netdev - Re: eBPF verifier thoughts (Re: [PATCH v15 net-next 00/11] eBPF syscall, verifier, testsuite)

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: <CAMEtUuxq7oNmDAHZ+1t4Vd-QhW6SV7eoM_juxXGEDJBF3Nfu6A@mail.gmail.com>
Date:	Fri, 26 Sep 2014 15:03:31 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	David Miller <davem@...emloft.net>, Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Daniel Borkmann <dborkman@...hat.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Chema Gonzalez <chema@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <keescook@...omium.org>,
	Linux API <linux-api@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: eBPF verifier thoughts (Re: [PATCH v15 net-next 00/11] eBPF
 syscall, verifier, testsuite)

On Fri, Sep 26, 2014 at 2:47 PM, Andy Lutomirski <luto@...capital.net> wrote:
>
> Can't you just disallow the 1-byte write to the stack?

of course not.
That would be extremely limiting to users.
Can you actually see yourself living with stack that only
allows 8-byte writes/reads?
The stack usage will increase a lot, since all char/short
stack variables will become 8-byte...

> I'll try it in Python.  I bet I can get it to be shorter than the current code.

Awesome challenge! :)
I'll buy you a drink of your choice if you can achieve that.
Also I'll send you our C programs that we use for
testing to make sure, your python verifier can analyze them.
If it passes, I'll be glad to rip mine out. Seriously.
Deal?

> Yes, but does it work reliably?

I'm not saying current verifier is perfect. It can get better.
So far it was enough to let people code freely on top of it.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html