dom/base/nsDataDocumentContentPolicy.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * Content policy implementation that prevents all loads of images,
   9  * subframes, etc from documents loaded as data (eg documents loaded
  10  * via XMLHttpRequest).
  11  */
  12
  13 #include "nsContentPolicyUtils.h"
  14 #include "nsContentUtils.h"
  15 #include "nsDataDocumentContentPolicy.h"
  16 #include "nsNetUtil.h"
  17 #include "nsIProtocolHandler.h"
  18 #include "nsScriptSecurityManager.h"
  19 #include "mozilla/dom/Document.h"
  20 #include "mozilla/ScopeExit.h"
  21 #include "nsINode.h"
  22 #include "nsIURI.h"
  23
  24 using namespace mozilla;
  25
  26 NS_IMPL_ISUPPORTS(nsDataDocumentContentPolicy, nsIContentPolicy)
  27
  28 // Helper method for ShouldLoad()
  29 // Checks a URI for the given flags.  Returns true if the URI has the flags,
  30 // and false if not (or if we weren't able to tell).
  31 static bool HasFlags(nsIURI* aURI, uint32_t aURIFlags) {
  32   bool hasFlags;
  33   nsresult rv = NS_URIChainHasFlags(aURI, aURIFlags, &hasFlags);
  34   return NS_SUCCEEDED(rv) && hasFlags;
  35 }
  36
  37 // If you change DataDocumentContentPolicy, make sure to check that
  38 // CHECK_PRINCIPAL_AND_DATA in nsContentPolicyUtils is still valid.
  39 // nsContentPolicyUtils may not pass all the parameters to ShouldLoad.
  40 NS_IMETHODIMP
  41 nsDataDocumentContentPolicy::ShouldLoad(nsIURI* aContentLocation,
  42                                         nsILoadInfo* aLoadInfo,
  43                                         int16_t* aDecision) {
  44   auto setBlockingReason = mozilla::MakeScopeExit([&]() {
  45     if (NS_CP_REJECTED(*aDecision)) {
  46       NS_SetRequestBlockingReason(
  47           aLoadInfo, nsILoadInfo::BLOCKING_REASON_CONTENT_POLICY_DATA_DOCUMENT);
  48     }
  49   });
  50
  51   ExtContentPolicyType contentType = aLoadInfo->GetExternalContentPolicyType();
  52   nsCOMPtr<nsISupports> requestingContext = aLoadInfo->GetLoadingContext();
  53
  54   *aDecision = nsIContentPolicy::ACCEPT;
  55   // Look for the document.  In most cases, requestingContext is a node.
  56   nsCOMPtr<mozilla::dom::Document> doc;
  57   nsCOMPtr<nsINode> node = do_QueryInterface(requestingContext);
  58   if (node) {
  59     doc = node->OwnerDoc();
  60   } else {
  61     if (nsCOMPtr<nsPIDOMWindowOuter> window =
  62             do_QueryInterface(requestingContext)) {
  63       doc = window->GetDoc();
  64     }
  65   }
  66
  67   // DTDs are always OK to load
  68   if (!doc || contentType == ExtContentPolicy::TYPE_DTD) {
  69     return NS_OK;
  70   }
  71
  72   if (doc->IsLoadedAsData()) {
  73     bool allowed = [&] {
  74       if (!doc->IsStaticDocument()) {
  75         // If not a print/print preview doc, then nothing else is allowed for
  76         // data documents.
  77         return false;
  78       }
  79       // Let static (print/print preview) documents to load fonts and
  80       // images.
  81       switch (contentType) {
  82         case ExtContentPolicy::TYPE_IMAGE:
  83         case ExtContentPolicy::TYPE_IMAGESET:
  84         case ExtContentPolicy::TYPE_FONT:
  85         case ExtContentPolicy::TYPE_UA_FONT:
  86         // This one is a bit sketchy, but nsObjectLoadingContent takes care of
  87         // only getting here if it is an image.
  88         case ExtContentPolicy::TYPE_OBJECT:
  89           return true;
  90         default:
  91           return false;
  92       }
  93     }();
  94
  95     if (!allowed) {
  96       *aDecision = nsIContentPolicy::REJECT_TYPE;
  97       return NS_OK;
  98     }
  99   }
 100
 101   mozilla::dom::Document* docToCheckForImage = doc->GetDisplayDocument();
 102   if (!docToCheckForImage) {
 103     docToCheckForImage = doc;
 104   }
 105
 106   if (docToCheckForImage->IsBeingUsedAsImage()) {
 107     // We only allow SVG images to load content from URIs that are local and
 108     // also satisfy one of the following conditions:
 109     //  - URI inherits security context, e.g. data URIs
 110     //   OR
 111     //  - URI loadable by subsumers, e.g. blob URIs
 112     // Any URI that doesn't meet these requirements will be rejected below.
 113     if (!(HasFlags(aContentLocation,
 114                    nsIProtocolHandler::URI_IS_LOCAL_RESOURCE) &&
 115           (HasFlags(aContentLocation,
 116                     nsIProtocolHandler::URI_INHERITS_SECURITY_CONTEXT) ||
 117            HasFlags(aContentLocation,
 118                     nsIProtocolHandler::URI_LOADABLE_BY_SUBSUMERS)))) {
 119       *aDecision = nsIContentPolicy::REJECT_TYPE;
 120
 121       // Report error, if we can.
 122       if (node) {
 123         nsIPrincipal* requestingPrincipal = node->NodePrincipal();
 124         nsAutoCString sourceSpec;
 125         requestingPrincipal->GetAsciiSpec(sourceSpec);
 126         nsAutoCString targetSpec;
 127         aContentLocation->GetAsciiSpec(targetSpec);
 128         nsScriptSecurityManager::ReportError(
 129             "ExternalDataError", sourceSpec, targetSpec,
 130             requestingPrincipal->OriginAttributesRef().IsPrivateBrowsing());
 131       }
 132     } else if ((contentType == ExtContentPolicy::TYPE_IMAGE ||
 133                 contentType == ExtContentPolicy::TYPE_IMAGESET) &&
 134                doc->GetDocumentURI()) {
 135       // Check for (& disallow) recursive image-loads
 136       bool isRecursiveLoad;
 137       nsresult rv = aContentLocation->EqualsExceptRef(doc->GetDocumentURI(),
 138                                                       &isRecursiveLoad);
 139       if (NS_FAILED(rv) || isRecursiveLoad) {
 140         NS_WARNING("Refusing to recursively load image");
 141         *aDecision = nsIContentPolicy::REJECT_TYPE;
 142       }
 143     }
 144     return NS_OK;
 145   }
 146
 147   // Allow all loads for non-resource documents
 148   if (!doc->IsResourceDoc()) {
 149     return NS_OK;
 150   }
 151
 152   // For resource documents, blacklist some load types
 153   if (contentType == ExtContentPolicy::TYPE_OBJECT ||
 154       contentType == ExtContentPolicy::TYPE_DOCUMENT ||
 155       contentType == ExtContentPolicy::TYPE_SUBDOCUMENT ||
 156       contentType == ExtContentPolicy::TYPE_SCRIPT ||
 157       contentType == ExtContentPolicy::TYPE_XSLT ||
 158       contentType == ExtContentPolicy::TYPE_FETCH ||
 159       contentType == ExtContentPolicy::TYPE_WEB_MANIFEST) {
 160     *aDecision = nsIContentPolicy::REJECT_TYPE;
 161   }
 162
 163   // If you add more restrictions here, make sure to check that
 164   // CHECK_PRINCIPAL_AND_DATA in nsContentPolicyUtils is still valid.
 165   // nsContentPolicyUtils may not pass all the parameters to ShouldLoad
 166
 167   return NS_OK;
 168 }
 169
 170 NS_IMETHODIMP
 171 nsDataDocumentContentPolicy::ShouldProcess(nsIURI* aContentLocation,
 172                                            nsILoadInfo* aLoadInfo,
 173                                            int16_t* aDecision) {
 174   return ShouldLoad(aContentLocation, aLoadInfo, aDecision);
 175 }