linux-kernel - Re: [PATCH v3 bpf-next 0/6] Enable writing xattr from BPF programs

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Message-ID: <20241211131804.GA1912640@mit.edu>
Date: Wed, 11 Dec 2024 08:18:04 -0500
From: "Theodore Ts'o" <tytso@....edu>
To: Song Liu <song@...nel.org>
Cc: bpf@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org,
        kernel-team@...a.com, andrii@...nel.org, eddyz87@...il.com,
        ast@...nel.org, daniel@...earbox.net, martin.lau@...ux.dev,
        viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
        kpsingh@...nel.org, mattbobrowski@...gle.com, liamwisehart@...a.com,
        shankaran@...a.com
Subject: Re: [PATCH v3 bpf-next 0/6] Enable writing xattr from BPF programs

On Tue, Dec 10, 2024 at 02:06:21PM -0800, Song Liu wrote:
> Add support to set and remove xattr from BPF program. Also add
> security.bpf. xattr name prefix.

If the system allows for the execution of unprivileged BPF programs
(e.g., ones where a random user can load their own BPF programs), will
they have hte ability to set and remove security.bpf.* xattrs?  If the
answer is yes, should this be disallowed?

I note that one of the use cases seems to be BPF-based LSM's, so we
may want to have something even more restrictive since otherwise any
BPF program could potentially have the same power as the LSM?

    	    	  	      	       	    - Ted