Re: [PATCH v5 2/7] tpm: remove definition of TPM2_ACTIVE_PCR_BANKS

[Roberto Sassu]

On 11/28/2018 1:17 PM, Roberto Sassu wrote:
> On 11/16/2018 2:38 PM, Jarkko Sakkinen wrote:
> > On Wed, Nov 14, 2018 at 04:31:03PM +0100, Roberto Sassu wrote:
> > > tcg_efi_specid_event and tcg_pcr_event2 declaration contains static 
> > > arrays
> > > for a list of hash algorithms used for event logs and event log digests.
> > >
> > > However, according to TCG EFI Protocol Specification, these arrays have
> > > variable sizes. Setting the array size to zero or 3 does not make any
> > > difference, because the parser has to adjust the offset depending on the
> > > actual array size to access structure members after the static arrays.
> > >
> > > Thus, this patch removes the declaration of TPM2_ACTIVE_PCR_BANKS and 
> > > sets
> > > the array size to zero.
> > >
> > > Fixes: 4d23cc323cdb ("tpm: add securityfs support for TPM 2.0 firmware
> > > event log")
> > >
> > > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> > > ---
> > > Â include/linux/tpm_eventlog.h | 5 ++---
> > > Â 1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h
> > > index 20d9da77fc11..3d5d162f09cc 100644
> > > --- a/include/linux/tpm_eventlog.h
> > > +++ b/include/linux/tpm_eventlog.h
> > > @@ -8,7 +8,6 @@
> > > Â #define TCG_EVENT_NAME_LEN_MAXÂÂÂ 255
> > > Â #define MAX_TEXT_EVENTÂÂÂÂÂÂÂ 1000ÂÂÂ /* Max event string length */
> > > Â #define ACPI_TCPA_SIGÂÂÂÂÂÂÂ "TCPA"ÂÂÂ /* 0x41504354 /'TCPA' */
> > > -#define TPM2_ACTIVE_PCR_BANKSÂÂÂ 3
> > > Â #define EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2 0x1
> > > Â #define EFI_TCG2_EVENT_LOG_FORMAT_TCG_2ÂÂ 0x2
> > > @@ -90,7 +89,7 @@ struct tcg_efi_specid_event {
> > > ÂÂÂÂÂ u8 spec_errata;
> > > ÂÂÂÂÂ u8 uintnsize;
> > > ÂÂÂÂÂ u32 num_algs;
> > > -ÂÂÂ struct tcg_efi_specid_event_algs 
> > > digest_sizes[TPM2_ACTIVE_PCR_BANKS];
> > > +ÂÂÂ struct tcg_efi_specid_event_algs digest_sizes[0];
> > > ÂÂÂÂÂ u8 vendor_info_size;
> > > ÂÂÂÂÂ u8 vendor_info[0];
> > > Â } __packed;
> > > @@ -117,7 +116,7 @@ struct tcg_pcr_event2 {
> > > ÂÂÂÂÂ u32 pcr_idx;
> > > ÂÂÂÂÂ u32 event_type;
> > > ÂÂÂÂÂ u32 count;
> > > -ÂÂÂ struct tpm2_digest digests[TPM2_ACTIVE_PCR_BANKS];
> > > +ÂÂÂ struct tpm2_digest digests[0];
> > > ÂÂÂÂÂ struct tcg_event_field event;
> > > Â } __packed;
> > > --
> > > 2.17.1
> >
> > NAK for the same reason as last time.
>
> I added this comment to include/linux/tpm_eventlog.h:
>
> /*
>  Â* http://www.trustedcomputinggroup.org/tcg-efi-protocol-specification/
>  Â*
>  Â* Set the size of 'digest_sizes' and 'digests', members of 
> tcg_efi_specid_event
>  Â* and tcg_pcr_event2, to zero. Structures with variable-sized arrays 
> placed
>  Â* midway are not suitable for type casting.
>  Â*/

If this comment is ok, I will send a new version of the patch set.

Roberto


> > /Jarkko

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