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From: Richard Weinberger <richard@nod.at>
To: Tomas Bortoli <tomasbortoli@hotmail.it>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: ext3 and like, mount point in module
Date: Sat, 1 Aug 2015 15:27:17 +0200	[thread overview]
Message-ID: <55BCC935.2000908@nod.at> (raw)
In-Reply-To: <DUB109-W314DF4407AB469152E3A9B6890@phx.gbl>

Am 01.08.2015 um 15:10 schrieb Tomas Bortoli:
> Thanks for the clarification!
> I'm trying to make a patch to slightly improve security in file system.
> It consists in removing the ".." dir entry in the "/" dir of the file system mounted on the root mount point.

What about chroot/namespaces/etc? :)

> This could prevent an attacker from using a long series of "../../../" etc in a  transversal directory attack 
> with unknown initial relative path to reach the root dir for sure and then move from there.
> The dangerousness depends from which is the flaw
> Do you think it's worth it?

I'm not sure if it is worth the hassle, I bet some applications depend on that behavior.
But you can give it a try, I'd insert a negative dentry for ".." if ".." is child of the current
root.

Thanks,
//richard

  reply	other threads:[~2015-08-01 13:27 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-01 12:27 ext3 and like, mount point in module Tomas Bortoli
2015-08-01 12:46 ` Richard Weinberger
2015-08-01 13:10   ` Tomas Bortoli
2015-08-01 13:27     ` Richard Weinberger [this message]
2015-08-01 13:43       ` Al Viro
2015-08-01 14:34       ` Tomas Bortoli
2015-08-05 17:17         ` Eric W. Biederman

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