@@ -43,6 +43,8 @@
#include <linux/swap.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
+#include <linux/namei.h>
+#include <linux/fs.h>
#include <asm/processor.h>
#include <asm/io.h>
@@ -575,12 +577,73 @@ out:
return r;
}
+/*
+ * We want to test whether the caller has been granted permissions to
+ * use this device. To be able to configure and control the device,
+ * the user needs access to PCI configuration space and BAR resources.
+ * These are accessed through PCI sysfs. PCI config space is often
+ * passed to the process calling this ioctl via file descriptor, so we
+ * can't rely on access to that file. We can check for permissions
+ * on each of the BAR resource files, which is a pretty clear
+ * indicator that the user has been granted access to the device.
+ */
+static int probe_sysfs_permissions(struct pci_dev *dev)
+{
+#ifdef CONFIG_SYSFS
+ int i;
+ bool bar_found = false;
+
+ for (i = PCI_STD_RESOURCES; i <= PCI_STD_RESOURCE_END; i++) {
+ char *kpath, *syspath;
+ struct path path;
+ struct inode *inode;
+ int r;
+
+ if (!pci_resource_len(dev, i))
+ continue;
+
+ kpath = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
+ if (!kpath)
+ return -ENOMEM;
+
+ /* Per sysfs-rules, sysfs is always at /sys */
+ syspath = kasprintf(GFP_KERNEL, "/sys%s/resource%d", kpath, i);
+ kfree(kpath);
+ if (!syspath)
+ return -ENOMEM;
+
+ r = kern_path(syspath, LOOKUP_FOLLOW, &path);
+ kfree(syspath);
+ if (r)
+ return r;
+
+ inode = path.dentry->d_inode;
+
+ r = inode_permission(inode, MAY_READ | MAY_WRITE | MAY_ACCESS);
+ path_put(&path);
+ if (r)
+ return r;
+
+ bar_found = true;
+ }
+
+ /* If no resources, probably something special */
+ if (!bar_found)
+ return -EPERM;
+
+ return 0;
+#else
+ return -EINVAL; /* No way to control the device without sysfs */
+#endif
+}
+
static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
struct kvm_assigned_pci_dev *assigned_dev)
{
int r = 0;
struct kvm_assigned_dev_kernel *match;
struct pci_dev *dev;
+ u8 header_type;
down_read(&kvm->slots_lock);
mutex_lock(&kvm->lock);
@@ -607,6 +670,18 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
r = -EINVAL;
goto out_free;
}
+
+ /* Don't allow bridges to be assigned */
+ pci_read_config_byte(dev, PCI_HEADER_TYPE, &header_type);
+ if ((header_type & PCI_HEADER_TYPE) != PCI_HEADER_TYPE_NORMAL) {
+ r = -EPERM;
+ goto out_put;
+ }
+
+ r = probe_sysfs_permissions(dev);
+ if (r)
+ goto out_put;
+
if (pci_enable_device(dev)) {
printk(KERN_INFO "%s: Could not enable PCI device\n", __func__);
r = -EBUSY;