[PATCH] efi_loader: capsule: remove authentication data

[AKASHI Takahiro]

Please ignore this patch as I mistakenly sent out v1.

-Takahiro Akashi

On Tue, Jul 20, 2021 at 02:44:42PM +0900, AKASHI Takahiro wrote:
> If capsule authentication is disabled and yet a capsule file is signed,
> its signature must be removed from image data to flush.
> Otherwise, the firmware will be corrupted after update.
> 
> Fixes: 04be98bd6bcf ("efi: capsule: Add support for uefi capsule
> 	authentication")
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
>  lib/efi_loader/efi_capsule.c | 70 +++++++++++++++++++++++++++++-------
>  1 file changed, 57 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/efi_loader/efi_capsule.c b/lib/efi_loader/efi_capsule.c
> index b0dffd3ac9ce..5d156c730faa 100644
> --- a/lib/efi_loader/efi_capsule.c
> +++ b/lib/efi_loader/efi_capsule.c
> @@ -206,6 +206,39 @@ skip:
>  	return NULL;
>  }
>  
> +/**
> + * efi_remove_auth_hdr - remove authentication data from image
> + * @image:	Pointer to pointer to Image
> + * @image_size:	Pointer to Image size
> + *
> + * Remove the authentication data from image if possible.
> + * Update @image and @image_size.
> + *
> + * Return:		status code
> + */
> +static efi_status_t efi_remove_auth_hdr(void **image, efi_uintn_t *image_size)
> +{
> +	struct efi_firmware_image_authentication *auth_hdr;
> +	efi_status_t ret = EFI_INVALID_PARAMETER;
> +
> +	auth_hdr = (struct efi_firmware_image_authentication *)*image;
> +	if (*image_size < sizeof(*auth_hdr))
> +		goto out;
> +
> +	if (auth_hdr->auth_info.hdr.dwLength <=
> +	    offsetof(struct win_certificate_uefi_guid, cert_data))
> +		goto out;
> +
> +	*image = (uint8_t *)*image + sizeof(auth_hdr->monotonic_count) +
> +		auth_hdr->auth_info.hdr.dwLength;
> +	*image_size = *image_size - auth_hdr->auth_info.hdr.dwLength -
> +		sizeof(auth_hdr->monotonic_count);
> +
> +	ret = EFI_SUCCESS;
> +out:
> +	return ret;
> +}
> +
>  #if defined(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>  
>  #if defined(CONFIG_EFI_PKEY_DTB_EMBED)
> @@ -271,21 +304,15 @@ efi_status_t efi_capsule_authenticate(const void *capsule, efi_uintn_t capsule_s
>  	if (capsule == NULL || capsule_size == 0)
>  		goto out;
>  
> -	auth_hdr = (struct efi_firmware_image_authentication *)capsule;
> -	if (capsule_size < sizeof(*auth_hdr))
> -		goto out;
> -
> -	if (auth_hdr->auth_info.hdr.dwLength <=
> -	    offsetof(struct win_certificate_uefi_guid, cert_data))
> +	*image = (uint8_t *)capsule;
> +	*image_size = capsule_size;
> +	if (efi_remove_auth_hdr(image, image_size) != EFI_SUCCESS)
>  		goto out;
>  
> +	auth_hdr = (struct efi_firmware_image_authentication *)capsule;
>  	if (guidcmp(&auth_hdr->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
>  		goto out;
>  
> -	*image = (uint8_t *)capsule + sizeof(auth_hdr->monotonic_count) +
> -		auth_hdr->auth_info.hdr.dwLength;
> -	*image_size = capsule_size - auth_hdr->auth_info.hdr.dwLength -
> -		sizeof(auth_hdr->monotonic_count);
>  	memcpy(&monotonic_count, &auth_hdr->monotonic_count,
>  	       sizeof(monotonic_count));
>  
> @@ -367,7 +394,7 @@ static efi_status_t efi_capsule_update_firmware(
>  {
>  	struct efi_firmware_management_capsule_header *capsule;
>  	struct efi_firmware_management_capsule_image_header *image;
> -	size_t capsule_size;
> +	size_t capsule_size, image_binary_size;
>  	void *image_binary, *vendor_code;
>  	efi_handle_t *handles;
>  	efi_uintn_t no_handles;
> @@ -429,13 +456,30 @@ static efi_status_t efi_capsule_update_firmware(
>  		}
>  
>  		/* do update */
> +		if (IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE) &&
> +		    !(image->image_capsule_support &
> +				CAPSULE_SUPPORT_AUTHENTICATION)) {
> +			/* no signature */
> +			ret = EFI_SECURITY_VIOLATION;
> +			goto out;
> +		}
> +
>  		image_binary = (void *)image + sizeof(*image);
> -		vendor_code = image_binary + image->update_image_size;
> +		image_binary_size = image->update_image_size;
> +		vendor_code = image_binary + image_binary_size;
> +		if (!IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE) &&
> +		    (image->image_capsule_support &
> +				CAPSULE_SUPPORT_AUTHENTICATION)) {
> +			ret = efi_remove_auth_hdr(&image_binary,
> +						  &image_binary_size);
> +			if (ret != EFI_SUCCESS)
> +				goto out;
> +		}
>  
>  		abort_reason = NULL;
>  		ret = EFI_CALL(fmp->set_image(fmp, image->update_image_index,
>  					      image_binary,
> -					      image->update_image_size,
> +					      image_binary_size,
>  					      vendor_code, NULL,
>  					      &abort_reason));
>  		if (ret != EFI_SUCCESS) {
> -- 
> 2.31.0
>