Re: [PATCH v5 0/5] Use RngLib instead of TimerLib for OpensslLib

["Ard Biesheuvel" <ard.biesheuvel@arm.com>]

On 8/12/20 4:21 AM, matthewfcarlson@gmail.com wrote:
> From: Matthew Carlson <macarl@microsoft.com>
> 
> Hello all,
> 
> This patch contains a fix for Bugzilla 1871.

Thanks Matthew. This looks a lot better.

Given that it was me who reported 1871 in the first place, could you 
resend this series and put me on cc on all of it? Laszlo explicitly 
requested me to review all of it, not just the parts that I co-maintain.

Thanks,
Ard.

> There's been a good bit of community discussion around the topic,
> so below follows a general overview of the discussion and what this patch does.
> 
> Back in Devel message#40590 (https://edk2.groups.io/g/devel/message/40590)
> around the patch series that updates OpenSSL to 1.1.1b, a comment was made
> that suggested that platforms be in charge of the entropy/randomness that
> is provided to OpenSSL as currently the entropry source seems to be a
> hand-rolled random number generator that uses the PerformanceCounter from
> TimerLib. This causes OpenSSL to depend on TimerLib, which is often platform
> specific. In addition to being a potentially weaker source of randomness,
> this also poses a challenge to compile BaseCryptLibOnProtocol with a platform-
> agnostic version of TimerLib that works universally.
> 
> The solution here is to allow platform to specify their source of entropy in
> addition to providing two new RngLibs: one that uses the TimerLib as well as
> one that uses RngProtocol to provide randomness. Then the decision to use
> RDRAND or other entropy sources is up to the platform. Mixing various entropy
> sources is the onus of the platform. It has been suggested on Devel#40590 and
> BZ#1871 that there should be mixing of the PerformanceCounter and RDRAND using
> something similar to the yarrow alogirthm that FreeBSD uses for example. This
> patch series doesn't offer an RngLib that offers that sort of mixing as the
> ultimate source of random is defined by the platform.
> 
> This patch series offers three benefits:
> 1. Dependency reduction: Removes the need for a platform specific timer
> library.  We publish a single binary used on numerous platforms for
> crypto and the introduced timer lib dependency caused issues because we
> could not fulfill our platform needs with one library instance.
> 
> 2. Code maintenance: Removing this additional code and leveraging an existing
> library within Edk2 means less code to maintain.
> 
> 3. Platform defined quality: A platform can choose which instance to use and
> the implications of that instance.
> 
> This patch series seeks to address five seperate issues.
>    1) Use RngLib interface to generate random entropy in rand_pool
>    2) Remove dependency on TimerLib in OpensslLib
>    3) Add a new version of RngLib implemented by TimerLib
>    4) Add a new version of RngLib implemented by EFI_RNG_PROTOCOL
>    5) Add RngLib to platforms in EDK2 such as ArmVirtPkg and OvmfPkg
> 
> Since this changes the dependencies of OpenSSL, this has the potential of being
> a breaking change for platforms in edk2-platforms. The easiest solution is just
> to use the RngLib that uses the TimerLib as this closely mimics the behavior of
> OpenSSL prior to this patch series. There is also a null version of RngLib for
> CI environments that need this change
> (https://edk2.groups.io/g/devel/message/50432). Though it should be pointed out
> that in CI environments, the null version of BaseCryptLib or OpenSSL should be
> used.
> 
> In addition, it has been suggested that
> 1) Add AsmRdSeed to BaseLib.
> 2) Update BaseRngLib to use AsmRdSeed() for the random number,
> if RdSeed is supported (CPUID BIT18)
> 
> However, this is largely out of scope for this particular patch series and
> will likely need to be in a follow-up series later.
> 
> It is my understanding that the OpenSSL code uses the values provided as a
> randomness pool rather than a seed or random numbers itself, so the
> requirements for randomness are not quite as stringent as other applications.
> 
> For the ArmVirtPkg and OvmfPkg platforms, the patch series here just adds in
> the TimerLib based RngLib as that is similar to the functionality of before.
> It is added as a common library so any custom RngLib defined in the DSC
> should take precedence over the TimerLibRngLib.
> 
> Ref: https://github.com/tianocore/edk2/pull/845
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1871
> 
> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
> Cc: Anthony Perard <anthony.perard@citrix.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Julien Grall <julien@xen.org>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Leif Lindholm <leif@nuviainc.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Xiaoyu Lu <xiaoyux.lu@intel.com>
> Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> 
> Signed-off-by: Matthew Carlson <matthewfcarlson@gmail.com>
> 
> Matthew Carlson (5):
>    MdePkg: TimerRngLib: Added RngLib that uses TimerLib
>    MdePkg: BaseRngLibDxe: Add RngLib that uses RngDxe
>    OvmfPkg: Add RngLib based on TimerLib for Crypto
>    ArmVirtPkg: Add RngLib based on TimerLib for CryptoPkg
>    CryptoPkg: OpensslLib: Use RngLib to generate entropy in rand_pool
> 
>   CryptoPkg/Library/OpensslLib/rand_pool.c                 | 203 ++------------------
>   CryptoPkg/Library/OpensslLib/rand_pool_noise.c           |  29 ---
>   CryptoPkg/Library/OpensslLib/rand_pool_noise_tsc.c       |  43 -----
>   MdePkg/Library/BaseRngLibDxe/RngDxeLib.c                 | 200 +++++++++++++++++++
>   MdePkg/Library/BaseRngLibTimerLib/RngLibTimer.c          | 187 ++++++++++++++++++
>   ArmVirtPkg/ArmVirt.dsc.inc                               |   1 +
>   CryptoPkg/CryptoPkg.dsc                                  |   1 +
>   CryptoPkg/Library/OpensslLib/OpensslLib.inf              |  15 +-
>   CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf        |  15 +-
>   CryptoPkg/Library/OpensslLib/rand_pool_noise.h           |  29 ---
>   MdePkg/Library/BaseRngLibDxe/BaseRngLibDxe.inf           |  38 ++++
>   MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf |  40 ++++
>   MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.uni |  17 ++
>   MdePkg/MdePkg.dsc                                        |   5 +-
>   OvmfPkg/Bhyve/BhyvePkgX64.dsc                            |   1 +
>   OvmfPkg/OvmfPkgIa32.dsc                                  |   1 +
>   OvmfPkg/OvmfPkgIa32X64.dsc                               |   2 +
>   OvmfPkg/OvmfPkgX64.dsc                                   |   1 +
>   OvmfPkg/OvmfXen.dsc                                      |   1 +
>   19 files changed, 515 insertions(+), 314 deletions(-)
>   delete mode 100644 CryptoPkg/Library/OpensslLib/rand_pool_noise.c
>   delete mode 100644 CryptoPkg/Library/OpensslLib/rand_pool_noise_tsc.c
>   create mode 100644 MdePkg/Library/BaseRngLibDxe/RngDxeLib.c
>   create mode 100644 MdePkg/Library/BaseRngLibTimerLib/RngLibTimer.c
>   delete mode 100644 CryptoPkg/Library/OpensslLib/rand_pool_noise.h
>   create mode 100644 MdePkg/Library/BaseRngLibDxe/BaseRngLibDxe.inf
>   create mode 100644 MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf
>   create mode 100644 MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.uni
> 
> --
> 2.27.0.windows.1
>