Re: [PATCH net-next 10/10] mptcp: support TCP_CORK and TCP_NODELAY

[Paolo Abeni <pabeni@redhat.com>]

On Mon, 2021-12-06 at 17:30 -0800, Jakub Kicinski wrote:
> On Fri,  3 Dec 2021 14:35:41 -0800 Mat Martineau wrote:
> > +static int mptcp_setsockopt_sol_tcp_nodelay(struct mptcp_sock *msk, sockptr_t optval,
> > +					    unsigned int optlen)
> > +{
> > +	struct mptcp_subflow_context *subflow;
> > +	struct sock *sk = (struct sock *)msk;
> > +	int val;
> > +
> > +	if (optlen < sizeof(int))
> > +		return -EINVAL;
> > +
> > +	if (copy_from_sockptr(&val, optval, sizeof(val)))
> > +		return -EFAULT;
> 
> Should we check that optval is not larger than sizeof(int) or if it is
> that the rest of the buffer is zero? Or for the old school options we
> should stick to the old school behavior?

I think it's useful if we keep the MPTCP socket options binary API as
close as possible to the plain TCP ones: that allows for seamless
switching existing TCP application to MPTCP with no code changes.

Old school, please ;)

Cheers,

Paolo