krb5: fix CVE-2018-20217

Fix CVE-2018-20217

Signed-off-by: Wenlin Kang <wenlin.kang@windriver.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

2 files changed, 81 insertions, 0 deletions

diff --git a/meta-oe/recipes-connectivity/krb5/krb5/0001-Ignore-password-attributes-for-S4U2Self-requests.patch b/meta-oe/recipes-connectivity/krb5/krb5/0001-Ignore-password-attributes-for-S4U2Self-requests.patch
new file mode 100644
index 000000000..8d1e14358
--- /dev/null
+++ b/meta-oe/recipes-connectivity/krb5/krb5/0001-Ignore-password-attributes-for-S4U2Self-requests.patch
@@ -0,0 +1,80 @@
+From 6fad7d45701234c8e81300d50dd5b8037d846d11 Mon Sep 17 00:00:00 2001
+From: Isaac Boukris <iboukris@gmail.com>
+Date: Wed, 27 Feb 2019 23:59:59 -0800
+Subject: [PATCH] Ignore password attributes for S4U2Self requests
+
+For consistency with Windows KDCs, allow protocol transition to work
+even if the password has expired or needs changing.
+
+Also, when looking up an enterprise principal with an AS request,
+treat ERR_KEY_EXP as confirmation that the client is present in the
+realm.
+
+[ghudson@mit.edu: added comment in kdc_process_s4u2self_req(); edited
+commit message]
+
+ticket: 8763 (new)
+tags: pullup
+target_version: 1.17
+
+Upsteam-Status: Backport [https://github.com/krb5/krb5/commit/5e6d1796106df8ba6bc1973ee0917c170d929086]
+CVE: CVE-2018-20217
+
+Signed-off-by: Wenlin Kang <wenlin.kang@windriver.com>
+---
+ src/kdc/kdc_util.c           | 5 +++++
+ src/lib/krb5/krb/s4u_creds.c | 2 +-
+ src/tests/gssapi/t_s4u.py    | 8 ++++++++
+ 3 files changed, 14 insertions(+), 1 deletion(-)
+
+diff --git a/src/kdc/kdc_util.c b/src/kdc/kdc_util.c
+index 754570c..034c979 100644
+--- a/src/kdc/kdc_util.c
++++ b/src/kdc/kdc_util.c
+@@ -1574,6 +1574,11 @@ kdc_process_s4u2self_req(kdc_realm_t *kdc_active_realm,
+ 
+         memset(&no_server, 0, sizeof(no_server));
+ 
++        /* Ignore password expiration and needchange attributes (as Windows
++         * does), since S4U2Self is not password authentication. */
++        princ->pw_expiration = 0;
++        clear(princ->attributes, KRB5_KDB_REQUIRES_PWCHANGE);
++
+         code = validate_as_request(kdc_active_realm, request, *princ,
+                                    no_server, kdc_time, status, &e_data);
+         if (code) {
+diff --git a/src/lib/krb5/krb/s4u_creds.c b/src/lib/krb5/krb/s4u_creds.c
+index 91c02aa..2037984 100644
+--- a/src/lib/krb5/krb/s4u_creds.c
++++ b/src/lib/krb5/krb/s4u_creds.c
+@@ -117,7 +117,7 @@ s4u_identify_user(krb5_context context,
+     code = k5_get_init_creds(context, &creds, client, NULL, NULL, 0, NULL,
+                              opts, krb5_get_as_key_noop, &userid, &use_master,
+                              NULL);
+-    if (code == 0 || code == KRB5_PREAUTH_FAILED) {
++    if (!code || code == KRB5_PREAUTH_FAILED || code == KRB5KDC_ERR_KEY_EXP) {
+         *canon_user = userid.user;
+         userid.user = NULL;
+         code = 0;
+diff --git a/src/tests/gssapi/t_s4u.py b/src/tests/gssapi/t_s4u.py
+index 3da6544..ba0469e 100755
+--- a/src/tests/gssapi/t_s4u.py
++++ b/src/tests/gssapi/t_s4u.py
+@@ -20,6 +20,14 @@ pservice2 = 'p:' + service2
+ # Get forwardable creds for service1 in the default cache.
+ realm.kinit(service1, None, ['-f', '-k'])
+ 
++# Try S4U2Self for user with a restricted password.
++realm.run([kadminl, 'modprinc', '+needchange', realm.user_princ])
++realm.run(['./t_s4u', 'e:user', '-'])
++realm.run([kadminl, 'modprinc', '-needchange',
++          '-pwexpire', '1/1/2000', realm.user_princ])
++realm.run(['./t_s4u', 'e:user', '-'])
++realm.run([kadminl, 'modprinc', '-pwexpire', 'never', realm.user_princ])
++
+ # Try krb5 -> S4U2Proxy with forwardable user creds.  This should fail
+ # at the S4U2Proxy step since the DB2 back end currently has no
+ # support for allowing it.
+-- 
+2.17.1
+
diff --git a/meta-oe/recipes-connectivity/krb5/krb5_1.16.2.bb b/meta-oe/recipes-connectivity/krb5/krb5_1.16.2.bb
index 76b5d3042..1d3ef8a34 100644
--- a/meta-oe/recipes-connectivity/krb5/krb5_1.16.2.bb
+++ b/meta-oe/recipes-connectivity/krb5/krb5_1.16.2.bb
@@ -30,6 +30,7 @@ SRC_URI = "http://web.mit.edu/kerberos/dist/${BPN}/${SHRT_VER}/${BP}.tar.gz \
            file://etc/default/krb5-admin-server \
            file://krb5-kdc.service \
            file://krb5-admin-server.service \
+           file://0001-Ignore-password-attributes-for-S4U2Self-requests.patch;striplevel=2 \
 "
 SRC_URI[md5sum] = "ffd52595e969fb700d37313606e4dc3d"
 SRC_URI[sha256sum] = "9f721e1fe593c219174740c71de514c7228a97d23eb7be7597b2ae14e487f027"