linux-kernel - Re: [PATCH] device_cgroup: Cleanup cgroup eBPF device filter code

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Message-ID: <4264eb59-920e-20da-a256-23b6f0bbc95e@iogearbox.net>
Date:   Mon, 6 Apr 2020 22:30:49 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Roman Gushchin <guro@...com>, Odin Ugedal <odin@...dal.com>
Cc:     bpf@...r.kernel.org, linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, tj@...nel.org,
        Harish.Kasiviswanathan@....com, amd-gfx@...ts.freedesktop.org
Subject: Re: [PATCH] device_cgroup: Cleanup cgroup eBPF device filter code

On 4/4/20 12:37 AM, Roman Gushchin wrote:
> On Fri, Apr 03, 2020 at 07:55:28PM +0200, Odin Ugedal wrote:
>> Original cgroup v2 eBPF code for filtering device access made it
>> possible to compile with CONFIG_CGROUP_DEVICE=n and still use the eBPF
>> filtering. Change
>> commit 4b7d4d453fc4 ("device_cgroup: Export devcgroup_check_permission")
>> reverted this, making it required to set it to y.
>>
>> Since the device filtering (and all the docs) for cgroup v2 is no longer
>> a "device controller" like it was in v1, someone might compile their
>> kernel with CONFIG_CGROUP_DEVICE=n. Then (for linux 5.5+) the eBPF
>> filter will not be invoked, and all processes will be allowed access
>> to all devices, no matter what the eBPF filter says.
>>
>> Signed-off-by: Odin Ugedal <odin@...dal.com>
> 
> The patch makes perfect sense to me.
> 
> Acked-by: Roman Gushchin <guro@...com>

Tejun, I presume you'll pick this up (given the files this fix touches)?

Thanks,
Daniel