diff options
| -rw-r--r-- | executor/common_kvm_amd64_syzos.h | 33 | ||||
| -rw-r--r-- | sys/linux/dev_kvm_amd64.txt | 8 | ||||
| -rw-r--r-- | sys/linux/test/amd64-syz_kvm_nested_amd_set_intercept | 39 |
3 files changed, 80 insertions, 0 deletions
diff --git a/executor/common_kvm_amd64_syzos.h b/executor/common_kvm_amd64_syzos.h index 846569af5..31f62a79c 100644 --- a/executor/common_kvm_amd64_syzos.h +++ b/executor/common_kvm_amd64_syzos.h @@ -37,6 +37,7 @@ typedef enum { SYZOS_API_NESTED_AMD_STGI = 382, SYZOS_API_NESTED_AMD_CLGI = 383, SYZOS_API_NESTED_AMD_INJECT_EVENT = 384, + SYZOS_API_NESTED_AMD_SET_INTERCEPT = 385, SYZOS_API_STOP, // Must be the last one } syzos_api_id; @@ -121,6 +122,7 @@ GUEST_CODE static void guest_handle_nested_amd_invlpga(struct api_call_2* cmd, u GUEST_CODE static void guest_handle_nested_amd_stgi(); GUEST_CODE static void guest_handle_nested_amd_clgi(); GUEST_CODE static void guest_handle_nested_amd_inject_event(struct api_call_5* cmd, uint64 cpu_id); +GUEST_CODE static void guest_handle_nested_amd_set_intercept(struct api_call_5* cmd, uint64 cpu_id); typedef enum { UEXIT_END = (uint64)-1, @@ -248,6 +250,9 @@ guest_main(uint64 size, uint64 cpu) } else if (call == SYZOS_API_NESTED_AMD_INJECT_EVENT) { // Inject an event (IRQ/Exception) into the L2 guest via VMCB. guest_handle_nested_amd_inject_event((struct api_call_5*)cmd, cpu); + } else if (call == SYZOS_API_NESTED_AMD_SET_INTERCEPT) { + // Set/Clear specific intercept bits in the VMCB. + guest_handle_nested_amd_set_intercept((struct api_call_5*)cmd, cpu); } addr += cmd->size; size -= cmd->size; @@ -570,6 +575,11 @@ GUEST_CODE static noinline void vmcb_write32(uint64 vmcb, uint16 offset, uint32 *((volatile uint32*)(vmcb + offset)) = val; } +GUEST_CODE static noinline uint32 vmcb_read32(uint64 vmcb, uint16 offset) +{ + return *((volatile uint32*)(vmcb + offset)); +} + GUEST_CODE static noinline void vmcb_write64(uint64 vmcb, uint16 offset, uint64 val) { *((volatile uint64*)(vmcb + offset)) = val; @@ -1359,4 +1369,27 @@ guest_handle_nested_amd_inject_event(struct api_call_5* cmd, uint64 cpu_id) vmcb_write64(vmcb_addr, 0x60, event_inj); } +GUEST_CODE static noinline void +guest_handle_nested_amd_set_intercept(struct api_call_5* cmd, uint64 cpu_id) +{ + if (get_cpu_vendor() != CPU_VENDOR_AMD) + return; + + uint64 vm_id = cmd->args[0]; + uint64 vmcb_addr = X86_SYZOS_ADDR_VMCS_VMCB(cpu_id, vm_id); + uint64 offset = cmd->args[1]; + uint64 bit_mask = cmd->args[2]; + uint64 action = cmd->args[3]; // 1 = Set, 0 = Clear + + // Read 32-bit intercept field (Offsets 0x00 - 0x14 are all 32-bit vectors). + uint32 current = vmcb_read32(vmcb_addr, (uint16)offset); + + if (action == 1) + current |= (uint32)bit_mask; + else + current &= ~((uint32)bit_mask); + + vmcb_write32(vmcb_addr, (uint16)offset, current); +} + #endif // EXECUTOR_COMMON_KVM_AMD64_SYZOS_H diff --git a/sys/linux/dev_kvm_amd64.txt b/sys/linux/dev_kvm_amd64.txt index acd80540c..0d90ceeab 100644 --- a/sys/linux/dev_kvm_amd64.txt +++ b/sys/linux/dev_kvm_amd64.txt @@ -160,6 +160,13 @@ syzos_api_nested_amd_inject_event { flags int64[0:3] } +syzos_api_nested_amd_set_intercept { + vm_id syzos_api_vm_id + offset int64 + bit_mask int64 + action int64[0:1] +} + # IDs here must match those in executor/common_kvm_amd64_syzos.h. syzos_api_call$x86 [ uexit syzos_api$x86[0, intptr] @@ -183,6 +190,7 @@ syzos_api_call$x86 [ nested_amd_stgi syzos_api$x86[382, void] nested_amd_clgi syzos_api$x86[383, void] nested_amd_inject_event syzos_api$x86[384, syzos_api_nested_amd_inject_event] + nested_amd_set_intercept syzos_api$x86[385, syzos_api_nested_amd_set_intercept] ] [varlen] kvm_text_x86 [ diff --git a/sys/linux/test/amd64-syz_kvm_nested_amd_set_intercept b/sys/linux/test/amd64-syz_kvm_nested_amd_set_intercept new file mode 100644 index 000000000..91293ba0d --- /dev/null +++ b/sys/linux/test/amd64-syz_kvm_nested_amd_set_intercept @@ -0,0 +1,39 @@ +# +# requires: arch=amd64 -threaded +# +r0 = openat$kvm(0, &AUTO='/dev/kvm\x00', 0x0, 0x0) +r1 = ioctl$KVM_CREATE_VM(r0, AUTO, 0x0) +r2 = syz_kvm_setup_syzos_vm$x86(r1, &(0x7f0000c00000/0x400000)=nil) + +# Test AMD Nested Intercepts: The RDTSC Liberation +# +# 1. L1 Setup: +# - SYZOS initializes VMCB with ALL intercepts enabled. +# - We call SET_INTERCEPT to *CLEAR* the RDTSC intercept. +# - Offset: 0xC (Control Vector 1) +# - Bit: 14 (0x4000) = RDTSC +# - Action: 0 (Clear/Disable) +# +# 2. L2 Payload: +# - "rdtsc" (0x0f 0x31) +# - "hlt" (0xf4) +# +# 3. Execution Flow: +# - If RDTSC is intercepted: Exit Reason = RDTSC (0x4). +# - If RDTSC is native: executes RDTSC -> executes HLT -> Exit Reason = HLT (0x1). +# +r3 = syz_kvm_add_vcpu$x86(r2, &AUTO={0x0, &AUTO=[@enable_nested={AUTO, AUTO, 0x0}, @nested_create_vm={AUTO, AUTO, 0x0}, @nested_amd_set_intercept={AUTO, AUTO, {0x0, 0xC, 0x4000, 0x0}}, @nested_load_code={AUTO, AUTO, {0x0, "0f31f4"}}, @nested_vmlaunch={AUTO, AUTO, 0x0}], AUTO}) +r4 = ioctl$KVM_GET_VCPU_MMAP_SIZE(r0, AUTO) +r5 = mmap$KVM_VCPU(&(0x7f0000009000/0x1000)=nil, r4, 0x3, 0x1, r3, 0x0) + +# Run the VCPU. +# Expectation: Success (Native Execution) -> HLT Exit. +# Code: 0xe2e20001 (SYZOS_NESTED_EXIT_REASON_HLT) +# +ioctl$KVM_RUN(r3, AUTO, 0x0) +syz_kvm_assert_syzos_uexit$x86(r3, r5, 0xe2e20001) + +# Cleanup +# +ioctl$KVM_RUN(r3, AUTO, 0x0) +syz_kvm_assert_syzos_uexit$x86(r3, r5, 0xffffffffffffffff) |