From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: David Howells <dhowells@redhat.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
James Morris <jmorris@namei.org>,
One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
Matthew Garrett <mjg59@google.com>,
Greg KH <gregkh@linuxfoundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Justin Forbes <jforbes@redhat.com>,
linux-man <linux-man@vger.kernel.org>, joeyli <jlee@suse.com>,
LSM List <linux-security-module@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
linux-efi <linux-efi@vger.kernel.org>
Subject: Re: [GIT PULL] Kernel lockdown for secure boot
Date: Tue, 3 Apr 2018 19:34:25 -0700 [thread overview]
Message-ID: <CAADnVQLu5EZLJ1C9-dd4=K+sed6+38oy047+nqCMfuPFB=wttw@mail.gmail.com> (raw)
On Tue, Apr 3, 2018 at 9:26 AM, Andy Lutomirski <luto@kernel.org> wrote:
> On Tue, Apr 3, 2018 at 8:41 AM, Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
>> On Tue, Apr 03, 2018 at 08:11:07AM -0700, Andy Lutomirski wrote:
>>> >
>>> >> "bpf: Restrict kernel image access functions when the kernel is locked down":
>>> >> This patch just sucks in general.
>>> >
>>> > Yes - but that's what Alexei Starovoitov specified. bpf kind of sucks since
>>> > it gives you unrestricted access to the kernel.
>>>
>>> bpf, in certain contexts, gives you unrestricted access to *reading*
>>> kernel memory. bpf should, under no circumstances, let you write to
>>> the kernel unless you're using fault injection or similar.
>>>
>>> I'm surprised that Alexei acked this patch. If something like XDP or
>>> bpfilter starts becoming widely used, this patch will require a lot of
>>> reworking to avoid breaking standard distros.
>>
>> my understanding was that this lockdown set attemps to disallow _reads_
>> of kernel memory from anything, so first version of patch was adding
>> run-time checks for bpf_probe_read() which is no-go
>> and without this helper the bpf for tracing is losing a lot of its power,
>> so the easiest is to disable it all.
>
> Fair enough.
Actually looking at the patch again:
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?h=efi-lock-down&id=78bb0059c3b8304a8d124b55feebc780fb3e0500
If the only thing that folks are paranoid about is reading
arbitrary kernel memory with bpf_probe_read() helper
then preferred patch would be to disable it during verification
when in lockdown mode.
No run-time overhead and android folks will be happy
that lockdown doesn't break their work.
They converted out-of-tree networking accounting
module and corresponding user daemon to use bpf:
https://www.linuxplumbersconf.org/2017/ocw/system/presentations/4791/original/eBPF%20cgroup%20filters%20for%20data%20usage%20accounting%20on%20Android.pdf
next reply other threads:[~2018-04-04 2:34 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-04 2:34 Alexei Starovoitov [this message]
2018-04-04 4:31 ` [GIT PULL] Kernel lockdown for secure boot Matthew Garrett
2018-04-08 7:44 ` joeyli
2018-04-08 8:07 ` joeyli
2018-04-09 3:40 ` Alexei Starovoitov
2018-04-09 8:14 ` Daniel Borkmann
2018-04-09 13:55 ` joeyli
-- strict thread matches above, loose matches on Subject: below --
2018-03-30 23:29 David Howells
2018-03-31 0:46 ` James Morris
2018-04-03 0:37 ` Andy Lutomirski
2018-04-03 0:59 ` Kees Cook
2018-04-03 1:47 ` Andy Lutomirski
2018-04-03 7:06 ` David Howells
2018-04-03 15:11 ` Andy Lutomirski
2018-04-03 15:41 ` Alexei Starovoitov
2018-04-03 16:26 ` Andy Lutomirski
2018-04-03 16:29 ` Matthew Garrett
2018-04-03 16:45 ` Andy Lutomirski
2018-04-03 18:45 ` Kees Cook
2018-04-03 19:01 ` Andy Lutomirski
2018-04-03 19:07 ` Kees Cook
2018-04-03 19:29 ` Matthew Garrett
2018-04-03 21:51 ` Andy Lutomirski
2018-04-04 18:42 ` Peter Jones
2018-04-04 20:01 ` Thomas Gleixner
2018-04-04 20:18 ` Matthew Garrett
2018-04-05 18:47 ` Andy Lutomirski
2018-04-06 4:42 ` Peter Dolding
2018-04-03 17:16 ` David Howells
2018-04-03 19:01 ` Andy Lutomirski
2018-04-03 19:49 ` David Howells
2018-04-03 21:58 ` Andy Lutomirski
2018-04-03 22:32 ` David Howells
2018-04-03 22:39 ` Andy Lutomirski
2018-04-03 22:46 ` Linus Torvalds
2018-04-03 22:51 ` Matthew Garrett
2018-04-03 22:53 ` Andy Lutomirski
2018-04-03 23:08 ` Justin Forbes
2018-04-03 23:09 ` Matthew Garrett
2018-04-03 23:08 ` Linus Torvalds
2018-04-03 23:10 ` Linus Torvalds
2018-04-03 23:17 ` Matthew Garrett
2018-04-03 23:26 ` Linus Torvalds
2018-04-03 23:39 ` Linus Torvalds
2018-04-03 23:47 ` Matthew Garrett
2018-04-04 0:02 ` Linus Torvalds
2018-04-04 0:04 ` Matthew Garrett
2018-04-04 0:08 ` Linus Torvalds
2018-04-04 0:12 ` Matthew Garrett
2018-04-05 14:58 ` Alan Cox
2018-04-04 0:22 ` David Howells
2018-04-05 17:59 ` Alan Cox
2018-04-05 18:03 ` Matthew Garrett
2018-04-03 23:45 ` Matthew Garrett
2018-04-03 23:55 ` Linus Torvalds
2018-04-03 23:59 ` Matthew Garrett
2018-04-04 0:06 ` Linus Torvalds
2018-04-04 0:10 ` Matthew Garrett
2018-04-04 0:15 ` Linus Torvalds
2018-04-04 0:16 ` Matthew Garrett
2018-04-04 0:18 ` Andy Lutomirski
2018-04-04 0:19 ` Matthew Garrett
2018-04-04 9:04 ` Greg Kroah-Hartman
2018-04-04 0:25 ` Linus Torvalds
2018-04-04 0:33 ` Linus Torvalds
2018-04-04 0:46 ` Matthew Garrett
2018-04-04 0:56 ` Linus Torvalds
2018-04-04 1:13 ` Matthew Garrett
2018-04-04 1:43 ` Linus Torvalds
2018-04-04 4:30 ` Matthew Garrett
2018-04-04 12:57 ` Theodore Y. Ts'o
2018-04-04 13:02 ` Greg Kroah-Hartman
2018-04-04 13:34 ` Theodore Y. Ts'o
2018-04-04 13:57 ` Greg Kroah-Hartman
2018-04-04 13:29 ` Mike Galbraith
2018-04-04 16:20 ` Matthew Garrett
2018-04-08 22:00 ` Pavel Machek
2018-04-04 13:33 ` David Howells
2018-04-04 13:52 ` Theodore Y. Ts'o
2018-04-04 16:22 ` Matthew Garrett
2018-04-04 16:39 ` Andy Lutomirski
2018-04-04 16:42 ` Matthew Garrett
2018-04-04 16:46 ` Justin Forbes
2018-04-05 0:05 ` Peter Dolding
2018-04-05 0:20 ` Matthew Garrett
2018-04-04 13:57 ` David Howells
2018-04-04 16:09 ` Linus Torvalds
2018-04-04 16:17 ` Matthew Garrett
2018-04-04 6:56 ` Peter Dolding
2018-04-04 16:26 ` Matthew Garrett
2018-04-05 1:28 ` Peter Dolding
2018-04-04 1:30 ` Justin Forbes
2018-04-04 1:58 ` Linus Torvalds
2018-04-04 1:36 ` Justin Forbes
2018-04-04 0:17 ` Jann Horn
2018-04-04 0:23 ` Andy Lutomirski
2018-04-04 8:05 ` David Howells
2018-04-04 14:35 ` Andy Lutomirski
2018-04-04 14:44 ` David Howells
2018-04-04 15:43 ` Eric W. Biederman
2018-04-03 23:56 ` David Howells
2018-04-03 23:58 ` Linus Torvalds
2018-04-03 23:39 ` David Howells
2018-04-03 23:48 ` Andy Lutomirski
2018-04-08 8:23 ` Pavel Machek
2018-04-03 23:12 ` David Howells
2018-04-03 23:27 ` Linus Torvalds
2018-04-03 23:42 ` Andy Lutomirski
2018-04-03 20:53 ` Linus Torvalds
2018-04-03 20:54 ` Matthew Garrett
2018-04-03 21:01 ` Linus Torvalds
2018-04-03 21:08 ` Matthew Garrett
2018-04-03 21:21 ` Al Viro
2018-04-03 21:37 ` Matthew Garrett
2018-04-03 21:26 ` Linus Torvalds
2018-04-03 21:32 ` Matthew Garrett
2018-04-08 8:10 ` Pavel Machek
2018-03-31 10:20 ` David Howells
2018-04-03 13:25 ` Ard Biesheuvel
2018-04-03 21:48 ` James Morris
2018-04-05 17:53 ` Alan Cox
2017-10-26 16:37 David Howells
2017-10-26 18:22 ` Mimi Zohar
2017-10-26 19:20 ` James Morris
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