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authorColin Watson <cjwatson@debian.org>2014-03-20 00:32:39 +0000
committerColin Watson <cjwatson@debian.org>2014-03-20 00:34:16 +0000
commit2ee2de47fd0f684f54218d31b4ec83930e69c18e (patch)
tree86848a7668424b392d48791a0e41e05f9df7b62b /auth2-jpake.c
parentc9947303ad3c432b1cadfbeb1d95a7cd38662d66 (diff)
parent9cbb60f5e4932634db04c330c88abc49cc5567bd (diff)
Merge 6.6p1.
* New upstream release (http://www.openssh.com/txt/release-6.6).
Diffstat (limited to 'auth2-jpake.c')
-rw-r--r--auth2-jpake.c563
1 files changed, 0 insertions, 563 deletions
diff --git a/auth2-jpake.c b/auth2-jpake.c
deleted file mode 100644
index 78a6b8817..000000000
--- a/auth2-jpake.c
+++ /dev/null
@@ -1,563 +0,0 @@
1/* $OpenBSD: auth2-jpake.c,v 1.6 2013/05/17 00:13:13 djm Exp $ */
2/*
3 * Copyright (c) 2008 Damien Miller. All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/*
19 * Server side of zero-knowledge password auth using J-PAKE protocol
20 * as described in:
21 *
22 * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling",
23 * 16th Workshop on Security Protocols, Cambridge, April 2008
24 *
25 * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
26 */
27
28#ifdef JPAKE
29
30#include <sys/types.h>
31#include <sys/param.h>
32
33#include <pwd.h>
34#include <stdio.h>
35#include <string.h>
36#include <login_cap.h>
37
38#include <openssl/bn.h>
39#include <openssl/evp.h>
40
41#include "xmalloc.h"
42#include "ssh2.h"
43#include "key.h"
44#include "hostfile.h"
45#include "auth.h"
46#include "buffer.h"
47#include "packet.h"
48#include "dispatch.h"
49#include "log.h"
50#include "servconf.h"
51#include "auth-options.h"
52#include "canohost.h"
53#ifdef GSSAPI
54#include "ssh-gss.h"
55#endif
56#include "monitor_wrap.h"
57
58#include "schnorr.h"
59#include "jpake.h"
60
61/*
62 * XXX options->permit_empty_passwd (at the moment, they will be refused
63 * anyway because they will mismatch on fake salt.
64 */
65
66/* Dispatch handlers */
67static void input_userauth_jpake_client_step1(int, u_int32_t, void *);
68static void input_userauth_jpake_client_step2(int, u_int32_t, void *);
69static void input_userauth_jpake_client_confirm(int, u_int32_t, void *);
70
71static int auth2_jpake_start(Authctxt *);
72
73/* import */
74extern ServerOptions options;
75extern u_char *session_id2;
76extern u_int session_id2_len;
77
78/*
79 * Attempt J-PAKE authentication.
80 */
81static int
82userauth_jpake(Authctxt *authctxt)
83{
84 int authenticated = 0;
85
86 packet_check_eom();
87
88 debug("jpake-01@openssh.com requested");
89
90 if (authctxt->user != NULL) {
91 if (authctxt->jpake_ctx == NULL)
92 authctxt->jpake_ctx = jpake_new();
93 if (options.zero_knowledge_password_authentication)
94 authenticated = auth2_jpake_start(authctxt);
95 }
96
97 return authenticated;
98}
99
100Authmethod method_jpake = {
101 "jpake-01@openssh.com",
102 userauth_jpake,
103 &options.zero_knowledge_password_authentication
104};
105
106/* Clear context and callbacks */
107void
108auth2_jpake_stop(Authctxt *authctxt)
109{
110 /* unregister callbacks */
111 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL);
112 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL);
113 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL);
114 if (authctxt->jpake_ctx != NULL) {
115 jpake_free(authctxt->jpake_ctx);
116 authctxt->jpake_ctx = NULL;
117 }
118}
119
120/* Returns 1 if 'c' is a valid crypt(3) salt character, 0 otherwise */
121static int
122valid_crypt_salt(int c)
123{
124 if (c >= 'A' && c <= 'Z')
125 return 1;
126 if (c >= 'a' && c <= 'z')
127 return 1;
128 if (c >= '.' && c <= '9')
129 return 1;
130 return 0;
131}
132
133/*
134 * Derive fake salt as H(username || first_private_host_key)
135 * This provides relatively stable fake salts for non-existent
136 * users and avoids the jpake method becoming an account validity
137 * oracle.
138 */
139static void
140derive_rawsalt(const char *username, u_char *rawsalt, u_int len)
141{
142 u_char *digest;
143 u_int digest_len;
144 Buffer b;
145 Key *k;
146
147 buffer_init(&b);
148 buffer_put_cstring(&b, username);
149 if ((k = get_hostkey_by_index(0)) == NULL ||
150 (k->flags & KEY_FLAG_EXT))
151 fatal("%s: no hostkeys", __func__);
152 switch (k->type) {
153 case KEY_RSA1:
154 case KEY_RSA:
155 if (k->rsa->p == NULL || k->rsa->q == NULL)
156 fatal("%s: RSA key missing p and/or q", __func__);
157 buffer_put_bignum2(&b, k->rsa->p);
158 buffer_put_bignum2(&b, k->rsa->q);
159 break;
160 case KEY_DSA:
161 if (k->dsa->priv_key == NULL)
162 fatal("%s: DSA key missing priv_key", __func__);
163 buffer_put_bignum2(&b, k->dsa->priv_key);
164 break;
165 case KEY_ECDSA:
166 if (EC_KEY_get0_private_key(k->ecdsa) == NULL)
167 fatal("%s: ECDSA key missing priv_key", __func__);
168 buffer_put_bignum2(&b, EC_KEY_get0_private_key(k->ecdsa));
169 break;
170 default:
171 fatal("%s: unknown key type %d", __func__, k->type);
172 }
173 if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(),
174 &digest, &digest_len) != 0)
175 fatal("%s: hash_buffer", __func__);
176 buffer_free(&b);
177 if (len > digest_len)
178 fatal("%s: not enough bytes for rawsalt (want %u have %u)",
179 __func__, len, digest_len);
180 memcpy(rawsalt, digest, len);
181 bzero(digest, digest_len);
182 free(digest);
183}
184
185/* ASCII an integer [0, 64) for inclusion in a password/salt */
186static char
187pw_encode64(u_int i64)
188{
189 const u_char e64[] =
190 "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
191 return e64[i64 % 64];
192}
193
194/* Generate ASCII salt bytes for user */
195static char *
196makesalt(u_int want, const char *user)
197{
198 u_char rawsalt[32];
199 static char ret[33];
200 u_int i;
201
202 if (want > sizeof(ret) - 1)
203 fatal("%s: want %u", __func__, want);
204
205 derive_rawsalt(user, rawsalt, sizeof(rawsalt));
206 bzero(ret, sizeof(ret));
207 for (i = 0; i < want; i++)
208 ret[i] = pw_encode64(rawsalt[i]);
209 bzero(rawsalt, sizeof(rawsalt));
210
211 return ret;
212}
213
214/*
215 * Select the system's default password hashing scheme and generate
216 * a stable fake salt under it for use by a non-existent account.
217 * Prevents jpake method being used to infer the validity of accounts.
218 */
219static void
220fake_salt_and_scheme(Authctxt *authctxt, char **salt, char **scheme)
221{
222 char *rounds_s, *style;
223 long long rounds;
224 login_cap_t *lc;
225
226
227 if ((lc = login_getclass(authctxt->pw->pw_class)) == NULL &&
228 (lc = login_getclass(NULL)) == NULL)
229 fatal("%s: login_getclass failed", __func__);
230 style = login_getcapstr(lc, "localcipher", NULL, NULL);
231 if (style == NULL)
232 style = xstrdup("blowfish,6");
233 login_close(lc);
234
235 if ((rounds_s = strchr(style, ',')) != NULL)
236 *rounds_s++ = '\0';
237 rounds = strtonum(rounds_s, 1, 1<<31, NULL);
238
239 if (strcmp(style, "md5") == 0) {
240 xasprintf(salt, "$1$%s$", makesalt(8, authctxt->user));
241 *scheme = xstrdup("md5");
242 } else if (strcmp(style, "old") == 0) {
243 *salt = xstrdup(makesalt(2, authctxt->user));
244 *scheme = xstrdup("crypt");
245 } else if (strcmp(style, "newsalt") == 0) {
246 rounds = MAX(rounds, 7250);
247 rounds = MIN(rounds, (1<<24) - 1);
248 xasprintf(salt, "_%c%c%c%c%s",
249 pw_encode64(rounds), pw_encode64(rounds >> 6),
250 pw_encode64(rounds >> 12), pw_encode64(rounds >> 18),
251 makesalt(4, authctxt->user));
252 *scheme = xstrdup("crypt-extended");
253 } else {
254 /* Default to blowfish */
255 rounds = MAX(rounds, 3);
256 rounds = MIN(rounds, 31);
257 xasprintf(salt, "$2a$%02lld$%s", rounds,
258 makesalt(22, authctxt->user));
259 *scheme = xstrdup("bcrypt");
260 }
261 free(style);
262 debug3("%s: fake %s salt for user %s: %s",
263 __func__, *scheme, authctxt->user, *salt);
264}
265
266/*
267 * Fetch password hashing scheme, password salt and derive shared secret
268 * for user. If user does not exist, a fake but stable and user-unique
269 * salt will be returned.
270 */
271void
272auth2_jpake_get_pwdata(Authctxt *authctxt, BIGNUM **s,
273 char **hash_scheme, char **salt)
274{
275 char *cp;
276 u_char *secret;
277 u_int secret_len, salt_len;
278
279#ifdef JPAKE_DEBUG
280 debug3("%s: valid %d pw %.5s...", __func__,
281 authctxt->valid, authctxt->pw->pw_passwd);
282#endif
283
284 *salt = NULL;
285 *hash_scheme = NULL;
286 if (authctxt->valid) {
287 if (strncmp(authctxt->pw->pw_passwd, "$2$", 3) == 0 &&
288 strlen(authctxt->pw->pw_passwd) > 28) {
289 /*
290 * old-variant bcrypt:
291 * "$2$", 2 digit rounds, "$", 22 bytes salt
292 */
293 salt_len = 3 + 2 + 1 + 22 + 1;
294 *salt = xmalloc(salt_len);
295 strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
296 *hash_scheme = xstrdup("bcrypt");
297 } else if (strncmp(authctxt->pw->pw_passwd, "$2a$", 4) == 0 &&
298 strlen(authctxt->pw->pw_passwd) > 29) {
299 /*
300 * current-variant bcrypt:
301 * "$2a$", 2 digit rounds, "$", 22 bytes salt
302 */
303 salt_len = 4 + 2 + 1 + 22 + 1;
304 *salt = xmalloc(salt_len);
305 strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
306 *hash_scheme = xstrdup("bcrypt");
307 } else if (strncmp(authctxt->pw->pw_passwd, "$1$", 3) == 0 &&
308 strlen(authctxt->pw->pw_passwd) > 5) {
309 /*
310 * md5crypt:
311 * "$1$", salt until "$"
312 */
313 cp = strchr(authctxt->pw->pw_passwd + 3, '$');
314 if (cp != NULL) {
315 salt_len = (cp - authctxt->pw->pw_passwd) + 1;
316 *salt = xmalloc(salt_len);
317 strlcpy(*salt, authctxt->pw->pw_passwd,
318 salt_len);
319 *hash_scheme = xstrdup("md5crypt");
320 }
321 } else if (strncmp(authctxt->pw->pw_passwd, "_", 1) == 0 &&
322 strlen(authctxt->pw->pw_passwd) > 9) {
323 /*
324 * BSDI extended crypt:
325 * "_", 4 digits count, 4 chars salt
326 */
327 salt_len = 1 + 4 + 4 + 1;
328 *salt = xmalloc(salt_len);
329 strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
330 *hash_scheme = xstrdup("crypt-extended");
331 } else if (strlen(authctxt->pw->pw_passwd) == 13 &&
332 valid_crypt_salt(authctxt->pw->pw_passwd[0]) &&
333 valid_crypt_salt(authctxt->pw->pw_passwd[1])) {
334 /*
335 * traditional crypt:
336 * 2 chars salt
337 */
338 salt_len = 2 + 1;
339 *salt = xmalloc(salt_len);
340 strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
341 *hash_scheme = xstrdup("crypt");
342 }
343 if (*salt == NULL) {
344 debug("%s: unrecognised crypt scheme for user %s",
345 __func__, authctxt->pw->pw_name);
346 }
347 }
348 if (*salt == NULL)
349 fake_salt_and_scheme(authctxt, salt, hash_scheme);
350
351 if (hash_buffer(authctxt->pw->pw_passwd,
352 strlen(authctxt->pw->pw_passwd), EVP_sha256(),
353 &secret, &secret_len) != 0)
354 fatal("%s: hash_buffer", __func__);
355 if ((*s = BN_bin2bn(secret, secret_len, NULL)) == NULL)
356 fatal("%s: BN_bin2bn (secret)", __func__);
357#ifdef JPAKE_DEBUG
358 debug3("%s: salt = %s (len %u)", __func__,
359 *salt, (u_int)strlen(*salt));
360 debug3("%s: scheme = %s", __func__, *hash_scheme);
361 JPAKE_DEBUG_BN((*s, "%s: s = ", __func__));
362#endif
363 bzero(secret, secret_len);
364 free(secret);
365}
366
367/*
368 * Begin authentication attempt.
369 * Note, sets authctxt->postponed while in subprotocol
370 */
371static int
372auth2_jpake_start(Authctxt *authctxt)
373{
374 struct jpake_ctx *pctx = authctxt->jpake_ctx;
375 u_char *x3_proof, *x4_proof;
376 u_int x3_proof_len, x4_proof_len;
377 char *salt, *hash_scheme;
378
379 debug("%s: start", __func__);
380
381 PRIVSEP(jpake_step1(pctx->grp,
382 &pctx->server_id, &pctx->server_id_len,
383 &pctx->x3, &pctx->x4, &pctx->g_x3, &pctx->g_x4,
384 &x3_proof, &x3_proof_len,
385 &x4_proof, &x4_proof_len));
386
387 PRIVSEP(auth2_jpake_get_pwdata(authctxt, &pctx->s,
388 &hash_scheme, &salt));
389
390 if (!use_privsep)
391 JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
392
393 packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1);
394 packet_put_cstring(hash_scheme);
395 packet_put_cstring(salt);
396 packet_put_string(pctx->server_id, pctx->server_id_len);
397 packet_put_bignum2(pctx->g_x3);
398 packet_put_bignum2(pctx->g_x4);
399 packet_put_string(x3_proof, x3_proof_len);
400 packet_put_string(x4_proof, x4_proof_len);
401 packet_send();
402 packet_write_wait();
403
404 bzero(hash_scheme, strlen(hash_scheme));
405 bzero(salt, strlen(salt));
406 free(hash_scheme);
407 free(salt);
408 bzero(x3_proof, x3_proof_len);
409 bzero(x4_proof, x4_proof_len);
410 free(x3_proof);
411 free(x4_proof);
412
413 /* Expect step 1 packet from peer */
414 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1,
415 input_userauth_jpake_client_step1);
416
417 authctxt->postponed = 1;
418 return 0;
419}
420
421/* ARGSUSED */
422static void
423input_userauth_jpake_client_step1(int type, u_int32_t seq, void *ctxt)
424{
425 Authctxt *authctxt = ctxt;
426 struct jpake_ctx *pctx = authctxt->jpake_ctx;
427 u_char *x1_proof, *x2_proof, *x4_s_proof;
428 u_int x1_proof_len, x2_proof_len, x4_s_proof_len;
429
430 /* Disable this message */
431 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL);
432
433 /* Fetch step 1 values */
434 if ((pctx->g_x1 = BN_new()) == NULL ||
435 (pctx->g_x2 = BN_new()) == NULL)
436 fatal("%s: BN_new", __func__);
437 pctx->client_id = packet_get_string(&pctx->client_id_len);
438 packet_get_bignum2(pctx->g_x1);
439 packet_get_bignum2(pctx->g_x2);
440 x1_proof = packet_get_string(&x1_proof_len);
441 x2_proof = packet_get_string(&x2_proof_len);
442 packet_check_eom();
443
444 if (!use_privsep)
445 JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
446
447 PRIVSEP(jpake_step2(pctx->grp, pctx->s, pctx->g_x3,
448 pctx->g_x1, pctx->g_x2, pctx->x4,
449 pctx->client_id, pctx->client_id_len,
450 pctx->server_id, pctx->server_id_len,
451 x1_proof, x1_proof_len,
452 x2_proof, x2_proof_len,
453 &pctx->b,
454 &x4_s_proof, &x4_s_proof_len));
455
456 bzero(x1_proof, x1_proof_len);
457 bzero(x2_proof, x2_proof_len);
458 free(x1_proof);
459 free(x2_proof);
460
461 if (!use_privsep)
462 JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
463
464 /* Send values for step 2 */
465 packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2);
466 packet_put_bignum2(pctx->b);
467 packet_put_string(x4_s_proof, x4_s_proof_len);
468 packet_send();
469 packet_write_wait();
470
471 bzero(x4_s_proof, x4_s_proof_len);
472 free(x4_s_proof);
473
474 /* Expect step 2 packet from peer */
475 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2,
476 input_userauth_jpake_client_step2);
477}
478
479/* ARGSUSED */
480static void
481input_userauth_jpake_client_step2(int type, u_int32_t seq, void *ctxt)
482{
483 Authctxt *authctxt = ctxt;
484 struct jpake_ctx *pctx = authctxt->jpake_ctx;
485 u_char *x2_s_proof;
486 u_int x2_s_proof_len;
487
488 /* Disable this message */
489 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL);
490
491 if ((pctx->a = BN_new()) == NULL)
492 fatal("%s: BN_new", __func__);
493
494 /* Fetch step 2 values */
495 packet_get_bignum2(pctx->a);
496 x2_s_proof = packet_get_string(&x2_s_proof_len);
497 packet_check_eom();
498
499 if (!use_privsep)
500 JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
501
502 /* Derive shared key and calculate confirmation hash */
503 PRIVSEP(jpake_key_confirm(pctx->grp, pctx->s, pctx->a,
504 pctx->x4, pctx->g_x3, pctx->g_x4, pctx->g_x1, pctx->g_x2,
505 pctx->server_id, pctx->server_id_len,
506 pctx->client_id, pctx->client_id_len,
507 session_id2, session_id2_len,
508 x2_s_proof, x2_s_proof_len,
509 &pctx->k,
510 &pctx->h_k_sid_sessid, &pctx->h_k_sid_sessid_len));
511
512 bzero(x2_s_proof, x2_s_proof_len);
513 free(x2_s_proof);
514
515 if (!use_privsep)
516 JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
517
518 /* Send key confirmation proof */
519 packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM);
520 packet_put_string(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len);
521 packet_send();
522 packet_write_wait();
523
524 /* Expect confirmation from peer */
525 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM,
526 input_userauth_jpake_client_confirm);
527}
528
529/* ARGSUSED */
530static void
531input_userauth_jpake_client_confirm(int type, u_int32_t seq, void *ctxt)
532{
533 Authctxt *authctxt = ctxt;
534 struct jpake_ctx *pctx = authctxt->jpake_ctx;
535 int authenticated = 0;
536
537 /* Disable this message */
538 dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL);
539
540 pctx->h_k_cid_sessid = packet_get_string(&pctx->h_k_cid_sessid_len);
541 packet_check_eom();
542
543 if (!use_privsep)
544 JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
545
546 /* Verify expected confirmation hash */
547 if (PRIVSEP(jpake_check_confirm(pctx->k,
548 pctx->client_id, pctx->client_id_len,
549 session_id2, session_id2_len,
550 pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len)) == 1)
551 authenticated = authctxt->valid ? 1 : 0;
552 else
553 debug("%s: confirmation mismatch", __func__);
554
555 /* done */
556 authctxt->postponed = 0;
557 jpake_free(authctxt->jpake_ctx);
558 authctxt->jpake_ctx = NULL;
559 userauth_finish(authctxt, authenticated, method_jpake.name, NULL);
560}
561
562#endif /* JPAKE */
563
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-02 14:48:39 +0000