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

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Message-ID: <2bcffc9f-9244-0362-2da9-ece230055320@intel.com>
Date:   Mon, 15 May 2023 07:28:29 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     jeffxu@...omium.org, luto@...nel.org, jorgelo@...omium.org,
        keescook@...omium.org, groeck@...omium.org, jannh@...gle.com,
        sroettger@...gle.com
Cc:     akpm@...ux-foundation.org, jeffxu@...gle.com,
        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 5/15/23 06:05, jeffxu@...omium.org wrote:
> We're using PKU for in-process isolation to enforce control-flow integrity
> for a JIT compiler. In our threat model, an attacker exploits a 
> vulnerability and has arbitrary read/write access to the whole process
> space concurrently to other threads being executed. This attacker can
> manipulate some arguments to syscalls from some threads.

This all sounds like it hinges on the contents of PKRU in the attacker
thread.

Could you talk a bit about how the attacker is prevented from running
WRPKRU, XRSTOR or compelling the kernel to write to PKRU like at sigreturn?