# 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')