From: Paul Mackerras <paulus@ozlabs.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
"Christoffer Dall" <christoffer.dall@linaro.org>,
"Marc Zyngier" <marc.zyngier@arm.com>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"James Hogan" <james.hogan@imgtec.com>,
kernel-hardening@lists.openwall.com,
"Kees Cook" <keescook@chromium.org>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH v2 0/2] KVM: fixes for the kernel-hardening tree
Date: Fri, 27 Oct 2017 16:25:03 +1100 [thread overview]
Message-ID: <20171027052503.GB27483@fergus.ozlabs.ibm.com> (raw)
In-Reply-To: <20171026134547.23664-1-pbonzini@redhat.com>
On Thu, Oct 26, 2017 at 03:45:45PM +0200, Paolo Bonzini wrote:
> Four KVM ioctls (KVM_GET/SET_CPUID2 on x86, KVM_GET/SET_ONE_REG on
> ARM and s390) directly access the kvm_vcpu_arch struct. 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 on those architectures.
>
> The kvm_vcpu_arch struct is embedded in the kvm_vcpu struct and the
> corresponding slab cache is allocated by architecture-independent code.
> It is enough, for simplicity, to whitelist the whole sub-struct and
> only touch one place of the KVM code. Later, any further restrictions
> can be applied in the KVM tree.
I checked arch/powerpc/kvm, and all the copy_to/from_user calls are
accessing the stack or memory allocated with kzalloc or kvzalloc, so
if I understand correctly, we should be OK there.
Paul.
WARNING: multiple messages have this Message-ID (diff)
From: Paul Mackerras <paulus@ozlabs.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
"Christoffer Dall" <christoffer.dall@linaro.org>,
"Marc Zyngier" <marc.zyngier@arm.com>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"James Hogan" <james.hogan@imgtec.com>,
kernel-hardening@lists.openwall.com,
"Kees Cook" <keescook@chromium.org>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: [kernel-hardening] Re: [PATCH v2 0/2] KVM: fixes for the kernel-hardening tree
Date: Fri, 27 Oct 2017 16:25:03 +1100 [thread overview]
Message-ID: <20171027052503.GB27483@fergus.ozlabs.ibm.com> (raw)
In-Reply-To: <20171026134547.23664-1-pbonzini@redhat.com>
On Thu, Oct 26, 2017 at 03:45:45PM +0200, Paolo Bonzini wrote:
> Four KVM ioctls (KVM_GET/SET_CPUID2 on x86, KVM_GET/SET_ONE_REG on
> ARM and s390) directly access the kvm_vcpu_arch struct. 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 on those architectures.
>
> The kvm_vcpu_arch struct is embedded in the kvm_vcpu struct and the
> corresponding slab cache is allocated by architecture-independent code.
> It is enough, for simplicity, to whitelist the whole sub-struct and
> only touch one place of the KVM code. Later, any further restrictions
> can be applied in the KVM tree.
I checked arch/powerpc/kvm, and all the copy_to/from_user calls are
accessing the stack or memory allocated with kzalloc or kvzalloc, so
if I understand correctly, we should be OK there.
Paul.
next prev parent reply other threads:[~2017-10-27 5:25 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-26 13:45 [PATCH v2 0/2] KVM: fixes for the kernel-hardening tree Paolo Bonzini
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
2017-10-26 13:45 ` [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch Paolo Bonzini
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
2017-10-26 14:13 ` Cornelia Huck
2017-10-26 14:13 ` [kernel-hardening] " Cornelia Huck
2017-10-26 14:21 ` Christoffer Dall
2017-10-26 14:21 ` [kernel-hardening] " Christoffer Dall
2017-10-26 14:34 ` Marc Zyngier
2017-10-26 14:34 ` [kernel-hardening] " Marc Zyngier
2017-10-26 14:51 ` Christian Borntraeger
2017-10-26 14:51 ` [kernel-hardening] " Christian Borntraeger
2017-10-30 23:28 ` [kernel-hardening] " Eric Biggers
2017-10-30 23:51 ` Kees Cook
2017-10-26 13:45 ` [PATCH 2/2] kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl Paolo Bonzini
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
2017-10-26 13:48 ` Kees Cook
2017-10-26 13:48 ` [kernel-hardening] " Kees Cook
2017-11-30 20:40 ` Kees Cook
2017-11-30 20:40 ` [kernel-hardening] " Kees Cook
2017-12-01 8:29 ` Paolo Bonzini
2017-12-01 8:29 ` [kernel-hardening] " Paolo Bonzini
2017-10-27 5:25 ` Paul Mackerras [this message]
2017-10-27 5:25 ` [kernel-hardening] Re: [PATCH v2 0/2] KVM: fixes for the kernel-hardening tree Paul Mackerras
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