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fix(gatsby-plugin-mdx): Do not leak frontmatter into page #35859

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91 changes: 91 additions & 0 deletions e2e-tests/mdx-less-babel/cypress/integration/frontmatter.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,91 @@
const page = {
js: `/frontmatter-js`,
javascript: `/frontmatter-javascript`,
yaml: `/frontmatter-yaml`,
json: `/frontmatter-json`,
graphqlQuery: `/frontmatter-graphql-query`,
}

// Attribute selector for element we assert against in pages
const selector = `[data-cy="frontmatter"]`

// Strings used for frontmatter titles
const titles = {
notParsed: `I should not be parsed`,
parsed: `I am parsed`,
}

// Frontmatter that should not be rendered
const otherKey = `Some other key`

describe(`webpack loader`, () => {
describe(`---yaml frontmatter`, () => {
beforeEach(() => {
cy.visit(page.yaml).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, titles.parsed)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})

describe(`---json frontmatter`, () => {
beforeEach(() => {
cy.visit(page.json).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, titles.parsed)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})

describe(`---js frontmatter`, () => {
beforeEach(() => {
cy.visit(page.js).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, `disabled`)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})

describe(`---javascript frontmatter`, () => {
beforeEach(() => {
cy.visit(page.javascript).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, `disabled`)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})
})

describe(`data layer`, () => {
it(`---js or ---javascript frontmatter should not parse by default`, () => {
cy.visit(page.graphqlQuery).waitForRouteChange()
cy.contains(titles.notParsed).should(`not.exist`)
})
})

it(`---js and ---javascript frontmatter should not allow remote code execution`, () => {
cy.readFile(`cypress/fixtures/file-to-attempt-rce-on.txt`).should(
`eq`,
`Nothing here, do not remove`
)
})
29 changes: 0 additions & 29 deletions e2e-tests/mdx-less-babel/cypress/integration/js-frontmatter.js

This file was deleted.

Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,15 @@
require(`fs`).writeFileSync(`${process.cwd()}/cypress/fixtures/file-to-attempt-rce-on.txt`, (new Error('Helpful stack trace if this does execute. It should not execute.')).stack)
console.trace()
return {
title: `I should not be parsed`
title: `I should not be parsed`,
otherKey: `Some other key`
}
})()

---

<h1>JS frontmatter engine is disabled by default</h1>

<span data-cy="js-frontmatter">
<span data-cy="frontmatter">
{props.pageContext.frontmatter?.title || `disabled`}
</span>
Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,15 @@
require(`fs`).writeFileSync(`${process.cwd()}/cypress/fixtures/file-to-attempt-rce-on.txt`, (new Error('Helpful stack trace if this does execute. It should not execute.')).stack)
console.trace()
return {
title: `I should not be parsed`
title: `I should not be parsed`,
otherKey: `Some other key`
}
})()

---

<h1>JS frontmatter engine is disabled by default</h1>

<span data-cy="js-frontmatter">
<span data-cy="frontmatter">
{props.pageContext.frontmatter?.title || `disabled`}
</span>
8 changes: 8 additions & 0 deletions e2e-tests/mdx-less-babel/src/pages/frontmatter-json.mdx
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
---json
{ "title": "I am parsed", "otherKey": "Some other key" }

---

<h1>A page with JSON frontmatter</h1>

<span data-cy="frontmatter">{props.pageContext.frontmatter?.title}</span>
9 changes: 9 additions & 0 deletions e2e-tests/mdx-less-babel/src/pages/frontmatter-yaml.mdx
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
---yaml
title: I am parsed
otherKey: Some other key

---

<h1>A page with YAML frontmatter</h1>

<span data-cy="frontmatter">{props.pageContext.frontmatter?.title}</span>
91 changes: 91 additions & 0 deletions e2e-tests/mdx/cypress/integration/frontmatter.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,91 @@
const page = {
js: `/frontmatter-js`,
javascript: `/frontmatter-javascript`,
yaml: `/frontmatter-yaml`,
json: `/frontmatter-json`,
graphqlQuery: `/frontmatter-graphql-query`,
}

// Attribute selector for element we assert against in pages
const selector = `[data-cy="frontmatter"]`

// Strings used for frontmatter titles
const titles = {
notParsed: `I should not be parsed`,
parsed: `I am parsed`,
}

// Frontmatter that should not be rendered
const otherKey = `Some other key`

describe(`webpack loader`, () => {
describe(`---yaml frontmatter`, () => {
beforeEach(() => {
cy.visit(page.yaml).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, titles.parsed)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})

describe(`---json frontmatter`, () => {
beforeEach(() => {
cy.visit(page.json).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, titles.parsed)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})

describe(`---js frontmatter`, () => {
beforeEach(() => {
cy.visit(page.js).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, `disabled`)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})

describe(`---javascript frontmatter`, () => {
beforeEach(() => {
cy.visit(page.javascript).waitForRouteChange()
})

it(`should parse`, () => {
cy.get(selector).invoke(`text`).should(`eq`, `disabled`)
})

it(`should not leak into the page`, () => {
cy.contains(otherKey).should(`not.exist`)
})
})
})

describe(`data layer`, () => {
it(`---js or ---javascript frontmatter should not parse by default`, () => {
cy.visit(page.graphqlQuery).waitForRouteChange()
cy.contains(titles.notParsed).should(`not.exist`)
})
})

it(`---js and ---javascript frontmatter should not allow remote code execution`, () => {
cy.readFile(`cypress/fixtures/file-to-attempt-rce-on.txt`).should(
`eq`,
`Nothing here, do not remove`
)
})
29 changes: 0 additions & 29 deletions e2e-tests/mdx/cypress/integration/js-frontmatter.js

This file was deleted.

30 changes: 30 additions & 0 deletions e2e-tests/mdx/src/pages/frontmatter-graphql-query.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
import React from "react"
import { graphql } from "gatsby"

export default function PageRunningGraphqlResolversOnJSFrontmatterTestInputs({
data,
}) {
return <pre>{JSON.stringify(data.allMdx.nodes, null, 2)}</pre>
}

export const query = graphql`
{
allMdx(filter: { slug: { glob: "frontmatter-engine/*" } }) {
nodes {
frontmatter {
title
}
body
excerpt
tableOfContents
timeToRead
wordCount {
paragraphs
sentences
words
}
mdxAST
}
}
}
`
Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,15 @@
require(`fs`).writeFileSync(`${process.cwd()}/cypress/fixtures/file-to-attempt-rce-on.txt`, (new Error('Helpful stack trace if this does execute. It should not execute.')).stack)
console.trace()
return {
title: `I should not be parsed`
title: `I should not be parsed`,
otherKey: `Some other key`
}
})()

---

<h1>JS frontmatter engine is disabled by default</h1>

<span data-cy="js-frontmatter">
<span data-cy="frontmatter">
{props.pageContext.frontmatter?.title || `disabled`}
</span>
Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,15 @@
require(`fs`).writeFileSync(`${process.cwd()}/cypress/fixtures/file-to-attempt-rce-on.txt`, (new Error('Helpful stack trace if this does execute. It should not execute.')).stack)
console.trace()
return {
title: `I should not be parsed`
title: `I should not be parsed`,
otherKey: `Some other key`
}
})()

---

<h1>JS frontmatter engine is disabled by default</h1>

<span data-cy="js-frontmatter">
<span data-cy="frontmatter">
{props.pageContext.frontmatter?.title || `disabled`}
</span>
8 changes: 8 additions & 0 deletions e2e-tests/mdx/src/pages/frontmatter-json.mdx
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
---json
{ "title": "I am parsed", "otherKey": "Some other key" }

---

<h1>A page with JSON frontmatter</h1>

<span data-cy="frontmatter">{props.pageContext.frontmatter?.title}</span>
9 changes: 9 additions & 0 deletions e2e-tests/mdx/src/pages/frontmatter-yaml.mdx
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
---yaml
title: I am parsed
otherKey: Some other key

---

<h1>A page with YAML frontmatter</h1>

<span data-cy="frontmatter">{props.pageContext.frontmatter?.title}</span>
7 changes: 2 additions & 5 deletions packages/gatsby-plugin-mdx/loaders/mdx-loader.js
Original file line number Diff line number Diff line change
Expand Up @@ -182,12 +182,9 @@ export const _frontmatter = ${JSON.stringify(data)};`
// check needs to happen first.
if (!hasDefaultExport(content, options) && !!defaultLayout) {
debug(`inserting default layout`, defaultLayout)
const { content: contentWithoutFrontmatter, matter } = grayMatter(
content,
options
)
const { content: contentWithoutFrontmatter } = grayMatter(content, options)

code = `${matter ? matter : ``}
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When grayMatter was not passed options prior to this change, matter would always be undefined, resulting in no frontmatter rendered to the page. This changes removes matter entirely from the output node raw body.

Unsure if this is the correct fix since it's unclear to me why matter was included here in the first place (maybe it is stripped in later code paths?).

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I tracked first introduction of it to ChristopherBiscardi/gatsby-mdx#329 - there is 0 context on it - to me it seem more like debugging code than anything else - the code is in the MDX format, so it would just output any content put there as content which doesn;t make much sense (to me anyway).

Especially with fact that matter in returned object means:

file.matter {String}: the raw, un-parsed front-matter string

code = `

import DefaultLayout from "${slash(defaultLayout)}"

Expand Down