Hi Ard,

Given this patch plus the corresponding linux-efi patches wrt RNG, I'm
mildly concerned about buggy RDRAND implementations compromising the
kernel's RNG. Is this not a concern?

It's also worth noting that MdePkg/Library/BaseRngLib skips the CPUID bit
check in ArchIsRngSupported for $REASON, which I assume will crash
pre-RDRAND VMs.
We should probably also test for stupidly broken rdrand implementations
like the notorious Zen 3 which always return 0xFFFFFFFF (per xkcd 221 ;)).

Thanks,
Pedro

On Thu, Nov 10, 2022 at 1:48 PM Ard Biesheuvel <ardb@kernel.org> wrote:

> Expose the EFI_RNG_PROTOCOL based on RdRand, so that we don't have to
> rely on QEMU providing a virtio-rng device in order to implement this
> protocol.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  OvmfPkg/OvmfPkgIa32.dsc    | 1 +
>  OvmfPkg/OvmfPkgIa32.fdf    | 1 +
>  OvmfPkg/OvmfPkgIa32X64.dsc | 1 +
>  OvmfPkg/OvmfPkgIa32X64.fdf | 1 +
>  OvmfPkg/OvmfPkgX64.dsc     | 1 +
>  OvmfPkg/OvmfPkgX64.fdf     | 1 +
>  6 files changed, 6 insertions(+)
>
> diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
> index e9ba491237ae..18c1e7255812 100644
> --- a/OvmfPkg/OvmfPkgIa32.dsc
> +++ b/OvmfPkg/OvmfPkgIa32.dsc
> @@ -941,6 +941,7 @@ [Components]
>    }
>  !endif
>
> +  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
>  !if $(SECURE_BOOT_ENABLE) == TRUE
>
>  SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf
>    OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.inf
> diff --git a/OvmfPkg/OvmfPkgIa32.fdf b/OvmfPkg/OvmfPkgIa32.fdf
> index 7023ade8cebe..34f27ca832bc 100644
> --- a/OvmfPkg/OvmfPkgIa32.fdf
> +++ b/OvmfPkg/OvmfPkgIa32.fdf
> @@ -248,6 +248,7 @@ [FV.DXEFV]
>  INF  OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf
>  !endif
>
> +  INF  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
>  !if $(SECURE_BOOT_ENABLE) == TRUE
>    INF
> SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf
>  !endif
> diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
> index af566b953f36..e9a199c9f490 100644
> --- a/OvmfPkg/OvmfPkgIa32X64.dsc
> +++ b/OvmfPkg/OvmfPkgIa32X64.dsc
> @@ -955,6 +955,7 @@ [Components.X64]
>    }
>  !endif
>
> +  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
>  !if $(SECURE_BOOT_ENABLE) == TRUE
>
>  SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf
>    OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.inf
> diff --git a/OvmfPkg/OvmfPkgIa32X64.fdf b/OvmfPkg/OvmfPkgIa32X64.fdf
> index 80de4fa2c0df..33cc163e596e 100644
> --- a/OvmfPkg/OvmfPkgIa32X64.fdf
> +++ b/OvmfPkg/OvmfPkgIa32X64.fdf
> @@ -249,6 +249,7 @@ [FV.DXEFV]
>  INF  OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf
>  !endif
>
> +  INF  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
>  !if $(SECURE_BOOT_ENABLE) == TRUE
>    INF
> SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf
>  !endif
> diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
> index f39d9cd117e6..5572cb82998f 100644
> --- a/OvmfPkg/OvmfPkgX64.dsc
> +++ b/OvmfPkg/OvmfPkgX64.dsc
> @@ -1023,6 +1023,7 @@ [Components]
>    }
>  !endif
>
> +  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
>  !if $(SECURE_BOOT_ENABLE) == TRUE
>
>  SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf
>    OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.inf
> diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
> index c0f5a1ef3c30..d42deebe3f8f 100644
> --- a/OvmfPkg/OvmfPkgX64.fdf
> +++ b/OvmfPkg/OvmfPkgX64.fdf
> @@ -274,6 +274,7 @@ [FV.DXEFV]
>  INF  OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf
>  !endif
>
> +INF  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
>  !if $(SECURE_BOOT_ENABLE) == TRUE
>    INF
> SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf
>  !endif
> --
> 2.35.1
>
>
>
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-- 
Pedro Falcato