Rough first draft of the firmware signing utility.

utility/sign_image.c

+/* 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.
+ *
+ * Utility for signing boot firmware images.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "file_keys.h"
+#include "utility.h"
+#include "host_key.h"
+#include "host_signature.h"
+#include "host_common.h"
+
+static void usage()
+{
+  static char* help_mesg =
+      "Usage: sign_image <fw_version> <fw_key_block> <signing_key> "
+      "<kernel_public_key> <firmware_file> <output_file>\n";
+  printf(help_mesg);
+}
+
+int SignAndWriteImage(uint64_t fw_version, VbKeyBlockHeader* wrapper_kb,
+                      VbPrivateKey* signing_key,
+                      VbPublicKey* nested_pubkey,
+                      uint8_t* image, uint64_t image_size,
+                      FILE* out_file)
+{
+  VbFirmwarePreambleHeader* fw_preamble = NULL;
+  int rv = 1;
+  do { /* to be able to bail out anywhere */
+    VbSignature* firmware_sig;
+
+    /* sign the firmware first */
+    firmware_sig = CalculateSignature(image, image_size, signing_key);
+
+    /* write the original keyblock */
+    if (fwrite(wrapper_kb, wrapper_kb->key_block_size, 1, out_file) != 1) {
+      debug("failed writing key block\n");
+      break;
+    }
+
+    fw_preamble = CreateFirmwarePreamble(fw_version, nested_pubkey,
+                                         firmware_sig, signing_key);
+
+    if (!fw_preamble) {
+      debug("failed creating preamble\n");
+      break;
+    }
+
+    /* write the preamble */
+    if (fwrite(fw_preamble, fw_preamble->preamble_size, 1, out_file) != 1) {
+      debug("failed writing fw preamble\n");
+      break;
+    }
+
+    /* write the image */
+    if (fwrite(image, image_size, 1, out_file) != 1) {
+      debug("failed writing image\n");
+      break;
+    }
+    rv = 0;
+  } while(0);
+
+  if (fw_preamble) {
+    Free(fw_preamble);
+  }
+
+  return rv;
+}
+
+int main(int argc, char* argv[]) {
+  VbKeyBlockHeader* firmware_kb;
+  VbPublicKey* kernel_pubk;
+  uint8_t* firmware;
+  uint64_t fw_size;
+  uint64_t version;
+  VbPrivateKey* signing_key = NULL;
+  FILE* out_file;
+  int rv;
+
+  if (argc != 7) {
+    usage();
+    exit(1);
+  }
+
+  version = strtoul(argv[1], 0, 0);
+  firmware_kb = KeyBlockRead(argv[2]);
+  kernel_pubk = PublicKeyRead(argv[4]);
+  firmware = BufferFromFile(argv[5], &fw_size);
+  if (firmware_kb) {
+    signing_key = PrivateKeyRead(argv[3], firmware_kb->data_key.algorithm);
+  }
+  if (!firmware_kb || !kernel_pubk || !firmware || ! signing_key) {
+    return 1;
+  }
+
+  out_file = fopen(argv[6], "wb");
+  if (!out_file) {
+    debug("could not open %s for writing\n");
+    return 1;
+  }
+
+  rv = SignAndWriteImage(version, firmware_kb, signing_key,
+                         kernel_pubk, firmware, fw_size, out_file);
+
+  fclose(out_file);
+  if (rv) {
+    unlink(argv[6]);
+  }
+  return rv;
+}