diff options
Diffstat (limited to 'src/plugins/HookSystem.cpp')
| -rw-r--r-- | src/plugins/HookSystem.cpp | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/src/plugins/HookSystem.cpp b/src/plugins/HookSystem.cpp new file mode 100644 index 00000000..a8ddd90e --- /dev/null +++ b/src/plugins/HookSystem.cpp @@ -0,0 +1,151 @@ +#include "HookSystem.hpp" + +#define register +#include <udis86.h> +#undef register +#include <sys/mman.h> +#include <unistd.h> +#include <cstring> + +CFunctionHook::CFunctionHook(HANDLE owner, void* source, void* destination) { + m_pSource = source; + m_pDestination = destination; + m_pOwner = owner; +} + +CFunctionHook::~CFunctionHook() { + if (m_bActive) { + unhook(); + } +} + +size_t getInstructionLenAt(void* start) { + ud_t udis; + + ud_init(&udis); + ud_set_mode(&udis, 64); + ud_set_syntax(&udis, UD_SYN_INTEL); + + 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++; + } + + return insSize; +} + +size_t probeMinimumJumpSize(void* start, size_t min) { + + size_t size = 0; + + while (size <= min) { + // find info about this instruction + size_t insLen = getInstructionLenAt(start + size); + size += insLen; + } + + return size; +} + +bool CFunctionHook::hook() { + + // check for unsupported platforms +#if !defined(__x86_64__) + return false; +#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}; + // 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; + + // 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); + + // 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 + + // fixup trampoline addr + *(uint64_t*)(m_pTrampolineAddr + HOOKSIZE + 2 + sizeof(PUSH_RAX)) = (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); + memcpy(m_pSource, ABSOLUTE_JMP_ADDRESS, sizeof(ABSOLUTE_JMP_ADDRESS)); + + // make popq %rax and NOP all remaining + memcpy(m_pSource + sizeof(ABSOLUTE_JMP_ADDRESS), POP_RAX, sizeof(POP_RAX)); + size_t currentOp = sizeof(ABSOLUTE_JMP_ADDRESS) + sizeof(POP_RAX); + memset(m_pSource + currentOp, NOP, HOOKSIZE - currentOp); + + // fixup jump addr + *(uint64_t*)(m_pSource + 2) = (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); + + // set original addr to trampo addr + m_pOriginal = m_pTrampolineAddr; + + m_bActive = true; + m_iHookLen = HOOKSIZE; + m_iTrampoLen = HOOKSIZE + sizeof(ABSOLUTE_JMP_ADDRESS); + + 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(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_pTrampolineAddr, m_iHookLen); + + // revert mprot + mprotect(m_pSource - ((uint64_t)m_pSource) % sysconf(_SC_PAGE_SIZE), sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_EXEC); + + // unmap + munmap(m_pTrampolineAddr, m_iTrampoLen); + + // reset vars + m_bActive = false; + m_iHookLen = 0; + m_iTrampoLen = 0; + m_pTrampolineAddr = nullptr; + + 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; }); +}
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