In krb5_get_cred_via_tkt, strip the ok-as-delegate flag from

credentials obtained using a foreign TGT, unless the TGT also has
ok-as-delegate set.

ticket: 6473
tags: pullup

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@22272 dc483132-0cff-0310-8789-dd5450dbe970

diff --git a/src/lib/krb5/krb/gc_via_tkt.c b/src/lib/krb5/krb/gc_via_tkt.c
index 059da828a935300fc1cc39a3acb8746d12b1c986..e8dbd97fecacb69edcdb89dd93a4e1c22e298163 100644 (file)
--- a/src/lib/krb5/krb/gc_via_tkt.c
+++ b/src/lib/krb5/krb/gc_via_tkt.c
@@ -144,6 +144,16 @@ check_reply_server(krb5_context context, krb5_flags kdcoptions,
     return 0;
 }
 
+/* Return true if a TGS credential is for the client's local realm. */
+static inline int
+tgt_is_local_realm(krb5_creds *tgt)
+{
+    return (tgt->server->length == 2
+           && data_eq_string(tgt->server->data[0], KRB5_TGS_NAME)
+           && data_eq(tgt->server->data[1], tgt->client->realm)
+           && data_eq(tgt->server->realm, tgt->client->realm));
+}
+
 krb5_error_code
 krb5_get_cred_via_tkt (krb5_context context, krb5_creds *tkt,
                       krb5_flags kdcoptions, krb5_address *const *address,
@@ -289,6 +299,14 @@ krb5_get_cred_via_tkt (krb5_context context, krb5_creds *tkt,
        goto error_3;
     }
    
+    /*
+     * Don't trust the ok-as-delegate flag from foreign KDCs unless the
+     * cross-realm TGT also had the ok-as-delegate flag set.
+     */
+    if (!tgt_is_local_realm(tkt)
+       && !(tkt->ticket_flags & TKT_FLG_OK_AS_DELEGATE))
+       dec_rep->enc_part2->flags &= ~TKT_FLG_OK_AS_DELEGATE;
+
     /* make sure the response hasn't been tampered with..... */
     retval = 0;