net/phonet/af_phonet.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * File: af_phonet.c
  *
  * Phonet protocols family
  *
  * Copyright (C) 2008 Nokia Corporation.
  *
  * Authors: Sakari Ailus <sakari.ailus@nokia.com>
  *          Rémi Denis-Courmont
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/unaligned.h>
 #include <net/sock.h>

 #include <linux/if_phonet.h>
 #include <linux/phonet.h>
 #include <net/phonet/phonet.h>
 #include <net/phonet/pn_dev.h>

 /* Transport protocol registration */
 static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;

 static const struct phonet_protocol *phonet_proto_get(unsigned int protocol)
 {
 	const struct phonet_protocol *pp;

 	if (protocol >= PHONET_NPROTO)
 		return NULL;

 	rcu_read_lock();
 	pp = rcu_dereference(proto_tab[protocol]);
 	if (pp && !try_module_get(pp->prot->owner))
 		pp = NULL;
 	rcu_read_unlock();

 	return pp;
 }

 static inline void phonet_proto_put(const struct phonet_protocol *pp)
 {
 	module_put(pp->prot->owner);
 }

 /* protocol family functions */

 static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
 			    int kern)
 {
 	struct sock *sk;
 	struct pn_sock *pn;
 	const struct phonet_protocol *pnp;
 	int err;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	if (protocol == 0) {
 		/* Default protocol selection */
 		switch (sock->type) {
 		case SOCK_DGRAM:
 			protocol = PN_PROTO_PHONET;
 			break;
 		case SOCK_SEQPACKET:
 			protocol = PN_PROTO_PIPE;
 			break;
 		default:
 			return -EPROTONOSUPPORT;
 		}
 	}

 	pnp = phonet_proto_get(protocol);
 	if (pnp == NULL &&
 	    request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
 		pnp = phonet_proto_get(protocol);

 	if (pnp == NULL)
 		return -EPROTONOSUPPORT;
 	if (sock->type != pnp->sock_type) {
 		err = -EPROTONOSUPPORT;
 		goto out;
 	}

 	sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot, kern);
 	if (sk == NULL) {
 		err = -ENOMEM;
 		goto out;
 	}

 	sock_init_data(sock, sk);
 	sock->state = SS_UNCONNECTED;
 	sock->ops = pnp->ops;
 	sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
 	sk->sk_protocol = protocol;
 	pn = pn_sk(sk);
 	pn->sobject = 0;
 	pn->dobject = 0;
 	pn->resource = 0;
 	sk->sk_prot->init(sk);
 	err = 0;

 out:
 	phonet_proto_put(pnp);
 	return err;
 }

 static const struct net_proto_family phonet_proto_family = {
 	.family = PF_PHONET,
 	.create = pn_socket_create,
 	.owner = THIS_MODULE,
 };

 /* Phonet device header operations */
 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 				unsigned short type, const void *daddr,
 				const void *saddr, unsigned int len)
 {
 	u8 *media = skb_push(skb, 1);

 	if (type != ETH_P_PHONET)
 		return -1;

 	if (!saddr)
 		saddr = dev->dev_addr;
 	*media = *(const u8 *)saddr;
 	return 1;
 }

 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 {
 	const u8 *media = skb_mac_header(skb);
 	*haddr = *media;
 	return 1;
 }

 const struct header_ops phonet_header_ops = {
 	.create = pn_header_create,
 	.parse = pn_header_parse,
 };
 EXPORT_SYMBOL(phonet_header_ops);

 /*
  * Prepends an ISI header and sends a datagram.
  */
 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 			u16 dst, u16 src, u8 res)
 {
 	struct phonethdr *ph;
 	int err;

 	if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
 	    skb->len + sizeof(struct phonethdr) > dev->mtu) {
 		err = -EMSGSIZE;
 		goto drop;
 	}

 	/* Broadcast sending is not implemented */
 	if (pn_addr(dst) == PNADDR_BROADCAST) {
 		err = -EOPNOTSUPP;
 		goto drop;
 	}

 	skb_reset_transport_header(skb);
 	WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 	skb_push(skb, sizeof(struct phonethdr));
 	skb_reset_network_header(skb);
 	ph = pn_hdr(skb);
 	ph->pn_rdev = pn_dev(dst);
 	ph->pn_sdev = pn_dev(src);
 	ph->pn_res = res;
 	ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 	ph->pn_robj = pn_obj(dst);
 	ph->pn_sobj = pn_obj(src);

 	skb->protocol = htons(ETH_P_PHONET);
 	skb->priority = 0;
 	skb->dev = dev;

 	if (skb->pkt_type == PACKET_LOOPBACK) {
 		skb_reset_mac_header(skb);
 		skb_orphan(skb);
 		err = netif_rx(skb) ? -ENOBUFS : 0;
 	} else {
 		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 					NULL, NULL, skb->len);
 		if (err < 0) {
 			err = -EHOSTUNREACH;
 			goto drop;
 		}
 		err = dev_queue_xmit(skb);
 		if (unlikely(err > 0))
 			err = net_xmit_errno(err);
 	}

 	return err;
 drop:
 	kfree_skb(skb);
 	return err;
 }

 static int pn_raw_send(const void *data, int len, struct net_device *dev,
 			u16 dst, u16 src, u8 res)
 {
 	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 	if (skb == NULL)
 		return -ENOMEM;

 	if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
 		skb->pkt_type = PACKET_LOOPBACK;

 	skb_reserve(skb, MAX_PHONET_HEADER);
 	__skb_put(skb, len);
 	skb_copy_to_linear_data(skb, data, len);
 	return pn_send(skb, dev, dst, src, res);
 }

 /*
  * Create a Phonet header for the skb and send it out. Returns
  * non-zero error code if failed. The skb is freed then.
  */
 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 		const struct sockaddr_pn *target)
 {
 	struct net *net = sock_net(sk);
 	struct net_device *dev;
 	struct pn_sock *pn = pn_sk(sk);
 	int err;
 	u16 src, dst;
 	u8 daddr, saddr, res;

 	src = pn->sobject;
 	if (target != NULL) {
 		dst = pn_sockaddr_get_object(target);
 		res = pn_sockaddr_get_resource(target);
 	} else {
 		dst = pn->dobject;
 		res = pn->resource;
 	}
 	daddr = pn_addr(dst);

 	err = -EHOSTUNREACH;
 	if (sk->sk_bound_dev_if)
 		dev = dev_get_by_index(net, sk->sk_bound_dev_if);
 	else if (phonet_address_lookup(net, daddr) == 0) {
 		dev = phonet_device_get(net);
 		skb->pkt_type = PACKET_LOOPBACK;
 	} else if (dst == 0) {
 		/* Resource routing (small race until phonet_rcv()) */
 		struct sock *sk = pn_find_sock_by_res(net, res);
 		if (sk)	{
 			sock_put(sk);
 			dev = phonet_device_get(net);
 			skb->pkt_type = PACKET_LOOPBACK;
 		} else
 			dev = phonet_route_output(net, daddr);
 	} else
 		dev = phonet_route_output(net, daddr);

 	if (!dev || !(dev->flags & IFF_UP))
 		goto drop;

 	saddr = phonet_address_get(dev, daddr);
 	if (saddr == PN_NO_ADDR)
 		goto drop;

 	if (!pn_addr(src))
 		src = pn_object(saddr, pn_obj(src));

 	err = pn_send(skb, dev, dst, src, res);
 	dev_put(dev);
 	return err;

 drop:
 	kfree_skb(skb);
 	dev_put(dev);
 	return err;
 }
 EXPORT_SYMBOL(pn_skb_send);

 /* Do not send an error message in response to an error message */
 static inline int can_respond(struct sk_buff *skb)
 {
 	const struct phonethdr *ph;
 	const struct phonetmsg *pm;
 	u8 submsg_id;

 	if (!pskb_may_pull(skb, 3))
 		return 0;

 	ph = pn_hdr(skb);
 	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 		return 0;
 	if (ph->pn_res == PN_COMMGR) /* indications */
 		return 0;

 	ph = pn_hdr(skb); /* re-acquires the pointer */
 	pm = pn_msg(skb);
 	if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 		return 1;
 	submsg_id = (ph->pn_res == PN_PREFIX)
 		? pm->pn_e_submsg_id : pm->pn_submsg_id;
 	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 		pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 		return 1;
 	return 0;
 }

 static int send_obj_unreachable(struct sk_buff *rskb)
 {
 	const struct phonethdr *oph = pn_hdr(rskb);
 	const struct phonetmsg *opm = pn_msg(rskb);
 	struct phonetmsg resp;

 	memset(&resp, 0, sizeof(resp));
 	resp.pn_trans_id = opm->pn_trans_id;
 	resp.pn_msg_id = PN_COMMON_MESSAGE;
 	if (oph->pn_res == PN_PREFIX) {
 		resp.pn_e_res_id = opm->pn_e_res_id;
 		resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 		resp.pn_e_orig_msg_id = opm->pn_msg_id;
 		resp.pn_e_status = 0;
 	} else {
 		resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 		resp.pn_orig_msg_id = opm->pn_msg_id;
 		resp.pn_status = 0;
 	}
 	return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 				pn_object(oph->pn_sdev, oph->pn_sobj),
 				pn_object(oph->pn_rdev, oph->pn_robj),
 				oph->pn_res);
 }

 static int send_reset_indications(struct sk_buff *rskb)
 {
 	struct phonethdr *oph = pn_hdr(rskb);
 	static const u8 data[4] = {
 		0x00 /* trans ID */, 0x10 /* subscribe msg */,
 		0x00 /* subscription count */, 0x00 /* dummy */
 	};

 	return pn_raw_send(data, sizeof(data), rskb->dev,
 				pn_object(oph->pn_sdev, 0x00),
 				pn_object(oph->pn_rdev, oph->pn_robj),
 				PN_COMMGR);
 }


 /* packet type functions */

 /*
  * Stuff received packets to associated sockets.
  * On error, returns non-zero and releases the skb.
  */
 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 			struct packet_type *pkttype,
 			struct net_device *orig_dev)
 {
 	struct net *net = dev_net(dev);
 	struct phonethdr *ph;
 	struct sockaddr_pn sa;
 	u16 len;

 	skb = skb_share_check(skb, GFP_ATOMIC);
 	if (!skb)
 		return NET_RX_DROP;

 	/* check we have at least a full Phonet header */
 	if (!pskb_pull(skb, sizeof(struct phonethdr)))
 		goto out;

 	/* check that the advertised length is correct */
 	ph = pn_hdr(skb);
 	len = get_unaligned_be16(&ph->pn_length);
 	if (len < 2)
 		goto out;
 	len -= 2;
 	if ((len > skb->len) || pskb_trim(skb, len))
 		goto out;
 	skb_reset_transport_header(skb);

 	pn_skb_get_dst_sockaddr(skb, &sa);

 	/* check if this is broadcasted */
 	if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
 		pn_deliver_sock_broadcast(net, skb);
 		goto out;
 	}

 	/* resource routing */
 	if (pn_sockaddr_get_object(&sa) == 0) {
 		struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
 		if (sk)
 			return sk_receive_skb(sk, skb, 0);
 	}

 	/* check if we are the destination */
 	if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
 		/* Phonet packet input */
 		struct sock *sk = pn_find_sock_by_sa(net, &sa);

 		if (sk)
 			return sk_receive_skb(sk, skb, 0);

 		if (can_respond(skb)) {
 			send_obj_unreachable(skb);
 			send_reset_indications(skb);
 		}
 	} else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 		goto out; /* Race between address deletion and loopback */
 	else {
 		/* Phonet packet routing */
 		struct net_device *out_dev;

 		out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
 		if (!out_dev) {
 			net_dbg_ratelimited("No Phonet route to %02X\n",
 					    pn_sockaddr_get_addr(&sa));
 			goto out;
 		}

 		__skb_push(skb, sizeof(struct phonethdr));
 		skb->dev = out_dev;
 		if (out_dev == dev) {
 			net_dbg_ratelimited("Phonet loop to %02X on %s\n",
 					    pn_sockaddr_get_addr(&sa),
 					    dev->name);
 			goto out_dev;
 		}
 		/* Some drivers (e.g. TUN) do not allocate HW header space */
 		if (skb_cow_head(skb, out_dev->hard_header_len))
 			goto out_dev;

 		if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
 					skb->len) < 0)
 			goto out_dev;
 		dev_queue_xmit(skb);
 		dev_put(out_dev);
 		return NET_RX_SUCCESS;
 out_dev:
 		dev_put(out_dev);
 	}

 out:
 	kfree_skb(skb);
 	return NET_RX_DROP;
 }

 static struct packet_type phonet_packet_type __read_mostly = {
 	.type = cpu_to_be16(ETH_P_PHONET),
 	.func = phonet_rcv,
 };

 static DEFINE_MUTEX(proto_tab_lock);

 int __init_or_module phonet_proto_register(unsigned int protocol,
 				const struct phonet_protocol *pp)
 {
 	int err = 0;

 	if (protocol >= PHONET_NPROTO)
 		return -EINVAL;

 	err = proto_register(pp->prot, 1);
 	if (err)
 		return err;

 	mutex_lock(&proto_tab_lock);
 	if (proto_tab[protocol])
 		err = -EBUSY;
 	else
 		rcu_assign_pointer(proto_tab[protocol], pp);
 	mutex_unlock(&proto_tab_lock);

 	return err;
 }
 EXPORT_SYMBOL(phonet_proto_register);

 void phonet_proto_unregister(unsigned int protocol,
 			const struct phonet_protocol *pp)
 {
 	mutex_lock(&proto_tab_lock);
 	BUG_ON(proto_tab[protocol] != pp);
 	RCU_INIT_POINTER(proto_tab[protocol], NULL);
 	mutex_unlock(&proto_tab_lock);
 	synchronize_rcu();
 	proto_unregister(pp->prot);
 }
 EXPORT_SYMBOL(phonet_proto_unregister);

 /* Module registration */
 static int __init phonet_init(void)
 {
 	int err;

 	err = phonet_device_init();
 	if (err)
 		return err;

 	pn_sock_init();
 	err = sock_register(&phonet_proto_family);
 	if (err) {
 		printk(KERN_ALERT
 			"phonet protocol family initialization failed\n");
 		goto err_sock;
 	}

 	dev_add_pack(&phonet_packet_type);
 	phonet_sysctl_init();

 	err = isi_register();
 	if (err)
 		goto err;
 	return 0;

 err:
 	phonet_sysctl_exit();
 	sock_unregister(PF_PHONET);
 	dev_remove_pack(&phonet_packet_type);
 err_sock:
 	phonet_device_exit();
 	return err;
 }

 static void __exit phonet_exit(void)
 {
 	isi_unregister();
 	phonet_sysctl_exit();
 	sock_unregister(PF_PHONET);
 	dev_remove_pack(&phonet_packet_type);
 	phonet_device_exit();
 }

 module_init(phonet_init);
 module_exit(phonet_exit);
 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_NETPROTO(PF_PHONET);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* File: af_phonet.c
	*
	* Phonet protocols family
	*
	* Copyright (C) 2008 Nokia Corporation.
	*
	* Authors: Sakari Ailus <sakari.ailus@nokia.com>
	* Rémi Denis-Courmont
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/unaligned.h>
	#include <net/sock.h>

	#include <linux/if_phonet.h>
	#include <linux/phonet.h>
	#include <net/phonet/phonet.h>
	#include <net/phonet/pn_dev.h>

	/* Transport protocol registration */
	static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;

	static const struct phonet_protocol *phonet_proto_get(unsigned int protocol)
	{
	const struct phonet_protocol *pp;

	if (protocol >= PHONET_NPROTO)
	return NULL;

	rcu_read_lock();
	pp = rcu_dereference(proto_tab[protocol]);
	if (pp && !try_module_get(pp->prot->owner))
	pp = NULL;
	rcu_read_unlock();

	return pp;
	}

	static inline void phonet_proto_put(const struct phonet_protocol *pp)
	{
	module_put(pp->prot->owner);
	}

	/* protocol family functions */

	static int pn_socket_create(struct net net, struct socket sock, int protocol,
	int kern)
	{
	struct sock *sk;
	struct pn_sock *pn;
	const struct phonet_protocol *pnp;
	int err;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;

	if (protocol == 0) {
	/* Default protocol selection */
	switch (sock->type) {
	case SOCK_DGRAM:
	protocol = PN_PROTO_PHONET;
	break;
	case SOCK_SEQPACKET:
	protocol = PN_PROTO_PIPE;
	break;
	default:
	return -EPROTONOSUPPORT;
	}
	}

	pnp = phonet_proto_get(protocol);
	if (pnp == NULL &&
	request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
	pnp = phonet_proto_get(protocol);

	if (pnp == NULL)
	return -EPROTONOSUPPORT;
	if (sock->type != pnp->sock_type) {
	err = -EPROTONOSUPPORT;
	goto out;
	}

	sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot, kern);
	if (sk == NULL) {
	err = -ENOMEM;
	goto out;
	}

	sock_init_data(sock, sk);
	sock->state = SS_UNCONNECTED;
	sock->ops = pnp->ops;
	sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
	sk->sk_protocol = protocol;
	pn = pn_sk(sk);
	pn->sobject = 0;
	pn->dobject = 0;
	pn->resource = 0;
	sk->sk_prot->init(sk);
	err = 0;

	out:
	phonet_proto_put(pnp);
	return err;
	}

	static const struct net_proto_family phonet_proto_family = {
	.family = PF_PHONET,
	.create = pn_socket_create,
	.owner = THIS_MODULE,
	};

	/* Phonet device header operations */
	static int pn_header_create(struct sk_buff skb, struct net_device dev,
	unsigned short type, const void *daddr,
	const void *saddr, unsigned int len)
	{
	u8 *media = skb_push(skb, 1);

	if (type != ETH_P_PHONET)
	return -1;

	if (!saddr)
	saddr = dev->dev_addr;
	media = (const u8 *)saddr;
	return 1;
	}

	static int pn_header_parse(const struct sk_buff skb, unsigned char haddr)
	{
	const u8 *media = skb_mac_header(skb);
	haddr = media;
	return 1;
	}

	const struct header_ops phonet_header_ops = {
	.create = pn_header_create,
	.parse = pn_header_parse,
	};
	EXPORT_SYMBOL(phonet_header_ops);

	/*
	* Prepends an ISI header and sends a datagram.
	*/
	static int pn_send(struct sk_buff skb, struct net_device dev,
	u16 dst, u16 src, u8 res)
	{
	struct phonethdr *ph;
	int err;

	if (skb->len + 2 > 0xffff /* Phonet length field limit */ \|\|
	skb->len + sizeof(struct phonethdr) > dev->mtu) {
	err = -EMSGSIZE;
	goto drop;
	}

	/* Broadcast sending is not implemented */
	if (pn_addr(dst) == PNADDR_BROADCAST) {
	err = -EOPNOTSUPP;
	goto drop;
	}

	skb_reset_transport_header(skb);
	WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
	skb_push(skb, sizeof(struct phonethdr));
	skb_reset_network_header(skb);
	ph = pn_hdr(skb);
	ph->pn_rdev = pn_dev(dst);
	ph->pn_sdev = pn_dev(src);
	ph->pn_res = res;
	ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
	ph->pn_robj = pn_obj(dst);
	ph->pn_sobj = pn_obj(src);

	skb->protocol = htons(ETH_P_PHONET);
	skb->priority = 0;
	skb->dev = dev;

	if (skb->pkt_type == PACKET_LOOPBACK) {
	skb_reset_mac_header(skb);
	skb_orphan(skb);
	err = netif_rx(skb) ? -ENOBUFS : 0;
	} else {
	err = dev_hard_header(skb, dev, ntohs(skb->protocol),
	NULL, NULL, skb->len);
	if (err < 0) {
	err = -EHOSTUNREACH;
	goto drop;
	}
	err = dev_queue_xmit(skb);
	if (unlikely(err > 0))
	err = net_xmit_errno(err);
	}

	return err;
	drop:
	kfree_skb(skb);
	return err;
	}

	static int pn_raw_send(const void data, int len, struct net_device dev,
	u16 dst, u16 src, u8 res)
	{
	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
	if (skb == NULL)
	return -ENOMEM;

	if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
	skb->pkt_type = PACKET_LOOPBACK;

	skb_reserve(skb, MAX_PHONET_HEADER);
	__skb_put(skb, len);
	skb_copy_to_linear_data(skb, data, len);
	return pn_send(skb, dev, dst, src, res);
	}

	/*
	* Create a Phonet header for the skb and send it out. Returns
	* non-zero error code if failed. The skb is freed then.
	*/
	int pn_skb_send(struct sock sk, struct sk_buff skb,
	const struct sockaddr_pn *target)
	{
	struct net *net = sock_net(sk);
	struct net_device *dev;
	struct pn_sock *pn = pn_sk(sk);
	int err;
	u16 src, dst;
	u8 daddr, saddr, res;

	src = pn->sobject;
	if (target != NULL) {
	dst = pn_sockaddr_get_object(target);
	res = pn_sockaddr_get_resource(target);
	} else {
	dst = pn->dobject;
	res = pn->resource;
	}
	daddr = pn_addr(dst);

	err = -EHOSTUNREACH;
	if (sk->sk_bound_dev_if)
	dev = dev_get_by_index(net, sk->sk_bound_dev_if);
	else if (phonet_address_lookup(net, daddr) == 0) {
	dev = phonet_device_get(net);
	skb->pkt_type = PACKET_LOOPBACK;
	} else if (dst == 0) {
	/* Resource routing (small race until phonet_rcv()) */
	struct sock *sk = pn_find_sock_by_res(net, res);
	if (sk) {
	sock_put(sk);
	dev = phonet_device_get(net);
	skb->pkt_type = PACKET_LOOPBACK;
	} else
	dev = phonet_route_output(net, daddr);
	} else
	dev = phonet_route_output(net, daddr);

	if (!dev \|\| !(dev->flags & IFF_UP))
	goto drop;

	saddr = phonet_address_get(dev, daddr);
	if (saddr == PN_NO_ADDR)
	goto drop;

	if (!pn_addr(src))
	src = pn_object(saddr, pn_obj(src));

	err = pn_send(skb, dev, dst, src, res);
	dev_put(dev);
	return err;

	drop:
	kfree_skb(skb);
	dev_put(dev);
	return err;
	}
	EXPORT_SYMBOL(pn_skb_send);

	/* Do not send an error message in response to an error message */
	static inline int can_respond(struct sk_buff *skb)
	{
	const struct phonethdr *ph;
	const struct phonetmsg *pm;
	u8 submsg_id;

	if (!pskb_may_pull(skb, 3))
	return 0;

	ph = pn_hdr(skb);
	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
	return 0;
	if (ph->pn_res == PN_COMMGR) /* indications */
	return 0;

	ph = pn_hdr(skb); /* re-acquires the pointer */
	pm = pn_msg(skb);
	if (pm->pn_msg_id != PN_COMMON_MESSAGE)
	return 1;
	submsg_id = (ph->pn_res == PN_PREFIX)
	? pm->pn_e_submsg_id : pm->pn_submsg_id;
	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
	pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
	return 1;
	return 0;
	}

	static int send_obj_unreachable(struct sk_buff *rskb)
	{
	const struct phonethdr *oph = pn_hdr(rskb);
	const struct phonetmsg *opm = pn_msg(rskb);
	struct phonetmsg resp;

	memset(&resp, 0, sizeof(resp));
	resp.pn_trans_id = opm->pn_trans_id;
	resp.pn_msg_id = PN_COMMON_MESSAGE;
	if (oph->pn_res == PN_PREFIX) {
	resp.pn_e_res_id = opm->pn_e_res_id;
	resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
	resp.pn_e_orig_msg_id = opm->pn_msg_id;
	resp.pn_e_status = 0;
	} else {
	resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
	resp.pn_orig_msg_id = opm->pn_msg_id;
	resp.pn_status = 0;
	}
	return pn_raw_send(&resp, sizeof(resp), rskb->dev,
	pn_object(oph->pn_sdev, oph->pn_sobj),
	pn_object(oph->pn_rdev, oph->pn_robj),
	oph->pn_res);
	}

	static int send_reset_indications(struct sk_buff *rskb)
	{
	struct phonethdr *oph = pn_hdr(rskb);
	static const u8 data[4] = {
	0x00 /* trans ID /, 0x10 / subscribe msg */,
	0x00 /* subscription count /, 0x00 / dummy */
	};

	return pn_raw_send(data, sizeof(data), rskb->dev,
	pn_object(oph->pn_sdev, 0x00),
	pn_object(oph->pn_rdev, oph->pn_robj),
	PN_COMMGR);
	}


	/* packet type functions */

	/*
	* Stuff received packets to associated sockets.
	* On error, returns non-zero and releases the skb.
	*/
	static int phonet_rcv(struct sk_buff skb, struct net_device dev,
	struct packet_type *pkttype,
	struct net_device *orig_dev)
	{
	struct net *net = dev_net(dev);
	struct phonethdr *ph;
	struct sockaddr_pn sa;
	u16 len;

	skb = skb_share_check(skb, GFP_ATOMIC);
	if (!skb)
	return NET_RX_DROP;

	/* check we have at least a full Phonet header */
	if (!pskb_pull(skb, sizeof(struct phonethdr)))
	goto out;

	/* check that the advertised length is correct */
	ph = pn_hdr(skb);
	len = get_unaligned_be16(&ph->pn_length);
	if (len < 2)
	goto out;
	len -= 2;
	if ((len > skb->len) \|\| pskb_trim(skb, len))
	goto out;
	skb_reset_transport_header(skb);

	pn_skb_get_dst_sockaddr(skb, &sa);

	/* check if this is broadcasted */
	if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
	pn_deliver_sock_broadcast(net, skb);
	goto out;
	}

	/* resource routing */
	if (pn_sockaddr_get_object(&sa) == 0) {
	struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
	if (sk)
	return sk_receive_skb(sk, skb, 0);
	}

	/* check if we are the destination */
	if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
	/* Phonet packet input */
	struct sock *sk = pn_find_sock_by_sa(net, &sa);

	if (sk)
	return sk_receive_skb(sk, skb, 0);

	if (can_respond(skb)) {
	send_obj_unreachable(skb);
	send_reset_indications(skb);
	}
	} else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
	goto out; /* Race between address deletion and loopback */
	else {
	/* Phonet packet routing */
	struct net_device *out_dev;

	out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
	if (!out_dev) {
	net_dbg_ratelimited("No Phonet route to %02X\n",
	pn_sockaddr_get_addr(&sa));
	goto out;
	}

	__skb_push(skb, sizeof(struct phonethdr));
	skb->dev = out_dev;
	if (out_dev == dev) {
	net_dbg_ratelimited("Phonet loop to %02X on %s\n",
	pn_sockaddr_get_addr(&sa),
	dev->name);
	goto out_dev;
	}
	/* Some drivers (e.g. TUN) do not allocate HW header space */
	if (skb_cow_head(skb, out_dev->hard_header_len))
	goto out_dev;

	if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
	skb->len) < 0)
	goto out_dev;
	dev_queue_xmit(skb);
	dev_put(out_dev);
	return NET_RX_SUCCESS;
	out_dev:
	dev_put(out_dev);
	}

	out:
	kfree_skb(skb);
	return NET_RX_DROP;
	}

	static struct packet_type phonet_packet_type __read_mostly = {
	.type = cpu_to_be16(ETH_P_PHONET),
	.func = phonet_rcv,
	};

	static DEFINE_MUTEX(proto_tab_lock);

	int __init_or_module phonet_proto_register(unsigned int protocol,
	const struct phonet_protocol *pp)
	{
	int err = 0;

	if (protocol >= PHONET_NPROTO)
	return -EINVAL;

	err = proto_register(pp->prot, 1);
	if (err)
	return err;

	mutex_lock(&proto_tab_lock);
	if (proto_tab[protocol])
	err = -EBUSY;
	else
	rcu_assign_pointer(proto_tab[protocol], pp);
	mutex_unlock(&proto_tab_lock);

	return err;
	}
	EXPORT_SYMBOL(phonet_proto_register);

	void phonet_proto_unregister(unsigned int protocol,
	const struct phonet_protocol *pp)
	{
	mutex_lock(&proto_tab_lock);
	BUG_ON(proto_tab[protocol] != pp);
	RCU_INIT_POINTER(proto_tab[protocol], NULL);
	mutex_unlock(&proto_tab_lock);
	synchronize_rcu();
	proto_unregister(pp->prot);
	}
	EXPORT_SYMBOL(phonet_proto_unregister);

	/* Module registration */
	static int __init phonet_init(void)
	{
	int err;

	err = phonet_device_init();
	if (err)
	return err;

	pn_sock_init();
	err = sock_register(&phonet_proto_family);
	if (err) {
	printk(KERN_ALERT
	"phonet protocol family initialization failed\n");
	goto err_sock;
	}

	dev_add_pack(&phonet_packet_type);
	phonet_sysctl_init();

	err = isi_register();
	if (err)
	goto err;
	return 0;

	err:
	phonet_sysctl_exit();
	sock_unregister(PF_PHONET);
	dev_remove_pack(&phonet_packet_type);
	err_sock:
	phonet_device_exit();
	return err;
	}

	static void __exit phonet_exit(void)
	{
	isi_unregister();
	phonet_sysctl_exit();
	sock_unregister(PF_PHONET);
	dev_remove_pack(&phonet_packet_type);
	phonet_device_exit();
	}

	module_init(phonet_init);
	module_exit(phonet_exit);
	MODULE_DESCRIPTION("Phonet protocol stack for Linux");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS_NETPROTO(PF_PHONET);