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Add I/O buffer resizing in handshake init and free

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Add a conditional buffer resizing feature. Introduce tests exercising
it in various setups (serialization, renegotiation, mfl manipulations).
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
This commit is contained in:
Andrzej Kurek 2020-03-03 10:39:58 -05:00
parent aad82f9bbb
commit 0afa2a1b65
No known key found for this signature in database
GPG key ID: 89A90840DC388527
4 changed files with 309 additions and 0 deletions
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116
library/ssl_tls.c
View file

@ -245,6 +245,29 @@ int mbedtls_ssl_session_copy( mbedtls_ssl_session *dst,
return( 0 );
}
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
static int resize_buffer( unsigned char **buffer, size_t len_new, size_t *len_old )
{
unsigned char* resized_buffer = mbedtls_calloc( 1, len_new );
if( resized_buffer == NULL )
return -1;
/* We want to copy len_new bytes when downsizing the buffer, and
* len_old bytes when upsizing, so we choose the smaller of two sizes,
* to fit one buffer into another. Size checks, ensuring that no data is
* lost, are done outside of this function. */
memcpy( resized_buffer, *buffer,
( len_new < *len_old ) ? len_new : *len_old );
mbedtls_platform_zeroize( *buffer, *len_old );
mbedtls_free( *buffer );
*buffer = resized_buffer;
*len_old = len_new;
return 0;
}
#endif /* MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH */
/*
* Key material generation
*/
@ -3643,6 +3666,43 @@ static int ssl_handshake_init( mbedtls_ssl_context *ssl )
{
ssl->handshake = mbedtls_calloc( 1, sizeof(mbedtls_ssl_handshake_params) );
}
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
/* If the buffers are too small - reallocate */
{
int modified = 0;
if( ssl->in_buf_len < MBEDTLS_SSL_IN_BUFFER_LEN )
{
if( resize_buffer( &ssl->in_buf, MBEDTLS_SSL_IN_BUFFER_LEN,
&ssl->in_buf_len ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", MBEDTLS_SSL_IN_BUFFER_LEN ) );
modified = 1;
}
}
if( ssl->out_buf_len < MBEDTLS_SSL_OUT_BUFFER_LEN )
{
if( resize_buffer( &ssl->out_buf, MBEDTLS_SSL_OUT_BUFFER_LEN,
&ssl->out_buf_len ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", MBEDTLS_SSL_OUT_BUFFER_LEN ) );
modified = 1;
}
}
if( modified )
{
/* Update pointers here to avoid doing it twice. */
mbedtls_ssl_reset_in_out_pointers( ssl );
}
}
#endif
/* All pointers should exist and can be directly freed without issue */
if( ssl->handshake == NULL ||
@ -5818,6 +5878,60 @@ void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
mbedtls_platform_zeroize( handshake,
sizeof( mbedtls_ssl_handshake_params ) );
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
/* If the buffers are too big - reallocate. Because of the way Mbed TLS
* processes datagrams and the fact that a datagram is allowed to have
* several records in it, it is possible that the I/O buffers are not
* empty at this stage */
{
int modified = 0;
uint32_t buf_len = mbedtls_ssl_get_input_buflen( ssl );
size_t written_in = 0;
size_t written_out = 0;
if( ssl->in_buf != NULL &&
ssl->in_buf_len > buf_len &&
ssl->in_left < buf_len )
{
written_in = ssl->in_msg - ssl->in_buf;
if( resize_buffer( &ssl->in_buf, buf_len, &ssl->in_buf_len ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", buf_len ) );
modified = 1;
}
}
buf_len = mbedtls_ssl_get_output_buflen( ssl );
if( ssl->out_buf != NULL &&
ssl->out_buf_len > mbedtls_ssl_get_output_buflen( ssl ) &&
ssl->out_left < buf_len )
{
written_out = ssl->out_msg - ssl->out_buf;
if( resize_buffer( &ssl->out_buf, buf_len, &ssl->out_buf_len ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", buf_len ) );
modified = 1;
}
}
if( modified )
{
/* Update pointers here to avoid doing it twice. */
mbedtls_ssl_reset_in_out_pointers( ssl );
/* Fields below might not be properly updated with record
* splitting, so they are manually updated here. */
ssl->out_msg = ssl->out_buf + written_out;
ssl->in_msg = ssl->in_buf + written_in;
}
}
#endif
}
void mbedtls_ssl_session_free( mbedtls_ssl_session *session )
@ -6499,12 +6613,14 @@ void mbedtls_ssl_free( mbedtls_ssl_context *ssl )
{
mbedtls_platform_zeroize( ssl->out_buf, out_buf_len );
mbedtls_free( ssl->out_buf );
ssl->out_buf = NULL;
}
if( ssl->in_buf != NULL )
{
mbedtls_platform_zeroize( ssl->in_buf, in_buf_len );
mbedtls_free( ssl->in_buf );
ssl->in_buf = NULL;
}
#if defined(MBEDTLS_ZLIB_SUPPORT)