1 /* $OpenBSD: sshconnect.c,v 1.329 2020/03/13 04:01:56 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/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 <net/if.h>
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 #ifdef HAVE_POLL_H
39 #include <poll.h>
40 #endif
41 #include <signal.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <stdarg.h>
45 #include <string.h>
46 #include <unistd.h>
47 #ifdef HAVE_IFADDRS_H
48 # include <ifaddrs.h>
49 #endif
50
51 #include "xmalloc.h"
52 #include "hostfile.h"
53 #include "ssh.h"
54 #include "sshbuf.h"
55 #include "packet.h"
56 #include "compat.h"
57 #include "sshkey.h"
58 #include "sshconnect.h"
59 #include "log.h"
60 #include "misc.h"
61 #include "readconf.h"
62 #include "atomicio.h"
63 #include "dns.h"
64 #include "monitor_fdpass.h"
65 #include "ssh2.h"
66 #include "version.h"
67 #include "authfile.h"
68 #include "ssherr.h"
69 #include "authfd.h"
70 #include "kex.h"
71
72 struct sshkey *previous_host_key = NULL;
73
74 static int matching_host_key_dns = 0;
75
76 static pid_t proxy_command_pid = 0;
77
78 /* import */
79 extern int debug_flag;
80 extern Options options;
81 extern char *__progname;
82
83 static int show_other_keys(struct hostkeys *, struct sshkey *);
84 static void warn_changed_key(struct sshkey *);
85
86 /* Expand a proxy command */
87 static char *
expand_proxy_command(const char * proxy_command,const char * user,const char * host,const char * host_arg,int port)88 expand_proxy_command(const char *proxy_command, const char *user,
89 const char *host, const char *host_arg, 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,
96 "h", host,
97 "n", host_arg,
98 "p", strport,
99 "r", options.user,
100 (char *)NULL);
101 free(tmp);
102 return ret;
103 }
104
105 static void
stderr_null(void)106 stderr_null(void)
107 {
108 int devnull;
109
110 if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
111 error("Can't open %s for stderr redirection: %s",
112 _PATH_DEVNULL, strerror(errno));
113 return;
114 }
115 if (devnull == STDERR_FILENO)
116 return;
117 if (dup2(devnull, STDERR_FILENO) == -1)
118 error("Cannot redirect stderr to %s", _PATH_DEVNULL);
119 if (devnull > STDERR_FILENO)
120 close(devnull);
121 }
122
123 /*
124 * Connect to the given ssh server using a proxy command that passes a
125 * a connected fd back to us.
126 */
127 static int
ssh_proxy_fdpass_connect(struct ssh * ssh,const char * host,const char * host_arg,u_short port,const char * proxy_command)128 ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
129 const char *host_arg, u_short port, const char *proxy_command)
130 {
131 char *command_string;
132 int sp[2], sock;
133 pid_t pid;
134 char *shell;
135
136 if ((shell = getenv("SHELL")) == NULL)
137 shell = _PATH_BSHELL;
138
139 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
140 fatal("Could not create socketpair to communicate with "
141 "proxy dialer: %.100s", strerror(errno));
142
143 command_string = expand_proxy_command(proxy_command, options.user,
144 host, host_arg, port);
145 debug("Executing proxy dialer command: %.500s", command_string);
146
147 /* Fork and execute the proxy command. */
148 if ((pid = fork()) == 0) {
149 char *argv[10];
150
151 close(sp[1]);
152 /* Redirect stdin and stdout. */
153 if (sp[0] != 0) {
154 if (dup2(sp[0], 0) == -1)
155 perror("dup2 stdin");
156 }
157 if (sp[0] != 1) {
158 if (dup2(sp[0], 1) == -1)
159 perror("dup2 stdout");
160 }
161 if (sp[0] >= 2)
162 close(sp[0]);
163
164 /*
165 * Stderr is left for non-ControlPersist connections is so
166 * error messages may be printed on the user's terminal.
167 */
168 if (!debug_flag && options.control_path != NULL &&
169 options.control_persist)
170 stderr_null();
171
172 argv[0] = shell;
173 argv[1] = "-c";
174 argv[2] = command_string;
175 argv[3] = NULL;
176
177 /*
178 * Execute the proxy command.
179 * Note that we gave up any extra privileges above.
180 */
181 execv(argv[0], argv);
182 perror(argv[0]);
183 exit(1);
184 }
185 /* Parent. */
186 if (pid == -1)
187 fatal("fork failed: %.100s", strerror(errno));
188 close(sp[0]);
189 free(command_string);
190
191 if ((sock = mm_receive_fd(sp[1])) == -1)
192 fatal("proxy dialer did not pass back a connection");
193 close(sp[1]);
194
195 while (waitpid(pid, NULL, 0) == -1)
196 if (errno != EINTR)
197 fatal("Couldn't wait for child: %s", strerror(errno));
198
199 /* Set the connection file descriptors. */
200 if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
201 return -1; /* ssh_packet_set_connection logs error */
202
203 return 0;
204 }
205
206 /*
207 * Connect to the given ssh server using a proxy command.
208 */
209 static int
ssh_proxy_connect(struct ssh * ssh,const char * host,const char * host_arg,u_short port,const char * proxy_command)210 ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
211 u_short port, const char *proxy_command)
212 {
213 char *command_string;
214 int pin[2], pout[2];
215 pid_t pid;
216 char *shell;
217
218 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
219 shell = _PATH_BSHELL;
220
221 /* Create pipes for communicating with the proxy. */
222 if (pipe(pin) == -1 || pipe(pout) == -1)
223 fatal("Could not create pipes to communicate with the proxy: %.100s",
224 strerror(errno));
225
226 command_string = expand_proxy_command(proxy_command, options.user,
227 host, host_arg, port);
228 debug("Executing proxy command: %.500s", command_string);
229
230 /* Fork and execute the proxy command. */
231 if ((pid = fork()) == 0) {
232 char *argv[10];
233
234 /* Redirect stdin and stdout. */
235 close(pin[1]);
236 if (pin[0] != 0) {
237 if (dup2(pin[0], 0) == -1)
238 perror("dup2 stdin");
239 close(pin[0]);
240 }
241 close(pout[0]);
242 if (dup2(pout[1], 1) == -1)
243 perror("dup2 stdout");
244 /* Cannot be 1 because pin allocated two descriptors. */
245 close(pout[1]);
246
247 /*
248 * Stderr is left for non-ControlPersist connections is so
249 * error messages may be printed on the user's terminal.
250 */
251 if (!debug_flag && options.control_path != NULL &&
252 options.control_persist)
253 stderr_null();
254
255 argv[0] = shell;
256 argv[1] = "-c";
257 argv[2] = command_string;
258 argv[3] = NULL;
259
260 /* Execute the proxy command. Note that we gave up any
261 extra privileges above. */
262 ssh_signal(SIGPIPE, SIG_DFL);
263 execv(argv[0], argv);
264 perror(argv[0]);
265 exit(1);
266 }
267 /* Parent. */
268 if (pid == -1)
269 fatal("fork failed: %.100s", strerror(errno));
270 else
271 proxy_command_pid = pid; /* save pid to clean up later */
272
273 /* Close child side of the descriptors. */
274 close(pin[0]);
275 close(pout[1]);
276
277 /* Free the command name. */
278 free(command_string);
279
280 /* Set the connection file descriptors. */
281 if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
282 return -1; /* ssh_packet_set_connection logs error */
283
284 return 0;
285 }
286
287 void
ssh_kill_proxy_command(void)288 ssh_kill_proxy_command(void)
289 {
290 /*
291 * Send SIGHUP to proxy command if used. We don't wait() in
292 * case it hangs and instead rely on init to reap the child
293 */
294 if (proxy_command_pid > 1)
295 kill(proxy_command_pid, SIGHUP);
296 }
297
298 #ifdef HAVE_IFADDRS_H
299 /*
300 * Search a interface address list (returned from getifaddrs(3)) for an
301 * address that matches the desired address family on the specified interface.
302 * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
303 */
304 static int
check_ifaddrs(const char * ifname,int af,const struct ifaddrs * ifaddrs,struct sockaddr_storage * resultp,socklen_t * rlenp)305 check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
306 struct sockaddr_storage *resultp, socklen_t *rlenp)
307 {
308 struct sockaddr_in6 *sa6;
309 struct sockaddr_in *sa;
310 struct in6_addr *v6addr;
311 const struct ifaddrs *ifa;
312 int allow_local;
313
314 /*
315 * Prefer addresses that are not loopback or linklocal, but use them
316 * if nothing else matches.
317 */
318 for (allow_local = 0; allow_local < 2; allow_local++) {
319 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
320 if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
321 (ifa->ifa_flags & IFF_UP) == 0 ||
322 ifa->ifa_addr->sa_family != af ||
323 strcmp(ifa->ifa_name, options.bind_interface) != 0)
324 continue;
325 switch (ifa->ifa_addr->sa_family) {
326 case AF_INET:
327 sa = (struct sockaddr_in *)ifa->ifa_addr;
328 if (!allow_local && sa->sin_addr.s_addr ==
329 htonl(INADDR_LOOPBACK))
330 continue;
331 if (*rlenp < sizeof(struct sockaddr_in)) {
332 error("%s: v4 addr doesn't fit",
333 __func__);
334 return -1;
335 }
336 *rlenp = sizeof(struct sockaddr_in);
337 memcpy(resultp, sa, *rlenp);
338 return 0;
339 case AF_INET6:
340 sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
341 v6addr = &sa6->sin6_addr;
342 if (!allow_local &&
343 (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
344 IN6_IS_ADDR_LOOPBACK(v6addr)))
345 continue;
346 if (*rlenp < sizeof(struct sockaddr_in6)) {
347 error("%s: v6 addr doesn't fit",
348 __func__);
349 return -1;
350 }
351 *rlenp = sizeof(struct sockaddr_in6);
352 memcpy(resultp, sa6, *rlenp);
353 return 0;
354 }
355 }
356 }
357 return -1;
358 }
359 #endif
360
361 /*
362 * Creates a socket for use as the ssh connection.
363 */
364 static int
ssh_create_socket(struct addrinfo * ai)365 ssh_create_socket(struct addrinfo *ai)
366 {
367 int sock, r;
368 struct sockaddr_storage bindaddr;
369 socklen_t bindaddrlen = 0;
370 struct addrinfo hints, *res = NULL;
371 #ifdef HAVE_IFADDRS_H
372 struct ifaddrs *ifaddrs = NULL;
373 #endif
374 char ntop[NI_MAXHOST];
375
376 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
377 if (sock == -1) {
378 error("socket: %s", strerror(errno));
379 return -1;
380 }
381 fcntl(sock, F_SETFD, FD_CLOEXEC);
382
383 /* Bind the socket to an alternative local IP address */
384 if (options.bind_address == NULL && options.bind_interface == NULL)
385 return sock;
386
387 if (options.bind_address != NULL) {
388 memset(&hints, 0, sizeof(hints));
389 hints.ai_family = ai->ai_family;
390 hints.ai_socktype = ai->ai_socktype;
391 hints.ai_protocol = ai->ai_protocol;
392 hints.ai_flags = AI_PASSIVE;
393 if ((r = getaddrinfo(options.bind_address, NULL,
394 &hints, &res)) != 0) {
395 error("getaddrinfo: %s: %s", options.bind_address,
396 ssh_gai_strerror(r));
397 goto fail;
398 }
399 if (res == NULL) {
400 error("getaddrinfo: no addrs");
401 goto fail;
402 }
403 memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
404 bindaddrlen = res->ai_addrlen;
405 } else if (options.bind_interface != NULL) {
406 #ifdef HAVE_IFADDRS_H
407 if ((r = getifaddrs(&ifaddrs)) != 0) {
408 error("getifaddrs: %s: %s", options.bind_interface,
409 strerror(errno));
410 goto fail;
411 }
412 bindaddrlen = sizeof(bindaddr);
413 if (check_ifaddrs(options.bind_interface, ai->ai_family,
414 ifaddrs, &bindaddr, &bindaddrlen) != 0) {
415 logit("getifaddrs: %s: no suitable addresses",
416 options.bind_interface);
417 goto fail;
418 }
419 #else
420 error("BindInterface not supported on this platform.");
421 #endif
422 }
423 if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
424 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
425 error("%s: getnameinfo failed: %s", __func__,
426 ssh_gai_strerror(r));
427 goto fail;
428 }
429 if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
430 error("bind %s: %s", ntop, strerror(errno));
431 goto fail;
432 }
433 debug("%s: bound to %s", __func__, ntop);
434 /* success */
435 goto out;
436 fail:
437 close(sock);
438 sock = -1;
439 out:
440 if (res != NULL)
441 freeaddrinfo(res);
442 #ifdef HAVE_IFADDRS_H
443 if (ifaddrs != NULL)
444 freeifaddrs(ifaddrs);
445 #endif
446 return sock;
447 }
448
449 /*
450 * Opens a TCP/IP connection to the remote server on the given host.
451 * The address of the remote host will be returned in hostaddr.
452 * If port is 0, the default port will be used.
453 * Connection_attempts specifies the maximum number of tries (one per
454 * second). If proxy_command is non-NULL, it specifies the command (with %h
455 * and %p substituted for host and port, respectively) to use to contact
456 * the daemon.
457 */
458 static int
ssh_connect_direct(struct ssh * ssh,const char * host,struct addrinfo * aitop,struct sockaddr_storage * hostaddr,u_short port,int family,int connection_attempts,int * timeout_ms,int want_keepalive)459 ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
460 struct sockaddr_storage *hostaddr, u_short port, int family,
461 int connection_attempts, int *timeout_ms, int want_keepalive)
462 {
463 int on = 1, saved_timeout_ms = *timeout_ms;
464 int oerrno, sock = -1, attempt;
465 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
466 struct addrinfo *ai;
467
468 debug2("%s", __func__);
469 memset(ntop, 0, sizeof(ntop));
470 memset(strport, 0, sizeof(strport));
471
472 for (attempt = 0; attempt < connection_attempts; attempt++) {
473 if (attempt > 0) {
474 /* Sleep a moment before retrying. */
475 sleep(1);
476 debug("Trying again...");
477 }
478 /*
479 * Loop through addresses for this host, and try each one in
480 * sequence until the connection succeeds.
481 */
482 for (ai = aitop; ai; ai = ai->ai_next) {
483 if (ai->ai_family != AF_INET &&
484 ai->ai_family != AF_INET6) {
485 errno = EAFNOSUPPORT;
486 continue;
487 }
488 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
489 ntop, sizeof(ntop), strport, sizeof(strport),
490 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
491 oerrno = errno;
492 error("%s: getnameinfo failed", __func__);
493 errno = oerrno;
494 continue;
495 }
496 debug("Connecting to %.200s [%.100s] port %s.",
497 host, ntop, strport);
498
499 /* Create a socket for connecting. */
500 sock = ssh_create_socket(ai);
501 if (sock < 0) {
502 /* Any error is already output */
503 errno = 0;
504 continue;
505 }
506
507 *timeout_ms = saved_timeout_ms;
508 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
509 timeout_ms) >= 0) {
510 /* Successful connection. */
511 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
512 break;
513 } else {
514 oerrno = errno;
515 debug("connect to address %s port %s: %s",
516 ntop, strport, strerror(errno));
517 close(sock);
518 sock = -1;
519 errno = oerrno;
520 }
521 }
522 if (sock != -1)
523 break; /* Successful connection. */
524 }
525
526 /* Return failure if we didn't get a successful connection. */
527 if (sock == -1) {
528 error("ssh: connect to host %s port %s: %s",
529 host, strport, errno == 0 ? "failure" : strerror(errno));
530 return -1;
531 }
532
533 debug("Connection established.");
534
535 /* Set SO_KEEPALIVE if requested. */
536 if (want_keepalive &&
537 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
538 sizeof(on)) == -1)
539 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
540
541 /* Set the connection. */
542 if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
543 return -1; /* ssh_packet_set_connection logs error */
544
545 return 0;
546 }
547
548 int
ssh_connect(struct ssh * ssh,const char * host,const char * host_arg,struct addrinfo * addrs,struct sockaddr_storage * hostaddr,u_short port,int family,int connection_attempts,int * timeout_ms,int want_keepalive)549 ssh_connect(struct ssh *ssh, const char *host, const char *host_arg,
550 struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port,
551 int family, int connection_attempts, int *timeout_ms, int want_keepalive)
552 {
553 int in, out;
554
555 if (options.proxy_command == NULL) {
556 return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
557 family, connection_attempts, timeout_ms, want_keepalive);
558 } else if (strcmp(options.proxy_command, "-") == 0) {
559 if ((in = dup(STDIN_FILENO)) == -1 ||
560 (out = dup(STDOUT_FILENO)) == -1) {
561 if (in >= 0)
562 close(in);
563 error("%s: dup() in/out failed", __func__);
564 return -1; /* ssh_packet_set_connection logs error */
565 }
566 if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
567 return -1; /* ssh_packet_set_connection logs error */
568 return 0;
569 } else if (options.proxy_use_fdpass) {
570 return ssh_proxy_fdpass_connect(ssh, host, host_arg, port,
571 options.proxy_command);
572 }
573 return ssh_proxy_connect(ssh, host, host_arg, port,
574 options.proxy_command);
575 }
576
577 /* defaults to 'no' */
578 static int
confirm(const char * prompt,const char * fingerprint)579 confirm(const char *prompt, const char *fingerprint)
580 {
581 const char *msg, *again = "Please type 'yes' or 'no': ";
582 const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
583 char *p, *cp;
584 int ret = -1;
585
586 if (options.batch_mode)
587 return 0;
588 for (msg = prompt;;msg = fingerprint ? again_fp : again) {
589 cp = p = read_passphrase(msg, RP_ECHO);
590 if (p == NULL)
591 return 0;
592 p += strspn(p, " \t"); /* skip leading whitespace */
593 p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */
594 if (p[0] == '\0' || strcasecmp(p, "no") == 0)
595 ret = 0;
596 else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
597 strcasecmp(p, fingerprint) == 0))
598 ret = 1;
599 free(cp);
600 if (ret != -1)
601 return ret;
602 }
603 }
604
605 static int
check_host_cert(const char * host,const struct sshkey * key)606 check_host_cert(const char *host, const struct sshkey *key)
607 {
608 const char *reason;
609 int r;
610
611 if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
612 error("%s", reason);
613 return 0;
614 }
615 if (sshbuf_len(key->cert->critical) != 0) {
616 error("Certificate for %s contains unsupported "
617 "critical options(s)", host);
618 return 0;
619 }
620 if ((r = sshkey_check_cert_sigtype(key,
621 options.ca_sign_algorithms)) != 0) {
622 logit("%s: certificate signature algorithm %s: %s", __func__,
623 (key->cert == NULL || key->cert->signature_type == NULL) ?
624 "(null)" : key->cert->signature_type, ssh_err(r));
625 return 0;
626 }
627
628 return 1;
629 }
630
631 static int
sockaddr_is_local(struct sockaddr * hostaddr)632 sockaddr_is_local(struct sockaddr *hostaddr)
633 {
634 switch (hostaddr->sa_family) {
635 case AF_INET:
636 return (ntohl(((struct sockaddr_in *)hostaddr)->
637 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
638 case AF_INET6:
639 return IN6_IS_ADDR_LOOPBACK(
640 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
641 default:
642 return 0;
643 }
644 }
645
646 /*
647 * Prepare the hostname and ip address strings that are used to lookup
648 * host keys in known_hosts files. These may have a port number appended.
649 */
650 void
get_hostfile_hostname_ipaddr(char * hostname,struct sockaddr * hostaddr,u_short port,char ** hostfile_hostname,char ** hostfile_ipaddr)651 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
652 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
653 {
654 char ntop[NI_MAXHOST];
655 socklen_t addrlen;
656
657 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
658 case -1:
659 addrlen = 0;
660 break;
661 case AF_INET:
662 addrlen = sizeof(struct sockaddr_in);
663 break;
664 case AF_INET6:
665 addrlen = sizeof(struct sockaddr_in6);
666 break;
667 default:
668 addrlen = sizeof(struct sockaddr);
669 break;
670 }
671
672 /*
673 * We don't have the remote ip-address for connections
674 * using a proxy command
675 */
676 if (hostfile_ipaddr != NULL) {
677 if (options.proxy_command == NULL) {
678 if (getnameinfo(hostaddr, addrlen,
679 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
680 fatal("%s: getnameinfo failed", __func__);
681 *hostfile_ipaddr = put_host_port(ntop, port);
682 } else {
683 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
684 "command>");
685 }
686 }
687
688 /*
689 * Allow the user to record the key under a different name or
690 * differentiate a non-standard port. This is useful for ssh
691 * tunneling over forwarded connections or if you run multiple
692 * sshd's on different ports on the same machine.
693 */
694 if (hostfile_hostname != NULL) {
695 if (options.host_key_alias != NULL) {
696 *hostfile_hostname = xstrdup(options.host_key_alias);
697 debug("using hostkeyalias: %s", *hostfile_hostname);
698 } else {
699 *hostfile_hostname = put_host_port(hostname, port);
700 }
701 }
702 }
703
704 /*
705 * check whether the supplied host key is valid, return -1 if the key
706 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
707 */
708 #define RDRW 0
709 #define RDONLY 1
710 #define ROQUIET 2
711 static int
check_host_key(char * hostname,struct sockaddr * hostaddr,u_short port,struct sshkey * host_key,int readonly,char ** user_hostfiles,u_int num_user_hostfiles,char ** system_hostfiles,u_int num_system_hostfiles)712 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
713 struct sshkey *host_key, int readonly,
714 char **user_hostfiles, u_int num_user_hostfiles,
715 char **system_hostfiles, u_int num_system_hostfiles)
716 {
717 HostStatus host_status;
718 HostStatus ip_status;
719 struct sshkey *raw_key = NULL;
720 char *ip = NULL, *host = NULL;
721 char hostline[1000], *hostp, *fp, *ra;
722 char msg[1024];
723 const char *type;
724 const struct hostkey_entry *host_found, *ip_found;
725 int len, cancelled_forwarding = 0, confirmed;
726 int local = sockaddr_is_local(hostaddr);
727 int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
728 int hostkey_trusted = 0; /* Known or explicitly accepted by user */
729 struct hostkeys *host_hostkeys, *ip_hostkeys;
730 u_int i;
731
732 /*
733 * Force accepting of the host key for loopback/localhost. The
734 * problem is that if the home directory is NFS-mounted to multiple
735 * machines, localhost will refer to a different machine in each of
736 * them, and the user will get bogus HOST_CHANGED warnings. This
737 * essentially disables host authentication for localhost; however,
738 * this is probably not a real problem.
739 */
740 if (options.no_host_authentication_for_localhost == 1 && local &&
741 options.host_key_alias == NULL) {
742 debug("Forcing accepting of host key for "
743 "loopback/localhost.");
744 return 0;
745 }
746
747 /*
748 * Prepare the hostname and address strings used for hostkey lookup.
749 * In some cases, these will have a port number appended.
750 */
751 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
752
753 /*
754 * Turn off check_host_ip if the connection is to localhost, via proxy
755 * command or if we don't have a hostname to compare with
756 */
757 if (options.check_host_ip && (local ||
758 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
759 options.check_host_ip = 0;
760
761 host_hostkeys = init_hostkeys();
762 for (i = 0; i < num_user_hostfiles; i++)
763 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
764 for (i = 0; i < num_system_hostfiles; i++)
765 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
766
767 ip_hostkeys = NULL;
768 if (!want_cert && options.check_host_ip) {
769 ip_hostkeys = init_hostkeys();
770 for (i = 0; i < num_user_hostfiles; i++)
771 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
772 for (i = 0; i < num_system_hostfiles; i++)
773 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
774 }
775
776 retry:
777 /* Reload these as they may have changed on cert->key downgrade */
778 want_cert = sshkey_is_cert(host_key);
779 type = sshkey_type(host_key);
780
781 /*
782 * Check if the host key is present in the user's list of known
783 * hosts or in the systemwide list.
784 */
785 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
786 &host_found);
787
788 /*
789 * Also perform check for the ip address, skip the check if we are
790 * localhost, looking for a certificate, or the hostname was an ip
791 * address to begin with.
792 */
793 if (!want_cert && ip_hostkeys != NULL) {
794 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
795 &ip_found);
796 if (host_status == HOST_CHANGED &&
797 (ip_status != HOST_CHANGED ||
798 (ip_found != NULL &&
799 !sshkey_equal(ip_found->key, host_found->key))))
800 host_ip_differ = 1;
801 } else
802 ip_status = host_status;
803
804 switch (host_status) {
805 case HOST_OK:
806 /* The host is known and the key matches. */
807 debug("Host '%.200s' is known and matches the %s host %s.",
808 host, type, want_cert ? "certificate" : "key");
809 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
810 host_found->file, host_found->line);
811 if (want_cert &&
812 !check_host_cert(options.host_key_alias == NULL ?
813 hostname : options.host_key_alias, host_key))
814 goto fail;
815 if (options.check_host_ip && ip_status == HOST_NEW) {
816 if (readonly || want_cert)
817 logit("%s host key for IP address "
818 "'%.128s' not in list of known hosts.",
819 type, ip);
820 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
821 host_key, options.hash_known_hosts))
822 logit("Failed to add the %s host key for IP "
823 "address '%.128s' to the list of known "
824 "hosts (%.500s).", type, ip,
825 user_hostfiles[0]);
826 else
827 logit("Warning: Permanently added the %s host "
828 "key for IP address '%.128s' to the list "
829 "of known hosts.", type, ip);
830 } else if (options.visual_host_key) {
831 fp = sshkey_fingerprint(host_key,
832 options.fingerprint_hash, SSH_FP_DEFAULT);
833 ra = sshkey_fingerprint(host_key,
834 options.fingerprint_hash, SSH_FP_RANDOMART);
835 if (fp == NULL || ra == NULL)
836 fatal("%s: sshkey_fingerprint fail", __func__);
837 logit("Host key fingerprint is %s\n%s", fp, ra);
838 free(ra);
839 free(fp);
840 }
841 hostkey_trusted = 1;
842 break;
843 case HOST_NEW:
844 if (options.host_key_alias == NULL && port != 0 &&
845 port != SSH_DEFAULT_PORT) {
846 debug("checking without port identifier");
847 if (check_host_key(hostname, hostaddr, 0, host_key,
848 ROQUIET, user_hostfiles, num_user_hostfiles,
849 system_hostfiles, num_system_hostfiles) == 0) {
850 debug("found matching key w/out port");
851 break;
852 }
853 }
854 if (readonly || want_cert)
855 goto fail;
856 /* The host is new. */
857 if (options.strict_host_key_checking ==
858 SSH_STRICT_HOSTKEY_YES) {
859 /*
860 * User has requested strict host key checking. We
861 * will not add the host key automatically. The only
862 * alternative left is to abort.
863 */
864 error("No %s host key is known for %.200s and you "
865 "have requested strict checking.", type, host);
866 goto fail;
867 } else if (options.strict_host_key_checking ==
868 SSH_STRICT_HOSTKEY_ASK) {
869 char msg1[1024], msg2[1024];
870
871 if (show_other_keys(host_hostkeys, host_key))
872 snprintf(msg1, sizeof(msg1),
873 "\nbut keys of different type are already"
874 " known for this host.");
875 else
876 snprintf(msg1, sizeof(msg1), ".");
877 /* The default */
878 fp = sshkey_fingerprint(host_key,
879 options.fingerprint_hash, SSH_FP_DEFAULT);
880 ra = sshkey_fingerprint(host_key,
881 options.fingerprint_hash, SSH_FP_RANDOMART);
882 if (fp == NULL || ra == NULL)
883 fatal("%s: sshkey_fingerprint fail", __func__);
884 msg2[0] = '\0';
885 if (options.verify_host_key_dns) {
886 if (matching_host_key_dns)
887 snprintf(msg2, sizeof(msg2),
888 "Matching host key fingerprint"
889 " found in DNS.\n");
890 else
891 snprintf(msg2, sizeof(msg2),
892 "No matching host key fingerprint"
893 " found in DNS.\n");
894 }
895 snprintf(msg, sizeof(msg),
896 "The authenticity of host '%.200s (%s)' can't be "
897 "established%s\n"
898 "%s key fingerprint is %s.%s%s\n%s"
899 "Are you sure you want to continue connecting "
900 "(yes/no/[fingerprint])? ",
901 host, ip, msg1, type, fp,
902 options.visual_host_key ? "\n" : "",
903 options.visual_host_key ? ra : "",
904 msg2);
905 free(ra);
906 confirmed = confirm(msg, fp);
907 free(fp);
908 if (!confirmed)
909 goto fail;
910 hostkey_trusted = 1; /* user explicitly confirmed */
911 }
912 /*
913 * If in "new" or "off" strict mode, add the key automatically
914 * to the local known_hosts file.
915 */
916 if (options.check_host_ip && ip_status == HOST_NEW) {
917 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
918 hostp = hostline;
919 if (options.hash_known_hosts) {
920 /* Add hash of host and IP separately */
921 r = add_host_to_hostfile(user_hostfiles[0],
922 host, host_key, options.hash_known_hosts) &&
923 add_host_to_hostfile(user_hostfiles[0], ip,
924 host_key, options.hash_known_hosts);
925 } else {
926 /* Add unhashed "host,ip" */
927 r = add_host_to_hostfile(user_hostfiles[0],
928 hostline, host_key,
929 options.hash_known_hosts);
930 }
931 } else {
932 r = add_host_to_hostfile(user_hostfiles[0], host,
933 host_key, options.hash_known_hosts);
934 hostp = host;
935 }
936
937 if (!r)
938 logit("Failed to add the host to the list of known "
939 "hosts (%.500s).", user_hostfiles[0]);
940 else
941 logit("Warning: Permanently added '%.200s' (%s) to the "
942 "list of known hosts.", hostp, type);
943 break;
944 case HOST_REVOKED:
945 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
946 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
947 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
948 error("The %s host key for %s is marked as revoked.", type, host);
949 error("This could mean that a stolen key is being used to");
950 error("impersonate this host.");
951
952 /*
953 * If strict host key checking is in use, the user will have
954 * to edit the key manually and we can only abort.
955 */
956 if (options.strict_host_key_checking !=
957 SSH_STRICT_HOSTKEY_OFF) {
958 error("%s host key for %.200s was revoked and you have "
959 "requested strict checking.", type, host);
960 goto fail;
961 }
962 goto continue_unsafe;
963
964 case HOST_CHANGED:
965 if (want_cert) {
966 /*
967 * This is only a debug() since it is valid to have
968 * CAs with wildcard DNS matches that don't match
969 * all hosts that one might visit.
970 */
971 debug("Host certificate authority does not "
972 "match %s in %s:%lu", CA_MARKER,
973 host_found->file, host_found->line);
974 goto fail;
975 }
976 if (readonly == ROQUIET)
977 goto fail;
978 if (options.check_host_ip && host_ip_differ) {
979 char *key_msg;
980 if (ip_status == HOST_NEW)
981 key_msg = "is unknown";
982 else if (ip_status == HOST_OK)
983 key_msg = "is unchanged";
984 else
985 key_msg = "has a different value";
986 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
987 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
988 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
989 error("The %s host key for %s has changed,", type, host);
990 error("and the key for the corresponding IP address %s", ip);
991 error("%s. This could either mean that", key_msg);
992 error("DNS SPOOFING is happening or the IP address for the host");
993 error("and its host key have changed at the same time.");
994 if (ip_status != HOST_NEW)
995 error("Offending key for IP in %s:%lu",
996 ip_found->file, ip_found->line);
997 }
998 /* The host key has changed. */
999 warn_changed_key(host_key);
1000 error("Add correct host key in %.100s to get rid of this message.",
1001 user_hostfiles[0]);
1002 error("Offending %s key in %s:%lu",
1003 sshkey_type(host_found->key),
1004 host_found->file, host_found->line);
1005
1006 /*
1007 * If strict host key checking is in use, the user will have
1008 * to edit the key manually and we can only abort.
1009 */
1010 if (options.strict_host_key_checking !=
1011 SSH_STRICT_HOSTKEY_OFF) {
1012 error("%s host key for %.200s has changed and you have "
1013 "requested strict checking.", type, host);
1014 goto fail;
1015 }
1016
1017 continue_unsafe:
1018 /*
1019 * If strict host key checking has not been requested, allow
1020 * the connection but without MITM-able authentication or
1021 * forwarding.
1022 */
1023 if (options.password_authentication) {
1024 error("Password authentication is disabled to avoid "
1025 "man-in-the-middle attacks.");
1026 options.password_authentication = 0;
1027 cancelled_forwarding = 1;
1028 }
1029 if (options.kbd_interactive_authentication) {
1030 error("Keyboard-interactive authentication is disabled"
1031 " to avoid man-in-the-middle attacks.");
1032 options.kbd_interactive_authentication = 0;
1033 options.challenge_response_authentication = 0;
1034 cancelled_forwarding = 1;
1035 }
1036 if (options.challenge_response_authentication) {
1037 error("Challenge/response authentication is disabled"
1038 " to avoid man-in-the-middle attacks.");
1039 options.challenge_response_authentication = 0;
1040 cancelled_forwarding = 1;
1041 }
1042 if (options.forward_agent) {
1043 error("Agent forwarding is disabled to avoid "
1044 "man-in-the-middle attacks.");
1045 options.forward_agent = 0;
1046 cancelled_forwarding = 1;
1047 }
1048 if (options.forward_x11) {
1049 error("X11 forwarding is disabled to avoid "
1050 "man-in-the-middle attacks.");
1051 options.forward_x11 = 0;
1052 cancelled_forwarding = 1;
1053 }
1054 if (options.num_local_forwards > 0 ||
1055 options.num_remote_forwards > 0) {
1056 error("Port forwarding is disabled to avoid "
1057 "man-in-the-middle attacks.");
1058 options.num_local_forwards =
1059 options.num_remote_forwards = 0;
1060 cancelled_forwarding = 1;
1061 }
1062 if (options.tun_open != SSH_TUNMODE_NO) {
1063 error("Tunnel forwarding is disabled to avoid "
1064 "man-in-the-middle attacks.");
1065 options.tun_open = SSH_TUNMODE_NO;
1066 cancelled_forwarding = 1;
1067 }
1068 if (options.exit_on_forward_failure && cancelled_forwarding)
1069 fatal("Error: forwarding disabled due to host key "
1070 "check failure");
1071
1072 /*
1073 * XXX Should permit the user to change to use the new id.
1074 * This could be done by converting the host key to an
1075 * identifying sentence, tell that the host identifies itself
1076 * by that sentence, and ask the user if he/she wishes to
1077 * accept the authentication.
1078 */
1079 break;
1080 case HOST_FOUND:
1081 fatal("internal error");
1082 break;
1083 }
1084
1085 if (options.check_host_ip && host_status != HOST_CHANGED &&
1086 ip_status == HOST_CHANGED) {
1087 snprintf(msg, sizeof(msg),
1088 "Warning: the %s host key for '%.200s' "
1089 "differs from the key for the IP address '%.128s'"
1090 "\nOffending key for IP in %s:%lu",
1091 type, host, ip, ip_found->file, ip_found->line);
1092 if (host_status == HOST_OK) {
1093 len = strlen(msg);
1094 snprintf(msg + len, sizeof(msg) - len,
1095 "\nMatching host key in %s:%lu",
1096 host_found->file, host_found->line);
1097 }
1098 if (options.strict_host_key_checking ==
1099 SSH_STRICT_HOSTKEY_ASK) {
1100 strlcat(msg, "\nAre you sure you want "
1101 "to continue connecting (yes/no)? ", sizeof(msg));
1102 if (!confirm(msg, NULL))
1103 goto fail;
1104 } else if (options.strict_host_key_checking !=
1105 SSH_STRICT_HOSTKEY_OFF) {
1106 logit("%s", msg);
1107 error("Exiting, you have requested strict checking.");
1108 goto fail;
1109 } else {
1110 logit("%s", msg);
1111 }
1112 }
1113
1114 if (!hostkey_trusted && options.update_hostkeys) {
1115 debug("%s: hostkey not known or explicitly trusted: "
1116 "disabling UpdateHostkeys", __func__);
1117 options.update_hostkeys = 0;
1118 }
1119
1120 free(ip);
1121 free(host);
1122 if (host_hostkeys != NULL)
1123 free_hostkeys(host_hostkeys);
1124 if (ip_hostkeys != NULL)
1125 free_hostkeys(ip_hostkeys);
1126 return 0;
1127
1128 fail:
1129 if (want_cert && host_status != HOST_REVOKED) {
1130 /*
1131 * No matching certificate. Downgrade cert to raw key and
1132 * search normally.
1133 */
1134 debug("No matching CA found. Retry with plain key");
1135 if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1136 fatal("%s: sshkey_from_private: %s",
1137 __func__, ssh_err(r));
1138 if ((r = sshkey_drop_cert(raw_key)) != 0)
1139 fatal("Couldn't drop certificate: %s", ssh_err(r));
1140 host_key = raw_key;
1141 goto retry;
1142 }
1143 sshkey_free(raw_key);
1144 free(ip);
1145 free(host);
1146 if (host_hostkeys != NULL)
1147 free_hostkeys(host_hostkeys);
1148 if (ip_hostkeys != NULL)
1149 free_hostkeys(ip_hostkeys);
1150 return -1;
1151 }
1152
1153 /* returns 0 if key verifies or -1 if key does NOT verify */
1154 int
verify_host_key(char * host,struct sockaddr * hostaddr,struct sshkey * host_key)1155 verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1156 {
1157 u_int i;
1158 int r = -1, flags = 0;
1159 char valid[64], *fp = NULL, *cafp = NULL;
1160 struct sshkey *plain = NULL;
1161
1162 if ((fp = sshkey_fingerprint(host_key,
1163 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1164 error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1165 r = -1;
1166 goto out;
1167 }
1168
1169 if (sshkey_is_cert(host_key)) {
1170 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1171 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1172 error("%s: fingerprint CA key: %s",
1173 __func__, ssh_err(r));
1174 r = -1;
1175 goto out;
1176 }
1177 sshkey_format_cert_validity(host_key->cert,
1178 valid, sizeof(valid));
1179 debug("Server host certificate: %s %s, serial %llu "
1180 "ID \"%s\" CA %s %s valid %s",
1181 sshkey_ssh_name(host_key), fp,
1182 (unsigned long long)host_key->cert->serial,
1183 host_key->cert->key_id,
1184 sshkey_ssh_name(host_key->cert->signature_key), cafp,
1185 valid);
1186 for (i = 0; i < host_key->cert->nprincipals; i++) {
1187 debug2("Server host certificate hostname: %s",
1188 host_key->cert->principals[i]);
1189 }
1190 } else {
1191 debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1192 }
1193
1194 if (sshkey_equal(previous_host_key, host_key)) {
1195 debug2("%s: server host key %s %s matches cached key",
1196 __func__, sshkey_type(host_key), fp);
1197 r = 0;
1198 goto out;
1199 }
1200
1201 /* Check in RevokedHostKeys file if specified */
1202 if (options.revoked_host_keys != NULL) {
1203 r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1204 switch (r) {
1205 case 0:
1206 break; /* not revoked */
1207 case SSH_ERR_KEY_REVOKED:
1208 error("Host key %s %s revoked by file %s",
1209 sshkey_type(host_key), fp,
1210 options.revoked_host_keys);
1211 r = -1;
1212 goto out;
1213 default:
1214 error("Error checking host key %s %s in "
1215 "revoked keys file %s: %s", sshkey_type(host_key),
1216 fp, options.revoked_host_keys, ssh_err(r));
1217 r = -1;
1218 goto out;
1219 }
1220 }
1221
1222 if (options.verify_host_key_dns) {
1223 /*
1224 * XXX certs are not yet supported for DNS, so downgrade
1225 * them and try the plain key.
1226 */
1227 if ((r = sshkey_from_private(host_key, &plain)) != 0)
1228 goto out;
1229 if (sshkey_is_cert(plain))
1230 sshkey_drop_cert(plain);
1231 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1232 if (flags & DNS_VERIFY_FOUND) {
1233 if (options.verify_host_key_dns == 1 &&
1234 flags & DNS_VERIFY_MATCH &&
1235 flags & DNS_VERIFY_SECURE) {
1236 r = 0;
1237 goto out;
1238 }
1239 if (flags & DNS_VERIFY_MATCH) {
1240 matching_host_key_dns = 1;
1241 } else {
1242 warn_changed_key(plain);
1243 error("Update the SSHFP RR in DNS "
1244 "with the new host key to get rid "
1245 "of this message.");
1246 }
1247 }
1248 }
1249 }
1250 r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1251 options.user_hostfiles, options.num_user_hostfiles,
1252 options.system_hostfiles, options.num_system_hostfiles);
1253
1254 out:
1255 sshkey_free(plain);
1256 free(fp);
1257 free(cafp);
1258 if (r == 0 && host_key != NULL) {
1259 sshkey_free(previous_host_key);
1260 r = sshkey_from_private(host_key, &previous_host_key);
1261 }
1262
1263 return r;
1264 }
1265
1266 /*
1267 * Starts a dialog with the server, and authenticates the current user on the
1268 * server. This does not need any extra privileges. The basic connection
1269 * to the server must already have been established before this is called.
1270 * If login fails, this function prints an error and never returns.
1271 * This function does not require super-user privileges.
1272 */
1273 void
ssh_login(struct ssh * ssh,Sensitive * sensitive,const char * orighost,struct sockaddr * hostaddr,u_short port,struct passwd * pw,int timeout_ms)1274 ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1275 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1276 {
1277 char *host;
1278 char *server_user, *local_user;
1279 int r;
1280
1281 local_user = xstrdup(pw->pw_name);
1282 server_user = options.user ? options.user : local_user;
1283
1284 /* Convert the user-supplied hostname into all lowercase. */
1285 host = xstrdup(orighost);
1286 lowercase(host);
1287
1288 /* Exchange protocol version identification strings with the server. */
1289 if ((r = kex_exchange_identification(ssh, timeout_ms, NULL)) != 0)
1290 sshpkt_fatal(ssh, r, "banner exchange");
1291
1292 /* Put the connection into non-blocking mode. */
1293 ssh_packet_set_nonblocking(ssh);
1294
1295 /* key exchange */
1296 /* authenticate user */
1297 debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1298 ssh_kex2(ssh, host, hostaddr, port);
1299 ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1300 free(local_user);
1301 free(host);
1302 }
1303
1304 /* print all known host keys for a given host, but skip keys of given type */
1305 static int
show_other_keys(struct hostkeys * hostkeys,struct sshkey * key)1306 show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1307 {
1308 int type[] = {
1309 KEY_RSA,
1310 KEY_DSA,
1311 KEY_ECDSA,
1312 KEY_ED25519,
1313 KEY_XMSS,
1314 -1
1315 };
1316 int i, ret = 0;
1317 char *fp, *ra;
1318 const struct hostkey_entry *found;
1319
1320 for (i = 0; type[i] != -1; i++) {
1321 if (type[i] == key->type)
1322 continue;
1323 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1324 continue;
1325 fp = sshkey_fingerprint(found->key,
1326 options.fingerprint_hash, SSH_FP_DEFAULT);
1327 ra = sshkey_fingerprint(found->key,
1328 options.fingerprint_hash, SSH_FP_RANDOMART);
1329 if (fp == NULL || ra == NULL)
1330 fatal("%s: sshkey_fingerprint fail", __func__);
1331 logit("WARNING: %s key found for host %s\n"
1332 "in %s:%lu\n"
1333 "%s key fingerprint %s.",
1334 sshkey_type(found->key),
1335 found->host, found->file, found->line,
1336 sshkey_type(found->key), fp);
1337 if (options.visual_host_key)
1338 logit("%s", ra);
1339 free(ra);
1340 free(fp);
1341 ret = 1;
1342 }
1343 return ret;
1344 }
1345
1346 static void
warn_changed_key(struct sshkey * host_key)1347 warn_changed_key(struct sshkey *host_key)
1348 {
1349 char *fp;
1350
1351 fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1352 SSH_FP_DEFAULT);
1353 if (fp == NULL)
1354 fatal("%s: sshkey_fingerprint fail", __func__);
1355
1356 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1357 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1358 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1359 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1360 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1361 error("It is also possible that a host key has just been changed.");
1362 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1363 sshkey_type(host_key), fp);
1364 error("Please contact your system administrator.");
1365
1366 free(fp);
1367 }
1368
1369 /*
1370 * Execute a local command
1371 */
1372 int
ssh_local_cmd(const char * args)1373 ssh_local_cmd(const char *args)
1374 {
1375 char *shell;
1376 pid_t pid;
1377 int status;
1378 void (*osighand)(int);
1379
1380 if (!options.permit_local_command ||
1381 args == NULL || !*args)
1382 return (1);
1383
1384 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1385 shell = _PATH_BSHELL;
1386
1387 osighand = ssh_signal(SIGCHLD, SIG_DFL);
1388 pid = fork();
1389 if (pid == 0) {
1390 ssh_signal(SIGPIPE, SIG_DFL);
1391 debug3("Executing %s -c \"%s\"", shell, args);
1392 execl(shell, shell, "-c", args, (char *)NULL);
1393 error("Couldn't execute %s -c \"%s\": %s",
1394 shell, args, strerror(errno));
1395 _exit(1);
1396 } else if (pid == -1)
1397 fatal("fork failed: %.100s", strerror(errno));
1398 while (waitpid(pid, &status, 0) == -1)
1399 if (errno != EINTR)
1400 fatal("Couldn't wait for child: %s", strerror(errno));
1401 ssh_signal(SIGCHLD, osighand);
1402
1403 if (!WIFEXITED(status))
1404 return (1);
1405
1406 return (WEXITSTATUS(status));
1407 }
1408
1409 void
maybe_add_key_to_agent(const char * authfile,struct sshkey * private,const char * comment,const char * passphrase)1410 maybe_add_key_to_agent(const char *authfile, struct sshkey *private,
1411 const char *comment, const char *passphrase)
1412 {
1413 int auth_sock = -1, r;
1414 const char *skprovider = NULL;
1415
1416 if (options.add_keys_to_agent == 0)
1417 return;
1418
1419 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1420 debug3("no authentication agent, not adding key");
1421 return;
1422 }
1423
1424 if (options.add_keys_to_agent == 2 &&
1425 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1426 debug3("user denied adding this key");
1427 close(auth_sock);
1428 return;
1429 }
1430 if (sshkey_is_sk(private))
1431 skprovider = options.sk_provider;
1432 if ((r = ssh_add_identity_constrained(auth_sock, private,
1433 comment == NULL ? authfile : comment, 0,
1434 (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1435 debug("identity added to agent: %s", authfile);
1436 else
1437 debug("could not add identity to agent: %s (%d)", authfile, r);
1438 close(auth_sock);
1439 }
1440