From: Greg KH <gregkh@linuxfoundation.org>
To: Dov Murik <dovmurik@linux.ibm.com>
Cc: James Bottomley <jejb@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 15:59:27 +0200 [thread overview]
Message-ID: <YXAgvyZ9ZxPxJ3lp@kroah.com> (raw)
In-Reply-To: <bfa4872d-f64a-0559-1c5d-c5d1ae333eee@linux.ibm.com>
On Wed, Oct 20, 2021 at 03:52:49PM +0300, Dov Murik wrote:
>
>
> On 20/10/2021 15:11, Greg KH wrote:
> > 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.
> >
>
>
> So something like:
>
>
> config EFI_COCO_SECRET
> bool "Keep the EFI Confidential Computing secret area"
> depends on EFI
> help
> Confidential Computing platforms (such as AMD SEV) allow for
> secrets injection during guest VM launch. The secrets are
> placed in a designated EFI memory area. EFI destorys
> the confidential computing secret area when ExitBootServices
> is called.
That last sentence does not make much sense to me, sorry.
> In order to use the secrets in the kernel, the secret area
> must be copied to kernel-reserved memory (before it is erased).
>
> If you say Y here, the EFI stub will copy the EFI secret area (if
> available) and reserve it for use inside the kernel. This will
> allow the virt/coco/efi_secret module to access the secrets.
Really this is about getting that data out to userspace, right? Should
you mention that here?
> and some new file like Documentation/security/coco/efi_secret.rst which
> describes this whole protocol (from secret injection at VM launch
> into an EFI page, through efistub and efi in linux, to the efi_secret
> module which exposes the secrets).
Yes, that would be good to have documented.
thanks,
greg k-h
next prev parent reply other threads:[~2021-10-20 13:59 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
2021-10-20 12:52 ` Dov Murik
2021-10-20 13:59 ` Greg KH [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YXAgvyZ9ZxPxJ3lp@kroah.com \
--to=gregkh@linuxfoundation.org \
--cc=ak@linux.intel.com \
--cc=ardb@kernel.org \
--cc=ascull@google.com \
--cc=ashish.kalra@amd.com \
--cc=bp@suse.de \
--cc=brijesh.singh@amd.com \
--cc=dave.hansen@intel.com \
--cc=dbuono@linux.vnet.ibm.com \
--cc=dgilbert@redhat.com \
--cc=dovmurik@linux.ibm.com \
--cc=jcadden@ibm.com \
--cc=jejb@linux.ibm.com \
--cc=jmorris@namei.org \
--cc=linux-coco@lists.linux.dev \
--cc=linux-efi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=serge@hallyn.com \
--cc=thomas.lendacky@amd.com \
--cc=tobin@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).