1 /* $OpenBSD: sshconnect.c,v 1.246 2014/02/06 22:21:01 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
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".
18 #include <sys/types.h>
21 #include <sys/socket.h>
22 #ifdef HAVE_SYS_TIME_H
23 # include <sys/time.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
54 #include "sshconnect.h"
62 #include "monitor_fdpass.h"
66 char *client_version_string = NULL;
67 char *server_version_string = NULL;
69 static int matching_host_key_dns = 0;
71 static pid_t proxy_command_pid = 0;
74 extern Options options;
75 extern char *__progname;
76 extern uid_t original_real_uid;
77 extern uid_t original_effective_uid;
79 static int show_other_keys(struct hostkeys *, Key *);
80 static void warn_changed_key(Key *);
82 /* Expand a proxy command */
84 expand_proxy_command(const char *proxy_command, const char *user,
85 const char *host, int port)
87 char *tmp, *ret, strport[NI_MAXSERV];
89 snprintf(strport, sizeof strport, "%d", port);
90 xasprintf(&tmp, "exec %s", proxy_command);
91 ret = percent_expand(tmp, "h", host, "p", strport,
92 "r", options.user, (char *)NULL);
98 * Connect to the given ssh server using a proxy command that passes a
99 * a connected fd back to us.
102 ssh_proxy_fdpass_connect(const char *host, u_short port,
103 const char *proxy_command)
105 char *command_string;
110 if ((shell = getenv("SHELL")) == NULL)
111 shell = _PATH_BSHELL;
113 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
114 fatal("Could not create socketpair to communicate with "
115 "proxy dialer: %.100s", strerror(errno));
117 command_string = expand_proxy_command(proxy_command, options.user,
119 debug("Executing proxy dialer command: %.500s", command_string);
121 /* Fork and execute the proxy command. */
122 if ((pid = fork()) == 0) {
125 /* Child. Permanently give up superuser privileges. */
126 permanently_drop_suid(original_real_uid);
129 /* Redirect stdin and stdout. */
131 if (dup2(sp[0], 0) < 0)
132 perror("dup2 stdin");
135 if (dup2(sp[0], 1) < 0)
136 perror("dup2 stdout");
142 * Stderr is left as it is so that error messages get
143 * printed on the user's terminal.
147 argv[2] = command_string;
151 * Execute the proxy command.
152 * Note that we gave up any extra privileges above.
154 execv(argv[0], argv);
160 fatal("fork failed: %.100s", strerror(errno));
162 free(command_string);
164 if ((sock = mm_receive_fd(sp[1])) == -1)
165 fatal("proxy dialer did not pass back a connection");
167 while (waitpid(pid, NULL, 0) == -1)
169 fatal("Couldn't wait for child: %s", strerror(errno));
171 /* Set the connection file descriptors. */
172 packet_set_connection(sock, sock);
178 * Connect to the given ssh server using a proxy command.
181 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
183 char *command_string;
188 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
189 shell = _PATH_BSHELL;
191 /* Create pipes for communicating with the proxy. */
192 if (pipe(pin) < 0 || pipe(pout) < 0)
193 fatal("Could not create pipes to communicate with the proxy: %.100s",
196 command_string = expand_proxy_command(proxy_command, options.user,
198 debug("Executing proxy command: %.500s", command_string);
200 /* Fork and execute the proxy command. */
201 if ((pid = fork()) == 0) {
204 /* Child. Permanently give up superuser privileges. */
205 permanently_drop_suid(original_real_uid);
207 /* Redirect stdin and stdout. */
210 if (dup2(pin[0], 0) < 0)
211 perror("dup2 stdin");
215 if (dup2(pout[1], 1) < 0)
216 perror("dup2 stdout");
217 /* Cannot be 1 because pin allocated two descriptors. */
220 /* Stderr is left as it is so that error messages get
221 printed on the user's terminal. */
224 argv[2] = command_string;
227 /* Execute the proxy command. Note that we gave up any
228 extra privileges above. */
229 signal(SIGPIPE, SIG_DFL);
230 execv(argv[0], argv);
236 fatal("fork failed: %.100s", strerror(errno));
238 proxy_command_pid = pid; /* save pid to clean up later */
240 /* Close child side of the descriptors. */
244 /* Free the command name. */
245 free(command_string);
247 /* Set the connection file descriptors. */
248 packet_set_connection(pout[0], pin[1]);
250 /* Indicate OK return */
255 ssh_kill_proxy_command(void)
258 * Send SIGHUP to proxy command if used. We don't wait() in
259 * case it hangs and instead rely on init to reap the child
261 if (proxy_command_pid > 1)
262 kill(proxy_command_pid, SIGHUP);
266 * Creates a (possibly privileged) socket for use as the ssh connection.
269 ssh_create_socket(int privileged, struct addrinfo *ai)
272 struct addrinfo hints, *res = NULL;
274 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
276 error("socket: %s", strerror(errno));
279 fcntl(sock, F_SETFD, FD_CLOEXEC);
281 /* Bind the socket to an alternative local IP address */
282 if (options.bind_address == NULL && !privileged)
285 if (options.bind_address) {
286 memset(&hints, 0, sizeof(hints));
287 hints.ai_family = ai->ai_family;
288 hints.ai_socktype = ai->ai_socktype;
289 hints.ai_protocol = ai->ai_protocol;
290 hints.ai_flags = AI_PASSIVE;
291 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
293 error("getaddrinfo: %s: %s", options.bind_address,
294 ssh_gai_strerror(gaierr));
300 * If we are running as root and want to connect to a privileged
301 * port, bind our own socket to a privileged port.
305 r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
308 error("bindresvport_sa: af=%d %s", ai->ai_family,
313 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
314 error("bind: %s: %s", options.bind_address,
328 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
329 socklen_t addrlen, int *timeoutp)
332 struct timeval tv, t_start;
334 int optval, rc, result = -1;
336 gettimeofday(&t_start, NULL);
338 if (*timeoutp <= 0) {
339 result = connect(sockfd, serv_addr, addrlen);
343 set_nonblock(sockfd);
344 rc = connect(sockfd, serv_addr, addrlen);
346 unset_nonblock(sockfd);
350 if (errno != EINPROGRESS) {
355 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
357 FD_SET(sockfd, fdset);
358 ms_to_timeval(&tv, *timeoutp);
361 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
362 if (rc != -1 || errno != EINTR)
373 debug("select: %s", strerror(errno));
376 /* Completed or failed */
378 optlen = sizeof(optval);
379 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
381 debug("getsockopt: %s", strerror(errno));
389 unset_nonblock(sockfd);
392 /* Should not occur */
393 fatal("Bogus return (%d) from select()", rc);
399 if (result == 0 && *timeoutp > 0) {
400 ms_subtract_diff(&t_start, timeoutp);
401 if (*timeoutp <= 0) {
411 * Opens a TCP/IP connection to the remote server on the given host.
412 * The address of the remote host will be returned in hostaddr.
413 * If port is 0, the default port will be used. If needpriv is true,
414 * a privileged port will be allocated to make the connection.
415 * This requires super-user privileges if needpriv is true.
416 * Connection_attempts specifies the maximum number of tries (one per
417 * second). If proxy_command is non-NULL, it specifies the command (with %h
418 * and %p substituted for host and port, respectively) to use to contact
422 ssh_connect_direct(const char *host, struct addrinfo *aitop,
423 struct sockaddr_storage *hostaddr, u_short port, int family,
424 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
427 int sock = -1, attempt;
428 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
431 debug2("ssh_connect: needpriv %d", needpriv);
433 for (attempt = 0; attempt < connection_attempts; attempt++) {
435 /* Sleep a moment before retrying. */
437 debug("Trying again...");
440 * Loop through addresses for this host, and try each one in
441 * sequence until the connection succeeds.
443 for (ai = aitop; ai; ai = ai->ai_next) {
444 if (ai->ai_family != AF_INET &&
445 ai->ai_family != AF_INET6)
447 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
448 ntop, sizeof(ntop), strport, sizeof(strport),
449 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
450 error("ssh_connect: getnameinfo failed");
453 debug("Connecting to %.200s [%.100s] port %s.",
454 host, ntop, strport);
456 /* Create a socket for connecting. */
457 sock = ssh_create_socket(needpriv, ai);
459 /* Any error is already output */
462 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
464 /* Successful connection. */
465 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
468 debug("connect to address %s port %s: %s",
469 ntop, strport, strerror(errno));
475 break; /* Successful connection. */
478 /* Return failure if we didn't get a successful connection. */
480 error("ssh: connect to host %s port %s: %s",
481 host, strport, strerror(errno));
485 debug("Connection established.");
487 /* Set SO_KEEPALIVE if requested. */
488 if (want_keepalive &&
489 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
491 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
493 /* Set the connection. */
494 packet_set_connection(sock, sock);
500 ssh_connect(const char *host, struct addrinfo *addrs,
501 struct sockaddr_storage *hostaddr, u_short port, int family,
502 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
504 if (options.proxy_command == NULL) {
505 return ssh_connect_direct(host, addrs, hostaddr, port, family,
506 connection_attempts, timeout_ms, want_keepalive, needpriv);
507 } else if (strcmp(options.proxy_command, "-") == 0) {
508 packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
509 return 0; /* Always succeeds */
510 } else if (options.proxy_use_fdpass) {
511 return ssh_proxy_fdpass_connect(host, port,
512 options.proxy_command);
514 return ssh_proxy_connect(host, port, options.proxy_command);
518 send_client_banner(int connection_out, int minor1)
520 /* Send our own protocol version identification. */
522 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
523 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
525 xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
526 PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
528 if (roaming_atomicio(vwrite, connection_out, client_version_string,
529 strlen(client_version_string)) != strlen(client_version_string))
530 fatal("write: %.100s", strerror(errno));
531 chop(client_version_string);
532 debug("Local version string %.100s", client_version_string);
536 * Waits for the server identification string, and sends our own
537 * identification string.
540 ssh_exchange_identification(int timeout_ms)
542 char buf[256], remote_version[256]; /* must be same size! */
543 int remote_major, remote_minor, mismatch;
544 int connection_in = packet_get_connection_in();
545 int connection_out = packet_get_connection_out();
546 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
549 int fdsetsz, remaining, rc;
550 struct timeval t_start, t_remaining;
553 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
554 fdset = xcalloc(1, fdsetsz);
557 * If we are SSH2-only then we can send the banner immediately and
560 if (options.protocol == SSH_PROTO_2) {
562 send_client_banner(connection_out, 0);
563 client_banner_sent = 1;
566 /* Read other side's version identification. */
567 remaining = timeout_ms;
569 for (i = 0; i < sizeof(buf) - 1; i++) {
570 if (timeout_ms > 0) {
571 gettimeofday(&t_start, NULL);
572 ms_to_timeval(&t_remaining, remaining);
573 FD_SET(connection_in, fdset);
574 rc = select(connection_in + 1, fdset, NULL,
575 fdset, &t_remaining);
576 ms_subtract_diff(&t_start, &remaining);
577 if (rc == 0 || remaining <= 0)
578 fatal("Connection timed out during "
583 fatal("ssh_exchange_identification: "
584 "select: %s", strerror(errno));
588 len = roaming_atomicio(read, connection_in, &buf[i], 1);
590 if (len != 1 && errno == EPIPE)
591 fatal("ssh_exchange_identification: "
592 "Connection closed by remote host");
594 fatal("ssh_exchange_identification: "
595 "read: %.100s", strerror(errno));
596 if (buf[i] == '\r') {
599 continue; /**XXX wait for \n */
601 if (buf[i] == '\n') {
606 fatal("ssh_exchange_identification: "
607 "No banner received");
609 buf[sizeof(buf) - 1] = 0;
610 if (strncmp(buf, "SSH-", 4) == 0)
612 debug("ssh_exchange_identification: %s", buf);
614 server_version_string = xstrdup(buf);
618 * Check that the versions match. In future this might accept
619 * several versions and set appropriate flags to handle them.
621 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
622 &remote_major, &remote_minor, remote_version) != 3)
623 fatal("Bad remote protocol version identification: '%.100s'", buf);
624 debug("Remote protocol version %d.%d, remote software version %.100s",
625 remote_major, remote_minor, remote_version);
627 compat_datafellows(remote_version);
630 switch (remote_major) {
632 if (remote_minor == 99 &&
633 (options.protocol & SSH_PROTO_2) &&
634 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
638 if (!(options.protocol & SSH_PROTO_1)) {
642 if (remote_minor < 3) {
643 fatal("Remote machine has too old SSH software version.");
644 } else if (remote_minor == 3 || remote_minor == 4) {
645 /* We speak 1.3, too. */
648 if (options.forward_agent) {
649 logit("Agent forwarding disabled for protocol 1.3");
650 options.forward_agent = 0;
655 if (options.protocol & SSH_PROTO_2) {
665 fatal("Protocol major versions differ: %d vs. %d",
666 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
668 if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
669 fatal("Server version \"%.100s\" uses unsafe key agreement; "
670 "refusing connection", remote_version);
671 if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
672 logit("Server version \"%.100s\" uses unsafe RSA signature "
673 "scheme; disabling use of RSA keys", remote_version);
674 if (!client_banner_sent)
675 send_client_banner(connection_out, minor1);
676 chop(server_version_string);
679 /* defaults to 'no' */
681 confirm(const char *prompt)
683 const char *msg, *again = "Please type 'yes' or 'no': ";
687 if (options.batch_mode)
689 for (msg = prompt;;msg = again) {
690 p = read_passphrase(msg, RP_ECHO);
692 (p[0] == '\0') || (p[0] == '\n') ||
693 strncasecmp(p, "no", 2) == 0)
695 if (p && strncasecmp(p, "yes", 3) == 0)
704 check_host_cert(const char *host, const Key *host_key)
708 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
712 if (buffer_len(&host_key->cert->critical) != 0) {
713 error("Certificate for %s contains unsupported "
714 "critical options(s)", host);
721 sockaddr_is_local(struct sockaddr *hostaddr)
723 switch (hostaddr->sa_family) {
725 return (ntohl(((struct sockaddr_in *)hostaddr)->
726 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
728 return IN6_IS_ADDR_LOOPBACK(
729 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
736 * Prepare the hostname and ip address strings that are used to lookup
737 * host keys in known_hosts files. These may have a port number appended.
740 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
741 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
743 char ntop[NI_MAXHOST];
746 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
751 addrlen = sizeof(struct sockaddr_in);
754 addrlen = sizeof(struct sockaddr_in6);
757 addrlen = sizeof(struct sockaddr);
762 * We don't have the remote ip-address for connections
763 * using a proxy command
765 if (hostfile_ipaddr != NULL) {
766 if (options.proxy_command == NULL) {
767 if (getnameinfo(hostaddr, addrlen,
768 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
769 fatal("check_host_key: getnameinfo failed");
770 *hostfile_ipaddr = put_host_port(ntop, port);
772 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
778 * Allow the user to record the key under a different name or
779 * differentiate a non-standard port. This is useful for ssh
780 * tunneling over forwarded connections or if you run multiple
781 * sshd's on different ports on the same machine.
783 if (hostfile_hostname != NULL) {
784 if (options.host_key_alias != NULL) {
785 *hostfile_hostname = xstrdup(options.host_key_alias);
786 debug("using hostkeyalias: %s", *hostfile_hostname);
788 *hostfile_hostname = put_host_port(hostname, port);
794 * check whether the supplied host key is valid, return -1 if the key
795 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
801 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
802 Key *host_key, int readonly,
803 char **user_hostfiles, u_int num_user_hostfiles,
804 char **system_hostfiles, u_int num_system_hostfiles)
806 HostStatus host_status;
807 HostStatus ip_status;
809 char *ip = NULL, *host = NULL;
810 char hostline[1000], *hostp, *fp, *ra;
813 const struct hostkey_entry *host_found, *ip_found;
814 int len, cancelled_forwarding = 0;
815 int local = sockaddr_is_local(hostaddr);
816 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
817 struct hostkeys *host_hostkeys, *ip_hostkeys;
821 * Force accepting of the host key for loopback/localhost. The
822 * problem is that if the home directory is NFS-mounted to multiple
823 * machines, localhost will refer to a different machine in each of
824 * them, and the user will get bogus HOST_CHANGED warnings. This
825 * essentially disables host authentication for localhost; however,
826 * this is probably not a real problem.
828 if (options.no_host_authentication_for_localhost == 1 && local &&
829 options.host_key_alias == NULL) {
830 debug("Forcing accepting of host key for "
831 "loopback/localhost.");
836 * Prepare the hostname and address strings used for hostkey lookup.
837 * In some cases, these will have a port number appended.
839 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
842 * Turn off check_host_ip if the connection is to localhost, via proxy
843 * command or if we don't have a hostname to compare with
845 if (options.check_host_ip && (local ||
846 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
847 options.check_host_ip = 0;
849 host_hostkeys = init_hostkeys();
850 for (i = 0; i < num_user_hostfiles; i++)
851 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
852 for (i = 0; i < num_system_hostfiles; i++)
853 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
856 if (!want_cert && options.check_host_ip) {
857 ip_hostkeys = init_hostkeys();
858 for (i = 0; i < num_user_hostfiles; i++)
859 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
860 for (i = 0; i < num_system_hostfiles; i++)
861 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
865 /* Reload these as they may have changed on cert->key downgrade */
866 want_cert = key_is_cert(host_key);
867 type = key_type(host_key);
870 * Check if the host key is present in the user's list of known
871 * hosts or in the systemwide list.
873 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
877 * Also perform check for the ip address, skip the check if we are
878 * localhost, looking for a certificate, or the hostname was an ip
879 * address to begin with.
881 if (!want_cert && ip_hostkeys != NULL) {
882 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
884 if (host_status == HOST_CHANGED &&
885 (ip_status != HOST_CHANGED ||
887 !key_equal(ip_found->key, host_found->key))))
890 ip_status = host_status;
892 switch (host_status) {
894 /* The host is known and the key matches. */
895 debug("Host '%.200s' is known and matches the %s host %s.",
896 host, type, want_cert ? "certificate" : "key");
897 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
898 host_found->file, host_found->line);
899 if (want_cert && !check_host_cert(hostname, host_key))
901 if (options.check_host_ip && ip_status == HOST_NEW) {
902 if (readonly || want_cert)
903 logit("%s host key for IP address "
904 "'%.128s' not in list of known hosts.",
906 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
907 host_key, options.hash_known_hosts))
908 logit("Failed to add the %s host key for IP "
909 "address '%.128s' to the list of known "
910 "hosts (%.30s).", type, ip,
913 logit("Warning: Permanently added the %s host "
914 "key for IP address '%.128s' to the list "
915 "of known hosts.", type, ip);
916 } else if (options.visual_host_key) {
917 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
918 ra = key_fingerprint(host_key, SSH_FP_MD5,
920 logit("Host key fingerprint is %s\n%s\n", fp, ra);
926 if (options.host_key_alias == NULL && port != 0 &&
927 port != SSH_DEFAULT_PORT) {
928 debug("checking without port identifier");
929 if (check_host_key(hostname, hostaddr, 0, host_key,
930 ROQUIET, user_hostfiles, num_user_hostfiles,
931 system_hostfiles, num_system_hostfiles) == 0) {
932 debug("found matching key w/out port");
936 if (readonly || want_cert)
938 /* The host is new. */
939 if (options.strict_host_key_checking == 1) {
941 * User has requested strict host key checking. We
942 * will not add the host key automatically. The only
943 * alternative left is to abort.
945 error("No %s host key is known for %.200s and you "
946 "have requested strict checking.", type, host);
948 } else if (options.strict_host_key_checking == 2) {
949 char msg1[1024], msg2[1024];
951 if (show_other_keys(host_hostkeys, host_key))
952 snprintf(msg1, sizeof(msg1),
953 "\nbut keys of different type are already"
954 " known for this host.");
956 snprintf(msg1, sizeof(msg1), ".");
958 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
959 ra = key_fingerprint(host_key, SSH_FP_MD5,
962 if (options.verify_host_key_dns) {
963 if (matching_host_key_dns)
964 snprintf(msg2, sizeof(msg2),
965 "Matching host key fingerprint"
968 snprintf(msg2, sizeof(msg2),
969 "No matching host key fingerprint"
972 snprintf(msg, sizeof(msg),
973 "The authenticity of host '%.200s (%s)' can't be "
975 "%s key fingerprint is %s.%s%s\n%s"
976 "Are you sure you want to continue connecting "
978 host, ip, msg1, type, fp,
979 options.visual_host_key ? "\n" : "",
980 options.visual_host_key ? ra : "",
988 * If not in strict mode, add the key automatically to the
989 * local known_hosts file.
991 if (options.check_host_ip && ip_status == HOST_NEW) {
992 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
994 if (options.hash_known_hosts) {
995 /* Add hash of host and IP separately */
996 r = add_host_to_hostfile(user_hostfiles[0],
997 host, host_key, options.hash_known_hosts) &&
998 add_host_to_hostfile(user_hostfiles[0], ip,
999 host_key, options.hash_known_hosts);
1001 /* Add unhashed "host,ip" */
1002 r = add_host_to_hostfile(user_hostfiles[0],
1004 options.hash_known_hosts);
1007 r = add_host_to_hostfile(user_hostfiles[0], host,
1008 host_key, options.hash_known_hosts);
1013 logit("Failed to add the host to the list of known "
1014 "hosts (%.500s).", user_hostfiles[0]);
1016 logit("Warning: Permanently added '%.200s' (%s) to the "
1017 "list of known hosts.", hostp, type);
1020 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1021 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1022 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1023 error("The %s host key for %s is marked as revoked.", type, host);
1024 error("This could mean that a stolen key is being used to");
1025 error("impersonate this host.");
1028 * If strict host key checking is in use, the user will have
1029 * to edit the key manually and we can only abort.
1031 if (options.strict_host_key_checking) {
1032 error("%s host key for %.200s was revoked and you have "
1033 "requested strict checking.", type, host);
1036 goto continue_unsafe;
1041 * This is only a debug() since it is valid to have
1042 * CAs with wildcard DNS matches that don't match
1043 * all hosts that one might visit.
1045 debug("Host certificate authority does not "
1046 "match %s in %s:%lu", CA_MARKER,
1047 host_found->file, host_found->line);
1050 if (readonly == ROQUIET)
1052 if (options.check_host_ip && host_ip_differ) {
1054 if (ip_status == HOST_NEW)
1055 key_msg = "is unknown";
1056 else if (ip_status == HOST_OK)
1057 key_msg = "is unchanged";
1059 key_msg = "has a different value";
1060 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1061 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1062 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1063 error("The %s host key for %s has changed,", type, host);
1064 error("and the key for the corresponding IP address %s", ip);
1065 error("%s. This could either mean that", key_msg);
1066 error("DNS SPOOFING is happening or the IP address for the host");
1067 error("and its host key have changed at the same time.");
1068 if (ip_status != HOST_NEW)
1069 error("Offending key for IP in %s:%lu",
1070 ip_found->file, ip_found->line);
1072 /* The host key has changed. */
1073 warn_changed_key(host_key);
1074 error("Add correct host key in %.100s to get rid of this message.",
1076 error("Offending %s key in %s:%lu", key_type(host_found->key),
1077 host_found->file, host_found->line);
1080 * If strict host key checking is in use, the user will have
1081 * to edit the key manually and we can only abort.
1083 if (options.strict_host_key_checking) {
1084 error("%s host key for %.200s has changed and you have "
1085 "requested strict checking.", type, host);
1091 * If strict host key checking has not been requested, allow
1092 * the connection but without MITM-able authentication or
1095 if (options.password_authentication) {
1096 error("Password authentication is disabled to avoid "
1097 "man-in-the-middle attacks.");
1098 options.password_authentication = 0;
1099 cancelled_forwarding = 1;
1101 if (options.kbd_interactive_authentication) {
1102 error("Keyboard-interactive authentication is disabled"
1103 " to avoid man-in-the-middle attacks.");
1104 options.kbd_interactive_authentication = 0;
1105 options.challenge_response_authentication = 0;
1106 cancelled_forwarding = 1;
1108 if (options.challenge_response_authentication) {
1109 error("Challenge/response authentication is disabled"
1110 " to avoid man-in-the-middle attacks.");
1111 options.challenge_response_authentication = 0;
1112 cancelled_forwarding = 1;
1114 if (options.forward_agent) {
1115 error("Agent forwarding is disabled to avoid "
1116 "man-in-the-middle attacks.");
1117 options.forward_agent = 0;
1118 cancelled_forwarding = 1;
1120 if (options.forward_x11) {
1121 error("X11 forwarding is disabled to avoid "
1122 "man-in-the-middle attacks.");
1123 options.forward_x11 = 0;
1124 cancelled_forwarding = 1;
1126 if (options.num_local_forwards > 0 ||
1127 options.num_remote_forwards > 0) {
1128 error("Port forwarding is disabled to avoid "
1129 "man-in-the-middle attacks.");
1130 options.num_local_forwards =
1131 options.num_remote_forwards = 0;
1132 cancelled_forwarding = 1;
1134 if (options.tun_open != SSH_TUNMODE_NO) {
1135 error("Tunnel forwarding is disabled to avoid "
1136 "man-in-the-middle attacks.");
1137 options.tun_open = SSH_TUNMODE_NO;
1138 cancelled_forwarding = 1;
1140 if (options.exit_on_forward_failure && cancelled_forwarding)
1141 fatal("Error: forwarding disabled due to host key "
1145 * XXX Should permit the user to change to use the new id.
1146 * This could be done by converting the host key to an
1147 * identifying sentence, tell that the host identifies itself
1148 * by that sentence, and ask the user if he/she wishes to
1149 * accept the authentication.
1153 fatal("internal error");
1157 if (options.check_host_ip && host_status != HOST_CHANGED &&
1158 ip_status == HOST_CHANGED) {
1159 snprintf(msg, sizeof(msg),
1160 "Warning: the %s host key for '%.200s' "
1161 "differs from the key for the IP address '%.128s'"
1162 "\nOffending key for IP in %s:%lu",
1163 type, host, ip, ip_found->file, ip_found->line);
1164 if (host_status == HOST_OK) {
1166 snprintf(msg + len, sizeof(msg) - len,
1167 "\nMatching host key in %s:%lu",
1168 host_found->file, host_found->line);
1170 if (options.strict_host_key_checking == 1) {
1172 error("Exiting, you have requested strict checking.");
1174 } else if (options.strict_host_key_checking == 2) {
1175 strlcat(msg, "\nAre you sure you want "
1176 "to continue connecting (yes/no)? ", sizeof(msg));
1186 if (host_hostkeys != NULL)
1187 free_hostkeys(host_hostkeys);
1188 if (ip_hostkeys != NULL)
1189 free_hostkeys(ip_hostkeys);
1193 if (want_cert && host_status != HOST_REVOKED) {
1195 * No matching certificate. Downgrade cert to raw key and
1198 debug("No matching CA found. Retry with plain key");
1199 raw_key = key_from_private(host_key);
1200 if (key_drop_cert(raw_key) != 0)
1201 fatal("Couldn't drop certificate");
1205 if (raw_key != NULL)
1209 if (host_hostkeys != NULL)
1210 free_hostkeys(host_hostkeys);
1211 if (ip_hostkeys != NULL)
1212 free_hostkeys(ip_hostkeys);
1216 /* returns 0 if key verifies or -1 if key does NOT verify */
1218 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1223 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1224 debug("Server host key: %s %s", key_type(host_key), fp);
1227 /* XXX certs are not yet supported for DNS */
1228 if (!key_is_cert(host_key) && options.verify_host_key_dns &&
1229 verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1230 if (flags & DNS_VERIFY_FOUND) {
1232 if (options.verify_host_key_dns == 1 &&
1233 flags & DNS_VERIFY_MATCH &&
1234 flags & DNS_VERIFY_SECURE)
1237 if (flags & DNS_VERIFY_MATCH) {
1238 matching_host_key_dns = 1;
1240 warn_changed_key(host_key);
1241 error("Update the SSHFP RR in DNS with the new "
1242 "host key to get rid of this message.");
1247 return check_host_key(host, hostaddr, options.port, host_key, RDRW,
1248 options.user_hostfiles, options.num_user_hostfiles,
1249 options.system_hostfiles, options.num_system_hostfiles);
1253 * Starts a dialog with the server, and authenticates the current user on the
1254 * server. This does not need any extra privileges. The basic connection
1255 * to the server must already have been established before this is called.
1256 * If login fails, this function prints an error and never returns.
1257 * This function does not require super-user privileges.
1260 ssh_login(Sensitive *sensitive, const char *orighost,
1261 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1264 char *server_user, *local_user;
1266 local_user = xstrdup(pw->pw_name);
1267 server_user = options.user ? options.user : local_user;
1269 /* Convert the user-supplied hostname into all lowercase. */
1270 host = xstrdup(orighost);
1273 /* Exchange protocol version identification strings with the server. */
1274 ssh_exchange_identification(timeout_ms);
1276 /* Put the connection into non-blocking mode. */
1277 packet_set_nonblocking();
1280 /* authenticate user */
1282 ssh_kex2(host, hostaddr, port);
1283 ssh_userauth2(local_user, server_user, host, sensitive);
1285 ssh_kex(host, hostaddr);
1286 ssh_userauth1(local_user, server_user, host, sensitive);
1292 ssh_put_password(char *password)
1297 if (datafellows & SSH_BUG_PASSWORDPAD) {
1298 packet_put_cstring(password);
1301 size = roundup(strlen(password) + 1, 32);
1302 padded = xcalloc(1, size);
1303 strlcpy(padded, password, size);
1304 packet_put_string(padded, size);
1305 explicit_bzero(padded, size);
1309 /* print all known host keys for a given host, but skip keys of given type */
1311 show_other_keys(struct hostkeys *hostkeys, Key *key)
1323 const struct hostkey_entry *found;
1325 for (i = 0; type[i] != -1; i++) {
1326 if (type[i] == key->type)
1328 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1330 fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1331 ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1332 logit("WARNING: %s key found for host %s\n"
1334 "%s key fingerprint %s.",
1335 key_type(found->key),
1336 found->host, found->file, found->line,
1337 key_type(found->key), fp);
1338 if (options.visual_host_key)
1348 warn_changed_key(Key *host_key)
1352 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1354 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1355 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1356 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1357 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1358 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1359 error("It is also possible that a host key has just been changed.");
1360 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1361 key_type(host_key), fp);
1362 error("Please contact your system administrator.");
1368 * Execute a local command
1371 ssh_local_cmd(const char *args)
1376 void (*osighand)(int);
1378 if (!options.permit_local_command ||
1379 args == NULL || !*args)
1382 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1383 shell = _PATH_BSHELL;
1385 osighand = signal(SIGCHLD, SIG_DFL);
1388 signal(SIGPIPE, SIG_DFL);
1389 debug3("Executing %s -c \"%s\"", shell, args);
1390 execl(shell, shell, "-c", args, (char *)NULL);
1391 error("Couldn't execute %s -c \"%s\": %s",
1392 shell, args, strerror(errno));
1394 } else if (pid == -1)
1395 fatal("fork failed: %.100s", strerror(errno));
1396 while (waitpid(pid, &status, 0) == -1)
1398 fatal("Couldn't wait for child: %s", strerror(errno));
1399 signal(SIGCHLD, osighand);
1401 if (!WIFEXITED(status))
1404 return (WEXITSTATUS(status));