1 /* Look up an environment variable, returning NULL in insecure situations.
2
3 Copyright 2013-2021 Free Software Foundation, Inc.
4
5 This file is free software: you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 of the
8 License, or (at your option) any later version.
9
10 This file 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
13 GNU Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18 #include <config.h>
19
20 #include <stdlib.h>
21
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
27
28 char *
29 secure_getenv (char const *name)
/* ![[previous]](../icons/n_left.png)
![[next]](../icons/n_right.png)
![[first]](../icons/n_first.png)
![[last]](../icons/n_last.png)
![[top]](../icons/top.png)
![[bottom]](../icons/bottom.png)
![[index]](../icons/index.png)
*/
30 {
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 __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
54 }