From d09b7ee10541b5a81430d2e11abb3a9a09643ade Mon Sep 17 00:00:00 2001 From: Wojtek Kosior Date: Fri, 20 Aug 2021 12:57:48 +0200 Subject: sanitize `' tags containing CSP rules under Chromium This commit adds a mechanism of hijacking document when it loads and injecting sanitized nodes to the DOM from the level of content script. --- background/policy_injector.js | 23 +++++++---------------- 1 file changed, 7 insertions(+), 16 deletions(-) (limited to 'background') diff --git a/background/policy_injector.js b/background/policy_injector.js index 702f879..3398b53 100644 --- a/background/policy_injector.js +++ b/background/policy_injector.js @@ -18,19 +18,12 @@ * IMPORT query_best * IMPORT sanitize_csp_header * IMPORT csp_rule + * IMPORT is_csp_header_name * IMPORTS_END */ var storage; -const csp_header_names = new Set([ - "content-security-policy", - "x-webkit-csp", - "x-content-security-policy" -]); - -const report_only = "content-security-policy-report-only"; - function headers_inject(details) { const url = details.url; @@ -40,7 +33,6 @@ function headers_inject(details) const [pattern, settings] = query_best(storage, url); const allow = !!(settings && settings.allow); const nonce = gen_nonce(); - const rule = `'nonce-${nonce}'`; let orig_csp_headers; let old_signature; @@ -70,20 +62,19 @@ function headers_inject(details) } orig_csp_headers = orig_csp_headers || - headers.filter(h => csp_header_names.has(h.name.toLowerCase())); - headers = headers.filter(h => !csp_header_names.has(h.name.toLowerCase())); + headers.filter(h => is_csp_header_name(h.name)); - /* Remove headers that only snitch on us */ - if (!allow) - headers = headers.filter(h => h.name.toLowerCase() !== report_only); + /* When blocking remove report-only CSP headers that snitch on us. */ + headers = headers.filter(h => !is_csp_header_name(h.name, !allow)); if (old_signature) headers = headers.filter(h => h.name.search(old_signature) === -1); - const sanitizer = h => sanitize_csp_header(h, rule, allow); + const policy_object = {allow, nonce, url}; + const sanitizer = h => sanitize_csp_header(h, policy_object); headers.push(...orig_csp_headers.map(sanitizer)); - const policy = encodeURIComponent(JSON.stringify({allow, nonce, url})); + const policy = encodeURIComponent(JSON.stringify(policy_object)); const policy_signature = sign_data(policy, new Date()); const later_30sec = new Date(new Date().getTime() + 30000).toGMTString(); headers.push({ -- cgit v1.2.3