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pluginapi: Trampoline hooks %rip patching improvements (#4256)

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Co-authored-by: Jan Beich <jbeich@FreeBSD.org>
This commit is contained in:
Vaxry 2023-12-27 11:43:04 +01:00 committed by GitHub
parent 191fa587f4
commit 7474c81958
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 114 additions and 60 deletions
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140
src/plugins/HookSystem.cpp
View file

@ -1,5 +1,6 @@
#include "HookSystem.hpp"
#include "../debug/Log.hpp"
#include "../helpers/VarList.hpp"
#define register
#include <udis86.h>
@ -19,12 +20,12 @@ CFunctionHook::~CFunctionHook() {
unhook();
}
size_t CFunctionHook::getInstructionLenAt(void* start) {
CFunctionHook::SInstructionProbe CFunctionHook::getInstructionLenAt(void* start) {
ud_t udis;
ud_init(&udis);
ud_set_mode(&udis, 64);
ud_set_syntax(&udis, UD_SYN_INTEL);
ud_set_syntax(&udis, UD_SYN_ATT);
size_t curOffset = 1;
size_t insSize = 0;
@ -41,31 +42,83 @@ size_t CFunctionHook::getInstructionLenAt(void* start) {
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));
else {
Debug::log(ERR, "[CFunctionHook] Cannot hook: unsupported %rip usage: {}", ins);
throw std::runtime_error("unsupported %rip usage");
}
}
return insSize;
return {insSize, ins};
}
size_t CFunctionHook::probeMinimumJumpSize(void* start, size_t min) {
CFunctionHook::SInstructionProbe CFunctionHook::probeMinimumJumpSize(void* start, size_t min) {
size_t size = 0;
size_t size = 0;
std::string instrs = "";
std::vector<size_t> sizes;
while (size <= min) {
// find info about this instruction
size_t insLen = getInstructionLenAt((uint8_t*)start + size);
size += insLen;
auto probe = getInstructionLenAt((uint8_t*)start + size);
sizes.push_back(probe.len);
size += probe.len;
instrs += probe.assembly + "\n";
}
return size;
return {size, instrs, sizes};
}
CFunctionHook::SAssembly CFunctionHook::fixInstructionProbeRIPCalls(const SInstructionProbe& probe) {
// analyze the code and fix what we know how to.
uint64_t currentAddress = (uint64_t)m_pSource;
// actually newline + 1
size_t lastAsmNewline = 0;
std::string assemblyBuilder;
for (auto& len : probe.insSizes) {
std::string code = probe.assembly.substr(lastAsmNewline, probe.assembly.find("\n", lastAsmNewline) - lastAsmNewline);
if (code.contains("%rip")) {
CVarList tokens{code, 0, 's'};
size_t plusPresent = tokens[1][0] == '+' ? 1 : 0;
std::string addr = tokens[1].substr(plusPresent, tokens[1].find("(%rip)") - plusPresent);
const uint64_t OFFSET = configStringToInt(addr);
if (OFFSET == 0)
return {};
const uint64_t DESTINATION = currentAddress + OFFSET + len;
if (code.starts_with("mov")) {
// mov +0xdeadbeef(%rip), %rax
assemblyBuilder += std::format("movabs $0x{:x}, {}\n", DESTINATION, tokens[2]);
} else if (code.starts_with("call")) {
// call +0xdeadbeef(%rip)
assemblyBuilder += std::format("pushq %rax\nmovabs $0x{:x}, %rax\ncallq *%rax\npopq %rax\n", DESTINATION);
} else if (code.starts_with("lea")) {
// lea 0xdeadbeef(%rip), %rax
assemblyBuilder += std::format("movabs $0x{:x}, {}\n", DESTINATION, tokens[2]);
} else {
return {};
}
} else {
assemblyBuilder += code + "\n";
}
lastAsmNewline = probe.assembly.find("\n", lastAsmNewline) + 1;
currentAddress += len;
}
std::ofstream ofs("/tmp/hypr/.hookcode.asm", std::ios::trunc);
ofs << assemblyBuilder;
ofs.close();
execAndGet("cc -x assembler -c /tmp/hypr/.hookcode.asm -o /tmp/hypr/.hookbinary.o && objcopy -O binary -j .text /tmp/hypr/.hookbinary.o /tmp/hypr/.hookbinary2.o");
if (!std::filesystem::exists("/tmp/hypr/.hookbinary2.o")) {
std::filesystem::remove("/tmp/hypr/.hookcode.asm");
std::filesystem::remove("/tmp/hypr/.hookbinary.asm");
return {};
}
std::ifstream ifs("/tmp/hypr/.hookbinary2.o", std::ios::binary);
SAssembly returns = {std::vector<char>(std::istreambuf_iterator<char>(ifs), {})};
ifs.close();
std::filesystem::remove("/tmp/hypr/.hookcode.asm");
std::filesystem::remove("/tmp/hypr/.hookbinary.o");
std::filesystem::remove("/tmp/hypr/.hookbinary2.o");
return returns;
}
bool CFunctionHook::hook() {
@ -85,44 +138,35 @@ bool CFunctionHook::hook() {
static constexpr uint8_t POP_RAX[] = {0x58};
// nop
static constexpr uint8_t NOP = 0x90;
/*
movabs $0,%rax
callq *%rax
offset for addr: 3
*/
static constexpr uint8_t CALL_WITH_RAX[] = {0x48, 0xB8, 0xEF, 0xBE, 0xAD, 0xDE, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x10};
static constexpr size_t CALL_WITH_RAX_ADDRESS_OFFSET = 2;
// get minimum size to overwrite
size_t HOOKSIZE = 0;
// probe instructions to be trampolin'd
SInstructionProbe probe;
try {
HOOKSIZE = probeMinimumJumpSize(m_pSource, sizeof(ABSOLUTE_JMP_ADDRESS) + sizeof(PUSH_RAX) + sizeof(POP_RAX));
probe = probeMinimumJumpSize(m_pSource, sizeof(ABSOLUTE_JMP_ADDRESS) + sizeof(PUSH_RAX) + sizeof(POP_RAX));
} catch (std::exception& e) { return false; }
const auto PROBEFIXEDASM = fixInstructionProbeRIPCalls(probe);
if (PROBEFIXEDASM.bytes.size() == 0) {
Debug::log(ERR, "[functionhook] failed, unsupported assembly:\n{}", probe.assembly);
return false;
}
const size_t HOOKSIZE = PROBEFIXEDASM.bytes.size();
const size_t ORIGSIZE = probe.len;
// alloc trampoline
const auto TRAMPOLINE_SIZE = sizeof(ABSOLUTE_JMP_ADDRESS) + HOOKSIZE + sizeof(PUSH_RAX) + m_vTrampolineRIPUses.size() * (sizeof(CALL_WITH_RAX) - 6);
const auto TRAMPOLINE_SIZE = sizeof(ABSOLUTE_JMP_ADDRESS) + HOOKSIZE + sizeof(PUSH_RAX);
m_pTrampolineAddr = mmap(NULL, TRAMPOLINE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
m_pOriginalBytes = malloc(HOOKSIZE);
memcpy(m_pOriginalBytes, m_pSource, HOOKSIZE);
m_pOriginalBytes = malloc(ORIGSIZE);
memcpy(m_pOriginalBytes, m_pSource, ORIGSIZE);
// populate trampoline
memcpy(m_pTrampolineAddr, m_pSource, HOOKSIZE); // first, original func bytes
memcpy(m_pTrampolineAddr, PROBEFIXEDASM.bytes.data(), HOOKSIZE); // first, original but fixed func bytes
memcpy((uint8_t*)m_pTrampolineAddr + HOOKSIZE, PUSH_RAX, sizeof(PUSH_RAX)); // then, pushq %rax
memcpy((uint8_t*)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*)((uint8_t*)m_pSource + callOffset + 2));
memmove((uint8_t*)m_pTrampolineAddr + callOffset + sizeof(CALL_WITH_RAX), (uint8_t*)m_pTrampolineAddr + callOffset + 6, TRAMPOLINE_SIZE - callOffset - 6);
memcpy((uint8_t*)m_pTrampolineAddr + callOffset, CALL_WITH_RAX, sizeof(CALL_WITH_RAX));
*(uint64_t*)((uint8_t*)m_pTrampolineAddr + callOffset + CALL_WITH_RAX_ADDRESS_OFFSET) = (uint64_t)realCallAddress;
}
// fixup trampoline addr
*(uint64_t*)((uint8_t*)m_pTrampolineAddr + TRAMPOLINE_SIZE - sizeof(ABSOLUTE_JMP_ADDRESS) + ABSOLUTE_JMP_ADDRESS_OFFSET) =
(uint64_t)((uint8_t*)m_pSource + sizeof(ABSOLUTE_JMP_ADDRESS));
@ -130,14 +174,14 @@ bool CFunctionHook::hook() {
// make jump to hk
const auto PAGESIZE = sysconf(_SC_PAGE_SIZE);
const uint8_t* PROTSTART = (uint8_t*)m_pSource - ((uint64_t)m_pSource % PAGESIZE);
const size_t PROTLEN = std::ceil((float)(HOOKSIZE + ((uint64_t)m_pSource - (uint64_t)PROTSTART)) / (float)PAGESIZE) * PAGESIZE;
const size_t PROTLEN = std::ceil((float)(ORIGSIZE + ((uint64_t)m_pSource - (uint64_t)PROTSTART)) / (float)PAGESIZE) * PAGESIZE;
mprotect((uint8_t*)PROTSTART, PROTLEN, PROT_READ | PROT_WRITE | PROT_EXEC);
memcpy((uint8_t*)m_pSource, ABSOLUTE_JMP_ADDRESS, sizeof(ABSOLUTE_JMP_ADDRESS));
// make popq %rax and NOP all remaining
memcpy((uint8_t*)m_pSource + sizeof(ABSOLUTE_JMP_ADDRESS), POP_RAX, sizeof(POP_RAX));
size_t currentOp = sizeof(ABSOLUTE_JMP_ADDRESS) + sizeof(POP_RAX);
memset((uint8_t*)m_pSource + currentOp, NOP, HOOKSIZE - currentOp);
memset((uint8_t*)m_pSource + currentOp, NOP, ORIGSIZE - currentOp);
// fixup jump addr
*(uint64_t*)((uint8_t*)m_pSource + ABSOLUTE_JMP_ADDRESS_OFFSET) = (uint64_t)(m_pDestination);
@ -149,7 +193,7 @@ bool CFunctionHook::hook() {
m_pOriginal = m_pTrampolineAddr;
m_bActive = true;
m_iHookLen = HOOKSIZE;
m_iHookLen = ORIGSIZE;
m_iTrampoLen = TRAMPOLINE_SIZE;
return true;

34
src/plugins/HookSystem.hpp
View file

@ -22,21 +22,31 @@ 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;
void* m_pOriginalBytes = nullptr;
void* m_pOriginalBytes = nullptr;
struct SInstructionProbe {
size_t len = 0;
std::string assembly = "";
std::vector<size_t> insSizes;
};
size_t probeMinimumJumpSize(void* start, size_t min);
size_t getInstructionLenAt(void* start);
struct SAssembly {
std::vector<char> bytes;
};
SInstructionProbe probeMinimumJumpSize(void* start, size_t min);
SInstructionProbe getInstructionLenAt(void* start);
SAssembly fixInstructionProbeRIPCalls(const SInstructionProbe& probe);
friend class CHookSystem;
};