Source/WebCore/loader/PolicyChecker.cpp

/*
 * Copyright (C) 2006-2016 Apple Inc. All rights reserved.
 * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer. 
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution. 
 * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "PolicyChecker.h"

#include "ContentFilter.h"
#include "ContentSecurityPolicy.h"
#include "DOMWindow.h"
#include "DocumentLoader.h"
#include "Event.h"
#include "EventNames.h"
#include "FormState.h"
#include "Frame.h"
#include "FrameLoader.h"
#include "FrameLoaderClient.h"
#include "HTMLFormElement.h"
#include "HTMLFrameOwnerElement.h"
#include "HTMLPlugInElement.h"

#if USE(QUICK_LOOK)
#include "QuickLook.h"
#endif

namespace WebCore {

static bool isAllowedByContentSecurityPolicy(const URL& url, const Element* ownerElement, bool didReceiveRedirectResponse)
{
    if (!ownerElement)
        return true;
    // Elements in user agent show tree should load whatever the embedding document policy is.
    if (ownerElement->isInUserAgentShadowTree())
        return true;

    auto redirectResponseReceived = didReceiveRedirectResponse ? ContentSecurityPolicy::RedirectResponseReceived::Yes : ContentSecurityPolicy::RedirectResponseReceived::No;

    ASSERT(ownerElement->document().contentSecurityPolicy());
    if (is<HTMLPlugInElement>(ownerElement))
        return ownerElement->document().contentSecurityPolicy()->allowObjectFromSource(url, redirectResponseReceived);
    return ownerElement->document().contentSecurityPolicy()->allowChildFrameFromSource(url, redirectResponseReceived);
}

PolicyChecker::PolicyChecker(Frame& frame)
    : m_frame(frame)
    , m_delegateIsDecidingNavigationPolicy(false)
    , m_delegateIsHandlingUnimplementablePolicy(false)
    , m_loadType(FrameLoadType::Standard)
{
}

void PolicyChecker::checkNavigationPolicy(const ResourceRequest& newRequest, bool didReceiveRedirectResponse, NavigationPolicyDecisionFunction function)
{
    checkNavigationPolicy(newRequest, didReceiveRedirectResponse, m_frame.loader().activeDocumentLoader(), nullptr, WTFMove(function));
}

void PolicyChecker::checkNavigationPolicy(const ResourceRequest& request, bool didReceiveRedirectResponse, DocumentLoader* loader, FormState* formState, NavigationPolicyDecisionFunction function)
{
    NavigationAction action = loader->triggeringAction();
    if (action.isEmpty()) {
        action = NavigationAction { *m_frame.document(), request, NavigationType::Other, loader->shouldOpenExternalURLsPolicyToPropagate() };
        loader->setTriggeringAction(action);
    }

    // Don't ask more than once for the same request or if we are loading an empty URL.
    // This avoids confusion on the part of the client.
    if (equalIgnoringHeaderFields(request, loader->lastCheckedRequest()) || (!request.isNull() && request.url().isEmpty())) {
        function(request, 0, true);
        loader->setLastCheckedRequest(request);
        return;
    }

    // We are always willing to show alternate content for unreachable URLs;
    // treat it like a reload so it maintains the right state for b/f list.
    auto& substituteData = loader->substituteData();
    if (substituteData.isValid() && !substituteData.failingURL().isEmpty()) {
        bool shouldContinue = true;
#if ENABLE(CONTENT_FILTERING)
        shouldContinue = ContentFilter::continueAfterSubstituteDataRequest(*m_frame.loader().activeDocumentLoader(), substituteData);
#endif
        if (isBackForwardLoadType(m_loadType))
            m_loadType = FrameLoadType::Reload;
        function(request, 0, shouldContinue);
        return;
    }

    if (!isAllowedByContentSecurityPolicy(request.url(), m_frame.ownerElement(), didReceiveRedirectResponse)) {
        if (m_frame.ownerElement()) {
            // Fire a load event (even though we were blocked by CSP) as timing attacks would otherwise
            // reveal that the frame was blocked. This way, it looks like any other cross-origin page load.
            m_frame.ownerElement()->dispatchEvent(Event::create(eventNames().loadEvent, false, false));
        }
        function(request, 0, false);
        return;
    }

    loader->setLastCheckedRequest(request);

    m_callback.set(request, formState, WTFMove(function));

#if USE(QUICK_LOOK)
    // Always allow QuickLook-generated URLs based on the protocol scheme.
    if (!request.isNull() && isQuickLookPreviewURL(request.url())) {
        continueAfterNavigationPolicy(PolicyUse);
        return;
    }
#endif

#if ENABLE(CONTENT_FILTERING)
    if (m_contentFilterUnblockHandler.canHandleRequest(request)) {
        RefPtr<Frame> frame { &m_frame };
        m_contentFilterUnblockHandler.requestUnblockAsync([frame](bool unblocked) {
            if (unblocked)
                frame->loader().reload();
        });
        continueAfterNavigationPolicy(PolicyIgnore);
        return;
    }
    m_contentFilterUnblockHandler = { };
#endif

    m_delegateIsDecidingNavigationPolicy = true;
    m_suggestedFilename = action.downloadAttribute().isEmpty() ? nullAtom() : action.downloadAttribute();
    m_frame.loader().client().dispatchDecidePolicyForNavigationAction(action, request, formState, [this](PolicyAction action) {
        continueAfterNavigationPolicy(action);
    });
    m_delegateIsDecidingNavigationPolicy = false;
}

void PolicyChecker::checkNewWindowPolicy(const NavigationAction& action, const ResourceRequest& request, FormState* formState, const String& frameName, NewWindowPolicyDecisionFunction function)
{
    if (m_frame.document() && m_frame.document()->isSandboxed(SandboxPopups))
        return continueAfterNavigationPolicy(PolicyIgnore);

    if (!DOMWindow::allowPopUp(m_frame))
        return continueAfterNavigationPolicy(PolicyIgnore);

    m_callback.set(request, formState, frameName, action, WTFMove(function));
    m_frame.loader().client().dispatchDecidePolicyForNewWindowAction(action, request, formState, frameName, [this](PolicyAction action) {
        continueAfterNewWindowPolicy(action);
    });
}

void PolicyChecker::checkContentPolicy(const ResourceResponse& response, ContentPolicyDecisionFunction function)
{
    m_callback.set(WTFMove(function));
    m_frame.loader().client().dispatchDecidePolicyForResponse(response, m_frame.loader().activeDocumentLoader()->request(), [this](PolicyAction action) {
        continueAfterContentPolicy(action);
    });
}

void PolicyChecker::cancelCheck()
{
    m_frame.loader().client().cancelPolicyCheck();
    m_callback = { };
}

void PolicyChecker::stopCheck()
{
    m_frame.loader().client().cancelPolicyCheck();
    PolicyCallback callback = WTFMove(m_callback);
    callback.cancel();
}

void PolicyChecker::cannotShowMIMEType(const ResourceResponse& response)
{
    handleUnimplementablePolicy(m_frame.loader().client().cannotShowMIMETypeError(response));
}

void PolicyChecker::continueLoadAfterWillSubmitForm(PolicyAction)
{
    // See header file for an explaination of why this function
    // isn't like the others.
    m_frame.loader().continueLoadAfterWillSubmitForm();
}

void PolicyChecker::continueAfterNavigationPolicy(PolicyAction policy)
{
    PolicyCallback callback = WTFMove(m_callback);

    bool shouldContinue = policy == PolicyUse;

    switch (policy) {
        case PolicyIgnore:
            callback.clearRequest();
            break;
        case PolicyDownload: {
            ResourceRequest request = callback.request();
            m_frame.loader().setOriginalURLForDownloadRequest(request);
            m_frame.loader().client().startDownload(request, m_suggestedFilename);
            callback.clearRequest();
            break;
        }
        case PolicyUse: {
            ResourceRequest request(callback.request());

            if (!m_frame.loader().client().canHandleRequest(request)) {
                handleUnimplementablePolicy(m_frame.loader().client().cannotShowURLError(callback.request()));
                callback.clearRequest();
                shouldContinue = false;
            }
            break;
        }
    }

    callback.call(shouldContinue);
}

void PolicyChecker::continueAfterNewWindowPolicy(PolicyAction policy)
{
    PolicyCallback callback = WTFMove(m_callback);

    switch (policy) {
        case PolicyIgnore:
            callback.clearRequest();
            break;
        case PolicyDownload:
            m_frame.loader().client().startDownload(callback.request());
            callback.clearRequest();
            break;
        case PolicyUse:
            break;
    }

    callback.call(policy == PolicyUse);
}

void PolicyChecker::continueAfterContentPolicy(PolicyAction policy)
{
    PolicyCallback callback = WTFMove(m_callback);
    callback.call(policy);
}

void PolicyChecker::handleUnimplementablePolicy(const ResourceError& error)
{
    m_delegateIsHandlingUnimplementablePolicy = true;
    m_frame.loader().client().dispatchUnableToImplementPolicy(error);
    m_delegateIsHandlingUnimplementablePolicy = false;
}

} // namespace WebCore