Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.59
1.1 deraadt 1: /*
1.39 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
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.
1.59 ! markus 8: *
! 9: * SSH2 support added by Markus Friedl.
1.39 deraadt 10: */
1.1 deraadt 11:
12: #include "includes.h"
1.59 ! markus 13: RCSID("$OpenBSD: sshconnect.c,v 1.58 2000/03/23 22:15:33 markus Exp $");
1.1 deraadt 14:
1.3 provos 15: #include <ssl/bn.h>
1.1 deraadt 16: #include "xmalloc.h"
17: #include "rsa.h"
18: #include "ssh.h"
1.59 ! markus 19: #include "buffer.h"
1.1 deraadt 20: #include "packet.h"
21: #include "authfd.h"
22: #include "cipher.h"
23: #include "mpaux.h"
24: #include "uidswap.h"
1.21 markus 25: #include "compat.h"
1.27 markus 26: #include "readconf.h"
1.1 deraadt 27:
1.59 ! markus 28: #include "bufaux.h"
1.58 markus 29: #include <ssl/rsa.h>
30: #include <ssl/dsa.h>
1.59 ! markus 31:
! 32: #include "ssh2.h"
1.24 deraadt 33: #include <ssl/md5.h>
1.59 ! markus 34: #include <ssl/dh.h>
! 35: #include <ssl/hmac.h>
! 36: #include "kex.h"
! 37: #include "myproposal.h"
1.58 markus 38: #include "key.h"
1.59 ! markus 39: #include "dsa.h"
1.58 markus 40: #include "hostfile.h"
1.10 deraadt 41:
1.1 deraadt 42: /* Session id for the current session. */
43: unsigned char session_id[16];
44:
1.51 markus 45: /* authentications supported by server */
46: unsigned int supported_authentications;
47:
1.59 ! markus 48: static char *client_version_string = NULL;
! 49: static char *server_version_string = NULL;
! 50:
1.43 markus 51: extern Options options;
1.50 markus 52: extern char *__progname;
1.43 markus 53:
1.39 deraadt 54: /*
55: * Connect to the given ssh server using a proxy command.
56: */
1.3 provos 57: int
1.41 markus 58: ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid,
1.3 provos 59: const char *proxy_command)
1.1 deraadt 60: {
1.38 markus 61: Buffer command;
62: const char *cp;
63: char *command_string;
64: int pin[2], pout[2];
65: int pid;
1.49 markus 66: char strport[NI_MAXSERV];
1.38 markus 67:
68: /* Convert the port number into a string. */
1.49 markus 69: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 70:
71: /* Build the final command string in the buffer by making the
72: appropriate substitutions to the given proxy command. */
73: buffer_init(&command);
74: for (cp = proxy_command; *cp; cp++) {
75: if (cp[0] == '%' && cp[1] == '%') {
76: buffer_append(&command, "%", 1);
77: cp++;
78: continue;
79: }
80: if (cp[0] == '%' && cp[1] == 'h') {
81: buffer_append(&command, host, strlen(host));
82: cp++;
83: continue;
84: }
85: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 86: buffer_append(&command, strport, strlen(strport));
1.38 markus 87: cp++;
88: continue;
89: }
90: buffer_append(&command, cp, 1);
91: }
92: buffer_append(&command, "\0", 1);
93:
94: /* Get the final command string. */
95: command_string = buffer_ptr(&command);
96:
97: /* Create pipes for communicating with the proxy. */
98: if (pipe(pin) < 0 || pipe(pout) < 0)
99: fatal("Could not create pipes to communicate with the proxy: %.100s",
100: strerror(errno));
101:
102: debug("Executing proxy command: %.500s", command_string);
103:
104: /* Fork and execute the proxy command. */
105: if ((pid = fork()) == 0) {
106: char *argv[10];
107:
108: /* Child. Permanently give up superuser privileges. */
109: permanently_set_uid(original_real_uid);
110:
111: /* Redirect stdin and stdout. */
112: close(pin[1]);
113: if (pin[0] != 0) {
114: if (dup2(pin[0], 0) < 0)
115: perror("dup2 stdin");
116: close(pin[0]);
117: }
118: close(pout[0]);
119: if (dup2(pout[1], 1) < 0)
120: perror("dup2 stdout");
121: /* Cannot be 1 because pin allocated two descriptors. */
122: close(pout[1]);
123:
124: /* Stderr is left as it is so that error messages get
125: printed on the user's terminal. */
126: argv[0] = "/bin/sh";
127: argv[1] = "-c";
128: argv[2] = command_string;
129: argv[3] = NULL;
130:
131: /* Execute the proxy command. Note that we gave up any
132: extra privileges above. */
133: execv("/bin/sh", argv);
134: perror("/bin/sh");
135: exit(1);
136: }
137: /* Parent. */
138: if (pid < 0)
139: fatal("fork failed: %.100s", strerror(errno));
140:
141: /* Close child side of the descriptors. */
142: close(pin[0]);
143: close(pout[1]);
144:
145: /* Free the command name. */
146: buffer_free(&command);
147:
148: /* Set the connection file descriptors. */
149: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 150:
1.38 markus 151: return 1;
1.1 deraadt 152: }
153:
1.39 deraadt 154: /*
155: * Creates a (possibly privileged) socket for use as the ssh connection.
156: */
1.38 markus 157: int
1.49 markus 158: ssh_create_socket(uid_t original_real_uid, int privileged, int family)
1.1 deraadt 159: {
1.38 markus 160: int sock;
1.1 deraadt 161:
1.40 markus 162: /*
163: * If we are running as root and want to connect to a privileged
164: * port, bind our own socket to a privileged port.
165: */
1.38 markus 166: if (privileged) {
167: int p = IPPORT_RESERVED - 1;
1.49 markus 168: sock = rresvport_af(&p, family);
1.38 markus 169: if (sock < 0)
1.55 markus 170: error("rresvport: af=%d %.100s", family, strerror(errno));
171: else
172: debug("Allocated local port %d.", p);
1.38 markus 173: } else {
1.46 markus 174: /*
175: * Just create an ordinary socket on arbitrary port. We use
176: * the user's uid to create the socket.
177: */
1.38 markus 178: temporarily_use_uid(original_real_uid);
1.49 markus 179: sock = socket(family, SOCK_STREAM, 0);
1.38 markus 180: if (sock < 0)
1.49 markus 181: error("socket: %.100s", strerror(errno));
1.38 markus 182: restore_uid();
183: }
184: return sock;
1.1 deraadt 185: }
186:
1.39 deraadt 187: /*
1.49 markus 188: * Opens a TCP/IP connection to the remote server on the given host.
189: * The address of the remote host will be returned in hostaddr.
190: * If port is 0, the default port will be used. If anonymous is zero,
1.39 deraadt 191: * a privileged port will be allocated to make the connection.
192: * This requires super-user privileges if anonymous is false.
193: * Connection_attempts specifies the maximum number of tries (one per
194: * second). If proxy_command is non-NULL, it specifies the command (with %h
195: * and %p substituted for host and port, respectively) to use to contact
196: * the daemon.
197: */
1.38 markus 198: int
1.49 markus 199: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.41 markus 200: u_short port, int connection_attempts,
1.38 markus 201: int anonymous, uid_t original_real_uid,
202: const char *proxy_command)
1.1 deraadt 203: {
1.49 markus 204: int sock = -1, attempt;
1.38 markus 205: struct servent *sp;
1.49 markus 206: struct addrinfo hints, *ai, *aitop;
207: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
208: int gaierr;
1.38 markus 209: struct linger linger;
210:
211: debug("ssh_connect: getuid %d geteuid %d anon %d",
212: (int) getuid(), (int) geteuid(), anonymous);
213:
214: /* Get default port if port has not been set. */
215: if (port == 0) {
216: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
217: if (sp)
218: port = ntohs(sp->s_port);
219: else
220: port = SSH_DEFAULT_PORT;
221: }
222: /* If a proxy command is given, connect using it. */
223: if (proxy_command != NULL)
224: return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
225:
226: /* No proxy command. */
227:
1.49 markus 228: memset(&hints, 0, sizeof(hints));
229: hints.ai_family = IPv4or6;
230: hints.ai_socktype = SOCK_STREAM;
231: snprintf(strport, sizeof strport, "%d", port);
232: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 233: fatal("%s: %.100s: %s", __progname, host,
234: gai_strerror(gaierr));
1.38 markus 235:
1.46 markus 236: /*
237: * Try to connect several times. On some machines, the first time
238: * will sometimes fail. In general socket code appears to behave
239: * quite magically on many machines.
240: */
1.38 markus 241: for (attempt = 0; attempt < connection_attempts; attempt++) {
242: if (attempt > 0)
243: debug("Trying again...");
244:
1.49 markus 245: /* Loop through addresses for this host, and try each one in
246: sequence until the connection succeeds. */
247: for (ai = aitop; ai; ai = ai->ai_next) {
248: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
249: continue;
250: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
251: ntop, sizeof(ntop), strport, sizeof(strport),
252: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
253: error("ssh_connect: getnameinfo failed");
254: continue;
255: }
256: debug("Connecting to %.200s [%.100s] port %s.",
257: host, ntop, strport);
258:
259: /* Create a socket for connecting. */
260: sock = ssh_create_socket(original_real_uid,
261: !anonymous && geteuid() == 0 && port < IPPORT_RESERVED,
262: ai->ai_family);
263: if (sock < 0)
264: continue;
265:
266: /* Connect to the host. We use the user's uid in the
267: * hope that it will help with tcp_wrappers showing
268: * the remote uid as root.
1.40 markus 269: */
1.38 markus 270: temporarily_use_uid(original_real_uid);
1.49 markus 271: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
272: /* Successful connection. */
273: memcpy(hostaddr, ai->ai_addr, sizeof(*hostaddr));
1.38 markus 274: restore_uid();
275: break;
1.49 markus 276: } else {
1.38 markus 277: debug("connect: %.100s", strerror(errno));
278: restore_uid();
1.40 markus 279: /*
280: * Close the failed socket; there appear to
281: * be some problems when reusing a socket for
282: * which connect() has already returned an
283: * error.
284: */
1.38 markus 285: shutdown(sock, SHUT_RDWR);
286: close(sock);
287: }
288: }
1.49 markus 289: if (ai)
290: break; /* Successful connection. */
1.1 deraadt 291:
1.38 markus 292: /* Sleep a moment before retrying. */
293: sleep(1);
294: }
1.49 markus 295:
296: freeaddrinfo(aitop);
297:
1.38 markus 298: /* Return failure if we didn't get a successful connection. */
299: if (attempt >= connection_attempts)
300: return 0;
301:
302: debug("Connection established.");
303:
1.40 markus 304: /*
305: * Set socket options. We would like the socket to disappear as soon
306: * as it has been closed for whatever reason.
307: */
308: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 309: linger.l_onoff = 1;
310: linger.l_linger = 5;
311: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
312:
313: /* Set the connection. */
314: packet_set_connection(sock, sock);
1.1 deraadt 315:
1.38 markus 316: return 1;
1.1 deraadt 317: }
318:
1.39 deraadt 319: /*
320: * Checks if the user has an authentication agent, and if so, tries to
321: * authenticate using the agent.
322: */
1.3 provos 323: int
324: try_agent_authentication()
1.1 deraadt 325: {
1.38 markus 326: int status, type;
327: char *comment;
328: AuthenticationConnection *auth;
329: unsigned char response[16];
330: unsigned int i;
331: BIGNUM *e, *n, *challenge;
332:
333: /* Get connection to the agent. */
334: auth = ssh_get_authentication_connection();
335: if (!auth)
336: return 0;
337:
338: e = BN_new();
339: n = BN_new();
340: challenge = BN_new();
341:
342: /* Loop through identities served by the agent. */
343: for (status = ssh_get_first_identity(auth, e, n, &comment);
344: status;
345: status = ssh_get_next_identity(auth, e, n, &comment)) {
346: int plen, clen;
347:
348: /* Try this identity. */
349: debug("Trying RSA authentication via agent with '%.100s'", comment);
350: xfree(comment);
351:
352: /* Tell the server that we are willing to authenticate using this key. */
353: packet_start(SSH_CMSG_AUTH_RSA);
354: packet_put_bignum(n);
355: packet_send();
356: packet_write_wait();
357:
358: /* Wait for server's response. */
359: type = packet_read(&plen);
360:
361: /* The server sends failure if it doesn\'t like our key or
362: does not support RSA authentication. */
363: if (type == SSH_SMSG_FAILURE) {
364: debug("Server refused our key.");
365: continue;
366: }
367: /* Otherwise it should have sent a challenge. */
368: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
369: packet_disconnect("Protocol error during RSA authentication: %d",
370: type);
371:
372: packet_get_bignum(challenge, &clen);
373:
374: packet_integrity_check(plen, clen, type);
375:
376: debug("Received RSA challenge from server.");
377:
378: /* Ask the agent to decrypt the challenge. */
379: if (!ssh_decrypt_challenge(auth, e, n, challenge,
380: session_id, 1, response)) {
381: /* The agent failed to authenticate this identifier although it
382: advertised it supports this. Just return a wrong value. */
383: log("Authentication agent failed to decrypt challenge.");
384: memset(response, 0, sizeof(response));
385: }
386: debug("Sending response to RSA challenge.");
1.1 deraadt 387:
1.38 markus 388: /* Send the decrypted challenge back to the server. */
389: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
390: for (i = 0; i < 16; i++)
391: packet_put_char(response[i]);
392: packet_send();
393: packet_write_wait();
394:
395: /* Wait for response from the server. */
396: type = packet_read(&plen);
397:
398: /* The server returns success if it accepted the authentication. */
399: if (type == SSH_SMSG_SUCCESS) {
400: debug("RSA authentication accepted by server.");
401: BN_clear_free(e);
402: BN_clear_free(n);
403: BN_clear_free(challenge);
404: return 1;
405: }
406: /* Otherwise it should return failure. */
407: if (type != SSH_SMSG_FAILURE)
408: packet_disconnect("Protocol error waiting RSA auth response: %d",
409: type);
410: }
411:
412: BN_clear_free(e);
413: BN_clear_free(n);
414: BN_clear_free(challenge);
415:
416: debug("RSA authentication using agent refused.");
417: return 0;
1.1 deraadt 418: }
419:
1.39 deraadt 420: /*
421: * Computes the proper response to a RSA challenge, and sends the response to
422: * the server.
423: */
1.3 provos 424: void
1.38 markus 425: respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv)
1.1 deraadt 426: {
1.38 markus 427: unsigned char buf[32], response[16];
428: MD5_CTX md;
429: int i, len;
430:
431: /* Decrypt the challenge using the private key. */
432: rsa_private_decrypt(challenge, challenge, prv);
433:
434: /* Compute the response. */
435: /* The response is MD5 of decrypted challenge plus session id. */
436: len = BN_num_bytes(challenge);
437: if (len <= 0 || len > sizeof(buf))
438: packet_disconnect("respond_to_rsa_challenge: bad challenge length %d",
439: len);
440:
441: memset(buf, 0, sizeof(buf));
442: BN_bn2bin(challenge, buf + sizeof(buf) - len);
443: MD5_Init(&md);
444: MD5_Update(&md, buf, 32);
445: MD5_Update(&md, session_id, 16);
446: MD5_Final(response, &md);
447:
448: debug("Sending response to host key RSA challenge.");
449:
450: /* Send the response back to the server. */
451: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
452: for (i = 0; i < 16; i++)
453: packet_put_char(response[i]);
454: packet_send();
455: packet_write_wait();
456:
457: memset(buf, 0, sizeof(buf));
458: memset(response, 0, sizeof(response));
459: memset(&md, 0, sizeof(md));
1.1 deraadt 460: }
461:
1.39 deraadt 462: /*
463: * Checks if the user has authentication file, and if so, tries to authenticate
464: * the user using it.
465: */
1.3 provos 466: int
1.43 markus 467: try_rsa_authentication(const char *authfile)
1.1 deraadt 468: {
1.38 markus 469: BIGNUM *challenge;
470: RSA *private_key;
471: RSA *public_key;
472: char *passphrase, *comment;
473: int type, i;
474: int plen, clen;
475:
476: /* Try to load identification for the authentication key. */
477: public_key = RSA_new();
478: if (!load_public_key(authfile, public_key, &comment)) {
479: RSA_free(public_key);
1.43 markus 480: /* Could not load it. Fail. */
481: return 0;
1.38 markus 482: }
483: debug("Trying RSA authentication with key '%.100s'", comment);
484:
485: /* Tell the server that we are willing to authenticate using this key. */
486: packet_start(SSH_CMSG_AUTH_RSA);
487: packet_put_bignum(public_key->n);
488: packet_send();
489: packet_write_wait();
490:
491: /* We no longer need the public key. */
492: RSA_free(public_key);
493:
494: /* Wait for server's response. */
495: type = packet_read(&plen);
496:
1.40 markus 497: /*
498: * The server responds with failure if it doesn\'t like our key or
499: * doesn\'t support RSA authentication.
500: */
1.38 markus 501: if (type == SSH_SMSG_FAILURE) {
502: debug("Server refused our key.");
503: xfree(comment);
1.43 markus 504: return 0;
1.38 markus 505: }
506: /* Otherwise, the server should respond with a challenge. */
507: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
508: packet_disconnect("Protocol error during RSA authentication: %d", type);
509:
510: /* Get the challenge from the packet. */
511: challenge = BN_new();
512: packet_get_bignum(challenge, &clen);
513:
514: packet_integrity_check(plen, clen, type);
515:
516: debug("Received RSA challenge from server.");
517:
518: private_key = RSA_new();
1.40 markus 519: /*
520: * Load the private key. Try first with empty passphrase; if it
521: * fails, ask for a passphrase.
522: */
1.38 markus 523: if (!load_private_key(authfile, "", private_key, NULL)) {
524: char buf[300];
525: snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ",
1.45 deraadt 526: comment);
1.38 markus 527: if (!options.batch_mode)
528: passphrase = read_passphrase(buf, 0);
529: else {
530: debug("Will not query passphrase for %.100s in batch mode.",
531: comment);
532: passphrase = xstrdup("");
533: }
534:
535: /* Load the authentication file using the pasphrase. */
536: if (!load_private_key(authfile, passphrase, private_key, NULL)) {
537: memset(passphrase, 0, strlen(passphrase));
538: xfree(passphrase);
539: error("Bad passphrase.");
540:
541: /* Send a dummy response packet to avoid protocol error. */
542: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
543: for (i = 0; i < 16; i++)
544: packet_put_char(0);
545: packet_send();
546: packet_write_wait();
547:
548: /* Expect the server to reject it... */
549: packet_read_expect(&plen, SSH_SMSG_FAILURE);
550: xfree(comment);
551: return 0;
552: }
553: /* Destroy the passphrase. */
554: memset(passphrase, 0, strlen(passphrase));
555: xfree(passphrase);
556: }
557: /* We no longer need the comment. */
558: xfree(comment);
559:
560: /* Compute and send a response to the challenge. */
561: respond_to_rsa_challenge(challenge, private_key);
562:
563: /* Destroy the private key. */
564: RSA_free(private_key);
565:
566: /* We no longer need the challenge. */
567: BN_clear_free(challenge);
568:
569: /* Wait for response from the server. */
570: type = packet_read(&plen);
571: if (type == SSH_SMSG_SUCCESS) {
572: debug("RSA authentication accepted by server.");
573: return 1;
574: }
575: if (type != SSH_SMSG_FAILURE)
576: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
577: debug("RSA authentication refused.");
578: return 0;
1.1 deraadt 579: }
580:
1.39 deraadt 581: /*
582: * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
583: * authentication and RSA host authentication.
584: */
1.3 provos 585: int
1.38 markus 586: try_rhosts_rsa_authentication(const char *local_user, RSA * host_key)
1.1 deraadt 587: {
1.38 markus 588: int type;
589: BIGNUM *challenge;
590: int plen, clen;
591:
592: debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
593:
594: /* Tell the server that we are willing to authenticate using this key. */
595: packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
596: packet_put_string(local_user, strlen(local_user));
597: packet_put_int(BN_num_bits(host_key->n));
598: packet_put_bignum(host_key->e);
599: packet_put_bignum(host_key->n);
600: packet_send();
601: packet_write_wait();
602:
603: /* Wait for server's response. */
604: type = packet_read(&plen);
605:
606: /* The server responds with failure if it doesn't admit our
607: .rhosts authentication or doesn't know our host key. */
608: if (type == SSH_SMSG_FAILURE) {
609: debug("Server refused our rhosts authentication or host key.");
610: return 0;
611: }
612: /* Otherwise, the server should respond with a challenge. */
613: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
614: packet_disconnect("Protocol error during RSA authentication: %d", type);
615:
616: /* Get the challenge from the packet. */
617: challenge = BN_new();
618: packet_get_bignum(challenge, &clen);
619:
620: packet_integrity_check(plen, clen, type);
621:
622: debug("Received RSA challenge for host key from server.");
623:
624: /* Compute a response to the challenge. */
625: respond_to_rsa_challenge(challenge, host_key);
626:
627: /* We no longer need the challenge. */
628: BN_clear_free(challenge);
629:
630: /* Wait for response from the server. */
631: type = packet_read(&plen);
632: if (type == SSH_SMSG_SUCCESS) {
633: debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
634: return 1;
635: }
636: if (type != SSH_SMSG_FAILURE)
637: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
638: debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
639: return 0;
1.1 deraadt 640: }
641:
642: #ifdef KRB4
1.38 markus 643: int
644: try_kerberos_authentication()
1.1 deraadt 645: {
1.38 markus 646: KTEXT_ST auth; /* Kerberos data */
647: char *reply;
648: char inst[INST_SZ];
649: char *realm;
650: CREDENTIALS cred;
651: int r, type, plen;
1.57 markus 652: socklen_t slen;
1.38 markus 653: Key_schedule schedule;
654: u_long checksum, cksum;
655: MSG_DAT msg_data;
656: struct sockaddr_in local, foreign;
657: struct stat st;
658:
659: /* Don't do anything if we don't have any tickets. */
660: if (stat(tkt_string(), &st) < 0)
661: return 0;
662:
663: strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
664:
665: realm = (char *) krb_realmofhost(get_canonical_hostname());
666: if (!realm) {
667: debug("Kerberos V4: no realm for %s", get_canonical_hostname());
668: return 0;
669: }
670: /* This can really be anything. */
671: checksum = (u_long) getpid();
672:
673: r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
674: if (r != KSUCCESS) {
675: debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]);
676: return 0;
677: }
678: /* Get session key to decrypt the server's reply with. */
679: r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
680: if (r != KSUCCESS) {
681: debug("get_cred failed: %s", krb_err_txt[r]);
682: return 0;
683: }
684: des_key_sched((des_cblock *) cred.session, schedule);
685:
686: /* Send authentication info to server. */
687: packet_start(SSH_CMSG_AUTH_KERBEROS);
688: packet_put_string((char *) auth.dat, auth.length);
689: packet_send();
690: packet_write_wait();
691:
692: /* Zero the buffer. */
693: (void) memset(auth.dat, 0, MAX_KTXT_LEN);
694:
1.57 markus 695: slen = sizeof(local);
1.38 markus 696: memset(&local, 0, sizeof(local));
697: if (getsockname(packet_get_connection_in(),
1.57 markus 698: (struct sockaddr *) & local, &slen) < 0)
1.38 markus 699: debug("getsockname failed: %s", strerror(errno));
700:
1.57 markus 701: slen = sizeof(foreign);
1.38 markus 702: memset(&foreign, 0, sizeof(foreign));
703: if (getpeername(packet_get_connection_in(),
1.57 markus 704: (struct sockaddr *) & foreign, &slen) < 0) {
1.38 markus 705: debug("getpeername failed: %s", strerror(errno));
706: fatal_cleanup();
707: }
708: /* Get server reply. */
709: type = packet_read(&plen);
710: switch (type) {
711: case SSH_SMSG_FAILURE:
712: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
713: debug("Kerberos V4 authentication failed.");
714: return 0;
715: break;
716:
717: case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
718: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
719: debug("Kerberos V4 authentication accepted.");
720:
721: /* Get server's response. */
722: reply = packet_get_string((unsigned int *) &auth.length);
723: memcpy(auth.dat, reply, auth.length);
724: xfree(reply);
725:
726: packet_integrity_check(plen, 4 + auth.length, type);
727:
1.40 markus 728: /*
729: * If his response isn't properly encrypted with the session
730: * key, and the decrypted checksum fails to match, he's
731: * bogus. Bail out.
732: */
1.38 markus 733: r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
734: &foreign, &local, &msg_data);
735: if (r != KSUCCESS) {
736: debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]);
737: packet_disconnect("Kerberos V4 challenge failed!");
738: }
739: /* Fetch the (incremented) checksum that we supplied in the request. */
740: (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum));
741: cksum = ntohl(cksum);
742:
743: /* If it matches, we're golden. */
744: if (cksum == checksum + 1) {
745: debug("Kerberos V4 challenge successful.");
746: return 1;
747: } else
748: packet_disconnect("Kerberos V4 challenge failed!");
749: break;
750:
751: default:
752: packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
753: }
754: return 0;
1.1 deraadt 755: }
1.38 markus 756:
1.1 deraadt 757: #endif /* KRB4 */
758:
759: #ifdef AFS
1.38 markus 760: int
761: send_kerberos_tgt()
1.1 deraadt 762: {
1.38 markus 763: CREDENTIALS *creds;
764: char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
765: int r, type, plen;
1.57 markus 766: char buffer[8192];
1.38 markus 767: struct stat st;
768:
769: /* Don't do anything if we don't have any tickets. */
770: if (stat(tkt_string(), &st) < 0)
771: return 0;
772:
773: creds = xmalloc(sizeof(*creds));
774:
775: if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) {
776: debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]);
777: return 0;
778: }
779: if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
780: debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]);
781: return 0;
782: }
783: if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
784: debug("Kerberos V4 ticket expired: %s", TKT_FILE);
785: return 0;
786: }
1.57 markus 787: creds_to_radix(creds, (unsigned char *)buffer);
1.38 markus 788: xfree(creds);
789:
790: packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
1.57 markus 791: packet_put_string(buffer, strlen(buffer));
1.38 markus 792: packet_send();
793: packet_write_wait();
794:
795: type = packet_read(&plen);
1.1 deraadt 796:
1.38 markus 797: if (type == SSH_SMSG_FAILURE)
798: debug("Kerberos TGT for realm %s rejected.", prealm);
799: else if (type != SSH_SMSG_SUCCESS)
800: packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
801:
802: return 1;
1.1 deraadt 803: }
804:
1.38 markus 805: void
806: send_afs_tokens(void)
1.1 deraadt 807: {
1.38 markus 808: CREDENTIALS creds;
809: struct ViceIoctl parms;
810: struct ClearToken ct;
811: int i, type, len, plen;
812: char buf[2048], *p, *server_cell;
1.57 markus 813: char buffer[8192];
1.38 markus 814:
815: /* Move over ktc_GetToken, here's something leaner. */
816: for (i = 0; i < 100; i++) { /* just in case */
817: parms.in = (char *) &i;
818: parms.in_size = sizeof(i);
819: parms.out = buf;
820: parms.out_size = sizeof(buf);
821: if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0)
822: break;
823: p = buf;
824:
825: /* Get secret token. */
826: memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
827: if (creds.ticket_st.length > MAX_KTXT_LEN)
828: break;
829: p += sizeof(unsigned int);
830: memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
831: p += creds.ticket_st.length;
832:
833: /* Get clear token. */
834: memcpy(&len, p, sizeof(len));
835: if (len != sizeof(struct ClearToken))
836: break;
837: p += sizeof(len);
838: memcpy(&ct, p, len);
839: p += len;
840: p += sizeof(len); /* primary flag */
841: server_cell = p;
842:
843: /* Flesh out our credentials. */
844: strlcpy(creds.service, "afs", sizeof creds.service);
845: creds.instance[0] = '\0';
846: strlcpy(creds.realm, server_cell, REALM_SZ);
847: memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
848: creds.issue_date = ct.BeginTimestamp;
849: creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
850: creds.kvno = ct.AuthHandle;
851: snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId);
852: creds.pinst[0] = '\0';
853:
854: /* Encode token, ship it off. */
1.57 markus 855: if (!creds_to_radix(&creds, (unsigned char*) buffer))
1.38 markus 856: break;
857: packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
1.57 markus 858: packet_put_string(buffer, strlen(buffer));
1.38 markus 859: packet_send();
860: packet_write_wait();
861:
862: /* Roger, Roger. Clearance, Clarence. What's your vector,
863: Victor? */
864: type = packet_read(&plen);
865:
866: if (type == SSH_SMSG_FAILURE)
867: debug("AFS token for cell %s rejected.", server_cell);
868: else if (type != SSH_SMSG_SUCCESS)
869: packet_disconnect("Protocol error on AFS token response: %d", type);
870: }
1.1 deraadt 871: }
1.38 markus 872:
1.1 deraadt 873: #endif /* AFS */
874:
1.39 deraadt 875: /*
1.43 markus 876: * Tries to authenticate with any string-based challenge/response system.
877: * Note that the client code is not tied to s/key or TIS.
878: */
879: int
880: try_skey_authentication()
881: {
1.57 markus 882: int type, i;
883: int payload_len;
884: unsigned int clen;
1.43 markus 885: char *challenge, *response;
886:
887: debug("Doing skey authentication.");
888:
889: /* request a challenge */
890: packet_start(SSH_CMSG_AUTH_TIS);
891: packet_send();
892: packet_write_wait();
893:
894: type = packet_read(&payload_len);
895: if (type != SSH_SMSG_FAILURE &&
896: type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
897: packet_disconnect("Protocol error: got %d in response "
898: "to skey-auth", type);
899: }
900: if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
901: debug("No challenge for skey authentication.");
902: return 0;
903: }
1.57 markus 904: challenge = packet_get_string(&clen);
905: packet_integrity_check(payload_len, (4 + clen), type);
1.43 markus 906: if (options.cipher == SSH_CIPHER_NONE)
907: log("WARNING: Encryption is disabled! "
908: "Reponse will be transmitted in clear text.");
909: fprintf(stderr, "%s\n", challenge);
1.54 markus 910: xfree(challenge);
1.43 markus 911: fflush(stderr);
912: for (i = 0; i < options.number_of_password_prompts; i++) {
913: if (i != 0)
914: error("Permission denied, please try again.");
915: response = read_passphrase("Response: ", 0);
916: packet_start(SSH_CMSG_AUTH_TIS_RESPONSE);
917: packet_put_string(response, strlen(response));
918: memset(response, 0, strlen(response));
919: xfree(response);
920: packet_send();
921: packet_write_wait();
922: type = packet_read(&payload_len);
923: if (type == SSH_SMSG_SUCCESS)
924: return 1;
925: if (type != SSH_SMSG_FAILURE)
926: packet_disconnect("Protocol error: got %d in response "
927: "to skey-auth-reponse", type);
928: }
929: /* failure */
930: return 0;
931: }
932:
933: /*
934: * Tries to authenticate with plain passwd authentication.
935: */
936: int
937: try_password_authentication(char *prompt)
938: {
939: int type, i, payload_len;
940: char *password;
941:
942: debug("Doing password authentication.");
943: if (options.cipher == SSH_CIPHER_NONE)
944: log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
945: for (i = 0; i < options.number_of_password_prompts; i++) {
946: if (i != 0)
947: error("Permission denied, please try again.");
948: password = read_passphrase(prompt, 0);
949: packet_start(SSH_CMSG_AUTH_PASSWORD);
950: packet_put_string(password, strlen(password));
951: memset(password, 0, strlen(password));
952: xfree(password);
953: packet_send();
954: packet_write_wait();
955:
956: type = packet_read(&payload_len);
957: if (type == SSH_SMSG_SUCCESS)
958: return 1;
959: if (type != SSH_SMSG_FAILURE)
960: packet_disconnect("Protocol error: got %d in response to passwd auth", type);
961: }
962: /* failure */
963: return 0;
964: }
965:
1.59 ! markus 966: char *
! 967: chop(char *s)
! 968: {
! 969: char *t = s;
! 970: while (*t) {
! 971: if(*t == '\n' || *t == '\r') {
! 972: *t = '\0';
! 973: return s;
! 974: }
! 975: t++;
! 976: }
! 977: return s;
! 978:
! 979: }
! 980:
1.43 markus 981: /*
1.39 deraadt 982: * Waits for the server identification string, and sends our own
983: * identification string.
984: */
1.38 markus 985: void
986: ssh_exchange_identification()
1.1 deraadt 987: {
1.38 markus 988: char buf[256], remote_version[256]; /* must be same size! */
989: int remote_major, remote_minor, i;
990: int connection_in = packet_get_connection_in();
991: int connection_out = packet_get_connection_out();
992:
993: /* Read other side\'s version identification. */
994: for (i = 0; i < sizeof(buf) - 1; i++) {
1.56 markus 995: int len = read(connection_in, &buf[i], 1);
996: if (len < 0)
1.38 markus 997: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
1.56 markus 998: if (len != 1)
999: fatal("ssh_exchange_identification: Connection closed by remote host");
1.38 markus 1000: if (buf[i] == '\r') {
1001: buf[i] = '\n';
1002: buf[i + 1] = 0;
1.59 ! markus 1003: continue; /**XXX wait for \n */
1.38 markus 1004: }
1005: if (buf[i] == '\n') {
1006: buf[i + 1] = 0;
1007: break;
1008: }
1009: }
1010: buf[sizeof(buf) - 1] = 0;
1.59 ! markus 1011: server_version_string = xstrdup(buf);
1.38 markus 1012:
1.40 markus 1013: /*
1014: * Check that the versions match. In future this might accept
1015: * several versions and set appropriate flags to handle them.
1016: */
1.59 ! markus 1017: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
! 1018: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 1019: fatal("Bad remote protocol version identification: '%.100s'", buf);
1020: debug("Remote protocol version %d.%d, remote software version %.100s",
1021: remote_major, remote_minor, remote_version);
1022:
1.59 ! markus 1023: /*** XXX option for disabling 2.0 or 1.5 */
! 1024: compat_datafellows(remote_version);
! 1025:
1.38 markus 1026: /* Check if the remote protocol version is too old. */
1027: if (remote_major == 1 && remote_minor < 3)
1028: fatal("Remote machine has too old SSH software version.");
1029:
1030: /* We speak 1.3, too. */
1031: if (remote_major == 1 && remote_minor == 3) {
1032: enable_compat13();
1.53 markus 1033: if (options.forward_agent) {
1034: log("Agent forwarding disabled for protocol 1.3");
1.38 markus 1035: options.forward_agent = 0;
1036: }
1037: }
1.59 ! markus 1038: if ((remote_major == 2 && remote_minor == 0) ||
! 1039: (remote_major == 1 && remote_minor == 99)) {
! 1040: enable_compat20();
! 1041: }
1.1 deraadt 1042: #if 0
1.40 markus 1043: /*
1044: * Removed for now, to permit compatibility with latter versions. The
1045: * server will reject our version and disconnect if it doesn't
1046: * support it.
1047: */
1.38 markus 1048: if (remote_major != PROTOCOL_MAJOR)
1049: fatal("Protocol major versions differ: %d vs. %d",
1050: PROTOCOL_MAJOR, remote_major);
1.1 deraadt 1051: #endif
1.38 markus 1052: /* Send our own protocol version identification. */
1053: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.59 ! markus 1054: compat20 ? 2 : PROTOCOL_MAJOR,
! 1055: compat20 ? 0 : PROTOCOL_MINOR,
! 1056: SSH_VERSION);
1.45 deraadt 1057: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 1058: fatal("write: %.100s", strerror(errno));
1.59 ! markus 1059: client_version_string = xstrdup(buf);
! 1060: chop(client_version_string);
! 1061: chop(server_version_string);
! 1062: debug("Local version string %.100s", client_version_string);
1.1 deraadt 1063: }
1064:
1.38 markus 1065: int
1066: read_yes_or_no(const char *prompt, int defval)
1.1 deraadt 1067: {
1.38 markus 1068: char buf[1024];
1069: FILE *f;
1070: int retval = -1;
1071:
1072: if (isatty(0))
1073: f = stdin;
1074: else
1075: f = fopen("/dev/tty", "rw");
1076:
1077: if (f == NULL)
1078: return 0;
1079:
1080: fflush(stdout);
1081:
1082: while (1) {
1083: fprintf(stderr, "%s", prompt);
1084: if (fgets(buf, sizeof(buf), f) == NULL) {
1085: /* Print a newline (the prompt probably didn\'t have one). */
1086: fprintf(stderr, "\n");
1087: strlcpy(buf, "no", sizeof buf);
1088: }
1089: /* Remove newline from response. */
1090: if (strchr(buf, '\n'))
1091: *strchr(buf, '\n') = 0;
1092:
1093: if (buf[0] == 0)
1094: retval = defval;
1095: if (strcmp(buf, "yes") == 0)
1096: retval = 1;
1097: if (strcmp(buf, "no") == 0)
1098: retval = 0;
1099:
1100: if (retval != -1) {
1101: if (f != stdin)
1102: fclose(f);
1103: return retval;
1104: }
1.1 deraadt 1105: }
1106: }
1107:
1.39 deraadt 1108: /*
1.46 markus 1109: * check whether the supplied host key is valid, return only if ok.
1.39 deraadt 1110: */
1.46 markus 1111:
1.38 markus 1112: void
1.58 markus 1113: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1.1 deraadt 1114: {
1.58 markus 1115: Key *file_key;
1.46 markus 1116: char *ip = NULL;
1.38 markus 1117: char hostline[1000], *hostp;
1118: HostStatus host_status;
1119: HostStatus ip_status;
1.49 markus 1120: int local = 0, host_ip_differ = 0;
1121: char ntop[NI_MAXHOST];
1122:
1123: /*
1124: * Force accepting of the host key for loopback/localhost. The
1125: * problem is that if the home directory is NFS-mounted to multiple
1126: * machines, localhost will refer to a different machine in each of
1127: * them, and the user will get bogus HOST_CHANGED warnings. This
1128: * essentially disables host authentication for localhost; however,
1129: * this is probably not a real problem.
1130: */
1131: switch (hostaddr->sa_family) {
1132: case AF_INET:
1133: local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1134: break;
1135: case AF_INET6:
1136: local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1137: break;
1138: default:
1139: local = 0;
1140: break;
1141: }
1142: if (local) {
1143: debug("Forcing accepting of host key for loopback/localhost.");
1144: return;
1145: }
1.42 markus 1146:
1147: /*
1.44 markus 1148: * Turn off check_host_ip for proxy connects, since
1.42 markus 1149: * we don't have the remote ip-address
1150: */
1151: if (options.proxy_command != NULL && options.check_host_ip)
1152: options.check_host_ip = 0;
1.38 markus 1153:
1.49 markus 1154: if (options.check_host_ip) {
1155: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1156: NULL, 0, NI_NUMERICHOST) != 0)
1157: fatal("check_host_key: getnameinfo failed");
1158: ip = xstrdup(ntop);
1159: }
1.38 markus 1160:
1.46 markus 1161: /*
1162: * Store the host key from the known host file in here so that we can
1163: * compare it with the key for the IP address.
1164: */
1.58 markus 1165: file_key = key_new(host_key->type);
1.38 markus 1166:
1.40 markus 1167: /*
1168: * Check if the host key is present in the user\'s list of known
1169: * hosts or in the systemwide list.
1170: */
1.58 markus 1171: host_status = check_host_in_hostfile(options.user_hostfile, host, host_key, file_key);
1.38 markus 1172: if (host_status == HOST_NEW)
1.58 markus 1173: host_status = check_host_in_hostfile(options.system_hostfile, host, host_key, file_key);
1.40 markus 1174: /*
1175: * Also perform check for the ip address, skip the check if we are
1176: * localhost or the hostname was an ip address to begin with
1177: */
1.38 markus 1178: if (options.check_host_ip && !local && strcmp(host, ip)) {
1.58 markus 1179: Key *ip_key = key_new(host_key->type);
1180: ip_status = check_host_in_hostfile(options.user_hostfile, ip, host_key, ip_key);
1.38 markus 1181:
1182: if (ip_status == HOST_NEW)
1.58 markus 1183: ip_status = check_host_in_hostfile(options.system_hostfile, ip, host_key, ip_key);
1.38 markus 1184: if (host_status == HOST_CHANGED &&
1.58 markus 1185: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 1186: host_ip_differ = 1;
1187:
1.58 markus 1188: key_free(ip_key);
1.38 markus 1189: } else
1190: ip_status = host_status;
1191:
1.58 markus 1192: key_free(file_key);
1.38 markus 1193:
1194: switch (host_status) {
1195: case HOST_OK:
1196: /* The host is known and the key matches. */
1197: debug("Host '%.200s' is known and matches the host key.", host);
1198: if (options.check_host_ip) {
1199: if (ip_status == HOST_NEW) {
1.58 markus 1200: if (!add_host_to_hostfile(options.user_hostfile, ip, host_key))
1.38 markus 1201: log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).",
1202: ip, options.user_hostfile);
1203: else
1204: log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.",
1205: ip);
1206: } else if (ip_status != HOST_OK)
1207: log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'",
1208: host, ip);
1209: }
1210: break;
1211: case HOST_NEW:
1212: /* The host is new. */
1213: if (options.strict_host_key_checking == 1) {
1214: /* User has requested strict host key checking. We will not add the host key
1215: automatically. The only alternative left is to abort. */
1216: fatal("No host key is known for %.200s and you have requested strict checking.", host);
1217: } else if (options.strict_host_key_checking == 2) {
1218: /* The default */
1219: char prompt[1024];
1.58 markus 1220: char *fp = key_fingerprint(host_key);
1.38 markus 1221: snprintf(prompt, sizeof(prompt),
1.45 deraadt 1222: "The authenticity of host '%.200s' can't be established.\n"
1.58 markus 1223: "Key fingerprint is %s.\n"
1.45 deraadt 1224: "Are you sure you want to continue connecting (yes/no)? ",
1.58 markus 1225: host, fp);
1.38 markus 1226: if (!read_yes_or_no(prompt, -1))
1227: fatal("Aborted by user!\n");
1228: }
1229: if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) {
1230: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1231: hostp = hostline;
1232: } else
1233: hostp = host;
1234:
1235: /* If not in strict mode, add the key automatically to the local known_hosts file. */
1.58 markus 1236: if (!add_host_to_hostfile(options.user_hostfile, hostp, host_key))
1.38 markus 1237: log("Failed to add the host to the list of known hosts (%.500s).",
1238: options.user_hostfile);
1239: else
1240: log("Warning: Permanently added '%.200s' to the list of known hosts.",
1241: hostp);
1242: break;
1243: case HOST_CHANGED:
1244: if (options.check_host_ip && host_ip_differ) {
1245: char *msg;
1246: if (ip_status == HOST_NEW)
1247: msg = "is unknown";
1248: else if (ip_status == HOST_OK)
1249: msg = "is unchanged";
1250: else
1251: msg = "has a different value";
1252: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1253: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1254: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1255: error("The host key for %s has changed,", host);
1256: error("and the key for the according IP address %s", ip);
1257: error("%s. This could either mean that", msg);
1258: error("DNS SPOOFING is happening or the IP address for the host");
1259: error("and its host key have changed at the same time");
1260: }
1261: /* The host key has changed. */
1262: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 1263: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 1264: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1265: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1266: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1267: error("It is also possible that the host key has just been changed.");
1268: error("Please contact your system administrator.");
1269: error("Add correct host key in %.100s to get rid of this message.",
1270: options.user_hostfile);
1271:
1.40 markus 1272: /*
1273: * If strict host key checking is in use, the user will have
1274: * to edit the key manually and we can only abort.
1275: */
1.38 markus 1276: if (options.strict_host_key_checking)
1277: fatal("Host key for %.200s has changed and you have requested strict checking.", host);
1278:
1.40 markus 1279: /*
1280: * If strict host key checking has not been requested, allow
1281: * the connection but without password authentication or
1282: * agent forwarding.
1283: */
1.38 markus 1284: if (options.password_authentication) {
1285: error("Password authentication is disabled to avoid trojan horses.");
1286: options.password_authentication = 0;
1287: }
1288: if (options.forward_agent) {
1289: error("Agent forwarding is disabled to avoid trojan horses.");
1290: options.forward_agent = 0;
1291: }
1.40 markus 1292: /*
1293: * XXX Should permit the user to change to use the new id.
1294: * This could be done by converting the host key to an
1295: * identifying sentence, tell that the host identifies itself
1296: * by that sentence, and ask the user if he/she whishes to
1297: * accept the authentication.
1298: */
1.38 markus 1299: break;
1300: }
1301: if (options.check_host_ip)
1302: xfree(ip);
1.46 markus 1303: }
1.58 markus 1304: void
1305: check_rsa_host_key(char *host, struct sockaddr *hostaddr, RSA *host_key)
1306: {
1307: Key k;
1308: k.type = KEY_RSA;
1309: k.rsa = host_key;
1310: check_host_key(host, hostaddr, &k);
1311: }
1.46 markus 1312:
1313: /*
1.59 ! markus 1314: * SSH2 key exchange
! 1315: */
! 1316: void
! 1317: ssh_kex2(char *host, struct sockaddr *hostaddr)
! 1318: {
! 1319: Kex *kex;
! 1320: char *cprop[PROPOSAL_MAX];
! 1321: char *sprop[PROPOSAL_MAX];
! 1322: Buffer *client_kexinit;
! 1323: Buffer *server_kexinit;
! 1324: int payload_len, dlen;
! 1325: unsigned int klen, kout;
! 1326: char *ptr;
! 1327: char *signature = NULL;
! 1328: unsigned int slen;
! 1329: char *server_host_key_blob = NULL;
! 1330: Key *server_host_key;
! 1331: unsigned int sbloblen;
! 1332: DH *dh;
! 1333: BIGNUM *dh_server_pub = 0;
! 1334: BIGNUM *shared_secret = 0;
! 1335: int i;
! 1336: unsigned char *kbuf;
! 1337: unsigned char *hash;
! 1338:
! 1339: /* KEXINIT */
! 1340:
! 1341: debug("Sending KEX init.");
! 1342: if (options.cipher == SSH_CIPHER_ARCFOUR ||
! 1343: options.cipher == SSH_CIPHER_3DES_CBC ||
! 1344: options.cipher == SSH_CIPHER_CAST128_CBC ||
! 1345: options.cipher == SSH_CIPHER_BLOWFISH_CBC) {
! 1346: myproposal[PROPOSAL_ENC_ALGS_CTOS] = cipher_name(options.cipher);
! 1347: myproposal[PROPOSAL_ENC_ALGS_STOC] = cipher_name(options.cipher);
! 1348: }
! 1349: if (options.compression) {
! 1350: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
! 1351: myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
! 1352: } else {
! 1353: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
! 1354: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
! 1355: }
! 1356: for (i = 0; i < PROPOSAL_MAX; i++)
! 1357: cprop[i] = xstrdup(myproposal[i]);
! 1358:
! 1359: client_kexinit = kex_init(cprop);
! 1360: packet_start(SSH2_MSG_KEXINIT);
! 1361: packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));
! 1362: packet_send();
! 1363: packet_write_wait();
! 1364:
! 1365: debug("done");
! 1366:
! 1367: packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
! 1368:
! 1369: /* save payload for session_id */
! 1370: server_kexinit = xmalloc(sizeof(*server_kexinit));
! 1371: buffer_init(server_kexinit);
! 1372: ptr = packet_get_raw(&payload_len);
! 1373: buffer_append(server_kexinit, ptr, payload_len);
! 1374:
! 1375: /* skip cookie */
! 1376: for (i = 0; i < 16; i++)
! 1377: (void) packet_get_char();
! 1378: /* kex init proposal strings */
! 1379: for (i = 0; i < PROPOSAL_MAX; i++) {
! 1380: sprop[i] = packet_get_string(NULL);
! 1381: debug("got kexinit string: %s", sprop[i]);
! 1382: }
! 1383: i = (int) packet_get_char();
! 1384: debug("first kex follow == %d", i);
! 1385: i = packet_get_int();
! 1386: debug("reserved == %d", i);
! 1387:
! 1388: debug("done read kexinit");
! 1389: kex = kex_choose_conf(cprop, sprop, 0);
! 1390:
! 1391: /* KEXDH */
! 1392:
! 1393: debug("Sending SSH2_MSG_KEXDH_INIT.");
! 1394:
! 1395: /* generate and send 'e', client DH public key */
! 1396: dh = new_dh_group1();
! 1397: packet_start(SSH2_MSG_KEXDH_INIT);
! 1398: packet_put_bignum2(dh->pub_key);
! 1399: packet_send();
! 1400: packet_write_wait();
! 1401:
! 1402: #ifdef DEBUG_KEXDH
! 1403: fprintf(stderr, "\np= ");
! 1404: bignum_print(dh->p);
! 1405: fprintf(stderr, "\ng= ");
! 1406: bignum_print(dh->g);
! 1407: fprintf(stderr, "\npub= ");
! 1408: bignum_print(dh->pub_key);
! 1409: fprintf(stderr, "\n");
! 1410: DHparams_print_fp(stderr, dh);
! 1411: #endif
! 1412:
! 1413: debug("Wait SSH2_MSG_KEXDH_REPLY.");
! 1414:
! 1415: packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);
! 1416:
! 1417: debug("Got SSH2_MSG_KEXDH_REPLY.");
! 1418:
! 1419: /* key, cert */
! 1420: server_host_key_blob = packet_get_string(&sbloblen);
! 1421: server_host_key = dsa_serverkey_from_blob(server_host_key_blob, sbloblen);
! 1422: if (server_host_key == NULL)
! 1423: fatal("cannot decode server_host_key_blob");
! 1424:
! 1425: check_host_key(host, hostaddr, server_host_key);
! 1426:
! 1427: /* DH paramter f, server public DH key */
! 1428: dh_server_pub = BN_new();
! 1429: if (dh_server_pub == NULL)
! 1430: fatal("dh_server_pub == NULL");
! 1431: packet_get_bignum2(dh_server_pub, &dlen);
! 1432:
! 1433: #ifdef DEBUG_KEXDH
! 1434: fprintf(stderr, "\ndh_server_pub= ");
! 1435: bignum_print(dh_server_pub);
! 1436: fprintf(stderr, "\n");
! 1437: debug("bits %d", BN_num_bits(dh_server_pub));
! 1438: #endif
! 1439:
! 1440: /* signed H */
! 1441: signature = packet_get_string(&slen);
! 1442:
! 1443: klen = DH_size(dh);
! 1444: kbuf = xmalloc(klen);
! 1445: kout = DH_compute_key(kbuf, dh_server_pub, dh);
! 1446: #ifdef DEBUG_KEXDH
! 1447: debug("shared secret: len %d/%d", klen, kout);
! 1448: fprintf(stderr, "shared secret == ");
! 1449: for (i = 0; i< kout; i++)
! 1450: fprintf(stderr, "%02x", (kbuf[i])&0xff);
! 1451: fprintf(stderr, "\n");
! 1452: #endif
! 1453: shared_secret = BN_new();
! 1454:
! 1455: BN_bin2bn(kbuf, kout, shared_secret);
! 1456: memset(kbuf, 0, klen);
! 1457: xfree(kbuf);
! 1458:
! 1459: /* calc and verify H */
! 1460: hash = kex_hash(
! 1461: client_version_string,
! 1462: server_version_string,
! 1463: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
! 1464: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
! 1465: server_host_key_blob, sbloblen,
! 1466: dh->pub_key,
! 1467: dh_server_pub,
! 1468: shared_secret
! 1469: );
! 1470: buffer_clear(client_kexinit);
! 1471: buffer_clear(server_kexinit);
! 1472: xfree(client_kexinit);
! 1473: xfree(server_kexinit);
! 1474: #ifdef DEBUG_KEXDH
! 1475: fprintf(stderr, "hash == ");
! 1476: for (i = 0; i< 20; i++)
! 1477: fprintf(stderr, "%02x", (hash[i])&0xff);
! 1478: fprintf(stderr, "\n");
! 1479: #endif
! 1480: dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20);
! 1481: key_free(server_host_key);
! 1482:
! 1483: kex_derive_keys(kex, hash, shared_secret);
! 1484: packet_set_kex(kex);
! 1485:
! 1486: /* have keys, free DH */
! 1487: DH_free(dh);
! 1488:
! 1489: debug("Wait SSH2_MSG_NEWKEYS.");
! 1490: packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
! 1491: debug("GOT SSH2_MSG_NEWKEYS.");
! 1492:
! 1493: debug("send SSH2_MSG_NEWKEYS.");
! 1494: packet_start(SSH2_MSG_NEWKEYS);
! 1495: packet_send();
! 1496: packet_write_wait();
! 1497: debug("done: send SSH2_MSG_NEWKEYS.");
! 1498:
! 1499: /* send 1st encrypted/maced/compressed message */
! 1500: packet_start(SSH2_MSG_IGNORE);
! 1501: packet_put_cstring("markus");
! 1502: packet_send();
! 1503: packet_write_wait();
! 1504:
! 1505: debug("done: KEX2.");
! 1506: }
! 1507: /*
! 1508: * Authenticate user
! 1509: */
! 1510: void
! 1511: ssh_userauth2(int host_key_valid, RSA *own_host_key,
! 1512: uid_t original_real_uid, char *host)
! 1513: {
! 1514: int type;
! 1515: int plen;
! 1516: unsigned int dlen;
! 1517: int partial;
! 1518: struct passwd *pw;
! 1519: char *server_user, *local_user;
! 1520: char *auths;
! 1521: char *password;
! 1522: char *service = "ssh-connection"; // service name
! 1523:
! 1524: debug("send SSH2_MSG_SERVICE_REQUEST");
! 1525: packet_start(SSH2_MSG_SERVICE_REQUEST);
! 1526: packet_put_cstring("ssh-userauth");
! 1527: packet_send();
! 1528: packet_write_wait();
! 1529:
! 1530: type = packet_read(&plen);
! 1531: if (type != SSH2_MSG_SERVICE_ACCEPT) {
! 1532: fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
! 1533: }
! 1534: /* payload empty for ssh-2.0.13 ?? */
! 1535: /* reply = packet_get_string(&payload_len); */
! 1536: debug("got SSH2_MSG_SERVICE_ACCEPT");
! 1537:
! 1538: /*XX COMMONCODE: */
! 1539: /* Get local user name. Use it as server user if no user name was given. */
! 1540: pw = getpwuid(original_real_uid);
! 1541: if (!pw)
! 1542: fatal("User id %d not found from user database.", original_real_uid);
! 1543: local_user = xstrdup(pw->pw_name);
! 1544: server_user = options.user ? options.user : local_user;
! 1545:
! 1546: /* INITIAL request for auth */
! 1547: packet_start(SSH2_MSG_USERAUTH_REQUEST);
! 1548: packet_put_cstring(server_user);
! 1549: packet_put_cstring(service);
! 1550: packet_put_cstring("none");
! 1551: packet_send();
! 1552: packet_write_wait();
! 1553:
! 1554: for (;;) {
! 1555: type = packet_read(&plen);
! 1556: if (type == SSH2_MSG_USERAUTH_SUCCESS)
! 1557: break;
! 1558: if (type != SSH2_MSG_USERAUTH_FAILURE)
! 1559: fatal("access denied: %d", type);
! 1560: /* SSH2_MSG_USERAUTH_FAILURE means: try again */
! 1561: auths = packet_get_string(&dlen);
! 1562: debug("authentications that can continue: %s", auths);
! 1563: partial = packet_get_char();
! 1564: if (partial)
! 1565: debug("partial success");
! 1566: if (strstr(auths, "password") == NULL)
! 1567: fatal("passwd auth not supported: %s", auths);
! 1568: xfree(auths);
! 1569: /* try passwd */
! 1570: password = read_passphrase("password: ", 0);
! 1571: packet_start(SSH2_MSG_USERAUTH_REQUEST);
! 1572: packet_put_cstring(server_user);
! 1573: packet_put_cstring(service);
! 1574: packet_put_cstring("password");
! 1575: packet_put_char(0);
! 1576: packet_put_cstring(password);
! 1577: memset(password, 0, strlen(password));
! 1578: xfree(password);
! 1579: packet_send();
! 1580: packet_write_wait();
! 1581: }
! 1582: debug("ssh-userauth2 successfull");
! 1583: }
! 1584:
! 1585: /*
1.51 markus 1586: * SSH1 key exchange
1.46 markus 1587: */
1588: void
1.51 markus 1589: ssh_kex(char *host, struct sockaddr *hostaddr)
1.46 markus 1590: {
1.51 markus 1591: int i;
1.46 markus 1592: BIGNUM *key;
1593: RSA *host_key;
1594: RSA *public_key;
1595: int bits, rbits;
1.59 ! markus 1596: int ssh_cipher_default = SSH_CIPHER_3DES;
1.46 markus 1597: unsigned char session_key[SSH_SESSION_KEY_LENGTH];
1.51 markus 1598: unsigned char cookie[8];
1599: unsigned int supported_ciphers;
1.46 markus 1600: unsigned int server_flags, client_flags;
1601: int payload_len, clen, sum_len = 0;
1602: u_int32_t rand = 0;
1603:
1604: debug("Waiting for server public key.");
1605:
1606: /* Wait for a public key packet from the server. */
1607: packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
1608:
1.51 markus 1609: /* Get cookie from the packet. */
1.46 markus 1610: for (i = 0; i < 8; i++)
1.51 markus 1611: cookie[i] = packet_get_char();
1.46 markus 1612:
1613: /* Get the public key. */
1614: public_key = RSA_new();
1615: bits = packet_get_int();/* bits */
1616: public_key->e = BN_new();
1617: packet_get_bignum(public_key->e, &clen);
1618: sum_len += clen;
1619: public_key->n = BN_new();
1620: packet_get_bignum(public_key->n, &clen);
1621: sum_len += clen;
1622:
1623: rbits = BN_num_bits(public_key->n);
1624: if (bits != rbits) {
1625: log("Warning: Server lies about size of server public key: "
1626: "actual size is %d bits vs. announced %d.", rbits, bits);
1627: log("Warning: This may be due to an old implementation of ssh.");
1628: }
1629: /* Get the host key. */
1630: host_key = RSA_new();
1631: bits = packet_get_int();/* bits */
1632: host_key->e = BN_new();
1633: packet_get_bignum(host_key->e, &clen);
1634: sum_len += clen;
1635: host_key->n = BN_new();
1636: packet_get_bignum(host_key->n, &clen);
1637: sum_len += clen;
1638:
1639: rbits = BN_num_bits(host_key->n);
1640: if (bits != rbits) {
1641: log("Warning: Server lies about size of server host key: "
1642: "actual size is %d bits vs. announced %d.", rbits, bits);
1643: log("Warning: This may be due to an old implementation of ssh.");
1644: }
1645:
1646: /* Get protocol flags. */
1647: server_flags = packet_get_int();
1648: packet_set_protocol_flags(server_flags);
1649:
1650: supported_ciphers = packet_get_int();
1651: supported_authentications = packet_get_int();
1652:
1653: debug("Received server public key (%d bits) and host key (%d bits).",
1654: BN_num_bits(public_key->n), BN_num_bits(host_key->n));
1655:
1656: packet_integrity_check(payload_len,
1657: 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
1658: SSH_SMSG_PUBLIC_KEY);
1659:
1.58 markus 1660: check_rsa_host_key(host, hostaddr, host_key);
1.46 markus 1661:
1662: client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN;
1663:
1.51 markus 1664: compute_session_id(session_id, cookie, host_key->n, public_key->n);
1.38 markus 1665:
1666: /* Generate a session key. */
1667: arc4random_stir();
1668:
1.40 markus 1669: /*
1670: * Generate an encryption key for the session. The key is a 256 bit
1671: * random number, interpreted as a 32-byte key, with the least
1672: * significant 8 bits being the first byte of the key.
1673: */
1.38 markus 1674: for (i = 0; i < 32; i++) {
1675: if (i % 4 == 0)
1676: rand = arc4random();
1677: session_key[i] = rand & 0xff;
1678: rand >>= 8;
1679: }
1680:
1.40 markus 1681: /*
1682: * According to the protocol spec, the first byte of the session key
1683: * is the highest byte of the integer. The session key is xored with
1684: * the first 16 bytes of the session id.
1685: */
1.38 markus 1686: key = BN_new();
1687: BN_set_word(key, 0);
1688: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
1689: BN_lshift(key, key, 8);
1690: if (i < 16)
1691: BN_add_word(key, session_key[i] ^ session_id[i]);
1692: else
1693: BN_add_word(key, session_key[i]);
1694: }
1695:
1.40 markus 1696: /*
1697: * Encrypt the integer using the public key and host key of the
1698: * server (key with smaller modulus first).
1699: */
1.38 markus 1700: if (BN_cmp(public_key->n, host_key->n) < 0) {
1701: /* Public key has smaller modulus. */
1702: if (BN_num_bits(host_key->n) <
1703: BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) {
1704: fatal("respond_to_rsa_challenge: host_key %d < public_key %d + "
1705: "SSH_KEY_BITS_RESERVED %d",
1706: BN_num_bits(host_key->n),
1707: BN_num_bits(public_key->n),
1708: SSH_KEY_BITS_RESERVED);
1709: }
1710: rsa_public_encrypt(key, key, public_key);
1711: rsa_public_encrypt(key, key, host_key);
1712: } else {
1713: /* Host key has smaller modulus (or they are equal). */
1714: if (BN_num_bits(public_key->n) <
1715: BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) {
1716: fatal("respond_to_rsa_challenge: public_key %d < host_key %d + "
1717: "SSH_KEY_BITS_RESERVED %d",
1718: BN_num_bits(public_key->n),
1719: BN_num_bits(host_key->n),
1720: SSH_KEY_BITS_RESERVED);
1721: }
1722: rsa_public_encrypt(key, key, host_key);
1723: rsa_public_encrypt(key, key, public_key);
1724: }
1725:
1.52 markus 1726: /* Destroy the public keys since we no longer need them. */
1727: RSA_free(public_key);
1728: RSA_free(host_key);
1729:
1.38 markus 1730: if (options.cipher == SSH_CIPHER_NOT_SET) {
1731: if (cipher_mask() & supported_ciphers & (1 << ssh_cipher_default))
1732: options.cipher = ssh_cipher_default;
1733: else {
1734: debug("Cipher %s not supported, using %.100s instead.",
1735: cipher_name(ssh_cipher_default),
1736: cipher_name(SSH_FALLBACK_CIPHER));
1737: options.cipher = SSH_FALLBACK_CIPHER;
1738: }
1739: }
1740: /* Check that the selected cipher is supported. */
1741: if (!(supported_ciphers & (1 << options.cipher)))
1742: fatal("Selected cipher type %.100s not supported by server.",
1743: cipher_name(options.cipher));
1744:
1745: debug("Encryption type: %.100s", cipher_name(options.cipher));
1746:
1747: /* Send the encrypted session key to the server. */
1748: packet_start(SSH_CMSG_SESSION_KEY);
1749: packet_put_char(options.cipher);
1750:
1.51 markus 1751: /* Send the cookie back to the server. */
1.38 markus 1752: for (i = 0; i < 8; i++)
1.51 markus 1753: packet_put_char(cookie[i]);
1.38 markus 1754:
1.52 markus 1755: /* Send and destroy the encrypted encryption key integer. */
1.38 markus 1756: packet_put_bignum(key);
1.52 markus 1757: BN_clear_free(key);
1.38 markus 1758:
1759: /* Send protocol flags. */
1.46 markus 1760: packet_put_int(client_flags);
1.38 markus 1761:
1762: /* Send the packet now. */
1763: packet_send();
1764: packet_write_wait();
1765:
1766: debug("Sent encrypted session key.");
1767:
1768: /* Set the encryption key. */
1769: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher);
1770:
1771: /* We will no longer need the session key here. Destroy any extra copies. */
1772: memset(session_key, 0, sizeof(session_key));
1773:
1.40 markus 1774: /*
1775: * Expect a success message from the server. Note that this message
1776: * will be received in encrypted form.
1777: */
1.38 markus 1778: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1779:
1780: debug("Received encrypted confirmation.");
1.51 markus 1781: }
1782:
1783: /*
1784: * Authenticate user
1785: */
1786: void
1787: ssh_userauth(int host_key_valid, RSA *own_host_key,
1788: uid_t original_real_uid, char *host)
1789: {
1790: int i, type;
1791: int payload_len;
1792: struct passwd *pw;
1793: const char *server_user, *local_user;
1794:
1795: /* Get local user name. Use it as server user if no user name was given. */
1796: pw = getpwuid(original_real_uid);
1797: if (!pw)
1798: fatal("User id %d not found from user database.", original_real_uid);
1799: local_user = xstrdup(pw->pw_name);
1800: server_user = options.user ? options.user : local_user;
1.38 markus 1801:
1802: /* Send the name of the user to log in as on the server. */
1803: packet_start(SSH_CMSG_USER);
1804: packet_put_string(server_user, strlen(server_user));
1.16 dugsong 1805: packet_send();
1806: packet_write_wait();
1.38 markus 1807:
1.40 markus 1808: /*
1809: * The server should respond with success if no authentication is
1810: * needed (the user has no password). Otherwise the server responds
1811: * with failure.
1812: */
1.16 dugsong 1813: type = packet_read(&payload_len);
1.38 markus 1814:
1815: /* check whether the connection was accepted without authentication. */
1.16 dugsong 1816: if (type == SSH_SMSG_SUCCESS)
1.38 markus 1817: return;
1.16 dugsong 1818: if (type != SSH_SMSG_FAILURE)
1.38 markus 1819: packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
1820: type);
1821:
1822: #ifdef AFS
1823: /* Try Kerberos tgt passing if the server supports it. */
1824: if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
1825: options.kerberos_tgt_passing) {
1826: if (options.cipher == SSH_CIPHER_NONE)
1827: log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
1828: (void) send_kerberos_tgt();
1829: }
1830: /* Try AFS token passing if the server supports it. */
1831: if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
1832: options.afs_token_passing && k_hasafs()) {
1833: if (options.cipher == SSH_CIPHER_NONE)
1834: log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
1835: send_afs_tokens();
1836: }
1837: #endif /* AFS */
1838:
1839: #ifdef KRB4
1840: if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
1841: options.kerberos_authentication) {
1842: debug("Trying Kerberos authentication.");
1843: if (try_kerberos_authentication()) {
1844: /* The server should respond with success or failure. */
1845: type = packet_read(&payload_len);
1846: if (type == SSH_SMSG_SUCCESS)
1847: return;
1848: if (type != SSH_SMSG_FAILURE)
1849: packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
1850: }
1851: }
1852: #endif /* KRB4 */
1853:
1.40 markus 1854: /*
1855: * Use rhosts authentication if running in privileged socket and we
1856: * do not wish to remain anonymous.
1857: */
1.38 markus 1858: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
1859: options.rhosts_authentication) {
1860: debug("Trying rhosts authentication.");
1861: packet_start(SSH_CMSG_AUTH_RHOSTS);
1862: packet_put_string(local_user, strlen(local_user));
1863: packet_send();
1864: packet_write_wait();
1865:
1866: /* The server should respond with success or failure. */
1867: type = packet_read(&payload_len);
1868: if (type == SSH_SMSG_SUCCESS)
1869: return;
1870: if (type != SSH_SMSG_FAILURE)
1871: packet_disconnect("Protocol error: got %d in response to rhosts auth",
1872: type);
1873: }
1.40 markus 1874: /*
1875: * Try .rhosts or /etc/hosts.equiv authentication with RSA host
1876: * authentication.
1877: */
1.38 markus 1878: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
1879: options.rhosts_rsa_authentication && host_key_valid) {
1880: if (try_rhosts_rsa_authentication(local_user, own_host_key))
1881: return;
1882: }
1883: /* Try RSA authentication if the server supports it. */
1884: if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
1885: options.rsa_authentication) {
1.40 markus 1886: /*
1887: * Try RSA authentication using the authentication agent. The
1888: * agent is tried first because no passphrase is needed for
1889: * it, whereas identity files may require passphrases.
1890: */
1.38 markus 1891: if (try_agent_authentication())
1892: return;
1893:
1894: /* Try RSA authentication for each identity. */
1895: for (i = 0; i < options.num_identity_files; i++)
1.43 markus 1896: if (try_rsa_authentication(options.identity_files[i]))
1.38 markus 1897: return;
1898: }
1899: /* Try skey authentication if the server supports it. */
1900: if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
1901: options.skey_authentication && !options.batch_mode) {
1.43 markus 1902: if (try_skey_authentication())
1903: return;
1.38 markus 1904: }
1905: /* Try password authentication if the server supports it. */
1906: if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
1907: options.password_authentication && !options.batch_mode) {
1908: char prompt[80];
1.45 deraadt 1909:
1.43 markus 1910: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1.45 deraadt 1911: server_user, host);
1.43 markus 1912: if (try_password_authentication(prompt))
1913: return;
1.38 markus 1914: }
1915: /* All authentication methods have failed. Exit with an error message. */
1916: fatal("Permission denied.");
1917: /* NOTREACHED */
1.51 markus 1918: }
1919: /*
1920: * Starts a dialog with the server, and authenticates the current user on the
1921: * server. This does not need any extra privileges. The basic connection
1922: * to the server must already have been established before this is called.
1923: * If login fails, this function prints an error and never returns.
1924: * This function does not require super-user privileges.
1925: */
1926: void
1927: ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
1928: struct sockaddr *hostaddr, uid_t original_real_uid)
1929: {
1930: char *host, *cp;
1931:
1932: /* Convert the user-supplied hostname into all lowercase. */
1933: host = xstrdup(orighost);
1934: for (cp = host; *cp; cp++)
1935: if (isupper(*cp))
1936: *cp = tolower(*cp);
1937:
1938: /* Exchange protocol version identification strings with the server. */
1939: ssh_exchange_identification();
1940:
1941: /* Put the connection into non-blocking mode. */
1942: packet_set_nonblocking();
1943:
1944: /* key exchange */
1945: /* authenticate user */
1.59 ! markus 1946: if (compat20) {
! 1947: ssh_kex2(host, hostaddr);
! 1948: ssh_userauth2(host_key_valid, own_host_key, original_real_uid, host);
! 1949: } else {
! 1950: supported_authentications = 0;
! 1951: ssh_kex(host, hostaddr);
! 1952: if (supported_authentications == 0)
! 1953: fatal("supported_authentications == 0.");
! 1954: ssh_userauth(host_key_valid, own_host_key, original_real_uid, host);
! 1955: }
1.1 deraadt 1956: }
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