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mirror of https://github.com/samba-team/samba.git synced 2025-01-10 01:18:15 +03:00

CVE-2020-25722 pytest: test sAMAccountName/userPrincipalName over ldap

Because the sam account name + the dns host name is used as the
default user principal name, we need to check for collisions between
these. Fixes are coming in upcoming patches.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14564

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
This commit is contained in:
Douglas Bagnall 2021-09-13 14:15:09 +12:00 committed by Jule Anger
parent 82ea0d52b0
commit f1b6fe0097
3 changed files with 535 additions and 0 deletions

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# Unix SMB/CIFS implementation.
#
# Copyright 2021 (C) Catalyst IT Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import os
import sys
from samba.samdb import SamDB
from samba.auth import system_session
import ldb
from samba.tests.subunitrun import SubunitOptions, TestProgram
from samba.tests import TestCase, ldb_err
from samba.tests import DynamicTestCase
import samba.getopt as options
import optparse
from samba.colour import c_RED, c_GREEN, c_DARK_YELLOW
import re
import pprint
from samba.dsdb import (
UF_SERVER_TRUST_ACCOUNT,
UF_TRUSTED_FOR_DELEGATION,
)
# bad sAMAccountName characters from [MS-SAMR]
# "3.1.1.6 Attribute Constraints for Originating Updates"
BAD_SAM_CHARS = (''.join(chr(x) for x in range(0, 32)) +
'"/\\[]:|<>+=;?,*')
# 0x7f is *said* to be bad, but turns out to be fine.
ALLEGED_BAD_SAM_CHARS = chr(127)
LATIN1_BAD_CHARS = set([chr(x) for x in range(129, 160)] +
list("ªºÿ") +
[chr(x) for x in range(0xc0, 0xc6)] +
[chr(x) for x in range(0xc7, 0xd7)] +
[chr(x) for x in range(0xd8, 0xde)] +
[chr(x) for x in range(0xe0, 0xe6)] +
[chr(x) for x in range(0xe7, 0xf7)] +
[chr(x) for x in range(0xf8, 0xfe)])
LATIN_EXTENDED_A_NO_CLASH = {306, 307, 330, 331, 338, 339, 358, 359, 383}
#XXX does '\x00' just truncate the string though?
#XXX elsewhere we see "[\\\"|,/:<>+=;?*']" with "'"
## UPN limits
# max length 1024 UTF-8 bytes, following "rfc822"
# for o365 sync https://docs.microsoft.com/en-us/microsoft-365/enterprise/prepare-for-directory-synchronization?view=o365-worldwide
# max length is 113 [64 before @] "@" [48 after @]
# invalid chars: '\\%&*+/=?{}|<>();:,[]"'
# allowed chars: A Z, a - z, 0 9, ' . - _ ! # ^ ~
# "Letters with diacritical marks, such as umlauts, accents, and tildes, are invalid characters."
#
# "@" can't be first
# "The username cannot end with a period (.), an ampersand (&), a space, or an at sign (@)."
#
# per RFC 822, «"a b" @ example.org» is
ok = True
bad = False
report = 'report'
exists = ldb.ERR_ENTRY_ALREADY_EXISTS
if sys.stdout.isatty():
c_doc = c_DARK_YELLOW
else:
c_doc = lambda x: x
def get_samdb():
return SamDB(url=f"ldap://{SERVER}",
lp=LP,
session_info=system_session(),
credentials=CREDS)
def format(s):
if type(s) is str:
s = s.format(realm=REALM.upper(),
lrealm=REALM.lower(),
other_realm=(REALM + ".another.example.net"))
return s
class LdapUpnSamTestBase(TestCase):
"""Make sure we can't add userPrincipalNames or sAMAccountNames that
implicitly collide.
"""
_disabled = False
@classmethod
def setUpDynamicTestCases(cls):
if getattr(cls, '_disabled', False):
return
for doc, *rows in cls.cases:
name = re.sub(r'\W+', '_', doc)
cls.generate_dynamic_test("test_upn_sam", name, rows, doc)
def setup_objects(self, rows):
objects = set(r[0] for r in rows)
for name in objects:
if ':' in name:
objtype, name = name.split(':', 1)
else:
objtype = 'user'
getattr(self, f'add_{objtype}')(name)
self.addCleanup(self.remove_object, name)
def _test_upn_sam_with_args(self, rows, doc):
self.setup_objects(rows)
cdoc = c_doc(doc)
for i, row in enumerate(rows):
if len(row) == 4:
obj, data, expected, op = row
else:
obj, data, expected = row
op = ldb.FLAG_MOD_REPLACE
dn, dnsname = self.objects[obj]
sam, upn = None, None
if isinstance(data, dict):
sam = data.get('sam')
upn = data.get('upn')
elif isinstance(data, str):
if '@' in data:
upn = data
else:
sam = data
else: # bytes
if b'@' in data:
upn = data
else:
sam = data
m = {"dn": dn}
if upn is not None:
m["userPrincipalName"] = format(upn)
if sam is not None:
m["sAMAccountName"] = format(sam)
msg = ldb.Message.from_dict(self.samdb, m, op)
if expected is bad:
try:
self.samdb.modify(msg)
except ldb.LdbError as e:
print(f"row {i+1} of '{cdoc}' failed as expected with "
f"{ldb_err(e)}\n")
continue
self.fail(f"row {i+1} of '{cdoc}' should have failed:\n"
f"{pprint.pformat(m)} on {obj}")
elif expected is ok:
try:
self.samdb.modify(msg)
except ldb.LdbError as e:
raise AssertionError(
f"row {i+1} of '{cdoc}' failed with {ldb_err(e)}:\n"
f"{pprint.pformat(m)} on {obj}") from None
elif expected is report:
try:
self.samdb.modify(msg)
print(f"row {i+1} of '{cdoc}' SUCCEEDED:\n"
f"{pprint.pformat(m)} on {obj}")
except ldb.LdbError as e:
print(f"row {i+1} of '{cdoc}' FAILED "
f"with {ldb_err(e)}:\n"
f"{pprint.pformat(m)} on {obj}")
else:
try:
self.samdb.modify(msg)
except ldb.LdbError as e:
if hasattr(expected, '__contains__'):
if e.args[0] in expected:
continue
if e.args[0] == expected:
continue
self.fail(f"row {i+1} of '{cdoc}' "
f"should have failed with {ldb_err(expected)} "
f"but instead failed with {ldb_err(e)}:\n"
f"{pprint.pformat(m)} on {obj}")
self.fail(f"row {i+1} of '{cdoc}' "
f"should have failed with {ldb_err(expected)}:\n"
f"{pprint.pformat(m)} on {obj}")
def add_dc(self, name):
dn = f"CN={name},OU=Domain Controllers,{self.base_dn}"
dnsname = f"{name}.{REALM}".lower()
self.samdb.add({
"dn": dn,
"objectclass": "computer",
"userAccountControl": str(UF_SERVER_TRUST_ACCOUNT |
UF_TRUSTED_FOR_DELEGATION),
"dnsHostName": dnsname,
"carLicense": self.id()
})
self.objects[name] = (dn, dnsname)
def add_user(self, name):
dn = f"CN={name},{self.ou}"
self.samdb.add({
"dn": dn,
"name": name,
"objectclass": "user",
"carLicense": self.id()
})
self.objects[name] = (dn, None)
def remove_object(self, name):
dn, dnsname = self.objects.pop(name)
self.samdb.delete(dn)
def setUp(self):
super().setUp()
self.samdb = get_samdb()
self.base_dn = self.samdb.get_default_basedn()
self.short_id = self.id().rsplit('.', 1)[1][:63]
self.objects = {}
self.ou = f"OU={ self.short_id },{ self.base_dn }"
self.addCleanup(self.samdb.delete, self.ou, ["tree_delete:1"])
self.samdb.add({"dn": self.ou, "objectclass": "organizationalUnit"})
@DynamicTestCase
class LdapUpnSamTest(LdapUpnSamTestBase):
cases = [
# The structure is
# ( «documentation/message that becomes test name»,
# («short object id», «upn or sam or mapping», «expected»),
# («short object id», «upn or sam or mapping», «expected»),
# ...,
# )
#
# where the first item is a one line string explaining the
# test, and subsequent items describe database modifications,
# to be applied in series.
#
# First is a short ID, which maps to an object DN. Second is
# either a string or a dictionary.
#
# * If a string, if it contains '@', it is a UPN, otherwise a
# samaccountname.
#
# * If a dictionary, it is a mapping of some of ['sam', 'upn']
# to strings (in this way, you can add two attributes in one
# mesage, or attempt a samaccountname with '@').
#
# expected can be «ok», «bad» (mapped to True and False,
# respectively), or a specific LDB error code, if that exact
# exception is wanted.
("add good UPN",
('A', 'a@{realm}', ok),
),
("add the same upn to different objects",
('A', 'a@{realm}', ok),
('B', 'a@{realm}', ldb.ERR_CONSTRAINT_VIOLATION),
('B', 'a@{lrealm}', ldb.ERR_CONSTRAINT_VIOLATION), # lowercase realm
),
("replace UPN with itself",
('A', 'a@{realm}', ok),
('A', 'a@{realm}', ok),
('A', 'a@{lrealm}', ok),
),
("replace SAM with itself",
('A', 'a', ok),
('A', 'a', ok),
),
("replace UPN realm",
('A', 'a@{realm}', ok),
('A', 'a@{other_realm}', ok),
),
("matching SAM and UPN",
('A', 'a', ok),
('A', 'a@{realm}', ok),
),
("matching SAM and UPN, other realm",
('A', 'a', ok),
('A', 'a@{other_realm}', ok),
),
("matching SAM and UPN, single message",
('A', {'sam': 'a', 'upn': 'a@{realm}'}, ok),
('A', {'sam': 'a', 'upn': 'a@{other_realm}'}, ok),
),
("different objects, different realms",
('A', 'a@{realm}', ok),
('B', 'a@{other_realm}', ok),
),
("different objects, same UPN, different case",
('A', 'a@{realm}', ok),
('B', 'A@{realm}', ldb.ERR_CONSTRAINT_VIOLATION),
),
("different objects, SAM after UPN",
('A', 'a@{realm}', ok),
('B', 'a', ldb.ERR_CONSTRAINT_VIOLATION),
),
("different objects, SAM before UPN",
('A', 'a', ok),
('B', 'a@{realm}', exists),
),
("different objects, SAM account clash",
('A', 'a', ok),
('B', 'a', exists),
),
("different objects, SAM account clash, different case",
('A', 'a', ok),
('B', 'A', exists),
),
("two way clash",
('A', {'sam': 'x', 'upn': 'y@{realm}'}, ok),
# The sam account raises EXISTS while the UPN raises
# CONSTRAINT_VIOLATION. We don't really care in which order
# they are checked, so either error is ok.
('B', {'sam': 'y', 'upn': 'x@{realm}'},
(exists, ldb.ERR_CONSTRAINT_VIOLATION)),
),
("two way clash, other realm",
('A', {'sam': 'x', 'upn': 'y@{other_realm}'}, ok),
('B', {'sam': 'y', 'upn': 'x@{other_realm}'}, ok),
),
# UPN versions of bad sam account names
("UPN clash on other realm",
('A', 'a@x.x', ok),
('B', 'a@x.x', ldb.ERR_CONSTRAINT_VIOLATION),
),
("UPN same but for trailing spaces",
('A', 'a@{realm}', ok),
('B', 'a @{realm}', ok),
),
# UPN has no at
("UPN has no at",
('A', {'upn': 'noat'}, ok),
('B', {'upn': 'noat'}, ldb.ERR_CONSTRAINT_VIOLATION),
('C', {'upn': 'NOAT'}, ldb.ERR_CONSTRAINT_VIOLATION),
),
# UPN has non-ascii at, followed by real at.
("UPN with non-ascii at vs real at",
('A', {'upn': 'smallat﹫{realm}'}, ok),
('B', {'upn': 'smallat@{realm}'}, ok),
('C', {'upn': 'tagat\U000e0040{realm}'}, ok),
('D', {'upn': 'tagat@{realm}'}, ok),
),
("UPN with unicode at vs real at, real at first",
('B', {'upn': 'smallat@{realm}'}, ok),
('A', {'upn': 'smallat﹫{realm}'}, ok),
('D', {'upn': 'tagat@{realm}'}, ok),
('C', {'upn': 'tagat\U000e0040{realm}'}, ok),
),
("UPN username too long",
# SPN soft limit 20; hard limit 256, overall UPN 1024
('A', 'a' * 25 + '@b.c', ok),
('A', 'a' * 65 + '@b.c', ok), # Azure AD limit is 64
('A', 'a' * 257 + '@b.c', ok), # 256 is sam account name limit
),
("sam account name 20 long",
# SPN soft limit 20
('A', 'a' * 20, ok),
),
("UPN has two at signs",
('A', 'a@{realm}', ok),
('A', 'a@{realm}@{realm}', ok),
('A', 'a@a.b', ok),
('A', 'a@a@a.b', ok),
),
("SAM has at signs clashing upn second, non-realm",
('A', {'sam': 'a@a.b'}, ok),
('B', 'a@a.b@a.b', ok), # UPN won't clash with SAM, because realm
),
("SAM has at signs clashing upn second",
('A', {'sam': 'a@{realm}'}, ok),
('B', 'a@{realm}@{realm}', bad), # UPN would clashes with SAM
),
("SAM has at signs clashing upn first",
('B', 'a@{realm}@{realm}', ok),
('A', {'sam': 'a@{realm}'}, bad),
),
("spaces around at",
('A', 'a name @ {realm}', ok),
('B', 'a name @ {realm}', ldb.ERR_CONSTRAINT_VIOLATION),
('B', 'a name @{realm}', ok), # because realm looks different
('C', 'a name@{realm}', ok),
('D', 'a name', ldb.ERR_CONSTRAINT_VIOLATION),
('D', 'a name ', (exists, ldb.ERR_CONSTRAINT_VIOLATION)), # matches B
),
("SAM starts with at",
('A', {'sam': '@{realm}'}, ok),
('B', {'sam': '@a'}, ok),
('C', {'sam': '@{realm}'}, exists),
('C', {'sam': '@a'}, exists),
('C', {'upn': '@{realm}@{realm}'}, bad),
('C', {'upn': '@a@{realm}'}, bad),
),
("UPN starts with at",
('A', {'upn': '@{realm}'}, ok),
('B', {'upn': '@a@{realm}'}, ok),
('C', {'upn': '@{realm}'}, bad),
('C', {'sam': '@a'}, bad),
),
("SAM ends with at",
('A', {'sam': '{realm}@'}, ok),
('B', {'sam': 'a@'}, ok),
('C', {'sam': '{realm}@'}, exists),
('C', {'sam': 'a@'}, exists),
('C', {'upn': 'a@@{realm}'}, bad),
('C', {'upn': '{realm}@@{realm}'}, bad),
),
("UPN ends with at",
('A', {'upn': '{realm}@'}, ok),
('B', {'upn': '@a@{realm}@'}, ok),
('C', {'upn': '{realm}@'}, bad),
('C', {'sam': '@a@{realm}'}, ok), # not like B, because other realm
),
]
@DynamicTestCase
class LdapUpnSamSambaOnlyTest(LdapUpnSamTestBase):
# We don't run these ones outside of selftest, where we are
# probably testing against Windows and these are known failures.
_disabled = 'SAMBA_SELFTEST' not in os.environ
cases = [
("sam account name too long",
# SPN soft limit 20
('A', 'a' * 19, ok),
('A', 'a' * 20, ok),
('A', 'a' * 65, ok),
('A', 'a' * 255, ok),
('A', 'a' * 256, ok),
('A', 'a' * 257, ldb.ERR_INVALID_ATTRIBUTE_SYNTAX),
),
("UPN username too long",
('A', 'a' * 254 + '@' + 'b.c' * 257,
ldb.ERR_INVALID_ATTRIBUTE_SYNTAX), # 1024 is alleged UPN limit
),
("UPN same but for internal spaces",
('A', 'a b@x.x', ok),
('B', 'a b@x.x', ldb.ERR_CONSTRAINT_VIOLATION),
),
("SAM contains delete",
# forbidden according to documentation, but works in practice on Windows
('A', 'a\x7f', ldb.ERR_CONSTRAINT_VIOLATION),
('A', 'a\x7f'.encode(), ldb.ERR_CONSTRAINT_VIOLATION),
('A', 'a\x7fb', ldb.ERR_CONSTRAINT_VIOLATION),
('A', 'a\x7fb'.encode(), ldb.ERR_CONSTRAINT_VIOLATION),
('A', '\x7fb', ldb.ERR_CONSTRAINT_VIOLATION),
('A', '\x7fb'.encode(), ldb.ERR_CONSTRAINT_VIOLATION),
),
# The wide at symbol ('' U+FF20) does not count as '@' for Samba
# so it will look like a string with no @s.
("UPN with unicode wide at vs real at",
('A', {'upn': 'wideat{realm}'}, ok),
('B', {'upn': 'wideat@{realm}'}, ok),
),
("UPN with real at vs wide at",
('B', {'upn': 'wideat@{realm}'}, ok),
('A', {'upn': 'wideat{realm}'}, ok)
),
]
def main():
global LP, CREDS, SERVER, REALM
parser = optparse.OptionParser(
"python3 ldap_upn_sam_account_name.py <server> [options]")
sambaopts = options.SambaOptions(parser)
parser.add_option_group(sambaopts)
# use command line creds if available
credopts = options.CredentialsOptions(parser)
parser.add_option_group(credopts)
subunitopts = SubunitOptions(parser)
parser.add_option_group(subunitopts)
opts, args = parser.parse_args()
if len(args) != 1:
parser.print_usage()
sys.exit(1)
LP = sambaopts.get_loadparm()
CREDS = credopts.get_credentials(LP)
SERVER = args[0]
REALM = CREDS.get_realm()
TestProgram(module=__name__, opts=subunitopts)
main()

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samba.tests.ldap_upn_sam_account.+LdapUpnSamSambaOnlyTest.test_upn_sam_SAM_contains_delete
samba.tests.ldap_upn_sam_account.+LdapUpnSamSambaOnlyTest.test_upn_sam_UPN_same_but_for_internal_spaces
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_SAM_ends_with_at
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_SAM_has_at_signs_clashing_upn_first
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_SAM_has_at_signs_clashing_upn_second
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_SAM_starts_with_at
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_UPN_clash_on_other_realm
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_UPN_ends_with_at
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_UPN_has_no_at
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_UPN_starts_with_at
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_add_the_same_upn_to_different_objects
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_different_objects_SAM_after_UPN
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_different_objects_SAM_before_UPN
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_different_objects_same_UPN_different_case
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_spaces_around_at
samba.tests.ldap_upn_sam_account.+LdapUpnSamTest.test_upn_sam_two_way_clash

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@ -1073,6 +1073,15 @@ planoldpythontestsuite("ad_dc",
extra_args=['-U"$USERNAME%$PASSWORD"'], extra_args=['-U"$USERNAME%$PASSWORD"'],
environ={'TEST_ENV': 'ad_dc'}) environ={'TEST_ENV': 'ad_dc'})
plantestsuite_loadlist("samba.tests.ldap_upn_sam_account", "ad_dc",
[python,
f"{srcdir()}/python/samba/tests/ldap_upn_sam_account.py",
'$SERVER',
'-U"$USERNAME%$PASSWORD"',
'--workgroup=$DOMAIN',
'$LOADLIST', '$LISTOPT'])
plantestsuite_loadlist("samba4.tokengroups.krb5.python(ad_dc_default)", "ad_dc_default:local", [python, os.path.join(DSDB_PYTEST_DIR, "token_group.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN', '-k', 'yes', '$LOADLIST', '$LISTOPT']) plantestsuite_loadlist("samba4.tokengroups.krb5.python(ad_dc_default)", "ad_dc_default:local", [python, os.path.join(DSDB_PYTEST_DIR, "token_group.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN', '-k', 'yes', '$LOADLIST', '$LISTOPT'])
plantestsuite_loadlist("samba4.tokengroups.ntlm.python(ad_dc_default)", "ad_dc_default:local", [python, os.path.join(DSDB_PYTEST_DIR, "token_group.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN', '-k', 'no', '$LOADLIST', '$LISTOPT']) plantestsuite_loadlist("samba4.tokengroups.ntlm.python(ad_dc_default)", "ad_dc_default:local", [python, os.path.join(DSDB_PYTEST_DIR, "token_group.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN', '-k', 'no', '$LOADLIST', '$LISTOPT'])
plantestsuite("samba4.sam.python(fl2008r2dc)", "fl2008r2dc", [python, os.path.join(DSDB_PYTEST_DIR, "sam.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN']) plantestsuite("samba4.sam.python(fl2008r2dc)", "fl2008r2dc", [python, os.path.join(DSDB_PYTEST_DIR, "sam.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN'])