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Allow passing any X.509 CRT chain to ssl_parse_certificate_chain()

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This commit modifies the helper `ssl_parse_certificate_chain()` to
accep any target X.509 CRT chain instead of hardcoding it to
`session_negotiate->peer_cert`. This increases modularity and paves
the way towards removing `mbedtls_ssl_session::peer_cert`.
This commit is contained in:
Hanno Becker 2019-02-05 15:37:23 +00:00
parent 6863619a2f
commit c7bd780e02
1 changed files with 41 additions and 47 deletions
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88
library/ssl_tls.c
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@ -5740,9 +5740,13 @@ static void ssl_clear_peer_cert( mbedtls_ssl_session *session )
* Once the certificate message is read, parse it into a cert chain and
* perform basic checks, but leave actual verification to the caller
*/
static int ssl_parse_certificate_chain( mbedtls_ssl_context *ssl )
static int ssl_parse_certificate_chain( mbedtls_ssl_context *ssl,
mbedtls_x509_crt *chain )
{
int ret, crt_cnt=0;
int ret;
#if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
int crt_cnt=0;
#endif
size_t i, n;
uint8_t alert;
@ -5819,58 +5823,34 @@ static int ssl_parse_certificate_chain( mbedtls_ssl_context *ssl )
}
/* Check if we're handling the first CRT in the chain. */
if( crt_cnt++ == 0 )
#if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
if( crt_cnt++ == 0 &&
ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
{
/* During client-side renegotiation, check that the server's
* end-CRTs hasn't changed compared to the initial handshake,
* mitigating the triple handshake attack. On success, reuse
* the original end-CRT instead of parsing it again. */
#if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Check that peer CRT hasn't changed during renegotiation" ) );
if( ssl_check_peer_crt_unchanged( ssl,
&ssl->in_msg[i],
n ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Check that peer CRT hasn't changed during renegotiation" ) );
if( ssl_check_peer_crt_unchanged( ssl,
&ssl->in_msg[i],
n ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "new server cert during renegotiation" ) );
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED );
return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
}
/* Now we can safely free the original chain. */
ssl_clear_peer_cert( ssl->session );
/* Intentional fallthrough. */
MBEDTLS_SSL_DEBUG_MSG( 1, ( "new server cert during renegotiation" ) );
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED );
return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
}
/* Now we can safely free the original chain. */
ssl_clear_peer_cert( ssl->session );
}
#endif /* MBEDTLS_SSL_RENEGOTIATION && MBEDTLS_SSL_CLI_C */
/* Outside of client-side renegotiation, create a fresh X.509 CRT
* instance to parse the end-CRT into. */
ssl->session_negotiate->peer_cert =
mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
if( ssl->session_negotiate->peer_cert == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
sizeof( mbedtls_x509_crt ) ) );
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
}
mbedtls_x509_crt_init( ssl->session_negotiate->peer_cert );
/* Intentional fall through */
}
/* Parse the next certificate in the chain. */
ret = mbedtls_x509_crt_parse_der( ssl->session_negotiate->peer_cert,
ssl->in_msg + i, n );
ret = mbedtls_x509_crt_parse_der( chain, ssl->in_msg + i, n );
switch( ret )
{
case 0: /*ok*/
@ -5898,7 +5878,7 @@ static int ssl_parse_certificate_chain( mbedtls_ssl_context *ssl )
i += n;
}
MBEDTLS_SSL_DEBUG_CRT( 3, "peer certificate", ssl->session_negotiate->peer_cert );
MBEDTLS_SSL_DEBUG_CRT( 3, "peer certificate", chain );
return( 0 );
}
@ -6179,10 +6159,24 @@ int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
}
#endif /* MBEDTLS_SSL_SRV_C */
/* In case we tried to reuse a session but it failed. */
/* Clear existing peer CRT structure in case we tried to
* reuse a session but it failed, and allocate a new one. */
ssl_clear_peer_cert( ssl->session_negotiate );
ssl->session_negotiate->peer_cert =
mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
if( ssl->session_negotiate->peer_cert == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
sizeof( mbedtls_x509_crt ) ) );
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
}
mbedtls_x509_crt_init( ssl->session_negotiate->peer_cert );
if( ( ret = ssl_parse_certificate_chain( ssl ) ) != 0 )
ret = ssl_parse_certificate_chain( ssl, ssl->session_negotiate->peer_cert );
if( ret != 0 )
return( ret );
#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)