Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 31 Oct 2018 14:04:42 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     Tycho Andersen <tycho@tycho.ws>,
        Andy Lutomirski <luto@amacapital.net>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        "Serge E . Hallyn" <serge@hallyn.com>,
        Christian Brauner <christian@brauner.io>,
        Tyler Hicks <tyhicks@canonical.com>,
        Akihiro Suda <suda.akihiro@lab.ntt.co.jp>,
        Aleksa Sarai <asarai@suse.de>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Containers <containers@lists.linux-foundation.org>,
        Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH v8 1/2] seccomp: add a return code to trap to userspace
Message-ID: <20181031130442.GB9007@redhat.com>
References: <20181029224031.29809-1-tycho@tycho.ws>
 <20181029224031.29809-2-tycho@tycho.ws>
 <20181030150254.GB3385@redhat.com>
 <20181030155403.GC7343@cisco>
 <20181030162752.GB7643@redhat.com>
 <20181030163926.GC7643@redhat.com>
 <20181030172143.GD7343@cisco>
 <CAGXu5j+MYbAiSxdhLnQHdOZC-B=FWZoODxzwkYVEUqDc9SHnBQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAGXu5j+MYbAiSxdhLnQHdOZC-B=FWZoODxzwkYVEUqDc9SHnBQ@mail.gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 10/30, Kees Cook wrote:
>
> I'd like to avoid changing the return value of __secure_computing() to
> just avoid having to touch all the callers. And I'd prefer not to
> change __seccomp_filter() to a bool, since I'd like the return values
> to be consistent through the call chain.

Sure, please forget.

> I find the existing code more readable than a single-line return, just
> because it's very explicit. I don't want to have to think any harder
> when reading seccomp. ;)

Heh ;) Again, please forget, this is cosmetic.

But I simply can't resist. I asked this question exactly because I was
confused by these 2 lines:

		if (__seccomp_filter(this_syscall, NULL, true))
			return -1;

		return 0;

to me it looks as if we need to filter out some non-zero return values and
turn them into -1. I had to spend some time (and think harder ;) to verify
that this is just the recursive call and nothing more.

nevermind, please ignore.

Oleg.