From 741ab25b1f609f4ca11429b99811c4a427c60024 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 07 Jan 2017 19:14:29 +0100
Subject: [PATCH] splice: introduce FMODE_SPLICE_READ and FMODE_SPLICE_WRITE

Introduce FMODE_SPLICE_READ and FMODE_SPLICE_WRITE. These modes check
whether it is legal to read or write a file using splice. Both get
automatically set on regular files and are not checked when a 'struct
fileoperations' includes the splice_{read,write} methods.

Change-Id: Ice6a3fab20bf0ac131f8d908f4bb0f7dc34bf4e3
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
---

diff --git a/fs/open.c b/fs/open.c
index 4c28c4f..7512d8a 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -683,6 +683,10 @@
 		return f;
 	}
 
+	if (S_ISREG(inode->i_mode))
+		f->f_mode |= FMODE_SPLICE_WRITE | FMODE_SPLICE_READ;
+
+
 	f->f_op = fops_get(inode->i_fop);
 
 	error = security_dentry_open(f, cred);
diff --git a/fs/splice.c b/fs/splice.c
index ea85353..bf597dc5 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -376,6 +376,9 @@
 		index++;
 	}
 
+	if (unlikely(!(in->f_mode & FMODE_SPLICE_READ)))
+		return -EINVAL;
+
 	/*
 	 * Now loop over the map and see if we need to start IO on any
 	 * pages, fill in the partial map, etc.
@@ -1059,6 +1062,9 @@
 {
 	ssize_t ret;
 
+	if (unlikely(!(out->f_mode & FMODE_SPLICE_WRITE)))
+		return -EINVAL;
+
 	ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
 	if (ret > 0)
 		*ppos += ret;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0e03633..ef0590d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -117,6 +117,11 @@
 /* File was opened by fanotify and shouldn't generate fanotify events */
 #define FMODE_NONOTIFY		((__force fmode_t)0x1000000)
 
+/* File can be read using splice */
+#define FMODE_SPLICE_READ       ((__force fmode_t)0x8000000)
+/* File can be written using splice */
+#define FMODE_SPLICE_WRITE      ((__force fmode_t)0x10000000)
+
 /*
  * The below are the various read and write types that we support. Some of
  * them include behavioral modifiers that send information down to the