Subject: Re: [PATCH net-next v18 12/25] ovpn: implement TCP transport

From: Sabrina Dubroca <[email-masked]>
Date: Mon, 3 Feb 2025 11:05:13 +0100

2025-01-13, 10:31:31 +0100, Antonio Quartulli wrote:
> +static void ovpn_tcp_rcv(struct strparser *strp, struct sk_buff *skb)
> +{
[...]
> +	/* we need the first byte of data to be accessible
> +	 * to extract the opcode and the key ID later on
> +	 */
> +	if (!pskb_may_pull(skb, 1)) {

make sure we have 1B...

> +		net_warn_ratelimited("%s: packet too small to fetch opcode for peer %u\n",
> +				     netdev_name(peer->ovpn->dev), peer->id);
> +		goto err;
> +	}
> +
> +	/* DATA_V2 packets are handled in kernel, the rest goes to user space */
> +	opcode = ovpn_opcode_from_skb(skb, 0);

but this reads a u32 (4B) from skb->data

[...]
> +void ovpn_tcp_socket_detach(struct ovpn_socket *ovpn_sock)
> +{
> +	struct ovpn_peer *peer = ovpn_sock->peer;
> +	struct socket *sock = ovpn_sock->sock;
> +
> +	strp_stop(&peer->tcp.strp);
> +
> +	skb_queue_purge(&peer->tcp.user_queue);
>
> +	/* restore CBs that were saved in ovpn_sock_set_tcp_cb() */
> +	sock->sk->sk_data_ready = peer->tcp.sk_cb.sk_data_ready;
> +	sock->sk->sk_write_space = peer->tcp.sk_cb.sk_write_space;
> +	sock->sk->sk_prot = peer->tcp.sk_cb.prot;
> +	sock->sk->sk_socket->ops = peer->tcp.sk_cb.ops;
> +
> +	/* drop reference to peer */

nit: not really :)

> +	rcu_assign_sk_user_data(sock->sk, NULL);
> +
> +	/* before canceling any ongoing work we must ensure that CBs
> +	 * have been reset to prevent workers from being re-armed
> +	 */
> +	barrier();
> +
> +	cancel_work_sync(&peer->tcp.tx_work);
> +	strp_done(&peer->tcp.strp);
> +	skb_queue_purge(&peer->tcp.out_queue);

Also kfree_skb(peer->tcp.out_msg.skb)?

> +	ovpn_peer_put(peer);
> +}

[...]
> +static int ovpn_tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
> +{
[...]
> +	ret = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
> +	if (ret) {
> +		kfree_skb(skb);
> +		net_err_ratelimited("%s: skb copy from iter failed: %d\n",
> +				    netdev_name(sock->peer->ovpn->dev), ret);
> +		goto peer_free;
> +	}
> +
> +	ovpn_tcp_send_sock_skb(sock->peer, skb);

This isn't propagating MSG_DONTWAIT down to ovpn_tcp_send_sock?

-- 
Sabrina