linux-kernel - Re: [PATCH v6 bpf 0/4] lwt: fix return values of BPF ops

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Message-ID: <61e79414-9290-736f-6a50-dfe1585dc2a7@iogearbox.net>
Date:   Fri, 18 Aug 2023 18:08:34 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Yan Zhai <yan@...udflare.com>
Cc:     bpf@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        David Ahern <dsahern@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>,
        Thomas Graf <tgraf@...g.ch>,
        Jordan Griege <jgriege@...udflare.com>,
        Dan Carpenter <dan.carpenter@...aro.org>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v6 bpf 0/4] lwt: fix return values of BPF ops

On 8/18/23 6:01 PM, Yan Zhai wrote:
> On Fri, Aug 18, 2023 at 9:55 AM Daniel Borkmann <daniel@...earbox.net> wrote:
>>
>> On 8/18/23 4:58 AM, Yan Zhai wrote:
>>> lwt xmit hook does not expect positive return values in function
>>> ip_finish_output2 and ip6_finish_output. However, BPF programs can
>>> directly return positive statuses such like NET_XMIT_DROP, NET_RX_DROP,
>>> and etc to the caller. Such return values would make the kernel continue
>>> processing already freed skbs and eventually panic.
>>>
>>> This set fixes the return values from BPF ops to unexpected continue
>>> processing, checks strictly on the correct continue condition for
>>> future proof. In addition, add missing selftests for BPF redirect
>>> and reroute cases for BPF-CI.
>>>
>>> v5: https://lore.kernel.org/bpf/cover.1692153515.git.yan@cloudflare.com/
>>> v4: https://lore.kernel.org/bpf/ZMD1sFTW8SFiex+x@debian.debian/T/
>>> v3: https://lore.kernel.org/bpf/cover.1690255889.git.yan@cloudflare.com/
>>> v2: https://lore.kernel.org/netdev/ZLdY6JkWRccunvu0@debian.debian/
>>> v1: https://lore.kernel.org/bpf/ZLbYdpWC8zt9EJtq@debian.debian/
>>>
>>> changes since v5:
>>>    * fix BPF-CI failures due to missing config and busybox ping issue
>>
>> Series looks good, thanks! Given we're fairly close to merge window and
>> this has been broken for quite some time, I took this into bpf-next.
>>
> Thanks Daniel! Can you also queue this up for stable (or guide how I can do it)?

Given the Fixes tags, it will be picked up automatically once it lands in
Linus' tree.

Thanks,
Daniel