Re: [PATCH] bridge: Superfluous skb->nfct check in br_nf_dev_queue_xmit

[Vasily Averin <vvs@parallels.com>]

On 05/04/2014 04:54 PM, Pablo Neira Ayuso wrote:
> On Wed, Apr 30, 2014 at 12:54:50PM +0400, Vasily Averin wrote:
>> Currently bridge can silently drop ipv4 fragments.
>> If node have loaded nf_defrag_ipv4 module but have no nf_conntrack_ipv4,
>> br_nf_pre_routing defragments incoming ipv4 fragments
>> but nfct check in br_nf_dev_queue_xmit does not allow re-fragment combined packet back,
>> and therefore it is dropped in br_dev_queue_push_xmit without incrementing of any failcounters
> 
> If no further objections, I'll push this original patch appending this comment
> to the description:
> 
> [ It seems the only way to hit the ip_fragment code in the bridge xmit
>   path is to have a fragment list whose reassembled fragments go over
>   the mtu. This only happens if nf_defrag is enabled. Thanks to
>   Florian Westphal for providing feedback to clarify this. ]

I have not objections, however I still do not understand why #if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV4) 
is required in br_dev_queue_push_xmit()?

If ipv4 defragmentation is required not only for conntracks but for TPROXY target and xt_socket match
I think we need to use NF_DEFRAG_IPV4 instead.