Annotation of src/usr.bin/ssh/sshconnect2.c, Revision 1.35
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"
1.35 ! markus 26: RCSID("$OpenBSD: sshconnect2.c,v 1.34 2000/12/27 12:34:50 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:
1.32 markus 66: u_char *session_id2 = NULL;
1.1 markus 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;
1.32 markus 154: u_int klen, kout;
1.1 markus 155: char *signature = NULL;
1.32 markus 156: u_int slen;
1.1 markus 157: char *server_host_key_blob = NULL;
158: Key *server_host_key;
1.32 markus 159: u_int sbloblen;
1.1 markus 160: DH *dh;
161: BIGNUM *dh_server_pub = 0;
162: BIGNUM *shared_secret = 0;
1.32 markus 163: u_char *kbuf;
164: u_char *hash;
1.1 markus 165:
166: debug("Sending SSH2_MSG_KEXDH_INIT.");
167: /* generate and send 'e', client DH public key */
168: dh = dh_new_group1();
1.31 provos 169: dh_gen_key(dh);
1.1 markus 170: packet_start(SSH2_MSG_KEXDH_INIT);
171: packet_put_bignum2(dh->pub_key);
172: packet_send();
173: packet_write_wait();
174:
175: #ifdef DEBUG_KEXDH
176: fprintf(stderr, "\np= ");
1.19 markus 177: BN_print_fp(stderr, dh->p);
1.1 markus 178: fprintf(stderr, "\ng= ");
1.19 markus 179: BN_print_fp(stderr, dh->g);
1.1 markus 180: fprintf(stderr, "\npub= ");
1.19 markus 181: BN_print_fp(stderr, dh->pub_key);
1.1 markus 182: fprintf(stderr, "\n");
183: DHparams_print_fp(stderr, dh);
184: #endif
185:
186: debug("Wait SSH2_MSG_KEXDH_REPLY.");
187:
1.11 markus 188: packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
1.1 markus 189:
190: debug("Got SSH2_MSG_KEXDH_REPLY.");
191:
192: /* key, cert */
193: server_host_key_blob = packet_get_string(&sbloblen);
1.28 markus 194: server_host_key = key_from_blob(server_host_key_blob, sbloblen);
1.1 markus 195: if (server_host_key == NULL)
196: fatal("cannot decode server_host_key_blob");
197:
198: check_host_key(host, hostaddr, server_host_key,
1.22 provos 199: options.user_hostfile2, options.system_hostfile2);
1.1 markus 200:
201: /* DH paramter f, server public DH key */
202: dh_server_pub = BN_new();
203: if (dh_server_pub == NULL)
204: fatal("dh_server_pub == NULL");
205: packet_get_bignum2(dh_server_pub, &dlen);
206:
207: #ifdef DEBUG_KEXDH
208: fprintf(stderr, "\ndh_server_pub= ");
1.19 markus 209: BN_print_fp(stderr, dh_server_pub);
1.1 markus 210: fprintf(stderr, "\n");
211: debug("bits %d", BN_num_bits(dh_server_pub));
212: #endif
213:
214: /* signed H */
215: signature = packet_get_string(&slen);
216: packet_done();
217:
218: if (!dh_pub_is_valid(dh, dh_server_pub))
219: packet_disconnect("bad server public DH value");
220:
221: klen = DH_size(dh);
222: kbuf = xmalloc(klen);
223: kout = DH_compute_key(kbuf, dh_server_pub, dh);
224: #ifdef DEBUG_KEXDH
225: debug("shared secret: len %d/%d", klen, kout);
226: fprintf(stderr, "shared secret == ");
227: for (i = 0; i< kout; i++)
228: fprintf(stderr, "%02x", (kbuf[i])&0xff);
229: fprintf(stderr, "\n");
230: #endif
231: shared_secret = BN_new();
232:
233: BN_bin2bn(kbuf, kout, shared_secret);
234: memset(kbuf, 0, klen);
235: xfree(kbuf);
236:
237: /* calc and verify H */
238: hash = kex_hash(
239: client_version_string,
240: server_version_string,
241: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
242: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
243: server_host_key_blob, sbloblen,
244: dh->pub_key,
245: dh_server_pub,
246: shared_secret
247: );
1.3 markus 248: xfree(server_host_key_blob);
1.11 markus 249: DH_free(dh);
1.1 markus 250: #ifdef DEBUG_KEXDH
251: fprintf(stderr, "hash == ");
252: for (i = 0; i< 20; i++)
253: fprintf(stderr, "%02x", (hash[i])&0xff);
254: fprintf(stderr, "\n");
255: #endif
1.32 markus 256: if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1)
1.28 markus 257: fatal("key_verify failed for server_host_key");
1.1 markus 258: key_free(server_host_key);
259:
260: kex_derive_keys(kex, hash, shared_secret);
261: packet_set_kex(kex);
262:
263: /* save session id */
264: session_id2_len = 20;
265: session_id2 = xmalloc(session_id2_len);
266: memcpy(session_id2, hash, session_id2_len);
1.11 markus 267: }
268:
1.22 provos 269: /* diffie-hellman-group-exchange-sha1 */
270:
271: /*
272: * Estimates the group order for a Diffie-Hellman group that has an
273: * attack complexity approximately the same as O(2**bits). Estimate
274: * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3)))
275: */
276:
277: int
278: dh_estimate(int bits)
279: {
280:
281: if (bits < 64)
282: return (512); /* O(2**63) */
283: if (bits < 128)
284: return (1024); /* O(2**86) */
285: if (bits < 192)
286: return (2048); /* O(2**116) */
287: return (4096); /* O(2**156) */
288: }
289:
1.11 markus 290: void
1.22 provos 291: ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
292: Buffer *client_kexinit, Buffer *server_kexinit)
1.11 markus 293: {
1.22 provos 294: #ifdef DEBUG_KEXDH
295: int i;
296: #endif
297: int plen, dlen;
1.32 markus 298: u_int klen, kout;
1.22 provos 299: char *signature = NULL;
1.32 markus 300: u_int slen, nbits;
1.22 provos 301: char *server_host_key_blob = NULL;
302: Key *server_host_key;
1.32 markus 303: u_int sbloblen;
1.22 provos 304: DH *dh;
305: BIGNUM *dh_server_pub = 0;
306: BIGNUM *shared_secret = 0;
307: BIGNUM *p = 0, *g = 0;
1.32 markus 308: u_char *kbuf;
309: u_char *hash;
1.22 provos 310:
1.24 markus 311: nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8);
1.22 provos 312:
313: debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST.");
314: packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
315: packet_put_int(nbits);
316: packet_send();
317: packet_write_wait();
1.11 markus 318:
1.22 provos 319: #ifdef DEBUG_KEXDH
320: fprintf(stderr, "\nnbits = %d", nbits);
321: #endif
1.11 markus 322:
1.22 provos 323: debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP.");
1.11 markus 324:
1.22 provos 325: packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP);
1.11 markus 326:
1.22 provos 327: debug("Got SSH2_MSG_KEX_DH_GEX_GROUP.");
1.11 markus 328:
1.22 provos 329: if ((p = BN_new()) == NULL)
330: fatal("BN_new");
331: packet_get_bignum2(p, &dlen);
332: if ((g = BN_new()) == NULL)
333: fatal("BN_new");
334: packet_get_bignum2(g, &dlen);
335: if ((dh = dh_new_group(g, p)) == NULL)
336: fatal("dh_new_group");
1.31 provos 337:
338: dh_gen_key(dh);
1.1 markus 339:
1.22 provos 340: #ifdef DEBUG_KEXDH
341: fprintf(stderr, "\np= ");
342: BN_print_fp(stderr, dh->p);
343: fprintf(stderr, "\ng= ");
344: BN_print_fp(stderr, dh->g);
345: fprintf(stderr, "\npub= ");
346: BN_print_fp(stderr, dh->pub_key);
347: fprintf(stderr, "\n");
348: DHparams_print_fp(stderr, dh);
349: #endif
1.1 markus 350:
1.22 provos 351: debug("Sending SSH2_MSG_KEX_DH_GEX_INIT.");
352: /* generate and send 'e', client DH public key */
353: packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
354: packet_put_bignum2(dh->pub_key);
1.1 markus 355: packet_send();
356: packet_write_wait();
357:
1.22 provos 358: debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY.");
359:
360: packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY);
361:
362: debug("Got SSH2_MSG_KEXDH_REPLY.");
363:
364: /* key, cert */
365: server_host_key_blob = packet_get_string(&sbloblen);
1.28 markus 366: server_host_key = key_from_blob(server_host_key_blob, sbloblen);
1.22 provos 367: if (server_host_key == NULL)
368: fatal("cannot decode server_host_key_blob");
369:
370: check_host_key(host, hostaddr, server_host_key,
371: options.user_hostfile2, options.system_hostfile2);
372:
373: /* DH paramter f, server public DH key */
374: dh_server_pub = BN_new();
375: if (dh_server_pub == NULL)
376: fatal("dh_server_pub == NULL");
377: packet_get_bignum2(dh_server_pub, &dlen);
378:
379: #ifdef DEBUG_KEXDH
380: fprintf(stderr, "\ndh_server_pub= ");
381: BN_print_fp(stderr, dh_server_pub);
382: fprintf(stderr, "\n");
383: debug("bits %d", BN_num_bits(dh_server_pub));
384: #endif
385:
386: /* signed H */
387: signature = packet_get_string(&slen);
388: packet_done();
389:
390: if (!dh_pub_is_valid(dh, dh_server_pub))
391: packet_disconnect("bad server public DH value");
392:
393: klen = DH_size(dh);
394: kbuf = xmalloc(klen);
395: kout = DH_compute_key(kbuf, dh_server_pub, dh);
396: #ifdef DEBUG_KEXDH
397: debug("shared secret: len %d/%d", klen, kout);
398: fprintf(stderr, "shared secret == ");
399: for (i = 0; i< kout; i++)
400: fprintf(stderr, "%02x", (kbuf[i])&0xff);
401: fprintf(stderr, "\n");
402: #endif
403: shared_secret = BN_new();
404:
405: BN_bin2bn(kbuf, kout, shared_secret);
406: memset(kbuf, 0, klen);
407: xfree(kbuf);
408:
409: /* calc and verify H */
410: hash = kex_hash_gex(
411: client_version_string,
412: server_version_string,
413: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
414: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
415: server_host_key_blob, sbloblen,
416: nbits, dh->p, dh->g,
417: dh->pub_key,
418: dh_server_pub,
419: shared_secret
420: );
421: xfree(server_host_key_blob);
422: DH_free(dh);
1.1 markus 423: #ifdef DEBUG_KEXDH
1.22 provos 424: fprintf(stderr, "hash == ");
425: for (i = 0; i< 20; i++)
426: fprintf(stderr, "%02x", (hash[i])&0xff);
427: fprintf(stderr, "\n");
1.1 markus 428: #endif
1.32 markus 429: if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1)
1.28 markus 430: fatal("key_verify failed for server_host_key");
1.22 provos 431: key_free(server_host_key);
432:
433: kex_derive_keys(kex, hash, shared_secret);
434: packet_set_kex(kex);
435:
436: /* save session id */
437: session_id2_len = 20;
438: session_id2 = xmalloc(session_id2_len);
439: memcpy(session_id2, hash, session_id2_len);
1.1 markus 440: }
1.11 markus 441:
1.1 markus 442: /*
443: * Authenticate user
444: */
1.20 markus 445:
446: typedef struct Authctxt Authctxt;
447: typedef struct Authmethod Authmethod;
448:
449: typedef int sign_cb_fn(
450: Authctxt *authctxt, Key *key,
1.32 markus 451: u_char **sigp, int *lenp, u_char *data, int datalen);
1.20 markus 452:
453: struct Authctxt {
454: const char *server_user;
455: const char *host;
456: const char *service;
457: AuthenticationConnection *agent;
1.23 markus 458: Authmethod *method;
1.20 markus 459: int success;
460: };
461: struct Authmethod {
462: char *name; /* string to compare against server's list */
463: int (*userauth)(Authctxt *authctxt);
464: int *enabled; /* flag in option struct that enables method */
465: int *batch_flag; /* flag in option struct that disables method */
466: };
467:
468: void input_userauth_success(int type, int plen, void *ctxt);
469: void input_userauth_failure(int type, int plen, void *ctxt);
1.35 ! markus 470: void input_userauth_banner(int type, int plen, void *ctxt);
1.20 markus 471: void input_userauth_error(int type, int plen, void *ctxt);
1.23 markus 472: void input_userauth_info_req(int type, int plen, void *ctxt);
473:
474: int userauth_none(Authctxt *authctxt);
1.20 markus 475: int userauth_pubkey(Authctxt *authctxt);
476: int userauth_passwd(Authctxt *authctxt);
1.23 markus 477: int userauth_kbdint(Authctxt *authctxt);
1.20 markus 478:
1.33 markus 479: void authmethod_clear(void);
1.23 markus 480: Authmethod *authmethod_get(char *authlist);
481: Authmethod *authmethod_lookup(const char *name);
1.20 markus 482:
483: Authmethod authmethods[] = {
484: {"publickey",
485: userauth_pubkey,
1.28 markus 486: &options.pubkey_authentication,
1.20 markus 487: NULL},
488: {"password",
489: userauth_passwd,
490: &options.password_authentication,
491: &options.batch_mode},
1.23 markus 492: {"keyboard-interactive",
493: userauth_kbdint,
494: &options.kbd_interactive_authentication,
495: &options.batch_mode},
496: {"none",
497: userauth_none,
498: NULL,
499: NULL},
1.20 markus 500: {NULL, NULL, NULL, NULL}
501: };
502:
503: void
504: ssh_userauth2(const char *server_user, char *host)
505: {
506: Authctxt authctxt;
507: int type;
508: int plen;
509:
510: debug("send SSH2_MSG_SERVICE_REQUEST");
511: packet_start(SSH2_MSG_SERVICE_REQUEST);
512: packet_put_cstring("ssh-userauth");
513: packet_send();
514: packet_write_wait();
515: type = packet_read(&plen);
516: if (type != SSH2_MSG_SERVICE_ACCEPT) {
517: fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
518: }
519: if (packet_remaining() > 0) {
520: char *reply = packet_get_string(&plen);
521: debug("service_accept: %s", reply);
522: xfree(reply);
523: packet_done();
524: } else {
525: debug("buggy server: service_accept w/o service");
526: }
527: packet_done();
528: debug("got SSH2_MSG_SERVICE_ACCEPT");
529:
530: /* setup authentication context */
531: authctxt.agent = ssh_get_authentication_connection();
532: authctxt.server_user = server_user;
533: authctxt.host = host;
534: authctxt.service = "ssh-connection"; /* service name */
535: authctxt.success = 0;
1.23 markus 536: authctxt.method = authmethod_lookup("none");
537: if (authctxt.method == NULL)
538: fatal("ssh_userauth2: internal error: cannot send userauth none request");
539: authmethod_clear();
1.20 markus 540:
541: /* initial userauth request */
1.23 markus 542: userauth_none(&authctxt);
1.20 markus 543:
544: dispatch_init(&input_userauth_error);
545: dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
546: dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
1.35 ! markus 547: dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
1.20 markus 548: dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
549:
550: if (authctxt.agent != NULL)
551: ssh_close_authentication_connection(authctxt.agent);
552:
1.34 markus 553: debug("ssh-userauth2 successful: method %s", authctxt.method->name);
1.20 markus 554: }
555: void
556: input_userauth_error(int type, int plen, void *ctxt)
557: {
1.35 ! markus 558: fatal("input_userauth_error: bad message during authentication: "
! 559: "type %d", type);
! 560: }
! 561: void
! 562: input_userauth_banner(int type, int plen, void *ctxt)
! 563: {
! 564: char *msg, *lang;
! 565: debug3("input_userauth_banner");
! 566: msg = packet_get_string(NULL);
! 567: lang = packet_get_string(NULL);
! 568: fprintf(stderr, "%s", msg);
! 569: xfree(msg);
! 570: xfree(lang);
1.20 markus 571: }
572: void
573: input_userauth_success(int type, int plen, void *ctxt)
574: {
575: Authctxt *authctxt = ctxt;
576: if (authctxt == NULL)
577: fatal("input_userauth_success: no authentication context");
578: authctxt->success = 1; /* break out */
579: }
580: void
581: input_userauth_failure(int type, int plen, void *ctxt)
582: {
583: Authmethod *method = NULL;
584: Authctxt *authctxt = ctxt;
585: char *authlist = NULL;
586: int partial;
587:
588: if (authctxt == NULL)
589: fatal("input_userauth_failure: no authentication context");
590:
1.23 markus 591: authlist = packet_get_string(NULL);
1.20 markus 592: partial = packet_get_char();
593: packet_done();
594:
595: if (partial != 0)
596: debug("partial success");
597: debug("authentications that can continue: %s", authlist);
598:
599: for (;;) {
600: method = authmethod_get(authlist);
601: if (method == NULL)
602: fatal("Unable to find an authentication method");
1.23 markus 603: authctxt->method = method;
1.20 markus 604: if (method->userauth(authctxt) != 0) {
1.23 markus 605: debug2("we sent a %s packet, wait for reply", method->name);
1.20 markus 606: break;
607: } else {
608: debug2("we did not send a packet, disable method");
609: method->enabled = NULL;
610: }
611: }
612: xfree(authlist);
613: }
614:
1.1 markus 615: int
1.23 markus 616: userauth_none(Authctxt *authctxt)
617: {
618: /* initial userauth request */
619: packet_start(SSH2_MSG_USERAUTH_REQUEST);
620: packet_put_cstring(authctxt->server_user);
621: packet_put_cstring(authctxt->service);
622: packet_put_cstring(authctxt->method->name);
623: packet_send();
624: packet_write_wait();
625: return 1;
626: }
627:
628: int
1.20 markus 629: userauth_passwd(Authctxt *authctxt)
1.1 markus 630: {
1.6 markus 631: static int attempt = 0;
1.1 markus 632: char prompt[80];
633: char *password;
1.6 markus 634:
1.13 todd 635: if (attempt++ >= options.number_of_password_prompts)
1.6 markus 636: return 0;
1.13 todd 637:
638: if(attempt != 1)
639: error("Permission denied, please try again.");
1.1 markus 640:
641: snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
1.20 markus 642: authctxt->server_user, authctxt->host);
1.1 markus 643: password = read_passphrase(prompt, 0);
644: packet_start(SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 645: packet_put_cstring(authctxt->server_user);
646: packet_put_cstring(authctxt->service);
1.23 markus 647: packet_put_cstring(authctxt->method->name);
1.1 markus 648: packet_put_char(0);
649: packet_put_cstring(password);
650: memset(password, 0, strlen(password));
651: xfree(password);
652: packet_send();
653: packet_write_wait();
654: return 1;
655: }
656:
1.17 markus 657: int
1.20 markus 658: sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
1.1 markus 659: {
660: Buffer b;
1.32 markus 661: u_char *blob, *signature;
1.1 markus 662: int bloblen, slen;
1.14 markus 663: int skip = 0;
1.17 markus 664: int ret = -1;
1.23 markus 665: int have_sig = 1;
1.1 markus 666:
1.30 markus 667: debug3("sign_and_send_pubkey");
1.28 markus 668: if (key_to_blob(k, &blob, &bloblen) == 0) {
669: /* we cannot handle this key */
1.30 markus 670: debug3("sign_and_send_pubkey: cannot handle key");
1.28 markus 671: return 0;
672: }
1.1 markus 673: /* data to be signed */
674: buffer_init(&b);
1.26 markus 675: if (datafellows & SSH_OLD_SESSIONID) {
676: buffer_append(&b, session_id2, session_id2_len);
677: skip = session_id2_len;
678: } else {
1.14 markus 679: buffer_put_string(&b, session_id2, session_id2_len);
680: skip = buffer_len(&b);
681: }
1.1 markus 682: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 683: buffer_put_cstring(&b, authctxt->server_user);
1.10 markus 684: buffer_put_cstring(&b,
1.30 markus 685: datafellows & SSH_BUG_PKSERVICE ?
1.10 markus 686: "ssh-userauth" :
1.20 markus 687: authctxt->service);
1.30 markus 688: if (datafellows & SSH_BUG_PKAUTH) {
689: buffer_put_char(&b, have_sig);
690: } else {
691: buffer_put_cstring(&b, authctxt->method->name);
692: buffer_put_char(&b, have_sig);
693: buffer_put_cstring(&b, key_ssh_name(k));
694: }
1.1 markus 695: buffer_put_string(&b, blob, bloblen);
696:
697: /* generate signature */
1.20 markus 698: ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
1.17 markus 699: if (ret == -1) {
700: xfree(blob);
701: buffer_free(&b);
702: return 0;
703: }
1.28 markus 704: #ifdef DEBUG_PK
1.1 markus 705: buffer_dump(&b);
706: #endif
1.30 markus 707: if (datafellows & SSH_BUG_PKSERVICE) {
1.10 markus 708: buffer_clear(&b);
709: buffer_append(&b, session_id2, session_id2_len);
710: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1.20 markus 711: buffer_put_cstring(&b, authctxt->server_user);
712: buffer_put_cstring(&b, authctxt->service);
1.23 markus 713: buffer_put_cstring(&b, authctxt->method->name);
714: buffer_put_char(&b, have_sig);
1.30 markus 715: if (!(datafellows & SSH_BUG_PKAUTH))
716: buffer_put_cstring(&b, key_ssh_name(k));
1.10 markus 717: buffer_put_string(&b, blob, bloblen);
718: }
719: xfree(blob);
1.1 markus 720: /* append signature */
721: buffer_put_string(&b, signature, slen);
722: xfree(signature);
723:
724: /* skip session id and packet type */
1.14 markus 725: if (buffer_len(&b) < skip + 1)
1.20 markus 726: fatal("userauth_pubkey: internal error");
1.14 markus 727: buffer_consume(&b, skip + 1);
1.1 markus 728:
729: /* put remaining data from buffer into packet */
730: packet_start(SSH2_MSG_USERAUTH_REQUEST);
731: packet_put_raw(buffer_ptr(&b), buffer_len(&b));
732: buffer_free(&b);
733:
734: /* send */
735: packet_send();
736: packet_write_wait();
1.17 markus 737:
738: return 1;
1.16 markus 739: }
740:
1.20 markus 741: /* sign callback */
1.32 markus 742: int key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp,
743: u_char *data, int datalen)
1.20 markus 744: {
1.28 markus 745: return key_sign(key, sigp, lenp, data, datalen);
1.20 markus 746: }
747:
1.16 markus 748: int
1.20 markus 749: userauth_pubkey_identity(Authctxt *authctxt, char *filename)
1.16 markus 750: {
751: Key *k;
1.20 markus 752: int i, ret, try_next;
1.16 markus 753: struct stat st;
754:
755: if (stat(filename, &st) != 0) {
756: debug("key does not exist: %s", filename);
757: return 0;
758: }
759: debug("try pubkey: %s", filename);
760:
1.28 markus 761: k = key_new(KEY_UNSPEC);
1.16 markus 762: if (!load_private_key(filename, "", k, NULL)) {
763: int success = 0;
764: char *passphrase;
765: char prompt[300];
766: snprintf(prompt, sizeof prompt,
1.28 markus 767: "Enter passphrase for key '%.100s': ", filename);
1.20 markus 768: for (i = 0; i < options.number_of_password_prompts; i++) {
769: passphrase = read_passphrase(prompt, 0);
770: if (strcmp(passphrase, "") != 0) {
771: success = load_private_key(filename, passphrase, k, NULL);
772: try_next = 0;
773: } else {
774: debug2("no passphrase given, try next key");
775: try_next = 1;
776: }
777: memset(passphrase, 0, strlen(passphrase));
778: xfree(passphrase);
779: if (success || try_next)
780: break;
781: debug2("bad passphrase given, try again...");
782: }
1.16 markus 783: if (!success) {
784: key_free(k);
785: return 0;
786: }
787: }
1.28 markus 788: ret = sign_and_send_pubkey(authctxt, k, key_sign_cb);
1.17 markus 789: key_free(k);
790: return ret;
791: }
792:
1.20 markus 793: /* sign callback */
1.32 markus 794: int agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp,
795: u_char *data, int datalen)
1.17 markus 796: {
1.20 markus 797: return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen);
1.17 markus 798: }
799:
800: int
1.20 markus 801: userauth_pubkey_agent(Authctxt *authctxt)
1.17 markus 802: {
803: static int called = 0;
1.28 markus 804: int ret = 0;
1.17 markus 805: char *comment;
806: Key *k;
807:
808: if (called == 0) {
1.28 markus 809: if (ssh_get_num_identities(authctxt->agent, 2) == 0)
810: debug2("userauth_pubkey_agent: no keys at all");
1.20 markus 811: called = 1;
1.17 markus 812: }
1.28 markus 813: k = ssh_get_next_identity(authctxt->agent, &comment, 2);
1.20 markus 814: if (k == NULL) {
1.28 markus 815: debug2("userauth_pubkey_agent: no more keys");
816: } else {
817: debug("userauth_pubkey_agent: trying agent key %s", comment);
818: xfree(comment);
819: ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb);
820: key_free(k);
1.20 markus 821: }
1.28 markus 822: if (ret == 0)
823: debug2("userauth_pubkey_agent: no message sent");
1.17 markus 824: return ret;
1.1 markus 825: }
826:
1.20 markus 827: int
828: userauth_pubkey(Authctxt *authctxt)
829: {
830: static int idx = 0;
831: int sent = 0;
832:
1.28 markus 833: if (authctxt->agent != NULL) {
834: do {
835: sent = userauth_pubkey_agent(authctxt);
836: } while(!sent && authctxt->agent->howmany > 0);
837: }
838: while (!sent && idx < options.num_identity_files) {
839: if (options.identity_files_type[idx] != KEY_RSA1)
840: sent = userauth_pubkey_identity(authctxt,
841: options.identity_files[idx]);
842: idx++;
843: }
1.20 markus 844: return sent;
845: }
846:
1.23 markus 847: /*
848: * Send userauth request message specifying keyboard-interactive method.
849: */
850: int
851: userauth_kbdint(Authctxt *authctxt)
852: {
853: static int attempt = 0;
854:
855: if (attempt++ >= options.number_of_password_prompts)
856: return 0;
857:
858: debug2("userauth_kbdint");
859: packet_start(SSH2_MSG_USERAUTH_REQUEST);
860: packet_put_cstring(authctxt->server_user);
861: packet_put_cstring(authctxt->service);
862: packet_put_cstring(authctxt->method->name);
863: packet_put_cstring(""); /* lang */
864: packet_put_cstring(options.kbd_interactive_devices ?
865: options.kbd_interactive_devices : "");
866: packet_send();
867: packet_write_wait();
868:
869: dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
870: return 1;
871: }
872:
873: /*
874: * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send
875: * SSH2_MSG_USERAUTH_INFO_RESPONSE
876: */
877: void
878: input_userauth_info_req(int type, int plen, void *ctxt)
879: {
880: Authctxt *authctxt = ctxt;
881: char *name = NULL;
882: char *inst = NULL;
883: char *lang = NULL;
884: char *prompt = NULL;
885: char *response = NULL;
1.32 markus 886: u_int num_prompts, i;
1.23 markus 887: int echo = 0;
888:
889: debug2("input_userauth_info_req");
890:
891: if (authctxt == NULL)
892: fatal("input_userauth_info_req: no authentication context");
893:
894: name = packet_get_string(NULL);
895: inst = packet_get_string(NULL);
896: lang = packet_get_string(NULL);
897:
898: if (strlen(name) > 0)
899: cli_mesg(name);
900: xfree(name);
901:
902: if (strlen(inst) > 0)
903: cli_mesg(inst);
904: xfree(inst);
905: xfree(lang); /* unused */
906:
907: num_prompts = packet_get_int();
908: /*
909: * Begin to build info response packet based on prompts requested.
910: * We commit to providing the correct number of responses, so if
911: * further on we run into a problem that prevents this, we have to
912: * be sure and clean this up and send a correct error response.
913: */
914: packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
915: packet_put_int(num_prompts);
916:
917: for (i = 0; i < num_prompts; i++) {
918: prompt = packet_get_string(NULL);
919: echo = packet_get_char();
920:
921: response = cli_prompt(prompt, echo);
922:
923: packet_put_cstring(response);
924: memset(response, 0, strlen(response));
925: xfree(response);
926: xfree(prompt);
927: }
928: packet_done(); /* done with parsing incoming message. */
929:
930: packet_send();
931: packet_write_wait();
932: }
1.20 markus 933:
934: /* find auth method */
935:
936: #define DELIM ","
937:
938: static char *def_authlist = "publickey,password";
939: static char *authlist_current = NULL; /* clean copy used for comparison */
940: static char *authname_current = NULL; /* last used auth method */
941: static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */
942: static char *authlist_state = NULL; /* state variable for strtok_r() */
943:
944: /*
945: * Before starting to use a new authentication method list sent by the
946: * server, reset internal variables. This should also be called when
947: * finished processing server list to free resources.
948: */
1.1 markus 949: void
1.33 markus 950: authmethod_clear(void)
1.20 markus 951: {
952: if (authlist_current != NULL) {
953: xfree(authlist_current);
954: authlist_current = NULL;
955: }
956: if (authlist_working != NULL) {
957: xfree(authlist_working);
958: authlist_working = NULL;
959: }
960: if (authname_current != NULL) {
961: xfree(authname_current);
962: authlist_state = NULL;
963: }
964: if (authlist_state != NULL)
965: authlist_state = NULL;
966: return;
967: }
968:
969: /*
970: * given auth method name, if configurable options permit this method fill
971: * in auth_ident field and return true, otherwise return false.
972: */
973: int
974: authmethod_is_enabled(Authmethod *method)
975: {
976: if (method == NULL)
977: return 0;
978: /* return false if options indicate this method is disabled */
979: if (method->enabled == NULL || *method->enabled == 0)
980: return 0;
981: /* return false if batch mode is enabled but method needs interactive mode */
982: if (method->batch_flag != NULL && *method->batch_flag != 0)
983: return 0;
984: return 1;
985: }
986:
987: Authmethod *
988: authmethod_lookup(const char *name)
1.1 markus 989: {
1.20 markus 990: Authmethod *method = NULL;
991: if (name != NULL)
992: for (method = authmethods; method->name != NULL; method++)
993: if (strcmp(name, method->name) == 0)
994: return method;
995: debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
996: return NULL;
997: }
1.1 markus 998:
1.20 markus 999: /*
1000: * Given the authentication method list sent by the server, return the
1001: * next method we should try. If the server initially sends a nil list,
1002: * use a built-in default list. If the server sends a nil list after
1003: * previously sending a valid list, continue using the list originally
1004: * sent.
1005: */
1.1 markus 1006:
1.20 markus 1007: Authmethod *
1008: authmethod_get(char *authlist)
1009: {
1.27 provos 1010: char *name = NULL, *authname_old;
1.20 markus 1011: Authmethod *method = NULL;
1012:
1013: /* Use a suitable default if we're passed a nil list. */
1014: if (authlist == NULL || strlen(authlist) == 0)
1015: authlist = def_authlist;
1016:
1017: if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) {
1018: /* start over if passed a different list */
1.23 markus 1019: debug3("start over, passed a different list");
1.20 markus 1020: authmethod_clear();
1021: authlist_current = xstrdup(authlist);
1022: authlist_working = xstrdup(authlist);
1023: name = strtok_r(authlist_working, DELIM, &authlist_state);
1024: } else {
1025: /*
1026: * try to use previously used authentication method
1027: * or continue to use previously passed list
1028: */
1029: name = (authname_current != NULL) ?
1030: authname_current : strtok_r(NULL, DELIM, &authlist_state);
1.1 markus 1031: }
1.20 markus 1032:
1033: while (name != NULL) {
1.23 markus 1034: debug3("authmethod_lookup %s", name);
1.20 markus 1035: method = authmethod_lookup(name);
1.23 markus 1036: if (method != NULL && authmethod_is_enabled(method)) {
1037: debug3("authmethod_is_enabled %s", name);
1.20 markus 1038: break;
1.23 markus 1039: }
1.20 markus 1040: name = strtok_r(NULL, DELIM, &authlist_state);
1.23 markus 1041: method = NULL;
1.1 markus 1042: }
1043:
1.27 provos 1044: authname_old = authname_current;
1.23 markus 1045: if (method != NULL) {
1.20 markus 1046: debug("next auth method to try is %s", name);
1047: authname_current = xstrdup(name);
1048: } else {
1049: debug("no more auth methods to try");
1050: authname_current = NULL;
1.1 markus 1051: }
1.27 provos 1052:
1053: if (authname_old != NULL)
1054: xfree(authname_old);
1055:
1056: return (method);
1.1 markus 1057: }
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