linux-kernel - Re: [PATCH 0/9] proc: protect /proc/<pid>/* files across execve

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Message-ID: <m1pqchocok.fsf@fess.ebiederm.org>
Date:	Mon, 12 Mar 2012 12:13:15 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Djalal Harouni <tixxdz@...ndz.org>
Cc:	linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Vasiliy Kulikov <segoon@...nwall.com>,
	Kees Cook <keescook@...omium.org>,
	Solar Designer <solar@...nwall.com>,
	WANG Cong <xiyou.wangcong@...il.com>,
	James Morris <james.l.morris@...cle.com>,
	Oleg Nesterov <oleg@...hat.com>,
	linux-security-module@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, Alan Cox <alan@...rguk.ukuu.org.uk>,
	Greg KH <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...e.hu>, Stephen Wilson <wilsons@...rt.ca>,
	"Jason A. Donenfeld" <Jason@...c4.com>
Subject: Re: [PATCH 0/9] proc: protect /proc/<pid>/* files across execve

Djalal Harouni <tixxdz@...ndz.org> writes:

> Procfs files and other important objects may contain sensitive information
> which must not be seen, inherited or processed across execve.

So I am dense.  /proc/<pid>/mem was special in that it uses a different
set of checks than other files, and to do those access checks
/proc/<pid>/mem needed to look at exec_id.

For all of the access checks that are not written in that silly way.
What is wrong with ptrace_may_access run at every read/write of a file?

We redo all of the permission checks every time so that should avoid
races.

I really think you are trying to solve something that is not broken.
Certainly I could not see your argument for why anything but
/proc/<pid>/mem needs attention.

Eric
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