Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.67
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"
1.67 ! markus 13: RCSID("$OpenBSD: sshconnect.c,v 1.66 2000/04/12 09:39:10 markus Exp $");
1.1 deraadt 14:
1.66 markus 15: #include <openssl/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"
1.66 markus 29: #include <openssl/rsa.h>
30: #include <openssl/dsa.h>
1.59 markus 31:
32: #include "ssh2.h"
1.66 markus 33: #include <openssl/md5.h>
34: #include <openssl/dh.h>
35: #include <openssl/hmac.h>
1.59 markus 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! */
1.64 markus 989: int remote_major, remote_minor, i, mismatch;
1.38 markus 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: compat_datafellows(remote_version);
1.64 markus 1024: mismatch = 0;
1.59 markus 1025:
1.64 markus 1026: switch(remote_major) {
1027: case 1:
1028: if (remote_minor == 99 &&
1029: (options.protocol & SSH_PROTO_2) &&
1030: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
1031: enable_compat20();
1032: break;
1033: }
1034: if (!(options.protocol & SSH_PROTO_1)) {
1035: mismatch = 1;
1036: break;
1037: }
1038: if (remote_minor < 3) {
1039: fatal("Remote machine has too old SSH software version.");
1040: } else if (remote_minor == 3) {
1041: /* We speak 1.3, too. */
1042: enable_compat13();
1043: if (options.forward_agent) {
1044: log("Agent forwarding disabled for protocol 1.3");
1045: options.forward_agent = 0;
1046: }
1047: }
1048: break;
1049: case 2:
1050: if (options.protocol & SSH_PROTO_2) {
1051: enable_compat20();
1052: break;
1.38 markus 1053: }
1.64 markus 1054: /* FALLTHROUGH */
1055: default:
1056: mismatch = 1;
1057: break;
1.38 markus 1058: }
1.64 markus 1059: if (mismatch)
1.38 markus 1060: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 1061: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1062: remote_major);
1063:
1.38 markus 1064: /* Send our own protocol version identification. */
1065: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 1066: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.65 markus 1067: compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1,
1.59 markus 1068: SSH_VERSION);
1.45 deraadt 1069: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 1070: fatal("write: %.100s", strerror(errno));
1.59 markus 1071: client_version_string = xstrdup(buf);
1072: chop(client_version_string);
1073: chop(server_version_string);
1074: debug("Local version string %.100s", client_version_string);
1.1 deraadt 1075: }
1076:
1.38 markus 1077: int
1078: read_yes_or_no(const char *prompt, int defval)
1.1 deraadt 1079: {
1.38 markus 1080: char buf[1024];
1081: FILE *f;
1082: int retval = -1;
1083:
1084: if (isatty(0))
1085: f = stdin;
1086: else
1087: f = fopen("/dev/tty", "rw");
1088:
1089: if (f == NULL)
1090: return 0;
1091:
1092: fflush(stdout);
1093:
1094: while (1) {
1095: fprintf(stderr, "%s", prompt);
1096: if (fgets(buf, sizeof(buf), f) == NULL) {
1097: /* Print a newline (the prompt probably didn\'t have one). */
1098: fprintf(stderr, "\n");
1099: strlcpy(buf, "no", sizeof buf);
1100: }
1101: /* Remove newline from response. */
1102: if (strchr(buf, '\n'))
1103: *strchr(buf, '\n') = 0;
1104:
1105: if (buf[0] == 0)
1106: retval = defval;
1107: if (strcmp(buf, "yes") == 0)
1108: retval = 1;
1109: if (strcmp(buf, "no") == 0)
1110: retval = 0;
1111:
1112: if (retval != -1) {
1113: if (f != stdin)
1114: fclose(f);
1115: return retval;
1116: }
1.1 deraadt 1117: }
1118: }
1119:
1.39 deraadt 1120: /*
1.46 markus 1121: * check whether the supplied host key is valid, return only if ok.
1.39 deraadt 1122: */
1.46 markus 1123:
1.38 markus 1124: void
1.58 markus 1125: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1.1 deraadt 1126: {
1.58 markus 1127: Key *file_key;
1.46 markus 1128: char *ip = NULL;
1.38 markus 1129: char hostline[1000], *hostp;
1130: HostStatus host_status;
1131: HostStatus ip_status;
1.49 markus 1132: int local = 0, host_ip_differ = 0;
1133: char ntop[NI_MAXHOST];
1134:
1135: /*
1136: * Force accepting of the host key for loopback/localhost. The
1137: * problem is that if the home directory is NFS-mounted to multiple
1138: * machines, localhost will refer to a different machine in each of
1139: * them, and the user will get bogus HOST_CHANGED warnings. This
1140: * essentially disables host authentication for localhost; however,
1141: * this is probably not a real problem.
1142: */
1143: switch (hostaddr->sa_family) {
1144: case AF_INET:
1145: local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1146: break;
1147: case AF_INET6:
1148: local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1149: break;
1150: default:
1151: local = 0;
1152: break;
1153: }
1154: if (local) {
1155: debug("Forcing accepting of host key for loopback/localhost.");
1156: return;
1157: }
1.42 markus 1158:
1159: /*
1.44 markus 1160: * Turn off check_host_ip for proxy connects, since
1.42 markus 1161: * we don't have the remote ip-address
1162: */
1163: if (options.proxy_command != NULL && options.check_host_ip)
1164: options.check_host_ip = 0;
1.38 markus 1165:
1.49 markus 1166: if (options.check_host_ip) {
1167: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1168: NULL, 0, NI_NUMERICHOST) != 0)
1169: fatal("check_host_key: getnameinfo failed");
1170: ip = xstrdup(ntop);
1171: }
1.38 markus 1172:
1.46 markus 1173: /*
1174: * Store the host key from the known host file in here so that we can
1175: * compare it with the key for the IP address.
1176: */
1.58 markus 1177: file_key = key_new(host_key->type);
1.38 markus 1178:
1.40 markus 1179: /*
1180: * Check if the host key is present in the user\'s list of known
1181: * hosts or in the systemwide list.
1182: */
1.58 markus 1183: host_status = check_host_in_hostfile(options.user_hostfile, host, host_key, file_key);
1.38 markus 1184: if (host_status == HOST_NEW)
1.58 markus 1185: host_status = check_host_in_hostfile(options.system_hostfile, host, host_key, file_key);
1.40 markus 1186: /*
1187: * Also perform check for the ip address, skip the check if we are
1188: * localhost or the hostname was an ip address to begin with
1189: */
1.38 markus 1190: if (options.check_host_ip && !local && strcmp(host, ip)) {
1.58 markus 1191: Key *ip_key = key_new(host_key->type);
1192: ip_status = check_host_in_hostfile(options.user_hostfile, ip, host_key, ip_key);
1.38 markus 1193:
1194: if (ip_status == HOST_NEW)
1.58 markus 1195: ip_status = check_host_in_hostfile(options.system_hostfile, ip, host_key, ip_key);
1.38 markus 1196: if (host_status == HOST_CHANGED &&
1.58 markus 1197: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 1198: host_ip_differ = 1;
1199:
1.58 markus 1200: key_free(ip_key);
1.38 markus 1201: } else
1202: ip_status = host_status;
1203:
1.58 markus 1204: key_free(file_key);
1.38 markus 1205:
1206: switch (host_status) {
1207: case HOST_OK:
1208: /* The host is known and the key matches. */
1209: debug("Host '%.200s' is known and matches the host key.", host);
1210: if (options.check_host_ip) {
1211: if (ip_status == HOST_NEW) {
1.58 markus 1212: if (!add_host_to_hostfile(options.user_hostfile, ip, host_key))
1.38 markus 1213: log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).",
1214: ip, options.user_hostfile);
1215: else
1216: log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.",
1217: ip);
1218: } else if (ip_status != HOST_OK)
1219: log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'",
1220: host, ip);
1221: }
1222: break;
1223: case HOST_NEW:
1224: /* The host is new. */
1225: if (options.strict_host_key_checking == 1) {
1226: /* User has requested strict host key checking. We will not add the host key
1227: automatically. The only alternative left is to abort. */
1228: fatal("No host key is known for %.200s and you have requested strict checking.", host);
1229: } else if (options.strict_host_key_checking == 2) {
1230: /* The default */
1231: char prompt[1024];
1.58 markus 1232: char *fp = key_fingerprint(host_key);
1.38 markus 1233: snprintf(prompt, sizeof(prompt),
1.45 deraadt 1234: "The authenticity of host '%.200s' can't be established.\n"
1.58 markus 1235: "Key fingerprint is %s.\n"
1.45 deraadt 1236: "Are you sure you want to continue connecting (yes/no)? ",
1.58 markus 1237: host, fp);
1.38 markus 1238: if (!read_yes_or_no(prompt, -1))
1239: fatal("Aborted by user!\n");
1240: }
1241: if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) {
1242: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1243: hostp = hostline;
1244: } else
1245: hostp = host;
1246:
1247: /* If not in strict mode, add the key automatically to the local known_hosts file. */
1.58 markus 1248: if (!add_host_to_hostfile(options.user_hostfile, hostp, host_key))
1.38 markus 1249: log("Failed to add the host to the list of known hosts (%.500s).",
1250: options.user_hostfile);
1251: else
1252: log("Warning: Permanently added '%.200s' to the list of known hosts.",
1253: hostp);
1254: break;
1255: case HOST_CHANGED:
1256: if (options.check_host_ip && host_ip_differ) {
1257: char *msg;
1258: if (ip_status == HOST_NEW)
1259: msg = "is unknown";
1260: else if (ip_status == HOST_OK)
1261: msg = "is unchanged";
1262: else
1263: msg = "has a different value";
1264: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1265: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1266: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1267: error("The host key for %s has changed,", host);
1268: error("and the key for the according IP address %s", ip);
1269: error("%s. This could either mean that", msg);
1270: error("DNS SPOOFING is happening or the IP address for the host");
1271: error("and its host key have changed at the same time");
1272: }
1273: /* The host key has changed. */
1274: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 1275: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 1276: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1277: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1278: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1279: error("It is also possible that the host key has just been changed.");
1280: error("Please contact your system administrator.");
1281: error("Add correct host key in %.100s to get rid of this message.",
1282: options.user_hostfile);
1283:
1.40 markus 1284: /*
1285: * If strict host key checking is in use, the user will have
1286: * to edit the key manually and we can only abort.
1287: */
1.38 markus 1288: if (options.strict_host_key_checking)
1289: fatal("Host key for %.200s has changed and you have requested strict checking.", host);
1290:
1.40 markus 1291: /*
1292: * If strict host key checking has not been requested, allow
1293: * the connection but without password authentication or
1294: * agent forwarding.
1295: */
1.38 markus 1296: if (options.password_authentication) {
1297: error("Password authentication is disabled to avoid trojan horses.");
1298: options.password_authentication = 0;
1299: }
1300: if (options.forward_agent) {
1301: error("Agent forwarding is disabled to avoid trojan horses.");
1302: options.forward_agent = 0;
1303: }
1.40 markus 1304: /*
1305: * XXX Should permit the user to change to use the new id.
1306: * This could be done by converting the host key to an
1307: * identifying sentence, tell that the host identifies itself
1308: * by that sentence, and ask the user if he/she whishes to
1309: * accept the authentication.
1310: */
1.38 markus 1311: break;
1312: }
1313: if (options.check_host_ip)
1314: xfree(ip);
1.46 markus 1315: }
1.58 markus 1316: void
1317: check_rsa_host_key(char *host, struct sockaddr *hostaddr, RSA *host_key)
1318: {
1319: Key k;
1320: k.type = KEY_RSA;
1321: k.rsa = host_key;
1322: check_host_key(host, hostaddr, &k);
1323: }
1.46 markus 1324:
1325: /*
1.59 markus 1326: * SSH2 key exchange
1327: */
1328: void
1329: ssh_kex2(char *host, struct sockaddr *hostaddr)
1330: {
1331: Kex *kex;
1332: char *cprop[PROPOSAL_MAX];
1333: char *sprop[PROPOSAL_MAX];
1334: Buffer *client_kexinit;
1335: Buffer *server_kexinit;
1336: int payload_len, dlen;
1337: unsigned int klen, kout;
1338: char *ptr;
1339: char *signature = NULL;
1340: unsigned int slen;
1341: char *server_host_key_blob = NULL;
1342: Key *server_host_key;
1343: unsigned int sbloblen;
1344: DH *dh;
1345: BIGNUM *dh_server_pub = 0;
1346: BIGNUM *shared_secret = 0;
1347: int i;
1348: unsigned char *kbuf;
1349: unsigned char *hash;
1350:
1351: /* KEXINIT */
1352:
1353: debug("Sending KEX init.");
1.64 markus 1354: if (options.ciphers != NULL) {
1355: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1356: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1357: } else if (
1358: options.cipher == SSH_CIPHER_ARCFOUR ||
1.59 markus 1359: options.cipher == SSH_CIPHER_3DES_CBC ||
1360: options.cipher == SSH_CIPHER_CAST128_CBC ||
1361: options.cipher == SSH_CIPHER_BLOWFISH_CBC) {
1.64 markus 1362: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.59 markus 1363: myproposal[PROPOSAL_ENC_ALGS_STOC] = cipher_name(options.cipher);
1364: }
1365: if (options.compression) {
1366: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
1367: myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
1368: } else {
1369: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
1370: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1371: }
1372: for (i = 0; i < PROPOSAL_MAX; i++)
1373: cprop[i] = xstrdup(myproposal[i]);
1374:
1375: client_kexinit = kex_init(cprop);
1376: packet_start(SSH2_MSG_KEXINIT);
1377: packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));
1378: packet_send();
1379: packet_write_wait();
1380:
1381: debug("done");
1382:
1383: packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
1384:
1385: /* save payload for session_id */
1386: server_kexinit = xmalloc(sizeof(*server_kexinit));
1387: buffer_init(server_kexinit);
1388: ptr = packet_get_raw(&payload_len);
1389: buffer_append(server_kexinit, ptr, payload_len);
1390:
1391: /* skip cookie */
1392: for (i = 0; i < 16; i++)
1393: (void) packet_get_char();
1394: /* kex init proposal strings */
1395: for (i = 0; i < PROPOSAL_MAX; i++) {
1396: sprop[i] = packet_get_string(NULL);
1397: debug("got kexinit string: %s", sprop[i]);
1398: }
1399: i = (int) packet_get_char();
1400: debug("first kex follow == %d", i);
1401: i = packet_get_int();
1402: debug("reserved == %d", i);
1.67 ! markus 1403: packet_done();
1.59 markus 1404:
1405: debug("done read kexinit");
1406: kex = kex_choose_conf(cprop, sprop, 0);
1407:
1408: /* KEXDH */
1409:
1410: debug("Sending SSH2_MSG_KEXDH_INIT.");
1411:
1412: /* generate and send 'e', client DH public key */
1.63 markus 1413: dh = dh_new_group1();
1.59 markus 1414: packet_start(SSH2_MSG_KEXDH_INIT);
1415: packet_put_bignum2(dh->pub_key);
1416: packet_send();
1417: packet_write_wait();
1418:
1419: #ifdef DEBUG_KEXDH
1420: fprintf(stderr, "\np= ");
1421: bignum_print(dh->p);
1422: fprintf(stderr, "\ng= ");
1423: bignum_print(dh->g);
1424: fprintf(stderr, "\npub= ");
1425: bignum_print(dh->pub_key);
1426: fprintf(stderr, "\n");
1427: DHparams_print_fp(stderr, dh);
1428: #endif
1429:
1430: debug("Wait SSH2_MSG_KEXDH_REPLY.");
1431:
1432: packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);
1433:
1434: debug("Got SSH2_MSG_KEXDH_REPLY.");
1435:
1436: /* key, cert */
1437: server_host_key_blob = packet_get_string(&sbloblen);
1438: server_host_key = dsa_serverkey_from_blob(server_host_key_blob, sbloblen);
1439: if (server_host_key == NULL)
1440: fatal("cannot decode server_host_key_blob");
1441:
1442: check_host_key(host, hostaddr, server_host_key);
1443:
1444: /* DH paramter f, server public DH key */
1445: dh_server_pub = BN_new();
1446: if (dh_server_pub == NULL)
1447: fatal("dh_server_pub == NULL");
1448: packet_get_bignum2(dh_server_pub, &dlen);
1449:
1450: #ifdef DEBUG_KEXDH
1451: fprintf(stderr, "\ndh_server_pub= ");
1452: bignum_print(dh_server_pub);
1453: fprintf(stderr, "\n");
1454: debug("bits %d", BN_num_bits(dh_server_pub));
1455: #endif
1456:
1457: /* signed H */
1458: signature = packet_get_string(&slen);
1.67 ! markus 1459: packet_done();
1.63 markus 1460:
1461: if (!dh_pub_is_valid(dh, dh_server_pub))
1462: packet_disconnect("bad server public DH value");
1.59 markus 1463:
1464: klen = DH_size(dh);
1465: kbuf = xmalloc(klen);
1466: kout = DH_compute_key(kbuf, dh_server_pub, dh);
1467: #ifdef DEBUG_KEXDH
1468: debug("shared secret: len %d/%d", klen, kout);
1469: fprintf(stderr, "shared secret == ");
1470: for (i = 0; i< kout; i++)
1471: fprintf(stderr, "%02x", (kbuf[i])&0xff);
1472: fprintf(stderr, "\n");
1473: #endif
1474: shared_secret = BN_new();
1475:
1476: BN_bin2bn(kbuf, kout, shared_secret);
1477: memset(kbuf, 0, klen);
1478: xfree(kbuf);
1479:
1480: /* calc and verify H */
1481: hash = kex_hash(
1482: client_version_string,
1483: server_version_string,
1484: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1485: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1486: server_host_key_blob, sbloblen,
1487: dh->pub_key,
1488: dh_server_pub,
1489: shared_secret
1490: );
1.60 markus 1491: buffer_free(client_kexinit);
1492: buffer_free(server_kexinit);
1.59 markus 1493: xfree(client_kexinit);
1494: xfree(server_kexinit);
1495: #ifdef DEBUG_KEXDH
1496: fprintf(stderr, "hash == ");
1497: for (i = 0; i< 20; i++)
1498: fprintf(stderr, "%02x", (hash[i])&0xff);
1499: fprintf(stderr, "\n");
1500: #endif
1501: dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20);
1502: key_free(server_host_key);
1503:
1504: kex_derive_keys(kex, hash, shared_secret);
1505: packet_set_kex(kex);
1506:
1507: /* have keys, free DH */
1508: DH_free(dh);
1509:
1510: debug("Wait SSH2_MSG_NEWKEYS.");
1511: packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1.67 ! markus 1512: packet_done();
1.59 markus 1513: debug("GOT SSH2_MSG_NEWKEYS.");
1514:
1515: debug("send SSH2_MSG_NEWKEYS.");
1516: packet_start(SSH2_MSG_NEWKEYS);
1517: packet_send();
1518: packet_write_wait();
1519: debug("done: send SSH2_MSG_NEWKEYS.");
1520:
1.62 markus 1521: #ifdef DEBUG_KEXDH
1.59 markus 1522: /* send 1st encrypted/maced/compressed message */
1523: packet_start(SSH2_MSG_IGNORE);
1524: packet_put_cstring("markus");
1525: packet_send();
1526: packet_write_wait();
1.62 markus 1527: #endif
1.59 markus 1528: debug("done: KEX2.");
1529: }
1530: /*
1531: * Authenticate user
1532: */
1533: void
1534: ssh_userauth2(int host_key_valid, RSA *own_host_key,
1535: uid_t original_real_uid, char *host)
1536: {
1537: int type;
1538: int plen;
1539: unsigned int dlen;
1540: int partial;
1541: struct passwd *pw;
1.62 markus 1542: char prompt[80];
1.59 markus 1543: char *server_user, *local_user;
1544: char *auths;
1545: char *password;
1.67 ! markus 1546: char *service = "ssh-connection"; /* service name */
1.59 markus 1547:
1548: debug("send SSH2_MSG_SERVICE_REQUEST");
1549: packet_start(SSH2_MSG_SERVICE_REQUEST);
1550: packet_put_cstring("ssh-userauth");
1551: packet_send();
1552: packet_write_wait();
1553:
1554: type = packet_read(&plen);
1555: if (type != SSH2_MSG_SERVICE_ACCEPT) {
1556: fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
1557: }
1.67 ! markus 1558: if (packet_remaining() > 0) {
! 1559: char *reply = packet_get_string(&plen);
! 1560: debug("service_accept: %s", reply);
! 1561: xfree(reply);
! 1562: } else {
! 1563: /* payload empty for ssh-2.0.13 ?? */
! 1564: log("buggy server: service_accept w/o service");
! 1565: }
! 1566: packet_done();
1.59 markus 1567: debug("got SSH2_MSG_SERVICE_ACCEPT");
1568:
1569: /*XX COMMONCODE: */
1570: /* Get local user name. Use it as server user if no user name was given. */
1571: pw = getpwuid(original_real_uid);
1572: if (!pw)
1573: fatal("User id %d not found from user database.", original_real_uid);
1574: local_user = xstrdup(pw->pw_name);
1575: server_user = options.user ? options.user : local_user;
1576:
1577: /* INITIAL request for auth */
1578: packet_start(SSH2_MSG_USERAUTH_REQUEST);
1579: packet_put_cstring(server_user);
1580: packet_put_cstring(service);
1581: packet_put_cstring("none");
1582: packet_send();
1583: packet_write_wait();
1584:
1585: for (;;) {
1586: type = packet_read(&plen);
1587: if (type == SSH2_MSG_USERAUTH_SUCCESS)
1588: break;
1589: if (type != SSH2_MSG_USERAUTH_FAILURE)
1590: fatal("access denied: %d", type);
1591: /* SSH2_MSG_USERAUTH_FAILURE means: try again */
1592: auths = packet_get_string(&dlen);
1593: debug("authentications that can continue: %s", auths);
1594: partial = packet_get_char();
1.67 ! markus 1595: packet_done();
1.59 markus 1596: if (partial)
1597: debug("partial success");
1598: if (strstr(auths, "password") == NULL)
1599: fatal("passwd auth not supported: %s", auths);
1600: xfree(auths);
1601: /* try passwd */
1.62 markus 1602: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1603: server_user, host);
1604: password = read_passphrase(prompt, 0);
1.59 markus 1605: packet_start(SSH2_MSG_USERAUTH_REQUEST);
1606: packet_put_cstring(server_user);
1607: packet_put_cstring(service);
1608: packet_put_cstring("password");
1609: packet_put_char(0);
1610: packet_put_cstring(password);
1611: memset(password, 0, strlen(password));
1612: xfree(password);
1613: packet_send();
1614: packet_write_wait();
1615: }
1.67 ! markus 1616: packet_done();
1.59 markus 1617: debug("ssh-userauth2 successfull");
1618: }
1619:
1620: /*
1.51 markus 1621: * SSH1 key exchange
1.46 markus 1622: */
1623: void
1.51 markus 1624: ssh_kex(char *host, struct sockaddr *hostaddr)
1.46 markus 1625: {
1.51 markus 1626: int i;
1.46 markus 1627: BIGNUM *key;
1628: RSA *host_key;
1629: RSA *public_key;
1630: int bits, rbits;
1.59 markus 1631: int ssh_cipher_default = SSH_CIPHER_3DES;
1.46 markus 1632: unsigned char session_key[SSH_SESSION_KEY_LENGTH];
1.51 markus 1633: unsigned char cookie[8];
1634: unsigned int supported_ciphers;
1.46 markus 1635: unsigned int server_flags, client_flags;
1636: int payload_len, clen, sum_len = 0;
1637: u_int32_t rand = 0;
1638:
1639: debug("Waiting for server public key.");
1640:
1641: /* Wait for a public key packet from the server. */
1642: packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
1643:
1.51 markus 1644: /* Get cookie from the packet. */
1.46 markus 1645: for (i = 0; i < 8; i++)
1.51 markus 1646: cookie[i] = packet_get_char();
1.46 markus 1647:
1648: /* Get the public key. */
1649: public_key = RSA_new();
1650: bits = packet_get_int();/* bits */
1651: public_key->e = BN_new();
1652: packet_get_bignum(public_key->e, &clen);
1653: sum_len += clen;
1654: public_key->n = BN_new();
1655: packet_get_bignum(public_key->n, &clen);
1656: sum_len += clen;
1657:
1658: rbits = BN_num_bits(public_key->n);
1659: if (bits != rbits) {
1660: log("Warning: Server lies about size of server public key: "
1661: "actual size is %d bits vs. announced %d.", rbits, bits);
1662: log("Warning: This may be due to an old implementation of ssh.");
1663: }
1664: /* Get the host key. */
1665: host_key = RSA_new();
1666: bits = packet_get_int();/* bits */
1667: host_key->e = BN_new();
1668: packet_get_bignum(host_key->e, &clen);
1669: sum_len += clen;
1670: host_key->n = BN_new();
1671: packet_get_bignum(host_key->n, &clen);
1672: sum_len += clen;
1673:
1674: rbits = BN_num_bits(host_key->n);
1675: if (bits != rbits) {
1676: log("Warning: Server lies about size of server host key: "
1677: "actual size is %d bits vs. announced %d.", rbits, bits);
1678: log("Warning: This may be due to an old implementation of ssh.");
1679: }
1680:
1681: /* Get protocol flags. */
1682: server_flags = packet_get_int();
1683: packet_set_protocol_flags(server_flags);
1684:
1685: supported_ciphers = packet_get_int();
1686: supported_authentications = packet_get_int();
1687:
1688: debug("Received server public key (%d bits) and host key (%d bits).",
1689: BN_num_bits(public_key->n), BN_num_bits(host_key->n));
1690:
1691: packet_integrity_check(payload_len,
1692: 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
1693: SSH_SMSG_PUBLIC_KEY);
1694:
1.58 markus 1695: check_rsa_host_key(host, hostaddr, host_key);
1.46 markus 1696:
1697: client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN;
1698:
1.51 markus 1699: compute_session_id(session_id, cookie, host_key->n, public_key->n);
1.38 markus 1700:
1701: /* Generate a session key. */
1702: arc4random_stir();
1703:
1.40 markus 1704: /*
1705: * Generate an encryption key for the session. The key is a 256 bit
1706: * random number, interpreted as a 32-byte key, with the least
1707: * significant 8 bits being the first byte of the key.
1708: */
1.38 markus 1709: for (i = 0; i < 32; i++) {
1710: if (i % 4 == 0)
1711: rand = arc4random();
1712: session_key[i] = rand & 0xff;
1713: rand >>= 8;
1714: }
1715:
1.40 markus 1716: /*
1717: * According to the protocol spec, the first byte of the session key
1718: * is the highest byte of the integer. The session key is xored with
1719: * the first 16 bytes of the session id.
1720: */
1.38 markus 1721: key = BN_new();
1722: BN_set_word(key, 0);
1723: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
1724: BN_lshift(key, key, 8);
1725: if (i < 16)
1726: BN_add_word(key, session_key[i] ^ session_id[i]);
1727: else
1728: BN_add_word(key, session_key[i]);
1729: }
1730:
1.40 markus 1731: /*
1732: * Encrypt the integer using the public key and host key of the
1733: * server (key with smaller modulus first).
1734: */
1.38 markus 1735: if (BN_cmp(public_key->n, host_key->n) < 0) {
1736: /* Public key has smaller modulus. */
1737: if (BN_num_bits(host_key->n) <
1738: BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) {
1739: fatal("respond_to_rsa_challenge: host_key %d < public_key %d + "
1740: "SSH_KEY_BITS_RESERVED %d",
1741: BN_num_bits(host_key->n),
1742: BN_num_bits(public_key->n),
1743: SSH_KEY_BITS_RESERVED);
1744: }
1745: rsa_public_encrypt(key, key, public_key);
1746: rsa_public_encrypt(key, key, host_key);
1747: } else {
1748: /* Host key has smaller modulus (or they are equal). */
1749: if (BN_num_bits(public_key->n) <
1750: BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) {
1751: fatal("respond_to_rsa_challenge: public_key %d < host_key %d + "
1752: "SSH_KEY_BITS_RESERVED %d",
1753: BN_num_bits(public_key->n),
1754: BN_num_bits(host_key->n),
1755: SSH_KEY_BITS_RESERVED);
1756: }
1757: rsa_public_encrypt(key, key, host_key);
1758: rsa_public_encrypt(key, key, public_key);
1759: }
1760:
1.52 markus 1761: /* Destroy the public keys since we no longer need them. */
1762: RSA_free(public_key);
1763: RSA_free(host_key);
1764:
1.38 markus 1765: if (options.cipher == SSH_CIPHER_NOT_SET) {
1.61 markus 1766: if (cipher_mask1() & supported_ciphers & (1 << ssh_cipher_default))
1.38 markus 1767: options.cipher = ssh_cipher_default;
1768: else {
1769: debug("Cipher %s not supported, using %.100s instead.",
1770: cipher_name(ssh_cipher_default),
1771: cipher_name(SSH_FALLBACK_CIPHER));
1772: options.cipher = SSH_FALLBACK_CIPHER;
1773: }
1774: }
1775: /* Check that the selected cipher is supported. */
1776: if (!(supported_ciphers & (1 << options.cipher)))
1777: fatal("Selected cipher type %.100s not supported by server.",
1778: cipher_name(options.cipher));
1779:
1780: debug("Encryption type: %.100s", cipher_name(options.cipher));
1781:
1782: /* Send the encrypted session key to the server. */
1783: packet_start(SSH_CMSG_SESSION_KEY);
1784: packet_put_char(options.cipher);
1785:
1.51 markus 1786: /* Send the cookie back to the server. */
1.38 markus 1787: for (i = 0; i < 8; i++)
1.51 markus 1788: packet_put_char(cookie[i]);
1.38 markus 1789:
1.52 markus 1790: /* Send and destroy the encrypted encryption key integer. */
1.38 markus 1791: packet_put_bignum(key);
1.52 markus 1792: BN_clear_free(key);
1.38 markus 1793:
1794: /* Send protocol flags. */
1.46 markus 1795: packet_put_int(client_flags);
1.38 markus 1796:
1797: /* Send the packet now. */
1798: packet_send();
1799: packet_write_wait();
1800:
1801: debug("Sent encrypted session key.");
1802:
1803: /* Set the encryption key. */
1804: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher);
1805:
1806: /* We will no longer need the session key here. Destroy any extra copies. */
1807: memset(session_key, 0, sizeof(session_key));
1808:
1.40 markus 1809: /*
1810: * Expect a success message from the server. Note that this message
1811: * will be received in encrypted form.
1812: */
1.38 markus 1813: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1814:
1815: debug("Received encrypted confirmation.");
1.51 markus 1816: }
1817:
1818: /*
1819: * Authenticate user
1820: */
1821: void
1822: ssh_userauth(int host_key_valid, RSA *own_host_key,
1823: uid_t original_real_uid, char *host)
1824: {
1825: int i, type;
1826: int payload_len;
1827: struct passwd *pw;
1828: const char *server_user, *local_user;
1829:
1830: /* Get local user name. Use it as server user if no user name was given. */
1831: pw = getpwuid(original_real_uid);
1832: if (!pw)
1833: fatal("User id %d not found from user database.", original_real_uid);
1834: local_user = xstrdup(pw->pw_name);
1835: server_user = options.user ? options.user : local_user;
1.38 markus 1836:
1837: /* Send the name of the user to log in as on the server. */
1838: packet_start(SSH_CMSG_USER);
1839: packet_put_string(server_user, strlen(server_user));
1.16 dugsong 1840: packet_send();
1841: packet_write_wait();
1.38 markus 1842:
1.40 markus 1843: /*
1844: * The server should respond with success if no authentication is
1845: * needed (the user has no password). Otherwise the server responds
1846: * with failure.
1847: */
1.16 dugsong 1848: type = packet_read(&payload_len);
1.38 markus 1849:
1850: /* check whether the connection was accepted without authentication. */
1.16 dugsong 1851: if (type == SSH_SMSG_SUCCESS)
1.38 markus 1852: return;
1.16 dugsong 1853: if (type != SSH_SMSG_FAILURE)
1.38 markus 1854: packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
1855: type);
1856:
1857: #ifdef AFS
1858: /* Try Kerberos tgt passing if the server supports it. */
1859: if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
1860: options.kerberos_tgt_passing) {
1861: if (options.cipher == SSH_CIPHER_NONE)
1862: log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
1863: (void) send_kerberos_tgt();
1864: }
1865: /* Try AFS token passing if the server supports it. */
1866: if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
1867: options.afs_token_passing && k_hasafs()) {
1868: if (options.cipher == SSH_CIPHER_NONE)
1869: log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
1870: send_afs_tokens();
1871: }
1872: #endif /* AFS */
1873:
1874: #ifdef KRB4
1875: if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
1876: options.kerberos_authentication) {
1877: debug("Trying Kerberos authentication.");
1878: if (try_kerberos_authentication()) {
1879: /* The server should respond with success or failure. */
1880: type = packet_read(&payload_len);
1881: if (type == SSH_SMSG_SUCCESS)
1882: return;
1883: if (type != SSH_SMSG_FAILURE)
1884: packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
1885: }
1886: }
1887: #endif /* KRB4 */
1888:
1.40 markus 1889: /*
1890: * Use rhosts authentication if running in privileged socket and we
1891: * do not wish to remain anonymous.
1892: */
1.38 markus 1893: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
1894: options.rhosts_authentication) {
1895: debug("Trying rhosts authentication.");
1896: packet_start(SSH_CMSG_AUTH_RHOSTS);
1897: packet_put_string(local_user, strlen(local_user));
1898: packet_send();
1899: packet_write_wait();
1900:
1901: /* The server should respond with success or failure. */
1902: type = packet_read(&payload_len);
1903: if (type == SSH_SMSG_SUCCESS)
1904: return;
1905: if (type != SSH_SMSG_FAILURE)
1906: packet_disconnect("Protocol error: got %d in response to rhosts auth",
1907: type);
1908: }
1.40 markus 1909: /*
1910: * Try .rhosts or /etc/hosts.equiv authentication with RSA host
1911: * authentication.
1912: */
1.38 markus 1913: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
1914: options.rhosts_rsa_authentication && host_key_valid) {
1915: if (try_rhosts_rsa_authentication(local_user, own_host_key))
1916: return;
1917: }
1918: /* Try RSA authentication if the server supports it. */
1919: if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
1920: options.rsa_authentication) {
1.40 markus 1921: /*
1922: * Try RSA authentication using the authentication agent. The
1923: * agent is tried first because no passphrase is needed for
1924: * it, whereas identity files may require passphrases.
1925: */
1.38 markus 1926: if (try_agent_authentication())
1927: return;
1928:
1929: /* Try RSA authentication for each identity. */
1930: for (i = 0; i < options.num_identity_files; i++)
1.43 markus 1931: if (try_rsa_authentication(options.identity_files[i]))
1.38 markus 1932: return;
1933: }
1934: /* Try skey authentication if the server supports it. */
1935: if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
1936: options.skey_authentication && !options.batch_mode) {
1.43 markus 1937: if (try_skey_authentication())
1938: return;
1.38 markus 1939: }
1940: /* Try password authentication if the server supports it. */
1941: if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
1942: options.password_authentication && !options.batch_mode) {
1943: char prompt[80];
1.45 deraadt 1944:
1.43 markus 1945: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1.45 deraadt 1946: server_user, host);
1.43 markus 1947: if (try_password_authentication(prompt))
1948: return;
1.38 markus 1949: }
1950: /* All authentication methods have failed. Exit with an error message. */
1951: fatal("Permission denied.");
1952: /* NOTREACHED */
1.51 markus 1953: }
1954: /*
1955: * Starts a dialog with the server, and authenticates the current user on the
1956: * server. This does not need any extra privileges. The basic connection
1957: * to the server must already have been established before this is called.
1958: * If login fails, this function prints an error and never returns.
1959: * This function does not require super-user privileges.
1960: */
1961: void
1962: ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
1963: struct sockaddr *hostaddr, uid_t original_real_uid)
1964: {
1965: char *host, *cp;
1966:
1967: /* Convert the user-supplied hostname into all lowercase. */
1968: host = xstrdup(orighost);
1969: for (cp = host; *cp; cp++)
1970: if (isupper(*cp))
1971: *cp = tolower(*cp);
1972:
1973: /* Exchange protocol version identification strings with the server. */
1974: ssh_exchange_identification();
1975:
1976: /* Put the connection into non-blocking mode. */
1977: packet_set_nonblocking();
1978:
1979: /* key exchange */
1980: /* authenticate user */
1.59 markus 1981: if (compat20) {
1982: ssh_kex2(host, hostaddr);
1983: ssh_userauth2(host_key_valid, own_host_key, original_real_uid, host);
1984: } else {
1985: supported_authentications = 0;
1986: ssh_kex(host, hostaddr);
1987: if (supported_authentications == 0)
1988: fatal("supported_authentications == 0.");
1989: ssh_userauth(host_key_valid, own_host_key, original_real_uid, host);
1990: }
1.1 deraadt 1991: }
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