cherry-pick-91dd4f79ab5b.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Ken Rockot <rockot@google.com>
Date: Mon, 25 Oct 2021 18:22:50 +0000
Subject: Validate INTRODUCE source node

INTRODUCE NodeChannel messages should only be acknowledged when coming
from the broker process.

(cherry picked from commit 6e74f7b5cb2f48b17403f0431f3e4f3a2e716265)

Fixed: 1252858
Change-Id: I2dff6d5cab102ce744ad2ad66a9f24b4202cbea8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3193798
Reviewed-by: Alex Gough <ajgo@chromium.org>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Original-Commit-Position: refs/heads/main@{#926430}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3229034
Auto-Submit: Ken Rockot <rockot@google.com>
Reviewed-by: Oksana Zhuravlova <oksamyt@chromium.org>
Commit-Queue: Oksana Zhuravlova <oksamyt@chromium.org>
Cr-Commit-Position: refs/branch-heads/4638@{#964}
Cr-Branched-From: 159257cab5585bc8421abf347984bb32fdfe9eb9-refs/heads/main@{#920003}

diff --git a/mojo/core/node_controller.cc b/mojo/core/node_controller.cc
index 9f2e79b9e04e9df8aff6c924e6a480ac81857701..21edab39368e69ee6665e490b2c4de13f424edbd 100644
--- a/mojo/core/node_controller.cc
+++ b/mojo/core/node_controller.cc
@@ -20,6 +20,7 @@
 #include "mojo/core/broker.h"
 #include "mojo/core/broker_host.h"
 #include "mojo/core/configuration.h"
+#include "mojo/core/ports/name.h"
 #include "mojo/core/request_context.h"
 #include "mojo/core/user_message_impl.h"
 #include "mojo/public/cpp/platform/named_platform_channel.h"
@@ -1127,6 +1128,12 @@ void NodeController::OnIntroduce(const ports::NodeName& from_node,
                                  const uint64_t remote_capabilities) {
   DCHECK(io_task_runner_->RunsTasksInCurrentSequence());
 
+  if (broker_name_ == ports::kInvalidNodeName || from_node != broker_name_) {
+    DVLOG(1) << "Ignoring introduction from non-broker process.";
+    DropPeer(from_node, nullptr);
+    return;
+  }
+
   if (!channel_handle.is_valid()) {
     node_->LostConnectionToNode(name);