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Ivan Gotovchits edited this page Dec 18, 2014 · 31 revisions

Abstract

This documents describes Binary Analysis Platform (BAP) library public API. The current state of the document is draft. Everything can be changed without further notice.

Table Of Contents

Introduction

This is a draft for a public API for BAP Server. The BAP server is an application that can provide BAP as a service to the third party applications, written in any language. We will refer to a BAP server as SERVER, and to third party application as a CLIENT. This document describes only the application protocol, the underlying transport protocol is out of the scope of the document.

Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 .

Transport Layer

Transport Layer is used to deliver messages and data. Different transport layers may be used to deliver different data. For example, while requests and responses may be delivered using http, data maybe delivered using ZMQ, network sockets or file system. Data is referenced using Uniform Resource Identifiers uri.

Uri must fully identify the contents of the file, i.e., two objects with the same uri must have the same data.

Resources

BAP Server performs analysis of binary data. The data can be represented as files, memory chunks. The latter can also have some meta data associated with it. To abstract this BAP Server uses resource object. Each resource denotes some existent block of binary data. Each resource is identified by its id. Client can add new resources to Server environment, using load-file or load-memory-chunk commands. The resources can be queried using get-resource command.

Uploading Resource Data

To upload some resource to Server, Client must use load-file or load-memory-chunk commands. This commands contain an URL to the data source. If the transport protocol of the URL is message oriented, then the resource data would be one message. If it is stream oriented, then all data would be obtained until the end of stream condition is met. For example, for resource specified by URL file:///bin/ls, all the file data would be read.

Downloading Resource Data

Every object describing particular resource contains a non empty set of URL that provides the resource data.

Image resource

Image resource represents a whole executable or library loaded into BAP Server environment. It can be loaded by Client with load-file command. Server may have additional images already loaded before the session start. The array of available images, is enumerated in images response to the init request. Image by itself, contains some meta data and also has links to symbols and sections resources, contained in it.

Section resource

Section is a contiguous region of memory belonging to some image and having some meta data associated with it. Sections can be added only by a particular in process of load-file command processing.

Symbol resource

Symbol is a non empty set of memory regions, that belongs to one artifact. The definition of the artifact is due to the particular container and programming language. But usually it is just a function. Symbols has some meta data associated with them, and also, can possibly have name.

Symbols are added by a particular loader in the process of load-file operation. Symbol is always associated with some section, and thus with an image.

Depending on platform or compiler, symbols can occupy a non-contiguous region of memory. In that case symbol resource will not served by itself, but should be retrieved by iterating over its memory regions. In other words, symbol will have links field if and only if it has one memory region.

Memory

Memory is a contiguous sequence of bytes, at the specified address. Memory can be associated with some section or symbol, but in general, it can have no associations. An arbitrary piece of code can be loaded into BAP Server with load-memory-chunk command.

Session

Session consists of a series of interactions. Each interaction must consist of at one request and at least one response. Request and response are messages. Client must be an initiator of the session. Client must not send responses, and server must not send requests. Server must send messages only in response to the client's requests. Server may send more than one response to one request.

Requests

The request should be a JSON object of the following schema:

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "title": "Request",
    "description": "A request from Client to Server",
    "type": "object",
    "properties": {
        "id" : {
            "description" : "unique for the client side identifier",
            "type" : "integer",
        },

        "init" : {
            "description" : "initialize session",
            "type" : {"$ref" : "#/definitions/init"}
        },

        "load-file" : {
            "description": "Loads specified file into BAP Server",
            "type" : {"$ref" : "#/definitions/load-file"},
        },

        "load-memory-chunk" : {
            "description": "Loads a piece of memory into BAP Server",
            "type" : {"$ref" : "#/definitions/load-memory-chunk"},
        },

        "get-insns" : {
            "description" : "Retrieve instructions from the resource",
            "type" : {"$ref" : "#/definitions/get-insns"}
        },

        "get-resource" : {
            "description" : "Request particular data from Server",
            "type" : "string"
        },
    },
    "required" : ["id"],
    "minProperties" : 1,
    "maxProperties" : 2,

    "definitions" : {
        "init"  : {
            "type" : "object",
            "properties" : {
                "version" : "string"
            }
        },
        "load-file" : {
            "type" : "object",
            "properties": {
                "url" : {
                    "description" : "url to the file data",
                    "type" : "string",
                    "format" : "uri",
                },

                "loader" : {
                    "description" : "force to use specified backend",
                    "type" : "string",
                }
            },
            "required" : ["url"]
        },

        "load-memory-chunk" : {
            "type": "object",
            "properties": {
                "url" : {
                    "description" : "url to them memory chunk",
                    "type" : "uri",
                },

                "arch" : {
                    "description" : "target architecture",
                    "type" : "string",
                },

                "address" : {
                    "description" : "virtual address of the first byte",
                    "type" : "int",
                    "default" : 0,
                },
                "endian" : {
                    "description" : "order of bytes in a memory word",
                    "type" : "string",
                    "format" : "ADT",
                    "oneOf"  : ["LittleEndian()", "BigEndian()"]
                },
            },
            "required" : ["url", "arch"],
        },


        "get-insns" : {
            "type": "object",
            "properties": {
                "resource" : {
                    "description" : "The identifier of the resource",
                    "type" : "string",
                },
                "stop-conditions" : {
                    "description" : "A set of stop conditions",
                    "type" : "array",
                    "minItems" : 1,
                    "uniqueItems" : true,
                    "items" : {
                        "type" : "string",
                        "format" : "ADT"
                    }
                }
            },
            "required" : ["resource"]
        }
    }
}

init

The init request is sent to initiate a session. Client must not send any requests before the init request.

Server must respond to this request with error or capabilities message.

If Server responded with error message the session is not started, and Client should either finish its interaction or send another init message.

load-file

The load-file request is sent to direct the server in order to load new executable or library. Server must respond to this request with either of this responses:

  • error
  • image resource

The file must be a properly encoded binary container in one of the supported formats, see capabilities. For loading raw binary chunks into bap see load-memory-chunk command. Despite the name load-file can point to any resource location.

Client may send several load-file or use-data request per session.

Example of the request:

{
    "id" : 12,
    "load-file" : {
        "url"    : "file:///bin/ls",
        "loader"  : "bap-elf",
    }
}

load-memory-chunk

The load-memory-chunk may be used if the calling side wants to provide an arbitrary data for analyzing. The data shouldn't contain any meta information, and it wouldn't be parsed as a binary container. Since no meta data exists, a client side must define an instruction set, using arch property.

The server must respond to this request with the error or memory resource responses.

Example:

{
    "id" : "15",
    "load-memory-chunk" : {
        "arch"    : "arm",
        "url"     : "zmq+ipc:/tmp/bap/15"
    }
}

get-insns

The get-insn command is used to retrieve instructions from the specified binary data.

The server must respond with insns or error messages. The server may still response with insns message even when the error has occurred.

Example:

{
    "id" : 17,
    "get-insns" : {
        "resource" : "24",
        "stop-conditions" : ["isCall()"]
    }
}

get-resource

This message allows Client to request information about arbitrary resource. Depending on the resource identified, Server must respond with either of the following messages:

  • error
  • image
  • memory
  • section
  • symbol

Responses

Response message must be a JSON object with the following schema:

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "title": "Response",
    "description": "A reply from Server to Client",
    "type": "object",
    "properties": {

        "id" : {
            "description" : "An id of the request to which we're replying",
            "type" : "string",
        },

        "error" : {
            "description" : "the request cannot be satisfied",
            "type" : {"$ref" : "#/definitions/error"}
        },

        "capabilities" : {
            "description" : "a set of capabilities supported by Server",
            "type" : {"$ref" : "#/definitions/capabilities"}
        },

        "image" : {
            "description" : "binary container description",
            "type" : {"$ref" : "#/definitions/image"}
        },

        "images" : {
            "description" : "the array of preloaded images",
            "uniqueItems" : true,
            "type" : {"$ref" : "#/definitions/ids"}
        },

        "symbols" : {
            "description" : "the array of symbols",
            "type" : {"$ref" : "#/definitions/ids"},
        },

        "symbol" : {"type" : {"$ref" : "#/definitions/symbol"}},

        "sections" : {
            "description" : "the array of sections",
            "type" : {"$ref" : "#/definitions/ids"}
        },

        "section" : {"type" : {"$ref" : "#/definitions/section"}},

        "insns" : {
            "description" : "the array of insns",
            "type" : "array",
            "minItems" : 1,
            "items" : {"$ref" : "#/definitions/insn"}
        },
    },
    "required" : ["id"],
    "minProperties" : 1,
    "maxProperties" : 2,

    "definitions" : {

        "error" : {
            "type" : "object",
            "properties" : {
                "description" : {"type" : "string"},
                "severity" : {
                    "type"  : "string",
                    "oneOf" : ["critical", "error", "warning"]
                }
            },
            "required" : ["description", "severity"]
        },

        "capabilities" : {
            "type" : "array",
            "minItems" : 1,
            "items" : {
                "type" : "object",
                "properties" : {
                    "version" : {
                        "description" : "protocol version",
                        "type" : "stringArray"
                    },
                    "loaders" : {
                        "description" : "a set of supported file loaders",
                        "type" : "array",
                        "minItems" : 1,
                        "uniqueItems" : true,
                        "items" : {"type" : {"$ref" : "#/definitions/loader"}}
                    },
                    "disassemblers" : {
                        "description" : "a set of supported disassemblers backend",
                        "type" : "array",
                        "minItems" : 1,
                        "uniqueItems" : true,
                        "items" : {"type" : {"$ref" : "#/definitions/disassembler"}}
                    },
                    "transports" : {
                        "description" : "Supported set of transport protocols",
                        "type" : "array",
                        "minItems" : 1,
                        "uniqueItems" : true,
                        "items" : {"type" : "string"}
                    }
                },
                "required" : ["version", "loaders", "disassemblers"]
            },
        },

        "resource" : {
            "type" : "object",
            "description" : "server resource",
            "properties" : {
                "id" : {
                    "description" : "unique resource identifier",
                    "type" : "string"
                },
                "links" : {
                    "description" : "a set of URL where the resource is available",
                    "type" : "array",
                    "minItems" : 1,
                    "uniqueItems" : true,
                    "items" : {"type" : "string", "format" : "uri"}
                }
            },
            "required" : ["id"]
        },

        "ids" : {
            "title" : "identifiers",
            "description" : "a list of resource identifiers",
            "type"  : "array",
            "items" : {
                "description" : "id of the resource",
                "type" : "string"
            },
            "uniqueItems" : true,
        },

        "memory" : {
            "type" : "object",
            "properties" : {
                "addr" : {"type" : "integer"},
                "size" : {"type" : "integer"},
                "section" : {"type" : "string"},
                "symbol"  : {"type" : "string"},
            },
            "additionalProperties" : {"$ref" : "#/definitions/resource"},
            "dependencies" : {
                "symbol" : "section"
            },
            "required" : ["addr", "size"],
        },

        "symbol" : {
            "type" : "object",
            "properties" : {
                "name" : { "type" : "string" },
                "is_function" : {"type" : "boolean"},
                "is_debug" : {"type" : "boolean"},
                "section" : {
                    "description" : "id of a section to which the symbol belongs",
                    "type" : "string"
                },

                "memory" : {"$ref" : "#/definitions/ids"},
            },
            "required" : ["memory", "is_function", "is_debug", "section"]
        },

        "section" : {
            "type" : "object",
            "properties" : {
                "name" : {"type" : "string"},
                "image": {"type" : "integer", "description" : "image id"},
                "off"  : {"type" : "integer", "description" : "offset in the image"},
                "perm" : {
                    "type" : "array",
                    "minItems" : 1,
                    "maxItems" : 3,
                    "uniqueItems" : true,
                    "items" : {"type" : "string", "oneOf" : ["r", "w", "x"]}
                },
                "memory" : {"type" : "integer", "description" : "memory id"},
            },
            "additionalProperties" : {"$ref" : "#/definitions/resource"},
            "required" : ["off", "perm", "memory", "image", "links"]
        },

        "image" : {
            "type" : "object",
            "properties" : {
                "file" : {"type" : "string", "description" : "associated file name"},
                "arch" : {"type" : "string"},
                "entry-point" : {"type" : "integer"},
                "addr-size" : {
                    "type" : "integer",
                    "oneOf" : [32, 64],
                },
                "endian" : {
                    "type" : "string",
                    "oneOf" : ["LittleEndian()", "BigEndian()"],
                    "format" : "ADT",
                },
                "sections" : {"$ref" : "#/definitions/ids"},
                "symbols"  : {"$ref" : "#/definitions/ids"},
            },
            "additionalProperties" : {"$ref" : "#/definitions/resource"},
            "required" : ["arch", "entry-point", "addr-size", "endian", "memory", "links"],
        },

        "insn" : {
            "type" : "object",
            "properties" : {
                "name" : {
                    "title" : "Instruction name",
                    "description" : "Name accroding to the disassembler backend in use",
                    "type" : "string",
                },

                "asm" : {
                    "description" : "Instruction representation in a target assembler",
                    "type" : "string"
                },

                "operands" : {
                    "description" : "An array of operators, according to the disassembler",
                    "type" : "array",
                    "minItems" : 0,
                    "items" : {"type" : "string", "format" : "ADT"}
                },

                "kinds" : {
                    "description" : "A set of kinds appropriate for the instruction",
                    "type" : "array",
                    "minItems" : 0,
                    "uniqueItems" : true,
                    "items" : {"type" : "string", "format" : "ADT"}
                },

                "target" : {
                    "title" : "Target Instruction",
                    "description" : "Target specific machine instruction",
                    "type" : "string",
                    "format" : "ADT",
                },

                "bil" : {
                    "description" : "BIL Instructions",
                    "type" : "array",
                    "minItems" : 0,
                    "items" : {"type" : "string", "format" : "ADT"}
                },
                "memory" : {
                    "description" : "Memory region occupied by an insn",
                    "type" : {"$ref" : "#/definitions/id"}
                }
            },

            "required" : ["name", "operands", "memory", "asm"],
            "dependencies" : {
                "bil" : "target",
            }
        },

        "loader" : {
            "description" : "Capabilities of binary container parser",
            "type" : "object",
            "properties" : {
                "name" : { "type" : "string"},
                "format" : {
                    "description" : "File format",
                    "type" : "string"
                },
                "architecture" : {
                    "description" : "Supported architecture",
                    "type" : "string",
                },
                "symbols" : {
                    "description" : "Capability to read symbol information",
                    "type" : "array",
                    "minItems" : 0,
                    "items" : {
                        "type" : "string",
                        "anyOf" : ["symtab", "debug"],
                    }
                }
            },
            "required" : ["name", "format", "architecture", "symbols"]
        },

        "disassembler" : {
            "description" : "capabilities of disassembler",
            "type" : "object",
            "properties" : {
                "name" : { "type" : "string"},
                "architecture" : {
                    "description" : "Disassembler instruction set",
                    "type" : "string",
                },
                "kinds" : {
                    "description" : "set of understandable kinds",
                    "type" : "array",
                    "items" : {"type" : "string"},
                    "minItems" : 1,
                    "uniqueItems" : true
                },
                "has-name" : {
                    "description" : "can provide instruction name",
                    "type" : "boolean",
                },
                "has-ops" : {
                    "description" : "can provide instruction operands",
                    "type" : "boolean",
                },
                "has-target" : {
                    "description" : "can provide lifted target instruction",
                    "type" : "boolean",
                },
                "has-bil" : {
                    "description" : "can provide BIL",
                    "type" : "boolean",
                },
            },
            "required" : [
                "name", "architecture", "kinds",
                "has-name", "has-ops", "has-target", "has-bil"
            ]
        }
    }
}

error

Server may use this message as a respond to any request. The description field shall contain a printable and human readable description of the occurred condition. The severity field values have the following meaning:

  • critical an unrecoverable error has occurred. All further request may contain invalid data or may be ignored. Client should start new session.

  • error the corresponding request cannot be satisfied. All following responses to the specified request should be discarded.

  • warning the corresponding request can not be satisfied to full extent. All other responses to the request may be considered valid.

capabilities

This message must be sent in response to the init request, if Server supports the requested protocol version. Otherwise Server must respond with an error. Message contains a description of features, that Server can provide to Client. Each set of features is tagged by a protocol version. Example:

{
    "id" : 0,
    "request" : 0,
    "capabilities" : [
        {
            "version" : "1.2.1-alpha",
            "loaders" : [
                {
                    "name" : "bap-elf",
                    "formats" : ["ELF"],
                    "architecture" : "386",
                    "symbols" : ["debug"]
                },
                {
                    "name" : "bap-elf",
                    "formats" : ["ELF"],
                    "architecture" : "ARM",
                    "symbols" : ["debug"]
                }
            ],
            "disassemblers" : [
                {
                    "name" : "llvm",
                    "architecture"  : "arm",
                    "kinds" : [
                        "Kind()", "Having_side_effects()",
                        "Affecting_control()", "Branch()",
                        "ConditionalBranch()", "UnconditionalBranch()",
                        "IndirectBranch()", "Return()", "Call()",
                        "Barrier()", "Terminator()", "May_affect_control_flow()",
                        "May_load()", "May_store()"
                    ],
                    "has-name" : true,
                    "has-ops" : true,
                    "has-target" : true,
                    "has-bil" : true,
                },
                {
                    "name" : "llvm",
                    "architecture"  : "x86",
                    "kinds" : [
                        "Kind()", "Having_side_effects()",
                        "Affecting_control()", "Branch()",
                        "ConditionalBranch()", "UnconditionalBranch()",
                        "IndirectBranch()", "Return()", "Call()",
                        "Barrier()", "Terminator()", "May_affect_control_flow()",
                        "May_load()", "May_store()"
                    ],
                    "has-name" : true,
                    "has-ops" : true,
                    "has-target" : false,
                    "has-bil" : false,
                }
            ],
            "transports" : ["ipc", "socket", "file"],

        }
    ]
}

image

This message must be sent in response to load-file command, if there're no error conditions of error or critical severity. It contains the most information about loaded file (aka, image).

{
    "id" : 128,
    "request" : 17,
    "image" : {
        "id" : "12123",
        "links" : ["file:///bin/ls"],
        "arch" : "ARM",
        "entry-point" : 40000000,
        "addr-size"  : 32,
        "endian" : "LittleEndian()",
        "sections" : ["12", "17"],
        "symbols" : ["114", "21"]
    }
}

symbol

An example of the symbol resource.

{
    "id"     : 3423,
    "request" : 12,
    "symbol" : {
        "id"   : "124",
        "links"  : [
            "mmap:///tmp/bap/2145/image_AF16DE?off=16343420&size16",
            "zmq+ipc:///tmp/bap/syms?id=124"
        ],
        "name" : "get_args",
        "memory" : ["17", "184"],
        "section" : "189",
        "is_function" : "true",
        "is_debug" : "true"
    }
}

section

Example of the section resource

{
    "id" : 34324,
    "request" : 12,
    "section" : {
        "id"   : "122344",
        "links": ["file:///tmp/bap/sec_12A34DF3"],
        "image": "12",
        "name" : "data",
        "perm" : ["r"],
        "off"  : 64,
        "memory" : "1253543",
    }
}

insns

This message must be send in response to disassemble command if no error conditions have occurred. Server may still send this message, if error condition have occurred. Server must send all instructions disassembled by the request in one message.

Example:

{
    "id"     : 4256,
    "request" : 17,
    "insns" : [
        {
            "name"  : "MOVi",
            "asm"   : "mov r0, #5",
            "ops"   : [ "Reg(\"R0\")", "Imm(5)", "Imm(14)", "Reg(\"Nil\")", "Reg(\"Nil\")"],
            "kinds" : ["Call()"],
            "target": "MOVi(Reg(R0()), Imm(Int(5,32)), Imm(Int(14,32)), Reg(Nil()), Reg(Nil()))",
            "bil"   : ["Move(Var('R0', Imm(32)), Int(5))"]
        }
    ]
}

ops items, target and bil uses ADT format to represent data.