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/*-
* Copyright (c) 2004 Tim Kientzle
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <string.h>
#include "libutil.h"
static int env_var_in_list(const char * const *list, char *var, size_t len);
/*
* Default whitelist of "known safe" environment variables.
*/
static const char *default_whitelist[] = {
/* List from SUS "Environment Variables" Appendix */
"ARFLAGS", "CC", "CDPATH", "CFLAGS", "CHARSET", "COLUMNS",
"DATEMSK", "DEAD", "EDITOR", "ENV", "EXINIT", "FC", "FCEDIT",
"FFLAGS", "GET", "GFLAGS", "HISTFILE", "HISTORY", "HISTSIZE",
"HOME", "IFS", "LANG", "LC_ALL", "LC_COLLATE", "LC_CTYPE",
"LC_MESSAGES", "LC_MONETARY", "LC_NUMERIC", "LC_TIME", "LDFLAGS",
"LEX", "LFLAGS", "LINENO", "LINES", "LISTER", "LOGNAME", "LPDEST",
"MAIL", "MAILCHECK", "MAILER", "MAILPATH", "MAILRC", "MAKEFLAGS",
"MAKESHELL", "MANPATH", "MBOX", "MORE", "MSGVERB", "NLSPATH",
"NPROC", "OLDPWD", "OPTARG", "OPTERR", "OPTIND", "PAGER", "PATH",
"PPID", "PRINTER", "PROCLANG", "PROJECTDIR", "PS1", "PS2", "PS3",
"PS4", "PWD", "RANDOM", "SECONDS", "SHELL", "TERM", "TERMCAP",
"TERMINFO", "TMPDIR", "TZ", "USER", "VISUAL", "YACC", "YFLAGS",
/* Additional Environment Variables */
"KRB5CCNAME", "LOGIN", "MAILDIR", "SSH_AGENT_PID", "SSH_AUTH_SOCK",
/* Terminating NULL */
NULL
};
static int
env_var_in_list(const char * const *list, char *var, size_t len)
{
if (list == NULL)
return (0);
while (*list != NULL) {
if (strncmp(var, *list, len) == 0 &&
len == strlen(*list))
return (1);
list++;
}
return (0);
}
/*
* Scrub the environment by applying a "whitelist" of safe variables
* and a "blacklist" of known dangerous variables. Each environment
* variable is examined and is retained only if it appears in a whitelist
* and does not appear in the blacklist.
*
* If the first argument is NULL, a built-in whitelist will be used.
* The second and third arguments allow clients to adjust the built-in
* whitelist without having to replicate it.
*
*/
void
clean_environment(const char * const *whitelist,
const char * const *extra_whitelist)
{
extern char **environ;
char *p, **new, **old;
int len;
int safe;
old = environ;
new = environ;
if (whitelist == NULL)
whitelist = default_whitelist;
while (*old != NULL) {
safe = 0;
p = strchr(*old, '=');
if (p != NULL)
len = p - *old;
else
len = strlen(*old);
if (env_var_in_list(whitelist, *old, len) ||
env_var_in_list(extra_whitelist, *old, len))
*new++ = *old;
old++;
}
while (*new != NULL)
*new++ = NULL;
}
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