2004-03-13  Dmitry V. Levin  <ldv@altlinux.org>

	Improve chroot jailing support.
	* common/common.c:
	(become_user): Moved initgroups call from here ...
	(get_user_pwent): ... to here.
	(chroot_start): Call tzset(3) before chroot(2) call.
	Preopen /dev/null before chroot(2) call ...
	(background): ... and use the descriptor for redirection.
	(background): Do not close standard descriptors in parent process.

--- nut-2.0.0/common/common.c.orig	2004-03-08 15:09:54 +0300
+++ nut-2.0.0/common/common.c	2004-04-04 23:53:38 +0400
@@ -26,6 +26,7 @@
 
 	int	nut_debug_level = 0;
 	static	int	upslog_flags = UPSLOG_STDERR;
+	static	int	null_fd = -1;
 
 static void xbit_set(int *val, int flag)
 {
@@ -66,28 +67,29 @@
 /* close ttys and become a daemon */
 void background(void)
 {
-	int	pid;
+	int fd;
+	pid_t	pid;
 
 	if ((pid = fork()) < 0)
 		fatal("Unable to enter background");
 
-	xbit_set(&upslog_flags, UPSLOG_SYSLOG);
-	xbit_clear(&upslog_flags, UPSLOG_STDERR);
-
-	close(0);
-	close(1);
-	close(2);
-
 	if (pid != 0) 
 		_exit(EXIT_SUCCESS);		/* parent */
 
 	/* child */
 
+	xbit_set(&upslog_flags, UPSLOG_SYSLOG);
+	xbit_clear(&upslog_flags, UPSLOG_STDERR);
+
 	/* make fds 0-2 point somewhere defined */
-	if (open("/dev/null", O_RDWR) != 0)
+	if ((null_fd < 0) && ((null_fd = open("/dev/null", O_RDWR)) < 0))
 		fatal("open /dev/null");
-	dup(0);
-	dup(0);
+	for (fd = 0; fd<= 2; ++fd)
+		if ((null_fd != fd) && (dup2(null_fd, fd) < 0))
+			fatal("dup2 /dev/null");
+	if ((null_fd > 2) && (close(null_fd) < 0))
+		fatal("close /dev/null");
+	null_fd = -1;
 
 #ifdef HAVE_SETSID
 	setsid();		/* make a new session to dodge signals */
@@ -99,7 +101,12 @@
 /* do this here to keep pwd/grp stuff out of the main files */
 struct passwd *get_user_pwent(const char *name)
 {
-	return getpwnam(name);
+	struct passwd *pw = getpwnam(name);
+
+	if (pw && !geteuid() && initgroups(pw->pw_name, pw->pw_gid) == -1)
+		fatal("initgroups");
+
+	return pw;
 }
 
 /* change to the user defined in the struct */
@@ -113,9 +120,6 @@ void become_user(struct passwd *pw)
 		if (seteuid(0))
 			fatal("getuid gave 0, but seteuid(0) failed");
 
-	if (initgroups(pw->pw_name, pw->pw_gid) == -1)
-		fatal("initgroups");
-
 	if (setgid(pw->pw_gid) == -1)
 		fatal("setgid");
 
@@ -126,6 +130,11 @@
 /* drop down into a directory and throw away pointers to the old path */
 void chroot_start(const char *path)
 {
+	tzset();
+	
+	if ((null_fd = open("/dev/null", O_RDWR)) < 0)
+		fatal("open /dev/null");
+
 	if (chdir(path))
 		fatal("chdir(%s)", path);