Currently, bpf_lwt_push_ip_encap() does not update skb->transport_header.
When a driver, e.g. ice, reuses the stale skb->transport_header to
offload checksum computation to NIC hardware, VxLAN packets encapsulated
by bpf_lwt_push_encap() helper may be dropped due to incorrect checksum.
Update skb->transport_header in bpf_lwt_push_ip_encap() whenever the
encapsulated packet uses UDP, so checksum offload works correctly.
Fixes: 52f278774e79 ("bpf: implement BPF_LWT_ENCAP_IP mode in
bpf_lwt_push_encap")
Cc: Leon Hwang <[email protected]>
Signed-off-by: Leon Hwang <[email protected]>
---
net/core/lwt_bpf.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index f71ef82a5f3d..cbb2803367c6 100644
--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c
@@ -637,6 +637,10 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr,
u32 len, bool ingress)
if (ingress)
skb_postpush_rcsum(skb, iph, len);
skb_reset_network_header(skb);
+ if (ipv4 && iph->protocol == IPPROTO_UDP /* UDP tunnel */)
+ skb_set_transport_header(skb, skb_network_offset(skb) +
iph->ihl * 4);
+ else if (!ipv4 && ((struct ipv6hdr *)hdr)->nexthdr == NEXTHDR_UDP /*
UDP tunnel */)
+ skb_set_transport_header(skb, skb_network_offset(skb) +
sizeof(struct ipv6hdr));
memcpy(skb_network_header(skb), hdr, len);
bpf_compute_data_pointers(skb);
skb_clear_hash(skb);
--
2.54.0
