Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.70
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.
8: */
1.1 deraadt 9:
10: #include "includes.h"
1.70 ! markus 11: RCSID("$OpenBSD: sshconnect.c,v 1.28 2000/04/18 15:01:33 markus Exp $");
1.1 deraadt 12:
1.66 markus 13: #include <openssl/bn.h>
1.1 deraadt 14: #include "xmalloc.h"
15: #include "rsa.h"
16: #include "ssh.h"
1.59 markus 17: #include "buffer.h"
1.1 deraadt 18: #include "packet.h"
19: #include "authfd.h"
20: #include "cipher.h"
21: #include "mpaux.h"
22: #include "uidswap.h"
1.21 markus 23: #include "compat.h"
1.27 markus 24: #include "readconf.h"
1.1 deraadt 25:
1.59 markus 26: #include "bufaux.h"
1.66 markus 27: #include <openssl/rsa.h>
28: #include <openssl/dsa.h>
1.59 markus 29:
30: #include "ssh2.h"
1.66 markus 31: #include <openssl/md5.h>
32: #include <openssl/dh.h>
33: #include <openssl/hmac.h>
1.59 markus 34: #include "kex.h"
35: #include "myproposal.h"
1.58 markus 36: #include "key.h"
1.59 markus 37: #include "dsa.h"
1.58 markus 38: #include "hostfile.h"
1.70 ! markus 39: #include "authfile.h"
1.10 deraadt 40:
1.1 deraadt 41: /* Session id for the current session. */
42: unsigned char session_id[16];
1.70 ! markus 43: unsigned int supported_authentications = 0;
1.1 deraadt 44:
1.70 ! markus 45: unsigned char *session_id2 = NULL;
! 46: int session_id2_len = 0;
1.51 markus 47:
1.70 ! markus 48: char *client_version_string = NULL;
! 49: char *server_version_string = NULL;
1.59 markus 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];
1.69 deraadt 65: pid_t 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
1.68 markus 246: sequence until the connection succeeds. */
1.49 markus 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. */
1.68 markus 260: sock = ssh_create_socket(original_real_uid,
1.49 markus 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:
1.70 ! markus 319:
1.39 deraadt 320: /*
321: * Checks if the user has an authentication agent, and if so, tries to
322: * authenticate using the agent.
323: */
1.3 provos 324: int
325: try_agent_authentication()
1.1 deraadt 326: {
1.38 markus 327: int status, type;
328: char *comment;
329: AuthenticationConnection *auth;
330: unsigned char response[16];
331: unsigned int i;
332: BIGNUM *e, *n, *challenge;
333:
334: /* Get connection to the agent. */
335: auth = ssh_get_authentication_connection();
336: if (!auth)
337: return 0;
338:
339: e = BN_new();
340: n = BN_new();
341: challenge = BN_new();
342:
343: /* Loop through identities served by the agent. */
344: for (status = ssh_get_first_identity(auth, e, n, &comment);
345: status;
346: status = ssh_get_next_identity(auth, e, n, &comment)) {
347: int plen, clen;
348:
349: /* Try this identity. */
350: debug("Trying RSA authentication via agent with '%.100s'", comment);
351: xfree(comment);
352:
353: /* Tell the server that we are willing to authenticate using this key. */
354: packet_start(SSH_CMSG_AUTH_RSA);
355: packet_put_bignum(n);
356: packet_send();
357: packet_write_wait();
358:
359: /* Wait for server's response. */
360: type = packet_read(&plen);
361:
362: /* The server sends failure if it doesn\'t like our key or
363: does not support RSA authentication. */
364: if (type == SSH_SMSG_FAILURE) {
365: debug("Server refused our key.");
366: continue;
367: }
368: /* Otherwise it should have sent a challenge. */
369: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
370: packet_disconnect("Protocol error during RSA authentication: %d",
371: type);
372:
373: packet_get_bignum(challenge, &clen);
374:
375: packet_integrity_check(plen, clen, type);
376:
377: debug("Received RSA challenge from server.");
378:
379: /* Ask the agent to decrypt the challenge. */
380: if (!ssh_decrypt_challenge(auth, e, n, challenge,
381: session_id, 1, response)) {
382: /* The agent failed to authenticate this identifier although it
383: advertised it supports this. Just return a wrong value. */
384: log("Authentication agent failed to decrypt challenge.");
385: memset(response, 0, sizeof(response));
386: }
387: debug("Sending response to RSA challenge.");
1.1 deraadt 388:
1.38 markus 389: /* Send the decrypted challenge back to the server. */
390: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
391: for (i = 0; i < 16; i++)
392: packet_put_char(response[i]);
393: packet_send();
394: packet_write_wait();
395:
396: /* Wait for response from the server. */
397: type = packet_read(&plen);
398:
399: /* The server returns success if it accepted the authentication. */
400: if (type == SSH_SMSG_SUCCESS) {
401: debug("RSA authentication accepted by server.");
402: BN_clear_free(e);
403: BN_clear_free(n);
404: BN_clear_free(challenge);
405: return 1;
406: }
407: /* Otherwise it should return failure. */
408: if (type != SSH_SMSG_FAILURE)
409: packet_disconnect("Protocol error waiting RSA auth response: %d",
410: type);
411: }
412:
413: BN_clear_free(e);
414: BN_clear_free(n);
415: BN_clear_free(challenge);
416:
417: debug("RSA authentication using agent refused.");
418: return 0;
1.1 deraadt 419: }
420:
1.39 deraadt 421: /*
422: * Computes the proper response to a RSA challenge, and sends the response to
423: * the server.
424: */
1.3 provos 425: void
1.38 markus 426: respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv)
1.1 deraadt 427: {
1.38 markus 428: unsigned char buf[32], response[16];
429: MD5_CTX md;
430: int i, len;
431:
432: /* Decrypt the challenge using the private key. */
433: rsa_private_decrypt(challenge, challenge, prv);
434:
435: /* Compute the response. */
436: /* The response is MD5 of decrypted challenge plus session id. */
437: len = BN_num_bytes(challenge);
438: if (len <= 0 || len > sizeof(buf))
439: packet_disconnect("respond_to_rsa_challenge: bad challenge length %d",
440: len);
441:
442: memset(buf, 0, sizeof(buf));
443: BN_bn2bin(challenge, buf + sizeof(buf) - len);
444: MD5_Init(&md);
445: MD5_Update(&md, buf, 32);
446: MD5_Update(&md, session_id, 16);
447: MD5_Final(response, &md);
448:
449: debug("Sending response to host key RSA challenge.");
450:
451: /* Send the response back to the server. */
452: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
453: for (i = 0; i < 16; i++)
454: packet_put_char(response[i]);
455: packet_send();
456: packet_write_wait();
457:
458: memset(buf, 0, sizeof(buf));
459: memset(response, 0, sizeof(response));
460: memset(&md, 0, sizeof(md));
1.1 deraadt 461: }
462:
1.39 deraadt 463: /*
464: * Checks if the user has authentication file, and if so, tries to authenticate
465: * the user using it.
466: */
1.3 provos 467: int
1.43 markus 468: try_rsa_authentication(const char *authfile)
1.1 deraadt 469: {
1.38 markus 470: BIGNUM *challenge;
1.70 ! markus 471: Key *public;
! 472: Key *private;
1.38 markus 473: char *passphrase, *comment;
474: int type, i;
475: int plen, clen;
476:
477: /* Try to load identification for the authentication key. */
1.70 ! markus 478: public = key_new(KEY_RSA);
! 479: if (!load_public_key(authfile, public, &comment)) {
! 480: key_free(public);
1.43 markus 481: /* Could not load it. Fail. */
482: return 0;
1.38 markus 483: }
484: debug("Trying RSA authentication with key '%.100s'", comment);
485:
486: /* Tell the server that we are willing to authenticate using this key. */
487: packet_start(SSH_CMSG_AUTH_RSA);
1.70 ! markus 488: packet_put_bignum(public->rsa->n);
1.38 markus 489: packet_send();
490: packet_write_wait();
491:
492: /* We no longer need the public key. */
1.70 ! markus 493: key_free(public);
1.38 markus 494:
495: /* Wait for server's response. */
496: type = packet_read(&plen);
497:
1.40 markus 498: /*
499: * The server responds with failure if it doesn\'t like our key or
500: * doesn\'t support RSA authentication.
501: */
1.38 markus 502: if (type == SSH_SMSG_FAILURE) {
503: debug("Server refused our key.");
504: xfree(comment);
1.43 markus 505: return 0;
1.38 markus 506: }
507: /* Otherwise, the server should respond with a challenge. */
508: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
509: packet_disconnect("Protocol error during RSA authentication: %d", type);
510:
511: /* Get the challenge from the packet. */
512: challenge = BN_new();
513: packet_get_bignum(challenge, &clen);
514:
515: packet_integrity_check(plen, clen, type);
516:
517: debug("Received RSA challenge from server.");
518:
1.70 ! markus 519: private = key_new(KEY_RSA);
1.40 markus 520: /*
521: * Load the private key. Try first with empty passphrase; if it
522: * fails, ask for a passphrase.
523: */
1.70 ! markus 524: if (!load_private_key(authfile, "", private, NULL)) {
1.38 markus 525: char buf[300];
526: snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ",
1.45 deraadt 527: comment);
1.38 markus 528: if (!options.batch_mode)
529: passphrase = read_passphrase(buf, 0);
530: else {
531: debug("Will not query passphrase for %.100s in batch mode.",
532: comment);
533: passphrase = xstrdup("");
534: }
535:
536: /* Load the authentication file using the pasphrase. */
1.70 ! markus 537: if (!load_private_key(authfile, passphrase, private, NULL)) {
1.38 markus 538: memset(passphrase, 0, strlen(passphrase));
539: xfree(passphrase);
540: error("Bad passphrase.");
541:
542: /* Send a dummy response packet to avoid protocol error. */
543: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
544: for (i = 0; i < 16; i++)
545: packet_put_char(0);
546: packet_send();
547: packet_write_wait();
548:
549: /* Expect the server to reject it... */
550: packet_read_expect(&plen, SSH_SMSG_FAILURE);
551: xfree(comment);
552: return 0;
553: }
554: /* Destroy the passphrase. */
555: memset(passphrase, 0, strlen(passphrase));
556: xfree(passphrase);
557: }
558: /* We no longer need the comment. */
559: xfree(comment);
560:
561: /* Compute and send a response to the challenge. */
1.70 ! markus 562: respond_to_rsa_challenge(challenge, private->rsa);
1.38 markus 563:
564: /* Destroy the private key. */
1.70 ! markus 565: key_free(private);
1.38 markus 566:
567: /* We no longer need the challenge. */
568: BN_clear_free(challenge);
569:
570: /* Wait for response from the server. */
571: type = packet_read(&plen);
572: if (type == SSH_SMSG_SUCCESS) {
573: debug("RSA authentication accepted by server.");
574: return 1;
575: }
576: if (type != SSH_SMSG_FAILURE)
577: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
578: debug("RSA authentication refused.");
579: return 0;
1.1 deraadt 580: }
581:
1.39 deraadt 582: /*
583: * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
584: * authentication and RSA host authentication.
585: */
1.3 provos 586: int
1.38 markus 587: try_rhosts_rsa_authentication(const char *local_user, RSA * host_key)
1.1 deraadt 588: {
1.38 markus 589: int type;
590: BIGNUM *challenge;
591: int plen, clen;
592:
593: debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
594:
595: /* Tell the server that we are willing to authenticate using this key. */
596: packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
597: packet_put_string(local_user, strlen(local_user));
598: packet_put_int(BN_num_bits(host_key->n));
599: packet_put_bignum(host_key->e);
600: packet_put_bignum(host_key->n);
601: packet_send();
602: packet_write_wait();
603:
604: /* Wait for server's response. */
605: type = packet_read(&plen);
606:
607: /* The server responds with failure if it doesn't admit our
608: .rhosts authentication or doesn't know our host key. */
609: if (type == SSH_SMSG_FAILURE) {
610: debug("Server refused our rhosts authentication or host key.");
611: return 0;
612: }
613: /* Otherwise, the server should respond with a challenge. */
614: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
615: packet_disconnect("Protocol error during RSA authentication: %d", type);
616:
617: /* Get the challenge from the packet. */
618: challenge = BN_new();
619: packet_get_bignum(challenge, &clen);
620:
621: packet_integrity_check(plen, clen, type);
622:
623: debug("Received RSA challenge for host key from server.");
624:
625: /* Compute a response to the challenge. */
626: respond_to_rsa_challenge(challenge, host_key);
627:
628: /* We no longer need the challenge. */
629: BN_clear_free(challenge);
630:
631: /* Wait for response from the server. */
632: type = packet_read(&plen);
633: if (type == SSH_SMSG_SUCCESS) {
634: debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
635: return 1;
636: }
637: if (type != SSH_SMSG_FAILURE)
638: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
639: debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
640: return 0;
1.1 deraadt 641: }
642:
643: #ifdef KRB4
1.38 markus 644: int
645: try_kerberos_authentication()
1.1 deraadt 646: {
1.38 markus 647: KTEXT_ST auth; /* Kerberos data */
648: char *reply;
649: char inst[INST_SZ];
650: char *realm;
651: CREDENTIALS cred;
652: int r, type, plen;
1.57 markus 653: socklen_t slen;
1.38 markus 654: Key_schedule schedule;
655: u_long checksum, cksum;
656: MSG_DAT msg_data;
657: struct sockaddr_in local, foreign;
658: struct stat st;
659:
660: /* Don't do anything if we don't have any tickets. */
661: if (stat(tkt_string(), &st) < 0)
662: return 0;
663:
664: strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
665:
666: realm = (char *) krb_realmofhost(get_canonical_hostname());
667: if (!realm) {
668: debug("Kerberos V4: no realm for %s", get_canonical_hostname());
669: return 0;
670: }
671: /* This can really be anything. */
672: checksum = (u_long) getpid();
673:
674: r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
675: if (r != KSUCCESS) {
676: debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]);
677: return 0;
678: }
679: /* Get session key to decrypt the server's reply with. */
680: r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
681: if (r != KSUCCESS) {
682: debug("get_cred failed: %s", krb_err_txt[r]);
683: return 0;
684: }
685: des_key_sched((des_cblock *) cred.session, schedule);
686:
687: /* Send authentication info to server. */
688: packet_start(SSH_CMSG_AUTH_KERBEROS);
689: packet_put_string((char *) auth.dat, auth.length);
690: packet_send();
691: packet_write_wait();
692:
693: /* Zero the buffer. */
694: (void) memset(auth.dat, 0, MAX_KTXT_LEN);
695:
1.57 markus 696: slen = sizeof(local);
1.38 markus 697: memset(&local, 0, sizeof(local));
698: if (getsockname(packet_get_connection_in(),
1.57 markus 699: (struct sockaddr *) & local, &slen) < 0)
1.38 markus 700: debug("getsockname failed: %s", strerror(errno));
701:
1.57 markus 702: slen = sizeof(foreign);
1.38 markus 703: memset(&foreign, 0, sizeof(foreign));
704: if (getpeername(packet_get_connection_in(),
1.57 markus 705: (struct sockaddr *) & foreign, &slen) < 0) {
1.38 markus 706: debug("getpeername failed: %s", strerror(errno));
707: fatal_cleanup();
708: }
709: /* Get server reply. */
710: type = packet_read(&plen);
711: switch (type) {
712: case SSH_SMSG_FAILURE:
713: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
714: debug("Kerberos V4 authentication failed.");
715: return 0;
716: break;
717:
718: case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
719: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
720: debug("Kerberos V4 authentication accepted.");
721:
722: /* Get server's response. */
723: reply = packet_get_string((unsigned int *) &auth.length);
724: memcpy(auth.dat, reply, auth.length);
725: xfree(reply);
726:
727: packet_integrity_check(plen, 4 + auth.length, type);
728:
1.40 markus 729: /*
730: * If his response isn't properly encrypted with the session
731: * key, and the decrypted checksum fails to match, he's
732: * bogus. Bail out.
733: */
1.38 markus 734: r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
735: &foreign, &local, &msg_data);
736: if (r != KSUCCESS) {
737: debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]);
738: packet_disconnect("Kerberos V4 challenge failed!");
739: }
740: /* Fetch the (incremented) checksum that we supplied in the request. */
741: (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum));
742: cksum = ntohl(cksum);
743:
744: /* If it matches, we're golden. */
745: if (cksum == checksum + 1) {
746: debug("Kerberos V4 challenge successful.");
747: return 1;
748: } else
749: packet_disconnect("Kerberos V4 challenge failed!");
750: break;
751:
752: default:
753: packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
754: }
755: return 0;
1.1 deraadt 756: }
1.38 markus 757:
1.1 deraadt 758: #endif /* KRB4 */
759:
760: #ifdef AFS
1.38 markus 761: int
762: send_kerberos_tgt()
1.1 deraadt 763: {
1.38 markus 764: CREDENTIALS *creds;
765: char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
766: int r, type, plen;
1.57 markus 767: char buffer[8192];
1.38 markus 768: struct stat st;
769:
770: /* Don't do anything if we don't have any tickets. */
771: if (stat(tkt_string(), &st) < 0)
772: return 0;
773:
774: creds = xmalloc(sizeof(*creds));
775:
776: if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) {
777: debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]);
778: return 0;
779: }
780: if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
781: debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]);
782: return 0;
783: }
784: if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
785: debug("Kerberos V4 ticket expired: %s", TKT_FILE);
786: return 0;
787: }
1.57 markus 788: creds_to_radix(creds, (unsigned char *)buffer);
1.38 markus 789: xfree(creds);
790:
791: packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
1.57 markus 792: packet_put_string(buffer, strlen(buffer));
1.38 markus 793: packet_send();
794: packet_write_wait();
795:
796: type = packet_read(&plen);
1.1 deraadt 797:
1.38 markus 798: if (type == SSH_SMSG_FAILURE)
799: debug("Kerberos TGT for realm %s rejected.", prealm);
800: else if (type != SSH_SMSG_SUCCESS)
801: packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
802:
803: return 1;
1.1 deraadt 804: }
805:
1.38 markus 806: void
807: send_afs_tokens(void)
1.1 deraadt 808: {
1.38 markus 809: CREDENTIALS creds;
810: struct ViceIoctl parms;
811: struct ClearToken ct;
812: int i, type, len, plen;
813: char buf[2048], *p, *server_cell;
1.57 markus 814: char buffer[8192];
1.38 markus 815:
816: /* Move over ktc_GetToken, here's something leaner. */
817: for (i = 0; i < 100; i++) { /* just in case */
818: parms.in = (char *) &i;
819: parms.in_size = sizeof(i);
820: parms.out = buf;
821: parms.out_size = sizeof(buf);
822: if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0)
823: break;
824: p = buf;
825:
826: /* Get secret token. */
827: memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
828: if (creds.ticket_st.length > MAX_KTXT_LEN)
829: break;
830: p += sizeof(unsigned int);
831: memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
832: p += creds.ticket_st.length;
833:
834: /* Get clear token. */
835: memcpy(&len, p, sizeof(len));
836: if (len != sizeof(struct ClearToken))
837: break;
838: p += sizeof(len);
839: memcpy(&ct, p, len);
840: p += len;
841: p += sizeof(len); /* primary flag */
842: server_cell = p;
843:
844: /* Flesh out our credentials. */
845: strlcpy(creds.service, "afs", sizeof creds.service);
846: creds.instance[0] = '\0';
847: strlcpy(creds.realm, server_cell, REALM_SZ);
848: memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
849: creds.issue_date = ct.BeginTimestamp;
850: creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
851: creds.kvno = ct.AuthHandle;
852: snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId);
853: creds.pinst[0] = '\0';
854:
855: /* Encode token, ship it off. */
1.57 markus 856: if (!creds_to_radix(&creds, (unsigned char*) buffer))
1.38 markus 857: break;
858: packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
1.57 markus 859: packet_put_string(buffer, strlen(buffer));
1.38 markus 860: packet_send();
861: packet_write_wait();
862:
863: /* Roger, Roger. Clearance, Clarence. What's your vector,
864: Victor? */
865: type = packet_read(&plen);
866:
867: if (type == SSH_SMSG_FAILURE)
868: debug("AFS token for cell %s rejected.", server_cell);
869: else if (type != SSH_SMSG_SUCCESS)
870: packet_disconnect("Protocol error on AFS token response: %d", type);
871: }
1.1 deraadt 872: }
1.38 markus 873:
1.1 deraadt 874: #endif /* AFS */
875:
1.39 deraadt 876: /*
1.43 markus 877: * Tries to authenticate with any string-based challenge/response system.
878: * Note that the client code is not tied to s/key or TIS.
879: */
880: int
881: try_skey_authentication()
882: {
1.57 markus 883: int type, i;
884: int payload_len;
885: unsigned int clen;
1.43 markus 886: char *challenge, *response;
887:
888: debug("Doing skey authentication.");
889:
890: /* request a challenge */
891: packet_start(SSH_CMSG_AUTH_TIS);
892: packet_send();
893: packet_write_wait();
894:
895: type = packet_read(&payload_len);
896: if (type != SSH_SMSG_FAILURE &&
897: type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
898: packet_disconnect("Protocol error: got %d in response "
899: "to skey-auth", type);
900: }
901: if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
902: debug("No challenge for skey authentication.");
903: return 0;
904: }
1.57 markus 905: challenge = packet_get_string(&clen);
906: packet_integrity_check(payload_len, (4 + clen), type);
1.43 markus 907: if (options.cipher == SSH_CIPHER_NONE)
908: log("WARNING: Encryption is disabled! "
909: "Reponse will be transmitted in clear text.");
910: fprintf(stderr, "%s\n", challenge);
1.54 markus 911: xfree(challenge);
1.43 markus 912: fflush(stderr);
913: for (i = 0; i < options.number_of_password_prompts; i++) {
914: if (i != 0)
915: error("Permission denied, please try again.");
916: response = read_passphrase("Response: ", 0);
917: packet_start(SSH_CMSG_AUTH_TIS_RESPONSE);
918: packet_put_string(response, strlen(response));
919: memset(response, 0, strlen(response));
920: xfree(response);
921: packet_send();
922: packet_write_wait();
923: type = packet_read(&payload_len);
924: if (type == SSH_SMSG_SUCCESS)
925: return 1;
926: if (type != SSH_SMSG_FAILURE)
927: packet_disconnect("Protocol error: got %d in response "
928: "to skey-auth-reponse", type);
929: }
930: /* failure */
931: return 0;
932: }
933:
934: /*
935: * Tries to authenticate with plain passwd authentication.
936: */
937: int
938: try_password_authentication(char *prompt)
939: {
940: int type, i, payload_len;
941: char *password;
942:
943: debug("Doing password authentication.");
944: if (options.cipher == SSH_CIPHER_NONE)
945: log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
946: for (i = 0; i < options.number_of_password_prompts; i++) {
947: if (i != 0)
948: error("Permission denied, please try again.");
949: password = read_passphrase(prompt, 0);
950: packet_start(SSH_CMSG_AUTH_PASSWORD);
951: packet_put_string(password, strlen(password));
952: memset(password, 0, strlen(password));
953: xfree(password);
954: packet_send();
955: packet_write_wait();
956:
957: type = packet_read(&payload_len);
958: if (type == SSH_SMSG_SUCCESS)
959: return 1;
960: if (type != SSH_SMSG_FAILURE)
961: packet_disconnect("Protocol error: got %d in response to passwd auth", type);
962: }
963: /* failure */
964: return 0;
965: }
966:
1.70 ! markus 967:
1.59 markus 968: char *
969: chop(char *s)
970: {
971: char *t = s;
972: while (*t) {
973: if(*t == '\n' || *t == '\r') {
974: *t = '\0';
975: return s;
976: }
977: t++;
978: }
979: return s;
980:
981: }
982:
1.43 markus 983: /*
1.39 deraadt 984: * Waits for the server identification string, and sends our own
985: * identification string.
986: */
1.38 markus 987: void
988: ssh_exchange_identification()
1.1 deraadt 989: {
1.38 markus 990: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 991: int remote_major, remote_minor, i, mismatch;
1.38 markus 992: int connection_in = packet_get_connection_in();
993: int connection_out = packet_get_connection_out();
994:
995: /* Read other side\'s version identification. */
996: for (i = 0; i < sizeof(buf) - 1; i++) {
1.56 markus 997: int len = read(connection_in, &buf[i], 1);
998: if (len < 0)
1.38 markus 999: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
1.56 markus 1000: if (len != 1)
1001: fatal("ssh_exchange_identification: Connection closed by remote host");
1.38 markus 1002: if (buf[i] == '\r') {
1003: buf[i] = '\n';
1004: buf[i + 1] = 0;
1.59 markus 1005: continue; /**XXX wait for \n */
1.38 markus 1006: }
1007: if (buf[i] == '\n') {
1008: buf[i + 1] = 0;
1009: break;
1010: }
1011: }
1012: buf[sizeof(buf) - 1] = 0;
1.59 markus 1013: server_version_string = xstrdup(buf);
1.38 markus 1014:
1.40 markus 1015: /*
1016: * Check that the versions match. In future this might accept
1017: * several versions and set appropriate flags to handle them.
1018: */
1.59 markus 1019: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
1020: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 1021: fatal("Bad remote protocol version identification: '%.100s'", buf);
1022: debug("Remote protocol version %d.%d, remote software version %.100s",
1023: remote_major, remote_minor, remote_version);
1024:
1.59 markus 1025: compat_datafellows(remote_version);
1.64 markus 1026: mismatch = 0;
1.59 markus 1027:
1.64 markus 1028: switch(remote_major) {
1029: case 1:
1030: if (remote_minor == 99 &&
1031: (options.protocol & SSH_PROTO_2) &&
1032: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
1033: enable_compat20();
1034: break;
1035: }
1036: if (!(options.protocol & SSH_PROTO_1)) {
1037: mismatch = 1;
1038: break;
1039: }
1040: if (remote_minor < 3) {
1041: fatal("Remote machine has too old SSH software version.");
1042: } else if (remote_minor == 3) {
1043: /* We speak 1.3, too. */
1044: enable_compat13();
1045: if (options.forward_agent) {
1046: log("Agent forwarding disabled for protocol 1.3");
1047: options.forward_agent = 0;
1048: }
1049: }
1050: break;
1051: case 2:
1052: if (options.protocol & SSH_PROTO_2) {
1053: enable_compat20();
1054: break;
1.38 markus 1055: }
1.64 markus 1056: /* FALLTHROUGH */
1.68 markus 1057: default:
1.64 markus 1058: mismatch = 1;
1059: break;
1.38 markus 1060: }
1.64 markus 1061: if (mismatch)
1.38 markus 1062: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 1063: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1064: remote_major);
1.70 ! markus 1065: if (compat20)
! 1066: packet_set_ssh2_format();
1.38 markus 1067: /* Send our own protocol version identification. */
1068: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 1069: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.65 markus 1070: compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1,
1.59 markus 1071: SSH_VERSION);
1.45 deraadt 1072: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 1073: fatal("write: %.100s", strerror(errno));
1.59 markus 1074: client_version_string = xstrdup(buf);
1075: chop(client_version_string);
1076: chop(server_version_string);
1077: debug("Local version string %.100s", client_version_string);
1.1 deraadt 1078: }
1079:
1.38 markus 1080: int
1081: read_yes_or_no(const char *prompt, int defval)
1.1 deraadt 1082: {
1.38 markus 1083: char buf[1024];
1084: FILE *f;
1085: int retval = -1;
1086:
1087: if (isatty(0))
1088: f = stdin;
1089: else
1090: f = fopen("/dev/tty", "rw");
1091:
1092: if (f == NULL)
1093: return 0;
1094:
1095: fflush(stdout);
1096:
1097: while (1) {
1098: fprintf(stderr, "%s", prompt);
1099: if (fgets(buf, sizeof(buf), f) == NULL) {
1100: /* Print a newline (the prompt probably didn\'t have one). */
1101: fprintf(stderr, "\n");
1102: strlcpy(buf, "no", sizeof buf);
1103: }
1104: /* Remove newline from response. */
1105: if (strchr(buf, '\n'))
1106: *strchr(buf, '\n') = 0;
1107:
1108: if (buf[0] == 0)
1109: retval = defval;
1110: if (strcmp(buf, "yes") == 0)
1111: retval = 1;
1112: if (strcmp(buf, "no") == 0)
1113: retval = 0;
1114:
1115: if (retval != -1) {
1116: if (f != stdin)
1117: fclose(f);
1118: return retval;
1119: }
1.1 deraadt 1120: }
1121: }
1122:
1.39 deraadt 1123: /*
1.46 markus 1124: * check whether the supplied host key is valid, return only if ok.
1.39 deraadt 1125: */
1.46 markus 1126:
1.38 markus 1127: void
1.70 ! markus 1128: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
! 1129: const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 1130: {
1.58 markus 1131: Key *file_key;
1.46 markus 1132: char *ip = NULL;
1.38 markus 1133: char hostline[1000], *hostp;
1134: HostStatus host_status;
1135: HostStatus ip_status;
1.49 markus 1136: int local = 0, host_ip_differ = 0;
1137: char ntop[NI_MAXHOST];
1138:
1139: /*
1140: * Force accepting of the host key for loopback/localhost. The
1141: * problem is that if the home directory is NFS-mounted to multiple
1142: * machines, localhost will refer to a different machine in each of
1143: * them, and the user will get bogus HOST_CHANGED warnings. This
1144: * essentially disables host authentication for localhost; however,
1145: * this is probably not a real problem.
1146: */
1.70 ! markus 1147: /** hostaddr == 0! */
1.49 markus 1148: switch (hostaddr->sa_family) {
1149: case AF_INET:
1150: local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1151: break;
1152: case AF_INET6:
1153: local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1154: break;
1155: default:
1156: local = 0;
1157: break;
1158: }
1159: if (local) {
1160: debug("Forcing accepting of host key for loopback/localhost.");
1161: return;
1162: }
1.42 markus 1163:
1164: /*
1.44 markus 1165: * Turn off check_host_ip for proxy connects, since
1.42 markus 1166: * we don't have the remote ip-address
1167: */
1168: if (options.proxy_command != NULL && options.check_host_ip)
1169: options.check_host_ip = 0;
1.38 markus 1170:
1.49 markus 1171: if (options.check_host_ip) {
1172: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1173: NULL, 0, NI_NUMERICHOST) != 0)
1174: fatal("check_host_key: getnameinfo failed");
1175: ip = xstrdup(ntop);
1176: }
1.38 markus 1177:
1.46 markus 1178: /*
1179: * Store the host key from the known host file in here so that we can
1180: * compare it with the key for the IP address.
1181: */
1.58 markus 1182: file_key = key_new(host_key->type);
1.38 markus 1183:
1.40 markus 1184: /*
1185: * Check if the host key is present in the user\'s list of known
1186: * hosts or in the systemwide list.
1187: */
1.70 ! markus 1188: host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key);
1.38 markus 1189: if (host_status == HOST_NEW)
1.70 ! markus 1190: host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key);
1.40 markus 1191: /*
1192: * Also perform check for the ip address, skip the check if we are
1193: * localhost or the hostname was an ip address to begin with
1194: */
1.38 markus 1195: if (options.check_host_ip && !local && strcmp(host, ip)) {
1.58 markus 1196: Key *ip_key = key_new(host_key->type);
1.70 ! markus 1197: ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key);
1.38 markus 1198:
1199: if (ip_status == HOST_NEW)
1.70 ! markus 1200: ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key);
1.38 markus 1201: if (host_status == HOST_CHANGED &&
1.58 markus 1202: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 1203: host_ip_differ = 1;
1204:
1.58 markus 1205: key_free(ip_key);
1.38 markus 1206: } else
1207: ip_status = host_status;
1208:
1.58 markus 1209: key_free(file_key);
1.38 markus 1210:
1211: switch (host_status) {
1212: case HOST_OK:
1213: /* The host is known and the key matches. */
1214: debug("Host '%.200s' is known and matches the host key.", host);
1215: if (options.check_host_ip) {
1216: if (ip_status == HOST_NEW) {
1.70 ! markus 1217: if (!add_host_to_hostfile(user_hostfile, ip, host_key))
1.38 markus 1218: log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).",
1.70 ! markus 1219: ip, user_hostfile);
1.38 markus 1220: else
1221: log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.",
1222: ip);
1223: } else if (ip_status != HOST_OK)
1224: log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'",
1225: host, ip);
1226: }
1227: break;
1228: case HOST_NEW:
1229: /* The host is new. */
1230: if (options.strict_host_key_checking == 1) {
1231: /* User has requested strict host key checking. We will not add the host key
1232: automatically. The only alternative left is to abort. */
1233: fatal("No host key is known for %.200s and you have requested strict checking.", host);
1234: } else if (options.strict_host_key_checking == 2) {
1235: /* The default */
1236: char prompt[1024];
1.58 markus 1237: char *fp = key_fingerprint(host_key);
1.38 markus 1238: snprintf(prompt, sizeof(prompt),
1.45 deraadt 1239: "The authenticity of host '%.200s' can't be established.\n"
1.58 markus 1240: "Key fingerprint is %s.\n"
1.45 deraadt 1241: "Are you sure you want to continue connecting (yes/no)? ",
1.58 markus 1242: host, fp);
1.38 markus 1243: if (!read_yes_or_no(prompt, -1))
1244: fatal("Aborted by user!\n");
1245: }
1246: if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) {
1247: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1248: hostp = hostline;
1249: } else
1250: hostp = host;
1251:
1252: /* If not in strict mode, add the key automatically to the local known_hosts file. */
1.70 ! markus 1253: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.38 markus 1254: log("Failed to add the host to the list of known hosts (%.500s).",
1.70 ! markus 1255: user_hostfile);
1.38 markus 1256: else
1257: log("Warning: Permanently added '%.200s' to the list of known hosts.",
1258: hostp);
1259: break;
1260: case HOST_CHANGED:
1261: if (options.check_host_ip && host_ip_differ) {
1262: char *msg;
1263: if (ip_status == HOST_NEW)
1264: msg = "is unknown";
1265: else if (ip_status == HOST_OK)
1266: msg = "is unchanged";
1267: else
1268: msg = "has a different value";
1269: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1270: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1271: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1272: error("The host key for %s has changed,", host);
1273: error("and the key for the according IP address %s", ip);
1274: error("%s. This could either mean that", msg);
1275: error("DNS SPOOFING is happening or the IP address for the host");
1276: error("and its host key have changed at the same time");
1277: }
1278: /* The host key has changed. */
1279: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 1280: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 1281: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1282: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1283: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1284: error("It is also possible that the host key has just been changed.");
1285: error("Please contact your system administrator.");
1286: error("Add correct host key in %.100s to get rid of this message.",
1.70 ! markus 1287: user_hostfile);
1.38 markus 1288:
1.40 markus 1289: /*
1290: * If strict host key checking is in use, the user will have
1291: * to edit the key manually and we can only abort.
1292: */
1.38 markus 1293: if (options.strict_host_key_checking)
1294: fatal("Host key for %.200s has changed and you have requested strict checking.", host);
1295:
1.40 markus 1296: /*
1297: * If strict host key checking has not been requested, allow
1298: * the connection but without password authentication or
1299: * agent forwarding.
1300: */
1.38 markus 1301: if (options.password_authentication) {
1302: error("Password authentication is disabled to avoid trojan horses.");
1303: options.password_authentication = 0;
1304: }
1305: if (options.forward_agent) {
1306: error("Agent forwarding is disabled to avoid trojan horses.");
1307: options.forward_agent = 0;
1308: }
1.40 markus 1309: /*
1310: * XXX Should permit the user to change to use the new id.
1311: * This could be done by converting the host key to an
1312: * identifying sentence, tell that the host identifies itself
1313: * by that sentence, and ask the user if he/she whishes to
1314: * accept the authentication.
1315: */
1.38 markus 1316: break;
1317: }
1318: if (options.check_host_ip)
1319: xfree(ip);
1.46 markus 1320: }
1321:
1322: /*
1.59 markus 1323: * SSH2 key exchange
1324: */
1.70 ! markus 1325:
1.59 markus 1326: void
1327: ssh_kex2(char *host, struct sockaddr *hostaddr)
1328: {
1329: Kex *kex;
1330: char *cprop[PROPOSAL_MAX];
1331: char *sprop[PROPOSAL_MAX];
1332: Buffer *client_kexinit;
1333: Buffer *server_kexinit;
1334: int payload_len, dlen;
1335: unsigned int klen, kout;
1336: char *ptr;
1337: char *signature = NULL;
1338: unsigned int slen;
1339: char *server_host_key_blob = NULL;
1340: Key *server_host_key;
1341: unsigned int sbloblen;
1342: DH *dh;
1343: BIGNUM *dh_server_pub = 0;
1344: BIGNUM *shared_secret = 0;
1345: int i;
1346: unsigned char *kbuf;
1347: unsigned char *hash;
1348:
1349: /* KEXINIT */
1350:
1351: debug("Sending KEX init.");
1.64 markus 1352: if (options.ciphers != NULL) {
1.68 markus 1353: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.64 markus 1354: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1355: } else if (
1356: options.cipher == SSH_CIPHER_ARCFOUR ||
1.68 markus 1357: options.cipher == SSH_CIPHER_3DES_CBC ||
1358: options.cipher == SSH_CIPHER_CAST128_CBC ||
1359: options.cipher == SSH_CIPHER_BLOWFISH_CBC) {
1.64 markus 1360: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.59 markus 1361: myproposal[PROPOSAL_ENC_ALGS_STOC] = cipher_name(options.cipher);
1362: }
1363: if (options.compression) {
1364: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
1365: myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
1366: } else {
1367: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
1368: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1369: }
1370: for (i = 0; i < PROPOSAL_MAX; i++)
1371: cprop[i] = xstrdup(myproposal[i]);
1372:
1373: client_kexinit = kex_init(cprop);
1374: packet_start(SSH2_MSG_KEXINIT);
1375: packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));
1376: packet_send();
1377: packet_write_wait();
1378:
1379: debug("done");
1380:
1381: packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
1382:
1383: /* save payload for session_id */
1384: server_kexinit = xmalloc(sizeof(*server_kexinit));
1385: buffer_init(server_kexinit);
1386: ptr = packet_get_raw(&payload_len);
1387: buffer_append(server_kexinit, ptr, payload_len);
1388:
1389: /* skip cookie */
1390: for (i = 0; i < 16; i++)
1391: (void) packet_get_char();
1392: /* kex init proposal strings */
1393: for (i = 0; i < PROPOSAL_MAX; i++) {
1394: sprop[i] = packet_get_string(NULL);
1395: debug("got kexinit string: %s", sprop[i]);
1396: }
1397: i = (int) packet_get_char();
1398: debug("first kex follow == %d", i);
1399: i = packet_get_int();
1400: debug("reserved == %d", i);
1.67 markus 1401: packet_done();
1.59 markus 1402:
1403: debug("done read kexinit");
1404: kex = kex_choose_conf(cprop, sprop, 0);
1405:
1406: /* KEXDH */
1407:
1408: debug("Sending SSH2_MSG_KEXDH_INIT.");
1409:
1410: /* generate and send 'e', client DH public key */
1.63 markus 1411: dh = dh_new_group1();
1.59 markus 1412: packet_start(SSH2_MSG_KEXDH_INIT);
1413: packet_put_bignum2(dh->pub_key);
1414: packet_send();
1415: packet_write_wait();
1416:
1417: #ifdef DEBUG_KEXDH
1418: fprintf(stderr, "\np= ");
1419: bignum_print(dh->p);
1420: fprintf(stderr, "\ng= ");
1421: bignum_print(dh->g);
1422: fprintf(stderr, "\npub= ");
1423: bignum_print(dh->pub_key);
1424: fprintf(stderr, "\n");
1.68 markus 1425: DHparams_print_fp(stderr, dh);
1.59 markus 1426: #endif
1427:
1428: debug("Wait SSH2_MSG_KEXDH_REPLY.");
1429:
1430: packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);
1431:
1432: debug("Got SSH2_MSG_KEXDH_REPLY.");
1433:
1434: /* key, cert */
1435: server_host_key_blob = packet_get_string(&sbloblen);
1.70 ! markus 1436: server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
1.59 markus 1437: if (server_host_key == NULL)
1438: fatal("cannot decode server_host_key_blob");
1439:
1.70 ! markus 1440: check_host_key(host, hostaddr, server_host_key,
! 1441: options.user_hostfile2, options.system_hostfile2);
1.59 markus 1442:
1443: /* DH paramter f, server public DH key */
1444: dh_server_pub = BN_new();
1445: if (dh_server_pub == NULL)
1446: fatal("dh_server_pub == NULL");
1447: packet_get_bignum2(dh_server_pub, &dlen);
1448:
1449: #ifdef DEBUG_KEXDH
1450: fprintf(stderr, "\ndh_server_pub= ");
1451: bignum_print(dh_server_pub);
1452: fprintf(stderr, "\n");
1453: debug("bits %d", BN_num_bits(dh_server_pub));
1454: #endif
1455:
1456: /* signed H */
1457: signature = packet_get_string(&slen);
1.67 markus 1458: packet_done();
1.63 markus 1459:
1460: if (!dh_pub_is_valid(dh, dh_server_pub))
1461: packet_disconnect("bad server public DH value");
1.59 markus 1462:
1463: klen = DH_size(dh);
1464: kbuf = xmalloc(klen);
1465: kout = DH_compute_key(kbuf, dh_server_pub, dh);
1466: #ifdef DEBUG_KEXDH
1467: debug("shared secret: len %d/%d", klen, kout);
1.68 markus 1468: fprintf(stderr, "shared secret == ");
1469: for (i = 0; i< kout; i++)
1470: fprintf(stderr, "%02x", (kbuf[i])&0xff);
1471: fprintf(stderr, "\n");
1.59 markus 1472: #endif
1.68 markus 1473: shared_secret = BN_new();
1.59 markus 1474:
1.68 markus 1475: BN_bin2bn(kbuf, kout, shared_secret);
1.59 markus 1476: memset(kbuf, 0, klen);
1477: xfree(kbuf);
1478:
1479: /* calc and verify H */
1480: hash = kex_hash(
1481: client_version_string,
1482: server_version_string,
1483: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1484: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1485: server_host_key_blob, sbloblen,
1486: dh->pub_key,
1487: dh_server_pub,
1488: shared_secret
1489: );
1.60 markus 1490: buffer_free(client_kexinit);
1491: buffer_free(server_kexinit);
1.59 markus 1492: xfree(client_kexinit);
1493: xfree(server_kexinit);
1494: #ifdef DEBUG_KEXDH
1.68 markus 1495: fprintf(stderr, "hash == ");
1496: for (i = 0; i< 20; i++)
1497: fprintf(stderr, "%02x", (hash[i])&0xff);
1498: fprintf(stderr, "\n");
1.59 markus 1499: #endif
1.70 ! markus 1500: if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
! 1501: fatal("dsa_verify failed for server_host_key");
1.59 markus 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:
1.70 ! markus 1510: /* save session id */
! 1511: session_id2_len = 20;
! 1512: session_id2 = xmalloc(session_id2_len);
! 1513: memcpy(session_id2, hash, session_id2_len);
! 1514:
1.59 markus 1515: debug("Wait SSH2_MSG_NEWKEYS.");
1516: packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1.67 markus 1517: packet_done();
1.59 markus 1518: debug("GOT SSH2_MSG_NEWKEYS.");
1519:
1520: debug("send SSH2_MSG_NEWKEYS.");
1521: packet_start(SSH2_MSG_NEWKEYS);
1522: packet_send();
1523: packet_write_wait();
1524: debug("done: send SSH2_MSG_NEWKEYS.");
1525:
1.62 markus 1526: #ifdef DEBUG_KEXDH
1.59 markus 1527: /* send 1st encrypted/maced/compressed message */
1528: packet_start(SSH2_MSG_IGNORE);
1529: packet_put_cstring("markus");
1530: packet_send();
1531: packet_write_wait();
1.62 markus 1532: #endif
1.59 markus 1533: debug("done: KEX2.");
1534: }
1535: /*
1536: * Authenticate user
1537: */
1.70 ! markus 1538: int
! 1539: ssh2_try_passwd(const char *server_user, const char *host, const char *service)
! 1540: {
! 1541: char prompt[80];
! 1542: char *password;
! 1543:
! 1544: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
! 1545: server_user, host);
! 1546: password = read_passphrase(prompt, 0);
! 1547: packet_start(SSH2_MSG_USERAUTH_REQUEST);
! 1548: packet_put_cstring(server_user);
! 1549: packet_put_cstring(service);
! 1550: packet_put_cstring("password");
! 1551: packet_put_char(0);
! 1552: packet_put_cstring(password);
! 1553: memset(password, 0, strlen(password));
! 1554: xfree(password);
! 1555: packet_send();
! 1556: packet_write_wait();
! 1557: return 1;
! 1558: }
! 1559:
! 1560: int
! 1561: ssh2_try_pubkey(char *filename,
! 1562: const char *server_user, const char *host, const char *service)
! 1563: {
! 1564: Buffer b;
! 1565: Key *k;
! 1566: unsigned char *blob, *signature;
! 1567: int bloblen, slen;
! 1568:
! 1569: debug("try pubkey: %s", filename);
! 1570:
! 1571: k = key_new(KEY_DSA);
! 1572: if (!load_private_key(filename, "", k, NULL)) {
! 1573: int success = 0;
! 1574: char *passphrase;
! 1575: char prompt[300];
! 1576: snprintf(prompt, sizeof prompt,
! 1577: "Enter passphrase for DSA key '%.100s': ",
! 1578: filename);
! 1579: passphrase = read_passphrase(prompt, 0);
! 1580: success = load_private_key(filename, passphrase, k, NULL);
! 1581: memset(passphrase, 0, strlen(passphrase));
! 1582: xfree(passphrase);
! 1583: if (!success)
! 1584: return 0;
! 1585: }
! 1586: dsa_make_key_blob(k, &blob, &bloblen);
! 1587:
! 1588: /* data to be signed */
! 1589: buffer_init(&b);
! 1590: buffer_append(&b, session_id2, session_id2_len);
! 1591: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
! 1592: buffer_put_cstring(&b, server_user);
! 1593: buffer_put_cstring(&b, service);
! 1594: buffer_put_cstring(&b, "publickey");
! 1595: buffer_put_char(&b, 1);
! 1596: buffer_put_cstring(&b, KEX_DSS);
! 1597: buffer_put_string(&b, blob, bloblen);
! 1598:
! 1599: /* generate signature */
! 1600: dsa_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
! 1601: key_free(k);
! 1602: #ifdef DEBUG_DSS
! 1603: buffer_dump(&b);
! 1604: #endif
! 1605: /* append signature */
! 1606: buffer_put_string(&b, signature, slen);
! 1607: xfree(signature);
! 1608:
! 1609: /* skip session id and packet type */
! 1610: if (buffer_len(&b) < session_id2_len + 1)
! 1611: fatal("ssh2_try_pubkey: internal error");
! 1612: buffer_consume(&b, session_id2_len + 1);
! 1613:
! 1614: /* put remaining data from buffer into packet */
! 1615: packet_start(SSH2_MSG_USERAUTH_REQUEST);
! 1616: packet_put_raw(buffer_ptr(&b), buffer_len(&b));
! 1617: buffer_free(&b);
! 1618:
! 1619: /* send */
! 1620: packet_send();
! 1621: packet_write_wait();
! 1622: return 1;
! 1623: }
! 1624:
1.59 markus 1625: void
1.70 ! markus 1626: ssh_userauth2(const char *server_user, char *host)
1.59 markus 1627: {
1628: int type;
1629: int plen;
1.70 ! markus 1630: int sent;
1.59 markus 1631: unsigned int dlen;
1632: int partial;
1.70 ! markus 1633: int i = 0;
1.59 markus 1634: char *auths;
1.67 markus 1635: char *service = "ssh-connection"; /* service name */
1.59 markus 1636:
1637: debug("send SSH2_MSG_SERVICE_REQUEST");
1638: packet_start(SSH2_MSG_SERVICE_REQUEST);
1639: packet_put_cstring("ssh-userauth");
1640: packet_send();
1641: packet_write_wait();
1642:
1643: type = packet_read(&plen);
1644: if (type != SSH2_MSG_SERVICE_ACCEPT) {
1645: fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
1646: }
1.67 markus 1647: if (packet_remaining() > 0) {
1648: char *reply = packet_get_string(&plen);
1649: debug("service_accept: %s", reply);
1650: xfree(reply);
1651: } else {
1652: /* payload empty for ssh-2.0.13 ?? */
1653: log("buggy server: service_accept w/o service");
1654: }
1655: packet_done();
1.59 markus 1656: debug("got SSH2_MSG_SERVICE_ACCEPT");
1657:
1658: /* INITIAL request for auth */
1659: packet_start(SSH2_MSG_USERAUTH_REQUEST);
1660: packet_put_cstring(server_user);
1661: packet_put_cstring(service);
1662: packet_put_cstring("none");
1663: packet_send();
1664: packet_write_wait();
1665:
1666: for (;;) {
1.70 ! markus 1667: sent = 0;
1.59 markus 1668: type = packet_read(&plen);
1669: if (type == SSH2_MSG_USERAUTH_SUCCESS)
1670: break;
1671: if (type != SSH2_MSG_USERAUTH_FAILURE)
1672: fatal("access denied: %d", type);
1673: /* SSH2_MSG_USERAUTH_FAILURE means: try again */
1674: auths = packet_get_string(&dlen);
1675: debug("authentications that can continue: %s", auths);
1676: partial = packet_get_char();
1.67 markus 1677: packet_done();
1.59 markus 1678: if (partial)
1679: debug("partial success");
1.70 ! markus 1680: if (strstr(auths, "publickey") != NULL) {
! 1681: while (i < options.num_identity_files2) {
! 1682: sent = ssh2_try_pubkey(
! 1683: options.identity_files2[i++],
! 1684: server_user, host, service);
! 1685: if (sent)
! 1686: break;
! 1687: }
! 1688: }
! 1689: if (!sent) {
! 1690: if (strstr(auths, "password") != NULL) {
! 1691: sent = ssh2_try_passwd(server_user, host, service);
! 1692: } else {
! 1693: fatal("passwd auth not supported: %s", auths);
! 1694: }
! 1695: if (!sent)
! 1696: fatal("no more auths: %s", auths);
! 1697: }
1.59 markus 1698: xfree(auths);
1699: }
1.67 markus 1700: packet_done();
1.59 markus 1701: debug("ssh-userauth2 successfull");
1702: }
1703:
1704: /*
1.51 markus 1705: * SSH1 key exchange
1.46 markus 1706: */
1707: void
1.51 markus 1708: ssh_kex(char *host, struct sockaddr *hostaddr)
1.46 markus 1709: {
1.51 markus 1710: int i;
1.46 markus 1711: BIGNUM *key;
1712: RSA *host_key;
1713: RSA *public_key;
1.70 ! markus 1714: Key k;
1.46 markus 1715: int bits, rbits;
1.59 markus 1716: int ssh_cipher_default = SSH_CIPHER_3DES;
1.46 markus 1717: unsigned char session_key[SSH_SESSION_KEY_LENGTH];
1.51 markus 1718: unsigned char cookie[8];
1719: unsigned int supported_ciphers;
1.46 markus 1720: unsigned int server_flags, client_flags;
1721: int payload_len, clen, sum_len = 0;
1722: u_int32_t rand = 0;
1723:
1724: debug("Waiting for server public key.");
1725:
1726: /* Wait for a public key packet from the server. */
1727: packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
1728:
1.51 markus 1729: /* Get cookie from the packet. */
1.46 markus 1730: for (i = 0; i < 8; i++)
1.51 markus 1731: cookie[i] = packet_get_char();
1.46 markus 1732:
1733: /* Get the public key. */
1734: public_key = RSA_new();
1735: bits = packet_get_int();/* bits */
1736: public_key->e = BN_new();
1737: packet_get_bignum(public_key->e, &clen);
1738: sum_len += clen;
1739: public_key->n = BN_new();
1740: packet_get_bignum(public_key->n, &clen);
1741: sum_len += clen;
1742:
1743: rbits = BN_num_bits(public_key->n);
1744: if (bits != rbits) {
1745: log("Warning: Server lies about size of server public key: "
1746: "actual size is %d bits vs. announced %d.", rbits, bits);
1747: log("Warning: This may be due to an old implementation of ssh.");
1748: }
1749: /* Get the host key. */
1750: host_key = RSA_new();
1751: bits = packet_get_int();/* bits */
1752: host_key->e = BN_new();
1753: packet_get_bignum(host_key->e, &clen);
1754: sum_len += clen;
1755: host_key->n = BN_new();
1756: packet_get_bignum(host_key->n, &clen);
1757: sum_len += clen;
1758:
1759: rbits = BN_num_bits(host_key->n);
1760: if (bits != rbits) {
1761: log("Warning: Server lies about size of server host key: "
1762: "actual size is %d bits vs. announced %d.", rbits, bits);
1763: log("Warning: This may be due to an old implementation of ssh.");
1764: }
1765:
1766: /* Get protocol flags. */
1767: server_flags = packet_get_int();
1768: packet_set_protocol_flags(server_flags);
1769:
1770: supported_ciphers = packet_get_int();
1771: supported_authentications = packet_get_int();
1772:
1773: debug("Received server public key (%d bits) and host key (%d bits).",
1774: BN_num_bits(public_key->n), BN_num_bits(host_key->n));
1775:
1776: packet_integrity_check(payload_len,
1777: 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
1778: SSH_SMSG_PUBLIC_KEY);
1.70 ! markus 1779: k.type = KEY_RSA;
! 1780: k.rsa = host_key;
! 1781: check_host_key(host, hostaddr, &k,
! 1782: options.user_hostfile, options.system_hostfile);
1.46 markus 1783:
1784: client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN;
1785:
1.51 markus 1786: compute_session_id(session_id, cookie, host_key->n, public_key->n);
1.38 markus 1787:
1788: /* Generate a session key. */
1789: arc4random_stir();
1790:
1.40 markus 1791: /*
1792: * Generate an encryption key for the session. The key is a 256 bit
1793: * random number, interpreted as a 32-byte key, with the least
1794: * significant 8 bits being the first byte of the key.
1795: */
1.38 markus 1796: for (i = 0; i < 32; i++) {
1797: if (i % 4 == 0)
1798: rand = arc4random();
1799: session_key[i] = rand & 0xff;
1800: rand >>= 8;
1801: }
1802:
1.40 markus 1803: /*
1804: * According to the protocol spec, the first byte of the session key
1805: * is the highest byte of the integer. The session key is xored with
1806: * the first 16 bytes of the session id.
1807: */
1.38 markus 1808: key = BN_new();
1809: BN_set_word(key, 0);
1810: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
1811: BN_lshift(key, key, 8);
1812: if (i < 16)
1813: BN_add_word(key, session_key[i] ^ session_id[i]);
1814: else
1815: BN_add_word(key, session_key[i]);
1816: }
1817:
1.40 markus 1818: /*
1819: * Encrypt the integer using the public key and host key of the
1820: * server (key with smaller modulus first).
1821: */
1.38 markus 1822: if (BN_cmp(public_key->n, host_key->n) < 0) {
1823: /* Public key has smaller modulus. */
1824: if (BN_num_bits(host_key->n) <
1825: BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) {
1826: fatal("respond_to_rsa_challenge: host_key %d < public_key %d + "
1827: "SSH_KEY_BITS_RESERVED %d",
1828: BN_num_bits(host_key->n),
1829: BN_num_bits(public_key->n),
1830: SSH_KEY_BITS_RESERVED);
1831: }
1832: rsa_public_encrypt(key, key, public_key);
1833: rsa_public_encrypt(key, key, host_key);
1834: } else {
1835: /* Host key has smaller modulus (or they are equal). */
1836: if (BN_num_bits(public_key->n) <
1837: BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) {
1838: fatal("respond_to_rsa_challenge: public_key %d < host_key %d + "
1839: "SSH_KEY_BITS_RESERVED %d",
1840: BN_num_bits(public_key->n),
1841: BN_num_bits(host_key->n),
1842: SSH_KEY_BITS_RESERVED);
1843: }
1844: rsa_public_encrypt(key, key, host_key);
1845: rsa_public_encrypt(key, key, public_key);
1846: }
1847:
1.52 markus 1848: /* Destroy the public keys since we no longer need them. */
1849: RSA_free(public_key);
1850: RSA_free(host_key);
1851:
1.38 markus 1852: if (options.cipher == SSH_CIPHER_NOT_SET) {
1.61 markus 1853: if (cipher_mask1() & supported_ciphers & (1 << ssh_cipher_default))
1.38 markus 1854: options.cipher = ssh_cipher_default;
1855: else {
1856: debug("Cipher %s not supported, using %.100s instead.",
1857: cipher_name(ssh_cipher_default),
1858: cipher_name(SSH_FALLBACK_CIPHER));
1859: options.cipher = SSH_FALLBACK_CIPHER;
1860: }
1861: }
1862: /* Check that the selected cipher is supported. */
1863: if (!(supported_ciphers & (1 << options.cipher)))
1864: fatal("Selected cipher type %.100s not supported by server.",
1865: cipher_name(options.cipher));
1866:
1867: debug("Encryption type: %.100s", cipher_name(options.cipher));
1868:
1869: /* Send the encrypted session key to the server. */
1870: packet_start(SSH_CMSG_SESSION_KEY);
1871: packet_put_char(options.cipher);
1872:
1.51 markus 1873: /* Send the cookie back to the server. */
1.38 markus 1874: for (i = 0; i < 8; i++)
1.51 markus 1875: packet_put_char(cookie[i]);
1.38 markus 1876:
1.52 markus 1877: /* Send and destroy the encrypted encryption key integer. */
1.38 markus 1878: packet_put_bignum(key);
1.52 markus 1879: BN_clear_free(key);
1.38 markus 1880:
1881: /* Send protocol flags. */
1.46 markus 1882: packet_put_int(client_flags);
1.38 markus 1883:
1884: /* Send the packet now. */
1885: packet_send();
1886: packet_write_wait();
1887:
1888: debug("Sent encrypted session key.");
1889:
1890: /* Set the encryption key. */
1891: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher);
1892:
1893: /* We will no longer need the session key here. Destroy any extra copies. */
1894: memset(session_key, 0, sizeof(session_key));
1895:
1.40 markus 1896: /*
1897: * Expect a success message from the server. Note that this message
1898: * will be received in encrypted form.
1899: */
1.38 markus 1900: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1901:
1902: debug("Received encrypted confirmation.");
1.51 markus 1903: }
1904:
1905: /*
1906: * Authenticate user
1907: */
1908: void
1.70 ! markus 1909: ssh_userauth(
! 1910: const char* local_user,
! 1911: const char* server_user,
! 1912: char *host,
! 1913: int host_key_valid, RSA *own_host_key)
1.51 markus 1914: {
1915: int i, type;
1916: int payload_len;
1917:
1.70 ! markus 1918: if (supported_authentications == 0)
! 1919: fatal("ssh_userauth: server supports no auth methods");
1.38 markus 1920:
1921: /* Send the name of the user to log in as on the server. */
1922: packet_start(SSH_CMSG_USER);
1923: packet_put_string(server_user, strlen(server_user));
1.16 dugsong 1924: packet_send();
1925: packet_write_wait();
1.38 markus 1926:
1.40 markus 1927: /*
1928: * The server should respond with success if no authentication is
1929: * needed (the user has no password). Otherwise the server responds
1930: * with failure.
1931: */
1.16 dugsong 1932: type = packet_read(&payload_len);
1.38 markus 1933:
1934: /* check whether the connection was accepted without authentication. */
1.16 dugsong 1935: if (type == SSH_SMSG_SUCCESS)
1.38 markus 1936: return;
1.16 dugsong 1937: if (type != SSH_SMSG_FAILURE)
1.38 markus 1938: packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
1939: type);
1940:
1941: #ifdef AFS
1942: /* Try Kerberos tgt passing if the server supports it. */
1943: if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
1944: options.kerberos_tgt_passing) {
1945: if (options.cipher == SSH_CIPHER_NONE)
1946: log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
1947: (void) send_kerberos_tgt();
1948: }
1949: /* Try AFS token passing if the server supports it. */
1950: if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
1951: options.afs_token_passing && k_hasafs()) {
1952: if (options.cipher == SSH_CIPHER_NONE)
1953: log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
1954: send_afs_tokens();
1955: }
1956: #endif /* AFS */
1957:
1958: #ifdef KRB4
1959: if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
1960: options.kerberos_authentication) {
1961: debug("Trying Kerberos authentication.");
1962: if (try_kerberos_authentication()) {
1963: /* The server should respond with success or failure. */
1964: type = packet_read(&payload_len);
1965: if (type == SSH_SMSG_SUCCESS)
1966: return;
1967: if (type != SSH_SMSG_FAILURE)
1968: packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
1969: }
1970: }
1971: #endif /* KRB4 */
1972:
1.40 markus 1973: /*
1974: * Use rhosts authentication if running in privileged socket and we
1975: * do not wish to remain anonymous.
1976: */
1.38 markus 1977: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
1978: options.rhosts_authentication) {
1979: debug("Trying rhosts authentication.");
1980: packet_start(SSH_CMSG_AUTH_RHOSTS);
1981: packet_put_string(local_user, strlen(local_user));
1982: packet_send();
1983: packet_write_wait();
1984:
1985: /* The server should respond with success or failure. */
1986: type = packet_read(&payload_len);
1987: if (type == SSH_SMSG_SUCCESS)
1988: return;
1989: if (type != SSH_SMSG_FAILURE)
1990: packet_disconnect("Protocol error: got %d in response to rhosts auth",
1991: type);
1992: }
1.40 markus 1993: /*
1994: * Try .rhosts or /etc/hosts.equiv authentication with RSA host
1995: * authentication.
1996: */
1.38 markus 1997: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
1998: options.rhosts_rsa_authentication && host_key_valid) {
1999: if (try_rhosts_rsa_authentication(local_user, own_host_key))
2000: return;
2001: }
2002: /* Try RSA authentication if the server supports it. */
2003: if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
2004: options.rsa_authentication) {
1.40 markus 2005: /*
2006: * Try RSA authentication using the authentication agent. The
2007: * agent is tried first because no passphrase is needed for
2008: * it, whereas identity files may require passphrases.
2009: */
1.38 markus 2010: if (try_agent_authentication())
2011: return;
2012:
2013: /* Try RSA authentication for each identity. */
2014: for (i = 0; i < options.num_identity_files; i++)
1.43 markus 2015: if (try_rsa_authentication(options.identity_files[i]))
1.38 markus 2016: return;
2017: }
2018: /* Try skey authentication if the server supports it. */
2019: if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
2020: options.skey_authentication && !options.batch_mode) {
1.43 markus 2021: if (try_skey_authentication())
2022: return;
1.38 markus 2023: }
2024: /* Try password authentication if the server supports it. */
2025: if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
2026: options.password_authentication && !options.batch_mode) {
2027: char prompt[80];
1.45 deraadt 2028:
1.43 markus 2029: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1.45 deraadt 2030: server_user, host);
1.43 markus 2031: if (try_password_authentication(prompt))
2032: return;
1.38 markus 2033: }
2034: /* All authentication methods have failed. Exit with an error message. */
2035: fatal("Permission denied.");
2036: /* NOTREACHED */
1.51 markus 2037: }
1.70 ! markus 2038:
1.51 markus 2039: /*
2040: * Starts a dialog with the server, and authenticates the current user on the
2041: * server. This does not need any extra privileges. The basic connection
2042: * to the server must already have been established before this is called.
2043: * If login fails, this function prints an error and never returns.
2044: * This function does not require super-user privileges.
2045: */
2046: void
2047: ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
2048: struct sockaddr *hostaddr, uid_t original_real_uid)
2049: {
1.70 ! markus 2050: struct passwd *pw;
1.51 markus 2051: char *host, *cp;
1.70 ! markus 2052: char *server_user, *local_user;
! 2053:
! 2054: /* Get local user name. Use it as server user if no user name was given. */
! 2055: pw = getpwuid(original_real_uid);
! 2056: if (!pw)
! 2057: fatal("User id %d not found from user database.", original_real_uid);
! 2058: local_user = xstrdup(pw->pw_name);
! 2059: server_user = options.user ? options.user : local_user;
1.51 markus 2060:
2061: /* Convert the user-supplied hostname into all lowercase. */
2062: host = xstrdup(orighost);
2063: for (cp = host; *cp; cp++)
2064: if (isupper(*cp))
2065: *cp = tolower(*cp);
2066:
2067: /* Exchange protocol version identification strings with the server. */
2068: ssh_exchange_identification();
2069:
2070: /* Put the connection into non-blocking mode. */
2071: packet_set_nonblocking();
2072:
2073: /* key exchange */
2074: /* authenticate user */
1.59 markus 2075: if (compat20) {
2076: ssh_kex2(host, hostaddr);
1.70 ! markus 2077: ssh_userauth2(server_user, host);
1.59 markus 2078: } else {
2079: ssh_kex(host, hostaddr);
1.70 ! markus 2080: ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key);
1.59 markus 2081: }
1.1 deraadt 2082: }
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