releasetools: Add bootable image signing

Set PRODUCT_PRIVATE_KEY to the path of the boot image signing
certificate to sign an image for secure boot.

Change-Id: I2c767c6f9c3740bed3d7094d2d0b50a075e08abc

Author: Brint E. Kriebel

tools/releasetools/common.py

@@ -296,6 +296,7 @@ def BuildBootableImage(sourcedir, fs_config_file, info_dict=None):
 
   ramdisk_img = tempfile.NamedTemporaryFile()
   img = tempfile.NamedTemporaryFile()
+  bootimg_key = os.getenv("PRODUCT_PRIVATE_KEY", None)
 
   if os.access(fs_config_file, os.F_OK):
     cmd = ["mkbootfs", "-f", fs_config_file, os.path.join(sourcedir, "RAMDISK")]
@@ -362,8 +363,9 @@ def BuildBootableImage(sourcedir, fs_config_file, info_dict=None):
 
     fn = os.path.join(sourcedir, "pagesize")
     if os.access(fn, os.F_OK):
+      kernel_pagesize=open(fn).read().rstrip("\n")
       cmd.append("--pagesize")
-      cmd.append(open(fn).read().rstrip("\n"))
+      cmd.append(kernel_pagesize)
 
     args = info_dict.get("mkbootimg_args", None)
     if args and args.strip():
@@ -376,6 +378,42 @@ def BuildBootableImage(sourcedir, fs_config_file, info_dict=None):
   assert p.returncode == 0, "mkbootimg of %s image failed" % (
       os.path.basename(sourcedir),)
 
+  if bootimg_key and os.path.exists(bootimg_key) and kernel_pagesize > 0:
+    print "Signing bootable image..."
+    bootimg_key_passwords = {}
+    bootimg_key_passwords.update(PasswordManager().GetPasswords(bootimg_key.split()))
+    bootimg_key_password = bootimg_key_passwords[bootimg_key]
+    if bootimg_key_password is not None:
+        bootimg_key_password += "\n"
+    img_sha256 = tempfile.NamedTemporaryFile()
+    img_sig = tempfile.NamedTemporaryFile()
+    img_sig_padded = tempfile.NamedTemporaryFile()
+    img_secure = tempfile.NamedTemporaryFile()
+    p = Run(["openssl", "dgst", "-sha256", "-binary", "-out", img_sha256.name, img.name],
+        stdout=subprocess.PIPE)
+    p.communicate()
+    assert p.returncode == 0, "signing of bootable image failed"
+    p = Run(["openssl", "rsautl", "-sign", "-in", img_sha256.name, "-inkey", bootimg_key, "-out",
+        img_sig.name, "-passin", "stdin"], stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+    p.communicate(bootimg_key_password)
+    assert p.returncode == 0, "signing of bootable image failed"
+    p = Run(["dd", "if=/dev/zero", "of=%s" % img_sig_padded.name, "bs=%s" % kernel_pagesize,
+        "count=1"], stdout=subprocess.PIPE)
+    p.communicate()
+    assert p.returncode == 0, "signing of bootable image failed"
+    p = Run(["dd", "if=%s" % img_sig.name, "of=%s" % img_sig_padded.name, "conv=notrunc"],
+        stdout=subprocess.PIPE)
+    p.communicate()
+    assert p.returncode == 0, "signing of bootable image failed"
+    p = Run(["cat", img.name, img_sig_padded.name], stdout=img_secure.file.fileno())
+    p.communicate()
+    assert p.returncode == 0, "signing of bootable image failed"
+    shutil.copyfile(img_secure.name, img.name)
+    img_sha256.close()
+    img_sig.close()
+    img_sig_padded.close()
+    img_secure.close()
+
   if info_dict.get("verity_key", None):
     path = "/" + os.path.basename(sourcedir).lower()
     cmd = ["boot_signer", path, img.name, info_dict["verity_key"] + ".pk8", info_dict["verity_key"] + ".x509.pem", img.name]