mkimage: fit: Support signed configurations in 'auto' FITs

Extend support for signing in auto-generated (-f auto) FIT. Previously,
it was possible to get signed 'images' subnodes in the FIT using
options -g and -o together with -f auto. This patch allows signing
'configurations' subnodes instead of 'images' ones (which are hashed),
using option -f auto-conf instead of -f auto. Adding also -K <dtb> and
-r options, will add public key to <dtb> file with required = "conf"
property.

Summary:
    -f auto => FIT with crc32 images
    -f auto -g ... -o ... => FIT with signed images
    -f auto-conf -g ... -o ... => FIT with sha1 images and signed confs

Example: FIT with kernel, two device tree files, and signed
configurations; public key (needed to verify signatures) is
added to u-boot.dtb with required = "conf" property.

mkimage -f auto-conf -A arm -O linux -T kernel -C none -a 43e00000 \
        -e 0 -d vmlinuz -b /path/to/first.dtb -b /path/to/second.dtb \
        -k /folder/with/key-files -g keyname -o sha256,rsa4096 \
        -K u-boot.dtb -r kernel.itb

Example: Add public key with required = "conf" property to u-boot.dtb
without needing to sign anything. This will also create a useless FIT
named unused.itb.

mkimage -f auto-conf -d /dev/null -k /folder/with/key-files \
        -g keyname -o sha256,rsa4096 -K u-boot.dtb -r unused.itb

Signed-off-by: Massimo Pegorer <massimo.pegorer@vimar.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 195 insertions, 0 deletions

diff --git a/test/py/tests/test_fit_auto_signed.py b/test/py/tests/test_fit_auto_signed.py
new file mode 100644
index 0000000000..9ea3351619
--- /dev/null
+++ b/test/py/tests/test_fit_auto_signed.py
@@ -0,0 +1,195 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Copyright (c) 2022 Massimo Pegorer
+
+"""
+Test that mkimage generates auto-FIT with signatures and/or hashes as expected.
+
+The mkimage tool can create auto generated (i.e. without an ITS file
+provided as input) FIT in three different flavours: with crc32 checksums
+of 'images' subnodes; with signatures of 'images' subnodes; with sha1
+hashes of 'images' subnodes and signatures of 'configurations' subnodes.
+This test verifies that auto-FIT are generated as expected, in all of
+the three flavours, including check of hashes and signatures (except for
+configurations ones).
+
+The test does not run the sandbox. It only checks the host tool mkimage.
+"""
+
+import os
+import pytest
+import u_boot_utils as util
+import binascii
+from Cryptodome.Hash import SHA1
+from Cryptodome.Hash import SHA256
+from Cryptodome.PublicKey import RSA
+from Cryptodome.Signature import pkcs1_15
+
+class SignedFitHelper(object):
+    """Helper to manipulate a FIT with signed/hashed images/configs."""
+    def __init__(self, cons, file_name):
+        self.fit = file_name
+        self.cons = cons
+        self.images_nodes = set()
+        self.confgs_nodes = set()
+
+    def __fdt_list(self, path):
+        return util.run_and_log(self.cons,
+            f'fdtget -l {self.fit} {path}')
+
+    def __fdt_get_string(self, node, prop):
+        return util.run_and_log(self.cons,
+            f'fdtget -ts {self.fit} {node} {prop}')
+
+    def __fdt_get_binary(self, node, prop):
+        numbers = util.run_and_log(self.cons,
+            f'fdtget -tbi {self.fit} {node} {prop}')
+
+        bignum = bytearray()
+        for little_num in numbers.split():
+            bignum.append(int(little_num))
+
+        return bignum
+
+    def build_nodes_sets(self):
+        """Fill sets with FIT images and configurations subnodes."""
+        for node in self.__fdt_list('/images').split():
+            subnode = f'/images/{node}'
+            self.images_nodes.add(subnode)
+
+        for node in self.__fdt_list('/configurations').split():
+            subnode = f'/configurations/{node}'
+            self.confgs_nodes.add(subnode)
+
+        return len(self.images_nodes) + len(self.confgs_nodes)
+
+    def check_fit_crc32_images(self):
+        """Test that all images in the set are hashed as expected.
+
+        Each image must have an hash with algo=crc32 and hash value must match
+        the one calculated over image data.
+        """
+        for node in self.images_nodes:
+            algo = self.__fdt_get_string(f'{node}/hash', 'algo')
+            assert algo == "crc32\n", "Missing expected crc32 image hash!"
+
+            raw_crc32 = self.__fdt_get_binary(f'{node}/hash', 'value')
+            raw_bin = self.__fdt_get_binary(node, 'data')
+            assert raw_crc32 == (binascii.crc32(raw_bin) &
+                0xffffffff).to_bytes(4, 'big'), "Wrong crc32 hash!"
+
+    def check_fit_signed_images(self, key_name, sign_algo, verifier):
+        """Test that all images in the set are signed as expected.
+
+        Each image must have a signature with: key-name-hint matching key_name
+        argument; algo matching sign_algo argument; value matching the one
+        calculated over image data using verifier argument.
+        """
+        for node in self.images_nodes:
+            hint = self.__fdt_get_string(f'{node}/signature', 'key-name-hint')
+            assert hint == key_name + "\n", "Missing expected key name hint!"
+            algo = self.__fdt_get_string(f'{node}/signature', 'algo')
+            assert algo == sign_algo + "\n", "Missing expected signature algo!"
+
+            raw_sig = self.__fdt_get_binary(f'{node}/signature', 'value')
+            raw_bin = self.__fdt_get_binary(node, 'data')
+            verifier.verify(SHA256.new(raw_bin), bytes(raw_sig))
+
+    def check_fit_signed_confgs(self, key_name, sign_algo):
+        """Test that all configs are signed, and images hashed, as expected.
+
+        Each image must have an hash with algo=sha1 and hash value must match
+        the one calculated over image data. Each configuration must have a
+        signature with key-name-hint matching key_name argument and algo
+        matching sign_algo argument.
+        TODO: configurations signature checking.
+        """
+        for node in self.images_nodes:
+            algo = self.__fdt_get_string(f'{node}/hash', 'algo')
+            assert algo == "sha1\n", "Missing expected sha1 image hash!"
+
+            raw_hash = self.__fdt_get_binary(f'{node}/hash', 'value')
+            raw_bin = self.__fdt_get_binary(node, 'data')
+            assert raw_hash == SHA1.new(raw_bin).digest(), "Wrong sha1 hash!"
+
+        for node in self.confgs_nodes:
+            hint = self.__fdt_get_string(f'{node}/signature', 'key-name-hint')
+            assert hint == key_name + "\n", "Missing expected key name hint!"
+            algo = self.__fdt_get_string(f'{node}/signature', 'algo')
+            assert algo == sign_algo + "\n", "Missing expected signature algo!"
+
+
+@pytest.mark.buildconfigspec('fit_signature')
+@pytest.mark.requiredtool('fdtget')
+def test_fit_auto_signed(u_boot_console):
+    """Test that mkimage generates auto-FIT with signatures/hashes as expected.
+
+    The mkimage tool can create auto generated (i.e. without an ITS file
+    provided as input) FIT in three different flavours: with crc32 checksums
+    of 'images' subnodes; with signatures of 'images' subnodes; with sha1
+    hashes of 'images' subnodes and signatures of 'configurations' subnodes.
+    This test verifies that auto-FIT are generated as expected, in all of
+    the three flavours, including check of hashes and signatures (except for
+    configurations ones).
+
+    The test does not run the sandbox. It only checks the host tool mkimage.
+    """
+    cons = u_boot_console
+    mkimage = cons.config.build_dir + '/tools/mkimage'
+    tempdir = os.path.join(cons.config.result_dir, 'auto_fit')
+    os.makedirs(tempdir, exist_ok=True)
+    kernel_file = f'{tempdir}/vmlinuz'
+    dt1_file = f'{tempdir}/dt-1.dtb'
+    dt2_file = f'{tempdir}/dt-2.dtb'
+    key_name = 'sign-key'
+    sign_algo = 'sha256,rsa4096'
+    key_file = f'{tempdir}/{key_name}.key'
+    fit_file = f'{tempdir}/test.fit'
+
+    # Create a fake kernel image and two dtb files with random data
+    with open(kernel_file, 'wb') as fd:
+        fd.write(os.urandom(512))
+
+    with open(dt1_file, 'wb') as fd:
+        fd.write(os.urandom(256))
+
+    with open(dt2_file, 'wb') as fd:
+        fd.write(os.urandom(256))
+
+    # Create 4096 RSA key and write to file to be read by mkimage
+    key = RSA.generate(bits=4096)
+    verifier = pkcs1_15.new(key)
+
+    with open(key_file, 'w') as fd:
+        fd.write(str(key.export_key(format='PEM').decode('ascii')))
+
+    b_args = " -d" + kernel_file + " -b" + dt1_file + " -b" + dt2_file
+    s_args = " -k" + tempdir + " -g" + key_name + " -o" + sign_algo
+
+    # 1 - Create auto FIT with images crc32 checksum, and verify it
+    util.run_and_log(cons, mkimage + ' -fauto' + b_args + " " + fit_file)
+
+    fit = SignedFitHelper(cons, fit_file)
+    if fit.build_nodes_sets() == 0:
+        raise ValueError('FIT-1 has no "/image" nor "/configuration" nodes')
+
+    fit.check_fit_crc32_images()
+
+    # 2 - Create auto FIT with signed images, and verify it
+    util.run_and_log(cons, mkimage + ' -fauto' + b_args + s_args + " " +
+        fit_file)
+
+    fit = SignedFitHelper(cons, fit_file)
+    if fit.build_nodes_sets() == 0:
+        raise ValueError('FIT-2 has no "/image" nor "/configuration" nodes')
+
+    fit.check_fit_signed_images(key_name, sign_algo, verifier)
+
+    # 3 - Create auto FIT with signed configs and hashed images, and verify it
+    util.run_and_log(cons, mkimage + ' -fauto-conf' + b_args + s_args + " " +
+        fit_file)
+
+    fit = SignedFitHelper(cons, fit_file)
+    if fit.build_nodes_sets() == 0:
+        raise ValueError('FIT-3 has no "/image" nor "/configuration" nodes')
+
+    fit.check_fit_signed_confgs(key_name, sign_algo)