6.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Antoine Tenart <atenart@xxxxxxxxxx>
commit 64235eabc4b5b18c507c08a1f16cdac6c5661220 upstream.
GRO has a fundamental issue with UDP tunnel packets as it can't detect
those in a foolproof way and GRO could happen before they reach the
tunnel endpoint. Previous commits have fixed issues when UDP tunnel
packets come from a remote host, but if those packets are issued locally
they could run into checksum issues.
If the inner packet has a partial checksum the information will be lost
in the GRO logic, either in udp4/6_gro_complete or in
udp_gro_complete_segment and packets will have an invalid checksum when
leaving the host.
Prevent local UDP tunnel packets from ever being GROed at the outer UDP
level.
Due to skb->encapsulation being wrongly used in some drivers this is
actually only preventing UDP tunnel packets with a partial checksum to
be GROed (see iptunnel_handle_offloads) but those were also the packets
triggering issues so in practice this should be sufficient.
Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Suggested-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Antoine Tenart <atenart@xxxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/udp_offload.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -559,6 +559,12 @@ struct sk_buff *udp_gro_receive(struct l
*/
NAPI_GRO_CB(skb)->is_flist = 0;
if (!sk || !udp_sk(sk)->gro_receive) {
+ /* If the packet was locally encapsulated in a UDP tunnel that
+ * wasn't detected above, do not GRO.
+ */
+ if (skb->encapsulation)
+ goto out;
+
if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
NAPI_GRO_CB(skb)->is_flist = sk ? !udp_test_bit(GRO_ENABLED, sk) : 1;
