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path: root/drivers/firmware/efi/libstub/tpm.c
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2018-03-13efi/libstub/tpm: Initialize pointer variables to zero for mixed modeArd Biesheuvel
As reported by Jeremy Cline, running the new TPM libstub code in mixed mode (i.e., 64-bit kernel on 32-bit UEFI) results in hangs when invoking the TCG2 protocol, or when accessing the log_tbl pool allocation. The reason turns out to be that in both cases, the 64-bit pointer variables are not fully initialized by the 32-bit EFI code, and so we should take care to zero initialize these variables beforehand, or we'll end up dereferencing bogus pointers. Reported-by: Jeremy Cline <jeremy@jcline.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hdegoede@redhat.com Cc: jarkko.sakkinen@linux.intel.com Cc: javierm@redhat.com Cc: linux-efi@vger.kernel.org Cc: tweek@google.com Link: http://lkml.kernel.org/r/20180313140922.17266-2-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-08efi: call get_event_log before ExitBootServicesThiebaud Weksteen
With TPM 2.0 specification, the event logs may only be accessible by calling an EFI Boot Service. Modify the EFI stub to copy the log area to a new Linux-specific EFI configuration table so it remains accessible once booted. When calling this service, it is possible to specify the expected format of the logs: TPM 1.2 (SHA1) or TPM 2.0 ("Crypto Agile"). For now, only the first format is retrieved. Signed-off-by: Thiebaud Weksteen <tweek@google.com> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Tested-by: Javier Martinez Canillas <javierm@redhat.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2017-08-26efi/libstub: Enable reset attack mitigationMatthew Garrett
If a machine is reset while secrets are present in RAM, it may be possible for code executed after the reboot to extract those secrets from untouched memory. The Trusted Computing Group specified a mechanism for requesting that the firmware clear all RAM on reset before booting another OS. This is done by setting the MemoryOverwriteRequestControl variable at startup. If userspace can ensure that all secrets are removed as part of a controlled shutdown, it can reset this variable to 0 before triggering a hardware reboot. Signed-off-by: Matthew Garrett <mjg59@google.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170825155019.6740-2-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>