linux-kernel - Re: [PATCH v6 0/5] riscv: Introduce KASLR

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Message-ID: <CAHVXubhiYT07L2ve2iEB5AZZdOgA0Sux8vDP4tMfdR6UTWuMgg@mail.gmail.com>
Date:   Tue, 25 Jul 2023 09:08:01 +0200
From:   Alexandre Ghiti <alexghiti@...osinc.com>
To:     Conor Dooley <conor.dooley@...rochip.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Ard Biesheuvel <ardb@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v6 0/5] riscv: Introduce KASLR

On Mon, Jul 24, 2023 at 4:32 PM Conor Dooley <conor.dooley@...rochip.com> wrote:
>
> Hey Alex,
>
> On Sat, Jul 22, 2023 at 02:38:45PM +0200, Alexandre Ghiti wrote:
> > The following KASLR implementation allows to randomize the kernel mapping:
> >
> > - virtually: we expect the bootloader to provide a seed in the device-tree
> > - physically: only implemented in the EFI stub, it relies on the firmware to
> >   provide a seed using EFI_RNG_PROTOCOL. arm64 has a similar implementation
> >   hence the patch 3 factorizes KASLR related functions for riscv to take
> >   advantage.
> >
> > The new virtual kernel location is limited by the early page table that only
> > has one PUD and with the PMD alignment constraint, the kernel can only take
> > < 512 positions.
>
> I gave this all a go today, it seems to do what it it says on the tin,
> and crashing my kernel does dump out an offset etc.
>
> Tested-by: Conor Dooley <conor.dooley@...rochip.com>

Great, thanks for testing!

>
> I'll hopefully get some time later in the week to go through the code.

I will be on holiday in 3 weeks, you have some time, no worries :)

Thanks again,

Alex

>
> Cheers,
> Conor.
>