s4-dcerpc: fixed auth padding to be relative to the stub, not packet

The recent dcerpc padding changes made our padding relative to the
packet header, instead of the start of the stub. Surprisingly, this
broke w2k8r2 doing a dcpromo join to a s4 server. It seems that w2k8r2
is very fussy about the padding it gets in some circumstances.

1 files changed, 10 insertions, 5 deletions

diff --git a/source4/rpc_server/dcesrv_auth.c b/source4/rpc_server/dcesrv_auth.c
index e74b2ef167..59d8be3e24 100644
--- a/source4/rpc_server/dcesrv_auth.c
+++ b/source4/rpc_server/dcesrv_auth.c
@@ -378,7 +378,7 @@ bool dcesrv_auth_response(struct dcesrv_call_state *call,
 	NTSTATUS status;
 	enum ndr_err_code ndr_err;
 	struct ndr_push *ndr;
-	uint32_t payload_length, offset;
+	uint32_t payload_length;
 	DATA_BLOB creds2;
 
 	/* non-signed packets are simple */
@@ -422,13 +422,17 @@ bool dcesrv_auth_response(struct dcesrv_call_state *call,
 		return false;
 	}
 
-	/* pad to 16 byte multiple, match win2k3 */
-	offset = ndr->offset;
-	ndr_err = ndr_push_align(ndr, 16);
+	/* pad to 16 byte multiple in the payload portion of the
+	   packet. This matches what w2k3 does. Note that we can't use
+	   ndr_push_align() as that is relative to the start of the
+	   whole packet, whereas w2k8 wants it relative to the start
+	   of the stub */
+	dce_conn->auth_state.auth_info->auth_pad_length =
+		(16 - (pkt->u.response.stub_and_verifier.length & 15)) & 15;
+	ndr_err = ndr_push_zero(ndr, dce_conn->auth_state.auth_info->auth_pad_length);
 	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 		return false;
 	}
-	dce_conn->auth_state.auth_info->auth_pad_length = ndr->offset - offset;
 
 	payload_length = pkt->u.response.stub_and_verifier.length +
 		dce_conn->auth_state.auth_info->auth_pad_length;
@@ -497,6 +501,7 @@ bool dcesrv_auth_response(struct dcesrv_call_state *call,
 
 	if (!data_blob_append(call, blob, creds2.data, creds2.length)) {
 		status = NT_STATUS_NO_MEMORY;
+		return false;
 	}
 	data_blob_free(&creds2);