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Split parts of ssl_parse_client_key_exchange() into separate functions

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Made ssl_parse_client_dh_public(), ssl_parse_cient_ecdh_public() and
ssl_parse_encrypted_pms_secret() in preparation for PSK-related code
This commit is contained in:
Paul Bakker 2013-04-17 17:19:09 +02:00
parent d4a56ec6bf
commit 70df2fbaa5
1 changed files with 167 additions and 126 deletions
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293
library/ssl_srv.c
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@ -1382,14 +1382,166 @@ static int ssl_write_server_hello_done( ssl_context *ssl )
return( 0 );
}
static int ssl_parse_client_dh_public( ssl_context *ssl )
{
int ret = POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE;
#if defined(POLARSSL_DHM_C)
size_t n;
/*
* Receive G^Y mod P, premaster = (G^Y)^X mod P
*/
n = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
if( n < 1 || n > ssl->handshake->dhm_ctx.len ||
n + 6 != ssl->in_hslen )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
if( ( ret = dhm_read_public( &ssl->handshake->dhm_ctx,
ssl->in_msg + 6, n ) ) != 0 )
{
SSL_DEBUG_RET( 1, "dhm_read_public", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP );
}
SSL_DEBUG_MPI( 3, "DHM: GY", &ssl->handshake->dhm_ctx.GY );
ssl->handshake->pmslen = ssl->handshake->dhm_ctx.len;
if( ( ret = dhm_calc_secret( &ssl->handshake->dhm_ctx,
ssl->handshake->premaster,
&ssl->handshake->pmslen ) ) != 0 )
{
SSL_DEBUG_RET( 1, "dhm_calc_secret", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_CS );
}
SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K );
#endif /* POLARSSL_DHM_C */
return( ret );
}
static int ssl_parse_client_ecdh_public( ssl_context *ssl )
{
int ret = POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE;
#if defined(POLARSSL_ECDH_C)
size_t n;
/*
* Receive client public key and calculate premaster
*/
n = ssl->in_msg[3];
if( n < 1 || n > mpi_size( &ssl->handshake->ecdh_ctx.grp.P ) * 2 + 2 ||
n + 4 != ssl->in_hslen )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
if( ( ret = ecdh_read_public( &ssl->handshake->ecdh_ctx,
ssl->in_msg + 4, n ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ecdh_read_public", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP );
}
SSL_DEBUG_ECP( 3, "ECDH: Qp ", &ssl->handshake->ecdh_ctx.Qp );
if( ( ret = ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
&ssl->handshake->pmslen,
ssl->handshake->premaster,
POLARSSL_MPI_MAX_SIZE ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ecdh_calc_secret", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_CS );
}
SSL_DEBUG_MPI( 3, "ECDH: z ", &ssl->handshake->ecdh_ctx.z );
#endif /* POLARSSL_ECDH_C */
return( ret );
}
static int ssl_parse_encrypted_pms_secret( ssl_context *ssl )
{
int ret = POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE;
size_t i, n = 0;
if( ssl->rsa_key == NULL )
{
SSL_DEBUG_MSG( 1, ( "got no private key" ) );
return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
}
/*
* Decrypt the premaster using own private RSA key
*/
i = 4;
if( ssl->rsa_key )
n = ssl->rsa_key_len( ssl->rsa_key );
ssl->handshake->pmslen = 48;
if( ssl->minor_ver != SSL_MINOR_VERSION_0 )
{
i += 2;
if( ssl->in_msg[4] != ( ( n >> 8 ) & 0xFF ) ||
ssl->in_msg[5] != ( ( n ) & 0xFF ) )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
}
if( ssl->in_hslen != i + n )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
if( ssl->rsa_key ) {
ret = ssl->rsa_decrypt( ssl->rsa_key, RSA_PRIVATE,
&ssl->handshake->pmslen,
ssl->in_msg + i,
ssl->handshake->premaster,
sizeof(ssl->handshake->premaster) );
}
if( ret != 0 || ssl->handshake->pmslen != 48 ||
ssl->handshake->premaster[0] != ssl->max_major_ver ||
ssl->handshake->premaster[1] != ssl->max_minor_ver )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
/*
* Protection against Bleichenbacher's attack:
* invalid PKCS#1 v1.5 padding must not cause
* the connection to end immediately; instead,
* send a bad_record_mac later in the handshake.
*/
ssl->handshake->pmslen = 48;
ret = ssl->f_rng( ssl->p_rng, ssl->handshake->premaster,
ssl->handshake->pmslen );
if( ret != 0 )
return( ret );
}
return( ret );
}
static int ssl_parse_client_key_exchange( ssl_context *ssl )
{
int ret;
size_t i, n = 0;
#if defined(POLARSSL_DHM_C) || defined(POLARSSL_ECDH_C)
const ssl_ciphersuite_t *ciphersuite_info;
ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
#endif
SSL_DEBUG_MSG( 2, ( "=> parse client key exchange" ) );
@ -1411,139 +1563,28 @@ static int ssl_parse_client_key_exchange( ssl_context *ssl )
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
#if defined(POLARSSL_DHM_C)
if( ciphersuite_info->key_exchange == POLARSSL_KEY_EXCHANGE_DHE_RSA )
{
/*
* Receive G^Y mod P, premaster = (G^Y)^X mod P
*/
n = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
if( n < 1 || n > ssl->handshake->dhm_ctx.len ||
n + 6 != ssl->in_hslen )
if( ( ret = ssl_parse_client_dh_public( ssl ) ) != 0 )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
SSL_DEBUG_RET( 1, ( "ssl_parse_client_dh_public" ), ret );
return( ret );
}
if( ( ret = dhm_read_public( &ssl->handshake->dhm_ctx,
ssl->in_msg + 6, n ) ) != 0 )
}
else if( ciphersuite_info->key_exchange == POLARSSL_KEY_EXCHANGE_ECDHE_RSA )
{
if( ( ret = ssl_parse_client_ecdh_public( ssl ) ) != 0 )
{
SSL_DEBUG_RET( 1, "dhm_read_public", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP );
SSL_DEBUG_RET( 1, ( "ssl_parse_client_ecdh_public" ), ret );
return( ret );
}
SSL_DEBUG_MPI( 3, "DHM: GY", &ssl->handshake->dhm_ctx.GY );
ssl->handshake->pmslen = ssl->handshake->dhm_ctx.len;
if( ( ret = dhm_calc_secret( &ssl->handshake->dhm_ctx,
ssl->handshake->premaster,
&ssl->handshake->pmslen ) ) != 0 )
{
SSL_DEBUG_RET( 1, "dhm_calc_secret", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_CS );
}
SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K );
}
else
#endif
#if defined(POLARSSL_ECDH_C)
if( ciphersuite_info->key_exchange == POLARSSL_KEY_EXCHANGE_ECDHE_RSA )
{
/*
* Receive client public key and calculate premaster
*/
n = ssl->in_msg[3];
if( n < 1 || n > mpi_size( &ssl->handshake->ecdh_ctx.grp.P ) * 2 + 2 ||
n + 4 != ssl->in_hslen )
if( ( ret = ssl_parse_encrypted_pms_secret( ssl ) ) != 0 )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
if( ( ret = ecdh_read_public( &ssl->handshake->ecdh_ctx,
ssl->in_msg + 4, n ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ecdh_read_public", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP );
}
SSL_DEBUG_ECP( 3, "ECDH: Qp ", &ssl->handshake->ecdh_ctx.Qp );
if( ( ret = ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
&ssl->handshake->pmslen,
ssl->handshake->premaster,
POLARSSL_MPI_MAX_SIZE ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ecdh_calc_secret", ret );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_CS );
}
SSL_DEBUG_MPI( 3, "ECDH: z ", &ssl->handshake->ecdh_ctx.z );
}
else
#endif
{
if( ssl->rsa_key == NULL )
{
SSL_DEBUG_MSG( 1, ( "got no private key" ) );
return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
}
/*
* Decrypt the premaster using own private RSA key
*/
i = 4;
if( ssl->rsa_key )
n = ssl->rsa_key_len( ssl->rsa_key );
ssl->handshake->pmslen = 48;
if( ssl->minor_ver != SSL_MINOR_VERSION_0 )
{
i += 2;
if( ssl->in_msg[4] != ( ( n >> 8 ) & 0xFF ) ||
ssl->in_msg[5] != ( ( n ) & 0xFF ) )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
}
if( ssl->in_hslen != i + n )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
if( ssl->rsa_key ) {
ret = ssl->rsa_decrypt( ssl->rsa_key, RSA_PRIVATE,
&ssl->handshake->pmslen,
ssl->in_msg + i,
ssl->handshake->premaster,
sizeof(ssl->handshake->premaster) );
}
if( ret != 0 || ssl->handshake->pmslen != 48 ||
ssl->handshake->premaster[0] != ssl->max_major_ver ||
ssl->handshake->premaster[1] != ssl->max_minor_ver )
{
SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
/*
* Protection against Bleichenbacher's attack:
* invalid PKCS#1 v1.5 padding must not cause
* the connection to end immediately; instead,
* send a bad_record_mac later in the handshake.
*/
ssl->handshake->pmslen = 48;
ret = ssl->f_rng( ssl->p_rng, ssl->handshake->premaster,
ssl->handshake->pmslen );
if( ret != 0 )
return( ret );
SSL_DEBUG_RET( 1, ( "ssl_parse_client_ecdh_public" ), ret );
return( ret );
}
}