System Admin

<br />
#define CODESIZE 7<br />
<br />
static char originalcode[CODESIZE];<br />
static char jmpcode[CODESIZE]=<br />
"\xb8\x00\x00\x00\x00" /*movl $0,%eax*/<br />
"\xff\xe0" /* jmp *%eax */<br />
;<br />
void modfun(unsigned int,int);<br />
<br />
int (*getkeycode)(unsigned int scancode)=(int (*)(unsigned <br />
int))0xc022fae0;<br />
<br />
int keycode;<br />
void (*kbd_keycode)(unsigned int keycode,int down,struct pt_regs <br />
*regs)=<br />
 (void(*)(unsigned int keycode,int down,struct pt_regs <br />
*regs))0xc0230d30;<br />
 <br />
int init_module(void)<br />
{<br />
 printk(KERN_INFO "ENTERED INTO INIT MODULE\n");<br />
 keycode=(getkeycode(0x1e));<br />
<br />
 *(long *)&jmpcode[1]=(long)modfun;<br />
 memcpy(originalcode,kbd_keycode,CODESIZE);<br />
 memcpy(kbd_keycode,jmpcode,CODESIZE);<br />
<br />
 return 0;<br />
}<br />
<br />
void cleanup_module(void) <br />
{<br />
 printk(KERN_INFO "ENTERED INTO CLEANUP MODULE\n");<br />
 memcpy(kbd_keycode,originalcode,CODESIZE);<br />
}<br />
<br />
void modfun(unsigned int keycode,int down)<br />
{<br />
 printk("ENTERED INTO MODIFIED FUNCTION\n");<br />
<br />
 if(keycode==30)<br />
    memcpy(kbd_keycode,originalcode,CODESIZE);<br />
 else<br />
    printk("KEY IS NOT 'a'\n");<br />
}<br />
 <br />
<br />
kbd_keycode is the first function to be called when we press a key.