102 lines
4.1 KiB
Python
102 lines
4.1 KiB
Python
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"""Secure serializer."""
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from kombu.serialization import dumps, loads, registry
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from kombu.utils.encoding import bytes_to_str, ensure_bytes, str_to_bytes
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from celery.app.defaults import DEFAULT_SECURITY_DIGEST
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from celery.utils.serialization import b64decode, b64encode
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from .certificate import Certificate, FSCertStore
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from .key import PrivateKey
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from .utils import get_digest_algorithm, reraise_errors
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__all__ = ('SecureSerializer', 'register_auth')
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class SecureSerializer:
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"""Signed serializer."""
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def __init__(self, key=None, cert=None, cert_store=None,
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digest=DEFAULT_SECURITY_DIGEST, serializer='json'):
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self._key = key
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self._cert = cert
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self._cert_store = cert_store
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self._digest = get_digest_algorithm(digest)
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self._serializer = serializer
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def serialize(self, data):
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"""Serialize data structure into string."""
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assert self._key is not None
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assert self._cert is not None
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with reraise_errors('Unable to serialize: {0!r}', (Exception,)):
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content_type, content_encoding, body = dumps(
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bytes_to_str(data), serializer=self._serializer)
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# What we sign is the serialized body, not the body itself.
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# this way the receiver doesn't have to decode the contents
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# to verify the signature (and thus avoiding potential flaws
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# in the decoding step).
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body = ensure_bytes(body)
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return self._pack(body, content_type, content_encoding,
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signature=self._key.sign(body, self._digest),
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signer=self._cert.get_id())
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def deserialize(self, data):
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"""Deserialize data structure from string."""
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assert self._cert_store is not None
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with reraise_errors('Unable to deserialize: {0!r}', (Exception,)):
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payload = self._unpack(data)
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signature, signer, body = (payload['signature'],
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payload['signer'],
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payload['body'])
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self._cert_store[signer].verify(body, signature, self._digest)
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return loads(bytes_to_str(body), payload['content_type'],
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payload['content_encoding'], force=True)
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def _pack(self, body, content_type, content_encoding, signer, signature,
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sep=str_to_bytes('\x00\x01')):
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fields = sep.join(
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ensure_bytes(s) for s in [signer, signature, content_type,
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content_encoding, body]
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)
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return b64encode(fields)
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def _unpack(self, payload, sep=str_to_bytes('\x00\x01')):
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raw_payload = b64decode(ensure_bytes(payload))
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first_sep = raw_payload.find(sep)
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signer = raw_payload[:first_sep]
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signer_cert = self._cert_store[signer]
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# shift 3 bits right to get signature length
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# 2048bit rsa key has a signature length of 256
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# 4096bit rsa key has a signature length of 512
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sig_len = signer_cert.get_pubkey().key_size >> 3
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sep_len = len(sep)
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signature_start_position = first_sep + sep_len
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signature_end_position = signature_start_position + sig_len
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signature = raw_payload[
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signature_start_position:signature_end_position
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]
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v = raw_payload[signature_end_position + sep_len:].split(sep)
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return {
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'signer': signer,
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'signature': signature,
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'content_type': bytes_to_str(v[0]),
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'content_encoding': bytes_to_str(v[1]),
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'body': bytes_to_str(v[2]),
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}
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def register_auth(key=None, key_password=None, cert=None, store=None,
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digest=DEFAULT_SECURITY_DIGEST,
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serializer='json'):
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"""Register security serializer."""
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s = SecureSerializer(key and PrivateKey(key, password=key_password),
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cert and Certificate(cert),
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store and FSCertStore(store),
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digest, serializer=serializer)
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registry.register('auth', s.serialize, s.deserialize,
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content_type='application/data',
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content_encoding='utf-8')
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