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From:   Djalal Harouni <tixxdz@gmail.com>
Date:   Mon, 4 Apr 2022 09:44:59 +0200
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Subject: Re: [PATCH 00/18] bpf: Secure and authenticated preloading of eBPF programs
To:     KP Singh <kpsingh@kernel.org>
Cc:     Alexei Starovoitov <alexei.starovoitov@gmail.com>,
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On Sun, Apr 3, 2022 at 5:42 PM KP Singh <kpsingh@kernel.org> wrote:
>
> On Sat, Apr 2, 2022 at 1:55 AM Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
...
> >
> > > Pinning
> > > them to unreachable inodes intuitively looked the
> > > way to go for achieving the stated goal.
> >
> > We can consider inodes in bpffs that are not unlinkable by root
> > in the future, but certainly not for this use case.
>
> Can this not be already done by adding a BPF_LSM program to the
> inode_unlink LSM hook?
>

Also, beside of the inode_unlink... and out of curiosity: making sysfs/bpffs/
readonly after pinning, then using bpf LSM hooks sb_mount|remount|unmount...
family combining bpf() LSM hook... isn't this enough to:
1. Restrict who can pin to bpffs without using a full MAC
2. Restrict who can delete or unmount bpf filesystem

?

-- 
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