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Re: /proc filesystem allows bypassing directory permissions on Linux

Related Terms:
check Pavel Machek
From: Glynn Clements <glynn gclements plus com>
To: Pavel Machek <pavel ucw cz>
Cc: Dan Yefimov <dan lightwave net ru>, bugtraq securityfocus com
Subject: Re: /proc filesystem allows bypassing directory permissions on Linux
Date: Mon - Oct 26, 2009 02:23 PM



Pavel Machek wrote:

> Check it again.  There's no race; I check link count before chmod 666.

Which creates a race condition, as the link could be created after the
check but before the chmod.

You can't safely rely upon directory permissions if the directory was
created 0777 then chmod'ed down later. It needs to be created with the
restrictive permissions from the outset.

-- 
Glynn Clements <glynn@gclements.plus.com>




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