From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> To: Jeremy Linton <jeremy.linton@arm.com> Cc: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will.deacon@arm.com, marc.zyngier@arm.com, suzuki.poulose@arm.com, dave.martin@arm.com, shankerd@codeaurora.org, mark.rutland@arm.com, linux-kernel@vger.kernel.org, ykaukab@suse.de, julien.thierry@arm.com, mlangsdo@redhat.com, steven.price@arm.com, Thomas Gleixner <tglx@linutronix.de>, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Peter Zijlstra <peterz@infradead.org>, Dave Hansen <dave.hansen@intel.com>, Borislav Petkov <bp@alien8.de>, David Woodhouse <dwmw@amazon.co.uk> Subject: Re: [PATCH v2 1/7] sysfs/cpu: Add "Unknown" vulnerability state Date: Thu, 3 Jan 2019 17:48:31 +0100 [thread overview] Message-ID: <20190103164831.GF14994@kroah.com> (raw) In-Reply-To: <c9e08010-3ca0-cb03-e5ad-ab19342ff63b@arm.com> On Thu, Jan 03, 2019 at 10:38:16AM -0600, Jeremy Linton wrote: > On 01/03/2019 03:38 AM, Greg Kroah-Hartman wrote: > > On Wed, Jan 02, 2019 at 06:49:15PM -0600, Jeremy Linton wrote: > > > There is a lot of variation in the Arm ecosystem. Because of this, > > > there exist possible cases where the kernel cannot authoritatively > > > determine if a machine is vulnerable. > > > > Really? Why not? What keeps you from "knowing" this? Can't the > > developer of the chip tell you? > > There tends to be a few cases, possibly incomplete white/black lists, Then fix the lists :) > firmware that isn't responding correctly, or the user didn't build in the > code to check the mitigation (possibly because its an embedded system and > they know its not vulnerable?). If the firmware doesn't respond, that would imply it is vulnerable :) And if the code isn't built in, again, it's vulnerable. > I would hope that it is an exceptional case. Then have the default be vulnerable, don't give people false hope. > > > Rather than guess the vulnerability status in cases where > > > the mitigation is disabled or the firmware isn't responding > > > correctly, we need to display an "Unknown" state. > > > > Shouldn't "Unknown" really be the same thing as "Vulnerable"? A user > > should treat it the same way, "Unknown" makes it feel like "maybe I can > > just ignore this and hope I really am safe", which is not a good idea at > > all. > > I tend to agree its not clear what to do with "unknown". > > OTOH, I think there is a hesitation to declare something vulnerable when it > isn't. Meltdown for example, is fairly rare given that it currently only > affects a few arm parts, so declaring someone vulnerable when they likely > aren't is going to be just as difficult to explain. If you know it is rare, then you know how to properly detect it so "unknown" is not needed, correct? Again, "unknown" is not going to help anyone out here, please don't do it. thanks, greg k-h
WARNING: multiple messages have this Message-ID (diff)
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> To: Jeremy Linton <jeremy.linton@arm.com> Cc: mark.rutland@arm.com, David Woodhouse <dwmw@amazon.co.uk>, mlangsdo@redhat.com, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, suzuki.poulose@arm.com, marc.zyngier@arm.com, catalin.marinas@arm.com, Dave Hansen <dave.hansen@intel.com>, julien.thierry@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, steven.price@arm.com, Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>, shankerd@codeaurora.org, ykaukab@suse.de, Thomas Gleixner <tglx@linutronix.de>, dave.martin@arm.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 1/7] sysfs/cpu: Add "Unknown" vulnerability state Date: Thu, 3 Jan 2019 17:48:31 +0100 [thread overview] Message-ID: <20190103164831.GF14994@kroah.com> (raw) In-Reply-To: <c9e08010-3ca0-cb03-e5ad-ab19342ff63b@arm.com> On Thu, Jan 03, 2019 at 10:38:16AM -0600, Jeremy Linton wrote: > On 01/03/2019 03:38 AM, Greg Kroah-Hartman wrote: > > On Wed, Jan 02, 2019 at 06:49:15PM -0600, Jeremy Linton wrote: > > > There is a lot of variation in the Arm ecosystem. Because of this, > > > there exist possible cases where the kernel cannot authoritatively > > > determine if a machine is vulnerable. > > > > Really? Why not? What keeps you from "knowing" this? Can't the > > developer of the chip tell you? > > There tends to be a few cases, possibly incomplete white/black lists, Then fix the lists :) > firmware that isn't responding correctly, or the user didn't build in the > code to check the mitigation (possibly because its an embedded system and > they know its not vulnerable?). If the firmware doesn't respond, that would imply it is vulnerable :) And if the code isn't built in, again, it's vulnerable. > I would hope that it is an exceptional case. Then have the default be vulnerable, don't give people false hope. > > > Rather than guess the vulnerability status in cases where > > > the mitigation is disabled or the firmware isn't responding > > > correctly, we need to display an "Unknown" state. > > > > Shouldn't "Unknown" really be the same thing as "Vulnerable"? A user > > should treat it the same way, "Unknown" makes it feel like "maybe I can > > just ignore this and hope I really am safe", which is not a good idea at > > all. > > I tend to agree its not clear what to do with "unknown". > > OTOH, I think there is a hesitation to declare something vulnerable when it > isn't. Meltdown for example, is fairly rare given that it currently only > affects a few arm parts, so declaring someone vulnerable when they likely > aren't is going to be just as difficult to explain. If you know it is rare, then you know how to properly detect it so "unknown" is not needed, correct? Again, "unknown" is not going to help anyone out here, please don't do it. thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-01-03 16:48 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-01-03 0:49 [PATCH v2 0/7] add system vulnerability sysfs entries Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton 2019-01-03 0:49 ` [PATCH v2 1/7] sysfs/cpu: Add "Unknown" vulnerability state Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton 2019-01-03 9:38 ` Greg Kroah-Hartman 2019-01-03 9:38 ` Greg Kroah-Hartman 2019-01-03 16:38 ` Jeremy Linton 2019-01-03 16:38 ` Jeremy Linton 2019-01-03 16:48 ` Greg Kroah-Hartman [this message] 2019-01-03 16:48 ` Greg Kroah-Hartman 2019-01-04 14:08 ` Dave Martin 2019-01-04 14:08 ` Dave Martin 2019-01-04 14:18 ` Greg Kroah-Hartman 2019-01-04 14:18 ` Greg Kroah-Hartman 2019-01-04 14:55 ` Will Deacon 2019-01-04 14:55 ` Will Deacon 2019-01-03 16:37 ` Dave Martin 2019-01-03 16:37 ` Dave Martin 2019-01-03 16:46 ` Jeremy Linton 2019-01-03 16:46 ` Jeremy Linton 2019-01-03 19:30 ` Stefan Wahren 2019-01-03 19:30 ` Stefan Wahren 2019-01-03 20:32 ` Jeremy Linton 2019-01-03 20:32 ` Jeremy Linton 2019-01-04 10:13 ` Will Deacon 2019-01-04 10:13 ` Will Deacon 2019-01-03 0:49 ` [PATCH v2 2/7] arm64: kpti: move check for non-vulnerable CPUs to a function Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton 2019-01-03 0:49 ` [PATCH v2 3/7] arm64: add sysfs vulnerability show for meltdown Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton 2019-01-03 0:49 ` [PATCH v2 4/7] arm64: add sysfs vulnerability show for spectre v1 Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton 2019-01-03 0:49 ` [PATCH v2 5/7] arm64: add sysfs vulnerability show for spectre v2 Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton 2019-01-03 0:49 ` [PATCH v2 6/7] arm64: add sysfs vulnerability show for speculative store bypass Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton 2019-01-03 0:49 ` [PATCH v2 7/7] arm64: enable generic CPU vulnerabilites support Jeremy Linton 2019-01-03 0:49 ` Jeremy Linton
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