Re: [RFC][PATCH] kill the fake conntrack

[Patrick McHardy <kaber@trash.net>]

Pablo Neira wrote:
> Patrick McHardy wrote:
> 
>> What is the advantage of this patch?
> 
> Whenever we work with conntracks, we always have to check if it's the
> fake or not previously. For example, a bad use of NOTRACK together with
> other targets, say ipt_CONNMARK, that doesn't currently check if it's
> working with the fake conntrack or not. Same thing for NAT handlings, I
> see that this can result in weirdness.
> 
> Setting nfct to NULL will make NAT targets, conntrack helpers and
> friends just ignore untracked packets, so we could forget about making
> sure that we aren't messing with the fake conntrack.

Sounds reasonable - but couldn't we simply change ip_conntrack_get
to return NULL for untracked connections?

>> Its changing the assumption
>> that skb->nfctinfo is only valid if skb->nfct is set, so you probably
>> need to set nfctinfo to 0 in nf_reset as well. This alone is a reason
>> not to do it IMO.
> 
> why need to set nfctinfo to 0 in nf_reset? since skb->nfct is NULL
> nf_reset shouldn't be ever called. With the logic I'm proposing, this
> packet will be handle just like invalid ones, so it will be just ignored.

nf_reset is called independant of the contents of skb->nfct. nfctinfo
needs to be set to 0 so a packet isn't untracked afterwards anymore.
Think of tunnel devices.

Regards
Patrick