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From: "Gerd Hoffmann" <kraxel@redhat.com>
To: James Bottomley <jejb@linux.ibm.com>
Cc: devel@edk2.groups.io, "Jiewen Yao" <jiewen.yao@intel.com>,
	"Erdem Aktas" <erdemaktas@google.com>,
	"Min Xu" <min.m.xu@intel.com>,
	"Tom Lendacky" <thomas.lendacky@amd.com>,
	"Jordan Justen" <jordan.l.justen@intel.com>,
	"Stefan Berger" <stefanb@linux.ibm.com>,
	"Julien Grall" <julien@xen.org>,
	"Anthony Perard" <anthony.perard@citrix.com>,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Ard Biesheuvel" <ardb+tianocore@kernel.org>,
	"Oliver Steffen" <osteffen@redhat.com>,
	"Pawel Polawski" <ppolawsk@redhat.com>,
	"Michael Roth" <michael.roth@amd.com>
Subject: Re: [PATCH 2/3] OvmfPkg/AmdSev: stop using PlatformBootManagerLibGrub
Date: Thu, 4 May 2023 17:08:21 +0200	[thread overview]
Message-ID: <gjhnb2f6plr7mcfropglaqcfiwf7o7g2ody3vt4ksbdwbdsbxm@srtsuf77t6tb> (raw)
In-Reply-To: <b4722568547d54b15de4b592dcbd24755893ef88.camel@linux.ibm.com>

On Thu, May 04, 2023 at 10:16:05AM -0400, James Bottomley wrote:
> On Thu, 2023-05-04 at 15:32 +0200, Gerd Hoffmann wrote:
> > Use PlatformBootManagerLib with PcdBootRestrictToFirmware
> > set to TRUE instead.
> > 
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> > ---
> >  OvmfPkg/AmdSev/AmdSevX64.dsc | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/OvmfPkg/AmdSev/AmdSevX64.dsc
> > b/OvmfPkg/AmdSev/AmdSevX64.dsc
> > index 943c4eed9831..b32049194d39 100644
> > --- a/OvmfPkg/AmdSev/AmdSevX64.dsc
> > +++ b/OvmfPkg/AmdSev/AmdSevX64.dsc
> > @@ -153,6 +153,7 @@ [LibraryClasses]
> >   
> > UefiDriverEntryPoint|MdePkg/Library/UefiDriverEntryPoint/UefiDriverEn
> > tryPoint.inf
> >   
> > UefiApplicationEntryPoint|MdePkg/Library/UefiApplicationEntryPoint/Ue
> > fiApplicationEntryPoint.inf
> >   
> > DevicePathLib|MdePkg/Library/UefiDevicePathLibDevicePathProtocol/Uefi
> > DevicePathLibDevicePathProtocol.inf
> > +  NvVarsFileLib|OvmfPkg/Library/NvVarsFileLib/NvVarsFileLib.inf
> 
> All additions apart from this look fine, but this one is a security
> risk: EFI variables represent an unmeasured configuration for SEV boot
> and, as such, can be used to influence the boot and potentially reveal
> boot secrets, so the AmdSevPkg was designed to have read only EFI
> variables that couldn't be subject to outside influence.

NvVarsFileLib gets disabled already case PcdSecureBootSupported is set.
Is that good enough?  If not I can extend that to also check
PcdBootRestrictToFirmware.

take care,
  Gerd


  reply	other threads:[~2023-05-04 15:08 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-04 13:32 [PATCH 0/3] OvmfPkg: remove PlatformBootManagerLibGrub Gerd Hoffmann
2023-05-04 13:32 ` [PATCH 1/3] OvmfPkg/PlatformBootManagerLib: add PcdBootRestrictToFirmware Gerd Hoffmann
2023-05-04 13:32 ` [PATCH 2/3] OvmfPkg/AmdSev: stop using PlatformBootManagerLibGrub Gerd Hoffmann
2023-05-04 14:16   ` James Bottomley
2023-05-04 15:08     ` Gerd Hoffmann [this message]
2023-05-04 15:14       ` [edk2-devel] " James Bottomley
2023-05-04 13:32 ` [PATCH 3/3] OvmfPkg: drop PlatformBootManagerLibGrub Gerd Hoffmann
2023-05-04 13:44 ` [PATCH 0/3] OvmfPkg: remove PlatformBootManagerLibGrub Yao, Jiewen
2023-05-04 14:02 ` Ard Biesheuvel

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