Add psk_key_exchange_modes parser

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu 2022-07-08 12:04:51 +00:00
parent 6dc7cdfdd1
commit e19e3b9eb8
2 changed files with 73 additions and 0 deletions

View file

@ -169,6 +169,15 @@
/** Invalid value in SSL config */
#define MBEDTLS_ERR_SSL_BAD_CONFIG -0x5E80
/*
* Constants from RFC 8446 for TLS 1.3 PSK modes
*
* Those are used in the Pre-Shared Key Exchange Modes extension.
* See Section 4.2.9 in RFC 8446.
*/
#define MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE 0 /* Pure PSK-based exchange */
#define MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE 1 /* PSK+ECDHE-based exchange */
/*
* TLS 1.3 NamedGroup values
*

View file

@ -45,6 +45,53 @@
#include "ssl_tls13_keys.h"
#include "ssl_debug_helpers.h"
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
/* From RFC 8446:
*
* enum { psk_ke(0), psk_dhe_ke(1), (255) } PskKeyExchangeMode;
* struct {
* PskKeyExchangeMode ke_modes<1..255>;
* } PskKeyExchangeModes;
*/
static int ssl_tls13_parse_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
size_t ke_modes_len;
int ke_modes = 0;
/* Read PSK mode list length (1 Byte) */
MBEDTLS_SSL_CHK_BUF_READ_PTR( buf, end, 1 );
ke_modes_len = *buf++;
/* Currently, there are only two PSK modes, so even without looking
* at the content, something's wrong if the list has more than 2 items. */
if( ke_modes_len > 2 )
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
MBEDTLS_SSL_CHK_BUF_READ_PTR( buf, end, ke_modes_len );
while( ke_modes_len-- != 0 )
{
switch( *buf++ )
{
case MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE:
ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Found PSK KEX MODE" ) );
break;
case MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE:
ke_modes |= MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Found PSK_EPHEMERAL KEX MODE" ) );
break;
default:
return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
}
}
ssl->handshake->tls13_kex_modes = ke_modes;
return( 0 );
}
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
/* From RFC 8446:
* struct {
* ProtocolVersion versions<2..254>;
@ -754,6 +801,23 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_SUPPORTED_VERSIONS;
break;
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found psk key exchange modes extension" ) );
ret = ssl_tls13_parse_key_exchange_modes_ext(
ssl, p, extension_data_end );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET(
1, "ssl_tls13_parse_key_exchange_modes_ext", ret );
return( ret );
}
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES;
break;
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
#if defined(MBEDTLS_SSL_ALPN)
case MBEDTLS_TLS_EXT_ALPN:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found alpn extension" ) );