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| author | Leon Hwang <leon.hwang@linux.dev> | 2026-06-02 23:09:30 +0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-06-05 15:28:28 -0700 |
| commit | 82d7d0adbc678064543e9d254864f6b4ea4a388c (patch) | |
| tree | 5420abdf68d3ab937442faa379038a55299d20fc /net/core | |
| parent | b9845290525cf19d29f3a0d06ae3feb923f60e4c (diff) | |
| download | linux-next-82d7d0adbc678064543e9d254864f6b4ea4a388c.tar.gz linux-next-82d7d0adbc678064543e9d254864f6b4ea4a388c.zip | |
bpf: Update transport_header when encapsulating UDP tunnel in lwt
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 <leon.huangfu@shopee.com>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260602150931.49629-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/lwt_bpf.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index f71ef82a5f3d..bf588f508b79 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -599,6 +599,7 @@ static int handle_gso_encap(struct sk_buff *skb, bool ipv4, int encap_len) int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) { + bool is_udp_tunnel; struct iphdr *iph; bool ipv4; int err; @@ -612,10 +613,16 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) ipv4 = true; if (unlikely(len < iph->ihl * 4)) return -EINVAL; + is_udp_tunnel = iph->protocol == IPPROTO_UDP; + if (unlikely(is_udp_tunnel && len < iph->ihl * 4 + sizeof(struct udphdr))) + return -EINVAL; } else if (iph->version == 6) { ipv4 = false; if (unlikely(len < sizeof(struct ipv6hdr))) return -EINVAL; + is_udp_tunnel = ((struct ipv6hdr *)iph)->nexthdr == NEXTHDR_UDP; + if (unlikely(is_udp_tunnel && len < sizeof(struct ipv6hdr) + sizeof(struct udphdr))) + return -EINVAL; } else { return -EINVAL; } @@ -637,6 +644,11 @@ 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 (is_udp_tunnel) { + size_t iph_sz = ipv4 ? iph->ihl * 4 : sizeof(struct ipv6hdr); + + skb_set_transport_header(skb, skb_network_offset(skb) + iph_sz); + } memcpy(skb_network_header(skb), hdr, len); bpf_compute_data_pointers(skb); skb_clear_hash(skb); |