linux-hardening - Re: [PATCH v4 23/26] arm64: head: remap the kernel text/inittext region read-only

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Date:   Mon, 13 Jun 2022 09:57:23 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-hardening@...r.kernel.org, Marc Zyngier <maz@...nel.org>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Brown <broonie@...nel.org>,
        Anshuman Khandual <anshuman.khandual@....com>
Subject: Re: [PATCH v4 23/26] arm64: head: remap the kernel text/inittext
 region read-only

On Mon, Jun 13, 2022 at 04:45:47PM +0200, Ard Biesheuvel wrote:
> In order to be able to run with WXN from boot (which could potentially
> be under a hypervisor regime that mandates this), update the temporary
> kernel page tables with read-only attributes for the text regions before
> attempting to execute from them.
> 
> This is rather straight-forward for 16k and 64k granule configurations,
> as the split between executable and writable regions is guaranteed to be
> aligned to the granule used for the early kernel page tables. For 4k, it
> involves installing a single table entry and populating it accordingly.
> 
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook