drivers/connector/connector.c - linux - Git at Google

 /*
  *	connector.c
  *
  * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
  * All rights reserved.
  *
  * 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.
  *
  * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/list.h>
 #include <linux/skbuff.h>
 #include <linux/netlink.h>
 #include <linux/moduleparam.h>
 #include <linux/connector.h>
 #include <linux/slab.h>
 #include <linux/mutex.h>
 #include <linux/proc_fs.h>
 #include <linux/spinlock.h>

 #include <net/sock.h>

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);

 static struct cn_dev cdev;

 static int cn_already_initialized;

 /*
  * msg->seq and msg->ack are used to determine message genealogy.
  * When someone sends message it puts there locally unique sequence
  * and random acknowledge numbers.  Sequence number may be copied into
  * nlmsghdr->nlmsg_seq too.
  *
  * Sequence number is incremented with each message to be sent.
  *
  * If we expect reply to our message then the sequence number in
  * received message MUST be the same as in original message, and
  * acknowledge number MUST be the same + 1.
  *
  * If we receive a message and its sequence number is not equal to the
  * one we are expecting then it is a new message.
  *
  * If we receive a message and its sequence number is the same as one
  * we are expecting but it's acknowledgement number is not equal to
  * the acknowledgement number in the original message + 1, then it is
  * a new message.
  *
  */
 int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
 {
 	struct cn_callback_entry *__cbq;
 	unsigned int size;
 	struct sk_buff *skb;
 	struct nlmsghdr *nlh;
 	struct cn_msg *data;
 	struct cn_dev *dev = &cdev;
 	u32 group = 0;
 	int found = 0;

 	if (!__group) {
 		spin_lock_bh(&dev->cbdev->queue_lock);
 		list_for_each_entry(__cbq, &dev->cbdev->queue_list,
 				    callback_entry) {
 			if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
 				found = 1;
 				group = __cbq->group;
 				break;
 			}
 		}
 		spin_unlock_bh(&dev->cbdev->queue_lock);

 		if (!found)
 			return -ENODEV;
 	} else {
 		group = __group;
 	}

 	if (!netlink_has_listeners(dev->nls, group))
 		return -ESRCH;

 	size = NLMSG_SPACE(sizeof(*msg) + msg->len);

 	skb = alloc_skb(size, gfp_mask);
 	if (!skb)
 		return -ENOMEM;

 	nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh), 0);
 	if (!nlh) {
 		kfree_skb(skb);
 		return -EMSGSIZE;
 	}

 	data = nlmsg_data(nlh);

 	memcpy(data, msg, sizeof(*data) + msg->len);

 	NETLINK_CB(skb).dst_group = group;

 	return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
 }
 EXPORT_SYMBOL_GPL(cn_netlink_send);

 /*
  * Callback helper - queues work and setup destructor for given data.
  */
 static int cn_call_callback(struct sk_buff *skb)
 {
 	struct cn_callback_entry *i, *cbq = NULL;
 	struct cn_dev *dev = &cdev;
 	struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb));
 	struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
 	int err = -ENODEV;

 	spin_lock_bh(&dev->cbdev->queue_lock);
 	list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
 		if (cn_cb_equal(&i->id.id, &msg->id)) {
 			atomic_inc(&i->refcnt);
 			cbq = i;
 			break;
 		}
 	}
 	spin_unlock_bh(&dev->cbdev->queue_lock);

 	if (cbq != NULL) {
 		err = 0;
 		cbq->callback(msg, nsp);
 		kfree_skb(skb);
 		cn_queue_release_callback(cbq);
 		err = 0;
 	}

 	return err;
 }

 /*
  * Main netlink receiving function.
  *
  * It checks skb, netlink header and msg sizes, and calls callback helper.
  */
 static void cn_rx_skb(struct sk_buff *__skb)
 {
 	struct nlmsghdr *nlh;
 	int err;
 	struct sk_buff *skb;

 	skb = skb_get(__skb);

 	if (skb->len >= NLMSG_SPACE(0)) {
 		nlh = nlmsg_hdr(skb);

 		if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
 		    skb->len < nlh->nlmsg_len ||
 		    nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
 			kfree_skb(skb);
 			return;
 		}

 		err = cn_call_callback(skb);
 		if (err < 0)
 			kfree_skb(skb);
 	}
 }

 /*
  * Callback add routing - adds callback with given ID and name.
  * If there is registered callback with the same ID it will not be added.
  *
  * May sleep.
  */
 int cn_add_callback(struct cb_id *id, const char *name,
 		    void (*callback)(struct cn_msg *,
 				     struct netlink_skb_parms *))
 {
 	int err;
 	struct cn_dev *dev = &cdev;

 	if (!cn_already_initialized)
 		return -EAGAIN;

 	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
 	if (err)
 		return err;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(cn_add_callback);

 /*
  * Callback remove routing - removes callback
  * with given ID.
  * If there is no registered callback with given
  * ID nothing happens.
  *
  * May sleep while waiting for reference counter to become zero.
  */
 void cn_del_callback(struct cb_id *id)
 {
 	struct cn_dev *dev = &cdev;

 	cn_queue_del_callback(dev->cbdev, id);
 }
 EXPORT_SYMBOL_GPL(cn_del_callback);

 static int cn_proc_show(struct seq_file *m, void *v)
 {
 	struct cn_queue_dev *dev = cdev.cbdev;
 	struct cn_callback_entry *cbq;

 	seq_printf(m, "Name            ID\n");

 	spin_lock_bh(&dev->queue_lock);

 	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
 		seq_printf(m, "%-15s %u:%u\n",
 			   cbq->id.name,
 			   cbq->id.id.idx,
 			   cbq->id.id.val);
 	}

 	spin_unlock_bh(&dev->queue_lock);

 	return 0;
 }

 static int cn_proc_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, cn_proc_show, NULL);
 }

 static const struct file_operations cn_file_ops = {
 	.owner   = THIS_MODULE,
 	.open    = cn_proc_open,
 	.read    = seq_read,
 	.llseek  = seq_lseek,
 	.release = single_release
 };

 static struct cn_dev cdev = {
 	.input   = cn_rx_skb,
 };

 static int cn_init(void)
 {
 	struct cn_dev *dev = &cdev;
 	struct netlink_kernel_cfg cfg = {
 		.groups	= CN_NETLINK_USERS + 0xf,
 		.input	= dev->input,
 	};

 	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
 	if (!dev->nls)
 		return -EIO;

 	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
 	if (!dev->cbdev) {
 		netlink_kernel_release(dev->nls);
 		return -EINVAL;
 	}

 	cn_already_initialized = 1;

 	proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops);

 	return 0;
 }

 static void cn_fini(void)
 {
 	struct cn_dev *dev = &cdev;

 	cn_already_initialized = 0;

 	proc_net_remove(&init_net, "connector");

 	cn_queue_free_dev(dev->cbdev);
 	netlink_kernel_release(dev->nls);
 }

 subsys_initcall(cn_init);
 module_exit(cn_fini);
	/*
	* connector.c
	*
	* 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
	* All rights reserved.
	*
	* 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.
	*
	* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/list.h>
	#include <linux/skbuff.h>
	#include <linux/netlink.h>
	#include <linux/moduleparam.h>
	#include <linux/connector.h>
	#include <linux/slab.h>
	#include <linux/mutex.h>
	#include <linux/proc_fs.h>
	#include <linux/spinlock.h>

	#include <net/sock.h>

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
	MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
	MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);

	static struct cn_dev cdev;

	static int cn_already_initialized;

	/*
	* msg->seq and msg->ack are used to determine message genealogy.
	* When someone sends message it puts there locally unique sequence
	* and random acknowledge numbers. Sequence number may be copied into
	* nlmsghdr->nlmsg_seq too.
	*
	* Sequence number is incremented with each message to be sent.
	*
	* If we expect reply to our message then the sequence number in
	* received message MUST be the same as in original message, and
	* acknowledge number MUST be the same + 1.
	*
	* If we receive a message and its sequence number is not equal to the
	* one we are expecting then it is a new message.
	*
	* If we receive a message and its sequence number is the same as one
	* we are expecting but it's acknowledgement number is not equal to
	* the acknowledgement number in the original message + 1, then it is
	* a new message.
	*
	*/
	int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
	{
	struct cn_callback_entry *__cbq;
	unsigned int size;
	struct sk_buff *skb;
	struct nlmsghdr *nlh;
	struct cn_msg *data;
	struct cn_dev *dev = &cdev;
	u32 group = 0;
	int found = 0;

	if (!__group) {
	spin_lock_bh(&dev->cbdev->queue_lock);
	list_for_each_entry(__cbq, &dev->cbdev->queue_list,
	callback_entry) {
	if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
	found = 1;
	group = __cbq->group;
	break;
	}
	}
	spin_unlock_bh(&dev->cbdev->queue_lock);

	if (!found)
	return -ENODEV;
	} else {
	group = __group;
	}

	if (!netlink_has_listeners(dev->nls, group))
	return -ESRCH;

	size = NLMSG_SPACE(sizeof(*msg) + msg->len);

	skb = alloc_skb(size, gfp_mask);
	if (!skb)
	return -ENOMEM;

	nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh), 0);
	if (!nlh) {
	kfree_skb(skb);
	return -EMSGSIZE;
	}

	data = nlmsg_data(nlh);

	memcpy(data, msg, sizeof(*data) + msg->len);

	NETLINK_CB(skb).dst_group = group;

	return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
	}
	EXPORT_SYMBOL_GPL(cn_netlink_send);

	/*
	* Callback helper - queues work and setup destructor for given data.
	*/
	static int cn_call_callback(struct sk_buff *skb)
	{
	struct cn_callback_entry i, cbq = NULL;
	struct cn_dev *dev = &cdev;
	struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb));
	struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
	int err = -ENODEV;

	spin_lock_bh(&dev->cbdev->queue_lock);
	list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
	if (cn_cb_equal(&i->id.id, &msg->id)) {
	atomic_inc(&i->refcnt);
	cbq = i;
	break;
	}
	}
	spin_unlock_bh(&dev->cbdev->queue_lock);

	if (cbq != NULL) {
	err = 0;
	cbq->callback(msg, nsp);
	kfree_skb(skb);
	cn_queue_release_callback(cbq);
	err = 0;
	}

	return err;
	}

	/*
	* Main netlink receiving function.
	*
	* It checks skb, netlink header and msg sizes, and calls callback helper.
	*/
	static void cn_rx_skb(struct sk_buff *__skb)
	{
	struct nlmsghdr *nlh;
	int err;
	struct sk_buff *skb;

	skb = skb_get(__skb);

	if (skb->len >= NLMSG_SPACE(0)) {
	nlh = nlmsg_hdr(skb);

	if (nlh->nlmsg_len < sizeof(struct cn_msg) \|\|
	skb->len < nlh->nlmsg_len \|\|
	nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
	kfree_skb(skb);
	return;
	}

	err = cn_call_callback(skb);
	if (err < 0)
	kfree_skb(skb);
	}
	}

	/*
	* Callback add routing - adds callback with given ID and name.
	* If there is registered callback with the same ID it will not be added.
	*
	* May sleep.
	*/
	int cn_add_callback(struct cb_id id, const char name,
	void (callback)(struct cn_msg ,
	struct netlink_skb_parms *))
	{
	int err;
	struct cn_dev *dev = &cdev;

	if (!cn_already_initialized)
	return -EAGAIN;

	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
	if (err)
	return err;

	return 0;
	}
	EXPORT_SYMBOL_GPL(cn_add_callback);

	/*
	* Callback remove routing - removes callback
	* with given ID.
	* If there is no registered callback with given
	* ID nothing happens.
	*
	* May sleep while waiting for reference counter to become zero.
	*/
	void cn_del_callback(struct cb_id *id)
	{
	struct cn_dev *dev = &cdev;

	cn_queue_del_callback(dev->cbdev, id);
	}
	EXPORT_SYMBOL_GPL(cn_del_callback);

	static int cn_proc_show(struct seq_file m, void v)
	{
	struct cn_queue_dev *dev = cdev.cbdev;
	struct cn_callback_entry *cbq;

	seq_printf(m, "Name ID\n");

	spin_lock_bh(&dev->queue_lock);

	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
	seq_printf(m, "%-15s %u:%u\n",
	cbq->id.name,
	cbq->id.id.idx,
	cbq->id.id.val);
	}

	spin_unlock_bh(&dev->queue_lock);

	return 0;
	}

	static int cn_proc_open(struct inode inode, struct file file)
	{
	return single_open(file, cn_proc_show, NULL);
	}

	static const struct file_operations cn_file_ops = {
	.owner = THIS_MODULE,
	.open = cn_proc_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release
	};

	static struct cn_dev cdev = {
	.input = cn_rx_skb,
	};

	static int cn_init(void)
	{
	struct cn_dev *dev = &cdev;
	struct netlink_kernel_cfg cfg = {
	.groups = CN_NETLINK_USERS + 0xf,
	.input = dev->input,
	};

	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
	if (!dev->nls)
	return -EIO;

	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
	if (!dev->cbdev) {
	netlink_kernel_release(dev->nls);
	return -EINVAL;
	}

	cn_already_initialized = 1;

	proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops);

	return 0;
	}

	static void cn_fini(void)
	{
	struct cn_dev *dev = &cdev;

	cn_already_initialized = 0;

	proc_net_remove(&init_net, "connector");

	cn_queue_free_dev(dev->cbdev);
	netlink_kernel_release(dev->nls);
	}

	subsys_initcall(cn_init);
	module_exit(cn_fini);