Re: [PATCH net-next v18 07/25] ovpn: implement basic TX path (UDP)

[Antonio Quartulli]

On 04/02/2025 17:18, Sabrina Dubroca wrote:
> 2025-02-03, 10:52:41 +0100, Sabrina Dubroca wrote:
> > 2025-01-13, 10:31:26 +0100, Antonio Quartulli wrote:
> > > +static void ovpn_encrypt_post(struct sk_buff *skb, int ret)
> > > +{
> > > +	struct ovpn_peer *peer = ovpn_skb_cb(skb)->peer;
> > > +
> > > +	if (unlikely(ret < 0))
> > > +		goto err;
> > > +
> > > +	skb_mark_not_on_list(skb);
> > > +
> > > +	switch (peer->sock->sock->sk->sk_protocol) {
> >
> > We have a ref on the peer, but not on the ovpn_sock. DEL_PEER could
> > have detached the sock by the time the crypto completes.
> >
> > (unfortunately I don't have any idea to fix this yet)
>
> Maybe an idea:
>
> Since ovpn_sock itself lives under RCU (because of sk_user_data),
> peer->sock should be an RCU pointer and also follow RCU rules. For
> most parts (io.c, netlink.c) the conversion is not too
> problematic. TCP is more difficult.
>
> I still need to think about whether this works, and whether this is
> worth the complexity, or if we could solve this in another way.

It may actually be a reasonable solution.
And maybe it is not that complex to get done.

I'll see what I come up with.

Regards,


--
Antonio Quartulli
OpenVPN Inc.