linux-kernel - Re: [PATCH 6/7] vfs: only add " (deleted)" where necessary

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Message-Id: <E1OfvDK-0003fw-WD@pomaz-ex.szeredi.hu>
Date:	Mon, 02 Aug 2010 15:37:58 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	Bastien ROUCARIES <roucaries.bastien@...il.com>
CC:	Valdis.Kletnieks@...edu, miklos@...redi.hu,
	viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/7] vfs: only add " (deleted)" where necessary

On Mon, 2 Aug 2010, Bastien ROUCARIES wrote:
> On Mon, Aug 2, 2010 at 3:00 PM,  <Valdis.Kletnieks@...edu> wrote:
> > On Mon, 02 Aug 2010 13:20:01 +0200, Miklos Szeredi said:
> >
> >> Index: linux-2.6/fs/dcache.c
> >> ===================================================================
> >> --- linux-2.6.orig/fs/dcache.c        2010-07-06 18:08:16.000000000 +0200
> >> +++ linux-2.6/fs/dcache.c     2010-07-06 18:08:19.000000000 +0200
> >> @@ -1977,8 +1977,7 @@ global_root:
> >>   * @buffer: buffer to return value in
> >>   * @buflen: buffer length
> >>   *
> >> - * Convert a dentry into an ASCII path name. If the entry has been deleted
> >> - * the string " (deleted)" is appended. Note that this is ambiguous.
> >> + * Convert a dentry into an ASCII path name.
> >>   *
> >>   * Returns a pointer into the buffer or an error code if the
> >>   * path was too long.
> >
> > I'd prefer the comment about it being ambiguous remain.  I'm waiting to see how
> > long it takes for somebody to create a security hole by creating a file called
> > '/etc/some/thing/important (deleted)' and having some software Do The Wrong
> > Thing instead to /etc/some/thing/important.
> >
> 
> In order to close this kind of hole why not creating a deleted
> directory on /proc and redirect symbolic link to this directory.
> And do the same for unreachable. If we use the good permission it will
> work from a backaward compatibily point of view

Unfortunately the "(deleted)" thing is part of the userspace ABI and
can't be changed.

The only thing we can do is make sure new interfaces use a saner
convention.

Thanks,
Miklos
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