From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 0/2] KVM: fixes for the kernel-hardening tree
Date: Mon, 23 Oct 2017 16:15:32 +0200
Message-ID: <6fbcdbac-a717-def4-1864-6426d58986fc@redhat.com>
References: <20171020232525.7387-1-pbonzini@redhat.com>
 <f13340f5-4027-181b-7e41-e9bc434b195c@redhat.com>
 <20171023143918.21112222.cohuck@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        kernel-hardening@lists.openwall.com,
        Kees Cook <keescook@chromium.org>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Christoffer Dall <christoffer.dall@linaro.org>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        James Hogan <james.hogan@imgtec.com>,
        Paul Mackerras <paulus@samba.org>
To: Cornelia Huck <cohuck@redhat.com>,
        David Hildenbrand <david@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20171023143918.21112222.cohuck@redhat.com>
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On 23/10/2017 14:39, Cornelia Huck wrote:
> On Mon, 23 Oct 2017 11:52:51 +0200
> David Hildenbrand <david@redhat.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.

Paolo