linux-kernel - Re: [PATCH net-next v5 3/5] net: vxlan: bind vxlan sockets to their local address if configured

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Message-ID: <088b9c26-482d-49af-bd22-bc870aaae851@gmail.com>
Date: Wed, 13 Aug 2025 17:41:12 +0200
From: Richard Gobert <richardbgobert@...il.com>
To: Kuniyuki Iwashima <kuniyu@...gle.com>
Cc: andrew+netdev@...n.ch, daniel@...earbox.net, davem@...emloft.net,
 donald.hunter@...il.com, dsahern@...nel.org, edumazet@...gle.com,
 horms@...nel.org, idosch@...dia.com, jacob.e.keller@...el.com,
 kuba@...nel.org, linux-kernel@...r.kernel.org, martin.lau@...nel.org,
 menglong8.dong@...il.com, netdev@...r.kernel.org, pabeni@...hat.com,
 petrm@...dia.com, razor@...ckwall.org, shuah@...nel.org
Subject: Re: [PATCH net-next v5 3/5] net: vxlan: bind vxlan sockets to their
 local address if configured

Kuniyuki Iwashima wrote:
> From: Richard Gobert <richardbgobert@...il.com>
> Date: Tue, 12 Aug 2025 14:51:53 +0200
>> diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
>> index 15fe9d83c724..12da9595436e 100644
>> --- a/drivers/net/vxlan/vxlan_core.c
>> +++ b/drivers/net/vxlan/vxlan_core.c
>> @@ -78,18 +78,34 @@ static inline bool vxlan_collect_metadata(struct vxlan_sock *vs)
>>  }
>>  
>>  /* Find VXLAN socket based on network namespace, address family, UDP port,
>> - * enabled unshareable flags and socket device binding (see l3mdev with
>> - * non-default VRF).
>> + * bound address, enabled unshareable flags and socket device binding
>> + * (see l3mdev with non-default VRF).
>>   */
>>  static struct vxlan_sock *vxlan_find_sock(struct net *net, sa_family_t family,
>> -					  __be16 port, u32 flags, int ifindex)
>> +					  __be16 port, u32 flags, int ifindex,
>> +					  union vxlan_addr *saddr)
>>  {
>>  	struct vxlan_sock *vs;
>>  
>>  	flags &= VXLAN_F_RCV_FLAGS;
> 
> VXLAN_F_LOCALBIND seems to be cleared ?
> 
>>  
>>  	hlist_for_each_entry_rcu(vs, vs_head(net, port), hlist) {
>> -		if (inet_sk(vs->sock->sk)->inet_sport == port &&
>> +		struct sock *sk = vs->sock->sk;
>> +		struct inet_sock *inet = inet_sk(sk);
>> +
>> +		if (flags & VXLAN_F_LOCALBIND) {
> 
> Does selftest exercise this path ?
> 
> 
>> +			if (family == AF_INET &&
>> +			    inet->inet_rcv_saddr != saddr->sin.sin_addr.s_addr)
>> +				continue;
>> +#if IS_ENABLED(CONFIG_IPV6)
>> +			else if (family == AF_INET6 &&
>> +				 ipv6_addr_cmp(&sk->sk_v6_rcv_saddr,
>> +					       &saddr->sin6.sin6_addr) != 0)
>> +				continue;
>> +#endif
>> +		}
>> +
>> +		if (inet->inet_sport == port &&
>>  		    vxlan_get_sk_family(vs) == family &&
>>  		    vs->flags == flags &&
>>  		    vs->sock->sk->sk_bound_dev_if == ifindex)

Nice catch. I don't think the new selftest exercises this path, but I'm
running the other vxlan selftests with the localbind option enabled by default
and ensuring that they pass.