net/rxrpc/ar-accept.c - kernel/msm - Gitiles

 /* incoming call handling
  *
  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */

 #include <linux/module.h>
 #include <linux/net.h>
 #include <linux/skbuff.h>
 #include <linux/errqueue.h>
 #include <linux/udp.h>
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/icmp.h>
 #include <net/sock.h>
 #include <net/af_rxrpc.h>
 #include <net/ip.h>
 #include "ar-internal.h"

 /*
  * generate a connection-level abort
  */
 static int rxrpc_busy(struct rxrpc_local *local, struct sockaddr_rxrpc *srx,
 		      struct rxrpc_header *hdr)
 {
 	struct msghdr msg;
 	struct kvec iov[1];
 	size_t len;
 	int ret;

 	_enter("%d,,", local->debug_id);

 	msg.msg_name	= &srx->transport.sin;
 	msg.msg_namelen	= sizeof(srx->transport.sin);
 	msg.msg_control	= NULL;
 	msg.msg_controllen = 0;
 	msg.msg_flags	= 0;

 	hdr->seq	= 0;
 	hdr->type	= RXRPC_PACKET_TYPE_BUSY;
 	hdr->flags	= 0;
 	hdr->userStatus	= 0;
 	hdr->_rsvd	= 0;

 	iov[0].iov_base	= hdr;
 	iov[0].iov_len	= sizeof(*hdr);

 	len = iov[0].iov_len;

 	hdr->serial = htonl(1);
 	_proto("Tx BUSY %%%u", ntohl(hdr->serial));

 	ret = kernel_sendmsg(local->socket, &msg, iov, 1, len);
 	if (ret < 0) {
 		_leave(" = -EAGAIN [sendmsg failed: %d]", ret);
 		return -EAGAIN;
 	}

 	_leave(" = 0");
 	return 0;
 }

 /*
  * accept an incoming call that needs peer, transport and/or connection setting
  * up
  */
 static int rxrpc_accept_incoming_call(struct rxrpc_local *local,
 				      struct rxrpc_sock *rx,
 				      struct sk_buff *skb,
 				      struct sockaddr_rxrpc *srx)
 {
 	struct rxrpc_connection *conn;
 	struct rxrpc_transport *trans;
 	struct rxrpc_skb_priv *sp, *nsp;
 	struct rxrpc_peer *peer;
 	struct rxrpc_call *call;
 	struct sk_buff *notification;
 	int ret;

 	_enter("");

 	sp = rxrpc_skb(skb);

 	/* get a notification message to send to the server app */
 	notification = alloc_skb(0, GFP_NOFS);
 	if (!notification) {
 		_debug("no memory");
 		ret = -ENOMEM;
 		goto error_nofree;
 	}
 	rxrpc_new_skb(notification);
 	notification->mark = RXRPC_SKB_MARK_NEW_CALL;

 	peer = rxrpc_get_peer(srx, GFP_NOIO);
 	if (IS_ERR(peer)) {
 		_debug("no peer");
 		ret = -EBUSY;
 		goto error;
 	}

 	trans = rxrpc_get_transport(local, peer, GFP_NOIO);
 	rxrpc_put_peer(peer);
 	if (IS_ERR(trans)) {
 		_debug("no trans");
 		ret = -EBUSY;
 		goto error;
 	}

 	conn = rxrpc_incoming_connection(trans, &sp->hdr, GFP_NOIO);
 	rxrpc_put_transport(trans);
 	if (IS_ERR(conn)) {
 		_debug("no conn");
 		ret = PTR_ERR(conn);
 		goto error;
 	}

 	call = rxrpc_incoming_call(rx, conn, &sp->hdr, GFP_NOIO);
 	rxrpc_put_connection(conn);
 	if (IS_ERR(call)) {
 		_debug("no call");
 		ret = PTR_ERR(call);
 		goto error;
 	}

 	/* attach the call to the socket */
 	read_lock_bh(&local->services_lock);
 	if (rx->sk.sk_state == RXRPC_CLOSE)
 		goto invalid_service;

 	write_lock(&rx->call_lock);
 	if (!test_and_set_bit(RXRPC_CALL_INIT_ACCEPT, &call->flags)) {
 		rxrpc_get_call(call);

 		spin_lock(&call->conn->state_lock);
 		if (sp->hdr.securityIndex > 0 &&
 		    call->conn->state == RXRPC_CONN_SERVER_UNSECURED) {
 			_debug("await conn sec");
 			list_add_tail(&call->accept_link, &rx->secureq);
 			call->conn->state = RXRPC_CONN_SERVER_CHALLENGING;
 			atomic_inc(&call->conn->usage);
 			set_bit(RXRPC_CONN_CHALLENGE, &call->conn->events);
 			rxrpc_queue_conn(call->conn);
 		} else {
 			_debug("conn ready");
 			call->state = RXRPC_CALL_SERVER_ACCEPTING;
 			list_add_tail(&call->accept_link, &rx->acceptq);
 			rxrpc_get_call(call);
 			nsp = rxrpc_skb(notification);
 			nsp->call = call;

 			ASSERTCMP(atomic_read(&call->usage), >=, 3);

 			_debug("notify");
 			spin_lock(&call->lock);
 			ret = rxrpc_queue_rcv_skb(call, notification, true,
 						  false);
 			spin_unlock(&call->lock);
 			notification = NULL;
 			BUG_ON(ret < 0);
 		}
 		spin_unlock(&call->conn->state_lock);

 		_debug("queued");
 	}
 	write_unlock(&rx->call_lock);

 	_debug("process");
 	rxrpc_fast_process_packet(call, skb);

 	_debug("done");
 	read_unlock_bh(&local->services_lock);
 	rxrpc_free_skb(notification);
 	rxrpc_put_call(call);
 	_leave(" = 0");
 	return 0;

 invalid_service:
 	_debug("invalid");
 	read_unlock_bh(&local->services_lock);

 	read_lock_bh(&call->state_lock);
 	if (!test_bit(RXRPC_CALL_RELEASE, &call->flags) &&
 	    !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events)) {
 		rxrpc_get_call(call);
 		rxrpc_queue_call(call);
 	}
 	read_unlock_bh(&call->state_lock);
 	rxrpc_put_call(call);
 	ret = -ECONNREFUSED;
 error:
 	rxrpc_free_skb(notification);
 error_nofree:
 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * accept incoming calls that need peer, transport and/or connection setting up
  * - the packets we get are all incoming client DATA packets that have seq == 1
  */
 void rxrpc_accept_incoming_calls(struct work_struct *work)
 {
 	struct rxrpc_local *local =
 		container_of(work, struct rxrpc_local, acceptor);
 	struct rxrpc_skb_priv *sp;
 	struct sockaddr_rxrpc srx;
 	struct rxrpc_sock *rx;
 	struct sk_buff *skb;
 	__be16 service_id;
 	int ret;

 	_enter("%d", local->debug_id);

 	read_lock_bh(&rxrpc_local_lock);
 	if (atomic_read(&local->usage) > 0)
 		rxrpc_get_local(local);
 	else
 		local = NULL;
 	read_unlock_bh(&rxrpc_local_lock);
 	if (!local) {
 		_leave(" [local dead]");
 		return;
 	}

 process_next_packet:
 	skb = skb_dequeue(&local->accept_queue);
 	if (!skb) {
 		rxrpc_put_local(local);
 		_leave("\n");
 		return;
 	}

 	_net("incoming call skb %p", skb);

 	sp = rxrpc_skb(skb);

 	/* determine the remote address */
 	memset(&srx, 0, sizeof(srx));
 	srx.srx_family = AF_RXRPC;
 	srx.transport.family = local->srx.transport.family;
 	srx.transport_type = local->srx.transport_type;
 	switch (srx.transport.family) {
 	case AF_INET:
 		srx.transport_len = sizeof(struct sockaddr_in);
 		srx.transport.sin.sin_port = udp_hdr(skb)->source;
 		srx.transport.sin.sin_addr.s_addr = ip_hdr(skb)->saddr;
 		break;
 	default:
 		goto busy;
 	}

 	/* get the socket providing the service */
 	service_id = sp->hdr.serviceId;
 	read_lock_bh(&local->services_lock);
 	list_for_each_entry(rx, &local->services, listen_link) {
 		if (rx->service_id == service_id &&
 		    rx->sk.sk_state != RXRPC_CLOSE)
 			goto found_service;
 	}
 	read_unlock_bh(&local->services_lock);
 	goto invalid_service;

 found_service:
 	_debug("found service %hd", ntohs(rx->service_id));
 	if (sk_acceptq_is_full(&rx->sk))
 		goto backlog_full;
 	sk_acceptq_added(&rx->sk);
 	sock_hold(&rx->sk);
 	read_unlock_bh(&local->services_lock);

 	ret = rxrpc_accept_incoming_call(local, rx, skb, &srx);
 	if (ret < 0)
 		sk_acceptq_removed(&rx->sk);
 	sock_put(&rx->sk);
 	switch (ret) {
 	case -ECONNRESET: /* old calls are ignored */
 	case -ECONNABORTED: /* aborted calls are reaborted or ignored */
 	case 0:
 		goto process_next_packet;
 	case -ECONNREFUSED:
 		goto invalid_service;
 	case -EBUSY:
 		goto busy;
 	case -EKEYREJECTED:
 		goto security_mismatch;
 	default:
 		BUG();
 	}

 backlog_full:
 	read_unlock_bh(&local->services_lock);
 busy:
 	rxrpc_busy(local, &srx, &sp->hdr);
 	rxrpc_free_skb(skb);
 	goto process_next_packet;

 invalid_service:
 	skb->priority = RX_INVALID_OPERATION;
 	rxrpc_reject_packet(local, skb);
 	goto process_next_packet;

 	/* can't change connection security type mid-flow */
 security_mismatch:
 	skb->priority = RX_PROTOCOL_ERROR;
 	rxrpc_reject_packet(local, skb);
 	goto process_next_packet;
 }

 /*
  * handle acceptance of a call by userspace
  * - assign the user call ID to the call at the front of the queue
  */
 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 				     unsigned long user_call_ID)
 {
 	struct rxrpc_call *call;
 	struct rb_node *parent, **pp;
 	int ret;

 	_enter(",%lx", user_call_ID);

 	ASSERT(!irqs_disabled());

 	write_lock(&rx->call_lock);

 	ret = -ENODATA;
 	if (list_empty(&rx->acceptq))
 		goto out;

 	/* check the user ID isn't already in use */
 	ret = -EBADSLT;
 	pp = &rx->calls.rb_node;
 	parent = NULL;
 	while (*pp) {
 		parent = *pp;
 		call = rb_entry(parent, struct rxrpc_call, sock_node);

 		if (user_call_ID < call->user_call_ID)
 			pp = &(*pp)->rb_left;
 		else if (user_call_ID > call->user_call_ID)
 			pp = &(*pp)->rb_right;
 		else
 			goto out;
 	}

 	/* dequeue the first call and check it's still valid */
 	call = list_entry(rx->acceptq.next, struct rxrpc_call, accept_link);
 	list_del_init(&call->accept_link);
 	sk_acceptq_removed(&rx->sk);

 	write_lock_bh(&call->state_lock);
 	switch (call->state) {
 	case RXRPC_CALL_SERVER_ACCEPTING:
 		call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 		break;
 	case RXRPC_CALL_REMOTELY_ABORTED:
 	case RXRPC_CALL_LOCALLY_ABORTED:
 		ret = -ECONNABORTED;
 		goto out_release;
 	case RXRPC_CALL_NETWORK_ERROR:
 		ret = call->conn->error;
 		goto out_release;
 	case RXRPC_CALL_DEAD:
 		ret = -ETIME;
 		goto out_discard;
 	default:
 		BUG();
 	}

 	/* formalise the acceptance */
 	call->user_call_ID = user_call_ID;
 	rb_link_node(&call->sock_node, parent, pp);
 	rb_insert_color(&call->sock_node, &rx->calls);
 	if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 		BUG();
 	if (test_and_set_bit(RXRPC_CALL_ACCEPTED, &call->events))
 		BUG();
 	rxrpc_queue_call(call);

 	rxrpc_get_call(call);
 	write_unlock_bh(&call->state_lock);
 	write_unlock(&rx->call_lock);
 	_leave(" = %p{%d}", call, call->debug_id);
 	return call;

 	/* if the call is already dying or dead, then we leave the socket's ref
 	 * on it to be released by rxrpc_dead_call_expired() as induced by
 	 * rxrpc_release_call() */
 out_release:
 	_debug("release %p", call);
 	if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
 	    !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
 		rxrpc_queue_call(call);
 out_discard:
 	write_unlock_bh(&call->state_lock);
 	_debug("discard %p", call);
 out:
 	write_unlock(&rx->call_lock);
 	_leave(" = %d", ret);
 	return ERR_PTR(ret);
 }

 /*
  * handle rejectance of a call by userspace
  * - reject the call at the front of the queue
  */
 int rxrpc_reject_call(struct rxrpc_sock *rx)
 {
 	struct rxrpc_call *call;
 	int ret;

 	_enter("");

 	ASSERT(!irqs_disabled());

 	write_lock(&rx->call_lock);

 	ret = -ENODATA;
 	if (list_empty(&rx->acceptq))
 		goto out;

 	/* dequeue the first call and check it's still valid */
 	call = list_entry(rx->acceptq.next, struct rxrpc_call, accept_link);
 	list_del_init(&call->accept_link);
 	sk_acceptq_removed(&rx->sk);

 	write_lock_bh(&call->state_lock);
 	switch (call->state) {
 	case RXRPC_CALL_SERVER_ACCEPTING:
 		call->state = RXRPC_CALL_SERVER_BUSY;
 		if (test_and_set_bit(RXRPC_CALL_REJECT_BUSY, &call->events))
 			rxrpc_queue_call(call);
 		ret = 0;
 		goto out_release;
 	case RXRPC_CALL_REMOTELY_ABORTED:
 	case RXRPC_CALL_LOCALLY_ABORTED:
 		ret = -ECONNABORTED;
 		goto out_release;
 	case RXRPC_CALL_NETWORK_ERROR:
 		ret = call->conn->error;
 		goto out_release;
 	case RXRPC_CALL_DEAD:
 		ret = -ETIME;
 		goto out_discard;
 	default:
 		BUG();
 	}

 	/* if the call is already dying or dead, then we leave the socket's ref
 	 * on it to be released by rxrpc_dead_call_expired() as induced by
 	 * rxrpc_release_call() */
 out_release:
 	_debug("release %p", call);
 	if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
 	    !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
 		rxrpc_queue_call(call);
 out_discard:
 	write_unlock_bh(&call->state_lock);
 	_debug("discard %p", call);
 out:
 	write_unlock(&rx->call_lock);
 	_leave(" = %d", ret);
 	return ret;
 }

 /**
  * rxrpc_kernel_accept_call - Allow a kernel service to accept an incoming call
  * @sock: The socket on which the impending call is waiting
  * @user_call_ID: The tag to attach to the call
  *
  * Allow a kernel service to accept an incoming call, assuming the incoming
  * call is still valid.
  */
 struct rxrpc_call *rxrpc_kernel_accept_call(struct socket *sock,
 					    unsigned long user_call_ID)
 {
 	struct rxrpc_call *call;

 	_enter(",%lx", user_call_ID);
 	call = rxrpc_accept_call(rxrpc_sk(sock->sk), user_call_ID);
 	_leave(" = %p", call);
 	return call;
 }

 EXPORT_SYMBOL(rxrpc_kernel_accept_call);

 /**
  * rxrpc_kernel_reject_call - Allow a kernel service to reject an incoming call
  * @sock: The socket on which the impending call is waiting
  *
  * Allow a kernel service to reject an incoming call with a BUSY message,
  * assuming the incoming call is still valid.
  */
 int rxrpc_kernel_reject_call(struct socket *sock)
 {
 	int ret;

 	_enter("");
 	ret = rxrpc_reject_call(rxrpc_sk(sock->sk));
 	_leave(" = %d", ret);
 	return ret;
 }

 EXPORT_SYMBOL(rxrpc_kernel_reject_call);
	/* incoming call handling
	*
	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	#include <linux/module.h>
	#include <linux/net.h>
	#include <linux/skbuff.h>
	#include <linux/errqueue.h>
	#include <linux/udp.h>
	#include <linux/in.h>
	#include <linux/in6.h>
	#include <linux/icmp.h>
	#include <net/sock.h>
	#include <net/af_rxrpc.h>
	#include <net/ip.h>
	#include "ar-internal.h"

	/*
	* generate a connection-level abort
	*/
	static int rxrpc_busy(struct rxrpc_local local, struct sockaddr_rxrpc srx,
	struct rxrpc_header *hdr)
	{
	struct msghdr msg;
	struct kvec iov[1];
	size_t len;
	int ret;

	_enter("%d,,", local->debug_id);

	msg.msg_name = &srx->transport.sin;
	msg.msg_namelen = sizeof(srx->transport.sin);
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	msg.msg_flags = 0;

	hdr->seq = 0;
	hdr->type = RXRPC_PACKET_TYPE_BUSY;
	hdr->flags = 0;
	hdr->userStatus = 0;
	hdr->_rsvd = 0;

	iov[0].iov_base = hdr;
	iov[0].iov_len = sizeof(*hdr);

	len = iov[0].iov_len;

	hdr->serial = htonl(1);
	_proto("Tx BUSY %%%u", ntohl(hdr->serial));

	ret = kernel_sendmsg(local->socket, &msg, iov, 1, len);
	if (ret < 0) {
	_leave(" = -EAGAIN [sendmsg failed: %d]", ret);
	return -EAGAIN;
	}

	_leave(" = 0");
	return 0;
	}

	/*
	* accept an incoming call that needs peer, transport and/or connection setting
	* up
	*/
	static int rxrpc_accept_incoming_call(struct rxrpc_local *local,
	struct rxrpc_sock *rx,
	struct sk_buff *skb,
	struct sockaddr_rxrpc *srx)
	{
	struct rxrpc_connection *conn;
	struct rxrpc_transport *trans;
	struct rxrpc_skb_priv sp, nsp;
	struct rxrpc_peer *peer;
	struct rxrpc_call *call;
	struct sk_buff *notification;
	int ret;

	_enter("");

	sp = rxrpc_skb(skb);

	/* get a notification message to send to the server app */
	notification = alloc_skb(0, GFP_NOFS);
	if (!notification) {
	_debug("no memory");
	ret = -ENOMEM;
	goto error_nofree;
	}
	rxrpc_new_skb(notification);
	notification->mark = RXRPC_SKB_MARK_NEW_CALL;

	peer = rxrpc_get_peer(srx, GFP_NOIO);
	if (IS_ERR(peer)) {
	_debug("no peer");
	ret = -EBUSY;
	goto error;
	}

	trans = rxrpc_get_transport(local, peer, GFP_NOIO);
	rxrpc_put_peer(peer);
	if (IS_ERR(trans)) {
	_debug("no trans");
	ret = -EBUSY;
	goto error;
	}

	conn = rxrpc_incoming_connection(trans, &sp->hdr, GFP_NOIO);
	rxrpc_put_transport(trans);
	if (IS_ERR(conn)) {
	_debug("no conn");
	ret = PTR_ERR(conn);
	goto error;
	}

	call = rxrpc_incoming_call(rx, conn, &sp->hdr, GFP_NOIO);
	rxrpc_put_connection(conn);
	if (IS_ERR(call)) {
	_debug("no call");
	ret = PTR_ERR(call);
	goto error;
	}

	/* attach the call to the socket */
	read_lock_bh(&local->services_lock);
	if (rx->sk.sk_state == RXRPC_CLOSE)
	goto invalid_service;

	write_lock(&rx->call_lock);
	if (!test_and_set_bit(RXRPC_CALL_INIT_ACCEPT, &call->flags)) {
	rxrpc_get_call(call);

	spin_lock(&call->conn->state_lock);
	if (sp->hdr.securityIndex > 0 &&
	call->conn->state == RXRPC_CONN_SERVER_UNSECURED) {
	_debug("await conn sec");
	list_add_tail(&call->accept_link, &rx->secureq);
	call->conn->state = RXRPC_CONN_SERVER_CHALLENGING;
	atomic_inc(&call->conn->usage);
	set_bit(RXRPC_CONN_CHALLENGE, &call->conn->events);
	rxrpc_queue_conn(call->conn);
	} else {
	_debug("conn ready");
	call->state = RXRPC_CALL_SERVER_ACCEPTING;
	list_add_tail(&call->accept_link, &rx->acceptq);
	rxrpc_get_call(call);
	nsp = rxrpc_skb(notification);
	nsp->call = call;

	ASSERTCMP(atomic_read(&call->usage), >=, 3);

	_debug("notify");
	spin_lock(&call->lock);
	ret = rxrpc_queue_rcv_skb(call, notification, true,
	false);
	spin_unlock(&call->lock);
	notification = NULL;
	BUG_ON(ret < 0);
	}
	spin_unlock(&call->conn->state_lock);

	_debug("queued");
	}
	write_unlock(&rx->call_lock);

	_debug("process");
	rxrpc_fast_process_packet(call, skb);

	_debug("done");
	read_unlock_bh(&local->services_lock);
	rxrpc_free_skb(notification);
	rxrpc_put_call(call);
	_leave(" = 0");
	return 0;

	invalid_service:
	_debug("invalid");
	read_unlock_bh(&local->services_lock);

	read_lock_bh(&call->state_lock);
	if (!test_bit(RXRPC_CALL_RELEASE, &call->flags) &&
	!test_and_set_bit(RXRPC_CALL_RELEASE, &call->events)) {
	rxrpc_get_call(call);
	rxrpc_queue_call(call);
	}
	read_unlock_bh(&call->state_lock);
	rxrpc_put_call(call);
	ret = -ECONNREFUSED;
	error:
	rxrpc_free_skb(notification);
	error_nofree:
	_leave(" = %d", ret);
	return ret;
	}

	/*
	* accept incoming calls that need peer, transport and/or connection setting up
	* - the packets we get are all incoming client DATA packets that have seq == 1
	*/
	void rxrpc_accept_incoming_calls(struct work_struct *work)
	{
	struct rxrpc_local *local =
	container_of(work, struct rxrpc_local, acceptor);
	struct rxrpc_skb_priv *sp;
	struct sockaddr_rxrpc srx;
	struct rxrpc_sock *rx;
	struct sk_buff *skb;
	__be16 service_id;
	int ret;

	_enter("%d", local->debug_id);

	read_lock_bh(&rxrpc_local_lock);
	if (atomic_read(&local->usage) > 0)
	rxrpc_get_local(local);
	else
	local = NULL;
	read_unlock_bh(&rxrpc_local_lock);
	if (!local) {
	_leave(" [local dead]");
	return;
	}

	process_next_packet:
	skb = skb_dequeue(&local->accept_queue);
	if (!skb) {
	rxrpc_put_local(local);
	_leave("\n");
	return;
	}

	_net("incoming call skb %p", skb);

	sp = rxrpc_skb(skb);

	/* determine the remote address */
	memset(&srx, 0, sizeof(srx));
	srx.srx_family = AF_RXRPC;
	srx.transport.family = local->srx.transport.family;
	srx.transport_type = local->srx.transport_type;
	switch (srx.transport.family) {
	case AF_INET:
	srx.transport_len = sizeof(struct sockaddr_in);
	srx.transport.sin.sin_port = udp_hdr(skb)->source;
	srx.transport.sin.sin_addr.s_addr = ip_hdr(skb)->saddr;
	break;
	default:
	goto busy;
	}

	/* get the socket providing the service */
	service_id = sp->hdr.serviceId;
	read_lock_bh(&local->services_lock);
	list_for_each_entry(rx, &local->services, listen_link) {
	if (rx->service_id == service_id &&
	rx->sk.sk_state != RXRPC_CLOSE)
	goto found_service;
	}
	read_unlock_bh(&local->services_lock);
	goto invalid_service;

	found_service:
	_debug("found service %hd", ntohs(rx->service_id));
	if (sk_acceptq_is_full(&rx->sk))
	goto backlog_full;
	sk_acceptq_added(&rx->sk);
	sock_hold(&rx->sk);
	read_unlock_bh(&local->services_lock);

	ret = rxrpc_accept_incoming_call(local, rx, skb, &srx);
	if (ret < 0)
	sk_acceptq_removed(&rx->sk);
	sock_put(&rx->sk);
	switch (ret) {
	case -ECONNRESET: /* old calls are ignored */
	case -ECONNABORTED: /* aborted calls are reaborted or ignored */
	case 0:
	goto process_next_packet;
	case -ECONNREFUSED:
	goto invalid_service;
	case -EBUSY:
	goto busy;
	case -EKEYREJECTED:
	goto security_mismatch;
	default:
	BUG();
	}

	backlog_full:
	read_unlock_bh(&local->services_lock);
	busy:
	rxrpc_busy(local, &srx, &sp->hdr);
	rxrpc_free_skb(skb);
	goto process_next_packet;

	invalid_service:
	skb->priority = RX_INVALID_OPERATION;
	rxrpc_reject_packet(local, skb);
	goto process_next_packet;

	/* can't change connection security type mid-flow */
	security_mismatch:
	skb->priority = RX_PROTOCOL_ERROR;
	rxrpc_reject_packet(local, skb);
	goto process_next_packet;
	}

	/*
	* handle acceptance of a call by userspace
	* - assign the user call ID to the call at the front of the queue
	*/
	struct rxrpc_call rxrpc_accept_call(struct rxrpc_sock rx,
	unsigned long user_call_ID)
	{
	struct rxrpc_call *call;
	struct rb_node parent, *pp;
	int ret;

	_enter(",%lx", user_call_ID);

	ASSERT(!irqs_disabled());

	write_lock(&rx->call_lock);

	ret = -ENODATA;
	if (list_empty(&rx->acceptq))
	goto out;

	/* check the user ID isn't already in use */
	ret = -EBADSLT;
	pp = &rx->calls.rb_node;
	parent = NULL;
	while (*pp) {
	parent = *pp;
	call = rb_entry(parent, struct rxrpc_call, sock_node);

	if (user_call_ID < call->user_call_ID)
	pp = &(*pp)->rb_left;
	else if (user_call_ID > call->user_call_ID)
	pp = &(*pp)->rb_right;
	else
	goto out;
	}

	/* dequeue the first call and check it's still valid */
	call = list_entry(rx->acceptq.next, struct rxrpc_call, accept_link);
	list_del_init(&call->accept_link);
	sk_acceptq_removed(&rx->sk);

	write_lock_bh(&call->state_lock);
	switch (call->state) {
	case RXRPC_CALL_SERVER_ACCEPTING:
	call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
	break;
	case RXRPC_CALL_REMOTELY_ABORTED:
	case RXRPC_CALL_LOCALLY_ABORTED:
	ret = -ECONNABORTED;
	goto out_release;
	case RXRPC_CALL_NETWORK_ERROR:
	ret = call->conn->error;
	goto out_release;
	case RXRPC_CALL_DEAD:
	ret = -ETIME;
	goto out_discard;
	default:
	BUG();
	}

	/* formalise the acceptance */
	call->user_call_ID = user_call_ID;
	rb_link_node(&call->sock_node, parent, pp);
	rb_insert_color(&call->sock_node, &rx->calls);
	if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
	BUG();
	if (test_and_set_bit(RXRPC_CALL_ACCEPTED, &call->events))
	BUG();
	rxrpc_queue_call(call);

	rxrpc_get_call(call);
	write_unlock_bh(&call->state_lock);
	write_unlock(&rx->call_lock);
	_leave(" = %p{%d}", call, call->debug_id);
	return call;

	/* if the call is already dying or dead, then we leave the socket's ref
	* on it to be released by rxrpc_dead_call_expired() as induced by
	* rxrpc_release_call() */
	out_release:
	_debug("release %p", call);
	if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
	!test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
	rxrpc_queue_call(call);
	out_discard:
	write_unlock_bh(&call->state_lock);
	_debug("discard %p", call);
	out:
	write_unlock(&rx->call_lock);
	_leave(" = %d", ret);
	return ERR_PTR(ret);
	}

	/*
	* handle rejectance of a call by userspace
	* - reject the call at the front of the queue
	*/
	int rxrpc_reject_call(struct rxrpc_sock *rx)
	{
	struct rxrpc_call *call;
	int ret;

	_enter("");

	ASSERT(!irqs_disabled());

	write_lock(&rx->call_lock);

	ret = -ENODATA;
	if (list_empty(&rx->acceptq))
	goto out;

	/* dequeue the first call and check it's still valid */
	call = list_entry(rx->acceptq.next, struct rxrpc_call, accept_link);
	list_del_init(&call->accept_link);
	sk_acceptq_removed(&rx->sk);

	write_lock_bh(&call->state_lock);
	switch (call->state) {
	case RXRPC_CALL_SERVER_ACCEPTING:
	call->state = RXRPC_CALL_SERVER_BUSY;
	if (test_and_set_bit(RXRPC_CALL_REJECT_BUSY, &call->events))
	rxrpc_queue_call(call);
	ret = 0;
	goto out_release;
	case RXRPC_CALL_REMOTELY_ABORTED:
	case RXRPC_CALL_LOCALLY_ABORTED:
	ret = -ECONNABORTED;
	goto out_release;
	case RXRPC_CALL_NETWORK_ERROR:
	ret = call->conn->error;
	goto out_release;
	case RXRPC_CALL_DEAD:
	ret = -ETIME;
	goto out_discard;
	default:
	BUG();
	}

	/* if the call is already dying or dead, then we leave the socket's ref
	* on it to be released by rxrpc_dead_call_expired() as induced by
	* rxrpc_release_call() */
	out_release:
	_debug("release %p", call);
	if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
	!test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
	rxrpc_queue_call(call);
	out_discard:
	write_unlock_bh(&call->state_lock);
	_debug("discard %p", call);
	out:
	write_unlock(&rx->call_lock);
	_leave(" = %d", ret);
	return ret;
	}

	/**
	* rxrpc_kernel_accept_call - Allow a kernel service to accept an incoming call
	* @sock: The socket on which the impending call is waiting
	* @user_call_ID: The tag to attach to the call
	*
	* Allow a kernel service to accept an incoming call, assuming the incoming
	* call is still valid.
	*/
	struct rxrpc_call rxrpc_kernel_accept_call(struct socket sock,
	unsigned long user_call_ID)
	{
	struct rxrpc_call *call;

	_enter(",%lx", user_call_ID);
	call = rxrpc_accept_call(rxrpc_sk(sock->sk), user_call_ID);
	_leave(" = %p", call);
	return call;
	}

	EXPORT_SYMBOL(rxrpc_kernel_accept_call);

	/**
	* rxrpc_kernel_reject_call - Allow a kernel service to reject an incoming call
	* @sock: The socket on which the impending call is waiting
	*
	* Allow a kernel service to reject an incoming call with a BUSY message,
	* assuming the incoming call is still valid.
	*/
	int rxrpc_kernel_reject_call(struct socket *sock)
	{
	int ret;

	_enter("");
	ret = rxrpc_reject_call(rxrpc_sk(sock->sk));
	_leave(" = %d", ret);
	return ret;
	}

	EXPORT_SYMBOL(rxrpc_kernel_reject_call);