1 /* $OpenBSD: sshconnect.c,v 1.251 2014/07/15 15:54:14 millert 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>
55 #include "sshconnect.h"
63 #include "monitor_fdpass.h"
67 char *client_version_string = NULL;
68 char *server_version_string = NULL;
69 Key *previous_host_key = NULL;
71 static int matching_host_key_dns = 0;
73 static pid_t proxy_command_pid = 0;
76 extern Options options;
77 extern char *__progname;
78 extern uid_t original_real_uid;
79 extern uid_t original_effective_uid;
81 static int show_other_keys(struct hostkeys *, Key *);
82 static void warn_changed_key(Key *);
84 /* Expand a proxy command */
86 expand_proxy_command(const char *proxy_command, const char *user,
87 const char *host, int port)
89 char *tmp, *ret, strport[NI_MAXSERV];
91 snprintf(strport, sizeof strport, "%d", port);
92 xasprintf(&tmp, "exec %s", proxy_command);
93 ret = percent_expand(tmp, "h", host, "p", strport,
94 "r", options.user, (char *)NULL);
100 * Connect to the given ssh server using a proxy command that passes a
101 * a connected fd back to us.
104 ssh_proxy_fdpass_connect(const char *host, u_short port,
105 const char *proxy_command)
107 char *command_string;
112 if ((shell = getenv("SHELL")) == NULL)
113 shell = _PATH_BSHELL;
115 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
116 fatal("Could not create socketpair to communicate with "
117 "proxy dialer: %.100s", strerror(errno));
119 command_string = expand_proxy_command(proxy_command, options.user,
121 debug("Executing proxy dialer command: %.500s", command_string);
123 /* Fork and execute the proxy command. */
124 if ((pid = fork()) == 0) {
127 /* Child. Permanently give up superuser privileges. */
128 permanently_drop_suid(original_real_uid);
131 /* Redirect stdin and stdout. */
133 if (dup2(sp[0], 0) < 0)
134 perror("dup2 stdin");
137 if (dup2(sp[0], 1) < 0)
138 perror("dup2 stdout");
144 * Stderr is left as it is so that error messages get
145 * printed on the user's terminal.
149 argv[2] = command_string;
153 * Execute the proxy command.
154 * Note that we gave up any extra privileges above.
156 execv(argv[0], argv);
162 fatal("fork failed: %.100s", strerror(errno));
164 free(command_string);
166 if ((sock = mm_receive_fd(sp[1])) == -1)
167 fatal("proxy dialer did not pass back a connection");
169 while (waitpid(pid, NULL, 0) == -1)
171 fatal("Couldn't wait for child: %s", strerror(errno));
173 /* Set the connection file descriptors. */
174 packet_set_connection(sock, sock);
180 * Connect to the given ssh server using a proxy command.
183 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
185 char *command_string;
190 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
191 shell = _PATH_BSHELL;
193 /* Create pipes for communicating with the proxy. */
194 if (pipe(pin) < 0 || pipe(pout) < 0)
195 fatal("Could not create pipes to communicate with the proxy: %.100s",
198 command_string = expand_proxy_command(proxy_command, options.user,
200 debug("Executing proxy command: %.500s", command_string);
202 /* Fork and execute the proxy command. */
203 if ((pid = fork()) == 0) {
206 /* Child. Permanently give up superuser privileges. */
207 permanently_drop_suid(original_real_uid);
209 /* Redirect stdin and stdout. */
212 if (dup2(pin[0], 0) < 0)
213 perror("dup2 stdin");
217 if (dup2(pout[1], 1) < 0)
218 perror("dup2 stdout");
219 /* Cannot be 1 because pin allocated two descriptors. */
222 /* Stderr is left as it is so that error messages get
223 printed on the user's terminal. */
226 argv[2] = command_string;
229 /* Execute the proxy command. Note that we gave up any
230 extra privileges above. */
231 signal(SIGPIPE, SIG_DFL);
232 execv(argv[0], argv);
238 fatal("fork failed: %.100s", strerror(errno));
240 proxy_command_pid = pid; /* save pid to clean up later */
242 /* Close child side of the descriptors. */
246 /* Free the command name. */
247 free(command_string);
249 /* Set the connection file descriptors. */
250 packet_set_connection(pout[0], pin[1]);
252 /* Indicate OK return */
257 ssh_kill_proxy_command(void)
260 * Send SIGHUP to proxy command if used. We don't wait() in
261 * case it hangs and instead rely on init to reap the child
263 if (proxy_command_pid > 1)
264 kill(proxy_command_pid, SIGHUP);
268 * Set TCP receive buffer if requested.
269 * Note: tuning needs to happen after the socket is
270 * created but before the connection happens
271 * so winscale is negotiated properly -cjr
274 ssh_set_socket_recvbuf(int sock)
276 void *buf = (void *)&options.tcp_rcv_buf;
277 int sz = sizeof(options.tcp_rcv_buf);
279 int socksizelen = sizeof(int);
281 debug("setsockopt Attempting to set SO_RCVBUF to %d", options.tcp_rcv_buf);
282 if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, buf, sz) >= 0) {
283 getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &socksize, &socksizelen);
284 debug("setsockopt SO_RCVBUF: %.100s %d", strerror(errno), socksize);
287 error("Couldn't set socket receive buffer to %d: %.100s",
288 options.tcp_rcv_buf, strerror(errno));
293 * Creates a (possibly privileged) socket for use as the ssh connection.
296 ssh_create_socket(int privileged, struct addrinfo *ai)
299 struct addrinfo hints, *res = NULL;
301 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
303 error("socket: %s", strerror(errno));
306 fcntl(sock, F_SETFD, FD_CLOEXEC);
308 if (options.tcp_rcv_buf > 0)
309 ssh_set_socket_recvbuf(sock);
311 /* Bind the socket to an alternative local IP address */
312 if (options.bind_address == NULL && !privileged)
315 if (options.bind_address) {
316 memset(&hints, 0, sizeof(hints));
317 hints.ai_family = ai->ai_family;
318 hints.ai_socktype = ai->ai_socktype;
319 hints.ai_protocol = ai->ai_protocol;
320 hints.ai_flags = AI_PASSIVE;
321 gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
323 error("getaddrinfo: %s: %s", options.bind_address,
324 ssh_gai_strerror(gaierr));
330 * If we are running as root and want to connect to a privileged
331 * port, bind our own socket to a privileged port.
335 r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
338 error("bindresvport_sa: af=%d %s", ai->ai_family,
343 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
344 error("bind: %s: %s", options.bind_address,
358 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
359 socklen_t addrlen, int *timeoutp)
362 struct timeval tv, t_start;
364 int optval, rc, result = -1;
366 gettimeofday(&t_start, NULL);
368 if (*timeoutp <= 0) {
369 result = connect(sockfd, serv_addr, addrlen);
373 set_nonblock(sockfd);
374 rc = connect(sockfd, serv_addr, addrlen);
376 unset_nonblock(sockfd);
380 if (errno != EINPROGRESS) {
385 fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
387 FD_SET(sockfd, fdset);
388 ms_to_timeval(&tv, *timeoutp);
391 rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
392 if (rc != -1 || errno != EINTR)
403 debug("select: %s", strerror(errno));
406 /* Completed or failed */
408 optlen = sizeof(optval);
409 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
411 debug("getsockopt: %s", strerror(errno));
419 unset_nonblock(sockfd);
422 /* Should not occur */
423 fatal("Bogus return (%d) from select()", rc);
429 if (result == 0 && *timeoutp > 0) {
430 ms_subtract_diff(&t_start, timeoutp);
431 if (*timeoutp <= 0) {
441 * Opens a TCP/IP connection to the remote server on the given host.
442 * The address of the remote host will be returned in hostaddr.
443 * If port is 0, the default port will be used. If needpriv is true,
444 * a privileged port will be allocated to make the connection.
445 * This requires super-user privileges if needpriv is true.
446 * Connection_attempts specifies the maximum number of tries (one per
447 * second). If proxy_command is non-NULL, it specifies the command (with %h
448 * and %p substituted for host and port, respectively) to use to contact
452 ssh_connect_direct(const char *host, struct addrinfo *aitop,
453 struct sockaddr_storage *hostaddr, u_short port, int family,
454 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
457 int sock = -1, attempt;
458 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
461 debug2("ssh_connect: needpriv %d", needpriv);
463 for (attempt = 0; attempt < connection_attempts; attempt++) {
465 /* Sleep a moment before retrying. */
467 debug("Trying again...");
470 * Loop through addresses for this host, and try each one in
471 * sequence until the connection succeeds.
473 for (ai = aitop; ai; ai = ai->ai_next) {
474 if (ai->ai_family != AF_INET &&
475 ai->ai_family != AF_INET6)
477 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
478 ntop, sizeof(ntop), strport, sizeof(strport),
479 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
480 error("ssh_connect: getnameinfo failed");
483 debug("Connecting to %.200s [%.100s] port %s.",
484 host, ntop, strport);
486 /* Create a socket for connecting. */
487 sock = ssh_create_socket(needpriv, ai);
489 /* Any error is already output */
492 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
494 /* Successful connection. */
495 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
498 debug("connect to address %s port %s: %s",
499 ntop, strport, strerror(errno));
505 break; /* Successful connection. */
508 /* Return failure if we didn't get a successful connection. */
510 error("ssh: connect to host %s port %s: %s",
511 host, strport, strerror(errno));
515 debug("Connection established.");
517 /* Set SO_KEEPALIVE if requested. */
518 if (want_keepalive &&
519 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
521 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
523 /* Set the connection. */
524 packet_set_connection(sock, sock);
530 ssh_connect(const char *host, struct addrinfo *addrs,
531 struct sockaddr_storage *hostaddr, u_short port, int family,
532 int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
534 if (options.proxy_command == NULL) {
535 return ssh_connect_direct(host, addrs, hostaddr, port, family,
536 connection_attempts, timeout_ms, want_keepalive, needpriv);
537 } else if (strcmp(options.proxy_command, "-") == 0) {
538 packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
539 return 0; /* Always succeeds */
540 } else if (options.proxy_use_fdpass) {
541 return ssh_proxy_fdpass_connect(host, port,
542 options.proxy_command);
544 return ssh_proxy_connect(host, port, options.proxy_command);
548 send_client_banner(int connection_out, int minor1)
550 /* Send our own protocol version identification. */
551 xasprintf(&client_version_string, "SSH-%d.%d-%.100s%s%s%s%s",
552 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
553 compat20 ? PROTOCOL_MINOR_2 : minor1,
554 SSH_RELEASE, options.hpn_disabled ? "" : SSH_VERSION_HPN,
555 *options.version_addendum == '\0' ? "" : " ",
556 options.version_addendum, compat20 ? "\r\n" : "\n");
557 if (roaming_atomicio(vwrite, connection_out, client_version_string,
558 strlen(client_version_string)) != strlen(client_version_string))
559 fatal("write: %.100s", strerror(errno));
560 chop(client_version_string);
561 debug("Local version string %.100s", client_version_string);
565 * Waits for the server identification string, and sends our own
566 * identification string.
569 ssh_exchange_identification(int timeout_ms)
571 char buf[256], remote_version[256]; /* must be same size! */
572 int remote_major, remote_minor, mismatch;
573 int connection_in = packet_get_connection_in();
574 int connection_out = packet_get_connection_out();
575 int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
578 int fdsetsz, remaining, rc;
579 struct timeval t_start, t_remaining;
582 fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
583 fdset = xcalloc(1, fdsetsz);
586 * If we are SSH2-only then we can send the banner immediately and
589 if (options.protocol == SSH_PROTO_2) {
591 send_client_banner(connection_out, 0);
592 client_banner_sent = 1;
595 /* Read other side's version identification. */
596 remaining = timeout_ms;
598 for (i = 0; i < sizeof(buf) - 1; i++) {
599 if (timeout_ms > 0) {
600 gettimeofday(&t_start, NULL);
601 ms_to_timeval(&t_remaining, remaining);
602 FD_SET(connection_in, fdset);
603 rc = select(connection_in + 1, fdset, NULL,
604 fdset, &t_remaining);
605 ms_subtract_diff(&t_start, &remaining);
606 if (rc == 0 || remaining <= 0)
607 fatal("Connection timed out during "
612 fatal("ssh_exchange_identification: "
613 "select: %s", strerror(errno));
617 len = roaming_atomicio(read, connection_in, &buf[i], 1);
619 if (len != 1 && errno == EPIPE)
620 fatal("ssh_exchange_identification: "
621 "Connection closed by remote host");
623 fatal("ssh_exchange_identification: "
624 "read: %.100s", strerror(errno));
625 if (buf[i] == '\r') {
628 continue; /**XXX wait for \n */
630 if (buf[i] == '\n') {
635 fatal("ssh_exchange_identification: "
636 "No banner received");
638 buf[sizeof(buf) - 1] = 0;
639 if (strncmp(buf, "SSH-", 4) == 0)
641 debug("ssh_exchange_identification: %s", buf);
643 server_version_string = xstrdup(buf);
647 * Check that the versions match. In future this might accept
648 * several versions and set appropriate flags to handle them.
650 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
651 &remote_major, &remote_minor, remote_version) != 3)
652 fatal("Bad remote protocol version identification: '%.100s'", buf);
653 debug("Remote protocol version %d.%d, remote software version %.100s",
654 remote_major, remote_minor, remote_version);
656 compat_datafellows(remote_version);
659 switch (remote_major) {
661 if (remote_minor == 99 &&
662 (options.protocol & SSH_PROTO_2) &&
663 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
667 if (!(options.protocol & SSH_PROTO_1)) {
671 if (remote_minor < 3) {
672 fatal("Remote machine has too old SSH software version.");
673 } else if (remote_minor == 3 || remote_minor == 4) {
674 /* We speak 1.3, too. */
677 if (options.forward_agent) {
678 logit("Agent forwarding disabled for protocol 1.3");
679 options.forward_agent = 0;
684 if (options.protocol & SSH_PROTO_2) {
694 fatal("Protocol major versions differ: %d vs. %d",
695 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
697 if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
698 fatal("Server version \"%.100s\" uses unsafe key agreement; "
699 "refusing connection", remote_version);
700 if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
701 logit("Server version \"%.100s\" uses unsafe RSA signature "
702 "scheme; disabling use of RSA keys", remote_version);
703 if (!client_banner_sent)
704 send_client_banner(connection_out, minor1);
705 chop(server_version_string);
708 /* defaults to 'no' */
710 confirm(const char *prompt)
712 const char *msg, *again = "Please type 'yes' or 'no': ";
716 if (options.batch_mode)
718 for (msg = prompt;;msg = again) {
719 p = read_passphrase(msg, RP_ECHO);
721 (p[0] == '\0') || (p[0] == '\n') ||
722 strncasecmp(p, "no", 2) == 0)
724 if (p && strncasecmp(p, "yes", 3) == 0)
733 check_host_cert(const char *host, const Key *host_key)
737 if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
741 if (buffer_len(host_key->cert->critical) != 0) {
742 error("Certificate for %s contains unsupported "
743 "critical options(s)", host);
750 sockaddr_is_local(struct sockaddr *hostaddr)
752 switch (hostaddr->sa_family) {
754 return (ntohl(((struct sockaddr_in *)hostaddr)->
755 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
757 return IN6_IS_ADDR_LOOPBACK(
758 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
765 * Prepare the hostname and ip address strings that are used to lookup
766 * host keys in known_hosts files. These may have a port number appended.
769 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
770 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
772 char ntop[NI_MAXHOST];
775 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
780 addrlen = sizeof(struct sockaddr_in);
783 addrlen = sizeof(struct sockaddr_in6);
786 addrlen = sizeof(struct sockaddr);
791 * We don't have the remote ip-address for connections
792 * using a proxy command
794 if (hostfile_ipaddr != NULL) {
795 if (options.proxy_command == NULL) {
796 if (getnameinfo(hostaddr, addrlen,
797 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
798 fatal("check_host_key: getnameinfo failed");
799 *hostfile_ipaddr = put_host_port(ntop, port);
801 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
807 * Allow the user to record the key under a different name or
808 * differentiate a non-standard port. This is useful for ssh
809 * tunneling over forwarded connections or if you run multiple
810 * sshd's on different ports on the same machine.
812 if (hostfile_hostname != NULL) {
813 if (options.host_key_alias != NULL) {
814 *hostfile_hostname = xstrdup(options.host_key_alias);
815 debug("using hostkeyalias: %s", *hostfile_hostname);
817 *hostfile_hostname = put_host_port(hostname, port);
823 * check whether the supplied host key is valid, return -1 if the key
824 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
830 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
831 Key *host_key, int readonly,
832 char **user_hostfiles, u_int num_user_hostfiles,
833 char **system_hostfiles, u_int num_system_hostfiles)
835 HostStatus host_status;
836 HostStatus ip_status;
838 char *ip = NULL, *host = NULL;
839 char hostline[1000], *hostp, *fp, *ra;
842 const struct hostkey_entry *host_found, *ip_found;
843 int len, cancelled_forwarding = 0;
844 int local = sockaddr_is_local(hostaddr);
845 int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
846 struct hostkeys *host_hostkeys, *ip_hostkeys;
850 * Force accepting of the host key for loopback/localhost. The
851 * problem is that if the home directory is NFS-mounted to multiple
852 * machines, localhost will refer to a different machine in each of
853 * them, and the user will get bogus HOST_CHANGED warnings. This
854 * essentially disables host authentication for localhost; however,
855 * this is probably not a real problem.
857 if (options.no_host_authentication_for_localhost == 1 && local &&
858 options.host_key_alias == NULL) {
859 debug("Forcing accepting of host key for "
860 "loopback/localhost.");
865 * Prepare the hostname and address strings used for hostkey lookup.
866 * In some cases, these will have a port number appended.
868 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
871 * Turn off check_host_ip if the connection is to localhost, via proxy
872 * command or if we don't have a hostname to compare with
874 if (options.check_host_ip && (local ||
875 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
876 options.check_host_ip = 0;
878 host_hostkeys = init_hostkeys();
879 for (i = 0; i < num_user_hostfiles; i++)
880 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
881 for (i = 0; i < num_system_hostfiles; i++)
882 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
885 if (!want_cert && options.check_host_ip) {
886 ip_hostkeys = init_hostkeys();
887 for (i = 0; i < num_user_hostfiles; i++)
888 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
889 for (i = 0; i < num_system_hostfiles; i++)
890 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
894 /* Reload these as they may have changed on cert->key downgrade */
895 want_cert = key_is_cert(host_key);
896 type = key_type(host_key);
899 * Check if the host key is present in the user's list of known
900 * hosts or in the systemwide list.
902 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
906 * Also perform check for the ip address, skip the check if we are
907 * localhost, looking for a certificate, or the hostname was an ip
908 * address to begin with.
910 if (!want_cert && ip_hostkeys != NULL) {
911 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
913 if (host_status == HOST_CHANGED &&
914 (ip_status != HOST_CHANGED ||
916 !key_equal(ip_found->key, host_found->key))))
919 ip_status = host_status;
921 switch (host_status) {
923 /* The host is known and the key matches. */
924 debug("Host '%.200s' is known and matches the %s host %s.",
925 host, type, want_cert ? "certificate" : "key");
926 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
927 host_found->file, host_found->line);
928 if (want_cert && !check_host_cert(hostname, host_key))
930 if (options.check_host_ip && ip_status == HOST_NEW) {
931 if (readonly || want_cert)
932 logit("%s host key for IP address "
933 "'%.128s' not in list of known hosts.",
935 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
936 host_key, options.hash_known_hosts))
937 logit("Failed to add the %s host key for IP "
938 "address '%.128s' to the list of known "
939 "hosts (%.30s).", type, ip,
942 logit("Warning: Permanently added the %s host "
943 "key for IP address '%.128s' to the list "
944 "of known hosts.", type, ip);
945 } else if (options.visual_host_key) {
946 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
947 ra = key_fingerprint(host_key, SSH_FP_MD5,
949 logit("Host key fingerprint is %s\n%s\n", fp, ra);
955 if (options.host_key_alias == NULL && port != 0 &&
956 port != SSH_DEFAULT_PORT) {
957 debug("checking without port identifier");
958 if (check_host_key(hostname, hostaddr, 0, host_key,
959 ROQUIET, user_hostfiles, num_user_hostfiles,
960 system_hostfiles, num_system_hostfiles) == 0) {
961 debug("found matching key w/out port");
965 if (readonly || want_cert)
967 /* The host is new. */
968 if (options.strict_host_key_checking == 1) {
970 * User has requested strict host key checking. We
971 * will not add the host key automatically. The only
972 * alternative left is to abort.
974 error("No %s host key is known for %.200s and you "
975 "have requested strict checking.", type, host);
977 } else if (options.strict_host_key_checking == 2) {
978 char msg1[1024], msg2[1024];
980 if (show_other_keys(host_hostkeys, host_key))
981 snprintf(msg1, sizeof(msg1),
982 "\nbut keys of different type are already"
983 " known for this host.");
985 snprintf(msg1, sizeof(msg1), ".");
987 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
988 ra = key_fingerprint(host_key, SSH_FP_MD5,
991 if (options.verify_host_key_dns) {
992 if (matching_host_key_dns)
993 snprintf(msg2, sizeof(msg2),
994 "Matching host key fingerprint"
997 snprintf(msg2, sizeof(msg2),
998 "No matching host key fingerprint"
1001 snprintf(msg, sizeof(msg),
1002 "The authenticity of host '%.200s (%s)' can't be "
1004 "%s key fingerprint is %s.%s%s\n%s"
1005 "Are you sure you want to continue connecting "
1007 host, ip, msg1, type, fp,
1008 options.visual_host_key ? "\n" : "",
1009 options.visual_host_key ? ra : "",
1017 * If not in strict mode, add the key automatically to the
1018 * local known_hosts file.
1020 if (options.check_host_ip && ip_status == HOST_NEW) {
1021 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1023 if (options.hash_known_hosts) {
1024 /* Add hash of host and IP separately */
1025 r = add_host_to_hostfile(user_hostfiles[0],
1026 host, host_key, options.hash_known_hosts) &&
1027 add_host_to_hostfile(user_hostfiles[0], ip,
1028 host_key, options.hash_known_hosts);
1030 /* Add unhashed "host,ip" */
1031 r = add_host_to_hostfile(user_hostfiles[0],
1033 options.hash_known_hosts);
1036 r = add_host_to_hostfile(user_hostfiles[0], host,
1037 host_key, options.hash_known_hosts);
1042 logit("Failed to add the host to the list of known "
1043 "hosts (%.500s).", user_hostfiles[0]);
1045 logit("Warning: Permanently added '%.200s' (%s) to the "
1046 "list of known hosts.", hostp, type);
1049 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1050 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1051 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1052 error("The %s host key for %s is marked as revoked.", type, host);
1053 error("This could mean that a stolen key is being used to");
1054 error("impersonate this host.");
1057 * If strict host key checking is in use, the user will have
1058 * to edit the key manually and we can only abort.
1060 if (options.strict_host_key_checking) {
1061 error("%s host key for %.200s was revoked and you have "
1062 "requested strict checking.", type, host);
1065 goto continue_unsafe;
1070 * This is only a debug() since it is valid to have
1071 * CAs with wildcard DNS matches that don't match
1072 * all hosts that one might visit.
1074 debug("Host certificate authority does not "
1075 "match %s in %s:%lu", CA_MARKER,
1076 host_found->file, host_found->line);
1079 if (readonly == ROQUIET)
1081 if (options.check_host_ip && host_ip_differ) {
1083 if (ip_status == HOST_NEW)
1084 key_msg = "is unknown";
1085 else if (ip_status == HOST_OK)
1086 key_msg = "is unchanged";
1088 key_msg = "has a different value";
1089 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1090 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1091 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1092 error("The %s host key for %s has changed,", type, host);
1093 error("and the key for the corresponding IP address %s", ip);
1094 error("%s. This could either mean that", key_msg);
1095 error("DNS SPOOFING is happening or the IP address for the host");
1096 error("and its host key have changed at the same time.");
1097 if (ip_status != HOST_NEW)
1098 error("Offending key for IP in %s:%lu",
1099 ip_found->file, ip_found->line);
1101 /* The host key has changed. */
1102 warn_changed_key(host_key);
1103 error("Add correct host key in %.100s to get rid of this message.",
1105 error("Offending %s key in %s:%lu", key_type(host_found->key),
1106 host_found->file, host_found->line);
1109 * If strict host key checking is in use, the user will have
1110 * to edit the key manually and we can only abort.
1112 if (options.strict_host_key_checking) {
1113 error("%s host key for %.200s has changed and you have "
1114 "requested strict checking.", type, host);
1120 * If strict host key checking has not been requested, allow
1121 * the connection but without MITM-able authentication or
1124 if (options.password_authentication) {
1125 error("Password authentication is disabled to avoid "
1126 "man-in-the-middle attacks.");
1127 options.password_authentication = 0;
1128 cancelled_forwarding = 1;
1130 if (options.kbd_interactive_authentication) {
1131 error("Keyboard-interactive authentication is disabled"
1132 " to avoid man-in-the-middle attacks.");
1133 options.kbd_interactive_authentication = 0;
1134 options.challenge_response_authentication = 0;
1135 cancelled_forwarding = 1;
1137 if (options.challenge_response_authentication) {
1138 error("Challenge/response authentication is disabled"
1139 " to avoid man-in-the-middle attacks.");
1140 options.challenge_response_authentication = 0;
1141 cancelled_forwarding = 1;
1143 if (options.forward_agent) {
1144 error("Agent forwarding is disabled to avoid "
1145 "man-in-the-middle attacks.");
1146 options.forward_agent = 0;
1147 cancelled_forwarding = 1;
1149 if (options.forward_x11) {
1150 error("X11 forwarding is disabled to avoid "
1151 "man-in-the-middle attacks.");
1152 options.forward_x11 = 0;
1153 cancelled_forwarding = 1;
1155 if (options.num_local_forwards > 0 ||
1156 options.num_remote_forwards > 0) {
1157 error("Port forwarding is disabled to avoid "
1158 "man-in-the-middle attacks.");
1159 options.num_local_forwards =
1160 options.num_remote_forwards = 0;
1161 cancelled_forwarding = 1;
1163 if (options.tun_open != SSH_TUNMODE_NO) {
1164 error("Tunnel forwarding is disabled to avoid "
1165 "man-in-the-middle attacks.");
1166 options.tun_open = SSH_TUNMODE_NO;
1167 cancelled_forwarding = 1;
1169 if (options.exit_on_forward_failure && cancelled_forwarding)
1170 fatal("Error: forwarding disabled due to host key "
1174 * XXX Should permit the user to change to use the new id.
1175 * This could be done by converting the host key to an
1176 * identifying sentence, tell that the host identifies itself
1177 * by that sentence, and ask the user if he/she wishes to
1178 * accept the authentication.
1182 fatal("internal error");
1186 if (options.check_host_ip && host_status != HOST_CHANGED &&
1187 ip_status == HOST_CHANGED) {
1188 snprintf(msg, sizeof(msg),
1189 "Warning: the %s host key for '%.200s' "
1190 "differs from the key for the IP address '%.128s'"
1191 "\nOffending key for IP in %s:%lu",
1192 type, host, ip, ip_found->file, ip_found->line);
1193 if (host_status == HOST_OK) {
1195 snprintf(msg + len, sizeof(msg) - len,
1196 "\nMatching host key in %s:%lu",
1197 host_found->file, host_found->line);
1199 if (options.strict_host_key_checking == 1) {
1201 error("Exiting, you have requested strict checking.");
1203 } else if (options.strict_host_key_checking == 2) {
1204 strlcat(msg, "\nAre you sure you want "
1205 "to continue connecting (yes/no)? ", sizeof(msg));
1215 if (host_hostkeys != NULL)
1216 free_hostkeys(host_hostkeys);
1217 if (ip_hostkeys != NULL)
1218 free_hostkeys(ip_hostkeys);
1222 if (want_cert && host_status != HOST_REVOKED) {
1224 * No matching certificate. Downgrade cert to raw key and
1227 debug("No matching CA found. Retry with plain key");
1228 raw_key = key_from_private(host_key);
1229 if (key_drop_cert(raw_key) != 0)
1230 fatal("Couldn't drop certificate");
1234 if (raw_key != NULL)
1238 if (host_hostkeys != NULL)
1239 free_hostkeys(host_hostkeys);
1240 if (ip_hostkeys != NULL)
1241 free_hostkeys(ip_hostkeys);
1245 /* returns 0 if key verifies or -1 if key does NOT verify */
1247 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1249 int r = -1, flags = 0;
1253 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1254 debug("Server host key: %s %s", key_type(host_key), fp);
1257 if (key_equal(previous_host_key, host_key)) {
1258 debug("%s: server host key matches cached key", __func__);
1262 if (options.verify_host_key_dns) {
1264 * XXX certs are not yet supported for DNS, so downgrade
1265 * them and try the plain key.
1267 plain = key_from_private(host_key);
1268 if (key_is_cert(plain))
1269 key_drop_cert(plain);
1270 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1271 if (flags & DNS_VERIFY_FOUND) {
1272 if (options.verify_host_key_dns == 1 &&
1273 flags & DNS_VERIFY_MATCH &&
1274 flags & DNS_VERIFY_SECURE) {
1279 if (flags & DNS_VERIFY_MATCH) {
1280 matching_host_key_dns = 1;
1282 warn_changed_key(plain);
1283 error("Update the SSHFP RR in DNS "
1284 "with the new host key to get rid "
1285 "of this message.");
1292 r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1293 options.user_hostfiles, options.num_user_hostfiles,
1294 options.system_hostfiles, options.num_system_hostfiles);
1297 if (r == 0 && host_key != NULL) {
1298 key_free(previous_host_key);
1299 previous_host_key = key_from_private(host_key);
1306 * Starts a dialog with the server, and authenticates the current user on the
1307 * server. This does not need any extra privileges. The basic connection
1308 * to the server must already have been established before this is called.
1309 * If login fails, this function prints an error and never returns.
1310 * This function does not require super-user privileges.
1313 ssh_login(Sensitive *sensitive, const char *orighost,
1314 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1317 char *server_user, *local_user;
1319 local_user = xstrdup(pw->pw_name);
1320 server_user = options.user ? options.user : local_user;
1322 /* Convert the user-supplied hostname into all lowercase. */
1323 host = xstrdup(orighost);
1326 /* Exchange protocol version identification strings with the server. */
1327 ssh_exchange_identification(timeout_ms);
1329 /* Put the connection into non-blocking mode. */
1330 packet_set_nonblocking();
1333 /* authenticate user */
1335 ssh_kex2(host, hostaddr, port);
1336 ssh_userauth2(local_user, server_user, host, sensitive);
1339 ssh_kex(host, hostaddr);
1340 ssh_userauth1(local_user, server_user, host, sensitive);
1342 fatal("ssh1 is not unsupported");
1349 ssh_put_password(char *password)
1354 if (datafellows & SSH_BUG_PASSWORDPAD) {
1355 packet_put_cstring(password);
1358 size = roundup(strlen(password) + 1, 32);
1359 padded = xcalloc(1, size);
1360 strlcpy(padded, password, size);
1361 packet_put_string(padded, size);
1362 explicit_bzero(padded, size);
1366 /* print all known host keys for a given host, but skip keys of given type */
1368 show_other_keys(struct hostkeys *hostkeys, Key *key)
1380 const struct hostkey_entry *found;
1382 for (i = 0; type[i] != -1; i++) {
1383 if (type[i] == key->type)
1385 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1387 fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1388 ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1389 logit("WARNING: %s key found for host %s\n"
1391 "%s key fingerprint %s.",
1392 key_type(found->key),
1393 found->host, found->file, found->line,
1394 key_type(found->key), fp);
1395 if (options.visual_host_key)
1405 warn_changed_key(Key *host_key)
1409 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1411 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1412 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1413 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1414 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1415 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1416 error("It is also possible that a host key has just been changed.");
1417 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1418 key_type(host_key), fp);
1419 error("Please contact your system administrator.");
1425 * Execute a local command
1428 ssh_local_cmd(const char *args)
1433 void (*osighand)(int);
1435 if (!options.permit_local_command ||
1436 args == NULL || !*args)
1439 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1440 shell = _PATH_BSHELL;
1442 osighand = signal(SIGCHLD, SIG_DFL);
1445 signal(SIGPIPE, SIG_DFL);
1446 debug3("Executing %s -c \"%s\"", shell, args);
1447 execl(shell, shell, "-c", args, (char *)NULL);
1448 error("Couldn't execute %s -c \"%s\": %s",
1449 shell, args, strerror(errno));
1451 } else if (pid == -1)
1452 fatal("fork failed: %.100s", strerror(errno));
1453 while (waitpid(pid, &status, 0) == -1)
1455 fatal("Couldn't wait for child: %s", strerror(errno));
1456 signal(SIGCHLD, osighand);
1458 if (!WIFEXITED(status))
1461 return (WEXITSTATUS(status));