_fingerprint(host_key,
968 options.fingerprint_hash, SSH_FP_DEFAULT);
969 ra = sshkey_fingerprint(host_key,
970 options.fingerprint_hash, SSH_FP_RANDOMART);
971 if (fp == NULL || ra == NULL)
972 fatal("%s: sshkey_fingerprint fail", __func__);
973 msg2[0] = '\0';
974 if (options.verify_host_key_dns) {
975 if (matching_host_key_dns)
976 snprintf(msg2, sizeof(msg2),
977 "Matching host key fingerprint"
978 " found in DNS.\n");
979 else
980 snprintf(msg2, sizeof(msg2),
981 "No matching host key fingerprint"
982 " found in DNS.\n");
983 }
984 snprintf(msg, sizeof(msg),
985 "The authenticity of host '%.200s (%s)' can't be "
986 "established%s\n"
987 "%s key fingerprint is %s.%s%s\n%s"
988 "Are you sure you want to continue connecting "
989 "(yes/no)? ",
990 host, ip, msg1, type, fp,
991 options.visual_host_key ? "\n" : "",
992 options.visual_host_key ? ra : "",
993 msg2);
994 free(ra);
995 free(fp);
996 if (!confirm(msg))
997 goto fail;
998 hostkey_trusted = 1; /* user explicitly confirmed */
999 }
1000 /*
1001 * If not in strict mode, add the key automatically to the
1002 * local known_hosts file.
1003 */
1004 if (options.check_host_ip && ip_status == HOST_NEW) {
1005 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1006 hostp = hostline;
1007 if (options.hash_known_hosts) {
1008 /* Add hash of host and IP separately */
1009 r = add_host_to_hostfile(user_hostfiles[0],
1010 host, host_key, options.hash_known_hosts) &&
1011 add_host_to_hostfile(user_hostfiles[0], ip,
1012 host_key, options.hash_known_hosts);
1013 } else {
1014 /* Add unhashed "host,ip" */
1015 r = add_host_to_hostfile(user_hostfiles[0],
1016 hostline, host_key,
1017 options.hash_known_hosts);
1018 }
1019 } else {
1020 r = add_host_to_hostfile(user_hostfiles[0], host,
1021 host_key, options.hash_known_hosts);
1022 hostp = host;
1023 }
1024
1025 if (!r)
1026 logit("Failed to add the host to the list of known "
1027 "hosts (%.500s).", user_hostfiles[0]);
1028 else
1029 logit("Warning: Permanently added '%.200s' (%s) to the "
1030 "list of known hosts.", hostp, type);
1031 break;
1032 case HOST_REVOKED:
1033 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1034 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1035 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1036 error("The %s host key for %s is marked as revoked.", type, host);
1037 error("This could mean that a stolen key is being used to");
1038 error("impersonate this host.");
1039
1040 /*
1041 * If strict host key checking is in use, the user will have
1042 * to edit the key manually and we can only abort.
1043 */
1044 if (options.strict_host_key_checking) {
1045 error("%s host key for %.200s was revoked and you have "
1046 "requested strict checking.", type, host);
1047 goto fail;
1048 }
1049 goto continue_unsafe;
1050
1051 case HOST_CHANGED:
1052 if (want_cert) {
1053 /*
1054 * This is only a debug() since it is valid to have
1055 * CAs with wildcard DNS matches that don't match
1056 * all hosts that one might visit.
1057 */
1058 debug("Host certificate authority does not "
1059 "match %s in %s:%lu", CA_MARKER,
1060 host_found->file, host_found->line);
1061 goto fail;
1062 }
1063 if (readonly == ROQUIET)
1064 goto fail;
1065 if (options.check_host_ip && host_ip_differ) {
1066 char *key_msg;
1067 if (ip_status == HOST_NEW)
1068 key_msg = "is unknown";
1069 else if (ip_status == HOST_OK)
1070 key_msg = "is unchanged";
1071 else
1072 key_msg = "has a different value";
1073 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1074 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1075 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1076 error("The %s host key for %s has changed,", type, host);
1077 error("and the key for the corresponding IP address %s", ip);
1078 error("%s. This could either mean that", key_msg);
1079 error("DNS SPOOFING is happening or the IP address for the host");
1080 error("and its host key have changed at the same time.");
1081 if (ip_status != HOST_NEW)
1082 error("Offending key for IP in %s:%lu",
1083 ip_found->file, ip_found->line);
1084 }
1085 /* The host key has changed. */
1086 warn_changed_key(host_key);
1087 error("Add correct host key in %.100s to get rid of this message.",
1088 user_hostfiles[0]);
1089 error("Offending %s key in %s:%lu", key_type(host_found->key),
1090 host_found->file, host_found->line);
1091
1092 /*
1093 * If strict host key checking is in use, the user will have
1094 * to edit the key manually and we can only abort.
1095 */
1096 if (options.strict_host_key_checking) {
1097 error("%s host key for %.200s has changed and you have "
1098 "requested strict checking.", type, host);
1099 goto fail;
1100 }
1101
1102 continue_unsafe:
1103 /*
1104 * If strict host key checking has not been requested, allow
1105 * the connection but without MITM-able authentication or
1106 * forwarding.
1107 */
1108 if (options.password_authentication) {
1109 error("Password authentication is disabled to avoid "
1110 "man-in-the-middle attacks.");
1111 options.password_authentication = 0;
1112 cancelled_forwarding = 1;
1113 }
1114 if (options.kbd_interactive_authentication) {
1115 error("Keyboard-interactive authentication is disabled"
1116 " to avoid man-in-the-middle attacks.");
1117 options.kbd_interactive_authentication = 0;
1118 options.challenge_response_authentication = 0;
1119 cancelled_forwarding = 1;
1120 }
1121 if (options.challenge_response_authentication) {
1122 error("Challenge/response authentication is disabled"
1123 " to avoid man-in-the-middle attacks.");
1124 options.challenge_response_authentication = 0;
1125 cancelled_forwarding = 1;
1126 }
1127 if (options.forward_agent) {
1128 error("Agent forwarding is disabled to avoid "
1129 "man-in-the-middle attacks.");
1130 options.forward_agent = 0;
1131 cancelled_forwarding = 1;
1132 }
1133 if (options.forward_x11) {
1134 error("X11 forwarding is disabled to avoid "
1135 "man-in-the-middle attacks.");
1136 options.forward_x11 = 0;
1137 cancelled_forwarding = 1;
1138 }
1139 if (options.num_local_forwards > 0 ||
1140 options.num_remote_forwards > 0) {
1141 error("Port forwarding is disabled to avoid "
1142 "man-in-the-middle attacks.");
1143 options.num_local_forwards =
1144 options.num_remote_forwards = 0;
1145 cancelled_forwarding = 1;
1146 }
1147 if (options.tun_open != SSH_TUNMODE_NO) {
1148 error("Tunnel forwarding is disabled to avoid "
1149 "man-in-the-middle attacks.");
1150 options.tun_open = SSH_TUNMODE_NO;
1151 cancelled_forwarding = 1;
1152 }
1153 if (options.exit_on_forward_failure && cancelled_forwarding)
1154 fatal("Error: forwarding disabled due to host key "
1155 "check failure");
1156
1157 /*
1158 * XXX Should permit the user to change to use the new id.
1159 * This could be done by converting the host key to an
1160 * identifying sentence, tell that the host identifies itself
1161 * by that sentence, and ask the user if he/she wishes to
1162 * accept the authentication.
1163 */
1164 break;
1165 case HOST_FOUND:
1166 fatal("internal error");
1167 break;
1168 }
1169
1170 if (options.check_host_ip && host_status != HOST_CHANGED &&
1171 ip_status == HOST_CHANGED) {
1172 snprintf(msg, sizeof(msg),
1173 "Warning: the %s host key for '%.200s' "
1174 "differs from the key for the IP address '%.128s'"
1175 "\nOffending key for IP in %s:%lu",
1176 type, host, ip, ip_found->file, ip_found->line);
1177 if (host_status == HOST_OK) {
1178 len = strlen(msg);
1179 snprintf(msg + len, sizeof(msg) - len,
1180 "\nMatching host key in %s:%lu",
1181 host_found->file, host_found->line);
1182 }
1183 if (options.strict_host_key_checking == 1) {
1184 logit("%s", msg);
1185 error("Exiting, you have requested strict checking.");
1186 goto fail;
1187 } else if (options.strict_host_key_checking == 2) {
1188 strlcat(msg, "\nAre you sure you want "
1189 "to continue connecting (yes/no)? ", sizeof(msg));
1190 if (!confirm(msg))
1191 goto fail;
1192 } else {
1193 logit("%s", msg);
1194 }
1195 }
1196
1197 if (!hostkey_trusted && options.update_hostkeys) {
1198 debug("%s: hostkey not known or explicitly trusted: "
1199 "disabling UpdateHostkeys", __func__);
1200 options.update_hostkeys = 0;
1201 }
1202
1203 free(ip);
1204 free(host);
1205 if (host_hostkeys != NULL)
1206 free_hostkeys(host_hostkeys);
1207 if (ip_hostkeys != NULL)
1208 free_hostkeys(ip_hostkeys);
1209 return 0;
1210
1211 fail:
1212 if (want_cert && host_status != HOST_REVOKED) {
1213 /*
1214 * No matching certificate. Downgrade cert to raw key and
1215 * search normally.
1216 */
1217 debug("No matching CA found. Retry with plain key");
1218 raw_key = key_from_private(host_key);
1219 if (key_drop_cert(raw_key) != 0)
1220 fatal("Couldn't drop certificate");
1221 host_key = raw_key;
1222 goto retry;
1223 }
1224 if (raw_key != NULL)
1225 key_free(raw_key);
1226 free(ip);
1227 free(host);
1228 if (host_hostkeys != NULL)
1229 free_hostkeys(host_hostkeys);
1230 if (ip_hostkeys != NULL)
1231 free_hostkeys(ip_hostkeys);
1232 return -1;
1233 }
1234
1235 /* returns 0 if key verifies or -1 if key does NOT verify */
1236 int
verify_host_key(char * host,struct sockaddr * hostaddr,Key * host_key)1237 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1238 {
1239 int r = -1, flags = 0;
1240 char *fp = NULL;
1241 struct sshkey *plain = NULL;
1242
1243 if ((fp = sshkey_fingerprint(host_key,
1244 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1245 error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1246 r = -1;
1247 goto out;
1248 }
1249
1250 debug("Server host key: %s %s",
1251 compat20 ? sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
1252
1253 if (sshkey_equal(previous_host_key, host_key)) {
1254 debug2("%s: server host key %s %s matches cached key",
1255 __func__, sshkey_type(host_key), fp);
1256 r = 0;
1257 goto out;
1258 }
1259
1260 /* Check in RevokedHostKeys file if specified */
1261 if (options.revoked_host_keys != NULL) {
1262 r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1263 switch (r) {
1264 case 0:
1265 break; /* not revoked */
1266 case SSH_ERR_KEY_REVOKED:
1267 error("Host key %s %s revoked by file %s",
1268 sshkey_type(host_key), fp,
1269 options.revoked_host_keys);
1270 r = -1;
1271 goto out;
1272 default:
1273 error("Error checking host key %s %s in "
1274 "revoked keys file %s: %s", sshkey_type(host_key),
1275 fp, options.revoked_host_keys, ssh_err(r));
1276 r = -1;
1277 goto out;
1278 }
1279 }
1280
1281 if (options.verify_host_key_dns) {
1282 /*
1283 * XXX certs are not yet supported for DNS, so downgrade
1284 * them and try the plain key.
1285 */
1286 if ((r = sshkey_from_private(host_key, &plain)) != 0)
1287 goto out;
1288 if (sshkey_is_cert(plain))
1289 sshkey_drop_cert(plain);
1290 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1291 if (flags & DNS_VERIFY_FOUND) {
1292 if (options.verify_host_key_dns == 1 &&
1293 flags & DNS_VERIFY_MATCH &&
1294 flags & DNS_VERIFY_SECURE) {
1295 r = 0;
1296 goto out;
1297 }
1298 if (flags & DNS_VERIFY_MATCH) {
1299 matching_host_key_dns = 1;
1300 } else {
1301 warn_changed_key(plain);
1302 error("Update the SSHFP RR in DNS "
1303 "with the new host key to get rid "
1304 "of this message.");
1305 }
1306 }
1307 }
1308 }
1309 r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1310 options.user_hostfiles, options.num_user_hostfiles,
1311 options.system_hostfiles, options.num_system_hostfiles);
1312
1313 out:
1314 sshkey_free(plain);
1315 free(fp);
1316 if (r == 0 && host_key != NULL) {
1317 key_free(previous_host_key);
1318 previous_host_key = key_from_private(host_key);
1319 }
1320
1321 return r;
1322 }
1323
1324 /*
1325 * Starts a dialog with the server, and authenticates the current user on the
1326 * server. This does not need any extra privileges. The basic connection
1327 * to the server must already have been established before this is called.
1328 * If login fails, this function prints an error and never returns.
1329 * This function does not require super-user privileges.
1330 */
1331 void
ssh_login(Sensitive * sensitive,const char * orighost,struct sockaddr * hostaddr,u_short port,struct passwd * pw,int timeout_ms)1332 ssh_login(Sensitive *sensitive, const char *orighost,
1333 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1334 {
1335 char *host;
1336 char *server_user, *local_user;
1337
1338 local_user = xstrdup(pw->pw_name);
1339 server_user = options.user ? options.user : local_user;
1340
1341 /* Convert the user-supplied hostname into all lowercase. */
1342 host = xstrdup(orighost);
1343 lowercase(host);
1344
1345 /* Exchange protocol version identification strings with the server. */
1346 ssh_exchange_identification(timeout_ms);
1347
1348 /* Put the connection into non-blocking mode. */
1349 packet_set_nonblocking();
1350
1351 /* key exchange */
1352 /* authenticate user */
1353 if (compat20) {
1354 ssh_kex2(host, hostaddr, port);
1355 ssh_userauth2(local_user, server_user, host, sensitive);
1356 } else {
1357 #ifdef WITH_SSH1
1358 ssh_kex(host, hostaddr);
1359 ssh_userauth1(local_user, server_user, host, sensitive);
1360 #else
1361 fatal("ssh1 is not unsupported");
1362 #endif
1363 }
1364 free(local_user);
1365 }
1366
1367 void
ssh_put_password(char * password)1368 ssh_put_password(char *password)
1369 {
1370 int size;
1371 char *padded;
1372
1373 if (datafellows & SSH_BUG_PASSWORDPAD) {
1374 packet_put_cstring(password);
1375 return;
1376 }
1377 size = roundup(strlen(password) + 1, 32);
1378 padded = xcalloc(1, size);
1379 strlcpy(padded, password, size);
1380 packet_put_string(padded, size);
1381 explicit_bzero(padded, size);
1382 free(padded);
1383 }
1384
1385 /* print all known host keys for a given host, but skip keys of given type */
1386 static int
show_other_keys(struct hostkeys * hostkeys,Key * key)1387 show_other_keys(struct hostkeys *hostkeys, Key *key)
1388 {
1389 int type[] = {
1390 KEY_RSA1,
1391 KEY_RSA,
1392 KEY_DSA,
1393 KEY_ECDSA,
1394 KEY_ED25519,
1395 -1
1396 };
1397 int i, ret = 0;
1398 char *fp, *ra;
1399 const struct hostkey_entry *found;
1400
1401 for (i = 0; type[i] != -1; i++) {
1402 if (type[i] == key->type)
1403 continue;
1404 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1405 continue;
1406 fp = sshkey_fingerprint(found->key,
1407 options.fingerprint_hash, SSH_FP_DEFAULT);
1408 ra = sshkey_fingerprint(found->key,
1409 options.fingerprint_hash, SSH_FP_RANDOMART);
1410 if (fp == NULL || ra == NULL)
1411 fatal("%s: sshkey_fingerprint fail", __func__);
1412 logit("WARNING: %s key found for host %s\n"
1413 "in %s:%lu\n"
1414 "%s key fingerprint %s.",
1415 key_type(found->key),
1416 found->host, found->file, found->line,
1417 key_type(found->key), fp);
1418 if (options.visual_host_key)
1419 logit("%s", ra);
1420 free(ra);
1421 free(fp);
1422 ret = 1;
1423 }
1424 return ret;
1425 }
1426
1427 static void
warn_changed_key(Key * host_key)1428 warn_changed_key(Key *host_key)
1429 {
1430 char *fp;
1431
1432 fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1433 SSH_FP_DEFAULT);
1434 if (fp == NULL)
1435 fatal("%s: sshkey_fingerprint fail", __func__);
1436
1437 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1438 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1439 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1440 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1441 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1442 error("It is also possible that a host key has just been changed.");
1443 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1444 key_type(host_key), fp);
1445 error("Please contact your system administrator.");
1446
1447 free(fp);
1448 }
1449
1450 /*
1451 * Execute a local command
1452 */
1453 int
ssh_local_cmd(const char * args)1454 ssh_local_cmd(const char *args)
1455 {
1456 char *shell;
1457 pid_t pid;
1458 int status;
1459 void (*osighand)(int);
1460
1461 if (!options.permit_local_command ||
1462 args == NULL || !*args)
1463 return (1);
1464
1465 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1466 shell = _PATH_BSHELL;
1467
1468 osighand = signal(SIGCHLD, SIG_DFL);
1469 pid = fork();
1470 if (pid == 0) {
1471 signal(SIGPIPE, SIG_DFL);
1472 debug3("Executing %s -c \"%s\"", shell, args);
1473 execl(shell, shell, "-c", args, (char *)NULL);
1474 error("Couldn't execute %s -c \"%s\": %s",
1475 shell, args, strerror(errno));
1476 _exit(1);
1477 } else if (pid == -1)
1478 fatal("fork failed: %.100s", strerror(errno));
1479 while (waitpid(pid, &status, 0) == -1)
1480 if (errno != EINTR)
1481 fatal("Couldn't wait for child: %s", strerror(errno));
1482 signal(SIGCHLD, osighand);
1483
1484 if (!WIFEXITED(status))
1485 return (1);
1486
1487 return (WEXITSTATUS(status));
1488 }
1489