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Plugin Hooks: fix calls to %rip offsets

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This commit is contained in:
vaxerski 2023-02-27 18:34:44 +00:00
parent 3bceabe29b
commit c5d741fb39
2 changed files with 56 additions and 15 deletions
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50
src/plugins/HookSystem.cpp
View file

@ -19,7 +19,7 @@ CFunctionHook::~CFunctionHook() {
}
}
size_t getInstructionLenAt(void* start) {
size_t CFunctionHook::getInstructionLenAt(void* start) {
ud_t udis;
ud_init(&udis);
@ -36,10 +36,22 @@ size_t getInstructionLenAt(void* start) {
curOffset++;
}
// check for RIP refs
std::string ins;
if (const auto CINS = ud_insn_asm(&udis); CINS)
ins = std::string(CINS);
if (!ins.empty() && ins.find("rip") != std::string::npos) {
// todo: support something besides call qword ptr [rip + 0xdeadbeef]
// I don't have an assembler. I don't think udis provides one. Besides, variables might be tricky.
if (((uint8_t*)start)[0] == 0xFF && ((uint8_t*)start)[1] == 0x15)
m_vTrampolineRIPUses.emplace_back(std::make_pair<>((uint64_t)start - (uint64_t)m_pSource, ins));
}
return insSize;
}
size_t probeMinimumJumpSize(void* start, size_t min) {
size_t CFunctionHook::probeMinimumJumpSize(void* start, size_t min) {
size_t size = 0;
@ -60,27 +72,51 @@ bool CFunctionHook::hook() {
#endif
// movabs $0,%rax | jmpq *%rax
static constexpr uint8_t ABSOLUTE_JMP_ADDRESS[] = {0x48, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xE0};
// offset for addr: 2
static constexpr uint8_t ABSOLUTE_JMP_ADDRESS[] = {0x48, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xE0};
static constexpr size_t ABSOLUTE_JMP_ADDRESS_OFFSET = 2;
// pushq %rax
static constexpr uint8_t PUSH_RAX[] = {0x50};
// popq %rax
static constexpr uint8_t POP_RAX[] = {0x58};
// nop
static constexpr uint8_t NOP = 0x90;
/*
pushq %rax
movabs $0,%rax
callq *%rax
popq %rax
offset for addr: 3
*/
static constexpr uint8_t CALL_WITH_RAX[] = {0x50, 0x48, 0xB8, 0xEF, 0xBE, 0xAD, 0xDE, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x10, 0x58};
static constexpr size_t CALL_WITH_RAX_ADDRESS_OFFSET = 3;
// get minimum size to overwrite
const auto HOOKSIZE = probeMinimumJumpSize(m_pSource, sizeof(ABSOLUTE_JMP_ADDRESS) + sizeof(PUSH_RAX) + sizeof(POP_RAX));
// alloc trampoline
m_pTrampolineAddr = mmap(NULL, sizeof(ABSOLUTE_JMP_ADDRESS) + HOOKSIZE + sizeof(PUSH_RAX), PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
const auto TRAMPOLINE_SIZE = sizeof(ABSOLUTE_JMP_ADDRESS) + HOOKSIZE + sizeof(PUSH_RAX) + m_vTrampolineRIPUses.size() * (sizeof(CALL_WITH_RAX) - 6);
m_pTrampolineAddr = mmap(NULL, TRAMPOLINE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
// populate trampoline
memcpy(m_pTrampolineAddr, m_pSource, HOOKSIZE); // first, original func bytes
memcpy(m_pTrampolineAddr + HOOKSIZE, PUSH_RAX, sizeof(PUSH_RAX)); // then, pushq %rax
memcpy(m_pTrampolineAddr + HOOKSIZE + sizeof(PUSH_RAX), ABSOLUTE_JMP_ADDRESS, sizeof(ABSOLUTE_JMP_ADDRESS)); // then, jump to source
// fix trampoline %rip calls
for (size_t i = 0; i < m_vTrampolineRIPUses.size(); ++i) {
size_t callOffset = i * (sizeof(CALL_WITH_RAX) - 6 /* callq [rip + x] */) + m_vTrampolineRIPUses[i].first;
size_t realCallAddress = (uint64_t)m_pSource + callOffset + 6 + *((uint32_t*)(m_pSource + callOffset + 2));
memmove(m_pTrampolineAddr + callOffset + sizeof(CALL_WITH_RAX), m_pTrampolineAddr + callOffset + 6, TRAMPOLINE_SIZE - callOffset - 6);
memcpy(m_pTrampolineAddr + callOffset, CALL_WITH_RAX, sizeof(CALL_WITH_RAX));
*(uint64_t*)(m_pTrampolineAddr + callOffset + CALL_WITH_RAX_ADDRESS_OFFSET) = (uint64_t)realCallAddress;
}
// fixup trampoline addr
*(uint64_t*)(m_pTrampolineAddr + HOOKSIZE + 2 + sizeof(PUSH_RAX)) = (uint64_t)(m_pSource + sizeof(ABSOLUTE_JMP_ADDRESS));
*(uint64_t*)(m_pTrampolineAddr + TRAMPOLINE_SIZE - sizeof(ABSOLUTE_JMP_ADDRESS) + ABSOLUTE_JMP_ADDRESS_OFFSET) = (uint64_t)(m_pSource + sizeof(ABSOLUTE_JMP_ADDRESS));
// make jump to hk
mprotect(m_pSource - ((uint64_t)m_pSource) % sysconf(_SC_PAGE_SIZE), sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE | PROT_EXEC);
@ -92,7 +128,7 @@ bool CFunctionHook::hook() {
memset(m_pSource + currentOp, NOP, HOOKSIZE - currentOp);
// fixup jump addr
*(uint64_t*)(m_pSource + 2) = (uint64_t)(m_pDestination);
*(uint64_t*)(m_pSource + ABSOLUTE_JMP_ADDRESS_OFFSET) = (uint64_t)(m_pDestination);
// revert mprot
mprotect(m_pSource - ((uint64_t)m_pSource) % sysconf(_SC_PAGE_SIZE), sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_EXEC);
@ -102,7 +138,7 @@ bool CFunctionHook::hook() {
m_bActive = true;
m_iHookLen = HOOKSIZE;
m_iTrampoLen = HOOKSIZE + sizeof(ABSOLUTE_JMP_ADDRESS);
m_iTrampoLen = TRAMPOLINE_SIZE;
return true;
}

21
src/plugins/HookSystem.hpp
View file

@ -22,14 +22,19 @@ class CFunctionHook {
void* m_pOriginal = nullptr;
private:
void* m_pSource = nullptr;
void* m_pFunctionAddr = nullptr;
void* m_pTrampolineAddr = nullptr;
void* m_pDestination = nullptr;
size_t m_iHookLen = 0;
size_t m_iTrampoLen = 0;
HANDLE m_pOwner = nullptr;
bool m_bActive = false;
void* m_pSource = nullptr;
void* m_pFunctionAddr = nullptr;
void* m_pTrampolineAddr = nullptr;
void* m_pDestination = nullptr;
size_t m_iHookLen = 0;
size_t m_iTrampoLen = 0;
HANDLE m_pOwner = nullptr;
bool m_bActive = false;
std::vector<std::pair<size_t, std::string>> m_vTrampolineRIPUses;
size_t probeMinimumJumpSize(void* start, size_t min);
size_t getInstructionLenAt(void* start);
friend class CHookSystem;
};