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, 24 Jan 2018 20:46:22 +0000
From:   Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Dominik Brodowski <linux@dominikbrodowski.net>,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        kvm@vger.kernel.org, Heiko Carstens <heiko.carstens@de.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jon Masters <jcm@redhat.com>,
        Marcus Meissner <meissner@suse.de>,
        Jiri Kosina <jkosina@suse.cz>, w@1wt.eu, keescook@chromium.org,
        thomas.lendacky@amd.com, dwmw@amazon.co.uk, ak@linux.intel.com
Subject: Re: Avoiding information leaks between users and between processes
 by default? [Was: : [PATCH 1/5] prctl: add PR_ISOLATE_BP process control]
Message-ID: <20180124204622.1f7b0de2@alans-desktop>
In-Reply-To: <20180124190105.GA30107@amd>
References: <1516712825-2917-1-git-send-email-schwidefsky@de.ibm.com>
        <1516712825-2917-2-git-send-email-schwidefsky@de.ibm.com>
        <20180123170719.GA4154@isilmar-4.linta.de>
        <20180124072953.50851fec@mschwideX1>
        <20180124083705.GA14868@light.dominikbrodowski.net>
        <20180124111552.GA24675@amd>
        <20180124134803.3e11c6d6@mschwideX1>
        <20180124190105.GA30107@amd>
Organization: Intel Corporation
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

> Anyway, no need to add prctl(), if A can ptrace B and B can ptrace A,
> leaking info between them should not be a big deal. You can probably
> find existing macros doing neccessary checks.

Until one of them is security managed so it shouldn't be able to ptrace
the other, or (and this is the nasty one) when a process is executing
code it wants to protect from the rest of the same process (eg an
untrusted jvm, javascript or probably nastiest of all webassembly)

We don't need a prctl for trusted/untrusted IMHO but we do eventually
need to think about API's for "this lot is me but I don't trust
it" (flatpack, docker, etc) and for what JIT engines need to do.

Alan