| /* |
| * TLS server tickets callbacks implementation |
| * |
| * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| * This file is part of mbed TLS (https://tls.mbed.org) |
| */ |
| |
| #if !defined(MBEDTLS_CONFIG_FILE) |
| #include "mbedtls/config.h" |
| #else |
| #include MBEDTLS_CONFIG_FILE |
| #endif |
| |
| #if defined(MBEDTLS_SSL_TICKET_C) |
| |
| #if defined(MBEDTLS_PLATFORM_C) |
| #include "mbedtls/platform.h" |
| #else |
| #include <stdlib.h> |
| #define mbedtls_calloc calloc |
| #define mbedtls_free free |
| #endif |
| |
| #include "mbedtls/ssl_ticket.h" |
| |
| #include <string.h> |
| |
| /* Implementation that should never be optimized out by the compiler */ |
| static void mbedtls_zeroize( void *v, size_t n ) { |
| volatile unsigned char *p = v; while( n-- ) *p++ = 0; |
| } |
| |
| /* |
| * Initialze context |
| */ |
| void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx ) |
| { |
| memset( ctx, 0, sizeof( mbedtls_ssl_ticket_context ) ); |
| |
| #if defined(MBEDTLS_THREADING_C) |
| mbedtls_mutex_init( &ctx->mutex ); |
| #endif |
| } |
| |
| #define MAX_KEY_BYTES 32 /* 256 bits */ |
| |
| /* |
| * Generate/update a key |
| */ |
| static int ssl_ticket_gen_key( mbedtls_ssl_ticket_context *ctx, |
| unsigned char index ) |
| { |
| int ret; |
| unsigned char buf[MAX_KEY_BYTES]; |
| mbedtls_ssl_ticket_key *key = ctx->keys + index; |
| |
| #if defined(MBEDTLS_HAVE_TIME) |
| key->generation_time = (uint32_t) mbedtls_time( NULL ); |
| #endif |
| |
| if( ( ret = ctx->f_rng( ctx->p_rng, key->name, sizeof( key->name ) ) ) != 0 ) |
| return( ret ); |
| |
| if( ( ret = ctx->f_rng( ctx->p_rng, buf, sizeof( buf ) ) ) != 0 ) |
| return( ret ); |
| |
| /* With GCM and CCM, same context can encrypt & decrypt */ |
| ret = mbedtls_cipher_setkey( &key->ctx, buf, |
| mbedtls_cipher_get_key_bitlen( &key->ctx ), |
| MBEDTLS_ENCRYPT ); |
| |
| mbedtls_zeroize( buf, sizeof( buf ) ); |
| |
| return( ret ); |
| } |
| |
| /* |
| * Rotate/generate keys if necessary |
| */ |
| static int ssl_ticket_update_keys( mbedtls_ssl_ticket_context *ctx ) |
| { |
| #if !defined(MBEDTLS_HAVE_TIME) |
| ((void) ctx); |
| #else |
| if( ctx->ticket_lifetime != 0 ) |
| { |
| uint32_t current_time = (uint32_t) mbedtls_time( NULL ); |
| uint32_t key_time = ctx->keys[ctx->active].generation_time; |
| |
| if( current_time > key_time && |
| current_time - key_time < ctx->ticket_lifetime ) |
| { |
| return( 0 ); |
| } |
| |
| ctx->active = 1 - ctx->active; |
| |
| return( ssl_ticket_gen_key( ctx, ctx->active ) ); |
| } |
| else |
| #endif /* MBEDTLS_HAVE_TIME */ |
| return( 0 ); |
| } |
| |
| /* |
| * Setup context for actual use |
| */ |
| int mbedtls_ssl_ticket_setup( mbedtls_ssl_ticket_context *ctx, |
| int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, |
| mbedtls_cipher_type_t cipher, |
| uint32_t lifetime ) |
| { |
| int ret; |
| const mbedtls_cipher_info_t *cipher_info; |
| |
| ctx->f_rng = f_rng; |
| ctx->p_rng = p_rng; |
| |
| ctx->ticket_lifetime = lifetime; |
| |
| cipher_info = mbedtls_cipher_info_from_type( cipher); |
| if( cipher_info == NULL ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| if( cipher_info->mode != MBEDTLS_MODE_GCM && |
| cipher_info->mode != MBEDTLS_MODE_CCM ) |
| { |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| } |
| |
| if( cipher_info->key_bitlen > 8 * MAX_KEY_BYTES ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| if( ( ret = mbedtls_cipher_setup( &ctx->keys[0].ctx, cipher_info ) ) != 0 || |
| ( ret = mbedtls_cipher_setup( &ctx->keys[1].ctx, cipher_info ) ) != 0 ) |
| { |
| return( ret ); |
| } |
| |
| if( ( ret = ssl_ticket_gen_key( ctx, 0 ) ) != 0 || |
| ( ret = ssl_ticket_gen_key( ctx, 1 ) ) != 0 ) |
| { |
| return( ret ); |
| } |
| |
| return( 0 ); |
| } |
| |
| /* |
| * Serialize a session in the following format: |
| * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session) |
| * n . n+2 peer_cert length = m (0 if no certificate) |
| * n+3 . n+2+m peer cert ASN.1 |
| */ |
| static int ssl_save_session( const mbedtls_ssl_session *session, |
| unsigned char *buf, size_t buf_len, |
| size_t *olen ) |
| { |
| unsigned char *p = buf; |
| size_t left = buf_len; |
| #if defined(MBEDTLS_X509_CRT_PARSE_C) |
| size_t cert_len; |
| #endif /* MBEDTLS_X509_CRT_PARSE_C */ |
| |
| if( left < sizeof( mbedtls_ssl_session ) ) |
| return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); |
| |
| memcpy( p, session, sizeof( mbedtls_ssl_session ) ); |
| p += sizeof( mbedtls_ssl_session ); |
| left -= sizeof( mbedtls_ssl_session ); |
| |
| #if defined(MBEDTLS_X509_CRT_PARSE_C) |
| if( session->peer_cert == NULL ) |
| cert_len = 0; |
| else |
| cert_len = session->peer_cert->raw.len; |
| |
| if( left < 3 + cert_len ) |
| return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); |
| |
| *p++ = (unsigned char)( cert_len >> 16 & 0xFF ); |
| *p++ = (unsigned char)( cert_len >> 8 & 0xFF ); |
| *p++ = (unsigned char)( cert_len & 0xFF ); |
| |
| if( session->peer_cert != NULL ) |
| memcpy( p, session->peer_cert->raw.p, cert_len ); |
| |
| p += cert_len; |
| #endif /* MBEDTLS_X509_CRT_PARSE_C */ |
| |
| *olen = p - buf; |
| |
| return( 0 ); |
| } |
| |
| /* |
| * Unserialise session, see ssl_save_session() |
| */ |
| static int ssl_load_session( mbedtls_ssl_session *session, |
| const unsigned char *buf, size_t len ) |
| { |
| const unsigned char *p = buf; |
| const unsigned char * const end = buf + len; |
| #if defined(MBEDTLS_X509_CRT_PARSE_C) |
| size_t cert_len; |
| #endif /* MBEDTLS_X509_CRT_PARSE_C */ |
| |
| if( p + sizeof( mbedtls_ssl_session ) > end ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| memcpy( session, p, sizeof( mbedtls_ssl_session ) ); |
| p += sizeof( mbedtls_ssl_session ); |
| |
| #if defined(MBEDTLS_X509_CRT_PARSE_C) |
| if( p + 3 > end ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| cert_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2]; |
| p += 3; |
| |
| if( cert_len == 0 ) |
| { |
| session->peer_cert = NULL; |
| } |
| else |
| { |
| int ret; |
| |
| if( p + cert_len > end ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| session->peer_cert = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) ); |
| |
| if( session->peer_cert == NULL ) |
| return( MBEDTLS_ERR_SSL_ALLOC_FAILED ); |
| |
| mbedtls_x509_crt_init( session->peer_cert ); |
| |
| if( ( ret = mbedtls_x509_crt_parse_der( session->peer_cert, |
| p, cert_len ) ) != 0 ) |
| { |
| mbedtls_x509_crt_free( session->peer_cert ); |
| mbedtls_free( session->peer_cert ); |
| session->peer_cert = NULL; |
| return( ret ); |
| } |
| |
| p += cert_len; |
| } |
| #endif /* MBEDTLS_X509_CRT_PARSE_C */ |
| |
| if( p != end ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| return( 0 ); |
| } |
| |
| /* |
| * Create session ticket, with the following structure: |
| * |
| * struct { |
| * opaque key_name[4]; |
| * opaque iv[12]; |
| * opaque encrypted_state<0..2^16-1>; |
| * opaque tag[16]; |
| * } ticket; |
| * |
| * The key_name, iv, and length of encrypted_state are the additional |
| * authenticated data. |
| */ |
| int mbedtls_ssl_ticket_write( void *p_ticket, |
| const mbedtls_ssl_session *session, |
| unsigned char *start, |
| const unsigned char *end, |
| size_t *tlen, |
| uint32_t *ticket_lifetime ) |
| { |
| int ret; |
| mbedtls_ssl_ticket_context *ctx = p_ticket; |
| mbedtls_ssl_ticket_key *key; |
| unsigned char *key_name = start; |
| unsigned char *iv = start + 4; |
| unsigned char *state_len_bytes = iv + 12; |
| unsigned char *state = state_len_bytes + 2; |
| unsigned char *tag; |
| size_t clear_len, ciph_len; |
| |
| *tlen = 0; |
| |
| if( ctx == NULL || ctx->f_rng == NULL ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| /* We need at least 4 bytes for key_name, 12 for IV, 2 for len 16 for tag, |
| * in addition to session itself, that will be checked when writing it. */ |
| if( end - start < 4 + 12 + 2 + 16 ) |
| return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); |
| |
| #if defined(MBEDTLS_THREADING_C) |
| if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) |
| return( ret ); |
| #endif |
| |
| if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 ) |
| goto cleanup; |
| |
| key = &ctx->keys[ctx->active]; |
| |
| *ticket_lifetime = ctx->ticket_lifetime; |
| |
| memcpy( key_name, key->name, 4 ); |
| |
| if( ( ret = ctx->f_rng( ctx->p_rng, iv, 12 ) ) != 0 ) |
| goto cleanup; |
| |
| /* Dump session state */ |
| if( ( ret = ssl_save_session( session, |
| state, end - state, &clear_len ) ) != 0 || |
| (unsigned long) clear_len > 65535 ) |
| { |
| goto cleanup; |
| } |
| state_len_bytes[0] = ( clear_len >> 8 ) & 0xff; |
| state_len_bytes[1] = ( clear_len ) & 0xff; |
| |
| /* Encrypt and authenticate */ |
| tag = state + clear_len; |
| if( ( ret = mbedtls_cipher_auth_encrypt( &key->ctx, |
| iv, 12, key_name, 4 + 12 + 2, |
| state, clear_len, state, &ciph_len, tag, 16 ) ) != 0 ) |
| { |
| goto cleanup; |
| } |
| if( ciph_len != clear_len ) |
| { |
| ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; |
| goto cleanup; |
| } |
| |
| *tlen = 4 + 12 + 2 + 16 + ciph_len; |
| |
| cleanup: |
| #if defined(MBEDTLS_THREADING_C) |
| if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) |
| return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); |
| #endif |
| |
| return( ret ); |
| } |
| |
| /* |
| * Select key based on name |
| */ |
| static mbedtls_ssl_ticket_key *ssl_ticket_select_key( |
| mbedtls_ssl_ticket_context *ctx, |
| const unsigned char name[4] ) |
| { |
| unsigned char i; |
| |
| for( i = 0; i < sizeof( ctx->keys ) / sizeof( *ctx->keys ); i++ ) |
| if( memcmp( name, ctx->keys[i].name, 4 ) == 0 ) |
| return( &ctx->keys[i] ); |
| |
| return( NULL ); |
| } |
| |
| /* |
| * Load session ticket (see mbedtls_ssl_ticket_write for structure) |
| */ |
| int mbedtls_ssl_ticket_parse( void *p_ticket, |
| mbedtls_ssl_session *session, |
| unsigned char *buf, |
| size_t len ) |
| { |
| int ret; |
| mbedtls_ssl_ticket_context *ctx = p_ticket; |
| mbedtls_ssl_ticket_key *key; |
| unsigned char *key_name = buf; |
| unsigned char *iv = buf + 4; |
| unsigned char *enc_len_p = iv + 12; |
| unsigned char *ticket = enc_len_p + 2; |
| unsigned char *tag; |
| size_t enc_len, clear_len; |
| |
| if( ctx == NULL || ctx->f_rng == NULL ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| /* See mbedtls_ssl_ticket_write() */ |
| if( len < 4 + 12 + 2 + 16 ) |
| return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); |
| |
| #if defined(MBEDTLS_THREADING_C) |
| if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) |
| return( ret ); |
| #endif |
| |
| if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 ) |
| goto cleanup; |
| |
| enc_len = ( enc_len_p[0] << 8 ) | enc_len_p[1]; |
| tag = ticket + enc_len; |
| |
| if( len != 4 + 12 + 2 + enc_len + 16 ) |
| { |
| ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA; |
| goto cleanup; |
| } |
| |
| /* Select key */ |
| if( ( key = ssl_ticket_select_key( ctx, key_name ) ) == NULL ) |
| { |
| /* We can't know for sure but this is a likely option unless we're |
| * under attack - this is only informative anyway */ |
| ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED; |
| goto cleanup; |
| } |
| |
| /* Decrypt and authenticate */ |
| if( ( ret = mbedtls_cipher_auth_decrypt( &key->ctx, iv, 12, |
| key_name, 4 + 12 + 2, ticket, enc_len, |
| ticket, &clear_len, tag, 16 ) ) != 0 ) |
| { |
| if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED ) |
| ret = MBEDTLS_ERR_SSL_INVALID_MAC; |
| |
| goto cleanup; |
| } |
| if( clear_len != enc_len ) |
| { |
| ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; |
| goto cleanup; |
| } |
| |
| /* Actually load session */ |
| if( ( ret = ssl_load_session( session, ticket, clear_len ) ) != 0 ) |
| goto cleanup; |
| |
| #if defined(MBEDTLS_HAVE_TIME) |
| { |
| /* Check for expiration */ |
| mbedtls_time_t current_time = mbedtls_time( NULL ); |
| |
| if( current_time < session->start || |
| (uint32_t)( current_time - session->start ) > ctx->ticket_lifetime ) |
| { |
| ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED; |
| goto cleanup; |
| } |
| } |
| #endif |
| |
| cleanup: |
| #if defined(MBEDTLS_THREADING_C) |
| if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) |
| return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); |
| #endif |
| |
| return( ret ); |
| } |
| |
| /* |
| * Free context |
| */ |
| void mbedtls_ssl_ticket_free( mbedtls_ssl_ticket_context *ctx ) |
| { |
| mbedtls_cipher_free( &ctx->keys[0].ctx ); |
| mbedtls_cipher_free( &ctx->keys[1].ctx ); |
| |
| #if defined(MBEDTLS_THREADING_C) |
| mbedtls_mutex_free( &ctx->mutex ); |
| #endif |
| |
| mbedtls_zeroize( ctx, sizeof( mbedtls_ssl_ticket_context ) ); |
| } |
| |
| #endif /* MBEDTLS_SSL_TICKET_C */ |