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: / usr / share / crypto-policies / python / policygenerators /
Filename : bind.py
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# SPDX-License-Identifier: LGPL-2.1-or-later

# Copyright (c) 2019 Red Hat, Inc.
# Copyright (c) 2019 Tomáš Mráz <tmraz@fedoraproject.org>

from subprocess import check_output, CalledProcessError
from tempfile import mkstemp
import os

from .configgenerator import ConfigGenerator


class BindGenerator(ConfigGenerator):
	CONFIG_NAME = 'bind'
	SCOPES = {'dnssec', 'bind'}

	RELOAD_CMD = 'systemctl try-reload-or-restart bind.service 2>/dev/null || :\n'

	sign_not_map = {
		'DSA-SHA1': ('DSA', 'NSEC3DSA'),
		'RSA-SHA1': ('RSASHA1', 'NSEC3RSASHA1'),
		'RSA-SHA2-256': ('RSASHA256',),
		'RSA-SHA2-512': ('RSASHA512',),
		'ECDSA-SHA2-256': ('ECDSAP256SHA256',),  # + custom handling below
		'ECDSA-SHA2-384': ('ECDSAP384SHA384',),  # + custom handling below
		'EDDSA-ED25519': ('ED25519',),
		'EDDSA-ED448': ('ED448',),
	}

	hash_not_map = {
		'SHA1': 'SHA-1',
		'SHA2-256': 'SHA-256',
		'SHA2-384': 'SHA-384',
		'GOST': 'GOST',
	}

	@classmethod
	def generate_config(cls, policy):
		ip = policy.disabled
		s = ''

		s += 'disable-algorithms "." {\n'
		s += 'RSAMD5;\n'  # deprecated, disabled unconditionally
		s += 'ECCGOST;\n'  # deprecated, disabled unconditionally, no such knob
		for i in ip['sign']:
			try:
				for disabled_sign in cls.sign_not_map[i]:
					s += f'{disabled_sign};\n'
			except KeyError:
				pass
		if 'ECDSA-SHA256' not in ip['sign'] and 'SECP256R1' in ip['group']:
			s += 'ECDSAP256SHA256;\n'  # additionally disabled on lack of P-256
		if 'ECDSA-SHA384' not in ip['sign'] and 'SECP384R1' in ip['group']:
			s += 'ECDSAP384SHA384;\n'  # additionally disabled on lack of P-384
		s += '};\n'

		s += 'disable-ds-digests "." {\n'
		for i in ip['hash']:
			try:
				s += f'{cls.hash_not_map[i]};\n'
			except KeyError:
				pass
		s += '};\n'

		return s

	@classmethod
	def test_config(cls, config):
		fd, path = mkstemp()

		try:
			with os.fdopen(fd, 'w') as f:
				f.write('options {\n')
				f.write(config)
				f.write('\n};\n')
			try:
				_ = check_output(["/usr/sbin/named-checkconf", path])
			except CalledProcessError:
				cls.eprint("There is an error in bind generated policy")
				cls.eprint("Policy:\n%s" % config)
				return False
			except OSError:
				# Ignore missing check command
				pass
		finally:
			os.unlink(path)

		return True