The FMP Payload Header which EDK2 capsule generation scripts
insert contains lowest supported version.
This commit reads the lowest supported version stored in the
"FmpStateXXXX" EFI non-volatile variable, then check if the
firmware version of ongoing capsule is equal or greater than
the lowest supported version.
Signed-off-by: Masahisa Kojima <masahisa.koj...@linaro.org>
---
lib/efi_loader/efi_firmware.c | 43 ++++++++++++++++++++++++++++++++++-
1 file changed, 42 insertions(+), 1 deletion(-)
diff --git a/lib/efi_loader/efi_firmware.c b/lib/efi_loader/efi_firmware.c
index 1d63804717..8bbbb3f081 100644
--- a/lib/efi_loader/efi_firmware.c
+++ b/lib/efi_loader/efi_firmware.c
@@ -368,6 +368,34 @@ void efi_firmware_parse_payload_header(const void
**p_image,
*p_image_size = image_size;
}
+/**
+ * efi_firmware_get_lowest_supported_version - get the lowest supported version
+ * @image_index: image_index
+ *
+ * Get the lowest supported version from FmpStateXXXX variable.
+ *
+ * Return: lowest supported version, return 0 if reading
FmpStateXXXX
+ * variable failed
+ */
+static
+u32 efi_firmware_get_lowest_supported_version(u8 image_index)
+{
+ u16 varname[13]; /* u"FmpStateXXXX" */
+ efi_status_t ret;
+ efi_uintn_t size;
+ struct fmp_state var_state = { 0 };
+
+ efi_create_indexed_name(varname, sizeof(varname), "FmpState",
+ image_index);
+ size = sizeof(var_state);
+ ret = efi_get_variable_int(varname, &efi_guid_fmp_state, NULL, &size,
+ &var_state, NULL);
+ if (ret != EFI_SUCCESS)
+ return 0;
+
+ return var_state.lowest_supported_version;
+}
+
/**
* efi_firmware_verify_image - verify image
* @p_image: Pointer to new image
@@ -375,7 +403,8 @@ void efi_firmware_parse_payload_header(const void **p_image,
* @image_index Image index
* @state Pointer to fmp state
*
- * Verify the capsule file
+ * Verify the capsule authentication and check if the fw_version
+ * is equal or greater than the lowest supported version.
*
* Return: status code
*/
@@ -386,10 +415,22 @@ efi_status_t efi_firmware_verify_image(const void
**p_image,
struct fmp_state *state)
{
efi_status_t ret;
+ u32 lowest_supported_version;
ret = efi_firmware_capsule_authenticate(p_image, p_image_size, state);
efi_firmware_parse_payload_header(p_image, p_image_size, state);
+ /* check lowest_supported_version if capsule authentication passes */
+ if (ret == EFI_SUCCESS) {
+ lowest_supported_version =
+ efi_firmware_get_lowest_supported_version(image_index);
+ if (lowest_supported_version > state->fw_version) {
+ state->last_attempt_status =
+ LAST_ATTEMPT_STATUS_ERROR_INCORRECT_VERSION;
+ ret = EFI_INVALID_PARAMETER;
+ }
+ }
+
return ret;
}
--
2.17.1
