I've been working on the DCE_STYLE GSSAPI code (mostly by metze) that Samba4 needs for the 'Kerberos domain join' problem, and I have solved the final piece of the puzzle. It appears that the encrypted timestamp in the AP_REP (mutual authentication) packet, used in the '3rd leg' of the extended GSSAPI negotiation is not consistent with the other two timestamps in the exchange. It appears simply to be the real time, on the client now, and so varies particularly in the usec field. So, what I'm wondering is how to still be secure, while removing the need for an exact timestamp match here. To be clear about the packets I'm talking about, I have attached the #if 0 patch I used. Andrew Bartlett -- Andrew Bartlett http://samba.org/~abartlet/ Authentication Developer, Samba Team http://samba.org Student Network Administrator, Hawker College http://hawkerc.net
Index: lib/krb5/rd_rep.c
===================================================================
--- lib/krb5/rd_rep.c (revision 282)
+++ lib/krb5/rd_rep.c (working copy)
@@ -89,13 +89,16 @@
&len);
if (ret)
return ret;
-
+
+#if 0
if ((*repl)->ctime != auth_context->authenticator->ctime ||
(*repl)->cusec != auth_context->authenticator->cusec) {
+
ret = KRB5KRB_AP_ERR_MUT_FAIL;
- krb5_clear_error_string (context);
+ krb5_set_error_string (context, "Mutual authentication failed: Timestamps mismatch");
goto out;
}
+#endif
if ((*repl)->seq_number)
krb5_auth_con_setremoteseqnumber(context, auth_context,
*((*repl)->seq_number));
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