Commit 3e0b0f88 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi/libstub: Use TPM event typedefs from the TCG PC Client spec 

Our efi_tcg2_tagged_event is not defined in the EFI spec, but it is not
a local invention either: it was taken from the TCG PC Client spec,
where it is called TCG_PCClientTaggedEvent.

Note that this spec also contains some guidance on how to populate it,
which is not being followed closely at the moment; it claims that the
event size should cover the TCG_PCClientTaggedEvent and its payload
only, but it currently covers the preceding efi_tcg2_event too.

However, this directly contradicts the TCG EFI protocol specification,
which states very clearly that the event size should cover the entire
data structure, including the leading efi_tcg2_event_t struct.

So rename the struct and document its provenance, but retain the
existing logic to populate the size field.

Link: https://lore.kernel.org/all/20240308085754.476197-8-ardb+git@google.com


Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 841c3516

drivers/firmware/efi/libstub/efi-stub-helper.c

+11 −9
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 


#include <linux/efi.h>

#include <linux/kernel.h>

#include <linux/overflow.h>

#include <asm/efi.h>

#include <asm/setup.h>
@@ -219,23 +220,24 @@ static const struct { 
	},

};



struct efistub_measured_event {

	efi_tcg2_event_t	event_data;

	TCG_PCClientTaggedEvent tagged_event __packed;

};



static efi_status_t efi_measure_tagged_event(unsigned long load_addr,

					     unsigned long load_size,

					     enum efistub_event event)

{

	struct efistub_measured_event *evt;

	int size = struct_size(evt, tagged_event.tagged_event_data,

			       events[event].event_data_len);

	efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;

	efi_tcg2_protocol_t *tcg2 = NULL;

	efi_status_t status;



	efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2);

	if (tcg2) {

		struct efi_measured_event {

			efi_tcg2_event_t	event_data;

			efi_tcg2_tagged_event_t tagged_event;

			u8			tagged_event_data[];

		} *evt;

		int size = sizeof(*evt) + events[event].event_data_len;



		status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,

				     (void **)&evt);

		if (status != EFI_SUCCESS)
@@ -249,12 +251,12 @@ static efi_status_t efi_measure_tagged_event(unsigned long load_addr, 
			.event_header.event_type	= EV_EVENT_TAG,

		};



		evt->tagged_event = (struct efi_tcg2_tagged_event){

		evt->tagged_event = (TCG_PCClientTaggedEvent){

			.tagged_event_id		= events[event].event_id,

			.tagged_event_data_size		= events[event].event_data_len,

		};



		memcpy(evt->tagged_event_data, events[event].event_data,

		memcpy(evt->tagged_event.tagged_event_data, events[event].event_data,

		       events[event].event_data_len);



		status = efi_call_proto(tcg2, hash_log_extend_event, 0,

drivers/firmware/efi/libstub/efistub.h

+6 −6
Original line number Diff line number Diff line
@@ -843,14 +843,14 @@ struct efi_tcg2_event { 
	/* u8[] event follows here */

} __packed;



struct efi_tcg2_tagged_event {

/* from TCG PC Client Platform Firmware Profile Specification */

typedef struct tdTCG_PCClientTaggedEvent {

	u32	tagged_event_id;

	u32	tagged_event_data_size;

	/* u8  tagged event data follows here */

} __packed;

	u8	tagged_event_data[];

} TCG_PCClientTaggedEvent;



typedef struct efi_tcg2_event efi_tcg2_event_t;

typedef struct efi_tcg2_tagged_event efi_tcg2_tagged_event_t;

typedef union efi_tcg2_protocol efi_tcg2_protocol_t;



union efi_tcg2_protocol {