Hi Heinrich,
On Wed, Nov 17, 2021 at 11:01:55AM +0100, Heinrich Schuchardt wrote:
On 11/17/21 10:10, Ilias Apalodimas wrote:
As described in the TCG spec [1] in sections 7.1.1 and 7.1.2 the FinalEvent table should include events after GetEventLog has been called. This currently works for us as long as the kernel is the only EFI application calling that. Specifically we only implement what's described in 7.1.1.
So refactor the code a bit and support EFI application calling GetEventLog. Events will now be logged in both the EventLog and FinalEvent table as long as ExitBootServices haven't been invoked.
[1] https://trustedcomputinggroup.org/wp-content/uploads/EFI-Protocol-Specificat...
Signed-off-by: Ilias Apalodimas ilias.apalodimas@linaro.org
lib/efi_loader/efi_tcg2.c | 90 ++++++++++++++++++++++++++------------- 1 file changed, 61 insertions(+), 29 deletions(-)
diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c index 189e4a5ba59c..215f4b2b04b8 100644 --- a/lib/efi_loader/efi_tcg2.c +++ b/lib/efi_loader/efi_tcg2.c @@ -34,6 +34,7 @@ struct event_log_buffer { size_t final_pos; /* final events config table position */ size_t last_event_size; bool get_event_called;
- bool ebs_called;
Please, add documentation for the elements of the structure. Not every reader will be aware of ebs_called referring to ExitBootServices().
Sure
bool truncated; };
@@ -186,39 +187,29 @@ static efi_status_t tcg2_pcr_extend(struct udevice *dev, u32 pcr_index, return EFI_SUCCESS;
[...]
/** @@ -1303,6 +1333,7 @@ static efi_status_t efi_init_event_log(void) event_log.pos = 0; event_log.last_event_size = 0; event_log.get_event_called = false;
event_log.ebs_called = false; event_log.truncated = false;
/*
@@ -1792,6 +1823,7 @@ efi_tcg2_notify_exit_boot_services(struct efi_event *event, void *context)
EFI_ENTRY("%p, %p", event, context);
This is called in EFI_EVENT_GROUP_EXIT_BOOT_SERVICES.
This implies that whatever happens in EFI_EVENT_GROUP_BEFORE_EXIT_BOOT_SERVICES is measured normally. Does this conform to the TCG2 standard?
Yes I think so. My understanding of 7.1.2 diagram in the spec is: - Log all events to the EventLog buffer if GetEventLog() hasn't been called - Log all events to the EventLog buffer *and* the FinalEvent config table if GetEventLog() has been called - If you are in EBS(), you don't know if the firmware has cleaned up the EventLog buffer, so log these events in the FinalEvent config table only.
- event_log.ebs_called = true;
How should a failed call to ExitBootServices() be handled? E.g. invalid memory map?
Good question. We also have efi_tcg2_notify_exit_boot_services_failed(). If the EventLog buffer hasn't been destroyed from memory we can switch the ebs_called = false?
Cheers /Ilias
Best regards
Heinrich
ret = platform_get_tpm2_device(&dev); if (ret != EFI_SUCCESS) goto out;