/* A basic linux lkm to allow debugging and tracing of binarys    */
/* that uses anti-debugging technique like                        */
/* if (ptrace(PTRACE_TRACEME..                   */
/* to stop the debugger or tracer                            */

/* just #gcc -c anti-anti-dbug.c ; insmod anti-anti-dbug.o          */
/* then strace or debug the protected binary       */

/* by Dalnet SLACKo   slacko@mail.ru  */

#define __KERNEL__
#define MODULE

#include <linux/sched.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <sys/syscall.h>
#include <asm/uaccess.h>

extern void *sys_call_table[];
int i=0;
long int(*saved)(int,pid_t,void *,void *);
  
long int _ptrace(int a,pid_t b,void * c,void * d) 
  {
     if(a == 0) {
    i++;
    if (i == 2) {
    i = 0;
    return 0;
      }
    } 
         return saved(a,b,c,d); 
  }

int init_module() {
  saved = sys_call_table[SYS_ptrace];
  sys_call_table[SYS_ptrace] = _ptrace;
  return 0;
  }
void cleanup_module() {
  sys_call_table[SYS_ptrace] = saved;
  }