linux-kernel - Re: [tpmdd-devel] [PATCH v3 0/5] Call GetEventLog before ExitBootServices

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Date:   Tue, 26 Sep 2017 13:17:27 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Thiebaud Weksteen <tweek@...gle.com>, linux-efi@...r.kernel.org,
        linux-integrity@...r.kernel.org, tpmdd-devel@...ts.sourceforge.net
Cc:     ard.biesheuvel@...aro.org, matt@...eblueprint.co.uk,
        linux-kernel@...r.kernel.org, jarkko.sakkinen@...ux.intel.com,
        jgunthorpe@...idianresearch.com, mjg59@...gle.com
Subject: Re: [tpmdd-devel] [PATCH v3 0/5] Call GetEventLog before
 ExitBootServices

On 09/20/2017 10:13 AM, Thiebaud Weksteen via tpmdd-devel wrote:
> With TPM 1.2, the ACPI table ("TCPA") has two fields to recover the Event
> Log Area (LAML and LASA). These logs are useful to understand and rebuild
> the final values of PCRs.
> 
> With TPM 2.0, the ACPI table ("TPM2") does not contain these fields
> anymore. The recommended method is now to call the GetEventLog EFI
> protocol before ExitBootServices.
> 
> Implement this method within the EFI stub and create a copy of the logs
> for the TPM device using a Linux-specific EFI configuration table
> (LINUX_EFI_TPM_EVENT_LOG). This will create
> /sys/kernel/security/tpm0/binary_bios_measurements for TPM 2.0 devices
> (similarly to the current behaviour for TPM 1.2 devices).
> 
> Two formats for the log entries exist: TPM 1.2 (SHA1) and TPM 2.0 (Crypto
> Agile). This patch set only retrieves the first type of logs. The second
> type will be implemented in a subsequent patch set.
> 
> According to the specifications[1], once GetEventLog has been called,
> future events shall be stored in a separate EFI configuration table
> (EFI_TCG2_FINAL_EVENTS_TABLE). Events stored in this table are not
> processed in this patch set as they are stored in the Crypto Agile format.
> These could eventually be merged with the new table for a unified view
> of the logs from userspace.
> 
> [1] TCG EFI Protocol Specification, Revision 00.13, March 30, 2016
>     https://trustedcomputinggroup.org/wp-content/uploads/EFI-Protocol-Specification-rev13-160330final.pdf
> 
> -------------------------------------------------------------------------------
> 
> Patchset Changelog:
> 
> Version 3:
> - Move event log providers (acpi and of) to tpm_eventlog_*.c
> - Move efi changes from PATCH 3 to PATCH 2
> - Change return value of tpm_read_log_acpi and tpm_read_log_of
> - Change iounmap to memunmap calls
> - Use log_tbl as variable name for consistency
> - Fix kbuild failures
> 

Thanks for addressing the things I pointed out. For the whole patch-set:

Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>
Tested-by: Javier Martinez Canillas <javierm@...hat.com>

Best regards,
-- 
Javier Martinez Canillas
Software Engineer - Desktop Hardware Enablement
Red Hat