netdev - Re: [PATCH net-next 1/4] vxlan: Join / leave MC group after remote changes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87seoksdjh.fsf@nvidia.com>
Date: Tue, 11 Feb 2025 15:56:59 +0100
From: Petr Machata <petrm@...dia.com>
To: Paolo Abeni <pabeni@...hat.com>
CC: Petr Machata <petrm@...dia.com>, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
	<netdev@...r.kernel.org>, Ido Schimmel <idosch@...dia.com>,
	<mlxsw@...dia.com>, Andrew Lunn <andrew+netdev@...n.ch>, Nikolay Aleksandrov
	<razor@...ckwall.org>, Roopa Prabhu <roopa@...dia.com>, Menglong Dong
	<menglong8.dong@...il.com>, Guillaume Nault <gnault@...hat.com>
Subject: Re: [PATCH net-next 1/4] vxlan: Join / leave MC group after remote
 changes


Paolo Abeni <pabeni@...hat.com> writes:

> On 2/7/25 6:34 PM, Petr Machata wrote:
>> @@ -3899,6 +3904,11 @@ static void vxlan_config_apply(struct net_device *dev,
>>  			dev->mtu = conf->mtu;
>>  
>>  		vxlan->net = src_net;
>> +
>> +	} else if (vxlan->dev->flags & IFF_UP) {
>> +		if (vxlan_addr_multicast(&vxlan->default_dst.remote_ip) &&
>> +		    rem_changed)
>> +			vxlan_multicast_leave(vxlan);
>
> AFAICS vxlan_vni_update_group() is not completely ignore
> vxlan_multicast_{leave,join} errors. Instead is bailing out as soon as
> any error happens. For consistency's sake I think it would be better do
> the same here.
>
> Also I have the feeling that ending-up in an inconsistent status with no
> group joined would be less troublesome than the opposite.

This can already happen FWIW. If you currently want to change the remote
group address in a way that doesn't break things, you take the netdevice
down, then change it, then bring it back up. The leave during downing
can fail and will not be diagnosed. (Nor can it really be, you can't
veto downing.)

I can add the bail-outs that you ask for, but I don't know that there is
a way to resolve these issues for real.