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Message-ID: <e1c34f97-9687-0475-b7f3-02f54a7b200f@redhat.com>
Date: Wed, 7 Nov 2018 15:17:36 -0800
From: Laura Abbott <labbott@...hat.com>
To: Ard Biesheuvel <ard.biesheuvel@...aro.org>,
linux-arm-kernel@...ts.infradead.org
Cc: kernel-hardening@...ts.openwall.com, keescook@...omium.org,
will.deacon@....com, jannh@...gle.com, mark.rutland@....com,
james.morse@....com, catalin.marinas@....com
Subject: Re: [PATCH v4 2/2] arm64: mm: apply r/o permissions of VM areas to
its linear alias as well
On 11/7/18 2:36 AM, Ard Biesheuvel wrote:
> @@ -93,6 +96,18 @@ static int change_memory_common(unsigned long addr, int numpages,
> if (!numpages)
> return 0;
>
> + /*
> + * If we are manipulating read-only permissions, apply the same
> + * change to the linear mapping of the pages that back this VM area.
> + */
> + if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
> + pgprot_val(clear_mask) == PTE_RDONLY)) {
> + for (i = 0; i < area->nr_pages; i++) {
> + __change_memory_common((u64)page_address(area->pages[i]),
> + PAGE_SIZE, set_mask, clear_mask);
> + }
> + }
> +
> /*
> * Get rid of potentially aliasing lazily unmapped vm areas that may
> * have permissions set that deviate from the ones we are setting here.
This check assumes the masks are only adjusting the PTE_RDONLY bit.
I guess this is fine for now since all the calls currently change one
bit at a time.
Tested-by: Laura Abbott <labbott@...hat.com>
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