linux-kernel - Re: [PATCH 5.19 0537/1157] bpf: Set flow flag to allow any source IP in bpf_tunnel

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Message-ID: <20220816150727.GA88824@Mem>
Date:   Tue, 16 Aug 2022 17:07:27 +0200
From:   Paul Chaignon <paul@...valent.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Martin KaFai Lau <kafai@...com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.19 0537/1157] bpf: Set flow flag to allow any source IP
 in bpf_tunnel_key

On Tue, Aug 16, 2022 at 04:47:30PM +0200, Greg Kroah-Hartman wrote:
> On Tue, Aug 16, 2022 at 04:35:54PM +0200, Paul Chaignon wrote:
> > On Mon, Aug 15, 2022 at 07:58:13PM +0200, Greg Kroah-Hartman wrote:
> > > From: Paul Chaignon <paul@...valent.com>
> > > 
> > > [ Upstream commit b8fff748521c7178b9a7d32b5a34a81cec8396f3 ]
> > > 
> > > Commit 26101f5ab6bd ("bpf: Add source ip in "struct bpf_tunnel_key"")
> > > added support for getting and setting the outer source IP of encapsulated
> > > packets via the bpf_skb_{get,set}_tunnel_key BPF helper. This change
> > > allows BPF programs to set any IP address as the source, including for
> > > example the IP address of a container running on the same host.
> > > 
> > > In that last case, however, the encapsulated packets are dropped when
> > > looking up the route because the source IP address isn't assigned to any
> > > interface on the host. To avoid this, we need to set the
> > > FLOWI_FLAG_ANYSRC flag.
> > 
> > This fix will also require upstream commits 861396ac0b47 ("geneve: Use
> > ip_tunnel_key flow flags in route lookups") and 7e2fb8bc7ef6 ("vxlan:
> > Use ip_tunnel_key flow flags in route lookups") to have the intended
> > effect. In short, these two commits "consume" the new field introduced
> > in 451ef36bd229 ("ip_tunnels: Add new flow flags field to
> > ip_tunnel_key") and populated in the present commit.
> 
> Ick.  Is it better to just drop this commit instead?  Or is it ok to
> also backport those 2 patches to 5.19.y?

It should be okay to backport those additional 2 patches to 5.19.y.

Thank you,

--
Paul