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, CORSMode aCORSMode,
  33                              const OriginAttributes& aAttrs,
  34                              Document* aDocument)
  35     : mURI(aURI),
  36       mOriginAttributes(aAttrs),
  37       mControlledDocument(GetSpecialCaseDocumentToken(aDocument)),
  38       mIsolationKey(GetIsolationKey(aDocument, aURI)),
  39       mCORSMode(aCORSMode) {}
  40
  41 ImageCacheKey::ImageCacheKey(const ImageCacheKey& aOther)
  42     : mURI(aOther.mURI),
  43       mOriginAttributes(aOther.mOriginAttributes),
  44       mControlledDocument(aOther.mControlledDocument),
  45       mIsolationKey(aOther.mIsolationKey),
  46       mHash(aOther.mHash),
  47       mCORSMode(aOther.mCORSMode) {}
  48
  49 ImageCacheKey::ImageCacheKey(ImageCacheKey&& aOther)
  50     : mURI(std::move(aOther.mURI)),
  51       mOriginAttributes(aOther.mOriginAttributes),
  52       mControlledDocument(aOther.mControlledDocument),
  53       mIsolationKey(aOther.mIsolationKey),
  54       mHash(aOther.mHash),
  55       mCORSMode(aOther.mCORSMode) {}
  56
  57 bool ImageCacheKey::operator==(const ImageCacheKey& aOther) const {
  58   // Don't share the image cache between a controlled document and anything
  59   // else.
  60   if (mControlledDocument != aOther.mControlledDocument) {
  61     return false;
  62   }
  63   // Don't share the image cache between two top-level documents of different
  64   // base domains.
  65   if (!mIsolationKey.Equals(aOther.mIsolationKey,
  66                             nsCaseInsensitiveCStringComparator)) {
  67     return false;
  68   }
  69   // The origin attributes always have to match.
  70   if (mOriginAttributes != aOther.mOriginAttributes) {
  71     return false;
  72   }
  73
  74   if (mCORSMode != aOther.mCORSMode) {
  75     return false;
  76   }
  77
  78   // For non-blob URIs, compare the URIs.
  79   bool equals = false;
  80   nsresult rv = mURI->Equals(aOther.mURI, &equals);
  81   return NS_SUCCEEDED(rv) && equals;
  82 }
  83
  84 void ImageCacheKey::EnsureHash() const {
  85   MOZ_ASSERT(mHash.isNothing());
  86   PLDHashNumber hash = 0;
  87
  88   // Since we frequently call Hash() several times in a row on the same
  89   // ImageCacheKey, as an optimization we compute our hash once and store it.
  90
  91   nsPrintfCString ptr("%p", mControlledDocument);
  92   nsAutoCString suffix;
  93   mOriginAttributes.CreateSuffix(suffix);
  94
  95   nsAutoCString spec;
  96   Unused << mURI->GetSpec(spec);
  97   hash = HashString(spec);
  98
  99   hash = AddToHash(hash, HashString(suffix), HashString(mIsolationKey),
 100                    HashString(ptr));
 101   mHash.emplace(hash);
 102 }
 103
 104 /* static */
 105 void* ImageCacheKey::GetSpecialCaseDocumentToken(Document* aDocument) {
 106   // Cookie-averse documents can never have storage granted to them.  Since they
 107   // may not have inner windows, they would require special handling below, so
 108   // just bail out early here.
 109   if (!aDocument || aDocument->IsCookieAverse()) {
 110     return nullptr;
 111   }
 112
 113   // For controlled documents, we cast the pointer into a void* to avoid
 114   // dereferencing it (since we only use it for comparisons).
 115   RefPtr<ServiceWorkerManager> swm = ServiceWorkerManager::GetInstance();
 116   if (swm && aDocument->GetController().isSome()) {
 117     return aDocument;
 118   }
 119
 120   return nullptr;
 121 }
 122
 123 /* static */
 124 nsCString ImageCacheKey::GetIsolationKey(Document* aDocument, nsIURI* aURI) {
 125   if (!aDocument || !aDocument->GetInnerWindow()) {
 126     return ""_ns;
 127   }
 128
 129   // Network-state isolation
 130   if (StaticPrefs::privacy_partition_network_state()) {
 131     OriginAttributes oa;
 132     StoragePrincipalHelper::GetOriginAttributesForNetworkState(aDocument, oa);
 133
 134     nsAutoCString suffix;
 135     oa.CreateSuffix(suffix);
 136
 137     return std::move(suffix);
 138   }
 139
 140   // If the window is 3rd party resource, let's see if first-party storage
 141   // access is granted for this image.
 142   if (AntiTrackingUtils::IsThirdPartyWindow(aDocument->GetInnerWindow(),
 143                                             nullptr)) {
 144     uint32_t rejectedReason = 0;
 145     Unused << rejectedReason;
 146     return ShouldAllowAccessFor(aDocument->GetInnerWindow(), aURI,
 147                                 &rejectedReason)
 148                ? ""_ns
 149                : aDocument->GetBaseDomain();
 150   }
 151
 152   // Another scenario is if this image is a 3rd party resource loaded by a
 153   // first party context. In this case, we should check if the nsIChannel has
 154   // been marked as tracking resource, but we don't have the channel yet at
 155   // this point.  The best approach here is to be conservative: if we are sure
 156   // that the permission is granted, let's return 0. Otherwise, let's make a
 157   // unique image cache per the top-level document eTLD+1.
 158   if (!ApproximateAllowAccessForWithoutChannel(aDocument->GetInnerWindow(),
 159                                                aURI)) {
 160     // If we are here, the image is a 3rd-party resource loaded by a first-party
 161     // context. We can just use the document's base domain as the key because it
 162     // should be the same as the top-level document's base domain.
 163     return aDocument
 164         ->GetBaseDomain();  // because we don't have anything better!
 165   }
 166
 167   return ""_ns;
 168 }
 169
 170 }  // namespace image
 171 }  // namespace mozilla