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From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
To: Ard Biesheuvel <ardb+git@google.com>, linux-efi@vger.kernel.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Ilias Apalodimas <ilias.apalodimas@linaro.org>
Subject: Re: [PATCH 3/4] efi/libstub: Measure into CC protocol if TCG2 protocol is absent
Date: Tue, 5 Mar 2024 13:39:11 -0800	[thread overview]
Message-ID: <ca82210c-ba17-4b91-aa97-9806459f1e11@linux.intel.com> (raw)
In-Reply-To: <20240304104409.2326422-9-ardb+git@google.com>


On 3/4/24 2:44 AM, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> To accommodate confidential compute VMs that expose the simplified CC
> measurement protocol instead of the full-blown TCG2 one, fall back to
> the former if the latter does not exist.
>
> The CC protocol was designed to be used in this manner, which is why the
> types and prototypes have been kept the same where possible. So reuse
> the existing code, and only deviate from the TCG2 code path where
> needed.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---

Looks fine to me.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>  drivers/firmware/efi/libstub/efi-stub-helper.c | 67 +++++++++++++++-----
>  drivers/firmware/efi/libstub/efistub.h         |  3 +
>  2 files changed, 53 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
> index 0dbc9d3f4abd..21f4567324f6 100644
> --- a/drivers/firmware/efi/libstub/efi-stub-helper.c
> +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
> @@ -223,44 +223,77 @@ static efi_status_t efi_measure_tagged_event(unsigned long load_addr,
>  					     unsigned long load_size,
>  					     enum efistub_event_type event)
>  {
> +	union {
> +		efi_status_t
> +		(__efiapi *hash_log_extend_event)(void *, u64, efi_physical_addr_t,
> +						  u64, const union efistub_event *);
> +		struct { u32 hash_log_extend_event; } mixed_mode;
> +	} method;
>  	struct efistub_measured_event *evt;
>  	int size = struct_size(evt, tagged_event_data,
>  			       events[event].event_data_len);
>  	efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
>  	efi_tcg2_protocol_t *tcg2 = NULL;
> +	union efistub_event ev;
>  	efi_status_t status;
> +	void *protocol;
>  
>  	efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2);
>  	if (tcg2) {
> -		status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
> -				     (void **)&evt);
> -		if (status != EFI_SUCCESS)
> -			goto fail;
> -
> -		evt->event_data.tcg2_data = (struct efi_tcg2_event){
> +		ev.tcg2_data = (struct efi_tcg2_event){
>  			.event_size			= size,
> -			.event_header.header_size	= sizeof(evt->event_data.tcg2_data.event_header),
> +			.event_header.header_size	= sizeof(ev.tcg2_data.event_header),
>  			.event_header.header_version	= EFI_TCG2_EVENT_HEADER_VERSION,
>  			.event_header.pcr_index		= events[event].pcr_index,
>  			.event_header.event_type	= EV_EVENT_TAG,
>  		};
> +		protocol = tcg2;
> +		method.hash_log_extend_event =
> +			(void *)efi_table_attr(tcg2, hash_log_extend_event);
> +	} else {
> +		efi_guid_t cc_guid = EFI_CC_MEASUREMENT_PROTOCOL_GUID;
> +		efi_cc_protocol_t *cc = NULL;
>  
> -		evt->tagged_event_id		= events[event].event_id;
> -		evt->tagged_event_data_size	= events[event].event_data_len;
> -
> -		memcpy(evt->tagged_event_data, events[event].event_data,
> -		       events[event].event_data_len);
> +		efi_bs_call(locate_protocol, &cc_guid, NULL, (void **)&cc);
> +		if (!cc)
> +			return EFI_UNSUPPORTED;
>  
> -		status = efi_call_proto(tcg2, hash_log_extend_event, 0,
> -					load_addr, load_size, &evt->event_data.tcg2_data);
> -		efi_bs_call(free_pool, evt);
> +		ev.cc_data = (struct efi_cc_event){
> +			.event_size			= size,
> +			.event_header.header_size	= sizeof(ev.cc_data.event_header),
> +			.event_header.header_version	= EFI_CC_EVENT_HEADER_VERSION,
> +			.event_header.event_type	= EV_EVENT_TAG,
> +		};
>  
> +		status = efi_call_proto(cc, map_pcr_to_mr_index,
> +					events[event].pcr_index,
> +					&ev.cc_data.event_header.mr_index);
>  		if (status != EFI_SUCCESS)
>  			goto fail;
> -		return EFI_SUCCESS;
> +
> +		protocol = cc;
> +		method.hash_log_extend_event =
> +			(void *)efi_table_attr(cc, hash_log_extend_event);
>  	}
>  
> -	return EFI_UNSUPPORTED;
> +	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, (void **)&evt);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	evt->event_data			= ev;
> +	evt->tagged_event_id		= events[event].event_id;
> +	evt->tagged_event_data_size	= events[event].event_data_len;
> +
> +	memcpy(evt->tagged_event_data, events[event].event_data,
> +	       events[event].event_data_len);
> +
> +	status = efi_fn_call(&method, hash_log_extend_event, protocol, 0,
> +			     load_addr, load_size, &evt->event_data);
> +	efi_bs_call(free_pool, evt);
> +
> +	if (status == EFI_SUCCESS)
> +		return EFI_SUCCESS;
> +
>  fail:
>  	efi_warn("Failed to measure data for event %d: 0x%lx\n", event, status);
>  	return status;
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index d621bfb719c4..4bf9a76796b7 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -954,8 +954,11 @@ union efi_cc_protocol {
>  	} mixed_mode;
>  };
>  
> +static_assert(sizeof(efi_tcg2_event_t) == sizeof(efi_cc_event_t));
> +
>  union efistub_event {
>  	efi_tcg2_event_t	tcg2_data;
> +	efi_cc_event_t		cc_data;
>  };
>  
>  struct efistub_measured_event {

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer


  parent reply	other threads:[~2024-03-05 21:39 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-04 10:44 [PATCH 0/4] efi/libstub: Fall back to CC proto for measurement Ard Biesheuvel
2024-03-04 10:44 ` [PATCH 1/4] efi/libstub: Fold efi_tcg2_tagged_event into efi_measured_event Ard Biesheuvel
2024-03-05  4:30   ` Kuppuswamy Sathyanarayanan
2024-03-05  8:21     ` Ard Biesheuvel
2024-03-05 19:19       ` Kuppuswamy Sathyanarayanan
2024-03-04 10:44 ` [PATCH 2/4] efi/libstub: Add Confidential Computing (CC) measurement typedefs Ard Biesheuvel
2024-03-05 18:00   ` Ilias Apalodimas
2024-03-05 19:27     ` Kuppuswamy Sathyanarayanan
2024-03-05 19:59       ` Ilias Apalodimas
2024-03-04 10:44 ` [PATCH 3/4] efi/libstub: Measure into CC protocol if TCG2 protocol is absent Ard Biesheuvel
2024-03-05 17:34   ` Dionna Amalie Glaze
2024-03-05 17:47     ` Ard Biesheuvel
2024-03-05 17:55       ` Ilias Apalodimas
2024-03-05 18:00       ` Dionna Amalie Glaze
2024-03-05 18:33         ` Kuppuswamy Sathyanarayanan
2024-03-05 18:46           ` Dionna Amalie Glaze
2024-03-05 19:36             ` Kuppuswamy Sathyanarayanan
2024-03-05 21:28               ` Dionna Amalie Glaze
2024-03-05 21:28             ` Ard Biesheuvel
2024-03-05 21:39   ` Kuppuswamy Sathyanarayanan [this message]
2024-03-04 10:44 ` [PATCH 4/4] efi/libstub: Add get_event_log() support for CC platforms Ard Biesheuvel

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