Start extracting ssl_compute_master()

For now just moving code around, not changing indentation. Calling convention
and signature are going to be adjusted in upcoming commits.
This commit is contained in:
Manuel Pégourié-Gonnard 2019-04-30 12:08:59 +02:00 committed by Jarno Lamsa
parent 8d2805c784
commit 9951b712bd

View File

@ -1002,14 +1002,6 @@ static int ssl_populate_transform( mbedtls_ssl_context *ssl )
const mbedtls_cipher_info_t *cipher_info;
const mbedtls_md_info_t *md_info;
/* cf. RFC 5246, Section 8.1:
* "The master secret is always exactly 48 bytes in length." */
size_t const master_secret_len = 48;
#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
unsigned char session_hash[48];
#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
mbedtls_ssl_session *session = ssl->session_negotiate;
mbedtls_ssl_transform *transform = ssl->transform_negotiate;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
@ -1059,136 +1051,6 @@ static int ssl_populate_transform( mbedtls_ssl_context *ssl )
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
/*
* 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]
*/
if( handshake->resume != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
}
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" ) );
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 defined(MBEDTLS_SHA512_C)
if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
{
salt_len = 48;
}
else
#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;
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;
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 );
}
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) );
}
}
/*
* Swap the client and server random values.
*/
@ -1715,6 +1577,156 @@ static int ssl_set_handshake_prfs( mbedtls_ssl_handshake_params *handshake,
return( 0 );
}
/*
* Compute master secret
*/
static int ssl_compute_master( mbedtls_ssl_context *ssl )
{
int ret;
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
mbedtls_ssl_session *session = ssl->session_negotiate;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info = handshake->ciphersuite_info;
/* cf. RFC 5246, Section 8.1:
* "The master secret is always exactly 48 bytes in length." */
size_t const master_secret_len = 48;
#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
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]
*/
if( handshake->resume != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
}
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" ) );
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 defined(MBEDTLS_SHA512_C)
if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
{
salt_len = 48;
}
else
#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;
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;
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 );
}
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 );
}
int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
{
@ -1731,6 +1743,13 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
return( ret );
}
ret = ssl_compute_master( ssl );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_compute_master", ret );
return( ret );
}
return( ssl_populate_transform( ssl ) );
}