diff --git a/docs/source/tutorials/options.md b/docs/source/tutorials/options.md index 1fa675d0b..b1c2315b3 100644 --- a/docs/source/tutorials/options.md +++ b/docs/source/tutorials/options.md @@ -140,6 +140,8 @@ It defaults to `false`. For example, when set to `true`, a blank string would ev **ownPropertyOnly** hides scope variables from prototypes, useful when you're passing a not sanitized object into LiquidJS or need to hide prototypes from templates. Defaults to `true`. +Built-in DoS limits and host isolation guidance are documented in [Security Model](./security-model.html). + {% note info Nonexistent Tags %} Nonexistent tags always throw errors during parsing and this behavior cannot be customized. {% endnote %} diff --git a/docs/source/tutorials/security-model.md b/docs/source/tutorials/security-model.md index b0658b359..329627bcf 100644 --- a/docs/source/tutorials/security-model.md +++ b/docs/source/tutorials/security-model.md @@ -4,20 +4,17 @@ title: Security Model LiquidJS provides DoS-oriented limits (`parseLimit`, `templateLimit`, `outputLengthLimit`, `maxDepth`) to reduce risk. This page summarizes those limits, [`ownPropertyOnly`][ownPropertyOnly], custom [`Drop`][drop] usage, and the security boundary to assume in production. -## Security boundary +## At a glance -The built-in limits are cooperative safeguards, not strict runtime isolation. - -- They do **not** equal process RSS/heap usage. -- They do **not** sandbox JavaScript execution. -- They should be combined with process/container limits and request timeouts for defense in depth. - -## Limits at a glance +LiquidJS ships a thin cooperative DoS layer: - [parseLimit][parseLimit]: limit total template size per `parse()` call. - [templateLimit][templateLimit]: limit total tag/HTML/output nodes rendered per `render()` call. - [outputLengthLimit][outputLengthLimit]: limit total output length per `render()` call. - [maxDepth][maxDepth]: limit nesting depth of `{% render %}`, `{% include %}`, and `{% layout %}`. +- Strftime numeric pad widths in the `date` filter are capped at `1_000_000` (1M) per conversion. + +These are cooperative safeguards, not runtime isolation—see [Production guidance](#production-guidance) below for host-level limits and online-service hardening. ## Limit details @@ -49,7 +46,7 @@ Each template node (the `for` tag, literal `order: `, output `{{i}}`, and so on) [maxDepth][maxDepth] limits how deeply `{% render %}`, `{% include %}`, and `{% layout %}` can nest. Defaults to `128`. In sync rendering (`renderSync`), nested tags are driven by `toValueSync`, which recursively resumes each yielded generator on the call stack—deep nesting can overflow it, and `maxDepth` caps that depth. Async `render()` resumes the same tag generators via `toPromise`/`yield` without a deep synchronous call chain, so stack overflow is not a concern there (the limit still applies as a DoS guard). -The `memoryLimit` option was removed; memory usage is not capped in-engine. +The `memoryLimit` option was removed in v11; enforce memory limits at the host or process level instead. ## `ownPropertyOnly` and scope data @@ -59,15 +56,22 @@ With [`ownPropertyOnly`][ownPropertyOnly] `true`, plain scope objects only expos [`Drop`][drop] values are not restricted the same way: LiquidJS still reads the prototype chain and may call [`liquidMethodMissing`][liquidMethodMissing]. **You** control what a drop exposes; narrow APIs and never feed unsafe data into drops unless the class is built for template access. `ownPropertyOnly` alone does not harden custom drops—audit them like any privileged code. -## Online service guidance +## Production guidance -If you run an online service, avoid rendering fully user-defined templates whenever possible. +LiquidJS does not sandbox template code—custom filters, tags, and scope helpers run as ordinary JavaScript with your process privileges. For production with untrusted templates, treat built-in DoS limits as one layer in a broader strategy. -- Prefer curated templates or a restricted template subset. -- If user-defined templates are required, isolate rendering (worker/process/container), enforce OS/container memory and CPU limits, and apply request rate limits. -- Treat `parseLimit`, `templateLimit`, `outputLengthLimit`, and `maxDepth` as one layer in a broader DoS defense strategy. +Host-level defenses: -For heavy single-template operations, process-level isolation is still recommended (for example with [paralleljs][paralleljs]). +- Run each render in a **worker thread or child process** with a wall-clock timeout; **kill** the worker on expiry. +- Enforce **container/Kubernetes cgroup limits**, `ulimit`, or equivalent on the renderer process for memory and CPU. +- Apply **request rate limits** at the API or gateway layer. +- **`node:vm` and `isolated-vm` are not a security boundary** for LiquidJS: custom filters and tags run ordinary host JavaScript with your privileges. +- Unlike Jinja/Twig sandbox modes, LiquidJS has **no restricted interpreter**—template logic executes in the same JS runtime as your app. + +For online services that accept template input: + +- Avoid rendering fully user-defined templates whenever possible; prefer curated templates or a restricted template subset. +- For heavy single-template operations, process-level isolation is still recommended (for example with [paralleljs][paralleljs]). [paralleljs]: https://www.npmjs.com/package/paralleljs [parseLimit]: /api/interfaces/LiquidOptions.html#parseLimit diff --git a/src/util/strftime.spec.ts b/src/util/strftime.spec.ts index b629b6d98..9de7731ba 100644 --- a/src/util/strftime.spec.ts +++ b/src/util/strftime.spec.ts @@ -188,6 +188,14 @@ describe('util/strftime', function () { it('should have higher priority than H', () => { expect(t(then, '%0H')).toBe('03') }) + it('should allow pad width up to MAX_STRFTIME_PAD', () => { + expect(t(now, '%100000d').length).toBe(100000) + expect(t(now, `%${1_000_000}d`).length).toBe(1_000_000) + }) + it('should throw when pad width exceeds MAX_STRFTIME_PAD', () => { + expect(() => t(now, `%${1024 * 1024 + 1}d`)).toThrow('strftime pad width limit exceeded') + expect(() => t(now, '%5000000d')).toThrow('strftime pad width limit exceeded') + }) }) describe('modifier field', () => { it('should ignore E modifier', () => { diff --git a/src/util/strftime.ts b/src/util/strftime.ts index 732b50dd1..9a97857bb 100644 --- a/src/util/strftime.ts +++ b/src/util/strftime.ts @@ -1,5 +1,9 @@ import { changeCase, padStart, padEnd } from './underscore' import { LiquidDate } from './liquid-date' +import { assert } from './assert' + +/** Per-conversion numeric width cap for strftime (%N, %15d, …). */ +export const MAX_STRFTIME_PAD = 1024 * 1024 const rFormat = /%([-_0^#:]+)?(\d+)?([EO])?(.)/ interface FormatOptions { @@ -96,6 +100,7 @@ const formatCodes: Record = { M: (d: LiquidDate) => d.getMinutes(), N: (d: LiquidDate, opts: FormatOptions) => { const width = Number(opts.width) || 9 + assertPadWidth(width) const str = String(d.getMilliseconds()).slice(0, width) return padEnd(str, width, '0') }, @@ -132,6 +137,10 @@ export function strftime (d: LiquidDate, formatStr: string) { return output + remaining } +function assertPadWidth (width: number) { + assert(width <= MAX_STRFTIME_PAD, 'strftime pad width limit exceeded') +} + function format (d: LiquidDate, match: RegExpExecArray) { const [input, flagStr = '', width, modifier, conversion] = match const convert = formatCodes[conversion] @@ -146,5 +155,6 @@ function format (d: LiquidDate, match: RegExpExecArray) { if (flags['_']) padChar = ' ' else if (flags['0']) padChar = '0' if (flags['-']) padWidth = 0 + else assertPadWidth(padWidth) return padStart(ret, padWidth, padChar) } diff --git a/test/integration/filters/date.spec.ts b/test/integration/filters/date.spec.ts index 3d3a683d4..f36090561 100644 --- a/test/integration/filters/date.spec.ts +++ b/test/integration/filters/date.spec.ts @@ -210,6 +210,16 @@ describe('filters/date', function () { const out = liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%5000d' }) expect(out.length).toBe(5000) }) + it('should honor large numeric strftime pad width up to the cap', () => { + const liquid = new Liquid() + const out = liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%100000d' }) + expect(out.length).toBe(100000) + }) + it('should throw when numeric strftime pad width is too large', () => { + const liquid = new Liquid() + expect(() => liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%5000000d' })) + .toThrow('strftime pad width limit exceeded') + }) }) }) describe('filters/date_to_xmlschema', function () {