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Message-ID: <f942d9b4-6fde-267d-aa04-a64218b1391f@redhat.com>
Date: Wed, 25 Oct 2017 11:45:21 +0200
From: David Hildenbrand <david@...hat.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Cornelia Huck <cohuck@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
kernel-hardening@...ts.openwall.com, Kees Cook <keescook@...omium.org>,
Radim Krčmář <rkrcmar@...hat.com>,
Christoffer Dall <christoffer.dall@...aro.org>,
Marc Zyngier <marc.zyngier@....com>,
Christian Borntraeger <borntraeger@...ibm.com>,
James Hogan <james.hogan@...tec.com>, Paul Mackerras <paulus@...ba.org>
Subject: Re: [PATCH 0/2] KVM: fixes for the kernel-hardening tree
On 23.10.2017 16:15, Paolo Bonzini wrote:
> On 23/10/2017 14:39, Cornelia Huck wrote:
>> On Mon, 23 Oct 2017 11:52:51 +0200
>> David Hildenbrand <david@...hat.com> wrote:
>>
>>> On 21.10.2017 01:25, Paolo Bonzini wrote:
>>>> Two KVM ioctls (KVM_GET/SET_CPUID2) directly access the cpuid_entries
>>>> field of struct kvm_vcpu_arch. Therefore, the new usercopy hardening
>>>> work in linux-next, which forbids copies from and to slab objects
>>>> unless they are from kmalloc or explicitly whitelisted, breaks KVM
>>>> completely.
>>>>
>>>> This series fixes it by adding the two new usercopy arguments
>>>> to kvm_init (more precisely to a new function kvm_init_usercopy,
>>>> while kvm_init passes zeroes as a default).
>>>>
>>>> There's also another broken ioctl, KVM_XEN_HVM_CONFIG, but it is
>>>> obsolete and not a big deal at all.
>>>>
>>>> I'm Ccing all submaintainers in case they have something similar
>>>> going on in their kvm_arch and kvm_vcpu_arch structs. KVM has a
>>>> pretty complex userspace API, so thorough with linux-next is highly
>>>> recommended.
>>>
>>> I assume on s390x, at least
>>>
>>> kvm_arch_vcpu_ioctl_get_one_reg() and
>>> kvm_arch_vcpu_ioctl_set_one_reg()
>>>
>>> have to be fixed.
>>
>> At a glance, seems like it.
>>
>>>
>>> Christian, are you already looking into this?
>>
>> I'm afraid I'm also busy with travel preparation/travel, so I'd be glad
>> for any takers.
>
> Let's do a generic fix now, so that we don't need to rush the switch to
> explicit whitelisting.
You mean a arch specific fix (allow writes/reads to arch) or even more
generic?
Otherwise I can you send a patch to fix these two functions.
>
> Paolo
>
--
Thanks,
David
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