From: ebiederm@xmission.com (Eric W. Biederman)
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org
Subject: Re: [PATCH 07/11] kexec: Disable in a secure boot environment
Date: Tue, 04 Sep 2012 14:13:54 -0700 [thread overview]
Message-ID: <87r4qhwkx9.fsf@xmission.com> (raw)
In-Reply-To: <20120904202205.GA28903@srcf.ucam.org> (Matthew Garrett's message of "Tue, 4 Sep 2012 21:22:05 +0100")
Matthew Garrett <mjg59@srcf.ucam.org> writes:
> On Tue, Sep 04, 2012 at 01:13:32PM -0700, Eric W. Biederman wrote:
>>
>> Matthew Garrett <mjg@redhat.com> writes:
>>
>> > kexec could be used as a vector for a malicious user to use a signed kernel
>> > to circumvent the secure boot trust model. In the long run we'll want to
>> > support signed kexec payloads, but for the moment we should just disable
>> > loading entirely in that situation.
>>
>> Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>>
>> This makes no sense. The naming CAP_SECURE_FIRMWARE is attrocious,
>> you aren't implementing or enforcing secure firmware.
>
> I'm certainly not attached to the name, and have no problem replacing
> it.
>
>> You don't give any justification for this other than to support some
>> silly EFI feature. Why would anyone want this if we were not booting
>> under EFI?
>
> Well, given that approximately everyone will be booting under EFI within
> 18 months, treating it as a niche case seems a little short sighted.
If we are all going to be using the code we need to keep the code
quality high.
> And
> secondly, there are already several non-EFI platforms that want to enact
> a policy preventing root from being able to arbitrarily replace the
> kernel. Given that people are doing this in the wild, it makes sense to
> move towards offering that policy in the mainline kernel.
Either this code makes sense without an appeal to EFI or this code makes
no sense.
It is fine for jumping through the EFI trusted boot hoops to be your
motivation, but EFI policy should not be the justification for kernel
implementation details.
There may be some sense to the desired functionality. From what I have
seen of the policies so far I have no respect for the way people are
using EFI secure boot. I have no expectation that EFI secure boot will
stop malware as long as anything signed by microsoft's key is trusted by
the firmware. We have already seen malware in the wild that could be
verified with Microsoft's key.
So please rework this to come from an angle that makes sense all by
itself.
Eric
next prev parent reply other threads:[~2012-09-04 21:14 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-04 15:55 [RFC] First attempt at kernel secure boot support Matthew Garrett
2012-09-04 15:55 ` [PATCH 01/11] Secure boot: Add new capability Matthew Garrett
2012-09-04 15:55 ` [PATCH 02/11] PCI: Lock down BAR access in secure boot environments Matthew Garrett
2012-10-01 21:00 ` Pavel Machek
2012-09-04 15:55 ` [PATCH 03/11] x86: Lock down IO port " Matthew Garrett
2012-09-04 16:16 ` Alan Cox
2012-09-04 16:16 ` Matthew Garrett
2012-09-04 15:55 ` [PATCH 04/11] ACPI: Limit access to custom_method Matthew Garrett
2012-09-04 15:55 ` [PATCH 05/11] asus-wmi: Restrict debugfs interface Matthew Garrett
2012-09-04 16:12 ` Alan Cox
2012-09-04 16:13 ` Matthew Garrett
2012-09-04 15:55 ` [PATCH 06/11] Restrict /dev/mem and /dev/kmem in secure boot setups Matthew Garrett
2012-09-04 15:55 ` [PATCH 07/11] kexec: Disable in a secure boot environment Matthew Garrett
2012-09-04 20:13 ` Eric W. Biederman
2012-09-04 20:22 ` Matthew Garrett
2012-09-04 21:13 ` Eric W. Biederman [this message]
2012-09-04 21:27 ` Matthew Garrett
2012-09-04 22:12 ` Eric W. Biederman
2012-09-04 23:25 ` Matthew Garrett
2012-09-05 4:33 ` Eric W. Biederman
2012-09-05 5:16 ` Matthew Garrett
2012-09-05 7:00 ` Eric W. Biederman
2012-09-05 7:03 ` Matthew Garrett
2012-09-04 21:39 ` Alan Cox
2012-09-04 21:40 ` Matthew Garrett
2012-09-05 15:43 ` Roland Eggner
2012-09-05 15:46 ` Matthew Garrett
2012-09-05 21:13 ` Mimi Zohar
2012-09-05 21:41 ` Matthew Garrett
2012-09-05 21:49 ` Eric Paris
2012-09-04 15:55 ` [PATCH 08/11] Secure boot: Add a dummy kernel parameter that will switch on Secure Boot mode Matthew Garrett
2012-09-04 15:55 ` [PATCH 09/11] efi: Enable secure boot lockdown automatically when enabled in firmware Matthew Garrett
2012-09-04 15:55 ` [PATCH 10/11] acpi: Ignore acpi_rsdp kernel parameter in a secure boot environment Matthew Garrett
2012-09-04 16:30 ` Shuah Khan
2012-09-04 16:38 ` Matthew Garrett
2012-09-04 16:44 ` Shuah Khan
2012-09-04 20:37 ` Alan Cox
2012-09-04 20:37 ` Matthew Garrett
2012-09-04 20:50 ` Josh Boyer
2012-09-04 15:55 ` [PATCH 11/11] SELinux: define mapping for new Secure Boot capability Matthew Garrett
2012-09-04 16:08 ` [RFC] First attempt at kernel secure boot support Alan Cox
2012-09-04 16:12 ` Matthew Garrett
2012-10-01 21:07 ` Pavel Machek
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