From bb458c644a59dbba3a1fe59b27106c5e68e1c4bd Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 13 Jul 2013 13:26:37 +0400
Subject: [PATCH] Safer ABI for O_TMPFILE

[suggested by Rasmus Villemoes] make O_DIRECTORY | O_RDWR part of O_TMPFILE;
that will fail on old kernels in a lot more cases than what I came up with.
And make sure O_CREAT doesn't get there...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/alpha/include/uapi/asm/fcntl.h  | 2 +-
 arch/parisc/include/uapi/asm/fcntl.h | 2 +-
 arch/sparc/include/uapi/asm/fcntl.h  | 2 +-
 fs/namei.c                           | 2 +-
 fs/open.c                            | 4 ++--
 include/uapi/asm-generic/fcntl.h     | 8 ++++++--
 6 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/alpha/include/uapi/asm/fcntl.h b/arch/alpha/include/uapi/asm/fcntl.h
index dfdadb0b4bef..09f49a6b87d1 100644
--- a/arch/alpha/include/uapi/asm/fcntl.h
+++ b/arch/alpha/include/uapi/asm/fcntl.h
@@ -32,7 +32,7 @@
 #define O_SYNC		(__O_SYNC|O_DSYNC)
 
 #define O_PATH		040000000
-#define O_TMPFILE	0100000000
+#define __O_TMPFILE	0100000000
 
 #define F_GETLK		7
 #define F_SETLK		8
diff --git a/arch/parisc/include/uapi/asm/fcntl.h b/arch/parisc/include/uapi/asm/fcntl.h
index cc61c475f277..34a46cbc76ed 100644
--- a/arch/parisc/include/uapi/asm/fcntl.h
+++ b/arch/parisc/include/uapi/asm/fcntl.h
@@ -20,7 +20,7 @@
 #define O_INVISIBLE	004000000 /* invisible I/O, for DMAPI/XDSM */
 
 #define O_PATH		020000000
-#define O_TMPFILE	040000000
+#define __O_TMPFILE	040000000
 
 #define F_GETLK64	8
 #define F_SETLK64	9
diff --git a/arch/sparc/include/uapi/asm/fcntl.h b/arch/sparc/include/uapi/asm/fcntl.h
index d73e5e008b0d..7e8ace5bf760 100644
--- a/arch/sparc/include/uapi/asm/fcntl.h
+++ b/arch/sparc/include/uapi/asm/fcntl.h
@@ -35,7 +35,7 @@
 #define O_SYNC		(__O_SYNC|O_DSYNC)
 
 #define O_PATH		0x1000000
-#define O_TMPFILE	0x2000000
+#define __O_TMPFILE	0x2000000
 
 #define F_GETOWN	5	/*  for sockets. */
 #define F_SETOWN	6	/*  for sockets. */
diff --git a/fs/namei.c b/fs/namei.c
index b2beee7a733f..8b61d103a8a7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2977,7 +2977,7 @@ static struct file *path_openat(int dfd, struct filename *pathname,
 
 	file->f_flags = op->open_flag;
 
-	if (unlikely(file->f_flags & O_TMPFILE)) {
+	if (unlikely(file->f_flags & __O_TMPFILE)) {
 		error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened);
 		goto out;
 	}
diff --git a/fs/open.c b/fs/open.c
index fca72c4d3f17..9156cb050d08 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -840,8 +840,8 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o
 	if (flags & __O_SYNC)
 		flags |= O_DSYNC;
 
-	if (flags & O_TMPFILE) {
-		if (!(flags & O_CREAT))
+	if (flags & __O_TMPFILE) {
+		if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
 			return -EINVAL;
 		acc_mode = MAY_OPEN | ACC_MODE(flags);
 	} else if (flags & O_PATH) {
diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h
index 06632beaa6d5..05ac354e124d 100644
--- a/include/uapi/asm-generic/fcntl.h
+++ b/include/uapi/asm-generic/fcntl.h
@@ -84,10 +84,14 @@
 #define O_PATH		010000000
 #endif
 
-#ifndef O_TMPFILE
-#define O_TMPFILE	020000000
+#ifndef __O_TMPFILE
+#define __O_TMPFILE	020000000
 #endif
 
+/* a horrid kludge trying to make sure that this will fail on old kernels */
+#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY | O_RDWR)
+#define O_TMPFILE_MASK (__O_TMPFILE | O_DIRECTORY | O_CREAT | O_ACCMODE)      
+
 #ifndef O_NDELAY
 #define O_NDELAY	O_NONBLOCK
 #endif
-- 
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