Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.9
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"
1.9 ! deraadt 18: RCSID("$Id: sshconnect.c,v 1.8 1999/09/30 05:53:04 deraadt 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. */
1.6 deraadt 48: snprintf(portstring, sizeof portstring, "%d", port);
1.1 deraadt 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: struct linger linger;
187:
188: debug("ssh_connect: getuid %d geteuid %d anon %d",
189: (int)getuid(), (int)geteuid(), anonymous);
190:
191: /* Get default port if port has not been set. */
192: if (port == 0)
193: {
194: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
195: if (sp)
196: port = ntohs(sp->s_port);
197: else
198: port = SSH_DEFAULT_PORT;
199: }
200:
201: /* If a proxy command is given, connect using it. */
202: if (proxy_command != NULL)
1.3 provos 203: return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
1.1 deraadt 204:
205: /* No proxy command. */
206:
207: /* No host lookup made yet. */
208: hp = NULL;
209:
210: /* Try to connect several times. On some machines, the first time will
211: sometimes fail. In general socket code appears to behave quite
212: magically on many machines. */
213: for (attempt = 0; attempt < connection_attempts; attempt++)
214: {
215: if (attempt > 0)
216: debug("Trying again...");
217:
218: /* Try to parse the host name as a numeric inet address. */
219: memset(&hostaddr, 0, sizeof(hostaddr));
220: hostaddr.sin_family = AF_INET;
221: hostaddr.sin_port = htons(port);
222: hostaddr.sin_addr.s_addr = inet_addr(host);
223: if ((hostaddr.sin_addr.s_addr & 0xffffffff) != 0xffffffff)
224: {
225: /* Valid numeric IP address */
226: debug("Connecting to %.100s port %d.",
227: inet_ntoa(hostaddr.sin_addr), port);
228:
229: /* Create a socket. */
230: sock = ssh_create_socket(original_real_uid,
231: !anonymous && geteuid() == 0 &&
1.9 ! deraadt 232: port < IPPORT_RESERVED);
1.1 deraadt 233:
234: /* Connect to the host. We use the user's uid in the hope that
235: it will help with the problems of tcp_wrappers showing the
236: remote uid as root. */
237: temporarily_use_uid(original_real_uid);
238: if (connect(sock, (struct sockaddr *)&hostaddr, sizeof(hostaddr))
239: >= 0)
240: {
241: /* Successful connect. */
242: restore_uid();
243: break;
244: }
245: debug("connect: %.100s", strerror(errno));
246: restore_uid();
247:
248: /* Destroy the failed socket. */
249: shutdown(sock, 2);
250: close(sock);
251: }
252: else
253: {
254: /* Not a valid numeric inet address. */
255: /* Map host name to an address. */
256: if (!hp)
257: hp = gethostbyname(host);
258: if (!hp)
259: fatal("Bad host name: %.100s", host);
260: if (!hp->h_addr_list[0])
261: fatal("Host does not have an IP address: %.100s", host);
262:
263: /* Loop through addresses for this host, and try each one in
264: sequence until the connection succeeds. */
265: for (i = 0; hp->h_addr_list[i]; i++)
266: {
267: /* Set the address to connect to. */
268: hostaddr.sin_family = hp->h_addrtype;
269: memcpy(&hostaddr.sin_addr, hp->h_addr_list[i],
270: sizeof(hostaddr.sin_addr));
271:
272: debug("Connecting to %.200s [%.100s] port %d.",
273: host, inet_ntoa(hostaddr.sin_addr), port);
274:
275: /* Create a socket for connecting. */
276: sock = ssh_create_socket(original_real_uid,
277: !anonymous && geteuid() == 0 &&
1.9 ! deraadt 278: port < IPPORT_RESERVED);
1.1 deraadt 279:
280: /* Connect to the host. We use the user's uid in the hope that
281: it will help with tcp_wrappers showing the remote uid as
282: root. */
283: temporarily_use_uid(original_real_uid);
284: if (connect(sock, (struct sockaddr *)&hostaddr,
285: sizeof(hostaddr)) >= 0)
286: {
287: /* Successful connection. */
288: restore_uid();
289: break;
290: }
291: debug("connect: %.100s", strerror(errno));
292: restore_uid();
293:
294: /* Close the failed socket; there appear to be some problems
295: when reusing a socket for which connect() has already
296: returned an error. */
297: shutdown(sock, 2);
298: close(sock);
299: }
300: if (hp->h_addr_list[i])
301: break; /* Successful connection. */
302: }
303:
304: /* Sleep a moment before retrying. */
305: sleep(1);
306: }
307: /* Return failure if we didn't get a successful connection. */
308: if (attempt >= connection_attempts)
309: return 0;
310:
311: debug("Connection established.");
312:
313: /* Set socket options. We would like the socket to disappear as soon as
314: it has been closed for whatever reason. */
315: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
316: setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&on, sizeof(on));
317: linger.l_onoff = 1;
318: linger.l_linger = 5;
319: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
320:
321: /* Set the connection. */
1.3 provos 322: packet_set_connection(sock, sock);
1.1 deraadt 323:
324: return 1;
325: }
326:
327: /* Checks if the user has an authentication agent, and if so, tries to
328: authenticate using the agent. */
329:
1.3 provos 330: int
331: try_agent_authentication()
1.1 deraadt 332: {
333: int status, type, bits;
334: char *comment;
335: AuthenticationConnection *auth;
336: unsigned char response[16];
337: unsigned int i;
1.3 provos 338: BIGNUM *e, *n, *challenge;
1.1 deraadt 339:
340: /* Get connection to the agent. */
341: auth = ssh_get_authentication_connection();
342: if (!auth)
343: return 0;
344:
1.3 provos 345: e = BN_new();
346: n = BN_new();
347: challenge = BN_new();
1.1 deraadt 348:
349: /* Loop through identities served by the agent. */
1.3 provos 350: for (status = ssh_get_first_identity(auth, &bits, e, n, &comment);
1.1 deraadt 351: status;
1.3 provos 352: status = ssh_get_next_identity(auth, &bits, e, n, &comment))
1.1 deraadt 353: {
354: int plen, clen;
355:
356: /* Try this identity. */
357: debug("Trying RSA authentication via agent with '%.100s'", comment);
358: xfree(comment);
359:
360: /* Tell the server that we are willing to authenticate using this key. */
361: packet_start(SSH_CMSG_AUTH_RSA);
1.3 provos 362: packet_put_bignum(n);
1.1 deraadt 363: packet_send();
364: packet_write_wait();
365:
366: /* Wait for server's response. */
367: type = packet_read(&plen);
368:
369: /* The server sends failure if it doesn\'t like our key or does not
370: support RSA authentication. */
371: if (type == SSH_SMSG_FAILURE)
372: {
373: debug("Server refused our key.");
374: continue;
375: }
376:
377: /* Otherwise it should have sent a challenge. */
378: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
379: packet_disconnect("Protocol error during RSA authentication: %d",
380: type);
381:
1.3 provos 382: packet_get_bignum(challenge, &clen);
1.1 deraadt 383:
384: packet_integrity_check(plen, clen, type);
385:
386: debug("Received RSA challenge from server.");
387:
388: /* Ask the agent to decrypt the challenge. */
1.3 provos 389: if (!ssh_decrypt_challenge(auth, bits, e, n, challenge,
1.1 deraadt 390: session_id, 1, response))
391: {
392: /* The agent failed to authenticate this identifier although it
393: advertised it supports this. Just return a wrong value. */
394: log("Authentication agent failed to decrypt challenge.");
395: memset(response, 0, sizeof(response));
396: }
397:
398: debug("Sending response to RSA challenge.");
399:
400: /* Send the decrypted challenge back to the server. */
401: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
402: for (i = 0; i < 16; i++)
403: packet_put_char(response[i]);
404: packet_send();
405: packet_write_wait();
406:
407: /* Wait for response from the server. */
408: type = packet_read(&plen);
409:
410: /* The server returns success if it accepted the authentication. */
411: if (type == SSH_SMSG_SUCCESS)
412: {
413: debug("RSA authentication accepted by server.");
1.3 provos 414: BN_clear_free(e);
415: BN_clear_free(n);
416: BN_clear_free(challenge);
1.1 deraadt 417: return 1;
418: }
419:
420: /* Otherwise it should return failure. */
421: if (type != SSH_SMSG_FAILURE)
422: packet_disconnect("Protocol error waiting RSA auth response: %d",
423: type);
424: }
425:
1.3 provos 426: BN_clear_free(e);
427: BN_clear_free(n);
428: BN_clear_free(challenge);
1.1 deraadt 429:
430: debug("RSA authentication using agent refused.");
431: return 0;
432: }
433:
434: /* Computes the proper response to a RSA challenge, and sends the response to
435: the server. */
436:
1.3 provos 437: void
438: respond_to_rsa_challenge(BIGNUM *challenge, RSA *prv)
1.1 deraadt 439: {
440: unsigned char buf[32], response[16];
441: struct MD5Context md;
1.3 provos 442: int i, len;
1.1 deraadt 443:
444: /* Decrypt the challenge using the private key. */
445: rsa_private_decrypt(challenge, challenge, prv);
446:
447: /* Compute the response. */
448: /* The response is MD5 of decrypted challenge plus session id. */
1.3 provos 449: len = BN_num_bytes(challenge);
450: assert(len <= sizeof(buf) && len);
451: memset(buf, 0, sizeof(buf));
452: BN_bn2bin(challenge, buf + sizeof(buf) - len);
1.1 deraadt 453: MD5Init(&md);
454: MD5Update(&md, buf, 32);
455: MD5Update(&md, session_id, 16);
456: MD5Final(response, &md);
457:
458: debug("Sending response to host key RSA challenge.");
459:
460: /* Send the response back to the server. */
461: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
462: for (i = 0; i < 16; i++)
463: packet_put_char(response[i]);
464: packet_send();
465: packet_write_wait();
466:
467: memset(buf, 0, sizeof(buf));
468: memset(response, 0, sizeof(response));
469: memset(&md, 0, sizeof(md));
470: }
471:
472: /* Checks if the user has authentication file, and if so, tries to authenticate
473: the user using it. */
474:
1.3 provos 475: int
476: try_rsa_authentication(struct passwd *pw, const char *authfile,
477: int may_ask_passphrase)
1.1 deraadt 478: {
1.3 provos 479: BIGNUM *challenge;
480: RSA *private_key;
481: RSA *public_key;
1.1 deraadt 482: char *passphrase, *comment;
483: int type, i;
484: int plen, clen;
485:
486: /* Try to load identification for the authentication key. */
1.3 provos 487: public_key = RSA_new();
488: if (!load_public_key(authfile, public_key, &comment)) {
489: RSA_free(public_key);
1.1 deraadt 490: return 0; /* Could not load it. Fail. */
1.3 provos 491: }
1.1 deraadt 492:
493: debug("Trying RSA authentication with key '%.100s'", comment);
494:
495: /* Tell the server that we are willing to authenticate using this key. */
496: packet_start(SSH_CMSG_AUTH_RSA);
1.3 provos 497: packet_put_bignum(public_key->n);
1.1 deraadt 498: packet_send();
499: packet_write_wait();
500:
501: /* We no longer need the public key. */
1.3 provos 502: RSA_free(public_key);
1.1 deraadt 503:
504: /* Wait for server's response. */
505: type = packet_read(&plen);
506:
507: /* The server responds with failure if it doesn\'t like our key or doesn\'t
508: support RSA authentication. */
509: if (type == SSH_SMSG_FAILURE)
510: {
511: debug("Server refused our key.");
512: xfree(comment);
513: return 0; /* Server refuses to authenticate with this key. */
514: }
515:
516: /* Otherwise, the server should respond with a challenge. */
517: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
518: packet_disconnect("Protocol error during RSA authentication: %d", type);
519:
520: /* Get the challenge from the packet. */
1.3 provos 521: challenge = BN_new();
522: packet_get_bignum(challenge, &clen);
1.1 deraadt 523:
524: packet_integrity_check(plen, clen, type);
525:
526: debug("Received RSA challenge from server.");
527:
1.3 provos 528: private_key = RSA_new();
1.1 deraadt 529: /* Load the private key. Try first with empty passphrase; if it fails,
530: ask for a passphrase. */
1.3 provos 531: if (!load_private_key(authfile, "", private_key, NULL))
1.1 deraadt 532: {
533: char buf[300];
534: /* Request passphrase from the user. We read from /dev/tty to make
535: this work even if stdin has been redirected. If running in
536: batch mode, we just use the empty passphrase, which will fail and
537: return. */
1.6 deraadt 538: snprintf(buf, sizeof buf,
539: "Enter passphrase for RSA key '%.100s': ", comment);
1.1 deraadt 540: if (may_ask_passphrase)
541: passphrase = read_passphrase(buf, 0);
542: else
543: {
544: debug("Will not query passphrase for %.100s in batch mode.",
545: comment);
546: passphrase = xstrdup("");
547: }
548:
549: /* Load the authentication file using the pasphrase. */
1.3 provos 550: if (!load_private_key(authfile, passphrase, private_key, NULL))
1.1 deraadt 551: {
552: memset(passphrase, 0, strlen(passphrase));
553: xfree(passphrase);
554: error("Bad passphrase.");
555:
556: /* Send a dummy response packet to avoid protocol error. */
557: packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
558: for (i = 0; i < 16; i++)
559: packet_put_char(0);
560: packet_send();
561: packet_write_wait();
562:
563: /* Expect the server to reject it... */
564: packet_read_expect(&plen, SSH_SMSG_FAILURE);
565: xfree(comment);
566: return 0;
567: }
568:
569: /* Destroy the passphrase. */
570: memset(passphrase, 0, strlen(passphrase));
571: xfree(passphrase);
572: }
573:
574: /* We no longer need the comment. */
575: xfree(comment);
576:
577: /* Compute and send a response to the challenge. */
1.3 provos 578: respond_to_rsa_challenge(challenge, private_key);
1.1 deraadt 579:
580: /* Destroy the private key. */
1.3 provos 581: RSA_free(private_key);
1.1 deraadt 582:
583: /* We no longer need the challenge. */
1.3 provos 584: BN_clear_free(challenge);
1.1 deraadt 585:
586: /* Wait for response from the server. */
587: type = packet_read(&plen);
588: if (type == SSH_SMSG_SUCCESS)
589: {
590: debug("RSA authentication accepted by server.");
591: return 1;
592: }
593: if (type != SSH_SMSG_FAILURE)
594: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
595: debug("RSA authentication refused.");
596: return 0;
597: }
598:
599: /* Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
600: authentication and RSA host authentication. */
601:
1.3 provos 602: int
603: try_rhosts_rsa_authentication(const char *local_user, RSA *host_key)
1.1 deraadt 604: {
605: int type;
1.3 provos 606: BIGNUM *challenge;
1.1 deraadt 607: int plen, clen;
608:
609: debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
610:
611: /* Tell the server that we are willing to authenticate using this key. */
612: packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
613: packet_put_string(local_user, strlen(local_user));
1.3 provos 614: packet_put_int(BN_num_bits(host_key->n));
615: packet_put_bignum(host_key->e);
616: packet_put_bignum(host_key->n);
1.1 deraadt 617: packet_send();
618: packet_write_wait();
619:
620: /* Wait for server's response. */
621: type = packet_read(&plen);
622:
623: /* The server responds with failure if it doesn't admit our .rhosts
624: authentication or doesn't know our host key. */
625: if (type == SSH_SMSG_FAILURE)
626: {
627: debug("Server refused our rhosts authentication or host key.");
628: return 0; /* Server refuses to authenticate us with this method. */
629: }
630:
631: /* Otherwise, the server should respond with a challenge. */
632: if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
633: packet_disconnect("Protocol error during RSA authentication: %d", type);
634:
635: /* Get the challenge from the packet. */
1.3 provos 636: challenge = BN_new();
637: packet_get_bignum(challenge, &clen);
1.1 deraadt 638:
639: packet_integrity_check(plen, clen, type);
640:
641: debug("Received RSA challenge for host key from server.");
642:
643: /* Compute a response to the challenge. */
1.3 provos 644: respond_to_rsa_challenge(challenge, host_key);
1.1 deraadt 645:
646: /* We no longer need the challenge. */
1.3 provos 647: BN_clear_free(challenge);
1.1 deraadt 648:
649: /* Wait for response from the server. */
650: type = packet_read(&plen);
651: if (type == SSH_SMSG_SUCCESS)
652: {
653: debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
654: return 1;
655: }
656: if (type != SSH_SMSG_FAILURE)
657: packet_disconnect("Protocol error waiting RSA auth response: %d", type);
658: debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
659: return 0;
660: }
661:
662: #ifdef KRB4
663: int try_kerberos_authentication()
664: {
665: KTEXT_ST auth; /* Kerberos data */
666: char *reply;
667: char inst[INST_SZ];
668: char *realm;
669: CREDENTIALS cred;
1.5 dugsong 670: int r, type, plen;
1.1 deraadt 671: Key_schedule schedule;
672: u_long checksum, cksum;
673: MSG_DAT msg_data;
674: struct sockaddr_in local, foreign;
675: struct stat st;
676:
677: /* Don't do anything if we don't have any tickets. */
678: if (stat(tkt_string(), &st) < 0) return 0;
679:
680: strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
681:
682: realm = (char *)krb_realmofhost(get_canonical_hostname());
683: if (!realm) {
1.5 dugsong 684: debug("Kerberos V4: no realm for %s", get_canonical_hostname());
1.1 deraadt 685: return 0;
686: }
687: /* This can really be anything. */
688: checksum = (u_long) getpid();
689:
690: r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
691: if (r != KSUCCESS) {
1.5 dugsong 692: debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]);
1.1 deraadt 693: return 0;
694: }
695: /* Get session key to decrypt the server's reply with. */
696: r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
697: if (r != KSUCCESS) {
1.5 dugsong 698: debug("get_cred failed: %s", krb_err_txt[r]);
1.1 deraadt 699: return 0;
700: }
701: des_key_sched((des_cblock *)cred.session, schedule);
702:
703: /* Send authentication info to server. */
704: packet_start(SSH_CMSG_AUTH_KERBEROS);
705: packet_put_string((char *)auth.dat, auth.length);
706: packet_send();
707: packet_write_wait();
708:
1.5 dugsong 709: /* Zero the buffer. */
1.1 deraadt 710: (void) memset(auth.dat, 0, MAX_KTXT_LEN);
711:
712: r = sizeof(local);
713: memset(&local, 0, sizeof(local));
714: if (getsockname(packet_get_connection_in(),
715: (struct sockaddr *) &local, &r) < 0)
1.5 dugsong 716: debug("getsockname failed: %s", strerror(errno));
1.1 deraadt 717:
718: r = sizeof(foreign);
719: memset(&foreign, 0, sizeof(foreign));
720: if (getpeername(packet_get_connection_in(),
721: (struct sockaddr *)&foreign, &r) < 0)
1.5 dugsong 722: debug("getpeername failed: %s", strerror(errno));
1.1 deraadt 723:
724: /* Get server reply. */
725: type = packet_read(&plen);
726: switch(type) {
727:
728: case SSH_SMSG_FAILURE: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
729: debug("Kerberos V4 authentication failed.");
730: return 0;
731: break;
732:
733: case SSH_SMSG_AUTH_KERBEROS_RESPONSE: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
734: debug("Kerberos V4 authentication accepted.");
735:
736: /* Get server's response. */
737: reply = packet_get_string((unsigned int *)&auth.length);
738: memcpy(auth.dat, reply, auth.length);
739: xfree(reply);
740:
741: packet_integrity_check(plen, 4 + auth.length, type);
742:
743: /* If his response isn't properly encrypted with the session key,
744: and the decrypted checksum fails to match, he's bogus. Bail out. */
745: r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
746: &foreign, &local, &msg_data);
747: if (r != KSUCCESS) {
1.5 dugsong 748: debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]);
1.1 deraadt 749: packet_disconnect("Kerberos V4 challenge failed!");
750: }
1.5 dugsong 751: /* Fetch the (incremented) checksum that we supplied in the request. */
1.1 deraadt 752: (void)memcpy((char *)&cksum, (char *)msg_data.app_data, sizeof(cksum));
753: cksum = ntohl(cksum);
754:
755: /* If it matches, we're golden. */
756: if (cksum == checksum + 1) {
757: debug("Kerberos V4 challenge successful.");
758: return 1;
759: }
760: else
761: packet_disconnect("Kerberos V4 challenge failed!");
762: break;
763:
764: default:
765: packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
766: }
767: return 0;
768: }
769: #endif /* KRB4 */
770:
771: #ifdef AFS
772: int send_kerberos_tgt()
773: {
774: CREDENTIALS *creds;
775: char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
1.5 dugsong 776: int r, type, plen;
1.1 deraadt 777: unsigned char buffer[8192];
778: struct stat st;
779:
780: /* Don't do anything if we don't have any tickets. */
781: if (stat(tkt_string(), &st) < 0) return 0;
782:
1.5 dugsong 783: creds = xmalloc(sizeof(*creds));
1.1 deraadt 784:
1.5 dugsong 785: if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) {
786: debug("Kerberos V4 tf_fullname failed: %s",krb_err_txt[r]);
1.1 deraadt 787: return 0;
1.5 dugsong 788: }
789: if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
790: debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]);
1.1 deraadt 791: return 0;
792: }
793: if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
1.5 dugsong 794: debug("Kerberos V4 ticket expired: %s", TKT_FILE);
1.1 deraadt 795: return 0;
796: }
797:
798: creds_to_radix(creds, buffer);
799: xfree(creds);
800:
801: packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
802: packet_put_string((char *)buffer, strlen(buffer));
803: packet_send();
804: packet_write_wait();
805:
806: type = packet_read(&plen);
1.5 dugsong 807:
1.1 deraadt 808: if (type == SSH_SMSG_FAILURE)
1.5 dugsong 809: debug("Kerberos TGT for realm %s rejected.", prealm);
1.1 deraadt 810: else if (type != SSH_SMSG_SUCCESS)
811: packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
812:
813: return 1;
814: }
815:
816: void send_afs_tokens(void)
817: {
818: CREDENTIALS creds;
819: struct ViceIoctl parms;
820: struct ClearToken ct;
1.5 dugsong 821: int i, type, len, plen;
1.1 deraadt 822: char buf[2048], *p, *server_cell;
823: unsigned char buffer[8192];
824:
825: /* Move over ktc_GetToken, here's something leaner. */
826: for (i = 0; i < 100; i++) { /* just in case */
827: parms.in = (char *)&i;
828: parms.in_size = sizeof(i);
829: parms.out = buf;
830: parms.out_size = sizeof(buf);
831: if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) break;
832: p = buf;
833:
834: /* Get secret token. */
835: memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
836: if (creds.ticket_st.length > MAX_KTXT_LEN) break;
837: p += sizeof(unsigned int);
838: memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
839: p += creds.ticket_st.length;
840:
841: /* Get clear token. */
842: memcpy(&len, p, sizeof(len));
843: if (len != sizeof(struct ClearToken)) break;
844: p += sizeof(len);
845: memcpy(&ct, p, len);
846: p += len;
847: p += sizeof(len); /* primary flag */
848: server_cell = p;
849:
850: /* Flesh out our credentials. */
1.6 deraadt 851: strlcpy(creds.service, "afs", sizeof creds.service);
1.1 deraadt 852: creds.instance[0] = '\0';
1.6 deraadt 853: strlcpy(creds.realm, server_cell, REALM_SZ);
1.1 deraadt 854: memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
855: creds.issue_date = ct.BeginTimestamp;
856: creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
857: creds.kvno = ct.AuthHandle;
1.5 dugsong 858: snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId);
1.1 deraadt 859: creds.pinst[0] = '\0';
860:
861: /* Encode token, ship it off. */
862: if (!creds_to_radix(&creds, buffer)) break;
863: packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
864: packet_put_string((char *)buffer, strlen(buffer));
865: packet_send();
866: packet_write_wait();
867:
868: /* Roger, Roger. Clearance, Clarence. What's your vector, Victor? */
869: type = packet_read(&plen);
870:
871: if (type == SSH_SMSG_FAILURE)
1.5 dugsong 872: debug("AFS token for cell %s rejected.", server_cell);
1.1 deraadt 873: else if (type != SSH_SMSG_SUCCESS)
874: packet_disconnect("Protocol error on AFS token response: %d", type);
875: }
876: }
877: #endif /* AFS */
878:
879: /* Waits for the server identification string, and sends our own identification
880: string. */
881:
882: void ssh_exchange_identification()
883: {
884: char buf[256], remote_version[256]; /* must be same size! */
885: int remote_major, remote_minor, i;
886: int connection_in = packet_get_connection_in();
887: int connection_out = packet_get_connection_out();
888:
889: /* Read other side\'s version identification. */
890: for (i = 0; i < sizeof(buf) - 1; i++)
891: {
892: if (read(connection_in, &buf[i], 1) != 1)
893: fatal("read: %.100s", strerror(errno));
894: if (buf[i] == '\r')
895: {
896: buf[i] = '\n';
897: buf[i + 1] = 0;
898: break;
899: }
900: if (buf[i] == '\n')
901: {
902: buf[i + 1] = 0;
903: break;
904: }
905: }
906: buf[sizeof(buf) - 1] = 0;
907:
908: /* Check that the versions match. In future this might accept several
909: versions and set appropriate flags to handle them. */
910: if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor,
911: remote_version) != 3)
912: fatal("Bad remote protocol version identification: '%.100s'", buf);
913: debug("Remote protocol version %d.%d, remote software version %.100s",
914: remote_major, remote_minor, remote_version);
915: #if 0
916: /* Removed for now, to permit compatibility with latter versions. The server
917: will reject our version and disconnect if it doesn't support it. */
918: if (remote_major != PROTOCOL_MAJOR)
919: fatal("Protocol major versions differ: %d vs. %d",
920: PROTOCOL_MAJOR, remote_major);
921: #endif
922:
923: /* Check if the remote protocol version is too old. */
924: if (remote_major == 1 && remote_minor == 0)
925: fatal("Remote machine has too old SSH software version.");
926:
927: /* Send our own protocol version identification. */
1.6 deraadt 928: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.1 deraadt 929: PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
930: if (write(connection_out, buf, strlen(buf)) != strlen(buf))
931: fatal("write: %.100s", strerror(errno));
932: }
933:
934: int ssh_cipher_default = SSH_CIPHER_3DES;
935:
936: int read_yes_or_no(const char *prompt, int defval)
937: {
938: char buf[1024];
939: FILE *f;
940: int retval = -1;
941:
942: if (isatty(0))
943: f = stdin;
944: else
945: f = fopen("/dev/tty", "rw");
946:
947: if (f == NULL)
948: return 0;
949:
950: fflush(stdout);
951:
952: while (1)
953: {
954: fprintf(stderr, "%s", prompt);
955: if (fgets(buf, sizeof(buf), f) == NULL)
956: {
957: /* Print a newline (the prompt probably didn\'t have one). */
958: fprintf(stderr, "\n");
1.6 deraadt 959: strlcpy(buf, "no", sizeof buf);
1.1 deraadt 960: }
961: /* Remove newline from response. */
962: if (strchr(buf, '\n'))
963: *strchr(buf, '\n') = 0;
964:
965: if (buf[0] == 0)
966: retval = defval;
967: if (strcmp(buf, "yes") == 0)
968: retval = 1;
969: if (strcmp(buf, "no") == 0)
970: retval = 0;
971:
972: if (retval != -1)
973: {
974: if (f != stdin)
975: fclose(f);
976: return retval;
977: }
978: }
979: }
980:
981: /* Starts a dialog with the server, and authenticates the current user on the
982: server. This does not need any extra privileges. The basic connection
983: to the server must already have been established before this is called.
984: User is the remote user; if it is NULL, the current local user name will
985: be used. Anonymous indicates that no rhosts authentication will be used.
986: If login fails, this function prints an error and never returns.
987: This function does not require super-user privileges. */
988:
1.3 provos 989: void ssh_login(int host_key_valid,
990: RSA *own_host_key,
1.1 deraadt 991: const char *orighost,
992: Options *options, uid_t original_real_uid)
993: {
994: int i, type;
995: char *password;
996: struct passwd *pw;
1.3 provos 997: BIGNUM *key;
998: RSA *host_key;
999: RSA *public_key;
1.1 deraadt 1000: unsigned char session_key[SSH_SESSION_KEY_LENGTH];
1001: const char *server_user, *local_user;
1002: char *cp, *host;
1003: unsigned char check_bytes[8];
1004: unsigned int supported_ciphers, supported_authentications, protocol_flags;
1005: HostStatus host_status;
1006: int payload_len, clen, sum_len = 0;
1.5 dugsong 1007: u_int32_t rand = 0;
1.1 deraadt 1008:
1009: /* Convert the user-supplied hostname into all lowercase. */
1010: host = xstrdup(orighost);
1011: for (cp = host; *cp; cp++)
1012: if (isupper(*cp))
1013: *cp = tolower(*cp);
1014:
1015: /* Exchange protocol version identification strings with the server. */
1016: ssh_exchange_identification();
1017:
1018: /* Put the connection into non-blocking mode. */
1019: packet_set_nonblocking();
1020:
1021: /* Get local user name. Use it as server user if no user name
1022: was given. */
1023: pw = getpwuid(original_real_uid);
1024: if (!pw)
1025: fatal("User id %d not found from user database.", original_real_uid);
1026: local_user = xstrdup(pw->pw_name);
1027: server_user = options->user ? options->user : local_user;
1028:
1029: debug("Waiting for server public key.");
1030:
1031: /* Wait for a public key packet from the server. */
1032: packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
1033:
1034: /* Get check bytes from the packet. */
1035: for (i = 0; i < 8; i++)
1036: check_bytes[i] = packet_get_char();
1037:
1038: /* Get the public key. */
1.3 provos 1039: public_key = RSA_new();
1040: packet_get_int(); /* bits */
1041: public_key->e = BN_new();
1042: packet_get_bignum(public_key->e, &clen);
1.1 deraadt 1043: sum_len += clen;
1.3 provos 1044: public_key->n = BN_new();
1045: packet_get_bignum(public_key->n, &clen);
1.1 deraadt 1046: sum_len += clen;
1047:
1048: /* Get the host key. */
1.3 provos 1049: host_key = RSA_new();
1050: packet_get_int(); /* bits */
1051: host_key->e = BN_new();
1052: packet_get_bignum(host_key->e, &clen);
1.1 deraadt 1053: sum_len += clen;
1.3 provos 1054: host_key->n = BN_new();
1055: packet_get_bignum(host_key->n, &clen);
1.1 deraadt 1056: sum_len += clen;
1057:
1058: /* Get protocol flags. */
1059: protocol_flags = packet_get_int();
1060: packet_set_protocol_flags(protocol_flags);
1061:
1062: /* Get supported cipher types. */
1063: supported_ciphers = packet_get_int();
1064:
1065: /* Get supported authentication types. */
1066: supported_authentications = packet_get_int();
1067:
1068: debug("Received server public key (%d bits) and host key (%d bits).",
1.3 provos 1069: BN_num_bits(public_key->n), BN_num_bits(host_key->n));
1.1 deraadt 1070:
1071: packet_integrity_check(payload_len,
1072: 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
1073: SSH_SMSG_PUBLIC_KEY);
1074:
1075: /* Compute the session id. */
1.3 provos 1076: compute_session_id(session_id, check_bytes,
1077: BN_num_bits(host_key->n), host_key->n,
1078: BN_num_bits(public_key->n), public_key->n);
1.1 deraadt 1079:
1080: /* Check if the host key is present in the user\'s list of known hosts
1081: or in the systemwide list. */
1082: host_status = check_host_in_hostfile(options->user_hostfile,
1.3 provos 1083: host, BN_num_bits(host_key->n),
1084: host_key->e, host_key->n);
1.1 deraadt 1085: if (host_status == HOST_NEW)
1086: host_status = check_host_in_hostfile(options->system_hostfile, host,
1.3 provos 1087: BN_num_bits(host_key->n),
1088: host_key->e, host_key->n);
1.1 deraadt 1089:
1090: /* Force accepting of the host key for localhost and 127.0.0.1.
1091: The problem is that if the home directory is NFS-mounted to multiple
1092: machines, localhost will refer to a different machine in each of them,
1093: and the user will get bogus HOST_CHANGED warnings. This essentially
1094: disables host authentication for localhost; however, this is probably
1095: not a real problem. */
1096: if (strcmp(host, "localhost") == 0 ||
1097: strcmp(host, "127.0.0.1") == 0)
1098: {
1099: debug("Forcing accepting of host key for localhost.");
1100: host_status = HOST_OK;
1101: }
1102:
1103: switch (host_status)
1104: {
1105: case HOST_OK:
1106: /* The host is known and the key matches. */
1107: debug("Host '%.200s' is known and matches the host key.", host);
1108: break;
1109: case HOST_NEW:
1110: /* The host is new. */
1111: if (options->strict_host_key_checking == 1)
1112: { /* User has requested strict host key checking. We will not
1113: add the host key automatically. The only alternative left
1114: is to abort. */
1115: fatal("No host key is known for %.200s and you have requested strict checking.", host);
1116: }
1117: else if (options->strict_host_key_checking == 2) /* The default */
1118: {
1119: char prompt[1024];
1120: sprintf(prompt,
1121: "The authenticity of host '%.200s' can't be established.\n"
1122: "Are you sure you want to continue connecting (yes/no)? ",
1123: host);
1124: if (!read_yes_or_no(prompt, -1))
1125: fatal("Aborted by user!\n");
1126: }
1127: /* If not in strict mode, add the key automatically to the local
1128: known_hosts file. */
1.3 provos 1129: if (!add_host_to_hostfile(options->user_hostfile, host,
1130: BN_num_bits(host_key->n),
1131: host_key->e, host_key->n))
1.1 deraadt 1132: log("Failed to add the host to the list of known hosts (%.500s).",
1133: options->user_hostfile);
1134: else
1135: log("Warning: Permanently added host '%.200s' to the list of known hosts.", host);
1136: break;
1137: case HOST_CHANGED:
1138: /* The host key has changed. */
1139: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1140: error("@ WARNING: HOST IDENTIFICATION HAS CHANGED! @");
1141: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1142: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1143: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1144: error("It is also possible that the host key has just been changed.");
1145: error("Please contact your system administrator.");
1146: error("Add correct host key in %.100s to get rid of this message.",
1147: options->user_hostfile);
1148:
1149: /* If strict host key checking is in use, the user will have to edit
1150: the key manually and we can only abort. */
1151: if (options->strict_host_key_checking)
1152: fatal("Host key for %.200s has changed and you have requested strict checking.", host);
1153:
1154: /* If strict host key checking has not been requested, allow the
1155: connection but without password authentication. */
1156: error("Password authentication is disabled to avoid trojan horses.");
1157: options->password_authentication = 0;
1158: /* XXX Should permit the user to change to use the new id. This could
1159: be done by converting the host key to an identifying sentence, tell
1160: that the host identifies itself by that sentence, and ask the user
1161: if he/she whishes to accept the authentication. */
1162: break;
1163: }
1164:
1165: /* Generate a session key. */
1.3 provos 1166: arc4random_stir();
1.1 deraadt 1167:
1168: /* Generate an encryption key for the session. The key is a 256 bit
1169: random number, interpreted as a 32-byte key, with the least significant
1170: 8 bits being the first byte of the key. */
1.3 provos 1171: for (i = 0; i < 32; i++) {
1172: if (i % 4 == 0)
1173: rand = arc4random();
1174: session_key[i] = rand & 0xff;
1175: rand >>= 8;
1176: }
1.1 deraadt 1177:
1178: /* According to the protocol spec, the first byte of the session key is
1179: the highest byte of the integer. The session key is xored with the
1180: first 16 bytes of the session id. */
1.3 provos 1181: key = BN_new();
1182: BN_set_word(key, 0);
1.1 deraadt 1183: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++)
1184: {
1.3 provos 1185: BN_lshift(key, key, 8);
1.1 deraadt 1186: if (i < 16)
1.3 provos 1187: BN_add_word(key, session_key[i] ^ session_id[i]);
1.1 deraadt 1188: else
1.3 provos 1189: BN_add_word(key, session_key[i]);
1.1 deraadt 1190: }
1191:
1192: /* Encrypt the integer using the public key and host key of the server
1193: (key with smaller modulus first). */
1.3 provos 1194: if (BN_cmp(public_key->n, host_key->n) < 0)
1.1 deraadt 1195: {
1196: /* Public key has smaller modulus. */
1.3 provos 1197: assert(BN_num_bits(host_key->n) >=
1198: BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED);
1.1 deraadt 1199:
1.3 provos 1200: rsa_public_encrypt(key, key, public_key);
1201: rsa_public_encrypt(key, key, host_key);
1.1 deraadt 1202: }
1203: else
1204: {
1205: /* Host key has smaller modulus (or they are equal). */
1.3 provos 1206: assert(BN_num_bits(public_key->n) >=
1207: BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED);
1.1 deraadt 1208:
1.3 provos 1209: rsa_public_encrypt(key, key, host_key);
1210: rsa_public_encrypt(key, key, public_key);
1.1 deraadt 1211: }
1212:
1.3 provos 1213: if (options->cipher == SSH_CIPHER_NOT_SET) {
1.1 deraadt 1214: if (cipher_mask() & supported_ciphers & (1 << ssh_cipher_default))
1215: options->cipher = ssh_cipher_default;
1.3 provos 1216: else {
1217: debug("Cipher %d not supported, using %.100s instead.",
1218: cipher_name(ssh_cipher_default),
1219: cipher_name(SSH_FALLBACK_CIPHER));
1220: options->cipher = SSH_FALLBACK_CIPHER;
1221: }
1222: }
1.1 deraadt 1223:
1224: /* Check that the selected cipher is supported. */
1225: if (!(supported_ciphers & (1 << options->cipher)))
1226: fatal("Selected cipher type %.100s not supported by server.",
1227: cipher_name(options->cipher));
1228:
1229: debug("Encryption type: %.100s", cipher_name(options->cipher));
1230:
1231: /* Send the encrypted session key to the server. */
1232: packet_start(SSH_CMSG_SESSION_KEY);
1233: packet_put_char(options->cipher);
1234:
1235: /* Send the check bytes back to the server. */
1236: for (i = 0; i < 8; i++)
1237: packet_put_char(check_bytes[i]);
1238:
1239: /* Send the encrypted encryption key. */
1.3 provos 1240: packet_put_bignum(key);
1.1 deraadt 1241:
1242: /* Send protocol flags. */
1243: packet_put_int(SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1244:
1245: /* Send the packet now. */
1246: packet_send();
1247: packet_write_wait();
1248:
1249: /* Destroy the session key integer and the public keys since we no longer
1250: need them. */
1.3 provos 1251: BN_clear_free(key);
1252: RSA_free(public_key);
1253: RSA_free(host_key);
1.1 deraadt 1254:
1255: debug("Sent encrypted session key.");
1256:
1257: /* Set the encryption key. */
1258: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH,
1259: options->cipher, 1);
1260:
1261: /* We will no longer need the session key here. Destroy any extra copies. */
1262: memset(session_key, 0, sizeof(session_key));
1263:
1264: /* Expect a success message from the server. Note that this message will
1265: be received in encrypted form. */
1266: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1267:
1268: debug("Received encrypted confirmation.");
1269:
1270: /* Send the name of the user to log in as on the server. */
1271: packet_start(SSH_CMSG_USER);
1272: packet_put_string(server_user, strlen(server_user));
1273: packet_send();
1274: packet_write_wait();
1275:
1276: /* The server should respond with success if no authentication is needed
1277: (the user has no password). Otherwise the server responds with
1278: failure. */
1279: type = packet_read(&payload_len);
1280: if (type == SSH_SMSG_SUCCESS)
1281: return; /* Connection was accepted without authentication. */
1282: if (type != SSH_SMSG_FAILURE)
1283: packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
1284: type);
1285:
1.5 dugsong 1286: #ifdef AFS
1.1 deraadt 1287: /* Try Kerberos tgt passing if the server supports it. */
1288: if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
1.5 dugsong 1289: options->kerberos_tgt_passing)
1290: {
1291: if (options->cipher == SSH_CIPHER_NONE)
1292: log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
1293: (void)send_kerberos_tgt();
1294: }
1295:
1.1 deraadt 1296: /* Try AFS token passing if the server supports it. */
1297: if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
1298: options->afs_token_passing && k_hasafs()) {
1299: if (options->cipher == SSH_CIPHER_NONE)
1300: log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
1301: send_afs_tokens();
1302: }
1303: #endif /* AFS */
1304:
1.5 dugsong 1305: #ifdef KRB4
1.1 deraadt 1306: if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
1307: options->kerberos_authentication)
1308: {
1.5 dugsong 1309: debug("Trying Kerberos authentication.");
1.1 deraadt 1310: if (try_kerberos_authentication()) {
1311: /* The server should respond with success or failure. */
1312: type = packet_read(&payload_len);
1313: if (type == SSH_SMSG_SUCCESS)
1314: return; /* Successful connection. */
1315: if (type != SSH_SMSG_FAILURE)
1316: packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
1317: }
1318: }
1319: #endif /* KRB4 */
1320:
1321: /* Use rhosts authentication if running in privileged socket and we do not
1322: wish to remain anonymous. */
1323: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
1324: options->rhosts_authentication)
1325: {
1326: debug("Trying rhosts authentication.");
1327: packet_start(SSH_CMSG_AUTH_RHOSTS);
1328: packet_put_string(local_user, strlen(local_user));
1329: packet_send();
1330: packet_write_wait();
1331:
1332: /* The server should respond with success or failure. */
1333: type = packet_read(&payload_len);
1334: if (type == SSH_SMSG_SUCCESS)
1335: return; /* Successful connection. */
1336: if (type != SSH_SMSG_FAILURE)
1337: packet_disconnect("Protocol error: got %d in response to rhosts auth",
1338: type);
1339: }
1340:
1341: /* Try .rhosts or /etc/hosts.equiv authentication with RSA host
1342: authentication. */
1343: if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
1344: options->rhosts_rsa_authentication && host_key_valid)
1345: {
1346: if (try_rhosts_rsa_authentication(local_user, own_host_key))
1347: return; /* Successful authentication. */
1348: }
1349:
1350: /* Try RSA authentication if the server supports it. */
1351: if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
1352: options->rsa_authentication)
1353: {
1354: /* Try RSA authentication using the authentication agent. The agent
1355: is tried first because no passphrase is needed for it, whereas
1356: identity files may require passphrases. */
1357: if (try_agent_authentication())
1358: return; /* Successful connection. */
1359:
1360: /* Try RSA authentication for each identity. */
1361: for (i = 0; i < options->num_identity_files; i++)
1362: if (try_rsa_authentication(pw, options->identity_files[i],
1363: !options->batch_mode))
1364: return; /* Successful connection. */
1365: }
1366:
1367: /* Try password authentication if the server supports it. */
1368: if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
1369: options->password_authentication && !options->batch_mode)
1370: {
1.4 provos 1371: char prompt[80];
1372: snprintf(prompt, sizeof(prompt), "%.30s@%.30s's password: ",
1373: server_user, host);
1.1 deraadt 1374: debug("Doing password authentication.");
1375: if (options->cipher == SSH_CIPHER_NONE)
1376: log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
1.4 provos 1377: password = read_passphrase(prompt, 0);
1.1 deraadt 1378: packet_start(SSH_CMSG_AUTH_PASSWORD);
1379: packet_put_string(password, strlen(password));
1380: memset(password, 0, strlen(password));
1381: xfree(password);
1382: packet_send();
1383: packet_write_wait();
1384:
1385: type = packet_read(&payload_len);
1386: if (type == SSH_SMSG_SUCCESS)
1387: return; /* Successful connection. */
1388: if (type != SSH_SMSG_FAILURE)
1389: packet_disconnect("Protocol error: got %d in response to passwd auth",
1390: type);
1391: }
1392:
1393: /* All authentication methods have failed. Exit with an error message. */
1394: fatal("Permission denied.");
1395: /*NOTREACHED*/
1396: }
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