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Account for future epoch records in the total buffering size

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Previous commits introduced the field `total_bytes_buffered`
which is supposed to keep track of the cumulative size of
all heap allocated buffers used for the purpose of reassembly
and/or buffering of future messages.

However, the buffering of future epoch records were not reflected
in this field so far. This commit changes this, adding the length
of a future epoch record to `total_bytes_buffered` when it's buffered,
and subtracting it when it's freed.
This commit is contained in:
Hanno Becker 2018-08-21 17:22:17 +01:00
parent a02b0b462d
commit 01315ea03a
1 changed files with 32 additions and 5 deletions
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33
library/ssl_tls.c
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@ -4438,12 +4438,22 @@ exit:
return( ret ); return( ret );
} }
static void ssl_free_buffered_record( mbedtls_ssl_context *ssl );
static int ssl_buffer_make_space( mbedtls_ssl_context *ssl, static int ssl_buffer_make_space( mbedtls_ssl_context *ssl,
size_t desired ) size_t desired )
{ {
int offset; int offset;
mbedtls_ssl_handshake_params * const hs = ssl->handshake; mbedtls_ssl_handshake_params * const hs = ssl->handshake;
/* Get rid of future records epoch first, if such exist. */
ssl_free_buffered_record( ssl );
/* Check if we have enough space available now. */
if( desired <= ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
hs->buffering.total_bytes_buffered ) )
{
return( 0 );
}
/* We don't have enough space to buffer the next expected /* We don't have enough space to buffer the next expected
* handshake message. Remove buffers used for future msgs * handshake message. Remove buffers used for future msgs
@ -4760,9 +4770,15 @@ static void ssl_free_buffered_record( mbedtls_ssl_context *ssl )
if( hs == NULL ) if( hs == NULL )
return; return;
if( hs->buffering.future_record.data != NULL )
{
hs->buffering.total_bytes_buffered -=
hs->buffering.future_record.len;
mbedtls_free( hs->buffering.future_record.data ); mbedtls_free( hs->buffering.future_record.data );
hs->buffering.future_record.data = NULL; hs->buffering.future_record.data = NULL;
} }
}
static int ssl_load_buffered_record( mbedtls_ssl_context *ssl ) static int ssl_load_buffered_record( mbedtls_ssl_context *ssl )
{ {
@ -4822,6 +4838,7 @@ static int ssl_buffer_future_record( mbedtls_ssl_context *ssl )
{ {
mbedtls_ssl_handshake_params * const hs = ssl->handshake; mbedtls_ssl_handshake_params * const hs = ssl->handshake;
size_t const rec_hdr_len = 13; size_t const rec_hdr_len = 13;
size_t const total_buf_sz = rec_hdr_len + ssl->in_msglen;
/* Don't buffer future records outside handshakes. */ /* Don't buffer future records outside handshakes. */
if( hs == NULL ) if( hs == NULL )
@ -4836,6 +4853,16 @@ static int ssl_buffer_future_record( mbedtls_ssl_context *ssl )
if( hs->buffering.future_record.data != NULL ) if( hs->buffering.future_record.data != NULL )
return( 0 ); return( 0 );
/* Don't buffer record if there's not enough buffering space remaining. */
if( total_buf_sz > ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
hs->buffering.total_bytes_buffered ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future epoch record of size %u would exceed the compile-time limit %u (already %u bytes buffered) -- ignore\n",
(unsigned) total_buf_sz, MBEDTLS_SSL_DTLS_MAX_BUFFERING,
(unsigned) hs->buffering.total_bytes_buffered ) );
return( 0 );
}
/* Buffer record */ /* Buffer record */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffer record from epoch %u", MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffer record from epoch %u",
ssl->in_epoch + 1 ) ); ssl->in_epoch + 1 ) );
@ -4845,7 +4872,7 @@ static int ssl_buffer_future_record( mbedtls_ssl_context *ssl )
/* ssl_parse_record_header() only considers records /* ssl_parse_record_header() only considers records
* of the next epoch as candidates for buffering. */ * of the next epoch as candidates for buffering. */
hs->buffering.future_record.epoch = ssl->in_epoch + 1; hs->buffering.future_record.epoch = ssl->in_epoch + 1;
hs->buffering.future_record.len = rec_hdr_len + ssl->in_msglen; hs->buffering.future_record.len = total_buf_sz;
hs->buffering.future_record.data = hs->buffering.future_record.data =
mbedtls_calloc( 1, hs->buffering.future_record.len ); mbedtls_calloc( 1, hs->buffering.future_record.len );
@ -4856,9 +4883,9 @@ static int ssl_buffer_future_record( mbedtls_ssl_context *ssl )
return( 0 ); return( 0 );
} }
memcpy( hs->buffering.future_record.data, memcpy( hs->buffering.future_record.data, ssl->in_hdr, total_buf_sz );
ssl->in_hdr, rec_hdr_len + ssl->in_msglen );
hs->buffering.total_bytes_buffered += total_buf_sz;
return( 0 ); return( 0 );
} }