shoumikhin / elf-hook Goto Github PK

elf_hook(handle, base_address, "socket", hook_socket);
elf_hook(handle, base_address, "bind", hook_bind);
elf_hook(handle, base_address, "connect", hook_connect);
elf_hook(handle, base_address, "getpeername", hook_getpeername);
elf_hook(handle, base_address, "getsockname", hook_getsockname);
elf_hook(handle, base_address, "getsockopt", hook_getsockopt);
elf_hook(handle, base_address, "listen", hook_listen);
elf_hook(handle, base_address, "recv", hook_recv);
elf_hook(handle, base_address, "recvfrom", hook_recvfrom);
elf_hook(handle, base_address, "recvmsg", hook_recvmsg);
elf_hook(handle, base_address, "send", hook_send);
elf_hook(handle, base_address, "sendmsg", hook_sendmsg);
elf_hook(handle, base_address, "sendto", hook_sendto);
elf_hook(handle, base_address, "setsockopt", hook_setsockopt);
elf_hook(handle, base_address, "shutdown", hook_shutdown);
elf_hook(handle, base_address, "socketpair", hook_socketpair);

  215           /* Is there a destructor function?  */
  216           if (l->l_info[DT_FINI_ARRAY] != NULL
  217               || l->l_info[DT_FINI] != NULL)
  218             {
  219               /* When debugging print a message first.  */
  220               if (__builtin_expect (GLRO(dl_debug_mask)
  221                         & DL_DEBUG_IMPCALLS, 0))
  222             _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
  223                       DSO_FILENAME (l->l_name),
  224                       ns);
  225 
  226               /* First see whether an array is given.  */
  227               if (l->l_info[DT_FINI_ARRAY] != NULL)
  228             {
  229               ElfW(Addr) *array =
  230                 (ElfW(Addr) *) (l->l_addr
  231                         + l->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
  232               unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
  233                         / sizeof (ElfW(Addr)));
  234               while (i-- > 0)
  235                 ((fini_t) array[i]) ();         // this is the line that seg faults
  236             }
  237

#include <stdio.h>

void func() {
  printf("func!\n");
}

void wrapfunc() {
  func();
}

#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>

#include "elf_hook.h"

#define LIBFUNC_PATH "./libfunc.so" //position dependent code

void wrapfunc();
void hook() {
  printf("hook!\n");
}

void set_hook(void * handle) {
  void *base = NULL;

  if (NULL == handle) {
    fprintf(stderr, "Failed to open \"%s\"! %s\n", LIBFUNC_PATH, dlerror()); exit(1);
  }
  if(get_module_base_address(LIBFUNC_PATH, handle, &base)) {
    fprintf(stderr, "Failed to get module base addresses\n"); exit(1);
  }
  void *orig = elf_hook(LIBFUNC_PATH, base, "func", hook);
  if (NULL == orig) {
    fprintf(stderr, "Redirection failed!\n"); exit(1);
  }
}

int main() {

  wrapfunc();

  void *handle = dlopen(LIBFUNC_PATH, RTLD_LAZY);
  set_hook(handle);

  wrapfunc();

  dlclose(handle);
  return 0;
}