Patch-mainline: v5.16-rc7

Git-commit: 1ed1d592113959f00cc552c3b9f47ca2d157768f

References: git-fixes

From: Willem de Bruijn <willemb@google.com>

Date: Mon, 20 Dec 2021 09:50:27 -0500

Subject: [PATCH] net: skip virtio_net_hdr_set_proto if protocol already set

virtio_net_hdr_set_proto infers skb->protocol from the virtio_net_hdr

gso_type, to avoid packets getting dropped for lack of a proto type.

Its protocol choice is a guess, especially in the case of UFO, where

the single VIRTIO_NET_HDR_GSO_UDP label covers both UFOv4 and UFOv6.

Skip this best effort if the field is already initialized. Whether

explicitly from userspace, or implicitly based on an earlier call to

dev_parse_header_protocol (which is more robust, but was introduced

after this patch).

Fixes: 9d2f67e43b73 ("net/packet: fix packet drop as of virtio gso")

Signed-off-by: Willem de Bruijn <willemb@google.com>

Link: https://lore.kernel.org/r/20211220145027.2784293-1-willemdebruijn.kernel@gmail.com

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Juergen Gross <jgross@suse.com>

---

 include/linux/virtio_net.h | 3 +++

 1 file changed, 3 insertions(+)

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h

index 22dd48c82560..a960de68ac69 100644

--- a/include/linux/virtio_net.h

+++ b/include/linux/virtio_net.h

@@ -25,6 +25,9 @@ static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)

 static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,

 					   const struct virtio_net_hdr *hdr)

 {

+	if (skb->protocol)

+		return 0;

+

 	switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {

 	case VIRTIO_NET_HDR_GSO_TCPV4:

 	case VIRTIO_NET_HDR_GSO_UDP:

-- 

2.35.3