From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id E85326B0275 for ; Tue, 28 Nov 2017 00:23:40 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id 70so30978377pgf.5 for ; Mon, 27 Nov 2017 21:23:40 -0800 (PST) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id f3si14939186plb.92.2017.11.27.21.23.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Nov 2017 21:23:39 -0800 (PST) Received: from mail-io0-f169.google.com (mail-io0-f169.google.com [209.85.223.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4257F218A4 for ; Tue, 28 Nov 2017 05:23:39 +0000 (UTC) Received: by mail-io0-f169.google.com with SMTP id s37so28080210ioe.10 for ; Mon, 27 Nov 2017 21:23:39 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20171128050322.f2mgrapew3illscm@treble> References: <20171127223110.479550152@infradead.org> <20171127223405.231444600@infradead.org> <20171128050322.f2mgrapew3illscm@treble> From: Andy Lutomirski Date: Mon, 27 Nov 2017 21:23:18 -0800 Message-ID: Subject: Re: [PATCH 2/5] x86/mm/kaiser: Add a banner Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Josh Poimboeuf Cc: Andy Lutomirski , Peter Zijlstra , "linux-kernel@vger.kernel.org" , Dave Hansen , Ingo Molnar , Borislav Petkov , Brian Gerst , Denys Vlasenko , "H. Peter Anvin" , Linus Torvalds , Rik van Riel , Daniel Gruss , Hugh Dickins , Kees Cook , "linux-mm@kvack.org" , michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at, richard.fellner@student.tugraz.at On Mon, Nov 27, 2017 at 9:03 PM, Josh Poimboeuf wrote: > On Mon, Nov 27, 2017 at 07:36:40PM -0800, Andy Lutomirski wrote: >> On Mon, Nov 27, 2017 at 2:31 PM, Peter Zijlstra wrote: >> > So we can more easily see if the shiny got enabled. >> > >> > Signed-off-by: Peter Zijlstra (Intel) >> > --- >> > arch/x86/mm/kaiser.c | 2 ++ >> > 1 file changed, 2 insertions(+) >> > >> > --- a/arch/x86/mm/kaiser.c >> > +++ b/arch/x86/mm/kaiser.c >> > @@ -425,6 +425,8 @@ void __init kaiser_init(void) >> > if (!kaiser_enabled) >> > return; >> > >> > + printk("All your KAISER are belong to us\n"); >> > + >> >> All your incomprehensible academic names are belong to us. >> >> On a serious note, can we please banish the name KAISER from all the >> user-facing bits? No one should be setting a boot option that has a >> name based on an academic project called "Kernel Address Isolation to >> have Side-channels Efficiently Removed". We're not efficiently >> removing side channels. The side channels are still very much there. >> Heck, the series as currently presented doesn't even rescue kASLR. It >> could*, if we were to finish the work that I mostly started and >> completely banish all the normal kernel mappings from the shadow** >> tables. We're rather inefficiently (and partially!) mitigating the >> fact that certain CPU designers have had their heads up their >> collective arses for *years* and have failed to pay attention to >> numerous academic papers documenting that fact. >> >> Let's call the user facing bits "separate user pagetables". If we >> want to make it conditioned on a future cpu cap called >> X86_BUG_REALLY_DUMB_SIDE_CHANNELS, great, assuming a better CPU ever >> shows up. But please let's not make users look up WTF "KAISER" means. >> >> * No one ever documented the %*!& side channels AFAIK, so everything >> we're talking about here is mostly speculation. >> >> ** The word "shadow" needs to die, too. I know what shadow page >> tables are, and they have *nothing* to do with KAISER. > > +1. Somebody please rename KAISER and shadow page tables for more > clarity. > > To fix KASLR I think we need to move (at least parts of) .entry.text, > .irqentry.text, and .entry_trampoline into their own fixed section(s). > Is there anything else missing? We need to completely eliminate anything that maps normal kernel addresses into the usermode tables. > > -- > Josh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org