The current behaviour of the compat ioctls is a bit odd.
We provide a compat_ioctl method when KVM_COMPAT is set, and NULL
otherwise. But NULL means that the normal, non-compat ioctl should
be used directly for compat tasks, and there is no way to actually
prevent a compat task from issueing KVM ioctls.
This patch changes this behaviour, by always registering a compat_ioctl
method, even if KVM_COMPAT is not selected. In that case, the callback
will always return -EINVAL.
Reported-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
virt/kvm/kvm_main.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ada21f47f22b..8b47507faab5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -116,6 +116,11 @@ static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
#ifdef CONFIG_KVM_COMPAT
static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
unsigned long arg);
+#define KVM_COMPAT(c) .compat_ioctl = (c)
+#else
+static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
+ unsigned long arg) { return -EINVAL; }
+#define KVM_COMPAT(c) .compat_ioctl = kvm_no_compat_ioctl
#endif
static int hardware_enable_all(void);
static void hardware_disable_all(void);
@@ -2396,11 +2401,9 @@ static int kvm_vcpu_release(struct inode *inode, struct file *filp)
static struct file_operations kvm_vcpu_fops = {
.release = kvm_vcpu_release,
.unlocked_ioctl = kvm_vcpu_ioctl,
-#ifdef CONFIG_KVM_COMPAT
- .compat_ioctl = kvm_vcpu_compat_ioctl,
-#endif
.mmap = kvm_vcpu_mmap,
.llseek = noop_llseek,
+ KVM_COMPAT(kvm_vcpu_compat_ioctl),
};
/*
@@ -2824,10 +2827,8 @@ static int kvm_device_release(struct inode *inode, struct file *filp)
static const struct file_operations kvm_device_fops = {
.unlocked_ioctl = kvm_device_ioctl,
-#ifdef CONFIG_KVM_COMPAT
- .compat_ioctl = kvm_device_ioctl,
-#endif
.release = kvm_device_release,
+ KVM_COMPAT(kvm_device_ioctl),
};
struct kvm_device *kvm_device_from_filp(struct file *filp)
@@ -3165,10 +3166,8 @@ static long kvm_vm_compat_ioctl(struct file *filp,
static struct file_operations kvm_vm_fops = {
.release = kvm_vm_release,
.unlocked_ioctl = kvm_vm_ioctl,
-#ifdef CONFIG_KVM_COMPAT
- .compat_ioctl = kvm_vm_compat_ioctl,
-#endif
.llseek = noop_llseek,
+ KVM_COMPAT(kvm_vm_compat_ioctl),
};
static int kvm_dev_ioctl_create_vm(unsigned long type)
@@ -3259,8 +3258,8 @@ static long kvm_dev_ioctl(struct file *filp,
static struct file_operations kvm_chardev_ops = {
.unlocked_ioctl = kvm_dev_ioctl,
- .compat_ioctl = kvm_dev_ioctl,
.llseek = noop_llseek,
+ KVM_COMPAT(kvm_dev_ioctl),
};
static struct miscdevice kvm_dev = {
--
2.17.1
