Line data Source code
1 : /*
2 : * Copyright (C) 2002-2012 Free Software Foundation, Inc.
3 : *
4 : * Author: Nikos Mavrogiannopoulos
5 : *
6 : * This file is part of GnuTLS.
7 : *
8 : * The GnuTLS is free software; you can redistribute it and/or
9 : * modify it under the terms of the GNU Lesser General Public License
10 : * as published by the Free Software Foundation; either version 2.1 of
11 : * the License, or (at your option) any later version.
12 : *
13 : * This library is distributed in the hope that it will be useful, but
14 : * WITHOUT ANY WARRANTY; without even the implied warranty of
15 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 : * Lesser General Public License for more details.
17 : *
18 : * You should have received a copy of the GNU Lesser General Public License
19 : * along with this program. If not, see <https://www.gnu.org/licenses/>
20 : *
21 : */
22 :
23 : /* This file contains common stuff in Ephemeral Diffie-Hellman (DHE)
24 : * and Anonymous DH key exchange(DHA). These are used in the handshake
25 : * procedure of the certificate and anonymous authentication.
26 : */
27 :
28 : #include "gnutls_int.h"
29 : #include "auth.h"
30 : #include "errors.h"
31 : #include "dh.h"
32 : #include "num.h"
33 : #include "tls-sig.h"
34 : #include <datum.h>
35 : #include <x509.h>
36 : #include <state.h>
37 : #include <pk.h>
38 : #include <auth/dh_common.h>
39 : #include <algorithms.h>
40 : #include <auth/psk.h>
41 :
42 : #if defined(ENABLE_DHE) || defined(ENABLE_ANON)
43 :
44 : /* Frees the dh_info_st structure.
45 : */
46 13454 : void _gnutls_free_dh_info(dh_info_st * dh)
47 : {
48 13454 : dh->secret_bits = 0;
49 13454 : _gnutls_free_datum(&dh->prime);
50 13454 : _gnutls_free_datum(&dh->generator);
51 13454 : _gnutls_free_datum(&dh->public_key);
52 13454 : }
53 :
54 : int
55 2004 : _gnutls_proc_dh_common_client_kx(gnutls_session_t session,
56 : uint8_t * data, size_t _data_size,
57 : gnutls_datum_t * psk_key)
58 : {
59 2004 : uint16_t n_Y;
60 2004 : size_t _n_Y;
61 2004 : int ret;
62 2004 : ssize_t data_size = _data_size;
63 2004 : gnutls_datum_t tmp_dh_key = {NULL, 0};
64 2004 : gnutls_pk_params_st peer_pub;
65 :
66 2004 : gnutls_pk_params_init(&peer_pub);
67 :
68 2004 : DECR_LEN(data_size, 2);
69 2002 : n_Y = _gnutls_read_uint16(&data[0]);
70 2002 : _n_Y = n_Y;
71 :
72 2002 : DECR_LEN(data_size, n_Y);
73 :
74 1999 : if (data_size != 0)
75 4 : return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
76 :
77 1996 : if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.client_Y, &data[2], _n_Y)) {
78 4 : gnutls_assert();
79 4 : return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; /* most likely zero or illegal size */
80 : }
81 :
82 1992 : _gnutls_dh_set_peer_public(session, session->key.proto.tls12.dh.client_Y);
83 :
84 1992 : peer_pub.params[DH_Y] = session->key.proto.tls12.dh.client_Y;
85 :
86 : /* calculate the key after calculating the message */
87 1992 : ret = _gnutls_pk_derive(GNUTLS_PK_DH, &tmp_dh_key, &session->key.proto.tls12.dh.params, &peer_pub);
88 1992 : if (ret < 0) {
89 10 : gnutls_assert();
90 10 : goto error;
91 : }
92 :
93 1982 : if (psk_key == NULL) {
94 1629 : session->key.key.data = tmp_dh_key.data;
95 1629 : session->key.key.size = tmp_dh_key.size;
96 : } else { /* In DHE_PSK the key is set differently */
97 353 : ret =
98 353 : _gnutls_set_psk_session_key(session, psk_key,
99 : &tmp_dh_key);
100 353 : _gnutls_free_temp_key_datum(&tmp_dh_key);
101 : }
102 :
103 1982 : if (ret < 0) {
104 0 : gnutls_assert();
105 0 : goto error;
106 : }
107 :
108 : ret = 0;
109 1992 : error:
110 1992 : _gnutls_mpi_release(&session->key.proto.tls12.dh.client_Y);
111 1992 : gnutls_pk_params_clear(&session->key.proto.tls12.dh.params);
112 :
113 1992 : return ret;
114 : }
115 :
116 193 : int _gnutls_gen_dh_common_client_kx(gnutls_session_t session,
117 : gnutls_buffer_st * data)
118 : {
119 193 : return _gnutls_gen_dh_common_client_kx_int(session, data, NULL);
120 : }
121 :
122 : int
123 223 : _gnutls_gen_dh_common_client_kx_int(gnutls_session_t session,
124 : gnutls_buffer_st * data,
125 : gnutls_datum_t * pskkey)
126 : {
127 223 : int ret;
128 223 : gnutls_pk_params_st peer_pub;
129 223 : gnutls_datum_t tmp_dh_key = {NULL, 0};
130 223 : unsigned init_pos = data->length;
131 :
132 223 : gnutls_pk_params_init(&peer_pub);
133 :
134 223 : ret =
135 223 : _gnutls_pk_generate_keys(GNUTLS_PK_DH, 0,
136 : &session->key.proto.tls12.dh.params, 1);
137 223 : if (ret < 0)
138 1 : return gnutls_assert_val(ret);
139 :
140 222 : _gnutls_dh_set_secret_bits(session, _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_X]));
141 :
142 222 : ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_Y], 0);
143 222 : if (ret < 0) {
144 0 : gnutls_assert();
145 0 : goto error;
146 : }
147 :
148 222 : peer_pub.params[DH_Y] = session->key.proto.tls12.dh.client_Y;
149 :
150 : /* calculate the key after calculating the message */
151 222 : ret = _gnutls_pk_derive(GNUTLS_PK_DH, &tmp_dh_key, &session->key.proto.tls12.dh.params, &peer_pub);
152 222 : if (ret < 0) {
153 2 : gnutls_assert();
154 2 : goto error;
155 : }
156 :
157 220 : if (session->security_parameters.cs->kx_algorithm != GNUTLS_KX_DHE_PSK) {
158 193 : session->key.key.data = tmp_dh_key.data;
159 193 : session->key.key.size = tmp_dh_key.size;
160 : } else { /* In DHE_PSK the key is set differently */
161 27 : ret =
162 27 : _gnutls_set_psk_session_key(session, pskkey,
163 : &tmp_dh_key);
164 27 : _gnutls_free_temp_key_datum(&tmp_dh_key);
165 : }
166 :
167 220 : if (ret < 0) {
168 0 : gnutls_assert();
169 0 : goto error;
170 : }
171 :
172 220 : ret = data->length - init_pos;
173 :
174 222 : error:
175 222 : gnutls_pk_params_clear(&session->key.proto.tls12.dh.params);
176 222 : return ret;
177 : }
178 :
179 : /* Returns the bytes parsed */
180 : int
181 245 : _gnutls_proc_dh_common_server_kx(gnutls_session_t session,
182 : uint8_t * data, size_t _data_size)
183 : {
184 245 : uint16_t n_Y, n_g, n_p;
185 245 : size_t _n_Y, _n_g, _n_p, _n_q;
186 245 : uint8_t *data_p;
187 245 : uint8_t *data_g;
188 245 : uint8_t *data_Y;
189 245 : uint8_t *data_q = NULL;
190 245 : int i, bits, ret, p_bits;
191 245 : unsigned j;
192 245 : ssize_t data_size = _data_size;
193 :
194 : /* just in case we are resuming a session */
195 245 : gnutls_pk_params_release(&session->key.proto.tls12.dh.params);
196 :
197 245 : gnutls_pk_params_init(&session->key.proto.tls12.dh.params);
198 :
199 245 : i = 0;
200 :
201 245 : DECR_LEN(data_size, 2);
202 244 : n_p = _gnutls_read_uint16(&data[i]);
203 244 : i += 2;
204 :
205 244 : DECR_LEN(data_size, n_p);
206 242 : data_p = &data[i];
207 242 : i += n_p;
208 :
209 242 : DECR_LEN(data_size, 2);
210 242 : n_g = _gnutls_read_uint16(&data[i]);
211 242 : i += 2;
212 :
213 242 : DECR_LEN(data_size, n_g);
214 240 : data_g = &data[i];
215 240 : i += n_g;
216 :
217 240 : DECR_LEN(data_size, 2);
218 239 : n_Y = _gnutls_read_uint16(&data[i]);
219 239 : i += 2;
220 :
221 239 : DECR_LEN(data_size, n_Y);
222 237 : data_Y = &data[i];
223 :
224 237 : _n_Y = n_Y;
225 237 : _n_g = n_g;
226 237 : _n_p = n_p;
227 :
228 237 : if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.client_Y, data_Y, _n_Y) != 0) {
229 2 : gnutls_assert();
230 2 : return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
231 : }
232 :
233 : /* if we are doing RFC7919 */
234 235 : if (session->internals.priorities->groups.have_ffdhe != 0) {
235 : /* verify whether the received parameters match the advertised, otherwise
236 : * log that. */
237 419 : for (j=0;j<session->internals.priorities->groups.size;j++) {
238 403 : if (session->internals.priorities->groups.entry[j]->generator &&
239 268 : session->internals.priorities->groups.entry[j]->generator->size == n_g &&
240 248 : session->internals.priorities->groups.entry[j]->prime->size == n_p &&
241 174 : memcmp(session->internals.priorities->groups.entry[j]->generator->data,
242 171 : data_g, n_g) == 0 &&
243 171 : memcmp(session->internals.priorities->groups.entry[j]->prime->data,
244 : data_p, n_p) == 0) {
245 :
246 169 : session->internals.hsk_flags |= HSK_USED_FFDHE;
247 169 : _gnutls_session_group_set(session, session->internals.priorities->groups.entry[j]);
248 169 : session->key.proto.tls12.dh.params.qbits = *session->internals.priorities->groups.entry[j]->q_bits;
249 169 : data_q = session->internals.priorities->groups.entry[j]->q->data;
250 169 : _n_q = session->internals.priorities->groups.entry[j]->q->size;
251 169 : break;
252 : }
253 : }
254 :
255 185 : if (!(session->internals.hsk_flags & HSK_USED_FFDHE)) {
256 16 : _gnutls_audit_log(session, "FFDHE groups advertised, but server didn't support it; falling back to server's choice\n");
257 : }
258 : }
259 :
260 : #ifdef ENABLE_FIPS140
261 : if (gnutls_fips140_mode_enabled() &&
262 : !_gnutls_dh_prime_match_fips_approved(data_p, n_p, data_g, n_g, NULL, NULL)) {
263 : gnutls_assert();
264 : return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
265 : }
266 : #endif
267 :
268 235 : if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.params.params[DH_G], data_g, _n_g) != 0) {
269 2 : gnutls_assert();
270 2 : return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
271 : }
272 :
273 233 : if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.params.params[DH_P], data_p, _n_p) != 0) {
274 1 : gnutls_assert();
275 : /* we release now because session->key.proto.tls12.dh.params.params_nr is not yet set */
276 1 : _gnutls_mpi_release(&session->key.proto.tls12.dh.params.params[DH_G]);
277 1 : return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
278 : }
279 232 : if (data_q && _gnutls_mpi_init_scan_nz(
280 : &session->key.proto.tls12.dh.params.params[DH_Q],
281 : data_q, _n_q) != 0) {
282 : /* we release now because params_nr is not yet set */
283 0 : _gnutls_mpi_release(
284 : &session->key.proto.tls12.dh.params.params[DH_P]);
285 0 : _gnutls_mpi_release(
286 : &session->key.proto.tls12.dh.params.params[DH_G]);
287 0 : return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
288 : }
289 :
290 : /* include, possibly empty, q */
291 232 : session->key.proto.tls12.dh.params.params_nr = 3;
292 232 : session->key.proto.tls12.dh.params.algo = GNUTLS_PK_DH;
293 :
294 232 : if (!(session->internals.hsk_flags & HSK_USED_FFDHE)) {
295 63 : bits = _gnutls_dh_get_min_prime_bits(session);
296 63 : if (bits < 0) {
297 0 : gnutls_assert();
298 0 : return bits;
299 : }
300 :
301 63 : p_bits = _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_P]);
302 63 : if (p_bits < bits) {
303 : /* the prime used by the peer is not acceptable
304 : */
305 0 : gnutls_assert();
306 0 : _gnutls_debug_log
307 : ("Received a prime of %u bits, limit is %u\n",
308 : (unsigned) _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_P]),
309 : (unsigned) bits);
310 0 : return GNUTLS_E_DH_PRIME_UNACCEPTABLE;
311 : }
312 :
313 63 : if (p_bits >= DEFAULT_MAX_VERIFY_BITS) {
314 1 : gnutls_assert();
315 1 : _gnutls_debug_log
316 : ("Received a prime of %u bits, limit is %u\n",
317 : (unsigned) p_bits,
318 : (unsigned) DEFAULT_MAX_VERIFY_BITS);
319 1 : return GNUTLS_E_DH_PRIME_UNACCEPTABLE;
320 : }
321 : }
322 :
323 231 : _gnutls_dh_save_group(session, session->key.proto.tls12.dh.params.params[DH_G],
324 : session->key.proto.tls12.dh.params.params[DH_P]);
325 231 : _gnutls_dh_set_peer_public(session, session->key.proto.tls12.dh.client_Y);
326 :
327 231 : ret = n_Y + n_p + n_g + 6;
328 :
329 231 : return ret;
330 : }
331 :
332 : int
333 2166 : _gnutls_dh_common_print_server_kx(gnutls_session_t session,
334 : gnutls_buffer_st * data)
335 : {
336 2166 : int ret;
337 2166 : unsigned q_bits = session->key.proto.tls12.dh.params.qbits;
338 2166 : unsigned init_pos = data->length;
339 :
340 2166 : if (q_bits < 192 && q_bits != 0) {
341 0 : gnutls_assert();
342 0 : _gnutls_debug_log("too small q_bits value for DH: %u\n", q_bits);
343 : q_bits = 0; /* auto-detect */
344 : }
345 :
346 : /* Y=g^x mod p */
347 2166 : ret =
348 2166 : _gnutls_pk_generate_keys(GNUTLS_PK_DH, q_bits,
349 : &session->key.proto.tls12.dh.params, 1);
350 2166 : if (ret < 0)
351 0 : return gnutls_assert_val(ret);
352 :
353 2166 : _gnutls_dh_set_secret_bits(session, _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_X]));
354 :
355 2166 : ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_P], 0);
356 2166 : if (ret < 0) {
357 0 : gnutls_assert();
358 0 : goto cleanup;
359 : }
360 :
361 2166 : ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_G], 0);
362 2166 : if (ret < 0) {
363 0 : gnutls_assert();
364 0 : goto cleanup;
365 : }
366 :
367 2166 : ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_Y], 0);
368 2166 : if (ret < 0) {
369 0 : gnutls_assert();
370 0 : goto cleanup;
371 : }
372 :
373 2166 : ret = data->length - init_pos;
374 :
375 : cleanup:
376 : return ret;
377 : }
378 :
379 : #endif
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