Re: [U-Boot] [PATCH v3 5/6] binman: add ROM image signing for Bay Trail SoC

4 Dec 2017

Hi Anatolij,
On Fri, Nov 17, 2017 at 9:16 AM, Anatolij Gustschin agust@denx.de wrote:
...
Generate u-boot-verified.rom image containing Secure Boot Manifest
when secure boot option is enabled.
Signed-off-by: Anatolij Gustschin agust@denx.de
NOTE: This patch applies on top of binman changes in binman-working
branch in git://git.denx.de/u-boot-dm.git
Changes in v3:

New patch. Moved signing script functionality (secure_boot_helper.py
in first series) to binman. The signing is enabled automatically
via u-boot.dtsi when secure boot option is enabled
Clean up all temporary files generated by signing script

arch/x86/dts/u-boot.dtsi         |   7 +
 tools/binman/signing/baytrail.py | 313 +++++++++++++++++++++++++++++++++++++++
 tools/binman/signing/signer.py   |   3 +
 3 files changed, 323 insertions(+)
 create mode 100644 tools/binman/signing/baytrail.py

diff --git a/arch/x86/dts/u-boot.dtsi b/arch/x86/dts/u-boot.dtsi
index 7e37d4f394..98e2309108 100644
--- a/arch/x86/dts/u-boot.dtsi
+++ b/arch/x86/dts/u-boot.dtsi
@@ -15,6 +15,13 @@
                sort-by-pos;
                pad-byte = <0xff>;
                size = <CONFIG_ROM_SIZE>;
+#ifdef CONFIG_BAYTRAIL_SECURE_BOOT
This needs to be a generic macro like CONFIG_SECURE_BOOT as this
affects all x86 rom images.
...

          sign;



+#ifdef CONFIG_SYS_SOC
I believe CONFIG_SYS_SOC is defined by every board, so no need to do
#ifdef here.
...

          socname = CONFIG_SYS_SOC;



+#endif
+#endif



#ifdef CONFIG_HAVE_INTEL_ME
                intel-descriptor {
                        filename = CONFIG_FLASH_DESCRIPTOR_FILE;
diff --git a/tools/binman/signing/baytrail.py b/tools/binman/signing/baytrail.py
new file mode 100644
index 0000000000..3bfbbedb5d
--- /dev/null
+++ b/tools/binman/signing/baytrail.py
@@ -0,0 +1,313 @@
+# Copyright (c) 2017 DENX Software Engineering
+# Written by Markus Valentin mv@denx.de
+# Adapted for binman integration: Anatolij Gustschin agust@denx.de
+#
+# SPDX-License-Identifier:     GPL-2.0+
+#
+# Functions for signing the binman output image for Bay Trail SoC
+#



+import binascii
+import logging, sys
+import os



+from hashlib import sha256
+from os.path import basename, isfile, splitext
+from os.path import join as pjoin
+from struct import pack



+import OpenSSL
+from OpenSSL import crypto
+from cryptography import x509
+from cryptography.hazmat.backends import default_backend



+FSP_FILE_NAME = "fsp-sb.bin"
+FSP_STAGE2_FILE_NAME = "fsp_stage2.bin"
+U_BOOT_ROM_FILE_NAME = 'u-boot.rom'
+OUTPUT_FILE_NAME = 'u-boot-verified.rom'
+U_BOOT_TO_SIGN_FILE_NAME = 'u-boot-to-sign.bin'
+IBB_FILE_NAME = 'ibb.bin'
+FPF_CONFIG_FILE_NAME = 'fpf_config.txt'
+SIGNED_MANIFEST_FILE_NAME = 'signed_manifest.bin'
+UNSIGNED_MANIFEST_FILE_NAME = 'un'+SIGNED_MANIFEST_FILE_NAME
+OEM_FILE_NAME = 'oemdata.bin'



+OEM_PRIV_KEY_FILE_NAME = 'oemkey.pem'
+OEM_PUB_KEY_FILE_NAME = 'pub_oemkey.pem'
+OEM_PUBKEY_BIN_FILE_NAME = 'pub_oemkey.bin'
+OEM_PUBKEY_AND_SIG_FILE_NAME = 'oem_pub_sig.bin'
This deserves a comment block on how there files are generated on the host.
...



+FIT_PUB_KEY_FILE_NAME = "dev.crt"



+# FSP Stage2 size is 0x1f400. For debug FSP it is 0x2f400,
+# you must change it here wenn building with debug FSP image!
typo: wenn -> when
...
+FSP_STAGE_2_SIZE = 0x1f400
+FSP_UPD_SIZE = 0xc00
+IBB_SIZE = 0x1fc00
+MANIFEST_SIZE = 0x400
+OEM_BLOCK_MAX_SIZE = 0x190
+U_BOOT_ROM_SIZE = 0x800000
Can this file size be determined from the CONFIG_ROM_SIZE?
...
+ROMFILE_SYS_TEXT_BASE = 0x00700000
and calculate this by ourselves?
...



+MANIFEST_IDENTIFIER = b'$VBM'
+VERSION = 1
+SECURE_VERSION_NUMBER = 2
+OEM_DATA_PREAMBLE = '01000200'



+oem_data_hash_files = []




+def append_binary_files(first_file, second_file, new_file):

with open(new_file, 'wb') as f:
   f.write(bytearray(open(first_file, 'rb').read()))


   f.write(bytearray(open(second_file, 'rb').read()))





+# This function creates the OEM-Data block which must be inserted
+# into the Bay Trail Secure Boot Manifest.
+def assemble_oem_data(file_path):

file_size = 0
with open(file_path, 'wb') as f:
   f.write(binascii.unhexlify(OEM_DATA_PREAMBLE))


   file_size += 4


   for hash_file in oem_data_hash_files:


       f.write(open(hash_file, 'rb').read())


       file_size += 32


   pad_file_with_zeros(f, OEM_BLOCK_MAX_SIZE-file_size)





+# This function creates the final U-Boot ROM image from
+# the original u-boot.rom and the signed Initial Boot Block
+# which contains the Secure Boot Manifest
+def assemble_secure_boot_image(u_boot_rom, signed_ibb):

data = bytearray(open(u_boot_rom, 'rb').read())
ibb = bytearray(open(signed_ibb, 'rb').read())
data[-(MANIFEST_SIZE+IBB_SIZE):] = ibb
open(OUTPUT_FILE_NAME, 'wb').write(data)



+# Constructs a complete Secure Boot Manifest which is just missing
+# the OEM publickey and the manifest signature
+def create_unsigned_secure_boot_manifest(unsigned_manifest,

                                    oem_file='oemdata.bin',


                                    ibb='ibb.bin'):


with open(unsigned_manifest, 'wb') as f:
   f.write(MANIFEST_IDENTIFIER)


   f.write(pack('i', VERSION))


   f.write(pack('i', MANIFEST_SIZE))


   f.write(pack('i', SECURE_VERSION_NUMBER))


   pad_file_with_zeros(f, 4)


   hash_function = sha256()


   hash_function.update(bytearray(open(ibb, 'rb').read()))


   f.write(hash_function.digest()[::-1])


   pad_file_with_zeros(f, 36)


   f.write(bytearray(open(oem_file, 'rb').read()))


   pad_file_with_zeros(f, 20)





+# Fetch part of a binary from from_byte to to_byte and write
+# this part to a secondary file
+def extract_binary_part(binary_to_extract_from, to_file, from_byte, to_byte):

data = open(binary_to_extract_from, 'rb').read()
open(to_file, 'wb').write(data[from_byte:to_byte])



+# Calculate a SHA256 checksum over a file and write a file with it to a
+# file next to the original file. If requested, change endianness
+# (sometimes needed because the TXE engine wants another byteorder)
+def sha256_to_file(binary_dir, file_to_hash, change_endianness=False):

# We collect the hashes in a list (in the correct order) to be able
# to put them later to the OEM data section
if not oem_data_hash_files.__contains__(hashfile_path(binary_dir,
                                       file_to_hash)):


   oem_data_hash_files.append(hashfile_path(binary_dir, file_to_hash))


with open(file_to_hash, 'rb') as f:
   hash_function = sha256()


   hash_function.update(f.read())


   # write as little to file


   if change_endianness:


       open(hashfile_path(binary_dir, file_to_hash),


            'wb').write(hash_function.digest())


   else:


       open(hashfile_path(binary_dir, file_to_hash),


            'wb').write(hash_function.digest()[::-1])





+# Create hash filename using the file_to_hash name
+def hashfile_path(binary_dir, file_to_hash):

hash_file_name = splitext(
           basename(file_to_hash))[0].__add__('.sha256')


return pjoin(binary_dir, hash_file_name)



+# Pad the given files with a given byte number of zeros.
+# byte_count value must be divisible by 4
+def pad_file_with_zeros(file_handle, byte_count):

if byte_count % 4 != 0:
   raise ValueError("Given byte_count must be divisible by 4 ...")


pad_count = 0
while pad_count < byte_count:
   file_handle.write(pack('i', 0))


   pad_count += 4





+# Extract the modulus of a public key. The TXE engine gets the public key
+# split in modulus and exponent, for this reason we need to extract it.
+def get_modulus_from_pubkey(public_key_path):

public_key = open(public_key_path, 'rb').read()
cert = x509.load_pem_x509_certificate(public_key, default_backend())
return ("%X" % (cert.public_key().public_numbers().n))



+# Save a given modulus and exponent to a file as binary for use within
+# the manifest
+def save_binary_public_key(pub_key_file_path, modulus, exponent=0x10001):

with open(pub_key_file_path, 'wb') as f:
   f.write(binascii.unhexlify(modulus)[::-1])


   f.write(pack('i', exponent))





+# Replace the public key hash in the fuse configuration text file
+# and set the lock bit
+def replace_oem_pubkey_hash(pubkey_hash, fpf_config_path, lock_fuses):

data = binascii.hexlify(pubkey_hash)
fpf_config_file = open(fpf_config_path, 'r').readlines()

new_line_hash = "FUSE_FILE_OEM_KEY_HASH_1:{:s}:{}\n"\
               .format(data.upper().decode('ascii'),


                       str(lock_fuses).upper())


new_line_sb_enabled = "FUSE_FILE_SECURE_BOOT_EN:01:{}\n"\
                     .format(str(lock_fuses).upper())



with open(fpf_config_path, 'w') as f:
   for line in fpf_config_file:


       if line.startswith('FUSE_FILE_OEM_KEY_HASH_1'):


           line = new_line_hash


       if line.startswith('FUSE_FILE_SECURE_BOOT_EN'):


           line = new_line_sb_enabled


       f.write(line)





+# For the TXE engine one needs to change the endianness
+def reverse_endianness(file_to_reverse):

data = open(file_to_reverse, 'rb').read()
open(file_to_reverse, 'wb').write(data[::-1])



+# Sign the given file with the private_key using OpenSSL
+# and write it to the signature_file
+def sign_file(unsigned_file, private_key, signature_file):

key = open(private_key, 'r').read()
pkey_obj = crypto.load_privatekey(crypto.FILETYPE_PEM, key)
data = open(unsigned_file, 'rb').read()
signature = OpenSSL.crypto.sign(pkey_obj, data, "sha256")
open(signature_file, 'wb').write(signature)



+# Perform IBB signing and generate Secure Boot Manifest for
+# Bay Trail SoC, then create final ROM image containing the
+# manifest and write it to u-boot-verified.rom file.
+def baytrail_sign(u_boot_rom, keydir, indir, outdir):

FORMAT = '  BINMAN  %(message)s'
logging.basicConfig(stream=sys.stderr, level=logging.INFO, format=FORMAT)
logging.info("Signing image %s" % u_boot_rom)
for dir in indir:
   fsp = pjoin(dir, FSP_FILE_NAME)


   if not isfile(fsp):


       continue



if not isfile(fsp):
   raise ValueError("Can't find FSP file %s" % fsp)



# Assemble file paths
fit_public_key = pjoin(keydir, FIT_PUB_KEY_FILE_NAME)
fit_public_key_modulus = pjoin(keydir, FIT_PUB_KEY_FILE_NAME+".mod")
fsp_stage2 = pjoin(outdir, FSP_STAGE2_FILE_NAME)
u_boot_to_sign = pjoin(outdir, U_BOOT_TO_SIGN_FILE_NAME)
ibb = pjoin(outdir, IBB_FILE_NAME)
signed_ibb = pjoin(outdir, "signed_" + IBB_FILE_NAME)

signed_manifest = pjoin(outdir, SIGNED_MANIFEST_FILE_NAME)
unsigned_manifest = pjoin(outdir, UNSIGNED_MANIFEST_FILE_NAME)
manifest_signature = splitext(unsigned_manifest)[0] + ".signature"

oem_file = pjoin(outdir, OEM_FILE_NAME)
oem_private_key = pjoin(keydir, OEM_PRIV_KEY_FILE_NAME)
oem_public_key = pjoin(keydir, OEM_PUB_KEY_FILE_NAME)
oem_pubkey_binary = pjoin(keydir, OEM_PUBKEY_BIN_FILE_NAME)
oem_pubkey_and_sig = pjoin(keydir, OEM_PUBKEY_AND_SIG_FILE_NAME)

# Check for all needed files to be available
for f in [fsp, u_boot_rom, fit_public_key, oem_private_key]:
   if not isfile(f):


       raise ValueError("File %s not found..." % f)



# Get everything from ROM file except IBB + Manfifest + UPD + FSP Stage2
# (127KiB + 1KiB + 3KiB + 125Kib), then write it to a separated file and
# calculate the hash. FPS Stage2 is verified in FSP, so skip it here
extract_binary_part(u_boot_rom, u_boot_to_sign, ROMFILE_SYS_TEXT_BASE,
                   (U_BOOT_ROM_SIZE - (IBB_SIZE + MANIFEST_SIZE +


                                       FSP_UPD_SIZE + FSP_STAGE_2_SIZE)))


sha256_to_file(outdir, u_boot_to_sign, True)

# Extract Stage2 of the FSP and calculate its hash
extract_binary_part(fsp, fsp_stage2, 0, FSP_STAGE_2_SIZE)
sha256_to_file(outdir, fsp_stage2)

with open(fit_public_key_modulus, 'wb') as f:
   f.write(binascii.unhexlify(get_modulus_from_pubkey(fit_public_key)))


sha256_to_file(outdir, fit_public_key_modulus, True)

# Assemble oemdata
logging.debug("Assembling OEM data from %d hashes: %s" %
             (oem_data_hash_files.__len__(), oem_data_hash_files))


assemble_oem_data(oem_file)

logging.debug("Extracting last 127K from %s as %s" %
             (u_boot_rom, ibb))


extract_binary_part(u_boot_rom, ibb,
                   (U_BOOT_ROM_SIZE-IBB_SIZE), U_BOOT_ROM_SIZE)



logging.debug("Creating Secure Boot Manifest")
create_unsigned_secure_boot_manifest(unsigned_manifest, oem_file, ibb)

logging.debug("Signing manifest with OpenSSL and private key %s" %
             (oem_private_key))


sign_file(unsigned_manifest, oem_private_key, manifest_signature)

logging.debug("Append public key and signature to unsigned manifest")
oem_pub_key_modulus = get_modulus_from_pubkey(oem_public_key)
save_binary_public_key(oem_pubkey_binary, oem_pub_key_modulus)

reverse_endianness(manifest_signature)
append_binary_files(oem_pubkey_binary, manifest_signature,
                   oem_pubkey_and_sig)



append_binary_files(unsigned_manifest, oem_pubkey_and_sig,
                   signed_manifest)



if isfile(FPF_CONFIG_FILE_NAME):
   hash_function = sha256()


   hash_function.update(bytearray(open(oem_pubkey_binary, 'rb').read()))


   replace_oem_pubkey_hash(hash_function.digest()[::-1],


                           FPF_CONFIG_FILE_NAME, False)



logging.debug("Append manifest with signature to IBB")
append_binary_files(signed_manifest, ibb, signed_ibb)

logging.debug("Assemble %s from %s and %s" %
             (OUTPUT_FILE_NAME, u_boot_rom, signed_manifest))


assemble_secure_boot_image(u_boot_rom, signed_ibb)

# Cleanup temporary files
os.remove(fsp_stage2)
os.remove(ibb)
os.remove(signed_ibb)
os.remove(signed_manifest)
os.remove(manifest_signature)
os.remove(oem_file)
os.remove(u_boot_to_sign)
os.remove(unsigned_manifest)
os.remove(FIT_PUB_KEY_FILE_NAME + ".sha256")
os.remove(splitext(fsp_stage2)[0] + ".sha256")
os.remove(splitext(u_boot_to_sign)[0] + ".sha256")

diff --git a/tools/binman/signing/signer.py b/tools/binman/signing/signer.py
index 4ec43d424f..e9ce97f559 100644
--- a/tools/binman/signing/signer.py
+++ b/tools/binman/signing/signer.py
@@ -6,10 +6,13 @@
 # Class for signing the output image of binman
 #
+from baytrail import baytrail_sign



# Dictionary with SoC names and corresponding signing functions.
 # Image signing support for not yet supported SoCs can be added
 # here
 soc_sign_dict = {

'baytrail': baytrail_sign,

}
class ImageSigner(object):
Regards,
Bin

    

Re: [U-Boot] [PATCH v3 5/6] binman: add ROM image signing for Bay Trail SoC

Bin Meng

Signed-off-by: Anatolij Gustschin agust@denx.de

class ImageSigner(object):