Annotation of src/usr.bin/ssh/sshconnect2.c, Revision 1.25
1.1 markus 1: /*
2: * Copyright (c) 2000 Markus Friedl. All rights reserved.
3: *
4: * Redistribution and use in source and binary forms, with or without
5: * modification, are permitted provided that the following conditions
6: * are met:
7: * 1. Redistributions of source code must retain the above copyright
8: * notice, this list of conditions and the following disclaimer.
9: * 2. Redistributions in binary form must reproduce the above copyright
10: * notice, this list of conditions and the following disclaimer in the
11: * documentation and/or other materials provided with the distribution.
12: *
13: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: */
24:
25: #include "includes.h"
1.25 ! markus 26: RCSID("$OpenBSD: sshconnect2.c,v 1.24 2000/10/11 20:27:24 markus Exp $");
1.1 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/rsa.h>
30: #include <openssl/dsa.h>
31: #include <openssl/md5.h>
32: #include <openssl/dh.h>
33: #include <openssl/hmac.h>
34:
35: #include "ssh.h"
36: #include "xmalloc.h"
37: #include "rsa.h"
38: #include "buffer.h"
39: #include "packet.h"
40: #include "uidswap.h"
41: #include "compat.h"
42: #include "readconf.h"
43: #include "bufaux.h"
44: #include "ssh2.h"
45: #include "kex.h"
46: #include "myproposal.h"
47: #include "key.h"
48: #include "dsa.h"
49: #include "sshconnect.h"
50: #include "authfile.h"
1.23 markus 51: #include "cli.h"
1.20 markus 52: #include "dispatch.h"
1.17 markus 53: #include "authfd.h"
1.1 markus 54:
1.22 provos 55: void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *);
56: void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *);
57:
1.1 markus 58: /* import */
59: extern char *client_version_string;
60: extern char *server_version_string;
61: extern Options options;
62:
63: /*
64: * SSH2 key exchange
65: */
66:
67: unsigned char *session_id2 = NULL;
68: int session_id2_len = 0;
69:
70: void
1.22 provos 71: ssh_kex2(char *host, struct sockaddr *hostaddr)
72: {
73: int i, plen;
74: Kex *kex;
75: Buffer *client_kexinit, *server_kexinit;
76: char *sprop[PROPOSAL_MAX];
77:
1.24 markus 78: if (options.ciphers == NULL) {
79: if (options.cipher == SSH_CIPHER_3DES) {
80: options.ciphers = "3des-cbc";
81: } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
82: options.ciphers = "blowfish-cbc";
1.25 ! markus 83: } else if (options.cipher == SSH_CIPHER_DES) {
! 84: fatal("cipher DES not supported for protocol version 2");
1.24 markus 85: }
86: }
1.22 provos 87: if (options.ciphers != NULL) {
88: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
89: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
90: }
91: if (options.compression) {
92: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
93: myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
94: } else {
95: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
96: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
97: }
98:
99: /* buffers with raw kexinit messages */
100: server_kexinit = xmalloc(sizeof(*server_kexinit));
101: buffer_init(server_kexinit);
102: client_kexinit = kex_init(myproposal);
103:
104: /* algorithm negotiation */
105: kex_exchange_kexinit(client_kexinit, server_kexinit, sprop);
106: kex = kex_choose_conf(myproposal, sprop, 0);
107: for (i = 0; i < PROPOSAL_MAX; i++)
108: xfree(sprop[i]);
109:
110: /* server authentication and session key agreement */
111: switch(kex->kex_type) {
112: case DH_GRP1_SHA1:
113: ssh_dh1_client(kex, host, hostaddr,
114: client_kexinit, server_kexinit);
115: break;
116: case DH_GEX_SHA1:
117: ssh_dhgex_client(kex, host, hostaddr, client_kexinit,
118: server_kexinit);
119: break;
120: default:
121: fatal("Unsupported key exchange %d", kex->kex_type);
122: }
123:
124: buffer_free(client_kexinit);
125: buffer_free(server_kexinit);
126: xfree(client_kexinit);
127: xfree(server_kexinit);
128:
129: debug("Wait SSH2_MSG_NEWKEYS.");
130: packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
131: packet_done();
132: debug("GOT SSH2_MSG_NEWKEYS.");
133:
134: debug("send SSH2_MSG_NEWKEYS.");
135: packet_start(SSH2_MSG_NEWKEYS);
136: packet_send();
137: packet_write_wait();
138: debug("done: send SSH2_MSG_NEWKEYS.");
139:
140: #ifdef DEBUG_KEXDH
141: /* send 1st encrypted/maced/compressed message */
142: packet_start(SSH2_MSG_IGNORE);
143: packet_put_cstring("markus");
144: packet_send();
145: packet_write_wait();
146: #endif
147: debug("done: KEX2.");
148: }
149:
150: /* diffie-hellman-group1-sha1 */
151:
152: void
153: ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr,
154: Buffer *client_kexinit, Buffer *server_kexinit)
1.1 markus 155: {
1.19 markus 156: #ifdef DEBUG_KEXDH
157: int i;
158: #endif
1.11 markus 159: int plen, dlen;
1.1 markus 160: unsigned int klen, kout;
161: char *signature = NULL;
162: unsigned int slen;
163: char *server_host_key_blob = NULL;
164: Key *server_host_key;
165: unsigned int sbloblen;
166: DH *dh;
167: BIGNUM *dh_server_pub = 0;
168: BIGNUM *shared_secret = 0;
169: unsigned char *kbuf;
170: unsigned char *hash;
171:
172: debug("Sending SSH2_MSG_KEXDH_INIT.");
173: /* generate and send 'e', client DH public key */
174: dh = dh_new_group1();
175: packet_start(SSH2_MSG_KEXDH_INIT);
176: packet_put_bignum2(dh->pub_key);
177: packet_send();
178: packet_write_wait();
179:
180: #ifdef DEBUG_KEXDH
181: fprintf(stderr, "\np= ");
1.19 markus 182: BN_print_fp(stderr, dh->p);
1.1 markus 183: fprintf(stderr, "\ng= ");
1.19 markus 184: BN_print_fp(stderr, dh->g);
1.1 markus 185: fprintf(stderr, "\npub= ");
1.19 markus 186: BN_print_fp(stderr, dh->pub_key);
1.1 markus 187: fprintf(stderr, "\n");
188: DHparams_print_fp(stderr, dh);
189: #endif
190:
191: debug("Wait SSH2_MSG_KEXDH_REPLY.");
192:
1.11 markus 193: packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
1.1 markus 194:
195: debug("Got SSH2_MSG_KEXDH_REPLY.");
196:
197: /* key, cert */
198: server_host_key_blob = packet_get_string(&sbloblen);
199: server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
200: if (server_host_key == NULL)
201: fatal("cannot decode server_host_key_blob");
202:
203: check_host_key(host, hostaddr, server_host_key,
1.22 provos 204: options.user_hostfile2, options.system_hostfile2);
1.1 markus 205:
206: /* DH paramter f, server public DH key */
207: dh_server_pub = BN_new();
208: if (dh_server_pub == NULL)
209: fatal("dh_server_pub == NULL");
210: packet_get_bignum2(dh_server_pub, &dlen);
211:
212: #ifdef DEBUG_KEXDH
213: fprintf(stderr, "\ndh_server_pub= ");
1.19 markus 214: BN_print_fp(stderr, dh_server_pub);
1.1 markus 215: fprintf(stderr, "\n");
216: debug("bits %d", BN_num_bits(dh_server_pub));
217: #endif
218:
219: /* signed H */
220: signature = packet_get_string(&slen);
221: packet_done();
222:
223: if (!dh_pub_is_valid(dh, dh_server_pub))
224: packet_disconnect("bad server public DH value");
225:
226: klen = DH_size(dh);
227: kbuf = xmalloc(klen);
228: kout = DH_compute_key(kbuf, dh_server_pub, dh);
229: #ifdef DEBUG_KEXDH
230: debug("shared secret: len %d/%d", klen, kout);
231: fprintf(stderr, "shared secret == ");
232: for (i = 0; i< kout; i++)
233: fprintf(stderr, "%02x", (kbuf[i])&0xff);
234: fprintf(stderr, "\n");
235: #endif
236: shared_secret = BN_new();
237:
238: BN_bin2bn(kbuf, kout, shared_secret);
239: memset(kbuf, 0, klen);
240: xfree(kbuf);
241:
242: /* calc and verify H */
243: hash = kex_hash(
244: client_version_string,
245: server_version_string,
246: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
247: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
248: server_host_key_blob, sbloblen,
249: dh->pub_key,
250: dh_server_pub,
251: shared_secret
252: );
1.3 markus 253: xfree(server_host_key_blob);
1.11 markus 254: DH_free(dh);
1.1 markus 255: #ifdef DEBUG_KEXDH
256: fprintf(stderr, "hash == ");
257: for (i = 0; i< 20; i++)
258: fprintf(stderr, "%02x", (hash[i])&0xff);
259: fprintf(stderr, "\n");
260: #endif
261: if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
262: fatal("dsa_verify failed for server_host_key");
263: key_free(server_host_key);
264:
265: kex_derive_keys(kex, hash, shared_secret);
266: packet_set_kex(kex);
267:
268: /* save session id */
269: session_id2_len = 20;
270: session_id2 = xmalloc(session_id2_len);
271: memcpy(session_id2, hash, session_id2_len);
1.11 markus 272: }
273:
1.22 provos 274: /* diffie-hellman-group-exchange-sha1 */
275:
276: /*
277: * Estimates the group order for a Diffie-Hellman group that has an
278: * attack complexity approximately the same as O(2**bits). Estimate
279: * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3)))
280: */
281:
282: int
283: dh_estimate(int bits)
284: {
285:
286: if (bits < 64)
287: return (512); /* O(2**63) */
288: if (bits < 128)
289: return (1024); /* O(2**86) */
290: if (bits < 192)
291: return (2048); /* O(2**116) */
292: return (4096); /* O(2**156) */
293: }
294:
1.11 markus 295: void
1.22 provos 296: ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
297: Buffer *client_kexinit, Buffer *server_kexinit)
1.11 markus 298: {
1.22 provos 299: #ifdef DEBUG_KEXDH
300: int i;
301: #endif
302: int plen, dlen;
303: unsigned int klen, kout;
304: char *signature = NULL;
305: unsigned int slen, nbits;
306: char *server_host_key_blob = NULL;
307: Key *server_host_key;
308: unsigned int sbloblen;
309: DH *dh;
310: BIGNUM *dh_server_pub = 0;
311: BIGNUM *shared_secret = 0;
312: BIGNUM *p = 0, *g = 0;
313: unsigned char *kbuf;
314: unsigned char *hash;
315:
1.24 markus 316: nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8);
1.22 provos 317:
318: debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST.");
319: packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
320: packet_put_int(nbits);
321: packet_send();
322: packet_write_wait();
1.11 markus 323:
1.22 provos 324: #ifdef DEBUG_KEXDH
325: fprintf(stderr, "\nnbits = %d", nbits);
326: #endif
1.11 markus 327:
1.22 provos 328: debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP.");
1.11 markus 329:
1.22 provos 330: packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP);
1.11 markus 331:
1.22 provos 332: debug("Got SSH2_MSG_KEX_DH_GEX_GROUP.");
1.11 markus 333:
1.22 provos 334: if ((p = BN_new()) == NULL)
335: fatal("BN_new");
336: packet_get_bignum2(p, &dlen);
337: if ((g = BN_new()) == NULL)
338: fatal("BN_new");
339: packet_get_bignum2(g, &dlen);
340: if ((dh = dh_new_group(g, p)) == NULL)
341: fatal("dh_new_group");
1.1 markus 342:
1.22 provos 343: #ifdef DEBUG_KEXDH
344: fprintf(stderr, "\np= ");
345: BN_print_fp(stderr, dh->p);
346: fprintf(stderr, "\ng= ");
347: BN_print_fp(stderr, dh->g);
348: fprintf(stderr, "\npub= ");
349: BN_print_fp(stderr, dh->pub_key);
350: fprintf(stderr, "\n");
351: DHparams_print_fp(stderr, dh);
352: #endif
1.1 markus 353:
1.22 provos 354: debug("Sending SSH2_MSG_KEX_DH_GEX_INIT.");
355: /* generate and send 'e', client DH public key */
356: packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
357: packet_put_bignum2(dh->pub_key);
1.1 markus 358: packet_send();
359: packet_write_wait();
360:
1.22 provos 361: debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY.");
362:
363: packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY);
364:
365: debug("Got SSH2_MSG_KEXDH_REPLY.");
366:
367: /* key, cert */
368: server_host_key_blob = packet_get_string(&sbloblen);
369: server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
370: if (server_host_key == NULL)
371: fatal("cannot decode server_host_key_blob");
372:
373: check_host_key(host, hostaddr, server_host_key,
374: options.user_hostfile2, options.system_hostfile2);
375:
376: /* DH paramter f, server public DH key */
377: dh_server_pub = BN_new();
378: if (dh_server_pub == NULL)
379: fatal("dh_server_pub == NULL");
380: packet_get_bignum2(dh_server_pub, &dlen);
381:
382: #ifdef DEBUG_KEXDH
383: fprintf(stderr, "\ndh_server_pub= ");
384: BN_print_fp(stderr, dh_server_pub);
385: fprintf(stderr, "\n");
386: debug("bits %d", BN_num_bits(dh_server_pub));
387: #endif
388:
389: /* signed H */
390: signature = packet_get_string(&slen);
391: packet_done();
392:
393: if (!dh_pub_is_valid(dh, dh_server_pub))
394: packet_disconnect("bad server public DH value");
395:
396: klen = DH_size(dh);
397: kbuf = xmalloc(klen);
398: kout = DH_compute_key(kbuf, dh_server_pub, dh);
399: #ifdef DEBUG_KEXDH
400: debug("shared secret: len %d/%d", klen, kout);
401: fprintf(stderr, "shared secret == ");
402: for (i = 0; i< kout; i++)
403: fprintf(stderr, "%02x", (kbuf[i])&0xff);
404: fprintf(stderr, "\n");
405: #endif
406: shared_secret = BN_new();
407:
408: BN_bin2bn(kbuf, kout, shared_secret);
409: memset(kbuf, 0, klen);
410: xfree(kbuf);
411:
412: /* calc and verify H */
413: hash = kex_hash_gex(
414: client_version_string,
415: server_version_string,
416: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
417: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
418: server_host_key_blob, sbloblen,
419: nbits, dh->p, dh->g,
420: dh->pub_key,
421: dh_server_pub,
422: shared_secret
423: );
424: xfree(server_host_key_blob);
425: DH_free(dh);
1.1 markus 426: #ifdef DEBUG_KEXDH
1.22 provos 427: fprintf(stderr, "hash == ");
428: for (i = 0; i< 20; i++)
429: fprintf(stderr, "%02x", (hash[i])&0xff);
430: fprintf(stderr, "\n");
1.1 markus 431: #endif
1.22 provos 432: if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
433: fatal("dsa_verify failed for server_host_key");
434: key_free(server_host_key);
435:
436: kex_derive_keys(kex, hash, shared_secret);
437: packet_set_kex(kex);
438:
439: /* save session id */
440: session_id2_len = 20;
441: session_id2 = xmalloc(session_id2_len);
442: memcpy(session_id2, hash, session_id2_len);
1.1 markus 443: }
1.11 markus 444:
1.1 markus 445: /*
446: * Authenticate user
447: */
1.20 markus 448:
449: typedef struct Authctxt Authctxt;
450: typedef struct Authmethod Authmethod;
451:
452: typedef int sign_cb_fn(
453: Authctxt *authctxt, Key *key,
454: unsigned char **sigp, int *lenp, unsigned char *data, int datalen);
455:
456: struct Authctxt {
457: const char *server_user;
458: const char *host;
459: const char *service;
460: AuthenticationConnection *agent;
1.23 markus 461: Authmethod *method;
1.20 markus 462: int success;
463: };
464: struct Authmethod {
465: char *name; /* string to compare against server's list */
466: int (*userauth)(Authctxt *authctxt);
467: int *enabled; /* flag in option struct that enables method */
468: int *batch_flag; /* flag in option struct that disables method */
469: };
470:
471: void input_userauth_success(int type, int plen, void *ctxt);
472: void input_userauth_failure(int type, int plen, void *ctxt);
473: void input_userauth_error(int type, int plen, void *ctxt);
1.23 markus 474: void input_userauth_info_req(int type, int plen, void *ctxt);
475:
476: int userauth_none(Authctxt *authctxt);
1.20 markus 477: int userauth_pubkey(Authctxt *authctxt);
478: int userauth_passwd(Authctxt *authctxt);
1.23 markus 479: int userauth_kbdint(Authctxt *authctxt);
1.20 markus 480:
481: void authmethod_clear();
1.23 markus 482: Authmethod *authmethod_get(char *authlist);
483: Authmethod *authmethod_lookup(const char *name);
1.20 markus 484:
485: Authmethod authmethods[] = {
486: {"publickey",
487: userauth_pubkey,
488: &options.dsa_authentication,
489: NULL},
490: {"password",
491: userauth_passwd,
492: &options.password_authentication,
493: &options.batch_mode},
1.23 markus 494: {"keyboard-interactive",
495: userauth_kbdint,
496: &options.kbd_interactive_authentication,
497: &options.batch_mode},
498: {"none",
499: userauth_none,
500: NULL,
501: NULL},
1.20 markus 502: {NULL, NULL, NULL, NULL}
503: };
504:
505: void
506: ssh_userauth2(const char *server_user, char *host)
507: {
508: Authctxt authctxt;
509: int type;
510: int plen;
511:
512: debug("send SSH2_MSG_SERVICE_REQUEST");
513: packet_start(SSH2_MSG_SERVICE_REQUEST);
514: packet_put_cstring("ssh-userauth");
515: packet_send();
516: packet_write_wait();
517: type = packet_read(&plen);
518: if (type != SSH2_MSG_SERVICE_ACCEPT) {
519: fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
520: }
521: if (packet_remaining() > 0) {
522: char *reply = packet_get_string(&plen);
523: debug("service_accept: %s", reply);
524: xfree(reply);
525: packet_done();
526: } else {
527: debug("buggy server: service_accept w/o service");
528: }
529: packet_done();
530: debug("got SSH2_MSG_SERVICE_ACCEPT");
531:
532: /* setup authentication context */
533: authctxt.agent = ssh_get_authentication_connection();
534: authctxt.server_user = server_user;
535: authctxt.host = host;
536: authctxt.service = "ssh-connection"; /* service name */
537: authctxt.success = 0;
1.23 markus 538: authctxt.method = authmethod_lookup("none");
539: if (authctxt.method == NULL)
540: fatal("ssh_userauth2: internal error: cannot send userauth none request");
541: authmethod_clear();
1.20 markus 542:
543: /* initial userauth request */
1.23 markus 544: userauth_none(&authctxt);
1.20 markus 545:
546: dispatch_init(&input_userauth_error);
547: dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
548: dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
549: dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
550:
551: if (authctxt.agent != NULL)
552: ssh_close_authentication_connection(authctxt.agent);
553:
1.23 markus 554: debug("ssh-userauth2 successfull: method %s", authctxt.method->name);
1.20 markus 555: }
556: void
557: input_userauth_error(int type, int plen, void *ctxt)
558: {
559: fatal("input_userauth_error: bad message during authentication");
560: }
561: void
562: input_userauth_success(int type, int plen, void *ctxt)
563: {
564: Authctxt *authctxt = ctxt;
565: if (authctxt == NULL)
566: fatal("input_userauth_success: no authentication context");
567: authctxt->success = 1; /* break out */
568: }
569: void
570: input_userauth_failure(int type, int plen, void *ctxt)
571: {
572: Authmethod *method = NULL;
573: Authctxt *authctxt = ctxt;
574: char *authlist = NULL;
575: int partial;
576:
577: if (authctxt == NULL)
578: fatal("input_userauth_failure: no authentication context");
579:
1.23 markus 580: authlist = packet_get_string(NULL);
1.20 markus 581: partial = packet_get_char();
582: packet_done();
583:
584: if (partial != 0)
585: debug("partial success");
586: debug("authentications that can continue: %s", authlist);
587:
588: for (;;) {
589: method = authmethod_get(authlist);
590: if (method == NULL)
591: fatal("Unable to find an authentication method");
1.23 markus 592: authctxt->method = method;
1.20 markus 593: if (method->userauth(authctxt) != 0) {
1.23 markus 594: debug2("we sent a %s packet, wait for reply", method->name);
1.20 markus 595: break;
596: } else {
597: debug2("we did not send a packet, disable method");
598: method->enabled = NULL;
599: }
600: }
601: xfree(authlist);
602: }
603:
1.1 markus 604: int
1.23 markus 605: userauth_none(Authctxt *authctxt)
606: {
607: /* initial userauth request */
608: packet_start(SSH2_MSG_USERAUTH_REQUEST);
609: packet_put_cstring(authctxt->server_user);
610: packet_put_cstring(authctxt->service);
611: packet_put_cstring(authctxt->method->name);
612: packet_send();
613: packet_write_wait();
614: return 1;
615: }
616:
617: int
1.20 markus 618: userauth_passwd(Authctxt *authctxt)
1.1 markus 619: {
1.6 markus 620: static int attempt = 0;
1.1 markus 621: char prompt[80];
622: char *password;
1.6 markus 623:
1.13 todd 624: if (attempt++ >= options.number_of_password_prompts)
1.6 markus 625: return 0;
1.13 todd 626:
627: if(attempt != 1)
628: error("Permission denied, please try again.");
1.1 markus 629:
630: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1.20 markus 631: authctxt->server_user, authctxt->host);
1.1 markus 632: password = read_passphrase(prompt, 0);
633: packet_start(SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 634: packet_put_cstring(authctxt->server_user);
635: packet_put_cstring(authctxt->service);
1.23 markus 636: packet_put_cstring(authctxt->method->name);
1.1 markus 637: packet_put_char(0);
638: packet_put_cstring(password);
639: memset(password, 0, strlen(password));
640: xfree(password);
641: packet_send();
642: packet_write_wait();
643: return 1;
644: }
645:
1.17 markus 646: int
1.20 markus 647: sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
1.1 markus 648: {
649: Buffer b;
650: unsigned char *blob, *signature;
651: int bloblen, slen;
1.14 markus 652: int skip = 0;
1.17 markus 653: int ret = -1;
1.23 markus 654: int have_sig = 1;
1.1 markus 655:
656: dsa_make_key_blob(k, &blob, &bloblen);
657:
658: /* data to be signed */
659: buffer_init(&b);
1.14 markus 660: if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) {
661: buffer_put_string(&b, session_id2, session_id2_len);
662: skip = buffer_len(&b);
663: } else {
664: buffer_append(&b, session_id2, session_id2_len);
665: skip = session_id2_len;
666: }
1.1 markus 667: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 668: buffer_put_cstring(&b, authctxt->server_user);
1.10 markus 669: buffer_put_cstring(&b,
670: datafellows & SSH_BUG_PUBKEYAUTH ?
671: "ssh-userauth" :
1.20 markus 672: authctxt->service);
1.23 markus 673: buffer_put_cstring(&b, authctxt->method->name);
674: buffer_put_char(&b, have_sig);
1.1 markus 675: buffer_put_cstring(&b, KEX_DSS);
676: buffer_put_string(&b, blob, bloblen);
677:
678: /* generate signature */
1.20 markus 679: ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
1.17 markus 680: if (ret == -1) {
681: xfree(blob);
682: buffer_free(&b);
683: return 0;
684: }
1.1 markus 685: #ifdef DEBUG_DSS
686: buffer_dump(&b);
687: #endif
1.10 markus 688: if (datafellows & SSH_BUG_PUBKEYAUTH) {
689: buffer_clear(&b);
690: buffer_append(&b, session_id2, session_id2_len);
691: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 692: buffer_put_cstring(&b, authctxt->server_user);
693: buffer_put_cstring(&b, authctxt->service);
1.23 markus 694: buffer_put_cstring(&b, authctxt->method->name);
695: buffer_put_char(&b, have_sig);
1.10 markus 696: buffer_put_cstring(&b, KEX_DSS);
697: buffer_put_string(&b, blob, bloblen);
698: }
699: xfree(blob);
1.1 markus 700: /* append signature */
701: buffer_put_string(&b, signature, slen);
702: xfree(signature);
703:
704: /* skip session id and packet type */
1.14 markus 705: if (buffer_len(&b) < skip + 1)
1.20 markus 706: fatal("userauth_pubkey: internal error");
1.14 markus 707: buffer_consume(&b, skip + 1);
1.1 markus 708:
709: /* put remaining data from buffer into packet */
710: packet_start(SSH2_MSG_USERAUTH_REQUEST);
711: packet_put_raw(buffer_ptr(&b), buffer_len(&b));
712: buffer_free(&b);
713:
714: /* send */
715: packet_send();
716: packet_write_wait();
1.17 markus 717:
718: return 1;
1.16 markus 719: }
720:
1.20 markus 721: /* sign callback */
722: int dsa_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp,
723: unsigned char *data, int datalen)
724: {
725: return dsa_sign(key, sigp, lenp, data, datalen);
726: }
727:
1.16 markus 728: int
1.20 markus 729: userauth_pubkey_identity(Authctxt *authctxt, char *filename)
1.16 markus 730: {
731: Key *k;
1.20 markus 732: int i, ret, try_next;
1.16 markus 733: struct stat st;
734:
735: if (stat(filename, &st) != 0) {
736: debug("key does not exist: %s", filename);
737: return 0;
738: }
739: debug("try pubkey: %s", filename);
740:
741: k = key_new(KEY_DSA);
742: if (!load_private_key(filename, "", k, NULL)) {
743: int success = 0;
744: char *passphrase;
745: char prompt[300];
746: snprintf(prompt, sizeof prompt,
1.21 markus 747: "Enter passphrase for %s key '%.100s': ",
748: key_type(k), filename);
1.20 markus 749: for (i = 0; i < options.number_of_password_prompts; i++) {
750: passphrase = read_passphrase(prompt, 0);
751: if (strcmp(passphrase, "") != 0) {
752: success = load_private_key(filename, passphrase, k, NULL);
753: try_next = 0;
754: } else {
755: debug2("no passphrase given, try next key");
756: try_next = 1;
757: }
758: memset(passphrase, 0, strlen(passphrase));
759: xfree(passphrase);
760: if (success || try_next)
761: break;
762: debug2("bad passphrase given, try again...");
763: }
1.16 markus 764: if (!success) {
765: key_free(k);
766: return 0;
767: }
768: }
1.20 markus 769: ret = sign_and_send_pubkey(authctxt, k, dsa_sign_cb);
1.17 markus 770: key_free(k);
771: return ret;
772: }
773:
1.20 markus 774: /* sign callback */
775: int agent_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp,
1.17 markus 776: unsigned char *data, int datalen)
777: {
1.20 markus 778: return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen);
1.17 markus 779: }
780:
781: int
1.20 markus 782: userauth_pubkey_agent(Authctxt *authctxt)
1.17 markus 783: {
784: static int called = 0;
785: char *comment;
786: Key *k;
787: int ret;
788:
789: if (called == 0) {
1.20 markus 790: k = ssh_get_first_identity(authctxt->agent, &comment, 2);
791: called = 1;
1.17 markus 792: } else {
1.20 markus 793: k = ssh_get_next_identity(authctxt->agent, &comment, 2);
1.17 markus 794: }
1.20 markus 795: if (k == NULL) {
796: debug2("no more DSA keys from agent");
1.17 markus 797: return 0;
1.20 markus 798: }
1.17 markus 799: debug("trying DSA agent key %s", comment);
800: xfree(comment);
1.20 markus 801: ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb);
1.17 markus 802: key_free(k);
803: return ret;
1.1 markus 804: }
805:
1.20 markus 806: int
807: userauth_pubkey(Authctxt *authctxt)
808: {
809: static int idx = 0;
810: int sent = 0;
811:
812: if (authctxt->agent != NULL)
813: sent = userauth_pubkey_agent(authctxt);
814: while (sent == 0 && idx < options.num_identity_files2)
815: sent = userauth_pubkey_identity(authctxt, options.identity_files2[idx++]);
816: return sent;
817: }
818:
1.23 markus 819: /*
820: * Send userauth request message specifying keyboard-interactive method.
821: */
822: int
823: userauth_kbdint(Authctxt *authctxt)
824: {
825: static int attempt = 0;
826:
827: if (attempt++ >= options.number_of_password_prompts)
828: return 0;
829:
830: debug2("userauth_kbdint");
831: packet_start(SSH2_MSG_USERAUTH_REQUEST);
832: packet_put_cstring(authctxt->server_user);
833: packet_put_cstring(authctxt->service);
834: packet_put_cstring(authctxt->method->name);
835: packet_put_cstring(""); /* lang */
836: packet_put_cstring(options.kbd_interactive_devices ?
837: options.kbd_interactive_devices : "");
838: packet_send();
839: packet_write_wait();
840:
841: dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
842: return 1;
843: }
844:
845: /*
846: * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send
847: * SSH2_MSG_USERAUTH_INFO_RESPONSE
848: */
849: void
850: input_userauth_info_req(int type, int plen, void *ctxt)
851: {
852: Authctxt *authctxt = ctxt;
853: char *name = NULL;
854: char *inst = NULL;
855: char *lang = NULL;
856: char *prompt = NULL;
857: char *response = NULL;
858: unsigned int num_prompts, i;
859: int echo = 0;
860:
861: debug2("input_userauth_info_req");
862:
863: if (authctxt == NULL)
864: fatal("input_userauth_info_req: no authentication context");
865:
866: name = packet_get_string(NULL);
867: inst = packet_get_string(NULL);
868: lang = packet_get_string(NULL);
869:
870: if (strlen(name) > 0)
871: cli_mesg(name);
872: xfree(name);
873:
874: if (strlen(inst) > 0)
875: cli_mesg(inst);
876: xfree(inst);
877: xfree(lang); /* unused */
878:
879: num_prompts = packet_get_int();
880: /*
881: * Begin to build info response packet based on prompts requested.
882: * We commit to providing the correct number of responses, so if
883: * further on we run into a problem that prevents this, we have to
884: * be sure and clean this up and send a correct error response.
885: */
886: packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
887: packet_put_int(num_prompts);
888:
889: for (i = 0; i < num_prompts; i++) {
890: prompt = packet_get_string(NULL);
891: echo = packet_get_char();
892:
893: response = cli_prompt(prompt, echo);
894:
895: packet_put_cstring(response);
896: memset(response, 0, strlen(response));
897: xfree(response);
898: xfree(prompt);
899: }
900: packet_done(); /* done with parsing incoming message. */
901:
902: packet_send();
903: packet_write_wait();
904: }
1.20 markus 905:
906: /* find auth method */
907:
908: #define DELIM ","
909:
910: static char *def_authlist = "publickey,password";
911: static char *authlist_current = NULL; /* clean copy used for comparison */
912: static char *authname_current = NULL; /* last used auth method */
913: static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */
914: static char *authlist_state = NULL; /* state variable for strtok_r() */
915:
916: /*
917: * Before starting to use a new authentication method list sent by the
918: * server, reset internal variables. This should also be called when
919: * finished processing server list to free resources.
920: */
1.1 markus 921: void
1.20 markus 922: authmethod_clear()
923: {
924: if (authlist_current != NULL) {
925: xfree(authlist_current);
926: authlist_current = NULL;
927: }
928: if (authlist_working != NULL) {
929: xfree(authlist_working);
930: authlist_working = NULL;
931: }
932: if (authname_current != NULL) {
933: xfree(authname_current);
934: authlist_state = NULL;
935: }
936: if (authlist_state != NULL)
937: authlist_state = NULL;
938: return;
939: }
940:
941: /*
942: * given auth method name, if configurable options permit this method fill
943: * in auth_ident field and return true, otherwise return false.
944: */
945: int
946: authmethod_is_enabled(Authmethod *method)
947: {
948: if (method == NULL)
949: return 0;
950: /* return false if options indicate this method is disabled */
951: if (method->enabled == NULL || *method->enabled == 0)
952: return 0;
953: /* return false if batch mode is enabled but method needs interactive mode */
954: if (method->batch_flag != NULL && *method->batch_flag != 0)
955: return 0;
956: return 1;
957: }
958:
959: Authmethod *
960: authmethod_lookup(const char *name)
1.1 markus 961: {
1.20 markus 962: Authmethod *method = NULL;
963: if (name != NULL)
964: for (method = authmethods; method->name != NULL; method++)
965: if (strcmp(name, method->name) == 0)
966: return method;
967: debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
968: return NULL;
969: }
1.1 markus 970:
1.20 markus 971: /*
972: * Given the authentication method list sent by the server, return the
973: * next method we should try. If the server initially sends a nil list,
974: * use a built-in default list. If the server sends a nil list after
975: * previously sending a valid list, continue using the list originally
976: * sent.
977: */
1.1 markus 978:
1.20 markus 979: Authmethod *
980: authmethod_get(char *authlist)
981: {
982: char *name = NULL;
983: Authmethod *method = NULL;
984:
985: /* Use a suitable default if we're passed a nil list. */
986: if (authlist == NULL || strlen(authlist) == 0)
987: authlist = def_authlist;
988:
989: if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) {
990: /* start over if passed a different list */
1.23 markus 991: debug3("start over, passed a different list");
1.20 markus 992: authmethod_clear();
993: authlist_current = xstrdup(authlist);
994: authlist_working = xstrdup(authlist);
995: name = strtok_r(authlist_working, DELIM, &authlist_state);
996: } else {
997: /*
998: * try to use previously used authentication method
999: * or continue to use previously passed list
1000: */
1001: name = (authname_current != NULL) ?
1002: authname_current : strtok_r(NULL, DELIM, &authlist_state);
1.1 markus 1003: }
1.20 markus 1004:
1005: while (name != NULL) {
1.23 markus 1006: debug3("authmethod_lookup %s", name);
1.20 markus 1007: method = authmethod_lookup(name);
1.23 markus 1008: if (method != NULL && authmethod_is_enabled(method)) {
1009: debug3("authmethod_is_enabled %s", name);
1.20 markus 1010: break;
1.23 markus 1011: }
1.20 markus 1012: name = strtok_r(NULL, DELIM, &authlist_state);
1.23 markus 1013: method = NULL;
1.1 markus 1014: }
1015:
1.20 markus 1016: if (authname_current != NULL)
1017: xfree(authname_current);
1.1 markus 1018:
1.23 markus 1019: if (method != NULL) {
1.20 markus 1020: debug("next auth method to try is %s", name);
1021: authname_current = xstrdup(name);
1022: return method;
1023: } else {
1024: debug("no more auth methods to try");
1025: authname_current = NULL;
1026: return NULL;
1.1 markus 1027: }
1028: }