linux-kernel - Re: [PATCH net-next v14 08/22] ovpn: implement basic RX path (UDP)

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Message-ID: <7d986843-d184-4ed7-930f-d30ae2bc4923@openvpn.net>
Date: Wed, 11 Dec 2024 11:00:06 +0100
From: Antonio Quartulli <antonio@...nvpn.net>
To: Simon Horman <horms@...nel.org>
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>,
 sd@...asysnail.net, ryazanov.s.a@...il.com,
 Andrew Lunn <andrew+netdev@...n.ch>, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next v14 08/22] ovpn: implement basic RX path (UDP)

On 10/12/2024 17:44, Simon Horman wrote:
> On Mon, Dec 09, 2024 at 09:53:17AM +0100, Antonio Quartulli wrote:
>> Packets received over the socket are forwarded to the user device.
>>
>> Implementation is UDP only. TCP will be added by a later patch.
>>
>> Note: no decryption/decapsulation exists yet, packets are forwarded as
>> they arrive without much processing.
>>
>> Signed-off-by: Antonio Quartulli <antonio@...nvpn.net>
> 
> ...
> 
>> diff --git a/drivers/net/ovpn/udp.c b/drivers/net/ovpn/udp.c
>> index c0e7aa289ad3345fcd91e7c890f70961300c356f..975392fc39bc4c0107a07a53795afecd88d72c53 100644
>> --- a/drivers/net/ovpn/udp.c
>> +++ b/drivers/net/ovpn/udp.c
>> @@ -23,9 +23,83 @@
>>   #include "bind.h"
>>   #include "io.h"
>>   #include "peer.h"
>> +#include "proto.h"
>>   #include "socket.h"
>>   #include "udp.h"
>>   
>> +/**
>> + * 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.
>> + *
>> + * 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)
>> +{
>> +	struct ovpn_priv *ovpn;
>> +	struct ovpn_peer *peer;
>> +	u32 peer_id;
>> +	u8 opcode;
>> +
>> +	ovpn = ovpn_from_udp_sock(sk);
>> +	if (unlikely(!ovpn)) {
>> +		net_err_ratelimited("%s: cannot obtain ovpn object from UDP socket\n",
>> +				    netdev_name(ovpn->dev));
> 
> Hi Antonio,
> 
> If we reach here then ovpn is NULL.
> But the like above dereferences it.
> 
> Flagged by Smatch.

Hi Simon,
Thanks for pointing this out. I will get this fixed and add smatch to my 
test battery.

Regards,

> 
>> +		goto drop_noovpn;
>> +	}
> 
> ...
> 

-- 
Antonio Quartulli
OpenVPN Inc.