; Merge from origin/emacs-25
[emacs.git] / lib / secure_getenv.c
blob88a60dc33c3787d4edb54ca3aa1fada76f72cc5b
1 /* Look up an environment variable, returning NULL in insecure situations.
3 Copyright 2013-2016 Free Software Foundation, Inc.
5 This program is free software: you can redistribute it and/or modify it
6 under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 #include <config.h>
20 #include <stdlib.h>
22 #if !HAVE___SECURE_GETENV
23 # if HAVE_ISSETUGID || (HAVE_GETUID && HAVE_GETEUID && HAVE_GETGID && HAVE_GETEGID)
24 # include <unistd.h>
25 # endif
26 #endif
28 char *
29 secure_getenv (char const *name)
31 #if HAVE___SECURE_GETENV /* glibc */
32 return __secure_getenv (name);
33 #elif HAVE_ISSETUGID /* OS X, FreeBSD, NetBSD, OpenBSD */
34 if (issetugid ())
35 return NULL;
36 return getenv (name);
37 #elif HAVE_GETUID && HAVE_GETEUID && HAVE_GETGID && HAVE_GETEGID /* other Unix */
38 if (geteuid () != getuid () || getegid () != getgid ())
39 return NULL;
40 return getenv (name);
41 #elif (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ /* native Windows */
42 /* On native Windows, there is no such concept as setuid or setgid binaries.
43 - Programs launched as system services have high privileges, but they don't
44 inherit environment variables from a user.
45 - Programs launched by a user with "Run as Administrator" have high
46 privileges and use the environment variables, but the user has been asked
47 whether he agrees.
48 - Programs launched by a user without "Run as Administrator" cannot gain
49 high privileges, therefore there is no risk. */
50 return getenv (name);
51 #else
52 return NULL;
53 #endif