Make kernel signature a part of the kernel preamble.

src/platform/vboot_reference/vboot_firmware/include/kernel_image_fw.h

 /* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * Data structure and API definitions for a verified boot kernel image.
  * (Firmware Portion)
  */
 
 #ifndef VBOOT_REFERENCE_KERNEL_IMAGE_FW_H_
 #define VBOOT_REFERENCE_KERNEL_IMAGE_FW_H_
@@ skipping 31 matching lines @@
                                                  * key_version] */
   /* End of kernel key header. */
   uint8_t* kernel_key_signature;   /* Signature of the header above. */
 
   /* Kernel preamble */
   uint16_t kernel_version;  /* Kernel Version# for preventing rollbacks. */
   uint64_t kernel_len;  /* Length of the actual kernel image. */
   uint64_t bootloader_offset;  /* Offset of bootloader in kernel_data. */
   uint64_t bootloader_size;  /* Size of bootloader in bytes. */
   uint64_t padded_header_size;  /* start of kernel_data in disk partition */
+  uint8_t* kernel_signature;  /* Signature on [kernel_data] below.
+                               * NOTE: This is only considered valid
+                               * if preamble_signature successfully verifies. */
   /* end of preamble */
-
-  uint8_t* preamble_signature;  /* Signature on the kernel preamble. */
-
-  /* The kernel signature comes first as it may allow us to parallelize
-   * the kernel data fetch and RSA public key operation.
-   */
-  uint8_t* kernel_signature;  /* Signature on the concatenation of
-                               * the kernel preamble and [kernel_data]. */
+  uint8_t* preamble_signature;  /* signature on preamble, (includes
+                                   [kernel_signature]) */
   uint8_t* kernel_data;  /* Actual kernel data. */
 
 } KernelImage;
 
 /* Error Codes for VerifyFirmware. */
 #define VERIFY_KERNEL_SUCCESS 0
 #define VERIFY_KERNEL_INVALID_IMAGE 1
 #define VERIFY_KERNEL_KEY_SIGNATURE_FAILED 2
 #define VERIFY_KERNEL_INVALID_ALGORITHM 3
 #define VERIFY_KERNEL_PREAMBLE_SIGNATURE_FAILED 4
 #define VERIFY_KERNEL_SIGNATURE_FAILED 5
 #define VERIFY_KERNEL_WRONG_MAGIC 6
 #define VERIFY_KERNEL_MAX 7  /* Generic catch-all. */
 
 extern char* kVerifyKernelErrors[VERIFY_KERNEL_MAX];
 
-/* Returns the length of the verified boot kernel preamble. */
-uint64_t GetKernelPreambleLen(void);
+/* Returns the length of the verified boot kernel preamble based on
+ * kernel signing algorithm [algorithm]. */
+uint64_t GetKernelPreambleLen(int algorithm);
 
 /* Returns the length of the Kernel Verified Boot header excluding
  * [kernel_data].
  *
  * This is always non-zero, so a return value of 0 signifies an error.
  */
 uint64_t GetVBlockHeaderSize(const uint8_t* vkernel_blob);
 
 /* Checks for the sanity of the kernel key header at [kernel_header_blob].
  * If [dev_mode] is enabled, also checks the kernel key signature using the
@@ skipping 15 matching lines @@
  * using the signing key [kernel_sign_key].
  *
  * On success, put kernel length into [kernel_len], and return 0.
  * Else, return error code on failure.
  */
 int VerifyKernelPreamble(RSAPublicKey* kernel_sign_key,
                          const uint8_t* kernel_preamble_blob,
                          int algorithm,
                          uint64_t* kernel_len);
 
-/* Checks the signature on the kernel data at location [kernel_data_start].
- * The length of the actual kernel data is kernel_len and it is assumed to
- * be prepended with the signature whose size depends on the signature_algorithm
- * [algorithm].
+/* Checks [kernel_signature] on the kernel data at location [kernel_data]. The
+ * signature is assumed to be generated using algorithm [algorithm].
+ * The length of the kernel data is [kernel_len].
  *
  * Return 0 on success, error code on failure.
  */
 int VerifyKernelData(RSAPublicKey* kernel_sign_key,
-                     const uint8_t* kernel_config_start,
-                     const uint8_t* kernel_data_start,
+                     const uint8_t* kernel_signature,
+                     const uint8_t* kernel_data,
                      uint64_t kernel_len,
                      int algorithm);
 
 /* Verifies the kernel key header and preamble at [kernel_header_blob]
  * using the firmware public key [firmware_key_blob]. If [dev_mode] is 1
  * (active), then key header verification is skipped.
  *
- * Fills in a pointer to preamble blob within [kernel_header_blob] in
- * [preamble_blob], pointer to expected kernel data signature
+ * Fills in a pointer to expected kernel data signature
  * within [kernel_header_blob] in [expected_kernel_signature].
  *
  * The signing key to use for kernel data verification is returned in
  * [kernel_sign_key], This must be free-d explicitly by the caller after use.
  * The kernel signing algorithm is returned in [kernel_sign_algorithm] and its
  * length in [kernel_len].
  *
  * Returns 0 on success, error code on failure.
  */
 int VerifyKernelHeader(const uint8_t* firmware_key_blob,
                        const uint8_t* kernel_header_blob,
                        const int dev_mode,
-                       const uint8_t** preamble_blob,
                        const uint8_t** expected_kernel_signature,
                        RSAPublicKey** kernel_sign_key,
                        int* kernel_sign_algorithm,
                        uint64_t* kernel_len);
 
 /* Performs a chained verify of the kernel blob [kernel_blob]. If
  * [dev_mode] is 0 [inactive], then the pre-processed public signing key
  * [root_key_blob] is used to verify the signature of the signing key,
  * else the check is skipped.
  *
@@ skipping 42 matching lines @@
  * BOOT_KERNEL_A_CONTINUE          Boot from Kenrel A
  * BOOT_KERNEL_B_CONTINUE          Boot from Kernel B
  * BOOT_KERNEL_RECOVERY_CONTINUE   Jump to recovery mode
  */
 int VerifyKernelDriver_f(uint8_t* firmware_key_blob,
                          kernel_entry* kernelA,
                          kernel_entry* kernelB,
                          int dev_mode);
 
 #endif  /* VBOOT_REFERENCE_KERNEL_IMAGE_FW_H_ */