From: Jiayuan Chen <jiayuan.chen@linux.dev>
To: Jakub Kicinski <kuba@kernel.org>
Cc: bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>,
Shuah Khan <shuah@kernel.org>,
Kuniyuki Iwashima <kuniyu@google.com>,
Hangbin Liu <liuhangbin@gmail.com>,
Krishna Kumar <krikku@gmail.com>,
Samiullah Khawaja <skhawaja@google.com>,
Martin Karsten <mkarsten@uwaterloo.ca>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH bpf-next v4 2/3] bpf, xdp: move offload check into dev_xdp_install()
Date: Tue, 11 Aug 2026 11:06:34 +0800 [thread overview]
Message-ID: <cf8655ff-4e45-40ab-898e-aff2aa7145c5@linux.dev> (raw)
In-Reply-To: <20260810114958.64e6a83d@kernel.org>
On 8/11/26 2:49 AM, Jakub Kicinski wrote:
> On Mon, 10 Aug 2026 13:06:00 +0800 Jiayuan Chen wrote:
>> bpf_xdp_link_update() calls dev_xdp_install() directly and skips
>> dev_xdp_attach(), so the checks in dev_xdp_attach() do not run. A user can
>> make an XDP link with a normal program and then swap in an offloaded or
>> device-bound program with BPF_LINK_UPDATE, which puts it on the software
>> path.
>>
>> Move the three program checks (offloaded, bound to another device, and
>> device-bound in generic mode) from dev_xdp_attach() into
>> dev_xdp_install(), so both the attach path and the link update path are
>> covered.
> Shouldn't we move all the checks that are not explicitly about the
> netlink API (so all but the first?)
Sounds great, the code would be much cleaner.
>
> It may be better to split the series and send this patch to net,
> the netdev CI has a netdevsim test for the prog offload, would be
> good to run that.
Though for now bpf_xdp_link_update() already does:
if (old_prog->type != new_prog->type ||
old_prog->expected_attach_type != new_prog->expected_attach_type) {
err = -EINVAL;
goto out_unlock;
}
so the other checks can't be triggered on the update path even without
them in dev_xdp_install().
So I'm thinking this patch works as a standalone fix (good for
backport), and the cleanup goes as a followup (if necessary)?
next prev parent reply other threads:[~2026-08-11 3:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-10 5:05 [PATCH bpf-next v4 0/3] bpf: prevent offloaded programs from running on host via tcx/netkit Jiayuan Chen
2026-08-10 5:05 ` [PATCH bpf-next v4 1/3] bpf, tcx, netkit: reject offloaded programs Jiayuan Chen
2026-08-10 5:06 ` [PATCH bpf-next v4 2/3] bpf, xdp: move offload check into dev_xdp_install() Jiayuan Chen
2026-08-10 18:49 ` Jakub Kicinski
2026-08-11 3:06 ` Jiayuan Chen [this message]
2026-08-10 5:06 ` [PATCH bpf-next v4 3/3] selftests/bpf: xdp: test dev_xdp_install() rejects device-bound program Jiayuan Chen
2026-08-10 5:23 ` sashiko-bot
2026-08-10 6:30 ` bot+bpf-ci
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