Re: [PATCH net-next v18 08/25] ovpn: implement basic RX path (UDP)

[Antonio Quartulli]

On 03/02/2025 10:30, Sabrina Dubroca wrote:
> 2025-01-13, 10:31:27 +0100, Antonio Quartulli wrote:
> > +/**
> > + * ovpn_opcode_from_skb - extract OP code from skb at specified offset
> > + * @skb: the packet to extract the OP code from
> > + * @offset: the offset in the data buffer where the OP code is located
> > + *
> > + * Note: this function assumes that the skb head was pulled enough
> > + * to access the first byte.
>
> nit:
>                     "first byte"
>
> > + *
> > + * Return: the OP code
> > + */
> > +static inline u8 ovpn_opcode_from_skb(const struct sk_buff *skb, u16 offset)
> > +{
> > +	u32 opcode = be32_to_cpu(*(__be32 *)(skb->data + offset));
>
> vs 4 bytes actually read?
>
> Also for ovpn_key_id_from_skb introduced in another patch. I guess
> that's a consequence of switching to those FIELD macros.

Your guess is right. I'll fix the comment.

> > +/**
> > + * ovpn_udp_encap_recv - Start processing a received UDP packet.
> > + * @sk: socket over which the packet was received
> > + * @skb: the received packet
> > + *
> > + * If the first byte of the payload is DATA_V2, the packet is further processed,
> > + * otherwise it is forwarded to the UDP stack for delivery to user space.
>
> nit: not consistent with the implementation in the case of DATA_V1 packets

Right, I'll extend the comment.

> > + * Return:
> > + *  0 if skb was consumed or dropped
> > + * >0 if skb should be passed up to userspace as UDP (packet not consumed)
> > + * <0 if skb should be resubmitted as proto -N (packet not consumed)
> > + */
> > +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)
> > +			goto drop;

Thanks!


--
Antonio Quartulli
OpenVPN Inc.