From 85680c49efb0e75068afba761ad9c1737cba520a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= Date: Fri, 3 May 2019 09:16:16 +0200 Subject: [PATCH] Reduce indentation in ssl_compute_master() Exit earlier when there's noting to do. For a small diff, review with 'git show -w'. --- library/ssl_tls.c | 205 ++++++++++++++++++++++------------------------ 1 file changed, 97 insertions(+), 108 deletions(-) diff --git a/library/ssl_tls.c b/library/ssl_tls.c index 1b40f458f4..a78d6e570f 100644 --- a/library/ssl_tls.c +++ b/library/ssl_tls.c @@ -1578,7 +1578,7 @@ static int ssl_set_handshake_prfs( mbedtls_ssl_handshake_params *handshake, } /* - * Compute master secret + * Compute master secret if needed */ static int ssl_compute_master( mbedtls_ssl_context *ssl ) { @@ -1595,134 +1595,123 @@ static int ssl_compute_master( mbedtls_ssl_context *ssl ) unsigned char session_hash[48]; #endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */ - /* - * SSLv3: - * master = - * MD5( premaster + SHA1( 'A' + premaster + randbytes ) ) + - * MD5( premaster + SHA1( 'BB' + premaster + randbytes ) ) + - * MD5( premaster + SHA1( 'CCC' + premaster + randbytes ) ) - * - * TLSv1+: - * master = PRF( premaster, "master secret", randbytes )[0..47] - */ + /* The label for the KDF used for key expansion. + * This is either "master secret" or "extended master secret" + * depending on whether the Extended Master Secret extension + * is used. */ + char const *lbl = "master secret"; + + /* The salt for the KDF used for key expansion. + * - If the Extended Master Secret extension is not used, + * this is ClientHello.Random + ServerHello.Random + * (see Sect. 8.1 in RFC 5246). + * - If the Extended Master Secret extension is used, + * this is the transcript of the handshake so far. + * (see Sect. 4 in RFC 7627). */ + unsigned char const *salt = handshake->randbytes; + size_t salt_len = 64; + if( handshake->resume != 0 ) { MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) ); + return( 0 ); } - else - { - /* The label for the KDF used for key expansion. - * This is either "master secret" or "extended master secret" - * depending on whether the Extended Master Secret extension - * is used. */ - char const *lbl = "master secret"; - - /* The salt for the KDF used for key expansion. - * - If the Extended Master Secret extension is not used, - * this is ClientHello.Random + ServerHello.Random - * (see Sect. 8.1 in RFC 5246). - * - If the Extended Master Secret extension is used, - * this is the transcript of the handshake so far. - * (see Sect. 4 in RFC 7627). */ - unsigned char const *salt = handshake->randbytes; - size_t salt_len = 64; #if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET) - if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED ) - { - MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) ); + if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED ) + { + MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) ); - lbl = "extended master secret"; - salt = session_hash; - ssl->handshake->calc_verify( ssl, session_hash ); + lbl = "extended master secret"; + salt = session_hash; + ssl->handshake->calc_verify( ssl, session_hash ); #if defined(MBEDTLS_SSL_PROTO_TLS1_2) - if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 ) - { + if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 ) + { #if defined(MBEDTLS_SHA512_C) - if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 ) - { - salt_len = 48; - } - else -#endif /* MBEDTLS_SHA512_C */ - salt_len = 32; + if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 ) + { + salt_len = 48; } else -#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ - salt_len = 36; - - MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, salt_len ); +#endif /* MBEDTLS_SHA512_C */ + salt_len = 32; } + else +#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */ + salt_len = 36; + + MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, salt_len ); + } #endif /* MBEDTLS_SSL_EXTENDED_MS_ENABLED */ #if defined(MBEDTLS_USE_PSA_CRYPTO) && \ - defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED) - if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK && - ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 && - ssl_use_opaque_psk( ssl ) == 1 ) - { - /* Perform PSK-to-MS expansion in a single step. */ - psa_status_t status; - psa_algorithm_t alg; - psa_key_handle_t psk; - psa_key_derivation_operation_t derivation = - PSA_KEY_DERIVATION_OPERATION_INIT; +defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED) + if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK && + ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 && + ssl_use_opaque_psk( ssl ) == 1 ) + { + /* Perform PSK-to-MS expansion in a single step. */ + psa_status_t status; + psa_algorithm_t alg; + psa_key_handle_t psk; + psa_key_derivation_operation_t derivation = + PSA_KEY_DERIVATION_OPERATION_INIT; - MBEDTLS_SSL_DEBUG_MSG( 2, ( "perform PSA-based PSK-to-MS expansion" ) ); + MBEDTLS_SSL_DEBUG_MSG( 2, ( "perform PSA-based PSK-to-MS expansion" ) ); - psk = ssl->conf->psk_opaque; - if( ssl->handshake->psk_opaque != 0 ) - psk = ssl->handshake->psk_opaque; + psk = ssl->conf->psk_opaque; + if( ssl->handshake->psk_opaque != 0 ) + psk = ssl->handshake->psk_opaque; - if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 ) - alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_384); - else - alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256); - - status = psa_key_derivation( &derivation, psk, alg, - salt, salt_len, - (unsigned char const *) lbl, - (size_t) strlen( lbl ), - master_secret_len ); - if( status != PSA_SUCCESS ) - { - psa_key_derivation_abort( &derivation ); - return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED ); - } - - status = psa_key_derivation_output_bytes( &derivation, - session->master, - master_secret_len ); - if( status != PSA_SUCCESS ) - { - psa_key_derivation_abort( &derivation ); - return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED ); - } - - status = psa_key_derivation_abort( &derivation ); - if( status != PSA_SUCCESS ) - return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED ); - } + if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 ) + alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_384); else -#endif + alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256); + + status = psa_key_derivation( &derivation, psk, alg, + salt, salt_len, + (unsigned char const *) lbl, + (size_t) strlen( lbl ), + master_secret_len ); + if( status != PSA_SUCCESS ) { - ret = handshake->tls_prf( handshake->premaster, handshake->pmslen, - lbl, salt, salt_len, - session->master, - master_secret_len ); - if( ret != 0 ) - { - MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret ); - return( ret ); - } - - MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret", - handshake->premaster, - handshake->pmslen ); - - mbedtls_platform_zeroize( handshake->premaster, - sizeof(handshake->premaster) ); + psa_key_derivation_abort( &derivation ); + return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED ); } + + status = psa_key_derivation_output_bytes( &derivation, + session->master, + master_secret_len ); + if( status != PSA_SUCCESS ) + { + psa_key_derivation_abort( &derivation ); + return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED ); + } + + status = psa_key_derivation_abort( &derivation ); + if( status != PSA_SUCCESS ) + return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED ); + } + else +#endif + { + ret = handshake->tls_prf( handshake->premaster, handshake->pmslen, + lbl, salt, salt_len, + session->master, + master_secret_len ); + if( ret != 0 ) + { + MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret ); + return( ret ); + } + + MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret", + handshake->premaster, + handshake->pmslen ); + + mbedtls_platform_zeroize( handshake->premaster, + sizeof(handshake->premaster) ); } return( 0 );