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    SubjectRe: [PATCH 5.19 0537/1157] bpf: Set flow flag to allow any source IP in bpf_tunnel_key
    On Mon, Aug 15, 2022 at 07:58:13PM +0200, Greg Kroah-Hartman wrote:
    > From: Paul Chaignon <paul@isovalent.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.

    >
    > Fixes: 26101f5ab6bd ("bpf: Add source ip in "struct bpf_tunnel_key"")
    > Signed-off-by: Paul Chaignon <paul@isovalent.com>
    > Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
    > Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
    > Acked-by: Martin KaFai Lau <kafai@fb.com>
    > Link: https://lore.kernel.org/bpf/76873d384e21288abe5767551a0799ac93ec07fb.1658759380.git.paul@isovalent.com
    > Signed-off-by: Sasha Levin <sashal@kernel.org>
    > ---
    > net/core/filter.c | 1 +
    > 1 file changed, 1 insertion(+)
    >
    > diff --git a/net/core/filter.c b/net/core/filter.c
    > index 7950f7520765..5978984b752f 100644
    > --- a/net/core/filter.c
    > +++ b/net/core/filter.c
    > @@ -4653,6 +4653,7 @@ BPF_CALL_4(bpf_skb_set_tunnel_key, struct sk_buff *, skb,
    > } else {
    > info->key.u.ipv4.dst = cpu_to_be32(from->remote_ipv4);
    > info->key.u.ipv4.src = cpu_to_be32(from->local_ipv4);
    > + info->key.flow_flags = FLOWI_FLAG_ANYSRC;
    > }
    >
    > return 0;
    > --
    > 2.35.1
    >
    >
    >

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