Phonet: PF_PHONET protocol family support

/*

 * File: af_phonet.h

 *

 * Phonet sockets kernel definitions

 *

 * Copyright (C) 2008 Nokia Corporation.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * version 2 as published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

 * 02110-1301 USA

 */

#ifndef AF_PHONET_H

#define AF_PHONET_H

/*

 * The lower layers may not require more space, ever. Make sure it's

 * enough.

 */

#define MAX_PHONET_HEADER	8

static inline struct phonethdr *pn_hdr(struct sk_buff *skb)

{

	return (struct phonethdr *)skb_network_header(skb);

}

/*

 * Get the other party's sockaddr from received skb. The skb begins

 * with a Phonet header.

 */

static inline

void pn_skb_get_src_sockaddr(struct sk_buff *skb, struct sockaddr_pn *sa)

{

	struct phonethdr *ph = pn_hdr(skb);

	u16 obj = pn_object(ph->pn_sdev, ph->pn_sobj);

	sa->spn_family = AF_PHONET;

	pn_sockaddr_set_object(sa, obj);

	pn_sockaddr_set_resource(sa, ph->pn_res);

	memset(sa->spn_zero, 0, sizeof(sa->spn_zero));

}

static inline

void pn_skb_get_dst_sockaddr(struct sk_buff *skb, struct sockaddr_pn *sa)

{

	struct phonethdr *ph = pn_hdr(skb);

	u16 obj = pn_object(ph->pn_rdev, ph->pn_robj);

	sa->spn_family = AF_PHONET;

	pn_sockaddr_set_object(sa, obj);

	pn_sockaddr_set_resource(sa, ph->pn_res);

	memset(sa->spn_zero, 0, sizeof(sa->spn_zero));

}

/* Protocols in Phonet protocol family. */

struct phonet_protocol {

	struct proto		*prot;

	int			sock_type;

};

int phonet_proto_register(int protocol, struct phonet_protocol *pp);

void phonet_proto_unregister(int protocol, struct phonet_protocol *pp);

#endif

/*

 * File: af_phonet.c

 *

 * Phonet protocols family

 *

 * Copyright (C) 2008 Nokia Corporation.

 *

 * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>

 * Original author: Sakari Ailus <sakari.ailus@nokia.com>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * version 2 as published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

 * 02110-1301 USA

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <asm/unaligned.h>

#include <net/sock.h>

#include <linux/if_phonet.h>

#include <linux/phonet.h>

#include <net/phonet/phonet.h>

static struct net_proto_family phonet_proto_family;

static struct phonet_protocol *phonet_proto_get(int protocol);

static inline void phonet_proto_put(struct phonet_protocol *pp);

/* protocol family functions */

static int pn_socket_create(struct net *net, struct socket *sock, int protocol)

{

	struct phonet_protocol *pnp;

	int err;

	if (net != &init_net)

		return -EAFNOSUPPORT;

	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;

	if (protocol == 0) {

		/* Default protocol selection */

		switch (sock->type) {

		case SOCK_DGRAM:

			protocol = PN_PROTO_PHONET;

			break;

		default:

			return -EPROTONOSUPPORT;

		}

	}

	pnp = phonet_proto_get(protocol);

	if (pnp == NULL)

		return -EPROTONOSUPPORT;

	if (sock->type != pnp->sock_type) {

		err = -EPROTONOSUPPORT;

		goto out;

	}

	/* TODO: create and init the struct sock */

	err = -EPROTONOSUPPORT;

out:

	phonet_proto_put(pnp);

	return err;

}

static struct net_proto_family phonet_proto_family = {

	.family = AF_PHONET,

	.create = pn_socket_create,

	.owner = THIS_MODULE,

};

/* 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 phonethdr *ph;

	struct sockaddr_pn sa;

	u16 len;

	if (dev_net(dev) != &init_net)

		goto out;

	/* 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);

	if (pn_sockaddr_get_addr(&sa) == 0)

		goto out; /* currently, we cannot be device 0 */

	/* TODO: put packets to sockets backlog */

out:

	kfree_skb(skb);

	return NET_RX_DROP;

}

static struct packet_type phonet_packet_type = {

	.type = __constant_htons(ETH_P_PHONET),

	.dev = NULL,

	.func = phonet_rcv,

};

/* Transport protocol registration */

static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;

static DEFINE_SPINLOCK(proto_tab_lock);

int __init_or_module phonet_proto_register(int protocol,

						struct phonet_protocol *pp)

{

	int err = 0;

	if (protocol >= PHONET_NPROTO)

		return -EINVAL;

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

	if (err)

		return err;

	spin_lock(&proto_tab_lock);

	if (proto_tab[protocol])

		err = -EBUSY;

	else

		proto_tab[protocol] = pp;

	spin_unlock(&proto_tab_lock);

	return err;

}

EXPORT_SYMBOL(phonet_proto_register);

void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)

{

	spin_lock(&proto_tab_lock);

	BUG_ON(proto_tab[protocol] != pp);

	proto_tab[protocol] = NULL;

	spin_unlock(&proto_tab_lock);

	proto_unregister(pp->prot);

}

EXPORT_SYMBOL(phonet_proto_unregister);

static struct phonet_protocol *phonet_proto_get(int protocol)

{

	struct phonet_protocol *pp;

	if (protocol >= PHONET_NPROTO)

		return NULL;

	spin_lock(&proto_tab_lock);

	pp = proto_tab[protocol];

	if (pp && !try_module_get(pp->prot->owner))

		pp = NULL;

	spin_unlock(&proto_tab_lock);

	return pp;

}

static inline void phonet_proto_put(struct phonet_protocol *pp)

{

	module_put(pp->prot->owner);

}

/* Module registration */

static int __init phonet_init(void)

{

	int err;

	err = sock_register(&phonet_proto_family);

	if (err) {

		printk(KERN_ALERT

			"phonet protocol family initialization failed\n");

		return err;

	}

	dev_add_pack(&phonet_packet_type);

	return 0;

}

static void __exit phonet_exit(void)

{

	sock_unregister(AF_PHONET);

	dev_remove_pack(&phonet_packet_type);

}

module_init(phonet_init);

module_exit(phonet_exit);

MODULE_DESCRIPTION("Phonet protocol stack for Linux");

MODULE_LICENSE("GPL");