linux-kernel - [PATCH 4.9 100/105] vfs: deny copy_file

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Date:   Tue, 10 Oct 2017 21:51:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, linux-api@...r.kernel.org,
        Al Viro <viro@...iv.linux.org.uk>,
        Amir Goldstein <amir73il@...il.com>,
        Christoph Hellwig <hch@....de>,
        Miklos Szeredi <mszeredi@...hat.com>,
        Theodore Tso <tytso@....edu>
Subject: [PATCH 4.9 100/105] vfs: deny copy_file_range() for non regular files

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Amir Goldstein <amir73il@...il.com>

commit 11cbfb10775aa2a01cee966d118049ede9d0bdf2 upstream.

There is no in-tree file system that implements copy_file_range()
for non regular files.

Deny an attempt to copy_file_range() a directory with EISDIR
and any other non regualr file with EINVAL to conform with
behavior of vfs_{clone,dedup}_file_range().

This change is needed prior to converting sb_start_write()
to  file_start_write() in the vfs helper.

Cc: linux-api@...r.kernel.org
Cc: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@...il.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Cc: Theodore Ts'o <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/read_write.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1518,6 +1518,11 @@ ssize_t vfs_copy_file_range(struct file
 	if (flags != 0)
 		return -EINVAL;
 
+	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
+		return -EISDIR;
+	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
+		return -EINVAL;
+
 	ret = rw_verify_area(READ, file_in, &pos_in, len);
 	if (unlikely(ret))
 		return ret;