Subject: Re: [PATCH net-next v11 09/23] ovpn: implement basic RX path (UDP)

From: Sabrina Dubroca <[email-masked]>
Date: Thu, 31 Oct 2024 12:29:01 +0100

2024-10-29, 11:47:22 +0100, Antonio Quartulli wrote:
> +static int ovpn_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
> +{
[...]
> +	opcode = ovpn_opcode_from_skb(skb, sizeof(struct udphdr));
> +	if (unlikely(opcode != OVPN_DATA_V2)) {
> +		/* DATA_V1 is not supported */
> +		if (opcode == OVPN_DATA_V1)

The TCP encap code passes everything that's not V2 to userspace. Why
not do that with UDP as well?

> +			goto drop;
> +
> +		/* unknown or control packet: let it bubble up to userspace */
> +		return 1;
> +	}
> +
> +	peer_id = ovpn_peer_id_from_skb(skb, sizeof(struct udphdr));
> +	/* some OpenVPN server implementations send data packets with the
> +	 * peer-id set to undef. In this case we skip the peer lookup by peer-id
> +	 * and we try with the transport address
> +	 */
> +	if (peer_id != OVPN_PEER_ID_UNDEF) {
> +		peer = ovpn_peer_get_by_id(ovpn, peer_id);
> +		if (!peer) {
> +			net_err_ratelimited("%s: received data from unknown peer (id: %d)\n",
> +					    __func__, peer_id);
> +			goto drop;
> +		}
> +	}
> +
> +	if (!peer) {

nit: that could be an "else" combined with the previous case?

> +		/* data packet with undef peer-id */
> +		peer = ovpn_peer_get_by_transp_addr(ovpn, skb);
> +		if (unlikely(!peer)) {
> +			net_dbg_ratelimited("%s: received data with undef peer-id from unknown source\n",
> +					    __func__);
> +			goto drop;
> +		}
> +	}

-- 
Sabrina