[PATCH v10 0/5] Use RngLib instead of TimerLib for OpensslLib

Matthew Carlson

From: Matthew Carlson <macarl@...>

Hello all,

This patch contains a fix for Bugzilla 1871.
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.

This is the seventh iteration of this patch series, focused on code style and a
few functions being renamed to comply with style.

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

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

Patch Series History:
v10 - addressed comments from Liming removing magic numbers and adding DebugLib to TimerRngLib
v8 - addressed comments from Ard and Mike around code style for DxeRngLib and BaseRngLibTimerLib
v7 - addressed comments from Lazlo and Ard for further fixes around OvmfPkg
v6 - addressed comments from Lazlo and Ard for fixes around OvmfPkg
v5 - moved additions for OvmfPkg and ArmVirtPkg to correct positions
v4 - added more information to various commit messages
v3 - addressed comments from Mike K around fixes to BaseRngLibTimer delays
v2 - renamed some libraries to fit with naming conventions

Cc: Ard Biesheuvel <ard.biesheuvel@...>
Cc: Anthony Perard <anthony.perard@...>
Cc: Jiewen Yao <jiewen.yao@...>
Cc: Jian J Wang <jian.j.wang@...>
Cc: Julien Grall <julien@...>
Cc: Jordan Justen <jordan.l.justen@...>
Cc: Laszlo Ersek <lersek@...>
Cc: Liming Gao <liming.gao@...>
Cc: Leif Lindholm <leif@...>
Cc: Michael D Kinney <michael.d.kinney@...>
Cc: Xiaoyu Lu <xiaoyux.lu@...>
Cc: Zhiguang Liu <zhiguang.liu@...>
Cc: Sean Brogan <sean.brogan@...>

Signed-off-by: Matthew Carlson <matthewfcarlson@...>

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 | 269 +++++---------------
CryptoPkg/Library/OpensslLib/rand_pool_noise.c | 29 ---
CryptoPkg/Library/OpensslLib/rand_pool_noise_tsc.c | 43 ----
MdePkg/Library/BaseRngLibTimerLib/RngLibTimer.c | 189 ++++++++++++++
MdePkg/Library/DxeRngLib/DxeRngLib.c | 199 +++++++++++++++
ArmVirtPkg/ArmVirt.dsc.inc | 1 +
CryptoPkg/CryptoPkg.ci.yaml | 4 +-
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/BaseRngLibTimerLib/BaseRngLibTimerLib.inf | 36 +++
MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.uni | 15 ++
MdePkg/Library/DxeRngLib/DxeRngLib.inf | 38 +++
MdePkg/Library/DxeRngLib/DxeRngLib.uni | 15 ++
MdePkg/MdePkg.dsc | 5 +-
OvmfPkg/Bhyve/BhyveX64.dsc | 1 +
OvmfPkg/OvmfPkgIa32.dsc | 1 +
OvmfPkg/OvmfPkgIa32X64.dsc | 1 +
OvmfPkg/OvmfPkgX64.dsc | 1 +
OvmfPkg/OvmfXen.dsc | 1 +
21 files changed, 570 insertions(+), 338 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/BaseRngLibTimerLib/RngLibTimer.c
create mode 100644 MdePkg/Library/DxeRngLib/DxeRngLib.c
delete mode 100644 CryptoPkg/Library/OpensslLib/rand_pool_noise.h
create mode 100644 MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf
create mode 100644 MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.uni
create mode 100644 MdePkg/Library/DxeRngLib/DxeRngLib.inf
create mode 100644 MdePkg/Library/DxeRngLib/DxeRngLib.uni


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