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 <stdio.h>
  17 #include <stdlib.h>
  18 #include <unistd.h>
  19 #include <string.h>
  20 #include <dlfcn.h>
  21 #include <syslog.h>
  22
  23 #include "seccomp.h"
  24 #include "../preload.h"
  25
  26 static main_t __main__;
  27
  28 static int __preload_main__(int argc, char **argv, char **envp)
  29 {
  30         uid_t uid = getuid();
  31         char *env_file = getenv("SECCOMP_FILE");
  32
  33         if (uid) {
  34                 INFO("preload-seccomp: %s: not root, cannot install seccomp filter\n", *argv);
  35                 return -1;
  36         }
  37
  38         if (install_syscall_filter(*argv, env_file))
  39                 return -1;
  40
  41         unsetenv("LD_PRELOAD");
  42         unsetenv("SECCOMP_FILE");
  43
  44         return (*__main__)(argc, argv, envp);
  45 }
  46
  47 int __libc_start_main(main_t main,
  48                         int argc,
  49                         char **argv,
  50                         ElfW(auxv_t) *auxvec,
  51                         __typeof (main) init,
  52                         void (*fini) (void),
  53                         void (*rtld_fini) (void),
  54                         void *stack_end)
  55 {
  56         start_main_t __start_main__;
  57
  58         __start_main__ = dlsym(RTLD_NEXT, "__libc_start_main");
  59         if (!__start_main__)
  60                 INFO("failed to find __libc_start_main %s\n", dlerror());
  61
  62         __main__ = main;
  63
  64         return (*__start_main__)(__preload_main__, argc, argv, auxvec,
  65                 init, fini, rtld_fini, stack_end);
  66 }
  67
  68 void __uClibc_main(main_t main,
  69                         int argc,
  70                         char **argv,
  71                         void (*app_init)(void),
  72                         void (*app_fini)(void),
  73                         void (*rtld_fini)(void),
  74                         void *stack_end attribute_unused)
  75 {
  76         uClibc_main __start_main__;
  77
  78         __start_main__ = dlsym(RTLD_NEXT, "__uClibc_main");
  79         if (!__start_main__)
  80                 INFO("failed to find __uClibc_main %s\n", dlerror());
  81
  82         __main__ = main;
  83
  84         return (*__start_main__)(__preload_main__, argc, argv,
  85                 app_init, app_fini, rtld_fini, stack_end);
  86 }