From: "Toke Høiland-Jørgensen" <toke@kernel•org>
To: shaozhengchao <shaozhengchao@huawei•com>,
"bpf@vger•kernel.org" <bpf@vger•kernel.org>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>,
"ast@kernel•org" <ast@kernel•org>,
"daniel@iogearbox•net" <daniel@iogearbox•net>,
"davem@davemloft•net" <davem@davemloft•net>,
"kuba@kernel•org" <kuba@kernel•org>,
"hawk@kernel•org" <hawk@kernel•org>,
"john.fastabend@gmail•com" <john.fastabend@gmail•com>,
"andrii@kernel•org" <andrii@kernel•org>,
"kafai@fb•com" <kafai@fb•com>,
"songliubraving@fb•com" <songliubraving@fb•com>,
"yhs@fb•com" <yhs@fb•com>,
"kpsingh@kernel•org" <kpsingh@kernel•org>
Cc: "weiyongjun (A)" <weiyongjun1@huawei•com>,
yuehaibing <yuehaibing@huawei•com>
Subject: Re: 答复: [PATCH bpf-next] samples/bpf: check detach prog exist or not in xdp_fwd
Date: Mon, 09 May 2022 12:55:29 +0200 [thread overview]
Message-ID: <87h75zynz2.fsf@toke.dk> (raw)
In-Reply-To: <f9c85578b94a4a38b3f7b9c796810a30@huawei.com>
shaozhengchao <shaozhengchao@huawei•com> writes:
> -----邮件原件-----
> 发件人: Toke Høiland-Jørgensen [mailto:toke@kernel•org]
> 发送时间: 2022年5月9日 17:46
> 收件人: shaozhengchao <shaozhengchao@huawei•com>; bpf@vger•kernel.org; netdev@vger•kernel.org; linux-kernel@vger•kernel.org; ast@kernel•org; daniel@iogearbox•net; davem@davemloft•net; kuba@kernel•org; hawk@kernel•org; john.fastabend@gmail•com; andrii@kernel•org; kafai@fb•com; songliubraving@fb•com; yhs@fb•com; kpsingh@kernel•org
> 抄送: weiyongjun (A) <weiyongjun1@huawei•com>; shaozhengchao <shaozhengchao@huawei•com>; yuehaibing <yuehaibing@huawei•com>
> 主题: Re: [PATCH bpf-next] samples/bpf: check detach prog exist or not in xdp_fwd
>
> Zhengchao Shao <shaozhengchao@huawei•com> writes:
>
>> Before detach the prog, we should check detach prog exist or not.
>
> If we're adding such a check we should also check that it's the *right* program. I.e., query the ID for the program name and check that it matches what the program attached, then obtain an fd and pass that as XDP_EXPECTED_FD on detach to make sure it wasn't swapped out in the meantime...
>
> -Toke
>
> Thank you for your reply. When finish running xdp_fwd to attatch prog,
> the program will exit and can't store fd as XDP_EXPECTED_FD.
>
> I think the sample xdp_fwd -d is just detach prog and don't care if
> the fd is expected.
So why are you adding the check? Either keep it the way it is, or add a
proper check that examines the program type; you're right that it
doesn't store the prog FD, but you can still check the program name and
see if it matches to get some idea that it's not a totally separate
program that's loaded. I think doing so would be an improvement to the
sample, but just adding a check if a program is loaded is not, really...
-Toke
next prev parent reply other threads:[~2022-05-09 10:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-09 0:51 [PATCH bpf-next] samples/bpf: check detach prog exist or not in xdp_fwd Zhengchao Shao
2022-05-09 9:46 ` Toke Høiland-Jørgensen
2022-05-09 10:27 ` 答复: " shaozhengchao
2022-05-09 10:55 ` Toke Høiland-Jørgensen [this message]
2022-05-17 2:00 ` 答复: " shaozhengchao
2022-05-17 9:42 ` Toke Høiland-Jørgensen
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