Linux Virtualization - Oct 2023 - [PATCH vhost v3 0/4] strictly check the acccess to the common cfg

1. fix the length of the pci_iomap_range() to the modern common cfg
2. add common cfg size check for the VIRTIO_F_NOTIF_CONFIG_DATA,
VIRTIO_F_RING_RESET
3. add build size check to the new common cfg items

Xuan Zhuo (4):
  virtio: add definition of VIRTIO_F_NOTIF_CONFIG_DATA feature bit
  virtio_pci: fix the common cfg map size
  virtio_pci: add check for common cfg size
  virtio_pci: add build offset check for the new common cfg items

 drivers/virtio/virtio_pci_modern.c     | 36 ++++++++++++++++++++++++++
 drivers/virtio/virtio_pci_modern_dev.c |  8 ++++--
 include/linux/virtio_pci_modern.h      |  1 +
 include/uapi/linux/virtio_config.h     |  5 ++++
 4 files changed, 48 insertions(+), 2 deletions(-)

--
2.32.0.3.g01195cf9f

This patch adds the definition of VIRTIO_F_NOTIF_CONFIG_DATA feature bit
in the relevant header file.

This feature indicates that the driver uses the data provided by the
device as a virtqueue identifier in available buffer notifications.

It comes from here:
    https://github.com/oasis-tcs/virtio-spec/issues/89

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 include/uapi/linux/virtio_config.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/uapi/linux/virtio_config.h
b/include/uapi/linux/virtio_config.h
index 2c712c654165..8881aea60f6f 100644
--- a/include/uapi/linux/virtio_config.h
+++ b/include/uapi/linux/virtio_config.h
@@ -105,6 +105,11 @@
  */
 #define VIRTIO_F_NOTIFICATION_DATA	38
 
+/* This feature indicates that the driver uses the data provided by the device
+ * as a virtqueue identifier in available buffer notifications.
+ */
+#define VIRTIO_F_NOTIF_CONFIG_DATA	39
+
 /*
  * This feature indicates that the driver can reset a queue individually.
  */
-- 
2.32.0.3.g01195cf9f

The function vp_modern_map_capability() takes the size parameter,
which corresponds to the size of virtio_pci_common_cfg. As a result,
this indicates the size of memory area to map.

Now the size is the size of virtio_pci_common_cfg, but some feature(such
as the _F_RING_RESET) needs the virtio_pci_modern_common_cfg, so this
commit changes the size to the size of virtio_pci_modern_common_cfg.

Fixes: 0b50cece0b78 ("virtio_pci: introduce helper to get/set queue
reset")
Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_pci_modern_dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index aad7d9296e77..9cb601e16688 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -291,7 +291,7 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 	err = -EINVAL;
 	mdev->common = vp_modern_map_capability(mdev, common,
 				      sizeof(struct virtio_pci_common_cfg), 4,
-				      0, sizeof(struct virtio_pci_common_cfg),
+				      0, sizeof(struct virtio_pci_modern_common_cfg),
 				      NULL, NULL);
 	if (!mdev->common)
 		goto err_map_common;
-- 
2.32.0.3.g01195cf9f

Some buggy devices, the common cfg size may not match the features.

This patch checks the common cfg size for the
features(VIRTIO_F_NOTIF_CONFIG_DATA, VIRTIO_F_RING_RESET). When the
common cfg size does not match the corresponding feature, we fail the
probe and print error message.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_pci_modern.c     | 36 ++++++++++++++++++++++++++
 drivers/virtio/virtio_pci_modern_dev.c |  2 +-
 include/linux/virtio_pci_modern.h      |  1 +
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index d6bb68ba84e5..6a8f5ff05636 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -39,6 +39,39 @@ static void vp_transport_features(struct virtio_device *vdev,
u64 features)
 		__virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
 }
 
+static int __vp_check_common_size_one_feature(struct virtio_device *vdev, u32
fbit,
+					    u32 offset, const char *fname)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	if (!__virtio_test_bit(vdev, fbit))
+		return 0;
+
+	if (likely(vp_dev->mdev.common_len >= offset))
+		return 0;
+
+	dev_err(&vdev->dev,
+		"virtio: common cfg size(%ld) does not match the feature %s\n",
+		vp_dev->mdev.common_len, fname);
+
+	return -EINVAL;
+}
+
+#define vp_check_common_size_one_feature(vdev, fbit, field) \
+	__vp_check_common_size_one_feature(vdev, fbit, \
+		offsetofend(struct virtio_pci_modern_common_cfg, field), #fbit)
+
+static int vp_check_common_size(struct virtio_device *vdev)
+{
+	if (vp_check_common_size_one_feature(vdev, VIRTIO_F_NOTIF_CONFIG_DATA,
queue_notify_data))
+		return -EINVAL;
+
+	if (vp_check_common_size_one_feature(vdev, VIRTIO_F_RING_RESET, queue_reset))
+		return -EINVAL;
+
+	return 0;
+}
+
 /* virtio config->finalize_features() implementation */
 static int vp_finalize_features(struct virtio_device *vdev)
 {
@@ -57,6 +90,9 @@ static int vp_finalize_features(struct virtio_device *vdev)
 		return -EINVAL;
 	}
 
+	if (vp_check_common_size(vdev))
+		return -EINVAL;
+
 	vp_modern_set_features(&vp_dev->mdev, vdev->features);
 
 	return 0;
diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index 9cb601e16688..33f319da1558 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -292,7 +292,7 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 	mdev->common = vp_modern_map_capability(mdev, common,
 				      sizeof(struct virtio_pci_common_cfg), 4,
 				      0, sizeof(struct virtio_pci_modern_common_cfg),
-				      NULL, NULL);
+				      &mdev->common_len, NULL);
 	if (!mdev->common)
 		goto err_map_common;
 	mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
index 067ac1d789bc..edf62bae0474 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -28,6 +28,7 @@ struct virtio_pci_modern_device {
 	/* So we can sanity-check accesses. */
 	size_t notify_len;
 	size_t device_len;
+	size_t common_len;
 
 	/* Capability for when we need to map notifications per-vq. */
 	int notify_map_cap;
-- 
2.32.0.3.g01195cf9f

Add checks to the check_offsets(void) for queue_notify_data and
queue_reset.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_pci_modern_dev.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index 33f319da1558..e2a1fe7bb66c 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -203,6 +203,10 @@ static inline void check_offsets(void)
 		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI ! 		     offsetof(struct
virtio_pci_common_cfg, queue_used_hi));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NDATA !+		     offsetof(struct
virtio_pci_modern_common_cfg, queue_notify_data));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_RESET !+		     offsetof(struct
virtio_pci_modern_common_cfg, queue_reset));
 }
 
 /*
-- 
2.32.0.3.g01195cf9f