/* * TLS server tickets callbacks implementation * * Copyright The Mbed TLS Contributors * 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. */ #include "common.h" #if defined(MBEDTLS_SSL_TICKET_C) #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include #define mbedtls_calloc calloc #define mbedtls_free free #endif #include "ssl_misc.h" #include "mbedtls/ssl_ticket.h" #include "mbedtls/error.h" #include "mbedtls/platform_util.h" #include /* * 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 MBEDTLS_SSL_TICKET_MAX_KEY_BYTES #define TICKET_KEY_NAME_BYTES MBEDTLS_SSL_TICKET_KEY_NAME_BYTES #define TICKET_IV_BYTES 12 #define TICKET_CRYPT_LEN_BYTES 2 #define TICKET_AUTH_TAG_BYTES 16 #define TICKET_MIN_LEN ( TICKET_KEY_NAME_BYTES + \ TICKET_IV_BYTES + \ TICKET_CRYPT_LEN_BYTES + \ TICKET_AUTH_TAG_BYTES ) #define TICKET_ADD_DATA_LEN ( TICKET_KEY_NAME_BYTES + \ TICKET_IV_BYTES + \ TICKET_CRYPT_LEN_BYTES ) /* * Generate/update a key */ static int ssl_ticket_gen_key( mbedtls_ssl_ticket_context *ctx, unsigned char index ) { int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; unsigned char buf[MAX_KEY_BYTES]; mbedtls_ssl_ticket_key *key = ctx->keys + index; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; #endif #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 ); #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_DECRYPT ); psa_set_key_algorithm( &attributes, key->alg ); psa_set_key_type( &attributes, key->key_type ); psa_set_key_bits( &attributes, key->key_bits ); ret = psa_ssl_status_to_mbedtls( psa_import_key( &attributes, buf, PSA_BITS_TO_BYTES( key->key_bits ), &key->key ) ); #else /* 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 ); #endif /* MBEDTLS_USE_PSA_CRYPTO */ mbedtls_platform_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 defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; #endif if( current_time >= key_time && current_time - key_time < ctx->ticket_lifetime ) { return( 0 ); } ctx->active = 1 - ctx->active; #if defined(MBEDTLS_USE_PSA_CRYPTO) if( ( status = psa_destroy_key( ctx->keys[ctx->active].key ) ) != PSA_SUCCESS ) { return psa_ssl_status_to_mbedtls( status ); } #endif /* MBEDTLS_USE_PSA_CRYPTO */ return( ssl_ticket_gen_key( ctx, ctx->active ) ); } else #endif /* MBEDTLS_HAVE_TIME */ return( 0 ); } /* * Rotate active session ticket encryption key */ int mbedtls_ssl_ticket_rotate( mbedtls_ssl_ticket_context *ctx, const unsigned char *name, size_t nlength, const unsigned char *k, size_t klength, uint32_t lifetime ) { const unsigned char idx = 1 - ctx->active; mbedtls_ssl_ticket_key * const key = ctx->keys + idx; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; const size_t bitlen = key->key_bits; #else const int bitlen = mbedtls_cipher_get_key_bitlen( &key->ctx ); #endif if( nlength < TICKET_KEY_NAME_BYTES || klength * 8 < (size_t)bitlen ) return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA ); #if defined(MBEDTLS_USE_PSA_CRYPTO) if( ( status = psa_destroy_key( key->key ) ) != PSA_SUCCESS ) { ret = psa_ssl_status_to_mbedtls( status ); return( ret ); } psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_DECRYPT ); psa_set_key_algorithm( &attributes, key->alg ); psa_set_key_type( &attributes, key->key_type ); psa_set_key_bits( &attributes, key->key_bits ); if( ( status = psa_import_key( &attributes, k, PSA_BITS_TO_BYTES( key->key_bits ), &key->key ) ) != PSA_SUCCESS ) { ret = psa_ssl_status_to_mbedtls( status ); return( ret ); } #else ret = mbedtls_cipher_setkey( &key->ctx, k, bitlen, MBEDTLS_ENCRYPT ); if( ret != 0 ) return( ret ); #endif /* MBEDTLS_USE_PSA_CRYPTO */ ctx->active = idx; ctx->ticket_lifetime = lifetime; memcpy( key->name, name, TICKET_KEY_NAME_BYTES ); #if defined(MBEDTLS_HAVE_TIME) key->generation_time = (uint32_t) mbedtls_time( NULL ); #endif 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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; size_t key_bits; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_algorithm_t alg; psa_key_type_t key_type; #else const mbedtls_cipher_info_t *cipher_info; #endif /* MBEDTLS_USE_PSA_CRYPTO */ #if defined(MBEDTLS_USE_PSA_CRYPTO) if( mbedtls_ssl_cipher_to_psa( cipher, TICKET_AUTH_TAG_BYTES, &alg, &key_type, &key_bits ) != PSA_SUCCESS ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); if( PSA_ALG_IS_AEAD( alg ) == 0 ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); #else cipher_info = mbedtls_cipher_info_from_type( cipher ); if( mbedtls_cipher_info_get_mode( cipher_info ) != MBEDTLS_MODE_GCM && mbedtls_cipher_info_get_mode( cipher_info ) != MBEDTLS_MODE_CCM && mbedtls_cipher_info_get_mode( cipher_info ) != MBEDTLS_MODE_CHACHAPOLY ) { return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); } key_bits = mbedtls_cipher_info_get_key_bitlen( cipher_info ); #endif /* MBEDTLS_USE_PSA_CRYPTO */ if( key_bits > 8 * MAX_KEY_BYTES ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); ctx->f_rng = f_rng; ctx->p_rng = p_rng; ctx->ticket_lifetime = lifetime; #if defined(MBEDTLS_USE_PSA_CRYPTO) ctx->keys[0].alg = alg; ctx->keys[0].key_type = key_type; ctx->keys[0].key_bits = key_bits; ctx->keys[1].alg = alg; ctx->keys[1].key_type = key_type; ctx->keys[1].key_bits = key_bits; #else if( ( ret = mbedtls_cipher_setup( &ctx->keys[0].ctx, cipher_info ) ) != 0 ) return( ret ); if( ( ret = mbedtls_cipher_setup( &ctx->keys[1].ctx, cipher_info ) ) != 0 ) return( ret ); #endif /* MBEDTLS_USE_PSA_CRYPTO */ if( ( ret = ssl_ticket_gen_key( ctx, 0 ) ) != 0 || ( ret = ssl_ticket_gen_key( ctx, 1 ) ) != 0 ) { return( ret ); } 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_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_ticket_context *ctx = p_ticket; mbedtls_ssl_ticket_key *key; unsigned char *key_name = start; unsigned char *iv = start + TICKET_KEY_NAME_BYTES; unsigned char *state_len_bytes = iv + TICKET_IV_BYTES; unsigned char *state = state_len_bytes + TICKET_CRYPT_LEN_BYTES; size_t clear_len, ciph_len; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; #endif *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. */ MBEDTLS_SSL_CHK_BUF_PTR( start, end, TICKET_MIN_LEN ); #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, TICKET_KEY_NAME_BYTES ); if( ( ret = ctx->f_rng( ctx->p_rng, iv, TICKET_IV_BYTES ) ) != 0 ) goto cleanup; /* Dump session state */ if( ( ret = mbedtls_ssl_session_save( session, state, end - state, &clear_len ) ) != 0 || (unsigned long) clear_len > 65535 ) { goto cleanup; } MBEDTLS_PUT_UINT16_BE( clear_len, state_len_bytes, 0 ); /* Encrypt and authenticate */ #if defined(MBEDTLS_USE_PSA_CRYPTO) if( ( status = psa_aead_encrypt( key->key, key->alg, iv, TICKET_IV_BYTES, key_name, TICKET_ADD_DATA_LEN, state, clear_len, state, end - state, &ciph_len ) ) != PSA_SUCCESS ) { ret = psa_ssl_status_to_mbedtls( status ); goto cleanup; } #else if( ( ret = mbedtls_cipher_auth_encrypt_ext( &key->ctx, iv, TICKET_IV_BYTES, /* Additional data: key name, IV and length */ key_name, TICKET_ADD_DATA_LEN, state, clear_len, state, end - state, &ciph_len, TICKET_AUTH_TAG_BYTES ) ) != 0 ) { goto cleanup; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ if( ciph_len != clear_len + TICKET_AUTH_TAG_BYTES ) { ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; goto cleanup; } *tlen = TICKET_MIN_LEN + ciph_len - TICKET_AUTH_TAG_BYTES; 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_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_ssl_ticket_context *ctx = p_ticket; mbedtls_ssl_ticket_key *key; unsigned char *key_name = buf; unsigned char *iv = buf + TICKET_KEY_NAME_BYTES; unsigned char *enc_len_p = iv + TICKET_IV_BYTES; unsigned char *ticket = enc_len_p + TICKET_CRYPT_LEN_BYTES; size_t enc_len, clear_len; #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; #endif if( ctx == NULL || ctx->f_rng == NULL ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); if( len < TICKET_MIN_LEN ) 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]; if( len != TICKET_MIN_LEN + enc_len ) { 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 defined(MBEDTLS_USE_PSA_CRYPTO) if( ( status = psa_aead_decrypt( key->key, key->alg, iv, TICKET_IV_BYTES, key_name, TICKET_ADD_DATA_LEN, ticket, enc_len + TICKET_AUTH_TAG_BYTES, ticket, enc_len, &clear_len ) ) != PSA_SUCCESS ) { ret = psa_ssl_status_to_mbedtls( status ); goto cleanup; } #else if( ( ret = mbedtls_cipher_auth_decrypt_ext( &key->ctx, iv, TICKET_IV_BYTES, /* Additional data: key name, IV and length */ key_name, TICKET_ADD_DATA_LEN, ticket, enc_len + TICKET_AUTH_TAG_BYTES, ticket, enc_len, &clear_len, TICKET_AUTH_TAG_BYTES ) ) != 0 ) { if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED ) ret = MBEDTLS_ERR_SSL_INVALID_MAC; goto cleanup; } #endif /* MBEDTLS_USE_PSA_CRYPTO */ if( clear_len != enc_len ) { ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; goto cleanup; } /* Actually load session */ if( ( ret = mbedtls_ssl_session_load( 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 ) { #if defined(MBEDTLS_USE_PSA_CRYPTO) psa_destroy_key( ctx->keys[0].key ); psa_destroy_key( ctx->keys[1].key ); #else mbedtls_cipher_free( &ctx->keys[0].ctx ); mbedtls_cipher_free( &ctx->keys[1].ctx ); #endif /* MBEDTLS_USE_PSA_CRYPTO */ #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_free( &ctx->mutex ); #endif mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ssl_ticket_context ) ); } #endif /* MBEDTLS_SSL_TICKET_C */