I brought the RFC into the CCC community
(https://github.com/confidential-computing/governance) and received
some comments.
Forward the email into the EDK2 dev and linux-coco.
Thanks,
Qinkun
---------- Forwarded message ---------
From: Mingshen Sun <mingshen....@tiktok.com>
Date: Thu, Apr 4, 2024 at 1:43 PM
Subject: Re: [External] Re: [linux-collab] [CCC][tac] [RFC PATCH]
OvmfPkg/SecurityPkg: Add build option for coexistance of vTPM and
RTMR.
To: <qin...@google.com>
Cc: <t...@lists.confidentialcomputing.io>,
<linux-col...@lists.confidentialcomputing.io>
Hi Qinkun,
Thanks for bringing this to the CCC community.
I think the proposal makes sense to me. RTMR and vTPM measurements
shouldn't be mutually exclusive.
Under certain threat models (e.g., workload operator is not trusted),
both of them may be valid.
1. Measurements of RTMR and vTPM can be used for cross validation with
different root-of-trust.
2. Key sealing feature provided by vTPM is not available in the
current TEE ecosystem.
Mingshen
On Thu, Apr 4, 2024 at 12:32 PM qinkun Bao via
lists.confidentialcomputing.io
<qinkun=google....@lists.confidentialcomputing.io> wrote:
>
> Hello,
>
> The current TDVF implementation does not extend to the vTPM if the
> RTMR attestation is enabled. We are working on proposals to address
> the issue. We would like to get the feedback from the CCC community
> about the proposal.
>
> Thanks,
> Qinkun
>
> On Thu, Apr 4, 2024 at 12:16 PM qinkun Bao via
> lists.confidentialcomputing.io
> <qinkun=google....@lists.confidentialcomputing.io> wrote:
> >
> >
> >
> > ---------- Forwarded message ---------
> > From: qinkun Bao <qin...@google.com>
> > Date: Thu, Mar 21, 2024 at 9:59 AM
> > Subject: [RFC PATCH] OvmfPkg/SecurityPkg: Add build option for coexistance
> > of vTPM and RTMR.
> > To: <devel@edk2.groups.io>
> > Cc: <linux-c...@lists.linux.dev>, Erdem Aktas <erdemak...@google.com>,
> > Jiewen Yao <jiewen....@intel.com>, Ard Biesheuvel <a...@kernel.org>, Peter
> > Gonda <pgo...@google.com>, Dionna Glaze <dionnagl...@google.com>, Qinkun
> > Bao <qin...@google.com>, James Bottomley <j...@linux.ibm.com>, Gerd
> > Hoffmann <kra...@redhat.com>, Tom Lendacky <thomas.lenda...@amd.com>,
> > Michael Roth <michael.r...@amd.com>
> >
> >
> > From: Qinkun Bao <qin...@google.com>
> >
> > The UEFI v2.10 spec defines the protocol EFI_CC_MEASUREMENT_PROTOCOL
> > to enable (for example) RTMR-based boot measurement for TDX VMs.
> > With the current UEFI spec’s “should not” wording and EDK2
> > implementation, TPM measurement in TDVF is disabled when
> > RTMR measurement is enabled.
> >
> > Mutual exclusion of the CC measurement protocol and TCG measurement
> > protocol breaks backwards compatibility, which makes adoption of RTMRs
> > challenging. A virtualized TPM device (vTPM) managed by the host VMM
> > makes boot measurements visible to the VMM operator, but this is an
> > oft-requested feature that users can choose to accept.
> >
> > The TPM has been a standard for over a decade and many existing
> > applications rely on the TPM. Both inside and outside Google,
> > we have many users that require vTPM, including features that are
> > not easily available via RTMRs (e.g. sealing using keys that the
> > guest OS cannot access).
> >
> > This patch adds a non-default build option to allow the coexistence
> > of both the CC measurement and TCG protocols. Not included is a
> > vendor-specific measured event in the CC event log that indicates
> > whether a vTPM is attached or not.
> >
> > Cc: Erdem Aktas <erdemak...@google.com>
> > Cc: James Bottomley <j...@linux.ibm.com>
> > Cc: Jiewen Yao <jiewen....@intel.com>
> > Cc: Gerd Hoffmann <kra...@redhat.com>
> > Cc: Tom Lendacky <thomas.lenda...@amd.com>
> > Cc: Michael Roth <michael.r...@amd.com>
> > Signed-off-by: Qinkun Bao <qin...@google.com>
> > ---
> > OvmfPkg/OvmfPkgX64.dsc | 9 ++++++++-
> > .../DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLib.c | 12 +++++++++++-
> > .../DxeTpmMeasurementLib/DxeTpmMeasurementLib.c | 6 ++++++
> > 3 files changed, 25 insertions(+), 2 deletions(-)
> >
> > diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
> > index 56c920168d..9bcee45047 100644
> > --- a/OvmfPkg/OvmfPkgX64.dsc
> > +++ b/OvmfPkg/OvmfPkgX64.dsc
> > @@ -32,7 +32,8 @@
> > DEFINE SECURE_BOOT_ENABLE = FALSE
> > DEFINE SMM_REQUIRE = FALSE
> > DEFINE SOURCE_DEBUG_ENABLE = FALSE
> > - DEFINE CC_MEASUREMENT_ENABLE = FALSE
> > + DEFINE CC_MEASUREMENT_ENABLE = TRUE
> > + DEFINE CC_MEASUREMENT_AND_TCG2_COEXIST = FASLE
> >
> > !include OvmfPkg/Include/Dsc/OvmfTpmDefines.dsc.inc
> >
> > @@ -99,6 +100,11 @@
> > INTEL:*_*_X64_GENFW_FLAGS = --keepexceptiontable
> > !endif
> > RELEASE_*_*_GENFW_FLAGS = --zero
> > +!if $(CC_MEASUREMENT_ENABLE) == TRUE && $(CC_MEASUREMENT_AND_TCG2_COEXIST)
> > == TRUE
> > + MSFT:*_*_*_CC_FLAGS = /D CC_MEASUREMENT_AND_TCG2_COEXIST_FEATURE
> > + INTEL:*_*_*_CC_FLAGS = /D CC_MEASUREMENT_AND_TCG2_COEXIST_FEATURE
> > + GCC:*_*_*_CC_FLAGS = -D CC_MEASUREMENT_AND_TCG2_COEXIST_FEATURE
> > +!endif
> >
> > #
> > # Disable deprecated APIs.
> > @@ -1045,6 +1051,7 @@
> > }
> > !endif
> >
> > +
> > #
> > # TPM support
> > #
> > diff --git
> > a/SecurityPkg/Library/DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLib.c
> > b/SecurityPkg/Library/DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLib.c
> > index 73719f3b96..4c9bc8ab4a 100644
> > --- a/SecurityPkg/Library/DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLib.c
> > +++ b/SecurityPkg/Library/DxeTpm2MeasureBootLib/DxeTpm2MeasureBootLib.c
> > @@ -325,7 +325,12 @@ Tcg2MeasureGptTable (
> > }
> >
> > DEBUG ((DEBUG_INFO, "DxeTpm2MeasureBootHandler - Cc MeasureGptTable -
> > %r\n", Status));
> > +#ifdef CC_MEASUREMENT_AND_TCG2_COEXIST_FEATURE
> > + }
> > + if (Tcg2Protocol != NULL) {
> > +#else
> > } else if (Tcg2Protocol != NULL) {
> > +#endif
> > //
> > // If Tcg2Protocol is installed, then Measure GPT data with this
> > protocol.
> > //
> > @@ -493,7 +498,12 @@ Tcg2MeasurePeImage (
> > CcEvent
> > );
> > DEBUG ((DEBUG_INFO, "DxeTpm2MeasureBootHandler - Cc MeasurePeImage -
> > %r\n", Status));
> > - } else if (Tcg2Protocol != NULL) {
> > +#ifdef CC_MEASUREMENT_AND_TCG2_COEXIST_FEATURE
> > + }
> > + if (Tcg2Protocol != NULL) {
> > +#else
> > + } else if (Tcg2Protocol != NULL) {
> > +#endif
> > Status = Tcg2Protocol->HashLogExtendEvent (
> > Tcg2Protocol,
> > PE_COFF_IMAGE,
> > diff --git
> > a/SecurityPkg/Library/DxeTpmMeasurementLib/DxeTpmMeasurementLib.c
> > b/SecurityPkg/Library/DxeTpmMeasurementLib/DxeTpmMeasurementLib.c
> > index 6f287b31fc..b1c6198b4b 100644
> > --- a/SecurityPkg/Library/DxeTpmMeasurementLib/DxeTpmMeasurementLib.c
> > +++ b/SecurityPkg/Library/DxeTpmMeasurementLib/DxeTpmMeasurementLib.c
> > @@ -261,7 +261,11 @@ TpmMeasureAndLogData (
> > HashData,
> > HashDataLen
> > );
> > +#ifdef CC_MEASUREMENT_AND_TCG2_COEXIST_FEATURE
> > + }
> > +#else
> > } else {
> > +#endif
> > //
> > // Try to measure using Tpm20 protocol
> > //
> > @@ -287,7 +291,9 @@ TpmMeasureAndLogData (
> > HashDataLen
> > );
> > }
> > +#ifndef CC_MEASUREMENT_AND_TCG2_COEXIST_FEATURE
> > }
> > +#endif
> >
> > return Status;
> > }
> > --
> > 2.44.0.291.gc1ea87d7ee-goog
> >
> >
>
>
>
>
>
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