sctp_disposition_t sctp_sf_do_5_1B_init(struct net *net,
					const struct sctp_endpoint *ep,
					const struct sctp_association *asoc,
					const sctp_subtype_t type,
					void *arg,
					sctp_cmd_seq_t *commands)
{
	struct sctp_chunk *chunk = arg;
	struct sctp_chunk *repl;
	struct sctp_association *new_asoc;
	struct sctp_chunk *err_chunk;
	struct sctp_packet *packet;
	sctp_unrecognized_param_t *unk_param;
	int len;

	/* 6.10 Bundling
	 * An endpoint MUST NOT bundle INIT, INIT ACK or
	 * SHUTDOWN COMPLETE with any other chunks.
	 *
	 * IG Section 2.11.2
	 * Furthermore, we require that the receiver of an INIT chunk MUST
	 * enforce these rules by silently discarding an arriving packet
	 * with an INIT chunk that is bundled with other chunks.
	 */
	if (!chunk->singleton)
		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);

	/* If the packet is an OOTB packet which is temporarily on the
	 * control endpoint, respond with an ABORT.
	 */
	if (ep == sctp_sk(net->sctp.ctl_sock)->ep) {
		SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
	}

	/* 3.1 A packet containing an INIT chunk MUST have a zero Verification
	 * Tag.
	 */
	if (chunk->sctp_hdr->vtag != 0)
		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);

	/* Make sure that the INIT chunk has a valid length.
	 * Normally, this would cause an ABORT with a Protocol Violation
	 * error, but since we don't have an association, we'll
	 * just discard the packet.
	 */
	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_init_chunk_t)))
		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);

	/* If the INIT is coming toward a closing socket, we'll send back
	 * and ABORT.  Essentially, this catches the race of INIT being
	 * backloged to the socket at the same time as the user isses close().
	 * Since the socket and all its associations are going away, we
	 * can treat this OOTB
	 */
	if (sctp_sstate(ep->base.sk, CLOSING))
		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);

	/* Verify the INIT chunk before processing it. */
	err_chunk = NULL;
	if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,
			      (sctp_init_chunk_t *)chunk->chunk_hdr, chunk,
			      &err_chunk)) {
		/* This chunk contains fatal error. It is to be discarded.
		 * Send an ABORT, with causes if there is any.
		 */
		if (err_chunk) {
			packet = sctp_abort_pkt_new(net, ep, asoc, arg,
					(__u8 *)(err_chunk->chunk_hdr) +
					sizeof(sctp_chunkhdr_t),
					ntohs(err_chunk->chunk_hdr->length) -
					sizeof(sctp_chunkhdr_t));

			sctp_chunk_free(err_chunk);

			if (packet) {
				sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
						SCTP_PACKET(packet));
				SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
				return SCTP_DISPOSITION_CONSUME;
			} else {
				return SCTP_DISPOSITION_NOMEM;
			}
		} else {
			return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg,
						    commands);
		}
	}

	/* Grab the INIT header.  */
	chunk->subh.init_hdr = (sctp_inithdr_t *)chunk->skb->data;

	/* Tag the variable length parameters.  */
	chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(sctp_inithdr_t));

	new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC);
	if (!new_asoc)
		goto nomem;

	if (sctp_assoc_set_bind_addr_from_ep(new_asoc,
					     sctp_scope(sctp_source(chunk)),
					     GFP_ATOMIC) < 0)
		goto nomem_init;

	/* The call, sctp_process_init(), can fail on memory allocation.  */
	if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk),
			       (sctp_init_chunk_t *)chunk->chunk_hdr,
			       GFP_ATOMIC))
		goto nomem_init;

	/* B) "Z" shall respond immediately with an INIT ACK chunk.  */

	/* If there are errors need to be reported for unknown parameters,
	 * make sure to reserve enough room in the INIT ACK for them.
	 */
	len = 0;
	if (err_chunk)
		len = ntohs(err_chunk->chunk_hdr->length) -
			sizeof(sctp_chunkhdr_t);

	repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len);
	if (!repl)
		goto nomem_init;

	/* If there are errors need to be reported for unknown parameters,
	 * include them in the outgoing INIT ACK as "Unrecognized parameter"
	 * parameter.
	 */
	if (err_chunk) {
		/* Get the "Unrecognized parameter" parameter(s) out of the
		 * ERROR chunk generated by sctp_verify_init(). Since the
		 * error cause code for "unknown parameter" and the
		 * "Unrecognized parameter" type is the same, we can
		 * construct the parameters in INIT ACK by copying the
		 * ERROR causes over.
		 */
		unk_param = (sctp_unrecognized_param_t *)
			    ((__u8 *)(err_chunk->chunk_hdr) +
			    sizeof(sctp_chunkhdr_t));
		/* Replace the cause code with the "Unrecognized parameter"
		 * parameter type.
		 */
		sctp_addto_chunk(repl, len, unk_param);
		sctp_chunk_free(err_chunk);
	}

	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));

	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));

	/*
	 * Note:  After sending out INIT ACK with the State Cookie parameter,
	 * "Z" MUST NOT allocate any resources, nor keep any states for the
	 * new association.  Otherwise, "Z" will be vulnerable to resource
	 * attacks.
	 */
	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());

	return SCTP_DISPOSITION_DELETE_TCB;

nomem_init:
	sctp_association_free(new_asoc);
nomem:
	if (err_chunk)
		sctp_chunk_free(err_chunk);
	return SCTP_DISPOSITION_NOMEM;
}