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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This is a list of environment variables which the ELF loader unsets when
// loading a SUID binary. Because they are unset rather than just ignored, they
// aren't passed to child processes of SUID processes either.
//
// We need to save these environment variables before running a SUID sandbox
// and restore them before running child processes (but after dropping root).
//
// List gathered from glibc sources (00ebd7ed58df389a78e41dece058048725cb585e):
// sysdeps/unix/sysv/linux/i386/dl-librecon.h
// sysdeps/generic/unsecvars.h
#ifndef SANDBOX_LINUX_SUID_COMMON_SUID_UNSAFE_ENVIRONMENT_VARIABLES_H_
#define SANDBOX_LINUX_SUID_COMMON_SUID_UNSAFE_ENVIRONMENT_VARIABLES_H_
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h> // malloc
#include <string.h> // memcpy
static const char* const kSUIDUnsafeEnvironmentVariables[] = {
"LD_AOUT_LIBRARY_PATH",
"LD_AOUT_PRELOAD",
"GCONV_PATH",
"GETCONF_DIR",
"HOSTALIASES",
"LD_AUDIT",
"LD_DEBUG",
"LD_DEBUG_OUTPUT",
"LD_DYNAMIC_WEAK",
"LD_LIBRARY_PATH",
"LD_ORIGIN_PATH",
"LD_PRELOAD",
"LD_PROFILE",
"LD_SHOW_AUXV",
"LD_USE_LOAD_BIAS",
"LOCALDOMAIN",
"LOCPATH",
"MALLOC_TRACE",
"NIS_PATH",
"NLSPATH",
"RESOLV_HOST_CONF",
"RES_OPTIONS",
"TMPDIR",
"TZDIR",
NULL,
};
// Return a malloc allocated string containing the 'saved' environment variable
// name for a given environment variable.
static inline char* SandboxSavedEnvironmentVariable(const char* envvar) {
const size_t envvar_len = strlen(envvar);
const size_t kMaxSizeT = (size_t) -1;
if (envvar_len > kMaxSizeT - 1 - 8)
return NULL;
const size_t saved_envvarlen = envvar_len + 1 /* NUL terminator */ +
8 /* strlen("SANDBOX_") */;
char* const saved_envvar = (char*) malloc(saved_envvarlen);
if (!saved_envvar)
return NULL;
memcpy(saved_envvar, "SANDBOX_", 8);
memcpy(saved_envvar + 8, envvar, envvar_len);
saved_envvar[8 + envvar_len] = 0;
return saved_envvar;
}
#endif // SANDBOX_LINUX_SUID_COMMON_SUID_UNSAFE_ENVIRONMENT_VARIABLES_H_
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