From: Greg KH <gregkh@linuxfoundation.org>
To: James Bottomley <jejb@linux.ibm.com>
Cc: Dov Murik <dovmurik@linux.ibm.com>,
linux-efi@vger.kernel.org, Borislav Petkov <bp@suse.de>,
Ashish Kalra <ashish.kalra@amd.com>,
Brijesh Singh <brijesh.singh@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Ard Biesheuvel <ardb@kernel.org>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Andi Kleen <ak@linux.intel.com>, Andrew Scull <ascull@google.com>,
Dave Hansen <dave.hansen@intel.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Tobin Feldman-Fitzthum <tobin@linux.ibm.com>,
Jim Cadden <jcadden@ibm.com>,
Daniele Buono <dbuono@linux.vnet.ibm.com>,
linux-coco@lists.linux.dev,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/3] efi/libstub: Copy confidential computing secret area
Date: Wed, 20 Oct 2021 14:11:46 +0200 [thread overview]
Message-ID: <YXAHgkcfwSCBeCbh@kroah.com> (raw)
In-Reply-To: <fb309e2686ca42df2c053cc1b060b1bc774fd3e7.camel@linux.ibm.com>
On Wed, Oct 20, 2021 at 08:00:28AM -0400, James Bottomley wrote:
> On Wed, 2021-10-20 at 08:39 +0200, Greg KH wrote:
> > On Wed, Oct 20, 2021 at 06:14:06AM +0000, Dov Murik wrote:
> [...]
> > > + help
> > > + Copy memory reserved by EFI for Confidential Computing (coco)
> > > + injected secrets, if EFI exposes such a table entry.
> >
> > Why would you want to "copy" secret memory?
> >
> > This sounds really odd here, it sounds like you are opening up a
> > security hole. Are you sure this is the correct text that everyone
> > on the "COCO" group agrees with?
>
> The way this works is that EFI covers the secret area with a boot time
> handoff block, which means it gets destroyed as soon as
> ExitBootServices is called as a security measure ... if you do nothing
> the secret is shredded. This means you need to make a copy of it
> before that happens if there are secrets that need to live beyond the
> EFI boot stub.
Ok, but "copy secrets" does sound really odd, so you all need a much
better description here, and hopefully somewhere else in Documentation/
to describe exactly what this new API is and is to be used for.
Otherwise I read this as "hey a backdoor to read the secrets I wasn't
supposed to be able to see!"
thanks,
greg k-h
next prev parent reply other threads:[~2021-10-20 12:11 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-20 6:14 [PATCH v4 0/3] Allow guest access to EFI confidential computing secret area Dov Murik
2021-10-20 6:14 ` [PATCH v4 1/3] efi/libstub: Copy " Dov Murik
2021-10-20 6:39 ` Greg KH
2021-10-20 7:02 ` Ard Biesheuvel
2021-10-20 8:02 ` Dov Murik
2021-10-20 12:00 ` James Bottomley
2021-10-20 12:11 ` Greg KH [this message]
2021-10-20 12:52 ` Dov Murik
2021-10-20 13:59 ` Greg KH
2021-10-20 6:14 ` [PATCH v4 2/3] efi: Reserve " Dov Murik
2021-10-20 6:40 ` Greg KH
2021-10-20 8:19 ` Dov Murik
2021-10-20 6:14 ` [PATCH v4 3/3] virt: Add efi_secret module to expose confidential computing secrets Dov Murik
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