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Refactor file descriptor checks into a common function

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This will make it easier to change the behavior uniformly.

No behavior change.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine
2021-06-20 23:08:19 +02:00
parent 56efc52d6b
commit 9065d786fd
1 changed files with 32 additions and 22 deletions
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54
library/net_sockets.c
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@@ -166,6 +166,26 @@ static int net_prepare( void )
return( 0 );
}
/*
* Return 0 if the file descriptor is valid, an error otherwise.
* If for_select != 0, check whether the file descriptor is within the range
* allowed for fd_set used for the FD_xxx macros and the select() function.
*/
static int check_fd( int fd, int for_select )
{
if( fd < 0 )
return( MBEDTLS_ERR_NET_INVALID_CONTEXT );
/* A limitation of select() is that it only works with file descriptors
* that are strictly less than FD_SETSIZE. This is a limitation of the
* fd_set type. Error out early, because attempting to call FD_SET on a
* large file descriptor is a buffer overflow on typical platforms. */
if( for_select && fd >= FD_SETSIZE )
return( MBEDTLS_ERR_NET_POLL_FAILED );
return( 0 );
}
/*
* Initialize a context
*/
@@ -497,15 +517,9 @@ int mbedtls_net_poll( mbedtls_net_context *ctx, uint32_t rw, uint32_t timeout )
int fd = ctx->fd;
if( fd < 0 )
return( MBEDTLS_ERR_NET_INVALID_CONTEXT );
/* A limitation of select() is that it only works with file descriptors
* that are strictly less than FD_SETSIZE. This is a limitation of the
* fd_set type. Error out early, because attempting to call FD_SET on a
* large file descriptor is a buffer overflow on typical platforms. */
if( fd >= FD_SETSIZE )
return( MBEDTLS_ERR_NET_POLL_FAILED );
ret = check_fd( fd, 1 );
if( ret != 0 )
return( ret );
#if defined(__has_feature)
#if __has_feature(memory_sanitizer)
@@ -584,8 +598,9 @@ int mbedtls_net_recv( void *ctx, unsigned char *buf, size_t len )
int ret;
int fd = ((mbedtls_net_context *) ctx)->fd;
if( fd < 0 )
return( MBEDTLS_ERR_NET_INVALID_CONTEXT );
ret = check_fd( fd, 0 );
if( ret != 0 )
return( ret );
ret = (int) read( fd, buf, len );
@@ -623,15 +638,9 @@ int mbedtls_net_recv_timeout( void *ctx, unsigned char *buf,
fd_set read_fds;
int fd = ((mbedtls_net_context *) ctx)->fd;
if( fd < 0 )
return( MBEDTLS_ERR_NET_INVALID_CONTEXT );
/* A limitation of select() is that it only works with file descriptors
* that are strictly less than FD_SETSIZE. This is a limitation of the
* fd_set type. Error out early, because attempting to call FD_SET on a
* large file descriptor is a buffer overflow on typical platforms. */
if( fd >= FD_SETSIZE )
return( MBEDTLS_ERR_NET_POLL_FAILED );
ret = check_fd( fd, 1 );
if( ret != 0 )
return( ret );
FD_ZERO( &read_fds );
FD_SET( fd, &read_fds );
@@ -671,8 +680,9 @@ int mbedtls_net_send( void *ctx, const unsigned char *buf, size_t len )
int ret;
int fd = ((mbedtls_net_context *) ctx)->fd;
if( fd < 0 )
return( MBEDTLS_ERR_NET_INVALID_CONTEXT );
ret = check_fd( fd, 0 );
if( ret != 0 )
return( ret );
ret = (int) write( fd, buf, len );