diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 4 | ||||
| -rw-r--r-- | virt/kvm/assigned-dev.c | 75 |
2 files changed, 79 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index ee2c96b3ba5..4df9af4f613 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1154,6 +1154,10 @@ following flags are specified: The KVM_DEV_ASSIGN_ENABLE_IOMMU flag is a mandatory option to ensure isolation of the device. Usages not specifying this flag are deprecated. +Only PCI header type 0 devices with PCI BAR resources are supported by +device assignment. The user requesting this ioctl must have read/write +access to the PCI sysfs resource files associated with the device. + 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 a251a28f79c..758e3b36d4c 100644 --- a/virt/kvm/assigned-dev.c +++ b/virt/kvm/assigned-dev.c @@ -17,6 +17,8 @@ #include <linux/pci.h> #include <linux/interrupt.h> #include <linux/slab.h> +#include <linux/namei.h> +#include <linux/fs.h> #include "irq.h" static struct kvm_assigned_dev_kernel *kvm_find_assigned_dev(struct list_head *head, @@ -480,12 +482,73 @@ 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, idx; struct kvm_assigned_dev_kernel *match; struct pci_dev *dev; + u8 header_type; if (!(assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU)) return -EINVAL; @@ -516,6 +579,18 @@ 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; |