s3:libsmb: use 16 zero bytes as channel binding checksum in the gssapi checksum ...

This fixes SMB session setups with kerberos against some closed
source SMB servers.

The new behavior matches heimdal and mit.

metze

Autobuild-User: Stefan Metzmacher <metze@samba.org>
Autobuild-Date: Thu Dec 23 09:38:43 CET 2010 on sn-devel-104

diff --git a/source3/libsmb/clikrb5.c b/source3/libsmb/clikrb5.c
index 5d51a5b19c85d0966ccfa0f7b55a540a74db86ac..b4962a02032ee35d9fc6e52af873721d60c07823 100644 (file)
--- a/source3/libsmb/clikrb5.c
+++ b/source3/libsmb/clikrb5.c
@@ -704,26 +704,16 @@ static krb5_error_code create_gss_checksum(krb5_data *in_data, /* [inout] */
        memset(gss_cksum, '\0', base_cksum_size + orig_length);
        SIVAL(gss_cksum, 0, GSSAPI_BNDLENGTH);
 
-       /* Precalculated MD5sum of NULL channel bindings (20 bytes) */
-       /* Channel bindings are: (all ints encoded as little endian)
-
-               [4 bytes] initiator_addrtype (255 for null bindings)
-               [4 bytes] initiator_address length
-                       [n bytes] .. initiator_address data - not present
-                                    in null bindings.
-               [4 bytes] acceptor_addrtype (255 for null bindings)
-               [4 bytes] acceptor_address length
-                       [n bytes] .. acceptor_address data - not present
-                                    in null bindings.
-               [4 bytes] application_data length
-                       [n bytes] .. application_ data - not present
-                                    in null bindings.
-               MD5 of this is ""\x14\x8f\x0c\xf7\xb1u\xdey*J\x9a%\xdfV\xc5\x18"
-       */
-
-       memcpy(&gss_cksum[4],
-               "\x14\x8f\x0c\xf7\xb1u\xdey*J\x9a%\xdfV\xc5\x18",
-               GSSAPI_BNDLENGTH);
+       /*
+        * GSS_C_NO_CHANNEL_BINDINGS means 16 zero bytes.
+        * This matches the behavior of heimdal and mit.
+        *
+        * And it is needed to work against some closed source
+        * SMB servers.
+        *
+        * See bug #7883
+        */
+       memset(&gss_cksum[4], 0x00, GSSAPI_BNDLENGTH);
 
        SIVAL(gss_cksum, 20, gss_flags);