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                                         const nsACString& aMimeGuess,
  44                                         int16_t* aDecision) {
  45   auto setBlockingReason = mozilla::MakeScopeExit([&]() {
  46     if (NS_CP_REJECTED(*aDecision)) {
  47       NS_SetRequestBlockingReason(
  48           aLoadInfo, nsILoadInfo::BLOCKING_REASON_CONTENT_POLICY_DATA_DOCUMENT);
  49     }
  50   });
  51
  52   ExtContentPolicyType contentType = aLoadInfo->GetExternalContentPolicyType();
  53   nsCOMPtr<nsISupports> requestingContext = aLoadInfo->GetLoadingContext();
  54
  55   *aDecision = nsIContentPolicy::ACCEPT;
  56   // Look for the document.  In most cases, requestingContext is a node.
  57   nsCOMPtr<mozilla::dom::Document> doc;
  58   nsCOMPtr<nsINode> node = do_QueryInterface(requestingContext);
  59   if (node) {
  60     doc = node->OwnerDoc();
  61   } else {
  62     if (nsCOMPtr<nsPIDOMWindowOuter> window =
  63             do_QueryInterface(requestingContext)) {
  64       doc = window->GetDoc();
  65     }
  66   }
  67
  68   // DTDs are always OK to load
  69   if (!doc || contentType == ExtContentPolicy::TYPE_DTD) {
  70     return NS_OK;
  71   }
  72
  73   if (doc->IsLoadedAsData()) {
  74     bool allowed = [&] {
  75       if (!doc->IsStaticDocument()) {
  76         // If not a print/print preview doc, then nothing else is allowed for
  77         // data documents.
  78         return false;
  79       }
  80       // Let static (print/print preview) documents to load fonts and
  81       // images.
  82       switch (contentType) {
  83         case ExtContentPolicy::TYPE_IMAGE:
  84         case ExtContentPolicy::TYPE_IMAGESET:
  85         case ExtContentPolicy::TYPE_FONT:
  86         case ExtContentPolicy::TYPE_UA_FONT:
  87         // This one is a bit sketchy, but nsObjectLoadingContent takes care of
  88         // only getting here if it is an image.
  89         case ExtContentPolicy::TYPE_OBJECT:
  90           return true;
  91         default:
  92           return false;
  93       }
  94     }();
  95
  96     if (!allowed) {
  97       *aDecision = nsIContentPolicy::REJECT_TYPE;
  98       return NS_OK;
  99     }
 100   }
 101
 102   mozilla::dom::Document* docToCheckForImage = doc->GetDisplayDocument();
 103   if (!docToCheckForImage) {
 104     docToCheckForImage = doc;
 105   }
 106
 107   if (docToCheckForImage->IsBeingUsedAsImage()) {
 108     // We only allow SVG images to load content from URIs that are local and
 109     // also satisfy one of the following conditions:
 110     //  - URI inherits security context, e.g. data URIs
 111     //   OR
 112     //  - URI loadable by subsumers, e.g. blob URIs
 113     // Any URI that doesn't meet these requirements will be rejected below.
 114     if (!(HasFlags(aContentLocation,
 115                    nsIProtocolHandler::URI_IS_LOCAL_RESOURCE) &&
 116           (HasFlags(aContentLocation,
 117                     nsIProtocolHandler::URI_INHERITS_SECURITY_CONTEXT) ||
 118            HasFlags(aContentLocation,
 119                     nsIProtocolHandler::URI_LOADABLE_BY_SUBSUMERS)))) {
 120       *aDecision = nsIContentPolicy::REJECT_TYPE;
 121
 122       // Report error, if we can.
 123       if (node) {
 124         nsIPrincipal* requestingPrincipal = node->NodePrincipal();
 125         nsAutoCString sourceSpec;
 126         requestingPrincipal->GetAsciiSpec(sourceSpec);
 127         nsAutoCString targetSpec;
 128         aContentLocation->GetAsciiSpec(targetSpec);
 129         nsScriptSecurityManager::ReportError(
 130             "ExternalDataError", sourceSpec, targetSpec,
 131             requestingPrincipal->OriginAttributesRef().mPrivateBrowsingId > 0);
 132       }
 133     } else if ((contentType == ExtContentPolicy::TYPE_IMAGE ||
 134                 contentType == ExtContentPolicy::TYPE_IMAGESET) &&
 135                doc->GetDocumentURI()) {
 136       // Check for (& disallow) recursive image-loads
 137       bool isRecursiveLoad;
 138       nsresult rv = aContentLocation->EqualsExceptRef(doc->GetDocumentURI(),
 139                                                       &isRecursiveLoad);
 140       if (NS_FAILED(rv) || isRecursiveLoad) {
 141         NS_WARNING("Refusing to recursively load image");
 142         *aDecision = nsIContentPolicy::REJECT_TYPE;
 143       }
 144     }
 145     return NS_OK;
 146   }
 147
 148   // Allow all loads for non-resource documents
 149   if (!doc->IsResourceDoc()) {
 150     return NS_OK;
 151   }
 152
 153   // For resource documents, blacklist some load types
 154   if (contentType == ExtContentPolicy::TYPE_OBJECT ||
 155       contentType == ExtContentPolicy::TYPE_DOCUMENT ||
 156       contentType == ExtContentPolicy::TYPE_SUBDOCUMENT ||
 157       contentType == ExtContentPolicy::TYPE_SCRIPT ||
 158       contentType == ExtContentPolicy::TYPE_XSLT ||
 159       contentType == ExtContentPolicy::TYPE_FETCH ||
 160       contentType == ExtContentPolicy::TYPE_WEB_MANIFEST) {
 161     *aDecision = nsIContentPolicy::REJECT_TYPE;
 162   }
 163
 164   // If you add more restrictions here, make sure to check that
 165   // CHECK_PRINCIPAL_AND_DATA in nsContentPolicyUtils is still valid.
 166   // nsContentPolicyUtils may not pass all the parameters to ShouldLoad
 167
 168   return NS_OK;
 169 }
 170
 171 NS_IMETHODIMP
 172 nsDataDocumentContentPolicy::ShouldProcess(nsIURI* aContentLocation,
 173                                            nsILoadInfo* aLoadInfo,
 174                                            const nsACString& aMimeGuess,
 175                                            int16_t* aDecision) {
 176   return ShouldLoad(aContentLocation, aLoadInfo, aMimeGuess, aDecision);
 177 }