Add CookieSettingOverride to allow ABA embeds to send cookies using CORS

For now, this functionality is gated behind a base::Feature that is
disabled by default.

This CL does *not* interact with SameSite semantics, and still
maintains that only SameSite=None cookies are allowed in ABA contexts.
This exception is for 3P cookie blocking only.

This exception cannot be applied to cookies accessed via JS.

Bug: 1513690
Change-Id: Id5964224403b7eb9aab69cebe69095530da5baa5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5147868
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Commit-Queue: Dylan Cutler <dylancutler@google.com>
Reviewed-by: Chris Fredrickson <cfredric@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1243468}

components/content_settings/core/common/cookie_settings_base.cc

@@ -26,6 +26,20 @@
 
 namespace content_settings {
 
+namespace {
+
+bool IsAllowedByCORS(const net::CookieSettingOverrides& overrides,
+                     const GURL& request_url,
+                     const GURL& first_party_url) {
+  return overrides.Has(
+             net::CookieSettingOverride::kCrossSiteCredentialedWithCORS) &&
+         base::FeatureList::IsEnabled(
+             net::features::kThirdPartyCookieTopLevelSiteCorsException) &&
+         net::SchemefulSite(request_url) == net::SchemefulSite(first_party_url);
+}
+
+}  // namespace
+
 bool CookieSettingsBase::storage_access_api_grants_unpartitioned_storage_ =
     false;
 
@@ -365,6 +379,14 @@ CookieSettingsBase::GetCookieSettingInternal(
                                    ACCESS_ALLOWED_3PCD_HEURISTICS_GRANT);
   }
 
+  if (block_third && IsAllowedByCORS(overrides, request_url, first_party_url)) {
+    block_third = false;
+    third_party_cookie_allow_mechanism =
+        ThirdPartyCookieAllowMechanism::kAllowByCORSException;
+    FireStorageAccessHistogram(
+        net::cookie_util::StorageAccessResult::ACCESS_ALLOWED_CORS_EXCEPTION);
+  }
+
   if (block_third) {
     bool has_storage_access_opt_in =
         ShouldConsiderStorageAccessGrants(overrides);

components/content_settings/core/common/cookie_settings_base.h

@@ -98,7 +98,8 @@ class CookieSettingsBase {
     kAllowBy3PCDHeuristics = 5,
     kAllowByStorageAccess = 6,
     kAllowByTopLevelStorageAccess = 7,
-    kMaxValue = kAllowByTopLevelStorageAccess,
+    kAllowByCORSException = 8,
+    kMaxValue = kAllowByCORSException,
   };
 
   class CookieSettingWithMetadata {

content/browser/network/http_cookie_browsertest.cc

@@ -575,8 +575,12 @@ class ThirdPartyCookiesBlockedHttpCookieBrowserTest
  public:
   ThirdPartyCookiesBlockedHttpCookieBrowserTest()
       : https_server_(net::EmbeddedTestServer::TYPE_HTTPS) {
-    feature_list_.InitAndEnableFeature(
-        net::features::kForceThirdPartyCookieBlocking);
+    feature_list_.InitWithFeatures(
+        {
+            net::features::kForceThirdPartyCookieBlocking,
+            net::features::kThirdPartyCookieTopLevelSiteCorsException,
+        },
+        {});
   }
 
   ~ThirdPartyCookiesBlockedHttpCookieBrowserTest() override = default;
@@ -615,19 +619,21 @@ class ThirdPartyCookiesBlockedHttpCookieBrowserTest
     return EvalJs(frame, JsReplace(script, url)).ExtractString();
   }
 
-  std::string FetchWithCredentials(RenderFrameHost* frame, const GURL& url) {
+  EvalJsResult Fetch(RenderFrameHost* frame,
+                     const GURL& url,
+                     const std::string& mode,
+                     const std::string& credentials) {
     constexpr char script[] = R"JS(
-      fetch($1, { credentials : 'include' }
-      ).then((result) => result.text());
+      fetch($1, {mode: $2, credentials: $3}).then(result => result.text());
     )JS";
-    return EvalJs(frame, JsReplace(script, url)).ExtractString();
+    return EvalJs(frame, JsReplace(script, url, mode, credentials));
   }
 
   bool CookieStoreEmpty(RenderFrameHost* frame) {
     constexpr char script[] = R"JS(
           (async () => {
             let cookies = await cookieStore.getAll();
-            return cookies.length == 0 ? true : false;
+            return cookies.length == 0;
           })();
       )JS";
     return EvalJs(frame, script).ExtractBool();
@@ -832,10 +838,51 @@ IN_PROC_BROWSER_TEST_F(
   // check if cookies are present on the request.
   ASSERT_TRUE(NavigateToURL(web_contents(), EchoCookiesUrl(kHostB)));
 
-  EXPECT_TRUE(FetchWithCredentials(
-                  web_contents()->GetPrimaryMainFrame(),
-                  https_server()->GetURL(kHostA, kEchoCookiesWithCorsPath))
-                  .empty());
+  EXPECT_THAT(Fetch(web_contents()->GetPrimaryMainFrame(),
+                    https_server()->GetURL(kHostA, kEchoCookiesWithCorsPath),
+                    "cors", "include")
+                  .ExtractString(),
+              net::CookieStringIs(IsEmpty()));
+}
+
+IN_PROC_BROWSER_TEST_F(ThirdPartyCookiesBlockedHttpCookieBrowserTest,
+                       TopLevelSiteCorsException) {
+  // Set and confirm SameSite=None cookie on Site A.
+  ASSERT_TRUE(SetCookie(
+      web_contents()->GetBrowserContext(), https_server()->GetURL(kHostA, "/"),
+      base::StrCat({kSameSiteNoneCookieName, "=1;Secure;SameSite=None;"})));
+
+  ASSERT_TRUE(NavigateToURL(web_contents(), EchoCookiesUrl(kHostA)));
+
+  // Embed an iframe containing A in B.
+  ASSERT_EQ(content::ArrangeFramesAndGetContentFromLeaf(
+                web_contents(), https_server(), base::StrCat({kHostA, "(%s)"}),
+                {0}, EchoCookiesUrl(kHostB)),
+            "None");
+
+  // Test that a subresource request from B to A can use cookies if it is
+  // in CORS mode and includes credentials.
+  EXPECT_EQ(Fetch(ChildFrameAt(web_contents()->GetPrimaryMainFrame(), 0),
+                  https_server()->GetURL(kHostA, kEchoCookiesWithCorsPath),
+                  "cors", "include")
+                .ExtractString(),
+            base::StrCat({kSameSiteNoneCookieName, "=1"}));
+
+  // Test that a subresource request from B to A cannot use cookies if it is
+  // in CORS mode and omits credentials.
+  EXPECT_THAT(Fetch(ChildFrameAt(web_contents()->GetPrimaryMainFrame(), 0),
+                    https_server()->GetURL(kHostA, kEchoCookiesWithCorsPath),
+                    "cors", "omit")
+                  .ExtractString(),
+              net::CookieStringIs(IsEmpty()));
+
+  // Test that a subresource request from B to A cannot use cookies if it is
+  // in no-cors mode.
+  EXPECT_THAT(Fetch(ChildFrameAt(web_contents()->GetPrimaryMainFrame(), 0),
+                    https_server()->GetURL(kHostA, kEchoCookiesWithCorsPath),
+                    "no-cors", "include")
+                  .ExtractString(),
+              net::CookieStringIs(IsEmpty()));
 }
 
 INSTANTIATE_TEST_SUITE_P(/* no label */,

net/base/features.cc

@@ -465,6 +465,10 @@ BASE_FEATURE(kForceThirdPartyCookieBlocking,
              "ForceThirdPartyCookieBlockingEnabled",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
+BASE_FEATURE(kThirdPartyCookieTopLevelSiteCorsException,
+             "ThirdPartyCookieTopLevelSiteCorsException",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
 BASE_FEATURE(kEnableEarlyHintsOnHttp11,
              "EnableEarlyHintsOnHttp11",
              base::FEATURE_DISABLED_BY_DEFAULT);

net/base/features.h

@@ -467,6 +467,11 @@ NET_EXPORT BASE_DECLARE_FEATURE(kTimeLimitedInsecureCookies);
 // Enables enabling third-party cookie blocking from the command line.
 NET_EXPORT BASE_DECLARE_FEATURE(kForceThirdPartyCookieBlocking);
 
+// Enables an exception for third-party cookie blocking when the request is
+// same-site with the top-level document, opted into CORS, but embedded in a
+// cross-site context.
+NET_EXPORT BASE_DECLARE_FEATURE(kThirdPartyCookieTopLevelSiteCorsException);
+
 // Enables Early Hints on HTTP/1.1.
 NET_EXPORT BASE_DECLARE_FEATURE(kEnableEarlyHintsOnHttp11);
 

net/cookies/cookie_setting_override.h

@@ -29,8 +29,13 @@ enum class CookieSettingOverride {
   // backs 3PC accesses granted via 3PC deprecation trial.
   kSkipTPCDSupport = 3,
   kSkipTPCDMetadataGrant = 4,
+  // Corresponds to checks that may grant 3PCs when a request opts into
+  // credentials and CORS protection.
+  // One example are subresource requests that are same-site with the top-level
+  // site but originate from a cross-site embed.
+  kCrossSiteCredentialedWithCORS = 5,
 
-  kMaxValue = kSkipTPCDMetadataGrant,
+  kMaxValue = kCrossSiteCredentialedWithCORS,
 };
 
 using CookieSettingOverrides = base::EnumSet<CookieSettingOverride,

net/cookies/cookie_util.h

@@ -49,7 +49,8 @@ enum class StorageAccessResult {
   ACCESS_ALLOWED_3PCD = 5,
   ACCESS_ALLOWED_3PCD_METADATA_GRANT = 6,
   ACCESS_ALLOWED_3PCD_HEURISTICS_GRANT = 7,
-  kMaxValue = ACCESS_ALLOWED_3PCD_HEURISTICS_GRANT,
+  ACCESS_ALLOWED_CORS_EXCEPTION = 8,
+  kMaxValue = ACCESS_ALLOWED_CORS_EXCEPTION,
 };
 // This enum must match the numbering for BreakageIndicatorType in
 // histograms/enums.xml. Do not reorder or remove items, only add new items

services/network/url_loader.cc

@@ -739,6 +739,12 @@ URLLoader::URLLoader(
     url_request_->cookie_setting_overrides().Put(
         net::CookieSettingOverride::kTopLevelStorageAccessGrantEligible);
   }
+  if (network::cors::IsCorsEnabledRequestMode(request_mode_) &&
+      url_request_->site_for_cookies().IsNull() &&
+      url_request_->allow_credentials()) {
+    url_request_->cookie_setting_overrides().Put(
+        net::CookieSettingOverride::kCrossSiteCredentialedWithCORS);
+  }
 
   AddAdsHeuristicCookieSettingOverrides(
       request.is_ad_tagged, url_request_->cookie_setting_overrides());

third_party/blink/web_tests/VirtualTestSuites

@@ -2449,6 +2449,16 @@
     "expires": "Jul 1, 2024",
     "owners": ["arichiv@chromium.org"]
   },
+  {
+    "prefix": "saa-top-level-site-cors-exception",
+    "platforms": ["Linux", "Mac", "Win"],
+    "bases": [
+      "external/wpt/storage-access-api/requestStorageAccess-cross-site-sibling-iframes.sub.https.window.js"
+    ],
+    "args": ["--enable-features=ThirdPartyCookieTopLevelSiteCorsException"],
+    "expires": "Jul 1, 2024",
+    "owners": ["dylancutler@google.com"]
+  },
   {
     "prefix": "permission-element",
     "platforms": ["Linux", "Mac", "Win"],

third_party/blink/web_tests/external/wpt/storage-access-api/helpers.js

@@ -264,6 +264,14 @@ function FetchFromFrame(frame, url) {
     { command: "cors fetch", url }, frame.contentWindow);
 }
 
+// Makes a subresource request to the provided host in the given frame with
+// the mode set to 'no-cors'
+function NoCorsSubresourceCookiesFromFrame(frame, host) {
+  const url = `${host}/storage-access-api/resources/echo-cookie-header.py`;
+  return PostMessageAndAwaitReply(
+    { command: "no-cors fetch", url }, frame.contentWindow);
+}
+
 // Tries to set storage access policy, ignoring any errors.
 //
 // Note: to discourage the writing of tests that assume unpartitioned cookie
@@ -295,4 +303,4 @@ function MessageWorker(frame, message = {}) {
 function ReadCookiesFromWebSocketConnection(frame, origin) {
   return PostMessageAndAwaitReply(
    { command: "get_cookie_via_websocket", origin}, frame.contentWindow);
-}
+}

third_party/blink/web_tests/external/wpt/storage-access-api/requestStorageAccess-cross-site-sibling-iframes.sub.https.window.js

@@ -75,6 +75,8 @@
     assert_true(cookieStringHasCookie("foo", "bar", await FetchSubresourceCookiesFromFrame(crossSiteFrame, wwwAlt)),"crossSiteFrame making same-origin subresource request can access cookies.");
 
     assert_false(cookieStringHasCookie("foo", "bar",  await FetchSubresourceCookiesFromFrame(crossOriginFrame, wwwAlt)), "crossOriginFrame making cross-site subresource request to sibling iframe's host should not include cookies.");
+
+    assert_false(cookieStringHasCookie("foo", "bar", await NoCorsSubresourceCookiesFromFrame(crossOriginFrame, www)), "crossSiteFrame making no-cors cross-site subresource request to sibling iframe's host should not include cookies.");
     assert_false(cookieStringHasCookie("cookie", "monster", await FetchSubresourceCookiesFromFrame(crossSiteFrame, www)),"crossSiteFrame making cross-site subresource request to sibling iframe's host should not include cookies.");
 
   }, "Cross-site sibling iframes should not be able to take advantage of the existing permission grant requested by others.");

third_party/blink/web_tests/external/wpt/storage-access-api/resources/embedded_responder.js

@@ -75,6 +75,9 @@ window.addEventListener("message", async (event) => {
     case "cors fetch":
       reply(await fetch(event.data.url, {mode: 'cors', credentials: 'include'}).then((resp) => resp.text()));
       break;
+    case "no-cors fetch":
+      reply(await fetch(event.data.url, {mode: 'no-cors', credentials: 'include'}).then((resp) => resp.text()));
+      break;
     case "start_dedicated_worker":
       worker = new Worker("embedded_worker.js");
       reply(undefined);

third_party/blink/web_tests/virtual/saa-top-level-site-cors-exception/README.md

@@ -0,0 +1,4 @@
+This directory verifies behavior of the Storage Access API when we grant an
+exception to third-party cookie blocking to requests that are to the same
+site as the top-level domain, even if they have a cross-site ancestor.
+`--enable-features=ThirdPartyCookieTopLevelSiteCorsException`

third_party/blink/web_tests/virtual/saa-top-level-site-cors-exception/external/wpt/storage-access-api/requestStorageAccess-cross-site-sibling-iframes.sub.https.window-expected.txt

@@ -0,0 +1,5 @@
+This is a testharness.js-based test.
+[FAIL] Cross-site sibling iframes should not be able to take advantage of the existing permission grant requested by others.
+  assert_false: crossSiteFrame making cross-site subresource request to sibling iframe's host should not include cookies. expected false got true
+Harness: the test ran to completion.
+

tools/metrics/histograms/metadata/page/enums.xml

@@ -305,6 +305,7 @@ chromium-metrics-reviews@google.com.
   <int value="5" label="Allow by 3PCD heuristics"/>
   <int value="6" label="Allow by Storage access API"/>
   <int value="7" label="Allow by top-level Storage access API"/>
+  <int value="8" label="Allow by opting into CORS protections"/>
 </enum>
 
 </enums>

tools/metrics/histograms/metadata/storage/enums.xml

@@ -301,6 +301,7 @@ chromium-metrics-reviews@google.com.
   <int value="6"
       label="Storage access allowed by 3PCD metadata grants content settings"/>
   <int value="7" label="Temporary storage access allowed by 3PCD heuristics"/>
+  <int value="8" label="Storage access allowed due to CORS opt in"/>
 </enum>
 
 <enum name="StorageBucketDurabilityParameter">