ovl: handle ATTR_KILL*
Before 4bacc9c9234c ("overlayfs: Make f_path...") file->f_path pointed to
the underlying file, hence suid/sgid removal on write worked fine.
After that patch file->f_path pointed to the overlay file, and the file
mode bits weren't copied to overlay_inode->i_mode. So the suid/sgid
removal simply stopped working.
The fix is to copy the mode bits, but then ovl_setattr() needs to clear
ATTR_MODE to avoid the BUG() in notify_change(). So do this first, then in
the next patch copy the mode.
Reported-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Cc: <stable@vger.kernel.org>
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index c831c2e..1233992 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -80,6 +80,9 @@
goto out_drop_write;
}
+ if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
+ attr->ia_valid &= ~ATTR_MODE;
+
inode_lock(upperdentry->d_inode);
err = notify_change(upperdentry, attr, NULL);
if (!err)
