Re: [PATCH RFC v2 5/5] test/py: ecdsa: Add test for mkimage ECDSA signing
Hi Alexandru,
On Wed, 30 Dec 2020 at 14:00, Alexandru Gagniuc wrote:
>
> Add a test to make sure that the ECDSA signatures generated by
> mkimage can be verified successfully. pyCryptodomex was chosen as the
> crypto library because it integrates much better with python code.
> Using openssl would have been unnecessarily painful.
>
> Signed-off-by: Alexandru Gagniuc
> ---
> test/py/tests/test_fit_ecdsa.py | 111
> 1 file changed, 111 insertions(+)
> create mode 100644 test/py/tests/test_fit_ecdsa.py
>
This test looks fine but the functions need full comments. I do think
it might be worth putting the code in test_vboot, particularly when
you get to the sandbox implementation.
For installing the Python library, you might need to update the docs
in test/ and perhaps install things in .gitlab-ci.yml and .azure...
> diff --git a/test/py/tests/test_fit_ecdsa.py b/test/py/tests/test_fit_ecdsa.py
> new file mode 100644
> index 00..957964d329
> --- /dev/null
> +++ b/test/py/tests/test_fit_ecdsa.py
> @@ -0,0 +1,111 @@
> +# SPDX-License-Identifier: GPL-2.0+
> +#
> +# Copyright (c) 2020, Alexandru Gagniuc
> +
> +"""
> +Test ECDSA signing of FIT images
> +
> +This test uses mkimage to sign an existing FIT image with an ECDSA key. The
> +signature is then extracted, and verified against pyCryptodome.
> +This test doesn't run the sandbox. It only checks the host tool 'mkimage'
> +"""
> +
> +import pytest
> +import u_boot_utils as util
> +from Cryptodome.Hash import SHA256
> +from Cryptodome.PublicKey import ECC
> +from Cryptodome.Signature import DSS
> +
> +class SignableFitImage(object):
> +""" Helper to manipulate a FIT image on disk """
> +def __init__(self, cons, file_name):
> +self.fit = file_name
> +self.cons = cons
> +self.signable_nodes = set()
> +
> +def __fdt_list(self, path):
> +return util.run_and_log(self.cons, f'fdtget -l {self.fit} {path}')
> +
> +def __fdt_set(self, node, **prop_value):
> +for prop, value in prop_value.items():
> +util.run_and_log(self.cons, f'fdtput -ts {self.fit} {node}
> {prop} {value}')
> +
> +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 find_signable_image_nodes(self):
> +for node in self.__fdt_list('/images').split():
> +image = f'/images/{node}'
> +if 'signature' in self.__fdt_list(image):
> +self.signable_nodes.add(image)
> +
> +return self.signable_nodes
> +
> +def change_signature_algo_to_ecdsa(self):
> +for image in self.signable_nodes:
> +self.__fdt_set(f'{image}/signature', algo='sha256,ecdsa256')
> +
> +def sign(self, mkimage, key_file):
> +util.run_and_log(self.cons, [mkimage, '-F', self.fit,
> f'-k{key_file}'])
> +
> +def check_signatures(self, key):
> +for image in self.signable_nodes:
> +raw_sig = self.__fdt_get_binary(f'{image}/signature', 'value')
> +raw_bin = self.__fdt_get_binary(image, 'data')
> +
> +sha = SHA256.new(raw_bin)
> +verifier = DSS.new(key, 'fips-186-3')
> +verifier.verify(sha, bytes(raw_sig))
> +
> +
> +@pytest.mark.buildconfigspec('fit_signature')
> +@pytest.mark.requiredtool('dtc')
> +@pytest.mark.requiredtool('fdtget')
> +@pytest.mark.requiredtool('fdtput')
> +def test_fit_ecdsa(u_boot_console):
> +"""TODO: Document me
> +"""
> +def generate_ecdsa_key():
> +return ECC.generate(curve='prime256v1')
> +
> +def assemble_fit_image(dest_fit, its, destdir):
> +dtc_args = f'-I dts -O dtb -i {destdir}'
> +util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f', its,
> dest_fit])
> +
> +def dtc(dts):
> +dtb = dts.replace('.dts', '.dtb')
> +util.run_and_log(cons, f'dtc {datadir}/{dts} -O dtb -o
> {tempdir}/{dtb}')
> +
> +cons = u_boot_console
> +mkimage = cons.config.build_dir + '/tools/mkimage'
> +datadir = cons.config.source_dir + '/test/py/tests/vboot/'
> +tempdir = cons.config.result_dir
> +key_file = f'{tempdir}/ecdsa-test-key.pem'
> +fit_file = f'{tempdir}/test.fit'
> +dtc('sandbox-kernel.dts')
> +
> +key = generate_ecdsa_key()
> +
> +# Create a number kernel image with zeroes
> +with open(f'{tempdir}/test-kernel.bin', 'w') as fd:
> +fd.write(500 * chr(0))
> +
> +with open(key_file, 'w') as f:
> +f.write(key.export_key(format='PEM'))
> +
> +assemble_fit_image(fit_file, f'{datadir}/sign-images-sha256.its',
> tempdir)
> +
> +fit = SignableFitImage(cons, fit_file)
> +nodes = fit.find_signable_image_nodes()
> +if len(nodes) == 0:
> +raise ValueError('FIT image has no "/image
Re: [PATCH RFC v2 5/5] test/py: ecdsa: Add test for mkimage ECDSA signing
On 1/7/21 6:35 AM, Simon Glass wrote:
Hi Alexandru,
On Wed, 30 Dec 2020 at 14:00, Alexandru Gagniuc wrote:
Add a test to make sure that the ECDSA signatures generated by
mkimage can be verified successfully. pyCryptodomex was chosen as the
crypto library because it integrates much better with python code.
Using openssl would have been unnecessarily painful.
Signed-off-by: Alexandru Gagniuc
---
test/py/tests/test_fit_ecdsa.py | 111
1 file changed, 111 insertions(+)
create mode 100644 test/py/tests/test_fit_ecdsa.py
This test looks fine but the functions need full comments. I do think
it might be worth putting the code in test_vboot, particularly when
you get to the sandbox implementation.
test_vboot seems to be testing the bootm command, while with this test
I'm only looking to test the host-side (mkimage). In the next series, I
won't have a software implementation of ECDSA, like RSA_MOD_EXP. I will
use the ROM on the stm32mp. So there won't be somthing testable in the
sandbox.
For installing the Python library, you might need to update the docs
in test/ and perhaps install things in .gitlab-ci.yml and .azure...
Sure, let me look into this.
diff --git a/test/py/tests/test_fit_ecdsa.py b/test/py/tests/test_fit_ecdsa.py
new file mode 100644
index 00..957964d329
--- /dev/null
+++ b/test/py/tests/test_fit_ecdsa.py
@@ -0,0 +1,111 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (c) 2020, Alexandru Gagniuc
+
+"""
+Test ECDSA signing of FIT images
+
+This test uses mkimage to sign an existing FIT image with an ECDSA key. The
+signature is then extracted, and verified against pyCryptodome.
+This test doesn't run the sandbox. It only checks the host tool 'mkimage'
+"""
+
+import pytest
+import u_boot_utils as util
+from Cryptodome.Hash import SHA256
+from Cryptodome.PublicKey import ECC
+from Cryptodome.Signature import DSS
+
+class SignableFitImage(object):
+""" Helper to manipulate a FIT image on disk """
+def __init__(self, cons, file_name):
+self.fit = file_name
+self.cons = cons
+self.signable_nodes = set()
+
+def __fdt_list(self, path):
+return util.run_and_log(self.cons, f'fdtget -l {self.fit} {path}')
+
+def __fdt_set(self, node, **prop_value):
+for prop, value in prop_value.items():
+util.run_and_log(self.cons, f'fdtput -ts {self.fit} {node} {prop}
{value}')
+
+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 find_signable_image_nodes(self):
+for node in self.__fdt_list('/images').split():
+image = f'/images/{node}'
+if 'signature' in self.__fdt_list(image):
+self.signable_nodes.add(image)
+
+return self.signable_nodes
+
+def change_signature_algo_to_ecdsa(self):
+for image in self.signable_nodes:
+self.__fdt_set(f'{image}/signature', algo='sha256,ecdsa256')
+
+def sign(self, mkimage, key_file):
+util.run_and_log(self.cons, [mkimage, '-F', self.fit, f'-k{key_file}'])
+
+def check_signatures(self, key):
+for image in self.signable_nodes:
+raw_sig = self.__fdt_get_binary(f'{image}/signature', 'value')
+raw_bin = self.__fdt_get_binary(image, 'data')
+
+sha = SHA256.new(raw_bin)
+verifier = DSS.new(key, 'fips-186-3')
+verifier.verify(sha, bytes(raw_sig))
+
+
+@pytest.mark.buildconfigspec('fit_signature')
+@pytest.mark.requiredtool('dtc')
+@pytest.mark.requiredtool('fdtget')
+@pytest.mark.requiredtool('fdtput')
+def test_fit_ecdsa(u_boot_console):
+"""TODO: Document me
+"""
+def generate_ecdsa_key():
+return ECC.generate(curve='prime256v1')
+
+def assemble_fit_image(dest_fit, its, destdir):
+dtc_args = f'-I dts -O dtb -i {destdir}'
+util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f', its, dest_fit])
+
+def dtc(dts):
+dtb = dts.replace('.dts', '.dtb')
+util.run_and_log(cons, f'dtc {datadir}/{dts} -O dtb -o
{tempdir}/{dtb}')
+
+cons = u_boot_console
+mkimage = cons.config.build_dir + '/tools/mkimage'
+datadir = cons.config.source_dir + '/test/py/tests/vboot/'
+tempdir = cons.config.result_dir
+key_file = f'{tempdir}/ecdsa-test-key.pem'
+fit_file = f'{tempdir}/test.fit'
+dtc('sandbox-kernel.dts')
+
+key = generate_ecdsa_key()
+
+# Create a number kernel image with zeroes
+with open(f'{tempdir}/test-kernel.bin', 'w') as fd:
+fd.write(500 * chr(0))
+
+with open(key_file, 'w') as f:
+f.write(key.export_key(format='PEM'))
+
+assemble_fit_image(fit_file, f'{datadir}/sign-images-sha256.its', tempdir)
+
+fit = SignableFitImage(cons, fit_file
Re: [PATCH RFC v2 5/5] test/py: ecdsa: Add test for mkimage ECDSA signing
Hi Alex, On Thu, 7 Jan 2021 at 09:44, Alex G. wrote: > > > > On 1/7/21 6:35 AM, Simon Glass wrote: > > Hi Alexandru, > > > > On Wed, 30 Dec 2020 at 14:00, Alexandru Gagniuc > > wrote: > >> > >> Add a test to make sure that the ECDSA signatures generated by > >> mkimage can be verified successfully. pyCryptodomex was chosen as the > >> crypto library because it integrates much better with python code. > >> Using openssl would have been unnecessarily painful. > >> > >> Signed-off-by: Alexandru Gagniuc > >> --- > >> test/py/tests/test_fit_ecdsa.py | 111 > >> 1 file changed, 111 insertions(+) > >> create mode 100644 test/py/tests/test_fit_ecdsa.py > >> > > > > This test looks fine but the functions need full comments. I do think > > it might be worth putting the code in test_vboot, particularly when > > you get to the sandbox implementation. > > test_vboot seems to be testing the bootm command, while with this test It also runs fit_check_sign to check the signature. > I'm only looking to test the host-side (mkimage). In the next series, I > won't have a software implementation of ECDSA, like RSA_MOD_EXP. I will > use the ROM on the stm32mp. So there won't be somthing testable in the > sandbox. I'm not sure that is a good idea. With driver model you'll end up creating a ECDSA driver I suppose, so implementing it for sandbox should be possible. Is it a complicated algorithm? Without that, I'm not even sure how fit_check_sign could work? > [..] Regards, Simon
Re: [PATCH RFC v2 5/5] test/py: ecdsa: Add test for mkimage ECDSA signing
On 1/7/21 11:31 AM, Simon Glass wrote: Hi Alex, On Thu, 7 Jan 2021 at 09:44, Alex G. wrote: On 1/7/21 6:35 AM, Simon Glass wrote: Hi Alexandru, On Wed, 30 Dec 2020 at 14:00, Alexandru Gagniuc wrote: Add a test to make sure that the ECDSA signatures generated by mkimage can be verified successfully. pyCryptodomex was chosen as the crypto library because it integrates much better with python code. Using openssl would have been unnecessarily painful. Signed-off-by: Alexandru Gagniuc --- test/py/tests/test_fit_ecdsa.py | 111 1 file changed, 111 insertions(+) create mode 100644 test/py/tests/test_fit_ecdsa.py This test looks fine but the functions need full comments. I do think it might be worth putting the code in test_vboot, particularly when you get to the sandbox implementation. test_vboot seems to be testing the bootm command, while with this test It also runs fit_check_sign to check the signature. Hmm, it backends on tools/check_fit_sign. Would be an interesting execrise to extend it ecdsa signatures, but that would take significantly more effort than the simple test I am proposing here. I'm only looking to test the host-side (mkimage). In the next series, I won't have a software implementation of ECDSA, like RSA_MOD_EXP. I will use the ROM on the stm32mp. So there won't be somthing testable in the sandbox. I'm not sure that is a good idea. With driver model you'll end up creating a ECDSA driver I suppose, so implementing it for sandbox should be possible. Is it a complicated algorithm? A software implementation of ECDSA is outside the scope of my project. Without that, I'm not even sure how fit_check_sign could work? It uses the ops->verify in ecdsa-libcrypto, does it not? [..] Regards, Simon
