s4:librpc/rpc: don't allow any unexpected upgrades of negotiate_flags

Only remove the unsupported flags from local_negotiate_flags for
the next try...

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15425

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

diff --git a/source4/librpc/rpc/dcerpc_schannel.c b/source4/librpc/rpc/dcerpc_schannel.c
index 556de33f46527fa6554165138f8ff2c7fdaa88fd..8cb95f01e11eddc613c8887ffb915e8f429b9dc1 100644 (file)
--- a/source4/librpc/rpc/dcerpc_schannel.c
+++ b/source4/librpc/rpc/dcerpc_schannel.c
@@ -245,6 +245,14 @@ static void continue_srv_auth2(struct tevent_req *subreq)
                uint32_t rf = s->remote_negotiate_flags;
                const char *rn = NULL;
 
+               if ((lf & rf) == lf) {
+                       /*
+                        * without a change in flags
+                        * there's no need to retry...
+                        */
+                       s->dcerpc_schannel_auto = false;
+               }
+
                if (!s->dcerpc_schannel_auto) {
                        composite_error(c, s->a.out.result);
                        return;
@@ -279,7 +287,7 @@ static void continue_srv_auth2(struct tevent_req *subreq)
                          "and retry! local[0x%08X] remote[0x%08X]\n",
                          ln, rn, lf, rf));
 
-               s->local_negotiate_flags = s->remote_negotiate_flags;
+               s->local_negotiate_flags &= s->remote_negotiate_flags;
 
                generate_random_buffer(s->credentials1.data,
                                       sizeof(s->credentials1.data));
@@ -294,14 +302,14 @@ static void continue_srv_auth2(struct tevent_req *subreq)
                return;
        }
 
-       s->creds->negotiate_flags = s->remote_negotiate_flags;
-
        /* verify credentials */
        if (!netlogon_creds_client_check(s->creds, s->a.out.return_credentials)) {
                composite_error(c, NT_STATUS_UNSUCCESSFUL);
                return;
        }
 
+       s->creds->negotiate_flags &= s->remote_negotiate_flags;
+
        composite_done(c);
 }