linux-kernel - Re: [PATCH RFC v2 net-next 10/16] bpf: add eBPF verifier

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Message-ID: <CAMEtUuzYD-WqxhDeq9tMhOKi+w9QCDdTbzpzaGgsnR83yEvz1A@mail.gmail.com>
Date:	Wed, 23 Jul 2014 22:01:18 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...capital.net>,
	Steven Rostedt <rostedt@...dmis.org>,
	Daniel Borkmann <dborkman@...hat.com>,
	Chema Gonzalez <chema@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Jiri Olsa <jolsa@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux API <linux-api@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v2 net-next 10/16] bpf: add eBPF verifier

On Wed, Jul 23, 2014 at 5:48 PM, Alexei Starovoitov <ast@...mgrid.com> wrote:
> check_reg_arg() is indeed incorrect here. Will fix. That was a good catch.
> Thank you for review!

I fixed this missing check_reg_arg() check, addressed feedback for
other patches, rebased it and pushed it:
https://git.kernel.org/cgit/linux/kernel/git/ast/bpf.git/log/

Also replaced dump into syslog from verifier with print into user supplied
buffer, so that user space can see why verifier rejected the program.
The more I play with it the more I like fd-based user interface. Cannot
thank enough Andy for suggesting it :)
Currently map_id is still there as kernel internal id that programs are
using to access maps. I'll try to replace it with direct pointer.
That will save one idr_find() lookup in critical path. That's a good
reason to add new 16-byte eBPF instruction. It will be
"load 64-bit immediate" that we've discussed before.
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