/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #include "AddonContentPolicy.h" #include "mozilla/dom/nsCSPContext.h" #include "nsCOMPtr.h" #include "nsComponentManagerUtils.h" #include "nsIContent.h" #include "mozilla/BasePrincipal.h" #include "mozilla/Components.h" #include "mozilla/dom/Document.h" #include "mozilla/intl/Localization.h" #include "nsIEffectiveTLDService.h" #include "nsIUUIDGenerator.h" #include "nsIURI.h" #include "nsNetCID.h" #include "nsNetUtil.h" using namespace mozilla; using namespace mozilla::intl; /* Enforces content policies for WebExtension scopes. Currently: * * - Checks custom content security policies for sufficiently stringent * script-src and other script-related directives. * - We also used to validate object-src similarly to script-src, but that was * dropped because NPAPI plugins are no longer supported (see bug 1766881). */ AddonContentPolicy::AddonContentPolicy() = default; AddonContentPolicy::~AddonContentPolicy() = default; NS_IMPL_ISUPPORTS(AddonContentPolicy, nsIAddonContentPolicy) // CSP Validation: static const char* allowedSchemes[] = {"blob", "filesystem", nullptr}; static const char* allowedHostSchemes[] = {"http", "https", "moz-extension", nullptr}; /** * Validates a CSP directive to ensure that it is sufficiently stringent. * In particular, ensures that: * * - No remote sources are allowed other than from https: schemes * * - No remote sources specify host wildcards for generic domains * (*.blogspot.com, *.com, *) * * - All remote sources and local extension sources specify a host * * - No scheme sources are allowed other than blob:, filesystem:, * moz-extension:, and https: * * - No keyword sources are allowed other than 'none', 'self', 'unsafe-eval', * and hash sources. * * Manifest V3 limits CSP for extension_pages, the script-src and * worker-src directives may only be the following: * - self * - none */ class CSPValidator final : public nsCSPSrcVisitor { public: CSPValidator(nsAString& aURL, CSPDirective aDirective, bool aDirectiveRequired = true, uint32_t aPermittedPolicy = 0) : mURL(aURL), mDirective(CSP_CSPDirectiveToString(aDirective)), mPermittedPolicy(aPermittedPolicy), mDirectiveRequired(aDirectiveRequired), mFoundSelf(false) { // Start with the default error message for a missing directive, since no // visitors will be called if the directive isn't present. mError.SetIsVoid(true); } // Visitors bool visitSchemeSrc(const nsCSPSchemeSrc& src) override { nsAutoString scheme; src.getScheme(scheme); if (SchemeInList(scheme, allowedHostSchemes)) { FormatError("csp-error-missing-host"_ns, "scheme"_ns, scheme); return false; } if (!SchemeInList(scheme, allowedSchemes)) { FormatError("csp-error-illegal-protocol"_ns, "scheme"_ns, scheme); return false; } return true; }; bool visitHostSrc(const nsCSPHostSrc& src) override { nsAutoString scheme, host; src.getScheme(scheme); src.getHost(host); if (scheme.LowerCaseEqualsLiteral("http")) { // Allow localhost on http if (mPermittedPolicy & nsIAddonContentPolicy::CSP_ALLOW_LOCALHOST && HostIsLocal(host)) { return true; } FormatError("csp-error-illegal-protocol"_ns, "scheme"_ns, scheme); return false; } if (scheme.LowerCaseEqualsLiteral("https")) { if (mPermittedPolicy & nsIAddonContentPolicy::CSP_ALLOW_LOCALHOST && HostIsLocal(host)) { return true; } if (!(mPermittedPolicy & nsIAddonContentPolicy::CSP_ALLOW_REMOTE)) { FormatError("csp-error-illegal-protocol"_ns, "scheme"_ns, scheme); return false; } if (!HostIsAllowed(host)) { FormatError("csp-error-illegal-host-wildcard"_ns, "scheme"_ns, scheme); return false; } } else if (scheme.LowerCaseEqualsLiteral("moz-extension")) { // The CSP parser silently converts 'self' keywords to the origin // URL, so we need to reconstruct the URL to see if it was present. if (!mFoundSelf) { nsAutoString url(u"moz-extension://"); url.Append(host); mFoundSelf = url.Equals(mURL); } if (host.IsEmpty() || host.EqualsLiteral("*")) { FormatError("csp-error-missing-host"_ns, "scheme"_ns, scheme); return false; } } else if (!SchemeInList(scheme, allowedSchemes)) { FormatError("csp-error-illegal-protocol"_ns, "scheme"_ns, scheme); return false; } return true; }; bool visitKeywordSrc(const nsCSPKeywordSrc& src) override { switch (src.getKeyword()) { case CSP_NONE: case CSP_SELF: return true; case CSP_WASM_UNSAFE_EVAL: if (mPermittedPolicy & nsIAddonContentPolicy::CSP_ALLOW_WASM) { return true; } // fall through to also check CSP_ALLOW_EVAL [[fallthrough]]; case CSP_UNSAFE_EVAL: if (mPermittedPolicy & nsIAddonContentPolicy::CSP_ALLOW_EVAL) { return true; } // fall through and produce an illegal-keyword error. [[fallthrough]]; default: FormatError( "csp-error-illegal-keyword"_ns, "keyword"_ns, nsDependentString(CSP_EnumToUTF16Keyword(src.getKeyword()))); return false; } }; bool visitNonceSrc(const nsCSPNonceSrc& src) override { FormatError("csp-error-illegal-keyword"_ns, "keyword"_ns, u"'nonce-*'"_ns); return false; }; bool visitHashSrc(const nsCSPHashSrc& src) override { return true; }; // Accessors inline nsAString& GetError() { if (mError.IsVoid() && mDirectiveRequired) { FormatError("csp-error-missing-directive"_ns); } return mError; }; inline bool FoundSelf() { return mFoundSelf; }; // Formatters inline void FormatError(const nsACString& l10nId, const nsACString& aKey = ""_ns, const nsAString& aValue = u""_ns) { nsTArray resIds = {"toolkit/global/cspErrors.ftl"_ns}; RefPtr l10n = intl::Localization::Create(resIds, true); auto l10nArgs = dom::Optional(); l10nArgs.Construct(); auto dirArg = l10nArgs.Value().Entries().AppendElement(); dirArg->mKey = "directive"; dirArg->mValue.SetValue().SetAsUTF8String().Assign( NS_ConvertUTF16toUTF8(mDirective)); if (!aKey.IsEmpty()) { auto optArg = l10nArgs.Value().Entries().AppendElement(); optArg->mKey = aKey; optArg->mValue.SetValue().SetAsUTF8String().Assign( NS_ConvertUTF16toUTF8(aValue)); } nsAutoCString translation; IgnoredErrorResult rv; l10n->FormatValueSync(l10nId, l10nArgs, translation, rv); if (rv.Failed()) { mError.AssignLiteral("An unexpected error occurred"); } else { mError = NS_ConvertUTF8toUTF16(translation); } }; private: // Validators bool HostIsLocal(nsAString& host) { return host.EqualsLiteral("localhost") || host.EqualsLiteral("127.0.0.1"); } bool HostIsAllowed(nsAString& host) { if (host.First() == '*') { if (host.EqualsLiteral("*") || host[1] != '.') { return false; } host.Cut(0, 2); nsCOMPtr tldService = do_GetService(NS_EFFECTIVETLDSERVICE_CONTRACTID); if (!tldService) { return false; } NS_ConvertUTF16toUTF8 cHost(host); nsAutoCString publicSuffix; nsresult rv = tldService->GetPublicSuffixFromHost(cHost, publicSuffix); return NS_SUCCEEDED(rv) && !cHost.Equals(publicSuffix); } return true; }; bool SchemeInList(nsAString& scheme, const char** schemes) { for (; *schemes; schemes++) { if (scheme.LowerCaseEqualsASCII(*schemes)) { return true; } } return false; }; // Data members nsAutoString mURL; NS_ConvertASCIItoUTF16 mDirective; nsString mError; uint32_t mPermittedPolicy; bool mDirectiveRequired; bool mFoundSelf; }; /** * Validates a custom content security policy string for use by an add-on. * In particular, ensures that: * * - That script-src (or default-src) directive is present, and meets * the policies required by the CSPValidator class * * - The script-src directive includes the source 'self' */ NS_IMETHODIMP AddonContentPolicy::ValidateAddonCSP(const nsAString& aPolicyString, uint32_t aPermittedPolicy, nsAString& aResult) { nsresult rv; // Validate against a randomly-generated extension origin. // There is no add-on-specific behavior in the CSP code, beyond the ability // for add-ons to specify a custom policy, but the parser requires a valid // origin in order to operate correctly. nsAutoString url(u"moz-extension://"); { nsCOMPtr uuidgen = components::UUIDGenerator::Service(); NS_ENSURE_TRUE(uuidgen, NS_ERROR_FAILURE); nsID id; rv = uuidgen->GenerateUUIDInPlace(&id); NS_ENSURE_SUCCESS(rv, rv); char idString[NSID_LENGTH]; id.ToProvidedString(idString); MOZ_RELEASE_ASSERT(idString[0] == '{' && idString[NSID_LENGTH - 2] == '}', "UUID generator did not return a valid UUID"); url.AppendASCII(idString + 1, NSID_LENGTH - 3); } RefPtr principal = BasePrincipal::CreateContentPrincipal(NS_ConvertUTF16toUTF8(url)); nsCOMPtr selfURI; principal->GetURI(getter_AddRefs(selfURI)); RefPtr csp = new nsCSPContext(); rv = csp->SetRequestContextWithPrincipal(principal, selfURI, ""_ns, 0); NS_ENSURE_SUCCESS(rv, rv); csp->AppendPolicy(aPolicyString, false, false); const nsCSPPolicy* policy = csp->GetPolicy(0); if (!policy) { CSPValidator validator(url, nsIContentSecurityPolicy::SCRIPT_SRC_DIRECTIVE, true, aPermittedPolicy); aResult.Assign(validator.GetError()); return NS_OK; } bool haveValidDefaultSrc = false; bool hasValidScriptSrc = false; { CSPDirective directive = nsIContentSecurityPolicy::DEFAULT_SRC_DIRECTIVE; CSPValidator validator(url, directive); haveValidDefaultSrc = policy->visitDirectiveSrcs(directive, &validator); } aResult.SetIsVoid(true); { CSPDirective directive = nsIContentSecurityPolicy::SCRIPT_SRC_DIRECTIVE; CSPValidator validator(url, directive, !haveValidDefaultSrc, aPermittedPolicy); if (!policy->visitDirectiveSrcs(directive, &validator)) { aResult.Assign(validator.GetError()); } else if (!validator.FoundSelf()) { validator.FormatError("csp-error-missing-source"_ns, "source"_ns, u"'self'"_ns); aResult.Assign(validator.GetError()); } hasValidScriptSrc = true; } if (aResult.IsVoid()) { CSPDirective directive = nsIContentSecurityPolicy::WORKER_SRC_DIRECTIVE; CSPValidator validator(url, directive, !haveValidDefaultSrc && !hasValidScriptSrc, aPermittedPolicy); if (!policy->visitDirectiveSrcs(directive, &validator)) { aResult.Assign(validator.GetError()); } } return NS_OK; }