1 files changed, 371 insertions, 0 deletions
diff --git a/toolkit/mozapps/extensions/AddonContentPolicy.cpp b/toolkit/mozapps/extensions/AddonContentPolicy.cpp
new file mode 100644
index 0000000000..983935f7c5
--- /dev/null
+++ b/toolkit/mozapps/extensions/AddonContentPolicy.cpp
@@ -0,0 +1,371 @@
+/* -*- 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<nsCString> resIds = {"toolkit/global/cspErrors.ftl"_ns};
+    RefPtr<intl::Localization> l10n = intl::Localization::Create(resIds, true);
+
+    auto l10nArgs = dom::Optional<intl::L10nArgs>();
+    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<nsIEffectiveTLDService> 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<nsIUUIDGenerator> 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<BasePrincipal> principal =
+      BasePrincipal::CreateContentPrincipal(NS_ConvertUTF16toUTF8(url));
+
+  nsCOMPtr<nsIURI> selfURI;
+  principal->GetURI(getter_AddRefs(selfURI));
+  RefPtr<nsCSPContext> csp = new nsCSPContext();
+  rv = csp->SetRequestContextWithPrincipal(principal, selfURI, u""_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;
+}