From: Thomas Gleixner <tglx@linutronix.de> To: Mathias Krause <minipli@googlemail.com> Cc: Andy Lutomirski <luto@amacapital.net>, Kees Cook <keescook@chromium.org>, Andy Lutomirski <luto@kernel.org>, "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com>, Mark Rutland <mark.rutland@arm.com>, Hoeun Ryu <hoeun.ryu@gmail.com>, PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>, Russell King <linux@armlinux.org.uk>, X86 ML <x86@kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Peter Zijlstra <peterz@infradead.org> Subject: Re: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Date: Fri, 7 Apr 2017 15:14:22 +0200 (CEST) [thread overview] Message-ID: <alpine.DEB.2.20.1704071426300.1716@nanos> (raw) In-Reply-To: <CA+rthh9-EJBBO6nYYY6noP0ybcvk+xJ+S5h6BCNPtidjMCv8VQ@mail.gmail.com> On Fri, 7 Apr 2017, Mathias Krause wrote: > On 7 April 2017 at 11:46, Thomas Gleixner <tglx@linutronix.de> wrote: > > Whether protected by preempt_disable or local_irq_disable, to make that > > work it needs CR0 handling in the exception entry/exit at the lowest > > level. And that's just a nightmare maintainence wise as it's prone to be > > broken over time. > > It seems to be working fine for more than a decade now in PaX. So it > can't be such a big maintenance nightmare ;) I really do not care whether PaX wants to chase and verify that over and over. I certainly don't want to take the chance to leak CR0.WP ever and I very much care about extra stuff to check in the entry/exit path. > The "proper solution" seems to be much slower compared to just > toggling CR0.WP (which is costly in itself, already) because of the > TLB invalidation / synchronisation involved. Why the heck should we care about rare writes being performant? > > It's valid (at least on x86) to have a shadow map with the same page > > attributes but write enabled. That does not require any fixups of CR0 and > > just works. > > "Just works", sure -- but it's not as tightly focused as the PaX > solution which is CPU local, while your proposed solution is globally > visible. Making the world and some more writeable hardly qualifies as tightly focussed. Making the mapping concept CPU local is not rocket science either. The question is whethers it's worth the trouble. Thanks, tglx
WARNING: multiple messages have this Message-ID (diff)
From: tglx@linutronix.de (Thomas Gleixner) To: linux-arm-kernel@lists.infradead.org Subject: [kernel-hardening] Re: [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Date: Fri, 7 Apr 2017 15:14:22 +0200 (CEST) [thread overview] Message-ID: <alpine.DEB.2.20.1704071426300.1716@nanos> (raw) In-Reply-To: <CA+rthh9-EJBBO6nYYY6noP0ybcvk+xJ+S5h6BCNPtidjMCv8VQ@mail.gmail.com> On Fri, 7 Apr 2017, Mathias Krause wrote: > On 7 April 2017 at 11:46, Thomas Gleixner <tglx@linutronix.de> wrote: > > Whether protected by preempt_disable or local_irq_disable, to make that > > work it needs CR0 handling in the exception entry/exit at the lowest > > level. And that's just a nightmare maintainence wise as it's prone to be > > broken over time. > > It seems to be working fine for more than a decade now in PaX. So it > can't be such a big maintenance nightmare ;) I really do not care whether PaX wants to chase and verify that over and over. I certainly don't want to take the chance to leak CR0.WP ever and I very much care about extra stuff to check in the entry/exit path. > The "proper solution" seems to be much slower compared to just > toggling CR0.WP (which is costly in itself, already) because of the > TLB invalidation / synchronisation involved. Why the heck should we care about rare writes being performant? > > It's valid (at least on x86) to have a shadow map with the same page > > attributes but write enabled. That does not require any fixups of CR0 and > > just works. > > "Just works", sure -- but it's not as tightly focused as the PaX > solution which is CPU local, while your proposed solution is globally > visible. Making the world and some more writeable hardly qualifies as tightly focussed. Making the mapping concept CPU local is not rocket science either. The question is whethers it's worth the trouble. Thanks, tglx
next prev parent reply other threads:[~2017-04-07 13:14 UTC|newest] Thread overview: 188+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-29 18:15 [RFC v2] Introduce rare_write() infrastructure Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-29 18:15 ` [RFC v2][PATCH 01/11] " Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-29 18:23 ` Kees Cook 2017-03-29 18:23 ` [kernel-hardening] " Kees Cook 2017-03-29 18:23 ` Kees Cook 2017-03-30 7:44 ` Ho-Eun Ryu 2017-03-30 7:44 ` [kernel-hardening] " Ho-Eun Ryu 2017-03-30 7:44 ` Ho-Eun Ryu 2017-03-30 17:02 ` Kees Cook 2017-03-30 17:02 ` [kernel-hardening] " Kees Cook 2017-03-30 17:02 ` Kees Cook 2017-04-07 8:09 ` Ho-Eun Ryu 2017-04-07 8:09 ` [kernel-hardening] " Ho-Eun Ryu 2017-04-07 8:09 ` Ho-Eun Ryu 2017-04-07 20:38 ` Kees Cook 2017-04-07 20:38 ` [kernel-hardening] " Kees Cook 2017-04-07 20:38 ` Kees Cook 2017-03-29 18:15 ` [RFC v2][PATCH 02/11] lkdtm: add test for " Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-30 9:34 ` [kernel-hardening] " Ian Campbell 2017-03-30 9:34 ` Ian Campbell 2017-03-30 16:16 ` Kees Cook 2017-03-30 16:16 ` Kees Cook 2017-03-30 16:16 ` Kees Cook 2017-03-29 18:15 ` [RFC v2][PATCH 03/11] net: switch sock_diag handlers to rare_write() Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-29 18:15 ` [RFC v2][PATCH 04/11] x86: Implement __arch_rare_write_begin/unmap() Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-29 22:38 ` Andy Lutomirski 2017-03-29 22:38 ` [kernel-hardening] " Andy Lutomirski 2017-03-29 22:38 ` Andy Lutomirski 2017-03-30 1:41 ` Kees Cook 2017-03-30 1:41 ` [kernel-hardening] " Kees Cook 2017-03-30 1:41 ` Kees Cook 2017-04-05 23:57 ` Andy Lutomirski 2017-04-05 23:57 ` [kernel-hardening] " Andy Lutomirski 2017-04-05 23:57 ` Andy Lutomirski 2017-04-06 0:14 ` Kees Cook 2017-04-06 0:14 ` [kernel-hardening] " Kees Cook 2017-04-06 0:14 ` Kees Cook 2017-04-06 15:59 ` Andy Lutomirski 2017-04-06 15:59 ` [kernel-hardening] " Andy Lutomirski 2017-04-06 15:59 ` Andy Lutomirski 2017-04-07 8:34 ` [kernel-hardening] " Mathias Krause 2017-04-07 8:34 ` Mathias Krause 2017-04-07 8:34 ` Mathias Krause 2017-04-07 9:46 ` Thomas Gleixner 2017-04-07 9:46 ` Thomas Gleixner 2017-04-07 9:46 ` Thomas Gleixner 2017-04-07 10:51 ` Mathias Krause 2017-04-07 10:51 ` Mathias Krause 2017-04-07 10:51 ` Mathias Krause 2017-04-07 13:14 ` Thomas Gleixner [this message] 2017-04-07 13:14 ` Thomas Gleixner 2017-04-07 13:14 ` Thomas Gleixner 2017-04-07 13:30 ` Mathias Krause 2017-04-07 13:30 ` Mathias Krause 2017-04-07 13:30 ` Mathias Krause 2017-04-07 16:14 ` Andy Lutomirski 2017-04-07 16:14 ` Andy Lutomirski 2017-04-07 16:14 ` Andy Lutomirski 2017-04-07 16:22 ` Mark Rutland 2017-04-07 16:22 ` Mark Rutland 2017-04-07 16:22 ` Mark Rutland 2017-04-07 19:58 ` PaX Team 2017-04-07 19:58 ` PaX Team 2017-04-07 19:58 ` PaX Team 2017-04-08 4:58 ` Andy Lutomirski 2017-04-08 4:58 ` Andy Lutomirski 2017-04-08 4:58 ` Andy Lutomirski 2017-04-09 12:47 ` PaX Team 2017-04-09 12:47 ` PaX Team 2017-04-09 12:47 ` PaX Team 2017-04-10 0:10 ` Andy Lutomirski 2017-04-10 0:10 ` Andy Lutomirski 2017-04-10 0:10 ` Andy Lutomirski 2017-04-10 10:42 ` PaX Team 2017-04-10 10:42 ` PaX Team 2017-04-10 10:42 ` PaX Team 2017-04-10 16:01 ` Andy Lutomirski 2017-04-10 16:01 ` Andy Lutomirski 2017-04-10 16:01 ` Andy Lutomirski 2017-04-07 20:44 ` Thomas Gleixner 2017-04-07 20:44 ` Thomas Gleixner 2017-04-07 20:44 ` Thomas Gleixner 2017-04-07 21:20 ` Kees Cook 2017-04-07 21:20 ` Kees Cook 2017-04-07 21:20 ` Kees Cook 2017-04-08 4:12 ` Daniel Micay 2017-04-08 4:12 ` Daniel Micay 2017-04-08 4:12 ` Daniel Micay 2017-04-08 4:13 ` Daniel Micay 2017-04-08 4:13 ` Daniel Micay 2017-04-08 4:13 ` Daniel Micay 2017-04-08 4:21 ` Daniel Micay 2017-04-08 4:21 ` Daniel Micay 2017-04-08 4:21 ` Daniel Micay 2017-04-08 5:07 ` Andy Lutomirski 2017-04-08 5:07 ` Andy Lutomirski 2017-04-08 5:07 ` Andy Lutomirski 2017-04-08 7:33 ` Daniel Micay 2017-04-08 7:33 ` Daniel Micay 2017-04-08 7:33 ` Daniel Micay 2017-04-08 15:20 ` Andy Lutomirski 2017-04-08 15:20 ` Andy Lutomirski 2017-04-08 15:20 ` Andy Lutomirski 2017-04-09 10:53 ` Ingo Molnar 2017-04-09 10:53 ` Ingo Molnar 2017-04-09 10:53 ` Ingo Molnar 2017-04-10 10:22 ` Mark Rutland 2017-04-10 10:22 ` Mark Rutland 2017-04-10 10:22 ` Mark Rutland 2017-04-09 20:24 ` PaX Team 2017-04-09 20:24 ` PaX Team 2017-04-09 20:24 ` PaX Team 2017-04-10 0:31 ` Andy Lutomirski 2017-04-10 0:31 ` Andy Lutomirski 2017-04-10 0:31 ` Andy Lutomirski 2017-04-10 19:47 ` PaX Team 2017-04-10 19:47 ` PaX Team 2017-04-10 19:47 ` PaX Team 2017-04-10 20:27 ` Andy Lutomirski 2017-04-10 20:27 ` Andy Lutomirski 2017-04-10 20:27 ` Andy Lutomirski 2017-04-10 20:13 ` Kees Cook 2017-04-10 20:13 ` Kees Cook 2017-04-10 20:13 ` Kees Cook 2017-04-10 20:17 ` Andy Lutomirski 2017-04-10 20:17 ` Andy Lutomirski 2017-04-10 20:17 ` Andy Lutomirski 2017-04-07 19:25 ` Thomas Gleixner 2017-04-07 19:25 ` Thomas Gleixner 2017-04-07 19:25 ` Thomas Gleixner 2017-04-07 14:45 ` Peter Zijlstra 2017-04-07 14:45 ` Peter Zijlstra 2017-04-07 14:45 ` Peter Zijlstra 2017-04-10 10:29 ` Mark Rutland 2017-04-10 10:29 ` Mark Rutland 2017-04-10 10:29 ` Mark Rutland 2017-04-07 19:52 ` PaX Team 2017-04-07 19:52 ` PaX Team 2017-04-07 19:52 ` PaX Team 2017-04-10 8:26 ` Thomas Gleixner 2017-04-10 8:26 ` Thomas Gleixner 2017-04-10 8:26 ` Thomas Gleixner 2017-04-10 19:55 ` PaX Team 2017-04-10 19:55 ` PaX Team 2017-04-10 19:55 ` PaX Team 2017-04-07 9:37 ` Peter Zijlstra 2017-04-07 9:37 ` [kernel-hardening] " Peter Zijlstra 2017-04-07 9:37 ` Peter Zijlstra 2017-03-29 18:15 ` [RFC v2][PATCH 05/11] ARM: mm: dump: Add domain to output Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-29 18:15 ` [RFC v2][PATCH 06/11] ARM: domains: Extract common USER domain init Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-29 18:15 ` [RFC v2][PATCH 07/11] ARM: mm: set DOMAIN_WR_RARE for rodata Kees Cook 2017-03-29 18:15 ` [kernel-hardening] " Kees Cook 2017-03-29 18:15 ` Kees Cook 2017-03-29 18:16 ` [RFC v2][PATCH 08/11] ARM: Implement __arch_rare_write_begin/end() Kees Cook 2017-03-29 18:16 ` [kernel-hardening] " Kees Cook 2017-03-29 18:16 ` Kees Cook 2017-04-07 9:36 ` Peter Zijlstra 2017-04-07 9:36 ` [kernel-hardening] " Peter Zijlstra 2017-04-07 9:36 ` Peter Zijlstra 2017-03-29 18:16 ` [RFC v2][PATCH 09/11] list: add rare_write() list helpers Kees Cook 2017-03-29 18:16 ` [kernel-hardening] " Kees Cook 2017-03-29 18:16 ` Kees Cook 2017-03-29 18:16 ` [RFC v2][PATCH 10/11] gcc-plugins: Add constify plugin Kees Cook 2017-03-29 18:16 ` [kernel-hardening] " Kees Cook 2017-03-29 18:16 ` Kees Cook 2017-03-29 18:16 ` [RFC v2][PATCH 11/11] cgroups: force all struct cftype const Kees Cook 2017-03-29 18:16 ` [kernel-hardening] " Kees Cook 2017-03-29 18:16 ` Kees Cook 2017-03-29 19:00 ` [RFC v2] Introduce rare_write() infrastructure Russell King - ARM Linux 2017-03-29 19:00 ` [kernel-hardening] " Russell King - ARM Linux 2017-03-29 19:00 ` Russell King - ARM Linux 2017-03-29 19:14 ` Kees Cook 2017-03-29 19:14 ` [kernel-hardening] " Kees Cook 2017-03-29 19:14 ` Kees Cook
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