go-judge

README

go-judge

Executor Service

Architecture

Overall Architecture

+----------------------------------------------------------------------------------+
| Transport Layer (HTTP / WebSocket / FFI / ...)                                   |
+----------------------------------------------------------------------------------+
| Executor Worker                                                                  |
+-----------------------------------------------------------+----------------------+
| EnvExec + Environment Pool + Environment Builder          | File Store           |
+--------------------+----------------+---------------------+--------+-------+-----+
| Linux (go-sandbox) | Windows (winc) | macOS (app sandbox) | Memory | Local | ... |
+--------------------+----------------+---------------------+--------+-------+-----+

A rest service to run program in restricted environment and it is basically a wrapper for pkg/envexec to run single / multiple programs.

• /run POST execute program in the restricted environment
• /file GET list all cached file
• /file POST prepare a file in the executor service (in memory), returns fileId (can be referenced in /run parameter)
• /file/:fileId GET downloads file from executor service (in memory), returns file content
• /file/:fileId DELETE delete file specified by fileId
• /ws WebSocket for /run
• /metrics prometheus metrics (specifies METRICS=1 environment variable to enable metrics)
• /debug (specifies DEBUG=1 environment variable to enable go runtime debug endpoint)
• /version gets build git version (e.g. v0.6.4-1-g20d2815) together with runtime information (go version, os, platform)

Install & Run Developing Server

Install GO 1.13+ from download

go get github.com/criyle/go-judge/cmd/executorserver
sudo ~/go/bin/executorserver # or executorserver if $(GOPATH)/bin is in your $PATH

Or, by docker

docker run -it --rm --privileged -p 5050:5050 criyle/executorserver:demo

Build by your own docker build -t executorserver -f Dockerfile.exec .

The executorserver need root privilege to create cgroup. Either creates sub-directory /sys/fs/cgroup/cpuacct/go-judger, /sys/fs/cgroup/memory/go-judger, /sys/fs/cgroup/pids/go-judger and make execution user readable or use sudo to run it.

Command Line Arguments

• The default binding address for the executor server is :5050. Can be specified with -http flag.
• The default binding address for the gRPC executor server is :5051. Can be specified with -grpc flag. (Notice: need to set GRPC=1 environment variable to enable GRPC endpoint)
• The default concurrency is 4, Can be specified with -parallism flag.
• The default file store is in memory, local cache can be specified with -dir flag.
• The default log level is debug, use -silent to disable logs.
• -token to add token-based authentication to REST / gRPC
• -srcprefix to restrict src copyIn path (need to be absolute path)

Environment Variables

Environment variable will override command line arguments if they both present.

• The http binding address specifies as HTTP_ADDR=addr
• The grpc binding address specifies as GRPC_ADDR=addr
• The parallism specifies as PARALLISM=4
• The token specifies as TOKEN=token
• GRPC=1 enables gRPC
• METRICS=1 enables metrics
• DEBUG=1 enables debug

Build Shared object

Build container init cinit:

go build -o cinit ./cmd/cinit

Build executor_server.so:

go build -buildmode=c-shared -o executor_server.so ./cmd/ffi/

For example, in JavaScript, run with ffi-napi (seems node 14 is not supported yet):

Build Executor Proxy

Build go build ./cmd/executorproxy

Run ./executorproxy, connect to gRPC endpoint and offers REST endpoint.

Build Executor Shell

Build go build ./cmd/executorshell

Run ./executorshell, connect to gRPC endpoint with interactive shell.

Container Root Filesystem

• necessary lib / exec / compiler / header readonly bind mounted from current file system: /lib /lib64 /bin /usr
• work directory tmpfs mount: /w (work dir), /tmp (compiler temp files)

The following mounts point are examples that can be configured through config file later

• additional compiler scripts / exec readonly bind mounted: /c
• additional header readonly bind mounted: /i

Utilities

• pkg/envexec: run single / group of programs in parallel within restricted environment and resource constraints
• pkg/pool: reference implementation for Cgroup & Environment Pool

Windows Support

Build executorserver by:

go build ./cmd/executorserver/

Build executor_server.dll: (need to install gcc as well)

go build -buildmode=c-shared -o executor_server.so ./cmd/ffi/

Run: ./executorserver

Windows Security

• Resources are limited by JobObject
• Privillege are limited by Restricted Low Mandatory Level Token
• Low Mandatory Level directory is created for read / write

MacOS Support

Build executorserver by:

go build ./cmd/executorserver/

Build executor_server.dylib: (need to install XCode)

go build -buildmode=c-shared -o executor_server.dylib ./cmd/ffi/

Run: ./executorserver

MacOS Security

• sandbox-init profile deny network access and file read / write

Benchmark

By wrk with t.lua: Tested ~140-160 op/s macOS Docker Desktop & ~1100-1200 op/s Windows 10 WSL2.

wrk.method = "POST"
wrk.body   = '{"cmd":[{"args":["/bin/cat","a.hs"],"env":["PATH=/usr/bin:/bin"],"files":[{"content":""},{"name":"stdout","max":10240},{"name":"stderr","max":10240}],"cpuLimit":10000000000,"memoryLimit":104857600,"procLimit":50,"copyIn":{"a.hs":{"content":"main = putStrLn \\"Hello, World!\\""},"b":{"content":"TEST"}}}]}'
wrk.headers["Content-Type"] = "application/json;charset=UTF-8"

wrk -s t.lua -c 1 -t 1 -d 30s --latency http://localhost:5050/run

Running 30s test @ http://localhost:5050/run
  1 threads and 1 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     6.28ms    1.66ms  19.00ms   90.63%
    Req/Sec   160.60     23.15   200.00     83.33%
  Latency Distribution
     50%    5.89ms
     75%    6.57ms
     90%    7.53ms
     99%   14.21ms
  4810 requests in 30.05s, 1.19MB read
Requests/sec:    160.05
Transfer/sec:     40.59KB

TODO

• Github actions to auto build
• Configure mounts using YAML config file
• Investigate root-free running mechanism (no cgroup && not set uid / gid)
• Investigate RLimit settings (cpu, data, fsize, stack, noFile)
• Add WebSocket for job submission
• Windows support
• MacOS support
• GRPC + protobuf support
• Token-based authentication
• Prometheus metrics support

API interface

interface LocalFile {
    src: string; // absolute path for the file
}

interface MemoryFile {
    content: string | Buffer; // file contents
}

interface PreparedFile {
    fileId: string; // fileId defines file uploaded by /file
}

interface Pipe {
    name: string; // file name in copyOut
    max: number;  // maximum bytes to collect from pipe
}

interface Cmd {
    args: string[]; // command line argument
    env?: string[]; // environment

    // specifies file input / pipe collector for program file descriptors
    files?: (LocalFile | MemoryFile | PreparedFile | Pipe | null)[];
    tty?: boolean; // enables tty on the input and output pipes (should have just one input & one output)
    // Notice: must have TERM environment variables (e.g. TERM=xterm)

    // limitations
    cpuLimit?: number;     // ns
    realCpuLimit?: number; // ns
    memoryLimit?: number;  // byte
    stackLimit?: number;   // byte (N/A on windows, macOS cannot set over 32M)
    procLimit?: number;

    // copy the correspond file to the container dst path
    copyIn?: {[dst:string]:LocalFile | MemoryFile | PreparedFile};

    // copy out specifies files need to be copied out from the container after execution
    copyOut?: string[];
    // similar to copyOut but stores file in executor service and returns fileId, later download through /file/:fileId
    copyOutCached?: string[];
    // specifies the directory to dump container /w content
    copyOutDir: string
    // specifies the max file size to copy out
    copyOutMax: number; // byte
}

enum Status {
    Accepted,            // normal
    MemoryLimitExceeded, // mle
    TimeLimitExceeded,   // tle
    OutputLimitExceeded, // ole
    FileError,           // fe
    RuntimeError,        // re
    DangerousSyscall,    // dgs
    InternalError,       // system error
}

interface PipeIndex {
    index: number; // the index of cmd
    fd: number;    // the fd number of cmd
}

interface PipeMap {
    in: PipeIndex;  // input end of the pipe
    out: PipeIndex; // output end of the pipe
}

interface Request {
    requestId?: string; // for WebSocket requests
    cmd: Cmd[];
    pipeMapping: PipeMap[];
}

interface Result {
    status: Status;
    error?: string; // potential system error message
    time: number;   // ns (cgroup recorded time)
    memory: number; // byte
    runTime: number; // ns (wall clock time)
    // copyFile name -> content
    files?: {[name:string]:string};
    // copyFileCached name -> fileId
    fileIds?: {[name:string]:string};
}

// WebSocket results
interface WSResult {
    requestId: string;
    results: []Result;
    error?: string;
}

Example Request & Response

FFI:

var ffi = require('ffi-napi');

var executor_server = ffi.Library('./executor_server', {
    'Init': ['int', ['string']],
    'Exec': ['string', ['string']],
    'FileList': ['string', []],
    'FileAdd': ['string', ['string']],
    'FileGet': ['string', ['string']],
    'FileDelete': ['string', ['string']]
});

if (executor_server.Init(JSON.stringify({
    cinitPath: "/judge/cinit",
    parallism: 4,
}))) {
    console.log("Failed to init executor server");
}

const result = JSON.parse(executor_server.Exec(JSON.stringify({
    "cmd": [{
        "args": ["/bin/cat", "test.txt"],
        "env": ["PATH=/usr/bin:/bin"],
        "files": [{
            "content": ""
        }, {
            "name": "stdout",
            "max": 10240
        }, {
            "name": "stderr",
            "max": 10240
        }],
        "cpuLimit": 10000000000,
        "memoryLimit": 104857600,
        "procLimit": 50,
        "copyIn": {
            "test.txt": {
                "content": "TEST"
            }
        }
    }]
})));
console.log(result);

// Async
executor_server.Exec.async(JSON.stringify({
    "cmd": [{
        "args": ["/bin/cat", "test.txt"],
        "env": ["PATH=/usr/bin:/bin"],
        "files": [{
            "content": ""
        }, {
            "name": "stdout",
            "max": 10240
        }, {
            "name": "stderr",
            "max": 10240
        }],
        "cpuLimit": 10000000000,
        "memoryLimit": 104857600,
        "procLimit": 50,
        "copyIn": {
            "test.txt": {
                "content": "TEST"
            }
        }
    }]
}), (err, res) => {
    if (err) throw err;
    console.log(JSON.parse(res));
});

const fileAdd = (param) => new Promise((resolve, reject) => {
    executor_server.FileAdd.async(JSON.stringify(param), (err, res) => {
        if (err != null) { reject(err); } else { resolve(res); }
    });
});
const fileList = () => new Promise((resolve, reject) => {
    executor_server.FileList.async((err, res) => {
        if (err != null && res == null) { reject(err); } else { resolve(JSON.parse(res)); }
    });
});
const fileGet = (param) => new Promise((resolve, reject) => {
    executor_server.FileGet.async(JSON.stringify(param), (err, res) => {
        if (err != null && res == null) { reject(err); } else { resolve(res); }
    });
});
const fileDelete = (param) => new Promise((resolve, reject) => {
    executor_server.FileDelete.async(JSON.stringify(param), (err, res) => {
        if (err != null && res == null) { reject(err); } else { resolve(res); }
    });
});

const fileOps = async () => {
    const fileId = await fileAdd({ name: 'Name', content: 'Content' });
    console.log(fileId);
    const list = await fileList();
    console.log(list);
    const file = await fileGet({ id: fileId });
    console.log(file);
    const d = await fileDelete({ id: fileId });
    console.log(d);
    const e = await fileList();
    console.log(e);
};

fileOps();

Output:

{
  requestId: '',
  results: [
    {
      status: 'Accepted',
      exitStatus: 0,
      time: 814048,
      memory: 253952,
      files: [Object]
    }
  ]
}

Single (this example require apt install g++ inside the container):

{
    "cmd": [{
        "args": ["/usr/bin/g++", "a.cc", "-o", "a"],
        "env": ["PATH=/usr/bin:/bin"],
        "files": [{
            "content": ""
        }, {
            "name": "stdout",
            "max": 10240
        }, {
            "name": "stderr",
            "max": 10240
        }],
        "cpuLimit": 10000000000,
        "memoryLimit": 104857600,
        "procLimit": 50,
        "copyIn": {
            "a.cc": {
                "content": "#include <iostream>\nusing namespace std;\nint main() {\nint a, b;\ncin >> a >> b;\ncout << a + b << endl;\n}"
            }
        },
        "copyOut": ["stdout", "stderr"],
        "copyOutCached": ["a.cc", "a"],
        "copyOutDir": "1"
    }]
}

[
    {
        "status": "Accepted",
        "exitStatus": 0,
        "time": 303225231,
        "memory": 32243712,
        "runTime": 524177700,
        "files": {
            "stderr": "",
            "stdout": ""
        },
        "fileIds": {
            "a": "5LWIZAA45JHX4Y4Z",
            "a.cc": "NOHPGGDTYQUFRSLJ"
        }
    }
]

Multiple (interaction problem):

{
    "cmd": [{
        "args": ["/bin/cat", "1"],
        "env": ["PATH=/usr/bin:/bin"],
        "files": [{
            "content": ""
        }, null, {
            "name": "stderr",
            "max": 10240
        }],
        "cpuLimit": 1000000000,
        "memoryLimit": 1048576,
        "procLimit": 50,
        "copyIn": {
            "1": { "content": "TEST 1" }
        },
        "copyOut": ["stderr"]
    },
    {
        "args": ["/bin/cat"],
        "env": ["PATH=/usr/bin:/bin"],
        "files": [null, {
            "name": "stdout",
            "max": 10240
        }, {
            "name": "stderr",
            "max": 10240
        }],
        "cpuLimit": 1000000000,
        "memoryLimit": 1048576,
        "procLimit": 50,
        "copyOut": ["stdout", "stderr"]
    }],
    "pipeMapping": [{
        "in" : {"index": 0, "fd": 1 },
        "out" : {"index": 1, "fd" : 0 }
    }]
}

[
    {
        "status": "Accepted",
        "exitStatus": 0,
        "time": 1545123,
        "memory": 253952,
        "runTime": 4148800,
        "files": {
            "stderr": ""
        },
        "fileIds": {}
    },
    {
        "status": "Accepted",
        "exitStatus": 0,
        "time": 1501463,
        "memory": 253952,
        "runTime": 5897700,
        "files": {
            "stderr": "",
            "stdout": "TEST 1"
        },
        "fileIds": {}
    }
]

Compile On Windows (cygwin):

{
    "cmd": [{
        "args": ["C:\\Cygwin\\bin\\g++", "a.cc", "-o", "a"],
        "env": ["PATH=C:\\Cygwin\\bin;"],
        "files": [{
            "content": ""
        }, {
            "name": "stdout",
            "max": 10240
        }, {
            "name": "stderr",
            "max": 10240
        }],
        "cpuLimit": 10000000000,
        "memoryLimit": 104857600,
        "procLimit": 50,
        "copyIn": {
            "a.cc": {
                "content": "#include <iostream>\n#include <signal.h>\n#include <unistd.h>\nusing namespace std;\nint main() {\nint a, b;\ncin >> a >> b;\ncout << a + b << endl;\n}"
            }
        },
        "copyOutCached": ["a.exe"]
    }]
}

[
    {
        "status": "Accepted",
        "exitStatus": 0,
        "time": 140625000,
        "memory": 36286464,
        "files": {
            "stderr": "",
            "stdout": ""
        },
        "fileIds": {
            "a.exe": "HLQH2OF4MXUUJBCB"
        }
    }
]