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From 8b598814d1e51466ebbe3e0a392af92370d0c93b Mon Sep 17 00:00:00 2001
From: Alexander Bokovoy <abokovoy@redhat.com>
Date: Wed, 7 Feb 2024 13:09:54 +0200
Subject: [PATCH] rpcserver: validate Kerberos principal name before running
kinit
Do minimal validation of the Kerberos principal name when passing it to
kinit command line tool. Also pass it as the final argument to prevent
option injection.
Accepted Kerberos principals are:
- user names, using the following regexp
(username with optional @realm, no spaces or slashes in the name):
"(?!^[0-9]+$)^[a-zA-Z0-9_.][a-zA-Z0-9_.-]*[a-zA-Z0-9_.$-]?@?[a-zA-Z0-9.-]*$"
- service names (with slash in the name but no spaces). Validation of
the hostname is done. There is no validation of the service name.
The regular expression above also covers cases where a principal name
starts with '-'. This prevents option injection as well.
This fixes CVE-2024-1481
Fixes: https://pagure.io/freeipa/issue/9541
Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Signed-off-by: Rob Crittenden <rcritten@redhat.com>
Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>
Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>
---
ipalib/install/kinit.py | 47 ++++++++++++++++++-
ipaserver/rpcserver.py | 9 ++--
ipatests/setup.py | 1 +
ipatests/test_ipalib_install/__init__.py | 0
ipatests/test_ipalib_install/test_kinit.py | 29 ++++++++++++
5 files changed, 80 insertions(+), 6 deletions(-)
create mode 100644 ipatests/test_ipalib_install/__init__.py
create mode 100644 ipatests/test_ipalib_install/test_kinit.py
diff --git a/ipalib/install/kinit.py b/ipalib/install/kinit.py
index cc839ec38d1dbcb1cf3b0334592d04baf0dba23b..4ad4eaa1c30f2fb0ab02be411917e304eb527d32 100644
--- a/ipalib/install/kinit.py
+++ b/ipalib/install/kinit.py
@@ -6,12 +6,16 @@ from __future__ import absolute_import
import logging
import os
+import re
import time
import gssapi
from ipaplatform.paths import paths
from ipapython.ipautil import run
+from ipalib.constants import PATTERN_GROUPUSER_NAME
+from ipalib.util import validate_hostname
+from ipalib import api
logger = logging.getLogger(__name__)
@@ -21,6 +25,40 @@ KRB5_KDC_UNREACH = 2529639068
# A service is not available that s required to process the request
KRB5KDC_ERR_SVC_UNAVAILABLE = 2529638941
+PATTERN_REALM = '@?([a-zA-Z0-9.-]*)$'
+PATTERN_PRINCIPAL = '(' + PATTERN_GROUPUSER_NAME[:-1] + ')' + PATTERN_REALM
+PATTERN_SERVICE = '([a-zA-Z0-9.-]+)/([a-zA-Z0-9.-]+)' + PATTERN_REALM
+
+user_pattern = re.compile(PATTERN_PRINCIPAL)
+service_pattern = re.compile(PATTERN_SERVICE)
+
+
+def validate_principal(principal):
+ if not isinstance(principal, str):
+ raise RuntimeError('Invalid principal: not a string')
+ if ('/' in principal) and (' ' in principal):
+ raise RuntimeError('Invalid principal: bad spacing')
+ else:
+ realm = None
+ match = user_pattern.match(principal)
+ if match is None:
+ match = service_pattern.match(principal)
+ if match is None:
+ raise RuntimeError('Invalid principal: cannot parse')
+ else:
+ # service = match[1]
+ hostname = match[2]
+ realm = match[3]
+ try:
+ validate_hostname(hostname)
+ except ValueError as e:
+ raise RuntimeError(str(e))
+ else: # user match, validate realm
+ # username = match[1]
+ realm = match[2]
+ if realm and 'realm' in api.env and realm != api.env.realm:
+ raise RuntimeError('Invalid principal: realm mismatch')
+
def kinit_keytab(principal, keytab, ccache_name, config=None, attempts=1):
"""
@@ -29,6 +67,7 @@ def kinit_keytab(principal, keytab, ccache_name, config=None, attempts=1):
The optional parameter 'attempts' specifies how many times the credential
initialization should be attempted in case of non-responsive KDC.
"""
+ validate_principal(principal)
errors_to_retry = {KRB5KDC_ERR_SVC_UNAVAILABLE,
KRB5_KDC_UNREACH}
logger.debug("Initializing principal %s using keytab %s",
@@ -65,6 +104,7 @@ def kinit_keytab(principal, keytab, ccache_name, config=None, attempts=1):
return None
+
def kinit_password(principal, password, ccache_name, config=None,
armor_ccache_name=None, canonicalize=False,
enterprise=False, lifetime=None):
@@ -73,8 +113,9 @@ def kinit_password(principal, password, ccache_name, config=None,
web-based authentication, use armor_ccache_path to specify http service
ccache.
"""
+ validate_principal(principal)
logger.debug("Initializing principal %s using password", principal)
- args = [paths.KINIT, principal, '-c', ccache_name]
+ args = [paths.KINIT, '-c', ccache_name]
if armor_ccache_name is not None:
logger.debug("Using armor ccache %s for FAST webauth",
armor_ccache_name)
@@ -91,6 +132,7 @@ def kinit_password(principal, password, ccache_name, config=None,
logger.debug("Using enterprise principal")
args.append('-E')
+ args.extend(['--', principal])
env = {'LC_ALL': 'C'}
if config is not None:
env['KRB5_CONFIG'] = config
@@ -154,6 +196,7 @@ def kinit_pkinit(
:raises: CalledProcessError if PKINIT fails
"""
+ validate_principal(principal)
logger.debug(
"Initializing principal %s using PKINIT %s", principal, user_identity
)
@@ -168,7 +211,7 @@ def kinit_pkinit(
assert pkinit_anchor.startswith(("FILE:", "DIR:", "ENV:"))
args.extend(["-X", f"X509_anchors={pkinit_anchor}"])
args.extend(["-X", f"X509_user_identity={user_identity}"])
- args.append(principal)
+ args.extend(['--', principal])
# this workaround enables us to capture stderr and put it
# into the raised exception in case of unsuccessful authentication
diff --git a/ipaserver/rpcserver.py b/ipaserver/rpcserver.py
index 198fc9e7dbae281f797dcccf96d21d475ff31e8c..4f65b7e057c3d184ffadd4f28872ec3cceb73077 100644
--- a/ipaserver/rpcserver.py
+++ b/ipaserver/rpcserver.py
@@ -1135,10 +1135,6 @@ class login_password(Backend, KerberosSession):
canonicalize=True,
lifetime=self.api.env.kinit_lifetime)
- if armor_path:
- logger.debug('Cleanup the armor ccache')
- ipautil.run([paths.KDESTROY, '-A', '-c', armor_path],
- env={'KRB5CCNAME': armor_path}, raiseonerr=False)
except RuntimeError as e:
if ('kinit: Cannot read password while '
'getting initial credentials') in str(e):
@@ -1156,6 +1152,11 @@ class login_password(Backend, KerberosSession):
raise KrbPrincipalWrongFAST(principal=principal)
raise InvalidSessionPassword(principal=principal,
message=unicode(e))
+ finally:
+ if armor_path:
+ logger.debug('Cleanup the armor ccache')
+ ipautil.run([paths.KDESTROY, '-A', '-c', armor_path],
+ env={'KRB5CCNAME': armor_path}, raiseonerr=False)
class change_password(Backend, HTTP_Status):
diff --git a/ipatests/setup.py b/ipatests/setup.py
index 6217a1ba5d82ba7fa79cc4c073270abe307cd2ed..0aec4a70dbd75d416e4288e1204130daf46bda94 100644
--- a/ipatests/setup.py
+++ b/ipatests/setup.py
@@ -41,6 +41,7 @@ if __name__ == '__main__':
"ipatests.test_integration",
"ipatests.test_ipaclient",
"ipatests.test_ipalib",
+ "ipatests.test_ipalib_install",
"ipatests.test_ipaplatform",
"ipatests.test_ipapython",
"ipatests.test_ipaserver",
diff --git a/ipatests/test_ipalib_install/__init__.py b/ipatests/test_ipalib_install/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/ipatests/test_ipalib_install/test_kinit.py b/ipatests/test_ipalib_install/test_kinit.py
new file mode 100644
index 0000000000000000000000000000000000000000..f89ea17d7874c28bad2524ebf456d2caeafddd1f
--- /dev/null
+++ b/ipatests/test_ipalib_install/test_kinit.py
@@ -0,0 +1,29 @@
+#
+# Copyright (C) 2024 FreeIPA Contributors see COPYING for license
+#
+"""Tests for ipalib.install.kinit module
+"""
+
+import pytest
+
+from ipalib.install.kinit import validate_principal
+
+
+# None means no exception is expected
+@pytest.mark.parametrize('principal, exception', [
+ ('testuser', None),
+ ('testuser@EXAMPLE.TEST', None),
+ ('test/ipa.example.test', None),
+ ('test/ipa.example.test@EXAMPLE.TEST', None),
+ ('test/ipa@EXAMPLE.TEST', RuntimeError),
+ ('test/-ipa.example.test@EXAMPLE.TEST', RuntimeError),
+ ('test/ipa.1example.test@EXAMPLE.TEST', RuntimeError),
+ ('test /ipa.example,test', RuntimeError),
+ ('testuser@OTHER.TEST', RuntimeError),
+ ('test/ipa.example.test@OTHER.TEST', RuntimeError),
+])
+def test_validate_principal(principal, exception):
+ try:
+ validate_principal(principal)
+ except Exception as e:
+ assert e.__class__ == exception
--
2.44.0
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