Patch "ovl: handle ATTR_KILL*" has been added to the 4.6-stable tree

Patch "ovl: handle ATTR_KILL*" has been added to the 4.6-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ovl: handle ATTR_KILL*

to the 4.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ovl-handle-attr_kill.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b99c2d913810e56682a538c9f2394d76fca808f8 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Mon, 4 Jul 2016 16:49:48 +0200
Subject: ovl: handle ATTR_KILL*

From: Miklos Szeredi <mszeredi@redhat.com>

commit b99c2d913810e56682a538c9f2394d76fca808f8 upstream.

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")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/overlayfs/inode.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -80,6 +80,9 @@ int ovl_setattr(struct dentry *dentry, s
 				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)


Patches currently in stable-queue which might be from mszeredi@redhat.com are

queue-4.6/ovl-copy-up-underlying-inode-s-i_mode-to-overlay-inode.patch
queue-4.6/ovl-verify-upper-dentry-in-ovl_remove_and_whiteout.patch
queue-4.6/ovl-fix-dentry-leak-for-default_permissions.patch
queue-4.6/ovl-get_write_access-in-truncate.patch
queue-4.6/ovl-handle-attr_kill.patch
queue-4.6/vfs-add-d_real_inode-helper.patch
queue-4.6/af_unix-fix-hard-linked-sockets-on-overlay.patch