Linux device drivers

A Linux device driver code that can be used to practice various exploit exploits.

First, the device driver

/* DEMO.C */

#include <linux/cdev.h>

#include <linux/device.h>

#include <asm/uaccess.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/fs.h>

Module_license ("Dual BSD/GPL");

#define DEMO_MAJOR 255

#define Demo_minor 0

#define DEMO_COUNT 1

dev_t dev = 0;

U32 demo_major = 0;

U32 Demo_minor = 0;

struct Cdev Demo_cdev;

struct class *dev_class = NULL;

struct device *dev_device = NULL;

int Demo_open (struct inode* inode, struct file *filp) {

PRINTK ("Enter Demo_open () \ n");

return 0;

}

ssize_t demo_read (struct file *filp, char __user *buf, size_t count, loff_t *offset) {

Char s[10] = {0};

PRINTK ("Enter Demo_read () \ n");

/* ADD CODE here */

Copy_from_user (S, buf, sizeof (s)-1);

PRINTK ("read from userspace =%s \ n", s);

return 0;

}

ssize_t demo_write (struct file *filp, const char __user *buf, size_t count, loff_t *offset) {

PRINTK ("Enter demo_write () \ n");

return 0;

}

/*

int Demo_ioctl (struct inode *inode, struct file *filp, unsigned int cmd, unsigned Long data)

{

PRINTK ("Enter Demo_ioctl () \ n");

return 0;

}

*/

int demo_release (struct inode *inode, struct file *filp) {

PRINTK ("Enter demo_release () \ n");

return 0;

}

struct File_operations demo_fops = {

. Owner = This_module,

. open = Demo_open,

. Read = Demo_read,

. write = Demo_write,

/*.ioctl = demo_ioctl,*/

. Release = Demo_release,

};

int __init demo_init (void) {

int ret = 0;

PRINTK ("Enter Demo_init () \ n");

if (demo_major) {

dev = MKDEV (demo_major, Demo_minor);

ret = register_chrdev_region (Dev, Demo_count, "Demo_demo");

} else {

ret = Alloc_chrdev_region (&dev, Demo_minor, Demo_count, "demo_demo02");

}

if (Ret < 0) {

PRINTK ("Register_chrdev_region failed!\n");

Goto Fail_register_chrdev;

}

Demo_major = major (Dev);

PRINTK ("demo_major =%d\n", demo_major);

Cdev_init (&demo_cdev, &demo_fops);

ret = Cdev_add (&demo_cdev, Dev, demo_count);

if (Ret < 0) {

PRINTK ("Cdev_add failed!\n");

Goto Fail_cdev_add;

}

Dev_class = Class_create (This_module, "Demo_class");

if (Is_err (Dev_class)) {

PRINTK ("Class_create failed!\n");

ret = Ptr_err ("Dev_class");

Goto Fail_class_create;

}

Dev_device = device_create (Dev_class, null, dev, null, "demo%d", Demo_minor);

if (Is_err (Dev_device)) {

PRINTK ("Device_create failed!\n");

ret = Ptr_err (dev_device);

Goto Fail_device_create;

}

return 0;

Fail_device_create:

Class_destroy (Dev_class);

Fail_class_create:

Cdev_del (&demo_cdev);

Fail_cdev_add:

Unregister_chrdev_region (Dev, demo_count);

Fail_register_chrdev:

return ret;

}

void __exit demo_exit (void) {

PRINTK ("Enter demo_exit () \ n");

Device_destroy (Dev_class, Dev);

Class_destroy (Dev_class);

Cdev_del (&demo_cdev);

Unregister_chrdev_region (Dev, demo_count);

}

Module_init (Demo_init);

Module_exit (Demo_exit);

Ii.. Makefile Documents

/* Makefile */

Ifneq ($ (kernelrelease),)

Obj-m: = demo.o

Else

Kerneldir =/lib/modules/$ (Shell uname-r)/build

PWD: = $ (shell pwd)

Default

$ (make)-C $ (Kerneldir) m=$ (PWD) modules

endif

Clean

RM-RF *.o *~ core depend. *.cmd *.ko *.mod.c. Tmp_versions Modules.order module.symvers

Third, driver installation script

/* setup.sh */

Rmmod Demo

Insmod./demo.ko

chmod 666/dev/demo0

Four, simple test

/* CLIENT.C */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <fcntl.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/ioctl.h>

Int

Main (int arg, char **argv) {

Char *s = (char*) malloc (20);

memcpy (S, "Hello driver.", 10);

int FD =-1;

if ( -1 = = (FD = open ("/dev/demo0", O_rdonly))) {

Perror ("open");

Return (-1);

}

Read (FD, s, 0, 0);

System ("/bin/sh");

return (0);

}

V. Test results

Kiiim@ubuntu : ~/__demo_driver$./client
Kiiim@ubuntu : ~/__demo_driver$ dmesg

......

[4405.506553] Enter Demo_init ()

[4405.506558] Demo_major = 247

[4408.702358] Enter Demo_open ()

[4408.702365] Enter Demo_read ()

[4408.702366] read from userspace = Hello dri

[4408.702527] Enter demo_release ()

Kiiim@ubuntu : ~/__demo_driver$

Linux device drivers