From 77631ca7c747796bf3d4dc347afb3f0cb5e4be78 Mon Sep 17 00:00:00 2001
From: Stefan Metzmacher <metze@samba.org>
Date: Tue, 22 Nov 2016 17:08:46 +0100
Subject: [PATCH] CVE-2016-2126: auth/kerberos: only allow known checksum types
 in check_pac_checksum()

aes based checksums can only be checked with the
corresponding aes based keytype.

Otherwise we may trigger an undefined code path
deep in the kerberos libraries, which can leed to
segmentation faults.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12446

Signed-off-by: Stefan Metzmacher <metze@samba.org>
---
 auth/kerberos/kerberos_pac.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/auth/kerberos/kerberos_pac.c b/auth/kerberos/kerberos_pac.c
index 32d9d7f..7b6efdc 100644
--- a/auth/kerberos/kerberos_pac.c
+++ b/auth/kerberos/kerberos_pac.c
@@ -39,6 +39,28 @@ krb5_error_code check_pac_checksum(DATA_BLOB pac_data,
 	krb5_boolean checksum_valid = false;
 	krb5_data input;
 
+	switch (sig->type) {
+	case CKSUMTYPE_HMAC_MD5:
+		/* ignores the key type */
+		break;
+	case CKSUMTYPE_HMAC_SHA1_96_AES_256:
+		if (KRB5_KEY_TYPE(keyblock) != ENCTYPE_AES256_CTS_HMAC_SHA1_96) {
+			return EINVAL;
+		}
+		/* ok */
+		break;
+	case CKSUMTYPE_HMAC_SHA1_96_AES_128:
+		if (KRB5_KEY_TYPE(keyblock) != ENCTYPE_AES128_CTS_HMAC_SHA1_96) {
+			return EINVAL;
+		}
+		/* ok */
+		break;
+	default:
+		DEBUG(2,("check_pac_checksum: Checksum Type %d is not supported\n",
+			(int)sig->type));
+		return EINVAL;
+	}
+
 #ifdef HAVE_CHECKSUM_IN_KRB5_CHECKSUM /* Heimdal */
 	cksum.cksumtype	= (krb5_cksumtype)sig->type;
 	cksum.checksum.length	= sig->signature.length;
-- 
1.9.1

From b6da00dee93b832e271040d80d4f6b6165b51f08 Mon Sep 17 00:00:00 2001
From: Stefan Metzmacher <metze@samba.org>
Date: Tue, 19 Jul 2016 16:31:01 +0200
Subject: [PATCH] krb5_wrap: provide CKSUMTYPE_HMAC_SHA1_96_AES_*
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

MIT only defined this as CKSUMTYPE_HMAC_SHA1_96_AES128,
while Heimdal has CKSUMTYPE_HMAC_SHA1_96_AES_128.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Günther Deschner <gd@samba.org>
(cherry picked from commit bb64c550ae19b08ad4e6d8d26f68c2474cb251e6)
---
 lib/krb5_wrap/krb5_samba.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lib/krb5_wrap/krb5_samba.h b/lib/krb5_wrap/krb5_samba.h
index cef9144..20ef6a3 100644
--- a/lib/krb5_wrap/krb5_samba.h
+++ b/lib/krb5_wrap/krb5_samba.h
@@ -74,6 +74,17 @@
 #define CKSUMTYPE_HMAC_MD5 CKSUMTYPE_HMAC_MD5_ARCFOUR
 #endif
 
+/*
+ * CKSUMTYPE_HMAC_SHA1_96_AES_* in Heimdal
+ * CKSUMTYPE_HMAC_SHA1_96_AES* in MIT
+ */
+#if defined(CKSUMTYPE_HMAC_SHA1_96_AES128) && !defined(CKSUMTYPE_HMAC_SHA1_96_AES_128)
+#define CKSUMTYPE_HMAC_SHA1_96_AES_128 CKSUMTYPE_HMAC_SHA1_96_AES128
+#endif
+#if defined(CKSUMTYPE_HMAC_SHA1_96_AES256) && !defined(CKSUMTYPE_HMAC_SHA1_96_AES_256)
+#define CKSUMTYPE_HMAC_SHA1_96_AES_256 CKSUMTYPE_HMAC_SHA1_96_AES256
+#endif
+
 typedef struct {
 #if defined(HAVE_MAGIC_IN_KRB5_ADDRESS) && defined(HAVE_ADDRTYPE_IN_KRB5_ADDRESS) /* MIT */
 	krb5_address **addrs;
-- 
1.9.1