stun

commit 30f0119c50248150d08503521b0720cad6139b52
parent bc3131cc03e573ebd79dbc9ed6867eb678c6bd2c
Author: sin <sin@2f30.org>
Date:   Tue, 29 Mar 2016 08:47:30 +0100

revoke privileges

Diffstat:
M
stun.c
 | 
17
+++++++++++++++++

1 file changed, 17 insertions(+), 0 deletions(-)
diff --git a/stun.c b/stun.c
@@ -21,6 +21,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <poll.h>
+#include <pwd.h>
 #include <signal.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -41,6 +42,7 @@
 #define explicit_bzero bzero
 #endif
 
+#define NOPRIVUSER	"nobody"
 #define CHALLENGETIMEO	1  /* in seconds */
 #define RECONNECTTIMEO	60 /* in seconds */
 #define HDRLEN		2
@@ -674,6 +676,20 @@ daemonize(void)
 }
 
 void
+revokeprivs(void)
+{
+	struct passwd *pw;
+
+	pw = getpwnam(NOPRIVUSER);
+	if (!pw)
+		logerr("no %s user", NOPRIVUSER);
+	if (setgroups(1, &pw->pw_gid) ||
+	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
+	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
+		logerr("failed to revoke privs");
+}
+
+void
 usage(void)
 {
 	fprintf(stderr, "usage: stun [-df] -s [-p port] [-t type] interface\n");
@@ -724,6 +740,7 @@ main(int argc, char *argv[])
 	openlog("stun", LOG_PID | LOG_NDELAY, LOG_DAEMON);
 
 	devfd = opendev(argv[0]);
+	revokeprivs();
 
 	pw = getenv("STUNPW");
 	if (!pw)