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/*
* === Android Connect Blinker ===
* -- by Jason A. Donenfeld --
* Jason@zx2c4.com
*
* This creates two files in proc:
*
* /proc/blinker/trigger_port
* /proc/blinker/backlight_file
*
* When the system attempts to make a connection to localhost using the port
* specified in trigger_port, backlight_file is used to blink the backlight.
*
* This occurs regardless of whether or not there exists anything listening
* on trigger_port.
*
* # cd /proc/blinker/
* # ls
* backlight_file trigger_port
* # echo 9184 > trigger_port
* # cat backlight_file
* /sys/class/backlight/s5p_bl/brightness
* # cat trigger_port
* 9184
* # nc localhost 9184
* ZX2C4-Laptop [127.0.0.1] 9184 (?) : Connection refused
* # dmesg | tail -n 1
* [ 789.250531] blinker: connected to the magic port 9184
*
*/
#include <linux/module.h>
#include <linux/net.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#define PROC_BLINKER "blinker"
#define PROC_PORT "trigger_port"
#define PROC_FILE "backlight_file"
#define MAX_LENGTH 512
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jason A. Donenfeld");
MODULE_DESCRIPTION("Android Screen Blinker");
extern struct proto_ops inet_stream_ops;
static struct proc_dir_entry *proc_blinker;
static struct proc_dir_entry *proc_port;
static struct proc_dir_entry *proc_file;
static unsigned int trigger_port;
static unsigned char backlight_file[MAX_LENGTH];
static void disable_page_protection(void)
{
unsigned long value;
asm volatile("mov %%cr0,%0" : "=r" (value));
if (value & 0x00010000) {
value &= ~0x00010000;
asm volatile("mov %0,%%cr0": : "r" (value));
}
}
static void enable_page_protection(void)
{
unsigned long value;
asm volatile("mov %%cr0,%0" : "=r" (value));
if (!(value & 0x00010000)) {
value |= 0x00010000;
asm volatile("mov %0,%%cr0": : "r" (value));
}
}
int (*old_connect)(struct socket *sock, struct sockaddr *uaddr, int sockaddr_len, int flags);
int connect(struct socket *sock, struct sockaddr *uaddr, int sockaddr_len, int flags)
{
struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
if (ntohl(usin->sin_addr.s_addr) == 2130706433 && ntohs(usin->sin_port) == trigger_port) {
printk(KERN_INFO "blinker: connected to the magic port %u\n", trigger_port);
//TODO: blink the screen
}
return (*old_connect)(sock, uaddr, sockaddr_len, flags);
}
int port_write(struct file *file, const char __user *ubuf, unsigned long count, void *data)
{
char buf[MAX_LENGTH];
printk(KERN_INFO "blinker: called set_port\n");
memset(buf, 0, sizeof(buf));
if (count > MAX_LENGTH - 1)
count = MAX_LENGTH - 1;
if (copy_from_user(&buf, ubuf, count))
return -EFAULT;
buf[MAX_LENGTH - 1] = 0;
sscanf(buf, "%u", &trigger_port);
return count;
}
int port_read(char *page, char **start, off_t off, int count, int *eof, void *data)
{
printk(KERN_INFO "blinker: called get_port\n");
return snprintf(page, MAX_LENGTH, "%u\n", trigger_port);
}
int file_write(struct file *file, const char __user *ubuf, unsigned long count, void *data)
{
char buf[MAX_LENGTH];
char *line;
printk(KERN_INFO "blinker: called set_file\n");
if (count > MAX_LENGTH - 1)
count = MAX_LENGTH - 1;
if (copy_from_user(&buf, ubuf, count))
return -EFAULT;
buf[count + 1] = 0;
line = strchr(buf, '\n');
if (line)
*line = 0;
memcpy(backlight_file, buf, sizeof(backlight_file));
return count;
}
int file_read(char *page, char **start, off_t off, int count, int *eof, void *data)
{
printk(KERN_INFO "blinker: called get_file\n");
return snprintf(page, MAX_LENGTH, "%s\n", backlight_file);
}
static int init(void)
{
proc_blinker = proc_mkdir(PROC_BLINKER, NULL);
proc_port = create_proc_entry(PROC_PORT, 0600, proc_blinker);
proc_port->read_proc = port_read;
proc_port->write_proc = port_write;
proc_file = create_proc_entry(PROC_FILE, 0600, proc_blinker);
proc_file->read_proc = file_read;
proc_file->write_proc = file_write;
printk(KERN_INFO "blinker: created /proc/blinker/\n");
old_connect = inet_stream_ops.connect;
disable_page_protection();
inet_stream_ops.connect = connect;
enable_page_protection();
printk(KERN_INFO "blinker: remapped inet_stream_ops.connect\n");
trigger_port = 9191;
strcpy(backlight_file, "/sys/class/backlight/s5p_bl/brightness");
return 0;
}
static void exit(void)
{
disable_page_protection();
inet_stream_ops.connect = old_connect;
enable_page_protection();
printk(KERN_INFO "blinker: unremapped inet_stream_ops.connect\n");
remove_proc_entry(PROC_PORT, proc_blinker);
remove_proc_entry(PROC_FILE, proc_blinker);
remove_proc_entry(PROC_BLINKER, NULL);
printk(KERN_INFO "blinker: removed /proc/blinker/\n");
}
module_init(init);
module_exit(exit);
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