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

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Message-ID: <2c22945a-1906-43a6-9339-d097242ac5fd@openvpn.net>
Date: Mon, 3 Feb 2025 10:58:55 +0100
From: Antonio Quartulli <antonio@...nvpn.net>
To: Sabrina Dubroca <sd@...asysnail.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)



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.