KVM: Device assignment permission checks

(cherry picked from commit 3d27e23b17010c668db311140b17bbbb70c78fb9)

Only allow KVM device assignment to attach to devices which:

 - Are not bridges
 - Have BAR resources (assume others are special devices)
 - The user has permissions to use

Assigning a bridge is a configuration error, it's not supported, and
typically doesn't result in the behavior the user is expecting anyway.
Devices without BAR resources are typically chipset components that
also don't have host drivers.  We don't want users to hold such devices
captive or cause system problems by fencing them off into an iommu
domain.  We determine "permission to use" by testing whether the user
has access to the PCI sysfs resource files.  By default a normal user
will not have access to these files, so it provides a good indication
that an administration agent has granted the user access to the device.

[Yang Bai: add missing #include]
[avi: fix comment style]

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Yang Bai <hamo.by@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
long kvm_vm_ioctl_assigned_device(struct kvm *kvm, unsigned ioctl,
				  unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int r;

	switch (ioctl) {
	case KVM_ASSIGN_PCI_DEVICE: {
		struct kvm_assigned_pci_dev assigned_dev;

		r = -EFAULT;
		if (copy_from_user(&assigned_dev, argp, sizeof assigned_dev))
			goto out;
		r = kvm_vm_ioctl_assign_device(kvm, &assigned_dev);
		if (r)
			goto out;
		break;
	}
	case KVM_ASSIGN_IRQ: {
		r = -EOPNOTSUPP;
		break;
	}
	case KVM_ASSIGN_DEV_IRQ: {
		struct kvm_assigned_irq assigned_irq;

		r = -EFAULT;
		if (copy_from_user(&assigned_irq, argp, sizeof assigned_irq))
			goto out;
		r = kvm_vm_ioctl_assign_irq(kvm, &assigned_irq);
		if (r)
			goto out;
		break;
	}
	case KVM_DEASSIGN_DEV_IRQ: {
		struct kvm_assigned_irq assigned_irq;

		r = -EFAULT;
		if (copy_from_user(&assigned_irq, argp, sizeof assigned_irq))
			goto out;
		r = kvm_vm_ioctl_deassign_dev_irq(kvm, &assigned_irq);
		if (r)
			goto out;
		break;
	}
	case KVM_DEASSIGN_PCI_DEVICE: {
		struct kvm_assigned_pci_dev assigned_dev;

		r = -EFAULT;
		if (copy_from_user(&assigned_dev, argp, sizeof assigned_dev))
			goto out;
		r = kvm_vm_ioctl_deassign_device(kvm, &assigned_dev);
		if (r)
			goto out;
		break;
	}
#ifdef KVM_CAP_IRQ_ROUTING
	case KVM_SET_GSI_ROUTING: {
		struct kvm_irq_routing routing;
		struct kvm_irq_routing __user *urouting;
		struct kvm_irq_routing_entry *entries;

		r = -EFAULT;
		if (copy_from_user(&routing, argp, sizeof(routing)))
			goto out;
		r = -EINVAL;
		if (routing.nr >= KVM_MAX_IRQ_ROUTES)
			goto out;
		if (routing.flags)
			goto out;
		r = -ENOMEM;
		entries = vmalloc(routing.nr * sizeof(*entries));
		if (!entries)
			goto out;
		r = -EFAULT;
		urouting = argp;
		if (copy_from_user(entries, urouting->entries,
				   routing.nr * sizeof(*entries)))
			goto out_free_irq_routing;
		r = kvm_set_irq_routing(kvm, entries, routing.nr,
					routing.flags);
	out_free_irq_routing:
		vfree(entries);
		break;
	}
#endif /* KVM_CAP_IRQ_ROUTING */
#ifdef __KVM_HAVE_MSIX
	case KVM_ASSIGN_SET_MSIX_NR: {
		struct kvm_assigned_msix_nr entry_nr;
		r = -EFAULT;
		if (copy_from_user(&entry_nr, argp, sizeof entry_nr))
			goto out;
		r = kvm_vm_ioctl_set_msix_nr(kvm, &entry_nr);
		if (r)
			goto out;
		break;
	}
	case KVM_ASSIGN_SET_MSIX_ENTRY: {
		struct kvm_assigned_msix_entry entry;
		r = -EFAULT;
		if (copy_from_user(&entry, argp, sizeof entry))
			goto out;
		r = kvm_vm_ioctl_set_msix_entry(kvm, &entry);
		if (r)
			goto out;
		break;
	}
#endif
	default:
		r = -ENOTTY;
		break;
	}
out:
	return r;
}

long kvm_vm_ioctl_assigned_device(struct kvm *kvm, unsigned ioctl,
				  unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int r;

	switch (ioctl) {
	case KVM_ASSIGN_PCI_DEVICE: {
		struct kvm_assigned_pci_dev assigned_dev;

		r = -EFAULT;
		if (copy_from_user(&assigned_dev, argp, sizeof assigned_dev))
			goto out;
		r = kvm_vm_ioctl_assign_device(kvm, &assigned_dev);
		if (r)
			goto out;
		break;
	}
	case KVM_ASSIGN_IRQ: {
		r = -EOPNOTSUPP;
		break;
	}
	case KVM_ASSIGN_DEV_IRQ: {
		struct kvm_assigned_irq assigned_irq;

		r = -EFAULT;
		if (copy_from_user(&assigned_irq, argp, sizeof assigned_irq))
			goto out;
		r = kvm_vm_ioctl_assign_irq(kvm, &assigned_irq);
		if (r)
			goto out;
		break;
	}
	case KVM_DEASSIGN_DEV_IRQ: {
		struct kvm_assigned_irq assigned_irq;

		r = -EFAULT;
		if (copy_from_user(&assigned_irq, argp, sizeof assigned_irq))
			goto out;
		r = kvm_vm_ioctl_deassign_dev_irq(kvm, &assigned_irq);
		if (r)
			goto out;
		break;
	}
	case KVM_DEASSIGN_PCI_DEVICE: {
		struct kvm_assigned_pci_dev assigned_dev;

		r = -EFAULT;
		if (copy_from_user(&assigned_dev, argp, sizeof assigned_dev))
			goto out;
		r = kvm_vm_ioctl_deassign_device(kvm, &assigned_dev);
		if (r)
			goto out;
		break;
	}
#ifdef KVM_CAP_IRQ_ROUTING
	case KVM_SET_GSI_ROUTING: {
		struct kvm_irq_routing routing;
		struct kvm_irq_routing __user *urouting;
		struct kvm_irq_routing_entry *entries;

		r = -EFAULT;
		if (copy_from_user(&routing, argp, sizeof(routing)))
			goto out;
		r = -EINVAL;
		if (routing.nr >= KVM_MAX_IRQ_ROUTES)
			goto out;
		if (routing.flags)
			goto out;
		r = -ENOMEM;
		entries = vmalloc(routing.nr * sizeof(*entries));
		if (!entries)
			goto out;
		r = -EFAULT;
		urouting = argp;
		if (copy_from_user(entries, urouting->entries,
				   routing.nr * sizeof(*entries)))
			goto out_free_irq_routing;
		r = kvm_set_irq_routing(kvm, entries, routing.nr,
					routing.flags);
	out_free_irq_routing:
		vfree(entries);
		break;
	}
#endif /* KVM_CAP_IRQ_ROUTING */
#ifdef __KVM_HAVE_MSIX
	case KVM_ASSIGN_SET_MSIX_NR: {
		struct kvm_assigned_msix_nr entry_nr;
		r = -EFAULT;
		if (copy_from_user(&entry_nr, argp, sizeof entry_nr))
			goto out;
		r = kvm_vm_ioctl_set_msix_nr(kvm, &entry_nr);
		if (r)
			goto out;
		break;
	}
	case KVM_ASSIGN_SET_MSIX_ENTRY: {
		struct kvm_assigned_msix_entry entry;
		r = -EFAULT;
		if (copy_from_user(&entry, argp, sizeof entry))
			goto out;
		r = kvm_vm_ioctl_set_msix_entry(kvm, &entry);
		if (r)
			goto out;
		break;
	}
#endif
	default:
		r = -ENOTTY;
		break;
	}
out:
	return r;
}
