1 files changed, 478 insertions, 0 deletions
diff --git a/toolkit/mozapps/webextensions/AddonContentPolicy.cpp b/toolkit/mozapps/webextensions/AddonContentPolicy.cpp
new file mode 100644
index 000000000..90e53b2ea
--- /dev/null
+++ b/toolkit/mozapps/webextensions/AddonContentPolicy.cpp
@@ -0,0 +1,478 @@
+/* -*- 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/nsCSPUtils.h"
+#include "nsCOMPtr.h"
+#include "nsContentPolicyUtils.h"
+#include "nsContentTypeParser.h"
+#include "nsContentUtils.h"
+#include "nsIConsoleService.h"
+#include "nsIContentSecurityPolicy.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+#include "nsIEffectiveTLDService.h"
+#include "nsIScriptError.h"
+#include "nsIStringBundle.h"
+#include "nsIUUIDGenerator.h"
+#include "nsIURI.h"
+#include "nsNetCID.h"
+#include "nsNetUtil.h"
+
+using namespace mozilla;
+
+/* Enforces content policies for WebExtension scopes. Currently:
+ *
+ *  - Prevents loading scripts with a non-default JavaScript version.
+ *  - Checks custom content security policies for sufficiently stringent
+ *    script-src and object-src directives.
+ */
+
+#define VERSIONED_JS_BLOCKED_MESSAGE \
+  u"Versioned JavaScript is a non-standard, deprecated extension, and is " \
+  u"not supported in WebExtension code. For alternatives, please see: " \
+  u"https://developer.mozilla.org/Add-ons/WebExtensions/Tips"
+
+AddonContentPolicy::AddonContentPolicy()
+{
+}
+
+AddonContentPolicy::~AddonContentPolicy()
+{
+}
+
+NS_IMPL_ISUPPORTS(AddonContentPolicy, nsIContentPolicy, nsIAddonContentPolicy)
+
+static nsresult
+GetWindowIDFromContext(nsISupports* aContext, uint64_t *aResult)
+{
+  NS_ENSURE_TRUE(aContext, NS_ERROR_FAILURE);
+
+  nsCOMPtr<nsIContent> content = do_QueryInterface(aContext);
+  NS_ENSURE_TRUE(content, NS_ERROR_FAILURE);
+
+  nsCOMPtr<nsIDocument> document = content->OwnerDoc();
+  NS_ENSURE_TRUE(document, NS_ERROR_FAILURE);
+
+  nsCOMPtr<nsPIDOMWindowInner> window = document->GetInnerWindow();
+  NS_ENSURE_TRUE(window, NS_ERROR_FAILURE);
+
+  *aResult = window->WindowID();
+  return NS_OK;
+}
+
+static nsresult
+LogMessage(const nsAString &aMessage, nsIURI* aSourceURI, const nsAString &aSourceSample,
+           nsISupports* aContext)
+{
+  nsCOMPtr<nsIScriptError> error = do_CreateInstance(NS_SCRIPTERROR_CONTRACTID);
+  NS_ENSURE_TRUE(error, NS_ERROR_OUT_OF_MEMORY);
+
+  nsCString sourceName = aSourceURI->GetSpecOrDefault();
+
+  uint64_t windowID = 0;
+  GetWindowIDFromContext(aContext, &windowID);
+
+  nsresult rv =
+    error->InitWithWindowID(aMessage, NS_ConvertUTF8toUTF16(sourceName),
+                            aSourceSample, 0, 0, nsIScriptError::errorFlag,
+                            "JavaScript", windowID);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIConsoleService> console = do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+  NS_ENSURE_TRUE(console, NS_ERROR_OUT_OF_MEMORY);
+
+  console->LogMessage(error);
+  return NS_OK;
+}
+
+
+// Content policy enforcement:
+
+NS_IMETHODIMP
+AddonContentPolicy::ShouldLoad(uint32_t aContentType,
+                               nsIURI* aContentLocation,
+                               nsIURI* aRequestOrigin,
+                               nsISupports* aContext,
+                               const nsACString& aMimeTypeGuess,
+                               nsISupports* aExtra,
+                               nsIPrincipal* aRequestPrincipal,
+                               int16_t* aShouldLoad)
+{
+  MOZ_ASSERT(aContentType == nsContentUtils::InternalContentPolicyTypeToExternal(aContentType),
+             "We should only see external content policy types here.");
+
+  *aShouldLoad = nsIContentPolicy::ACCEPT;
+
+  if (!aRequestOrigin) {
+    return NS_OK;
+  }
+
+  // Only apply this policy to requests from documents loaded from
+  // moz-extension URLs, or to resources being loaded from moz-extension URLs.
+  bool equals;
+  if (!((NS_SUCCEEDED(aContentLocation->SchemeIs("moz-extension", &equals)) && equals) ||
+        (NS_SUCCEEDED(aRequestOrigin->SchemeIs("moz-extension", &equals)) && equals))) {
+    return NS_OK;
+  }
+
+  if (aContentType == nsIContentPolicy::TYPE_SCRIPT) {
+    NS_ConvertUTF8toUTF16 typeString(aMimeTypeGuess);
+    nsContentTypeParser mimeParser(typeString);
+
+    // Reject attempts to load JavaScript scripts with a non-default version.
+    nsAutoString mimeType, version;
+    if (NS_SUCCEEDED(mimeParser.GetType(mimeType)) &&
+        nsContentUtils::IsJavascriptMIMEType(mimeType) &&
+        NS_SUCCEEDED(mimeParser.GetParameter("version", version))) {
+      *aShouldLoad = nsIContentPolicy::REJECT_REQUEST;
+
+      LogMessage(NS_MULTILINE_LITERAL_STRING(VERSIONED_JS_BLOCKED_MESSAGE),
+                 aRequestOrigin, typeString, aContext);
+      return NS_OK;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+AddonContentPolicy::ShouldProcess(uint32_t aContentType,
+                                  nsIURI* aContentLocation,
+                                  nsIURI* aRequestOrigin,
+                                  nsISupports* aRequestingContext,
+                                  const nsACString& aMimeTypeGuess,
+                                  nsISupports* aExtra,
+                                  nsIPrincipal* aRequestPrincipal,
+                                  int16_t* aShouldProcess)
+{
+  MOZ_ASSERT(aContentType == nsContentUtils::InternalContentPolicyTypeToExternal(aContentType),
+             "We should only see external content policy types here.");
+
+  *aShouldProcess = nsIContentPolicy::ACCEPT;
+  return NS_OK;
+}
+
+
+// CSP Validation:
+
+static const char* allowedSchemes[] = {
+  "blob",
+  "filesystem",
+  nullptr
+};
+
+static const char* allowedHostSchemes[] = {
+  "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.
+ */
+class CSPValidator final : public nsCSPSrcVisitor {
+  public:
+    CSPValidator(nsAString& aURL, CSPDirective aDirective, bool aDirectiveRequired = true) :
+      mURL(aURL),
+      mDirective(CSP_CSPDirectiveToString(aDirective)),
+      mFoundSelf(false)
+    {
+      // Start with the default error message for a missing directive, since no
+      // visitors will be called if the directive isn't present.
+      if (aDirectiveRequired) {
+        FormatError("csp.error.missing-directive");
+      }
+    }
+
+    // Visitors
+
+    bool visitSchemeSrc(const nsCSPSchemeSrc& src) override
+    {
+      nsAutoString scheme;
+      src.getScheme(scheme);
+
+      if (SchemeInList(scheme, allowedHostSchemes)) {
+        FormatError("csp.error.missing-host", scheme);
+        return false;
+      }
+      if (!SchemeInList(scheme, allowedSchemes)) {
+        FormatError("csp.error.illegal-protocol", scheme);
+        return false;
+      }
+      return true;
+    };
+
+    bool visitHostSrc(const nsCSPHostSrc& src) override
+    {
+      nsAutoString scheme, host;
+
+      src.getScheme(scheme);
+      src.getHost(host);
+
+      if (scheme.LowerCaseEqualsLiteral("https")) {
+        if (!HostIsAllowed(host)) {
+          FormatError("csp.error.illegal-host-wildcard", 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", scheme);
+          return false;
+        }
+      } else if (!SchemeInList(scheme, allowedSchemes)) {
+        FormatError("csp.error.illegal-protocol", scheme);
+        return false;
+      }
+
+      return true;
+    };
+
+    bool visitKeywordSrc(const nsCSPKeywordSrc& src) override
+    {
+      switch (src.getKeyword()) {
+      case CSP_NONE:
+      case CSP_SELF:
+      case CSP_UNSAFE_EVAL:
+        return true;
+
+      default:
+        NS_ConvertASCIItoUTF16 keyword(CSP_EnumToKeyword(src.getKeyword()));
+
+        FormatError("csp.error.illegal-keyword", keyword);
+        return false;
+      }
+    };
+
+    bool visitNonceSrc(const nsCSPNonceSrc& src) override
+    {
+      FormatError("csp.error.illegal-keyword", NS_LITERAL_STRING("'nonce-*'"));
+      return false;
+    };
+
+    bool visitHashSrc(const nsCSPHashSrc& src) override
+    {
+      return true;
+    };
+
+    // Accessors
+
+    inline nsAString& GetError()
+    {
+      return mError;
+    };
+
+    inline bool FoundSelf()
+    {
+      return mFoundSelf;
+    };
+
+
+    // Formatters
+
+    template <typename... T>
+    inline void FormatError(const char* aName, const T ...aParams)
+    {
+      const char16_t* params[] = { mDirective.get(), aParams.get()... };
+      FormatErrorParams(aName, params, MOZ_ARRAY_LENGTH(params));
+    };
+
+  private:
+    // Validators
+
+    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;
+    };
+
+
+    // Formatters
+
+    already_AddRefed<nsIStringBundle>
+    GetStringBundle()
+    {
+      nsCOMPtr<nsIStringBundleService> sbs =
+        mozilla::services::GetStringBundleService();
+      NS_ENSURE_TRUE(sbs, nullptr);
+
+      nsCOMPtr<nsIStringBundle> stringBundle;
+      sbs->CreateBundle("chrome://global/locale/extensions.properties",
+                        getter_AddRefs(stringBundle));
+
+      return stringBundle.forget();
+    };
+
+    void FormatErrorParams(const char* aName, const char16_t** aParams, int32_t aLength)
+    {
+      nsresult rv = NS_ERROR_FAILURE;
+
+      nsCOMPtr<nsIStringBundle> stringBundle = GetStringBundle();
+
+      if (stringBundle) {
+        NS_ConvertASCIItoUTF16 name(aName);
+
+        rv = stringBundle->FormatStringFromName(name.get(), aParams, aLength,
+                                                getter_Copies(mError));
+      }
+
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        mError.AssignLiteral("An unexpected error occurred");
+      }
+    };
+
+
+    // Data members
+
+    nsAutoString mURL;
+    NS_ConvertASCIItoUTF16 mDirective;
+    nsXPIDLString mError;
+
+    bool mFoundSelf;
+};
+
+/**
+ * Validates a custom content security policy string for use by an add-on.
+ * In particular, ensures that:
+ *
+ *  - Both object-src and script-src directives are present, and meet
+ *    the policies required by the CSPValidator class
+ *
+ *  - The script-src directive includes the source 'self'
+ */
+NS_IMETHODIMP
+AddonContentPolicy::ValidateAddonCSP(const nsAString& aPolicyString,
+                                     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 = services::GetUUIDGenerator();
+    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::CreateCodebasePrincipal(NS_ConvertUTF16toUTF8(url));
+
+  nsCOMPtr<nsIContentSecurityPolicy> csp;
+  rv = principal->EnsureCSP(nullptr, getter_AddRefs(csp));
+  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);
+    aResult.Assign(validator.GetError());
+    return NS_OK;
+  }
+
+  bool haveValidDefaultSrc = 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);
+
+    if (!policy->visitDirectiveSrcs(directive, &validator)) {
+      aResult.Assign(validator.GetError());
+    } else if (!validator.FoundSelf()) {
+      validator.FormatError("csp.error.missing-source", NS_LITERAL_STRING("'self'"));
+      aResult.Assign(validator.GetError());
+    }
+  }
+
+  if (aResult.IsVoid()) {
+    CSPDirective directive = nsIContentSecurityPolicy::OBJECT_SRC_DIRECTIVE;
+    CSPValidator validator(url, directive, !haveValidDefaultSrc);
+
+    if (!policy->visitDirectiveSrcs(directive, &validator)) {
+      aResult.Assign(validator.GetError());
+    }
+  }
+
+  return NS_OK;
+}