linux-kernel - Re: [PATCH V31 22/25] bpf: Restrict bpf when kernel lockdown is in confidentiality mode

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Message-ID: <CALCETrUtYir8bCCMMH2kEAEmWBB_h4tL_9fq0zgNwRNXmZfG6A@mail.gmail.com>
Date:   Tue, 26 Mar 2019 12:21:24 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Matthew Garrett <matthewgarrett@...gle.com>
Cc:     James Morris <jmorris@...ei.org>,
        LSM List <linux-security-module@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        David Howells <dhowells@...hat.com>,
        Linux API <linux-api@...r.kernel.org>,
        Andrew Lutomirski <luto@...nel.org>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Matthew Garrett <mjg59@...gle.com>,
        Network Development <netdev@...r.kernel.org>,
        Chun-Yi Lee <jlee@...e.com>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH V31 22/25] bpf: Restrict bpf when kernel lockdown is in
 confidentiality mode

On Tue, Mar 26, 2019 at 11:28 AM Matthew Garrett
<matthewgarrett@...gle.com> wrote:
>
> From: David Howells <dhowells@...hat.com>
>
> There are some bpf functions can be used to read kernel memory:
> bpf_probe_read, bpf_probe_write_user and bpf_trace_printk.  These allow
> private keys in kernel memory (e.g. the hibernation image signing key) to
> be read by an eBPF program and kernel memory to be altered without
> restriction. Disable them if the kernel has been locked down in
> confidentiality mode.
>

:)

This is yet another reason to get the new improved bpf_probe_user_read
stuff landed!