linux-kernel - Re: [PATCH 0/6] Memory Mapping (VMA) protection using PKU

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Message-ID: <CALmYWFteCd+h+tn+LmgTpN9Ld5=qAMMQ34=b1KCoE3OSBun+DQ@mail.gmail.com>
Date:   Tue, 16 May 2023 15:17:09 -0700
From:   Jeff Xu <jeffxu@...gle.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     jeffxu@...omium.org, dave.hansen@...el.com, luto@...nel.org,
        jorgelo@...omium.org, groeck@...omium.org, jannh@...gle.com,
        sroettger@...gle.com, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-mm@...ck.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH 0/6] Memory Mapping (VMA) protection using PKU - set 1

On Tue, May 16, 2023 at 1:08 PM Kees Cook <keescook@...omium.org> wrote:
>
> On Mon, May 15, 2023 at 01:05:46PM +0000, jeffxu@...omium.org wrote:
> > This patch introduces a new flag, PKEY_ENFORCE_API, to the pkey_alloc()
> > function. When a PKEY is created with this flag, it is enforced that any
> > thread that wants to make changes to the memory mapping (such as mprotect)
> > of the memory must have write access to the PKEY. PKEYs created without
> > this flag will continue to work as they do now, for backwards
> > compatibility.
> >
> > Only PKEY created from user space can have the new flag set, the PKEY
> > allocated by the kernel internally will not have it. In other words,
> > ARCH_DEFAULT_PKEY(0) and execute_only_pkey won’t have this flag set,
> > and continue work as today.
>
> Cool! Yeah, this looks like it could become quite useful. I assume
> V8 folks are on board with this API, etc?
>
> > This set of patch covers mprotect/munmap, I plan to work on other
> > syscalls after this.
>
> Which ones are on your list currently?
>
mprotect/mprotect_pkey/munmap
mmap/mremap
madvice,brk,sbrk

Thanks!
-Jeff Xu

> --
> Kees Cook