85 lines
3.0 KiB
Python
85 lines
3.0 KiB
Python
# Copyright 2012 Nebula, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import logging
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import os
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import random
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import string
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from oslo_concurrency import lockutils
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class FilePermissionError(Exception):
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"""The key file permissions are insecure."""
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def generate_key(key_length=64):
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"""Secret key generator.
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The quality of randomness depends on operating system support,
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see http://docs.python.org/library/random.html#random.SystemRandom.
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"""
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if hasattr(random, 'SystemRandom'):
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logging.info('Generating a secure random key using SystemRandom.')
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choice = random.SystemRandom().choice
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else:
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msg = "WARNING: SystemRandom not present. Generating a random "\
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"key using random.choice (NOT CRYPTOGRAPHICALLY SECURE)."
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logging.warning(msg)
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choice = random.choice
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return ''.join(map(lambda x: choice(string.digits + string.ascii_letters),
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range(key_length)))
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def read_from_file(key_file='.secret_key'):
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if (os.stat(key_file).st_mode & 0o777) != 0o600:
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raise FilePermissionError(
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"Insecure permissions on key file %s, should be 0600." %
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os.path.abspath(key_file))
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with open(key_file, 'r') as f:
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key = f.readline()
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return key
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def generate_or_read_from_file(key_file='.secret_key', key_length=64):
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"""Multiprocess-safe secret key file generator.
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Useful to replace the default (and thus unsafe) SECRET_KEY in settings.py
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upon first start. Save to use, i.e. when multiple Python interpreters
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serve the dashboard Django application (e.g. in a mod_wsgi + daemonized
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environment). Also checks if file permissions are set correctly and
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throws an exception if not.
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"""
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abspath = os.path.abspath(key_file)
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# check, if key_file already exists
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# if yes, then just read and return key
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if os.path.exists(key_file):
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key = read_from_file(key_file)
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return key
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# otherwise, first lock to make sure only one process
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lock = lockutils.external_lock(key_file + ".lock",
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lock_path=os.path.dirname(abspath))
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with lock:
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if not os.path.exists(key_file):
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key = generate_key(key_length)
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old_umask = os.umask(0o177) # Use '0600' file permissions
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with open(key_file, 'w') as f:
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f.write(key)
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os.umask(old_umask)
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else:
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key = read_from_file(key_file)
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return key
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