1 /* $OpenBSD: sshconnect.c,v 1.304 2018/07/27 05:34:42 dtucker 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".
19 #include <sys/types.h>
22 #include <sys/socket.h>
23 #ifdef HAVE_SYS_TIME_H
24 # include <sys/time.h>
28 #include <netinet/in.h>
29 #include <arpa/inet.h>
60 #include "sshconnect.h"
67 #include "monitor_fdpass.h"
74 char *client_version_string = NULL;
75 char *server_version_string = NULL;
76 struct sshkey *previous_host_key = NULL;
78 static int matching_host_key_dns = 0;
80 static pid_t proxy_command_pid = 0;
83 extern Options options;
84 extern char *__progname;
86 static int show_other_keys(struct hostkeys *, struct sshkey *);
87 static void warn_changed_key(struct sshkey *);
89 /* Expand a proxy command */
91 expand_proxy_command(const char *proxy_command, const char *user,
92 const char *host, int port)
94 char *tmp, *ret, strport[NI_MAXSERV];
96 snprintf(strport, sizeof strport, "%d", port);
97 xasprintf(&tmp, "exec %s", proxy_command);
98 ret = percent_expand(tmp, "h", host, "p", strport,
99 "r", options.user, (char *)NULL);
105 * Connect to the given ssh server using a proxy command that passes a
106 * a connected fd back to us.
109 ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
110 const char *proxy_command)
112 char *command_string;
117 if ((shell = getenv("SHELL")) == NULL)
118 shell = _PATH_BSHELL;
120 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
121 fatal("Could not create socketpair to communicate with "
122 "proxy dialer: %.100s", strerror(errno));
124 command_string = expand_proxy_command(proxy_command, options.user,
126 debug("Executing proxy dialer command: %.500s", command_string);
128 /* Fork and execute the proxy command. */
129 if ((pid = fork()) == 0) {
133 /* Redirect stdin and stdout. */
135 if (dup2(sp[0], 0) < 0)
136 perror("dup2 stdin");
139 if (dup2(sp[0], 1) < 0)
140 perror("dup2 stdout");
146 * Stderr is left as it is so that error messages get
147 * printed on the user's terminal.
151 argv[2] = command_string;
155 * Execute the proxy command.
156 * Note that we gave up any extra privileges above.
158 execv(argv[0], argv);
164 fatal("fork failed: %.100s", strerror(errno));
166 free(command_string);
168 if ((sock = mm_receive_fd(sp[1])) == -1)
169 fatal("proxy dialer did not pass back a connection");
172 while (waitpid(pid, NULL, 0) == -1)
174 fatal("Couldn't wait for child: %s", strerror(errno));
176 /* Set the connection file descriptors. */
177 if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
178 return -1; /* ssh_packet_set_connection logs error */
184 * Connect to the given ssh server using a proxy command.
187 ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
188 const char *proxy_command)
190 char *command_string;
195 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
196 shell = _PATH_BSHELL;
198 /* Create pipes for communicating with the proxy. */
199 if (pipe(pin) < 0 || pipe(pout) < 0)
200 fatal("Could not create pipes to communicate with the proxy: %.100s",
203 command_string = expand_proxy_command(proxy_command, options.user,
205 debug("Executing proxy command: %.500s", command_string);
207 /* Fork and execute the proxy command. */
208 if ((pid = fork()) == 0) {
211 /* Redirect stdin and stdout. */
214 if (dup2(pin[0], 0) < 0)
215 perror("dup2 stdin");
219 if (dup2(pout[1], 1) < 0)
220 perror("dup2 stdout");
221 /* Cannot be 1 because pin allocated two descriptors. */
224 /* Stderr is left as it is so that error messages get
225 printed on the user's terminal. */
228 argv[2] = command_string;
231 /* Execute the proxy command. Note that we gave up any
232 extra privileges above. */
233 signal(SIGPIPE, SIG_DFL);
234 execv(argv[0], argv);
240 fatal("fork failed: %.100s", strerror(errno));
242 proxy_command_pid = pid; /* save pid to clean up later */
244 /* Close child side of the descriptors. */
248 /* Free the command name. */
249 free(command_string);
251 /* Set the connection file descriptors. */
252 if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
253 return -1; /* ssh_packet_set_connection logs error */
259 ssh_kill_proxy_command(void)
262 * Send SIGHUP to proxy command if used. We don't wait() in
263 * case it hangs and instead rely on init to reap the child
265 if (proxy_command_pid > 1)
266 kill(proxy_command_pid, SIGHUP);
269 #ifdef HAVE_IFADDRS_H
271 * Search a interface address list (returned from getifaddrs(3)) for an
272 * address that matches the desired address family on the specified interface.
273 * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
276 check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
277 struct sockaddr_storage *resultp, socklen_t *rlenp)
279 struct sockaddr_in6 *sa6;
280 struct sockaddr_in *sa;
281 struct in6_addr *v6addr;
282 const struct ifaddrs *ifa;
286 * Prefer addresses that are not loopback or linklocal, but use them
287 * if nothing else matches.
289 for (allow_local = 0; allow_local < 2; allow_local++) {
290 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
291 if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
292 (ifa->ifa_flags & IFF_UP) == 0 ||
293 ifa->ifa_addr->sa_family != af ||
294 strcmp(ifa->ifa_name, options.bind_interface) != 0)
296 switch (ifa->ifa_addr->sa_family) {
298 sa = (struct sockaddr_in *)ifa->ifa_addr;
299 if (!allow_local && sa->sin_addr.s_addr ==
300 htonl(INADDR_LOOPBACK))
302 if (*rlenp < sizeof(struct sockaddr_in)) {
303 error("%s: v4 addr doesn't fit",
307 *rlenp = sizeof(struct sockaddr_in);
308 memcpy(resultp, sa, *rlenp);
311 sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
312 v6addr = &sa6->sin6_addr;
314 (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
315 IN6_IS_ADDR_LOOPBACK(v6addr)))
317 if (*rlenp < sizeof(struct sockaddr_in6)) {
318 error("%s: v6 addr doesn't fit",
322 *rlenp = sizeof(struct sockaddr_in6);
323 memcpy(resultp, sa6, *rlenp);
333 * Creates a socket for use as the ssh connection.
336 ssh_create_socket(struct addrinfo *ai)
339 struct sockaddr_storage bindaddr;
340 socklen_t bindaddrlen = 0;
341 struct addrinfo hints, *res = NULL;
342 #ifdef HAVE_IFADDRS_H
343 struct ifaddrs *ifaddrs = NULL;
345 char ntop[NI_MAXHOST];
347 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
349 error("socket: %s", strerror(errno));
352 fcntl(sock, F_SETFD, FD_CLOEXEC);
354 /* Bind the socket to an alternative local IP address */
355 if (options.bind_address == NULL && options.bind_interface == NULL)
358 if (options.bind_address != NULL) {
359 memset(&hints, 0, sizeof(hints));
360 hints.ai_family = ai->ai_family;
361 hints.ai_socktype = ai->ai_socktype;
362 hints.ai_protocol = ai->ai_protocol;
363 hints.ai_flags = AI_PASSIVE;
364 if ((r = getaddrinfo(options.bind_address, NULL,
365 &hints, &res)) != 0) {
366 error("getaddrinfo: %s: %s", options.bind_address,
367 ssh_gai_strerror(r));
371 error("getaddrinfo: no addrs");
374 if (res->ai_addrlen > sizeof(bindaddr)) {
375 error("%s: addr doesn't fit", __func__);
378 memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
379 bindaddrlen = res->ai_addrlen;
380 } else if (options.bind_interface != NULL) {
381 #ifdef HAVE_IFADDRS_H
382 if ((r = getifaddrs(&ifaddrs)) != 0) {
383 error("getifaddrs: %s: %s", options.bind_interface,
387 bindaddrlen = sizeof(bindaddr);
388 if (check_ifaddrs(options.bind_interface, ai->ai_family,
389 ifaddrs, &bindaddr, &bindaddrlen) != 0) {
390 logit("getifaddrs: %s: no suitable addresses",
391 options.bind_interface);
395 error("BindInterface not supported on this platform.");
398 if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
399 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
400 error("%s: getnameinfo failed: %s", __func__,
401 ssh_gai_strerror(r));
404 if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
405 error("bind %s: %s", ntop, strerror(errno));
408 debug("%s: bound to %s", __func__, ntop);
417 #ifdef HAVE_IFADDRS_H
419 freeifaddrs(ifaddrs);
425 * Wait up to *timeoutp milliseconds for fd to be readable. Updates
426 * *timeoutp with time remaining.
427 * Returns 0 if fd ready or -1 on timeout or error (see errno).
430 waitrfd(int fd, int *timeoutp)
433 struct timeval t_start;
436 monotime_tv(&t_start);
439 for (; *timeoutp >= 0;) {
440 r = poll(&pfd, 1, *timeoutp);
442 ms_subtract_diff(&t_start, timeoutp);
446 else if (r == -1 && errno != EAGAIN)
457 timeout_connect(int sockfd, const struct sockaddr *serv_addr,
458 socklen_t addrlen, int *timeoutp)
461 socklen_t optlen = sizeof(optval);
463 /* No timeout: just do a blocking connect() */
465 return connect(sockfd, serv_addr, addrlen);
467 set_nonblock(sockfd);
468 if (connect(sockfd, serv_addr, addrlen) == 0) {
469 /* Succeeded already? */
470 unset_nonblock(sockfd);
472 } else if (errno != EINPROGRESS)
475 if (waitrfd(sockfd, timeoutp) == -1)
478 /* Completed or failed */
479 if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
480 debug("getsockopt: %s", strerror(errno));
487 unset_nonblock(sockfd);
492 * Opens a TCP/IP connection to the remote server on the given host.
493 * The address of the remote host will be returned in hostaddr.
494 * If port is 0, the default port will be used.
495 * Connection_attempts specifies the maximum number of tries (one per
496 * second). If proxy_command is non-NULL, it specifies the command (with %h
497 * and %p substituted for host and port, respectively) to use to contact
501 ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
502 struct sockaddr_storage *hostaddr, u_short port, int family,
503 int connection_attempts, int *timeout_ms, int want_keepalive)
506 int oerrno, sock = -1, attempt;
507 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
510 debug2("%s", __func__);
511 memset(ntop, 0, sizeof(ntop));
512 memset(strport, 0, sizeof(strport));
514 for (attempt = 0; attempt < connection_attempts; attempt++) {
516 /* Sleep a moment before retrying. */
518 debug("Trying again...");
521 * Loop through addresses for this host, and try each one in
522 * sequence until the connection succeeds.
524 for (ai = aitop; ai; ai = ai->ai_next) {
525 if (ai->ai_family != AF_INET &&
526 ai->ai_family != AF_INET6) {
527 errno = EAFNOSUPPORT;
530 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
531 ntop, sizeof(ntop), strport, sizeof(strport),
532 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
534 error("%s: getnameinfo failed", __func__);
538 debug("Connecting to %.200s [%.100s] port %s.",
539 host, ntop, strport);
541 /* Create a socket for connecting. */
542 sock = ssh_create_socket(ai);
544 /* Any error is already output */
549 if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
551 /* Successful connection. */
552 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
556 debug("connect to address %s port %s: %s",
557 ntop, strport, strerror(errno));
564 break; /* Successful connection. */
567 /* Return failure if we didn't get a successful connection. */
569 error("ssh: connect to host %s port %s: %s",
570 host, strport, errno == 0 ? "failure" : strerror(errno));
574 debug("Connection established.");
576 /* Set SO_KEEPALIVE if requested. */
577 if (want_keepalive &&
578 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
580 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
582 /* Set the connection. */
583 if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
584 return -1; /* ssh_packet_set_connection logs error */
590 ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
591 struct sockaddr_storage *hostaddr, u_short port, int family,
592 int connection_attempts, int *timeout_ms, int want_keepalive)
594 if (options.proxy_command == NULL) {
595 return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
596 family, connection_attempts, timeout_ms, want_keepalive);
597 } else if (strcmp(options.proxy_command, "-") == 0) {
598 if ((ssh_packet_set_connection(ssh,
599 STDIN_FILENO, STDOUT_FILENO)) == NULL)
600 return -1; /* ssh_packet_set_connection logs error */
602 } else if (options.proxy_use_fdpass) {
603 return ssh_proxy_fdpass_connect(ssh, host, port,
604 options.proxy_command);
606 return ssh_proxy_connect(ssh, host, port, options.proxy_command);
610 send_client_banner(int connection_out, int minor1)
612 /* Send our own protocol version identification. */
613 xasprintf(&client_version_string, "SSH-%d.%d-%.100s%s%s\n",
614 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
615 *options.version_addendum == '\0' ? "" : " ",
616 options.version_addendum);
617 if (atomicio(vwrite, connection_out, client_version_string,
618 strlen(client_version_string)) != strlen(client_version_string))
619 fatal("write: %.100s", strerror(errno));
620 chop(client_version_string);
621 debug("Local version string %.100s", client_version_string);
625 * Waits for the server identification string, and sends our own
626 * identification string.
629 ssh_exchange_identification(int timeout_ms)
631 char buf[256], remote_version[256]; /* must be same size! */
632 int remote_major, remote_minor, mismatch;
633 int connection_in = packet_get_connection_in();
634 int connection_out = packet_get_connection_out();
639 send_client_banner(connection_out, 0);
641 /* Read other side's version identification. */
643 for (i = 0; i < sizeof(buf) - 1; i++) {
644 if (timeout_ms > 0) {
645 rc = waitrfd(connection_in, &timeout_ms);
646 if (rc == -1 && errno == ETIMEDOUT) {
647 fatal("Connection timed out during "
649 } else if (rc == -1) {
651 __func__, strerror(errno));
655 len = atomicio(read, connection_in, &buf[i], 1);
656 if (len != 1 && errno == EPIPE)
657 fatal("ssh_exchange_identification: "
658 "Connection closed by remote host");
660 fatal("ssh_exchange_identification: "
661 "read: %.100s", strerror(errno));
662 if (buf[i] == '\r') {
665 continue; /**XXX wait for \n */
667 if (buf[i] == '\n') {
672 fatal("ssh_exchange_identification: "
673 "No banner received");
675 buf[sizeof(buf) - 1] = 0;
676 if (strncmp(buf, "SSH-", 4) == 0)
678 debug("ssh_exchange_identification: %s", buf);
680 server_version_string = xstrdup(buf);
683 * Check that the versions match. In future this might accept
684 * several versions and set appropriate flags to handle them.
686 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
687 &remote_major, &remote_minor, remote_version) != 3)
688 fatal("Bad remote protocol version identification: '%.100s'", buf);
689 debug("Remote protocol version %d.%d, remote software version %.100s",
690 remote_major, remote_minor, remote_version);
692 active_state->compat = compat_datafellows(remote_version);
695 switch (remote_major) {
699 if (remote_minor != 99)
707 fatal("Protocol major versions differ: %d vs. %d",
708 PROTOCOL_MAJOR_2, remote_major);
709 if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
710 logit("Server version \"%.100s\" uses unsafe RSA signature "
711 "scheme; disabling use of RSA keys", remote_version);
712 chop(server_version_string);
715 /* defaults to 'no' */
717 confirm(const char *prompt)
719 const char *msg, *again = "Please type 'yes' or 'no': ";
723 if (options.batch_mode)
725 for (msg = prompt;;msg = again) {
726 p = read_passphrase(msg, RP_ECHO);
729 p[strcspn(p, "\n")] = '\0';
730 if (p[0] == '\0' || strcasecmp(p, "no") == 0)
732 else if (strcasecmp(p, "yes") == 0)
741 check_host_cert(const char *host, const struct sshkey *host_key)
745 if (sshkey_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
749 if (sshbuf_len(host_key->cert->critical) != 0) {
750 error("Certificate for %s contains unsupported "
751 "critical options(s)", host);
758 sockaddr_is_local(struct sockaddr *hostaddr)
760 switch (hostaddr->sa_family) {
762 return (ntohl(((struct sockaddr_in *)hostaddr)->
763 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
765 return IN6_IS_ADDR_LOOPBACK(
766 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
773 * Prepare the hostname and ip address strings that are used to lookup
774 * host keys in known_hosts files. These may have a port number appended.
777 get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
778 u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
780 char ntop[NI_MAXHOST];
783 switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
788 addrlen = sizeof(struct sockaddr_in);
791 addrlen = sizeof(struct sockaddr_in6);
794 addrlen = sizeof(struct sockaddr);
799 * We don't have the remote ip-address for connections
800 * using a proxy command
802 if (hostfile_ipaddr != NULL) {
803 if (options.proxy_command == NULL) {
804 if (getnameinfo(hostaddr, addrlen,
805 ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
806 fatal("%s: getnameinfo failed", __func__);
807 *hostfile_ipaddr = put_host_port(ntop, port);
809 *hostfile_ipaddr = xstrdup("<no hostip for proxy "
815 * Allow the user to record the key under a different name or
816 * differentiate a non-standard port. This is useful for ssh
817 * tunneling over forwarded connections or if you run multiple
818 * sshd's on different ports on the same machine.
820 if (hostfile_hostname != NULL) {
821 if (options.host_key_alias != NULL) {
822 *hostfile_hostname = xstrdup(options.host_key_alias);
823 debug("using hostkeyalias: %s", *hostfile_hostname);
825 *hostfile_hostname = put_host_port(hostname, port);
831 * check whether the supplied host key is valid, return -1 if the key
832 * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
838 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
839 struct sshkey *host_key, int readonly,
840 char **user_hostfiles, u_int num_user_hostfiles,
841 char **system_hostfiles, u_int num_system_hostfiles)
843 HostStatus host_status;
844 HostStatus ip_status;
845 struct sshkey *raw_key = NULL;
846 char *ip = NULL, *host = NULL;
847 char hostline[1000], *hostp, *fp, *ra;
850 const struct hostkey_entry *host_found, *ip_found;
851 int len, cancelled_forwarding = 0;
852 int local = sockaddr_is_local(hostaddr);
853 int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
854 int hostkey_trusted = 0; /* Known or explicitly accepted by user */
855 struct hostkeys *host_hostkeys, *ip_hostkeys;
859 * Force accepting of the host key for loopback/localhost. The
860 * problem is that if the home directory is NFS-mounted to multiple
861 * machines, localhost will refer to a different machine in each of
862 * them, and the user will get bogus HOST_CHANGED warnings. This
863 * essentially disables host authentication for localhost; however,
864 * this is probably not a real problem.
866 if (options.no_host_authentication_for_localhost == 1 && local &&
867 options.host_key_alias == NULL) {
868 debug("Forcing accepting of host key for "
869 "loopback/localhost.");
874 * Prepare the hostname and address strings used for hostkey lookup.
875 * In some cases, these will have a port number appended.
877 get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
880 * Turn off check_host_ip if the connection is to localhost, via proxy
881 * command or if we don't have a hostname to compare with
883 if (options.check_host_ip && (local ||
884 strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
885 options.check_host_ip = 0;
887 host_hostkeys = init_hostkeys();
888 for (i = 0; i < num_user_hostfiles; i++)
889 load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
890 for (i = 0; i < num_system_hostfiles; i++)
891 load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
894 if (!want_cert && options.check_host_ip) {
895 ip_hostkeys = init_hostkeys();
896 for (i = 0; i < num_user_hostfiles; i++)
897 load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
898 for (i = 0; i < num_system_hostfiles; i++)
899 load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
903 /* Reload these as they may have changed on cert->key downgrade */
904 want_cert = sshkey_is_cert(host_key);
905 type = sshkey_type(host_key);
908 * Check if the host key is present in the user's list of known
909 * hosts or in the systemwide list.
911 host_status = check_key_in_hostkeys(host_hostkeys, host_key,
915 * Also perform check for the ip address, skip the check if we are
916 * localhost, looking for a certificate, or the hostname was an ip
917 * address to begin with.
919 if (!want_cert && ip_hostkeys != NULL) {
920 ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
922 if (host_status == HOST_CHANGED &&
923 (ip_status != HOST_CHANGED ||
925 !sshkey_equal(ip_found->key, host_found->key))))
928 ip_status = host_status;
930 switch (host_status) {
932 /* The host is known and the key matches. */
933 debug("Host '%.200s' is known and matches the %s host %s.",
934 host, type, want_cert ? "certificate" : "key");
935 debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
936 host_found->file, host_found->line);
938 !check_host_cert(options.host_key_alias == NULL ?
939 hostname : options.host_key_alias, host_key))
941 if (options.check_host_ip && ip_status == HOST_NEW) {
942 if (readonly || want_cert)
943 logit("%s host key for IP address "
944 "'%.128s' not in list of known hosts.",
946 else if (!add_host_to_hostfile(user_hostfiles[0], ip,
947 host_key, options.hash_known_hosts))
948 logit("Failed to add the %s host key for IP "
949 "address '%.128s' to the list of known "
950 "hosts (%.500s).", type, ip,
953 logit("Warning: Permanently added the %s host "
954 "key for IP address '%.128s' to the list "
955 "of known hosts.", type, ip);
956 } else if (options.visual_host_key) {
957 fp = sshkey_fingerprint(host_key,
958 options.fingerprint_hash, SSH_FP_DEFAULT);
959 ra = sshkey_fingerprint(host_key,
960 options.fingerprint_hash, SSH_FP_RANDOMART);
961 if (fp == NULL || ra == NULL)
962 fatal("%s: sshkey_fingerprint fail", __func__);
963 logit("Host key fingerprint is %s\n%s", fp, ra);
970 if (options.host_key_alias == NULL && port != 0 &&
971 port != SSH_DEFAULT_PORT) {
972 debug("checking without port identifier");
973 if (check_host_key(hostname, hostaddr, 0, host_key,
974 ROQUIET, user_hostfiles, num_user_hostfiles,
975 system_hostfiles, num_system_hostfiles) == 0) {
976 debug("found matching key w/out port");
980 if (readonly || want_cert)
982 /* The host is new. */
983 if (options.strict_host_key_checking ==
984 SSH_STRICT_HOSTKEY_YES) {
986 * User has requested strict host key checking. We
987 * will not add the host key automatically. The only
988 * alternative left is to abort.
990 error("No %s host key is known for %.200s and you "
991 "have requested strict checking.", type, host);
993 } else if (options.strict_host_key_checking ==
994 SSH_STRICT_HOSTKEY_ASK) {
995 char msg1[1024], msg2[1024];
997 if (show_other_keys(host_hostkeys, host_key))
998 snprintf(msg1, sizeof(msg1),
999 "\nbut keys of different type are already"
1000 " known for this host.");
1002 snprintf(msg1, sizeof(msg1), ".");
1004 fp = sshkey_fingerprint(host_key,
1005 options.fingerprint_hash, SSH_FP_DEFAULT);
1006 ra = sshkey_fingerprint(host_key,
1007 options.fingerprint_hash, SSH_FP_RANDOMART);
1008 if (fp == NULL || ra == NULL)
1009 fatal("%s: sshkey_fingerprint fail", __func__);
1011 if (options.verify_host_key_dns) {
1012 if (matching_host_key_dns)
1013 snprintf(msg2, sizeof(msg2),
1014 "Matching host key fingerprint"
1015 " found in DNS.\n");
1017 snprintf(msg2, sizeof(msg2),
1018 "No matching host key fingerprint"
1019 " found in DNS.\n");
1021 snprintf(msg, sizeof(msg),
1022 "The authenticity of host '%.200s (%s)' can't be "
1024 "%s key fingerprint is %s.%s%s\n%s"
1025 "Are you sure you want to continue connecting "
1027 host, ip, msg1, type, fp,
1028 options.visual_host_key ? "\n" : "",
1029 options.visual_host_key ? ra : "",
1035 hostkey_trusted = 1; /* user explicitly confirmed */
1038 * If in "new" or "off" strict mode, add the key automatically
1039 * to the local known_hosts file.
1041 if (options.check_host_ip && ip_status == HOST_NEW) {
1042 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1044 if (options.hash_known_hosts) {
1045 /* Add hash of host and IP separately */
1046 r = add_host_to_hostfile(user_hostfiles[0],
1047 host, host_key, options.hash_known_hosts) &&
1048 add_host_to_hostfile(user_hostfiles[0], ip,
1049 host_key, options.hash_known_hosts);
1051 /* Add unhashed "host,ip" */
1052 r = add_host_to_hostfile(user_hostfiles[0],
1054 options.hash_known_hosts);
1057 r = add_host_to_hostfile(user_hostfiles[0], host,
1058 host_key, options.hash_known_hosts);
1063 logit("Failed to add the host to the list of known "
1064 "hosts (%.500s).", user_hostfiles[0]);
1066 logit("Warning: Permanently added '%.200s' (%s) to the "
1067 "list of known hosts.", hostp, type);
1070 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1071 error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1072 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1073 error("The %s host key for %s is marked as revoked.", type, host);
1074 error("This could mean that a stolen key is being used to");
1075 error("impersonate this host.");
1078 * If strict host key checking is in use, the user will have
1079 * to edit the key manually and we can only abort.
1081 if (options.strict_host_key_checking !=
1082 SSH_STRICT_HOSTKEY_OFF) {
1083 error("%s host key for %.200s was revoked and you have "
1084 "requested strict checking.", type, host);
1087 goto continue_unsafe;
1092 * This is only a debug() since it is valid to have
1093 * CAs with wildcard DNS matches that don't match
1094 * all hosts that one might visit.
1096 debug("Host certificate authority does not "
1097 "match %s in %s:%lu", CA_MARKER,
1098 host_found->file, host_found->line);
1101 if (readonly == ROQUIET)
1103 if (options.check_host_ip && host_ip_differ) {
1105 if (ip_status == HOST_NEW)
1106 key_msg = "is unknown";
1107 else if (ip_status == HOST_OK)
1108 key_msg = "is unchanged";
1110 key_msg = "has a different value";
1111 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1112 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1113 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1114 error("The %s host key for %s has changed,", type, host);
1115 error("and the key for the corresponding IP address %s", ip);
1116 error("%s. This could either mean that", key_msg);
1117 error("DNS SPOOFING is happening or the IP address for the host");
1118 error("and its host key have changed at the same time.");
1119 if (ip_status != HOST_NEW)
1120 error("Offending key for IP in %s:%lu",
1121 ip_found->file, ip_found->line);
1123 /* The host key has changed. */
1124 warn_changed_key(host_key);
1125 error("Add correct host key in %.100s to get rid of this message.",
1127 error("Offending %s key in %s:%lu",
1128 sshkey_type(host_found->key),
1129 host_found->file, host_found->line);
1132 * If strict host key checking is in use, the user will have
1133 * to edit the key manually and we can only abort.
1135 if (options.strict_host_key_checking !=
1136 SSH_STRICT_HOSTKEY_OFF) {
1137 error("%s host key for %.200s has changed and you have "
1138 "requested strict checking.", type, host);
1144 * If strict host key checking has not been requested, allow
1145 * the connection but without MITM-able authentication or
1148 if (options.password_authentication) {
1149 error("Password authentication is disabled to avoid "
1150 "man-in-the-middle attacks.");
1151 options.password_authentication = 0;
1152 cancelled_forwarding = 1;
1154 if (options.kbd_interactive_authentication) {
1155 error("Keyboard-interactive authentication is disabled"
1156 " to avoid man-in-the-middle attacks.");
1157 options.kbd_interactive_authentication = 0;
1158 options.challenge_response_authentication = 0;
1159 cancelled_forwarding = 1;
1161 if (options.challenge_response_authentication) {
1162 error("Challenge/response authentication is disabled"
1163 " to avoid man-in-the-middle attacks.");
1164 options.challenge_response_authentication = 0;
1165 cancelled_forwarding = 1;
1167 if (options.forward_agent) {
1168 error("Agent forwarding is disabled to avoid "
1169 "man-in-the-middle attacks.");
1170 options.forward_agent = 0;
1171 cancelled_forwarding = 1;
1173 if (options.forward_x11) {
1174 error("X11 forwarding is disabled to avoid "
1175 "man-in-the-middle attacks.");
1176 options.forward_x11 = 0;
1177 cancelled_forwarding = 1;
1179 if (options.num_local_forwards > 0 ||
1180 options.num_remote_forwards > 0) {
1181 error("Port forwarding is disabled to avoid "
1182 "man-in-the-middle attacks.");
1183 options.num_local_forwards =
1184 options.num_remote_forwards = 0;
1185 cancelled_forwarding = 1;
1187 if (options.tun_open != SSH_TUNMODE_NO) {
1188 error("Tunnel forwarding is disabled to avoid "
1189 "man-in-the-middle attacks.");
1190 options.tun_open = SSH_TUNMODE_NO;
1191 cancelled_forwarding = 1;
1193 if (options.exit_on_forward_failure && cancelled_forwarding)
1194 fatal("Error: forwarding disabled due to host key "
1198 * XXX Should permit the user to change to use the new id.
1199 * This could be done by converting the host key to an
1200 * identifying sentence, tell that the host identifies itself
1201 * by that sentence, and ask the user if he/she wishes to
1202 * accept the authentication.
1206 fatal("internal error");
1210 if (options.check_host_ip && host_status != HOST_CHANGED &&
1211 ip_status == HOST_CHANGED) {
1212 snprintf(msg, sizeof(msg),
1213 "Warning: the %s host key for '%.200s' "
1214 "differs from the key for the IP address '%.128s'"
1215 "\nOffending key for IP in %s:%lu",
1216 type, host, ip, ip_found->file, ip_found->line);
1217 if (host_status == HOST_OK) {
1219 snprintf(msg + len, sizeof(msg) - len,
1220 "\nMatching host key in %s:%lu",
1221 host_found->file, host_found->line);
1223 if (options.strict_host_key_checking ==
1224 SSH_STRICT_HOSTKEY_ASK) {
1225 strlcat(msg, "\nAre you sure you want "
1226 "to continue connecting (yes/no)? ", sizeof(msg));
1229 } else if (options.strict_host_key_checking !=
1230 SSH_STRICT_HOSTKEY_OFF) {
1232 error("Exiting, you have requested strict checking.");
1239 if (!hostkey_trusted && options.update_hostkeys) {
1240 debug("%s: hostkey not known or explicitly trusted: "
1241 "disabling UpdateHostkeys", __func__);
1242 options.update_hostkeys = 0;
1247 if (host_hostkeys != NULL)
1248 free_hostkeys(host_hostkeys);
1249 if (ip_hostkeys != NULL)
1250 free_hostkeys(ip_hostkeys);
1254 if (want_cert && host_status != HOST_REVOKED) {
1256 * No matching certificate. Downgrade cert to raw key and
1259 debug("No matching CA found. Retry with plain key");
1260 if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1261 fatal("%s: sshkey_from_private: %s",
1262 __func__, ssh_err(r));
1263 if ((r = sshkey_drop_cert(raw_key)) != 0)
1264 fatal("Couldn't drop certificate: %s", ssh_err(r));
1268 sshkey_free(raw_key);
1271 if (host_hostkeys != NULL)
1272 free_hostkeys(host_hostkeys);
1273 if (ip_hostkeys != NULL)
1274 free_hostkeys(ip_hostkeys);
1278 /* returns 0 if key verifies or -1 if key does NOT verify */
1280 verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1283 int r = -1, flags = 0;
1284 char valid[64], *fp = NULL, *cafp = NULL;
1285 struct sshkey *plain = NULL;
1287 if ((fp = sshkey_fingerprint(host_key,
1288 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1289 error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1294 if (sshkey_is_cert(host_key)) {
1295 if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1296 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1297 error("%s: fingerprint CA key: %s",
1298 __func__, ssh_err(r));
1302 sshkey_format_cert_validity(host_key->cert,
1303 valid, sizeof(valid));
1304 debug("Server host certificate: %s %s, serial %llu "
1305 "ID \"%s\" CA %s %s valid %s",
1306 sshkey_ssh_name(host_key), fp,
1307 (unsigned long long)host_key->cert->serial,
1308 host_key->cert->key_id,
1309 sshkey_ssh_name(host_key->cert->signature_key), cafp,
1311 for (i = 0; i < host_key->cert->nprincipals; i++) {
1312 debug2("Server host certificate hostname: %s",
1313 host_key->cert->principals[i]);
1316 debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1319 if (sshkey_equal(previous_host_key, host_key)) {
1320 debug2("%s: server host key %s %s matches cached key",
1321 __func__, sshkey_type(host_key), fp);
1326 /* Check in RevokedHostKeys file if specified */
1327 if (options.revoked_host_keys != NULL) {
1328 r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1331 break; /* not revoked */
1332 case SSH_ERR_KEY_REVOKED:
1333 error("Host key %s %s revoked by file %s",
1334 sshkey_type(host_key), fp,
1335 options.revoked_host_keys);
1339 error("Error checking host key %s %s in "
1340 "revoked keys file %s: %s", sshkey_type(host_key),
1341 fp, options.revoked_host_keys, ssh_err(r));
1347 if (options.verify_host_key_dns) {
1349 * XXX certs are not yet supported for DNS, so downgrade
1350 * them and try the plain key.
1352 if ((r = sshkey_from_private(host_key, &plain)) != 0)
1354 if (sshkey_is_cert(plain))
1355 sshkey_drop_cert(plain);
1356 if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1357 if (flags & DNS_VERIFY_FOUND) {
1358 if (options.verify_host_key_dns == 1 &&
1359 flags & DNS_VERIFY_MATCH &&
1360 flags & DNS_VERIFY_SECURE) {
1364 if (flags & DNS_VERIFY_MATCH) {
1365 matching_host_key_dns = 1;
1367 warn_changed_key(plain);
1368 error("Update the SSHFP RR in DNS "
1369 "with the new host key to get rid "
1370 "of this message.");
1375 r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1376 options.user_hostfiles, options.num_user_hostfiles,
1377 options.system_hostfiles, options.num_system_hostfiles);
1383 if (r == 0 && host_key != NULL) {
1384 sshkey_free(previous_host_key);
1385 r = sshkey_from_private(host_key, &previous_host_key);
1392 * Starts a dialog with the server, and authenticates the current user on the
1393 * server. This does not need any extra privileges. The basic connection
1394 * to the server must already have been established before this is called.
1395 * If login fails, this function prints an error and never returns.
1396 * This function does not require super-user privileges.
1399 ssh_login(Sensitive *sensitive, const char *orighost,
1400 struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1403 char *server_user, *local_user;
1405 local_user = xstrdup(pw->pw_name);
1406 server_user = options.user ? options.user : local_user;
1408 /* Convert the user-supplied hostname into all lowercase. */
1409 host = xstrdup(orighost);
1412 /* Exchange protocol version identification strings with the server. */
1413 ssh_exchange_identification(timeout_ms);
1415 /* Put the connection into non-blocking mode. */
1416 packet_set_nonblocking();
1419 /* authenticate user */
1420 debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1421 ssh_kex2(host, hostaddr, port);
1422 ssh_userauth2(local_user, server_user, host, sensitive);
1427 ssh_put_password(char *password)
1432 if (datafellows & SSH_BUG_PASSWORDPAD) {
1433 packet_put_cstring(password);
1436 size = ROUNDUP(strlen(password) + 1, 32);
1437 padded = xcalloc(1, size);
1438 strlcpy(padded, password, size);
1439 packet_put_string(padded, size);
1440 explicit_bzero(padded, size);
1444 /* print all known host keys for a given host, but skip keys of given type */
1446 show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1458 const struct hostkey_entry *found;
1460 for (i = 0; type[i] != -1; i++) {
1461 if (type[i] == key->type)
1463 if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1465 fp = sshkey_fingerprint(found->key,
1466 options.fingerprint_hash, SSH_FP_DEFAULT);
1467 ra = sshkey_fingerprint(found->key,
1468 options.fingerprint_hash, SSH_FP_RANDOMART);
1469 if (fp == NULL || ra == NULL)
1470 fatal("%s: sshkey_fingerprint fail", __func__);
1471 logit("WARNING: %s key found for host %s\n"
1473 "%s key fingerprint %s.",
1474 sshkey_type(found->key),
1475 found->host, found->file, found->line,
1476 sshkey_type(found->key), fp);
1477 if (options.visual_host_key)
1487 warn_changed_key(struct sshkey *host_key)
1491 fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1494 fatal("%s: sshkey_fingerprint fail", __func__);
1496 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1497 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1498 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1499 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1500 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1501 error("It is also possible that a host key has just been changed.");
1502 error("The fingerprint for the %s key sent by the remote host is\n%s.",
1503 sshkey_type(host_key), fp);
1504 error("Please contact your system administrator.");
1510 * Execute a local command
1513 ssh_local_cmd(const char *args)
1518 void (*osighand)(int);
1520 if (!options.permit_local_command ||
1521 args == NULL || !*args)
1524 if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1525 shell = _PATH_BSHELL;
1527 osighand = signal(SIGCHLD, SIG_DFL);
1530 signal(SIGPIPE, SIG_DFL);
1531 debug3("Executing %s -c \"%s\"", shell, args);
1532 execl(shell, shell, "-c", args, (char *)NULL);
1533 error("Couldn't execute %s -c \"%s\": %s",
1534 shell, args, strerror(errno));
1536 } else if (pid == -1)
1537 fatal("fork failed: %.100s", strerror(errno));
1538 while (waitpid(pid, &status, 0) == -1)
1540 fatal("Couldn't wait for child: %s", strerror(errno));
1541 signal(SIGCHLD, osighand);
1543 if (!WIFEXITED(status))
1546 return (WEXITSTATUS(status));
1550 maybe_add_key_to_agent(char *authfile, const struct sshkey *private,
1551 char *comment, char *passphrase)
1553 int auth_sock = -1, r;
1555 if (options.add_keys_to_agent == 0)
1558 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1559 debug3("no authentication agent, not adding key");
1563 if (options.add_keys_to_agent == 2 &&
1564 !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1565 debug3("user denied adding this key");
1570 if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1571 (options.add_keys_to_agent == 3), 0)) == 0)
1572 debug("identity added to agent: %s", authfile);
1574 debug("could not add identity to agent: %s (%d)", authfile, r);