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

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Message-ID: <Z6CMmJyJwZBuV-lC@hog>
Date: Mon, 3 Feb 2025 10:30:00 +0100
From: Sabrina Dubroca <sd@...asysnail.net>
To: Antonio Quartulli <antonio@...nvpn.net>
Cc: netdev@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Donald Hunter <donald.hunter@...il.com>,
	Shuah Khan <shuah@...nel.org>, ryazanov.s.a@...il.com,
	Andrew Lunn <andrew+netdev@...n.ch>,
	Simon Horman <horms@...nel.org>, linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org, Xiao Liang <shaw.leon@...il.com>
Subject: Re: [PATCH net-next v18 08/25] ovpn: implement basic RX path (UDP)

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.


> +/**
> + * 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

> + * 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;

-- 
Sabrina