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-rw-r--r--lib/secure_getenv.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/lib/secure_getenv.c b/lib/secure_getenv.c
new file mode 100644
index 0000000..4e4ebc9
--- /dev/null
+++ b/lib/secure_getenv.c
@@ -0,0 +1,54 @@
+/* Look up an environment variable, returning NULL in insecure situations.
+
+ Copyright 2013-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+#if !HAVE___SECURE_GETENV
+# if HAVE_ISSETUGID || (HAVE_GETUID && HAVE_GETEUID && HAVE_GETGID && HAVE_GETEGID)
+# include <unistd.h>
+# endif
+#endif
+
+char *
+secure_getenv (char const *name)
+{
+#if HAVE___SECURE_GETENV /* glibc */
+ return __secure_getenv (name);
+#elif HAVE_ISSETUGID /* OS X, FreeBSD, NetBSD, OpenBSD */
+ if (issetugid ())
+ return NULL;
+ return getenv (name);
+#elif HAVE_GETUID && HAVE_GETEUID && HAVE_GETGID && HAVE_GETEGID /* other Unix */
+ if (geteuid () != getuid () || getegid () != getgid ())
+ return NULL;
+ return getenv (name);
+#elif defined _WIN32 && ! defined __CYGWIN__ /* native Windows */
+ /* On native Windows, there is no such concept as setuid or setgid binaries.
+ - Programs launched as system services have high privileges, but they don't
+ inherit environment variables from a user.
+ - Programs launched by a user with "Run as Administrator" have high
+ privileges and use the environment variables, but the user has been asked
+ whether he agrees.
+ - Programs launched by a user without "Run as Administrator" cannot gain
+ high privileges, therefore there is no risk. */
+ return getenv (name);
+#else
+ return NULL;
+#endif
+}