KVM: Device assignment: Check for privileges before assigning irq

Even though we don't share irqs at the moment, we should ensure
regular user processes don't try to allocate system resources.

We check for capability to access IO devices (CAP_SYS_RAWIO) before
we request_irq on behalf of the guest.

Noticed by Avi.

Signed-off-by: Amit Shah <amit.shah@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4a033757a19e28d62730ff3d6bf286a23bc1a35e..fffdf4f69c5a772b69c102447910ebcc67a3dab5 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -191,6 +191,11 @@ static int kvm_vm_ioctl_assign_irq(struct kvm *kvm,
                  kvm_assigned_dev_interrupt_work_handler);
 
        if (irqchip_in_kernel(kvm)) {
+               if (!capable(CAP_SYS_RAWIO)) {
+                       return -EPERM;
+                       goto out;
+               }
+
                if (assigned_irq->host_irq)
                        match->host_irq = assigned_irq->host_irq;
                else