Re: [PATCH v5 0/2] CryptoPkg/BaseHashLib: Implement Unified Hash Calculation API

["Michael D Kinney" <michael.d.kinney@intel.com>]

Amol,

Thank your for providing patches for this feature.
You have done a very good job on following the 
design patterns from similar feature types in the
EDK II and following the EDK II coding style.  I 
do have some recommended changes below and have
attempted to provide reasons for these recommendations.
Please let me know if you have any questions or need
any clarifications

I am thinking of the use case where a developer is
updating an existing module that uses the BaseCryptLib
to use the BaseHashLib.  The BaseHashLib does not
provide that same set of services per hash algorithm
which means there may be module that would like to
switch to BaseHashLib, but can't.  

Can we update BaseHashLib to provide the same set of
services:

	HashApiGetContextSize()
	HashApiInit()
	HashApiDuplicate()
	HashApiUpdate()
	HashApiFinal()
	HashApiHashAll()

The BaseHashLib uses the term "Handle" where the
BaseCryptLib uses the term "Context".  This may confuse
developers that are porting from BaseCryptLib usage to
BaseHashLib usage.  I recommend we continue the use 
of the term "Context" in BasehHashLib.

The BaseCryptLib supports PEI, DXE, SMM, and Runtime.
is there a reason that BaseHashLib only supports PEI
and DXE INFs?  Upon further review, the implementation of
this library only uses the services of other library
classes and is not phase specific at all.  I think this
could be a single INF/UNI file  with a MODULE_TYPE of
BASE and include <Base.h> at the top of BaseHashLib.c.
This lib instance would be compatible with all module
types.

I see the PCD name " PcdSystemHashPolicy".  This PCD can
be set in the context of a single module if different
modules in a platform FW build use different hash algorithms.
As a result, this PCD can be used for both system wide 
policy settings using a Dynamic/DynamicEx PCD type or
a module scoped PCD setting using a FixedAtBuild or 
PatchableInModule PCD type.  This PCD is scoped for use
by the BaseHashLib.  Perhaps a better name would be
"PcdHashApiLibPolicy".

I have received feedback before against the use of the
term "Base" in the name of a library class.  It causes
confusion because the term "Base" usually applies to the
library implementation to describe the module type
compatibility of the lib instance.  Take BaseCryptLib
class as an example.  There are instances of this library
that are specific to PEI, DXE, SMM, and Runtime. If we
look at the entire edk2 repo, there are only 3 lib classes
that start with the term "Base":

  BaseLib        - OK.  Single instance of type BASE.
  BaseMemoryLib  - Confusing.  BASE, PEI, DXE versions
  BaseCryptLib   - Confusing.  PEI, DXE, SMM, RT versions

I also see the BaseHashLib service names use "HashApi".
In order to address both the use of the term "Base" and
The inconsistency between the lib class name and the lib
service names, I recommend the lib class be changed from
"BaseHashLib" to "HashApiLib" along with a few other name
changes to scope defines and types to the HashApiLib:

  BaseHashLib  -> HashApiLib
  HASH_HANDLE  -> HASH_API_CONTEXT
  HASH_INVALID -> HASH_API_ALGORITHM_INVALID
  HASH_MD4     -> HASH_API_ALGORITHM_MD4
  HASH_MD5     -> HASH_API_ALGORITHM_MD5
  HASH_SHA1    -> HASH_API_ALGORITHM_SHA1
  HASH_SHA256  -> HASH_API_ALGORITHM_SHA256
  HASH_SHA384  -> HASH_API_ALGORITHM_SHA384
  HASH_SHA512  -> HASH_API_ALGORITHM_SHA512
  HASH_SM3_256 -> HASH_API_ALGORITHM_SM3_256
  HASH_MAX     -> Remove.  Not used.

Some file name a directory names changes would
also be required to follow this same pattern.

The include file "CryptoPkgTokenSpace.h" can
be removed.  I know the pattern in the existing
packages contains this include file, but there
was a change in the autogen that supports defining
a GUID value in the DEC file without requiring
an associated .h file.  This new pattern only 
applies to GUIDs that have no associated data
structures, Protocols, or PPIs.  A token space
GUID is a good example of a GUID value with no
associated structures.

BaseHashLib.h includes the file <Uefi.h>.  This
can be removed.  Modules and library instances
that use a library class will include a top
level include file that matches the MODULE_TYPE
before including any library class .h files or
protocols/ppi/guid .h files. 

  <Base.h>
  <PiPei.h>
  <PiDxe.h>
  <PiSmm.h>
  <PiMm.h>
  <Uefi.h>

Thanks,

Mike

> -----Original Message-----
> From: Sukerkar, Amol N <amol.n.sukerkar@intel.com>
> Sent: Thursday, January 23, 2020 8:47 AM
> To: devel@edk2.groups.io
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Yao,
> Jiewen <jiewen.yao@intel.com>; Wang, Jian J
> <jian.j.wang@intel.com>; Agrawal, Sachin
> <sachin.agrawal@intel.com>; Musti, Srinivas
> <srinivas.musti@intel.com>; Lakkimsetti, Subash
> <subash.lakkimsetti@intel.com>
> Subject: [PATCH v5 0/2] CryptoPkg/BaseHashLib: Implement
> Unified Hash Calculation API
> 
> Currently, the UEFI drivers using the SHA/SM3 hashing
> algorithms use hard-coded
> API to calculate the hash, for instance, sha_256(...),
> etc. Since SHA384 and/or
> SM3_256 are being increasingly adopted for robustness,
> it becomes cumbersome to
> modify each driver that calls into hash calculating API.
> 
> To better achieve this, we are proposing a Unified API,
> which can be used by UEFI
> drivers, that provides the drivers with flexibility to
> use the desired hashing
> algorithm based on the required robnustness.
> 
> Alternatively, the design document is also attached to
> Bugzilla,
> https://bugzilla.tianocore.org/show_bug.cgi?id=2151.
> 
> Sukerkar, Amol N (2):
>   CryptoPkg: Add CryptoPkg Token Space GUID
>   CryptoPkg/BaseHashLib: Implement Unified Hash
> Calculation API
> 
>  CryptoPkg/Library/BaseHashLib/BaseHashLib.c      | 228
> ++++++++++++++++++++
>  CryptoPkg/CryptoPkg.dec                          |  28
> ++-
>  CryptoPkg/CryptoPkg.dsc                          |   6
> +-
>  CryptoPkg/CryptoPkg.uni                          |  17
> ++
>  CryptoPkg/Include/Guid/CryptoPkgTokenSpace.h     |  19
> ++
>  CryptoPkg/Include/Library/BaseHashLib.h          |  81
> +++++++
>  CryptoPkg/Library/BaseHashLib/BaseHashLibDxe.inf |  44
> ++++
>  CryptoPkg/Library/BaseHashLib/BaseHashLibDxe.uni |  17
> ++
>  CryptoPkg/Library/BaseHashLib/BaseHashLibPei.inf |  45
> ++++
>  CryptoPkg/Library/BaseHashLib/BaseHashLibPei.uni |  17
> ++
>  10 files changed, 500 insertions(+), 2 deletions(-)
>  create mode 100644
> CryptoPkg/Library/BaseHashLib/BaseHashLib.c
>  create mode 100644
> CryptoPkg/Include/Guid/CryptoPkgTokenSpace.h
>  create mode 100644
> CryptoPkg/Include/Library/BaseHashLib.h
>  create mode 100644
> CryptoPkg/Library/BaseHashLib/BaseHashLibDxe.inf
>  create mode 100644
> CryptoPkg/Library/BaseHashLib/BaseHashLibDxe.uni
>  create mode 100644
> CryptoPkg/Library/BaseHashLib/BaseHashLibPei.inf
>  create mode 100644
> CryptoPkg/Library/BaseHashLib/BaseHashLibPei.uni
> 
> --
> 2.16.2.windows.1