1 // All rights reserved. 2 // 3 // Redistribution and use in source and binary forms, with or without 4 // modification, are permitted provided that the following conditions are 5 // met: 6 // 7 // * Redistributions of source code must retain the above copyright 8 // notice, this list of conditions and the following disclaimer. 9 // * Redistributions in binary form must reproduce the above 10 // copyright notice, this list of conditions and the following disclaimer 11 // in the documentation and/or other materials provided with the 12 // distribution. 13 // * Neither the name of Google Inc. nor the names of its 14 // contributors may be used to endorse or promote products derived from 15 // this software without specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 29 // disassembler_x86.h: Basic x86 bytecode disassembler 30 // 31 // Provides a simple disassembler which wraps libdisasm. This allows simple 32 // tests to be run against bytecode to test for various properties. 33 // 34 // Author: Cris Neckar 35 36 #ifndef GOOGLE_BREAKPAD_PROCESSOR_DISASSEMBLER_X86_H_ 37 #define GOOGLE_BREAKPAD_PROCESSOR_DISASSEMBLER_X86_H_ 38 39 #include <stddef.h> 40 #include <sys/types.h> 41 42 #include "google_breakpad/common/breakpad_types.h" 43 44 namespace libdis { 45 #include "third_party/libdisasm/libdis.h" 46 } 47 48 namespace google_breakpad { 49 50 enum { 51 DISX86_NONE = 0x0, 52 DISX86_BAD_BRANCH_TARGET = 0x1, 53 DISX86_BAD_ARGUMENT_PASSED = 0x2, 54 DISX86_BAD_WRITE = 0x4, 55 DISX86_BAD_BLOCK_WRITE = 0x8, 56 DISX86_BAD_READ = 0x10, 57 DISX86_BAD_BLOCK_READ = 0x20, 58 DISX86_BAD_COMPARISON = 0x40 59 }; 60 61 class DisassemblerX86 { 62 public: 63 // TODO(cdn): Modify this class to take a MemoryRegion instead of just 64 // a raw buffer. This will make it easier to use this on arbitrary 65 // minidumps without first copying out the code segment. 66 DisassemblerX86(const uint8_t *bytecode, uint32_t, uint32_t); 67 ~DisassemblerX86(); 68 69 // This walks to the next instruction in the memory region and 70 // sets flags based on the type of instruction and previous state 71 // including any registers marked as bad through setBadRead() 72 // or setBadWrite(). This method can be called in a loop to 73 // disassemble until the end of a region. 74 uint32_t NextInstruction(); 75 76 // Indicates whether the current disassembled instruction was valid. currentInstructionValid()77 bool currentInstructionValid() { return instr_valid_; } 78 79 // Returns the current instruction as defined in libdis.h, 80 // or NULL if the current instruction is not valid. currentInstruction()81 const libdis::x86_insn_t* currentInstruction() { 82 return instr_valid_ ? ¤t_instr_ : NULL; 83 } 84 85 // Returns the type of the current instruction as defined in libdis.h. currentInstructionGroup()86 libdis::x86_insn_group currentInstructionGroup() { 87 return current_instr_.group; 88 } 89 90 // Indicates whether a return instruction has been encountered. endOfBlock()91 bool endOfBlock() { return end_of_block_; } 92 93 // The flags set so far for the disassembly. flags()94 uint16_t flags() { return flags_; } 95 96 // This sets an indicator that the register used to determine 97 // src or dest for the current instruction is tainted. These can 98 // be used after examining the current instruction to indicate, 99 // for example that a bad read or write occurred and the pointer 100 // stored in the register is currently invalid. 101 bool setBadRead(); 102 bool setBadWrite(); 103 104 protected: 105 const uint8_t *bytecode_; 106 uint32_t size_; 107 uint32_t virtual_address_; 108 uint32_t current_byte_offset_; 109 uint32_t current_inst_offset_; 110 111 bool instr_valid_; 112 libdis::x86_insn_t current_instr_; 113 114 // TODO(cdn): Maybe also track an expression's index register. 115 // ex: mov eax, [ebx + ecx]; ebx is base, ecx is index. 116 bool register_valid_; 117 libdis::x86_reg_t bad_register_; 118 119 bool pushed_bad_value_; 120 bool end_of_block_; 121 122 uint16_t flags_; 123 }; 124 125 } // namespace google_breakpad 126 127 #endif // GOOGLE_BREAKPAD_PROCESSOR_DISASSEMBLER_X86_H_ 128