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Date:   Wed, 6 Dec 2023 19:51:34 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
Cc:     =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= <mic@digikod.net>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Alexander Graf <graf@amazon.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
        Forrest Yuan Yu <yuanyu@google.com>,
        James Gowans <jgowans@amazon.com>,
        James Morris <jamorris@linux.microsoft.com>,
        John Andersen <john.s.andersen@intel.com>,
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Subject: Re: [RFC PATCH v2 17/19] heki: x86: Update permissions counters
 during text patching
Message-ID: <20231206185134.GA9899@noisy.programming.kicks-ass.net>
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On Wed, Dec 06, 2023 at 10:37:33AM -0600, Madhavan T. Venkataraman wrote:
> 
> 
> On 11/30/23 05:33, Peter Zijlstra wrote:
> > On Wed, Nov 29, 2023 at 03:07:15PM -0600, Madhavan T. Venkataraman wrote:
> > 
> >> Kernel Lockdown
> >> ---------------
> >>
> >> But, we must provide at least some security in V2. Otherwise, it is useless.
> >>
> >> So, we have implemented what we call a kernel lockdown. At the end of kernel
> >> boot, Heki establishes permissions in the extended page table as mentioned
> >> before. Also, it adds an immutable attribute for kernel text and kernel RO data.
> >> Beyond that point, guest requests that attempt to modify permissions on any of
> >> the immutable pages will be denied.
> >>
> >> This means that features like FTrace and KProbes will not work on kernel text
> >> in V2. This is a temporary limitation. Once authentication is in place, the
> >> limitation will go away.
> > 
> > So either you're saying your patch 17 / text_poke is broken (so why
> > include it ?!?) or your statement above is incorrect. Pick one.
> > 
> 
> It has been included so that people can be aware of the changes.
> 
> I will remove the text_poke() changes from the patchset and send it later when
> I have some authentication in place. It will make sense then.

If you know its broken then fucking say so in the Changelog instead of
wasting everybody's time.. OMG.