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/* -*- 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/. */
/*
* Content policy implementation that prevents all loads of images,
* subframes, etc from documents loaded as data (eg documents loaded
* via XMLHttpRequest).
*/
#include "nsDataDocumentContentPolicy.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/dom/Document.h"
#include "nsContentPolicyUtils.h"
#include "nsContentUtils.h"
#include "nsINode.h"
#include "nsIProtocolHandler.h"
#include "nsIURI.h"
#include "nsNetUtil.h"
#include "nsScriptSecurityManager.h"
using namespace mozilla;
NS_IMPL_ISUPPORTS(nsDataDocumentContentPolicy, nsIContentPolicy)
// Helper method for ShouldLoad()
// Checks a URI for the given flags. Returns true if the URI has the flags,
// and false if not (or if we weren't able to tell).
static bool HasFlags(nsIURI* aURI, uint32_t aURIFlags) {
bool hasFlags;
nsresult rv = NS_URIChainHasFlags(aURI, aURIFlags, &hasFlags);
return NS_SUCCEEDED(rv) && hasFlags;
}
// If you change DataDocumentContentPolicy, make sure to check that
// CHECK_PRINCIPAL_AND_DATA in nsContentPolicyUtils is still valid.
// nsContentPolicyUtils may not pass all the parameters to ShouldLoad.
NS_IMETHODIMP
nsDataDocumentContentPolicy::ShouldLoad(nsIURI* aContentLocation,
nsILoadInfo* aLoadInfo,
int16_t* aDecision) {
auto setBlockingReason = mozilla::MakeScopeExit([&]() {
if (NS_CP_REJECTED(*aDecision)) {
NS_SetRequestBlockingReason(
aLoadInfo, nsILoadInfo::BLOCKING_REASON_CONTENT_POLICY_DATA_DOCUMENT);
}
});
ExtContentPolicyType contentType = aLoadInfo->GetExternalContentPolicyType();
nsCOMPtr<nsISupports> requestingContext = aLoadInfo->GetLoadingContext();
*aDecision = nsIContentPolicy::ACCEPT;
// Look for the document. In most cases, requestingContext is a node.
nsCOMPtr<mozilla::dom::Document> doc;
nsCOMPtr<nsINode> node = do_QueryInterface(requestingContext);
if (node) {
doc = node->OwnerDoc();
} else {
if (nsCOMPtr<nsPIDOMWindowOuter> window =
do_QueryInterface(requestingContext)) {
doc = window->GetDoc();
}
}
// DTDs are always OK to load
if (!doc || contentType == ExtContentPolicy::TYPE_DTD) {
return NS_OK;
}
if (doc->IsLoadedAsData()) {
bool allowed = [&] {
if (!doc->IsStaticDocument()) {
// If not a print/print preview doc, then nothing else is allowed for
// data documents.
return false;
}
// Let static (print/print preview) documents to load fonts and
// images.
switch (contentType) {
case ExtContentPolicy::TYPE_IMAGE:
case ExtContentPolicy::TYPE_IMAGESET:
case ExtContentPolicy::TYPE_FONT:
case ExtContentPolicy::TYPE_UA_FONT:
// This one is a bit sketchy, but nsObjectLoadingContent takes care of
// only getting here if it is an image.
case ExtContentPolicy::TYPE_OBJECT:
return true;
default:
return false;
}
}();
if (!allowed) {
*aDecision = nsIContentPolicy::REJECT_TYPE;
return NS_OK;
}
}
mozilla::dom::Document* docToCheckForImage = doc->GetDisplayDocument();
if (!docToCheckForImage) {
docToCheckForImage = doc;
}
if (docToCheckForImage->IsBeingUsedAsImage()) {
// We only allow SVG images to load content from URIs that are local and
// also satisfy one of the following conditions:
// - URI inherits security context, e.g. data URIs
// OR
// - URI loadable by subsumers, e.g. blob URIs
// Any URI that doesn't meet these requirements will be rejected below.
if (!(HasFlags(aContentLocation,
nsIProtocolHandler::URI_IS_LOCAL_RESOURCE) &&
(HasFlags(aContentLocation,
nsIProtocolHandler::URI_INHERITS_SECURITY_CONTEXT) ||
HasFlags(aContentLocation,
nsIProtocolHandler::URI_LOADABLE_BY_SUBSUMERS)))) {
*aDecision = nsIContentPolicy::REJECT_TYPE;
// Report error, if we can.
if (node) {
nsIPrincipal* requestingPrincipal = node->NodePrincipal();
nsAutoCString sourceSpec;
requestingPrincipal->GetAsciiSpec(sourceSpec);
nsAutoCString targetSpec;
aContentLocation->GetAsciiSpec(targetSpec);
nsScriptSecurityManager::ReportError(
"ExternalDataError", sourceSpec, targetSpec,
requestingPrincipal->OriginAttributesRef().IsPrivateBrowsing());
}
} else if ((contentType == ExtContentPolicy::TYPE_IMAGE ||
contentType == ExtContentPolicy::TYPE_IMAGESET) &&
doc->GetDocumentURI()) {
// Check for (& disallow) recursive image-loads
bool isRecursiveLoad;
nsresult rv = aContentLocation->EqualsExceptRef(doc->GetDocumentURI(),
&isRecursiveLoad);
if (NS_FAILED(rv) || isRecursiveLoad) {
NS_WARNING("Refusing to recursively load image");
*aDecision = nsIContentPolicy::REJECT_TYPE;
}
}
return NS_OK;
}
// Allow all loads for non-resource documents
if (!doc->IsResourceDoc()) {
return NS_OK;
}
// For resource documents, blacklist some load types
if (contentType == ExtContentPolicy::TYPE_OBJECT ||
contentType == ExtContentPolicy::TYPE_DOCUMENT ||
contentType == ExtContentPolicy::TYPE_SUBDOCUMENT ||
contentType == ExtContentPolicy::TYPE_SCRIPT ||
contentType == ExtContentPolicy::TYPE_XSLT ||
contentType == ExtContentPolicy::TYPE_FETCH ||
contentType == ExtContentPolicy::TYPE_WEB_MANIFEST) {
*aDecision = nsIContentPolicy::REJECT_TYPE;
}
// If you add more restrictions here, make sure to check that
// CHECK_PRINCIPAL_AND_DATA in nsContentPolicyUtils is still valid.
// nsContentPolicyUtils may not pass all the parameters to ShouldLoad
return NS_OK;
}
NS_IMETHODIMP
nsDataDocumentContentPolicy::ShouldProcess(nsIURI* aContentLocation,
nsILoadInfo* aLoadInfo,
int16_t* aDecision) {
return ShouldLoad(aContentLocation, aLoadInfo, aDecision);
}
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