linux-kernel - Re: RFC v2: post-init-read-only protection for data allocated dynamically

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Date:   Wed, 10 May 2017 08:45:28 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Igor Stoppa <igor.stoppa@...wei.com>,
        Michal Hocko <mhocko@...nel.org>,
        Laura Abbott <labbott@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: RFC v2: post-init-read-only protection for data allocated
 dynamically

On 05/10/2017 08:19 AM, Igor Stoppa wrote:
> So I'd like to play a little what-if scenario:
> what if I was to support exclusively virtual memory and convert to it
> everything that might need sealing?

Because of the issues related to fracturing large pages, you might have
had to go this route eventually anyway.  Changing the kernel linear map
isn't nice.

FWIW, you could test this scheme by just converting all the users to
vmalloc() and seeing what breaks.  They'd all end up rounding up all
their allocations to PAGE_SIZE, but that'd be fine for testing.

Could you point out 5 or 10 places in the kernel that you want to convert?