Laszlo,
> -----Original Message----- > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo Ersek > Sent: Tuesday, November 12, 2019 3:50 PM > To: Wang, Jian J <jian.j.w...@intel.com>; devel@edk2.groups.io > Cc: Yao, Jiewen <jiewen....@intel.com>; Zhang, Chao B > <chao.b.zh...@intel.com>; Kinney, Michael D <michael.d.kin...@intel.com>; > Gao, Liming <liming....@intel.com>; Ard Biesheuvel > <ard.biesheu...@linaro.org>; Ni, Ray <ray...@intel.com> > Subject: Re: [edk2-devel] [PATCH] SecurityPkg/RngLibNull: add null version of > RngLib > > On 11/12/19 06:55, Jian J Wang wrote: > > This is null version of RngLib which is used for those platforms or > > components which don't need random number. > > > > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1871 > > Cc: Jiewen Yao <jiewen....@intel.com> > > Cc: Chao Zhang <chao.b.zh...@intel.com> > > Cc: Michael D Kinney <michael.d.kin...@intel.com> > > Cc: Liming Gao <liming....@intel.com> > > Cc: Laszlo Ersek <ler...@redhat.com> > > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > > Cc: Ray Ni <ray...@intel.com> > > Signed-off-by: Jian J Wang <jian.j.w...@intel.com> > > --- > > .../RngLibNull/RngLibNull.c | 95 +++++++++++++++++++ > > .../RngLibNull/RngLibNull.inf | 31 ++++++ > > .../RngLibNull/RngLibNull.uni | 14 +++ > > 3 files changed, 140 insertions(+) > > create mode 100644 > SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.c > > create mode 100644 > SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.inf > > create mode 100644 > SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.uni > > (1) I don't see any reason why this library instance should not be added > under MdePkg/Library. The other library instance is already there (and > the lib class header too is from MdePkg): > > MdePkg/Library/BaseRngLib > > (2) I think this library instance should be called "BaseRngLibNull", not > just "RngLibNull". > I have no strong opinion on this. Liming, do you have any comments? > More below: > > > diff --git a/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.c > b/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.c > > new file mode 100644 > > index 0000000000..13677abc84 > > --- /dev/null > > +++ b/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.c > > @@ -0,0 +1,95 @@ > > +/** @file > > + Null version of Random number generator services. > > + > > +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> > > + > > +/** > > + 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 > > + ) > > +{ > > + ASSERT (FALSE); > > + 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 > > + ) > > +{ > > + ASSERT (FALSE); > > + 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 > > + ) > > +{ > > + ASSERT (FALSE); > > + 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 (FALSE); > > + return FALSE; > > +} > > diff --git a/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.inf > b/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.inf > > new file mode 100644 > > index 0000000000..f6494cdb82 > > --- /dev/null > > +++ b/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.inf > > @@ -0,0 +1,31 @@ > > +## @file > > +# Null instance of RNG (Random Number Generator) Library. > > +# > > +# Copyright (c) 2019, Intel Corporation. All rights reserved.<BR> > > +# > > +# SPDX-License-Identifier: BSD-2-Clause-Patent > > +# > > +## > > + > > +[Defines] > > + INF_VERSION = 0x00010005 > > + BASE_NAME = RngLibNull > > + MODULE_UNI_FILE = RngLibNull.uni > > + FILE_GUID = CD8991F8-2061-4084-8C9E-9C6F352DC58D > > + MODULE_TYPE = BASE > > + VERSION_STRING = 1.0 > > + LIBRARY_CLASS = RngLib > > + > > +# > > +# VALID_ARCHITECTURES = IA32 X64 ARM AARCH64 > > +# > > + > > +[Sources] > > + RngLibNull.c > > + > > +[Packages] > > + MdePkg/MdePkg.dec > > + > > +[LibraryClasses] > > + BaseLib > > + DebugLib > > diff --git a/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.uni > b/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.uni > > new file mode 100644 > > index 0000000000..40b2ec3fe1 > > --- /dev/null > > +++ b/SecurityPkg/RandomNumberGenerator/RngLibNull/RngLibNull.uni > > @@ -0,0 +1,14 @@ > > +// /** @file > > +// Null Instance of RNG (Random Number Generator) Library. > > +// > > +// Copyright (c) 2019, Intel Corporation. All rights reserved.<BR> > > +// > > +// SPDX-License-Identifier: BSD-2-Clause-Patent > > +// > > +// **/ > > + > > + > > +#string STR_MODULE_ABSTRACT #language en-US "Null Instance of > RNG Library" > > + > > +#string STR_MODULE_DESCRIPTION #language en-US "Caution: This is a > null version of RNG library and SHOULD NOT be used on any product ever." > > + > > > > (3) I disagree with STR_MODULE_DESCRIPTION. > > This library instance is appropriate even in production, namely for such > modules that *inherit* a dependency on RngLib -- for example, through > another library instance --, but, in practice, they never consume > randomness, and/or they never *must* consume randomness. > > In other words, this library instance should be used with modules that > should, in practice, never *reach* any calls to GetRandomNumberXX() > APIs, but it is difficult to remove the call sites themselves -- for > example, because they are inherited (i.e., indirectly) through another > library class. > > With that in mind, the ASSERT()s seem justified -- these functions > should never be reached. > > Note: I'm not saying that the ASSERT()s are *required*. Luckily, all > these APIs are able to report failure, and so if all client code checks > the return values, no actual functionality will be misled. (The > functions in this lib instance all return FALSE, correctly.) But, the > ASSERT()s are good for pointing out the larger issue: if a module > actually calls these functions (because it needs actual randomness), > then the module / platform configuration (= DSC file) is broken. > > In summary, STR_MODULE_DESCRIPTION should state, "this library instance > should be used with modules that inherit an (indirect) dependency on the > RngLib class, but never actually call RngLib APIs for consuming randomness". > Good explanation. Thanks. And I agree with your version of STR_MODULE_DESCRIPTION. I'll update it in v2. Regards, Jian > Thanks, > Laszlo > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#50451): https://edk2.groups.io/g/devel/message/50451 Mute This Topic: https://groups.io/mt/54019525/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
