linux-kernel - Re: [PATCH 1/4] module: add syscall to load module from fd

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87a9vjp5d9.fsf@rustcorp.com.au>
Date:	Fri, 19 Oct 2012 12:53:14 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	"H. Peter Anvin" <hpa@...or.com>, mtk.manpages@...il.com
Cc:	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Arnd Bergmann <arnd@...db.de>,
	James Morris <james.l.morris@...cle.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Eric Paris <eparis@...hat.com>, Jiri Kosina <jkosina@...e.cz>,
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH 1/4] module: add syscall to load module from fd

"H. Peter Anvin" <hpa@...or.com> writes:
> Given that, I have to say I now seriously question the value of 
> finit_module().  The kernel can trivially discover if the pointed-to 
> memory area is a MAP_SHARED mmap() of a file descriptor and if so which 
> file descriptor... why can't we handle this behind the scenes?

It is a bit more indirect, but also in practice it's a bit trickier than
that.  We need to ensure the memory doesn't change underneath us and
stays attached to that fd.  I can easily see that code slipping and
ending in an exploit.

But that may be my irrational fear of the mm :)

Cheers,
Rusty.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/