libc: Use O_CLOEXEC for various internal file descriptors.

This fixes a race condition where another thread may fork() before CLOEXEC
is set, unintentionally passing the descriptor to the child process.

This commit only adds O_CLOEXEC flags to open() or openat() calls where no
fcntl(fd, F_SETFD, FD_CLOEXEC) follows. The separate fcntl() call still
leaves a race window so it should be fixed later.

lib/libc/gen/arc4random.c

@@ -153,7 +153,7 @@ arc4_stir(void)
 	if (arc4_sysctl((u_char *)&rdat, KEYSIZE) == KEYSIZE)
 		done = 1;
 	if (!done) {
-		fd = _open(RANDOMDEV, O_RDONLY, 0);
+		fd = _open(RANDOMDEV, O_RDONLY | O_CLOEXEC, 0);
 		if (fd >= 0) {
 			if (_read(fd, &rdat, KEYSIZE) == KEYSIZE)
 				done = 1;

lib/libc/gen/getcap.c

@@ -264,7 +264,7 @@ getent(char **cap, u_int *len, char **db_array, int fd, const char *name,
 				*cap = cbuf;
 				return (retval);
 			} else {
-				fd = _open(*db_p, O_RDONLY, 0);
+				fd = _open(*db_p, O_RDONLY | O_CLOEXEC, 0);
 				if (fd < 0)
 					continue;
 				myfd = 1;

lib/libc/gen/getcwd.c

@@ -142,7 +142,7 @@ getcwd(pt, size)
 
 		/* Open and stat parent directory. */
 		fd = _openat(dir != NULL ? _dirfd(dir) : AT_FDCWD,
-				"..", O_RDONLY);
+				"..", O_RDONLY | O_CLOEXEC);
 		if (fd == -1)
 			goto err;
 		if (dir)

lib/libc/gen/nlist.c

@@ -66,7 +66,7 @@ nlist(name, list)
 {
 	int fd, n;
 
-	fd = _open(name, O_RDONLY, 0);
+	fd = _open(name, O_RDONLY | O_CLOEXEC, 0);
 	if (fd < 0)
 		return (-1);
 	n = __fdnlist(fd, list);

lib/libc/gen/opendir.c

@@ -199,7 +199,8 @@ __opendir_common(int fd, const char *name, int flags)
 		 * which has also been read -- see fts.c.
 		 */
 		if (flags & DTF_REWIND) {
-			if ((fd2 = _open(name, O_RDONLY | O_DIRECTORY)) == -1) {
+			if ((fd2 = _open(name, O_RDONLY | O_DIRECTORY |
+			    O_CLOEXEC)) == -1) {
 				saved_errno = errno;
 				free(buf);
 				free(dirp);

lib/libc/gen/pututxline.c

@@ -47,7 +47,7 @@ futx_open(const char *file)
 	struct stat sb;
 	int fd;
 
-	fd = _open(file, O_CREAT|O_RDWR|O_EXLOCK, 0644);
+	fd = _open(file, O_CREAT|O_RDWR|O_EXLOCK|O_CLOEXEC, 0644);
 	if (fd < 0)
 		return (NULL);
 
@@ -235,7 +235,7 @@ utx_lastlogin_upgrade(void)
 	struct stat sb;
 	int fd;
 
-	fd = _open(_PATH_UTX_LASTLOGIN, O_RDWR, 0644);
+	fd = _open(_PATH_UTX_LASTLOGIN, O_RDWR|O_CLOEXEC, 0644);
 	if (fd < 0)
 		return;
 
@@ -269,7 +269,7 @@ utx_log_add(const struct futx *fu)
 	vec[1].iov_len = l;
 	l = htobe16(l);
 
-	fd = _open(_PATH_UTX_LOG, O_CREAT|O_WRONLY|O_APPEND, 0644);
+	fd = _open(_PATH_UTX_LOG, O_CREAT|O_WRONLY|O_APPEND|O_CLOEXEC, 0644);
 	if (fd < 0)
 		return (-1);
 	if (_writev(fd, vec, 2) == -1)

lib/libc/gen/readpassphrase.c

@@ -68,7 +68,7 @@ readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags)
 	 * stdin and write to stderr unless a tty is required.
 	 */
 	if ((flags & RPP_STDIN) ||
-	    (input = output = _open(_PATH_TTY, O_RDWR)) == -1) {
+	    (input = output = _open(_PATH_TTY, O_RDWR | O_CLOEXEC)) == -1) {
 		if (flags & RPP_REQUIRE_TTY) {
 			errno = ENOTTY;
 			return(NULL);

lib/libc/gen/sem_new.c

@@ -198,7 +198,7 @@ _sem_open(const char *name, int flags, ...)
 		goto error;
 	}
 
-	fd = _open(path, flags|O_RDWR, mode);
+	fd = _open(path, flags|O_RDWR|O_CLOEXEC, mode);
 	if (fd == -1)
 		goto error;
 	if (flock(fd, LOCK_EX) == -1)

lib/libc/gen/syslog.c

@@ -300,7 +300,8 @@ vsyslog(int pri, const char *fmt, va_list ap)
 	 * Make sure the error reported is the one from the syslogd failure.
 	 */
 	if (LogStat & LOG_CONS &&
-	    (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK, 0)) >= 0) {
+	    (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK|O_CLOEXEC, 0)) >=
+	    0) {
 		struct iovec iov[2];
 		struct iovec *v = iov;
 

lib/libc/locale/ldpart.c

@@ -87,7 +87,7 @@ __part_load_locale(const char *name,
 	strcat(filename, name);
 	strcat(filename, "/");
 	strcat(filename, category_filename);
-	if ((fd = _open(filename, O_RDONLY)) < 0)
+	if ((fd = _open(filename, O_RDONLY | O_CLOEXEC)) < 0)
 		return (_LDP_ERROR);
 	if (_fstat(fd, &st) != 0)
 		goto bad_locale;

lib/libc/nls/msgcat.c

@@ -384,7 +384,7 @@ load_msgcat(const char *path, const char *name, const char *lang)
 	}
 	UNLOCK;
 
-	if ((fd = _open(path, O_RDONLY)) == -1) {
+	if ((fd = _open(path, O_RDONLY | O_CLOEXEC)) == -1) {
 		SAVEFAIL(name, lang, errno);
 		NLRETERR(errno);
 	}

lib/libc/stdlib/rand.c

@@ -121,7 +121,7 @@ sranddev()
 	int fd, done;
 
 	done = 0;
-	fd = _open("/dev/random", O_RDONLY, 0);
+	fd = _open("/dev/random", O_RDONLY | O_CLOEXEC, 0);
 	if (fd >= 0) {
 		if (_read(fd, (void *) &next, sizeof(next)) == sizeof(next))
 			done = 1;

lib/libc/stdlib/random.c

@@ -303,7 +303,7 @@ srandomdev(void)
 		len = rand_deg * sizeof state[0];
 
 	done = 0;
-	fd = _open("/dev/random", O_RDONLY, 0);
+	fd = _open("/dev/random", O_RDONLY | O_CLOEXEC, 0);
 	if (fd >= 0) {
 		if (_read(fd, (void *) state, len) == (ssize_t) len)
 			done = 1;

lib/libc/yp/yplib.c

@@ -375,7 +375,7 @@ _yp_dobind(char *dom, struct dom_binding **ypdb)
 			ysd->dom_socket = -1;
 		}
 		snprintf(path, sizeof(path), "%s/%s.%d", BINDINGDIR, dom, 2);
-		if ((fd = _open(path, O_RDONLY)) == -1) {
+		if ((fd = _open(path, O_RDONLY | O_CLOEXEC)) == -1) {
 			/* no binding file, YP is dead. */
 			/* Try to bring it back to life. */
 			_close(fd);