Annotation of src/usr.bin/ssh/sshconnect2.c, Revision 1.29
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"
1.29 ! markus 26: RCSID("$OpenBSD: sshconnect2.c,v 1.28 2000/11/12 19:50:38 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 "sshconnect.h"
49: #include "authfile.h"
1.23 markus 50: #include "cli.h"
1.20 markus 51: #include "dispatch.h"
1.17 markus 52: #include "authfd.h"
1.1 markus 53:
1.22 provos 54: void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *);
55: void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *);
56:
1.1 markus 57: /* import */
58: extern char *client_version_string;
59: extern char *server_version_string;
60: extern Options options;
61:
62: /*
63: * SSH2 key exchange
64: */
65:
66: unsigned char *session_id2 = NULL;
67: int session_id2_len = 0;
68:
69: void
1.22 provos 70: ssh_kex2(char *host, struct sockaddr *hostaddr)
71: {
72: int i, plen;
73: Kex *kex;
74: Buffer *client_kexinit, *server_kexinit;
75: char *sprop[PROPOSAL_MAX];
76:
1.29 ! markus 77: if (options.ciphers == (char *)-1) {
! 78: log("No valid ciphers for protocol version 2 given, using defaults.");
! 79: options.ciphers = NULL;
1.24 markus 80: }
1.22 provos 81: if (options.ciphers != NULL) {
82: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
83: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
84: }
85: if (options.compression) {
86: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
87: myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
88: } else {
89: myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
90: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
91: }
92:
93: /* buffers with raw kexinit messages */
94: server_kexinit = xmalloc(sizeof(*server_kexinit));
95: buffer_init(server_kexinit);
96: client_kexinit = kex_init(myproposal);
97:
98: /* algorithm negotiation */
99: kex_exchange_kexinit(client_kexinit, server_kexinit, sprop);
100: kex = kex_choose_conf(myproposal, sprop, 0);
101: for (i = 0; i < PROPOSAL_MAX; i++)
102: xfree(sprop[i]);
103:
104: /* server authentication and session key agreement */
105: switch(kex->kex_type) {
106: case DH_GRP1_SHA1:
107: ssh_dh1_client(kex, host, hostaddr,
108: client_kexinit, server_kexinit);
109: break;
110: case DH_GEX_SHA1:
111: ssh_dhgex_client(kex, host, hostaddr, client_kexinit,
112: server_kexinit);
113: break;
114: default:
115: fatal("Unsupported key exchange %d", kex->kex_type);
116: }
117:
118: buffer_free(client_kexinit);
119: buffer_free(server_kexinit);
120: xfree(client_kexinit);
121: xfree(server_kexinit);
122:
123: debug("Wait SSH2_MSG_NEWKEYS.");
124: packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
125: packet_done();
126: debug("GOT SSH2_MSG_NEWKEYS.");
127:
128: debug("send SSH2_MSG_NEWKEYS.");
129: packet_start(SSH2_MSG_NEWKEYS);
130: packet_send();
131: packet_write_wait();
132: debug("done: send SSH2_MSG_NEWKEYS.");
133:
134: #ifdef DEBUG_KEXDH
135: /* send 1st encrypted/maced/compressed message */
136: packet_start(SSH2_MSG_IGNORE);
137: packet_put_cstring("markus");
138: packet_send();
139: packet_write_wait();
140: #endif
141: debug("done: KEX2.");
142: }
143:
144: /* diffie-hellman-group1-sha1 */
145:
146: void
147: ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr,
148: Buffer *client_kexinit, Buffer *server_kexinit)
1.1 markus 149: {
1.19 markus 150: #ifdef DEBUG_KEXDH
151: int i;
152: #endif
1.11 markus 153: int plen, dlen;
1.1 markus 154: unsigned int klen, kout;
155: char *signature = NULL;
156: unsigned int slen;
157: char *server_host_key_blob = NULL;
158: Key *server_host_key;
159: unsigned int sbloblen;
160: DH *dh;
161: BIGNUM *dh_server_pub = 0;
162: BIGNUM *shared_secret = 0;
163: unsigned char *kbuf;
164: unsigned char *hash;
165:
166: debug("Sending SSH2_MSG_KEXDH_INIT.");
167: /* generate and send 'e', client DH public key */
168: dh = dh_new_group1();
169: packet_start(SSH2_MSG_KEXDH_INIT);
170: packet_put_bignum2(dh->pub_key);
171: packet_send();
172: packet_write_wait();
173:
174: #ifdef DEBUG_KEXDH
175: fprintf(stderr, "\np= ");
1.19 markus 176: BN_print_fp(stderr, dh->p);
1.1 markus 177: fprintf(stderr, "\ng= ");
1.19 markus 178: BN_print_fp(stderr, dh->g);
1.1 markus 179: fprintf(stderr, "\npub= ");
1.19 markus 180: BN_print_fp(stderr, dh->pub_key);
1.1 markus 181: fprintf(stderr, "\n");
182: DHparams_print_fp(stderr, dh);
183: #endif
184:
185: debug("Wait SSH2_MSG_KEXDH_REPLY.");
186:
1.11 markus 187: packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
1.1 markus 188:
189: debug("Got SSH2_MSG_KEXDH_REPLY.");
190:
191: /* key, cert */
192: server_host_key_blob = packet_get_string(&sbloblen);
1.28 markus 193: server_host_key = key_from_blob(server_host_key_blob, sbloblen);
1.1 markus 194: if (server_host_key == NULL)
195: fatal("cannot decode server_host_key_blob");
196:
197: check_host_key(host, hostaddr, server_host_key,
1.22 provos 198: options.user_hostfile2, options.system_hostfile2);
1.1 markus 199:
200: /* DH paramter f, server public DH key */
201: dh_server_pub = BN_new();
202: if (dh_server_pub == NULL)
203: fatal("dh_server_pub == NULL");
204: packet_get_bignum2(dh_server_pub, &dlen);
205:
206: #ifdef DEBUG_KEXDH
207: fprintf(stderr, "\ndh_server_pub= ");
1.19 markus 208: BN_print_fp(stderr, dh_server_pub);
1.1 markus 209: fprintf(stderr, "\n");
210: debug("bits %d", BN_num_bits(dh_server_pub));
211: #endif
212:
213: /* signed H */
214: signature = packet_get_string(&slen);
215: packet_done();
216:
217: if (!dh_pub_is_valid(dh, dh_server_pub))
218: packet_disconnect("bad server public DH value");
219:
220: klen = DH_size(dh);
221: kbuf = xmalloc(klen);
222: kout = DH_compute_key(kbuf, dh_server_pub, dh);
223: #ifdef DEBUG_KEXDH
224: debug("shared secret: len %d/%d", klen, kout);
225: fprintf(stderr, "shared secret == ");
226: for (i = 0; i< kout; i++)
227: fprintf(stderr, "%02x", (kbuf[i])&0xff);
228: fprintf(stderr, "\n");
229: #endif
230: shared_secret = BN_new();
231:
232: BN_bin2bn(kbuf, kout, shared_secret);
233: memset(kbuf, 0, klen);
234: xfree(kbuf);
235:
236: /* calc and verify H */
237: hash = kex_hash(
238: client_version_string,
239: server_version_string,
240: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
241: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
242: server_host_key_blob, sbloblen,
243: dh->pub_key,
244: dh_server_pub,
245: shared_secret
246: );
1.3 markus 247: xfree(server_host_key_blob);
1.11 markus 248: DH_free(dh);
1.1 markus 249: #ifdef DEBUG_KEXDH
250: fprintf(stderr, "hash == ");
251: for (i = 0; i< 20; i++)
252: fprintf(stderr, "%02x", (hash[i])&0xff);
253: fprintf(stderr, "\n");
254: #endif
1.28 markus 255: if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
256: fatal("key_verify failed for server_host_key");
1.1 markus 257: key_free(server_host_key);
258:
259: kex_derive_keys(kex, hash, shared_secret);
260: packet_set_kex(kex);
261:
262: /* save session id */
263: session_id2_len = 20;
264: session_id2 = xmalloc(session_id2_len);
265: memcpy(session_id2, hash, session_id2_len);
1.11 markus 266: }
267:
1.22 provos 268: /* diffie-hellman-group-exchange-sha1 */
269:
270: /*
271: * Estimates the group order for a Diffie-Hellman group that has an
272: * attack complexity approximately the same as O(2**bits). Estimate
273: * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3)))
274: */
275:
276: int
277: dh_estimate(int bits)
278: {
279:
280: if (bits < 64)
281: return (512); /* O(2**63) */
282: if (bits < 128)
283: return (1024); /* O(2**86) */
284: if (bits < 192)
285: return (2048); /* O(2**116) */
286: return (4096); /* O(2**156) */
287: }
288:
1.11 markus 289: void
1.22 provos 290: ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
291: Buffer *client_kexinit, Buffer *server_kexinit)
1.11 markus 292: {
1.22 provos 293: #ifdef DEBUG_KEXDH
294: int i;
295: #endif
296: int plen, dlen;
297: unsigned int klen, kout;
298: char *signature = NULL;
299: unsigned int slen, nbits;
300: char *server_host_key_blob = NULL;
301: Key *server_host_key;
302: unsigned int sbloblen;
303: DH *dh;
304: BIGNUM *dh_server_pub = 0;
305: BIGNUM *shared_secret = 0;
306: BIGNUM *p = 0, *g = 0;
307: unsigned char *kbuf;
308: unsigned char *hash;
309:
1.24 markus 310: nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8);
1.22 provos 311:
312: debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST.");
313: packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
314: packet_put_int(nbits);
315: packet_send();
316: packet_write_wait();
1.11 markus 317:
1.22 provos 318: #ifdef DEBUG_KEXDH
319: fprintf(stderr, "\nnbits = %d", nbits);
320: #endif
1.11 markus 321:
1.22 provos 322: debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP.");
1.11 markus 323:
1.22 provos 324: packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP);
1.11 markus 325:
1.22 provos 326: debug("Got SSH2_MSG_KEX_DH_GEX_GROUP.");
1.11 markus 327:
1.22 provos 328: if ((p = BN_new()) == NULL)
329: fatal("BN_new");
330: packet_get_bignum2(p, &dlen);
331: if ((g = BN_new()) == NULL)
332: fatal("BN_new");
333: packet_get_bignum2(g, &dlen);
334: if ((dh = dh_new_group(g, p)) == NULL)
335: fatal("dh_new_group");
1.1 markus 336:
1.22 provos 337: #ifdef DEBUG_KEXDH
338: fprintf(stderr, "\np= ");
339: BN_print_fp(stderr, dh->p);
340: fprintf(stderr, "\ng= ");
341: BN_print_fp(stderr, dh->g);
342: fprintf(stderr, "\npub= ");
343: BN_print_fp(stderr, dh->pub_key);
344: fprintf(stderr, "\n");
345: DHparams_print_fp(stderr, dh);
346: #endif
1.1 markus 347:
1.22 provos 348: debug("Sending SSH2_MSG_KEX_DH_GEX_INIT.");
349: /* generate and send 'e', client DH public key */
350: packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
351: packet_put_bignum2(dh->pub_key);
1.1 markus 352: packet_send();
353: packet_write_wait();
354:
1.22 provos 355: debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY.");
356:
357: packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY);
358:
359: debug("Got SSH2_MSG_KEXDH_REPLY.");
360:
361: /* key, cert */
362: server_host_key_blob = packet_get_string(&sbloblen);
1.28 markus 363: server_host_key = key_from_blob(server_host_key_blob, sbloblen);
1.22 provos 364: if (server_host_key == NULL)
365: fatal("cannot decode server_host_key_blob");
366:
367: check_host_key(host, hostaddr, server_host_key,
368: options.user_hostfile2, options.system_hostfile2);
369:
370: /* DH paramter f, server public DH key */
371: dh_server_pub = BN_new();
372: if (dh_server_pub == NULL)
373: fatal("dh_server_pub == NULL");
374: packet_get_bignum2(dh_server_pub, &dlen);
375:
376: #ifdef DEBUG_KEXDH
377: fprintf(stderr, "\ndh_server_pub= ");
378: BN_print_fp(stderr, dh_server_pub);
379: fprintf(stderr, "\n");
380: debug("bits %d", BN_num_bits(dh_server_pub));
381: #endif
382:
383: /* signed H */
384: signature = packet_get_string(&slen);
385: packet_done();
386:
387: if (!dh_pub_is_valid(dh, dh_server_pub))
388: packet_disconnect("bad server public DH value");
389:
390: klen = DH_size(dh);
391: kbuf = xmalloc(klen);
392: kout = DH_compute_key(kbuf, dh_server_pub, dh);
393: #ifdef DEBUG_KEXDH
394: debug("shared secret: len %d/%d", klen, kout);
395: fprintf(stderr, "shared secret == ");
396: for (i = 0; i< kout; i++)
397: fprintf(stderr, "%02x", (kbuf[i])&0xff);
398: fprintf(stderr, "\n");
399: #endif
400: shared_secret = BN_new();
401:
402: BN_bin2bn(kbuf, kout, shared_secret);
403: memset(kbuf, 0, klen);
404: xfree(kbuf);
405:
406: /* calc and verify H */
407: hash = kex_hash_gex(
408: client_version_string,
409: server_version_string,
410: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
411: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
412: server_host_key_blob, sbloblen,
413: nbits, dh->p, dh->g,
414: dh->pub_key,
415: dh_server_pub,
416: shared_secret
417: );
418: xfree(server_host_key_blob);
419: DH_free(dh);
1.1 markus 420: #ifdef DEBUG_KEXDH
1.22 provos 421: fprintf(stderr, "hash == ");
422: for (i = 0; i< 20; i++)
423: fprintf(stderr, "%02x", (hash[i])&0xff);
424: fprintf(stderr, "\n");
1.1 markus 425: #endif
1.28 markus 426: if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
427: fatal("key_verify failed for server_host_key");
1.22 provos 428: key_free(server_host_key);
429:
430: kex_derive_keys(kex, hash, shared_secret);
431: packet_set_kex(kex);
432:
433: /* save session id */
434: session_id2_len = 20;
435: session_id2 = xmalloc(session_id2_len);
436: memcpy(session_id2, hash, session_id2_len);
1.1 markus 437: }
1.11 markus 438:
1.1 markus 439: /*
440: * Authenticate user
441: */
1.20 markus 442:
443: typedef struct Authctxt Authctxt;
444: typedef struct Authmethod Authmethod;
445:
446: typedef int sign_cb_fn(
447: Authctxt *authctxt, Key *key,
448: unsigned char **sigp, int *lenp, unsigned char *data, int datalen);
449:
450: struct Authctxt {
451: const char *server_user;
452: const char *host;
453: const char *service;
454: AuthenticationConnection *agent;
1.23 markus 455: Authmethod *method;
1.20 markus 456: int success;
457: };
458: struct Authmethod {
459: char *name; /* string to compare against server's list */
460: int (*userauth)(Authctxt *authctxt);
461: int *enabled; /* flag in option struct that enables method */
462: int *batch_flag; /* flag in option struct that disables method */
463: };
464:
465: void input_userauth_success(int type, int plen, void *ctxt);
466: void input_userauth_failure(int type, int plen, void *ctxt);
467: void input_userauth_error(int type, int plen, void *ctxt);
1.23 markus 468: void input_userauth_info_req(int type, int plen, void *ctxt);
469:
470: int userauth_none(Authctxt *authctxt);
1.20 markus 471: int userauth_pubkey(Authctxt *authctxt);
472: int userauth_passwd(Authctxt *authctxt);
1.23 markus 473: int userauth_kbdint(Authctxt *authctxt);
1.20 markus 474:
475: void authmethod_clear();
1.23 markus 476: Authmethod *authmethod_get(char *authlist);
477: Authmethod *authmethod_lookup(const char *name);
1.20 markus 478:
479: Authmethod authmethods[] = {
480: {"publickey",
481: userauth_pubkey,
1.28 markus 482: &options.pubkey_authentication,
1.20 markus 483: NULL},
484: {"password",
485: userauth_passwd,
486: &options.password_authentication,
487: &options.batch_mode},
1.23 markus 488: {"keyboard-interactive",
489: userauth_kbdint,
490: &options.kbd_interactive_authentication,
491: &options.batch_mode},
492: {"none",
493: userauth_none,
494: NULL,
495: NULL},
1.20 markus 496: {NULL, NULL, NULL, NULL}
497: };
498:
499: void
500: ssh_userauth2(const char *server_user, char *host)
501: {
502: Authctxt authctxt;
503: int type;
504: int plen;
505:
506: debug("send SSH2_MSG_SERVICE_REQUEST");
507: packet_start(SSH2_MSG_SERVICE_REQUEST);
508: packet_put_cstring("ssh-userauth");
509: packet_send();
510: packet_write_wait();
511: type = packet_read(&plen);
512: if (type != SSH2_MSG_SERVICE_ACCEPT) {
513: fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
514: }
515: if (packet_remaining() > 0) {
516: char *reply = packet_get_string(&plen);
517: debug("service_accept: %s", reply);
518: xfree(reply);
519: packet_done();
520: } else {
521: debug("buggy server: service_accept w/o service");
522: }
523: packet_done();
524: debug("got SSH2_MSG_SERVICE_ACCEPT");
525:
526: /* setup authentication context */
527: authctxt.agent = ssh_get_authentication_connection();
528: authctxt.server_user = server_user;
529: authctxt.host = host;
530: authctxt.service = "ssh-connection"; /* service name */
531: authctxt.success = 0;
1.23 markus 532: authctxt.method = authmethod_lookup("none");
533: if (authctxt.method == NULL)
534: fatal("ssh_userauth2: internal error: cannot send userauth none request");
535: authmethod_clear();
1.20 markus 536:
537: /* initial userauth request */
1.23 markus 538: userauth_none(&authctxt);
1.20 markus 539:
540: dispatch_init(&input_userauth_error);
541: dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
542: dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
543: dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
544:
545: if (authctxt.agent != NULL)
546: ssh_close_authentication_connection(authctxt.agent);
547:
1.23 markus 548: debug("ssh-userauth2 successfull: method %s", authctxt.method->name);
1.20 markus 549: }
550: void
551: input_userauth_error(int type, int plen, void *ctxt)
552: {
553: fatal("input_userauth_error: bad message during authentication");
554: }
555: void
556: input_userauth_success(int type, int plen, void *ctxt)
557: {
558: Authctxt *authctxt = ctxt;
559: if (authctxt == NULL)
560: fatal("input_userauth_success: no authentication context");
561: authctxt->success = 1; /* break out */
562: }
563: void
564: input_userauth_failure(int type, int plen, void *ctxt)
565: {
566: Authmethod *method = NULL;
567: Authctxt *authctxt = ctxt;
568: char *authlist = NULL;
569: int partial;
570:
571: if (authctxt == NULL)
572: fatal("input_userauth_failure: no authentication context");
573:
1.23 markus 574: authlist = packet_get_string(NULL);
1.20 markus 575: partial = packet_get_char();
576: packet_done();
577:
578: if (partial != 0)
579: debug("partial success");
580: debug("authentications that can continue: %s", authlist);
581:
582: for (;;) {
583: method = authmethod_get(authlist);
584: if (method == NULL)
585: fatal("Unable to find an authentication method");
1.23 markus 586: authctxt->method = method;
1.20 markus 587: if (method->userauth(authctxt) != 0) {
1.23 markus 588: debug2("we sent a %s packet, wait for reply", method->name);
1.20 markus 589: break;
590: } else {
591: debug2("we did not send a packet, disable method");
592: method->enabled = NULL;
593: }
594: }
595: xfree(authlist);
596: }
597:
1.1 markus 598: int
1.23 markus 599: userauth_none(Authctxt *authctxt)
600: {
601: /* initial userauth request */
602: packet_start(SSH2_MSG_USERAUTH_REQUEST);
603: packet_put_cstring(authctxt->server_user);
604: packet_put_cstring(authctxt->service);
605: packet_put_cstring(authctxt->method->name);
606: packet_send();
607: packet_write_wait();
608: return 1;
609: }
610:
611: int
1.20 markus 612: userauth_passwd(Authctxt *authctxt)
1.1 markus 613: {
1.6 markus 614: static int attempt = 0;
1.1 markus 615: char prompt[80];
616: char *password;
1.6 markus 617:
1.13 todd 618: if (attempt++ >= options.number_of_password_prompts)
1.6 markus 619: return 0;
1.13 todd 620:
621: if(attempt != 1)
622: error("Permission denied, please try again.");
1.1 markus 623:
624: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1.20 markus 625: authctxt->server_user, authctxt->host);
1.1 markus 626: password = read_passphrase(prompt, 0);
627: packet_start(SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 628: packet_put_cstring(authctxt->server_user);
629: packet_put_cstring(authctxt->service);
1.23 markus 630: packet_put_cstring(authctxt->method->name);
1.1 markus 631: packet_put_char(0);
632: packet_put_cstring(password);
633: memset(password, 0, strlen(password));
634: xfree(password);
635: packet_send();
636: packet_write_wait();
637: return 1;
638: }
639:
1.17 markus 640: int
1.20 markus 641: sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
1.1 markus 642: {
643: Buffer b;
644: unsigned char *blob, *signature;
645: int bloblen, slen;
1.14 markus 646: int skip = 0;
1.17 markus 647: int ret = -1;
1.23 markus 648: int have_sig = 1;
1.1 markus 649:
1.28 markus 650: if (key_to_blob(k, &blob, &bloblen) == 0) {
651: /* we cannot handle this key */
652: return 0;
653: }
1.1 markus 654: /* data to be signed */
655: buffer_init(&b);
1.26 markus 656: if (datafellows & SSH_OLD_SESSIONID) {
657: buffer_append(&b, session_id2, session_id2_len);
658: skip = session_id2_len;
659: } else {
1.14 markus 660: buffer_put_string(&b, session_id2, session_id2_len);
661: skip = buffer_len(&b);
662: }
1.1 markus 663: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 664: buffer_put_cstring(&b, authctxt->server_user);
1.10 markus 665: buffer_put_cstring(&b,
666: datafellows & SSH_BUG_PUBKEYAUTH ?
667: "ssh-userauth" :
1.20 markus 668: authctxt->service);
1.23 markus 669: buffer_put_cstring(&b, authctxt->method->name);
670: buffer_put_char(&b, have_sig);
1.28 markus 671: buffer_put_cstring(&b, key_ssh_name(k));
1.1 markus 672: buffer_put_string(&b, blob, bloblen);
673:
674: /* generate signature */
1.20 markus 675: ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
1.17 markus 676: if (ret == -1) {
677: xfree(blob);
678: buffer_free(&b);
679: return 0;
680: }
1.28 markus 681: #ifdef DEBUG_PK
1.1 markus 682: buffer_dump(&b);
683: #endif
1.10 markus 684: if (datafellows & SSH_BUG_PUBKEYAUTH) {
685: buffer_clear(&b);
686: buffer_append(&b, session_id2, session_id2_len);
687: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 688: buffer_put_cstring(&b, authctxt->server_user);
689: buffer_put_cstring(&b, authctxt->service);
1.23 markus 690: buffer_put_cstring(&b, authctxt->method->name);
691: buffer_put_char(&b, have_sig);
1.28 markus 692: buffer_put_cstring(&b, key_ssh_name(k));
1.10 markus 693: buffer_put_string(&b, blob, bloblen);
694: }
695: xfree(blob);
1.1 markus 696: /* append signature */
697: buffer_put_string(&b, signature, slen);
698: xfree(signature);
699:
700: /* skip session id and packet type */
1.14 markus 701: if (buffer_len(&b) < skip + 1)
1.20 markus 702: fatal("userauth_pubkey: internal error");
1.14 markus 703: buffer_consume(&b, skip + 1);
1.1 markus 704:
705: /* put remaining data from buffer into packet */
706: packet_start(SSH2_MSG_USERAUTH_REQUEST);
707: packet_put_raw(buffer_ptr(&b), buffer_len(&b));
708: buffer_free(&b);
709:
710: /* send */
711: packet_send();
712: packet_write_wait();
1.17 markus 713:
714: return 1;
1.16 markus 715: }
716:
1.20 markus 717: /* sign callback */
1.28 markus 718: int key_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp,
1.20 markus 719: unsigned char *data, int datalen)
720: {
1.28 markus 721: return key_sign(key, sigp, lenp, data, datalen);
1.20 markus 722: }
723:
1.16 markus 724: int
1.20 markus 725: userauth_pubkey_identity(Authctxt *authctxt, char *filename)
1.16 markus 726: {
727: Key *k;
1.20 markus 728: int i, ret, try_next;
1.16 markus 729: struct stat st;
730:
731: if (stat(filename, &st) != 0) {
732: debug("key does not exist: %s", filename);
733: return 0;
734: }
735: debug("try pubkey: %s", filename);
736:
1.28 markus 737: k = key_new(KEY_UNSPEC);
1.16 markus 738: if (!load_private_key(filename, "", k, NULL)) {
739: int success = 0;
740: char *passphrase;
741: char prompt[300];
742: snprintf(prompt, sizeof prompt,
1.28 markus 743: "Enter passphrase for key '%.100s': ", filename);
1.20 markus 744: for (i = 0; i < options.number_of_password_prompts; i++) {
745: passphrase = read_passphrase(prompt, 0);
746: if (strcmp(passphrase, "") != 0) {
747: success = load_private_key(filename, passphrase, k, NULL);
748: try_next = 0;
749: } else {
750: debug2("no passphrase given, try next key");
751: try_next = 1;
752: }
753: memset(passphrase, 0, strlen(passphrase));
754: xfree(passphrase);
755: if (success || try_next)
756: break;
757: debug2("bad passphrase given, try again...");
758: }
1.16 markus 759: if (!success) {
760: key_free(k);
761: return 0;
762: }
763: }
1.28 markus 764: ret = sign_and_send_pubkey(authctxt, k, key_sign_cb);
1.17 markus 765: key_free(k);
766: return ret;
767: }
768:
1.20 markus 769: /* sign callback */
770: int agent_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp,
1.17 markus 771: unsigned char *data, int datalen)
772: {
1.20 markus 773: return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen);
1.17 markus 774: }
775:
776: int
1.20 markus 777: userauth_pubkey_agent(Authctxt *authctxt)
1.17 markus 778: {
779: static int called = 0;
1.28 markus 780: int ret = 0;
1.17 markus 781: char *comment;
782: Key *k;
783:
784: if (called == 0) {
1.28 markus 785: if (ssh_get_num_identities(authctxt->agent, 2) == 0)
786: debug2("userauth_pubkey_agent: no keys at all");
1.20 markus 787: called = 1;
1.17 markus 788: }
1.28 markus 789: k = ssh_get_next_identity(authctxt->agent, &comment, 2);
1.20 markus 790: if (k == NULL) {
1.28 markus 791: debug2("userauth_pubkey_agent: no more keys");
792: } else {
793: debug("userauth_pubkey_agent: trying agent key %s", comment);
794: xfree(comment);
795: ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb);
796: key_free(k);
1.20 markus 797: }
1.28 markus 798: if (ret == 0)
799: debug2("userauth_pubkey_agent: no message sent");
1.17 markus 800: return ret;
1.1 markus 801: }
802:
1.20 markus 803: int
804: userauth_pubkey(Authctxt *authctxt)
805: {
806: static int idx = 0;
807: int sent = 0;
808:
1.28 markus 809: if (authctxt->agent != NULL) {
810: do {
811: sent = userauth_pubkey_agent(authctxt);
812: } while(!sent && authctxt->agent->howmany > 0);
813: }
814: while (!sent && idx < options.num_identity_files) {
815: if (options.identity_files_type[idx] != KEY_RSA1)
816: sent = userauth_pubkey_identity(authctxt,
817: options.identity_files[idx]);
818: idx++;
819: }
1.20 markus 820: return sent;
821: }
822:
1.23 markus 823: /*
824: * Send userauth request message specifying keyboard-interactive method.
825: */
826: int
827: userauth_kbdint(Authctxt *authctxt)
828: {
829: static int attempt = 0;
830:
831: if (attempt++ >= options.number_of_password_prompts)
832: return 0;
833:
834: debug2("userauth_kbdint");
835: packet_start(SSH2_MSG_USERAUTH_REQUEST);
836: packet_put_cstring(authctxt->server_user);
837: packet_put_cstring(authctxt->service);
838: packet_put_cstring(authctxt->method->name);
839: packet_put_cstring(""); /* lang */
840: packet_put_cstring(options.kbd_interactive_devices ?
841: options.kbd_interactive_devices : "");
842: packet_send();
843: packet_write_wait();
844:
845: dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
846: return 1;
847: }
848:
849: /*
850: * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send
851: * SSH2_MSG_USERAUTH_INFO_RESPONSE
852: */
853: void
854: input_userauth_info_req(int type, int plen, void *ctxt)
855: {
856: Authctxt *authctxt = ctxt;
857: char *name = NULL;
858: char *inst = NULL;
859: char *lang = NULL;
860: char *prompt = NULL;
861: char *response = NULL;
862: unsigned int num_prompts, i;
863: int echo = 0;
864:
865: debug2("input_userauth_info_req");
866:
867: if (authctxt == NULL)
868: fatal("input_userauth_info_req: no authentication context");
869:
870: name = packet_get_string(NULL);
871: inst = packet_get_string(NULL);
872: lang = packet_get_string(NULL);
873:
874: if (strlen(name) > 0)
875: cli_mesg(name);
876: xfree(name);
877:
878: if (strlen(inst) > 0)
879: cli_mesg(inst);
880: xfree(inst);
881: xfree(lang); /* unused */
882:
883: num_prompts = packet_get_int();
884: /*
885: * Begin to build info response packet based on prompts requested.
886: * We commit to providing the correct number of responses, so if
887: * further on we run into a problem that prevents this, we have to
888: * be sure and clean this up and send a correct error response.
889: */
890: packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
891: packet_put_int(num_prompts);
892:
893: for (i = 0; i < num_prompts; i++) {
894: prompt = packet_get_string(NULL);
895: echo = packet_get_char();
896:
897: response = cli_prompt(prompt, echo);
898:
899: packet_put_cstring(response);
900: memset(response, 0, strlen(response));
901: xfree(response);
902: xfree(prompt);
903: }
904: packet_done(); /* done with parsing incoming message. */
905:
906: packet_send();
907: packet_write_wait();
908: }
1.20 markus 909:
910: /* find auth method */
911:
912: #define DELIM ","
913:
914: static char *def_authlist = "publickey,password";
915: static char *authlist_current = NULL; /* clean copy used for comparison */
916: static char *authname_current = NULL; /* last used auth method */
917: static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */
918: static char *authlist_state = NULL; /* state variable for strtok_r() */
919:
920: /*
921: * Before starting to use a new authentication method list sent by the
922: * server, reset internal variables. This should also be called when
923: * finished processing server list to free resources.
924: */
1.1 markus 925: void
1.20 markus 926: authmethod_clear()
927: {
928: if (authlist_current != NULL) {
929: xfree(authlist_current);
930: authlist_current = NULL;
931: }
932: if (authlist_working != NULL) {
933: xfree(authlist_working);
934: authlist_working = NULL;
935: }
936: if (authname_current != NULL) {
937: xfree(authname_current);
938: authlist_state = NULL;
939: }
940: if (authlist_state != NULL)
941: authlist_state = NULL;
942: return;
943: }
944:
945: /*
946: * given auth method name, if configurable options permit this method fill
947: * in auth_ident field and return true, otherwise return false.
948: */
949: int
950: authmethod_is_enabled(Authmethod *method)
951: {
952: if (method == NULL)
953: return 0;
954: /* return false if options indicate this method is disabled */
955: if (method->enabled == NULL || *method->enabled == 0)
956: return 0;
957: /* return false if batch mode is enabled but method needs interactive mode */
958: if (method->batch_flag != NULL && *method->batch_flag != 0)
959: return 0;
960: return 1;
961: }
962:
963: Authmethod *
964: authmethod_lookup(const char *name)
1.1 markus 965: {
1.20 markus 966: Authmethod *method = NULL;
967: if (name != NULL)
968: for (method = authmethods; method->name != NULL; method++)
969: if (strcmp(name, method->name) == 0)
970: return method;
971: debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
972: return NULL;
973: }
1.1 markus 974:
1.20 markus 975: /*
976: * Given the authentication method list sent by the server, return the
977: * next method we should try. If the server initially sends a nil list,
978: * use a built-in default list. If the server sends a nil list after
979: * previously sending a valid list, continue using the list originally
980: * sent.
981: */
1.1 markus 982:
1.20 markus 983: Authmethod *
984: authmethod_get(char *authlist)
985: {
1.27 provos 986: char *name = NULL, *authname_old;
1.20 markus 987: Authmethod *method = NULL;
988:
989: /* Use a suitable default if we're passed a nil list. */
990: if (authlist == NULL || strlen(authlist) == 0)
991: authlist = def_authlist;
992:
993: if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) {
994: /* start over if passed a different list */
1.23 markus 995: debug3("start over, passed a different list");
1.20 markus 996: authmethod_clear();
997: authlist_current = xstrdup(authlist);
998: authlist_working = xstrdup(authlist);
999: name = strtok_r(authlist_working, DELIM, &authlist_state);
1000: } else {
1001: /*
1002: * try to use previously used authentication method
1003: * or continue to use previously passed list
1004: */
1005: name = (authname_current != NULL) ?
1006: authname_current : strtok_r(NULL, DELIM, &authlist_state);
1.1 markus 1007: }
1.20 markus 1008:
1009: while (name != NULL) {
1.23 markus 1010: debug3("authmethod_lookup %s", name);
1.20 markus 1011: method = authmethod_lookup(name);
1.23 markus 1012: if (method != NULL && authmethod_is_enabled(method)) {
1013: debug3("authmethod_is_enabled %s", name);
1.20 markus 1014: break;
1.23 markus 1015: }
1.20 markus 1016: name = strtok_r(NULL, DELIM, &authlist_state);
1.23 markus 1017: method = NULL;
1.1 markus 1018: }
1019:
1.27 provos 1020: authname_old = authname_current;
1.23 markus 1021: if (method != NULL) {
1.20 markus 1022: debug("next auth method to try is %s", name);
1023: authname_current = xstrdup(name);
1024: } else {
1025: debug("no more auth methods to try");
1026: authname_current = NULL;
1.1 markus 1027: }
1.27 provos 1028:
1029: if (authname_old != NULL)
1030: xfree(authname_old);
1031:
1032: return (method);
1.1 markus 1033: }
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