netdev - Re: [PATCH nf-next v9 2/3] net: netfilter: Add IPIP flowtable tx sw acceleration

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <aRWLhLobB4Rz0dA_@lore-desk>
Date: Thu, 13 Nov 2025 08:40:52 +0100
From: Lorenzo Bianconi <lorenzo@...nel.org>
To: Pablo Neira Ayuso <pablo@...filter.org>
Cc: "David S. Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	Jozsef Kadlecsik <kadlec@...filter.org>,
	Shuah Khan <shuah@...nel.org>, Andrew Lunn <andrew+netdev@...n.ch>,
	Phil Sutter <phil@....cc>, Florian Westphal <fw@...len.de>,
	netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
	coreteam@...filter.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH nf-next v9 2/3] net: netfilter: Add IPIP flowtable tx sw
 acceleration

> Hi Lorenzo,

Hi Pablo,

> 
> On Wed, Nov 12, 2025 at 05:02:37PM +0100, Lorenzo Bianconi wrote:
> [...]
> > > On Fri, Nov 07, 2025 at 12:14:47PM +0100, Lorenzo Bianconi wrote:
> > > [...]
> > > > @@ -565,8 +622,9 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
> > > >  
> > > >  	dir = tuplehash->tuple.dir;
> > > >  	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
> > > > +	other_tuple = &flow->tuplehash[!dir].tuple;
> > > >  
> > > > -	if (nf_flow_encap_push(skb, &flow->tuplehash[!dir].tuple) < 0)
> > > > +	if (nf_flow_encap_push(state->net, skb, other_tuple))
> > > >  		return NF_DROP;
> > > >  
> > > >  	switch (tuplehash->tuple.xmit_type) {
> > > > @@ -577,7 +635,9 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
> > > >  			flow_offload_teardown(flow);
> > > >  			return NF_DROP;
> > > >  		}
> > > > -		neigh = ip_neigh_gw4(rt->dst.dev, rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr));
> > > > +		dest = other_tuple->tun_num ? other_tuple->tun.src_v4.s_addr
> > > > +					    : other_tuple->src_v4.s_addr;
> > > 
> > > I think this can be simplified if my series use the ip_hdr(skb)->daddr
> > > for rt_nexthop(), see attached patch. This would be fetched _before_
> > > pushing the tunnel and layer 2 encapsulation headers. Then, there is
> > > no need to fetch other_tuple and check if tun_num is greater than
> > > zero.
> > > 
> > > See my sketch patch, I am going to give this a try, if this is
> > > correct, I would need one more iteration from you.
> > >
> > > diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
> > > index 8b74fb34998e..ff2b6c16c715 100644
> > > --- a/net/netfilter/nf_flow_table_ip.c
> > > +++ b/net/netfilter/nf_flow_table_ip.c
> > > @@ -427,6 +427,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
> > >  	struct flow_offload *flow;
> > >  	struct neighbour *neigh;
> > >  	struct rtable *rt;
> > > +	__be32 ip_dst;
> > >  	int ret;
> > >  
> > >  	tuplehash = nf_flow_offload_lookup(&ctx, flow_table, skb);
> > > @@ -449,6 +450,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
> > >  
> > >  	dir = tuplehash->tuple.dir;
> > >  	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
> > > +	ip_dst = ip_hdr(skb)->daddr;
> > 
> > I agree this patch will simplify my series (thx :)) but I guess we should move
> > ip_dst initialization after nf_flow_encap_push() since we need to route the
> > traffic according to the tunnel dst IP address, right?
> 
> Right, I made a quick edit, it looks like this:
> 
> @@ -566,9 +624,14 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
>  
>         dir = tuplehash->tuple.dir;
>         flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
> +       other_tuple = &flow->tuplehash[!dir].tuple;
> +
> +       if (nf_flow_tunnel_push(skb, other_tuple) < 0)
> +               return NF_DROP;
> +
>         ip_daddr = ip_hdr(skb)->daddr;
>  
> -       if (nf_flow_encap_push(skb, &flow->tuplehash[!dir].tuple) < 0)
> +       if (nf_flow_encap_push(skb, other_tuple) < 0)
>                 return NF_DROP;
>  
>         switch (tuplehash->tuple.xmit_type) {
> 
> That is, after tunnel header push but before pushing l2 encap (that
> could possibly modify skb_network_header pointer), fetch the
> destination address.
> 
> I made a few more comestic edits on your series and I pushed them out
> to this branch:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next.git/log/?h=flowtable-consolidate-xmit%2bipip
[

ack, I tested this branch and it works fine running my local tests. Thanks for
fixing pending bits.

Regards,
Lorenzo

> 
> I just noticed, in nf_flow_tunnel_ipip_push(), that this can be removed:
> 
>         memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
> 
> because this packet never entered the IP layer, the flowtable takes it
> before it can get there.

Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)