Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

custom inspector for objects, fix #314 #315

Closed
wants to merge 17 commits into from
Closed

custom inspector for objects, fix #314 #315

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
17 commits
Select commit Hold shift + click to select a range
e55af8f
support host inspect
shigma Aug 10, 2020
a00b7d3
tweak for node 6
shigma Aug 10, 2020
d9c89d4
catch potential inspect error
shigma Aug 11, 2020
65d92f0
decontextify inspect arguments
shigma Aug 11, 2020
6d7dce7
contextify inspect arguments
shigma Aug 11, 2020
4ab2b63
add version restriction
shigma Aug 11, 2020
8e787c0
update exception handler
shigma Aug 12, 2020
31f0d00
add node 14
shigma Aug 12, 2020
b22876c
be aware of custom inspect in sandbox
shigma Aug 13, 2020
96d44cb
and we do not need version checks any more
shigma Aug 13, 2020
451330d
wrap instance operation in try-catch
shigma Aug 13, 2020
0448be5
tweak
shigma Aug 13, 2020
4d06c6b
fix lint
shigma Aug 13, 2020
c7bb595
just rule out custom inspect
shigma Aug 14, 2020
0d40782
fix lint
shigma Aug 14, 2020
fb24675
use host object.assign
shigma Aug 15, 2020
9466989
use host null proto object
shigma Aug 15, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions lib/contextify.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -199,6 +199,11 @@ Decontextify.instance = (instance, klass, deepTraps, flags, toStringTag) => {
if (key === '__lookupGetter__') return host.Object.prototype.__lookupGetter__;
if (key === '__lookupSetter__') return host.Object.prototype.__lookupSetter__;
if (key === host.Symbol.toStringTag && toStringTag) return toStringTag;
if (key === host.inspect.custom) {
return (depth, options) => {
return host.inspect(instance, options.showHidden, depth, options.colors);
Copy link
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is unsafe. The instance object is from the sandbox and is passed into the host function inspect. This can be used to escape the sandbox. Here custom implementations inside the sandbox are required.

Copy link
Contributor Author

@shigma shigma Aug 10, 2020 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm sorry. Can you please provide an example to escape?

Copy link
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Here you go:

const vm = new VM();
const code = '(' + function() {
    const customInspect = Symbol.for('nodejs.util.inspect.custom');
    Date.prototype[customInspect] = (depth, options) => {throw options.constructor.constructor('return process')()};
    return new Date();
}+')();';
const bad_object = vm.run(code);
console.log("Still good");
console.log(bad_object);
console.log("Logging is bad");

};
}

try {
return Decontextify.value(instance[key], null, deepTraps, flags);
Expand Down Expand Up @@ -979,6 +984,7 @@ BufferOverride.inspect = function inspect(recurseTimes, ctx) {
const LocalBuffer = global.Buffer = Contextify.readonly(host.Buffer, BufferMock);
Contextify.connect(host.Buffer.prototype.inspect, BufferOverride.inspect);

Proxy[host.inspect.custom] = () => '[Function: Proxy]';

const exportsMap = host.Object.create(null);
exportsMap.Contextify = Contextify;
Expand Down
2 changes: 2 additions & 0 deletions lib/main.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
const fs = require('fs');
const vm = require('vm');
const pa = require('path');
const {inspect} = require('util');
const {EventEmitter} = require('events');
const {INSPECT_MAX_BYTES} = require('buffer');
const helpers = require('./helpers.js');
Expand Down Expand Up @@ -1286,6 +1287,7 @@ const HOST = {
Set,
WeakSet,
Promise,
inspect,
Symbol,
INSPECT_MAX_BYTES,
VM,
Expand Down
57 changes: 57 additions & 0 deletions test/vm.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -280,6 +280,63 @@ describe('contextify', () => {
});
});

describe('inspect', () => {
let vm;

before(() => {
const sandbox = { inspect };
vm = new VM({ sandbox });
});

it('boxed primitives', () => {
assert.equal(inspect(vm.run('new Number(1)')), inspect(new Number(1)));
assert.equal(vm.run('inspect(new Number(1))'), inspect(new Number(1)));
assert.equal(inspect(vm.run('new String(1)')), inspect(new String(1)));
assert.equal(vm.run('inspect(new String(1))'), inspect(new String(1)));
assert.equal(inspect(vm.run('new Boolean(1)')), inspect(new Boolean(1)));
assert.equal(vm.run('inspect(new Boolean(1))'), inspect(new Boolean(1)));
});

it('other built-in objects', () => {
assert.equal(inspect(vm.run('Object')), inspect(Object));
assert.equal(vm.run('inspect(Object)'), inspect(Object));
assert.equal(inspect(vm.run('Function')), inspect(Function));
assert.equal(vm.run('inspect(Function)'), inspect(Function));
assert.equal(inspect(vm.run('Symbol')), inspect(Symbol));
assert.equal(vm.run('inspect(Symbol)'), inspect(Symbol));
assert.equal(inspect(vm.run('Reflect')), inspect(Reflect));
assert.equal(vm.run('inspect(Reflect)'), inspect(Reflect));
assert.equal(inspect(vm.run('Proxy')), inspect(Proxy));
assert.equal(vm.run('inspect(Proxy)'), inspect(Proxy));
assert.equal(inspect(vm.run('JSON')), inspect(JSON));
assert.equal(vm.run('inspect(JSON)'), inspect(JSON));
});

it('built-in instances', () => {
assert.equal(inspect(vm.run('new Date')).slice(0, -3), inspect(new Date).slice(0, -3));
assert.equal(vm.run('inspect(new Date)').slice(0, -3), inspect(new Date).slice(0, -3));
assert.equal(inspect(vm.run('new RegExp("^", "g")')), inspect(new RegExp('^', 'g')));
assert.equal(vm.run('inspect(new RegExp("^", "g"))'), inspect(new RegExp('^', 'g')));
assert.equal(inspect(vm.run('new Array(50)')), inspect(new Array(50)));
assert.equal(vm.run('inspect(new Array(50))'), inspect(new Array(50)));
assert.equal(inspect(vm.run('new Set([1])')), inspect(new Set([1])));
assert.equal(vm.run('inspect(new Set([1]))'), inspect(new Set([1])));
assert.equal(inspect(vm.run('new Map([[1, 2]])')), inspect(new Map([[1, 2]])));
assert.equal(vm.run('inspect(new Map([[1, 2]]))'), inspect(new Map([[1, 2]])));
assert.equal(inspect(vm.run('Promise.resolve(1)')), inspect(Promise.resolve(1)));
assert.equal(vm.run('inspect(Promise.resolve(1))'), inspect(Promise.resolve(1)));
});

it('other objects', () => {
const AsyncFunction = Object.getPrototypeOf(async () => {}).constructor;
const GeneratorFunction = Object.getPrototypeOf(function* f() {}).constructor;
assert.equal(inspect(vm.run('Object.getPrototypeOf(async () => {}).constructor')), inspect(AsyncFunction));
assert.equal(vm.run('inspect(Object.getPrototypeOf(async () => {}).constructor)'), inspect(AsyncFunction));
assert.equal(inspect(vm.run('Object.getPrototypeOf(function* f() {}).constructor')), inspect(GeneratorFunction));
assert.equal(vm.run('inspect(Object.getPrototypeOf(function* f() {}).constructor)'), inspect(GeneratorFunction));
});
});

describe('VM', () => {
let vm;

Expand Down