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From:   Gabriel Krisman Bertazi <krisman@collabora.com>
To:     Paul Gofman <gofmanp@gmail.com>
Cc:     Matthew Wilcox <willy@infradead.org>,
        Kees Cook <keescook@chromium.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, kernel@collabora.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Andy Lutomirski <luto@amacapital.net>,
        Will Drewry <wad@chromium.org>,
        "H . Peter Anvin" <hpa@zytor.com>,
        linux-security-module@vger.kernel.org,
        Zebediah Figura <zfigura@codeweavers.com>
Subject: Re: [PATCH RFC] seccomp: Implement syscall isolation based on memory areas
Organization: Collabora
References: <20200530055953.817666-1-krisman@collabora.com>
        <202005300923.B245392C@keescook> <851rn0ejg9.fsf@collabora.com>
        <9a512096-7707-3fc6-34ba-22f969c0f964@gmail.com>
        <20200531164938.GF19604@bombadil.infradead.org>
        <c007e3e9-e915-16f3-de31-c811ad37c44c@gmail.com>
        <20200531173157.GG19604@bombadil.infradead.org>
        <9c1f9db8-5680-cd1a-37aa-5f494b034825@gmail.com>
Date:   Mon, 01 Jun 2020 13:54:19 -0400
In-Reply-To: <9c1f9db8-5680-cd1a-37aa-5f494b034825@gmail.com> (Paul Gofman's
        message of "Sun, 31 May 2020 21:01:46 +0300")
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Paul Gofman <gofmanp@gmail.com> writes:

> On 5/31/20 20:31, Matthew Wilcox wrote:
>> If it's the cost of the syscall that's the problem, there are ways
>> around that.  We'd still want a personality() call to indicate that
>> the syscall handler should look (somewhere) to determine the current
>> personality, but that could be issued at the start of execution rather
>> than when we switch between Windows & Linux code.
>
> Sure, we can call personality() at start and specify the location to
> look at, the only thing is that the location should be thread specific,
> that is, based on fs: or gs: or whatever else which would allow us to
> have different threads in different "personality" state. If anything
> needs to be set up at thread start we can do that also of course.
>
> If there will be any proof of concept solution I will be happy to make a
> proof of concept Wine patch using that and do some testing.

Let me give that a try and share the patches with you, so we can look at
how this implementation would look like.

-- 
Gabriel Krisman Bertazi