linux-kernel - Re: Formal description of system call interface

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Message-ID: <20161121161032.GB27353@rei.lan>
Date:   Mon, 21 Nov 2016 17:10:33 +0100
From:   Cyril Hrubis <chrubis@...e.cz>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     linux-api@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Michael Kerrisk-manpages <mtk.manpages@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sasha Levin <levinsasha928@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        scientist@...com, Steven Rostedt <rostedt@...dmis.org>,
        Arnd Bergmann <arnd@...db.de>, carlos@...hat.com,
        syzkaller <syzkaller@...glegroups.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Mike Frysinger <vapier@...gle.com>,
        Dave Jones <davej@...emonkey.org.uk>,
        Tavis Ormandy <taviso@...gle.com>
Subject: Re: Formal description of system call interface

Hi!
> Description of "returns fd or this set of errors" looks simple and useful.
> Any test system or fuzzer will be able to verify that kernel actually returns
> claimed return values. Also Carlos expressed interested in errno values
> in the context of glibc.
> I would do it from day one.
> 
> Re more complex side effects. I always feared that a description suitable
> for automatic verification (i.e. zero false positives, otherwise it is useless)
> may be too difficult to achieve.

I'm afraid it may be as well. I would expect that we will end up with
something quite complex with a large set of exceptions from the rules.

> Cyril, Tavis, can you come up with some set of predicates that can be
> checked automatically yet still useful?
> We can start small, e.g. "must not alter virtual address space".

I will try to thing about this a bit.

-- 
Cyril Hrubis
chrubis@...e.cz