libcloud/security.py

# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You 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.
"""
Security (SSL) Settings

Usage:
    import libcloud.security
    libcloud.security.VERIFY_SSL_CERT = True

    # Optional.
    libcloud.security.CA_CERTS_PATH.append('/path/to/cacert.txt')
"""

import os
import ssl

__all__ = [
    'VERIFY_SSL_CERT',
    'SSL_VERSION',
    'CA_CERTS_PATH'
]

VERIFY_SSL_CERT = True

SSL_VERSION = ssl.PROTOCOL_TLSv1

# True to use certifi CA bundle path when certifi library is available
USE_CERTIFI = os.environ.get('LIBCLOUD_SSL_USE_CERTIFI', True)
USE_CERTIFI = str(USE_CERTIFI).lower() in ['true', '1']

# File containing one or more PEM-encoded CA certificates
# concatenated together.
CA_CERTS_PATH = [
    # centos/fedora: openssl
    '/etc/pki/tls/certs/ca-bundle.crt',

    # debian/ubuntu/arch/gentoo: ca-certificates
    '/etc/ssl/certs/ca-certificates.crt',

    # freebsd: ca_root_nss
    '/usr/local/share/certs/ca-root-nss.crt',

    # macports: curl-ca-bundle
    '/opt/local/share/curl/curl-ca-bundle.crt',

    # homebrew: openssl
    '/usr/local/etc/openssl/cert.pem',

    # homebrew: curl-ca-bundle (backward compatibility)
    '/usr/local/opt/curl-ca-bundle/share/ca-bundle.crt',

    # opensuse/sles: openssl
    '/etc/ssl/certs/YaST-CA.pem',
]

# Insert certifi CA bundle path to the front of Libcloud CA bundle search
# path if certifi is available
try:
    import certifi
except ImportError:
    has_certifi = False
else:
    has_certifi = True

if has_certifi and USE_CERTIFI:
    certifi_ca_bundle_path = certifi.where()
    CA_CERTS_PATH.insert(0, certifi_ca_bundle_path)

# Allow user to explicitly specify which CA bundle to use, using an environment
# variable
environment_cert_file = os.getenv('SSL_CERT_FILE', None)
if environment_cert_file is not None:
    # Make sure the file exists
    if not os.path.exists(environment_cert_file):
        raise ValueError('Certificate file %s doesn\'t exist' %
                         (environment_cert_file))

    if not os.path.isfile(environment_cert_file):
        raise ValueError('Certificate file can\'t be a directory')

    # If a provided file exists we ignore other common paths because we
    # don't want to fall-back to a potentially less restrictive bundle
    CA_CERTS_PATH = [environment_cert_file]

CA_CERTS_UNAVAILABLE_ERROR_MSG = (
    'No CA Certificates were found in CA_CERTS_PATH. For information on '
    'how to get required certificate files, please visit '
    'https://libcloud.readthedocs.org/en/latest/other/'
    'ssl-certificate-validation.html'
)

VERIFY_SSL_DISABLED_MSG = (
    'SSL certificate verification is disabled, this can pose a '
    'security risk. For more information how to enable the SSL '
    'certificate verification, please visit the libcloud '
    'documentation.'
)