Protect setting of premaster_generated flag
The flag is used for tracking if the premaster has
been succesfully generated. Note that when resuming
a session, the flag should not be used when trying to
notice if all the key generation/derivation has been done.
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 6b95cfa..08c65d2 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2342,8 +2342,9 @@
unsigned char* out,
unsigned add_length_tag )
{
- int ret;
+ volatile int ret;
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_UNSET;
/*
* Generate (part of) the pre-master secret as
* struct {
@@ -2364,14 +2365,21 @@
mbedtls_ssl_conf_get_max_minor_ver( ssl->conf ),
ssl->conf->transport, out );
- if( ( ret = mbedtls_ssl_conf_get_frng( ssl->conf )
- ( mbedtls_ssl_conf_get_prng( ssl->conf ), out + 2, 46 ) ) != 0 )
+ ret = mbedtls_ssl_conf_get_frng( ssl->conf )
+ ( mbedtls_ssl_conf_get_prng( ssl->conf ), out + 2, 46 );
+
+ if( ret == 0 )
{
- MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret );
- return( ret );
+ mbedtls_platform_enforce_volatile_reads();
+ if( ret == 0 )
+ {
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+ return( 0 );
+ }
}
- return( 0 );
+ MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret );
+ return( ret );
}
/*
@@ -2383,11 +2391,12 @@
unsigned char *out, size_t buflen,
size_t *olen )
{
- int ret;
+ volatile int ret;
size_t len_bytes = mbedtls_ssl_get_minor_ver( ssl ) ==
MBEDTLS_SSL_MINOR_VERSION_0 ? 0 : 2;
mbedtls_pk_context *peer_pk = NULL;
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_UNSET;
if( buflen < len_bytes )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small for encrypted pms" ) );
@@ -2427,16 +2436,27 @@
goto cleanup;
}
- if( ( ret = mbedtls_pk_encrypt( peer_pk,
+ ret = mbedtls_pk_encrypt( peer_pk,
ppms, 48, out + len_bytes,
olen, buflen - len_bytes,
mbedtls_ssl_conf_get_frng( ssl->conf ),
- mbedtls_ssl_conf_get_prng( ssl->conf ) ) ) != 0 )
+ mbedtls_ssl_conf_get_prng( ssl->conf ) );
+
+ if( ret == 0 )
+ {
+ mbedtls_platform_enforce_volatile_reads();
+ if( ret == 0 )
+ {
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+ }
+ }
+ else
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_rsa_pkcs1_encrypt", ret );
goto cleanup;
}
+
#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( len_bytes == 2 )
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index e349ed8..3053818 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -3978,7 +3978,9 @@
unsigned char mask;
size_t i, peer_pmslen;
unsigned int diff;
+ volatile unsigned int pmscounter = 0;
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_UNSET;
/* In case of a failure in decryption, the decryption may write less than
* 2 bytes of output, but we always read the first two bytes. It doesn't
* matter in the end because diff will be nonzero in that case due to
@@ -4056,7 +4058,19 @@
/* Set pms to either the true or the fake PMS, without
* data-dependent branches. */
for( i = 0; i < ssl->handshake->pmslen; i++ )
+ {
pms[i] = ( mask & fake_pms[i] ) | ( (~mask) & peer_pms[i] );
+ pmscounter++;
+ }
+
+ if( pmscounter == ssl->handshake->pmslen )
+ {
+ mbedtls_platform_enforce_volatile_reads();
+ if( pmscounter == ssl->handshake->pmslen )
+ {
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+ }
+ }
return( 0 );
}
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index d7ad696..66772f4 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1881,7 +1881,7 @@
int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
{
- int ret;
+ volatile int ret;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> derive keys" ) );
@@ -1958,11 +1958,11 @@
int mbedtls_ssl_build_pms( mbedtls_ssl_context *ssl )
{
- int ret;
+ volatile int ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
mbedtls_ssl_ciphersuite_handle_t ciphersuite_info =
mbedtls_ssl_handshake_get_ciphersuite( ssl->handshake );
-
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_UNSET;
#if defined(MBEDTLS_USE_TINYCRYPT)
if( mbedtls_ssl_suite_get_key_exchange( ciphersuite_info )
== MBEDTLS_KEY_EXCHANGE_ECDHE_RSA ||
@@ -1980,6 +1980,7 @@
return( MBEDTLS_ERR_PLATFORM_FAULT_DETECTED );
if( ret != UECC_SUCCESS )
return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
ssl->handshake->pmslen = NUM_ECC_BYTES;
}
@@ -1989,12 +1990,26 @@
if( mbedtls_ssl_suite_get_key_exchange( ciphersuite_info )
== MBEDTLS_KEY_EXCHANGE_DHE_RSA )
{
- if( ( ret = mbedtls_dhm_calc_secret( &ssl->handshake->dhm_ctx,
+ ret = mbedtls_dhm_calc_secret( &ssl->handshake->dhm_ctx,
ssl->handshake->premaster,
MBEDTLS_PREMASTER_SIZE,
&ssl->handshake->pmslen,
mbedtls_ssl_conf_get_frng( ssl->conf ),
- mbedtls_ssl_conf_get_prng( ssl->conf ) ) ) != 0 )
+ mbedtls_ssl_conf_get_prng( ssl->conf ) );
+ if( ret == 0 )
+ {
+ mbedtls_platform_enforce_volatile_reads();
+ if( ret == 0 )
+ {
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_calc_secret", ret );
+ return( ret );
+ }
+ }
+ else
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_calc_secret", ret );
return( ret );
@@ -2018,12 +2033,26 @@
mbedtls_ssl_suite_get_key_exchange( ciphersuite_info )
== MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA )
{
- if( ( ret = mbedtls_ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
+ ret = mbedtls_ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
&ssl->handshake->pmslen,
ssl->handshake->premaster,
MBEDTLS_MPI_MAX_SIZE,
mbedtls_ssl_conf_get_frng( ssl->conf ),
- mbedtls_ssl_conf_get_prng( ssl->conf ) ) ) != 0 )
+ mbedtls_ssl_conf_get_prng( ssl->conf ) );
+ if( ret == 0 )
+ {
+ mbedtls_platform_enforce_volatile_reads();
+ if( ret == 0 )
+ {
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
+ return( ret );
+ }
+ }
+ else
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
return( ret );
@@ -2039,8 +2068,22 @@
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
if( mbedtls_ssl_ciphersuite_uses_psk( ciphersuite_info ) )
{
- if( ( ret = mbedtls_ssl_psk_derive_premaster( ssl,
- mbedtls_ssl_suite_get_key_exchange( ciphersuite_info ) ) ) != 0 )
+ ret = mbedtls_ssl_psk_derive_premaster( ssl,
+ mbedtls_ssl_suite_get_key_exchange( ciphersuite_info ) );
+ if( ret == 0 )
+ {
+ mbedtls_platform_enforce_volatile_reads();
+ if( ret == 0 )
+ {
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_psk_derive_premaster", ret );
+ return( ret );
+ }
+ }
+ else
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_psk_derive_premaster", ret );
return( ret );
@@ -2056,7 +2099,20 @@
ssl->handshake->premaster, 32, &ssl->handshake->pmslen,
mbedtls_ssl_conf_get_frng( ssl->conf ),
mbedtls_ssl_conf_get_prng( ssl->conf ) );
- if( ret != 0 )
+ if( ret == 0 )
+ {
+ mbedtls_platform_enforce_volatile_reads();
+ if( ret == 0 )
+ {
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecjpake_derive_secret", ret );
+ return( ret );
+ }
+ }
+ else
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecjpake_derive_secret", ret );
return( ret );
@@ -2091,6 +2147,7 @@
unsigned char *end = p + sizeof( ssl->handshake->premaster );
const unsigned char *psk = ssl->conf->psk;
size_t psk_len = ssl->conf->psk_len;
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_UNSET;
/* If the psk callback was called, use its result */
if( ssl->handshake->psk != NULL )
@@ -2214,6 +2271,8 @@
ssl->handshake->pmslen = p - ssl->handshake->premaster;
+ ssl->handshake->premaster_generated = MBEDTLS_SSL_FI_FLAG_SET;
+
return( 0 );
}
#endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */