From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Adalbert=20Laz=C4=83r?= Subject: [PATCH v9 73/84] KVM: introspection: add KVMI_EVENT_DESCRIPTOR Date: Wed, 22 Jul 2020 00:09:11 +0300 Message-ID: <20200721210922.7646-74-alazar@bitdefender.com> References: <20200721210922.7646-1-alazar@bitdefender.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200721210922.7646-1-alazar@bitdefender.com> Sender: kvm-owner@vger.kernel.org To: kvm@vger.kernel.org Cc: virtualization@lists.linux-foundation.org, Paolo Bonzini , =?UTF-8?q?Nicu=C8=99or=20C=C3=AE=C8=9Bu?= , =?UTF-8?q?Adalbert=20Laz=C4=83r?= List-Id: virtualization@lists.linuxfoundation.org From: Nicușor Cîțu This event is sent when IDTR, GDTR, LDTR or TR are accessed. These could be used to implement a tiny agent which runs in the context of an introspected guest and uses virtualized exceptions (#VE) and alternate EPT views (VMFUNC #0) to filter converted VMEXITS. The events of interested will be suppressed (after some appropriate guest-side handling) while the rest will be sent to the introspector via a VMCALL. Signed-off-by: Nicușor Cîțu Co-developed-by: Adalbert Lazăr Signed-off-by: Adalbert Lazăr --- Documentation/virt/kvm/kvmi.rst | 41 ++++++++++ arch/x86/include/asm/kvmi_host.h | 3 + arch/x86/include/uapi/asm/kvmi.h | 11 +++ arch/x86/kvm/kvmi.c | 75 +++++++++++++++++++ arch/x86/kvm/svm/svm.c | 33 ++++++++ arch/x86/kvm/vmx/vmx.c | 23 ++++++ include/uapi/linux/kvmi.h | 1 + .../testing/selftests/kvm/x86_64/kvmi_test.c | 75 +++++++++++++++++++ virt/kvm/introspection/kvmi.c | 1 + 9 files changed, 263 insertions(+) diff --git a/Documentation/virt/kvm/kvmi.rst b/Documentation/virt/kvm/kvmi.rst index 6de260c09f3b..0294c141eb0a 100644 --- a/Documentation/virt/kvm/kvmi.rst +++ b/Documentation/virt/kvm/kvmi.rst @@ -551,6 +551,7 @@ the following events:: KVMI_EVENT_BREAKPOINT KVMI_EVENT_CR + KVMI_EVENT_DESCRIPTOR KVMI_EVENT_HYPERCALL KVMI_EVENT_XSETBV @@ -574,6 +575,8 @@ the *KVMI_VM_CONTROL_EVENTS* command. * -KVM_EINVAL - the event ID is unknown (use *KVMI_VM_CHECK_EVENT* first) * -KVM_EPERM - the access is disallowed (use *KVMI_VM_CHECK_EVENT* first) * -KVM_EAGAIN - the selected vCPU can't be introspected yet +* -KVM_EOPNOTSUPP - the event can't be intercepted in the current setup + (e.g. KVMI_EVENT_DESCRIPTOR with AMD) * -KVM_EBUSY - the event can't be intercepted right now (e.g. KVMI_EVENT_BREAKPOINT if the #BP event is already intercepted by userspace) @@ -1211,3 +1214,41 @@ to be changed and the introspection has been enabled for this event ``kvmi_event``, the extended control register number, the old value and the new value are sent to the introspection tool. + +8. KVMI_EVENT_DESCRIPTOR +------------------------ + +:Architecture: x86 +:Versions: >= 1 +:Actions: CONTINUE, RETRY, CRASH +:Parameters: + +:: + + struct kvmi_event; + struct kvmi_event_descriptor { + __u8 descriptor; + __u8 write; + __u8 padding[6]; + }; + +:Returns: + +:: + + struct kvmi_vcpu_hdr; + struct kvmi_event_reply; + +This event is sent when a descriptor table register is accessed and the +introspection has been enabled for this event (see **KVMI_VCPU_CONTROL_EVENTS**). + +``kvmi_event`` and ``kvmi_event_descriptor`` are sent to the introspection tool. + +``descriptor`` can be one of:: + + KVMI_DESC_IDTR + KVMI_DESC_GDTR + KVMI_DESC_LDTR + KVMI_DESC_TR + +``write`` is 1 if the descriptor was written, 0 otherwise. diff --git a/arch/x86/include/asm/kvmi_host.h b/arch/x86/include/asm/kvmi_host.h index aed8a4b88a68..09ebed80a8cc 100644 --- a/arch/x86/include/asm/kvmi_host.h +++ b/arch/x86/include/asm/kvmi_host.h @@ -35,6 +35,7 @@ bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu); bool kvmi_monitor_cr3w_intercept(struct kvm_vcpu *vcpu, bool enable); void kvmi_xsetbv_event(struct kvm_vcpu *vcpu, u8 xcr, u64 old_value, u64 new_value); +bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, bool write); #else /* CONFIG_KVM_INTROSPECTION */ @@ -49,6 +50,8 @@ static inline bool kvmi_monitor_cr3w_intercept(struct kvm_vcpu *vcpu, bool enable) { return false; } static inline void kvmi_xsetbv_event(struct kvm_vcpu *vcpu, u8 xcr, u64 old_value, u64 new_value) { } +static inline bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, + bool write) { return true; } #endif /* CONFIG_KVM_INTROSPECTION */ diff --git a/arch/x86/include/uapi/asm/kvmi.h b/arch/x86/include/uapi/asm/kvmi.h index 33edbb5b32f4..b6ff39ba0ab3 100644 --- a/arch/x86/include/uapi/asm/kvmi.h +++ b/arch/x86/include/uapi/asm/kvmi.h @@ -116,4 +116,15 @@ struct kvmi_vcpu_get_mtrr_type_reply { __u8 padding[7]; }; +#define KVMI_DESC_IDTR 1 +#define KVMI_DESC_GDTR 2 +#define KVMI_DESC_LDTR 3 +#define KVMI_DESC_TR 4 + +struct kvmi_event_descriptor { + __u8 descriptor; + __u8 write; + __u8 padding[6]; +}; + #endif /* _UAPI_ASM_X86_KVMI_H */ diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c index 80ad67e875c4..3ae43a4c8764 100644 --- a/arch/x86/kvm/kvmi.c +++ b/arch/x86/kvm/kvmi.c @@ -361,6 +361,21 @@ static void kvmi_arch_disable_cr3w_intercept(struct kvm_vcpu *vcpu) vcpu->arch.kvmi->cr3w.kvm_intercepted = false; } +static int kvmi_control_desc_intercept(struct kvm_vcpu *vcpu, bool enable) +{ + if (!kvm_x86_ops.desc_ctrl_supported()) + return -KVM_EOPNOTSUPP; + + kvm_x86_ops.control_desc_intercept(vcpu, enable); + + return 0; +} + +static void kvmi_arch_disable_desc_intercept(struct kvm_vcpu *vcpu) +{ + kvmi_control_desc_intercept(vcpu, false); +} + int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu, unsigned int event_id, bool enable) { @@ -370,6 +385,9 @@ int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu, case KVMI_EVENT_BREAKPOINT: err = kvmi_control_bp_intercept(vcpu, enable); break; + case KVMI_EVENT_DESCRIPTOR: + err = kvmi_control_desc_intercept(vcpu, enable); + break; default: break; } @@ -401,6 +419,7 @@ static void kvmi_arch_restore_interception(struct kvm_vcpu *vcpu) { kvmi_arch_disable_bp_intercept(vcpu); kvmi_arch_disable_cr3w_intercept(vcpu); + kvmi_arch_disable_desc_intercept(vcpu); } bool kvmi_arch_clean_up_interception(struct kvm_vcpu *vcpu) @@ -791,3 +810,59 @@ int kvmi_arch_cmd_vcpu_get_mtrr_type(struct kvm_vcpu *vcpu, u64 gpa, u8 *type) return 0; } + +static u32 kvmi_msg_send_descriptor(struct kvm_vcpu *vcpu, u8 descriptor, + bool write) +{ + struct kvmi_event_descriptor e; + int err, action; + + memset(&e, 0, sizeof(e)); + e.descriptor = descriptor; + e.write = write ? 1 : 0; + + err = kvmi_send_event(vcpu, KVMI_EVENT_DESCRIPTOR, &e, sizeof(e), + NULL, 0, &action); + if (err) + return KVMI_EVENT_ACTION_CONTINUE; + + return action; +} + +static bool __kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, + bool write) +{ + bool ret = false; + u32 action; + + action = kvmi_msg_send_descriptor(vcpu, descriptor, write); + switch (action) { + case KVMI_EVENT_ACTION_CONTINUE: + ret = true; + break; + case KVMI_EVENT_ACTION_RETRY: + break; + default: + kvmi_handle_common_event_actions(vcpu->kvm, action); + } + + return ret; +} + +bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, bool write) +{ + struct kvm_introspection *kvmi; + bool ret = true; + + kvmi = kvmi_get(vcpu->kvm); + if (!kvmi) + return true; + + if (is_event_enabled(vcpu, KVMI_EVENT_DESCRIPTOR)) + ret = __kvmi_descriptor_event(vcpu, descriptor, write); + + kvmi_put(vcpu->kvm); + + return ret; +} +EXPORT_SYMBOL(kvmi_descriptor_event); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index bc886cedf45c..a0b91007e484 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2326,6 +2326,39 @@ static int descriptor_access_interception(struct vcpu_svm *svm) { struct kvm_vcpu *vcpu = &svm->vcpu; +#ifdef CONFIG_KVM_INTROSPECTION + struct vmcb_control_area *c = &svm->vmcb->control; + bool cont; + + switch (c->exit_code) { + case SVM_EXIT_IDTR_READ: + case SVM_EXIT_IDTR_WRITE: + cont = kvmi_descriptor_event(vcpu, KVMI_DESC_IDTR, + c->exit_code == SVM_EXIT_IDTR_WRITE); + break; + case SVM_EXIT_GDTR_READ: + case SVM_EXIT_GDTR_WRITE: + cont = kvmi_descriptor_event(vcpu, KVMI_DESC_GDTR, + c->exit_code == SVM_EXIT_GDTR_WRITE); + break; + case SVM_EXIT_LDTR_READ: + case SVM_EXIT_LDTR_WRITE: + cont = kvmi_descriptor_event(vcpu, KVMI_DESC_LDTR, + c->exit_code == SVM_EXIT_LDTR_WRITE); + break; + case SVM_EXIT_TR_READ: + case SVM_EXIT_TR_WRITE: + cont = kvmi_descriptor_event(vcpu, KVMI_DESC_TR, + c->exit_code == SVM_EXIT_TR_WRITE); + break; + default: + cont = true; + break; + } + if (!cont) + return 1; +#endif /* CONFIG_KVM_INTROSPECTION */ + return kvm_emulate_instruction(vcpu, 0); } diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 69aa1157a0f0..74bdcd4966ca 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5019,7 +5019,30 @@ static int handle_set_cr4(struct kvm_vcpu *vcpu, unsigned long val) static int handle_desc(struct kvm_vcpu *vcpu) { +#ifdef CONFIG_KVM_INTROSPECTION + struct vcpu_vmx *vmx = to_vmx(vcpu); + u32 exit_reason = vmx->exit_reason; + u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO); + u8 store = (vmx_instruction_info >> 29) & 0x1; + u8 descriptor = 0; + + if (exit_reason == EXIT_REASON_GDTR_IDTR) { + if ((vmx_instruction_info >> 28) & 0x1) + descriptor = KVMI_DESC_IDTR; + else + descriptor = KVMI_DESC_GDTR; + } else { + if ((vmx_instruction_info >> 28) & 0x1) + descriptor = KVMI_DESC_TR; + else + descriptor = KVMI_DESC_LDTR; + } + + if (!kvmi_descriptor_event(vcpu, descriptor, store)) + return 1; +#else WARN_ON(!(vcpu->arch.cr4 & X86_CR4_UMIP)); +#endif /* CONFIG_KVM_INTROSPECTION */ return kvm_emulate_instruction(vcpu, 0); } diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h index 207bcaeec05a..f2e802d2b712 100644 --- a/include/uapi/linux/kvmi.h +++ b/include/uapi/linux/kvmi.h @@ -55,6 +55,7 @@ enum { KVMI_EVENT_CR = 4, KVMI_EVENT_TRAP = 5, KVMI_EVENT_XSETBV = 6, + KVMI_EVENT_DESCRIPTOR = 7, KVMI_NUM_EVENTS }; diff --git a/tools/testing/selftests/kvm/x86_64/kvmi_test.c b/tools/testing/selftests/kvm/x86_64/kvmi_test.c index 7174e464d759..0087b91574f0 100644 --- a/tools/testing/selftests/kvm/x86_64/kvmi_test.c +++ b/tools/testing/selftests/kvm/x86_64/kvmi_test.c @@ -55,6 +55,7 @@ enum { GUEST_TEST_NOOP = 0, GUEST_TEST_BP, GUEST_TEST_CR, + GUEST_TEST_DESCRIPTOR, GUEST_TEST_HYPERCALL, GUEST_TEST_XSETBV, }; @@ -84,6 +85,14 @@ static void guest_cr_test(void) set_cr4(get_cr4() | X86_CR4_OSXSAVE); } +static void guest_descriptor_test(void) +{ + void *ptr; + + asm volatile("sgdt %0" :: "m"(ptr)); + asm volatile("lgdt %0" :: "m"(ptr)); +} + static void guest_hypercall_test(void) { asm volatile("mov $34, %rax"); @@ -143,6 +152,9 @@ static void guest_code(void) case GUEST_TEST_CR: guest_cr_test(); break; + case GUEST_TEST_DESCRIPTOR: + guest_descriptor_test(); + break; case GUEST_TEST_HYPERCALL: guest_hypercall_test(); break; @@ -1617,6 +1629,68 @@ static void test_cmd_vcpu_get_mtrr_type(struct kvm_vm *vm) pr_info("mtrr_type: gpa 0x%lx type 0x%x\n", test_gpa, rpl.type); } +static void test_desc_read_access(__u16 event_id) +{ + struct kvmi_msg_hdr hdr; + struct { + struct kvmi_event common; + struct kvmi_event_descriptor desc; + } ev; + struct vcpu_reply rpl = {}; + + receive_event(&hdr, &ev.common, sizeof(ev), event_id); + + pr_info("Descriptor event (read), descriptor %u, write %u\n", + ev.desc.descriptor, ev.desc.write); + + TEST_ASSERT(ev.desc.write == 0, + "Received a write descriptor access\n"); + + reply_to_event(&hdr, &ev.common, KVMI_EVENT_ACTION_CONTINUE, + &rpl, sizeof(rpl)); +} + +static void test_desc_write_access(__u16 event_id) +{ + struct kvmi_msg_hdr hdr; + struct { + struct kvmi_event common; + struct kvmi_event_descriptor desc; + } ev; + struct vcpu_reply rpl = {}; + + receive_event(&hdr, &ev.common, sizeof(ev), event_id); + + pr_info("Descriptor event (write), descriptor %u, write %u\n", + ev.desc.descriptor, ev.desc.write); + + TEST_ASSERT(ev.desc.write == 1, + "Received a read descriptor access\n"); + + reply_to_event(&hdr, &ev.common, KVMI_EVENT_ACTION_CONTINUE, + &rpl, sizeof(rpl)); +} + +static void test_event_descriptor(struct kvm_vm *vm) +{ + struct vcpu_worker_data data = { + .vm = vm, + .vcpu_id = VCPU_ID, + .test_id = GUEST_TEST_DESCRIPTOR, + }; + __u16 event_id = KVMI_EVENT_DESCRIPTOR; + pthread_t vcpu_thread; + + enable_vcpu_event(vm, event_id); + vcpu_thread = start_vcpu_worker(&data); + + test_desc_read_access(event_id); + test_desc_write_access(event_id); + + stop_vcpu_worker(vcpu_thread, &data); + disable_vcpu_event(vm, event_id); +} + static void test_introspection(struct kvm_vm *vm) { srandom(time(0)); @@ -1647,6 +1721,7 @@ static void test_introspection(struct kvm_vm *vm) test_cmd_vcpu_get_xcr(vm); test_cmd_vcpu_xsave(vm); test_cmd_vcpu_get_mtrr_type(vm); + test_event_descriptor(vm); unhook_introspection(vm); } diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c index 761d3fccddce..a1bc9570ac1c 100644 --- a/virt/kvm/introspection/kvmi.c +++ b/virt/kvm/introspection/kvmi.c @@ -99,6 +99,7 @@ static void setup_known_events(void) bitmap_zero(Kvmi_known_vcpu_events, KVMI_NUM_EVENTS); set_bit(KVMI_EVENT_BREAKPOINT, Kvmi_known_vcpu_events); set_bit(KVMI_EVENT_CR, Kvmi_known_vcpu_events); + set_bit(KVMI_EVENT_DESCRIPTOR, Kvmi_known_vcpu_events); set_bit(KVMI_EVENT_HYPERCALL, Kvmi_known_vcpu_events); set_bit(KVMI_EVENT_PAUSE_VCPU, Kvmi_known_vcpu_events); set_bit(KVMI_EVENT_TRAP, Kvmi_known_vcpu_events);