Add image signing scripts from TF-M bl2 library

requirements.txt

@@ -21,3 +21,4 @@ fuzzywuzzy>=0.11,<=0.17
 pyelftools>=0.24,<=0.25
 git+https://github.com/armmbed/manifest-tool.git@v1.4.6
 icetea>=1.2.1,<1.3
+pycryptodome>=3.7.2,<=3.7.3

tools/psa/tfm/bin_utils/__init__.py

@@ -0,0 +1,21 @@
+# Copyright (c) 2017-2018 ARM Limited
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from .assemble import Assembly
+
+__all__ = [
+    'Assembly'
+]

tools/psa/tfm/bin_utils/assemble.py

@@ -0,0 +1,105 @@
+#! /usr/bin/env python3
+#
+# Copyright 2017 Linaro Limited
+# Copyright (c) 2017-2018, Arm Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Assemble multiple images into a single image that can be flashed on the device.
+"""
+
+import argparse
+import errno
+import io
+import re
+import os
+import shutil
+
+offset_re = re.compile(r"^#define ([0-9A-Z_]+)_IMAGE_OFFSET\s+((0x)?[0-9a-fA-F]+)")
+size_re   = re.compile(r"^#define ([0-9A-Z_]+)_IMAGE_MAX_SIZE\s+((0x)?[0-9a-fA-F]+)")
+
+class Assembly():
+    def __init__(self, layout_path, output):
+        self.output = output
+        self.layout_path = layout_path
+        self.find_slots()
+        try:
+            os.unlink(output)
+        except OSError as e:
+            if e.errno != errno.ENOENT:
+                raise
+
+    def find_slots(self):
+        offsets = {}
+        sizes = {}
+
+        if os.path.isabs(self.layout_path):
+            configFile = self.layout_path
+        else:
+            scriptsDir = os.path.dirname(os.path.abspath(__file__))
+            configFile = os.path.join(scriptsDir, self.layout_path)
+
+        with open(configFile, 'r') as fd:
+            for line in fd:
+                m = offset_re.match(line)
+                if m is not None:
+                    offsets[m.group(1)] = int(m.group(2), 0)
+                m = size_re.match(line)
+                if m is not None:
+                    sizes[m.group(1)] = int(m.group(2), 0)
+
+        if 'SECURE' not in offsets:
+            raise Exception("Image config does not have secure partition")
+
+        if 'NON_SECURE' not in offsets:
+            raise Exception("Image config does not have non-secure partition")
+
+        self.offsets = offsets
+        self.sizes = sizes
+
+    def add_image(self, source, partition):
+        with open(self.output, 'ab') as ofd:
+            ofd.seek(0, os.SEEK_END)
+            pos = ofd.tell()
+            if pos > self.offsets[partition]:
+                raise Exception("Partitions not in order, unsupported")
+            if pos < self.offsets[partition]:
+                ofd.write(b'\xFF' * (self.offsets[partition] - pos))
+            statinfo = os.stat(source)
+            if statinfo.st_size > self.sizes[partition]:
+                raise Exception("Image {} is too large for partition".format(source))
+            with open(source, 'rb') as rfd:
+                shutil.copyfileobj(rfd, ofd, 0x10000)
+
+def main():
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument('-l', '--layout', required=True,
+            help='Location of the memory layout file')
+    parser.add_argument('-s', '--secure', required=True,
+            help='Unsigned secure image')
+    parser.add_argument('-n', '--non_secure',
+            help='Unsigned non-secure image')
+    parser.add_argument('-o', '--output', required=True,
+            help='Filename to write full image to')
+
+    args = parser.parse_args()
+    output = Assembly(args.layout, args.output)
+
+
+    output.add_image(args.secure, "SECURE")
+    output.add_image(args.non_secure, "NON_SECURE")
+
+if __name__ == '__main__':
+    main()

tools/psa/tfm/bin_utils/imgtool.py

@@ -0,0 +1,177 @@
+#! /usr/bin/env python3
+#
+# Copyright 2017 Linaro Limited
+# Copyright (c) 2018, Arm Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+import os
+import re
+import argparse
+from imgtool_lib import keys
+from imgtool_lib import image
+from imgtool_lib import version
+import sys
+
+def find_load_address(args):
+    load_address_re = re.compile(r"^#define\sIMAGE_LOAD_ADDRESS\s+(0x[0-9a-fA-F]+)")
+
+    if os.path.isabs(args.layout):
+            configFile = args.layout
+    else:
+        scriptsDir = os.path.dirname(os.path.abspath(__file__))
+        configFile = os.path.join(scriptsDir, args.layout)
+
+    ramLoadAddress = None
+    with open(configFile, 'r') as flash_layout_file:
+        for line in flash_layout_file:
+            m = load_address_re.match(line)
+            if m is not None:
+                ramLoadAddress = int(m.group(1), 0)
+                print("**[INFO]** Writing load address from the macro in "
+                      "flash_layout.h to the image header.. "
+                       + hex(ramLoadAddress)
+                       + " (dec. " + str(ramLoadAddress) + ")")
+                break
+    return ramLoadAddress
+
+# Returns the last version number if present, or None if not
+def get_last_version(path):
+    if (os.path.isfile(path) == False): # Version file not present
+        return None
+    else: # Version file is present, check it has a valid number inside it
+        with open(path, "r") as oldFile:
+            fileContents = oldFile.read()
+            if version.version_re.match(fileContents): # number is valid
+                return version.decode_version(fileContents)
+            else:
+                return None
+
+def next_version_number(args, defaultVersion, path):
+    newVersion = None
+    if (version.compare(args.version, defaultVersion) == 0): # Default version
+        lastVersion = get_last_version(path)
+        if (lastVersion is not None):
+            newVersion = version.increment_build_num(lastVersion)
+        else:
+            newVersion = version.increment_build_num(defaultVersion)
+    else: # Version number has been explicitly provided (not using the default)
+        newVersion = args.version
+    versionString = "{a}.{b}.{c}+{d}".format(
+                    a=str(newVersion.major),
+                    b=str(newVersion.minor),
+                    c=str(newVersion.revision),
+                    d=str(newVersion.build)
+    )
+    with open(path, "w") as newFile:
+        newFile.write(versionString)
+    print("**[INFO]** Image version number set to " + versionString)
+    return newVersion
+
+def gen_rsa2048(args):
+    keys.RSA2048.generate().export_private(args.key)
+
+keygens = {
+        'rsa-2048': gen_rsa2048, }
+
+def do_keygen(args):
+    if args.type not in keygens:
+        msg = "Unexpected key type: {}".format(args.type)
+        raise argparse.ArgumentTypeError(msg)
+    keygens[args.type](args)
+
+def do_getpub(args):
+    key = keys.load(args.key)
+    if args.lang == 'c':
+        key.emit_c()
+    else:
+        msg = "Unsupported language, valid are: c"
+        raise argparse.ArgumentTypeError(msg)
+
+def do_sign(args):
+    if args.rsa_pkcs1_15:
+        keys.sign_rsa_pss = False
+    img = image.Image.load(args.infile,
+            version=next_version_number(args,
+                                        version.decode_version("0"),
+                                        "lastVerNum.txt"),
+            header_size=args.header_size,
+            included_header=args.included_header,
+            pad=args.pad)
+    key = keys.load(args.key) if args.key else None
+    img.sign(key, find_load_address(args))
+
+    if args.pad:
+        img.pad_to(args.pad, args.align)
+
+    img.save(args.outfile)
+
+subcmds = {
+        'keygen': do_keygen,
+        'getpub': do_getpub,
+        'sign': do_sign, }
+
+def alignment_value(text):
+    value = int(text)
+    if value not in [1, 2, 4, 8]:
+        msg = "{} must be one of 1, 2, 4 or 8".format(value)
+        raise argparse.ArgumentTypeError(msg)
+    return value
+
+def intparse(text):
+    """Parse a command line argument as an integer.
+
+    Accepts 0x and other prefixes to allow other bases to be used."""
+    return int(text, 0)
+
+def args():
+    parser = argparse.ArgumentParser()
+    subs = parser.add_subparsers(help='subcommand help', dest='subcmd')
+
+    keygenp = subs.add_parser('keygen', help='Generate pub/private keypair')
+    keygenp.add_argument('-k', '--key', metavar='filename', required=True)
+    keygenp.add_argument('-t', '--type', metavar='type',
+                         choices=keygens.keys(), required=True)
+
+    getpub = subs.add_parser('getpub', help='Get public key from keypair')
+    getpub.add_argument('-k', '--key', metavar='filename', required=True)
+    getpub.add_argument('-l', '--lang', metavar='lang', default='c')
+
+    sign = subs.add_parser('sign', help='Sign an image with a private key')
+    sign.add_argument('--layout', required=True,
+                      help='Location of the memory layout file')
+    sign.add_argument('-k', '--key', metavar='filename')
+    sign.add_argument("--align", type=alignment_value, required=True)
+    sign.add_argument("-v", "--version", type=version.decode_version,
+                      default="0.0.0+0")
+    sign.add_argument("-H", "--header-size", type=intparse, required=True)
+    sign.add_argument("--included-header", default=False, action='store_true',
+                      help='Image has gap for header')
+    sign.add_argument("--pad", type=intparse,
+                      help='Pad image to this many bytes, adding trailer magic')
+    sign.add_argument("--rsa-pkcs1-15",
+                      help='Use old PKCS#1 v1.5 signature algorithm',
+                      default=False, action='store_true')
+    sign.add_argument("infile")
+    sign.add_argument("outfile")
+
+    args = parser.parse_args()
+    if args.subcmd is None:
+        print('Must specify a subcommand', file=sys.stderr)
+        sys.exit(1)
+
+    subcmds[args.subcmd](args)
+
+if __name__ == '__main__':
+    args()

tools/psa/tfm/bin_utils/imgtool_lib/__init__.py

@@ -0,0 +1,18 @@
+# Copyright 2017 Linaro Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is intentionally empty.
+#
+# The __init__.py files are required to make Python treat the directories as
+# containing packages.

tools/psa/tfm/bin_utils/imgtool_lib/image.py

@@ -0,0 +1,179 @@
+# Copyright 2017 Linaro Limited
+# Copyright (c) 2018, Arm Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Image signing and management.
+"""
+
+from . import version as versmod
+import hashlib
+import struct
+
+IMAGE_MAGIC = 0x96f3b83d
+IMAGE_HEADER_SIZE = 32
+
+# Image header flags.
+IMAGE_F = {
+        'PIC':                   0x0000001,
+        'NON_BOOTABLE':          0x0000010,
+        'RAM_LOAD':              0x0000020, }
+TLV_VALUES = {
+        'KEYHASH': 0x01,
+        'SHA256' : 0x10,
+        'RSA2048': 0x20, }
+
+TLV_INFO_SIZE = 4
+TLV_INFO_MAGIC = 0x6907
+
+# Sizes of the image trailer, depending on flash write size.
+trailer_sizes = {
+    write_size: 128 * 3 * write_size + 8 * 2 + 16
+    for write_size in [1, 2, 4, 8]
+}
+
+boot_magic = bytearray([
+    0x77, 0xc2, 0x95, 0xf3,
+    0x60, 0xd2, 0xef, 0x7f,
+    0x35, 0x52, 0x50, 0x0f,
+    0x2c, 0xb6, 0x79, 0x80, ])
+
+class TLV():
+    def __init__(self):
+        self.buf = bytearray()
+
+    def add(self, kind, payload):
+        """Add a TLV record.  Kind should be a string found in TLV_VALUES above."""
+        buf = struct.pack('<BBH', TLV_VALUES[kind], 0, len(payload))
+        self.buf += buf
+        self.buf += payload
+
+    def get(self):
+        header = struct.pack('<HH', TLV_INFO_MAGIC, TLV_INFO_SIZE + len(self.buf))
+        return header + bytes(self.buf)
+
+class Image():
+    @classmethod
+    def load(cls, path, included_header=False, **kwargs):
+        """Load an image from a given file"""
+        with open(path, 'rb') as f:
+            payload = f.read()
+        obj = cls(**kwargs)
+        obj.payload = payload
+
+        # Add the image header if needed.
+        if not included_header and obj.header_size > 0:
+            obj.payload = (b'\000' * obj.header_size) + obj.payload
+
+        obj.check()
+        return obj
+
+    def __init__(self, version, header_size=IMAGE_HEADER_SIZE, pad=0):
+        self.version = version
+        self.header_size = header_size or IMAGE_HEADER_SIZE
+        self.pad = pad
+
+    def __repr__(self):
+        return "<Image version={}, header_size={}, pad={}, payloadlen=0x{:x}>".format(
+                self.version,
+                self.header_size,
+                self.pad,
+                len(self.payload))
+
+    def save(self, path):
+        with open(path, 'wb') as f:
+            f.write(self.payload)
+
+    def check(self):
+        """Perform some sanity checking of the image."""
+        # If there is a header requested, make sure that the image
+        # starts with all zeros.
+        if self.header_size > 0:
+            if any(v != 0 and v != b'\000' for v in self.payload[0:self.header_size]):
+                raise Exception("Padding requested, but image does not start with zeros")
+
+    def sign(self, key, ramLoadAddress):
+        self.add_header(key, ramLoadAddress)
+
+        tlv = TLV()
+
+        sha = hashlib.sha256()
+        sha.update(self.payload)
+        digest = sha.digest()
+
+        tlv.add('SHA256', digest)
+
+        if key is not None:
+            pub = key.get_public_bytes()
+            sha = hashlib.sha256()
+            sha.update(pub)
+            pubbytes = sha.digest()
+            tlv.add('KEYHASH', pubbytes)
+
+            sig = key.sign(self.payload)
+            tlv.add(key.sig_tlv(), sig)
+
+        self.payload += tlv.get()
+
+    def add_header(self, key, ramLoadAddress):
+        """Install the image header.
+
+        The key is needed to know the type of signature, and
+        approximate the size of the signature."""
+
+        flags = 0
+        if ramLoadAddress is not None:
+            # add the load address flag to the header to indicate that an SRAM
+            # load address macro has been defined
+            flags |= IMAGE_F["RAM_LOAD"]
+
+        fmt = ('<' +
+            # type ImageHdr struct {
+            'I' +   # Magic uint32
+            'I' +   # LoadAddr uint32
+            'H' +   # HdrSz uint16
+            'H' +   # Pad1  uint16
+            'I' +   # ImgSz uint32
+            'I' +   # Flags uint32
+            'BBHI' + # Vers  ImageVersion
+            'I'     # Pad2  uint32
+            ) # }
+        assert struct.calcsize(fmt) == IMAGE_HEADER_SIZE
+        header = struct.pack(fmt,
+                IMAGE_MAGIC,
+                0 if (ramLoadAddress is None) else ramLoadAddress, # LoadAddr
+                self.header_size,
+                0, # Pad1
+                len(self.payload) - self.header_size, # ImageSz
+                flags, # Flags
+                self.version.major,
+                self.version.minor or 0,
+                self.version.revision or 0,
+                self.version.build or 0,
+                0) # Pad2
+        self.payload = bytearray(self.payload)
+        self.payload[:len(header)] = header
+
+    def pad_to(self, size, align):
+        """Pad the image to the given size, with the given flash alignment."""
+        tsize = trailer_sizes[align]
+        padding = size - (len(self.payload) + tsize)
+        if padding < 0:
+            msg = "Image size (0x{:x}) + trailer (0x{:x}) exceeds requested size 0x{:x}".format(
+                    len(self.payload), tsize, size)
+            raise Exception(msg)
+        pbytes  = b'\xff' * padding
+        pbytes += b'\xff' * (tsize - len(boot_magic))
+        pbytes += boot_magic
+        self.payload += pbytes

tools/psa/tfm/bin_utils/imgtool_lib/keys.py

@@ -0,0 +1,104 @@
+# Copyright 2017 Linaro Limited
+# Copyright (c) 2017-2018, Arm Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Cryptographic key management for imgtool.
+"""
+
+from __future__ import print_function
+from Crypto.Hash import SHA256
+from Crypto.PublicKey import RSA
+from Crypto.Signature import PKCS1_v1_5, PKCS1_PSS
+import hashlib
+from pyasn1.type import namedtype, univ
+from pyasn1.codec.der.encoder import encode
+
+# By default, we use RSA-PSS (PKCS 2.1).  That can be overridden on
+# the command line to support the older (less secure) PKCS1.5
+sign_rsa_pss = True
+
+AUTOGEN_MESSAGE = "/* Autogenerated by imgtool.py, do not edit. */"
+
+class RSAPublicKey(univ.Sequence):
+    componentType = namedtype.NamedTypes(
+            namedtype.NamedType('modulus', univ.Integer()),
+            namedtype.NamedType('publicExponent', univ.Integer()))
+
+class RSA2048():
+    def __init__(self, key):
+        """Construct an RSA2048 key with the given key data"""
+        self.key = key
+
+    @staticmethod
+    def generate():
+        return RSA2048(RSA.generate(2048))
+
+    def export_private(self, path):
+        with open(path, 'wb') as f:
+            f.write(self.key.exportKey('PEM'))
+
+    def get_public_bytes(self):
+        node = RSAPublicKey()
+        node['modulus'] = self.key.n
+        node['publicExponent'] = self.key.e
+        return bytearray(encode(node))
+
+    def emit_c(self):
+        print(AUTOGEN_MESSAGE)
+        print("const unsigned char rsa_pub_key[] = {", end='')
+        encoded = self.get_public_bytes()
+        for count, b in enumerate(encoded):
+            if count % 8 == 0:
+                print("\n\t", end='')
+            else:
+                print(" ", end='')
+            print("0x{:02x},".format(b), end='')
+        print("\n};")
+        print("const unsigned int rsa_pub_key_len = {};".format(len(encoded)))
+
+    def sig_type(self):
+        """Return the type of this signature (as a string)"""
+        if sign_rsa_pss:
+            return "PKCS1_PSS_RSA2048_SHA256"
+        else:
+            return "PKCS15_RSA2048_SHA256"
+
+    def sig_len(self):
+        return 256
+
+    def sig_tlv(self):
+        return "RSA2048"
+
+    def sign(self, payload):
+        converted_payload = bytes(payload)
+        sha = SHA256.new(converted_payload)
+        if sign_rsa_pss:
+            signer = PKCS1_PSS.new(self.key)
+        else:
+            signer = PKCS1_v1_5.new(self.key)
+        signature = signer.sign(sha)
+        assert len(signature) == self.sig_len()
+        return signature
+
+def load(path):
+    with open(path, 'rb') as f:
+        pem = f.read()
+    try:
+        key = RSA.importKey(pem)
+        if key.n.bit_length() != 2048:
+            raise Exception("Unsupported RSA bit length, only 2048 supported")
+        return RSA2048(key)
+    except ValueError:
+        raise Exception("Unsupported RSA key file")

tools/psa/tfm/bin_utils/imgtool_lib/version.py

@@ -0,0 +1,66 @@
+# Copyright 2017 Linaro Limited
+# Copyright (c) 2018, Arm Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Semi Semantic Versioning
+
+Implements a subset of semantic versioning that is supportable by the image header.
+"""
+
+import argparse
+from collections import namedtuple
+import re
+
+SemiSemVersion = namedtuple('SemiSemVersion', ['major', 'minor', 'revision', 'build'])
+
+def increment_build_num(lastVer):
+    newVer = SemiSemVersion(lastVer.major, lastVer.minor, lastVer.revision, lastVer.build + 1)
+    return newVer
+
+# -1 if a is older than b; 0 if they're the same version; 1 if a is newer than b
+def compare(a, b):
+    if (a.major > b.major): return 1
+    elif (a.major < b.major): return -1
+    else:
+        if (a.minor > b.minor): return 1
+        elif (a.minor < b.minor): return -1
+        else:
+            if (a.revision > b.revision): return 1
+            elif (a.revision < b.revision): return -1
+            else:
+                if (a.build > b.build): return 1
+                elif (a.build < b.build): return -1
+                else: return 0
+
+version_re = re.compile(r"""^([1-9]\d*|0)(\.([1-9]\d*|0)(\.([1-9]\d*|0)(\+([1-9]\d*|0))?)?)?$""")
+def decode_version(text):
+    """Decode the version string, which should be of the form maj.min.rev+build"""
+    m = version_re.match(text)
+    if m:
+        result = SemiSemVersion(
+                int(m.group(1)) if m.group(1) else 0,
+                int(m.group(3)) if m.group(3) else 0,
+                int(m.group(5)) if m.group(5) else 0,
+                int(m.group(7)) if m.group(7) else 0)
+        return result
+    else:
+        msg = "Invalid version number, should be maj.min.rev+build with later parts optional"
+        raise argparse.ArgumentTypeError(msg)
+
+if __name__ == '__main__':
+    print(decode_version("1.2"))
+    print(decode_version("1.0"))
+    print(decode_version("0.0.2+75"))
+    print(decode_version("0.0.0+00"))