[edk2-devel] [PATCH v6 00/14] Add the VariablePolicy feature
Bret Barkelew via groups.io
bret.barkelew=microsoft.com at groups.io
Tue Aug 18 05:24:43 UTC 2020
Responses below…
- Bret
From: Dandan Bi via groups.io<mailto:dandan.bi=intel.com at groups.io>
Sent: Tuesday, August 11, 2020 6:52 AM
To: devel at edk2.groups.io<mailto:devel at edk2.groups.io>; Bi, Dandan<mailto:dandan.bi at intel.com>; bret at corthon.com<mailto:bret at corthon.com>
Cc: Yao, Jiewen<mailto:jiewen.yao at intel.com>; Zhang, Chao B<mailto:chao.b.zhang at intel.com>; Wang, Jian J<mailto:jian.j.wang at intel.com>; Wu, Hao A<mailto:hao.a.wu at intel.com>; liming.gao<mailto:liming.gao at intel.com>; Justen, Jordan L<mailto:jordan.l.justen at intel.com>; Laszlo Ersek<mailto:lersek at redhat.com>; Ard Biesheuvel<mailto:ard.biesheuvel at arm.com>; Andrew Fish<mailto:afish at apple.com>; Ni, Ray<mailto:ray.ni at intel.com>
Subject: [EXTERNAL] Re: [edk2-devel] [PATCH v6 00/14] Add the VariablePolicy feature
Hi Bret,
Sorry for the delayed response.
Some more comments here:
1. Currently I see the LockVaribePolicy is called at ReadyToBoot by variable driver, could we update it to be called at EndOfDxe? We should prevent malicious code registering policy after EndOfDxe for security concern. And could we also add the test case to check the variable policy is locked at EndofDxe?
We could. Right now it’s at ReadyToBoot because it’s just there as a safety net and the platform could lock it earlier. Would it work to have a PCD for which EventGroup GUID the platform should lock on?
2. For patch 4, the SMM communication, some general guidelines for SMI handler:
a) Check whether the communication buffer is outside SMM and valid.
For this feature, please double check whether the communication buffer is checked, if all the range in communication buffer has already been checked within existing edk2 core infrastructure, please also add the comments in the code to mention that it has been checked.
I checked this, but I will recheck (since there’ve been a few revisions in the patches) and update the comments.
b) Should copy the communication buffer to SMRAM before checking the data fields to avoid TOC/TOU attac
For this feature, for example, when dump variable policy, if malicious code updates the DumpParams->TotalSize in communication buffer to smaller one to allocate the PaginationCache buffer, and then update it the correct one and dump the variable policy data into the PaginationCache buffer, it will cause buffer overflow in this case. So please double check the code and copy the communication buffer into SMRAM to avoid such kind issue.
Will also check for this.
3. Did you do any security test for this feature?
Such as? There are both unit tests and integration tests to ensure correct functionality and that the disable and lock interfaces work as expected. I haven’t fuzzed it or anything that involved.
4. Currently, LockVariablePolicy can prevent RegisterVariablePolicy and DisableVariablePolicy. So in SMI hander, could we check the variable policy is locked or not firstly and then decide whether need to check and execution for VAR_CHECK_POLICY_COMMAND_REGISTER and VAR_CHECK_POLICY_COMMAND_DISABLE?
I’ll take a look, but my gut says this may be an unnecessary complication.
5. Since there is the logic when variable policy is disabled, it will permit deletion of auth/protected variables. Could we add some comments in code to mention that variable policy should always be enabled for security concern to avoid giving bad example?
I’m happy to think about how to document this, but I’m not immediately inclined to outright say it shouldn’t be disabled. I’d be happy to say that it shouldn’t be disabled in “normal, production configuration”, but it’s entirely reasonable to be disabled in a Manufacturing or R&R environment and we would actually prefer this be used because it would at least be consistent across platforms, rather than being something done ad hoc by each platform that needs it. Would that be sufficient?
Thanks,
Dandan
> -----Original Message-----
> From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of Dandan
> Bi
> Sent: Thursday, July 2, 2020 10:14 AM
> To: devel at edk2.groups.io; bret at corthon.com
> Cc: Yao, Jiewen <jiewen.yao at intel.com>; Zhang, Chao B
> <chao.b.zhang at intel.com>; Wang, Jian J <jian.j.wang at intel.com>; Wu, Hao
> A <hao.a.wu at intel.com>; Gao, Liming <liming.gao at intel.com>; Justen,
> Jordan L <jordan.l.justen at intel.com>; Laszlo Ersek <lersek at redhat.com>;
> Ard Biesheuvel <ard.biesheuvel at arm.com>; Andrew Fish
> <afish at apple.com>; Ni, Ray <ray.ni at intel.com>
> Subject: Re: [edk2-devel] [PATCH v6 00/14] Add the VariablePolicy feature
>
> Hi Bret,
>
> Thanks for the contribution.
>
> I have taken an overview of this patch series and have some small comments
> in the related patches, please check in sub-patch.
>
> I will review the patch series more in details and bring more comments back
> if have. Do you have a branch for these patches in GitHub? Which should be
> easy for review.
>
>
> Thanks,
> Dandan
>
> > -----Original Message-----
> > From: devel at edk2.groups.io <devel at edk2.groups.io> On Behalf Of Bret
> > Barkelew
> > Sent: Tuesday, June 23, 2020 2:41 PM
> > To: devel at edk2.groups.io
> > Cc: Yao, Jiewen <jiewen.yao at intel.com>; Zhang, Chao B
> > <chao.b.zhang at intel.com>; Wang, Jian J <jian.j.wang at intel.com>; Wu,
> > Hao A <hao.a.wu at intel.com>; Gao, Liming <liming.gao at intel.com>;
> > Justen, Jordan L <jordan.l.justen at intel.com>; Laszlo Ersek
> > <lersek at redhat.com>; Ard Biesheuvel <ard.biesheuvel at arm.com>;
> Andrew
> > Fish <afish at apple.com>; Ni, Ray <ray.ni at intel.com>
> > Subject: [edk2-devel] [PATCH v6 00/14] Add the VariablePolicy feature
> >
> > REF:https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D2522&data=02%7C01%7CBret.Barkelew%40microsoft.com%7C91eed7c4a0d54e2eff6008d83dfdc4ec%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637327507431539442&sdata=cLpx7VZsG%2F6r6GCXmiCS4DmmgOH4iKfX3VSAAYUOU00%3D&reserved=0
> >
> > The 14 patches in this series add the VariablePolicy feature to the
> > core, deprecate Edk2VarLock (while adding a compatibility layer to
> > reduce code churn), and integrate the VariablePolicy libraries and
> > protocols into Variable Services.
> >
> > Since the integration requires multiple changes, including adding
> > libraries, a protocol, an SMI communication handler, and
> > VariableServices integration, the patches are broken up by individual
> > library additions and then a final integration. Security-sensitive
> > changes like bypassing Authenticated Variable enforcement are also
> > broken out into individual patches so that attention can be called directly to
> them.
> >
> > Platform porting instructions are described in this wiki entry:
> > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftianocore%2Ftianocore.github.io%2Fwiki%2FVariablePolicy-&data=02%7C01%7CBret.Barkelew%40microsoft.com%7C91eed7c4a0d54e2eff6008d83dfdc4ec%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637327507431539442&sdata=%2FYNgK7yixA5Gi7E9bHw3LIUNAQpZMh9ykTUqCqv2SRY%3D&reserved=0
> > Protocol---Enhanced-Method-for-Managing-Variables#platform-porting
> >
> > Discussion of the feature can be found in multiple places throughout
> > the last year on the RFC channel, staging branches, and in devel.
> >
> > Most recently, this subject was discussed in this thread:
> > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fedk2.groups.io%2Fg%2Fdevel%2Fmessage%2F53712&data=02%7C01%7CBret.Barkelew%40microsoft.com%7C91eed7c4a0d54e2eff6008d83dfdc4ec%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637327507431539442&sdata=i7qaO6eZT8%2BzCT0satTptMWwCNspDz%2BS05eJmGGR628%3D&reserved=0
> > (the code branches shared in that discussion are now out of date, but
> > the whitepapers and discussion are relevant).
> >
> > Cc: Jiewen Yao <jiewen.yao at intel.com>
> > Cc: Chao Zhang <chao.b.zhang at intel.com>
> > Cc: Jian J Wang <jian.j.wang at intel.com>
> > Cc: Hao A Wu <hao.a.wu at intel.com>
> > Cc: Liming Gao <liming.gao at intel.com>
> > Cc: Jordan Justen <jordan.l.justen at intel.com>
> > Cc: Laszlo Ersek <lersek at redhat.com>
> > Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
> > Cc: Andrew Fish <afish at apple.com>
> > Cc: Ray Ni <ray.ni at intel.com>
> > Cc: Bret Barkelew <brbarkel at microsoft.com>
> > Signed-off-by: Bret Barkelew <brbarkel at microsoft.com>
> >
> > v6 changes:
> > * Fix an issue with uninitialized Status in InitVariablePolicyLib()
> > and
> > DeinitVariablePolicyLib()
> > * Fix GCC building in shell-based functional test
> > * Rebase on latest origin/master
> >
> > v5 changes:
> > * Fix the CONST mismatch in VariablePolicy.h and
> > VariablePolicySmmDxe.c
> > * Fix EFIAPI mismatches in the functional unittest
> > * Rebase on latest origin/master
> >
> > v4 changes:
> > * Remove Optional PcdAllowVariablePolicyEnforcementDisable PCD from
> > platforms
> > * Rebase on master
> > * Migrate to new MmCommunicate2 protocol
> > * Fix an oversight in the default return value for
> > InitMmCommonCommBuffer
> > * Fix in VariablePolicyLib to allow ExtraInitRuntimeDxe to consume
> > variables
> >
> > V3 changes:
> > * Address all non-unittest issues with ECC
> > * Make additional style changes
> > * Include section name in hunk headers in "ini-style" files
> > * Remove requirement for the EdkiiPiSmmCommunicationsRegionTable
> > driver
> > (now allocates its own buffer)
> > * Change names from VARIABLE_POLICY_PROTOCOL and
> > gVariablePolicyProtocolGuid
> > to EDKII_VARIABLE_POLICY_PROTOCOL and
> > gEdkiiVariablePolicyProtocolGuid
> > * Fix GCC warning about initializing externs
> > * Add UNI strings for new PCD
> > * Add patches for ArmVirtPkg, OvmfXen, and UefiPayloadPkg
> > * Reorder patches according to Liming's feedback about adding to
> platforms
> > before changing variable driver
> >
> > V2 changes:
> > * Fixed implementation for RuntimeDxe
> > * Add PCD to block DisableVariablePolicy
> > * Fix the DumpVariablePolicy pagination in SMM
> >
> > Bret Barkelew (14):
> > MdeModulePkg: Define the VariablePolicy protocol interface
> > MdeModulePkg: Define the VariablePolicyLib
> > MdeModulePkg: Define the VariablePolicyHelperLib
> > MdeModulePkg: Define the VarCheckPolicyLib and SMM interface
> > OvmfPkg: Add VariablePolicy engine to OvmfPkg platform
> > EmulatorPkg: Add VariablePolicy engine to EmulatorPkg platform
> > ArmVirtPkg: Add VariablePolicy engine to ArmVirtPkg platform
> > UefiPayloadPkg: Add VariablePolicy engine to UefiPayloadPkg platform
> > MdeModulePkg: Connect VariablePolicy business logic to
> > VariableServices
> > MdeModulePkg: Allow VariablePolicy state to delete protected variables
> > SecurityPkg: Allow VariablePolicy state to delete authenticated
> > variables
> > MdeModulePkg: Change TCG MOR variables to use VariablePolicy
> > MdeModulePkg: Drop VarLock from RuntimeDxe variable driver
> > MdeModulePkg: Add a shell-based functional test for VariablePolicy
> >
> > MdeModulePkg/Library/VarCheckPolicyLib/VarCheckPolicyLib.c
> > | 320 +++
> >
> > MdeModulePkg/Library/VariablePolicyHelperLib/VariablePolicyHelperLib.c
> > | 396 ++++
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyExtraInitNull.c
> > | 46 +
> >
> >
> MdeModulePkg/Library/VariablePolicyLib/VariablePolicyExtraInitRuntimeDx
> > e.c | 85 +
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c
> > | 816 +++++++
> >
> >
> MdeModulePkg/Library/VariablePolicyLib/VariablePolicyUnitTest/VariablePo
> > licyUnitTest.c | 2440 ++++++++++++++++++++
> >
> >
> MdeModulePkg/Test/ShellTest/VariablePolicyFuncTestApp/VariablePolicyFu
> > ncTestApp.c | 1978 ++++++++++++++++
> > MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockDxe.c
> > | 52 +-
> > MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
> > | 60 +-
> > MdeModulePkg/Universal/Variable/RuntimeDxe/VarCheck.c
> > | 49 +-
> > MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c
> > | 53 +
> >
> >
> MdeModulePkg/Universal/Variable/RuntimeDxe/VariableLockRequstToLock
> > .c | 71 +
> > MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c
> > | 642 +++++
> >
> >
> MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.
> > c | 14 +
> > SecurityPkg/Library/AuthVariableLib/AuthService.c |
> 22
> > +-
> > ArmVirtPkg/ArmVirt.dsc.inc | 4 +
> > EmulatorPkg/EmulatorPkg.dsc | 3 +
> > MdeModulePkg/Include/Guid/VarCheckPolicyMmi.h
> |
> > 54 +
> > MdeModulePkg/Include/Library/VariablePolicyHelperLib.h
> > | 164 ++
> > MdeModulePkg/Include/Library/VariablePolicyLib.h |
> > 207 ++
> > MdeModulePkg/Include/Protocol/VariablePolicy.h |
> > 157 ++
> > MdeModulePkg/Library/VarCheckPolicyLib/VarCheckPolicyLib.inf
> > | 42 +
> > MdeModulePkg/Library/VarCheckPolicyLib/VarCheckPolicyLib.uni
> > | 12 +
> >
> > MdeModulePkg/Library/VariablePolicyHelperLib/VariablePolicyHelperLib.i
> > nf
> > | 35 +
> >
> > MdeModulePkg/Library/VariablePolicyHelperLib/VariablePolicyHelperLib.u
> > ni
> > | 12 +
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.inf
> > | 44 +
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.uni
> > | 12 +
> >
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLibRuntimeDxe.inf
> > | 51 +
> >
> >
> MdeModulePkg/Library/VariablePolicyLib/VariablePolicyUnitTest/VariablePo
> > licyUnitTest.inf | 40 +
> > MdeModulePkg/MdeModulePkg.ci.yaml | 4
> +-
> > MdeModulePkg/MdeModulePkg.dec | 26 +-
> > MdeModulePkg/MdeModulePkg.dsc | 15 +
> > MdeModulePkg/MdeModulePkg.uni | 7 +
> > MdeModulePkg/Test/MdeModulePkgHostTest.dsc
> |
> > 11 +
> > MdeModulePkg/Test/ShellTest/VariablePolicyFuncTestApp/Readme.md
> > | 55 +
> >
> >
> MdeModulePkg/Test/ShellTest/VariablePolicyFuncTestApp/VariablePolicyFu
> > ncTestApp.inf | 42 +
> > MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf
> > | 5 +
> > MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf
> > | 4 +
> >
> >
> MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.i
> > nf | 10 +
> >
> >
> MdeModulePkg/Universal/Variable/RuntimeDxe/VariableStandaloneMm.inf
> > | 4 +
> > OvmfPkg/OvmfPkgIa32.dsc | 5 +
> > OvmfPkg/OvmfPkgIa32X64.dsc | 5 +
> > OvmfPkg/OvmfPkgX64.dsc | 5 +
> > OvmfPkg/OvmfXen.dsc | 4 +
> > SecurityPkg/Library/AuthVariableLib/AuthVariableLib.inf |
> > 2 +
> > UefiPayloadPkg/UefiPayloadPkgIa32.dsc | 4 +
> > UefiPayloadPkg/UefiPayloadPkgIa32X64.dsc | 4 +
> > 47 files changed, 8015 insertions(+), 78 deletions(-) create mode
> > 100644 MdeModulePkg/Library/VarCheckPolicyLib/VarCheckPolicyLib.c
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyHelperLib/VariablePolicyHelperLib.c
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyExtraInitNull.c
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyExtraInitRuntimeD
> > x
> > e.c
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyUnitTest/Variable
> > Po
> > licyUnitTest.c
> > create mode 100644
> >
> MdeModulePkg/Test/ShellTest/VariablePolicyFuncTestApp/VariablePolicyFu
> > ncTestApp.c
> > create mode 100644
> >
> MdeModulePkg/Universal/Variable/RuntimeDxe/VariableLockRequstToLock
> > .c
> > create mode 100644
> > MdeModulePkg/Universal/Variable/RuntimeDxe/VariablePolicySmmDxe.c
> > create mode 100644 MdeModulePkg/Include/Guid/VarCheckPolicyMmi.h
> > create mode 100644
> > MdeModulePkg/Include/Library/VariablePolicyHelperLib.h
> > create mode 100644 MdeModulePkg/Include/Library/VariablePolicyLib.h
> > create mode 100644 MdeModulePkg/Include/Protocol/VariablePolicy.h
> > create mode 100644
> > MdeModulePkg/Library/VarCheckPolicyLib/VarCheckPolicyLib.inf
> > create mode 100644
> > MdeModulePkg/Library/VarCheckPolicyLib/VarCheckPolicyLib.uni
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyHelperLib/VariablePolicyHelperLib.i
> > nf
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyHelperLib/VariablePolicyHelperLib.u
> > ni
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.inf
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.uni
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLibRuntimeDxe.inf
> > create mode 100644
> > MdeModulePkg/Library/VariablePolicyLib/VariablePolicyUnitTest/Variable
> > Po
> > licyUnitTest.inf
> > create mode 100644
> > MdeModulePkg/Test/ShellTest/VariablePolicyFuncTestApp/Readme.md
> > create mode 100644
> >
> MdeModulePkg/Test/ShellTest/VariablePolicyFuncTestApp/VariablePolicyFu
> > ncTestApp.inf
> >
> > --
> > 2.26.2.windows.1.8.g01c50adf56.20200515075929
> >
> >
> >
>
>
>
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