[RFC PATCH] btrfs: drop file privileges in btrfs_clone_files

[Lu Fengqi]

The generic/513 tell that cloning into a file did not strip security
privileges (suid, capabilities) like a regular write would.

Signed-off-by: Lu Fengqi <lufq.f...@cn.fujitsu.com>
---
The xfs and ocfs2 call generic_remap_file_range_prep to drop file
privileges, I'm not sure whether btrfs should do the same thing.

Any suggestion?

 fs/btrfs/ioctl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 410c7e007ba8..bc33c480603b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4312,6 +4312,10 @@ static noinline int btrfs_clone_files(struct file *file, 
struct file *file_src,
                        goto out_unlock;
        }
 
+       ret = file_remove_privs(file);
+       if (ret)
+               goto out_unlock;
+
        if (destoff > inode->i_size) {
                ret = btrfs_cont_expand(inode, inode->i_size, destoff);
                if (ret)
-- 
2.19.2