Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.5
1.1 deraadt 1: /*
2:
3: sshconnect.c
4:
5: Author: Tatu Ylonen <ylo@cs.hut.fi>
6:
7: Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8: All rights reserved
9:
10: Created: Sat Mar 18 22:15:47 1995 ylo
11:
12: Code to connect to a remote host, and to perform the client side of the
13: login (authentication) dialog.
14:
15: */
16:
17: #include "includes.h"
1.5 ! dugsong 18: RCSID("$Id: sshconnect.c,v 1.4 1999/09/29 15:52:55 provos Exp $");
1.1 deraadt 19:
1.3 provos 20: #include <ssl/bn.h>
1.1 deraadt 21: #include "xmalloc.h"
22: #include "rsa.h"
23: #include "ssh.h"
24: #include "packet.h"
25: #include "authfd.h"
26: #include "cipher.h"
27: #include "ssh_md5.h"
28: #include "mpaux.h"
29: #include "uidswap.h"
30:
31: /* Session id for the current session. */
32: unsigned char session_id[16];
33:
34: /* Connect to the given ssh server using a proxy command. */
35:
1.3 provos 36: int
37: ssh_proxy_connect(const char *host, int port, uid_t original_real_uid,
38: const char *proxy_command)
1.1 deraadt 39: {
40: Buffer command;
41: const char *cp;
42: char *command_string;
43: int pin[2], pout[2];
44: int pid;
45: char portstring[100];
46:
47: /* Convert the port number into a string. */
48: sprintf(portstring, "%d", port);
49:
50: /* Build the final command string in the buffer by making the appropriate
51: substitutions to the given proxy command. */
52: buffer_init(&command);
53: for (cp = proxy_command; *cp; cp++)
54: {
55: if (cp[0] == '%' && cp[1] == '%')
56: {
57: buffer_append(&command, "%", 1);
58: cp++;
59: continue;
60: }
61: if (cp[0] == '%' && cp[1] == 'h')
62: {
63: buffer_append(&command, host, strlen(host));
64: cp++;
65: continue;
66: }
67: if (cp[0] == '%' && cp[1] == 'p')
68: {
69: buffer_append(&command, portstring, strlen(portstring));
70: cp++;
71: continue;
72: }
73: buffer_append(&command, cp, 1);
74: }
75: buffer_append(&command, "\0", 1);
76:
77: /* Get the final command string. */
78: command_string = buffer_ptr(&command);
79:
80: /* Create pipes for communicating with the proxy. */
81: if (pipe(pin) < 0 || pipe(pout) < 0)
82: fatal("Could not create pipes to communicate with the proxy: %.100s",
83: strerror(errno));
84:
85: debug("Executing proxy command: %.500s", command_string);
86:
87: /* Fork and execute the proxy command. */
88: if ((pid = fork()) == 0)
89: {
90: char *argv[10];
91:
92: /* Child. Permanently give up superuser privileges. */
93: permanently_set_uid(original_real_uid);
94:
95: /* Redirect stdin and stdout. */
96: close(pin[1]);
97: if (pin[0] != 0)
98: {
99: if (dup2(pin[0], 0) < 0)
100: perror("dup2 stdin");
101: close(pin[0]);
102: }
103: close(pout[0]);
104: if (dup2(pout[1], 1) < 0)
105: perror("dup2 stdout");
106: close(pout[1]); /* Cannot be 1 because pin allocated two descriptors. */
107:
108: /* Stderr is left as it is so that error messages get printed on
109: the user's terminal. */
110: argv[0] = "/bin/sh";
111: argv[1] = "-c";
112: argv[2] = command_string;
113: argv[3] = NULL;
114:
115: /* Execute the proxy command. Note that we gave up any extra
116: privileges above. */
117: execv("/bin/sh", argv);
118: perror("/bin/sh");
119: exit(1);
120: }
121: /* Parent. */
122: if (pid < 0)
123: fatal("fork failed: %.100s", strerror(errno));
124:
125: /* Close child side of the descriptors. */
126: close(pin[0]);
127: close(pout[1]);
128:
129: /* Free the command name. */
130: buffer_free(&command);
131:
132: /* Set the connection file descriptors. */
1.3 provos 133: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 134:
135: return 1;
136: }
137:
138: /* Creates a (possibly privileged) socket for use as the ssh connection. */
139:
140: int ssh_create_socket(uid_t original_real_uid, int privileged)
141: {
142: int sock;
143:
144: /* If we are running as root and want to connect to a privileged port,
145: bind our own socket to a privileged port. */
146: if (privileged)
147: {
1.2 deraadt 148: int p = IPPORT_RESERVED - 1;
149:
150: sock = rresvport(&p);
151: if (sock < 0)
152: fatal("rresvport: %.100s", strerror(errno));
1.1 deraadt 153: debug("Allocated local port %d.", p);
154: }
155: else
156: {
157: /* Just create an ordinary socket on arbitrary port. We use the
158: user's uid to create the socket. */
159: temporarily_use_uid(original_real_uid);
160: sock = socket(AF_INET, SOCK_STREAM, 0);
161: if (sock < 0)
162: fatal("socket: %.100s", strerror(errno));
163: restore_uid();
164: }
165: return sock;
166: }
167:
168: /* Opens a TCP/IP connection to the remote server on the given host. If
169: port is 0, the default port will be used. If anonymous is zero,
170: a privileged port will be allocated to make the connection.
171: This requires super-user privileges if anonymous is false.
172: Connection_attempts specifies the maximum number of tries (one per
173: second). If proxy_command is non-NULL, it specifies the command (with %h
174: and %p substituted for host and port, respectively) to use to contact
175: the daemon. */
176:
177: int ssh_connect(const char *host, int port, int connection_attempts,
178: int anonymous, uid_t original_real_uid,
1.3 provos 179: const char *proxy_command)
1.1 deraadt 180: {
181: int sock = -1, attempt, i;
182: int on = 1;
183: struct servent *sp;
184: struct hostent *hp;
185: struct sockaddr_in hostaddr;
186: #ifdef SO_LINGER
187: struct linger linger;
188: #endif /* SO_LINGER */
189:
190: debug("ssh_connect: getuid %d geteuid %d anon %d",
191: (int)getuid(), (int)geteuid(), anonymous);
192:
193: /* Get default port if port has not been set. */
194: if (port == 0)
195: {
196: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
197: if (sp)
198: port = ntohs(sp->s_port);
199: else
200: port = SSH_DEFAULT_PORT;
201: }
202:
203: /* If a proxy command is given, connect using it. */
204: if (proxy_command != NULL)
1.3 provos 205: return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
1.1 deraadt 206:
207: /* No proxy command. */
208:
209: /* No host lookup made yet. */
210: hp = NULL;
211:
212: /* Try to connect several times. On some machines, the first time will
213: sometimes fail. In general socket code appears to behave quite
214: magically on many machines. */
215: for (attempt = 0; attempt < connection_attempts; attempt++)
216: {
217: if (attempt > 0)
218: debug("Trying again...");
219:
220: /* Try to parse the host name as a numeric inet address. */
221: memset(&hostaddr, 0, sizeof(hostaddr));
222: hostaddr.sin_family = AF_INET;
223: hostaddr.sin_port = htons(port);
224: #ifdef BROKEN_INET_ADDR
225: hostaddr.sin_addr.s_addr = inet_network(host);
226: #else /* BROKEN_INET_ADDR */
227: hostaddr.sin_addr.s_addr = inet_addr(host);
228: #endif /* BROKEN_INET_ADDR */
229: if ((hostaddr.sin_addr.s_addr & 0xffffffff) != 0xffffffff)
230: {
231: /* Valid numeric IP address */
232: debug("Connecting to %.100s port %d.",
233: inet_ntoa(hostaddr.sin_addr), port);
234:
235: /* Create a socket. */
236: sock = ssh_create_socket(original_real_uid,
237: !anonymous && geteuid() == 0 &&
238: port < 1024);
239:
240: /* Connect to the host. We use the user's uid in the hope that
241: it will help with the problems of tcp_wrappers showing the
242: remote uid as root. */
243: temporarily_use_uid(original_real_uid);
244: if (connect(sock, (struct sockaddr *)&hostaddr, sizeof(hostaddr))
245: >= 0)
246: {
247: /* Successful connect. */
248: restore_uid();
249: break;
250: }
251: debug("connect: %.100s", strerror(errno));
252: restore_uid();
253:
254: /* Destroy the failed socket. */
255: shutdown(sock, 2);
256: close(sock);
257: }
258: else
259: {
260: /* Not a valid numeric inet address. */
261: /* Map host name to an address. */
262: if (!hp)
263: hp = gethostbyname(host);
264: if (!hp)
265: fatal("Bad host name: %.100s", host);
266: if (!hp->h_addr_list[0])
267: fatal("Host does not have an IP address: %.100s", host);
268:
269: /* Loop through addresses for this host, and try each one in
270: sequence until the connection succeeds. */
271: for (i = 0; hp->h_addr_list[i]; i++)
272: {
273: /* Set the address to connect to. */
274: hostaddr.sin_family = hp->h_addrtype;
275: memcpy(&hostaddr.sin_addr, hp->h_addr_list[i],
276: sizeof(hostaddr.sin_addr));
277:
278: debug("Connecting to %.200s [%.100s] port %d.",
279: host, inet_ntoa(hostaddr.sin_addr), port);
280:
281: /* Create a socket for connecting. */
282: sock = ssh_create_socket(original_real_uid,
283: !anonymous && geteuid() == 0 &&
284: port < 1024);
285:
286: /* Connect to the host. We use the user's uid in the hope that
287: it will help with tcp_wrappers showing the remote uid as
288: root. */
289: temporarily_use_uid(original_real_uid);
290: if (connect(sock, (struct sockaddr *)&hostaddr,
291: sizeof(hostaddr)) >= 0)
292: {
293: /* Successful connection. */
294: restore_uid();
295: break;
296: }
297: debug("connect: %.100s", strerror(errno));
298: restore_uid();
299:
300: /* Close the failed socket; there appear to be some problems
301: when reusing a socket for which connect() has already
302: returned an error. */
303: shutdown(sock, 2);
304: close(sock);
305: }
306: if (hp->h_addr_list[i])
307: break; /* Successful connection. */
308: }
309:
310: /* Sleep a moment before retrying. */
311: sleep(1);
312: }
313: /* Return failure if we didn't get a successful connection. */
314: if (attempt >= connection_attempts)
315: return 0;
316:
317: debug("Connection established.");
318:
319: /* Set socket options. We would like the socket to disappear as soon as
320: it has been closed for whatever reason. */
321: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
322: #ifdef TCP_NODELAY
323: setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&on, sizeof(on));
324: #endif /* TCP_NODELAY */
325: #ifdef SO_LINGER
326: linger.l_onoff = 1;
327: linger.l_linger = 5;
328: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
329: #endif /* SO_LINGER */
330:
331: /* Set the connection. */
1.3 provos 332: packet_set_connection(sock, sock);
1.1 deraadt 333:
334: return 1;
335: }
336:
337: /* Checks if the user has an authentication agent, and if so, tries to
338: authenticate using the agent. */
339:
1.3 provos 340: int
341: try_agent_authentication()
1.1 deraadt 342: {
343: int status, type, bits;
344: char *comment;
345: AuthenticationConnection *auth;
346: unsigned char response[16];
347: unsigned int i;
1.3 provos 348: BIGNUM *e, *n, *challenge;
1.1 deraadt 349:
350: /* Get connection to the agent. */
351: auth = ssh_get_authentication_connection();
352: if (!auth)
353: return 0;
354:
1.3 provos 355: e = BN_new();
356: n = BN_new();
357: challenge = BN_new();
1.1 deraadt 358:
359: /* Loop through identities served by the agent. */
1.3 provos 360: for (status = ssh_get_first_identity(auth, &bits, e, n, &comment);
1.1 deraadt 361: status;
1.3 provos 362: status = ssh_get_next_identity(auth, &bits, e, n, &comment))
1.1 deraadt 363: {
364: int plen, clen;
365:
366: /* Try this identity. */
367: debug("Trying RSA authentication via agent with '%.100s'", comment);
368: xfree(comment);
369:
370: /* Tell the server that we are willing to authenticate using this key. */
371: packet_start(SSH_CMSG_AUTH_RSA);
1.3 provos 372: packet_put_bignum(n);
1.1 deraadt 373: packet_send();
374: packet_write_wait();
375:
376: /* Wait for server's response. */
377: type = packet_read(&plen);
378:
379: /* The server sends failure if it doesn\'t like our key or does not
380: support RSA authentication. */
381: if (type == SSH_SMSG_FAILURE)
382: {
383: debug("Server refused our key.");
384: continue;
385: }
386:
387: /* Otherwise it should have sent a challenge. */
388: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
389: packet_disconnect("Protocol error during RSA authentication: %d",
390: type);
391:
1.3 provos 392: packet_get_bignum(challenge, &clen);
1.1 deraadt 393:
394: packet_integrity_check(plen, clen, type);
395:
396: debug("Received RSA challenge from server.");
397:
398: /* Ask the agent to decrypt the challenge. */
1.3 provos 399: if (!ssh_decrypt_challenge(auth, bits, e, n, challenge,
1.1 deraadt 400: session_id, 1, response))
401: {
402: /* The agent failed to authenticate this identifier although it
403: advertised it supports this. Just return a wrong value. */
404: log("Authentication agent failed to decrypt challenge.");
405: memset(response, 0, sizeof(response));
406: }
407:
408: debug("Sending response to RSA challenge.");
409:
410: /* Send the decrypted challenge back to the server. */
411: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
412: for (i = 0; i < 16; i++)
413: packet_put_char(response[i]);
414: packet_send();
415: packet_write_wait();
416:
417: /* Wait for response from the server. */
418: type = packet_read(&plen);
419:
420: /* The server returns success if it accepted the authentication. */
421: if (type == SSH_SMSG_SUCCESS)
422: {
423: debug("RSA authentication accepted by server.");
1.3 provos 424: BN_clear_free(e);
425: BN_clear_free(n);
426: BN_clear_free(challenge);
1.1 deraadt 427: return 1;
428: }
429:
430: /* Otherwise it should return failure. */
431: if (type != SSH_SMSG_FAILURE)
432: packet_disconnect("Protocol error waiting RSA auth response: %d",
433: type);
434: }
435:
1.3 provos 436: BN_clear_free(e);
437: BN_clear_free(n);
438: BN_clear_free(challenge);
1.1 deraadt 439:
440: debug("RSA authentication using agent refused.");
441: return 0;
442: }
443:
444: /* Computes the proper response to a RSA challenge, and sends the response to
445: the server. */
446:
1.3 provos 447: void
448: respond_to_rsa_challenge(BIGNUM *challenge, RSA *prv)
1.1 deraadt 449: {
450: unsigned char buf[32], response[16];
451: struct MD5Context md;
1.3 provos 452: int i, len;
1.1 deraadt 453:
454: /* Decrypt the challenge using the private key. */
455: rsa_private_decrypt(challenge, challenge, prv);
456:
457: /* Compute the response. */
458: /* The response is MD5 of decrypted challenge plus session id. */
1.3 provos 459: len = BN_num_bytes(challenge);
460: assert(len <= sizeof(buf) && len);
461: memset(buf, 0, sizeof(buf));
462: BN_bn2bin(challenge, buf + sizeof(buf) - len);
1.1 deraadt 463: MD5Init(&md);
464: MD5Update(&md, buf, 32);
465: MD5Update(&md, session_id, 16);
466: MD5Final(response, &md);
467:
468: debug("Sending response to host key RSA challenge.");
469:
470: /* Send the response back to the server. */
471: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
472: for (i = 0; i < 16; i++)
473: packet_put_char(response[i]);
474: packet_send();
475: packet_write_wait();
476:
477: memset(buf, 0, sizeof(buf));
478: memset(response, 0, sizeof(response));
479: memset(&md, 0, sizeof(md));
480: }
481:
482: /* Checks if the user has authentication file, and if so, tries to authenticate
483: the user using it. */
484:
1.3 provos 485: int
486: try_rsa_authentication(struct passwd *pw, const char *authfile,
487: int may_ask_passphrase)
1.1 deraadt 488: {
1.3 provos 489: BIGNUM *challenge;
490: RSA *private_key;
491: RSA *public_key;
1.1 deraadt 492: char *passphrase, *comment;
493: int type, i;
494: int plen, clen;
495:
496: /* Try to load identification for the authentication key. */
1.3 provos 497: public_key = RSA_new();
498: if (!load_public_key(authfile, public_key, &comment)) {
499: RSA_free(public_key);
1.1 deraadt 500: return 0; /* Could not load it. Fail. */
1.3 provos 501: }
1.1 deraadt 502:
503: debug("Trying RSA authentication with key '%.100s'", comment);
504:
505: /* Tell the server that we are willing to authenticate using this key. */
506: packet_start(SSH_CMSG_AUTH_RSA);
1.3 provos 507: packet_put_bignum(public_key->n);
1.1 deraadt 508: packet_send();
509: packet_write_wait();
510:
511: /* We no longer need the public key. */
1.3 provos 512: RSA_free(public_key);
1.1 deraadt 513:
514: /* Wait for server's response. */
515: type = packet_read(&plen);
516:
517: /* The server responds with failure if it doesn\'t like our key or doesn\'t
518: support RSA authentication. */
519: if (type == SSH_SMSG_FAILURE)
520: {
521: debug("Server refused our key.");
522: xfree(comment);
523: return 0; /* Server refuses to authenticate with this key. */
524: }
525:
526: /* Otherwise, the server should respond with a challenge. */
527: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
528: packet_disconnect("Protocol error during RSA authentication: %d", type);
529:
530: /* Get the challenge from the packet. */
1.3 provos 531: challenge = BN_new();
532: packet_get_bignum(challenge, &clen);
1.1 deraadt 533:
534: packet_integrity_check(plen, clen, type);
535:
536: debug("Received RSA challenge from server.");
537:
1.3 provos 538: private_key = RSA_new();
1.1 deraadt 539: /* Load the private key. Try first with empty passphrase; if it fails,
540: ask for a passphrase. */
1.3 provos 541: if (!load_private_key(authfile, "", private_key, NULL))
1.1 deraadt 542: {
543: char buf[300];
544: /* Request passphrase from the user. We read from /dev/tty to make
545: this work even if stdin has been redirected. If running in
546: batch mode, we just use the empty passphrase, which will fail and
547: return. */
548: sprintf(buf, "Enter passphrase for RSA key '%.100s': ", comment);
549: if (may_ask_passphrase)
550: passphrase = read_passphrase(buf, 0);
551: else
552: {
553: debug("Will not query passphrase for %.100s in batch mode.",
554: comment);
555: passphrase = xstrdup("");
556: }
557:
558: /* Load the authentication file using the pasphrase. */
1.3 provos 559: if (!load_private_key(authfile, passphrase, private_key, NULL))
1.1 deraadt 560: {
561: memset(passphrase, 0, strlen(passphrase));
562: xfree(passphrase);
563: error("Bad passphrase.");
564:
565: /* Send a dummy response packet to avoid protocol error. */
566: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
567: for (i = 0; i < 16; i++)
568: packet_put_char(0);
569: packet_send();
570: packet_write_wait();
571:
572: /* Expect the server to reject it... */
573: packet_read_expect(&plen, SSH_SMSG_FAILURE);
574: xfree(comment);
575: return 0;
576: }
577:
578: /* Destroy the passphrase. */
579: memset(passphrase, 0, strlen(passphrase));
580: xfree(passphrase);
581: }
582:
583: /* We no longer need the comment. */
584: xfree(comment);
585:
586: /* Compute and send a response to the challenge. */
1.3 provos 587: respond_to_rsa_challenge(challenge, private_key);
1.1 deraadt 588:
589: /* Destroy the private key. */
1.3 provos 590: RSA_free(private_key);
1.1 deraadt 591:
592: /* We no longer need the challenge. */
1.3 provos 593: BN_clear_free(challenge);
1.1 deraadt 594:
595: /* Wait for response from the server. */
596: type = packet_read(&plen);
597: if (type == SSH_SMSG_SUCCESS)
598: {
599: debug("RSA authentication accepted by server.");
600: return 1;
601: }
602: if (type != SSH_SMSG_FAILURE)
603: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
604: debug("RSA authentication refused.");
605: return 0;
606: }
607:
608: /* Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
609: authentication and RSA host authentication. */
610:
1.3 provos 611: int
612: try_rhosts_rsa_authentication(const char *local_user, RSA *host_key)
1.1 deraadt 613: {
614: int type;
1.3 provos 615: BIGNUM *challenge;
1.1 deraadt 616: int plen, clen;
617:
618: debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
619:
620: /* Tell the server that we are willing to authenticate using this key. */
621: packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
622: packet_put_string(local_user, strlen(local_user));
1.3 provos 623: packet_put_int(BN_num_bits(host_key->n));
624: packet_put_bignum(host_key->e);
625: packet_put_bignum(host_key->n);
1.1 deraadt 626: packet_send();
627: packet_write_wait();
628:
629: /* Wait for server's response. */
630: type = packet_read(&plen);
631:
632: /* The server responds with failure if it doesn't admit our .rhosts
633: authentication or doesn't know our host key. */
634: if (type == SSH_SMSG_FAILURE)
635: {
636: debug("Server refused our rhosts authentication or host key.");
637: return 0; /* Server refuses to authenticate us with this method. */
638: }
639:
640: /* Otherwise, the server should respond with a challenge. */
641: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
642: packet_disconnect("Protocol error during RSA authentication: %d", type);
643:
644: /* Get the challenge from the packet. */
1.3 provos 645: challenge = BN_new();
646: packet_get_bignum(challenge, &clen);
1.1 deraadt 647:
648: packet_integrity_check(plen, clen, type);
649:
650: debug("Received RSA challenge for host key from server.");
651:
652: /* Compute a response to the challenge. */
1.3 provos 653: respond_to_rsa_challenge(challenge, host_key);
1.1 deraadt 654:
655: /* We no longer need the challenge. */
1.3 provos 656: BN_clear_free(challenge);
1.1 deraadt 657:
658: /* Wait for response from the server. */
659: type = packet_read(&plen);
660: if (type == SSH_SMSG_SUCCESS)
661: {
662: debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
663: return 1;
664: }
665: if (type != SSH_SMSG_FAILURE)
666: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
667: debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
668: return 0;
669: }
670:
671: #ifdef KRB4
672: int try_kerberos_authentication()
673: {
674: KTEXT_ST auth; /* Kerberos data */
675: char *reply;
676: char inst[INST_SZ];
677: char *realm;
678: CREDENTIALS cred;
1.5 ! dugsong 679: int r, type, plen;
1.1 deraadt 680: Key_schedule schedule;
681: u_long checksum, cksum;
682: MSG_DAT msg_data;
683: struct sockaddr_in local, foreign;
684: struct stat st;
685:
686: /* Don't do anything if we don't have any tickets. */
687: if (stat(tkt_string(), &st) < 0) return 0;
688:
689: strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
690:
691: realm = (char *)krb_realmofhost(get_canonical_hostname());
692: if (!realm) {
1.5 ! dugsong 693: debug("Kerberos V4: no realm for %s", get_canonical_hostname());
1.1 deraadt 694: return 0;
695: }
696: /* This can really be anything. */
697: checksum = (u_long) getpid();
698:
699: r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
700: if (r != KSUCCESS) {
1.5 ! dugsong 701: debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]);
1.1 deraadt 702: return 0;
703: }
704: /* Get session key to decrypt the server's reply with. */
705: r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
706: if (r != KSUCCESS) {
1.5 ! dugsong 707: debug("get_cred failed: %s", krb_err_txt[r]);
1.1 deraadt 708: return 0;
709: }
710: des_key_sched((des_cblock *)cred.session, schedule);
711:
712: /* Send authentication info to server. */
713: packet_start(SSH_CMSG_AUTH_KERBEROS);
714: packet_put_string((char *)auth.dat, auth.length);
715: packet_send();
716: packet_write_wait();
717:
1.5 ! dugsong 718: /* Zero the buffer. */
1.1 deraadt 719: (void) memset(auth.dat, 0, MAX_KTXT_LEN);
720:
721: r = sizeof(local);
722: memset(&local, 0, sizeof(local));
723: if (getsockname(packet_get_connection_in(),
724: (struct sockaddr *) &local, &r) < 0)
1.5 ! dugsong 725: debug("getsockname failed: %s", strerror(errno));
1.1 deraadt 726:
727: r = sizeof(foreign);
728: memset(&foreign, 0, sizeof(foreign));
729: if (getpeername(packet_get_connection_in(),
730: (struct sockaddr *)&foreign, &r) < 0)
1.5 ! dugsong 731: debug("getpeername failed: %s", strerror(errno));
1.1 deraadt 732:
733: /* Get server reply. */
734: type = packet_read(&plen);
735: switch(type) {
736:
737: case SSH_SMSG_FAILURE: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
738: debug("Kerberos V4 authentication failed.");
739: return 0;
740: break;
741:
742: case SSH_SMSG_AUTH_KERBEROS_RESPONSE: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
743: debug("Kerberos V4 authentication accepted.");
744:
745: /* Get server's response. */
746: reply = packet_get_string((unsigned int *)&auth.length);
747: memcpy(auth.dat, reply, auth.length);
748: xfree(reply);
749:
750: packet_integrity_check(plen, 4 + auth.length, type);
751:
752: /* If his response isn't properly encrypted with the session key,
753: and the decrypted checksum fails to match, he's bogus. Bail out. */
754: r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
755: &foreign, &local, &msg_data);
756: if (r != KSUCCESS) {
1.5 ! dugsong 757: debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]);
1.1 deraadt 758: packet_disconnect("Kerberos V4 challenge failed!");
759: }
1.5 ! dugsong 760: /* Fetch the (incremented) checksum that we supplied in the request. */
1.1 deraadt 761: (void)memcpy((char *)&cksum, (char *)msg_data.app_data, sizeof(cksum));
762: cksum = ntohl(cksum);
763:
764: /* If it matches, we're golden. */
765: if (cksum == checksum + 1) {
766: debug("Kerberos V4 challenge successful.");
767: return 1;
768: }
769: else
770: packet_disconnect("Kerberos V4 challenge failed!");
771: break;
772:
773: default:
774: packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
775: }
776: return 0;
777: }
778: #endif /* KRB4 */
779:
780: #ifdef AFS
781: int send_kerberos_tgt()
782: {
783: CREDENTIALS *creds;
784: char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
1.5 ! dugsong 785: int r, type, plen;
1.1 deraadt 786: unsigned char buffer[8192];
787: struct stat st;
788:
789: /* Don't do anything if we don't have any tickets. */
790: if (stat(tkt_string(), &st) < 0) return 0;
791:
1.5 ! dugsong 792: creds = xmalloc(sizeof(*creds));
1.1 deraadt 793:
1.5 ! dugsong 794: if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) {
! 795: debug("Kerberos V4 tf_fullname failed: %s",krb_err_txt[r]);
1.1 deraadt 796: return 0;
1.5 ! dugsong 797: }
! 798: if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
! 799: debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]);
1.1 deraadt 800: return 0;
801: }
802: if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
1.5 ! dugsong 803: debug("Kerberos V4 ticket expired: %s", TKT_FILE);
1.1 deraadt 804: return 0;
805: }
806:
807: creds_to_radix(creds, buffer);
808: xfree(creds);
809:
810: packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
811: packet_put_string((char *)buffer, strlen(buffer));
812: packet_send();
813: packet_write_wait();
814:
815: type = packet_read(&plen);
1.5 ! dugsong 816:
1.1 deraadt 817: if (type == SSH_SMSG_FAILURE)
1.5 ! dugsong 818: debug("Kerberos TGT for realm %s rejected.", prealm);
1.1 deraadt 819: else if (type != SSH_SMSG_SUCCESS)
820: packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
821:
822: return 1;
823: }
824:
825: void send_afs_tokens(void)
826: {
827: CREDENTIALS creds;
828: struct ViceIoctl parms;
829: struct ClearToken ct;
1.5 ! dugsong 830: int i, type, len, plen;
1.1 deraadt 831: char buf[2048], *p, *server_cell;
832: unsigned char buffer[8192];
833:
834: /* Move over ktc_GetToken, here's something leaner. */
835: for (i = 0; i < 100; i++) { /* just in case */
836: parms.in = (char *)&i;
837: parms.in_size = sizeof(i);
838: parms.out = buf;
839: parms.out_size = sizeof(buf);
840: if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) break;
841: p = buf;
842:
843: /* Get secret token. */
844: memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
845: if (creds.ticket_st.length > MAX_KTXT_LEN) break;
846: p += sizeof(unsigned int);
847: memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
848: p += creds.ticket_st.length;
849:
850: /* Get clear token. */
851: memcpy(&len, p, sizeof(len));
852: if (len != sizeof(struct ClearToken)) break;
853: p += sizeof(len);
854: memcpy(&ct, p, len);
855: p += len;
856: p += sizeof(len); /* primary flag */
857: server_cell = p;
858:
859: /* Flesh out our credentials. */
860: strcpy(creds.service, "afs");
861: creds.instance[0] = '\0';
862: strncpy(creds.realm, server_cell, REALM_SZ);
863: memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
864: creds.issue_date = ct.BeginTimestamp;
865: creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
866: creds.kvno = ct.AuthHandle;
1.5 ! dugsong 867: snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId);
1.1 deraadt 868: creds.pinst[0] = '\0';
869:
870: /* Encode token, ship it off. */
871: if (!creds_to_radix(&creds, buffer)) break;
872: packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
873: packet_put_string((char *)buffer, strlen(buffer));
874: packet_send();
875: packet_write_wait();
876:
877: /* Roger, Roger. Clearance, Clarence. What's your vector, Victor? */
878: type = packet_read(&plen);
879:
880: if (type == SSH_SMSG_FAILURE)
1.5 ! dugsong 881: debug("AFS token for cell %s rejected.", server_cell);
1.1 deraadt 882: else if (type != SSH_SMSG_SUCCESS)
883: packet_disconnect("Protocol error on AFS token response: %d", type);
884: }
885: }
886: #endif /* AFS */
887:
888: /* Waits for the server identification string, and sends our own identification
889: string. */
890:
891: void ssh_exchange_identification()
892: {
893: char buf[256], remote_version[256]; /* must be same size! */
894: int remote_major, remote_minor, i;
895: int connection_in = packet_get_connection_in();
896: int connection_out = packet_get_connection_out();
897:
898: /* Read other side\'s version identification. */
899: for (i = 0; i < sizeof(buf) - 1; i++)
900: {
901: if (read(connection_in, &buf[i], 1) != 1)
902: fatal("read: %.100s", strerror(errno));
903: if (buf[i] == '\r')
904: {
905: buf[i] = '\n';
906: buf[i + 1] = 0;
907: break;
908: }
909: if (buf[i] == '\n')
910: {
911: buf[i + 1] = 0;
912: break;
913: }
914: }
915: buf[sizeof(buf) - 1] = 0;
916:
917: /* Check that the versions match. In future this might accept several
918: versions and set appropriate flags to handle them. */
919: if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor,
920: remote_version) != 3)
921: fatal("Bad remote protocol version identification: '%.100s'", buf);
922: debug("Remote protocol version %d.%d, remote software version %.100s",
923: remote_major, remote_minor, remote_version);
924: #if 0
925: /* Removed for now, to permit compatibility with latter versions. The server
926: will reject our version and disconnect if it doesn't support it. */
927: if (remote_major != PROTOCOL_MAJOR)
928: fatal("Protocol major versions differ: %d vs. %d",
929: PROTOCOL_MAJOR, remote_major);
930: #endif
931:
932: /* Check if the remote protocol version is too old. */
933: if (remote_major == 1 && remote_minor == 0)
934: fatal("Remote machine has too old SSH software version.");
935:
936: /* Send our own protocol version identification. */
937: sprintf(buf, "SSH-%d.%d-%.100s\n",
938: PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
939: if (write(connection_out, buf, strlen(buf)) != strlen(buf))
940: fatal("write: %.100s", strerror(errno));
941: }
942:
943: int ssh_cipher_default = SSH_CIPHER_3DES;
944:
945: int read_yes_or_no(const char *prompt, int defval)
946: {
947: char buf[1024];
948: FILE *f;
949: int retval = -1;
950:
951: if (isatty(0))
952: f = stdin;
953: else
954: f = fopen("/dev/tty", "rw");
955:
956: if (f == NULL)
957: return 0;
958:
959: fflush(stdout);
960:
961: while (1)
962: {
963: fprintf(stderr, "%s", prompt);
964: if (fgets(buf, sizeof(buf), f) == NULL)
965: {
966: /* Print a newline (the prompt probably didn\'t have one). */
967: fprintf(stderr, "\n");
968: strcpy(buf, "no");
969: }
970: /* Remove newline from response. */
971: if (strchr(buf, '\n'))
972: *strchr(buf, '\n') = 0;
973:
974: if (buf[0] == 0)
975: retval = defval;
976: if (strcmp(buf, "yes") == 0)
977: retval = 1;
978: if (strcmp(buf, "no") == 0)
979: retval = 0;
980:
981: if (retval != -1)
982: {
983: if (f != stdin)
984: fclose(f);
985: return retval;
986: }
987: }
988: }
989:
990: /* Starts a dialog with the server, and authenticates the current user on the
991: server. This does not need any extra privileges. The basic connection
992: to the server must already have been established before this is called.
993: User is the remote user; if it is NULL, the current local user name will
994: be used. Anonymous indicates that no rhosts authentication will be used.
995: If login fails, this function prints an error and never returns.
996: This function does not require super-user privileges. */
997:
1.3 provos 998: void ssh_login(int host_key_valid,
999: RSA *own_host_key,
1.1 deraadt 1000: const char *orighost,
1001: Options *options, uid_t original_real_uid)
1002: {
1003: int i, type;
1004: char *password;
1005: struct passwd *pw;
1.3 provos 1006: BIGNUM *key;
1007: RSA *host_key;
1008: RSA *public_key;
1.1 deraadt 1009: unsigned char session_key[SSH_SESSION_KEY_LENGTH];
1010: const char *server_user, *local_user;
1011: char *cp, *host;
1012: unsigned char check_bytes[8];
1013: unsigned int supported_ciphers, supported_authentications, protocol_flags;
1014: HostStatus host_status;
1015: int payload_len, clen, sum_len = 0;
1.5 ! dugsong 1016: u_int32_t rand = 0;
1.1 deraadt 1017:
1018: /* Convert the user-supplied hostname into all lowercase. */
1019: host = xstrdup(orighost);
1020: for (cp = host; *cp; cp++)
1021: if (isupper(*cp))
1022: *cp = tolower(*cp);
1023:
1024: /* Exchange protocol version identification strings with the server. */
1025: ssh_exchange_identification();
1026:
1027: /* Put the connection into non-blocking mode. */
1028: packet_set_nonblocking();
1029:
1030: /* Get local user name. Use it as server user if no user name
1031: was given. */
1032: pw = getpwuid(original_real_uid);
1033: if (!pw)
1034: fatal("User id %d not found from user database.", original_real_uid);
1035: local_user = xstrdup(pw->pw_name);
1036: server_user = options->user ? options->user : local_user;
1037:
1038: debug("Waiting for server public key.");
1039:
1040: /* Wait for a public key packet from the server. */
1041: packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
1042:
1043: /* Get check bytes from the packet. */
1044: for (i = 0; i < 8; i++)
1045: check_bytes[i] = packet_get_char();
1046:
1047: /* Get the public key. */
1.3 provos 1048: public_key = RSA_new();
1049: packet_get_int(); /* bits */
1050: public_key->e = BN_new();
1051: packet_get_bignum(public_key->e, &clen);
1.1 deraadt 1052: sum_len += clen;
1.3 provos 1053: public_key->n = BN_new();
1054: packet_get_bignum(public_key->n, &clen);
1.1 deraadt 1055: sum_len += clen;
1056:
1057: /* Get the host key. */
1.3 provos 1058: host_key = RSA_new();
1059: packet_get_int(); /* bits */
1060: host_key->e = BN_new();
1061: packet_get_bignum(host_key->e, &clen);
1.1 deraadt 1062: sum_len += clen;
1.3 provos 1063: host_key->n = BN_new();
1064: packet_get_bignum(host_key->n, &clen);
1.1 deraadt 1065: sum_len += clen;
1066:
1067: /* Get protocol flags. */
1068: protocol_flags = packet_get_int();
1069: packet_set_protocol_flags(protocol_flags);
1070:
1071: /* Get supported cipher types. */
1072: supported_ciphers = packet_get_int();
1073:
1074: /* Get supported authentication types. */
1075: supported_authentications = packet_get_int();
1076:
1077: debug("Received server public key (%d bits) and host key (%d bits).",
1.3 provos 1078: BN_num_bits(public_key->n), BN_num_bits(host_key->n));
1.1 deraadt 1079:
1080: packet_integrity_check(payload_len,
1081: 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
1082: SSH_SMSG_PUBLIC_KEY);
1083:
1084: /* Compute the session id. */
1.3 provos 1085: compute_session_id(session_id, check_bytes,
1086: BN_num_bits(host_key->n), host_key->n,
1087: BN_num_bits(public_key->n), public_key->n);
1.1 deraadt 1088:
1089: /* Check if the host key is present in the user\'s list of known hosts
1090: or in the systemwide list. */
1091: host_status = check_host_in_hostfile(options->user_hostfile,
1.3 provos 1092: host, BN_num_bits(host_key->n),
1093: host_key->e, host_key->n);
1.1 deraadt 1094: if (host_status == HOST_NEW)
1095: host_status = check_host_in_hostfile(options->system_hostfile, host,
1.3 provos 1096: BN_num_bits(host_key->n),
1097: host_key->e, host_key->n);
1.1 deraadt 1098:
1099: /* Force accepting of the host key for localhost and 127.0.0.1.
1100: The problem is that if the home directory is NFS-mounted to multiple
1101: machines, localhost will refer to a different machine in each of them,
1102: and the user will get bogus HOST_CHANGED warnings. This essentially
1103: disables host authentication for localhost; however, this is probably
1104: not a real problem. */
1105: if (strcmp(host, "localhost") == 0 ||
1106: strcmp(host, "127.0.0.1") == 0)
1107: {
1108: debug("Forcing accepting of host key for localhost.");
1109: host_status = HOST_OK;
1110: }
1111:
1112: switch (host_status)
1113: {
1114: case HOST_OK:
1115: /* The host is known and the key matches. */
1116: debug("Host '%.200s' is known and matches the host key.", host);
1117: break;
1118: case HOST_NEW:
1119: /* The host is new. */
1120: if (options->strict_host_key_checking == 1)
1121: { /* User has requested strict host key checking. We will not
1122: add the host key automatically. The only alternative left
1123: is to abort. */
1124: fatal("No host key is known for %.200s and you have requested strict checking.", host);
1125: }
1126: else if (options->strict_host_key_checking == 2) /* The default */
1127: {
1128: char prompt[1024];
1129: sprintf(prompt,
1130: "The authenticity of host '%.200s' can't be established.\n"
1131: "Are you sure you want to continue connecting (yes/no)? ",
1132: host);
1133: if (!read_yes_or_no(prompt, -1))
1134: fatal("Aborted by user!\n");
1135: }
1136: /* If not in strict mode, add the key automatically to the local
1137: known_hosts file. */
1.3 provos 1138: if (!add_host_to_hostfile(options->user_hostfile, host,
1139: BN_num_bits(host_key->n),
1140: host_key->e, host_key->n))
1.1 deraadt 1141: log("Failed to add the host to the list of known hosts (%.500s).",
1142: options->user_hostfile);
1143: else
1144: log("Warning: Permanently added host '%.200s' to the list of known hosts.", host);
1145: break;
1146: case HOST_CHANGED:
1147: /* The host key has changed. */
1148: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1149: error("@ WARNING: HOST IDENTIFICATION HAS CHANGED! @");
1150: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1151: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1152: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1153: error("It is also possible that the host key has just been changed.");
1154: error("Please contact your system administrator.");
1155: error("Add correct host key in %.100s to get rid of this message.",
1156: options->user_hostfile);
1157:
1158: /* If strict host key checking is in use, the user will have to edit
1159: the key manually and we can only abort. */
1160: if (options->strict_host_key_checking)
1161: fatal("Host key for %.200s has changed and you have requested strict checking.", host);
1162:
1163: /* If strict host key checking has not been requested, allow the
1164: connection but without password authentication. */
1165: error("Password authentication is disabled to avoid trojan horses.");
1166: options->password_authentication = 0;
1167: /* XXX Should permit the user to change to use the new id. This could
1168: be done by converting the host key to an identifying sentence, tell
1169: that the host identifies itself by that sentence, and ask the user
1170: if he/she whishes to accept the authentication. */
1171: break;
1172: }
1173:
1174: /* Generate a session key. */
1.3 provos 1175: arc4random_stir();
1.1 deraadt 1176:
1177: /* Generate an encryption key for the session. The key is a 256 bit
1178: random number, interpreted as a 32-byte key, with the least significant
1179: 8 bits being the first byte of the key. */
1.3 provos 1180: for (i = 0; i < 32; i++) {
1181: if (i % 4 == 0)
1182: rand = arc4random();
1183: session_key[i] = rand & 0xff;
1184: rand >>= 8;
1185: }
1.1 deraadt 1186:
1187: /* According to the protocol spec, the first byte of the session key is
1188: the highest byte of the integer. The session key is xored with the
1189: first 16 bytes of the session id. */
1.3 provos 1190: key = BN_new();
1191: BN_set_word(key, 0);
1.1 deraadt 1192: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++)
1193: {
1.3 provos 1194: BN_lshift(key, key, 8);
1.1 deraadt 1195: if (i < 16)
1.3 provos 1196: BN_add_word(key, session_key[i] ^ session_id[i]);
1.1 deraadt 1197: else
1.3 provos 1198: BN_add_word(key, session_key[i]);
1.1 deraadt 1199: }
1200:
1201: /* Encrypt the integer using the public key and host key of the server
1202: (key with smaller modulus first). */
1.3 provos 1203: if (BN_cmp(public_key->n, host_key->n) < 0)
1.1 deraadt 1204: {
1205: /* Public key has smaller modulus. */
1.3 provos 1206: assert(BN_num_bits(host_key->n) >=
1207: BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED);
1.1 deraadt 1208:
1.3 provos 1209: rsa_public_encrypt(key, key, public_key);
1210: rsa_public_encrypt(key, key, host_key);
1.1 deraadt 1211: }
1212: else
1213: {
1214: /* Host key has smaller modulus (or they are equal). */
1.3 provos 1215: assert(BN_num_bits(public_key->n) >=
1216: BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED);
1.1 deraadt 1217:
1.3 provos 1218: rsa_public_encrypt(key, key, host_key);
1219: rsa_public_encrypt(key, key, public_key);
1.1 deraadt 1220: }
1221:
1.3 provos 1222: if (options->cipher == SSH_CIPHER_NOT_SET) {
1.1 deraadt 1223: if (cipher_mask() & supported_ciphers & (1 << ssh_cipher_default))
1224: options->cipher = ssh_cipher_default;
1.3 provos 1225: else {
1226: debug("Cipher %d not supported, using %.100s instead.",
1227: cipher_name(ssh_cipher_default),
1228: cipher_name(SSH_FALLBACK_CIPHER));
1229: options->cipher = SSH_FALLBACK_CIPHER;
1230: }
1231: }
1.1 deraadt 1232:
1233: /* Check that the selected cipher is supported. */
1234: if (!(supported_ciphers & (1 << options->cipher)))
1235: fatal("Selected cipher type %.100s not supported by server.",
1236: cipher_name(options->cipher));
1237:
1238: debug("Encryption type: %.100s", cipher_name(options->cipher));
1239:
1240: /* Send the encrypted session key to the server. */
1241: packet_start(SSH_CMSG_SESSION_KEY);
1242: packet_put_char(options->cipher);
1243:
1244: /* Send the check bytes back to the server. */
1245: for (i = 0; i < 8; i++)
1246: packet_put_char(check_bytes[i]);
1247:
1248: /* Send the encrypted encryption key. */
1.3 provos 1249: packet_put_bignum(key);
1.1 deraadt 1250:
1251: /* Send protocol flags. */
1252: packet_put_int(SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1253:
1254: /* Send the packet now. */
1255: packet_send();
1256: packet_write_wait();
1257:
1258: /* Destroy the session key integer and the public keys since we no longer
1259: need them. */
1.3 provos 1260: BN_clear_free(key);
1261: RSA_free(public_key);
1262: RSA_free(host_key);
1.1 deraadt 1263:
1264: debug("Sent encrypted session key.");
1265:
1266: /* Set the encryption key. */
1267: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH,
1268: options->cipher, 1);
1269:
1270: /* We will no longer need the session key here. Destroy any extra copies. */
1271: memset(session_key, 0, sizeof(session_key));
1272:
1273: /* Expect a success message from the server. Note that this message will
1274: be received in encrypted form. */
1275: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1276:
1277: debug("Received encrypted confirmation.");
1278:
1279: /* Send the name of the user to log in as on the server. */
1280: packet_start(SSH_CMSG_USER);
1281: packet_put_string(server_user, strlen(server_user));
1282: packet_send();
1283: packet_write_wait();
1284:
1285: /* The server should respond with success if no authentication is needed
1286: (the user has no password). Otherwise the server responds with
1287: failure. */
1288: type = packet_read(&payload_len);
1289: if (type == SSH_SMSG_SUCCESS)
1290: return; /* Connection was accepted without authentication. */
1291: if (type != SSH_SMSG_FAILURE)
1292: packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
1293: type);
1294:
1.5 ! dugsong 1295: #ifdef AFS
1.1 deraadt 1296: /* Try Kerberos tgt passing if the server supports it. */
1297: if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
1.5 ! dugsong 1298: options->kerberos_tgt_passing)
! 1299: {
! 1300: if (options->cipher == SSH_CIPHER_NONE)
! 1301: log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
! 1302: (void)send_kerberos_tgt();
! 1303: }
! 1304:
1.1 deraadt 1305: /* Try AFS token passing if the server supports it. */
1306: if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
1307: options->afs_token_passing && k_hasafs()) {
1308: if (options->cipher == SSH_CIPHER_NONE)
1309: log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
1310: send_afs_tokens();
1311: }
1312: #endif /* AFS */
1313:
1.5 ! dugsong 1314: #ifdef KRB4
1.1 deraadt 1315: if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
1316: options->kerberos_authentication)
1317: {
1.5 ! dugsong 1318: debug("Trying Kerberos authentication.");
1.1 deraadt 1319: if (try_kerberos_authentication()) {
1320: /* The server should respond with success or failure. */
1321: type = packet_read(&payload_len);
1322: if (type == SSH_SMSG_SUCCESS)
1323: return; /* Successful connection. */
1324: if (type != SSH_SMSG_FAILURE)
1325: packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
1326: }
1327: }
1328: #endif /* KRB4 */
1329:
1330: /* Use rhosts authentication if running in privileged socket and we do not
1331: wish to remain anonymous. */
1332: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
1333: options->rhosts_authentication)
1334: {
1335: debug("Trying rhosts authentication.");
1336: packet_start(SSH_CMSG_AUTH_RHOSTS);
1337: packet_put_string(local_user, strlen(local_user));
1338: packet_send();
1339: packet_write_wait();
1340:
1341: /* The server should respond with success or failure. */
1342: type = packet_read(&payload_len);
1343: if (type == SSH_SMSG_SUCCESS)
1344: return; /* Successful connection. */
1345: if (type != SSH_SMSG_FAILURE)
1346: packet_disconnect("Protocol error: got %d in response to rhosts auth",
1347: type);
1348: }
1349:
1350: /* Try .rhosts or /etc/hosts.equiv authentication with RSA host
1351: authentication. */
1352: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
1353: options->rhosts_rsa_authentication && host_key_valid)
1354: {
1355: if (try_rhosts_rsa_authentication(local_user, own_host_key))
1356: return; /* Successful authentication. */
1357: }
1358:
1359: /* Try RSA authentication if the server supports it. */
1360: if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
1361: options->rsa_authentication)
1362: {
1363: /* Try RSA authentication using the authentication agent. The agent
1364: is tried first because no passphrase is needed for it, whereas
1365: identity files may require passphrases. */
1366: if (try_agent_authentication())
1367: return; /* Successful connection. */
1368:
1369: /* Try RSA authentication for each identity. */
1370: for (i = 0; i < options->num_identity_files; i++)
1371: if (try_rsa_authentication(pw, options->identity_files[i],
1372: !options->batch_mode))
1373: return; /* Successful connection. */
1374: }
1375:
1376: /* Try password authentication if the server supports it. */
1377: if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
1378: options->password_authentication && !options->batch_mode)
1379: {
1.4 provos 1380: char prompt[80];
1381: snprintf(prompt, sizeof(prompt), "%.30s@%.30s's password: ",
1382: server_user, host);
1.1 deraadt 1383: debug("Doing password authentication.");
1384: if (options->cipher == SSH_CIPHER_NONE)
1385: log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
1.4 provos 1386: password = read_passphrase(prompt, 0);
1.1 deraadt 1387: packet_start(SSH_CMSG_AUTH_PASSWORD);
1388: packet_put_string(password, strlen(password));
1389: memset(password, 0, strlen(password));
1390: xfree(password);
1391: packet_send();
1392: packet_write_wait();
1393:
1394: type = packet_read(&payload_len);
1395: if (type == SSH_SMSG_SUCCESS)
1396: return; /* Successful connection. */
1397: if (type != SSH_SMSG_FAILURE)
1398: packet_disconnect("Protocol error: got %d in response to passwd auth",
1399: type);
1400: }
1401:
1402: /* All authentication methods have failed. Exit with an error message. */
1403: fatal("Permission denied.");
1404: /*NOTREACHED*/
1405: }
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