krb5/SOURCES/Remove-incorrect-KDC-assert...

60 lines
2.2 KiB
Diff

From 2a96564f6fd53f2e1e8424d865c02349bfe5b818 Mon Sep 17 00:00:00 2001
From: Isaac Boukris <iboukris@gmail.com>
Date: Sat, 15 Dec 2018 11:56:36 +0200
Subject: [PATCH] Remove incorrect KDC assertion
The assertion in return_enc_padata() is reachable because
kdc_make_s4u2self_rep() may have previously added encrypted padata.
It is no longer necessary because the code uses add_pa_data_element()
instead of allocating a new list.
CVE-2018-20217:
In MIT krb5 1.8 or later, an authenticated user who can obtain a TGT
using an older encryption type (DES, DES3, or RC4) can cause an
assertion failure in the KDC by sending an S4U2Self request.
[ghudson@mit.edu: rewrote commit message with CVE description]
(cherry picked from commit 94e5eda5bb94d1d44733a49c3d9b6d1e42c74def)
ticket: 8767
version_fixed: 1.16.3
(cherry picked from commit 56870f9456da78d77a667dfc03a6d90f948dc3a5)
---
src/kdc/kdc_preauth.c | 1 -
src/tests/gssapi/t_s4u.py | 7 +++++++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/src/kdc/kdc_preauth.c b/src/kdc/kdc_preauth.c
index 811c16368..6f0cf68d9 100644
--- a/src/kdc/kdc_preauth.c
+++ b/src/kdc/kdc_preauth.c
@@ -1666,7 +1666,6 @@ return_enc_padata(krb5_context context, krb5_data *req_pkt,
krb5_error_code code = 0;
/* This should be initialized and only used for Win2K compat and other
* specific standardized uses such as FAST negotiation. */
- assert(reply_encpart->enc_padata == NULL);
if (is_referral) {
code = return_referral_enc_padata(context, reply_encpart, server);
if (code)
diff --git a/src/tests/gssapi/t_s4u.py b/src/tests/gssapi/t_s4u.py
index fc9d9e8a4..f65000453 100755
--- a/src/tests/gssapi/t_s4u.py
+++ b/src/tests/gssapi/t_s4u.py
@@ -139,6 +139,13 @@ if 'auth1: user@' not in out or 'auth2: user@' not in out:
realm.stop()
+for realm in multipass_realms(create_host=False, get_creds=False):
+ service1 = 'service/1@%s' % realm.realm
+ realm.addprinc(service1)
+ realm.extract_keytab(service1, realm.keytab)
+ realm.kinit(service1, None, ['-k'])
+ realm.run(['./t_s4u', 'p:user', '-'])
+
# Exercise cross-realm S4U2Self. The query in the foreign realm will
# fail, but we can check that the right server principal was used.
r1, r2 = cross_realms(2, create_user=False)