2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Created: Sat Mar 18 22:15:47 1995 ylo
6 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
9 * SSH2 support added by Markus Friedl.
13 RCSID("$OpenBSD: sshconnect.c,v 1.68 2000/04/14 10:30:33 markus Exp $");
16 #include <openssl/bn.h>
17 #include <openssl/rsa.h>
18 #include <openssl/dsa.h>
19 #include <openssl/md5.h>
44 #include "myproposal.h"
49 /* Session id for the current session. */
50 unsigned char session_id[16];
52 /* authentications supported by server */
53 unsigned int supported_authentications;
55 static char *client_version_string = NULL;
56 static char *server_version_string = NULL;
58 extern Options options;
59 extern char *__progname;
62 * Connect to the given ssh server using a proxy command.
65 ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid,
66 const char *proxy_command)
73 char strport[NI_MAXSERV];
75 /* Convert the port number into a string. */
76 snprintf(strport, sizeof strport, "%hu", port);
78 /* Build the final command string in the buffer by making the
79 appropriate substitutions to the given proxy command. */
80 buffer_init(&command);
81 for (cp = proxy_command; *cp; cp++) {
82 if (cp[0] == '%' && cp[1] == '%') {
83 buffer_append(&command, "%", 1);
87 if (cp[0] == '%' && cp[1] == 'h') {
88 buffer_append(&command, host, strlen(host));
92 if (cp[0] == '%' && cp[1] == 'p') {
93 buffer_append(&command, strport, strlen(strport));
97 buffer_append(&command, cp, 1);
99 buffer_append(&command, "\0", 1);
101 /* Get the final command string. */
102 command_string = buffer_ptr(&command);
104 /* Create pipes for communicating with the proxy. */
105 if (pipe(pin) < 0 || pipe(pout) < 0)
106 fatal("Could not create pipes to communicate with the proxy: %.100s",
109 debug("Executing proxy command: %.500s", command_string);
111 /* Fork and execute the proxy command. */
112 if ((pid = fork()) == 0) {
115 /* Child. Permanently give up superuser privileges. */
116 permanently_set_uid(original_real_uid);
118 /* Redirect stdin and stdout. */
121 if (dup2(pin[0], 0) < 0)
122 perror("dup2 stdin");
126 if (dup2(pout[1], 1) < 0)
127 perror("dup2 stdout");
128 /* Cannot be 1 because pin allocated two descriptors. */
131 /* Stderr is left as it is so that error messages get
132 printed on the user's terminal. */
135 argv[2] = command_string;
138 /* Execute the proxy command. Note that we gave up any
139 extra privileges above. */
140 execv("/bin/sh", argv);
146 fatal("fork failed: %.100s", strerror(errno));
148 /* Close child side of the descriptors. */
152 /* Free the command name. */
153 buffer_free(&command);
155 /* Set the connection file descriptors. */
156 packet_set_connection(pout[0], pin[1]);
162 * Creates a (possibly privileged) socket for use as the ssh connection.
165 ssh_create_socket(uid_t original_real_uid, int privileged, int family)
170 * If we are running as root and want to connect to a privileged
171 * port, bind our own socket to a privileged port.
174 int p = IPPORT_RESERVED - 1;
175 sock = rresvport_af(&p, family);
177 error("rresvport: af=%d %.100s", family, strerror(errno));
179 debug("Allocated local port %d.", p);
182 * Just create an ordinary socket on arbitrary port. We use
183 * the user's uid to create the socket.
185 temporarily_use_uid(original_real_uid);
186 sock = socket(family, SOCK_STREAM, 0);
188 error("socket: %.100s", strerror(errno));
195 * Opens a TCP/IP connection to the remote server on the given host.
196 * The address of the remote host will be returned in hostaddr.
197 * If port is 0, the default port will be used. If anonymous is zero,
198 * a privileged port will be allocated to make the connection.
199 * This requires super-user privileges if anonymous is false.
200 * Connection_attempts specifies the maximum number of tries (one per
201 * second). If proxy_command is non-NULL, it specifies the command (with %h
202 * and %p substituted for host and port, respectively) to use to contact
206 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
207 u_short port, int connection_attempts,
208 int anonymous, uid_t original_real_uid,
209 const char *proxy_command)
211 int sock = -1, attempt;
213 struct addrinfo hints, *ai, *aitop;
214 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
216 struct linger linger;
218 debug("ssh_connect: getuid %d geteuid %d anon %d",
219 (int) getuid(), (int) geteuid(), anonymous);
221 /* Get default port if port has not been set. */
223 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
225 port = ntohs(sp->s_port);
227 port = SSH_DEFAULT_PORT;
229 /* If a proxy command is given, connect using it. */
230 if (proxy_command != NULL)
231 return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
233 /* No proxy command. */
235 memset(&hints, 0, sizeof(hints));
236 hints.ai_family = IPv4or6;
237 hints.ai_socktype = SOCK_STREAM;
238 snprintf(strport, sizeof strport, "%d", port);
239 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
240 fatal("%s: %.100s: %s", __progname, host,
241 gai_strerror(gaierr));
244 * Try to connect several times. On some machines, the first time
245 * will sometimes fail. In general socket code appears to behave
246 * quite magically on many machines.
248 for (attempt = 0; attempt < connection_attempts; attempt++) {
250 debug("Trying again...");
252 /* Loop through addresses for this host, and try each one in
253 sequence until the connection succeeds. */
254 for (ai = aitop; ai; ai = ai->ai_next) {
255 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
257 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
258 ntop, sizeof(ntop), strport, sizeof(strport),
259 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
260 error("ssh_connect: getnameinfo failed");
263 debug("Connecting to %.200s [%.100s] port %s.",
264 host, ntop, strport);
266 /* Create a socket for connecting. */
267 sock = ssh_create_socket(original_real_uid,
268 !anonymous && geteuid() == 0 && port < IPPORT_RESERVED,
273 /* Connect to the host. We use the user's uid in the
274 * hope that it will help with tcp_wrappers showing
275 * the remote uid as root.
277 temporarily_use_uid(original_real_uid);
278 if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
279 /* Successful connection. */
280 memcpy(hostaddr, ai->ai_addr, sizeof(*(ai->ai_addr)));
284 debug("connect: %.100s", strerror(errno));
287 * Close the failed socket; there appear to
288 * be some problems when reusing a socket for
289 * which connect() has already returned an
292 shutdown(sock, SHUT_RDWR);
297 break; /* Successful connection. */
299 /* Sleep a moment before retrying. */
305 /* Return failure if we didn't get a successful connection. */
306 if (attempt >= connection_attempts)
309 debug("Connection established.");
312 * Set socket options. We would like the socket to disappear as soon
313 * as it has been closed for whatever reason.
315 /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
318 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
320 /* Set the connection. */
321 packet_set_connection(sock, sock);
327 * Checks if the user has an authentication agent, and if so, tries to
328 * authenticate using the agent.
331 try_agent_authentication()
335 AuthenticationConnection *auth;
336 unsigned char response[16];
338 BIGNUM *e, *n, *challenge;
340 /* Get connection to the agent. */
341 auth = ssh_get_authentication_connection();
347 challenge = BN_new();
349 /* Loop through identities served by the agent. */
350 for (status = ssh_get_first_identity(auth, e, n, &comment);
352 status = ssh_get_next_identity(auth, e, n, &comment)) {
355 /* Try this identity. */
356 debug("Trying RSA authentication via agent with '%.100s'", comment);
359 /* Tell the server that we are willing to authenticate using this key. */
360 packet_start(SSH_CMSG_AUTH_RSA);
361 packet_put_bignum(n);
365 /* Wait for server's response. */
366 type = packet_read(&plen);
368 /* The server sends failure if it doesn\'t like our key or
369 does not support RSA authentication. */
370 if (type == SSH_SMSG_FAILURE) {
371 debug("Server refused our key.");
374 /* Otherwise it should have sent a challenge. */
375 if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
376 packet_disconnect("Protocol error during RSA authentication: %d",
379 packet_get_bignum(challenge, &clen);
381 packet_integrity_check(plen, clen, type);
383 debug("Received RSA challenge from server.");
385 /* Ask the agent to decrypt the challenge. */
386 if (!ssh_decrypt_challenge(auth, e, n, challenge,
387 session_id, 1, response)) {
388 /* The agent failed to authenticate this identifier although it
389 advertised it supports this. Just return a wrong value. */
390 log("Authentication agent failed to decrypt challenge.");
391 memset(response, 0, sizeof(response));
393 debug("Sending response to RSA challenge.");
395 /* Send the decrypted challenge back to the server. */
396 packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
397 for (i = 0; i < 16; i++)
398 packet_put_char(response[i]);
402 /* Wait for response from the server. */
403 type = packet_read(&plen);
405 /* The server returns success if it accepted the authentication. */
406 if (type == SSH_SMSG_SUCCESS) {
407 debug("RSA authentication accepted by server.");
410 BN_clear_free(challenge);
413 /* Otherwise it should return failure. */
414 if (type != SSH_SMSG_FAILURE)
415 packet_disconnect("Protocol error waiting RSA auth response: %d",
421 BN_clear_free(challenge);
423 debug("RSA authentication using agent refused.");
428 * Computes the proper response to a RSA challenge, and sends the response to
432 respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv)
434 unsigned char buf[32], response[16];
438 /* Decrypt the challenge using the private key. */
439 rsa_private_decrypt(challenge, challenge, prv);
441 /* Compute the response. */
442 /* The response is MD5 of decrypted challenge plus session id. */
443 len = BN_num_bytes(challenge);
444 if (len <= 0 || len > sizeof(buf))
445 packet_disconnect("respond_to_rsa_challenge: bad challenge length %d",
448 memset(buf, 0, sizeof(buf));
449 BN_bn2bin(challenge, buf + sizeof(buf) - len);
451 MD5_Update(&md, buf, 32);
452 MD5_Update(&md, session_id, 16);
453 MD5_Final(response, &md);
455 debug("Sending response to host key RSA challenge.");
457 /* Send the response back to the server. */
458 packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
459 for (i = 0; i < 16; i++)
460 packet_put_char(response[i]);
464 memset(buf, 0, sizeof(buf));
465 memset(response, 0, sizeof(response));
466 memset(&md, 0, sizeof(md));
470 * Checks if the user has authentication file, and if so, tries to authenticate
474 try_rsa_authentication(const char *authfile)
479 char *passphrase, *comment;
483 /* Try to load identification for the authentication key. */
484 public_key = RSA_new();
485 if (!load_public_key(authfile, public_key, &comment)) {
486 RSA_free(public_key);
487 /* Could not load it. Fail. */
490 debug("Trying RSA authentication with key '%.100s'", comment);
492 /* Tell the server that we are willing to authenticate using this key. */
493 packet_start(SSH_CMSG_AUTH_RSA);
494 packet_put_bignum(public_key->n);
498 /* We no longer need the public key. */
499 RSA_free(public_key);
501 /* Wait for server's response. */
502 type = packet_read(&plen);
505 * The server responds with failure if it doesn\'t like our key or
506 * doesn\'t support RSA authentication.
508 if (type == SSH_SMSG_FAILURE) {
509 debug("Server refused our key.");
513 /* Otherwise, the server should respond with a challenge. */
514 if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
515 packet_disconnect("Protocol error during RSA authentication: %d", type);
517 /* Get the challenge from the packet. */
518 challenge = BN_new();
519 packet_get_bignum(challenge, &clen);
521 packet_integrity_check(plen, clen, type);
523 debug("Received RSA challenge from server.");
525 private_key = RSA_new();
527 * Load the private key. Try first with empty passphrase; if it
528 * fails, ask for a passphrase.
530 if (!load_private_key(authfile, "", private_key, NULL)) {
532 snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ",
534 if (!options.batch_mode)
535 passphrase = read_passphrase(buf, 0);
537 debug("Will not query passphrase for %.100s in batch mode.",
539 passphrase = xstrdup("");
542 /* Load the authentication file using the pasphrase. */
543 if (!load_private_key(authfile, passphrase, private_key, NULL)) {
544 memset(passphrase, 0, strlen(passphrase));
546 error("Bad passphrase.");
548 /* Send a dummy response packet to avoid protocol error. */
549 packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
550 for (i = 0; i < 16; i++)
555 /* Expect the server to reject it... */
556 packet_read_expect(&plen, SSH_SMSG_FAILURE);
560 /* Destroy the passphrase. */
561 memset(passphrase, 0, strlen(passphrase));
564 /* We no longer need the comment. */
567 /* Compute and send a response to the challenge. */
568 respond_to_rsa_challenge(challenge, private_key);
570 /* Destroy the private key. */
571 RSA_free(private_key);
573 /* We no longer need the challenge. */
574 BN_clear_free(challenge);
576 /* Wait for response from the server. */
577 type = packet_read(&plen);
578 if (type == SSH_SMSG_SUCCESS) {
579 debug("RSA authentication accepted by server.");
582 if (type != SSH_SMSG_FAILURE)
583 packet_disconnect("Protocol error waiting RSA auth response: %d", type);
584 debug("RSA authentication refused.");
589 * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
590 * authentication and RSA host authentication.
593 try_rhosts_rsa_authentication(const char *local_user, RSA * host_key)
599 debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
601 /* Tell the server that we are willing to authenticate using this key. */
602 packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
603 packet_put_string(local_user, strlen(local_user));
604 packet_put_int(BN_num_bits(host_key->n));
605 packet_put_bignum(host_key->e);
606 packet_put_bignum(host_key->n);
610 /* Wait for server's response. */
611 type = packet_read(&plen);
613 /* The server responds with failure if it doesn't admit our
614 .rhosts authentication or doesn't know our host key. */
615 if (type == SSH_SMSG_FAILURE) {
616 debug("Server refused our rhosts authentication or host key.");
619 /* Otherwise, the server should respond with a challenge. */
620 if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
621 packet_disconnect("Protocol error during RSA authentication: %d", type);
623 /* Get the challenge from the packet. */
624 challenge = BN_new();
625 packet_get_bignum(challenge, &clen);
627 packet_integrity_check(plen, clen, type);
629 debug("Received RSA challenge for host key from server.");
631 /* Compute a response to the challenge. */
632 respond_to_rsa_challenge(challenge, host_key);
634 /* We no longer need the challenge. */
635 BN_clear_free(challenge);
637 /* Wait for response from the server. */
638 type = packet_read(&plen);
639 if (type == SSH_SMSG_SUCCESS) {
640 debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
643 if (type != SSH_SMSG_FAILURE)
644 packet_disconnect("Protocol error waiting RSA auth response: %d", type);
645 debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
651 try_kerberos_authentication()
653 KTEXT_ST auth; /* Kerberos data */
660 Key_schedule schedule;
661 u_long checksum, cksum;
663 struct sockaddr_in local, foreign;
666 /* Don't do anything if we don't have any tickets. */
667 if (stat(tkt_string(), &st) < 0)
670 strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
672 realm = (char *) krb_realmofhost(get_canonical_hostname());
674 debug("Kerberos V4: no realm for %s", get_canonical_hostname());
677 /* This can really be anything. */
678 checksum = (u_long) getpid();
680 r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
682 debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]);
685 /* Get session key to decrypt the server's reply with. */
686 r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
688 debug("get_cred failed: %s", krb_err_txt[r]);
691 des_key_sched((des_cblock *) cred.session, schedule);
693 /* Send authentication info to server. */
694 packet_start(SSH_CMSG_AUTH_KERBEROS);
695 packet_put_string((char *) auth.dat, auth.length);
699 /* Zero the buffer. */
700 (void) memset(auth.dat, 0, MAX_KTXT_LEN);
702 slen = sizeof(local);
703 memset(&local, 0, sizeof(local));
704 if (getsockname(packet_get_connection_in(),
705 (struct sockaddr *) & local, &slen) < 0)
706 debug("getsockname failed: %s", strerror(errno));
708 slen = sizeof(foreign);
709 memset(&foreign, 0, sizeof(foreign));
710 if (getpeername(packet_get_connection_in(),
711 (struct sockaddr *) & foreign, &slen) < 0) {
712 debug("getpeername failed: %s", strerror(errno));
715 /* Get server reply. */
716 type = packet_read(&plen);
718 case SSH_SMSG_FAILURE:
719 /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
720 debug("Kerberos V4 authentication failed.");
724 case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
725 /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
726 debug("Kerberos V4 authentication accepted.");
728 /* Get server's response. */
729 reply = packet_get_string((unsigned int *) &auth.length);
730 memcpy(auth.dat, reply, auth.length);
733 packet_integrity_check(plen, 4 + auth.length, type);
736 * If his response isn't properly encrypted with the session
737 * key, and the decrypted checksum fails to match, he's
740 r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
741 &foreign, &local, &msg_data);
743 debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]);
744 packet_disconnect("Kerberos V4 challenge failed!");
746 /* Fetch the (incremented) checksum that we supplied in the request. */
747 (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum));
748 cksum = ntohl(cksum);
750 /* If it matches, we're golden. */
751 if (cksum == checksum + 1) {
752 debug("Kerberos V4 challenge successful.");
755 packet_disconnect("Kerberos V4 challenge failed!");
759 packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
771 char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
776 /* Don't do anything if we don't have any tickets. */
777 if (stat(tkt_string(), &st) < 0)
780 creds = xmalloc(sizeof(*creds));
782 if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) {
783 debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]);
786 if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
787 debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]);
790 if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
791 debug("Kerberos V4 ticket expired: %s", TKT_FILE);
794 creds_to_radix(creds, (unsigned char *)buffer);
797 packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
798 packet_put_string(buffer, strlen(buffer));
802 type = packet_read(&plen);
804 if (type == SSH_SMSG_FAILURE)
805 debug("Kerberos TGT for realm %s rejected.", prealm);
806 else if (type != SSH_SMSG_SUCCESS)
807 packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
813 send_afs_tokens(void)
816 struct ViceIoctl parms;
817 struct ClearToken ct;
818 int i, type, len, plen;
819 char buf[2048], *p, *server_cell;
822 /* Move over ktc_GetToken, here's something leaner. */
823 for (i = 0; i < 100; i++) { /* just in case */
824 parms.in = (char *) &i;
825 parms.in_size = sizeof(i);
827 parms.out_size = sizeof(buf);
828 if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0)
832 /* Get secret token. */
833 memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
834 if (creds.ticket_st.length > MAX_KTXT_LEN)
836 p += sizeof(unsigned int);
837 memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
838 p += creds.ticket_st.length;
840 /* Get clear token. */
841 memcpy(&len, p, sizeof(len));
842 if (len != sizeof(struct ClearToken))
847 p += sizeof(len); /* primary flag */
850 /* Flesh out our credentials. */
851 strlcpy(creds.service, "afs", sizeof creds.service);
852 creds.instance[0] = '\0';
853 strlcpy(creds.realm, server_cell, REALM_SZ);
854 memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
855 creds.issue_date = ct.BeginTimestamp;
856 creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
857 creds.kvno = ct.AuthHandle;
858 snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId);
859 creds.pinst[0] = '\0';
861 /* Encode token, ship it off. */
862 if (!creds_to_radix(&creds, (unsigned char*) buffer))
864 packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
865 packet_put_string(buffer, strlen(buffer));
869 /* Roger, Roger. Clearance, Clarence. What's your vector,
871 type = packet_read(&plen);
873 if (type == SSH_SMSG_FAILURE)
874 debug("AFS token for cell %s rejected.", server_cell);
875 else if (type != SSH_SMSG_SUCCESS)
876 packet_disconnect("Protocol error on AFS token response: %d", type);
883 * Tries to authenticate with any string-based challenge/response system.
884 * Note that the client code is not tied to s/key or TIS.
887 try_skey_authentication()
892 char *challenge, *response;
894 debug("Doing skey authentication.");
896 /* request a challenge */
897 packet_start(SSH_CMSG_AUTH_TIS);
901 type = packet_read(&payload_len);
902 if (type != SSH_SMSG_FAILURE &&
903 type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
904 packet_disconnect("Protocol error: got %d in response "
905 "to skey-auth", type);
907 if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
908 debug("No challenge for skey authentication.");
911 challenge = packet_get_string(&clen);
912 packet_integrity_check(payload_len, (4 + clen), type);
913 if (options.cipher == SSH_CIPHER_NONE)
914 log("WARNING: Encryption is disabled! "
915 "Reponse will be transmitted in clear text.");
916 fprintf(stderr, "%s\n", challenge);
919 for (i = 0; i < options.number_of_password_prompts; i++) {
921 error("Permission denied, please try again.");
922 response = read_passphrase("Response: ", 0);
923 packet_start(SSH_CMSG_AUTH_TIS_RESPONSE);
924 packet_put_string(response, strlen(response));
925 memset(response, 0, strlen(response));
929 type = packet_read(&payload_len);
930 if (type == SSH_SMSG_SUCCESS)
932 if (type != SSH_SMSG_FAILURE)
933 packet_disconnect("Protocol error: got %d in response "
934 "to skey-auth-reponse", type);
941 * Tries to authenticate with plain passwd authentication.
944 try_password_authentication(char *prompt)
946 int type, i, payload_len;
949 debug("Doing password authentication.");
950 if (options.cipher == SSH_CIPHER_NONE)
951 log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
952 for (i = 0; i < options.number_of_password_prompts; i++) {
954 error("Permission denied, please try again.");
955 password = read_passphrase(prompt, 0);
956 packet_start(SSH_CMSG_AUTH_PASSWORD);
957 packet_put_string(password, strlen(password));
958 memset(password, 0, strlen(password));
963 type = packet_read(&payload_len);
964 if (type == SSH_SMSG_SUCCESS)
966 if (type != SSH_SMSG_FAILURE)
967 packet_disconnect("Protocol error: got %d in response to passwd auth", type);
978 if(*t == '\n' || *t == '\r') {
989 * Waits for the server identification string, and sends our own
990 * identification string.
993 ssh_exchange_identification()
995 char buf[256], remote_version[256]; /* must be same size! */
996 int remote_major, remote_minor, i, mismatch;
997 int connection_in = packet_get_connection_in();
998 int connection_out = packet_get_connection_out();
1000 /* Read other side\'s version identification. */
1001 for (i = 0; i < sizeof(buf) - 1; i++) {
1002 int len = read(connection_in, &buf[i], 1);
1004 fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
1006 fatal("ssh_exchange_identification: Connection closed by remote host");
1007 if (buf[i] == '\r') {
1010 continue; /**XXX wait for \n */
1012 if (buf[i] == '\n') {
1017 buf[sizeof(buf) - 1] = 0;
1018 server_version_string = xstrdup(buf);
1021 * Check that the versions match. In future this might accept
1022 * several versions and set appropriate flags to handle them.
1024 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
1025 &remote_major, &remote_minor, remote_version) != 3)
1026 fatal("Bad remote protocol version identification: '%.100s'", buf);
1027 debug("Remote protocol version %d.%d, remote software version %.100s",
1028 remote_major, remote_minor, remote_version);
1030 compat_datafellows(remote_version);
1033 switch(remote_major) {
1035 if (remote_minor == 99 &&
1036 (options.protocol & SSH_PROTO_2) &&
1037 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
1041 if (!(options.protocol & SSH_PROTO_1)) {
1045 if (remote_minor < 3) {
1046 fatal("Remote machine has too old SSH software version.");
1047 } else if (remote_minor == 3) {
1048 /* We speak 1.3, too. */
1050 if (options.forward_agent) {
1051 log("Agent forwarding disabled for protocol 1.3");
1052 options.forward_agent = 0;
1057 if (options.protocol & SSH_PROTO_2) {
1067 fatal("Protocol major versions differ: %d vs. %d",
1068 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1071 /* Send our own protocol version identification. */
1072 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1073 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1074 compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1,
1076 if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1077 fatal("write: %.100s", strerror(errno));
1078 client_version_string = xstrdup(buf);
1079 chop(client_version_string);
1080 chop(server_version_string);
1081 debug("Local version string %.100s", client_version_string);
1085 read_yes_or_no(const char *prompt, int defval)
1094 f = fopen("/dev/tty", "rw");
1102 fprintf(stderr, "%s", prompt);
1103 if (fgets(buf, sizeof(buf), f) == NULL) {
1104 /* Print a newline (the prompt probably didn\'t have one). */
1105 fprintf(stderr, "\n");
1106 strlcpy(buf, "no", sizeof buf);
1108 /* Remove newline from response. */
1109 if (strchr(buf, '\n'))
1110 *strchr(buf, '\n') = 0;
1114 if (strcmp(buf, "yes") == 0)
1116 if (strcmp(buf, "no") == 0)
1128 * check whether the supplied host key is valid, return only if ok.
1132 check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1136 char hostline[1000], *hostp;
1137 HostStatus host_status;
1138 HostStatus ip_status;
1139 int local = 0, host_ip_differ = 0;
1141 char ntop[NI_MAXHOST];
1144 * Force accepting of the host key for loopback/localhost. The
1145 * problem is that if the home directory is NFS-mounted to multiple
1146 * machines, localhost will refer to a different machine in each of
1147 * them, and the user will get bogus HOST_CHANGED warnings. This
1148 * essentially disables host authentication for localhost; however,
1149 * this is probably not a real problem.
1151 switch (hostaddr->sa_family) {
1153 local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1154 salen = sizeof(struct sockaddr_in);
1157 local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1158 salen = sizeof(struct sockaddr_in6);
1162 salen = sizeof(struct sockaddr_storage);
1166 debug("Forcing accepting of host key for loopback/localhost.");
1171 * Turn off check_host_ip for proxy connects, since
1172 * we don't have the remote ip-address
1174 if (options.proxy_command != NULL && options.check_host_ip)
1175 options.check_host_ip = 0;
1177 if (options.check_host_ip) {
1178 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
1179 NULL, 0, NI_NUMERICHOST) != 0)
1180 fatal("check_host_key: getnameinfo failed");
1185 * Store the host key from the known host file in here so that we can
1186 * compare it with the key for the IP address.
1188 file_key = key_new(host_key->type);
1191 * Check if the host key is present in the user\'s list of known
1192 * hosts or in the systemwide list.
1194 host_status = check_host_in_hostfile(options.user_hostfile, host, host_key, file_key);
1195 if (host_status == HOST_NEW)
1196 host_status = check_host_in_hostfile(options.system_hostfile, host, host_key, file_key);
1198 * Also perform check for the ip address, skip the check if we are
1199 * localhost or the hostname was an ip address to begin with
1201 if (options.check_host_ip && !local && strcmp(host, ip)) {
1202 Key *ip_key = key_new(host_key->type);
1203 ip_status = check_host_in_hostfile(options.user_hostfile, ip, host_key, ip_key);
1205 if (ip_status == HOST_NEW)
1206 ip_status = check_host_in_hostfile(options.system_hostfile, ip, host_key, ip_key);
1207 if (host_status == HOST_CHANGED &&
1208 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1213 ip_status = host_status;
1217 switch (host_status) {
1219 /* The host is known and the key matches. */
1220 debug("Host '%.200s' is known and matches the host key.", host);
1221 if (options.check_host_ip) {
1222 if (ip_status == HOST_NEW) {
1223 if (!add_host_to_hostfile(options.user_hostfile, ip, host_key))
1224 log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).",
1225 ip, options.user_hostfile);
1227 log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.",
1229 } else if (ip_status != HOST_OK)
1230 log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'",
1235 /* The host is new. */
1236 if (options.strict_host_key_checking == 1) {
1237 /* User has requested strict host key checking. We will not add the host key
1238 automatically. The only alternative left is to abort. */
1239 fatal("No host key is known for %.200s and you have requested strict checking.", host);
1240 } else if (options.strict_host_key_checking == 2) {
1243 char *fp = key_fingerprint(host_key);
1244 snprintf(prompt, sizeof(prompt),
1245 "The authenticity of host '%.200s' can't be established.\n"
1246 "Key fingerprint is %s.\n"
1247 "Are you sure you want to continue connecting (yes/no)? ",
1249 if (!read_yes_or_no(prompt, -1))
1250 fatal("Aborted by user!\n");
1252 if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) {
1253 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1258 /* If not in strict mode, add the key automatically to the local known_hosts file. */
1259 if (!add_host_to_hostfile(options.user_hostfile, hostp, host_key))
1260 log("Failed to add the host to the list of known hosts (%.500s).",
1261 options.user_hostfile);
1263 log("Warning: Permanently added '%.200s' to the list of known hosts.",
1267 if (options.check_host_ip && host_ip_differ) {
1269 if (ip_status == HOST_NEW)
1271 else if (ip_status == HOST_OK)
1272 msg = "is unchanged";
1274 msg = "has a different value";
1275 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1276 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1277 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1278 error("The host key for %s has changed,", host);
1279 error("and the key for the according IP address %s", ip);
1280 error("%s. This could either mean that", msg);
1281 error("DNS SPOOFING is happening or the IP address for the host");
1282 error("and its host key have changed at the same time");
1284 /* The host key has changed. */
1285 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1286 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1287 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1288 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1289 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1290 error("It is also possible that the host key has just been changed.");
1291 error("Please contact your system administrator.");
1292 error("Add correct host key in %.100s to get rid of this message.",
1293 options.user_hostfile);
1296 * If strict host key checking is in use, the user will have
1297 * to edit the key manually and we can only abort.
1299 if (options.strict_host_key_checking)
1300 fatal("Host key for %.200s has changed and you have requested strict checking.", host);
1303 * If strict host key checking has not been requested, allow
1304 * the connection but without password authentication or
1307 if (options.password_authentication) {
1308 error("Password authentication is disabled to avoid trojan horses.");
1309 options.password_authentication = 0;
1311 if (options.forward_agent) {
1312 error("Agent forwarding is disabled to avoid trojan horses.");
1313 options.forward_agent = 0;
1316 * XXX Should permit the user to change to use the new id.
1317 * This could be done by converting the host key to an
1318 * identifying sentence, tell that the host identifies itself
1319 * by that sentence, and ask the user if he/she whishes to
1320 * accept the authentication.
1324 if (options.check_host_ip)
1328 check_rsa_host_key(char *host, struct sockaddr *hostaddr, RSA *host_key)
1333 check_host_key(host, hostaddr, &k);
1340 ssh_kex2(char *host, struct sockaddr *hostaddr)
1343 char *cprop[PROPOSAL_MAX];
1344 char *sprop[PROPOSAL_MAX];
1345 Buffer *client_kexinit;
1346 Buffer *server_kexinit;
1347 int payload_len, dlen;
1348 unsigned int klen, kout;
1350 char *signature = NULL;
1352 char *server_host_key_blob = NULL;
1353 Key *server_host_key;
1354 unsigned int sbloblen;
1356 BIGNUM *dh_server_pub = 0;
1357 BIGNUM *shared_secret = 0;
1359 unsigned char *kbuf;
1360 unsigned char *hash;
1364 debug("Sending KEX init.");
1365 if (options.ciphers != NULL) {
1366 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1367 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1369 options.cipher == SSH_CIPHER_ARCFOUR ||
1370 options.cipher == SSH_CIPHER_3DES_CBC ||
1371 options.cipher == SSH_CIPHER_CAST128_CBC ||
1372 options.cipher == SSH_CIPHER_BLOWFISH_CBC) {
1373 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1374 myproposal[PROPOSAL_ENC_ALGS_STOC] = cipher_name(options.cipher);
1376 if (options.compression) {
1377 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
1378 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
1380 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
1381 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1383 for (i = 0; i < PROPOSAL_MAX; i++)
1384 cprop[i] = xstrdup(myproposal[i]);
1386 client_kexinit = kex_init(cprop);
1387 packet_start(SSH2_MSG_KEXINIT);
1388 packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));
1390 packet_write_wait();
1394 packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
1396 /* save payload for session_id */
1397 server_kexinit = xmalloc(sizeof(*server_kexinit));
1398 buffer_init(server_kexinit);
1399 ptr = packet_get_raw(&payload_len);
1400 buffer_append(server_kexinit, ptr, payload_len);
1403 for (i = 0; i < 16; i++)
1404 (void) packet_get_char();
1405 /* kex init proposal strings */
1406 for (i = 0; i < PROPOSAL_MAX; i++) {
1407 sprop[i] = packet_get_string(NULL);
1408 debug("got kexinit string: %s", sprop[i]);
1410 i = (int) packet_get_char();
1411 debug("first kex follow == %d", i);
1412 i = packet_get_int();
1413 debug("reserved == %d", i);
1416 debug("done read kexinit");
1417 kex = kex_choose_conf(cprop, sprop, 0);
1421 debug("Sending SSH2_MSG_KEXDH_INIT.");
1423 /* generate and send 'e', client DH public key */
1424 dh = dh_new_group1();
1425 packet_start(SSH2_MSG_KEXDH_INIT);
1426 packet_put_bignum2(dh->pub_key);
1428 packet_write_wait();
1431 fprintf(stderr, "\np= ");
1432 bignum_print(dh->p);
1433 fprintf(stderr, "\ng= ");
1434 bignum_print(dh->g);
1435 fprintf(stderr, "\npub= ");
1436 bignum_print(dh->pub_key);
1437 fprintf(stderr, "\n");
1438 DHparams_print_fp(stderr, dh);
1441 debug("Wait SSH2_MSG_KEXDH_REPLY.");
1443 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);
1445 debug("Got SSH2_MSG_KEXDH_REPLY.");
1448 server_host_key_blob = packet_get_string(&sbloblen);
1449 server_host_key = dsa_serverkey_from_blob(server_host_key_blob, sbloblen);
1450 if (server_host_key == NULL)
1451 fatal("cannot decode server_host_key_blob");
1453 check_host_key(host, hostaddr, server_host_key);
1455 /* DH paramter f, server public DH key */
1456 dh_server_pub = BN_new();
1457 if (dh_server_pub == NULL)
1458 fatal("dh_server_pub == NULL");
1459 packet_get_bignum2(dh_server_pub, &dlen);
1462 fprintf(stderr, "\ndh_server_pub= ");
1463 bignum_print(dh_server_pub);
1464 fprintf(stderr, "\n");
1465 debug("bits %d", BN_num_bits(dh_server_pub));
1469 signature = packet_get_string(&slen);
1472 if (!dh_pub_is_valid(dh, dh_server_pub))
1473 packet_disconnect("bad server public DH value");
1476 kbuf = xmalloc(klen);
1477 kout = DH_compute_key(kbuf, dh_server_pub, dh);
1479 debug("shared secret: len %d/%d", klen, kout);
1480 fprintf(stderr, "shared secret == ");
1481 for (i = 0; i< kout; i++)
1482 fprintf(stderr, "%02x", (kbuf[i])&0xff);
1483 fprintf(stderr, "\n");
1485 shared_secret = BN_new();
1487 BN_bin2bn(kbuf, kout, shared_secret);
1488 memset(kbuf, 0, klen);
1491 /* calc and verify H */
1493 client_version_string,
1494 server_version_string,
1495 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1496 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1497 server_host_key_blob, sbloblen,
1502 buffer_free(client_kexinit);
1503 buffer_free(server_kexinit);
1504 xfree(client_kexinit);
1505 xfree(server_kexinit);
1507 fprintf(stderr, "hash == ");
1508 for (i = 0; i< 20; i++)
1509 fprintf(stderr, "%02x", (hash[i])&0xff);
1510 fprintf(stderr, "\n");
1512 dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20);
1513 key_free(server_host_key);
1515 kex_derive_keys(kex, hash, shared_secret);
1516 packet_set_kex(kex);
1518 /* have keys, free DH */
1521 debug("Wait SSH2_MSG_NEWKEYS.");
1522 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1524 debug("GOT SSH2_MSG_NEWKEYS.");
1526 debug("send SSH2_MSG_NEWKEYS.");
1527 packet_start(SSH2_MSG_NEWKEYS);
1529 packet_write_wait();
1530 debug("done: send SSH2_MSG_NEWKEYS.");
1533 /* send 1st encrypted/maced/compressed message */
1534 packet_start(SSH2_MSG_IGNORE);
1535 packet_put_cstring("markus");
1537 packet_write_wait();
1539 debug("done: KEX2.");
1545 ssh_userauth2(int host_key_valid, RSA *own_host_key,
1546 uid_t original_real_uid, char *host)
1554 char *server_user, *local_user;
1557 char *service = "ssh-connection"; /* service name */
1559 debug("send SSH2_MSG_SERVICE_REQUEST");
1560 packet_start(SSH2_MSG_SERVICE_REQUEST);
1561 packet_put_cstring("ssh-userauth");
1563 packet_write_wait();
1565 type = packet_read(&plen);
1566 if (type != SSH2_MSG_SERVICE_ACCEPT) {
1567 fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
1569 if (packet_remaining() > 0) {
1570 char *reply = packet_get_string(&plen);
1571 debug("service_accept: %s", reply);
1574 /* payload empty for ssh-2.0.13 ?? */
1575 log("buggy server: service_accept w/o service");
1578 debug("got SSH2_MSG_SERVICE_ACCEPT");
1581 /* Get local user name. Use it as server user if no user name was given. */
1582 pw = getpwuid(original_real_uid);
1584 fatal("User id %d not found from user database.", original_real_uid);
1585 local_user = xstrdup(pw->pw_name);
1586 server_user = options.user ? options.user : local_user;
1588 /* INITIAL request for auth */
1589 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1590 packet_put_cstring(server_user);
1591 packet_put_cstring(service);
1592 packet_put_cstring("none");
1594 packet_write_wait();
1597 type = packet_read(&plen);
1598 if (type == SSH2_MSG_USERAUTH_SUCCESS)
1600 if (type != SSH2_MSG_USERAUTH_FAILURE)
1601 fatal("access denied: %d", type);
1602 /* SSH2_MSG_USERAUTH_FAILURE means: try again */
1603 auths = packet_get_string(&dlen);
1604 debug("authentications that can continue: %s", auths);
1605 partial = packet_get_char();
1608 debug("partial success");
1609 if (strstr(auths, "password") == NULL)
1610 fatal("passwd auth not supported: %s", auths);
1613 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1615 password = read_passphrase(prompt, 0);
1616 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1617 packet_put_cstring(server_user);
1618 packet_put_cstring(service);
1619 packet_put_cstring("password");
1621 packet_put_cstring(password);
1622 memset(password, 0, strlen(password));
1625 packet_write_wait();
1628 debug("ssh-userauth2 successfull");
1635 ssh_kex(char *host, struct sockaddr *hostaddr)
1642 int ssh_cipher_default = SSH_CIPHER_3DES;
1643 unsigned char session_key[SSH_SESSION_KEY_LENGTH];
1644 unsigned char cookie[8];
1645 unsigned int supported_ciphers;
1646 unsigned int server_flags, client_flags;
1647 int payload_len, clen, sum_len = 0;
1650 debug("Waiting for server public key.");
1652 /* Wait for a public key packet from the server. */
1653 packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
1655 /* Get cookie from the packet. */
1656 for (i = 0; i < 8; i++)
1657 cookie[i] = packet_get_char();
1659 /* Get the public key. */
1660 public_key = RSA_new();
1661 bits = packet_get_int();/* bits */
1662 public_key->e = BN_new();
1663 packet_get_bignum(public_key->e, &clen);
1665 public_key->n = BN_new();
1666 packet_get_bignum(public_key->n, &clen);
1669 rbits = BN_num_bits(public_key->n);
1670 if (bits != rbits) {
1671 log("Warning: Server lies about size of server public key: "
1672 "actual size is %d bits vs. announced %d.", rbits, bits);
1673 log("Warning: This may be due to an old implementation of ssh.");
1675 /* Get the host key. */
1676 host_key = RSA_new();
1677 bits = packet_get_int();/* bits */
1678 host_key->e = BN_new();
1679 packet_get_bignum(host_key->e, &clen);
1681 host_key->n = BN_new();
1682 packet_get_bignum(host_key->n, &clen);
1685 rbits = BN_num_bits(host_key->n);
1686 if (bits != rbits) {
1687 log("Warning: Server lies about size of server host key: "
1688 "actual size is %d bits vs. announced %d.", rbits, bits);
1689 log("Warning: This may be due to an old implementation of ssh.");
1692 /* Get protocol flags. */
1693 server_flags = packet_get_int();
1694 packet_set_protocol_flags(server_flags);
1696 supported_ciphers = packet_get_int();
1697 supported_authentications = packet_get_int();
1699 debug("Received server public key (%d bits) and host key (%d bits).",
1700 BN_num_bits(public_key->n), BN_num_bits(host_key->n));
1702 packet_integrity_check(payload_len,
1703 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
1704 SSH_SMSG_PUBLIC_KEY);
1706 check_rsa_host_key(host, hostaddr, host_key);
1708 client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN;
1710 compute_session_id(session_id, cookie, host_key->n, public_key->n);
1712 /* Generate a session key. */
1716 * Generate an encryption key for the session. The key is a 256 bit
1717 * random number, interpreted as a 32-byte key, with the least
1718 * significant 8 bits being the first byte of the key.
1720 for (i = 0; i < 32; i++) {
1722 rand = arc4random();
1723 session_key[i] = rand & 0xff;
1728 * According to the protocol spec, the first byte of the session key
1729 * is the highest byte of the integer. The session key is xored with
1730 * the first 16 bytes of the session id.
1733 BN_set_word(key, 0);
1734 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
1735 BN_lshift(key, key, 8);
1737 BN_add_word(key, session_key[i] ^ session_id[i]);
1739 BN_add_word(key, session_key[i]);
1743 * Encrypt the integer using the public key and host key of the
1744 * server (key with smaller modulus first).
1746 if (BN_cmp(public_key->n, host_key->n) < 0) {
1747 /* Public key has smaller modulus. */
1748 if (BN_num_bits(host_key->n) <
1749 BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) {
1750 fatal("respond_to_rsa_challenge: host_key %d < public_key %d + "
1751 "SSH_KEY_BITS_RESERVED %d",
1752 BN_num_bits(host_key->n),
1753 BN_num_bits(public_key->n),
1754 SSH_KEY_BITS_RESERVED);
1756 rsa_public_encrypt(key, key, public_key);
1757 rsa_public_encrypt(key, key, host_key);
1759 /* Host key has smaller modulus (or they are equal). */
1760 if (BN_num_bits(public_key->n) <
1761 BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) {
1762 fatal("respond_to_rsa_challenge: public_key %d < host_key %d + "
1763 "SSH_KEY_BITS_RESERVED %d",
1764 BN_num_bits(public_key->n),
1765 BN_num_bits(host_key->n),
1766 SSH_KEY_BITS_RESERVED);
1768 rsa_public_encrypt(key, key, host_key);
1769 rsa_public_encrypt(key, key, public_key);
1772 /* Destroy the public keys since we no longer need them. */
1773 RSA_free(public_key);
1776 if (options.cipher == SSH_CIPHER_NOT_SET) {
1777 if (cipher_mask1() & supported_ciphers & (1 << ssh_cipher_default))
1778 options.cipher = ssh_cipher_default;
1780 debug("Cipher %s not supported, using %.100s instead.",
1781 cipher_name(ssh_cipher_default),
1782 cipher_name(SSH_FALLBACK_CIPHER));
1783 options.cipher = SSH_FALLBACK_CIPHER;
1786 /* Check that the selected cipher is supported. */
1787 if (!(supported_ciphers & (1 << options.cipher)))
1788 fatal("Selected cipher type %.100s not supported by server.",
1789 cipher_name(options.cipher));
1791 debug("Encryption type: %.100s", cipher_name(options.cipher));
1793 /* Send the encrypted session key to the server. */
1794 packet_start(SSH_CMSG_SESSION_KEY);
1795 packet_put_char(options.cipher);
1797 /* Send the cookie back to the server. */
1798 for (i = 0; i < 8; i++)
1799 packet_put_char(cookie[i]);
1801 /* Send and destroy the encrypted encryption key integer. */
1802 packet_put_bignum(key);
1805 /* Send protocol flags. */
1806 packet_put_int(client_flags);
1808 /* Send the packet now. */
1810 packet_write_wait();
1812 debug("Sent encrypted session key.");
1814 /* Set the encryption key. */
1815 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher);
1817 /* We will no longer need the session key here. Destroy any extra copies. */
1818 memset(session_key, 0, sizeof(session_key));
1821 * Expect a success message from the server. Note that this message
1822 * will be received in encrypted form.
1824 packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1826 debug("Received encrypted confirmation.");
1833 ssh_userauth(int host_key_valid, RSA *own_host_key,
1834 uid_t original_real_uid, char *host)
1839 const char *server_user, *local_user;
1841 /* Get local user name. Use it as server user if no user name was given. */
1842 pw = getpwuid(original_real_uid);
1844 fatal("User id %d not found from user database.", original_real_uid);
1845 local_user = xstrdup(pw->pw_name);
1846 server_user = options.user ? options.user : local_user;
1848 /* Send the name of the user to log in as on the server. */
1849 packet_start(SSH_CMSG_USER);
1850 packet_put_string(server_user, strlen(server_user));
1852 packet_write_wait();
1855 * The server should respond with success if no authentication is
1856 * needed (the user has no password). Otherwise the server responds
1859 type = packet_read(&payload_len);
1861 /* check whether the connection was accepted without authentication. */
1862 if (type == SSH_SMSG_SUCCESS)
1864 if (type != SSH_SMSG_FAILURE)
1865 packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
1869 /* Try Kerberos tgt passing if the server supports it. */
1870 if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
1871 options.kerberos_tgt_passing) {
1872 if (options.cipher == SSH_CIPHER_NONE)
1873 log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
1874 (void) send_kerberos_tgt();
1876 /* Try AFS token passing if the server supports it. */
1877 if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
1878 options.afs_token_passing && k_hasafs()) {
1879 if (options.cipher == SSH_CIPHER_NONE)
1880 log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
1886 if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
1887 options.kerberos_authentication) {
1888 debug("Trying Kerberos authentication.");
1889 if (try_kerberos_authentication()) {
1890 /* The server should respond with success or failure. */
1891 type = packet_read(&payload_len);
1892 if (type == SSH_SMSG_SUCCESS)
1894 if (type != SSH_SMSG_FAILURE)
1895 packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
1901 * Use rhosts authentication if running in privileged socket and we
1902 * do not wish to remain anonymous.
1904 if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
1905 options.rhosts_authentication) {
1906 debug("Trying rhosts authentication.");
1907 packet_start(SSH_CMSG_AUTH_RHOSTS);
1908 packet_put_string(local_user, strlen(local_user));
1910 packet_write_wait();
1912 /* The server should respond with success or failure. */
1913 type = packet_read(&payload_len);
1914 if (type == SSH_SMSG_SUCCESS)
1916 if (type != SSH_SMSG_FAILURE)
1917 packet_disconnect("Protocol error: got %d in response to rhosts auth",
1921 * Try .rhosts or /etc/hosts.equiv authentication with RSA host
1924 if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
1925 options.rhosts_rsa_authentication && host_key_valid) {
1926 if (try_rhosts_rsa_authentication(local_user, own_host_key))
1929 /* Try RSA authentication if the server supports it. */
1930 if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
1931 options.rsa_authentication) {
1933 * Try RSA authentication using the authentication agent. The
1934 * agent is tried first because no passphrase is needed for
1935 * it, whereas identity files may require passphrases.
1937 if (try_agent_authentication())
1940 /* Try RSA authentication for each identity. */
1941 for (i = 0; i < options.num_identity_files; i++)
1942 if (try_rsa_authentication(options.identity_files[i]))
1945 /* Try skey authentication if the server supports it. */
1946 if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
1947 options.skey_authentication && !options.batch_mode) {
1948 if (try_skey_authentication())
1951 /* Try password authentication if the server supports it. */
1952 if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
1953 options.password_authentication && !options.batch_mode) {
1956 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1958 if (try_password_authentication(prompt))
1961 /* All authentication methods have failed. Exit with an error message. */
1962 fatal("Permission denied.");
1966 * Starts a dialog with the server, and authenticates the current user on the
1967 * server. This does not need any extra privileges. The basic connection
1968 * to the server must already have been established before this is called.
1969 * If login fails, this function prints an error and never returns.
1970 * This function does not require super-user privileges.
1973 ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
1974 struct sockaddr *hostaddr, uid_t original_real_uid)
1978 /* Convert the user-supplied hostname into all lowercase. */
1979 host = xstrdup(orighost);
1980 for (cp = host; *cp; cp++)
1984 /* Exchange protocol version identification strings with the server. */
1985 ssh_exchange_identification();
1987 /* Put the connection into non-blocking mode. */
1988 packet_set_nonblocking();
1991 /* authenticate user */
1993 ssh_kex2(host, hostaddr);
1994 ssh_userauth2(host_key_valid, own_host_key, original_real_uid, host);
1996 supported_authentications = 0;
1997 ssh_kex(host, hostaddr);
1998 if (supported_authentications == 0)
1999 fatal("supported_authentications == 0.");
2000 ssh_userauth(host_key_valid, own_host_key, original_real_uid, host);