isatty() is used by stdio to determine the buffering mode. Add a F_ISATTY

option to fcntl(), so that isatty() can use this rather than than the bloated
ioctl() interface.  Reducing uses of ioctl() by libc makes it easier to
constrain programs with various kinds of systrace sandboxes.
ok guenther, previously discussed as a concept with nicm

diff --git a/lib/libc/gen/isatty.c b/lib/libc/gen/isatty.c
index 0a94648..3b63f25 100644 (file)
--- a/lib/libc/gen/isatty.c
+++ b/lib/libc/gen/isatty.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: isatty.c,v 1.8 2013/04/17 17:40:35 tedu Exp $ */
+/*     $OpenBSD: isatty.c,v 1.9 2015/05/17 01:22:01 deraadt Exp $ */
 /*
  * Copyright (c) 1988, 1993
  *     The Regents of the University of California.  All rights reserved.
@@ -28,13 +28,10 @@
  * SUCH DAMAGE.
  */
 
-#include <termios.h>
-#include <unistd.h>
+#include <fcntl.h>
 
 int
 isatty(int fd)
 {
-       struct termios t;
-
-       return (tcgetattr(fd, &t) != -1);
+       return (fcntl(fd, F_ISATTY));
 }

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 93d6a9c..76b8542 100644 (file)
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_descrip.c,v 1.119 2015/04/30 21:18:45 millert Exp $      */
+/*     $OpenBSD: kern_descrip.c,v 1.120 2015/05/17 01:22:01 deraadt Exp $      */
 /*     $NetBSD: kern_descrip.c,v 1.42 1996/03/30 22:24:38 christos Exp $       */
 
 /*
@@ -397,6 +397,16 @@ restart:
                *retval = OFLAGS(fp->f_flag);
                break;
 
+       case F_ISATTY:
+               vp = (struct vnode *)fp->f_data;
+               if (fp->f_type == DTYPE_VNODE && (vp->v_flag & VISTTY))
+                       *retval = 1;
+               else {
+                       *retval = 0;
+                       error = ENOTTY;
+               }
+               break;
+
        case F_SETFL:
                fp->f_flag &= ~FCNTLFLAGS;
                fp->f_flag |= FFLAGS((long)SCARG(uap, arg)) & FCNTLFLAGS;

diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h
index 47b7219..b08dcc7 100644 (file)
--- a/sys/sys/fcntl.h
+++ b/sys/sys/fcntl.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: fcntl.h,v 1.20 2013/06/05 01:26:00 guenther Exp $     */
+/*     $OpenBSD: fcntl.h,v 1.21 2015/05/17 01:22:01 deraadt Exp $      */
 /*     $NetBSD: fcntl.h,v 1.8 1995/03/26 20:24:12 jtc Exp $    */
 
 /*-
@@ -155,6 +155,9 @@
 #if __POSIX_VISIBLE >= 200809
 #define        F_DUPFD_CLOEXEC 10              /* duplicate with FD_CLOEXEC set */
 #endif
+#if __BSD_VISIBLE
+#define F_ISATTY       11              /* used by isatty(3) */
+#endif
 
 /* file descriptor flags (F_GETFD, F_SETFD) */
 #define        FD_CLOEXEC      1               /* close-on-exec flag */

diff --git a/usr.bin/kdump/mksubr b/usr.bin/kdump/mksubr
index 57680a0..709e464 100644 (file)
--- a/usr.bin/kdump/mksubr
+++ b/usr.bin/kdump/mksubr
@@ -1,5 +1,5 @@
 #!/bin/sh
-# $OpenBSD: mksubr,v 1.27 2015/04/17 06:14:36 guenther Exp $
+# $OpenBSD: mksubr,v 1.28 2015/05/17 01:22:01 deraadt Exp $
 #
 # Copyright (c) 2006 David Kirchner <dpk@dpk.net>
 #
@@ -394,7 +394,7 @@ cat <<_EOF_
        } else if (arg1 == F_SETFL) {
                (void)putchar(',');
                doflagsname(arg, 0);
-       } else if (!fancy || (arg1 != F_GETFD && arg1 != F_GETFL))
+       } else if (!fancy || (arg1 != F_GETFD && arg1 != F_GETFL && arg1 != F_ISATTY))
                (void)printf(",%#x", arg);
 }