From: Leon Hwang <leon.hwang@linux•dev>
To: bpf@vger•kernel.org
Cc: "David S . Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>,
Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>,
Simon Horman <horms@kernel•org>,
Andrii Nakryiko <andrii@kernel•org>,
Eduard Zingerman <eddyz87@gmail•com>,
Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <daniel@iogearbox•net>,
Martin KaFai Lau <martin.lau@linux•dev>,
Kumar Kartikeya Dwivedi <memxor@gmail•com>,
Song Liu <song@kernel•org>,
Yonghong Song <yonghong.song@linux•dev>,
Jiri Olsa <jolsa@kernel•org>, Shuah Khan <shuah@kernel•org>,
Guillaume Nault <gnault@redhat•com>,
Leon Hwang <leon.hwang@linux•dev>,
Ido Schimmel <idosch@nvidia•com>,
Fernando Fernandez Mancera <fmancera@suse•de>,
Peter Oskolkov <posk@google•com>,
linux-kernel@vger•kernel.org, netdev@vger•kernel.org,
linux-kselftest@vger•kernel.org, kernel-patches-bot@fb•com
Subject: [PATCH bpf v4 0/2] bpf: Update transport_header when encapsulating UDP tunnel in lwt
Date: Tue, 2 Jun 2026 23:09:29 +0800 [thread overview]
Message-ID: <20260602150931.49629-1-leon.hwang@linux.dev> (raw)
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.
Changes:
v3 -> v4:
* Address comments from Emil:
* Make the logic of skb_set_transport_header() clearer in patch #1.
* Fold the code of fexit_lwt_push_ip_encap() into test_lwt_ip_encap.c in
patch #2.
* Resolve assorted issues of test in patch #2.
* v3: https://lore.kernel.org/bpf/20260601150203.20352-1-leon.hwang@linux.dev/
v2 -> v3:
* Drop patch #1 and #2 of v2 that aim to resolve potential issues
reported by sashiko (per Alexei).
* Check target IP version and UDP tunnel in test (per sashiko).
* v2: https://lore.kernel.org/bpf/20260529151351.69911-1-leon.hwang@linux.dev/
v1 -> v2:
* Address sashiko's reviews:
* Fix TOCTOU issue in lwt to avoid changing hdr after checks.
* Add check iph->ihl < 5 in lwt to avoid infinite-loop in MIPS driver.
* Update comment style in selftests with BPF comment style.
* v1: https://lore.kernel.org/bpf/20260525142650.2569-1-leon.hwang@linux.dev/
Leon Hwang (2):
bpf: Update transport_header when encapsulating UDP tunnel in lwt
selftests/bpf: Add tests to verify the fix of encapsulating VxLAN in
lwt
net/core/lwt_bpf.c | 12 ++
.../selftests/bpf/prog_tests/lwt_ip_encap.c | 145 ++++++++++++++++
.../selftests/bpf/progs/test_lwt_ip_encap.c | 155 ++++++++++++++++--
3 files changed, 302 insertions(+), 10 deletions(-)
--
2.54.0
next reply other threads:[~2026-06-02 15:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-02 15:09 Leon Hwang [this message]
2026-06-02 15:09 ` [PATCH bpf v4 1/2] bpf: Update transport_header when encapsulating UDP tunnel in lwt Leon Hwang
2026-06-02 15:51 ` bot+bpf-ci
2026-06-02 15:09 ` [PATCH bpf v4 2/2] selftests/bpf: Add tests to verify the fix of encapsulating VxLAN " Leon Hwang
2026-06-05 22:30 ` [PATCH bpf v4 0/2] bpf: Update transport_header when encapsulating UDP tunnel " patchwork-bot+netdevbpf
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