From f0b5b76ae1bb6285bef428dc271caf7b927eec68 Mon Sep 17 00:00:00 2001
From: Theo de Raadt <deraadt@cvs.openbsd.org>
Date: Fri, 24 Oct 1997 09:04:28 +0000
Subject: prevent open() with wrong flags

---
 lib/libc/sys/open.2  |  2 ++
 sys/kern/vfs_vnops.c |  4 +++-
 sys/sys/fcntl.h      | 11 +++++++----
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/lib/libc/sys/open.2 b/lib/libc/sys/open.2
index 8b76371e021..4716156aa92 100644
--- a/lib/libc/sys/open.2
+++ b/lib/libc/sys/open.2
@@ -180,6 +180,8 @@ Too many symbolic links were encountered in translating the pathname.
 .It Bq Er EISDIR
 The named file is a directory, and the arguments specify
 it is to be opened for writing.
+.It Bq Er EINVAL
+The flags specified for opening the file are not valid.
 .It Bq Er EROFS
 The named file resides on a read-only file system,
 and the file is to be modified.
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index 2dc3f778374..ee781e8d79d 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_vnops.c,v 1.7 1997/10/06 20:20:15 deraadt Exp $	*/
+/*	$OpenBSD: vfs_vnops.c,v 1.8 1997/10/24 09:04:26 deraadt Exp $	*/
 /*	$NetBSD: vfs_vnops.c,v 1.20 1996/02/04 02:18:41 christos Exp $	*/
 
 /*
@@ -74,6 +74,8 @@ vn_open(ndp, fmode, cmode)
 	struct vattr va;
 	int error;
 
+	if ((fmode & (FREAD|FWRITE)) == 0)
+		return (EINVAL);
 	if (fmode & O_CREAT) {
 		ndp->ni_cnd.cn_nameiop = CREATE;
 		ndp->ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF;
diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h
index da92fd3c6ce..8b72150e986 100644
--- a/sys/sys/fcntl.h
+++ b/sys/sys/fcntl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fcntl.h,v 1.3 1996/11/03 06:35:20 deraadt Exp $	*/
+/*	$OpenBSD: fcntl.h,v 1.4 1997/10/24 09:04:24 deraadt Exp $	*/
 /*	$NetBSD: fcntl.h,v 1.8 1995/03/26 20:24:12 jtc Exp $	*/
 
 /*-
@@ -100,9 +100,12 @@
 #define	O_NOCTTY	0x8000		/* don't assign controlling terminal */
 
 #ifdef _KERNEL
-/* convert from open() flags to/from fflags; convert O_RD/WR to FREAD/FWRITE */
-#define	FFLAGS(oflags)	((oflags) + 1)
-#define	OFLAGS(fflags)	((fflags) - 1)
+/*
+ * convert from open() flags to/from fflags; convert O_RD/WR to FREAD/FWRITE.
+ * For out-of-range values for the flags, be slightly careful (but lossy).
+ */
+#define	FFLAGS(oflags)	(((oflags) & ~O_ACCMODE) | (((oflags) + 1) & O_ACCMODE))
+#define	OFLAGS(fflags)	(((fflags) & ~O_ACCMODE) | (((fflags) - 1) & O_ACCMODE))
 
 /* bits to save after open */
 #define	FMASK		(FREAD|FWRITE|FAPPEND|FASYNC|FFSYNC|FNONBLOCK)
-- 
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