* [kernel-hardening] [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
@ 2017-10-26 13:45 ` Paolo Bonzini
0 siblings, 0 replies; 24+ messages in thread
From: Paolo Bonzini @ 2017-10-26 13:45 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Christoffer Dall, Marc Zyngier, Christian Borntraeger,
Cornelia Huck, James Hogan, Paul Mackerras, kernel-hardening,
Kees Cook, Christian Borntraeger, Christoffer Dall,
Radim Krčmář
On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
KVM is completely broken on those architectures with usercopy hardening
enabled.
For now, allow writing to the entire struct on all architectures.
The KVM tree will not refine this to an architecture-specific
subset of struct kvm_vcpu_arch.
Cc: kernel-hardening@lists.openwall.com
Cc: Kees Cook <keescook@chromium.org>
Cc: Christian Borntraeger <borntraeger@redhat.com>
Cc: Christoffer Dall <cdall@linaro.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
virt/kvm/kvm_main.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4d81f6ded88e..b4809ccfdfa1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
/* A kmem cache lets us meet the alignment requirements of fx_save. */
if (!vcpu_align)
vcpu_align = __alignof__(struct kvm_vcpu);
- kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
- 0, NULL);
+ kvm_vcpu_cache =
+ kmem_cache_create_usercopy("kvm_vcpu",
+ sizeof(struct kvm_vcpu), vcpu_align,
+ 0, offsetof(struct kvm_vcpu, arch),
+ sizeof_field(struct kvm_vcpu, arch),
+ NULL);
if (!kvm_vcpu_cache) {
r = -ENOMEM;
goto out_free_3;
--
2.14.2
^ permalink raw reply related [flat|nested] 24+ messages in thread
* Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
@ 2017-10-26 14:13 ` Cornelia Huck
-1 siblings, 0 replies; 24+ messages in thread
From: Cornelia Huck @ 2017-10-26 14:13 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Christoffer Dall, Marc Zyngier,
Christian Borntraeger, James Hogan, Paul Mackerras,
kernel-hardening, Kees Cook, Christoffer Dall,
Radim Krčmář
On Thu, 26 Oct 2017 15:45:46 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4d81f6ded88e..b4809ccfdfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
> /* A kmem cache lets us meet the alignment requirements of fx_save. */
> if (!vcpu_align)
> vcpu_align = __alignof__(struct kvm_vcpu);
> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> - 0, NULL);
> + kvm_vcpu_cache =
> + kmem_cache_create_usercopy("kvm_vcpu",
> + sizeof(struct kvm_vcpu), vcpu_align,
> + 0, offsetof(struct kvm_vcpu, arch),
> + sizeof_field(struct kvm_vcpu, arch),
> + NULL);
> if (!kvm_vcpu_cache) {
> r = -ENOMEM;
> goto out_free_3;
Acked-by: Cornelia Huck <cohuck@redhat.com>
^ permalink raw reply [flat|nested] 24+ messages in thread
* [kernel-hardening] Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
@ 2017-10-26 14:13 ` Cornelia Huck
0 siblings, 0 replies; 24+ messages in thread
From: Cornelia Huck @ 2017-10-26 14:13 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Christoffer Dall, Marc Zyngier,
Christian Borntraeger, James Hogan, Paul Mackerras,
kernel-hardening, Kees Cook, Christoffer Dall,
Radim Krčmář
On Thu, 26 Oct 2017 15:45:46 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4d81f6ded88e..b4809ccfdfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
> /* A kmem cache lets us meet the alignment requirements of fx_save. */
> if (!vcpu_align)
> vcpu_align = __alignof__(struct kvm_vcpu);
> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> - 0, NULL);
> + kvm_vcpu_cache =
> + kmem_cache_create_usercopy("kvm_vcpu",
> + sizeof(struct kvm_vcpu), vcpu_align,
> + 0, offsetof(struct kvm_vcpu, arch),
> + sizeof_field(struct kvm_vcpu, arch),
> + NULL);
> if (!kvm_vcpu_cache) {
> r = -ENOMEM;
> goto out_free_3;
Acked-by: Cornelia Huck <cohuck@redhat.com>
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
@ 2017-10-26 14:21 ` Christoffer Dall
-1 siblings, 0 replies; 24+ messages in thread
From: Christoffer Dall @ 2017-10-26 14:21 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Marc Zyngier, Christian Borntraeger,
Cornelia Huck, James Hogan, Paul Mackerras, kernel-hardening,
Kees Cook, Christian Borntraeger, Radim Krčmář
On Thu, Oct 26, 2017 at 3:45 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4d81f6ded88e..b4809ccfdfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
> /* A kmem cache lets us meet the alignment requirements of fx_save. */
> if (!vcpu_align)
> vcpu_align = __alignof__(struct kvm_vcpu);
> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> - 0, NULL);
> + kvm_vcpu_cache =
> + kmem_cache_create_usercopy("kvm_vcpu",
> + sizeof(struct kvm_vcpu), vcpu_align,
> + 0, offsetof(struct kvm_vcpu, arch),
> + sizeof_field(struct kvm_vcpu, arch),
> + NULL);
> if (!kvm_vcpu_cache) {
> r = -ENOMEM;
> goto out_free_3;
> --
> 2.14.2
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
^ permalink raw reply [flat|nested] 24+ messages in thread
* [kernel-hardening] Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
@ 2017-10-26 14:21 ` Christoffer Dall
0 siblings, 0 replies; 24+ messages in thread
From: Christoffer Dall @ 2017-10-26 14:21 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Marc Zyngier, Christian Borntraeger,
Cornelia Huck, James Hogan, Paul Mackerras, kernel-hardening,
Kees Cook, Christian Borntraeger, Radim Krčmář
On Thu, Oct 26, 2017 at 3:45 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4d81f6ded88e..b4809ccfdfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
> /* A kmem cache lets us meet the alignment requirements of fx_save. */
> if (!vcpu_align)
> vcpu_align = __alignof__(struct kvm_vcpu);
> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> - 0, NULL);
> + kvm_vcpu_cache =
> + kmem_cache_create_usercopy("kvm_vcpu",
> + sizeof(struct kvm_vcpu), vcpu_align,
> + 0, offsetof(struct kvm_vcpu, arch),
> + sizeof_field(struct kvm_vcpu, arch),
> + NULL);
> if (!kvm_vcpu_cache) {
> r = -ENOMEM;
> goto out_free_3;
> --
> 2.14.2
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
@ 2017-10-26 14:34 ` Marc Zyngier
-1 siblings, 0 replies; 24+ messages in thread
From: Marc Zyngier @ 2017-10-26 14:34 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Christoffer Dall, Christian Borntraeger,
Cornelia Huck, James Hogan, Paul Mackerras, kernel-hardening,
Kees Cook, Christian Borntraeger, Christoffer Dall,
Radim Krčmář
On Thu, Oct 26 2017 at 3:45:46 pm BST, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny.
^ permalink raw reply [flat|nested] 24+ messages in thread
* [kernel-hardening] Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
@ 2017-10-26 14:34 ` Marc Zyngier
0 siblings, 0 replies; 24+ messages in thread
From: Marc Zyngier @ 2017-10-26 14:34 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Christoffer Dall, Christian Borntraeger,
Cornelia Huck, James Hogan, Paul Mackerras, kernel-hardening,
Kees Cook, Christian Borntraeger, Christoffer Dall,
Radim Krčmář
On Thu, Oct 26 2017 at 3:45:46 pm BST, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
@ 2017-10-26 14:51 ` Christian Borntraeger
-1 siblings, 0 replies; 24+ messages in thread
From: Christian Borntraeger @ 2017-10-26 14:51 UTC (permalink / raw)
To: Paolo Bonzini, linux-kernel, kvm
Cc: Christoffer Dall, Marc Zyngier, Cornelia Huck, James Hogan,
Paul Mackerras, kernel-hardening, Kees Cook,
Christian Borntraeger, Christoffer Dall,
Radim Krčmář
On 10/26/2017 03:45 PM, Paolo Bonzini wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
You wish? Not yet Paolo :-)
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4d81f6ded88e..b4809ccfdfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
> /* A kmem cache lets us meet the alignment requirements of fx_save. */
> if (!vcpu_align)
> vcpu_align = __alignof__(struct kvm_vcpu);
> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> - 0, NULL);
> + kvm_vcpu_cache =
> + kmem_cache_create_usercopy("kvm_vcpu",
> + sizeof(struct kvm_vcpu), vcpu_align,
> + 0, offsetof(struct kvm_vcpu, arch),
> + sizeof_field(struct kvm_vcpu, arch),
> + NULL);
> if (!kvm_vcpu_cache) {
> r = -ENOMEM;
> goto out_free_3;
>
^ permalink raw reply [flat|nested] 24+ messages in thread
* [kernel-hardening] Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
@ 2017-10-26 14:51 ` Christian Borntraeger
0 siblings, 0 replies; 24+ messages in thread
From: Christian Borntraeger @ 2017-10-26 14:51 UTC (permalink / raw)
To: Paolo Bonzini, linux-kernel, kvm
Cc: Christoffer Dall, Marc Zyngier, Cornelia Huck, James Hogan,
Paul Mackerras, kernel-hardening, Kees Cook,
Christian Borntraeger, Christoffer Dall,
Radim Krčmář
On 10/26/2017 03:45 PM, Paolo Bonzini wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
You wish? Not yet Paolo :-)
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4d81f6ded88e..b4809ccfdfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
> /* A kmem cache lets us meet the alignment requirements of fx_save. */
> if (!vcpu_align)
> vcpu_align = __alignof__(struct kvm_vcpu);
> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> - 0, NULL);
> + kvm_vcpu_cache =
> + kmem_cache_create_usercopy("kvm_vcpu",
> + sizeof(struct kvm_vcpu), vcpu_align,
> + 0, offsetof(struct kvm_vcpu, arch),
> + sizeof_field(struct kvm_vcpu, arch),
> + NULL);
> if (!kvm_vcpu_cache) {
> r = -ENOMEM;
> goto out_free_3;
>
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [kernel-hardening] [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
2017-10-26 13:45 ` [kernel-hardening] " Paolo Bonzini
` (4 preceding siblings ...)
(?)
@ 2017-10-30 23:28 ` Eric Biggers
2017-10-30 23:51 ` Kees Cook
-1 siblings, 1 reply; 24+ messages in thread
From: Eric Biggers @ 2017-10-30 23:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Christoffer Dall, Marc Zyngier,
Christian Borntraeger, Cornelia Huck, James Hogan,
Paul Mackerras, kernel-hardening, Kees Cook,
Christian Borntraeger, Christoffer Dall,
Radim Krčmář
On Thu, Oct 26, 2017 at 03:45:46PM +0200, Paolo Bonzini wrote:
> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
> KVM is completely broken on those architectures with usercopy hardening
> enabled.
>
> For now, allow writing to the entire struct on all architectures.
> The KVM tree will not refine this to an architecture-specific
> subset of struct kvm_vcpu_arch.
>
> Cc: kernel-hardening@lists.openwall.com
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Christian Borntraeger <borntraeger@redhat.com>
> Cc: Christoffer Dall <cdall@linaro.org>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> virt/kvm/kvm_main.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4d81f6ded88e..b4809ccfdfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
> /* A kmem cache lets us meet the alignment requirements of fx_save. */
> if (!vcpu_align)
> vcpu_align = __alignof__(struct kvm_vcpu);
> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> - 0, NULL);
> + kvm_vcpu_cache =
> + kmem_cache_create_usercopy("kvm_vcpu",
> + sizeof(struct kvm_vcpu), vcpu_align,
> + 0, offsetof(struct kvm_vcpu, arch),
> + sizeof_field(struct kvm_vcpu, arch),
> + NULL);
Doesn't it need to be 'vcpu_size' instead of 'sizeof(struct kvm_vcpu)'?
Eric
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [kernel-hardening] [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch
2017-10-30 23:28 ` [kernel-hardening] " Eric Biggers
@ 2017-10-30 23:51 ` Kees Cook
0 siblings, 0 replies; 24+ messages in thread
From: Kees Cook @ 2017-10-30 23:51 UTC (permalink / raw)
To: Eric Biggers
Cc: Paolo Bonzini, LKML, KVM, Christoffer Dall, Marc Zyngier,
Christian Borntraeger, Cornelia Huck, James Hogan,
Paul Mackerras, kernel-hardening, Christian Borntraeger,
Christoffer Dall, Radim Krčmář
On Mon, Oct 30, 2017 at 4:28 PM, Eric Biggers <ebiggers3@gmail.com> wrote:
> On Thu, Oct 26, 2017 at 03:45:46PM +0200, Paolo Bonzini wrote:
>> On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region
>> taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86)
>> or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area,
>> KVM is completely broken on those architectures with usercopy hardening
>> enabled.
>>
>> For now, allow writing to the entire struct on all architectures.
>> The KVM tree will not refine this to an architecture-specific
>> subset of struct kvm_vcpu_arch.
>>
>> Cc: kernel-hardening@lists.openwall.com
>> Cc: Kees Cook <keescook@chromium.org>
>> Cc: Christian Borntraeger <borntraeger@redhat.com>
>> Cc: Christoffer Dall <cdall@linaro.org>
>> Cc: Radim Krčmář <rkrcmar@redhat.com>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>> virt/kvm/kvm_main.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>> index 4d81f6ded88e..b4809ccfdfa1 100644
>> --- a/virt/kvm/kvm_main.c
>> +++ b/virt/kvm/kvm_main.c
>> @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
>> /* A kmem cache lets us meet the alignment requirements of fx_save. */
>> if (!vcpu_align)
>> vcpu_align = __alignof__(struct kvm_vcpu);
>> - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
>> - 0, NULL);
>> + kvm_vcpu_cache =
>> + kmem_cache_create_usercopy("kvm_vcpu",
>> + sizeof(struct kvm_vcpu), vcpu_align,
>> + 0, offsetof(struct kvm_vcpu, arch),
>> + sizeof_field(struct kvm_vcpu, arch),
>> + NULL);
>
> Doesn't it need to be 'vcpu_size' instead of 'sizeof(struct kvm_vcpu)'?
Oh, yikes, yes.
$ git grep '\bkvm_init('
arch/mips/kvm/mips.c: ret = kvm_init(NULL, sizeof(struct kvm_vcpu),
0, THIS_MODULE);
arch/powerpc/kvm/book3s.c: r = kvm_init(NULL, sizeof(struct
kvm_vcpu), 0, THIS_MODULE);
arch/powerpc/kvm/e500.c: r = kvm_init(NULL, sizeof(struct
kvmppc_vcpu_e500), 0, THIS_MODULE);
arch/powerpc/kvm/e500mc.c: r = kvm_init(NULL, sizeof(struct
kvmppc_vcpu_e500), 0, THIS_MODULE);
arch/s390/kvm/kvm-s390.c: return kvm_init(NULL, sizeof(struct
kvm_vcpu), 0, THIS_MODULE);
arch/x86/kvm/svm.c: return kvm_init(&svm_x86_ops, sizeof(struct vcpu_svm),
arch/x86/kvm/vmx.c: int r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx),
include/linux/kvm_host.h:int kvm_init(void *opaque, unsigned
vcpu_size, unsigned vcpu_align,
virt/kvm/arm/arm.c: int rc = kvm_init(NULL, sizeof(struct
kvm_vcpu), 0, THIS_MODULE);
I'll fix this up.
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 24+ messages in thread