Hi Heinrich, On Fri, Sep 03, 2021 at 08:22:30AM +0200, Heinrich Schuchardt wrote: > On 9/3/21 3:55 AM, Masahisa Kojima wrote: > > TCG EFI Protocol Specification defines that PCRIndex parameter > > passed from caller must be 0 to 23. > > TPM2_MAX_PCRS is currently used to check the range of PCRIndex, > > but TPM2_MAX_PCRS is tpm2 device dependent and may have larger value. > > This commit newly adds EFI_TCG2_MAX_PCR_INDEX macro, it is used to > > check the range of PCRIndex parameter. > > In the U-Boot code we have TPM2_MAX_PCRS hard coded as 32. Can the value > be less?
This is defined in [1] [1] https://trustedcomputinggroup.org/wp-content/uploads/TSS_Overview_Common_v0p9_r10_12june2021.pdf > > > > > Signed-off-by: Masahisa Kojima <masahisa.koj...@linaro.org> > > --- > > include/efi_tcg2.h | 2 ++ > > lib/efi_loader/efi_tcg2.c | 2 +- > > 2 files changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/include/efi_tcg2.h b/include/efi_tcg2.h > > index 45788d55d5..b647361d44 100644 > > --- a/include/efi_tcg2.h > > +++ b/include/efi_tcg2.h > > @@ -28,6 +28,8 @@ > > #define EFI_TCG2_EXTEND_ONLY 0x0000000000000001 > > #define PE_COFF_IMAGE 0x0000000000000010 > > > > +#define EFI_TCG2_MAX_PCR_INDEX 23 > > + > > /* Algorithm Registry */ > > #define EFI_TCG2_BOOT_HASH_ALG_SHA1 0x00000001 > > #define EFI_TCG2_BOOT_HASH_ALG_SHA256 0x00000002 > > diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c > > index c4e9f61fd6..b268a02976 100644 > > --- a/lib/efi_loader/efi_tcg2.c > > +++ b/lib/efi_loader/efi_tcg2.c > > @@ -958,7 +958,7 @@ efi_tcg2_hash_log_extend_event(struct efi_tcg2_protocol > > *this, u64 flags, > > goto out; > > } > > > > - if (efi_tcg_event->header.pcr_index > TPM2_MAX_PCRS) { > > If TPM2_MAX_PCRS were device dependent and could be less then 23 we > would need a check against both constants. > > Could you, please, clarify the issue. If TPM2_MAX_PCRS is always greater > then 23, please, mention this in the commit message and perhaps add a > comment in the code here. You don't need that (I think). If the spec says you have to check against 23, then that's what Kojima-san fixes here. If the device supports less than 23, then the current code as-is will return EFI_DEVICE_ERROR, in case the device has less than 23 PCRs. We could ofc just check against the value we get from GetCapability, which would be correct as well? > > Best regards > > Heinrich > > > + if (efi_tcg_event->header.pcr_index > EFI_TCG2_MAX_PCR_INDEX) { > > ret = EFI_INVALID_PARAMETER; > > goto out; > > } > > [1] https://trustedcomputinggroup.org/wp-content/uploads/TSS_Overview_Common_v0p9_r10_12june2021.pdf Regards /Ilias
