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 "log.h"
  22 #include "seccomp.h"
  23 #include "../preload.h"
  24
  25 static main_t __main__;
  26 int debug;
  27
  28 static int __preload_main__(int argc, char **argv, char **envp)
  29 {
  30         char *env_file = getenv("SECCOMP_FILE");
  31         char *env_debug = getenv("SECCOMP_DEBUG");
  32
  33         if (!env_file || !env_file[0]) {
  34                 ERROR("SECCOMP_FILE not specified\n");
  35                 return -1;
  36         }
  37
  38         if (env_debug)
  39                 debug = atoi(env_debug);
  40         else
  41                 debug = 0;
  42
  43         if (install_syscall_filter(*argv, env_file))
  44                 return -1;
  45
  46         unsetenv("LD_PRELOAD");
  47         unsetenv("SECCOMP_DEBUG");
  48         unsetenv("SECCOMP_FILE");
  49
  50         return (*__main__)(argc, argv, envp);
  51 }
  52
  53 int __libc_start_main(main_t main,
  54                         int argc,
  55                         char **argv,
  56                         ElfW(auxv_t) *auxvec,
  57                         __typeof (main) init,
  58                         void (*fini) (void),
  59                         void (*rtld_fini) (void),
  60                         void *stack_end)
  61 {
  62         start_main_t __start_main__;
  63
  64         __start_main__ = dlsym(RTLD_NEXT, "__libc_start_main");
  65         if (!__start_main__)
  66                 INFO("failed to find __libc_start_main %s\n", dlerror());
  67
  68         __main__ = main;
  69
  70         return (*__start_main__)(__preload_main__, argc, argv, auxvec,
  71                 init, fini, rtld_fini, stack_end);
  72 }
  73
  74 void __uClibc_main(main_t main,
  75                         int argc,
  76                         char **argv,
  77                         void (*app_init)(void),
  78                         void (*app_fini)(void),
  79                         void (*rtld_fini)(void),
  80                         void *stack_end attribute_unused)
  81 {
  82         uClibc_main __start_main__;
  83
  84         __start_main__ = dlsym(RTLD_NEXT, "__uClibc_main");
  85         if (!__start_main__)
  86                 INFO("failed to find __uClibc_main %s\n", dlerror());
  87
  88         __main__ = main;
  89
  90         return (*__start_main__)(__preload_main__, argc, argv,
  91                 app_init, app_fini, rtld_fini, stack_end);
  92 }