mechanisms.py 16.5 KB
Newer Older
Lance Stout's avatar
Lance Stout committed
1
2
3
4
5
6
7
8
9
10
11
# -*- coding: utf-8 -*-
"""
    sleekxmpp.util.sasl.mechanisms
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    A collection of supported SASL mechanisms.

    This module was originally based on Dave Cridland's Suelta library.

    Part of SleekXMPP: The Sleek XMPP Library

12
13
    :copryight: (c) 2004-2013 David Alan Cridland
    :copyright: (c) 2013 Nathanael C. Fritz, Lance J.T. Stout
14

Lance Stout's avatar
Lance Stout committed
15
16
17
18
19
20
21
22
23
24
25
    :license: MIT, see LICENSE for more details
"""

import sys
import hmac
import random

from base64 import b64encode, b64decode

from sleekxmpp.util import bytes, hash, XOR, quote, num_to_bytes
from sleekxmpp.util.sasl.client import sasl_mech, Mech, \
26
27
                                       SASLCancelled, SASLFailed, \
                                       SASLMutualAuthFailed
Lance Stout's avatar
Lance Stout committed
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


@sasl_mech(0)
class ANONYMOUS(Mech):

    name = 'ANONYMOUS'

    def process(self, challenge=b''):
        return b'Anonymous, Suelta'


@sasl_mech(1)
class LOGIN(Mech):

    name = 'LOGIN'
    required_credentials = set(['username', 'password'])

    def setup(self, name):
        self.step = 0

    def process(self, challenge=b''):
        if not challenge:
            return b''

        if self.step == 0:
            self.step = 1
            return self.credentials['username']
        else:
            return self.credentials['password']


@sasl_mech(2)
class PLAIN(Mech):

    name = 'PLAIN'
    required_credentials = set(['username', 'password'])
    optional_credentials = set(['authzid'])
    security = set(['encrypted', 'encrypted_plain', 'unencrypted_plain'])

    def setup(self, name):
        if not self.security_settings['encrypted']:
            if not self.security_settings['unencrypted_plain']:
                raise SASLCancelled('PLAIN without encryption')
        else:
            if not self.security_settings['encrypted_plain']:
                raise SASLCancelled('PLAIN with encryption')

    def process(self, challenge=b''):
        authzid = self.credentials['authzid']
        authcid = self.credentials['username']
        password = self.credentials['password']
        return authzid + b'\x00' + authcid + b'\x00' + password


@sasl_mech(100)
class EXTERNAL(Mech):

    name = 'EXTERNAL'
    optional_credentials = set(['authzid'])

    def process(self, challenge=b''):
        return self.credentials['authzid']


92
@sasl_mech(31)
Lance Stout's avatar
Lance Stout committed
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
class X_FACEBOOK_PLATFORM(Mech):

    name = 'X-FACEBOOK-PLATFORM'
    required_credentials = set(['api_key', 'access_token'])

    def process(self, challenge=b''):
        if challenge:
            values = {}
            for kv in challenge.split(b'&'):
                key, value = kv.split(b'=')
                values[key] = value

            resp_data = {
                b'method': values[b'method'],
                b'v': b'1.0',
                b'call_id': b'1.0',
                b'nonce': values[b'nonce'],
                b'access_token': self.credentials['access_token'],
                b'api_key': self.credentials['api_key']
            }

114
            resp = '&'.join(['%s=%s' % (k.decode("utf-8"), v.decode("utf-8")) for k, v in resp_data.items()])
Lance Stout's avatar
Lance Stout committed
115
116
117
118
119
120
121
122
123
124
125
126
127
128
            return bytes(resp)
        return b''


@sasl_mech(10)
class X_MESSENGER_OAUTH2(Mech):

    name = 'X-MESSENGER-OAUTH2'
    required_credentials = set(['access_token'])

    def process(self, challenge=b''):
        return self.credentials['access_token']


129
130
131
132
133
134
135
136
137
138
139
@sasl_mech(10)
class X_OAUTH2(Mech):

    name = 'X-OAUTH2'
    required_credentials = set(['username', 'access_token'])

    def process(self, challenge=b''):
        return b'\x00' + self.credentials['username'] + \
               b'\x00' + self.credentials['access_token']


Lance Stout's avatar
Lance Stout committed
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
@sasl_mech(3)
class X_GOOGLE_TOKEN(Mech):

    name = 'X-GOOGLE-TOKEN'
    required_credentials = set(['email', 'access_token'])

    def process(self, challenge=b''):
        email = self.credentials['email']
        token = self.credentials['access_token']
        return b'\x00' + email + b'\x00' + token


@sasl_mech(20)
class CRAM(Mech):

    name = 'CRAM'
    use_hashes = True
    required_credentials = set(['username', 'password'])
    security = set(['encrypted', 'unencrypted_cram'])

    def setup(self, name):
        self.hash_name = name[5:]
        self.hash = hash(self.hash_name)
        if self.hash is None:
            raise SASLCancelled('Unknown hash: %s' % self.hash_name)
        if not self.security_settings['encrypted']:
            if not self.security_settings['unencrypted_cram']:
                raise SASLCancelled('Unecrypted CRAM-%s' % self.hash_name)

    def process(self, challenge=b''):
        if not challenge:
            return None

        username = self.credentials['username']
        password = self.credentials['password']

        mac = hmac.HMAC(key=password, digestmod=self.hash)
        mac.update(challenge)

        return username + b' ' + bytes(mac.hexdigest())


@sasl_mech(60)
class SCRAM(Mech):

    name = 'SCRAM'
    use_hashes = True
    channel_binding = True
    required_credentials = set(['username', 'password'])
    optional_credentials = set(['authzid', 'channel_binding'])
    security = set(['encrypted', 'unencrypted_scram'])

    def setup(self, name):
        self.use_channel_binding = False
        if name[-5:] == '-PLUS':
            name = name[:-5]
            self.use_channel_binding = True

        self.hash_name = name[6:]
        self.hash = hash(self.hash_name)

        if self.hash is None:
            raise SASLCancelled('Unknown hash: %s' % self.hash_name)
        if not self.security_settings['encrypted']:
            if not self.security_settings['unencrypted_scram']:
                raise SASLCancelled('Unencrypted SCRAM')

        self.step = 0
        self._mutual_auth = False

    def HMAC(self, key, msg):
        return hmac.HMAC(key=key, msg=msg, digestmod=self.hash).digest()

    def Hi(self, text, salt, iterations):
        text = bytes(text)
        ui1 = self.HMAC(text, salt + b'\0\0\0\01')
        ui = ui1
        for i in range(iterations - 1):
            ui1 = self.HMAC(text, ui1)
            ui = XOR(ui, ui1)
        return ui

    def H(self, text):
        return self.hash(text).digest()

    def saslname(self, value):
        escaped = b''
        for char in bytes(value):
            if char == b',':
                escaped += b'=2C'
            elif char == b'=':
                escaped += b'=3D'
            else:
                if isinstance(char, int):
                    char = chr(char)
                escaped += bytes(char)
        return escaped

    def parse(self, challenge):
        items = {}
        for key, value in [item.split(b'=', 1) for item in challenge.split(b',')]:
            items[key] = value
        return items

    def process(self, challenge=b''):
        steps = [self.process_1, self.process_2, self.process_3]
        return steps[self.step](challenge)

    def process_1(self, challenge):
        self.step = 1
        data = {}

        self.cnonce = bytes(('%s' % random.random())[2:])

        gs2_cbind_flag = b'n'
        if self.credentials['channel_binding']:
            if self.use_channel_binding:
                gs2_cbind_flag = b'p=tls-unique'
            else:
                gs2_cbind_flag = b'y'

        authzid = b''
        if self.credentials['authzid']:
            authzid = b'a=' + self.saslname(self.credentials['authzid'])

        self.gs2_header = gs2_cbind_flag + b',' + authzid + b','

        nonce = b'r=' + self.cnonce
        username = b'n=' + self.saslname(self.credentials['username'])

        self.client_first_message_bare = username + b',' + nonce
        self.client_first_message = self.gs2_header + \
                                    self.client_first_message_bare

        return self.client_first_message

    def process_2(self, challenge):
        self.step = 2

        data = self.parse(challenge)
        if b'm' in data:
            raise SASLCancelled('Received reserved attribute.')

        salt = b64decode(data[b's'])
        iteration_count = int(data[b'i'])
        nonce = data[b'r']

        if nonce[:len(self.cnonce)] != self.cnonce:
            raise SASLCancelled('Invalid nonce')

Lance Stout's avatar
Lance Stout committed
290
291
292
        cbind_data = b''
        if self.use_channel_binding:
            cbind_data = self.credentials['channel_binding']
Lance Stout's avatar
Lance Stout committed
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
        cbind_input = self.gs2_header + cbind_data
        channel_binding = b'c=' + b64encode(cbind_input).replace(b'\n', b'')

        client_final_message_without_proof = channel_binding + b',' + \
                                             b'r=' + nonce

        salted_password = self.Hi(self.credentials['password'],
                                       salt,
                                       iteration_count)
        client_key = self.HMAC(salted_password, b'Client Key')
        stored_key = self.H(client_key)
        auth_message = self.client_first_message_bare + b',' + \
                       challenge + b',' + \
                       client_final_message_without_proof
        client_signature = self.HMAC(stored_key, auth_message)
        client_proof = XOR(client_key, client_signature)
        server_key = self.HMAC(salted_password, b'Server Key')

        self.server_signature = self.HMAC(server_key, auth_message)

        client_final_message = client_final_message_without_proof + \
                               b',p=' + b64encode(client_proof)

        return client_final_message

    def process_3(self, challenge):
        data = self.parse(challenge)
        verifier = data.get(b'v', None)
        error = data.get(b'e', 'Unknown error')

        if not verifier:
            raise SASLFailed(error)

        if b64decode(verifier) != self.server_signature:
            raise SASLMutualAuthFailed()

        self._mutual_auth = True

        return b''


@sasl_mech(30)
class DIGEST(Mech):

    name = 'DIGEST'
    use_hashes = True
    required_credentials = set(['username', 'password', 'realm', 'service', 'host'])
    optional_credentials = set(['authzid', 'service-name'])
    security = set(['encrypted', 'unencrypted_digest'])

    def setup(self, name):
        self.hash_name = name[7:]
        self.hash = hash(self.hash_name)
        if self.hash is None:
            raise SASLCancelled('Unknown hash: %s' % self.hash_name)
        if not self.security_settings['encrypted']:
            if not self.security_settings['unencrypted_digest']:
                raise SASLCancelled('Unencrypted DIGEST')

        self.qops = [b'auth']
        self.qop = b'auth'
        self.maxbuf = b'65536'
        self.nonce = b''
        self.cnonce = b''
        self.nonce_count = 1

    def parse(self, challenge=b''):
        data = {}
        var_name = b''
        var_value = b''

        # States: var, new_var, end, quote, escaped_quote
        state = 'var'


        for char in challenge:
            if sys.version_info >= (3, 0):
                char = bytes([char])

            if state == 'var':
                if char.isspace():
                    continue
                if char == b'=':
                    state = 'value'
                else:
                    var_name += char
            elif state == 'value':
                if char == b'"':
                    state = 'quote'
                elif char == b',':
                    if var_name:
                        data[var_name.decode('utf-8')] = var_value
                    var_name = b''
                    var_value = b''
                    state = 'var'
                else:
                    var_value += char
            elif state == 'escaped':
                var_value += char
            elif state == 'quote':
                if char == b'\\':
                    state = 'escaped'
                elif char == b'"':
                    state = 'end'
                else:
                    var_value += char
            else:
                if char == b',':
                    if var_name:
                        data[var_name.decode('utf-8')] = var_value
                    var_name = b''
                    var_value = b''
                    state = 'var'
                else:
                    var_value += char

        if var_name:
            data[var_name.decode('utf-8')] = var_value
        var_name = b''
        var_value = b''
        state = 'var'
        return data

    def MAC(self, key, seq, msg):
        mac = hmac.HMAC(key=key, digestmod=self.hash)
        seqnum = num_to_bytes(seq)
        mac.update(seqnum)
        mac.update(msg)
        return mac.digest()[:10] + b'\x00\x01' + seqnum

    def A1(self):
        username = self.credentials['username']
        password = self.credentials['password']
        authzid = self.credentials['authzid']
        realm = self.credentials['realm']

        a1 = self.hash()
        a1.update(username + b':' + realm + b':' + password)
        a1 = a1.digest()
        a1 += b':' + self.nonce + b':' + self.cnonce
        if authzid:
            a1 += b':' + authzid

        return bytes(a1)

    def A2(self, prefix=b''):
        a2 = prefix + b':' + self.digest_uri()
        if self.qop in (b'auth-int', b'auth-conf'):
            a2 += b':00000000000000000000000000000000'
        return bytes(a2)

    def response(self, prefix=b''):
        nc = bytes('%08x' % self.nonce_count)

        a1 = bytes(self.hash(self.A1()).hexdigest().lower())
        a2 = bytes(self.hash(self.A2(prefix)).hexdigest().lower())
        s = self.nonce + b':' + nc + b':' + self.cnonce + \
                         b':' + self.qop + b':' + a2

        return bytes(self.hash(a1 + b':' + s).hexdigest().lower())

    def digest_uri(self):
        serv_type = self.credentials['service']
        serv_name = self.credentials['service-name']
        host = self.credentials['host']

        uri = serv_type + b'/' + host
        if serv_name and host != serv_name:
            uri += b'/' + serv_name
        return uri

    def respond(self):
        data = {
            'username': quote(self.credentials['username']),
            'authzid': quote(self.credentials['authzid']),
            'realm': quote(self.credentials['realm']),
            'nonce': quote(self.nonce),
            'cnonce': quote(self.cnonce),
            'nc': bytes('%08x' % self.nonce_count),
            'qop': self.qop,
            'digest-uri': quote(self.digest_uri()),
            'response': self.response(b'AUTHENTICATE'),
475
476
            'maxbuf': self.maxbuf,
            'charset': 'utf-8'
Lance Stout's avatar
Lance Stout committed
477
478
479
480
481
482
483
484
485
486
487
488
        }
        resp = b''
        for key, value in data.items():
            if value and value != b'""':
                resp += b',' + bytes(key) + b'=' + bytes(value)
        return resp[1:]

    def process(self, challenge=b''):
        if not challenge:
            if self.cnonce and self.nonce and self.nonce_count and self.qop:
                self.nonce_count += 1
                return self.respond()
489
            return None
Lance Stout's avatar
Lance Stout committed
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548

        data = self.parse(challenge)
        if 'rspauth' in data:
            if data['rspauth'] != self.response():
                raise SASLMutualAuthFailed()
        else:
            self.nonce_count = 1
            self.cnonce = bytes('%s' % random.random())[2:]
            self.qops = data.get('qop', [b'auth'])
            self.qop = b'auth'
            if 'nonce' in data:
                self.nonce = data['nonce']
            if 'realm' in data and not self.credentials['realm']:
                self.credentials['realm'] = data['realm']

            return self.respond()


try:
    import kerberos
except ImportError:
    pass
else:
    @sasl_mech(75)
    class GSSAPI(Mech):

        name = 'GSSAPI'
        required_credentials = set(['username', 'service-name'])
        optional_credentials = set(['authzid'])

        def setup(self, name):
            authzid = self.credentials['authzid']
            if not authzid:
                authzid = 'xmpp@%s' % self.credentials['service-name']

            _, self.gss = kerberos.authGSSClientInit(authzid)
            self.step = 0

        def process(self, challenge=b''):
            b64_challenge = b64encode(challenge)
            try:
                if self.step == 0:
                    result = kerberos.authGSSClientStep(self.gss, b64_challenge)
                    if result != kerberos.AUTH_GSS_CONTINUE:
                        self.step = 1
                elif self.step == 1:
                    username = self.credentials['username']

                    kerberos.authGSSClientUnwrap(self.gss, b64_challenge)
                    resp = kerberos.authGSSClientResponse(self.gss)
                    kerberos.authGSSClientWrap(self.gss, resp, username)

                resp = kerberos.authGSSClientResponse(self.gss)
            except kerberos.GSSError as e:
                raise SASLCancelled('Kerberos error: %s' % e.message)
            if not resp:
                return b''
            else:
                return b64decode(resp)