image/ImageCacheKey.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "ImageCacheKey.h"
   7
   8 #include <utility>
   9
  10 #include "mozilla/AntiTrackingUtils.h"
  11 #include "mozilla/HashFunctions.h"
  12 #include "mozilla/StorageAccess.h"
  13 #include "mozilla/StoragePrincipalHelper.h"
  14 #include "mozilla/Unused.h"
  15 #include "mozilla/dom/Document.h"
  16 #include "mozilla/dom/File.h"
  17 #include "mozilla/dom/ServiceWorkerManager.h"
  18 #include "mozilla/StaticPrefs_privacy.h"
  19 #include "mozilla/StorageAccess.h"
  20 #include "nsContentUtils.h"
  21 #include "nsHashKeys.h"
  22 #include "nsLayoutUtils.h"
  23 #include "nsPrintfCString.h"
  24 #include "nsString.h"
  25
  26 namespace mozilla {
  27
  28 using namespace dom;
  29
  30 namespace image {
  31
  32 ImageCacheKey::ImageCacheKey(nsIURI* aURI, const OriginAttributes& aAttrs,
  33                              Document* aDocument)
  34     : mURI(aURI),
  35       mOriginAttributes(aAttrs),
  36       mControlledDocument(GetSpecialCaseDocumentToken(aDocument)),
  37       mIsolationKey(GetIsolationKey(aDocument, aURI)) {}
  38
  39 ImageCacheKey::ImageCacheKey(const ImageCacheKey& aOther)
  40     : mURI(aOther.mURI),
  41       mOriginAttributes(aOther.mOriginAttributes),
  42       mControlledDocument(aOther.mControlledDocument),
  43       mIsolationKey(aOther.mIsolationKey),
  44       mHash(aOther.mHash) {}
  45
  46 ImageCacheKey::ImageCacheKey(ImageCacheKey&& aOther)
  47     : mURI(std::move(aOther.mURI)),
  48       mOriginAttributes(aOther.mOriginAttributes),
  49       mControlledDocument(aOther.mControlledDocument),
  50       mIsolationKey(aOther.mIsolationKey),
  51       mHash(aOther.mHash) {}
  52
  53 bool ImageCacheKey::operator==(const ImageCacheKey& aOther) const {
  54   // Don't share the image cache between a controlled document and anything
  55   // else.
  56   if (mControlledDocument != aOther.mControlledDocument) {
  57     return false;
  58   }
  59   // Don't share the image cache between two top-level documents of different
  60   // base domains.
  61   if (!mIsolationKey.Equals(aOther.mIsolationKey,
  62                             nsCaseInsensitiveCStringComparator)) {
  63     return false;
  64   }
  65   // The origin attributes always have to match.
  66   if (mOriginAttributes != aOther.mOriginAttributes) {
  67     return false;
  68   }
  69
  70   // For non-blob URIs, compare the URIs.
  71   bool equals = false;
  72   nsresult rv = mURI->Equals(aOther.mURI, &equals);
  73   return NS_SUCCEEDED(rv) && equals;
  74 }
  75
  76 void ImageCacheKey::EnsureHash() const {
  77   MOZ_ASSERT(mHash.isNothing());
  78   PLDHashNumber hash = 0;
  79
  80   // Since we frequently call Hash() several times in a row on the same
  81   // ImageCacheKey, as an optimization we compute our hash once and store it.
  82
  83   nsPrintfCString ptr("%p", mControlledDocument);
  84   nsAutoCString suffix;
  85   mOriginAttributes.CreateSuffix(suffix);
  86
  87   nsAutoCString spec;
  88   Unused << mURI->GetSpec(spec);
  89   hash = HashString(spec);
  90
  91   hash = AddToHash(hash, HashString(suffix), HashString(mIsolationKey),
  92                    HashString(ptr));
  93   mHash.emplace(hash);
  94 }
  95
  96 /* static */
  97 void* ImageCacheKey::GetSpecialCaseDocumentToken(Document* aDocument) {
  98   // Cookie-averse documents can never have storage granted to them.  Since they
  99   // may not have inner windows, they would require special handling below, so
 100   // just bail out early here.
 101   if (!aDocument || aDocument->IsCookieAverse()) {
 102     return nullptr;
 103   }
 104
 105   // For controlled documents, we cast the pointer into a void* to avoid
 106   // dereferencing it (since we only use it for comparisons).
 107   RefPtr<ServiceWorkerManager> swm = ServiceWorkerManager::GetInstance();
 108   if (swm && aDocument->GetController().isSome()) {
 109     return aDocument;
 110   }
 111
 112   return nullptr;
 113 }
 114
 115 /* static */
 116 nsCString ImageCacheKey::GetIsolationKey(Document* aDocument, nsIURI* aURI) {
 117   if (!aDocument || !aDocument->GetInnerWindow()) {
 118     return ""_ns;
 119   }
 120
 121   // Network-state isolation
 122   if (StaticPrefs::privacy_partition_network_state()) {
 123     OriginAttributes oa;
 124     StoragePrincipalHelper::GetOriginAttributesForNetworkState(aDocument, oa);
 125
 126     nsAutoCString suffix;
 127     oa.CreateSuffix(suffix);
 128
 129     return std::move(suffix);
 130   }
 131
 132   // If the window is 3rd party resource, let's see if first-party storage
 133   // access is granted for this image.
 134   if (AntiTrackingUtils::IsThirdPartyWindow(aDocument->GetInnerWindow(),
 135                                             nullptr)) {
 136     uint32_t rejectedReason = 0;
 137     Unused << rejectedReason;
 138     return StorageDisabledByAntiTracking(aDocument, aURI, rejectedReason)
 139                ? aDocument->GetBaseDomain()
 140                : ""_ns;
 141   }
 142
 143   // Another scenario is if this image is a 3rd party resource loaded by a
 144   // first party context. In this case, we should check if the nsIChannel has
 145   // been marked as tracking resource, but we don't have the channel yet at
 146   // this point.  The best approach here is to be conservative: if we are sure
 147   // that the permission is granted, let's return 0. Otherwise, let's make a
 148   // unique image cache per the top-level document eTLD+1.
 149   if (!ApproximateAllowAccessForWithoutChannel(aDocument->GetInnerWindow(),
 150                                                aURI)) {
 151     // If we are here, the image is a 3rd-party resource loaded by a first-party
 152     // context. We can just use the document's base domain as the key because it
 153     // should be the same as the top-level document's base domain.
 154     return aDocument
 155         ->GetBaseDomain();  // because we don't have anything better!
 156   }
 157
 158   return ""_ns;
 159 }
 160
 161 }  // namespace image
 162 }  // namespace mozilla