On Thu, Sep 16, 2021 at 5:54 PM Chen Yu <yu.c.chen@xxxxxxxxx> wrote:
>
> Platform Firmware Runtime Update image starts with UEFI headers, and the
> headers are defined in UEFI specification, but some of them have not been
> defined in the kernel yet.
>
> For example, the header layout of a capsule file looks like this:
>
> EFI_CAPSULE_HEADER
> EFI_FIRMWARE_MANAGEMENT_CAPSULE_HEADER
> EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER
> EFI_FIRMWARE_IMAGE_AUTHENTICATION
>
> These structures would be used by the Platform Firmware Runtime Update
> driver to parse the format of capsule file to verify if the corresponding
> version number is valid. The EFI_CAPSULE_HEADER has been defined in the
> kernel, however the rest are not, thus introduce corresponding UEFI
> structures accordingly.
>
> The reason why efi_manage_capsule_header_t and
> efi_manage_capsule_image_header_t are packedi might be that:
> According to the uefi spec,
> [Figure 23-6 Firmware Management and Firmware Image Management headers]
> EFI_FIRMWARE_MANAGEMENT_CAPSULE_HEADER is located at the lowest offset
> within the body of the capsule. And this structure is designed to be
> unaligned to save space, because in this way the adjacent drivers and
> binary payload elements could start on byte boundary with no padding.
> And the EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER is at the head of
> each payload, so packing this structure also makes room for more data.
IMO it would be sufficient to say that both
EFI_FIRMWARE_MANAGEMENT_CAPSULE_HEADER and
EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER need not be aligned and
so the corresponding data types should be packed.
>
> Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
> ---
> include/linux/efi.h | 50 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 6b5d36babfcc..19ff834e1388 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -148,6 +148,56 @@ typedef struct {
> u32 imagesize;
> } efi_capsule_header_t;
>
> +#pragma pack(1)
> +
> +/* EFI_FIRMWARE_MANAGEMENT_CAPSULE_HEADER */
> +typedef struct {
> + u32 ver;
> + u16 emb_drv_cnt;
> + u16 payload_cnt;
> + /*
> + * Variable array indicated by number of
> + * (emb_drv_cnt + payload_cnt)
> + */
> + u64 offset_list[];
> +} efi_manage_capsule_header_t;
> +
> +/* EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER */
> +typedef struct {
> + u32 ver;
> + guid_t image_type_id;
> + u8 image_index;
> + u8 reserved_bytes[3];
> + u32 image_size;
> + u32 vendor_code_size;
> + /* ver = 2. */
> + u64 hw_ins;
> + /* ver = v3. */
> + u64 capsule_support;
> +} efi_manage_capsule_image_header_t;
> +
> +#pragma pack()
> +
> +/* WIN_CERTIFICATE */
> +typedef struct {
> + u32 len;
> + u16 rev;
> + u16 cert_type;
> +} win_cert_t;
> +
> +/* WIN_CERTIFICATE_UEFI_GUID */
> +typedef struct {
> + win_cert_t hdr;
> + guid_t cert_type;
> + u8 cert_data[];
> +} win_cert_uefi_guid_t;
> +
> +/* EFI_FIRMWARE_IMAGE_AUTHENTICATIO */
> +typedef struct {
> + u64 mon_count;
> + win_cert_uefi_guid_t auth_info;
> +} efi_image_auth_t;
> +
> /*
> * EFI capsule flags
> */
> --
> 2.25.1
>
