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

 /*
  * cn_proc.c - process events connector
  *
  * Copyright (C) Matt Helsley, IBM Corp. 2005
  * Based on cn_fork.c by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
  * Original copyright notice follows:
  * Copyright (C) 2005 BULL SA.
  *
  *
  * 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/module.h>
 #include <linux/kernel.h>
 #include <linux/ktime.h>
 #include <linux/init.h>
 #include <linux/connector.h>
 #include <linux/gfp.h>
 #include <linux/ptrace.h>
 #include <linux/atomic.h>

 #include <asm/unaligned.h>

 #include <linux/cn_proc.h>

 #define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event))

 static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
 static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };

 /* proc_event_counts is used as the sequence number of the netlink message */
 static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };

 static inline void get_seq(__u32 *ts, int *cpu)
 {
 	preempt_disable();
 	*ts = __this_cpu_inc_return(proc_event_counts) -1;
 	*cpu = smp_processor_id();
 	preempt_enable();
 }

 void proc_fork_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
 	struct timespec ts;
 	struct task_struct *parent;

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
 	ev->what = PROC_EVENT_FORK;
 	rcu_read_lock();
 	parent = rcu_dereference(task->real_parent);
 	ev->event_data.fork.parent_pid = parent->pid;
 	ev->event_data.fork.parent_tgid = parent->tgid;
 	rcu_read_unlock();
 	ev->event_data.fork.child_pid = task->pid;
 	ev->event_data.fork.child_tgid = task->tgid;

 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
 	msg->len = sizeof(*ev);
 	/*  If cn_netlink_send() failed, the data is not sent */
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 void proc_exec_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	struct timespec ts;
 	__u8 buffer[CN_PROC_MSG_SIZE];

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
 	ev->what = PROC_EVENT_EXEC;
 	ev->event_data.exec.process_pid = task->pid;
 	ev->event_data.exec.process_tgid = task->tgid;

 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
 	msg->len = sizeof(*ev);
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 void proc_id_connector(struct task_struct *task, int which_id)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
 	struct timespec ts;
 	const struct cred *cred;

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	ev->what = which_id;
 	ev->event_data.id.process_pid = task->pid;
 	ev->event_data.id.process_tgid = task->tgid;
 	rcu_read_lock();
 	cred = __task_cred(task);
 	if (which_id == PROC_EVENT_UID) {
 		ev->event_data.id.r.ruid = cred->uid;
 		ev->event_data.id.e.euid = cred->euid;
 	} else if (which_id == PROC_EVENT_GID) {
 		ev->event_data.id.r.rgid = cred->gid;
 		ev->event_data.id.e.egid = cred->egid;
 	} else {
 		rcu_read_unlock();
 	     	return;
 	}
 	rcu_read_unlock();
 	get_seq(&msg->seq, &ev->cpu);
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);

 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
 	msg->len = sizeof(*ev);
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 void proc_sid_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	struct timespec ts;
 	__u8 buffer[CN_PROC_MSG_SIZE];

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg *)buffer;
 	ev = (struct proc_event *)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
 	ev->what = PROC_EVENT_SID;
 	ev->event_data.sid.process_pid = task->pid;
 	ev->event_data.sid.process_tgid = task->tgid;

 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
 	msg->len = sizeof(*ev);
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	struct timespec ts;
 	__u8 buffer[CN_PROC_MSG_SIZE];

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg *)buffer;
 	ev = (struct proc_event *)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
 	ev->what = PROC_EVENT_PTRACE;
 	ev->event_data.ptrace.process_pid  = task->pid;
 	ev->event_data.ptrace.process_tgid = task->tgid;
 	if (ptrace_id == PTRACE_ATTACH) {
 		ev->event_data.ptrace.tracer_pid  = current->pid;
 		ev->event_data.ptrace.tracer_tgid = current->tgid;
 	} else if (ptrace_id == PTRACE_DETACH) {
 		ev->event_data.ptrace.tracer_pid  = 0;
 		ev->event_data.ptrace.tracer_tgid = 0;
 	} else
 		return;

 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
 	msg->len = sizeof(*ev);
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 void proc_comm_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	struct timespec ts;
 	__u8 buffer[CN_PROC_MSG_SIZE];

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg *)buffer;
 	ev = (struct proc_event *)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
 	ev->what = PROC_EVENT_COMM;
 	ev->event_data.comm.process_pid  = task->pid;
 	ev->event_data.comm.process_tgid = task->tgid;
 	get_task_comm(ev->event_data.comm.comm, task);

 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
 	msg->len = sizeof(*ev);
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 void proc_exit_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
 	struct timespec ts;

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
 	ev->what = PROC_EVENT_EXIT;
 	ev->event_data.exit.process_pid = task->pid;
 	ev->event_data.exit.process_tgid = task->tgid;
 	ev->event_data.exit.exit_code = task->exit_code;
 	ev->event_data.exit.exit_signal = task->exit_signal;

 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
 	msg->len = sizeof(*ev);
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 /*
  * Send an acknowledgement message to userspace
  *
  * Use 0 for success, EFOO otherwise.
  * Note: this is the negative of conventional kernel error
  * values because it's not being returned via syscall return
  * mechanisms.
  */
 static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
 	struct timespec ts;

 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;

 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	msg->seq = rcvd_seq;
 	ktime_get_ts(&ts); /* get high res monotonic timestamp */
 	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
 	ev->cpu = -1;
 	ev->what = PROC_EVENT_NONE;
 	ev->event_data.ack.err = err;
 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = rcvd_ack + 1;
 	msg->len = sizeof(*ev);
 	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }

 /**
  * cn_proc_mcast_ctl
  * @data: message sent from userspace via the connector
  */
 static void cn_proc_mcast_ctl(struct cn_msg *msg,
 			      struct netlink_skb_parms *nsp)
 {
 	enum proc_cn_mcast_op *mc_op = NULL;
 	int err = 0;

 	if (msg->len != sizeof(*mc_op))
 		return;

 	mc_op = (enum proc_cn_mcast_op*)msg->data;
 	switch (*mc_op) {
 	case PROC_CN_MCAST_LISTEN:
 		atomic_inc(&proc_event_num_listeners);
 		break;
 	case PROC_CN_MCAST_IGNORE:
 		atomic_dec(&proc_event_num_listeners);
 		break;
 	default:
 		err = EINVAL;
 		break;
 	}
 	cn_proc_ack(err, msg->seq, msg->ack);
 }

 /*
  * cn_proc_init - initialization entry point
  *
  * Adds the connector callback to the connector driver.
  */
 static int __init cn_proc_init(void)
 {
 	int err;

 	if ((err = cn_add_callback(&cn_proc_event_id, "cn_proc",
 	 			   &cn_proc_mcast_ctl))) {
 		printk(KERN_WARNING "cn_proc failed to register\n");
 		return err;
 	}
 	return 0;
 }

 module_init(cn_proc_init);
	/*
	* cn_proc.c - process events connector
	*
	* Copyright (C) Matt Helsley, IBM Corp. 2005
	* Based on cn_fork.c by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
	* Original copyright notice follows:
	* Copyright (C) 2005 BULL SA.
	*
	*
	* 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/module.h>
	#include <linux/kernel.h>
	#include <linux/ktime.h>
	#include <linux/init.h>
	#include <linux/connector.h>
	#include <linux/gfp.h>
	#include <linux/ptrace.h>
	#include <linux/atomic.h>

	#include <asm/unaligned.h>

	#include <linux/cn_proc.h>

	#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event))

	static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
	static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };

	/* proc_event_counts is used as the sequence number of the netlink message */
	static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };

	static inline void get_seq(__u32 ts, int cpu)
	{
	preempt_disable();
	*ts = __this_cpu_inc_return(proc_event_counts) -1;
	*cpu = smp_processor_id();
	preempt_enable();
	}

	void proc_fork_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE];
	struct timespec ts;
	struct task_struct *parent;

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg*)buffer;
	ev = (struct proc_event*)msg->data;
	get_seq(&msg->seq, &ev->cpu);
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
	ev->what = PROC_EVENT_FORK;
	rcu_read_lock();
	parent = rcu_dereference(task->real_parent);
	ev->event_data.fork.parent_pid = parent->pid;
	ev->event_data.fork.parent_tgid = parent->tgid;
	rcu_read_unlock();
	ev->event_data.fork.child_pid = task->pid;
	ev->event_data.fork.child_tgid = task->tgid;

	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = 0; /* not used */
	msg->len = sizeof(*ev);
	/* If cn_netlink_send() failed, the data is not sent */
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	void proc_exec_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	struct timespec ts;
	__u8 buffer[CN_PROC_MSG_SIZE];

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg*)buffer;
	ev = (struct proc_event*)msg->data;
	get_seq(&msg->seq, &ev->cpu);
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
	ev->what = PROC_EVENT_EXEC;
	ev->event_data.exec.process_pid = task->pid;
	ev->event_data.exec.process_tgid = task->tgid;

	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = 0; /* not used */
	msg->len = sizeof(*ev);
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	void proc_id_connector(struct task_struct *task, int which_id)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE];
	struct timespec ts;
	const struct cred *cred;

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg*)buffer;
	ev = (struct proc_event*)msg->data;
	ev->what = which_id;
	ev->event_data.id.process_pid = task->pid;
	ev->event_data.id.process_tgid = task->tgid;
	rcu_read_lock();
	cred = __task_cred(task);
	if (which_id == PROC_EVENT_UID) {
	ev->event_data.id.r.ruid = cred->uid;
	ev->event_data.id.e.euid = cred->euid;
	} else if (which_id == PROC_EVENT_GID) {
	ev->event_data.id.r.rgid = cred->gid;
	ev->event_data.id.e.egid = cred->egid;
	} else {
	rcu_read_unlock();
	return;
	}
	rcu_read_unlock();
	get_seq(&msg->seq, &ev->cpu);
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);

	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = 0; /* not used */
	msg->len = sizeof(*ev);
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	void proc_sid_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	struct timespec ts;
	__u8 buffer[CN_PROC_MSG_SIZE];

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg *)buffer;
	ev = (struct proc_event *)msg->data;
	get_seq(&msg->seq, &ev->cpu);
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
	ev->what = PROC_EVENT_SID;
	ev->event_data.sid.process_pid = task->pid;
	ev->event_data.sid.process_tgid = task->tgid;

	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = 0; /* not used */
	msg->len = sizeof(*ev);
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	struct timespec ts;
	__u8 buffer[CN_PROC_MSG_SIZE];

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg *)buffer;
	ev = (struct proc_event *)msg->data;
	get_seq(&msg->seq, &ev->cpu);
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
	ev->what = PROC_EVENT_PTRACE;
	ev->event_data.ptrace.process_pid = task->pid;
	ev->event_data.ptrace.process_tgid = task->tgid;
	if (ptrace_id == PTRACE_ATTACH) {
	ev->event_data.ptrace.tracer_pid = current->pid;
	ev->event_data.ptrace.tracer_tgid = current->tgid;
	} else if (ptrace_id == PTRACE_DETACH) {
	ev->event_data.ptrace.tracer_pid = 0;
	ev->event_data.ptrace.tracer_tgid = 0;
	} else
	return;

	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = 0; /* not used */
	msg->len = sizeof(*ev);
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	void proc_comm_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	struct timespec ts;
	__u8 buffer[CN_PROC_MSG_SIZE];

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg *)buffer;
	ev = (struct proc_event *)msg->data;
	get_seq(&msg->seq, &ev->cpu);
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
	ev->what = PROC_EVENT_COMM;
	ev->event_data.comm.process_pid = task->pid;
	ev->event_data.comm.process_tgid = task->tgid;
	get_task_comm(ev->event_data.comm.comm, task);

	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = 0; /* not used */
	msg->len = sizeof(*ev);
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	void proc_exit_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE];
	struct timespec ts;

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg*)buffer;
	ev = (struct proc_event*)msg->data;
	get_seq(&msg->seq, &ev->cpu);
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
	ev->what = PROC_EVENT_EXIT;
	ev->event_data.exit.process_pid = task->pid;
	ev->event_data.exit.process_tgid = task->tgid;
	ev->event_data.exit.exit_code = task->exit_code;
	ev->event_data.exit.exit_signal = task->exit_signal;

	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = 0; /* not used */
	msg->len = sizeof(*ev);
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	/*
	* Send an acknowledgement message to userspace
	*
	* Use 0 for success, EFOO otherwise.
	* Note: this is the negative of conventional kernel error
	* values because it's not being returned via syscall return
	* mechanisms.
	*/
	static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE];
	struct timespec ts;

	if (atomic_read(&proc_event_num_listeners) < 1)
	return;

	msg = (struct cn_msg*)buffer;
	ev = (struct proc_event*)msg->data;
	msg->seq = rcvd_seq;
	ktime_get_ts(&ts); /* get high res monotonic timestamp */
	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
	ev->cpu = -1;
	ev->what = PROC_EVENT_NONE;
	ev->event_data.ack.err = err;
	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
	msg->ack = rcvd_ack + 1;
	msg->len = sizeof(*ev);
	cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
	}

	/**
	* cn_proc_mcast_ctl
	* @data: message sent from userspace via the connector
	*/
	static void cn_proc_mcast_ctl(struct cn_msg *msg,
	struct netlink_skb_parms *nsp)
	{
	enum proc_cn_mcast_op *mc_op = NULL;
	int err = 0;

	if (msg->len != sizeof(*mc_op))
	return;

	mc_op = (enum proc_cn_mcast_op*)msg->data;
	switch (*mc_op) {
	case PROC_CN_MCAST_LISTEN:
	atomic_inc(&proc_event_num_listeners);
	break;
	case PROC_CN_MCAST_IGNORE:
	atomic_dec(&proc_event_num_listeners);
	break;
	default:
	err = EINVAL;
	break;
	}
	cn_proc_ack(err, msg->seq, msg->ack);
	}

	/*
	* cn_proc_init - initialization entry point
	*
	* Adds the connector callback to the connector driver.
	*/
	static int __init cn_proc_init(void)
	{
	int err;

	if ((err = cn_add_callback(&cn_proc_event_id, "cn_proc",
	&cn_proc_mcast_ctl))) {
	printk(KERN_WARNING "cn_proc failed to register\n");
	return err;
	}
	return 0;
	}

	module_init(cn_proc_init);