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feat: Enable CSP with Nonce in the Report Only Header #840

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Merged
merged 2 commits into from
Mar 27, 2025
Merged

feat: Enable CSP with Nonce in the Report Only Header #840

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a3da0a0
feat: Enable CSP with Nonce in the Report Only Header
andreituicu Mar 17, 2025
6bcbf58
feat: Enable CSP with Nonce in the Report Only Header
andreituicu Mar 17, 2025
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57 changes: 42 additions & 15 deletions src/steps/csp.js
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Original file line number Diff line number Diff line change
Expand Up @@ -40,17 +40,22 @@ function parseCSP(csp) {
/**
* Computes where nonces should be applied
* @param {string | null | undefined} metaCSPText The actual CSP value from the meta tag
* @param {string | null | undefined} headersCSPText The actual CSP value from the headers
* @param {string | null | undefined} headerCSPText The actual CSP value from the header
* @param {string | null | undefined} headerCSPROText The actual CSP value from report-only header
* @returns {scriptNonce: boolean, styleNonce: boolean}
*/
function shouldApplyNonce(metaCSPText, headersCSPText) {
function shouldApplyNonce(metaCSPText, headerCSPText, headerCSPROText) {
const metaBased = parseCSP(metaCSPText);
const headersBased = parseCSP(headersCSPText);
const headerBased = parseCSP(headerCSPText);
const headerROBased = parseCSP(headerCSPROText);

return {
scriptNonce: metaBased['script-src']?.includes(NONCE_AEM)
|| headersBased['script-src']?.includes(NONCE_AEM),
|| headerBased['script-src']?.includes(NONCE_AEM)
|| headerROBased['script-src']?.includes(NONCE_AEM),
styleNonce: metaBased['style-src']?.includes(NONCE_AEM)
|| headersBased['style-src']?.includes(NONCE_AEM),
|| headerBased['style-src']?.includes(NONCE_AEM)
|| headerROBased['style-src']?.includes(NONCE_AEM),
};
}

Expand All @@ -73,23 +78,36 @@ export function getHeaderCSP(res) {
return res.headers?.get('content-security-policy');
}

export function getHeaderCSPRO(res) {
return res.headers?.get('content-security-policy-report-only');
}

/**
* Apply CSP with nonces on an AST
* @param {PipelineResponse} res
* @param {Object} tree
* @param {Object} metaCSP
* @param {string} headersCSP
* @param {string} headerCSP
* @param {string} headerCSPRO
*/
function createAndApplyNonceOnAST(res, tree, metaCSP, headersCSP) {
function createAndApplyNonceOnAST(res, tree, metaCSP, headerCSP, headerCSPRO) {
const nonce = createNonce();
const { scriptNonce, styleNonce } = shouldApplyNonce(metaCSP?.properties.content, headersCSP);
const { scriptNonce, styleNonce } = shouldApplyNonce(
metaCSP?.properties.content,
headerCSP,
headerCSPRO,
);

if (metaCSP) {
metaCSP.properties.content = metaCSP.properties.content.replaceAll(NONCE_AEM, `'nonce-${nonce}'`);
}

if (headersCSP) {
res.headers.set('content-security-policy', headersCSP.replaceAll(NONCE_AEM, `'nonce-${nonce}'`));
if (headerCSP) {
res.headers.set('content-security-policy', headerCSP.replaceAll(NONCE_AEM, `'nonce-${nonce}'`));
}

if (headerCSPRO) {
res.headers.set('content-security-policy-report-only', headerCSPRO.replaceAll(NONCE_AEM, `'nonce-${nonce}'`));
}

visit(tree, (node) => {
Expand Down Expand Up @@ -130,15 +148,18 @@ export function getMetaCSP(tree) {
export function contentSecurityPolicyOnAST(res, tree) {
const metaCSP = getMetaCSP(tree);
const headersCSP = getHeaderCSP(res);

if (!metaCSP && !headersCSP) {
const headersCSPRO = getHeaderCSPRO(res);
if (!metaCSP && !headersCSP && !headersCSPRO) {
// No CSP defined
return;
}

// CSP with nonce
if (metaCSP?.properties.content.includes(NONCE_AEM) || headersCSP?.includes(NONCE_AEM)) {
createAndApplyNonceOnAST(res, tree, metaCSP, headersCSP);
if (metaCSP?.properties.content.includes(NONCE_AEM)
|| headersCSP?.includes(NONCE_AEM)
|| headersCSPRO?.includes(NONCE_AEM)
) {
createAndApplyNonceOnAST(res, tree, metaCSP, headersCSP, headersCSPRO);
}

if (metaCSP?.properties['move-as-header'] === 'true') {
Expand All @@ -159,15 +180,17 @@ export function contentSecurityPolicyOnCode(state, res) {
}

const cspHeader = getHeaderCSP(res);
const cspROHeader = getHeaderCSPRO(res);
if (!(
cspHeader?.includes(NONCE_AEM)
|| cspROHeader?.includes(NONCE_AEM)
|| (checkResponseBodyForMetaBasedCSP(res) && checkResponseBodyForAEMNonce(res))
)) {
return;
}

const nonce = createNonce();
let { scriptNonce, styleNonce } = shouldApplyNonce(null, cspHeader);
let { scriptNonce, styleNonce } = shouldApplyNonce(null, cspHeader, cspROHeader);

const html = res.body;
const chunks = [];
Expand Down Expand Up @@ -232,4 +255,8 @@ export function contentSecurityPolicyOnCode(state, res) {
if (cspHeader) {
res.headers.set('content-security-policy', cspHeader.replaceAll(NONCE_AEM, `'nonce-${nonce}'`));
}

if (cspROHeader) {
res.headers.set('content-security-policy-report-only', cspROHeader.replaceAll(NONCE_AEM, `'nonce-${nonce}'`));
}
}
44 changes: 44 additions & 0 deletions test/rendering.test.js
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -629,6 +629,31 @@ describe('Rendering', () => {
assert.strictEqual(headers.get('content-security-policy'), `script-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t' 'strict-dynamic'; style-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t'; base-uri 'self'; object-src 'none';`);
});

it('renders csp nonce header - report-only', async () => {
config = {
...DEFAULT_CONFIG,
headers: {
'/**': [
{
key: 'Content-Security-Policy-Report-Only',
// eslint-disable-next-line quotes
value: `script-src 'nonce-aem' 'strict-dynamic'; style-src 'nonce-aem'; base-uri 'self'; object-src 'none';`,
},
],
},
head: {
html: '<script nonce="aem" src="/scripts/aem.js" type="module"></script>\n'
+ '<script nonce="aem" src="/scripts/scripts.js" type="module"></script>\n'
+ '<link nonce="aem" rel="stylesheet" href="/styles/styles.css"/>\n'
+ '<script nonce="aem" > const a = 1 </script>\n'
+ '<style nonce="aem" id="at-body-style">body {opacity: 1}</style>',
},
};
const { headers } = await testRender('nonce-headers', 'html');
// eslint-disable-next-line quotes
assert.strictEqual(headers.get('content-security-policy-report-only'), `script-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t' 'strict-dynamic'; style-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t'; base-uri 'self'; object-src 'none';`);
});

it('renders csp nonce metadata - move as header', async () => {
config = {
...DEFAULT_CONFIG,
Expand Down Expand Up @@ -1054,6 +1079,25 @@ describe('Rendering', () => {
assert.strictEqual(headers.get('content-security-policy'), `script-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t' 'strict-dynamic'; style-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t'; base-uri 'self'; object-src 'none';`);
});

it('renders static html from the codebus and applies csp from header - report-only with nonce', async () => {
config = {
...DEFAULT_CONFIG,
headers: {
'/**': [
{
key: 'content-security-policy-report-only',
// eslint-disable-next-line quotes
value: `script-src 'nonce-aem' 'strict-dynamic'; style-src 'nonce-aem'; base-uri 'self'; object-src 'none';`,
},
],
},
};

const { headers } = await testRenderCode(new URL('https://helix-pages.com/static-nonce-header.html'));
// eslint-disable-next-line quotes
assert.strictEqual(headers.get('content-security-policy-report-only'), `script-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t' 'strict-dynamic'; style-src 'nonce-ckE0bmQwbW1tckE0bmQwbW1t'; base-uri 'self'; object-src 'none';`);
});

it('renders static html from the codebus and applies csp from meta with nonce', async () => {
const { headers } = await testRenderCode(new URL('https://helix-pages.com/static-nonce-meta.html'));
assert.ok(!headers.get('content-security-policy'));
Expand Down