linux-kernel - Re: [patch 06/14] hfsplus: remove hfsplus

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Date:	Thu, 22 May 2008 14:37:21 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	zippel@...ux-m68k.org
CC:	miklos@...redi.hu, linux-fsdevel@...r.kernel.org,
	hch@...radead.org, viro@...IV.linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 06/14] hfsplus: remove hfsplus_permission()

> > > That check didn't used to be there and that the HFS+ check is older than 
> > > that might have given you the idea that it at least used to work.
> > > So now the only way for a fs to differentiate between lookup and exec is 
> > > gone... :-(
> > 
> > That check was added quite some time ago:
> > 
> >    commit a343bb7750e6a098909c34f5c5dfddbc4fa40053
> >    Author: Trond Myklebust <Trond.Myklebust@...app.com>
> >    Date:   Tue Aug 22 20:06:03 2006 -0400
> >    
> >        VFS: Fix access("file", X_OK) in the presence of ACLs
> > 
> > Also it sounds just plain wrong to allow execution without an x bit.
> > It could cause nasty surprises at least.  What was the intended
> > purpose of that code, and why did nobody notice when it stopped
> > working?
> 
> As I said to allow lookup on files.

That requires a quite bit more support from the VFS than just allowing
lookup to work on regular files without x bits.  You'll have big
trouble with hard links for example: the VFS doesn't like non-leaf
dentries to be aliased.

Besides hfsplus_permission() did not differentiate between execve on
the file and lookup on that file, allowing both.  Which is obviously
wrong.

Miklos
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