1 /* $OpenBSD: sshconnect.c,v 1.273 2017/03/10 03:22:40 dtucker 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/types.h>
19 #include <sys/wait.h>
20 #include <sys/stat.h>
21 #include <sys/socket.h>
22 #ifdef HAVE_SYS_TIME_H
23 # include <sys/time.h>
24 #endif
25
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
28
29 #include <ctype.h>
30 #include <errno.h>
31 #include <fcntl.h>
32 #include <netdb.h>
33 #ifdef HAVE_PATHS_H
34 #include <paths.h>
35 #endif
36 #include <pwd.h>
37 #include <signal.h>
38 #include <stdarg.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43
44 #include "xmalloc.h"
45 #include "key.h"
46 #include "hostfile.h"
47 #include "ssh.h"
48 #include "rsa.h"
49 #include "buffer.h"
50 #include "packet.h"
51 #include "uidswap.h"
52 #include "compat.h"
53 #include "key.h"
54 #include "sshconnect.h"
55 #include "hostfile.h"
56 #include "log.h"
57 #include "misc.h"
58 #include "readconf.h"
59 #include "atomicio.h"
60 #include "dns.h"
61 #include "monitor_fdpass.h"
62 #include "ssh2.h"
63 #include "version.h"
64 #include "authfile.h"
65 #include "ssherr.h"
66 #include "authfd.h"
67
68 char *client_version_string = NULL;
69 char *server_version_string = NULL;
70 Key *previous_host_key = NULL;
71
72 static int matching_host_key_dns = 0;
73
74 static pid_t proxy_command_pid = 0;
75
76 /* import */
77 extern Options options;
78 extern char *__progname;
79 extern uid_t original_real_uid;
80 extern uid_t original_effective_uid;
81
82 static int show_other_keys(struct hostkeys *, Key *);
83 static void warn_changed_key(Key *);
84
85 /* Expand a proxy command */
86 static char *
expand_proxy_command(const char * proxy_command,const char * user,const char * host,int port)87 expand_proxy_command(const char *proxy_command, const char *user,
88 const char *host, int port)
89 {
90 char *tmp, *ret, strport[NI_MAXSERV];
91
92 snprintf(strport, sizeof strport, "%d", port);
93 xasprintf(&tmp, "exec %s", proxy_command);
94 ret = percent_expand(tmp, "h", host, "p", strport,
95 "r", options.user, (char *)NULL);
96 free(tmp);
97 return ret;
98 }
99
100 /*
101 * Connect to the given ssh server using a proxy command that passes a
102 * a connected fd back to us.
103 */
104 static int
ssh_proxy_fdpass_connect(const char * host,u_short port,const char * proxy_command)105 ssh_proxy_fdpass_connect(const char *host, u_short port,
106 const char *proxy_command)
107 {
108 char *command_string;
109 int sp[2], sock;
110 pid_t pid;
111 char *shell;
112
113 if ((shell = getenv("SHELL")) == NULL)
114 shell = _PATH_BSHELL;
115
116 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
117 fatal("Could not create socketpair to communicate with "
118 "proxy dialer: %.100s", strerror(errno));
119
120 command_string = expand_proxy_command(proxy_command, options.user,
121 host, port);
122 debug("Executing proxy dialer command: %.500s", command_string);
123
124 /* Fork and execute the proxy command. */
125 if ((pid = fork()) == 0) {
126 char *argv[10];
127
128 /* Child. Permanently give up superuser privileges. */
129 permanently_drop_suid(original_real_uid);
130
131 close(sp[1]);
132 /* Redirect stdin and stdout. */
133 if (sp[0] != 0) {
134 if (dup2(sp[0], 0) < 0)
135 perror("dup2 stdin");
136 }
137 if (sp[0] != 1) {
138 if (dup2(sp[0], 1) < 0)
139 perror("dup2 stdout");
140 }
141 if (sp[0] >= 2)
142 close(sp[0]);
143
144 /*
145 * Stderr is left as it is so that error messages get
146 * printed on the user's terminal.
147 */
148 argv[0] = shell;
149 argv[1] = "-c";
150 argv[2] = command_string;
151 argv[3] = NULL;
152
153 /*
154 * Execute the proxy command.
155 * Note that we gave up any extra privileges above.
156 */
157 execv(argv[0], argv);
158 perror(argv[0]);
159 exit(1);
160 }
161 /* Parent. */
162 if (pid < 0)
163 fatal("fork failed: %.100s", strerror(errno));
164 close(sp[0]);
165 free(command_string);
166
167 if ((sock = mm_receive_fd(sp[1])) == -1)
168 fatal("proxy dialer did not pass back a connection");
169 close(sp[1]);
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 = 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("%s: needpriv %d", __func__, needpriv);
436 memset(ntop, 0, sizeof(ntop));
437 memset(strport, 0, sizeof(strport));
438
439 for (attempt = 0; attempt < connection_attempts; attempt++) {
440 if (attempt > 0) {
441 /* Sleep a moment before retrying. */
442 sleep(1);
443 debug("Trying again...");
444 }
445 /*
446 * Loop through addresses for this host, and try each one in
447 * sequence until the connection succeeds.
448 */
449 for (ai = aitop; ai; ai = ai->ai_next) {
450 if (ai->ai_family != AF_INET &&
451 ai->ai_family != AF_INET6)
452 continue;
453 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
454 ntop, sizeof(ntop), strport, sizeof(strport),
455 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
456 error("%s: getnameinfo failed", __func__);
457 continue;
458 }
459 debug("Connecting to %.200s [%.100s] port %s.",
460 host, ntop, strport);
461
462 /* Create a socket for connecting. */
463 sock = ssh_create_socket(needpriv, ai);
464 if (sock < 0)
465 /* Any error is already output */
466 continue;
467
468 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
469 timeout_ms) >= 0) {
470 /* Successful connection. */
471 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
472 break;
473 } else {
474 debug("connect to address %s port %s: %s",
475 ntop, strport, strerror(errno));
476 close(sock);
477 sock = -1;
478 }
479 }
480 if (sock != -1)
481 break; /* Successful connection. */
482 }
483
484 /* Return failure if we didn't get a successful connection. */
485 if (sock == -1) {
486 error("ssh: connect to host %s port %s: %s",
487 host, strport, strerror(errno));
488 return (-1);
489 }
490
491 debug("Connection established.");
492
493 /* Set SO_KEEPALIVE if requested. */
494 if (want_keepalive &&
495 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
496 sizeof(on)) < 0)
497 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
498
499 /* Set the connection. */
500 packet_set_connection(sock, sock);
501
502 return 0;
503 }
504
505 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)506 ssh_connect(const char *host, struct addrinfo *addrs,
507 struct sockaddr_storage *hostaddr, u_short port, int family,
508 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
509 {
510 if (options.proxy_command == NULL) {
511 return ssh_connect_direct(host, addrs, hostaddr, port, family,
512 connection_attempts, timeout_ms, want_keepalive, needpriv);
513 } else if (strcmp(options.proxy_command, "-") == 0) {
514 packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
515 return 0; /* Always succeeds */
516 } else if (options.proxy_use_fdpass) {
517 return ssh_proxy_fdpass_connect(host, port,
518 options.proxy_command);
519 }
520 return ssh_proxy_connect(host, port, options.proxy_command);
521 }
522
523 static void
send_client_banner(int connection_out,int minor1)524 send_client_banner(int connection_out, int minor1)
525 {
526 /* Send our own protocol version identification. */
527 if (compat20) {
528 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
529 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
530 } else {
531 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
532 PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
533 }
534 if (atomicio(vwrite, connection_out, client_version_string,
535 strlen(client_version_string)) != strlen(client_version_string))
536 fatal("write: %.100s", strerror(errno));
537 chop(client_version_string);
538 debug("Local version string %.100s", client_version_string);
539 }
540
541 /*
542 * Waits for the server identification string, and sends our own
543 * identification string.
544 */
545 void
ssh_exchange_identification(int timeout_ms)546 ssh_exchange_identification(int timeout_ms)
547 {
548 char buf[256], remote_version[256]; /* must be same size! */
549 int remote_major, remote_minor, mismatch;
550 int connection_in = packet_get_connection_in();
551 int connection_out = packet_get_connection_out();
552 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
553 u_int i, n;
554 size_t len;
555 int fdsetsz, remaining, rc;
556 struct timeval t_start, t_remaining;
557 fd_set *fdset;
558
559 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
560 fdset = xcalloc(1, fdsetsz);
561
562 /*
563 * If we are SSH2-only then we can send the banner immediately and
564 * save a round-trip.
565 */
566 if (options.protocol == SSH_PROTO_2) {
567 enable_compat20();
568 send_client_banner(connection_out, 0);
569 client_banner_sent = 1;
570 }
571
572 /* Read other side's version identification. */
573 remaining = timeout_ms;
574 for (n = 0;;) {
575 for (i = 0; i < sizeof(buf) - 1; i++) {
576 if (timeout_ms > 0) {
577 gettimeofday(&t_start, NULL);
578 ms_to_timeval(&t_remaining, remaining);
579 FD_SET(connection_in, fdset);
580 rc = select(connection_in + 1, fdset, NULL,
581 fdset, &t_remaining);
582 ms_subtract_diff(&t_start, &remaining);
583 if (rc == 0 || remaining <= 0)
584 fatal("Connection timed out during "
585 "banner exchange");
586 if (rc == -1) {
587 if (errno == EINTR)
588 continue;
589 fatal("ssh_exchange_identification: "
590 "select: %s", strerror(errno));
591 }
592 }
593
594 len = atomicio(read, connection_in, &buf[i], 1);
595
596 if (len != 1 && errno == EPIPE)
597 fatal("ssh_exchange_identification: "
598 "Connection closed by remote host");
599 else if (len != 1)
600 fatal("ssh_exchange_identification: "
601 "read: %.100s", strerror(errno));
602 if (buf[i] == '\r') {
603 buf[i] = '\n';
604 buf[i + 1] = 0;
605 continue; /**XXX wait for \n */
606 }
607 if (buf[i] == '\n') {
608 buf[i + 1] = 0;
609 break;
610 }
611 if (++n > 65536)
612 fatal("ssh_exchange_identification: "
613 "No banner received");
614 }
615 buf[sizeof(buf) - 1] = 0;
616 if (strncmp(buf, "SSH-", 4) == 0)
617 break;
618 debug("ssh_exchange_identification: %s", buf);
619 }
620 server_version_string = xstrdup(buf);
621 free(fdset);
622
623 /*
624 * Check that the versions match. In future this might accept
625 * several versions and set appropriate flags to handle them.
626 */
627 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
628 &remote_major, &remote_minor, remote_version) != 3)
629 fatal("Bad remote protocol version identification: '%.100s'", buf);
630 debug("Remote protocol version %d.%d, remote software version %.100s",
631 remote_major, remote_minor, remote_version);
632
633 active_state->compat = compat_datafellows(remote_version);
634 mismatch = 0;
635
636 switch (remote_major) {
637 case 1:
638 if (remote_minor == 99 &&
639 (options.protocol & SSH_PROTO_2) &&
640 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
641 enable_compat20();
642 break;
643 }
644 if (!(options.protocol & SSH_PROTO_1)) {
645 mismatch = 1;
646 break;
647 }
648 if (remote_minor < 3) {
649 fatal("Remote machine has too old SSH software version.");
650 } else if (remote_minor == 3 || remote_minor == 4) {
651 /* We speak 1.3, too. */
652 enable_compat13();
653 minor1 = 3;
654 if (options.forward_agent) {
655 logit("Agent forwarding disabled for protocol 1.3");
656 options.forward_agent = 0;
657 }
658 }
659 break;
660 case 2:
661 if (options.protocol & SSH_PROTO_2) {
662 enable_compat20();
663 break;
664 }
665 /* FALLTHROUGH */
666 default:
667 mismatch = 1;
668 break;
669 }
670 if (mismatch)
671 fatal("Protocol major versions differ: %d vs. %d",
672 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
673 remote_major);
674 if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
675 fatal("Server version \"%.100s\" uses unsafe key agreement; "
676 "refusing connection", remote_version);
677 if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
678 logit("Server version \"%.100s\" uses unsafe RSA signature "
679 "scheme; disabling use of RSA keys", remote_version);
680 if (!client_banner_sent)
681 send_client_banner(connection_out, minor1);
682 chop(server_version_string);
683 }
684
685 /* defaults to 'no' */
686 static int
confirm(const char * prompt)687 confirm(const char *prompt)
688 {
689 const char *msg, *again = "Please type 'yes' or 'no': ";
690 char *p;
691 int ret = -1;
692
693 if (options.batch_mode)
694 return 0;
695 for (msg = prompt;;msg = again) {
696 p = read_passphrase(msg, RP_ECHO);
697 if (p == NULL ||
698 (p[0] == '\0') || (p[0] == '\n') ||
699 strncasecmp(p, "no", 2) == 0)
700 ret = 0;
701 if (p && strncasecmp(p, "yes", 3) == 0)
702 ret = 1;
703 free(p);
704 if (ret != -1)
705 return ret;
706 }
707 }
708
709 static int
check_host_cert(const char * host,const Key * host_key)710 check_host_cert(const char *host, const Key *host_key)
711 {
712 const char *reason;
713
714 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
715 error("%s", reason);
716 return 0;
717 }
718 if (buffer_len(host_key->cert->critical) != 0) {
719 error("Certificate for %s contains unsupported "
720 "critical options(s)", host);
721 return 0;
722 }
723 return 1;
724 }
725
726 static int
sockaddr_is_local(struct sockaddr * hostaddr)727 sockaddr_is_local(struct sockaddr *hostaddr)
728 {
729 switch (hostaddr->sa_family) {
730 case AF_INET:
731 return (ntohl(((struct sockaddr_in *)hostaddr)->
732 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
733 case AF_INET6:
734 return IN6_IS_ADDR_LOOPBACK(
735 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
736 default:
737 return 0;
738 }
739 }
740
741 /*
742 * Prepare the hostname and ip address strings that are used to lookup
743 * host keys in known_hosts files. These may have a port number appended.
744 */
745 void
get_hostfile_hostname_ipaddr(char * hostname,struct sockaddr * hostaddr,u_short port,char ** hostfile_hostname,char ** hostfile_ipaddr)746 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
747 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
748 {
749 char ntop[NI_MAXHOST];
750 socklen_t addrlen;
751
752 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
753 case -1:
754 addrlen = 0;
755 break;
756 case AF_INET:
757 addrlen = sizeof(struct sockaddr_in);
758 break;
759 case AF_INET6:
760 addrlen = sizeof(struct sockaddr_in6);
761 break;
762 default:
763 addrlen = sizeof(struct sockaddr);
764 break;
765 }
766
767 /*
768 * We don't have the remote ip-address for connections
769 * using a proxy command
770 */
771 if (hostfile_ipaddr != NULL) {
772 if (options.proxy_command == NULL) {
773 if (getnameinfo(hostaddr, addrlen,
774 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
775 fatal("%s: getnameinfo failed", __func__);
776 *hostfile_ipaddr = put_host_port(ntop, port);
777 } else {
778 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
779 "command>");
780 }
781 }
782
783 /*
784 * Allow the user to record the key under a different name or
785 * differentiate a non-standard port. This is useful for ssh
786 * tunneling over forwarded connections or if you run multiple
787 * sshd's on different ports on the same machine.
788 */
789 if (hostfile_hostname != NULL) {
790 if (options.host_key_alias != NULL) {
791 *hostfile_hostname = xstrdup(options.host_key_alias);
792 debug("using hostkeyalias: %s", *hostfile_hostname);
793 } else {
794 *hostfile_hostname = put_host_port(hostname, port);
795 }
796 }
797 }
798
799 /*
800 * check whether the supplied host key is valid, return -1 if the key
801 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
802 */
803 #define RDRW 0
804 #define RDONLY 1
805 #define ROQUIET 2
806 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)807 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
808 Key *host_key, int readonly,
809 char **user_hostfiles, u_int num_user_hostfiles,
810 char **system_hostfiles, u_int num_system_hostfiles)
811 {
812 HostStatus host_status;
813 HostStatus ip_status;
814 Key *raw_key = NULL;
815 char *ip = NULL, *host = NULL;
816 char hostline[1000], *hostp, *fp, *ra;
817 char msg[1024];
818 const char *type;
819 const struct hostkey_entry *host_found, *ip_found;
820 int len, cancelled_forwarding = 0;
821 int local = sockaddr_is_local(hostaddr);
822 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
823 int hostkey_trusted = 0; /* Known or explicitly accepted by user */
824 struct hostkeys *host_hostkeys, *ip_hostkeys;
825 u_int i;
826
827 /*
828 * Force accepting of the host key for loopback/localhost. The
829 * problem is that if the home directory is NFS-mounted to multiple
830 * machines, localhost will refer to a different machine in each of
831 * them, and the user will get bogus HOST_CHANGED warnings. This
832 * essentially disables host authentication for localhost; however,
833 * this is probably not a real problem.
834 */
835 if (options.no_host_authentication_for_localhost == 1 && local &&
836 options.host_key_alias == NULL) {
837 debug("Forcing accepting of host key for "
838 "loopback/localhost.");
839 return 0;
840 }
841
842 /*
843 * Prepare the hostname and address strings used for hostkey lookup.
844 * In some cases, these will have a port number appended.
845 */
846 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
847
848 /*
849 * Turn off check_host_ip if the connection is to localhost, via proxy
850 * command or if we don't have a hostname to compare with
851 */
852 if (options.check_host_ip && (local ||
853 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
854 options.check_host_ip = 0;
855
856 host_hostkeys = init_hostkeys();
857 for (i = 0; i < num_user_hostfiles; i++)
858 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
859 for (i = 0; i < num_system_hostfiles; i++)
860 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
861
862 ip_hostkeys = NULL;
863 if (!want_cert && options.check_host_ip) {
864 ip_hostkeys = init_hostkeys();
865 for (i = 0; i < num_user_hostfiles; i++)
866 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
867 for (i = 0; i < num_system_hostfiles; i++)
868 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
869 }
870
871 retry:
872 /* Reload these as they may have changed on cert->key downgrade */
873 want_cert = key_is_cert(host_key);
874 type = key_type(host_key);
875
876 /*
877 * Check if the host key is present in the user's list of known
878 * hosts or in the systemwide list.
879 */
880 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
881 &host_found);
882
883 /*
884 * Also perform check for the ip address, skip the check if we are
885 * localhost, looking for a certificate, or the hostname was an ip
886 * address to begin with.
887 */
888 if (!want_cert && ip_hostkeys != NULL) {
889 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
890 &ip_found);
891 if (host_status == HOST_CHANGED &&
892 (ip_status != HOST_CHANGED ||
893 (ip_found != NULL &&
894 !key_equal(ip_found->key, host_found->key))))
895 host_ip_differ = 1;
896 } else
897 ip_status = host_status;
898
899 switch (host_status) {
900 case HOST_OK:
901 /* The host is known and the key matches. */
902 debug("Host '%.200s' is known and matches the %s host %s.",
903 host, type, want_cert ? "certificate" : "key");
904 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
905 host_found->file, host_found->line);
906 if (want_cert && !check_host_cert(hostname, host_key))
907 goto fail;
908 if (options.check_host_ip && ip_status == HOST_NEW) {
909 if (readonly || want_cert)
910 logit("%s host key for IP address "
911 "'%.128s' not in list of known hosts.",
912 type, ip);
913 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
914 host_key, options.hash_known_hosts))
915 logit("Failed to add the %s host key for IP "
916 "address '%.128s' to the list of known "
917 "hosts (%.500s).", type, ip,
918 user_hostfiles[0]);
919 else
920 logit("Warning: Permanently added the %s host "
921 "key for IP address '%.128s' to the list "
922 "of known hosts.", type, ip);
923 } else if (options.visual_host_key) {
924 fp = sshkey_fingerprint(host_key,
925 options.fingerprint_hash, SSH_FP_DEFAULT);
926 ra = sshkey_fingerprint(host_key,
927 options.fingerprint_hash, SSH_FP_RANDOMART);
928 if (fp == NULL || ra == NULL)
929 fatal("%s: sshkey_fingerprint fail", __func__);
930 logit("Host key fingerprint is %s\n%s", fp, ra);
931 free(ra);
932 free(fp);
933 }
934 hostkey_trusted = 1;
935 break;
936 case HOST_NEW:
937 if (options.host_key_alias == NULL && port != 0 &&
938 port != SSH_DEFAULT_PORT) {
939 debug("checking without port identifier");
940 if (check_host_key(hostname, hostaddr, 0, host_key,
941 ROQUIET, user_hostfiles, num_user_hostfiles,
942 system_hostfiles, num_system_hostfiles) == 0) {
943 debug("found matching key w/out port");
944 break;
945 }
946 }
947 if (readonly || want_cert)
948 goto fail;
949 /* The host is new. */
950 if (options.strict_host_key_checking == 1) {
951 /*
952 * User has requested strict host key checking. We
953 * will not add the host key automatically. The only
954 * alternative left is to abort.
955 */
956 error("No %s host key is known for %.200s and you "
957 "have requested strict checking.", type, host);
958 goto fail;
959 } else if (options.strict_host_key_checking == 2) {
960 char msg1[1024], msg2[1024];
961
962 if (show_other_keys(host_hostkeys, host_key))
963 snprintf(msg1, sizeof(msg1),
964 "\nbut keys of different type are already"
965 " known for this host.");
966 else
967 snprintf(msg1, sizeof(msg1), ".");
968 /* The default */
969 fp = sshkey_fingerprint(host_key,
970 options.fingerprint_hash, SSH_FP_DEFAULT);
971 ra = sshkey_fingerprint(host_key,
972 options.fingerprint_hash, SSH_FP_RANDOMART);
973 if (fp == NULL || ra == NULL)
974 fatal("%s: sshkey_fingerprint fail", __func__);
975 msg2[0] = '\0';
976 if (options.verify_host_key_dns) {
977 if (matching_host_key_dns)
978 snprintf(msg2, sizeof(msg2),
979 "Matching host key fingerprint"
980 " found in DNS.\n");
981 else
982 snprintf(msg2, sizeof(msg2),
983 "No matching host key fingerprint"
984 " found in DNS.\n");
985 }
986 snprintf(msg, sizeof(msg),
987 "The authenticity of host '%.200s (%s)' can't be "
988 "established%s\n"
989 "%s key fingerprint is %s.%s%s\n%s"
990 "Are you sure you want to continue connecting "
991 "(yes/no)? ",
992 host, ip, msg1, type, fp,
993 options.visual_host_key ? "\n" : "",
994 options.visual_host_key ? ra : "",
995 msg2);
996 free(ra);
997 free(fp);
998 if (!confirm(msg))
999 goto fail;
1000 hostkey_trusted = 1; /* user explicitly confirmed */
1001 }
1002 /*
1003 * If not in strict mode, add the key automatically to the
1004 * local known_hosts file.
1005 */
1006 if (options.check_host_ip && ip_status == HOST_NEW) {
1007 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1008 hostp = hostline;
1009 if (options.hash_known_hosts) {
1010 /* Add hash of host and IP separately */
1011 r = add_host_to_hostfile(user_hostfiles[0],
1012 host, host_key, options.hash_known_hosts) &&
1013 add_host_to_hostfile(user_hostfiles[0], ip,
1014 host_key, options.hash_known_hosts);
1015 } else {
1016 /* Add unhashed "host,ip" */
1017 r = add_host_to_hostfile(user_hostfiles[0],
1018 hostline, host_key,
1019 options.hash_known_hosts);
1020 }
1021 } else {
1022 r = add_host_to_hostfile(user_hostfiles[0], host,
1023 host_key, options.hash_known_hosts);
1024 hostp = host;
1025 }
1026
1027 if (!r)
1028 logit("Failed to add the host to the list of known "
1029 "hosts (%.500s).", user_hostfiles[0]);
1030 else
1031 logit("Warning: Permanently added '%.200s' (%s) to the "
1032 "list of known hosts.", hostp, type);
1033 break;
1034 case HOST_REVOKED:
1035 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1036 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1037 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1038 error("The %s host key for %s is marked as revoked.", type, host);
1039 error("This could mean that a stolen key is being used to");
1040 error("impersonate this host.");
1041
1042 /*
1043 * If strict host key checking is in use, the user will have
1044 * to edit the key manually and we can only abort.
1045 */
1046 if (options.strict_host_key_checking) {
1047 error("%s host key for %.200s was revoked and you have "
1048 "requested strict checking.", type, host);
1049 goto fail;
1050 }
1051 goto continue_unsafe;
1052
1053 case HOST_CHANGED:
1054 if (want_cert) {
1055 /*
1056 * This is only a debug() since it is valid to have
1057 * CAs with wildcard DNS matches that don't match
1058 * all hosts that one might visit.
1059 */
1060 debug("Host certificate authority does not "
1061 "match %s in %s:%lu", CA_MARKER,
1062 host_found->file, host_found->line);
1063 goto fail;
1064 }
1065 if (readonly == ROQUIET)
1066 goto fail;
1067 if (options.check_host_ip && host_ip_differ) {
1068 char *key_msg;
1069 if (ip_status == HOST_NEW)
1070 key_msg = "is unknown";
1071 else if (ip_status == HOST_OK)
1072 key_msg = "is unchanged";
1073 else
1074 key_msg = "has a different value";
1075 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1076 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1077 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1078 error("The %s host key for %s has changed,", type, host);
1079 error("and the key for the corresponding IP address %s", ip);
1080 error("%s. This could either mean that", key_msg);
1081 error("DNS SPOOFING is happening or the IP address for the host");
1082 error("and its host key have changed at the same time.");
1083 if (ip_status != HOST_NEW)
1084 error("Offending key for IP in %s:%lu",
1085 ip_found->file, ip_found->line);
1086 }
1087 /* The host key has changed. */
1088 warn_changed_key(host_key);
1089 error("Add correct host key in %.100s to get rid of this message.",
1090 user_hostfiles[0]);
1091 error("Offending %s key in %s:%lu", key_type(host_found->key),
1092 host_found->file, host_found->line);
1093
1094 /*
1095 * If strict host key checking is in use, the user will have
1096 * to edit the key manually and we can only abort.
1097 */
1098 if (options.strict_host_key_checking) {
1099 error("%s host key for %.200s has changed and you have "
1100 "requested strict checking.", type, host);
1101 goto fail;
1102 }
1103
1104 continue_unsafe:
1105 /*
1106 * If strict host key checking has not been requested, allow
1107 * the connection but without MITM-able authentication or
1108 * forwarding.
1109 */
1110 if (options.password_authentication) {
1111 error("Password authentication is disabled to avoid "
1112 "man-in-the-middle attacks.");
1113 options.password_authentication = 0;
1114 cancelled_forwarding = 1;
1115 }
1116 if (options.kbd_interactive_authentication) {
1117 error("Keyboard-interactive authentication is disabled"
1118 " to avoid man-in-the-middle attacks.");
1119 options.kbd_interactive_authentication = 0;
1120 options.challenge_response_authentication = 0;
1121 cancelled_forwarding = 1;
1122 }
1123 if (options.challenge_response_authentication) {
1124 error("Challenge/response authentication is disabled"
1125 " to avoid man-in-the-middle attacks.");
1126 options.challenge_response_authentication = 0;
1127 cancelled_forwarding = 1;
1128 }
1129 if (options.forward_agent) {
1130 error("Agent forwarding is disabled to avoid "
1131 "man-in-the-middle attacks.");
1132 options.forward_agent = 0;
1133 cancelled_forwarding = 1;
1134 }
1135 if (options.forward_x11) {
1136 error("X11 forwarding is disabled to avoid "
1137 "man-in-the-middle attacks.");
1138 options.forward_x11 = 0;
1139 cancelled_forwarding = 1;
1140 }
1141 if (options.num_local_forwards > 0 ||
1142 options.num_remote_forwards > 0) {
1143 error("Port forwarding is disabled to avoid "
1144 "man-in-the-middle attacks.");
1145 options.num_local_forwards =
1146 options.num_remote_forwards = 0;
1147 cancelled_forwarding = 1;
1148 }
1149 if (options.tun_open != SSH_TUNMODE_NO) {
1150 error("Tunnel forwarding is disabled to avoid "
1151 "man-in-the-middle attacks.");
1152 options.tun_open = SSH_TUNMODE_NO;
1153 cancelled_forwarding = 1;
1154 }
1155 if (options.exit_on_forward_failure && cancelled_forwarding)
1156 fatal("Error: forwarding disabled due to host key "
1157 "check failure");
1158
1159 /*
1160 * XXX Should permit the user to change to use the new id.
1161 * This could be done by converting the host key to an
1162 * identifying sentence, tell that the host identifies itself
1163 * by that sentence, and ask the user if he/she wishes to
1164 * accept the authentication.
1165 */
1166 break;
1167 case HOST_FOUND:
1168 fatal("internal error");
1169 break;
1170 }
1171
1172 if (options.check_host_ip && host_status != HOST_CHANGED &&
1173 ip_status == HOST_CHANGED) {
1174 snprintf(msg, sizeof(msg),
1175 "Warning: the %s host key for '%.200s' "
1176 "differs from the key for the IP address '%.128s'"
1177 "\nOffending key for IP in %s:%lu",
1178 type, host, ip, ip_found->file, ip_found->line);
1179 if (host_status == HOST_OK) {
1180 len = strlen(msg);
1181 snprintf(msg + len, sizeof(msg) - len,
1182 "\nMatching host key in %s:%lu",
1183 host_found->file, host_found->line);
1184 }
1185 if (options.strict_host_key_checking == 1) {
1186 logit("%s", msg);
1187 error("Exiting, you have requested strict checking.");
1188 goto fail;
1189 } else if (options.strict_host_key_checking == 2) {
1190 strlcat(msg, "\nAre you sure you want "
1191 "to continue connecting (yes/no)? ", sizeof(msg));
1192 if (!confirm(msg))
1193 goto fail;
1194 } else {
1195 logit("%s", msg);
1196 }
1197 }
1198
1199 if (!hostkey_trusted && options.update_hostkeys) {
1200 debug("%s: hostkey not known or explicitly trusted: "
1201 "disabling UpdateHostkeys", __func__);
1202 options.update_hostkeys = 0;
1203 }
1204
1205 free(ip);
1206 free(host);
1207 if (host_hostkeys != NULL)
1208 free_hostkeys(host_hostkeys);
1209 if (ip_hostkeys != NULL)
1210 free_hostkeys(ip_hostkeys);
1211 return 0;
1212
1213 fail:
1214 if (want_cert && host_status != HOST_REVOKED) {
1215 /*
1216 * No matching certificate. Downgrade cert to raw key and
1217 * search normally.
1218 */
1219 debug("No matching CA found. Retry with plain key");
1220 raw_key = key_from_private(host_key);
1221 if (key_drop_cert(raw_key) != 0)
1222 fatal("Couldn't drop certificate");
1223 host_key = raw_key;
1224 goto retry;
1225 }
1226 if (raw_key != NULL)
1227 key_free(raw_key);
1228 free(ip);
1229 free(host);
1230 if (host_hostkeys != NULL)
1231 free_hostkeys(host_hostkeys);
1232 if (ip_hostkeys != NULL)
1233 free_hostkeys(ip_hostkeys);
1234 return -1;
1235 }
1236
1237 /* returns 0 if key verifies or -1 if key does NOT verify */
1238 int
verify_host_key(char * host,struct sockaddr * hostaddr,Key * host_key)1239 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1240 {
1241 u_int i;
1242 int r = -1, flags = 0;
1243 char valid[64], *fp = NULL, *cafp = NULL;
1244 struct sshkey *plain = NULL;
1245
1246 if ((fp = sshkey_fingerprint(host_key,
1247 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1248 error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1249 r = -1;
1250 goto out;
1251 }
1252
1253 if (sshkey_is_cert(host_key)) {
1254 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1255 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1256 error("%s: fingerprint CA key: %s",
1257 __func__, ssh_err(r));
1258 r = -1;
1259 goto out;
1260 }
1261 sshkey_format_cert_validity(host_key->cert,
1262 valid, sizeof(valid));
1263 debug("Server host certificate: %s %s, serial %llu "
1264 "ID \"%s\" CA %s %s valid %s",
1265 sshkey_ssh_name(host_key), fp,
1266 (unsigned long long)host_key->cert->serial,
1267 host_key->cert->key_id,
1268 sshkey_ssh_name(host_key->cert->signature_key), cafp,
1269 valid);
1270 for (i = 0; i < host_key->cert->nprincipals; i++) {
1271 debug2("Server host certificate hostname: %s",
1272 host_key->cert->principals[i]);
1273 }
1274 } else {
1275 debug("Server host key: %s %s", compat20 ?
1276 sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
1277 }
1278
1279 if (sshkey_equal(previous_host_key, host_key)) {
1280 debug2("%s: server host key %s %s matches cached key",
1281 __func__, sshkey_type(host_key), fp);
1282 r = 0;
1283 goto out;
1284 }
1285
1286 /* Check in RevokedHostKeys file if specified */
1287 if (options.revoked_host_keys != NULL) {
1288 r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1289 switch (r) {
1290 case 0:
1291 break; /* not revoked */
1292 case SSH_ERR_KEY_REVOKED:
1293 error("Host key %s %s revoked by file %s",
1294 sshkey_type(host_key), fp,
1295 options.revoked_host_keys);
1296 r = -1;
1297 goto out;
1298 default:
1299 error("Error checking host key %s %s in "
1300 "revoked keys file %s: %s", sshkey_type(host_key),
1301 fp, options.revoked_host_keys, ssh_err(r));
1302 r = -1;
1303 goto out;
1304 }
1305 }
1306
1307 if (options.verify_host_key_dns) {
1308 /*
1309 * XXX certs are not yet supported for DNS, so downgrade
1310 * them and try the plain key.
1311 */
1312 if ((r = sshkey_from_private(host_key, &plain)) != 0)
1313 goto out;
1314 if (sshkey_is_cert(plain))
1315 sshkey_drop_cert(plain);
1316 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1317 if (flags & DNS_VERIFY_FOUND) {
1318 if (options.verify_host_key_dns == 1 &&
1319 flags & DNS_VERIFY_MATCH &&
1320 flags & DNS_VERIFY_SECURE) {
1321 r = 0;
1322 goto out;
1323 }
1324 if (flags & DNS_VERIFY_MATCH) {
1325 matching_host_key_dns = 1;
1326 } else {
1327 warn_changed_key(plain);
1328 error("Update the SSHFP RR in DNS "
1329 "with the new host key to get rid "
1330 "of this message.");
1331 }
1332 }
1333 }
1334 }
1335 r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1336 options.user_hostfiles, options.num_user_hostfiles,
1337 options.system_hostfiles, options.num_system_hostfiles);
1338
1339 out:
1340 sshkey_free(plain);
1341 free(fp);
1342 free(cafp);
1343 if (r == 0 && host_key != NULL) {
1344 key_free(previous_host_key);
1345 previous_host_key = key_from_private(host_key);
1346 }
1347
1348 return r;
1349 }
1350
1351 /*
1352 * Starts a dialog with the server, and authenticates the current user on the
1353 * server. This does not need any extra privileges. The basic connection
1354 * to the server must already have been established before this is called.
1355 * If login fails, this function prints an error and never returns.
1356 * This function does not require super-user privileges.
1357 */
1358 void
ssh_login(Sensitive * sensitive,const char * orighost,struct sockaddr * hostaddr,u_short port,struct passwd * pw,int timeout_ms)1359 ssh_login(Sensitive *sensitive, const char *orighost,
1360 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1361 {
1362 char *host;
1363 char *server_user, *local_user;
1364
1365 local_user = xstrdup(pw->pw_name);
1366 server_user = options.user ? options.user : local_user;
1367
1368 /* Convert the user-supplied hostname into all lowercase. */
1369 host = xstrdup(orighost);
1370 lowercase(host);
1371
1372 /* Exchange protocol version identification strings with the server. */
1373 ssh_exchange_identification(timeout_ms);
1374
1375 /* Put the connection into non-blocking mode. */
1376 packet_set_nonblocking();
1377
1378 /* key exchange */
1379 /* authenticate user */
1380 debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1381 if (compat20) {
1382 ssh_kex2(host, hostaddr, port);
1383 ssh_userauth2(local_user, server_user, host, sensitive);
1384 } else {
1385 #ifdef WITH_SSH1
1386 ssh_kex(host, hostaddr);
1387 ssh_userauth1(local_user, server_user, host, sensitive);
1388 #else
1389 fatal("ssh1 is not supported");
1390 #endif
1391 }
1392 free(local_user);
1393 }
1394
1395 void
ssh_put_password(char * password)1396 ssh_put_password(char *password)
1397 {
1398 int size;
1399 char *padded;
1400
1401 if (datafellows & SSH_BUG_PASSWORDPAD) {
1402 packet_put_cstring(password);
1403 return;
1404 }
1405 size = ROUNDUP(strlen(password) + 1, 32);
1406 padded = xcalloc(1, size);
1407 strlcpy(padded, password, size);
1408 packet_put_string(padded, size);
1409 explicit_bzero(padded, size);
1410 free(padded);
1411 }
1412
1413 /* print all known host keys for a given host, but skip keys of given type */
1414 static int
show_other_keys(struct hostkeys * hostkeys,Key * key)1415 show_other_keys(struct hostkeys *hostkeys, Key *key)
1416 {
1417 int type[] = {
1418 KEY_RSA1,
1419 KEY_RSA,
1420 KEY_DSA,
1421 KEY_ECDSA,
1422 KEY_ED25519,
1423 -1
1424 };
1425 int i, ret = 0;
1426 char *fp, *ra;
1427 const struct hostkey_entry *found;
1428
1429 for (i = 0; type[i] != -1; i++) {
1430 if (type[i] == key->type)
1431 continue;
1432 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1433 continue;
1434 fp = sshkey_fingerprint(found->key,
1435 options.fingerprint_hash, SSH_FP_DEFAULT);
1436 ra = sshkey_fingerprint(found->key,
1437 options.fingerprint_hash, SSH_FP_RANDOMART);
1438 if (fp == NULL || ra == NULL)
1439 fatal("%s: sshkey_fingerprint fail", __func__);
1440 logit("WARNING: %s key found for host %s\n"
1441 "in %s:%lu\n"
1442 "%s key fingerprint %s.",
1443 key_type(found->key),
1444 found->host, found->file, found->line,
1445 key_type(found->key), fp);
1446 if (options.visual_host_key)
1447 logit("%s", ra);
1448 free(ra);
1449 free(fp);
1450 ret = 1;
1451 }
1452 return ret;
1453 }
1454
1455 static void
warn_changed_key(Key * host_key)1456 warn_changed_key(Key *host_key)
1457 {
1458 char *fp;
1459
1460 fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1461 SSH_FP_DEFAULT);
1462 if (fp == NULL)
1463 fatal("%s: sshkey_fingerprint fail", __func__);
1464
1465 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1466 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1467 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1468 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1469 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1470 error("It is also possible that a host key has just been changed.");
1471 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1472 key_type(host_key), fp);
1473 error("Please contact your system administrator.");
1474
1475 free(fp);
1476 }
1477
1478 /*
1479 * Execute a local command
1480 */
1481 int
ssh_local_cmd(const char * args)1482 ssh_local_cmd(const char *args)
1483 {
1484 char *shell;
1485 pid_t pid;
1486 int status;
1487 void (*osighand)(int);
1488
1489 if (!options.permit_local_command ||
1490 args == NULL || !*args)
1491 return (1);
1492
1493 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1494 shell = _PATH_BSHELL;
1495
1496 osighand = signal(SIGCHLD, SIG_DFL);
1497 pid = fork();
1498 if (pid == 0) {
1499 signal(SIGPIPE, SIG_DFL);
1500 debug3("Executing %s -c \"%s\"", shell, args);
1501 execl(shell, shell, "-c", args, (char *)NULL);
1502 error("Couldn't execute %s -c \"%s\": %s",
1503 shell, args, strerror(errno));
1504 _exit(1);
1505 } else if (pid == -1)
1506 fatal("fork failed: %.100s", strerror(errno));
1507 while (waitpid(pid, &status, 0) == -1)
1508 if (errno != EINTR)
1509 fatal("Couldn't wait for child: %s", strerror(errno));
1510 signal(SIGCHLD, osighand);
1511
1512 if (!WIFEXITED(status))
1513 return (1);
1514
1515 return (WEXITSTATUS(status));
1516 }
1517
1518 void
maybe_add_key_to_agent(char * authfile,Key * private,char * comment,char * passphrase)1519 maybe_add_key_to_agent(char *authfile, Key *private, char *comment,
1520 char *passphrase)
1521 {
1522 int auth_sock = -1, r;
1523
1524 if (options.add_keys_to_agent == 0)
1525 return;
1526
1527 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1528 debug3("no authentication agent, not adding key");
1529 return;
1530 }
1531
1532 if (options.add_keys_to_agent == 2 &&
1533 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1534 debug3("user denied adding this key");
1535 close(auth_sock);
1536 return;
1537 }
1538
1539 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1540 (options.add_keys_to_agent == 3))) == 0)
1541 debug("identity added to agent: %s", authfile);
1542 else
1543 debug("could not add identity to agent: %s (%d)", authfile, r);
1544 close(auth_sock);
1545 }
1546