| Message ID | 20211103140527.752797-8-eesposit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: nSVM: avoid TOC/TOU race when checking vmcb12 | expand |
On Wed, 2021-11-03 at 10:05 -0400, Emanuele Giuseppe Esposito wrote: > This requires changing all vmcb_is_intercept(&svm->nested.ctl, ...) > calls with vmcb12_is_intercept(). > > In addition, in svm_get_nested_state() user space expects a > vmcb_control_area struct, so we need to copy back all fields > in a temporary structure to provide to the user space. > > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> > --- > arch/x86/kvm/svm/nested.c | 48 +++++++++++++++++++++++++-------------- > arch/x86/kvm/svm/svm.c | 4 ++-- > arch/x86/kvm/svm/svm.h | 8 +++---- > 3 files changed, 37 insertions(+), 23 deletions(-) > > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c > index cd15d5373c05..6281d1877211 100644 > --- a/arch/x86/kvm/svm/nested.c > +++ b/arch/x86/kvm/svm/nested.c > @@ -58,8 +58,9 @@ static void svm_inject_page_fault_nested(struct kvm_vcpu *vcpu, struct x86_excep > struct vcpu_svm *svm = to_svm(vcpu); > WARN_ON(!is_guest_mode(vcpu)); > > - if (vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_EXCEPTION_OFFSET + PF_VECTOR) && > - !svm->nested.nested_run_pending) { > + if (vmcb12_is_intercept(&svm->nested.ctl, > + INTERCEPT_EXCEPTION_OFFSET + PF_VECTOR) && > + !svm->nested.nested_run_pending) { > svm->vmcb->control.exit_code = SVM_EXIT_EXCP_BASE + PF_VECTOR; > svm->vmcb->control.exit_code_hi = 0; > svm->vmcb->control.exit_info_1 = fault->error_code; > @@ -121,7 +122,8 @@ static void nested_svm_uninit_mmu_context(struct kvm_vcpu *vcpu) > > void recalc_intercepts(struct vcpu_svm *svm) > { > - struct vmcb_control_area *c, *h, *g; > + struct vmcb_control_area *c, *h; > + struct vmcb_ctrl_area_cached *g; > unsigned int i; > > vmcb_mark_dirty(svm->vmcb, VMCB_INTERCEPTS); > @@ -172,7 +174,7 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm) > */ > int i; > > - if (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) > + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) > return true; > > for (i = 0; i < MSRPM_OFFSETS; i++) { > @@ -220,9 +222,9 @@ static bool nested_svm_check_tlb_ctl(struct kvm_vcpu *vcpu, u8 tlb_ctl) > } > > static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu, > - struct vmcb_control_area *control) > + struct vmcb_ctrl_area_cached *control) > { > - if (CC(!vmcb_is_intercept(control, INTERCEPT_VMRUN))) > + if (CC(!vmcb12_is_intercept(control, INTERCEPT_VMRUN))) > return false; > > if (CC(control->asid == 0)) > @@ -288,7 +290,7 @@ static bool nested_vmcb_check_save(struct kvm_vcpu *vcpu) > } > > static > -void _nested_copy_vmcb_control_to_cache(struct vmcb_control_area *to, > +void _nested_copy_vmcb_control_to_cache(struct vmcb_ctrl_area_cached *to, > struct vmcb_control_area *from) > { > unsigned int i; > @@ -998,7 +1000,7 @@ static int nested_svm_exit_handled_msr(struct vcpu_svm *svm) > u32 offset, msr, value; > int write, mask; > > - if (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) > + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) > return NESTED_EXIT_HOST; > > msr = svm->vcpu.arch.regs[VCPU_REGS_RCX]; > @@ -1025,7 +1027,7 @@ static int nested_svm_intercept_ioio(struct vcpu_svm *svm) > u8 start_bit; > u64 gpa; > > - if (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_IOIO_PROT))) > + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_IOIO_PROT))) > return NESTED_EXIT_HOST; > > port = svm->vmcb->control.exit_info_1 >> 16; > @@ -1056,12 +1058,12 @@ static int nested_svm_intercept(struct vcpu_svm *svm) > vmexit = nested_svm_intercept_ioio(svm); > break; > case SVM_EXIT_READ_CR0 ... SVM_EXIT_WRITE_CR8: { > - if (vmcb_is_intercept(&svm->nested.ctl, exit_code)) > + if (vmcb12_is_intercept(&svm->nested.ctl, exit_code)) > vmexit = NESTED_EXIT_DONE; > break; > } > case SVM_EXIT_READ_DR0 ... SVM_EXIT_WRITE_DR7: { > - if (vmcb_is_intercept(&svm->nested.ctl, exit_code)) > + if (vmcb12_is_intercept(&svm->nested.ctl, exit_code)) > vmexit = NESTED_EXIT_DONE; > break; > } > @@ -1079,7 +1081,7 @@ static int nested_svm_intercept(struct vcpu_svm *svm) > break; > } > default: { > - if (vmcb_is_intercept(&svm->nested.ctl, exit_code)) > + if (vmcb12_is_intercept(&svm->nested.ctl, exit_code)) > vmexit = NESTED_EXIT_DONE; > } > } > @@ -1157,7 +1159,7 @@ static void nested_svm_inject_exception_vmexit(struct vcpu_svm *svm) > > static inline bool nested_exit_on_init(struct vcpu_svm *svm) > { > - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_INIT); > + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_INIT); > } > > static int svm_check_nested_events(struct kvm_vcpu *vcpu) > @@ -1300,6 +1302,8 @@ static int svm_get_nested_state(struct kvm_vcpu *vcpu, > u32 user_data_size) > { > struct vcpu_svm *svm; > + struct vmcb_control_area *ctl; > + unsigned long r; > struct kvm_nested_state kvm_state = { > .flags = 0, > .format = KVM_STATE_NESTED_FORMAT_SVM, > @@ -1341,9 +1345,18 @@ static int svm_get_nested_state(struct kvm_vcpu *vcpu, > */ > if (clear_user(user_vmcb, KVM_STATE_NESTED_SVM_VMCB_SIZE)) > return -EFAULT; > - if (copy_to_user(&user_vmcb->control, &svm->nested.ctl, > - sizeof(user_vmcb->control))) > + > + ctl = kzalloc(sizeof(*ctl), GFP_KERNEL); > + if (!ctl) > + return -ENOMEM; > + > + nested_copy_vmcb_cache_to_control(ctl, &svm->nested.ctl); > + r = copy_to_user(&user_vmcb->control, ctl, > + sizeof(user_vmcb->control)); > + kfree(ctl); > + if (r) > return -EFAULT; > + > if (copy_to_user(&user_vmcb->save, &svm->vmcb01.ptr->save, > sizeof(user_vmcb->save))) > return -EFAULT; > @@ -1361,6 +1374,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, > struct vmcb_control_area *ctl; > struct vmcb_save_area *save; > struct vmcb_save_area_cached save_cached; > + struct vmcb_ctrl_area_cached ctl_cached; > unsigned long cr0; > int ret; > > @@ -1413,7 +1427,8 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, > goto out_free; > > ret = -EINVAL; > - if (!nested_vmcb_check_controls(vcpu, ctl)) > + _nested_copy_vmcb_control_to_cache(&ctl_cached, ctl); > + if (!nested_vmcb_check_controls(vcpu, &ctl_cached)) > goto out_free; > > /* > @@ -1470,7 +1485,6 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, > svm->nested.vmcb12_gpa = kvm_state->hdr.svm.vmcb_pa; > > svm_copy_vmrun_state(&svm->vmcb01.ptr->save, save); > - nested_copy_vmcb_control_to_cache(svm, ctl); You should keep this line of code, to actualy load the control area, The whole copying to 'cache' is a bit ugly here, but let it be, as there is no other way around and the uglyness is only limited to those two functions (svm_get_nested_state/svm_set_nested_state). I am currently testing your patches with the above change reverted. Seems to pass at least my basic test so far. Thanks, Best regards, Maxim Levitsky > > svm_switch_vmcb(svm, &svm->nested.vmcb02); > nested_vmcb02_prepare_control(svm); > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 74d6db9017ea..134205678462 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -2506,7 +2506,7 @@ static bool check_selective_cr0_intercepted(struct kvm_vcpu *vcpu, > bool ret = false; > > if (!is_guest_mode(vcpu) || > - (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_SELECTIVE_CR0)))) > + (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_SELECTIVE_CR0)))) > return false; > > cr0 &= ~SVM_CR0_SELECTIVE_MASK; > @@ -4218,7 +4218,7 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, > info->intercept == x86_intercept_clts) > break; > > - if (!(vmcb_is_intercept(&svm->nested.ctl, > + if (!(vmcb12_is_intercept(&svm->nested.ctl, > INTERCEPT_SELECTIVE_CR0))) > break; > > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index e29423d4337c..a896a52417ee 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -156,7 +156,7 @@ struct svm_nested_state { > bool nested_run_pending; > > /* cache for control fields of the guest */ > - struct vmcb_control_area ctl; > + struct vmcb_ctrl_area_cached ctl; > struct vmcb_save_area_cached save; > > bool initialized; > @@ -494,17 +494,17 @@ static inline bool nested_svm_virtualize_tpr(struct kvm_vcpu *vcpu) > > static inline bool nested_exit_on_smi(struct vcpu_svm *svm) > { > - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_SMI); > + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_SMI); > } > > static inline bool nested_exit_on_intr(struct vcpu_svm *svm) > { > - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_INTR); > + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_INTR); > } > > static inline bool nested_exit_on_nmi(struct vcpu_svm *svm) > { > - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_NMI); > + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_NMI); > } > > int enter_svm_guest_mode(struct kvm_vcpu *vcpu,
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index cd15d5373c05..6281d1877211 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -58,8 +58,9 @@ static void svm_inject_page_fault_nested(struct kvm_vcpu *vcpu, struct x86_excep struct vcpu_svm *svm = to_svm(vcpu); WARN_ON(!is_guest_mode(vcpu)); - if (vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_EXCEPTION_OFFSET + PF_VECTOR) && - !svm->nested.nested_run_pending) { + if (vmcb12_is_intercept(&svm->nested.ctl, + INTERCEPT_EXCEPTION_OFFSET + PF_VECTOR) && + !svm->nested.nested_run_pending) { svm->vmcb->control.exit_code = SVM_EXIT_EXCP_BASE + PF_VECTOR; svm->vmcb->control.exit_code_hi = 0; svm->vmcb->control.exit_info_1 = fault->error_code; @@ -121,7 +122,8 @@ static void nested_svm_uninit_mmu_context(struct kvm_vcpu *vcpu) void recalc_intercepts(struct vcpu_svm *svm) { - struct vmcb_control_area *c, *h, *g; + struct vmcb_control_area *c, *h; + struct vmcb_ctrl_area_cached *g; unsigned int i; vmcb_mark_dirty(svm->vmcb, VMCB_INTERCEPTS); @@ -172,7 +174,7 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm) */ int i; - if (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) return true; for (i = 0; i < MSRPM_OFFSETS; i++) { @@ -220,9 +222,9 @@ static bool nested_svm_check_tlb_ctl(struct kvm_vcpu *vcpu, u8 tlb_ctl) } static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu, - struct vmcb_control_area *control) + struct vmcb_ctrl_area_cached *control) { - if (CC(!vmcb_is_intercept(control, INTERCEPT_VMRUN))) + if (CC(!vmcb12_is_intercept(control, INTERCEPT_VMRUN))) return false; if (CC(control->asid == 0)) @@ -288,7 +290,7 @@ static bool nested_vmcb_check_save(struct kvm_vcpu *vcpu) } static -void _nested_copy_vmcb_control_to_cache(struct vmcb_control_area *to, +void _nested_copy_vmcb_control_to_cache(struct vmcb_ctrl_area_cached *to, struct vmcb_control_area *from) { unsigned int i; @@ -998,7 +1000,7 @@ static int nested_svm_exit_handled_msr(struct vcpu_svm *svm) u32 offset, msr, value; int write, mask; - if (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) return NESTED_EXIT_HOST; msr = svm->vcpu.arch.regs[VCPU_REGS_RCX]; @@ -1025,7 +1027,7 @@ static int nested_svm_intercept_ioio(struct vcpu_svm *svm) u8 start_bit; u64 gpa; - if (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_IOIO_PROT))) + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_IOIO_PROT))) return NESTED_EXIT_HOST; port = svm->vmcb->control.exit_info_1 >> 16; @@ -1056,12 +1058,12 @@ static int nested_svm_intercept(struct vcpu_svm *svm) vmexit = nested_svm_intercept_ioio(svm); break; case SVM_EXIT_READ_CR0 ... SVM_EXIT_WRITE_CR8: { - if (vmcb_is_intercept(&svm->nested.ctl, exit_code)) + if (vmcb12_is_intercept(&svm->nested.ctl, exit_code)) vmexit = NESTED_EXIT_DONE; break; } case SVM_EXIT_READ_DR0 ... SVM_EXIT_WRITE_DR7: { - if (vmcb_is_intercept(&svm->nested.ctl, exit_code)) + if (vmcb12_is_intercept(&svm->nested.ctl, exit_code)) vmexit = NESTED_EXIT_DONE; break; } @@ -1079,7 +1081,7 @@ static int nested_svm_intercept(struct vcpu_svm *svm) break; } default: { - if (vmcb_is_intercept(&svm->nested.ctl, exit_code)) + if (vmcb12_is_intercept(&svm->nested.ctl, exit_code)) vmexit = NESTED_EXIT_DONE; } } @@ -1157,7 +1159,7 @@ static void nested_svm_inject_exception_vmexit(struct vcpu_svm *svm) static inline bool nested_exit_on_init(struct vcpu_svm *svm) { - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_INIT); + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_INIT); } static int svm_check_nested_events(struct kvm_vcpu *vcpu) @@ -1300,6 +1302,8 @@ static int svm_get_nested_state(struct kvm_vcpu *vcpu, u32 user_data_size) { struct vcpu_svm *svm; + struct vmcb_control_area *ctl; + unsigned long r; struct kvm_nested_state kvm_state = { .flags = 0, .format = KVM_STATE_NESTED_FORMAT_SVM, @@ -1341,9 +1345,18 @@ static int svm_get_nested_state(struct kvm_vcpu *vcpu, */ if (clear_user(user_vmcb, KVM_STATE_NESTED_SVM_VMCB_SIZE)) return -EFAULT; - if (copy_to_user(&user_vmcb->control, &svm->nested.ctl, - sizeof(user_vmcb->control))) + + ctl = kzalloc(sizeof(*ctl), GFP_KERNEL); + if (!ctl) + return -ENOMEM; + + nested_copy_vmcb_cache_to_control(ctl, &svm->nested.ctl); + r = copy_to_user(&user_vmcb->control, ctl, + sizeof(user_vmcb->control)); + kfree(ctl); + if (r) return -EFAULT; + if (copy_to_user(&user_vmcb->save, &svm->vmcb01.ptr->save, sizeof(user_vmcb->save))) return -EFAULT; @@ -1361,6 +1374,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, struct vmcb_control_area *ctl; struct vmcb_save_area *save; struct vmcb_save_area_cached save_cached; + struct vmcb_ctrl_area_cached ctl_cached; unsigned long cr0; int ret; @@ -1413,7 +1427,8 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, goto out_free; ret = -EINVAL; - if (!nested_vmcb_check_controls(vcpu, ctl)) + _nested_copy_vmcb_control_to_cache(&ctl_cached, ctl); + if (!nested_vmcb_check_controls(vcpu, &ctl_cached)) goto out_free; /* @@ -1470,7 +1485,6 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, svm->nested.vmcb12_gpa = kvm_state->hdr.svm.vmcb_pa; svm_copy_vmrun_state(&svm->vmcb01.ptr->save, save); - nested_copy_vmcb_control_to_cache(svm, ctl); svm_switch_vmcb(svm, &svm->nested.vmcb02); nested_vmcb02_prepare_control(svm); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 74d6db9017ea..134205678462 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2506,7 +2506,7 @@ static bool check_selective_cr0_intercepted(struct kvm_vcpu *vcpu, bool ret = false; if (!is_guest_mode(vcpu) || - (!(vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_SELECTIVE_CR0)))) + (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_SELECTIVE_CR0)))) return false; cr0 &= ~SVM_CR0_SELECTIVE_MASK; @@ -4218,7 +4218,7 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, info->intercept == x86_intercept_clts) break; - if (!(vmcb_is_intercept(&svm->nested.ctl, + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_SELECTIVE_CR0))) break; diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index e29423d4337c..a896a52417ee 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -156,7 +156,7 @@ struct svm_nested_state { bool nested_run_pending; /* cache for control fields of the guest */ - struct vmcb_control_area ctl; + struct vmcb_ctrl_area_cached ctl; struct vmcb_save_area_cached save; bool initialized; @@ -494,17 +494,17 @@ static inline bool nested_svm_virtualize_tpr(struct kvm_vcpu *vcpu) static inline bool nested_exit_on_smi(struct vcpu_svm *svm) { - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_SMI); + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_SMI); } static inline bool nested_exit_on_intr(struct vcpu_svm *svm) { - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_INTR); + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_INTR); } static inline bool nested_exit_on_nmi(struct vcpu_svm *svm) { - return vmcb_is_intercept(&svm->nested.ctl, INTERCEPT_NMI); + return vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_NMI); } int enter_svm_guest_mode(struct kvm_vcpu *vcpu,
This requires changing all vmcb_is_intercept(&svm->nested.ctl, ...) calls with vmcb12_is_intercept(). In addition, in svm_get_nested_state() user space expects a vmcb_control_area struct, so we need to copy back all fields in a temporary structure to provide to the user space. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> --- arch/x86/kvm/svm/nested.c | 48 +++++++++++++++++++++++++-------------- arch/x86/kvm/svm/svm.c | 4 ++-- arch/x86/kvm/svm/svm.h | 8 +++---- 3 files changed, 37 insertions(+), 23 deletions(-)