# Copyright 2017 Canonical Ltd.
# Licensed under the LGPLv3, see LICENCE file for details.
import os
import unittest
import macaroonbakery.bakery as bakery
import macaroonbakery.checkers as checkers
from macaroonbakery.tests import common
from pymacaroons import MACAROON_V1, Macaroon
class TestDischarge(unittest.TestCase):
def test_single_service_first_party(self):
''' Creates a single service with a macaroon with one first party
caveat.
It creates a request with this macaroon and checks that the service
can verify this macaroon as valid.
'''
oc = common.new_bakery('bakerytest')
primary = oc.oven.macaroon(bakery.LATEST_VERSION,
common.ages, None,
[bakery.LOGIN_OP])
self.assertEqual(primary.macaroon.location, 'bakerytest')
primary.add_caveat(checkers.Caveat(condition='str something',
namespace='testns'),
oc.oven.key, oc.oven.locator)
oc.checker.auth([[primary.macaroon]]).allow(
common.str_context('something'), [bakery.LOGIN_OP])
def test_macaroon_paper_fig6(self):
''' Implements an example flow as described in the macaroons paper:
http://theory.stanford.edu/~ataly/Papers/macaroons.pdf
There are three services, ts, fs, bs:
ts is a store service which has deligated authority to a forum
service fs.
The forum service wants to require its users to be logged into to an
authentication service bs.
The client obtains a macaroon from fs (minted by ts, with a third party
caveat addressed to bs).
The client obtains a discharge macaroon from bs to satisfy this caveat.
The target service verifies the original macaroon it delegated to fs
No direct contact between bs and ts is required
'''
locator = bakery.ThirdPartyStore()
bs = common.new_bakery('bs-loc', locator)
ts = common.new_bakery('ts-loc', locator)
fs = common.new_bakery('fs-loc', locator)
# ts creates a macaroon.
ts_macaroon = ts.oven.macaroon(bakery.LATEST_VERSION,
common.ages,
None, [bakery.LOGIN_OP])
# ts somehow sends the macaroon to fs which adds a third party caveat
# to be discharged by bs.
ts_macaroon.add_caveat(checkers.Caveat(location='bs-loc',
condition='user==bob'),
fs.oven.key, fs.oven.locator)
# client asks for a discharge macaroon for each third party caveat
def get_discharge(cav, payload):
self.assertEqual(cav.location, 'bs-loc')
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
bs.oven.key,
common.ThirdPartyStrcmpChecker('user==bob'),
bs.oven.locator,
)
d = bakery.discharge_all(ts_macaroon, get_discharge)
ts.checker.auth([d]).allow(common.test_context,
[bakery.LOGIN_OP])
def test_discharge_with_version1_macaroon(self):
locator = bakery.ThirdPartyStore()
bs = common.new_bakery('bs-loc', locator)
ts = common.new_bakery('ts-loc', locator)
# ts creates a old-version macaroon.
ts_macaroon = ts.oven.macaroon(bakery.VERSION_1, common.ages,
None, [bakery.LOGIN_OP])
ts_macaroon.add_caveat(checkers.Caveat(condition='something',
location='bs-loc'),
ts.oven.key, ts.oven.locator)
# client asks for a discharge macaroon for each third party caveat
def get_discharge(cav, payload):
# Make sure that the caveat id really is old-style.
try:
cav.caveat_id_bytes.decode('utf-8')
except UnicodeDecodeError:
self.fail('caveat id is not utf-8')
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
bs.oven.key,
common.ThirdPartyStrcmpChecker('something'),
bs.oven.locator,
)
d = bakery.discharge_all(ts_macaroon, get_discharge)
ts.checker.auth([d]).allow(common.test_context,
[bakery.LOGIN_OP])
for m in d:
self.assertEqual(m.version, MACAROON_V1)
def test_version1_macaroon_id(self):
# In the version 1 bakery, macaroon ids were hex-encoded with a
# hyphenated UUID suffix.
root_key_store = bakery.MemoryKeyStore()
b = bakery.Bakery(
root_key_store=root_key_store,
identity_client=common.OneIdentity(),
)
key, id = root_key_store.root_key()
root_key_store.get(id)
m = Macaroon(key=key, version=MACAROON_V1, location='',
identifier=id + b'-deadl00f')
b.checker.auth([[m]]).allow(common.test_context,
[bakery.LOGIN_OP])
def test_macaroon_paper_fig6_fails_without_discharges(self):
''' Runs a similar test as test_macaroon_paper_fig6 without the client
discharging the third party caveats.
'''
locator = bakery.ThirdPartyStore()
ts = common.new_bakery('ts-loc', locator)
fs = common.new_bakery('fs-loc', locator)
common.new_bakery('as-loc', locator)
# ts creates a macaroon.
ts_macaroon = ts.oven.macaroon(bakery.LATEST_VERSION,
common.ages, None,
[bakery.LOGIN_OP])
# ts somehow sends the macaroon to fs which adds a third party
# caveat to be discharged by as.
ts_macaroon.add_caveat(checkers.Caveat(location='as-loc',
condition='user==bob'),
fs.oven.key, fs.oven.locator)
# client makes request to ts
try:
ts.checker.auth([[ts_macaroon.macaroon]]).allow(
common.test_context,
bakery.LOGIN_OP
)
self.fail('macaroon unmet should be raised')
except bakery.PermissionDenied:
pass
def test_macaroon_paper_fig6_fails_with_binding_on_tampered_sig(self):
''' Runs a similar test as test_macaroon_paper_fig6 with the discharge
macaroon binding being done on a tampered signature.
'''
locator = bakery.ThirdPartyStore()
bs = common.new_bakery('bs-loc', locator)
ts = common.new_bakery('ts-loc', locator)
# ts creates a macaroon.
ts_macaroon = ts.oven.macaroon(bakery.LATEST_VERSION,
common.ages, None,
[bakery.LOGIN_OP])
# ts somehow sends the macaroon to fs which adds a third party caveat
# to be discharged by as.
ts_macaroon.add_caveat(checkers.Caveat(condition='user==bob',
location='bs-loc'),
ts.oven.key, ts.oven.locator)
# client asks for a discharge macaroon for each third party caveat
def get_discharge(cav, payload):
self.assertEqual(cav.location, 'bs-loc')
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
bs.oven.key,
common.ThirdPartyStrcmpChecker('user==bob'),
bs.oven.locator,
)
d = bakery.discharge_all(ts_macaroon, get_discharge)
# client has all the discharge macaroons. For each discharge macaroon
# bind it to our ts_macaroon and add it to our request.
tampered_macaroon = Macaroon()
for i, dm in enumerate(d[1:]):
d[i + 1] = tampered_macaroon.prepare_for_request(dm)
# client makes request to ts.
with self.assertRaises(bakery.PermissionDenied) as exc:
ts.checker.auth([d]).allow(common.test_context,
bakery.LOGIN_OP)
self.assertEqual('verification failed: Signatures do not match',
exc.exception.args[0])
def test_need_declared(self):
locator = bakery.ThirdPartyStore()
first_party = common.new_bakery('first', locator)
third_party = common.new_bakery('third', locator)
# firstParty mints a macaroon with a third-party caveat addressed
# to thirdParty with a need-declared caveat.
m = first_party.oven.macaroon(
bakery.LATEST_VERSION, common.ages, [
checkers.need_declared_caveat(
checkers.Caveat(location='third', condition='something'),
['foo', 'bar']
)
], [bakery.LOGIN_OP])
# The client asks for a discharge macaroon for each third party caveat.
def get_discharge(cav, payload):
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
third_party.oven.key,
common.ThirdPartyStrcmpChecker('something'),
third_party.oven.locator,
)
d = bakery.discharge_all(m, get_discharge)
# The required declared attributes should have been added
# to the discharge macaroons.
declared = checkers.infer_declared(d, first_party.checker.namespace())
self.assertEqual(declared, {
'foo': '',
'bar': '',
})
# Make sure the macaroons actually check out correctly
# when provided with the declared checker.
ctx = checkers.context_with_declared(common.test_context, declared)
first_party.checker.auth([d]).allow(ctx, [bakery.LOGIN_OP])
# Try again when the third party does add a required declaration.
# The client asks for a discharge macaroon for each third party caveat.
def get_discharge(cav, payload):
checker = common.ThirdPartyCheckerWithCaveats([
checkers.declared_caveat('foo', 'a'),
checkers.declared_caveat('arble', 'b')
])
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
third_party.oven.key,
checker,
third_party.oven.locator,
)
d = bakery.discharge_all(m, get_discharge)
# One attribute should have been added, the other was already there.
declared = checkers.infer_declared(d, first_party.checker.namespace())
self.assertEqual(declared, {
'foo': 'a',
'bar': '',
'arble': 'b',
})
ctx = checkers.context_with_declared(common.test_context, declared)
first_party.checker.auth([d]).allow(ctx, [bakery.LOGIN_OP])
# Try again, but this time pretend a client is sneakily trying
# to add another 'declared' attribute to alter the declarations.
def get_discharge(cav, payload):
checker = common.ThirdPartyCheckerWithCaveats([
checkers.declared_caveat('foo', 'a'),
checkers.declared_caveat('arble', 'b'),
])
# Sneaky client adds a first party caveat.
m = bakery.discharge(
common.test_context, cav.caveat_id_bytes,
payload,
third_party.oven.key, checker,
third_party.oven.locator,
)
m.add_caveat(checkers.declared_caveat('foo', 'c'), None, None)
return m
d = bakery.discharge_all(m, get_discharge)
declared = checkers.infer_declared(d, first_party.checker.namespace())
self.assertEqual(declared, {
'bar': '',
'arble': 'b',
})
with self.assertRaises(bakery.PermissionDenied) as exc:
first_party.checker.auth([d]).allow(common.test_context,
bakery.LOGIN_OP)
self.assertEqual('cannot authorize login macaroon: caveat '
'"declared foo a" not satisfied: got foo=null, '
'expected "a"', exc.exception.args[0])
def test_discharge_two_need_declared(self):
locator = bakery.ThirdPartyStore()
first_party = common.new_bakery('first', locator)
third_party = common.new_bakery('third', locator)
# first_party mints a macaroon with two third party caveats
# with overlapping attributes.
m = first_party.oven.macaroon(
bakery.LATEST_VERSION,
common.ages, [
checkers.need_declared_caveat(
checkers.Caveat(location='third', condition='x'),
['foo', 'bar']),
checkers.need_declared_caveat(
checkers.Caveat(location='third', condition='y'),
['bar', 'baz']),
], [bakery.LOGIN_OP])
# The client asks for a discharge macaroon for each third party caveat.
# Since no declarations are added by the discharger,
def get_discharge(cav, payload):
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
third_party.oven.key,
common.ThirdPartyCaveatCheckerEmpty(),
third_party.oven.locator,
)
d = bakery.discharge_all(m, get_discharge)
declared = checkers.infer_declared(d, first_party.checker.namespace())
self.assertEqual(declared, {
'foo': '',
'bar': '',
'baz': '',
})
ctx = checkers.context_with_declared(common.test_context, declared)
first_party.checker.auth([d]).allow(ctx, [bakery.LOGIN_OP])
# If they return conflicting values, the discharge fails.
# The client asks for a discharge macaroon for each third party caveat.
# Since no declarations are added by the discharger,
class ThirdPartyCaveatCheckerF(bakery.ThirdPartyCaveatChecker):
def check_third_party_caveat(self, ctx, cav_info):
if cav_info.condition == 'x':
return [checkers.declared_caveat('foo', 'fooval1')]
if cav_info.condition == 'y':
return [
checkers.declared_caveat('foo', 'fooval2'),
checkers.declared_caveat('baz', 'bazval')
]
raise bakery.ThirdPartyCaveatCheckFailed('not matched')
def get_discharge(cav, payload):
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
third_party.oven.key,
ThirdPartyCaveatCheckerF(),
third_party.oven.locator,
)
d = bakery.discharge_all(m, get_discharge)
declared = checkers.infer_declared(d, first_party.checker.namespace())
self.assertEqual(declared, {
'bar': '',
'baz': 'bazval',
})
with self.assertRaises(bakery.PermissionDenied) as exc:
first_party.checker.auth([d]).allow(common.test_context,
bakery.LOGIN_OP)
self.assertEqual('cannot authorize login macaroon: caveat "declared '
'foo fooval1" not satisfied: got foo=null, expected '
'"fooval1"', exc.exception.args[0])
def test_discharge_macaroon_cannot_be_used_as_normal_macaroon(self):
locator = bakery.ThirdPartyStore()
first_party = common.new_bakery('first', locator)
third_party = common.new_bakery('third', locator)
# First party mints a macaroon with a 3rd party caveat.
m = first_party.oven.macaroon(bakery.LATEST_VERSION,
common.ages, [
checkers.Caveat(location='third',
condition='true')],
[bakery.LOGIN_OP])
# Acquire the discharge macaroon, but don't bind it to the original.
class M:
unbound = None
def get_discharge(cav, payload):
m = bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
third_party.oven.key,
common.ThirdPartyStrcmpChecker('true'),
third_party.oven.locator,
)
M.unbound = m.macaroon.copy()
return m
bakery.discharge_all(m, get_discharge)
self.assertIsNotNone(M.unbound)
# Make sure it cannot be used as a normal macaroon in the third party.
with self.assertRaises(bakery.PermissionDenied) as exc:
third_party.checker.auth([[M.unbound]]).allow(
common.test_context, [bakery.LOGIN_OP])
self.assertEqual('no operations found in macaroon',
exc.exception.args[0])
def test_third_party_discharge_macaroon_ids_are_small(self):
locator = bakery.ThirdPartyStore()
bakeries = {
'ts-loc': common.new_bakery('ts-loc', locator),
'as1-loc': common.new_bakery('as1-loc', locator),
'as2-loc': common.new_bakery('as2-loc', locator),
}
ts = bakeries['ts-loc']
ts_macaroon = ts.oven.macaroon(bakery.LATEST_VERSION,
common.ages,
None, [bakery.LOGIN_OP])
ts_macaroon.add_caveat(checkers.Caveat(condition='something',
location='as1-loc'),
ts.oven.key, ts.oven.locator)
class ThirdPartyCaveatCheckerF(bakery.ThirdPartyCaveatChecker):
def __init__(self, loc):
self._loc = loc
def check_third_party_caveat(self, ctx, info):
if self._loc == 'as1-loc':
return [checkers.Caveat(condition='something',
location='as2-loc')]
if self._loc == 'as2-loc':
return []
raise bakery.ThirdPartyCaveatCheckFailed(
'unknown location {}'.format(self._loc))
def get_discharge(cav, payload):
oven = bakeries[cav.location].oven
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
oven.key,
ThirdPartyCaveatCheckerF(cav.location),
oven.locator,
)
d = bakery.discharge_all(ts_macaroon, get_discharge)
ts.checker.auth([d]).allow(common.test_context,
[bakery.LOGIN_OP])
for i, m in enumerate(d):
for j, cav in enumerate(m.caveats):
if (cav.verification_key_id is not None and
len(cav.caveat_id) > 3):
self.fail('caveat id on caveat {} of macaroon {} '
'is too big ({})'.format(j, i, cav.id))
def test_third_party_discharge_macaroon_wrong_root_key_and_third_party_caveat(self):
root_keys = bakery.MemoryKeyStore()
ts = bakery.Bakery(
key=bakery.generate_key(),
checker=common.test_checker(),
root_key_store=root_keys,
identity_client=common.OneIdentity(),
)
locator = bakery.ThirdPartyStore()
bs = common.new_bakery('bs-loc', locator)
# ts creates a macaroon with a third party caveat addressed to bs.
ts_macaroon = ts.oven.macaroon(bakery.LATEST_VERSION,
common.ages,
None, [bakery.LOGIN_OP])
ts_macaroon.add_caveat(
checkers.Caveat(location='bs-loc', condition='true'),
ts.oven.key, locator,
)
def get_discharge(cav, payload):
return bakery.discharge(
common.test_context,
cav.caveat_id_bytes,
payload,
bs.oven.key,
common.ThirdPartyStrcmpChecker('true'),
bs.oven.locator,
)
d = bakery.discharge_all(ts_macaroon, get_discharge)
# The authorization should succeed at first.
ts.checker.auth([d]).allow(common.test_context, [bakery.LOGIN_OP])
# Corrupt the root key and try again.
# We should get a DischargeRequiredError because the verification has failed.
root_keys._key = os.urandom(24)
with self.assertRaises(bakery.PermissionDenied) as err:
ts.checker.auth([d]).allow(common.test_context, [bakery.LOGIN_OP])
self.assertEqual(str(err.exception), 'verification failed: Decryption failed. Ciphertext failed verification')