netdev - Re: [PATCH 18/27] bpf: Restrict kernel image access functions when the kernel is locked down

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Date:   Mon, 23 Oct 2017 15:53:00 +0100
From:   David Howells <dhowells@...hat.com>
To:     jlee@...e.com
Cc:     dhowells@...hat.com,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        linux-security-module@...r.kernel.org, gnomes@...rguk.ukuu.org.uk,
        linux-efi@...r.kernel.org, matthew.garrett@...ula.com,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        jforbes@...hat.com, Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Gary Lin <GLin@...e.com>
Subject: Re: [PATCH 18/27] bpf: Restrict kernel image access functions when the kernel is locked down

jlee@...e.com wrote:

> hm... patch 4 only prevents write_mem() but not read_mem().
> Or I missed anything?

Actually, yes, as it happens, patch 11 prevents you from even opening /dev/mem
and /dev/kmem by locking down open of /dev/port.  So I've moved this bit to
patch 4, simplified and posted a new variant for patch 4.

David