linux-kernel - Re: [PATCH RFC 1/4] bpf: add cgroup device guard to flag a cgroup device prog

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Message-ID: <20230911-leerstand-letztendlich-043fab663451@brauner>
Date:   Mon, 11 Sep 2023 14:35:15 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Michael Weiß <michael.weiss@...ec.fraunhofer.de>
Cc:     Alexander Mikhalitsyn <alexander@...alicyn.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        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>,
        Quentin Monnet <quentin@...valent.com>,
        Alexander Viro <viro@...iv.linux.org.uk>, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        gyroidos@...ec.fraunhofer.de, paul@...l-moore.com,
        Miklos Szeredi <miklos@...redi.hu>,
        Amir Goldstein <amir73il@...il.com>
Subject: Re: [PATCH RFC 1/4] bpf: add cgroup device guard to flag a cgroup
 device prog

> So are OK with the checks here?

I'm ok with figuring out whether we can do this nicely, yes.

> > Because right now device access management seems its own form of
> > mandatory access control.
> 
> I'm currently testing an updated version which has incorporated the locking
> changes already mention by Alex and the change which avoids setting SB_I_NODEV
> in fs/super.c.

Not having to hack around SB_I_NODEV would be pretty crucial imho. It's
a core security assumption so we need to integrate with it nicely.