Hyprland/src/plugins/HookSystem.cpp

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#include "HookSystem.hpp"
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#include "../debug/Log.hpp"
#include "../helpers/VarList.hpp"
#define register
#include <udis86.h>
#undef register
#include <sys/mman.h>
#include <unistd.h>
#include <cstring>
#include <fstream>
CFunctionHook::CFunctionHook(HANDLE owner, void* source, void* destination) {
m_pSource = source;
m_pDestination = destination;
m_pOwner = owner;
}
CFunctionHook::~CFunctionHook() {
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if (m_bActive)
unhook();
}
CFunctionHook::SInstructionProbe CFunctionHook::getInstructionLenAt(void* start) {
ud_t udis;
ud_init(&udis);
ud_set_mode(&udis, 64);
ud_set_syntax(&udis, UD_SYN_ATT);
size_t curOffset = 1;
size_t insSize = 0;
while (true) {
ud_set_input_buffer(&udis, (uint8_t*)start, curOffset);
insSize = ud_disassemble(&udis);
if (insSize != curOffset)
break;
curOffset++;
}
// check for RIP refs
std::string ins;
if (const auto CINS = ud_insn_asm(&udis); CINS)
ins = std::string(CINS);
return {insSize, ins};
}
CFunctionHook::SInstructionProbe CFunctionHook::probeMinimumJumpSize(void* start, size_t min) {
size_t size = 0;
std::string instrs = "";
std::vector<size_t> sizes;
while (size <= min) {
// find info about this instruction
auto probe = getInstructionLenAt((uint8_t*)start + size);
sizes.push_back(probe.len);
size += probe.len;
instrs += probe.assembly + "\n";
}
return {size, instrs, sizes};
}
CFunctionHook::SAssembly CFunctionHook::fixInstructionProbeRIPCalls(const SInstructionProbe& probe) {
SAssembly returns;
// analyze the code and fix what we know how to.
uint64_t currentAddress = (uint64_t)m_pSource;
// actually newline + 1
size_t lastAsmNewline = 0;
// needle for destination binary
size_t currentDestinationOffset = 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;
size_t minusPresent = tokens[1][0] == '-' ? 1 : 0;
std::string addr = tokens[1].substr((plusPresent || minusPresent), tokens[1].find("(%rip)") - (plusPresent || minusPresent));
const uint64_t OFFSET = (minusPresent ? -1 : 1) * configStringToInt(addr);
if (OFFSET == 0)
return {};
const uint64_t DESTINATION = currentAddress + OFFSET + len;
if (code.starts_with("call")) {
// call +0xdeadbeef(%rip)
assemblyBuilder += std::format("pushq %rax\nmovabs $0x{:x}, %rax\ncallq *%rax\npopq %rax\n", DESTINATION);
currentDestinationOffset += 14;
} else if (code.starts_with("lea")) {
// lea 0xdeadbeef(%rip), %rax
assemblyBuilder += std::format("movabs $0x{:x}, {}\n", DESTINATION, tokens[2]);
currentDestinationOffset += 10;
} else {
auto ADDREND = code.find("(%rip)");
auto ADDRSTART = (code.substr(0, ADDREND).find_last_of(' '));
if (ADDREND == std::string::npos || ADDRSTART == std::string::npos)
return {};
const uint64_t PREDICTEDRIP = (uint64_t)m_pTrampolineAddr + currentDestinationOffset + len;
const bool POSITIVE = DESTINATION > PREDICTEDRIP;
const uint64_t NEWRIPOFFSET = POSITIVE ? DESTINATION - PREDICTEDRIP : PREDICTEDRIP - DESTINATION;
assemblyBuilder += std::format("{} {}0x{:x}{}\n", code.substr(0, ADDRSTART), POSITIVE ? '+' : '-', NEWRIPOFFSET, code.substr(ADDREND));
currentDestinationOffset += len;
}
} else if (code.contains("invalid")) {
std::vector<uint8_t> bytes;
bytes.resize(len);
memcpy(bytes.data(), (std::byte*)currentAddress, len);
if (len == 4 && bytes[0] == 0xF3 && bytes[1] == 0x0F && bytes[2] == 0x1E && bytes[3] == 0xFA) {
// F3 0F 1E FA = endbr64, udis doesn't understand that one
assemblyBuilder += "endbr64\n";
currentDestinationOffset += 4;
} else {
// raise error, unknown op
std::string strBytes;
for (auto& b : bytes) {
strBytes += std::format("{:x} ", b);
}
Debug::log(ERR, "[functionhook] unknown bytes: {}", strBytes);
return {};
}
} else {
assemblyBuilder += code + "\n";
currentDestinationOffset += len;
}
lastAsmNewline = probe.assembly.find("\n", lastAsmNewline) + 1;
currentAddress += len;
}
std::ofstream ofs("/tmp/hypr/.hookcode.asm", std::ios::trunc);
ofs << assemblyBuilder;
ofs.close();
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std::string ret = execAndGet(
"cc -x assembler -c /tmp/hypr/.hookcode.asm -o /tmp/hypr/.hookbinary.o 2>&1 && objcopy -O binary -j .text /tmp/hypr/.hookbinary.o /tmp/hypr/.hookbinary2.o 2>&1");
Debug::log(LOG, "[functionhook] assembler returned:\n{}", ret);
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);
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() {
// check for unsupported platforms
#if !defined(__x86_64__)
return false;
#endif
// movabs $0,%rax | jmpq *%rax
// 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;
// alloc trampoline
const auto MAX_TRAMPOLINE_SIZE = HOOK_TRAMPOLINE_MAX_SIZE; // we will never need more.
m_pTrampolineAddr = (void*)g_pFunctionHookSystem->getAddressForTrampo();
// probe instructions to be trampolin'd
SInstructionProbe probe;
try {
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 asm / failed assembling:\n{}", probe.assembly);
return false;
}
const size_t HOOKSIZE = PROBEFIXEDASM.bytes.size();
const size_t ORIGSIZE = probe.len;
const auto TRAMPOLINE_SIZE = sizeof(ABSOLUTE_JMP_ADDRESS) + HOOKSIZE + sizeof(PUSH_RAX);
if (TRAMPOLINE_SIZE > MAX_TRAMPOLINE_SIZE) {
Debug::log(ERR, "[functionhook] failed, not enough space in trampo to alloc:\n{}", probe.assembly);
return false;
}
m_pOriginalBytes = malloc(ORIGSIZE);
memcpy(m_pOriginalBytes, m_pSource, ORIGSIZE);
// populate trampoline
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
// fixup trampoline addr
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*(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));
// make jump to hk
const auto PAGESIZE_VAR = sysconf(_SC_PAGE_SIZE);
const uint8_t* PROTSTART = (uint8_t*)m_pSource - ((uint64_t)m_pSource % PAGESIZE_VAR);
const size_t PROTLEN = std::ceil((float)(ORIGSIZE + ((uint64_t)m_pSource - (uint64_t)PROTSTART)) / (float)PAGESIZE_VAR) * PAGESIZE_VAR;
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, ORIGSIZE - currentOp);
// fixup jump addr
*(uint64_t*)((uint8_t*)m_pSource + ABSOLUTE_JMP_ADDRESS_OFFSET) = (uint64_t)(m_pDestination);
// revert mprot
mprotect((uint8_t*)PROTSTART, PROTLEN, PROT_READ | PROT_EXEC);
// set original addr to trampo addr
m_pOriginal = m_pTrampolineAddr;
m_bActive = true;
m_iHookLen = ORIGSIZE;
m_iTrampoLen = TRAMPOLINE_SIZE;
return true;
}
bool CFunctionHook::unhook() {
// check for unsupported platforms
#if !defined(__x86_64__)
return false;
#endif
if (!m_bActive)
return false;
// allow write to src
mprotect((uint8_t*)m_pSource - ((uint64_t)m_pSource) % sysconf(_SC_PAGE_SIZE), sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE | PROT_EXEC);
// write back original bytes
memcpy(m_pSource, m_pOriginalBytes, m_iHookLen);
// revert mprot
mprotect((uint8_t*)m_pSource - ((uint64_t)m_pSource) % sysconf(_SC_PAGE_SIZE), sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_EXEC);
// reset vars
m_bActive = false;
m_iHookLen = 0;
m_iTrampoLen = 0;
m_pTrampolineAddr = nullptr; // no unmapping, it's managed by the HookSystem
m_pOriginalBytes = nullptr;
free(m_pOriginalBytes);
return true;
}
CFunctionHook* CHookSystem::initHook(HANDLE owner, void* source, void* destination) {
return m_vHooks.emplace_back(std::make_unique<CFunctionHook>(owner, source, destination)).get();
}
bool CHookSystem::removeHook(CFunctionHook* hook) {
std::erase_if(m_vHooks, [&](const auto& other) { return other.get() == hook; });
return true; // todo: make false if not found
}
void CHookSystem::removeAllHooksFrom(HANDLE handle) {
std::erase_if(m_vHooks, [&](const auto& other) { return other->m_pOwner == handle; });
}
static uintptr_t seekNewPageAddr() {
const uint64_t PAGESIZE_VAR = sysconf(_SC_PAGE_SIZE);
auto MAPS = std::ifstream("/proc/self/maps");
uint64_t lastStart = 0, lastEnd = 0;
std::string line;
while (std::getline(MAPS, line)) {
CVarList props{line, 0, 's', true};
uint64_t start = 0, end = 0;
if (props[0].empty()) {
Debug::log(WARN, "seekNewPageAddr: unexpected line in self maps");
continue;
}
CVarList startEnd{props[0], 0, '-', true};
try {
start = std::stoull(startEnd[0], nullptr, 16);
end = std::stoull(startEnd[1], nullptr, 16);
} catch (std::exception& e) {
Debug::log(WARN, "seekNewPageAddr: unexpected line in self maps: {}", line);
continue;
}
Debug::log(LOG, "seekNewPageAddr: page 0x{:x} - 0x{:x}", start, end);
if (lastStart == 0) {
lastStart = start;
lastEnd = end;
continue;
}
if (start - lastEnd > PAGESIZE_VAR * 2) {
Debug::log(LOG, "seekNewPageAddr: found gap: 0x{:x}-0x{:x} ({} bytes)", lastEnd, start, start - lastEnd);
MAPS.close();
return lastEnd;
}
lastStart = start;
lastEnd = end;
}
MAPS.close();
return 0;
}
uint64_t CHookSystem::getAddressForTrampo() {
// yes, technically this creates a memory leak of 64B every hook creation. But I don't care.
// tracking all the users of the memory would be painful.
// Nobody will hook 100k times, and even if, that's only 6.4 MB. Nothing.
SAllocatedPage* page = nullptr;
for (auto& p : pages) {
if (p.used + HOOK_TRAMPOLINE_MAX_SIZE > p.len)
continue;
page = &p;
break;
}
if (!page)
page = &pages.emplace_back();
if (!page->addr) {
// allocate it
Debug::log(LOG, "getAddressForTrampo: Allocating new page for hooks");
const uint64_t PAGESIZE_VAR = sysconf(_SC_PAGE_SIZE);
const auto BASEPAGEADDR = seekNewPageAddr();
for (int attempt = 0; attempt < 2; ++attempt) {
for (int i = 2; i >= 0; --i) {
const auto PAGEADDR = BASEPAGEADDR + i * PAGESIZE_VAR;
page->addr = (uint64_t)mmap((void*)PAGEADDR, PAGESIZE_VAR, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
page->len = PAGESIZE_VAR;
page->used = 0;
Debug::log(LOG, "Attempted to allocate 0x{:x}, got 0x{:x}", PAGEADDR, page->addr);
if (page->addr == (uint64_t)MAP_FAILED)
continue;
if (page->addr != PAGEADDR && attempt == 0) {
munmap((void*)page->addr, PAGESIZE_VAR);
page->addr = 0;
page->len = 0;
continue;
}
break;
}
if (page->addr)
break;
}
}
const auto ADDRFORCONSUMER = page->addr + page->used;
page->used += HOOK_TRAMPOLINE_MAX_SIZE;
Debug::log(LOG, "getAddressForTrampo: Returning addr 0x{:x} for page at 0x{:x}", ADDRFORCONSUMER, page->addr);
return ADDRFORCONSUMER;
}