From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mx.groups.io with SMTP id smtpd.web08.8020.1668610938409413920 for ; Wed, 16 Nov 2022 07:02:18 -0800 Authentication-Results: mx.groups.io; dkim=missing; spf=pass (domain: arm.com, ip: 217.140.110.172, mailfrom: pierre.gondois@arm.com) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 518A41477; Wed, 16 Nov 2022 07:02:24 -0800 (PST) Received: from cam-smtp0.cambridge.arm.com (pierre123.nice.arm.com [10.34.100.128]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 004D23F587; Wed, 16 Nov 2022 07:02:16 -0800 (PST) From: "PierreGondois" To: devel@edk2.groups.io Cc: Sami Mujawar , Ard Biesheuvel , Liming Gao , Jiewen Yao , Jian J Wang Subject: [PATCH v2 1/1] SecurityPkg/RngDxe: Fix Rng algo selection for Arm Date: Wed, 16 Nov 2022 16:01:49 +0100 Message-Id: <20221116150149.2200368-1-Pierre.Gondois@arm.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable From: Pierre Gondois BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3D4151 The EFI_RNG_PROTOCOL can advertise multiple algorithms through Guids. The PcdCpuRngSupportedAlgorithm contains a Guid that can be configured. It represents the algorithm used in RngLib. PcdCpuRngSupportedAlgorithm is set to the Zero Guid for KvmTool. When running KvmTool on a platform platform only having the RngLib, the only Guid available for EFI_RNG_PROTOCOL will be the zero Guid. To select the default algorithm in EFI_RNG_PROTOCOL.GetRng(): a. Zero Guids are skipped b. If no algorithm is found, an ASSERT is triggered To allow using the RngLib to be used for the case above, Zero Guids should not be skipped (a.). If no algorithm is found, don't prevent from booting on DEBUG builds (b.). Allow Zero Guids to be selected and don't ASSERT if no algorithm is found. Also simplify the selection of the Rng algorithm when the default one is selected by just picking up the first element of mAvailableAlgoArray. Reported-by: Sami Mujawar Signed-off-by: Pierre Gondois --- Notes: v2: - Reformulate commit message. - Do not warn if no algorithm is found as the message would be printed on non-Arm platforms. .../RandomNumberGenerator/RngDxe/ArmRngDxe.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c b/Secur= ityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c index 5ba319899ce9..722d53386373 100644 --- a/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c @@ -76,7 +76,6 @@ RngGetRNG ( ) { EFI_STATUS Status; - UINTN Index; =20 if ((This =3D=3D NULL) || (RNGValueLength =3D=3D 0) || (RNGValue =3D=3D= NULL)) { return EFI_INVALID_PARAMETER; @@ -86,21 +85,13 @@ RngGetRNG ( // // Use the default RNG algorithm if RNGAlgorithm is NULL. // - for (Index =3D 0; Index < mAvailableAlgoArrayCount; Index++) { - if (!IsZeroGuid (&mAvailableAlgoArray[Index])) { - RNGAlgorithm =3D &mAvailableAlgoArray[Index]; - goto FoundAlgo; - } - } - - if (Index =3D=3D mAvailableAlgoArrayCount) { - // No algorithm available. - ASSERT (Index !=3D mAvailableAlgoArrayCount); + if (mAvailableAlgoArrayCount !=3D 0) { + RNGAlgorithm =3D &mAvailableAlgoArray[0]; + } else { return EFI_DEVICE_ERROR; } } =20 -FoundAlgo: if (CompareGuid (RNGAlgorithm, PcdGetPtr (PcdCpuRngSupportedAlgorithm)= )) { Status =3D RngGetBytes (RNGValueLength, RNGValue); return Status; --=20 2.25.1