/*
   * 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
  ");
  		return err;
  	}
  	return 0;
  }
  
  module_init(cn_proc_init);