/*************************************************************************************************** Zyan Disassembler Library (Zydis) Original Author : Florian Bernd * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. ***************************************************************************************************/ /** * @file * @brief Demonstrates the hooking functionality of the @c ZydisFormatter class. * * This example demonstrates the hooking functionality of the @c ZydisFormatter class by * rewriting the mnemonics of (V)CMPPS and (V)CMPPD to their corresponding alias-forms (based on * the condition encoded in the immediate operand). */ #include #include #include #include #include /* ============================================================================================== */ /* Helper functions */ /* ============================================================================================== */ /** * @brief Appends formatted text to the given `string`. * * @param string A pointer to the string. * @param format The format string. * * @return @c ZYDIS_STATUS_SUCCESS, if the function succeeded, or * @c ZYDIS_STATUS_INSUFFICIENT_BUFFER_SIZE, if the size of the buffer was not * sufficient to append the given text. */ ZYDIS_INLINE ZydisStatus ZydisStringAppendFormatC(ZydisString* string, const char* format, ...) { if (!string || !string->buffer || !format) { return ZYDIS_STATUS_INVALID_PARAMETER; } va_list arglist; va_start(arglist, format); const int w = vsnprintf(string->buffer + string->length, string->capacity - string->length, format, arglist); if ((w < 0) || ((size_t)w > string->capacity - string->length)) { va_end(arglist); return ZYDIS_STATUS_INSUFFICIENT_BUFFER_SIZE; } string->length += w; va_end(arglist); return ZYDIS_STATUS_SUCCESS; } /* ============================================================================================== */ /* Static data */ /* ============================================================================================== */ /** * @brief Static array with the condition-code strings. */ static const char* conditionCodeStrings[0x20] = { /*00*/ "eq", /*01*/ "lt", /*02*/ "le", /*03*/ "unord", /*04*/ "neq", /*05*/ "nlt", /*06*/ "nle", /*07*/ "ord", /*08*/ "eq_uq", /*09*/ "nge", /*0A*/ "ngt", /*0B*/ "false", /*0C*/ "oq", /*0D*/ "ge", /*0E*/ "gt", /*0F*/ "true", /*10*/ "eq_os", /*11*/ "lt_oq", /*12*/ "le_oq", /*13*/ "unord_s", /*14*/ "neq_us", /*15*/ "nlt_uq", /*16*/ "nle_uq", /*17*/ "ord_s", /*18*/ "eq_us", /*19*/ "nge_uq", /*1A*/ "ngt_uq", /*1B*/ "false_os", /*1C*/ "neq_os", /*1D*/ "ge_oq", /*1E*/ "gt_oq", /*1F*/ "true_us" }; /* ============================================================================================== */ /* Enums and Types */ /* ============================================================================================== */ /** * @brief Custom user data struct. */ typedef struct ZydisCustomUserData_ { ZydisBool ommitImmediate; } ZydisCustomUserData; /* ============================================================================================== */ /* Hook callbacks */ /* ============================================================================================== */ ZydisFormatterFunc defaultPrintMnemonic; static ZydisStatus ZydisFormatterPrintMnemonic(const ZydisFormatter* formatter, ZydisString* string, const ZydisDecodedInstruction* instruction, ZydisCustomUserData* userData) { // We use the user-data to pass data to the @c ZydisFormatterFormatOperandImm function. userData->ommitImmediate = ZYDIS_TRUE; // Rewrite the instruction-mnemonic for the given instructions if (instruction->operands[instruction->operandCount - 1].type == ZYDIS_OPERAND_TYPE_IMMEDIATE) { const uint8_t conditionCode = (uint8_t)instruction->operands[instruction->operandCount - 1].imm.value.u; switch (instruction->mnemonic) { case ZYDIS_MNEMONIC_CMPPS: if (conditionCode < 0x08) { return ZydisStringAppendFormatC( string, "cmp%sps", conditionCodeStrings[conditionCode]); } break; case ZYDIS_MNEMONIC_CMPPD: if (conditionCode < 0x08) { return ZydisStringAppendFormatC( string, "cmp%spd", conditionCodeStrings[conditionCode]); } break; case ZYDIS_MNEMONIC_VCMPPS: if (conditionCode < 0x20) { return ZydisStringAppendFormatC( string, "vcmp%sps", conditionCodeStrings[conditionCode]); } break; case ZYDIS_MNEMONIC_VCMPPD: if (conditionCode < 0x20) { return ZydisStringAppendFormatC( string, "vcmp%spd", conditionCodeStrings[conditionCode]); } break; default: break; } } // We did not rewrite the instruction-mnemonic. Signal the @c ZydisFormatterFormatOperandImm // function not to omit the operand userData->ommitImmediate = ZYDIS_FALSE; // Default mnemonic printing return defaultPrintMnemonic(formatter, string, instruction, userData); } /* ---------------------------------------------------------------------------------------------- */ ZydisFormatterOperandFunc defaultFormatOperandImm; static ZydisStatus ZydisFormatterFormatOperandImm(const ZydisFormatter* formatter, ZydisString* string, const ZydisDecodedInstruction* instruction, const ZydisDecodedOperand* operand, ZydisCustomUserData* userData) { // The @c ZydisFormatterFormatMnemonic sinals us to omit the immediate (condition-code) // operand, because it got replaced by the alias-mnemonic if (userData->ommitImmediate) { // The formatter will automatically omit the operand, if the buffer remains unchanged // after the callback returns return ZYDIS_STATUS_SUCCESS; } // Default immediate formatting return defaultFormatOperandImm(formatter, string, instruction, operand, userData); } /* ---------------------------------------------------------------------------------------------- */ /* ============================================================================================== */ /* Helper functions */ /* ============================================================================================== */ void disassembleBuffer(ZydisDecoder* decoder, uint8_t* data, size_t length, ZydisBool installHooks) { ZydisFormatter formatter; ZydisFormatterInit(&formatter, ZYDIS_FORMATTER_STYLE_INTEL); ZydisFormatterSetProperty(&formatter, ZYDIS_FORMATTER_PROP_FORCE_MEMSEG, ZYDIS_TRUE); ZydisFormatterSetProperty(&formatter, ZYDIS_FORMATTER_PROP_FORCE_MEMSIZE, ZYDIS_TRUE); if (installHooks) { defaultPrintMnemonic = (ZydisFormatterFunc)&ZydisFormatterPrintMnemonic; ZydisFormatterSetHook(&formatter, ZYDIS_FORMATTER_HOOK_PRINT_MNEMONIC, (const void**)&defaultPrintMnemonic); defaultFormatOperandImm = (ZydisFormatterOperandFunc)&ZydisFormatterFormatOperandImm; ZydisFormatterSetHook(&formatter, ZYDIS_FORMATTER_HOOK_FORMAT_OPERAND_IMM, (const void**)&defaultFormatOperandImm); } uint64_t instructionPointer = 0x007FFFFFFF400000; ZydisDecodedInstruction instruction; ZydisCustomUserData userData; char buffer[256]; while (ZYDIS_SUCCESS( ZydisDecoderDecodeBuffer(decoder, data, length, instructionPointer, &instruction))) { data += instruction.length; length -= instruction.length; instructionPointer += instruction.length; printf("%016" PRIX64 " ", instruction.instrAddress); ZydisFormatterFormatInstructionEx( &formatter, &instruction, &buffer[0], sizeof(buffer), &userData); printf(" %s\n", &buffer[0]); } } /* ============================================================================================== */ /* Entry point */ /* ============================================================================================== */ int main() { if (ZydisGetVersion() != ZYDIS_VERSION) { fputs("Invalid zydis version\n", stderr); return EXIT_FAILURE; } uint8_t data[] = { // cmpps xmm1, xmm4, 0x03 0x0F, 0xC2, 0xCC, 0x03, // vcmppd xmm1, xmm2, xmm3, 0x17 0xC5, 0xE9, 0xC2, 0xCB, 0x17, // vcmpps k2 {k7}, zmm2, dword ptr ds:[rax + rbx*4 + 0x100] {1to16}, 0x0F 0x62, 0xF1, 0x6C, 0x5F, 0xC2, 0x54, 0x98, 0x40, 0x0F }; ZydisDecoder decoder; ZydisDecoderInit(&decoder, ZYDIS_MACHINE_MODE_LONG_64, ZYDIS_ADDRESS_WIDTH_64); disassembleBuffer(&decoder, &data[0], sizeof(data), ZYDIS_FALSE); puts(""); disassembleBuffer(&decoder, &data[0], sizeof(data), ZYDIS_TRUE); return 0; } /* ============================================================================================== */