Patchwork [oneiric,CVE,1/1] KVM: Remove ability to assign a device without iommu support

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Submitter Andy Whitcroft
Date March 12, 2012, 2:06 p.m.
Message ID <1331561197-16611-4-git-send-email-apw@canonical.com>
Download mbox | patch
Permalink /patch/146108/
State New
Headers show

Comments

Andy Whitcroft - March 12, 2012, 2:06 p.m.
From: Alex Williamson <alex.williamson@redhat.com>

This option has no users and it exposes a security hole that we
can allow devices to be assigned without iommu protection.  Make
KVM_DEV_ASSIGN_ENABLE_IOMMU a mandatory option.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

(cherry picked from commit 423873736b78f549fbfa2f715f2e4de7e6c5e1e9)
CVE-2011-4347
BugLink: http://bugs.launchpad.net/bugs/897812
Signed-off-by: Andy Whitcroft <apw@canonical.com>
---
 Documentation/virtual/kvm/api.txt |    3 +++
 virt/kvm/assigned-dev.c           |   18 +++++++++---------
 2 files changed, 12 insertions(+), 9 deletions(-)

Patch

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 42542eb..3628be1 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1118,6 +1118,9 @@  following flags are specified:
 /* Depends on KVM_CAP_IOMMU */
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
 
+The KVM_DEV_ASSIGN_ENABLE_IOMMU flag is a mandatory option to ensure
+isolation of the device.  Usages not specifying this flag are deprecated.
+
 4.49 KVM_DEASSIGN_PCI_DEVICE
 
 Capability: KVM_CAP_DEVICE_DEASSIGNMENT
diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 2e8c727..49b402c 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -544,6 +544,9 @@  static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 	struct pci_dev *dev;
 	u8 header_type;
 
+	if (!(assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU))
+		return -EINVAL;
+
 	mutex_lock(&kvm->lock);
 	idx = srcu_read_lock(&kvm->srcu);
 
@@ -613,16 +616,14 @@  static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 
 	list_add(&match->list, &kvm->arch.assigned_dev_head);
 
-	if (assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU) {
-		if (!kvm->arch.iommu_domain) {
-			r = kvm_iommu_map_guest(kvm);
-			if (r)
-				goto out_list_del;
-		}
-		r = kvm_assign_device(kvm, match);
+	if (!kvm->arch.iommu_domain) {
+		r = kvm_iommu_map_guest(kvm);
 		if (r)
 			goto out_list_del;
 	}
+	r = kvm_assign_device(kvm, match);
+	if (r)
+		goto out_list_del;
 
 out:
 	srcu_read_unlock(&kvm->srcu, idx);
@@ -662,8 +663,7 @@  static int kvm_vm_ioctl_deassign_device(struct kvm *kvm,
 		goto out;
 	}
 
-	if (match->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU)
-		kvm_deassign_device(kvm, match);
+	kvm_deassign_device(kvm, match);
 
 	kvm_free_assigned_device(kvm, match);