This file is indexed.

/usr/lib/python2.7/dist-packages/pymongo/auth.py is in python-pymongo 3.4.0-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
# Copyright 2013-2015 MongoDB, Inc.
#
# Licensed 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.

"""Authentication helpers."""

import hmac
import socket

HAVE_KERBEROS = True
try:
    import winkerberos as kerberos
except ImportError:
    try:
        import kerberos
    except ImportError:
        HAVE_KERBEROS = False

from base64 import standard_b64decode, standard_b64encode
from collections import namedtuple
from hashlib import md5, sha1
from random import SystemRandom

from bson.binary import Binary
from bson.py3compat import b, string_type, _unicode, PY3
from bson.son import SON
from pymongo.errors import ConfigurationError, OperationFailure


MECHANISMS = frozenset(
    ['GSSAPI', 'MONGODB-CR', 'MONGODB-X509', 'PLAIN', 'SCRAM-SHA-1', 'DEFAULT'])
"""The authentication mechanisms supported by PyMongo."""


MongoCredential = namedtuple(
    'MongoCredential',
    ['mechanism', 'source', 'username', 'password', 'mechanism_properties'])
"""A hashable namedtuple of values used for authentication."""


GSSAPIProperties = namedtuple('GSSAPIProperties',
                              ['service_name',
                               'canonicalize_host_name',
                               'service_realm'])
"""Mechanism properties for GSSAPI authentication."""


def _build_credentials_tuple(mech, source, user, passwd, extra):
    """Build and return a mechanism specific credentials tuple.
    """
    user = _unicode(user) if user is not None else None
    password = passwd if passwd is None else _unicode(passwd)
    if mech == 'GSSAPI':
        properties = extra.get('authmechanismproperties', {})
        service_name = properties.get('SERVICE_NAME', 'mongodb')
        canonicalize = properties.get('CANONICALIZE_HOST_NAME', False)
        service_realm = properties.get('SERVICE_REALM')
        props = GSSAPIProperties(service_name=service_name,
                                 canonicalize_host_name=canonicalize,
                                 service_realm=service_realm)
        # Source is always $external.
        return MongoCredential(mech, '$external', user, password, props)
    elif mech == 'MONGODB-X509':
        # user can be None.
        return MongoCredential(mech, '$external', user, None, None)
    else:
        if passwd is None:
            raise ConfigurationError("A password is required.")
        return MongoCredential(mech, source, user, password, None)


if PY3:
    def _xor(fir, sec):
        """XOR two byte strings together (python 3.x)."""
        return b"".join([bytes([x ^ y]) for x, y in zip(fir, sec)])


    _from_bytes = int.from_bytes
    _to_bytes = int.to_bytes
else:
    from binascii import (hexlify as _hexlify,
                          unhexlify as _unhexlify)


    def _xor(fir, sec):
        """XOR two byte strings together (python 2.x)."""
        return b"".join([chr(ord(x) ^ ord(y)) for x, y in zip(fir, sec)])


    def _from_bytes(value, dummy, int=int, _hexlify=_hexlify):
        """An implementation of int.from_bytes for python 2.x."""
        return int(_hexlify(value), 16)


    def _to_bytes(value, dummy0, dummy1, _unhexlify=_unhexlify):
        """An implementation of int.to_bytes for python 2.x."""
        return _unhexlify('%040x' % value)


try:
    # The fastest option, if it's been compiled to use OpenSSL's HMAC.
    from backports.pbkdf2 import pbkdf2_hmac

    def _hi(data, salt, iterations):
        return pbkdf2_hmac('sha1', data, salt, iterations)

except ImportError:
    try:
        # Python 2.7.8+, or Python 3.4+.
        from hashlib import pbkdf2_hmac

        def _hi(data, salt, iterations):
            return pbkdf2_hmac('sha1', data, salt, iterations)

    except ImportError:

        def _hi(data, salt, iterations):
            """A simple implementation of PBKDF2."""
            mac = hmac.HMAC(data, None, sha1)

            def _digest(msg, mac=mac):
                """Get a digest for msg."""
                _mac = mac.copy()
                _mac.update(msg)
                return _mac.digest()

            from_bytes = _from_bytes
            to_bytes = _to_bytes

            _u1 = _digest(salt + b'\x00\x00\x00\x01')
            _ui = from_bytes(_u1, 'big')
            for _ in range(iterations - 1):
                _u1 = _digest(_u1)
                _ui ^= from_bytes(_u1, 'big')
            return to_bytes(_ui, 20, 'big')

try:
    from hmac import compare_digest
except ImportError:
    if PY3:
        def _xor_bytes(a, b):
            return a ^ b
    else:
        def _xor_bytes(a, b, _ord=ord):
            return _ord(a) ^ _ord(b)

    # Python 2.x < 2.7.7 and Python 3.x < 3.3
    # References:
    #  - http://bugs.python.org/issue14532
    #  - http://bugs.python.org/issue14955
    #  - http://bugs.python.org/issue15061
    def compare_digest(a, b, _xor_bytes=_xor_bytes):
        left = None
        right = b
        if len(a) == len(b):
            left = a
            result = 0
        if len(a) != len(b):
            left = b
            result = 1

        for x, y in zip(left, right):
            result |= _xor_bytes(x, y)
        return result == 0


def _parse_scram_response(response):
    """Split a scram response into key, value pairs."""
    return dict(item.split(b"=", 1) for item in response.split(b","))


def _authenticate_scram_sha1(credentials, sock_info):
    """Authenticate using SCRAM-SHA-1."""
    username = credentials.username
    password = credentials.password
    source = credentials.source

    # Make local
    _hmac = hmac.HMAC
    _sha1 = sha1

    user = username.encode("utf-8").replace(b"=", b"=3D").replace(b",", b"=2C")
    nonce = standard_b64encode(
        (("%s" % (SystemRandom().random(),))[2:]).encode("utf-8"))
    first_bare = b"n=" + user + b",r=" + nonce

    cmd = SON([('saslStart', 1),
               ('mechanism', 'SCRAM-SHA-1'),
               ('payload', Binary(b"n,," + first_bare)),
               ('autoAuthorize', 1)])
    res = sock_info.command(source, cmd)

    server_first = res['payload']
    parsed = _parse_scram_response(server_first)
    iterations = int(parsed[b'i'])
    salt = parsed[b's']
    rnonce = parsed[b'r']
    if not rnonce.startswith(nonce):
        raise OperationFailure("Server returned an invalid nonce.")

    without_proof = b"c=biws,r=" + rnonce
    salted_pass = _hi(_password_digest(username, password).encode("utf-8"),
                      standard_b64decode(salt),
                      iterations)
    client_key = _hmac(salted_pass, b"Client Key", _sha1).digest()
    stored_key = _sha1(client_key).digest()
    auth_msg = b",".join((first_bare, server_first, without_proof))
    client_sig = _hmac(stored_key, auth_msg, _sha1).digest()
    client_proof = b"p=" + standard_b64encode(_xor(client_key, client_sig))
    client_final = b",".join((without_proof, client_proof))

    server_key = _hmac(salted_pass, b"Server Key", _sha1).digest()
    server_sig = standard_b64encode(
        _hmac(server_key, auth_msg, _sha1).digest())

    cmd = SON([('saslContinue', 1),
               ('conversationId', res['conversationId']),
               ('payload', Binary(client_final))])
    res = sock_info.command(source, cmd)

    parsed = _parse_scram_response(res['payload'])
    if not compare_digest(parsed[b'v'], server_sig):
        raise OperationFailure("Server returned an invalid signature.")

    # Depending on how it's configured, Cyrus SASL (which the server uses)
    # requires a third empty challenge.
    if not res['done']:
        cmd = SON([('saslContinue', 1),
                   ('conversationId', res['conversationId']),
                   ('payload', Binary(b''))])
        res = sock_info.command(source, cmd)
        if not res['done']:
            raise OperationFailure('SASL conversation failed to complete.')


def _password_digest(username, password):
    """Get a password digest to use for authentication.
    """
    if not isinstance(password, string_type):
        raise TypeError("password must be an "
                        "instance of %s" % (string_type.__name__,))
    if len(password) == 0:
        raise ValueError("password can't be empty")
    if not isinstance(username, string_type):
        raise TypeError("password must be an "
                        "instance of  %s" % (string_type.__name__,))

    md5hash = md5()
    data = "%s:mongo:%s" % (username, password)
    md5hash.update(data.encode('utf-8'))
    return _unicode(md5hash.hexdigest())


def _auth_key(nonce, username, password):
    """Get an auth key to use for authentication.
    """
    digest = _password_digest(username, password)
    md5hash = md5()
    data = "%s%s%s" % (nonce, username, digest)
    md5hash.update(data.encode('utf-8'))
    return _unicode(md5hash.hexdigest())


def _authenticate_gssapi(credentials, sock_info):
    """Authenticate using GSSAPI.
    """
    if not HAVE_KERBEROS:
        raise ConfigurationError('The "kerberos" module must be '
                                 'installed to use GSSAPI authentication.')

    try:
        username = credentials.username
        password = credentials.password
        props = credentials.mechanism_properties
        # Starting here and continuing through the while loop below - establish
        # the security context. See RFC 4752, Section 3.1, first paragraph.
        host = sock_info.address[0]
        if props.canonicalize_host_name:
            host = socket.getfqdn(host)
        service = props.service_name + '@' + host
        if props.service_realm is not None:
            service = service + '@' + props.service_realm

        if password is not None:
            if '@' in username:
                user, domain = username.split('@', 1)
            else:
                user, domain = username, None
            result, ctx = kerberos.authGSSClientInit(
                service, gssflags=kerberos.GSS_C_MUTUAL_FLAG,
                user=user, domain=domain, password=password)
        else:
            result, ctx = kerberos.authGSSClientInit(
                service, gssflags=kerberos.GSS_C_MUTUAL_FLAG)

        if result != kerberos.AUTH_GSS_COMPLETE:
            raise OperationFailure('Kerberos context failed to initialize.')

        try:
            # pykerberos uses a weird mix of exceptions and return values
            # to indicate errors.
            # 0 == continue, 1 == complete, -1 == error
            # Only authGSSClientStep can return 0.
            if kerberos.authGSSClientStep(ctx, '') != 0:
                raise OperationFailure('Unknown kerberos '
                                       'failure in step function.')

            # Start a SASL conversation with mongod/s
            # Note: pykerberos deals with base64 encoded byte strings.
            # Since mongo accepts base64 strings as the payload we don't
            # have to use bson.binary.Binary.
            payload = kerberos.authGSSClientResponse(ctx)
            cmd = SON([('saslStart', 1),
                       ('mechanism', 'GSSAPI'),
                       ('payload', payload),
                       ('autoAuthorize', 1)])
            response = sock_info.command('$external', cmd)

            # Limit how many times we loop to catch protocol / library issues
            for _ in range(10):
                result = kerberos.authGSSClientStep(ctx,
                                                    str(response['payload']))
                if result == -1:
                    raise OperationFailure('Unknown kerberos '
                                           'failure in step function.')

                payload = kerberos.authGSSClientResponse(ctx) or ''

                cmd = SON([('saslContinue', 1),
                           ('conversationId', response['conversationId']),
                           ('payload', payload)])
                response = sock_info.command('$external', cmd)

                if result == kerberos.AUTH_GSS_COMPLETE:
                    break
            else:
                raise OperationFailure('Kerberos '
                                       'authentication failed to complete.')

            # Once the security context is established actually authenticate.
            # See RFC 4752, Section 3.1, last two paragraphs.
            if kerberos.authGSSClientUnwrap(ctx,
                                            str(response['payload'])) != 1:
                raise OperationFailure('Unknown kerberos '
                                       'failure during GSS_Unwrap step.')

            if kerberos.authGSSClientWrap(ctx,
                                          kerberos.authGSSClientResponse(ctx),
                                          username) != 1:
                raise OperationFailure('Unknown kerberos '
                                       'failure during GSS_Wrap step.')

            payload = kerberos.authGSSClientResponse(ctx)
            cmd = SON([('saslContinue', 1),
                       ('conversationId', response['conversationId']),
                       ('payload', payload)])
            sock_info.command('$external', cmd)

        finally:
            kerberos.authGSSClientClean(ctx)

    except kerberos.KrbError as exc:
        raise OperationFailure(str(exc))


def _authenticate_plain(credentials, sock_info):
    """Authenticate using SASL PLAIN (RFC 4616)
    """
    source = credentials.source
    username = credentials.username
    password = credentials.password
    payload = ('\x00%s\x00%s' % (username, password)).encode('utf-8')
    cmd = SON([('saslStart', 1),
               ('mechanism', 'PLAIN'),
               ('payload', Binary(payload)),
               ('autoAuthorize', 1)])
    sock_info.command(source, cmd)


def _authenticate_cram_md5(credentials, sock_info):
    """Authenticate using CRAM-MD5 (RFC 2195)
    """
    source = credentials.source
    username = credentials.username
    password = credentials.password
    # The password used as the mac key is the
    # same as what we use for MONGODB-CR
    passwd = _password_digest(username, password)
    cmd = SON([('saslStart', 1),
               ('mechanism', 'CRAM-MD5'),
               ('payload', Binary(b'')),
               ('autoAuthorize', 1)])
    response = sock_info.command(source, cmd)
    # MD5 as implicit default digest for digestmod is deprecated
    # in python 3.4
    mac = hmac.HMAC(key=passwd.encode('utf-8'), digestmod=md5)
    mac.update(response['payload'])
    challenge = username.encode('utf-8') + b' ' + b(mac.hexdigest())
    cmd = SON([('saslContinue', 1),
               ('conversationId', response['conversationId']),
               ('payload', Binary(challenge))])
    sock_info.command(source, cmd)


def _authenticate_x509(credentials, sock_info):
    """Authenticate using MONGODB-X509.
    """
    query = SON([('authenticate', 1),
                 ('mechanism', 'MONGODB-X509')])
    if credentials.username is not None:
        query['user'] = credentials.username
    elif sock_info.max_wire_version < 5:
        raise ConfigurationError(
            "A username is required for MONGODB-X509 authentication "
            "when connected to MongoDB versions older than 3.4.")
    sock_info.command('$external', query)


def _authenticate_mongo_cr(credentials, sock_info):
    """Authenticate using MONGODB-CR.
    """
    source = credentials.source
    username = credentials.username
    password = credentials.password
    # Get a nonce
    response = sock_info.command(source, {'getnonce': 1})
    nonce = response['nonce']
    key = _auth_key(nonce, username, password)

    # Actually authenticate
    query = SON([('authenticate', 1),
                 ('user', username),
                 ('nonce', nonce),
                 ('key', key)])
    sock_info.command(source, query)


def _authenticate_default(credentials, sock_info):
    if sock_info.max_wire_version >= 3:
        return _authenticate_scram_sha1(credentials, sock_info)
    else:
        return _authenticate_mongo_cr(credentials, sock_info)


_AUTH_MAP = {
    'CRAM-MD5': _authenticate_cram_md5,
    'GSSAPI': _authenticate_gssapi,
    'MONGODB-CR': _authenticate_mongo_cr,
    'MONGODB-X509': _authenticate_x509,
    'PLAIN': _authenticate_plain,
    'SCRAM-SHA-1': _authenticate_scram_sha1,
    'DEFAULT': _authenticate_default,
}


def authenticate(credentials, sock_info):
    """Authenticate sock_info."""
    mechanism = credentials.mechanism
    auth_func = _AUTH_MAP.get(mechanism)
    auth_func(credentials, sock_info)


def logout(source, sock_info):
    """Log out from a database."""
    sock_info.command(source, {'logout': 1})