diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h index 06188bebc..9ad04181a 100644 --- a/include/mbedtls/ssl_internal.h +++ b/include/mbedtls/ssl_internal.h @@ -852,6 +852,50 @@ int mbedtls_ssl_get_key_exchange_md_tls1_2( mbedtls_ssl_context *ssl, #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \ MBEDTLS_SSL_PROTO_TLS1_2 */ +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \ + ( defined(MBEDTLS_SSL_PROTO_TLS1) || \ + defined(MBEDTLS_SSL_PROTO_TLS1_1) | \ + defined(MBEDTLS_SSL_PROTO_TLS1_2) ) +/** \brief Compute the HMAC of variable-length data with constant flow. + * + * This function computes the HMAC of the concatenation of \p add_data and \p + * data, and does with a code flow and memory access pattern that does not + * depend on \p data_len_secret, but only on \p min_data_len and \p + * max_data_len. In particular, this function always reads exactly \p + * max_data_len bytes from \p data. + * + * \param ctx The HMAC context. It must have keys configured + * with mbedtls_md_hmac_starts(). It is reset using + * mbedtls_md_hmac_reset() after the computation is + * complete to prepare for the next computation. + * \param add_data The additional data prepended to \p data. This + * must point to a readable buffer of \p add_data_len + * bytes. + * \param add_data_len The length of \p add_data in bytes. + * \param data The data appended to \p add_data. This must point + * to a readable buffer of \p max_data_len bytes. + * \param data_len_secret The length of the data to process in \p data. + * This must be no less than \p min_data_len and no + * greated than \p max_data_len. + * \param min_data_len The minimal length of \p data in bytes. + * \param max_data_len The maximal length of \p data in bytes. + * \param output The HMAC will be written here. This must point to + * a writeable buffer of sufficient size to hold the + * HMAC value. + * + * \retval 0 + * Success. + * \retval MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED + * The hardware accelerator failed. + */ +int mbedtls_ssl_cf_hmac( + mbedtls_md_context_t *ctx, + const unsigned char *add_data, size_t add_data_len, + const unsigned char *data, size_t data_len_secret, + size_t min_data_len, size_t max_data_len, + unsigned char *output ); +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC && TLS 1.0-1.2 */ + #ifdef __cplusplus } #endif diff --git a/library/ssl_tls.c b/library/ssl_tls.c index 34485d2ce..8bc79be05 100644 --- a/library/ssl_tls.c +++ b/library/ssl_tls.c @@ -1805,6 +1805,32 @@ static int ssl_encrypt_buf( mbedtls_ssl_context *ssl ) return( 0 ); } +#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \ + ( defined(MBEDTLS_SSL_PROTO_TLS1) || \ + defined(MBEDTLS_SSL_PROTO_TLS1_1) || \ + defined(MBEDTLS_SSL_PROTO_TLS1_2) ) +/* + * Compute HMAC of variable-length data with constant flow. + */ +int mbedtls_ssl_cf_hmac( + mbedtls_md_context_t *ctx, + const unsigned char *add_data, size_t add_data_len, + const unsigned char *data, size_t data_len_secret, + size_t min_data_len, size_t max_data_len, + unsigned char *output ) +{ + /* WORK IN PROGRESS - THIS IS NOT CONSTANT FLOW AT ALL */ + (void) min_data_len; + (void) max_data_len; + mbedtls_md_hmac_update( ctx, add_data, add_data_len ); + mbedtls_md_hmac_update( ctx, data, data_len_secret ); + mbedtls_md_hmac_finish( ctx, output ); + mbedtls_md_hmac_reset( ctx ); + + return( 0 ); +} +#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC && TLS 1.0-1.2 */ + static int ssl_decrypt_buf( mbedtls_ssl_context *ssl ) { mbedtls_cipher_mode_t mode; diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data index 147350744..db92a72bc 100644 --- a/tests/suites/test_suite_ssl.data +++ b/tests/suites/test_suite_ssl.data @@ -57,3 +57,19 @@ ssl_dtls_replay:"abcd12340000abcd12340100":"abcd123400ff":0 SSL SET_HOSTNAME memory leak: call ssl_set_hostname twice ssl_set_hostname_twice:"server0":"server1" + +Constant-flow HMAC: MD5 +depends_on:MBEDTLS_MD5_C +ssl_cf_hmac:MBEDTLS_MD_MD5 + +Constant-flow HMAC: SHA1 +depends_on:MBEDTLS_SHA1_C +ssl_cf_hmac:MBEDTLS_MD_SHA1 + +Constant-flow HMAC: SHA256 +depends_on:MBEDTLS_SHA256_C +ssl_cf_hmac:MBEDTLS_MD_SHA256 + +Constant-flow HMAC: SHA384 +depends_on:MBEDTLS_SHA512_C:!MBEDTLS_SHA512_NO_SHA384 +ssl_cf_hmac:MBEDTLS_MD_SHA384 diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function index 326f22d3b..fc953a125 100644 --- a/tests/suites/test_suite_ssl.function +++ b/tests/suites/test_suite_ssl.function @@ -52,3 +52,96 @@ void ssl_set_hostname_twice( char *hostname0, char *hostname1 ) mbedtls_ssl_free( &ssl ); } /* END_CASE */ + +/* BEGIN_CASE depends_on:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_AES_C:MBEDTLS_SSL_PROTO_TLS1_2 */ +void ssl_cf_hmac( int hash ) +{ + /* + * Test the function mbedtls_ssl_cf_hmac() against a reference + * implementation. + * + * Note: the dependency is actually on TLS 1.0-1.2 and (AES or ARIA or + * Camellia or DES), but since the test framework doesn't support + * alternation in dependencies, just depend on the most common. + */ + mbedtls_md_context_t ctx, ref_ctx; + const mbedtls_md_info_t *md_info; + size_t out_len, block_size; + size_t min_in_len, in_len, max_in_len, i; + /* TLS additional data is 13 bytes (hence the "lucky 13" name) */ + unsigned char add_data[13]; + unsigned char ref_out[MBEDTLS_MD_MAX_SIZE]; + unsigned char *data = NULL; + unsigned char *out = NULL; + unsigned char rec_num = 0; + + mbedtls_md_init( &ctx ); + mbedtls_md_init( &ref_ctx ); + + md_info = mbedtls_md_info_from_type( hash ); + TEST_ASSERT( md_info != NULL ); + out_len = mbedtls_md_get_size( md_info ); + TEST_ASSERT( out_len != 0 ); + block_size = hash == MBEDTLS_MD_SHA384 ? 128 : 64; + + /* Use allocated out buffer to catch overwrites */ + out = mbedtls_calloc( 1, out_len ); + TEST_ASSERT( out != NULL ); + + /* Set up contexts with the given hash and a dummy key */ + TEST_ASSERT( 0 == mbedtls_md_setup( &ctx, md_info, 1 ) ); + TEST_ASSERT( 0 == mbedtls_md_setup( &ref_ctx, md_info, 1 ) ); + memset( ref_out, 42, sizeof( ref_out ) ); + TEST_ASSERT( 0 == mbedtls_md_hmac_starts( &ctx, ref_out, out_len ) ); + TEST_ASSERT( 0 == mbedtls_md_hmac_starts( &ref_ctx, ref_out, out_len ) ); + memset( ref_out, 0, sizeof( ref_out ) ); + + /* + * Test all possible lengths up to a point. The difference between + * max_in_len and min_in_len is at most 255, and make sure they both vary + * by at least one block size. + */ + for( max_in_len = 0; max_in_len <= 255 + block_size; max_in_len++ ) + { + /* Use allocated in buffer to catch overreads */ + data = mbedtls_calloc( 1, max_in_len ); + TEST_ASSERT( data != NULL || max_in_len == 0 ); + + min_in_len = max_in_len > 255 ? max_in_len - 255 : 0; + for( in_len = min_in_len; in_len <= max_in_len; in_len++ ) + { + /* Set up dummy data and add_data */ + rec_num++; + memset( add_data, rec_num, sizeof( add_data ) ); + for( i = 0; i < in_len; i++ ) + data[i] = ( i & 0xff ) ^ rec_num; + + /* Get the function's result */ + TEST_ASSERT( 0 == mbedtls_ssl_cf_hmac( &ctx, add_data, sizeof( add_data ), + data, in_len, + min_in_len, max_in_len, + out ) ); + + /* Compute the reference result */ + TEST_ASSERT( 0 == mbedtls_md_hmac_update( &ref_ctx, add_data, + sizeof( add_data ) ) ); + TEST_ASSERT( 0 == mbedtls_md_hmac_update( &ref_ctx, data, in_len ) ); + TEST_ASSERT( 0 == mbedtls_md_hmac_finish( &ref_ctx, ref_out ) ); + TEST_ASSERT( 0 == mbedtls_md_hmac_reset( &ref_ctx ) ); + + /* Compare */ + TEST_ASSERT( 0 == memcmp( out, ref_out, out_len ) ); + } + + mbedtls_free( data ); + data = NULL; + } + +exit: + mbedtls_md_free( &ref_ctx ); + mbedtls_md_free( &ctx ); + + mbedtls_free( data ); + mbedtls_free( out ); +} +/* END_CASE */