From: Andy Lutomirski <luto@amacapital.net>
To: jwboyer@gmail.com
Cc: Matthew Garrett <mjg@redhat.com>,
Kees Cook <keescook@chromium.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
x86@kernel.org, linux-efi@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot
Date: Fri, 08 Feb 2013 15:09:19 -0800 [thread overview]
Message-ID: <5115859F.8070805@amacapital.net> (raw)
In-Reply-To: <CA+5PVA4EbgBRgg+ZDa4+vG0Ngw8wJ3kH6NcmDvZ=+CP=kH82_A@mail.gmail.com>
On 02/08/2013 01:14 PM, Josh Boyer wrote:
> On Fri, Feb 8, 2013 at 4:07 PM, Matthew Garrett
> <matthew.garrett-05XSO3Yj/JvQT0dZR+AlfA@public.gmane.org> wrote:
>> On Fri, 2013-02-08 at 13:02 -0800, Kees Cook wrote:
>>
>>> I don't find it unreasonable to drop all caps and lose access to
>>> sensitive things. :) That's sort of the point, really. I think a cap
>>> is the best match. It seems like it should either be a cap or a
>>> namespace flag, but the latter seems messy.
>>
>> Yeah, I think it's an expected outcome, but it means that if (say) qemu
>> drops privileges, qemu can no longer access PCI resources - even on
>> non-secure boot systems. That breaks existing userspace.
>
> Right. We've had a few reports in Fedora of things breaking on non-SB
> systems because of this. The qemu one is the latest, but the general
> problem is people think dropping all caps blindly is making their apps
> safer. Then they find they can't do things they could do before the new
> cap was added. It's messy.
Why not require CAP_COMPROMISE_KERNEL to open (with O_RDWR or O_WRONLY)
/dev/msr? After all, sudo </dev/null >/dev/msr will cause a privileged
write() call on the fd as long as the capability is in your bounding set.
--Andy
next prev parent reply other threads:[~2013-02-08 23:09 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-08 19:12 [PATCH] x86: Lock down MSR writing in secure boot Kees Cook
2013-02-08 19:17 ` H. Peter Anvin
2013-02-08 19:18 ` Kees Cook
2013-02-08 19:42 ` H. Peter Anvin
2013-02-08 20:14 ` Kees Cook
2013-02-08 20:18 ` H. Peter Anvin
2013-02-08 20:28 ` Kees Cook
2013-02-08 20:34 ` Matthew Garrett
2013-02-08 21:02 ` Kees Cook
2013-02-08 21:07 ` Matthew Garrett
2013-02-08 21:14 ` Josh Boyer
2013-02-08 23:09 ` Andy Lutomirski [this message]
2013-02-08 22:30 ` H. Peter Anvin
2013-02-08 23:06 ` Borislav Petkov
2013-02-08 23:26 ` Matthew Garrett
2013-02-09 1:22 ` H. Peter Anvin
2013-02-09 1:29 ` Matthew Garrett
2013-02-09 6:45 ` Kees Cook
2013-02-09 9:29 ` Borislav Petkov
2013-02-09 15:10 ` Kees Cook
2013-02-09 15:11 ` Matthew Garrett
2013-02-13 0:48 ` H. Peter Anvin
2013-02-13 5:39 ` Matthew Garrett
2013-02-13 6:12 ` H. Peter Anvin
2013-02-13 6:27 ` Matthew Garrett
2013-02-13 6:33 ` H. Peter Anvin
2013-02-13 6:41 ` Matthew Garrett
2013-02-13 17:20 ` H. Peter Anvin
2013-02-13 17:26 ` Matthew Garrett
2013-02-13 17:51 ` Casey Schaufler
2013-02-13 17:56 ` Matthew Garrett
2013-02-13 18:44 ` H. Peter Anvin
2013-02-13 18:51 ` Matthew Garrett
2013-02-13 22:26 ` H. Peter Anvin
2013-02-13 22:58 ` Casey Schaufler
2013-02-14 0:25 ` H. Peter Anvin
2013-02-14 0:44 ` Casey Schaufler
2013-02-14 1:04 ` Matthew Garrett
2013-02-14 1:08 ` H. Peter Anvin
2013-02-14 2:46 ` Matthew Garrett
2013-02-14 1:34 ` Casey Schaufler
2013-02-13 8:27 ` Paolo Bonzini
2013-02-13 17:21 ` H. Peter Anvin
2013-02-13 17:22 ` H. Peter Anvin
2013-02-13 19:55 ` Paolo Bonzini
2013-02-13 22:24 ` H. Peter Anvin
2013-02-08 19:17 ` Matthew Garrett
2013-02-08 19:21 ` Kees Cook
2013-02-08 19:27 ` Matthew Garrett
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