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References: <20230515130553.2311248-1-jeffxu@chromium.org> <202305161307.4A16BB6A47@keescook>
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From:   Jeff Xu <jeffxu@google.com>
Date:   Tue, 16 May 2023 15:17:09 -0700
Message-ID: <CALmYWFteCd+h+tn+LmgTpN9Ld5=qAMMQ34=b1KCoE3OSBun+DQ@mail.gmail.com>
Subject: Re: [PATCH 0/6] Memory Mapping (VMA) protection using PKU - set 1
To:     Kees Cook <keescook@chromium.org>
Cc:     jeffxu@chromium.org, dave.hansen@intel.com, luto@kernel.org,
        jorgelo@chromium.org, groeck@chromium.org, jannh@google.com,
        sroettger@google.com, akpm@linux-foundation.org,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-mm@kvack.org, linux-hardening@vger.kernel.org
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On Tue, May 16, 2023 at 1:08=E2=80=AFPM Kees Cook <keescook@chromium.org> w=
rote:
>
> On Mon, May 15, 2023 at 01:05:46PM +0000, jeffxu@chromium.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 an=
y
> > thread that wants to make changes to the memory mapping (such as mprote=
ct)
> > 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=E2=80=99t 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