sandbox/linux/suid/common/suid_unsafe_environment_variables.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This is a list of environment variables which the ELF loader unsets when
   6 // loading a SUID binary. Because they are unset rather than just ignored, they
   7 // aren't passed to child processes of SUID processes either.
   8 //
   9 // We need to save these environment variables before running a SUID sandbox
  10 // and restore them before running child processes (but after dropping root).
  11 //
  12 // List gathered from glibc sources (00ebd7ed58df389a78e41dece058048725cb585e):
  13 //   sysdeps/unix/sysv/linux/i386/dl-librecon.h
  14 //   sysdeps/generic/unsecvars.h
  15
  16 #ifndef SANDBOX_LINUX_SUID_SUID_UNSAFE_ENVIRONMENT_VARIABLES_H_
  17 #define SANDBOX_LINUX_SUID_SUID_UNSAFE_ENVIRONMENT_VARIABLES_H_
  18
  19 #include <stdint.h>
  20 #include <stdlib.h>  // malloc
  21 #include <string.h>  // memcpy
  22
  23 static const char* kSUIDUnsafeEnvironmentVariables[] = {
  24   "LD_AOUT_LIBRARY_PATH",
  25   "LD_AOUT_PRELOAD",
  26   "GCONV_PATH",
  27   "GETCONF_DIR",
  28   "HOSTALIASES",
  29   "LD_AUDIT",
  30   "LD_DEBUG",
  31   "LD_DEBUG_OUTPUT",
  32   "LD_DYNAMIC_WEAK",
  33   "LD_LIBRARY_PATH",
  34   "LD_ORIGIN_PATH",
  35   "LD_PRELOAD",
  36   "LD_PROFILE",
  37   "LD_SHOW_AUXV",
  38   "LD_USE_LOAD_BIAS",
  39   "LOCALDOMAIN",
  40   "LOCPATH",
  41   "MALLOC_TRACE",
  42   "NIS_PATH",
  43   "NLSPATH",
  44   "RESOLV_HOST_CONF",
  45   "RES_OPTIONS",
  46   "TMPDIR",
  47   "TZDIR",
  48   NULL,
  49 };
  50
  51 // Return a malloc allocated string containing the 'saved' environment variable
  52 // name for a given environment variable.
  53 static inline char* SandboxSavedEnvironmentVariable(const char* envvar) {
  54   const size_t envvar_len = strlen(envvar);
  55   const size_t kMaxSizeT = (size_t) -1;
  56
  57   if (envvar_len > kMaxSizeT - 1 - 8)
  58     return NULL;
  59
  60   const size_t saved_envvarlen = envvar_len + 1 /* NUL terminator */ +
  61                                               8 /* strlen("SANDBOX_") */;
  62   char* const saved_envvar = (char*) malloc(saved_envvarlen);
  63   if (!saved_envvar)
  64     return NULL;
  65
  66   memcpy(saved_envvar, "SANDBOX_", 8);
  67   memcpy(saved_envvar + 8, envvar, envvar_len);
  68   saved_envvar[8 + envvar_len] = 0;
  69
  70   return saved_envvar;
  71 }
  72
  73 #endif  // SANDBOX_LINUX_SUID_SUID_UNSAFE_ENVIRONMENT_VARIABLES_H_