kthread1.c

fsmlabs的real time linux的内核

/*
 * Written by Der Herr Hofrat, [e-mail]
 * (C) 2002 FSMLabs
 * License: GPL Version 2
 */

#define __KERNEL_SYSCALLS__

#include <linux/config.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/unistd.h>
#include <linux/kmod.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>

static int errno;

static char cmd_path[256] = "/bin/echo";

static int 
exec_cmd(void * kthread_arg)
{
	struct task_struct *curtask = current;
	/* we set up a minimum environment but note that we still inherit
	 * the environment of who ever launched insmod of this module !
	 * sounds dangorous ? - it is !
	 */
	static char * envp[] = { "HOME=/root ", 
		"TERM=linux ", 
		"PATH=/bin", 
		NULL };
	char *argv[] = { 
		cmd_path,
		kthread_arg,
		NULL };
	int ret;

	/* Give the kthread all effective privileges...scarry... */
	curtask->euid = curtask->fsuid = 0;
	curtask->egid = curtask->fsgid = 0;
	cap_set_full(curtask->cap_effective);

	/* Allow execve args to be in kernel space. */
	set_fs(KERNEL_DS);

	printk("calling execve for %s \n",cmd_path); 
	ret = execve(cmd_path, argv, envp);

	/* if we ever get here - execve failed */
	printk(KERN_ERR "failed to exec %s, ret = %d\n", cmd_path,ret);
	return -1;
}

int 
init_module(void)
{
	pid_t pid;
	char kthread_arg[]="Hello Kernel World !";

	pid = kernel_thread(exec_cmd, (void*) kthread_arg, 0);
	if (pid < 0) {
		printk(KERN_ERR "fork failed, errno %d\n", -pid);
		return pid;
	}
	printk("fork ok, pid %d\n",pid);
	return 0;
}

void 
cleanup_module(void)
{
	pid_t pid;
	char kthread_arg[]="Good by crul World :)";

	pid = kernel_thread(exec_cmd, (void*) kthread_arg, 0);
	if (pid < 0) {
		printk(KERN_ERR "fork failed, errno %d\n", -pid);
	}
	printk("fork ok, pid %d\n",pid);
	printk("module exit\n");
}