abort if it is
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
So the following is a simple solution for unstable
ring mappings security issue: simply detect this and stop.
Will repost series with this later after some testing,
but this is an RFC to get early feedback if any.
hw/vhost.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
hw/vhost.h | 3 +++
2 files changed, 52 insertions(+), 3 deletions(-)
diff --git a/hw/vhost.c b/hw/vhost.c
index 3b3a109..b9e115e 100644
--- a/hw/vhost.c
+++ b/hw/vhost.c
@@ -256,6 +256,33 @@ static inline void vhost_dev_log_resize(struct vhost_dev*
dev, uint64_t size)
dev->log_size = size;
}
+static int vhost_verify_ring_mappings(struct vhost_dev *dev,
+ uint64_t start_addr,
+ uint64_t size)
+{
+ int i;
+ for (i = 0; i < dev->nvqs; ++i) {
+ struct vhost_virtqueue *vq = dev->vqs + i;
+ target_phys_addr_t l;
+ void *p;
+
+ if (!ranges_overlap(start_addr, size, vq->ring_phys, vq->ring_size))
+ continue;
+ l = vq->ring_size;
+ p = cpu_physical_memory_map(vq->ring_phys, &l, 1);
+ if (!p || l != vq->ring_size) {
+ fprintf(stderr, "Unable to map ring buffer for ring %d\n", i);
+ return -ENOMEM;
+ }
+ if (p != vq->ring) {
+ fprintf(stderr, "Ring buffer relocated for ring %d\n", i);
+ return -EBUSY;
+ }
+ cpu_physical_memory_unmap(p, l, 0, 0);
+ }
+ return 0;
+}
+
static void vhost_client_set_memory(CPUPhysMemoryClient *client,
target_phys_addr_t start_addr,
ram_addr_t size,
@@ -284,6 +311,12 @@ static void vhost_client_set_memory(CPUPhysMemoryClient
*client,
if (!dev->started) {
return;
}
+
+ if (dev->started) {
+ r = vhost_verify_ring_mappings(dev, start_addr, size);
+ assert(r >= 0);
+ }
+
if (!dev->log_enabled) {
r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
assert(r >= 0);
@@ -442,6 +475,14 @@ static int vhost_virtqueue_init(struct vhost_dev *dev,
goto fail_alloc_used;
}
+ vq->ring_size = s = l = virtio_queue_get_ring_size(vdev, idx);
+ vq->ring_phys = a = virtio_queue_get_ring(vdev, idx);
+ vq->ring = cpu_physical_memory_map(a, &l, 1);
+ if (!vq->ring || l != s) {
+ r = -ENOMEM;
+ goto fail_alloc_ring;
+ }
+
r = vhost_virtqueue_set_addr(dev, vq, idx, dev->log_enabled);
if (r < 0) {
r = -errno;
@@ -485,6 +526,9 @@ fail_host_notifier:
vdev->binding->guest_notifier(vdev->binding_opaque, idx, false);
fail_guest_notifier:
fail_alloc:
+ cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
+ 0, 0);
+fail_alloc_ring:
cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
0, 0);
fail_alloc_used:
@@ -526,12 +570,14 @@ static void vhost_virtqueue_cleanup(struct vhost_dev *dev,
}
virtio_queue_set_last_avail_idx(vdev, idx, state.num);
assert (r >= 0);
+ cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
+ 0, virtio_queue_get_ring_size(vdev, idx));
cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
0, 0);
cpu_physical_memory_unmap(vq->avail, virtio_queue_get_avail_size(vdev,
idx),
0, 0);
cpu_physical_memory_unmap(vq->desc, virtio_queue_get_desc_size(vdev, idx),
0, 0);
}
int vhost_dev_init(struct vhost_dev *hdev, int devfd)
diff --git a/hw/vhost.h b/hw/vhost.h
index 48b52c7..86dd834 100644
--- a/hw/vhost.h
+++ b/hw/vhost.h
@@ -14,6 +14,9 @@ struct vhost_virtqueue {
int num;
unsigned long long used_phys;
unsigned used_size;
+ void *ring;
+ unsigned long long ring_phys;
+ unsigned ring_size;
};
typedef unsigned long vhost_log_chunk_t;
--
1.7.0.18.g0d53a5
