2 * TLS server tickets callbacks implementation
4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: Apache-2.0
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
19 * This file is part of mbed TLS (https://tls.mbed.org)
22 #if !defined(MBEDTLS_CONFIG_FILE)
23 #include "mbedtls/config.h"
25 #include MBEDTLS_CONFIG_FILE
28 #if defined(MBEDTLS_SSL_TICKET_C)
30 #if defined(MBEDTLS_PLATFORM_C)
31 #include "mbedtls/platform.h"
34 #define mbedtls_calloc calloc
35 #define mbedtls_free free
38 #include "mbedtls/ssl_ticket.h"
39 #include "mbedtls/platform_util.h"
46 void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx )
48 memset( ctx, 0, sizeof( mbedtls_ssl_ticket_context ) );
50 #if defined(MBEDTLS_THREADING_C)
51 mbedtls_mutex_init( &ctx->mutex );
55 #define MAX_KEY_BYTES 32 /* 256 bits */
57 #define TICKET_KEY_NAME_BYTES 4
58 #define TICKET_IV_BYTES 12
59 #define TICKET_CRYPT_LEN_BYTES 2
60 #define TICKET_AUTH_TAG_BYTES 16
62 #define TICKET_MIN_LEN ( TICKET_KEY_NAME_BYTES + \
64 TICKET_CRYPT_LEN_BYTES + \
65 TICKET_AUTH_TAG_BYTES )
66 #define TICKET_ADD_DATA_LEN ( TICKET_KEY_NAME_BYTES + \
68 TICKET_CRYPT_LEN_BYTES )
71 * Generate/update a key
73 static int ssl_ticket_gen_key( mbedtls_ssl_ticket_context *ctx,
77 unsigned char buf[MAX_KEY_BYTES];
78 mbedtls_ssl_ticket_key *key = ctx->keys + index;
80 #if defined(MBEDTLS_HAVE_TIME)
81 key->generation_time = (uint32_t) mbedtls_time( NULL );
84 if( ( ret = ctx->f_rng( ctx->p_rng, key->name, sizeof( key->name ) ) ) != 0 )
87 if( ( ret = ctx->f_rng( ctx->p_rng, buf, sizeof( buf ) ) ) != 0 )
90 /* With GCM and CCM, same context can encrypt & decrypt */
91 ret = mbedtls_cipher_setkey( &key->ctx, buf,
92 mbedtls_cipher_get_key_bitlen( &key->ctx ),
95 mbedtls_platform_zeroize( buf, sizeof( buf ) );
101 * Rotate/generate keys if necessary
103 static int ssl_ticket_update_keys( mbedtls_ssl_ticket_context *ctx )
105 #if !defined(MBEDTLS_HAVE_TIME)
108 if( ctx->ticket_lifetime != 0 )
110 uint32_t current_time = (uint32_t) mbedtls_time( NULL );
111 uint32_t key_time = ctx->keys[ctx->active].generation_time;
113 if( current_time >= key_time &&
114 current_time - key_time < ctx->ticket_lifetime )
119 ctx->active = 1 - ctx->active;
121 return( ssl_ticket_gen_key( ctx, ctx->active ) );
124 #endif /* MBEDTLS_HAVE_TIME */
129 * Setup context for actual use
131 int mbedtls_ssl_ticket_setup( mbedtls_ssl_ticket_context *ctx,
132 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
133 mbedtls_cipher_type_t cipher,
137 const mbedtls_cipher_info_t *cipher_info;
142 ctx->ticket_lifetime = lifetime;
144 cipher_info = mbedtls_cipher_info_from_type( cipher);
145 if( cipher_info == NULL )
146 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
148 if( cipher_info->mode != MBEDTLS_MODE_GCM &&
149 cipher_info->mode != MBEDTLS_MODE_CCM )
151 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
154 if( cipher_info->key_bitlen > 8 * MAX_KEY_BYTES )
155 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
157 #if defined(MBEDTLS_USE_PSA_CRYPTO)
158 ret = mbedtls_cipher_setup_psa( &ctx->keys[0].ctx,
159 cipher_info, TICKET_AUTH_TAG_BYTES );
160 if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
162 /* We don't yet expect to support all ciphers through PSA,
163 * so allow fallback to ordinary mbedtls_cipher_setup(). */
164 if( ret == MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
165 #endif /* MBEDTLS_USE_PSA_CRYPTO */
166 if( ( ret = mbedtls_cipher_setup( &ctx->keys[0].ctx, cipher_info ) ) != 0 )
169 #if defined(MBEDTLS_USE_PSA_CRYPTO)
170 ret = mbedtls_cipher_setup_psa( &ctx->keys[1].ctx,
171 cipher_info, TICKET_AUTH_TAG_BYTES );
172 if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
174 if( ret == MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
175 #endif /* MBEDTLS_USE_PSA_CRYPTO */
176 if( ( ret = mbedtls_cipher_setup( &ctx->keys[1].ctx, cipher_info ) ) != 0 )
179 if( ( ret = ssl_ticket_gen_key( ctx, 0 ) ) != 0 ||
180 ( ret = ssl_ticket_gen_key( ctx, 1 ) ) != 0 )
189 * Serialize a session in the following format:
191 * - If MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is enabled:
192 * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session)
193 * n . n+2 peer_cert length = m (0 if no certificate)
194 * n+3 . n+2+m peer cert ASN.1
196 * - If MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is disabled:
197 * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session)
198 * n . n length of peer certificate digest = k (0 if no digest)
199 * n+1 . n+k peer certificate digest (digest type encoded in session)
201 static int ssl_save_session( const mbedtls_ssl_session *session,
202 unsigned char *buf, size_t buf_len,
205 unsigned char *p = buf;
206 size_t left = buf_len;
207 #if defined(MBEDTLS_X509_CRT_PARSE_C)
208 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
211 size_t cert_digest_len;
212 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
213 #endif /* MBEDTLS_X509_CRT_PARSE_C */
215 if( left < sizeof( mbedtls_ssl_session ) )
216 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
218 /* This also copies the values of pointer fields in the
219 * session to be serialized, but they'll be ignored when
220 * loading the session through ssl_load_session(). */
221 memcpy( p, session, sizeof( mbedtls_ssl_session ) );
222 p += sizeof( mbedtls_ssl_session );
223 left -= sizeof( mbedtls_ssl_session );
225 #if defined(MBEDTLS_X509_CRT_PARSE_C)
226 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
227 if( session->peer_cert == NULL )
230 cert_len = session->peer_cert->raw.len;
232 if( left < 3 + cert_len )
233 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
235 *p++ = (unsigned char)( ( cert_len >> 16 ) & 0xFF );
236 *p++ = (unsigned char)( ( cert_len >> 8 ) & 0xFF );
237 *p++ = (unsigned char)( ( cert_len ) & 0xFF );
240 if( session->peer_cert != NULL )
241 memcpy( p, session->peer_cert->raw.p, cert_len );
245 #else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
246 if( session->peer_cert_digest != NULL )
249 cert_digest_len = session->peer_cert_digest_len;
251 if( left < 1 + cert_digest_len )
252 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
254 *p++ = (unsigned char) cert_digest_len;
257 if( session->peer_cert_digest != NULL )
258 memcpy( p, session->peer_cert_digest, cert_digest_len );
260 p += cert_digest_len;
261 left -= cert_digest_len;
262 #endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
263 #endif /* MBEDTLS_X509_CRT_PARSE_C */
271 * Unserialise session, see ssl_save_session()
273 static int ssl_load_session( mbedtls_ssl_session *session,
274 const unsigned char *buf, size_t len )
276 const unsigned char *p = buf;
277 const unsigned char * const end = buf + len;
278 #if defined(MBEDTLS_X509_CRT_PARSE_C)
279 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
282 size_t cert_digest_len;
283 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
284 #endif /* MBEDTLS_X509_CRT_PARSE_C */
286 if( sizeof( mbedtls_ssl_session ) > (size_t)( end - p ) )
287 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
289 memcpy( session, p, sizeof( mbedtls_ssl_session ) );
290 p += sizeof( mbedtls_ssl_session );
292 /* Non-NULL pointer fields of `session` are meaningless
293 * and potentially harmful. Zeroize them for safety. */
294 #if defined(MBEDTLS_X509_CRT_PARSE_C)
295 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
296 session->peer_cert = NULL;
298 session->peer_cert_digest = NULL;
299 #endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
300 #endif /* MBEDTLS_X509_CRT_PARSE_C */
301 #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
302 session->ticket = NULL;
303 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
305 #if defined(MBEDTLS_X509_CRT_PARSE_C)
306 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
307 /* Deserialize CRT from the end of the ticket. */
308 if( 3 > (size_t)( end - p ) )
309 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
311 cert_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2];
318 if( cert_len > (size_t)( end - p ) )
319 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
321 session->peer_cert = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
323 if( session->peer_cert == NULL )
324 return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
326 mbedtls_x509_crt_init( session->peer_cert );
328 if( ( ret = mbedtls_x509_crt_parse_der( session->peer_cert,
329 p, cert_len ) ) != 0 )
331 mbedtls_x509_crt_free( session->peer_cert );
332 mbedtls_free( session->peer_cert );
333 session->peer_cert = NULL;
339 #else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
340 /* Deserialize CRT digest from the end of the ticket. */
341 if( 1 > (size_t)( end - p ) )
342 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
344 cert_digest_len = (size_t) p[0];
347 if( cert_digest_len != 0 )
349 if( cert_digest_len > (size_t)( end - p ) ||
350 cert_digest_len != session->peer_cert_digest_len )
352 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
355 session->peer_cert_digest = mbedtls_calloc( 1, cert_digest_len );
356 if( session->peer_cert_digest == NULL )
357 return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
359 memcpy( session->peer_cert_digest, p, cert_digest_len );
360 p += cert_digest_len;
362 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
363 #endif /* MBEDTLS_X509_CRT_PARSE_C */
366 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
372 * Create session ticket, with the following structure:
375 * opaque key_name[4];
377 * opaque encrypted_state<0..2^16-1>;
381 * The key_name, iv, and length of encrypted_state are the additional
382 * authenticated data.
385 int mbedtls_ssl_ticket_write( void *p_ticket,
386 const mbedtls_ssl_session *session,
387 unsigned char *start,
388 const unsigned char *end,
390 uint32_t *ticket_lifetime )
393 mbedtls_ssl_ticket_context *ctx = p_ticket;
394 mbedtls_ssl_ticket_key *key;
395 unsigned char *key_name = start;
396 unsigned char *iv = start + TICKET_KEY_NAME_BYTES;
397 unsigned char *state_len_bytes = iv + TICKET_IV_BYTES;
398 unsigned char *state = state_len_bytes + TICKET_CRYPT_LEN_BYTES;
400 size_t clear_len, ciph_len;
404 if( ctx == NULL || ctx->f_rng == NULL )
405 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
407 /* We need at least 4 bytes for key_name, 12 for IV, 2 for len 16 for tag,
408 * in addition to session itself, that will be checked when writing it. */
409 if( end - start < TICKET_MIN_LEN )
410 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
412 #if defined(MBEDTLS_THREADING_C)
413 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
417 if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 )
420 key = &ctx->keys[ctx->active];
422 *ticket_lifetime = ctx->ticket_lifetime;
424 memcpy( key_name, key->name, TICKET_KEY_NAME_BYTES );
426 if( ( ret = ctx->f_rng( ctx->p_rng, iv, TICKET_IV_BYTES ) ) != 0 )
429 /* Dump session state */
430 if( ( ret = ssl_save_session( session,
431 state, end - state, &clear_len ) ) != 0 ||
432 (unsigned long) clear_len > 65535 )
436 state_len_bytes[0] = ( clear_len >> 8 ) & 0xff;
437 state_len_bytes[1] = ( clear_len ) & 0xff;
439 /* Encrypt and authenticate */
440 tag = state + clear_len;
441 if( ( ret = mbedtls_cipher_auth_encrypt( &key->ctx,
443 /* Additional data: key name, IV and length */
444 key_name, TICKET_ADD_DATA_LEN,
445 state, clear_len, state, &ciph_len,
446 tag, TICKET_AUTH_TAG_BYTES ) ) != 0 )
450 if( ciph_len != clear_len )
452 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
456 *tlen = TICKET_MIN_LEN + ciph_len;
459 #if defined(MBEDTLS_THREADING_C)
460 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
461 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
468 * Select key based on name
470 static mbedtls_ssl_ticket_key *ssl_ticket_select_key(
471 mbedtls_ssl_ticket_context *ctx,
472 const unsigned char name[4] )
476 for( i = 0; i < sizeof( ctx->keys ) / sizeof( *ctx->keys ); i++ )
477 if( memcmp( name, ctx->keys[i].name, 4 ) == 0 )
478 return( &ctx->keys[i] );
484 * Load session ticket (see mbedtls_ssl_ticket_write for structure)
486 int mbedtls_ssl_ticket_parse( void *p_ticket,
487 mbedtls_ssl_session *session,
492 mbedtls_ssl_ticket_context *ctx = p_ticket;
493 mbedtls_ssl_ticket_key *key;
494 unsigned char *key_name = buf;
495 unsigned char *iv = buf + TICKET_KEY_NAME_BYTES;
496 unsigned char *enc_len_p = iv + TICKET_IV_BYTES;
497 unsigned char *ticket = enc_len_p + TICKET_CRYPT_LEN_BYTES;
499 size_t enc_len, clear_len;
501 if( ctx == NULL || ctx->f_rng == NULL )
502 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
504 if( len < TICKET_MIN_LEN )
505 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
507 #if defined(MBEDTLS_THREADING_C)
508 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
512 if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 )
515 enc_len = ( enc_len_p[0] << 8 ) | enc_len_p[1];
516 tag = ticket + enc_len;
518 if( len != TICKET_MIN_LEN + enc_len )
520 ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
525 if( ( key = ssl_ticket_select_key( ctx, key_name ) ) == NULL )
527 /* We can't know for sure but this is a likely option unless we're
528 * under attack - this is only informative anyway */
529 ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED;
533 /* Decrypt and authenticate */
534 if( ( ret = mbedtls_cipher_auth_decrypt( &key->ctx,
536 /* Additional data: key name, IV and length */
537 key_name, TICKET_ADD_DATA_LEN,
540 tag, TICKET_AUTH_TAG_BYTES ) ) != 0 )
542 if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED )
543 ret = MBEDTLS_ERR_SSL_INVALID_MAC;
547 if( clear_len != enc_len )
549 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
553 /* Actually load session */
554 if( ( ret = ssl_load_session( session, ticket, clear_len ) ) != 0 )
557 #if defined(MBEDTLS_HAVE_TIME)
559 /* Check for expiration */
560 mbedtls_time_t current_time = mbedtls_time( NULL );
562 if( current_time < session->start ||
563 (uint32_t)( current_time - session->start ) > ctx->ticket_lifetime )
565 ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED;
572 #if defined(MBEDTLS_THREADING_C)
573 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
574 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
583 void mbedtls_ssl_ticket_free( mbedtls_ssl_ticket_context *ctx )
585 mbedtls_cipher_free( &ctx->keys[0].ctx );
586 mbedtls_cipher_free( &ctx->keys[1].ctx );
588 #if defined(MBEDTLS_THREADING_C)
589 mbedtls_mutex_free( &ctx->mutex );
592 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ssl_ticket_context ) );
595 #endif /* MBEDTLS_SSL_TICKET_C */