[RFC v3 05/19] Add validation ops vector

[John Johnson]

Validates cases where the return values aren't fully trusted
(prep work for vfio-user, where the return values from the
remote process aren't trusted)

Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
---
 include/hw/vfio/vfio-common.h | 21 ++++++++++++++
 hw/vfio/pci.c                 | 67 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 43fa948..c0dbbfb 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -125,6 +125,7 @@ typedef struct VFIOHostDMAWindow {
 
 typedef struct VFIODeviceOps VFIODeviceOps;
 typedef struct VFIODevIO VFIODevIO;
+typedef struct VFIOValidOps VFIOValidOps;
 
 typedef struct VFIODevice {
     QLIST_ENTRY(VFIODevice) next;
@@ -141,6 +142,7 @@ typedef struct VFIODevice {
     bool enable_migration;
     VFIODeviceOps *ops;
     VFIODevIO *io_ops;
+    VFIOValidOps *valid_ops;
     unsigned int num_irqs;
     unsigned int num_regions;
     unsigned int flags;
@@ -214,6 +216,25 @@ struct VFIOContIO {
 extern VFIODevIO vfio_dev_io_ioctl;
 extern VFIOContIO vfio_cont_io_ioctl;
 
+/*
+ * This ops vector allows for bus-specific verification
+ * routines in cases where the server may not be fully
+ * trusted.
+ */
+struct VFIOValidOps {
+    int (*validate_get_info)(VFIODevice *vdev, struct vfio_device_info *info);
+    int (*validate_get_region_info)(VFIODevice *vdev,
+                                    struct vfio_region_info *info, int *fd);
+    int (*validate_get_irq_info)(VFIODevice *vdev, struct vfio_irq_info *info);
+};
+
+#define VDEV_VALID_INFO(vdev, info) \
+    ((vdev)->valid_ops->validate_get_info((vdev), (info)))
+#define VDEV_VALID_REGION_INFO(vdev, info, fd) \
+    ((vdev)->valid_ops->validate_get_region_info((vdev), (info), (fd)))
+#define VDEV_VALID_IRQ_INFO(vdev, irq) \
+    ((vdev)->valid_ops->validate_get_irq_info((vdev), (irq)))
+
 #endif /* CONFIG_LINUX */
 
 typedef struct VFIOGroup {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 28f21f8..6e2ce35 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3371,3 +3371,70 @@ static void register_vfio_pci_dev_type(void)
 }
 
 type_init(register_vfio_pci_dev_type)
+
+
+/*
+ * PCI validation ops - used when return values need
+ * validation before use
+ */
+
+static int vfio_pci_valid_info(VFIODevice *vbasedev,
+                               struct vfio_device_info *info)
+{
+    /* must be PCI */
+    if ((info->flags & VFIO_DEVICE_FLAGS_PCI) == 0) {
+        return -EINVAL;
+    }
+    /* only other valid flag is reset */
+    if (info->flags & ~(VFIO_DEVICE_FLAGS_PCI | VFIO_DEVICE_FLAGS_RESET)) {
+        return -EINVAL;
+    }
+    /* account for extra migration region */
+    if (info->num_regions > VFIO_PCI_NUM_REGIONS + 1) {
+        return -EINVAL;
+    }
+    if (info->num_irqs > VFIO_PCI_NUM_IRQS) {
+        return -EINVAL;
+    }
+    return 0;
+}
+
+static int vfio_pci_valid_region_info(VFIODevice *vbasedev,
+                                          struct vfio_region_info *info,
+                                          int *fd)
+{
+    if (info->flags & ~(VFIO_REGION_INFO_FLAG_READ |
+                        VFIO_REGION_INFO_FLAG_WRITE |
+                        VFIO_REGION_INFO_FLAG_MMAP |
+                        VFIO_REGION_INFO_FLAG_CAPS)) {
+        return -EINVAL;
+    }
+    if (info->index > vbasedev->num_regions) {
+        return -EINVAL;
+    }
+    /* cap_offset in valid area */
+    if ((info->flags & VFIO_REGION_INFO_FLAG_CAPS) &&
+        (info->cap_offset < sizeof(*info) || info->cap_offset > info->argsz)) {
+        return -EINVAL;
+    }
+    return 0;
+}
+
+static int vfio_pci_valid_irq_info(VFIODevice *vbasedev,
+                                 struct vfio_irq_info *info)
+{
+    if (info->flags & ~(VFIO_IRQ_INFO_EVENTFD | VFIO_IRQ_INFO_MASKABLE |
+                        VFIO_IRQ_INFO_AUTOMASKED | VFIO_IRQ_INFO_NORESIZE)) {
+        return -EINVAL;
+    }
+    if (info->index > vbasedev->num_irqs) {
+        return -EINVAL;
+    }
+    return 0;
+}
+
+struct VFIOValidOps vfio_pci_valid_ops = {
+    .validate_get_info = vfio_pci_valid_info,
+    .validate_get_region_info = vfio_pci_valid_region_info,
+    .validate_get_irq_info = vfio_pci_valid_irq_info,
+};
-- 
1.8.3.1