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 (!env_file || !env_file[0]) {
  31                 ERROR("SECCOMP_FILE not specified\n");
  32                 return -1;
  33         }
  34
  35         if (install_syscall_filter(*argv, env_file))
  36                 return -1;
  37
  38         unsetenv("LD_PRELOAD");
  39         unsetenv("SECCOMP_FILE");
  40
  41         return (*__main__)(argc, argv, envp);
  42 }
  43
  44 int __libc_start_main(main_t main,
  45                         int argc,
  46                         char **argv,
  47                         ElfW(auxv_t) *auxvec,
  48                         __typeof (main) init,
  49                         void (*fini) (void),
  50                         void (*rtld_fini) (void),
  51                         void *stack_end)
  52 {
  53         start_main_t __start_main__;
  54
  55         __start_main__ = dlsym(RTLD_NEXT, "__libc_start_main");
  56         if (!__start_main__)
  57                 INFO("failed to find __libc_start_main %s\n", dlerror());
  58
  59         __main__ = main;
  60
  61         return (*__start_main__)(__preload_main__, argc, argv, auxvec,
  62                 init, fini, rtld_fini, stack_end);
  63 }
  64
  65 void __uClibc_main(main_t main,
  66                         int argc,
  67                         char **argv,
  68                         void (*app_init)(void),
  69                         void (*app_fini)(void),
  70                         void (*rtld_fini)(void),
  71                         void *stack_end attribute_unused)
  72 {
  73         uClibc_main __start_main__;
  74
  75         __start_main__ = dlsym(RTLD_NEXT, "__uClibc_main");
  76         if (!__start_main__)
  77                 INFO("failed to find __uClibc_main %s\n", dlerror());
  78
  79         __main__ = main;
  80
  81         return (*__start_main__)(__preload_main__, argc, argv,
  82                 app_init, app_fini, rtld_fini, stack_end);
  83 }