Let libgssapi see TGTs in the MSLSA cache

When the current user is a local administrator of a windows machine
where User Account Control (UAC) is enabled, the Windows LSA will
return a block of zeros as the session key for any TGT entry in the
MSLSA: cache.  The lcc_retrieve() implementation checks for such
"null" session keys and prevents them from escaping to callers (as
attempts to use them would encounger strange errors).  However,
when the TGT is the only entry in the cache, this filtering prevents
scan_ccache() from detecting that the cache contains non-expired
credentials (and that there is a TGT present).

Since scan_ccache() is only looking at metadata in the cache entries,
and does not need to actually use any tickets or session keys, set
the KRB5_TC_NOTICKET flag on the ccache before scanning it.  This
will allow the MSLSA implementation to return a cred for the TGT
entry and cause the GSSAPI credential selection algorithm to function
properly.

ticket: 8000 (new)
tags: pullup
target_version: 1.12.3
subject: gssapi.dll fails to detect TGTs in the MSLSA cache when UAC is enabled

diff --git a/src/lib/gssapi/krb5/acquire_cred.c b/src/lib/gssapi/krb5/acquire_cred.c
index eec6f2a4b1637d4d9b8a69f7c0d85c6ecf8d3640..8bdf7c417785b37fad4e6aaf86687560ae2ea9e7 100644 (file)
--- a/src/lib/gssapi/krb5/acquire_cred.c
+++ b/src/lib/gssapi/krb5/acquire_cred.c
@@ -376,8 +376,9 @@ scan_ccache(krb5_context context, krb5_gss_cred_id_rec *cred)
     krb5_timestamp endtime;
     krb5_boolean is_tgt;
 
-    /* Turn off OPENCLOSE mode while extensive frobbing is going on. */
-    code = krb5_cc_set_flags(context, ccache, 0);
+    /* Turn off OPENCLOSE mode while extensive frobbing is going on.
+     * Turn on NOTICKET, as we don't need session keys here. */
+    code = krb5_cc_set_flags(context, ccache, KRB5_TC_NOTICKET);
     if (code)
         return code;