Add --subkey_in and --subkey_out options to firmware signing utility.

src/platform/vboot_reference/utility/firmware_utility.cc

Index: src/platform/vboot_reference/utility/firmware_utility.cc
diff --git a/src/platform/vboot_reference/utility/firmware_utility.cc b/src/platform/vboot_reference/utility/firmware_utility.cc
index b152ee1cda5dc78c654f871d21c57e4b17962ef3..aaf936b2c09f4d23c75b7e22b803dec0d236cde5 100644
--- a/src/platform/vboot_reference/utility/firmware_utility.cc
+++ b/src/platform/vboot_reference/utility/firmware_utility.cc
@@ -19,23 +19,28 @@ extern "C" {
 #include "cryptolib.h"
 #include "file_keys.h"
 #include "firmware_image.h"
-#include "utility.h"
+#include "stateful_util.h"
 }
 
 using std::cerr;
 
+// Macro to determine the size of a field structure in the FirmwareImage
+// structure.
+#define FIELD_LEN(field) (sizeof(((FirmwareImage*)0)->field))
+
 namespace vboot_reference {
 
 FirmwareUtility::FirmwareUtility():
     image_(NULL),
     root_key_pub_(NULL),
-    firmware_version_(-1),
     firmware_key_version_(-1),
     firmware_sign_algorithm_(-1),
+    firmware_version_(-1),
     is_generate_(false),
     is_verify_(false),
     is_describe_(false),
-    is_only_vblock_(false) {
+    is_only_vblock_(false),
+    is_subkey_out_(false) {
 }
 
 FirmwareUtility::~FirmwareUtility() {
@@ -50,23 +55,27 @@ void FirmwareUtility::PrintUsage(void) {
       "Usage: firmware_utility <--generate|--verify> [OPTIONS]\n"
       "\n"
       "For \"--verify\",  required OPTIONS are:\n"
-      "--in <infile>\t\t\tVerified boot firmware image to verify.\n"
-      "--root_key_pub <pubkeyfile>\tPre-processed public root key "
+      "  --in <infile>\t\t\tVerified boot firmware image to verify.\n"
+      "  --root_key_pub <pubkeyfile>\tPre-processed public root key "
       "to use for verification.\n"
       "\n"
       "For \"--generate\", required OPTIONS are:\n"
-      "--root_key <privkeyfile>\tPrivate root key file\n"
-      "--firmware_sign_key <privkeyfile>\tPrivate signing key file\n"
-      "--firmware_sign_key_pub <pubkeyfile>\tPre-processed public signing"
+      "  --root_key <privkeyfile>\t\tPrivate root key file\n"
+      "  --firmware_key_pub <pubkeyfile>\tPre-processed public signing"
       " key\n"
-      "--firmware_sign_algorithm <algoid>\tSigning algorithm to use\n"
-      "--firmware_key_version <version#>\tSigning Key Version#\n"
-      "--firmware_version <version#>\tFirmware Version#\n"
-      "--in <infile>\t\t\tFirmware Image to sign\n"
-      "--out <outfile>\t\t\tOutput file for verified boot firmware image\n"
+      "  --firmware_sign_algorithm <algoid>\tSigning algorithm to use\n"
+      "  --firmware_key_version <version#>\tSigning Key Version#\n"
+      "OR\n"
+      "  --subkey_in <subkeyfile>\t\tExisting key signature header\n"
+      "\n"
+      "  --firmware_key <privkeyfile>\tPrivate signing key file\n"
+      "  --firmware_version <version#>\tFirmware Version#\n"
+      "  --in <infile>\t\t\tFirmware Image to sign\n"
+      "  --out <outfile>\t\tOutput file for verified boot firmware image\n"
       "\n"
       "Optional:\n"
-      " --vblock\t\t\tJust output the verification block\n"
+      "  --subkey_out\t\t\tJust output the subkey (key verification) header\n"
+      "  --vblock\t\t\tJust output the verification block\n"
       "\n"
       "<algoid> (for --sign-algorithm) is one of the following:\n";
   for (int i = 0; i < kNumAlgorithms; i++) {
@@ -83,6 +92,7 @@ bool FirmwareUtility::ParseCmdLineOptions(int argc, char* argv[]) {
     OPT_ROOT_KEY_PUB,
     OPT_FIRMWARE_KEY,
     OPT_FIRMWARE_KEY_PUB,
+    OPT_SUBKEY_IN,
     OPT_FIRMWARE_SIGN_ALGORITHM,
     OPT_FIRMWARE_KEY_VERSION,
     OPT_FIRMWARE_VERSION,
@@ -92,12 +102,14 @@ bool FirmwareUtility::ParseCmdLineOptions(int argc, char* argv[]) {
     OPT_VERIFY,
     OPT_DESCRIBE,
     OPT_VBLOCK,
+    OPT_SUBKEY_OUT,
   };
   static struct option long_options[] = {
     {"root_key", 1, 0,                  OPT_ROOT_KEY                },
     {"root_key_pub", 1, 0,              OPT_ROOT_KEY_PUB            },
     {"firmware_key", 1, 0,              OPT_FIRMWARE_KEY            },
     {"firmware_key_pub", 1, 0,          OPT_FIRMWARE_KEY_PUB        },
+    {"subkey_in", 1, 0,                 OPT_SUBKEY_IN               },
     {"firmware_sign_algorithm", 1, 0,   OPT_FIRMWARE_SIGN_ALGORITHM },
     {"firmware_key_version", 1, 0,      OPT_FIRMWARE_KEY_VERSION    },
     {"firmware_version", 1, 0,          OPT_FIRMWARE_VERSION        },
@@ -107,6 +119,7 @@ bool FirmwareUtility::ParseCmdLineOptions(int argc, char* argv[]) {
     {"verify", 0, 0,                    OPT_VERIFY                  },
     {"describe", 0, 0,                  OPT_DESCRIBE                },
     {"vblock", 0, 0,                    OPT_VBLOCK                  },
+    {"subkey_out", 0, 0,                OPT_SUBKEY_OUT              },
     {NULL, 0, 0, 0}
   };
   while ((i = getopt_long(argc, argv, "", long_options, &option_index)) != -1) {
@@ -126,6 +139,9 @@ bool FirmwareUtility::ParseCmdLineOptions(int argc, char* argv[]) {
       case OPT_FIRMWARE_KEY_PUB:
         firmware_key_pub_file_ = optarg;
         break;
+      case OPT_SUBKEY_IN:
+        subkey_in_file_ = optarg;
+        break;
       case OPT_FIRMWARE_SIGN_ALGORITHM:
         firmware_sign_algorithm_ = strtol(optarg, &e, 0);
         if (!*optarg || (e && *e)) {
@@ -171,6 +187,9 @@ bool FirmwareUtility::ParseCmdLineOptions(int argc, char* argv[]) {
       case OPT_VBLOCK:
         is_only_vblock_ = true;
         break;
+      case OPT_SUBKEY_OUT:
+        is_subkey_out_ = true;
+        break;
     }
   }
   return CheckOptions();
@@ -179,7 +198,9 @@ bool FirmwareUtility::ParseCmdLineOptions(int argc, char* argv[]) {
 
 void FirmwareUtility::OutputSignedImage(void) {
   if (image_) {
-    if (!WriteFirmwareImage(out_file_.c_str(), image_, is_only_vblock_)) {
+    if (!WriteFirmwareImage(out_file_.c_str(), image_,
+                            is_only_vblock_,
+                            is_subkey_out_)) {
         cerr << "Couldn't write verified boot image to file "
                   << out_file_ <<".\n";
     }
@@ -196,27 +217,106 @@ void FirmwareUtility::DescribeSignedImage(void) {
 
 bool FirmwareUtility::GenerateSignedImage(void) {
   uint64_t firmware_sign_key_pub_len;
-  image_ = FirmwareImageNew();
 
+  image_ = FirmwareImageNew();
   Memcpy(image_->magic, FIRMWARE_MAGIC, FIRMWARE_MAGIC_SIZE);
 
-  // Copy pre-processed public signing key.
-  image_->firmware_sign_algorithm = (uint16_t) firmware_sign_algorithm_;
-  image_->firmware_sign_key = BufferFromFile(
-      firmware_key_pub_file_.c_str(),
-      &firmware_sign_key_pub_len);
-  if (!image_->firmware_sign_key)
-    return false;
-  image_->firmware_key_version = firmware_key_version_;
+  if (subkey_in_file_.empty()) {
+    // We muse generate the firmware key signature header (subkey header)
+    // ourselves.
+    // Copy pre-processed public signing key.
+    image_->firmware_sign_algorithm = (uint16_t) firmware_sign_algorithm_;
+    image_->firmware_sign_key = BufferFromFile(
+        firmware_key_pub_file_.c_str(),
+        &firmware_sign_key_pub_len);
+    if (!image_->firmware_sign_key)
+      return false;
+    image_->firmware_key_version = firmware_key_version_;
+
+    // Update header length.
+    image_->header_len = GetFirmwareHeaderLen(image_);
 
-  // Update header length.
-  image_->header_len = GetFirmwareHeaderLen(image_);
+    // Calculate header checksum.
+    CalculateFirmwareHeaderChecksum(image_, image_->header_checksum);
 
-  // Calculate header checksum.
-  CalculateFirmwareHeaderChecksum(image_, image_->header_checksum);
+    image_->firmware_version = firmware_version_;
+    image_->firmware_len = 0;
+
+    // Generate and add the key signatures.
+    if (!AddFirmwareKeySignature(image_, root_key_file_.c_str())) {
+      cerr << "Couldn't write key signature to verified boot image.\n";
+      return false;
+    }
+  } else {
+    // Use existing subkey header.
+    MemcpyState st;
+    uint8_t* subkey_header_buf = NULL;
+    uint64_t subkey_len;
+    int header_len;
+    int firmware_sign_key_len;
+    uint8_t header_checksum[FIELD_LEN(header_checksum)];
+
+    subkey_header_buf = BufferFromFile(subkey_in_file_.c_str(), &subkey_len);
+    if (!subkey_header_buf) {
+      cerr << "Couldn't read subkey header from file %s\n"
+           << subkey_in_file_.c_str();
+      return false;
+    }
+    st.remaining_len = subkey_len;
+    st.remaining_buf = subkey_header_buf;
+    st.overrun = 0;
+
+    // TODO(gauravsh): This is basically the same code as the first half of
+    // of ReadFirmwareImage(). Refactor to eliminate code duplication.
+
+    StatefulMemcpy(&st, &image_->header_len, FIELD_LEN(header_len));
+    StatefulMemcpy(&st, &image_->firmware_sign_algorithm,
+                   FIELD_LEN(firmware_sign_algorithm));
+
+    // Valid Algorithm?
+    if (image_->firmware_sign_algorithm >= kNumAlgorithms) {
+      Free(subkey_header_buf);
+      return NULL;
+    }
+
+    // Compute size of pre-processed RSA public key and signature.
+    firmware_sign_key_len = RSAProcessedKeySize(image_->firmware_sign_algorithm);
+
+    // Check whether the header length is correct.
+    header_len = GetFirmwareHeaderLen(image_);
+    if (header_len != image_->header_len) {
+      debug("Header length mismatch. Got: %d Expected: %d\n",
+            image_->header_len, header_len);
+      Free(subkey_header_buf);
+      return NULL;
+    }
+
+    // Read pre-processed public half of the sign key.
+    StatefulMemcpy(&st, &image_->firmware_key_version,
+                 FIELD_LEN(firmware_key_version));
+    image_->firmware_sign_key = (uint8_t*) Malloc(firmware_sign_key_len);
+    StatefulMemcpy(&st, image_->firmware_sign_key, firmware_sign_key_len);
+    StatefulMemcpy(&st, image_->header_checksum, FIELD_LEN(header_checksum));
+
+    // Check whether the header checksum matches.
+    CalculateFirmwareHeaderChecksum(image_, header_checksum);
+    if (SafeMemcmp(header_checksum, image_->header_checksum,
+                   FIELD_LEN(header_checksum))) {
+      debug("Invalid firmware header checksum!\n");
+      Free(subkey_header_buf);
+      return NULL;
+    }
+
+    // Read key signature.
+    StatefulMemcpy(&st, image_->firmware_key_signature,
+                   FIELD_LEN(firmware_key_signature));
+
+    Free(subkey_header_buf);
+    if (st.overrun || st.remaining_len != 0)  // Overrun or underrun.
+      return false;
+    return true;
+  }
 
-  image_->firmware_version = firmware_version_;
-  image_->firmware_len = 0;
   // TODO(gauravsh): Populate this with the right bytes once we decide
   // what goes into the preamble.
   Memset(image_->preamble, 'P', FIRMWARE_PREAMBLE_SIZE);
@@ -224,11 +324,6 @@ bool FirmwareUtility::GenerateSignedImage(void) {
                                          &image_->firmware_len);
   if (!image_->firmware_data)
     return false;
-  // Generate and add the signatures.
-  if (!AddFirmwareKeySignature(image_, root_key_file_.c_str())) {
-    cerr << "Couldn't write key signature to verified boot image.\n";
-    return false;
-  }
 
   if (!AddFirmwareSignature(image_, firmware_key_file_.c_str())) {
     cerr << "Couldn't write firmware signature to verified boot image.\n";
@@ -279,30 +374,34 @@ bool FirmwareUtility::CheckOptions(void) {
   }
   // Required options for --generate.
   if (is_generate_) {
-    if (root_key_file_.empty()) {
-      cerr << "No root key file specified." << "\n";
-      return false;
-    }
-    if (firmware_version_ <= 0 || firmware_version_ > UINT16_MAX) {
-      cerr << "Invalid or no firmware version specified." << "\n";
-      return false;
+    if (subkey_in_file_.empty()) {
+      // Root key, kernel signing public key, and firmware signing
+      // algorithm are required to generate the key signature header.
+      if (root_key_file_.empty()) {
+        cerr << "No root key file specified." << "\n";
+        return false;
+      }
+      if (firmware_key_pub_file_.empty()) {
+        cerr << "No pre-processed public signing key file specified." << "\n";
+        return false;
+      }
+      if (firmware_key_version_ <= 0 || firmware_key_version_ > UINT16_MAX) {
+        cerr << "Invalid or no key version specified." << "\n";
+        return false;
+      }
+      if (firmware_sign_algorithm_ < 0 ||
+          firmware_sign_algorithm_ >= kNumAlgorithms) {
+        cerr << "Invalid or no signing key algorithm specified." << "\n";
+        return false;
+      }
     }
     if (firmware_key_file_.empty()) {
       cerr << "No signing key file specified." << "\n";
-      return false;
-    }
-    if (firmware_key_pub_file_.empty()) {
-      cerr << "No pre-processed public signing key file specified." << "\n";
-      return false;
-    }
-    if (firmware_key_version_ <= 0 || firmware_key_version_ > UINT16_MAX) {
-      cerr << "Invalid or no key version specified." << "\n";
-      return false;
-    }
-    if (firmware_sign_algorithm_ < 0 ||
-        firmware_sign_algorithm_ >= kNumAlgorithms) {
-      cerr << "Invalid or no signing key algorithm specified." << "\n";
-      return false;
+        return false;
+      }
+    if (firmware_version_ <= 0 || firmware_version_ > UINT16_MAX) {
+        cerr << "Invalid or no firmware version specified." << "\n";
+        return false;
     }
     if (out_file_.empty()) {
       cerr <<"No output file specified." << "\n";
@@ -312,7 +411,6 @@ bool FirmwareUtility::CheckOptions(void) {
   return true;
 }
 
-
 }  // namespace vboot_reference
 
 int main(int argc, char* argv[]) {