jail/preload.c

   1 /*
   2  * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #define _GNU_SOURCE
  15 #include <sys/types.h>
  16 #include <stdlib.h>
  17 #include <unistd.h>
  18 #include <string.h>
  19 #include <dlfcn.h>
  20
  21 #include "seccomp.h"
  22 #include "../preload.h"
  23
  24 static main_t __main__;
  25
  26 static int __preload_main__(int argc, char **argv, char **envp)
  27 {
  28         char *env_file = getenv("SECCOMP_FILE");
  29
  30         if (install_syscall_filter(*argv, env_file))
  31                 return -1;
  32
  33         unsetenv("LD_PRELOAD");
  34         unsetenv("SECCOMP_FILE");
  35
  36         return (*__main__)(argc, argv, envp);
  37 }
  38
  39 int __libc_start_main(main_t main,
  40                         int argc,
  41                         char **argv,
  42                         ElfW(auxv_t) *auxvec,
  43                         __typeof (main) init,
  44                         void (*fini) (void),
  45                         void (*rtld_fini) (void),
  46                         void *stack_end)
  47 {
  48         start_main_t __start_main__;
  49
  50         __start_main__ = dlsym(RTLD_NEXT, "__libc_start_main");
  51         if (!__start_main__)
  52                 INFO("failed to find __libc_start_main %s\n", dlerror());
  53
  54         __main__ = main;
  55
  56         return (*__start_main__)(__preload_main__, argc, argv, auxvec,
  57                 init, fini, rtld_fini, stack_end);
  58 }
  59
  60 void __uClibc_main(main_t main,
  61                         int argc,
  62                         char **argv,
  63                         void (*app_init)(void),
  64                         void (*app_fini)(void),
  65                         void (*rtld_fini)(void),
  66                         void *stack_end attribute_unused)
  67 {
  68         uClibc_main __start_main__;
  69
  70         __start_main__ = dlsym(RTLD_NEXT, "__uClibc_main");
  71         if (!__start_main__)
  72                 INFO("failed to find __uClibc_main %s\n", dlerror());
  73
  74         __main__ = main;
  75
  76         return (*__start_main__)(__preload_main__, argc, argv,
  77                 app_init, app_fini, rtld_fini, stack_end);
  78 }