linux-kernel - Re: [PATCH RFC net-next 08/14] bpf: add eBPF verifier

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Date:	Tue, 01 Jul 2014 10:05:04 +0200
From:	Daniel Borkmann <dborkman@...hat.com>
To:	Alexei Starovoitov <ast@...mgrid.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	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>,
	Kees Cook <keescook@...omium.org>, linux-api@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC net-next 08/14] bpf: add eBPF verifier

On 06/28/2014 02:06 AM, Alexei Starovoitov wrote:
> Safety of eBPF programs is statically determined by the verifier, which detects:
> - loops
> - out of range jumps
> - unreachable instructions
> - invalid instructions
> - uninitialized register access
> - uninitialized stack access
> - misaligned stack access
> - out of range stack access
> - invalid calling convention
...
> More details in Documentation/networking/filter.txt
>
> Signed-off-by: Alexei Starovoitov <ast@...mgrid.com>
> ---
...
>   kernel/bpf/verifier.c               | 1431 +++++++++++++++++++++++++++++++++++

Looking at classic BPF verifier which checks safety of BPF
user space programs, it's roughly 200 loc. :-/

> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> new file mode 100644
...
> +#define _(OP) ({ int ret = OP; if (ret < 0) return ret; })
...
> +	_(get_map_info(env, map_id, &map));
...
> +	_(size = bpf_size_to_bytes(bpf_size));

Nit: such macros should be removed, please.
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