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

Antonio Quartulli
2025-02-05T09:11:38Z

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.