/**
@file
@brief    'exec', 'exit' and 'fork' tracepoints
@details  Copyright (c) 2017-2021 Acronis International GmbH
@author   Mikhail Krivtsov ([email protected])
@since    $Id: $
*/

#include "tracepoints.h"

#include "compat.h"
#include "debug.h"
#include "exit_event.h"
#include "exec_event.h"
#include "ftrace_hooks/ftrace_events.h"
#include "fork_event.h"
#include "memory.h"
#include "message.h"

#include <linux/binfmts.h>
#include <linux/dcache.h>	// d_path
#include <linux/file.h>		// fput()
#include <linux/fs.h>		// struct file
#include <linux/limits.h>	// PATH_MAX
#include <linux/mm.h>		// get_task_exe_file()
#include <linux/mm_types.h>	// struct mm_struct
#include <linux/path.h>		// struct path
#ifndef KERNEL_MOCK
#include <linux/sched.h>	// struct task_struct
#else
#include <mock/mock_sched.h>
#endif
#include <linux/tracepoint.h>
#include <linux/version.h>	// LINUX_VERSION_CODE, KERNEL_VERSION()
#include <trace/events/sched.h>	// TRACE_EVENT(sched_*)

#ifdef HAVE_SCHED_PROCESS_EXEC_TRACEPOINT
static bool g_registered_exec = false;
#endif
static bool g_registered_exit = false;
static bool g_registered_fork = false;

static TRACE_CB_PROTO(sched_process_exit,
		TP_PROTO(struct task_struct *p))
{
	DPRINTF("exit() p=%p { pid=%d tgid=%d }", p, p->pid, p->tgid);
	exit_event_nowait(p);
}

/*
 * Here the caller only guarantees locking for struct file and struct inode.
 * Locking must therefore be done in the probe to use the dentry.
 */
static TRACE_CB_PROTO(sched_process_fork,
		TP_PROTO(struct task_struct *current_macro,
				struct task_struct *p))
{
	DPRINTF("fork() current=%p { pid=%d tgid=%d comm='%s' } "
		"p=%p { pid=%d tgid=%d comm='%s' }",
		current_macro, current_macro->pid, current_macro->tgid,
				current_macro->comm,
		p, p->pid, p->tgid, p->comm);
	fork_event_nowait(current_macro, p);
}

#ifdef HAVE_SCHED_PROCESS_EXEC_TRACEPOINT
static TRACE_CB_PROTO(sched_process_exec,
		TP_PROTO(struct task_struct *p, pid_t old_pid, struct linux_binprm *bprm))
{
	DPRINTF("exec() p=%p { pid=%d tgid=%d comm='%s' }", p, p->pid, p->tgid, p->comm);
	exec_event_nowait(p, bprm);
}
#endif

int tracepoints_attach(void)
{
	int ret;

	if (!ftrace_post_event_have(FTRACE_POST_EVENT_EXIT)) {
		ret = REGISTER_TRACE(sched_process_exit, TRACE_CB_NAME(sched_process_exit));
		if (ret) {
			EPRINTF("'register_trace_sched_process_exit()' failure %i", ret);
			goto fail;
		}
		g_registered_exit = true;
	}

	if (!ftrace_post_event_have(FTRACE_POST_EVENT_FORK)) {
		ret = REGISTER_TRACE(sched_process_fork, TRACE_CB_NAME(sched_process_fork));
		if (ret) {
			EPRINTF("'register_trace_sched_process_fork()' failure %i", ret);
			goto fail;
		}
		g_registered_fork = true;
	}

#ifdef HAVE_SCHED_PROCESS_EXEC_TRACEPOINT
	if (!ftrace_post_event_have(FTRACE_POST_EVENT_EXEC)) {
		ret = REGISTER_TRACE(sched_process_exec, TRACE_CB_NAME(sched_process_exec));
		if (ret) {
			EPRINTF("'register_trace_sched_process_exec()' failure %i", ret);
			goto fail;
		}
		g_registered_exec = true;
	}
#endif

	IPRINTF("tracepoints attached");
	return 0;

fail:
	tracepoints_detach();
	return ret;
}

void tracepoints_detach(void)
{
	if (g_registered_fork) {
		UNREGISTER_TRACE(sched_process_fork, TRACE_CB_NAME(sched_process_fork));
		g_registered_fork = false;
	}
	if (g_registered_exit) {
		UNREGISTER_TRACE(sched_process_exit, TRACE_CB_NAME(sched_process_exit));
		g_registered_exit = false;
	}
#ifdef HAVE_SCHED_PROCESS_EXEC_TRACEPOINT
	if (g_registered_exec) {
		UNREGISTER_TRACE(sched_process_exec, TRACE_CB_NAME(sched_process_exec));
		g_registered_exec = false;
	}
#endif
	tracepoint_synchronize_unregister();
	IPRINTF("tracepoints detached");
}