From 3558bf2bb5f17de8f6a80cad45d7412c7f61e6ea Mon Sep 17 00:00:00 2001
From: Liam Brady <lbrady@google.com>
Date: Tue, 04 Aug 2026 13:34:24 -0700
Subject: [PATCH] Recompute OpenerCrossOrigin download policy in browser.

This CL recomputes the OpenerCrossOrigin download policy inside
NavigationRequest on the browser side. This prevents a compromised
renderer from bypassing cross-origin opener download restrictions by
tampering with IPC parameters.

This CL also sanitizes the URL logged to the console for cross-origin
opener download deprecation to only include the serialized origin,
avoiding leakage of sensitive paths/tokens in query parameters.

Bug: 517178299
Change-Id: I829b4e653c3e0c7f9c6b6c5f35987bb51ce49d31
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8172183
Commit-Queue: Liam Brady <lbrady@google.com>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1673634}
---

diff --git a/content/browser/renderer_host/navigation_request.cc b/content/browser/renderer_host/navigation_request.cc
index f48b3b1..bd3801e1 100644
--- a/content/browser/renderer_host/navigation_request.cc
+++ b/content/browser/renderer_host/navigation_request.cc
@@ -1836,6 +1836,15 @@
   }
 #endif
 
+  if (GetInitiatorFrameToken().has_value()) {
+    RenderFrameHostImpl* initiator_rfh = RenderFrameHostImpl::FromFrameToken(
+        GetInitiatorProcessId(), GetInitiatorFrameToken().value());
+    if (initiator_rfh) {
+      initiator_document_token_ = initiator_rfh->GetDocumentToken();
+      is_opener_navigation_ =
+          (initiator_rfh->frame_tree_node()->opener() == frame_tree_node_);
+    }
+  }
 
   ComputeDownloadPolicy();
 
@@ -1847,13 +1856,6 @@
       perfetto::protos::pbzero::ChromeTrackEvent::kNavigation, this);
   TRACE_EVENT_BEGIN("navigation", "Initializing", GetNavigationTracingTrack());
 
-  if (GetInitiatorFrameToken().has_value()) {
-    RenderFrameHostImpl* initiator_rfh = RenderFrameHostImpl::FromFrameToken(
-        GetInitiatorProcessId(), GetInitiatorFrameToken().value());
-    if (initiator_rfh)
-      initiator_document_token_ = initiator_rfh->GetDocumentToken();
-  }
-
   // Spec: https://github.com/whatwg/html/issues/8846
   // We only allow the parent to access a subframe resource timing if the
   // navigation is container-initiated, e.g. iframe changed src.
@@ -8649,7 +8651,7 @@
             "Navigating a cross-origin opener to a download (%s) is "
             "deprecated, see "
             "https://www.chromestatus.com/feature/5742188281462784.",
-            common_params_->url.spec().c_str()));
+            common_params_->url.DeprecatedGetOriginAsURL().spec().c_str()));
     GetContentClient()->browser()->LogWebFeatureForCurrentPage(
         rfh, blink::mojom::WebFeature::kOpenerNavigationDownloadCrossOrigin);
   }
@@ -12247,12 +12249,21 @@
     download_policy().SetDisallowed(blink::NavigationDownloadType::kSandbox);
   }
 
+  // [OpenerCrossOrigin]
+  bool is_cross_origin =
+      GetInitiatorOrigin() && !GetInitiatorOrigin()->IsSameOriginWith(
+                                  frame_tree_node_->current_origin());
+
+  if (is_opener_navigation_ && is_cross_origin) {
+    download_policy().SetDisallowed(
+        blink::NavigationDownloadType::kOpenerCrossOrigin);
+  }
+
   // TODO(arthursonzogni): Check if the following fields from the
   // NavigationDownloadPolicy could be computed here from the browser process
   // instead:
   //
   // [NoGesture]
-  // [OpenerCrossOrigin]
   // [AdFrameNoGesture]
   // [AdFrame]
   // [Interstitial]
diff --git a/content/browser/renderer_host/navigation_request.h b/content/browser/renderer_host/navigation_request.h
index 2ed8127a..de88c2f 100644
--- a/content/browser/renderer_host/navigation_request.h
+++ b/content/browser/renderer_host/navigation_request.h
@@ -1904,6 +1904,9 @@
 
  private:
   friend class NavigationRequestTest;
+  FRIEND_TEST_ALL_PREFIXES(
+      NavigationRequestDownloadBrowserTest,
+      OpenerCrossOrigin_BrowserOverridesCompromisedRenderer);
   FRIEND_TEST_ALL_PREFIXES(NavigationRequestTest, SanitizeRedirectsForCommit);
   FRIEND_TEST_ALL_PREFIXES(NavigationRequestTest,
                            SanitizeRedirectsForCommitRelativeLocation);
@@ -3220,6 +3223,10 @@
   // initiated navigations which use `CreateBrowserInitiated()`.
   const bool was_opener_suppressed_ = false;
 
+  // Indicates whether the initiator is navigating its opener frame at the time
+  // of request creation.
+  bool is_opener_navigation_ = false;
+
   // This tracks a connection between the current pending entry and this
   // request, such that the pending entry can be discarded if no requests are
   // left referencing it.
diff --git a/content/browser/renderer_host/navigation_request_browsertest.cc b/content/browser/renderer_host/navigation_request_browsertest.cc
index 197641d..ca27378 100644
--- a/content/browser/renderer_host/navigation_request_browsertest.cc
+++ b/content/browser/renderer_host/navigation_request_browsertest.cc
@@ -15,6 +15,7 @@
 #include "base/strings/strcat.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
 #include "base/test/bind.h"
 #include "base/test/metrics/histogram_tester.h"
 #include "base/values.h"
@@ -3826,6 +3827,105 @@
   EXPECT_FALSE(handle_observer.is_download());
 }
 
+IN_PROC_BROWSER_TEST_F(NavigationRequestDownloadBrowserTest,
+                       OpenerCrossOriginDownload_SanitizesConsoleUrl) {
+  GURL main_url(embedded_test_server()->GetURL("a.com", "/title1.html"));
+  GURL popup_url(embedded_test_server()->GetURL("c.com", "/title1.html"));
+  GURL download_url(embedded_test_server()->GetURL(
+      "b.com", "/download-test1.lib?token=SECRET_12345"));
+
+  ASSERT_TRUE(NavigateToURL(shell(), main_url));
+
+  WebContentsConsoleObserver console_observer(shell()->web_contents());
+  console_observer.SetPattern(
+      "*Navigating a cross-origin opener to a download*");
+
+  // Open a cross-origin popup from a.com.
+  ShellAddedObserver shell_observer;
+  std::string open_script = JsReplace("window.open($1, 'popup');", popup_url);
+  EXPECT_TRUE(ExecJs(shell(), open_script));
+  Shell* popup = shell_observer.GetShell();
+  EXPECT_TRUE(WaitForLoadStop(popup->web_contents()));
+
+  // Navigate opener (a.com) to cross-origin download from the cross-origin
+  // popup (c.com).
+  std::string script = JsReplace("window.opener.location = $1;", download_url);
+  EXPECT_TRUE(ExecJs(popup->web_contents(), script));
+
+  ASSERT_TRUE(console_observer.Wait());
+  ASSERT_EQ(1u, console_observer.messages().size());
+  std::string msg = base::UTF16ToUTF8(console_observer.messages()[0].message);
+
+  // Verify the console message contains the origin (b.com) but not full path or
+  // secret query token.
+  EXPECT_THAT(msg, ::testing::HasSubstr("b.com"));
+  EXPECT_THAT(msg, ::testing::Not(::testing::HasSubstr("SECRET_12345")));
+  EXPECT_THAT(msg, ::testing::Not(::testing::HasSubstr("download-test1.lib")));
+}
+
+IN_PROC_BROWSER_TEST_F(NavigationRequestDownloadBrowserTest,
+                       OpenerCrossOrigin_BrowserOverridesCompromisedRenderer) {
+  GURL main_url(embedded_test_server()->GetURL("a.com", "/title1.html"));
+  GURL popup_url(embedded_test_server()->GetURL("c.com", "/title1.html"));
+  GURL download_url(
+      embedded_test_server()->GetURL("b.com", "/download-test1.lib"));
+
+  ASSERT_TRUE(NavigateToURL(shell(), main_url));
+
+  ShellAddedObserver shell_observer;
+  std::string open_script = JsReplace("window.open($1, 'popup');", popup_url);
+  EXPECT_TRUE(ExecJs(shell(), open_script));
+  Shell* popup = shell_observer.GetShell();
+  EXPECT_TRUE(WaitForLoadStop(popup->web_contents()));
+
+  RenderFrameHostImpl* main_rfh =
+      static_cast<WebContentsImpl*>(shell()->web_contents())
+          ->GetPrimaryMainFrame();
+  RenderFrameHostImpl* popup_rfh =
+      static_cast<WebContentsImpl*>(popup->web_contents())
+          ->GetPrimaryMainFrame();
+
+  EXPECT_NE(nullptr, popup_rfh->frame_tree_node()->opener());
+  EXPECT_EQ(main_rfh->frame_tree_node(),
+            popup_rfh->frame_tree_node()->opener());
+
+  TestNavigationManager manager(shell()->web_contents(), download_url);
+  std::string script = JsReplace("window.opener.location = $1;", download_url);
+  EXPECT_TRUE(ExecJs(popup->web_contents(), script));
+
+  EXPECT_TRUE(manager.WaitForRequestStart());
+  NavigationRequest* request =
+      static_cast<WebContentsImpl*>(shell()->web_contents())
+          ->GetPrimaryMainFrame()

diff --git a/content/browser/renderer_host/navigation_request_browsertest.cc b/content/browser/renderer_host/navigation_request_browsertest.cc
index 197641d..ca27378 100644
--- a/content/browser/renderer_host/navigation_request_browsertest.cc
+++ b/content/browser/renderer_host/navigation_request_browsertest.cc
@@ -15,6 +15,7 @@
 #include "base/strings/strcat.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
 #include "base/test/bind.h"
 #include "base/test/metrics/histogram_tester.h"
 #include "base/values.h"
@@ -3826,6 +3827,105 @@
   EXPECT_FALSE(handle_observer.is_download());
 }
 
+IN_PROC_BROWSER_TEST_F(NavigationRequestDownloadBrowserTest,
+                       OpenerCrossOriginDownload_SanitizesConsoleUrl) {
+  GURL main_url(embedded_test_server()->GetURL("a.com", "/title1.html"));
+  GURL popup_url(embedded_test_server()->GetURL("c.com", "/title1.html"));
+  GURL download_url(embedded_test_server()->GetURL(
+      "b.com", "/download-test1.lib?token=SECRET_12345"));
+
+  ASSERT_TRUE(NavigateToURL(shell(), main_url));
+
+  WebContentsConsoleObserver console_observer(shell()->web_contents());
+  console_observer.SetPattern(
+      "*Navigating a cross-origin opener to a download*");
+
+  // Open a cross-origin popup from a.com.
+  ShellAddedObserver shell_observer;
+  std::string open_script = JsReplace("window.open($1, 'popup');", popup_url);
+  EXPECT_TRUE(ExecJs(shell(), open_script));
+  Shell* popup = shell_observer.GetShell();
+  EXPECT_TRUE(WaitForLoadStop(popup->web_contents()));
+
+  // Navigate opener (a.com) to cross-origin download from the cross-origin
+  // popup (c.com).
+  std::string script = JsReplace("window.opener.location = $1;", download_url);
+  EXPECT_TRUE(ExecJs(popup->web_contents(), script));
+
+  ASSERT_TRUE(console_observer.Wait());
+  ASSERT_EQ(1u, console_observer.messages().size());
+  std::string msg = base::UTF16ToUTF8(console_observer.messages()[0].message);
+
+  // Verify the console message contains the origin (b.com) but not full path or
+  // secret query token.
+  EXPECT_THAT(msg, ::testing::HasSubstr("b.com"));
+  EXPECT_THAT(msg, ::testing::Not(::testing::HasSubstr("SECRET_12345")));
+  EXPECT_THAT(msg, ::testing::Not(::testing::HasSubstr("download-test1.lib")));
+}
+
+IN_PROC_BROWSER_TEST_F(NavigationRequestDownloadBrowserTest,
+                       OpenerCrossOrigin_BrowserOverridesCompromisedRenderer) {
+  GURL main_url(embedded_test_server()->GetURL("a.com", "/title1.html"));
+  GURL popup_url(embedded_test_server()->GetURL("c.com", "/title1.html"));
+  GURL download_url(
+      embedded_test_server()->GetURL("b.com", "/download-test1.lib"));
+
+  ASSERT_TRUE(NavigateToURL(shell(), main_url));
+
+  ShellAddedObserver shell_observer;
+  std::string open_script = JsReplace("window.open($1, 'popup');", popup_url);
+  EXPECT_TRUE(ExecJs(shell(), open_script));
+  Shell* popup = shell_observer.GetShell();
+  EXPECT_TRUE(WaitForLoadStop(popup->web_contents()));
+
+  RenderFrameHostImpl* main_rfh =
+      static_cast<WebContentsImpl*>(shell()->web_contents())
+          ->GetPrimaryMainFrame();
+  RenderFrameHostImpl* popup_rfh =
+      static_cast<WebContentsImpl*>(popup->web_contents())
+          ->GetPrimaryMainFrame();
+
+  EXPECT_NE(nullptr, popup_rfh->frame_tree_node()->opener());
+  EXPECT_EQ(main_rfh->frame_tree_node(),
+            popup_rfh->frame_tree_node()->opener());
+
+  TestNavigationManager manager(shell()->web_contents(), download_url);
+  std::string script = JsReplace("window.opener.location = $1;", download_url);
+  EXPECT_TRUE(ExecJs(popup->web_contents(), script));
+
+  EXPECT_TRUE(manager.WaitForRequestStart());
+  NavigationRequest* request =
+      static_cast<WebContentsImpl*>(shell()->web_contents())
+          ->GetPrimaryMainFrame()
+          ->frame_tree_node()
+          ->navigation_request();
+
+  // Simulate a compromised renderer that stripped the kOpenerCrossOrigin flag
+  // from IPC.
+  request->common_params_->download_policy.observed_types.reset();
+  request->common_params_->download_policy.disallowed_types.reset();
+
+  EXPECT_FALSE(request->common_params_->download_policy.IsType(
+      blink::NavigationDownloadType::kOpenerCrossOrigin));
+  EXPECT_TRUE(request->common_params_->download_policy.IsDownloadAllowed());
+
+  // Close the initiator popup to destroy the initiator RenderFrameHost. This
+  // verifies that browser-side enforcement relies on cached state recorded at
+  // NavigationRequest creation, preventing a race condition bypass where a
+  // compromised renderer closes itself or navigates away before policy
+  // recomputation.
+  popup->Close();
+
+  // Run browser recomputation:
+  request->ComputeDownloadPolicy();
+
+  // Verify browser recomputation enforced kOpenerCrossOrigin even after
+  // initiator RFH destruction:
+  EXPECT_TRUE(request->common_params_->download_policy.IsType(
+      blink::NavigationDownloadType::kOpenerCrossOrigin));
+  EXPECT_FALSE(request->common_params_->download_policy.IsDownloadAllowed());
+}
+
 class NavigationRequestBackForwardBrowserTest
     : public NavigationRequestBrowserTest,
       public WebContentsObserver {