From d3eb0619a6858798e1220b42c43e0487002cb34d Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Mon, 8 Jan 2018 17:07:44 +0100
Subject: [PATCH] ssl_write_server_key_exchange refactor: minor cleanup
Clean up some debug messages and improve some comments.
---
library/ssl_srv.c | 44 ++++++++++++++++++++++++++++----------------
1 file changed, 28 insertions(+), 16 deletions(-)
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index da6069d84..415eaf8c9 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2837,25 +2837,26 @@ static int ssl_resume_server_key_exchange( mbedtls_ssl_context *ssl,
ssl->handshake->p_async_operation_ctx,
ssl->out_msg + ssl->out_msglen + 2,
signature_len, sig_max_len );
- MBEDTLS_SSL_DEBUG_RET( 3, "f_async_resume", ret );
if( ret != MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS )
{
ssl->handshake->p_async_operation_ctx = NULL;
}
+ MBEDTLS_SSL_DEBUG_RET( 2, "ssl_resume_server_key_exchange", ret );
return( ret );
}
#endif /* defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED) &&
defined(MBEDTLS_SSL_ASYNC_PRIVATE_C) */
+/* Prepare the ServerKeyExchange message, up to and including
+ calculating the signature if any, but excluding formatting the
+ signature and sending the message. */
static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
size_t *signature_len )
{
const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
ssl->transform_negotiate->ciphersuite_info;
-
unsigned char *p = ssl->out_msg + 4;
#if defined(MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED)
- size_t len;
#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
unsigned char *dig_signed = NULL;
#endif /* MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED */
@@ -2863,8 +2864,6 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
(void) ciphersuite_info; /* unused in some configurations */
(void) signature_len; /* unused in some configurations */
- MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );
-
/*
*
* Part 1: Provide key exchange parameters for chosen ciphersuite.
@@ -2879,6 +2878,7 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
{
int ret;
const unsigned char *end = ssl->out_msg + MBEDTLS_SSL_MAX_CONTENT_LEN;
+ size_t len;
ret = mbedtls_ecjpake_write_round_two( &ssl->handshake->ecjpake_ctx,
p, end - p, &len, ssl->conf->f_rng, ssl->conf->p_rng );
@@ -2915,6 +2915,7 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
if( mbedtls_ssl_ciphersuite_uses_dhe( ciphersuite_info ) )
{
int ret;
+ size_t len;
if( ssl->conf->dhm_P.p == NULL || ssl->conf->dhm_G.p == NULL )
{
@@ -2976,6 +2977,7 @@ static int ssl_prepare_server_key_exchange( mbedtls_ssl_context *ssl,
const mbedtls_ecp_curve_info **curve = NULL;
const mbedtls_ecp_group_id *gid;
int ret;
+ size_t len;
/* Match our preference list against the offered curves */
for( gid = ssl->conf->curve_list; *gid != MBEDTLS_ECP_DP_NONE; gid++ )
@@ -3211,7 +3213,6 @@ curve_matching_done:
case 0:
return( ssl_resume_server_key_exchange( ssl, signature_len ) );
case MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS:
- MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server key exchange (pending)" ) );
return( MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS );
default:
MBEDTLS_SSL_DEBUG_RET( 1, "f_async_sign", ret );
@@ -3242,17 +3243,24 @@ curve_matching_done:
return( 0 );
}
+/* Prepare the ServerKeyExchange message and send it. For ciphersuites
+ that do not include a ServerKeyExchange message, do nothing. Either
+ way, if successful, move on to the next step in the SSL state
+ machine */
static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
{
int ret;
size_t signature_len = 0;
-
- /* Extract static ECDH parameters and abort if ServerKeyExchange
- * is not needed. */
#if defined(MBEDTLS_KEY_EXCHANGE__SOME_NON_PFS__ENABLED)
const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
ssl->transform_negotiate->ciphersuite_info;
+#endif /* MBEDTLS_KEY_EXCHANGE__NON_PFS__ENABLED */
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );
+
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME_NON_PFS__ENABLED)
+ /* Extract static ECDH parameters and abort if ServerKeyExchange
+ * is not needed. */
if( mbedtls_ssl_ciphersuite_no_pfs( ciphersuite_info ) )
{
/* For suites involving ECDH, extract DH parameters
@@ -3272,16 +3280,14 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
}
#endif /* MBEDTLS_KEY_EXCHANGE__NON_PFS__ENABLED */
- /* If we have already prepared the message and there is an ongoing
- signature operation, resume signing. */
#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED) && \
defined(MBEDTLS_SSL_ASYNC_PRIVATE_C)
+ /* If we have already prepared the message and there is an ongoing
+ signature operation, resume signing. */
if( ssl->handshake->p_async_operation_ctx != NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "resuming signature operation" ) );
ret = ssl_resume_server_key_exchange( ssl, &signature_len );
- if( ret != 0 )
- return( ret );
}
else
#endif /* defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED) &&
@@ -3289,8 +3295,15 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
{
/* ServerKeyExchange is needed. Prepare the message. */
ret = ssl_prepare_server_key_exchange( ssl, &signature_len );
- if( ret != 0 )
- return( ret );
+ }
+
+ if( ret != 0 )
+ {
+ if( ret == MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS )
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server key exchange (pending)" ) );
+ else
+ ssl->out_msglen = 0;
+ return( ret );
}
/* If there is a signature, write its length.
@@ -3324,7 +3337,6 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write server key exchange" ) );
-
return( 0 );
}