Re: [PATCH] vhost: add note about sockets in server mode

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Ilya,

On 02/26/2018 09:39 AM, Ilya Maximets wrote:
>  From time to time, someone sends patches about unlinking existing
> sockets when registering a vhost user in server mode.
> 
> A recent example:
> 	http://dpdk.org/ml/archives/dev/2018-February/090025.html
> 
> This problem has been discussed many times, and it was made clear that
> the library should not unlink files given by the application in order
> to avoid possible security problems, such as removing random files
> used by other programs.
> 
> One of the first discussions:
> 	http://dpdk.org/ml/archives/dev/2015-December/030326.html
> 
> To avoid such patches in the future, it was decided to add a comment
> that explains what is happening and tries to describe the reasoning.
> 
> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
> ---
> 
> I'm open for suggestions. Wording/grammar fixes are also welcome.
> 
>   lib/librte_vhost/socket.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
> index 83befdc..e8584f3 100644
> --- a/lib/librte_vhost/socket.c
> +++ b/lib/librte_vhost/socket.c
> @@ -318,6 +318,16 @@ vhost_user_start_server(struct vhost_user_socket *vsocket)
>   	int fd = vsocket->socket_fd;
>   	const char *path = vsocket->path;
>   
> +	/*
> +	 * bind () may fail if the socket file with the same name already
> +	 * exists. But the library obviously should not delete the file
> +	 * provided by the user, since we can not be sure that it is not
> +	 * being used by other applications. Moreover, many applications form
> +	 * socket names based on user input, which is prone to errors.
> +	 *
> +	 * The user must ensure that the socket does not exist before
> +	 * registering the vhost driver in server mode.
> +	 */
>   	ret = bind(fd, (struct sockaddr *)&vsocket->un, sizeof(vsocket->un));
>   	if (ret < 0) {
>   		RTE_LOG(ERR, VHOST_CONFIG,
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks!
Maxime