[PATCH 1/2] KVM: Enforce error in ioctl for compat tasks when !KVM_COMPAT
From: mark.rutland@arm.com (Mark Rutland)
Date: 2018-06-19 10:01:35
Also in:
kvm, kvmarm
On Tue, Jun 19, 2018 at 10:42:50AM +0100, Marc Zyngier wrote:
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@arm.com> Signed-off-by: Marc Zyngier <redacted>
I virt/kvm/Kconfig we have:
config KVM_COMPAT
def_bool y
depends on KVM && COMPAT && !S390
... and in arch/s390 we have COMPAT support, so does this potentially break
anything there?
Thanks,
Mark.
quoted hunk ↗ jump to hunk
--- 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