From: Mihai Donțu <mdo...@bitdefender.com>
This event is sent when a breakpoint was reached.
The introspection tool can place breakpoints and use them as notification
for when the OS or an application has reached a certain state or is
trying to perform a certain operation (eg. create a process).
Signed-off-by: Mihai Donțu <mdo...@bitdefender.com>
Co-developed-by: Nicușor Cîțu <nc...@bitdefender.com>
Signed-off-by: Nicușor Cîțu <nc...@bitdefender.com>
Co-developed-by: Adalbert Lazăr <ala...@bitdefender.com>
Signed-off-by: Adalbert Lazăr <ala...@bitdefender.com>
---
Documentation/virt/kvm/kvmi.rst | 40 ++++++++++++++++
arch/x86/include/uapi/asm/kvmi.h | 6 +++
arch/x86/kvm/kvmi.c | 48 +++++++++++++++++++
arch/x86/kvm/svm/svm.c | 34 +++++++++++++
arch/x86/kvm/vmx/vmx.c | 17 +++++--
include/linux/kvmi_host.h | 4 ++
include/uapi/linux/kvmi.h | 1 +
.../testing/selftests/kvm/x86_64/kvmi_test.c | 46 ++++++++++++++++++
virt/kvm/introspection/kvmi.c | 23 ++++++++-
virt/kvm/introspection/kvmi_int.h | 4 ++
virt/kvm/introspection/kvmi_msg.c | 17 +++++++
11 files changed, 235 insertions(+), 5 deletions(-)
diff --git a/Documentation/virt/kvm/kvmi.rst b/Documentation/virt/kvm/kvmi.rst
index d062f2ccf365..110a6e7a7d2a 100644
--- a/Documentation/virt/kvm/kvmi.rst
+++ b/Documentation/virt/kvm/kvmi.rst
@@ -549,6 +549,7 @@ command) before returning to guest.
Enables/disables vCPU introspection events. This command can be used with
the following events::
+ KVMI_EVENT_BREAKPOINT
KVMI_EVENT_HYPERCALL
When an event is enabled, the introspection tool is notified and
@@ -570,6 +571,9 @@ 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_EBUSY - the event can't be intercepted right now
+ (e.g. KVMI_EVENT_BREAKPOINT if the #BP event is already
intercepted
+ by userspace)
11. KVMI_VCPU_GET_REGISTERS
---------------------------
@@ -820,3 +824,39 @@ It is used by the code residing inside the introspected
guest to call the
introspection tool and to report certain details about its operation. For
example, a classic antimalware remediation tool can report what it has
found during a scan.
+
+4. KVMI_EVENT_BREAKPOINT
+------------------------
+
+:Architectures: x86
+:Versions: >= 1
+:Actions: CONTINUE, CRASH, RETRY
+:Parameters:
+
+::
+
+ struct kvmi_event;
+ struct kvmi_event_breakpoint {
+ __u64 gpa;
+ __u8 insn_len;
+ __u8 padding[7];
+ };
+
+:Returns:
+
+::
+
+ struct kvmi_vcpu_hdr;
+ struct kvmi_event_reply;
+
+This event is sent when a breakpoint was reached and the introspection has
+been enabled for this event (see *KVMI_VCPU_CONTROL_EVENTS*).
+
+Some of these breakpoints could have been injected by the introspection tool,
+placed in the slack space of various functions and used as notification
+for when the OS or an application has reached a certain state or is
+trying to perform a certain operation (like creating a process).
+
+``kvmi_event`` and the guest physical address are sent to the introspection
tool.
+
+The *RETRY* action is used by the introspection tool for its own breakpoints.
diff --git a/arch/x86/include/uapi/asm/kvmi.h b/arch/x86/include/uapi/asm/kvmi.h
index 9882e68cab75..1605777256a3 100644
--- a/arch/x86/include/uapi/asm/kvmi.h
+++ b/arch/x86/include/uapi/asm/kvmi.h
@@ -59,4 +59,10 @@ struct kvmi_vcpu_get_cpuid_reply {
__u32 edx;
};
+struct kvmi_event_breakpoint {
+ __u64 gpa;
+ __u8 insn_len;
+ __u8 padding[7];
+};
+
#endif /* _UAPI_ASM_X86_KVMI_H */
diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c
index 45f1a45d5c0f..f13272350bc9 100644
--- a/arch/x86/kvm/kvmi.c
+++ b/arch/x86/kvm/kvmi.c
@@ -242,3 +242,51 @@ void kvmi_arch_hypercall_event(struct kvm_vcpu *vcpu)
kvmi_handle_common_event_actions(vcpu->kvm, action);
}
}
+
+static int kvmi_control_bp_intercept(struct kvm_vcpu *vcpu, bool enable)
+{
+ struct kvm_guest_debug dbg = {};
+ int err = 0;
+
+ if (enable)
+ dbg.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
+ err = kvm_arch_vcpu_set_guest_debug(vcpu, &dbg);
+
+ return err;
+}
+
+int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu,
+ unsigned int event_id, bool enable)
+{
+ int err = 0;
+
+ switch (event_id) {
+ case KVMI_EVENT_BREAKPOINT:
+ err = kvmi_control_bp_intercept(vcpu, enable);
+ break;
+ default:
+ break;
+ }
+
+ return err;
+}
+
+void kvmi_arch_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len)
+{
+ u32 action;
+ u64 gpa;
+
+ gpa = kvm_mmu_gva_to_gpa_system(vcpu, gva, 0, NULL);
+
+ action = kvmi_msg_send_bp(vcpu, gpa, insn_len);
+ switch (action) {
+ case KVMI_EVENT_ACTION_CONTINUE:
+ kvm_queue_exception(vcpu, BP_VECTOR);
+ break;
+ case KVMI_EVENT_ACTION_RETRY:
+ /* rip was most likely adjusted past the INT 3 instruction */
+ break;
+ default:
+ kvmi_handle_common_event_actions(vcpu->kvm, action);
+ }
+}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 580997701b1c..47c50e2f0f86 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -25,6 +25,7 @@
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/rwsem.h>
+#include <linux/kvmi_host.h>
#include <asm/apic.h>
#include <asm/perf_event.h>
@@ -1841,10 +1842,43 @@ static int db_interception(struct vcpu_svm *svm)
return 1;
}
+static unsigned svm_get_instruction_len(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+ unsigned long rip = kvm_rip_read(vcpu);
+ unsigned long next_rip = 0;
+ unsigned insn_len;
+
+ if (static_cpu_has(X86_FEATURE_NRIPS))
+ next_rip = svm->vmcb->control.next_rip;
+
+ if (!next_rip) {
+ if (!kvm_emulate_instruction(vcpu, EMULTYPE_SKIP))
+ return 0;
+
+ next_rip = kvm_rip_read(vcpu);
+ kvm_rip_write(vcpu, rip);
+ }
+
+ insn_len = next_rip - rip;
+ if (insn_len > MAX_INST_SIZE) {
+ pr_err("%s: ip 0x%lx next 0x%lx\n",
+ __func__, rip, next_rip);
+ return 0;
+ }
+
+ return insn_len;
+}
+
static int bp_interception(struct vcpu_svm *svm)
{
struct kvm_run *kvm_run = svm->vcpu.run;
+ if (!kvmi_breakpoint_event(&svm->vcpu, svm->vmcb->save.cs.base +
+ svm->vmcb->save.rip,
+ svm_get_instruction_len(&svm->vcpu)))
+ return 1;
+
kvm_run->exit_reason = KVM_EXIT_DEBUG;
kvm_run->debug.arch.pc = svm->vmcb->save.cs.base + svm->vmcb->save.rip;
kvm_run->debug.arch.exception = BP_VECTOR;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4ef4f3c1b78a..9e1bea74b74c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -27,6 +27,7 @@
#include <linux/slab.h>
#include <linux/tboot.h>
#include <linux/trace_events.h>
+#include <linux/kvmi_host.h>
#include <asm/apic.h>
#include <asm/asm.h>
@@ -4798,7 +4799,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct kvm_run *kvm_run = vcpu->run;
u32 intr_info, ex_no, error_code;
- unsigned long cr2, rip, dr6;
+ unsigned long cr2, dr6;
u32 vect_info;
vect_info = vmx->idt_vectoring_info;
@@ -4871,7 +4872,10 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
kvm_run->debug.arch.dr6 = dr6 | DR6_FIXED_1 | DR6_RTM;
kvm_run->debug.arch.dr7 = vmcs_readl(GUEST_DR7);
/* fall through */
- case BP_VECTOR:
+ case BP_VECTOR: {
+ unsigned long gva = vmcs_readl(GUEST_CS_BASE) +
+ kvm_rip_read(vcpu);
+
/*
* Update instruction length as we may reinject #BP from
* user space while in guest debugging mode. Reading it for
@@ -4879,11 +4883,16 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
*/
vmx->vcpu.arch.event_exit_inst_len =
vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+
+ if (!kvmi_breakpoint_event(vcpu, gva,
+ vmx->vcpu.arch.event_exit_inst_len))
+ return 1;
+
kvm_run->exit_reason = KVM_EXIT_DEBUG;
- rip = kvm_rip_read(vcpu);
- kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
+ kvm_run->debug.arch.pc = gva;
kvm_run->debug.arch.exception = ex_no;
break;
+ }
case AC_VECTOR:
if (guest_inject_ac(vcpu)) {
kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
diff --git a/include/linux/kvmi_host.h b/include/linux/kvmi_host.h
index 5c4b9c160019..c4fac41bd5c7 100644
--- a/include/linux/kvmi_host.h
+++ b/include/linux/kvmi_host.h
@@ -73,6 +73,7 @@ int kvmi_ioctl_preunhook(struct kvm *kvm);
void kvmi_handle_requests(struct kvm_vcpu *vcpu);
bool kvmi_hypercall_event(struct kvm_vcpu *vcpu);
+bool kvmi_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len);
#else
@@ -84,6 +85,9 @@ static inline void kvmi_vcpu_uninit(struct kvm_vcpu *vcpu) { }
static inline void kvmi_handle_requests(struct kvm_vcpu *vcpu) { }
static inline bool kvmi_hypercall_event(struct kvm_vcpu *vcpu) { return false;
}
+static inline bool kvmi_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva,
+ u8 insn_len)
+ { return true; }
#endif /* CONFIG_KVM_INTROSPECTION */
diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h
index 7d1febd671d7..026ae5911b1c 100644
--- a/include/uapi/linux/kvmi.h
+++ b/include/uapi/linux/kvmi.h
@@ -39,6 +39,7 @@ enum {
KVMI_EVENT_UNHOOK = 0,
KVMI_EVENT_PAUSE_VCPU = 1,
KVMI_EVENT_HYPERCALL = 2,
+ KVMI_EVENT_BREAKPOINT = 3,
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 3a76842e48c6..3b921e3cf958 100644
--- a/tools/testing/selftests/kvm/x86_64/kvmi_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvmi_test.c
@@ -49,6 +49,7 @@ struct vcpu_worker_data {
enum {
GUEST_TEST_NOOP = 0,
+ GUEST_TEST_BP,
GUEST_TEST_HYPERCALL,
};
@@ -63,6 +64,11 @@ static int guest_test_id(void)
return READ_ONCE(test_id);
}
+static void guest_bp_test(void)
+{
+ asm volatile("int3");
+}
+
static void guest_hypercall_test(void)
{
asm volatile("mov $34, %rax");
@@ -77,6 +83,9 @@ static void guest_code(void)
switch (guest_test_id()) {
case GUEST_TEST_NOOP:
break;
+ case GUEST_TEST_BP:
+ guest_bp_test();
+ break;
case GUEST_TEST_HYPERCALL:
guest_hypercall_test();
break;
@@ -1107,6 +1116,42 @@ static void test_event_hypercall(struct kvm_vm *vm)
disable_vcpu_event(vm, event_id);
}
+static void test_event_breakpoint(struct kvm_vm *vm)
+{
+ struct vcpu_worker_data data = {
+ .vm = vm,
+ .vcpu_id = VCPU_ID,
+ .test_id = GUEST_TEST_BP,
+ };
+ struct kvmi_msg_hdr hdr;
+ struct {
+ struct kvmi_event common;
+ struct kvmi_event_breakpoint bp;
+ } ev;
+ struct vcpu_reply rpl = {};
+ __u16 event_id = KVMI_EVENT_BREAKPOINT;
+ pthread_t vcpu_thread;
+
+ enable_vcpu_event(vm, event_id);
+
+ vcpu_thread = start_vcpu_worker(&data);
+
+ receive_event(&hdr, &ev.common, sizeof(ev), event_id);
+
+ pr_info("Breakpoint event, rip 0x%llx, len %u\n",
+ ev.common.arch.regs.rip, ev.bp.insn_len);
+
+ ev.common.arch.regs.rip += ev.bp.insn_len;
+ __set_registers(vm, &ev.common.arch.regs);
+
+ reply_to_event(&hdr, &ev.common, KVMI_EVENT_ACTION_RETRY,
+ &rpl, sizeof(rpl));
+
+ stop_vcpu_worker(vcpu_thread, &data);
+
+ disable_vcpu_event(vm, event_id);
+}
+
static void test_introspection(struct kvm_vm *vm)
{
srandom(time(0));
@@ -1128,6 +1173,7 @@ static void test_introspection(struct kvm_vm *vm)
test_cmd_vcpu_set_registers(vm);
test_cmd_vcpu_get_cpuid(vm);
test_event_hypercall(vm);
+ test_event_breakpoint(vm);
unhook_introspection(vm);
}
diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c
index 571b79c52353..a5264696c630 100644
--- a/virt/kvm/introspection/kvmi.c
+++ b/virt/kvm/introspection/kvmi.c
@@ -97,6 +97,7 @@ static void setup_known_events(void)
set_bit(KVMI_EVENT_UNHOOK, Kvmi_known_vm_events);
bitmap_zero(Kvmi_known_vcpu_events, KVMI_NUM_EVENTS);
+ set_bit(KVMI_EVENT_BREAKPOINT, Kvmi_known_vcpu_events);
set_bit(KVMI_EVENT_HYPERCALL, Kvmi_known_vcpu_events);
set_bit(KVMI_EVENT_PAUSE_VCPU, Kvmi_known_vcpu_events);
@@ -637,7 +638,7 @@ int kvmi_cmd_vcpu_control_events(struct kvm_vcpu *vcpu,
else
clear_bit(event_id, vcpui->ev_enable_mask);
- return 0;
+ return kvmi_arch_cmd_control_intercept(vcpu, event_id, enable);
}
static unsigned long gfn_to_hva_safe(struct kvm *kvm, gfn_t gfn)
@@ -908,3 +909,23 @@ bool kvmi_hypercall_event(struct kvm_vcpu *vcpu)
return ret;
}
+
+bool kvmi_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len)
+{
+ struct kvm_introspection *kvmi;
+ bool ret = false;
+
+ kvmi = kvmi_get(vcpu->kvm);
+ if (!kvmi)
+ return true;
+
+ if (is_event_enabled(vcpu, KVMI_EVENT_BREAKPOINT))
+ kvmi_arch_breakpoint_event(vcpu, gva, insn_len);
+ else
+ ret = true;
+
+ kvmi_put(vcpu->kvm);
+
+ return ret;
+}
+EXPORT_SYMBOL(kvmi_breakpoint_event);
diff --git a/virt/kvm/introspection/kvmi_int.h
b/virt/kvm/introspection/kvmi_int.h
index 8c02528e3056..810dde913ad6 100644
--- a/virt/kvm/introspection/kvmi_int.h
+++ b/virt/kvm/introspection/kvmi_int.h
@@ -34,6 +34,7 @@ bool kvmi_msg_process(struct kvm_introspection *kvmi);
int kvmi_msg_send_unhook(struct kvm_introspection *kvmi);
u32 kvmi_msg_send_vcpu_pause(struct kvm_vcpu *vcpu);
u32 kvmi_msg_send_hypercall(struct kvm_vcpu *vcpu);
+u32 kvmi_msg_send_bp(struct kvm_vcpu *vcpu, u64 gpa, u8 insn_len);
/* kvmi.c */
void *kvmi_msg_alloc(void);
@@ -79,5 +80,8 @@ int kvmi_arch_cmd_vcpu_get_cpuid(struct kvm_vcpu *vcpu,
struct kvmi_vcpu_get_cpuid_reply *rpl);
bool kvmi_arch_is_agent_hypercall(struct kvm_vcpu *vcpu);
void kvmi_arch_hypercall_event(struct kvm_vcpu *vcpu);
+void kvmi_arch_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len);
+int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu,
+ unsigned int event_id, bool enable);
#endif
diff --git a/virt/kvm/introspection/kvmi_msg.c
b/virt/kvm/introspection/kvmi_msg.c
index 80ade6055747..4a03980e0bbb 100644
--- a/virt/kvm/introspection/kvmi_msg.c
+++ b/virt/kvm/introspection/kvmi_msg.c
@@ -805,3 +805,20 @@ u32 kvmi_msg_send_hypercall(struct kvm_vcpu *vcpu)
return action;
}
+
+u32 kvmi_msg_send_bp(struct kvm_vcpu *vcpu, u64 gpa, u8 insn_len)
+{
+ struct kvmi_event_breakpoint e;
+ int err, action;
+
+ memset(&e, 0, sizeof(e));
+ e.gpa = gpa;
+ e.insn_len = insn_len;
+
+ err = kvmi_send_event(vcpu, KVMI_EVENT_BREAKPOINT, &e, sizeof(e),
+ NULL, 0, &action);
+ if (err)
+ return KVMI_EVENT_ACTION_CONTINUE;
+
+ return action;
+}
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