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From: "Lorenz Bauer" <oss@lmb.io>
To: shaozhengchao <shaozhengchao@huawei.com>,
	"Stanislav Fomichev" <sdf@google.com>
Cc: "Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	yuehaibing@huawei.com
Subject: Re: [PATCH v4,bpf-next] bpf: Don't redirect packets with invalid pkt_len
Date: Fri, 14 Oct 2022 17:29:41 +0100	[thread overview]
Message-ID: <04d2eb4a-7365-495a-ab74-704febac2789@app.fastmail.com> (raw)
In-Reply-To: <cf6a99a1-e77f-113d-101a-5b5a52111df5@huawei.com>

On Thu, 13 Oct 2022, at 11:44, shaozhengchao wrote:
> 	Sorry, I haven't fully understood your intentions yet.
> Can you explain it more detail?

I'll try! Roughly, we do the following:

1. Create a BPF_PROG_TYPE_SOCKET_FILTER program that just returns 0
2. Load the program into the kernel
3. Call BPF_PROG_RUN with data_size_in == 14

After your bugfix, it seems like step 3 is rejected due to data_size_in == 14. We had to increase data_size_in to 15 to
avoid this, see [0].

This breaks user space, so it would be great if you could fix this in a way that doesn't refuse BPF_PROG_RUN with
data_size_in == 14. Since I don't understand the original problem very well I can't tell you what the best fix is however.

0: https://github.com/cilium/ebpf/commit/a38fb6b5a46ab3b5639ea4d421232a10013596c0

Thanks
Lorenz

  reply	other threads:[~2022-10-14 16:30 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-15 11:55 [PATCH v4,bpf-next] bpf: Don't redirect packets with invalid pkt_len Zhengchao Shao
2022-07-15 23:30 ` Stanislav Fomichev
2022-07-19 17:00 ` patchwork-bot+netdevbpf
2022-09-14 11:19 ` Lorenz Bauer
2022-09-17 15:46   ` Stanislav Fomichev
2022-09-19 10:55     ` shaozhengchao
2022-09-20 14:42       ` Lorenz Bauer
2022-09-21  8:48         ` shaozhengchao
2022-09-21 20:59           ` Stanislav Fomichev
2022-10-13  9:36           ` Lorenz Bauer
2022-10-13 10:44             ` shaozhengchao
2022-10-14 16:29               ` Lorenz Bauer [this message]
2022-10-14 16:55                 ` sdf
2022-10-15  2:36                   ` shaozhengchao
2022-11-03 21:07 ` Martin KaFai Lau
2022-11-03 21:36   ` Stanislav Fomichev
2022-11-03 22:42     ` Martin KaFai Lau
2022-11-03 22:58       ` Stanislav Fomichev
2022-11-09 21:43         ` Stanislav Fomichev

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