gecko-dev/dom/security/nsMixedContentBlocker.cpp

/* -*- 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 "nsMixedContentBlocker.h"

#include "nsContentPolicyUtils.h"
#include "nsCSPContext.h"
#include "nsThreadUtils.h"
#include "nsINode.h"
#include "nsCOMPtr.h"
#include "nsDocShell.h"
#include "nsIWebProgressListener.h"
#include "nsContentUtils.h"
#include "mozilla/dom/BrowsingContext.h"
#include "mozilla/dom/WindowContext.h"
#include "mozilla/dom/Document.h"
#include "nsIChannel.h"
#include "nsIParentChannel.h"
#include "mozilla/Preferences.h"
#include "nsIScriptObjectPrincipal.h"
#include "nsIProtocolHandler.h"
#include "nsCharSeparatedTokenizer.h"
#include "nsISecureBrowserUI.h"
#include "nsIWebNavigation.h"
#include "nsLoadGroup.h"
#include "nsIScriptError.h"
#include "nsIURI.h"
#include "nsIChannelEventSink.h"
#include "nsNetUtil.h"
#include "nsAsyncRedirectVerifyHelper.h"
#include "mozilla/LoadInfo.h"
#include "nsISiteSecurityService.h"
#include "prnetdb.h"
#include "nsQueryObject.h"

#include "mozilla/BasePrincipal.h"
#include "mozilla/Logging.h"
#include "mozilla/StaticPrefs_dom.h"
#include "mozilla/StaticPrefs_fission.h"
#include "mozilla/StaticPrefs_security.h"
#include "mozilla/Telemetry.h"
#include "mozilla/dom/ContentChild.h"
#include "mozilla/ipc/URIUtils.h"
#include "mozilla/net/DNS.h"
#include "mozilla/net/DocumentLoadListener.h"
#include "mozilla/net/DocumentChannel.h"

#include "mozilla/dom/nsHTTPSOnlyUtils.h"

using namespace mozilla;
using namespace mozilla::dom;

static mozilla::LazyLogModule sMCBLog("MCBLog");

enum nsMixedContentBlockerMessageType { eBlocked = 0x00, eUserOverride = 0x01 };

// Allowlist of hostnames that should be considered secure contexts even when
// served over http:// or ws://
nsCString* nsMixedContentBlocker::sSecurecontextAllowlist = nullptr;
bool nsMixedContentBlocker::sSecurecontextAllowlistCached = false;

enum MixedContentHSTSState {
  MCB_HSTS_PASSIVE_NO_HSTS = 0,
  MCB_HSTS_PASSIVE_WITH_HSTS = 1,
  MCB_HSTS_ACTIVE_NO_HSTS = 2,
  MCB_HSTS_ACTIVE_WITH_HSTS = 3
};

nsMixedContentBlocker::~nsMixedContentBlocker() = default;

NS_IMPL_ISUPPORTS(nsMixedContentBlocker, nsIContentPolicy, nsIChannelEventSink)

static void LogMixedContentMessage(
    MixedContentTypes aClassification, nsIURI* aContentLocation,
    uint64_t aInnerWindowID, nsMixedContentBlockerMessageType aMessageType,
    nsIURI* aRequestingLocation,
    const nsACString& aOverruleMessageLookUpKeyWithThis = EmptyCString()) {
  nsAutoCString messageCategory;
  uint32_t severityFlag;
  nsAutoCString messageLookupKey;

  if (aMessageType == eBlocked) {
    severityFlag = nsIScriptError::errorFlag;
    messageCategory.AssignLiteral("Mixed Content Blocker");
    if (aClassification == eMixedDisplay) {
      messageLookupKey.AssignLiteral("BlockMixedDisplayContent");
    } else {
      messageLookupKey.AssignLiteral("BlockMixedActiveContent");
    }
  } else {
    severityFlag = nsIScriptError::warningFlag;
    messageCategory.AssignLiteral("Mixed Content Message");
    if (aClassification == eMixedDisplay) {
      messageLookupKey.AssignLiteral("LoadingMixedDisplayContent2");
    } else {
      messageLookupKey.AssignLiteral("LoadingMixedActiveContent2");
    }
  }

  // if the callee explicitly wants to use a special message for this
  // console report, then we allow to overrule the default with the
  // explicitly provided one here.
  if (!aOverruleMessageLookUpKeyWithThis.IsEmpty()) {
    messageLookupKey = aOverruleMessageLookUpKeyWithThis;
  }

  nsAutoString localizedMsg;
  AutoTArray<nsString, 1> params;
  CopyUTF8toUTF16(aContentLocation->GetSpecOrDefault(),
                  *params.AppendElement());
  nsContentUtils::FormatLocalizedString(nsContentUtils::eSECURITY_PROPERTIES,
                                        messageLookupKey.get(), params,
                                        localizedMsg);

  nsContentUtils::ReportToConsoleByWindowID(localizedMsg, severityFlag,
                                            messageCategory, aInnerWindowID,
                                            aRequestingLocation);
}

/* nsIChannelEventSink implementation
 * This code is called when a request is redirected.
 * We check the channel associated with the new uri is allowed to load
 * in the current context
 */
NS_IMETHODIMP
nsMixedContentBlocker::AsyncOnChannelRedirect(
    nsIChannel* aOldChannel, nsIChannel* aNewChannel, uint32_t aFlags,
    nsIAsyncVerifyRedirectCallback* aCallback) {
  mozilla::net::nsAsyncRedirectAutoCallback autoCallback(aCallback);

  if (!aOldChannel) {
    NS_ERROR("No channel when evaluating mixed content!");
    return NS_ERROR_FAILURE;
  }

  // If we are in the parent process in e10s, we don't have access to the
  // document node, and hence ShouldLoad will fail when we try to get
  // the docShell.  If that's the case, ignore mixed content checks
  // on redirects in the parent.  Let the child check for mixed content.
  nsCOMPtr<nsIParentChannel> is_ipc_channel;
  NS_QueryNotificationCallbacks(aNewChannel, is_ipc_channel);
  RefPtr<net::DocumentLoadListener> docListener =
      do_QueryObject(is_ipc_channel);
  if (is_ipc_channel && !docListener) {
    return NS_OK;
  }

  // Don't do these checks if we're switching from DocumentChannel
  // to a real channel. In that case, we should already have done
  // the checks in the parent process. AsyncOnChannelRedirect
  // isn't called in the content process if we switch process,
  // so checking here would just hide bugs in the process switch
  // cases.
  if (RefPtr<net::DocumentChannel> docChannel = do_QueryObject(aOldChannel)) {
    return NS_OK;
  }

  nsresult rv;
  nsCOMPtr<nsIURI> oldUri;
  rv = aOldChannel->GetURI(getter_AddRefs(oldUri));
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIURI> newUri;
  rv = aNewChannel->GetURI(getter_AddRefs(newUri));
  NS_ENSURE_SUCCESS(rv, rv);

  // Get the loading Info from the old channel
  nsCOMPtr<nsILoadInfo> loadInfo = aOldChannel->LoadInfo();
  nsCOMPtr<nsIPrincipal> requestingPrincipal = loadInfo->GetLoadingPrincipal();

  // Since we are calling shouldLoad() directly on redirects, we don't go
  // through the code in nsContentPolicyUtils::NS_CheckContentLoadPolicy().
  // Hence, we have to duplicate parts of it here.
  if (requestingPrincipal) {
    // We check to see if the loadingPrincipal is systemPrincipal and return
    // early if it is
    if (requestingPrincipal->IsSystemPrincipal()) {
      return NS_OK;
    }
  }

  int16_t decision = REJECT_REQUEST;
  rv = ShouldLoad(newUri, loadInfo,
                  EmptyCString(),  // aMimeGuess
                  &decision);
  if (NS_FAILED(rv)) {
    autoCallback.DontCallback();
    aOldChannel->Cancel(NS_ERROR_DOM_BAD_URI);
    return NS_BINDING_FAILED;
  }

  // If the channel is about to load mixed content, abort the channel
  if (!NS_CP_ACCEPTED(decision)) {
    autoCallback.DontCallback();
    aOldChannel->Cancel(NS_ERROR_DOM_BAD_URI);
    return NS_BINDING_FAILED;
  }

  return NS_OK;
}

/* This version of ShouldLoad() is non-static and called by the Content Policy
 * API and AsyncOnChannelRedirect().  See nsIContentPolicy::ShouldLoad()
 * for detailed description of the parameters.
 */
NS_IMETHODIMP
nsMixedContentBlocker::ShouldLoad(nsIURI* aContentLocation,
                                  nsILoadInfo* aLoadInfo,
                                  const nsACString& aMimeGuess,
                                  int16_t* aDecision) {
  // We pass in false as the first parameter to ShouldLoad(), because the
  // callers of this method don't know whether the load went through cached
  // image redirects.  This is handled by direct callers of the static
  // ShouldLoad.
  nsresult rv =
      ShouldLoad(false,  // aHadInsecureImageRedirect
                 aContentLocation, aLoadInfo, aMimeGuess, true, aDecision);

  if (*aDecision == nsIContentPolicy::REJECT_REQUEST) {
    NS_SetRequestBlockingReason(aLoadInfo,
                                nsILoadInfo::BLOCKING_REASON_MIXED_BLOCKED);
  }

  return rv;
}

bool nsMixedContentBlocker::IsPotentiallyTrustworthyLoopbackHost(
    const nsACString& aAsciiHost) {
  if (aAsciiHost.EqualsLiteral("::1") ||
      aAsciiHost.EqualsLiteral("localhost")) {
    return true;
  }

  PRNetAddr tempAddr;
  memset(&tempAddr, 0, sizeof(PRNetAddr));

  if (PR_StringToNetAddr(PromiseFlatCString(aAsciiHost).get(), &tempAddr) !=
      PR_SUCCESS) {
    return false;
  }

  using namespace mozilla::net;
  NetAddr addr(&tempAddr);

  // Step 4 of
  // https://w3c.github.io/webappsec-secure-contexts/#is-origin-trustworthy says
  // we should only consider [::1]/128 as a potentially trustworthy IPv6
  // address, whereas for IPv4 127.0.0.1/8 are considered as potentially
  // trustworthy.  We already handled "[::1]" above, so all that's remained to
  // handle here are IPv4 loopback addresses.
  return addr.IsIPAddrV4() && addr.IsLoopbackAddr();
}

bool nsMixedContentBlocker::IsPotentiallyTrustworthyLoopbackURL(nsIURI* aURL) {
  nsAutoCString asciiHost;
  nsresult rv = aURL->GetAsciiHost(asciiHost);
  NS_ENSURE_SUCCESS(rv, false);
  return IsPotentiallyTrustworthyLoopbackHost(asciiHost);
}

/* Maybe we have a .onion URL. Treat it as trustworthy as well if
 * `dom.securecontext.whitelist_onions` is `true`.
 */
bool nsMixedContentBlocker::IsPotentiallyTrustworthyOnion(nsIURI* aURL) {
  if (!StaticPrefs::dom_securecontext_whitelist_onions()) {
    return false;
  }

  nsAutoCString host;
  nsresult rv = aURL->GetHost(host);
  NS_ENSURE_SUCCESS(rv, false);
  return StringEndsWith(host, ".onion"_ns);
}

// static
void nsMixedContentBlocker::OnPrefChange(const char* aPref, void* aClosure) {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(!strcmp(aPref, "dom.securecontext.whitelist"));
  Preferences::GetCString("dom.securecontext.whitelist",
                          *sSecurecontextAllowlist);
}

// static
void nsMixedContentBlocker::GetSecureContextAllowList(nsACString& aList) {
  MOZ_ASSERT(NS_IsMainThread());
  if (!sSecurecontextAllowlistCached) {
    MOZ_ASSERT(!sSecurecontextAllowlist);
    sSecurecontextAllowlistCached = true;
    sSecurecontextAllowlist = new nsCString();
    Preferences::RegisterCallbackAndCall(OnPrefChange,
                                         "dom.securecontext.whitelist");
  }
  aList = *sSecurecontextAllowlist;
}

// static
void nsMixedContentBlocker::Shutdown() {
  if (sSecurecontextAllowlist) {
    delete sSecurecontextAllowlist;
    sSecurecontextAllowlist = nullptr;
  }
}

bool nsMixedContentBlocker::IsPotentiallyTrustworthyOrigin(nsIURI* aURI) {
  // The following implements:
  // https://w3c.github.io/webappsec-secure-contexts/#is-origin-trustworthy

  nsAutoCString scheme;
  nsresult rv = aURI->GetScheme(scheme);
  if (NS_FAILED(rv)) {
    return false;
  }

  // Blobs are expected to inherit their principal so we don't expect to have
  // a content principal with scheme 'blob' here.  We can't assert that though
  // since someone could mess with a non-blob URI to give it that scheme.
  NS_WARNING_ASSERTION(!scheme.EqualsLiteral("blob"),
                       "IsOriginPotentiallyTrustworthy ignoring blob scheme");

  // According to the specification, the user agent may choose to extend the
  // trust to other, vendor-specific URL schemes. We use this for "resource:",
  // which is technically a substituting protocol handler that is not limited to
  // local resource mapping, but in practice is never mapped remotely as this
  // would violate assumptions a lot of code makes.
  // We use nsIProtocolHandler flags to determine which protocols we consider a
  // priori authenticated.
  bool aPrioriAuthenticated = false;
  if (NS_FAILED(NS_URIChainHasFlags(
          aURI, nsIProtocolHandler::URI_IS_POTENTIALLY_TRUSTWORTHY,
          &aPrioriAuthenticated))) {
    return false;
  }

  if (aPrioriAuthenticated) {
    return true;
  }

  nsAutoCString host;
  rv = aURI->GetHost(host);
  if (NS_FAILED(rv)) {
    return false;
  }

  if (IsPotentiallyTrustworthyLoopbackURL(aURI)) {
    return true;
  }

  // If a host is not considered secure according to the default algorithm, then
  // check to see if it has been allowlisted by the user.  We only apply this
  // allowlist for network resources, i.e., those with scheme "http" or "ws".
  // The pref should contain a comma-separated list of hostnames.

  if (!scheme.EqualsLiteral("http") && !scheme.EqualsLiteral("ws")) {
    return false;
  }

  nsAutoCString allowlist;
  GetSecureContextAllowList(allowlist);
  nsCCharSeparatedTokenizer tokenizer(allowlist, ',');
  while (tokenizer.hasMoreTokens()) {
    const nsACString& allowedHost = tokenizer.nextToken();
    if (host.Equals(allowedHost)) {
      return true;
    }
  }

  // Maybe we have a .onion URL. Treat it as trustworthy as well if
  // `dom.securecontext.whitelist_onions` is `true`.
  if (nsMixedContentBlocker::IsPotentiallyTrustworthyOnion(aURI)) {
    return true;
  }
  return false;
}

/* Static version of ShouldLoad() that contains all the Mixed Content Blocker
 * logic.  Called from non-static ShouldLoad().
 */
nsresult nsMixedContentBlocker::ShouldLoad(bool aHadInsecureImageRedirect,
                                           nsIURI* aContentLocation,
                                           nsILoadInfo* aLoadInfo,
                                           const nsACString& aMimeGuess,
                                           bool aReportError,
                                           int16_t* aDecision) {
  // Asserting that we are on the main thread here and hence do not have to lock
  // and unlock security.mixed_content.block_active_content and
  // security.mixed_content.block_display_content before reading/writing to
  // them.
  MOZ_ASSERT(NS_IsMainThread());

  if (MOZ_UNLIKELY(MOZ_LOG_TEST(sMCBLog, LogLevel::Verbose))) {
    nsAutoCString asciiUrl;
    aContentLocation->GetAsciiSpec(asciiUrl);
    MOZ_LOG(sMCBLog, LogLevel::Verbose, ("shouldLoad:"));
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  - contentLocation: %s", asciiUrl.get()));
  }

  uint32_t contentType = aLoadInfo->InternalContentPolicyType();
  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadInfo->GetLoadingPrincipal();
  nsCOMPtr<nsIPrincipal> triggeringPrincipal = aLoadInfo->TriggeringPrincipal();

  if (MOZ_UNLIKELY(MOZ_LOG_TEST(sMCBLog, LogLevel::Verbose))) {
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  - internalContentPolicyType: %s",
             NS_CP_ContentTypeName(contentType)));

    if (loadingPrincipal != nullptr) {
      nsAutoCString loadingPrincipalAsciiUrl;
      loadingPrincipal->GetAsciiSpec(loadingPrincipalAsciiUrl);
      MOZ_LOG(sMCBLog, LogLevel::Verbose,
              ("  - loadingPrincipal: %s", loadingPrincipalAsciiUrl.get()));
    } else {
      MOZ_LOG(sMCBLog, LogLevel::Verbose, ("  - loadingPrincipal: (nullptr)"));
    }

    nsAutoCString triggeringPrincipalAsciiUrl;
    triggeringPrincipal->GetAsciiSpec(triggeringPrincipalAsciiUrl);
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  - triggeringPrincipal: %s", triggeringPrincipalAsciiUrl.get()));
  }

  RefPtr<WindowContext> requestingWindow =
      WindowContext::GetById(aLoadInfo->GetInnerWindowID());

  bool isPreload = nsContentUtils::IsPreloadType(contentType);

  // The content policy type that we receive may be an internal type for
  // scripts.  Let's remember if we have seen a worker type, and reset it to the
  // external type in all cases right now.
  bool isWorkerType =
      contentType == nsIContentPolicy::TYPE_INTERNAL_WORKER ||
      contentType == nsIContentPolicy::TYPE_INTERNAL_SHARED_WORKER ||
      contentType == nsIContentPolicy::TYPE_INTERNAL_SERVICE_WORKER;
  contentType =
      nsContentUtils::InternalContentPolicyTypeToExternal(contentType);

  // Assume active (high risk) content and blocked by default
  MixedContentTypes classification = eMixedScript;
  // Make decision to block/reject by default
  *aDecision = REJECT_REQUEST;

  // Notes on non-obvious decisions:
  //
  // TYPE_DTD: A DTD can contain entity definitions that expand to scripts.
  //
  // TYPE_FONT: The TrueType hinting mechanism is basically a scripting
  // language that gets interpreted by the operating system's font rasterizer.
  // Mixed content web fonts are relatively uncommon, and we can can fall back
  // to built-in fonts with minimal disruption in almost all cases.
  //
  // TYPE_OBJECT_SUBREQUEST could actually be either active content (e.g. a
  // script that a plugin will execute) or display content (e.g. Flash video
  // content).  Until we have a way to determine active vs passive content
  // from plugin requests (bug 836352), we will treat this as passive content.
  // This is to prevent false positives from causing users to become
  // desensitized to the mixed content blocker.
  //
  // TYPE_CSP_REPORT: High-risk because they directly leak information about
  // the content of the page, and because blocking them does not have any
  // negative effect on the page loading.
  //
  // TYPE_PING: Ping requests are POSTS, not GETs like images and media.
  // Also, PING requests have no bearing on the rendering or operation of
  // the page when used as designed, so even though they are lower risk than
  // scripts, blocking them is basically risk-free as far as compatibility is
  // concerned.
  //
  // TYPE_STYLESHEET: XSLT stylesheets can insert scripts. CSS positioning
  // and other advanced CSS features can possibly be exploited to cause
  // spoofing attacks (e.g. make a "grant permission" button look like a
  // "refuse permission" button).
  //
  // TYPE_BEACON: Beacon requests are similar to TYPE_PING, and are blocked by
  // default.
  //
  // TYPE_WEBSOCKET: The Websockets API requires browsers to
  // reject mixed-content websockets: "If secure is false but the origin of
  // the entry script has a scheme component that is itself a secure protocol,
  // e.g. HTTPS, then throw a SecurityError exception." We already block mixed
  // content websockets within the websockets implementation, so we don't need
  // to do any blocking here, nor do we need to provide a way to undo or
  // override the blocking. Websockets without TLS are very flaky anyway in the
  // face of many HTTP-aware proxies. Compared to passive content, there is
  // additional risk that the script using WebSockets will disclose sensitive
  // information from the HTTPS page and/or eval (directly or indirectly)
  // received data.
  //
  // TYPE_XMLHTTPREQUEST: XHR requires either same origin or CORS, so most
  // mixed-content XHR will already be blocked by that check. This will also
  // block HTTPS-to-HTTP XHR with CORS. The same security concerns mentioned
  // above for WebSockets apply to XHR, and XHR should have the same security
  // properties as WebSockets w.r.t. mixed content. XHR's handling of redirects
  // amplifies these concerns.
  //

  static_assert(TYPE_DATAREQUEST == TYPE_XMLHTTPREQUEST,
                "TYPE_DATAREQUEST is not a synonym for "
                "TYPE_XMLHTTPREQUEST");

  switch (contentType) {
    // The top-level document cannot be mixed content by definition
    case TYPE_DOCUMENT:
      *aDecision = ACCEPT;
      return NS_OK;
    // Creating insecure websocket connections in a secure page is blocked
    // already in the websocket constructor. We don't need to check the blocking
    // here and we don't want to un-block
    case TYPE_WEBSOCKET:
      *aDecision = ACCEPT;
      return NS_OK;

      // TYPE_SAVEAS_DOWNLOAD: Save-link-as feature is used to download a
      // resource
      // without involving a docShell. This kind of loading must be
      // allowed, if not disabled in the preferences.
      // Creating insecure connections for a save-as link download is
      // acceptable. This download is completely disconnected from the docShell,
      // but still using the same loading principal.

    case TYPE_SAVEAS_DOWNLOAD:
      if (!StaticPrefs::dom_block_download_insecure()) {
        *aDecision = ACCEPT;
        return NS_OK;
      }
      break;

    // Static display content is considered moderate risk for mixed content so
    // these will be blocked according to the mixed display preference
    case TYPE_IMAGE:
    case TYPE_MEDIA:
      classification = eMixedDisplay;
      break;
    case TYPE_OBJECT_SUBREQUEST:
      if (StaticPrefs::security_mixed_content_block_object_subrequest()) {
        classification = eMixedScript;
      } else {
        classification = eMixedDisplay;
      }
      break;

    // Active content (or content with a low value/risk-of-blocking ratio)
    // that has been explicitly evaluated; listed here for documentation
    // purposes and to avoid the assertion and warning for the default case.
    case TYPE_BEACON:
    case TYPE_CSP_REPORT:
    case TYPE_DTD:
    case TYPE_FETCH:
    case TYPE_FONT:
    case TYPE_IMAGESET:
    case TYPE_OBJECT:
    case TYPE_SCRIPT:
    case TYPE_STYLESHEET:
    case TYPE_SUBDOCUMENT:
    case TYPE_PING:
    case TYPE_WEB_MANIFEST:
    case TYPE_XMLHTTPREQUEST:
    case TYPE_XSLT:
    case TYPE_OTHER:
    case TYPE_SPECULATIVE:
      break;

    // This content policy works as a allowlist.
    default:
      MOZ_ASSERT(false, "Mixed content of unknown type");
  }

  // Make sure to get the URI the load started with. No need to check
  // outer schemes because all the wrapping pseudo protocols inherit the
  // security properties of the actual network request represented
  // by the innerMost URL.
  nsCOMPtr<nsIURI> innerContentLocation = NS_GetInnermostURI(aContentLocation);
  if (!innerContentLocation) {
    NS_ERROR("Can't get innerURI from aContentLocation");
    *aDecision = REJECT_REQUEST;
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  -> decision: Request will be rejected because the innermost "
             "URI could not be "
             "retrieved"));
    return NS_OK;
  }

  // TYPE_IMAGE redirects are cached based on the original URI, not the final
  // destination and hence cache hits for images may not have the correct
  // innerContentLocation.  Check if the cached hit went through an http
  // redirect, and if it did, we can't treat this as a secure subresource.
  if (!aHadInsecureImageRedirect &&
      URISafeToBeLoadedInSecureContext(innerContentLocation)) {
    *aDecision = ACCEPT;
    return NS_OK;
  }

  /*
   * Most likely aLoadingPrincipal reflects the security context of the owning
   * document for this mixed content check. There are cases where that is not
   * true, hence we have to we process requests in the following order:
   * 1) If the load is triggered by the SystemPrincipal, we allow the load.
   *    Content scripts from addon code do provide aTriggeringPrincipal, which
   *    is an ExpandedPrincipal. If encountered, we allow the load.
   * 2) If aLoadingPrincipal does not yield to a requestingLocation, then we
   *    fall back to querying the requestingLocation from aTriggeringPrincipal.
   * 3) If we still end up not having a requestingLocation, we reject the load.
   */

  // 1) Check if the load was triggered by the system (SystemPrincipal) or
  // a content script from addons code (ExpandedPrincipal) in which case the
  // load is not subject to mixed content blocking.
  if (triggeringPrincipal) {
    if (triggeringPrincipal->IsSystemPrincipal()) {
      *aDecision = ACCEPT;
      return NS_OK;
    }
    nsCOMPtr<nsIExpandedPrincipal> expanded =
        do_QueryInterface(triggeringPrincipal);
    if (expanded) {
      *aDecision = ACCEPT;
      return NS_OK;
    }
  }

  // 2) If aLoadingPrincipal does not provide a requestingLocation, then
  // we fall back to to querying the requestingLocation from
  // aTriggeringPrincipal.
  nsCOMPtr<nsIURI> requestingLocation;
  auto* baseLoadingPrincipal = BasePrincipal::Cast(loadingPrincipal);
  if (baseLoadingPrincipal) {
    baseLoadingPrincipal->GetURI(getter_AddRefs(requestingLocation));
  }
  if (!requestingLocation) {
    auto* baseTriggeringPrincipal = BasePrincipal::Cast(triggeringPrincipal);
    if (baseTriggeringPrincipal) {
      baseTriggeringPrincipal->GetURI(getter_AddRefs(requestingLocation));
    }
  }

  // 3) Giving up. We still don't have a requesting location, therefore we can't
  // tell if this is a mixed content load. Deny to be safe.
  if (!requestingLocation) {
    *aDecision = REJECT_REQUEST;
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  -> decision: Request will be rejected because no requesting "
             "location could be "
             "gathered."));
    return NS_OK;
  }

  // Check the parent scheme. If it is not an HTTPS page then mixed content
  // restrictions do not apply.
  nsCOMPtr<nsIURI> innerRequestingLocation =
      NS_GetInnermostURI(requestingLocation);
  if (!innerRequestingLocation) {
    NS_ERROR("Can't get innerURI from requestingLocation");
    *aDecision = REJECT_REQUEST;
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  -> decision: Request will be rejected because the innermost "
             "URI of the "
             "requesting location could be gathered."));
    return NS_OK;
  }

  bool parentIsHttps = innerRequestingLocation->SchemeIs("https");
  if (!parentIsHttps) {
    *aDecision = ACCEPT;
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  -> decision: Request will be allowed because the requesting "
             "location is not using "
             "HTTPS."));
    return NS_OK;
  }

  // Disallow mixed content loads for workers, shared workers and service
  // workers.
  if (isWorkerType) {
    // For workers, we can assume that we're mixed content at this point, since
    // the parent is https, and the protocol associated with
    // innerContentLocation doesn't map to the secure URI flags checked above.
    // Assert this for sanity's sake
#ifdef DEBUG
    bool isHttpsScheme = innerContentLocation->SchemeIs("https");
    MOZ_ASSERT(!isHttpsScheme);
#endif
    *aDecision = REJECT_REQUEST;
    MOZ_LOG(sMCBLog, LogLevel::Verbose,
            ("  -> decision: Request will be rejected, trying to load a worker "
             "from an insecure origin."));
    return NS_OK;
  }

  bool isHttpScheme = innerContentLocation->SchemeIs("http");
  if (isHttpScheme && IsPotentiallyTrustworthyOrigin(innerContentLocation)) {
    *aDecision = ACCEPT;
    return NS_OK;
  }

  // Check if https-only mode upgrades this later anyway
  if (nsHTTPSOnlyUtils::IsSafeToAcceptCORSOrMixedContent(aLoadInfo)) {
    *aDecision = ACCEPT;
    return NS_OK;
  }

  // The page might have set the CSP directive 'upgrade-insecure-requests'. In
  // such a case allow the http: load to succeed with the promise that the
  // channel will get upgraded to https before fetching any data from the
  // netwerk. Please see: nsHttpChannel::Connect()
  //
  // Please note that the CSP directive 'upgrade-insecure-requests' only applies
  // to http: and ws: (for websockets). Websockets are not subject to mixed
  // content blocking since insecure websockets are not allowed within secure
  // pages. Hence, we only have to check against http: here. Skip mixed content
  // blocking if the subresource load uses http: and the CSP directive
  // 'upgrade-insecure-requests' is present on the page.

  // Carve-out: if we're in the parent and we're loading media, e.g. through
  // webbrowserpersist, don't reject it if we can't find a docshell.
  if (XRE_IsParentProcess() && !requestingWindow &&
      (contentType == TYPE_IMAGE || contentType == TYPE_MEDIA)) {
    *aDecision = ACCEPT;
    return NS_OK;
  }
  // Otherwise, we must have a window
  NS_ENSURE_TRUE(requestingWindow, NS_OK);

  if (isHttpScheme && aLoadInfo->GetUpgradeInsecureRequests()) {
    *aDecision = ACCEPT;
    return NS_OK;
  }

  // Allow http: mixed content if we are choosing to upgrade them when the
  // pref "security.mixed_content.upgrade_display_content" is true.
  // This behaves like GetUpgradeInsecureRequests above in that the channel will
  // be upgraded to https before fetching any data from the netwerk.
  bool isUpgradableDisplayType =
      nsContentUtils::IsUpgradableDisplayType(contentType) &&
      StaticPrefs::security_mixed_content_upgrade_display_content();
  if (isHttpScheme && isUpgradableDisplayType) {
    *aDecision = ACCEPT;
    return NS_OK;
  }

  // The page might have set the CSP directive 'block-all-mixed-content' which
  // should block not only active mixed content loads but in fact all mixed
  // content loads, see https://www.w3.org/TR/mixed-content/#strict-checking
  // Block all non secure loads in case the CSP directive is present. Please
  // note that at this point we already know, based on |schemeSecure| that the
  // load is not secure, so we can bail out early at this point.
  if (aLoadInfo->GetBlockAllMixedContent()) {
    // log a message to the console before returning.
    nsAutoCString spec;
    nsresult rv = aContentLocation->GetSpec(spec);
    NS_ENSURE_SUCCESS(rv, rv);

    AutoTArray<nsString, 1> params;
    CopyUTF8toUTF16(spec, *params.AppendElement());

    CSP_LogLocalizedStr("blockAllMixedContent", params,
                        EmptyString(),  // aSourceFile
                        EmptyString(),  // aScriptSample
                        0,              // aLineNumber
                        0,              // aColumnNumber
                        nsIScriptError::errorFlag, "blockAllMixedContent"_ns,
                        requestingWindow->Id(),
                        !!aLoadInfo->GetOriginAttributes().mPrivateBrowsingId);
    *aDecision = REJECT_REQUEST;
    MOZ_LOG(
        sMCBLog, LogLevel::Verbose,
        ("  -> decision: Request will be rejected because the CSP directive "
         "'block-all-mixed-content' was set while trying to load data from "
         "a non-secure origin."));
    return NS_OK;
  }

  // Determine if the rootDoc is https and if the user decided to allow Mixed
  // Content
  WindowContext* topWC = requestingWindow->TopWindowContext();
  bool rootHasSecureConnection = topWC->GetIsSecure();
  bool allowMixedContent = topWC->GetAllowMixedContent();

  // When navigating an iframe, the iframe may be https
  // but its parents may not be.  Check the parents to see if any of them are
  // https. If none of the parents are https, allow the load.
  if (contentType == TYPE_SUBDOCUMENT && !rootHasSecureConnection) {
    bool httpsParentExists = false;

    RefPtr<WindowContext> curWindow = requestingWindow;
    while (!httpsParentExists && curWindow) {
      httpsParentExists = curWindow->GetIsSecure();
      curWindow = curWindow->GetParentWindowContext();
    }

    if (!httpsParentExists) {
      *aDecision = nsIContentPolicy::ACCEPT;
      return NS_OK;
    }
  }

  OriginAttributes originAttributes;
  if (loadingPrincipal) {
    originAttributes = loadingPrincipal->OriginAttributesRef();
  } else if (triggeringPrincipal) {
    originAttributes = triggeringPrincipal->OriginAttributesRef();
  }

  // At this point we know that the request is mixed content, and the only
  // question is whether we block it.  Record telemetry at this point as to
  // whether HSTS would have fixed things by making the content location
  // into an HTTPS URL.
  //
  // Note that we count this for redirects as well as primary requests. This
  // will cause some degree of double-counting, especially when mixed content
  // is not blocked (e.g., for images).  For more detail, see:
  //   https://bugzilla.mozilla.org/show_bug.cgi?id=1198572#c19
  //
  // We do not count requests aHadInsecureImageRedirect=true, since these are
  // just an artifact of the image caching system.
  bool active = (classification == eMixedScript);
  if (!aHadInsecureImageRedirect) {
    if (XRE_IsParentProcess()) {
      AccumulateMixedContentHSTS(innerContentLocation, active,
                                 originAttributes);
    } else {
      // Ask the parent process to do the same call
      mozilla::dom::ContentChild* cc =
          mozilla::dom::ContentChild::GetSingleton();
      if (cc) {
        cc->SendAccumulateMixedContentHSTS(innerContentLocation, active,
                                           originAttributes);
      }
    }
  }

  // set hasMixedContentObjectSubrequest on this object if necessary
  if (contentType == TYPE_OBJECT_SUBREQUEST && aReportError) {
    if (!StaticPrefs::security_mixed_content_block_object_subrequest()) {
      nsAutoCString messageLookUpKey(
          "LoadingMixedDisplayObjectSubrequestDeprecation");

      LogMixedContentMessage(classification, aContentLocation, topWC->Id(),
                             eUserOverride, requestingLocation,
                             messageLookUpKey);
    }
  }

  uint32_t newState = 0;
  // If the content is display content, and the pref says display content should
  // be blocked, block it.
  if (classification == eMixedDisplay) {
    if (!StaticPrefs::security_mixed_content_block_display_content() ||
        allowMixedContent) {
      *aDecision = nsIContentPolicy::ACCEPT;
      // User has overriden the pref and the root is not https;
      // mixed display content was allowed on an https subframe.
      newState |= nsIWebProgressListener::STATE_LOADED_MIXED_DISPLAY_CONTENT;
    } else {
      *aDecision = nsIContentPolicy::REJECT_REQUEST;
      MOZ_LOG(sMCBLog, LogLevel::Verbose,
              ("  -> decision: Request will be rejected because the content is "
               "display "
               "content (blocked by pref "
               "security.mixed_content.block_display_content)."));
      newState |= nsIWebProgressListener::STATE_BLOCKED_MIXED_DISPLAY_CONTENT;
    }
  } else {
    MOZ_ASSERT(classification == eMixedScript);
    // If the content is active content, and the pref says active content should
    // be blocked, block it unless the user has choosen to override the pref
    if (!StaticPrefs::security_mixed_content_block_active_content() ||
        allowMixedContent) {
      *aDecision = nsIContentPolicy::ACCEPT;
      // User has already overriden the pref and the root is not https;
      // mixed active content was allowed on an https subframe.
      newState |= nsIWebProgressListener::STATE_LOADED_MIXED_ACTIVE_CONTENT;
    } else {
      // User has not overriden the pref by Disabling protection. Reject the
      // request and update the security state.
      *aDecision = nsIContentPolicy::REJECT_REQUEST;
      MOZ_LOG(sMCBLog, LogLevel::Verbose,
              ("  -> decision: Request will be rejected because the content is "
               "active "
               "content (blocked by pref "
               "security.mixed_content.block_active_content)."));
      // The user has not overriden the pref, so make sure they still have an
      // option by calling nativeDocShell which will invoke the doorhanger
      newState |= nsIWebProgressListener::STATE_BLOCKED_MIXED_ACTIVE_CONTENT;
    }
  }

  // To avoid duplicate errors on the console, we do not report blocked
  // preloads to the console.
  if (!isPreload && aReportError) {
    LogMixedContentMessage(classification, aContentLocation, topWC->Id(),
                           (*aDecision == nsIContentPolicy::REJECT_REQUEST)
                               ? eBlocked
                               : eUserOverride,
                           requestingLocation);
  }

  // Notify the top WindowContext of the flags we've computed, and it
  // will handle updating any relevant security UI.
  topWC->AddMixedContentSecurityState(newState);
  return NS_OK;
}

bool nsMixedContentBlocker::URISafeToBeLoadedInSecureContext(nsIURI* aURI) {
  /* Returns a bool if the URI can be loaded as a sub resource safely.
   *
   * Check Protocol Flags to determine if scheme is safe to load:
   * URI_DOES_NOT_RETURN_DATA - e.g.
   *   "mailto"
   * URI_IS_LOCAL_RESOURCE - e.g.
   *   "data",
   *   "resource",
   *   "moz-icon"
   * URI_INHERITS_SECURITY_CONTEXT - e.g.
   *   "javascript"
   * URI_IS_POTENTIALLY_TRUSTWORTHY - e.g.
   *   "https",
   *   "moz-safe-about"
   *
   */
  bool schemeLocal = false;
  bool schemeNoReturnData = false;
  bool schemeInherits = false;
  bool schemeSecure = false;
  if (NS_FAILED(NS_URIChainHasFlags(
          aURI, nsIProtocolHandler::URI_IS_LOCAL_RESOURCE, &schemeLocal)) ||
      NS_FAILED(NS_URIChainHasFlags(
          aURI, nsIProtocolHandler::URI_DOES_NOT_RETURN_DATA,
          &schemeNoReturnData)) ||
      NS_FAILED(NS_URIChainHasFlags(
          aURI, nsIProtocolHandler::URI_INHERITS_SECURITY_CONTEXT,
          &schemeInherits)) ||
      NS_FAILED(NS_URIChainHasFlags(
          aURI, nsIProtocolHandler::URI_IS_POTENTIALLY_TRUSTWORTHY,
          &schemeSecure))) {
    return false;
  }

  MOZ_LOG(sMCBLog, LogLevel::Verbose,
          ("  - URISafeToBeLoadedInSecureContext:"));
  MOZ_LOG(sMCBLog, LogLevel::Verbose, ("    - schemeLocal: %i", schemeLocal));
  MOZ_LOG(sMCBLog, LogLevel::Verbose,
          ("    - schemeNoReturnData: %i", schemeNoReturnData));
  MOZ_LOG(sMCBLog, LogLevel::Verbose,
          ("    - schemeInherits: %i", schemeInherits));
  MOZ_LOG(sMCBLog, LogLevel::Verbose, ("    - schemeSecure: %i", schemeSecure));
  return (schemeLocal || schemeNoReturnData || schemeInherits || schemeSecure);
}

NS_IMETHODIMP
nsMixedContentBlocker::ShouldProcess(nsIURI* aContentLocation,
                                     nsILoadInfo* aLoadInfo,
                                     const nsACString& aMimeGuess,
                                     int16_t* aDecision) {
  if (!aContentLocation) {
    // aContentLocation may be null when a plugin is loading without an
    // associated URI resource
    if (aLoadInfo->GetExternalContentPolicyType() == TYPE_OBJECT) {
      *aDecision = ACCEPT;
      return NS_OK;
    }

    NS_SetRequestBlockingReason(aLoadInfo,
                                nsILoadInfo::BLOCKING_REASON_MIXED_BLOCKED);
    *aDecision = REJECT_REQUEST;
    return NS_ERROR_FAILURE;
  }

  return ShouldLoad(aContentLocation, aLoadInfo, aMimeGuess, aDecision);
}

// Record information on when HSTS would have made mixed content not mixed
// content (regardless of whether it was actually blocked)
void nsMixedContentBlocker::AccumulateMixedContentHSTS(
    nsIURI* aURI, bool aActive, const OriginAttributes& aOriginAttributes) {
  // This method must only be called in the parent, because
  // nsSiteSecurityService is only available in the parent
  if (!XRE_IsParentProcess()) {
    MOZ_ASSERT(false);
    return;
  }

  bool hsts;
  nsresult rv;
  nsCOMPtr<nsISiteSecurityService> sss =
      do_GetService(NS_SSSERVICE_CONTRACTID, &rv);
  if (NS_FAILED(rv)) {
    return;
  }
  rv = sss->IsSecureURI(nsISiteSecurityService::HEADER_HSTS, aURI, 0,
                        aOriginAttributes, nullptr, nullptr, &hsts);
  if (NS_FAILED(rv)) {
    return;
  }

  // states: would upgrade, would prime, hsts info cached
  // active, passive
  //
  if (!aActive) {
    if (!hsts) {
      Telemetry::Accumulate(Telemetry::MIXED_CONTENT_HSTS,
                            MCB_HSTS_PASSIVE_NO_HSTS);
    } else {
      Telemetry::Accumulate(Telemetry::MIXED_CONTENT_HSTS,
                            MCB_HSTS_PASSIVE_WITH_HSTS);
    }
  } else {
    if (!hsts) {
      Telemetry::Accumulate(Telemetry::MIXED_CONTENT_HSTS,
                            MCB_HSTS_ACTIVE_NO_HSTS);
    } else {
      Telemetry::Accumulate(Telemetry::MIXED_CONTENT_HSTS,
                            MCB_HSTS_ACTIVE_WITH_HSTS);
    }
  }
}