Re: [edk2-devel] [PATCH 05/11] SecurityPkg/RngLibRdSeed: add an instance of RngLib to make use rdseed

["Ard Biesheuvel" <ard.biesheuvel@linaro.org>]

On Thu, 14 Nov 2019 at 04:39, Wang, Jian J <jian.j.wang@intel.com> wrote:
>
> Mike,
>
> I figured that rdseed is only needed in cases demanding highest entropy,
> like seeding other pseudo-RNG. It's not for general purpose randomness.
> Then I put it in SecurityPkg. But I'm ok to put it into MdePkg. I have no
> strong opinion for this.
>

I think it is a bad idea to use the same library abstraction [RngLib]
for exposing
a) entropy sources used for seeding deterministic random number generators
b) deterministic random number generators themselves
c) low entropy pseudo-RNGs based on timestamp counters, etc

given that the use cases don't usually overlap. I.e., only a DRBG
implementation requires a), and exports RngLib itself based on that.
Use cases that can tolerate c) [like IV generators for block
encryption] are typically disjoint from ones that require b) [for key
generation]. The idea that you can use RngLib for all of them, and
plug arbitrary instantiations of it into each is misguided IMHO.



> > -----Original Message-----
> > From: Kinney, Michael D <michael.d.kinney@intel.com>
> > Sent: Thursday, November 14, 2019 12:25 PM
> > To: devel@edk2.groups.io; Wang, Jian J <jian.j.wang@intel.com>; Kinney,
> > Michael D <michael.d.kinney@intel.com>
> > Cc: Yao, Jiewen <jiewen.yao@intel.com>; Zhang, Chao B
> > <chao.b.zhang@intel.com>; Gao, Liming <liming.gao@intel.com>; Ni, Ray
> > <ray.ni@intel.com>
> > Subject: RE: [edk2-devel] [PATCH 05/11] SecurityPkg/RngLibRdSeed: add an
> > instance of RngLib to make use rdseed
> >
> > Jian,
> >
> > Why is this lib instance in the SecurityPkg?  It only depends
> > on the MdePkg.  Can't non security feature related modules
> > that want to a random number use this lib without using the
> > SecurityPkg?  Could this lib instance be added to MdePkg?
> >
> > Thanks,
> >
> > Mike
> >
> > > -----Original Message-----
> > > From: devel@edk2.groups.io <devel@edk2.groups.io> On
> > > Behalf Of Wang, Jian J
> > > Sent: Wednesday, November 13, 2019 6:18 PM
> > > To: devel@edk2.groups.io
> > > Cc: Yao, Jiewen <jiewen.yao@intel.com>; Zhang, Chao B
> > > <chao.b.zhang@intel.com>; Kinney, Michael D
> > > <michael.d.kinney@intel.com>; Gao, Liming
> > > <liming.gao@intel.com>; Ni, Ray <ray.ni@intel.com>
> > > Subject: [edk2-devel] [PATCH 05/11]
> > > SecurityPkg/RngLibRdSeed: add an instance of RngLib to
> > > make use rdseed
> > >
> > > This version of RngLib makes use of AsmRdSeed to get
> > > non-deterministic random number, which can be used for
> > > seeding other software DRNG like rand interface in
> > > openssl. It can be used only on IA32/X64 processors
> > > which supports rdseed instruction.
> > >
> > > Ref:
> > > https://bugzilla.tianocore.org/show_bug.cgi?id=1871
> > > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > > Cc: Chao Zhang <chao.b.zhang@intel.com>
> > > Cc: Michael D Kinney <michael.d.kinney@intel.com>
> > > Cc: Liming Gao <liming.gao@intel.com>
> > > Cc: Ray Ni <ray.ni@intel.com>
> > > Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> > > ---
> > >  .../RngLibRdSeed/RngLibRdSeed.inf             |  37
> > > ++++
> > >  .../RngLibRdSeed/RngLibRdSeed.uni             |  18 ++
> > >  .../RngLibRdSeed/RngRdSeed.c                  | 189
> > > ++++++++++++++++++
> > >  3 files changed, 244 insertions(+)
> > >  create mode 100644
> > > SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLibRd
> > > Seed.inf
> > >  create mode 100644
> > > SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLibRd
> > > Seed.uni
> > >  create mode 100644
> > > SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngRdSee
> > > d.c
> > >
> > > diff --git
> > > a/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLib
> > > RdSeed.inf
> > > b/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLib
> > > RdSeed.inf
> > > new file mode 100644
> > > index 0000000000..8162408775
> > > --- /dev/null
> > > +++
> > > b/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLib
> > > RdSeed.inf
> > > @@ -0,0 +1,37 @@
> > > +## @file
> > > +#  Instance of RNG (Random Number Generator) Library.
> > > +#
> > > +#  Rng RdSeed Library that uses CPU RdSeed instruction
> > > access to
> > > +provide #  non-deterministic random number which can
> > > be used as seed
> > > +for other #  software deterministic RNGs.
> > > +#
> > > +#  Copyright (c) 2019, Intel Corporation. All rights
> > > reserved.<BR> # #
> > > +SPDX-License-Identifier: BSD-2-Clause-Patent # # ##
> > > +
> > > +[Defines]
> > > +  INF_VERSION                    = 0x00010029
> > > +  BASE_NAME                      = RngLibRdSeed
> > > +  MODULE_UNI_FILE                = RngLibRdSeed.uni
> > > +  FILE_GUID                      = 8B613B2E-B944-40F9-
> > > B979-1B60D7CAA73C
> > > +  MODULE_TYPE                    = BASE
> > > +  VERSION_STRING                 = 1.0
> > > +  LIBRARY_CLASS                  = RngLib
> > > +  CONSTRUCTOR                    =
> > > RngLibRdSeedConstructor
> > > +
> > > +#
> > > +#  VALID_ARCHITECTURES           = IA32 X64
> > > +#
> > > +
> > > +[Sources.Ia32, Sources.X64]
> > > +  RngRdSeed.c
> > > +
> > > +[Packages]
> > > +  MdePkg/MdePkg.dec
> > > +
> > > +[LibraryClasses]
> > > +  BaseLib
> > > +  DebugLib
> > > diff --git
> > > a/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLib
> > > RdSeed.uni
> > > b/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLib
> > > RdSeed.uni
> > > new file mode 100644
> > > index 0000000000..051a3019bc
> > > --- /dev/null
> > > +++
> > > b/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngLib
> > > RdSeed.uni
> > > @@ -0,0 +1,18 @@
> > > +// /** @file
> > > +// Instance of RNG (Random Number Generator) Library.
> > > +//
> > > +// Rng RdSeed Library that uses CPU RdSeed instruction
> > > access to
> > > +provide // non-deterministic random number which can
> > > be used as seed
> > > +for other // software deterministic RNGs.
> > > +//
> > > +// Copyright (c) 2019, Intel Corporation. All rights
> > > reserved.<BR> //
> > > +// SPDX-License-Identifier: BSD-2-Clause-Patent // //
> > > **/
> > > +
> > > +
> > > +#string STR_MODULE_ABSTRACT             #language en-
> > > US "Instance of RNG Library"
> > > +
> > > +#string STR_MODULE_DESCRIPTION          #language en-
> > > US "RngRdSeed Library that uses CPU RdSeed instruction
> > > access to provide non-deterministic random numbers."
> > > +
> > > diff --git
> > > a/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngRdS
> > > eed.c
> > > b/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngRdS
> > > eed.c
> > > new file mode 100644
> > > index 0000000000..0036faa050
> > > --- /dev/null
> > > +++
> > > b/SecurityPkg/RandomNumberGenerator/RngLibRdSeed/RngRdS
> > > eed.c
> > > @@ -0,0 +1,189 @@
> > > +/** @file
> > > +  Random number generator services that uses RdSeed
> > > instruction access
> > > +  to provide non-deterministic random numbers, which
> > > are usually used
> > > +  for seeding other pseudo-random number generators.
> > > +
> > > +Copyright (c) 2019, Intel Corporation. All rights
> > > reserved.<BR>
> > > +SPDX-License-Identifier: BSD-2-Clause-Patent
> > > +
> > > +**/
> > > +
> > > +#include <Library/BaseLib.h>
> > > +#include <Library/DebugLib.h>
> > > +#include <Library/RngLib.h>
> > > +
> > > +//
> > > +// Bit mask used to determine if RdSeed instruction is
> > > supported.
> > > +//
> > > +#define RDSEED_MASK                  BIT18
> > > +
> > > +//
> > > +// Limited retry number when valid random data is
> > > returned.
> > > +// It varies between 1 and 100 according to "Intel(R)
> > > DRGN Software
> > > +Implementation // Guide". Let's use the same value as
> > > RDRAND in BaseRngLib.
> > > +//
> > > +#define RDSEED_RETRY_LIMIT           10
> > > +
> > > +/**
> > > +  The constructor function checks whether or not
> > > RDSEED instruction is
> > > +supported
> > > +  by the host hardware.
> > > +
> > > +  The constructor function checks whether or not
> > > RDSEED instruction is supported.
> > > +  It will ASSERT() if RDSEED instruction is not
> > > supported.
> > > +
> > > +  @retval RETURN_SUCCESS      The processor supports
> > > RDSEED instruction.
> > > +  @retval RETURN_UNSUPPORTED  RDSEED instruction is
> > > not supported.
> > > +
> > > +**/
> > > +RETURN_STATUS
> > > +EFIAPI
> > > +RngLibRdSeedConstructor (
> > > +  VOID
> > > +  )
> > > +{
> > > +  UINT32  RegEbx;
> > > +
> > > +  //
> > > +  // Determine RDSEED support by examining bit 18 of
> > > the EBX register
> > > + returned by  // CPUID(EAX=7, ECX=0). BIT18 of EBX
> > > indicates that
> > > + processor support RDSEED  // instruction.
> > > +  //
> > > +  AsmCpuidEx (7, 0, NULL, &RegEbx, NULL, NULL);  if
> > > ((RegEbx &
> > > + RDSEED_MASK) != RDSEED_MASK) {
> > > +    ASSERT ((RegEbx & RDSEED_MASK) == RDSEED_MASK);
> > > +    return RETURN_UNSUPPORTED;
> > > +  }
> > > +
> > > +  return RETURN_SUCCESS;
> > > +}
> > > +
> > > +/**
> > > +  Generates a 16-bit random number.
> > > +
> > > +  if Rand is NULL, then ASSERT().
> > > +
> > > +  @param[out] Rand     Buffer pointer to store the 16-
> > > bit random value.
> > > +
> > > +  @retval TRUE         Random number generated
> > > successfully.
> > > +  @retval FALSE        Failed to generate the random
> > > number.
> > > +
> > > +**/
> > > +BOOLEAN
> > > +EFIAPI
> > > +GetRandomNumber16 (
> > > +  OUT     UINT16                    *Rand
> > > +  )
> > > +{
> > > +  UINT32  Index;
> > > +
> > > +  ASSERT (Rand != NULL);
> > > +
> > > +  //
> > > +  // A loop to fetch a 16 bit random value with a
> > > retry count limit.
> > > +  //
> > > +  for (Index = 0; Index < RDSEED_RETRY_LIMIT; Index++)
> > > {
> > > +    if (AsmRdSeed16 (Rand)) {
> > > +      return TRUE;
> > > +    }
> > > +  }
> > > +
> > > +  return FALSE;
> > > +}
> > > +
> > > +/**
> > > +  Generates a 32-bit random number.
> > > +
> > > +  if Rand is NULL, then ASSERT().
> > > +
> > > +  @param[out] Rand     Buffer pointer to store the 32-
> > > bit random value.
> > > +
> > > +  @retval TRUE         Random number generated
> > > successfully.
> > > +  @retval FALSE        Failed to generate the random
> > > number.
> > > +
> > > +**/
> > > +BOOLEAN
> > > +EFIAPI
> > > +GetRandomNumber32 (
> > > +  OUT     UINT32                    *Rand
> > > +  )
> > > +{
> > > +  UINT32  Index;
> > > +
> > > +  ASSERT (Rand != NULL);
> > > +
> > > +  //
> > > +  // A loop to fetch a 32 bit random value with a
> > > retry count limit.
> > > +  //
> > > +  for (Index = 0; Index < RDSEED_RETRY_LIMIT; Index++)
> > > {
> > > +    if (AsmRdSeed32 (Rand)) {
> > > +      return TRUE;
> > > +    }
> > > +  }
> > > +
> > > +  return FALSE;
> > > +}
> > > +
> > > +/**
> > > +  Generates a 64-bit random number.
> > > +
> > > +  if Rand is NULL, then ASSERT().
> > > +
> > > +  @param[out] Rand     Buffer pointer to store the 64-
> > > bit random value.
> > > +
> > > +  @retval TRUE         Random number generated
> > > successfully.
> > > +  @retval FALSE        Failed to generate the random
> > > number.
> > > +
> > > +**/
> > > +BOOLEAN
> > > +EFIAPI
> > > +GetRandomNumber64 (
> > > +  OUT     UINT64                    *Rand
> > > +  )
> > > +{
> > > +  UINT32  Index;
> > > +
> > > +  ASSERT (Rand != NULL);
> > > +
> > > +  //
> > > +  // A loop to fetch a 64 bit random value with a
> > > retry count limit.
> > > +  //
> > > +  for (Index = 0; Index < RDSEED_RETRY_LIMIT; Index++)
> > > {
> > > +    if (AsmRdSeed64 (Rand)) {
> > > +      return TRUE;
> > > +    }
> > > +  }
> > > +
> > > +  return FALSE;
> > > +}
> > > +
> > > +/**
> > > +  Generates a 128-bit random number.
> > > +
> > > +  if Rand is NULL, then ASSERT().
> > > +
> > > +  @param[out] Rand     Buffer pointer to store the
> > > 128-bit random value.
> > > +
> > > +  @retval TRUE         Random number generated
> > > successfully.
> > > +  @retval FALSE        Failed to generate the random
> > > number.
> > > +
> > > +**/
> > > +BOOLEAN
> > > +EFIAPI
> > > +GetRandomNumber128 (
> > > +  OUT     UINT64                    *Rand
> > > +  )
> > > +{
> > > +  ASSERT (Rand != NULL);
> > > +
> > > +  //
> > > +  // Read first 64 bits
> > > +  //
> > > +  if (!GetRandomNumber64 (Rand)) {
> > > +    return FALSE;
> > > +  }
> > > +
> > > +  //
> > > +  // Read second 64 bits
> > > +  //
> > > +  return GetRandomNumber64 (++Rand);
> > > +}
> > > --
> > > 2.17.1.windows.2
> > >
> > >
> > >
>
>
> 
>