[PATCH v6 2/8] efi_loader: store firmware version into FmpState variable
Heinrich Schuchardt
xypron.glpk at gmx.de
Sun May 28 10:39:19 CEST 2023
On 5/19/23 12:32, Masahisa Kojima wrote:
> Firmware version management is not implemented in the current
> FMP protocol.
> EDK II reference implementation capsule generation script inserts
> the FMP Payload Header right before the payload, FMP Payload Header
> contains the firmware version and lowest supported version.
>
> This commit utilizes the FMP Payload Header, reads the header and
> stores the firmware version into "FmpStateXXXX" EFI non-volatile variable.
> XXXX indicates the image index, since FMP protocol handles multiple
> image indexes.
> Note that lowest supported version included in the FMP Payload Header
> is not used. If the platform uses file-based EFI variable storage,
> it can be tampered. The file-based EFI variable storage is not the
> right place to store the lowest supported version for anti-rollback
> protection.
>
> This change is compatible with the existing FMP implementation.
> This change does not mandate the FMP Payload Header.
> If no FMP Payload Header is found in the capsule file, fw_version,
> lowest supported version, last attempt version and last attempt
> status is 0 and this is the same behavior as existing FMP
> implementation.
>
> Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> ---
> Changed in v6:
> - only store the fw_version in the FmpState EFI variable
>
> Changes in v4:
> - move lines that are the same in both branches out of the if statement
> - s/EDK2/EDK II/
> - create print result function
> - set last_attempt_version when capsule authentication failed
> - use log_err() instead of printf()
>
> Changes in v3:
> - exclude CONFIG_FWU_MULTI_BANK_UPDATE case
> - set image_type_id as a vendor field of FmpStateXXXX variable
> - set READ_ONLY flag for FmpStateXXXX variable
> - add error code for FIT image case
>
> Changes in v2:
> - modify indent
>
> lib/efi_loader/efi_firmware.c | 161 ++++++++++++++++++++++++++++++----
> 1 file changed, 146 insertions(+), 15 deletions(-)
>
> diff --git a/lib/efi_loader/efi_firmware.c b/lib/efi_loader/efi_firmware.c
> index cc650e1443..fc085e3c08 100644
> --- a/lib/efi_loader/efi_firmware.c
> +++ b/lib/efi_loader/efi_firmware.c
> @@ -10,6 +10,7 @@
> #include <charset.h>
> #include <dfu.h>
> #include <efi_loader.h>
> +#include <efi_variable.h>
> #include <fwu.h>
> #include <image.h>
> #include <signatures.h>
> @@ -36,11 +37,52 @@ struct fmp_payload_header {
> u32 lowest_supported_version;
> };
>
> +/**
> + * struct fmp_state - fmp firmware update state
> + *
> + * This structure describes the state of the firmware update
> + * through FMP protocol.
> + *
> + * @fw_version: Firmware versions used
> + * @lowest_supported_version: Lowest supported version
> + * @last_attempt_version: Last attempt version
> + * @last_attempt_status: Last attempt status
> + */
> +struct fmp_state {
> + u32 fw_version;
> + u32 lowest_supported_version; /* not used */
> + u32 last_attempt_version; /* not used */
> + u32 last_attempt_status; /* not used */
> +};
> +
> __weak void set_dfu_alt_info(char *interface, char *devstr)
> {
> env_set("dfu_alt_info", update_info.dfu_string);
> }
>
> +/**
> + * efi_firmware_get_image_type_id - get image_type_id
> + * @image_index: image index
> + *
> + * Return the image_type_id identified by the image index.
> + *
> + * Return: pointer to the image_type_id, NULL if image_index is invalid
> + */
> +static
> +efi_guid_t *efi_firmware_get_image_type_id(u8 image_index)
> +{
> + int i;
> + struct efi_fw_image *fw_array;
> +
> + fw_array = update_info.images;
> + for (i = 0; i < update_info.num_images; i++) {
> + if (fw_array[i].image_index == image_index)
> + return &fw_array[i].image_type_id;
> + }
> +
> + return NULL;
> +}
> +
> /* Place holder; not supported */
> static
> efi_status_t EFIAPI efi_firmware_get_image_unsupported(
> @@ -194,8 +236,6 @@ efi_status_t efi_firmware_capsule_authenticate(const void **p_image,
> {
> const void *image = *p_image;
> efi_uintn_t image_size = *p_image_size;
> - u32 fmp_hdr_signature;
> - struct fmp_payload_header *header;
> void *capsule_payload;
> efi_status_t status;
> efi_uintn_t capsule_payload_size;
> @@ -222,24 +262,107 @@ efi_status_t efi_firmware_capsule_authenticate(const void **p_image,
> debug("Updating capsule without authenticating.\n");
> }
>
> - fmp_hdr_signature = FMP_PAYLOAD_HDR_SIGNATURE;
> - header = (void *)image;
> + *p_image = image;
> + *p_image_size = image_size;
> + return EFI_SUCCESS;
> +}
> +
> +/**
> + * efi_firmware_set_fmp_state_var - set FmpStateXXXX variable
> + * @state: Pointer to fmp state
> + * @image_index: image index
> + *
> + * Update the FmpStateXXXX variable with the firmware update state.
> + *
> + * Return: status code
> + */
> +static
> +efi_status_t efi_firmware_set_fmp_state_var(struct fmp_state *state, u8 image_index)
> +{
> + u16 varname[13]; /* u"FmpStateXXXX" */
> + efi_status_t ret;
> + efi_guid_t *image_type_id;
> + struct fmp_state var_state = { 0 };
> +
> + image_type_id = efi_firmware_get_image_type_id(image_index);
> + if (!image_type_id)
> + return EFI_INVALID_PARAMETER;
> +
> + efi_create_indexed_name(varname, sizeof(varname), "FmpState",
> + image_index);
> +
> + /*
> + * Only the fw_version is set here.
> + * lowest_supported_version in FmpState variable is ignored since
> + * it can be tampered if the file based EFI variable storage is used.
> + */
> + var_state.fw_version = state->fw_version;
> +
> + ret = efi_set_variable_int(varname, image_type_id,
> + EFI_VARIABLE_READ_ONLY |
> + EFI_VARIABLE_NON_VOLATILE |
> + EFI_VARIABLE_BOOTSERVICE_ACCESS |
> + EFI_VARIABLE_RUNTIME_ACCESS,
> + sizeof(var_state), &var_state, false);
> +
> + return ret;
> +}
> +
> +/**
> + * efi_firmware_get_fw_version - get fw_version from FMP payload header
> + * @p_image: Pointer to new image
> + * @p_image_size: Pointer to size of new image
> + * @state Pointer to fmp state
Due to the missing colon this leads to a build failure for 'make htmldocs':
./lib/efi_loader/efi_firmware.c:401: warning: Function parameter or
member 'state' not described in 'efi_firmware_get_fw_version'
> + *
> + * Parse the FMP payload header and fill the fmp_state structure.
> + * If no FMP payload header is found, fmp_state structure is not updated.
> + *
> + */
> +static void efi_firmware_get_fw_version(const void **p_image,
> + efi_uintn_t *p_image_size,
> + struct fmp_state *state)
> +{
> + const void *image = *p_image;
> + efi_uintn_t image_size = *p_image_size;
> + const struct fmp_payload_header *header;
> + u32 fmp_hdr_signature = FMP_PAYLOAD_HDR_SIGNATURE;
> +
> + header = image;
> + if (header->signature == fmp_hdr_signature) {
> + /* FMP header is inserted above the capsule payload */
> + state->fw_version = header->fw_version;
>
> - if (!memcmp(&header->signature, &fmp_hdr_signature,
> - sizeof(fmp_hdr_signature))) {
> - /*
> - * When building the capsule with the scripts in
> - * edk2, a FMP header is inserted above the capsule
> - * payload. Compensate for this header to get the
> - * actual payload that is to be updated.
> - */
> image += header->header_size;
> image_size -= header->header_size;
> }
>
> *p_image = image;
> *p_image_size = image_size;
> - return EFI_SUCCESS;
> +}
> +
> +/**
> + * efi_firmware_verify_image - verify image
> + * @p_image: Pointer to new image
> + * @p_image_size: Pointer to size of new image
> + * @image_index Image index
> + * @state Pointer to fmp state
Due to the missing colons this leads to a build failure for 'make htmldocs':
./lib/efi_loader/efi_firmware.c:437: warning: Function parameter or
member 'image_index' not described in 'efi_firmware_verify_image'
./lib/efi_loader/efi_firmware.c:437: warning: Function parameter or
member 'state' not described in 'efi_firmware_verify_image'
Best regards
Heinrich
> + *
> + * Verify the capsule file
> + *
> + * Return: status code
> + */
> +static
> +efi_status_t efi_firmware_verify_image(const void **p_image,
> + efi_uintn_t *p_image_size,
> + u8 image_index,
> + struct fmp_state *state)
> +{
> + efi_status_t ret;
> +
> + ret = efi_firmware_capsule_authenticate(p_image, p_image_size);
> + efi_firmware_get_fw_version(p_image, p_image_size, state);
> +
> + return ret;
> }
>
> /**
> @@ -331,6 +454,7 @@ efi_status_t EFIAPI efi_firmware_fit_set_image(
> u16 **abort_reason)
> {
> efi_status_t status;
> + struct fmp_state state = { 0 };
>
> EFI_ENTRY("%p %d %p %zu %p %p %p\n", this, image_index, image,
> image_size, vendor_code, progress, abort_reason);
> @@ -338,13 +462,16 @@ efi_status_t EFIAPI efi_firmware_fit_set_image(
> if (!image || image_index != 1)
> return EFI_EXIT(EFI_INVALID_PARAMETER);
>
> - status = efi_firmware_capsule_authenticate(&image, &image_size);
> + status = efi_firmware_verify_image(&image, &image_size, image_index,
> + &state);
> if (status != EFI_SUCCESS)
> return EFI_EXIT(status);
>
> if (fit_update(image))
> return EFI_EXIT(EFI_DEVICE_ERROR);
>
> + efi_firmware_set_fmp_state_var(&state, image_index);
> +
> return EFI_EXIT(EFI_SUCCESS);
> }
>
> @@ -392,6 +519,7 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
> {
> int ret;
> efi_status_t status;
> + struct fmp_state state = { 0 };
>
> EFI_ENTRY("%p %d %p %zu %p %p %p\n", this, image_index, image,
> image_size, vendor_code, progress, abort_reason);
> @@ -399,7 +527,8 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
> if (!image)
> return EFI_EXIT(EFI_INVALID_PARAMETER);
>
> - status = efi_firmware_capsule_authenticate(&image, &image_size);
> + status = efi_firmware_verify_image(&image, &image_size, image_index,
> + &state);
> if (status != EFI_SUCCESS)
> return EFI_EXIT(status);
>
> @@ -419,6 +548,8 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
> NULL, NULL))
> return EFI_EXIT(EFI_DEVICE_ERROR);
>
> + efi_firmware_set_fmp_state_var(&state, image_index);
> +
> return EFI_EXIT(EFI_SUCCESS);
> }
>
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