binexport2.proto

// Copyright 2011-2024 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// This file describes a compact representation for disassembled binaries. It is
// loosely based on the PostgreSQL database schema used by BinNavi's
// postgresql_tables.sql (https://git.io/vzlYw).
// It is the output format for the BinExport IDA plugin and the BinDetego
// disassembler and consumed by the BinDiff comparison engine.

// The representation is generic to accommodate various source architectures.
// In particular 32 and 64 bit versions of x86, ARM, PowerPC and MIPS have been
// tested.
//
// Multiple levels of deduping have been applied to make the format more compact
// and avoid redundant data duplication. Some of this due to hard-earned
// experience trying to cope with intentionally obfuscated malicious binaries.
// Note in particular that the same instruction may occur in multiple basic
// blocks and the same basic block in multiple functions (instruction and basic
// block sharing). Implemented naively, malware can use this to cause
// combinatorial explosion in memory usage, DOSing the analyst. This format
// should store every unique expression, mnemonic, operand, instruction and
// basic block only once instead of duplicating the information for every
// instance of it.
//
// This format does _not_ try to be 100% backwards compatible with the old
// version. In particular, we do not store IDA's comment types, making lossless
// porting of IDA comments impossible. We do however, store comments and
// expression substitutions, so porting the actual data is possible, just not
// the exact IDA type.
//
// While it would be more natural to use addresses when defining call graph and
// flow graph edges and other such references, it is more efficient to employ
// one more level of indirection and use indices into the basic block or
// function arrays instead. This is because addresses will usually use most of
// the available 64 bit space while indices will be much smaller and compress
// much better (less randomly distributed).
//
// We omit all fields that are set to their default value anyways. Note that
// this has two side effects:
//   - changing the defaults in this proto file will, in effect, change what's
//     read from disk
//   - the generated code has_* methods are somewhat less useful
// WARNING: We omit the defaults manually in the code writing the data. Do not
//          change the defaults here without changing the code!
//
// TODO(cblichmann): Link flow graphs to call graph nodes. The connection is
//                   there via the address, but tricky to extract.

syntax = "proto2";

option java_package = "com.google.security.zynamics";
option java_outer_classname = "BinExport";

message BinExport2 {
  message Meta {
    reserved 5;  // Pre-BinDiff 4.3 padding

    // Input binary filename including file extension but excluding file path.
    // example: "insider_gcc.exe"
    optional string executable_name = 1;

    // Application defined executable id. Often the SHA256 hash of the input
    // binary.
    optional string executable_id = 2;

    // Input architecture name, e.g. x86-32.
    optional string architecture_name = 3;

    // When did this file get created? Unix time. This may be used for some
    // primitive versioning in case the file format ever changes.
    optional int64 timestamp = 4;
  }

  message CallGraph {
    message Vertex {
      enum Type {
        // Regular function with full disassembly.
        NORMAL = 0;

        // This function is a well known library function.
        LIBRARY = 1;

        // Imported from a dynamic link library (e.g. dll).
        IMPORTED = 2;

        // A thunk function, forwarding its work via an unconditional jump.
        THUNK = 3;

        // An invalid function (a function that contained invalid code or was
        // considered invalid by some heuristics).
        INVALID = 4;
      }

      // The function's entry point address. Messages need to be sorted, see
      // comment below on `vertex`.
      optional uint64 address = 1;
      optional Type type = 2 [default = NORMAL];

      // If the function has a user defined, real name it will be given here.
      // main() is a proper name, sub_BAADF00D is not (auto generated dummy
      // name).
      optional string mangled_name = 3;

      // Demangled name if the function is a mangled C++ function and we could
      // demangle it.
      optional string demangled_name = 4;

      // If this is a library function, what is its index in library arrays.
      optional int32 library_index = 5;

      // If module name, such as class name for DEX files, is present - index in
      // module table.
      optional int32 module_index = 6;
    }

    message Edge {
      // source and target index into the vertex repeated field.
      optional int32 source_vertex_index = 1;
      optional int32 target_vertex_index = 2;
    }

    // vertices == functions in the call graph.
    // Important: Most downstream tooling (notably BinDiff), need these to be
    //            sorted by `Vertex::address` (ascending). For C++, the
    //            `BinExport2Writer` class enforces this invariant.
    repeated Vertex vertex = 1;

    // edges == calls in the call graph.
    repeated Edge edge = 2;
  }

  // An operand consists of 1 or more expressions, linked together as a tree.
  message Expression {
    enum Type {
      SYMBOL = 1;
      IMMEDIATE_INT = 2;
      IMMEDIATE_FLOAT = 3;
      OPERATOR = 4;
      REGISTER = 5;
      SIZE_PREFIX = 6;
      DEREFERENCE = 7;
    }

    // IMMEDIATE_INT is by far the most common type and thus we can save some
    // space by omitting it as the default.
    optional Type type = 1 [default = IMMEDIATE_INT];

    // Symbol for this expression. Interpretation depends on type. Examples
    // include: "eax", "[", "+"
    optional string symbol = 2;

    // If the expression can be interpreted as an integer value (IMMEDIATE_INT)
    // the value is given here.
    optional uint64 immediate = 3;

    // The parent expression. Example expression tree for the second operand of:
    // mov eax, b4 [ebx + 12]
    // "b4" --- "[" --- "+" --- "ebx"
    //                       \  "12"
    optional int32 parent_index = 4;

    // true if the expression has entry in relocation table
    optional bool is_relocation = 5;
  }

  // An instruction may have 0 or more operands.
  message Operand {
    // Contains all expressions constituting this operand. All expressions
    // should be linked into a single tree, i.e. there should only be one
    // expression in this list with parent_index == NULL and all others should
    // descend from that. Rendering order for expressions on the same tree level
    // (siblings) is implicitly given by the order they are referenced in this
    // repeated field.
    // Implicit: expression sequence
    repeated int32 expression_index = 1;
  }

  // An instruction has exactly 1 mnemonic.
  message Mnemonic {
    // Literal representation of the mnemonic, e.g.: "mov".
    optional string name = 1;
  }

  message Instruction {
    // This will only be filled for instructions that do not just flow from the
    // immediately preceding instruction. Regular instructions will have to
    // calculate their own address by adding raw_bytes.size() to the previous
    // instruction's address.
    optional uint64 address = 1;

    // If this is a call instruction and call targets could be determined
    // they'll be given here. Note that we may or may not have a flow graph for
    // the target and thus cannot use an index into the flow graph table here.
    // We could potentially use call graph nodes, but linking instructions to
    // the call graph directly does not seem a good choice.
    repeated uint64 call_target = 2;

    // Index into the mnemonic array of strings. Used for de-duping the data.
    // The default value is used for the most common mnemonic in the executable.
    optional int32 mnemonic_index = 3 [default = 0];

    // Indices into the operand tree. On X86 this can be 0, 1 or 2 elements
    // long, 3 elements with VEX/EVEX.
    // Implicit: operand sequence
    repeated int32 operand_index = 4;

    // The unmodified input bytes corresponding to this instruction.
    optional bytes raw_bytes = 5;

    // Implicit: comment sequence
    repeated int32 comment_index = 6;
  }

  message BasicBlock {
    // This is a space optimization. The instructions for an individual basic
    // block will usually be in a continuous index range. Thus it is more
    // efficient to store the range instead of individual indices. However, this
    // does not hold true for all basic blocks, so we need to be able to store
    // multiple index ranges per block.
    message IndexRange {
      // These work like begin and end iterators, i.e. the sequence is
      // [begin_index, end_index). If the sequence only contains a single
      // element end_index will be omitted.
      optional int32 begin_index = 1;
      optional int32 end_index = 2;
    }

    // Implicit: instruction sequence
    repeated IndexRange instruction_index = 1;
  }

  message FlowGraph {
    message Edge {
      enum Type {
        CONDITION_TRUE = 1;
        CONDITION_FALSE = 2;
        UNCONDITIONAL = 3;
        SWITCH = 4;
      }

      // Source instruction will always be the last instruction of the source
      // basic block, target instruction the first instruction of the target
      // basic block.
      optional int32 source_basic_block_index = 1;
      optional int32 target_basic_block_index = 2;
      optional Type type = 3 [default = UNCONDITIONAL];

      // Indicates whether this is a loop edge as determined by Lengauer-Tarjan.
      optional bool is_back_edge = 4 [default = false];
    }

    // Basic blocks are sorted by address.
    repeated int32 basic_block_index = 1;

    // The flow graph's entry point address is the first instruction of the
    // entry_basic_block.
    optional int32 entry_basic_block_index = 3;

    repeated Edge edge = 2;
  }

  // Generic reference class used for address comments (deprecated), string
  // references and expression substitutions. It allows referencing from an
  // instruction, operand, expression subtree tuple to a de-duped string in the
  // string table.
  message Reference {
    // Index into the global instruction table.
    optional int32 instruction_index = 1;

    // Index into the operand array local to an instruction.
    optional int32 instruction_operand_index = 2 [default = 0];

    // Index into the expression array local to an operand.
    optional int32 operand_expression_index = 3 [default = 0];

    // Index into the global string table.
    optional int32 string_table_index = 4;
  }

  message DataReference {
    // Index into the global instruction table.
    optional int32 instruction_index = 1;

    // Address being referred.
    optional uint64 address = 2;
  }

  message Comment {
    enum Type {
      // A regular instruction comment. Typically displayed next to the
      // instruction disassembly.
      DEFAULT = 0;

      // A comment line that is typically displayed before (above) the
      // instruction it refers to.
      ANTERIOR = 1;

      // Like ANTERIOR, but a typically displayed after (below).
      POSTERIOR = 2;

      // Similar to an ANTERIOR comment, but applies to the beginning of an
      // identified function. Programs displaying the proto may choose to render
      // these differently (e.g. above an inferred function signature).
      FUNCTION = 3;

      // Named constants, bitfields and similar.
      ENUM = 4;

      // Named locations, usually the target of a jump.
      LOCATION = 5;

      // Data cross references.
      GLOBAL_REFERENCE = 6;

      // Local/stack variables.
      LOCAL_REFERENCE = 7;
    }

    // Index into the global instruction table. This is here to enable
    // comment processing without having to iterate over all instructions.
    // There is an N:M mapping of instructions to comments.
    optional int32 instruction_index = 1;

    // Index into the operand array local to an instruction.
    optional int32 instruction_operand_index = 2 [default = 0];

    // Index into the expression array local to an operand, like in Reference.
    // This is not currently used, but allows to implement expression
    // substitutions.
    optional int32 operand_expression_index = 3 [default = 0];

    // Index into the global string table.
    optional int32 string_table_index = 4;

    // Comment is propagated to all locations that reference the original
    // location.
    optional bool repeatable = 5;

    optional Type type = 6 [default = DEFAULT];
  }

  message Section {
    // Section start address.
    optional uint64 address = 1;

    // Section size.
    optional uint64 size = 2;

    // Read flag of the section, True when section is readable.
    optional bool flag_r = 3;

    // Write flag of the section, True when section is writable.
    optional bool flag_w = 4;

    // Execute flag of the section, True when section is executable.
    optional bool flag_x = 5;
  }

  message Library {
    // If this library is statically linked.
    optional bool is_static = 1;

    // Address where this library was loaded, 0 if unknown.
    optional uint64 load_address = 2 [default = 0];

    // Name of the library (format is platform-dependent).
    optional string name = 3;
  }

  message Module {
    // Name, such as Java class name. Platform-dependent.
    optional string name = 1;
  }

  optional Meta meta_information = 1;
  repeated Expression expression = 2;
  repeated Operand operand = 3;
  repeated Mnemonic mnemonic = 4;
  repeated Instruction instruction = 5;
  repeated BasicBlock basic_block = 6;
  repeated FlowGraph flow_graph = 7;
  optional CallGraph call_graph = 8;

  repeated string string_table = 9;

  // No longer written. This is here so that BinDiff can work with older
  // BinExport files.
  repeated Reference address_comment = 10 [deprecated = true];

  // Rich comment index used for BinDiff's comment porting.
  repeated Comment comment = 17;
  repeated Reference string_reference = 11;
  repeated Reference expression_substitution = 12;
  repeated Section section = 13;

  repeated Library library = 14;
  repeated DataReference data_reference = 15;
  repeated Module module = 16;

  // Allow for future extensions.
  extensions 100000000 to max;
}