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KVM: Forbid /dev/kvm being opened by a compat task when CONFIG_KVM_COMPAT=n

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On a system without KVM_COMPAT, we prevent IOCTLs from being issued
by a compat task. Although this prevents most silly things from
happening, it can still confuse a 32bit userspace that is able
to open the kvm device (the qemu test suite seems to be pretty
mad with this behaviour).

Take a more radical approach and return a -ENODEV to the compat
task.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Marc Zyngier 2019-11-13 16:05:23 +00:00 committed by Paolo Bonzini
parent 6cbee2b9ec
commit b9876e6de1
1 changed files with 7 additions and 1 deletions
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8
virt/kvm/kvm_main.c
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@ -124,7 +124,13 @@ static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
#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
static int kvm_no_compat_open(struct inode *inode, struct file *file)
{
return is_compat_task() ? -ENODEV : 0;
}
#define KVM_COMPAT(c) .compat_ioctl = kvm_no_compat_ioctl, \
.open = kvm_no_compat_open
#endif
static int hardware_enable_all(void);
static void hardware_disable_all(void);