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

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * 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.
  */

 #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 <linux/pid_namespace.h>

 #include <linux/cn_proc.h>

 /*
  * Size of a cn_msg followed by a proc_event structure.  Since the
  * sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
  * add one 4-byte word to the size here, and then start the actual
  * cn_msg structure 4 bytes into the stack buffer.  The result is that
  * the immediately following proc_event structure is aligned to 8 bytes.
  */
 #define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)

 /* See comment above; we test our assumption about sizeof struct cn_msg here. */
 static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
 {
 	BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
 	return (struct cn_msg *)(buffer + 4);
 }

 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 send_msg(struct cn_msg *msg)
 {
 	preempt_disable();

 	msg->seq = __this_cpu_inc_return(proc_event_counts) - 1;
 	((struct proc_event *)msg->data)->cpu = smp_processor_id();

 	/*
 	 * Preemption remains disabled during send to ensure the messages are
 	 * ordered according to their sequence numbers.
 	 *
 	 * If cn_netlink_send() fails, the data is not sent.
 	 */
 	cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);

 	preempt_enable();
 }

 void proc_fork_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 	struct task_struct *parent;

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	ev->timestamp_ns = ktime_get_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);
 	msg->flags = 0; /* not used */
 	send_msg(msg);
 }

 void proc_exec_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	ev->timestamp_ns = ktime_get_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);
 	msg->flags = 0; /* not used */
 	send_msg(msg);
 }

 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] __aligned(8);
 	const struct cred *cred;

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_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 = from_kuid_munged(&init_user_ns, cred->uid);
 		ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
 	} else if (which_id == PROC_EVENT_GID) {
 		ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
 		ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
 	} else {
 		rcu_read_unlock();
 		return;
 	}
 	rcu_read_unlock();
 	ev->timestamp_ns = ktime_get_ns();

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

 void proc_sid_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	ev->timestamp_ns = ktime_get_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);
 	msg->flags = 0; /* not used */
 	send_msg(msg);
 }

 void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	ev->timestamp_ns = ktime_get_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);
 	msg->flags = 0; /* not used */
 	send_msg(msg);
 }

 void proc_comm_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	ev->timestamp_ns = ktime_get_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);
 	msg->flags = 0; /* not used */
 	send_msg(msg);
 }

 void proc_coredump_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	struct task_struct *parent;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	ev->timestamp_ns = ktime_get_ns();
 	ev->what = PROC_EVENT_COREDUMP;
 	ev->event_data.coredump.process_pid = task->pid;
 	ev->event_data.coredump.process_tgid = task->tgid;

 	rcu_read_lock();
 	if (pid_alive(task)) {
 		parent = rcu_dereference(task->real_parent);
 		ev->event_data.coredump.parent_pid = parent->pid;
 		ev->event_data.coredump.parent_tgid = parent->tgid;
 	}
 	rcu_read_unlock();

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

 void proc_exit_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	struct task_struct *parent;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	ev->timestamp_ns = ktime_get_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;

 	rcu_read_lock();
 	if (pid_alive(task)) {
 		parent = rcu_dereference(task->real_parent);
 		ev->event_data.exit.parent_pid = parent->pid;
 		ev->event_data.exit.parent_tgid = parent->tgid;
 	}
 	rcu_read_unlock();

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

 /*
  * 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] __aligned(8);

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

 	msg = buffer_to_cn_msg(buffer);
 	ev = (struct proc_event *)msg->data;
 	memset(&ev->event_data, 0, sizeof(ev->event_data));
 	msg->seq = rcvd_seq;
 	ev->timestamp_ns = ktime_get_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);
 	msg->flags = 0; /* not used */
 	send_msg(msg);
 }

 /**
  * 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;

 	/*
 	 * Events are reported with respect to the initial pid
 	 * and user namespaces so ignore requestors from
 	 * other namespaces.
 	 */
 	if ((current_user_ns() != &init_user_ns) ||
 	    (task_active_pid_ns(current) != &init_pid_ns))
 		return;

 	/* Can only change if privileged. */
 	if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
 		err = EPERM;
 		goto out;
 	}

 	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;
 	}

 out:
 	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 = cn_add_callback(&cn_proc_event_id,
 				  "cn_proc",
 				  &cn_proc_mcast_ctl);
 	if (err) {
 		pr_warn("cn_proc failed to register\n");
 		return err;
 	}
 	return 0;
 }
 device_initcall(cn_proc_init);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* 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.
	*/

	#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 <linux/pid_namespace.h>

	#include <linux/cn_proc.h>

	/*
	* Size of a cn_msg followed by a proc_event structure. Since the
	* sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
	* add one 4-byte word to the size here, and then start the actual
	* cn_msg structure 4 bytes into the stack buffer. The result is that
	* the immediately following proc_event structure is aligned to 8 bytes.
	*/
	#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)

	/* See comment above; we test our assumption about sizeof struct cn_msg here. */
	static inline struct cn_msg buffer_to_cn_msg(__u8 buffer)
	{
	BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
	return (struct cn_msg *)(buffer + 4);
	}

	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 send_msg(struct cn_msg *msg)
	{
	preempt_disable();

	msg->seq = __this_cpu_inc_return(proc_event_counts) - 1;
	((struct proc_event *)msg->data)->cpu = smp_processor_id();

	/*
	* Preemption remains disabled during send to ensure the messages are
	* ordered according to their sequence numbers.
	*
	* If cn_netlink_send() fails, the data is not sent.
	*/
	cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);

	preempt_enable();
	}

	void proc_fork_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
	struct task_struct *parent;

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	ev->timestamp_ns = ktime_get_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);
	msg->flags = 0; /* not used */
	send_msg(msg);
	}

	void proc_exec_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	ev->timestamp_ns = ktime_get_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);
	msg->flags = 0; /* not used */
	send_msg(msg);
	}

	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] __aligned(8);
	const struct cred *cred;

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_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 = from_kuid_munged(&init_user_ns, cred->uid);
	ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
	} else if (which_id == PROC_EVENT_GID) {
	ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
	ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
	} else {
	rcu_read_unlock();
	return;
	}
	rcu_read_unlock();
	ev->timestamp_ns = ktime_get_ns();

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

	void proc_sid_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	ev->timestamp_ns = ktime_get_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);
	msg->flags = 0; /* not used */
	send_msg(msg);
	}

	void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	ev->timestamp_ns = ktime_get_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);
	msg->flags = 0; /* not used */
	send_msg(msg);
	}

	void proc_comm_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	ev->timestamp_ns = ktime_get_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);
	msg->flags = 0; /* not used */
	send_msg(msg);
	}

	void proc_coredump_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	struct task_struct *parent;
	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	ev->timestamp_ns = ktime_get_ns();
	ev->what = PROC_EVENT_COREDUMP;
	ev->event_data.coredump.process_pid = task->pid;
	ev->event_data.coredump.process_tgid = task->tgid;

	rcu_read_lock();
	if (pid_alive(task)) {
	parent = rcu_dereference(task->real_parent);
	ev->event_data.coredump.parent_pid = parent->pid;
	ev->event_data.coredump.parent_tgid = parent->tgid;
	}
	rcu_read_unlock();

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

	void proc_exit_connector(struct task_struct *task)
	{
	struct cn_msg *msg;
	struct proc_event *ev;
	struct task_struct *parent;
	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	ev->timestamp_ns = ktime_get_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;

	rcu_read_lock();
	if (pid_alive(task)) {
	parent = rcu_dereference(task->real_parent);
	ev->event_data.exit.parent_pid = parent->pid;
	ev->event_data.exit.parent_tgid = parent->tgid;
	}
	rcu_read_unlock();

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

	/*
	* 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] __aligned(8);

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

	msg = buffer_to_cn_msg(buffer);
	ev = (struct proc_event *)msg->data;
	memset(&ev->event_data, 0, sizeof(ev->event_data));
	msg->seq = rcvd_seq;
	ev->timestamp_ns = ktime_get_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);
	msg->flags = 0; /* not used */
	send_msg(msg);
	}

	/**
	* 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;

	/*
	* Events are reported with respect to the initial pid
	* and user namespaces so ignore requestors from
	* other namespaces.
	*/
	if ((current_user_ns() != &init_user_ns) \|\|
	(task_active_pid_ns(current) != &init_pid_ns))
	return;

	/* Can only change if privileged. */
	if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
	err = EPERM;
	goto out;
	}

	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;
	}

	out:
	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 = cn_add_callback(&cn_proc_event_id,
	"cn_proc",
	&cn_proc_mcast_ctl);
	if (err) {
	pr_warn("cn_proc failed to register\n");
	return err;
	}
	return 0;
	}
	device_initcall(cn_proc_init);