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.

(cherry picked from commit 0794746f8d8e6b8ce3748d442d2bc1faecf960ce)

ticket: 8013 (new)
version_fixed: 1.12.3
subject: gssapi.dll fails to detect TGTs in the MSLSA cache when UAC is enabled
status: resolved

diff --git a/src/lib/gssapi/krb5/acquire_cred.c b/src/lib/gssapi/krb5/acquire_cred.c
index dd19b43dda704a1cc9a7ff0a58cd40a415820c47..3cca20b6e5c29227dc086c5b7a9bfeb58bba0004 100644 (file)
--- a/src/lib/gssapi/krb5/acquire_cred.c
+++ b/src/lib/gssapi/krb5/acquire_cred.c
@@ -355,8 +355,9 @@ 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;