path: root/virt/kvm/kvm_main.c
diff options
authorMarc Zyngier <maz@kernel.org>2019-11-14 13:17:39 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2019-11-15 10:14:04 +0100
commit9cb09e7c1c9af2968d5186ef9085f05641ab65d9 (patch)
tree23972e24845a7ea316c2c5d53e6e6fafb1212469 /virt/kvm/kvm_main.c
parentKVM: x86/mmu: Take slots_lock when using kvm_mmu_zap_all_fast() (diff)
KVM: Add a comment describing the /dev/kvm no_compat handling
Add a comment explaining the rational behind having both no_compat open and ioctl callbacks to fend off compat tasks. Signed-off-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm/kvm_main.c')
1 files changed, 7 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6a65ed915c7a..13efc291b1c7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -122,6 +122,13 @@ static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
unsigned long arg);
#define KVM_COMPAT(c) .compat_ioctl = (c)
+ * For architectures that don't implement a compat infrastructure,
+ * adopt a double line of defense:
+ * - Prevent a compat task from opening /dev/kvm
+ * - If the open has been done by a 64bit task, and the KVM fd
+ * passed to a compat task, let the ioctls fail.
+ */
static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
unsigned long arg) { return -EINVAL; }