From 1e376a204337be41d2acaec2aba69ff59a0330e4 Mon Sep 17 00:00:00 2001
From: Yuwei Huang <yuweih@chromium.org>
Date: Fri, 03 Apr 2026 16:59:04 -0700
Subject: [PATCH] [crd host] Fix named mojo server socket paths

CRD puts named mojo server sockets in /tmp, which is susceptible to
CWE-377. This CL fixes this by:

1. Putting daemon started server sockets in
   /var/lib/chrome-remote-desktop/
2. Putting other server sockets in $XDG_RUNTIME_DIR/

Also delete WorkingDirectoryIndependentServerNameFromUTF8 since nothing
uses it.

Verified with multi-process host and single-process host that WebAuthn
forwarding still WAI.

Bug: 499154022
Change-Id: Ife333f5f6b355fc450626e13e5821e6704b47afe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7729845
Reviewed-by: Joe Downing <joedow@chromium.org>
Commit-Queue: Yuwei Huang <yuweih@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1610031}
---

diff --git a/components/named_mojo_ipc_server/BUILD.gn b/components/named_mojo_ipc_server/BUILD.gn
index b4231731..f186e557 100644
--- a/components/named_mojo_ipc_server/BUILD.gn
+++ b/components/named_mojo_ipc_server/BUILD.gn
@@ -21,8 +21,6 @@
     "named_mojo_ipc_server.h",
     "named_mojo_ipc_server_client_util.cc",
     "named_mojo_ipc_server_client_util.h",
-    "named_mojo_ipc_util.cc",
-    "named_mojo_ipc_util.h",
     "named_mojo_message_pipe_server.cc",
     "named_mojo_message_pipe_server.h",
     "named_mojo_server_endpoint_connector.cc",
diff --git a/components/named_mojo_ipc_server/named_mojo_ipc_util.cc b/components/named_mojo_ipc_server/named_mojo_ipc_util.cc
deleted file mode 100644
index 8fbbde16..0000000
--- a/components/named_mojo_ipc_server/named_mojo_ipc_util.cc
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright 2021 The Chromium Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/named_mojo_ipc_server/named_mojo_ipc_util.h"
-
-#include <string>
-#include <string_view>
-
-#include "build/build_config.h"
-
-#if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_MAC)
-#include "base/files/file_path.h"
-#include "base/files/file_util.h"
-#include "base/logging.h"
-#endif
-
-namespace named_mojo_ipc_server {
-
-mojo::NamedPlatformChannel::ServerName
-WorkingDirectoryIndependentServerNameFromUTF8(std::string_view name) {
-#if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_MAC)
-  // The channel name on non-mac POSIX (basically Linux) is the path to a unix
-  // domain socket, so it needs to be an absolute path to allow the IPC binary
-  // to be executed from any working directory.
-  base::FilePath temp_dir_path;
-  if (base::GetTempDir(&temp_dir_path)) {
-    return mojo::NamedPlatformChannel::ServerNameFromUTF8(
-        temp_dir_path.Append(name).value());
-  }
-  LOG(ERROR) << "Failed to retrieve temporary directory.";
-  // Fallback to just using |name|.
-#endif
-
-  // ServerName on other platforms (i.e. Windows and Mac) is globally unique.
-  return mojo::NamedPlatformChannel::ServerNameFromUTF8(name);
-}
-
-}  // namespace named_mojo_ipc_server
diff --git a/components/named_mojo_ipc_server/named_mojo_ipc_util.h b/components/named_mojo_ipc_server/named_mojo_ipc_util.h
deleted file mode 100644
index b7565c0..0000000
--- a/components/named_mojo_ipc_server/named_mojo_ipc_util.h
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright 2021 The Chromium Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef COMPONENTS_NAMED_MOJO_IPC_SERVER_NAMED_MOJO_IPC_UTIL_H_
-#define COMPONENTS_NAMED_MOJO_IPC_SERVER_NAMED_MOJO_IPC_UTIL_H_
-
-#include <string_view>
-
-#include "mojo/public/cpp/platform/named_platform_channel.h"
-
-namespace named_mojo_ipc_server {
-
-// Creates a server name that is independent to the working directory, i.e.
-// it resolves to the same channel no matter which working directory you are
-// running the binary from.
-mojo::NamedPlatformChannel::ServerName
-WorkingDirectoryIndependentServerNameFromUTF8(std::string_view name);
-
-}  // namespace named_mojo_ipc_server
-
-#endif  // COMPONENTS_NAMED_MOJO_IPC_SERVER_NAMED_MOJO_IPC_UTIL_H_
diff --git a/remoting/host/ipc_constants.cc b/remoting/host/ipc_constants.cc
index 1cd545d1..f74586d7 100644
--- a/remoting/host/ipc_constants.cc
+++ b/remoting/host/ipc_constants.cc
@@ -4,15 +4,20 @@
 
 #include "remoting/host/ipc_constants.h"
 
+#include "base/environment.h"
 #include "base/logging.h"
 #include "base/no_destructor.h"
 #include "base/path_service.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
-#include "components/named_mojo_ipc_server/named_mojo_ipc_util.h"
 #include "mojo/public/cpp/platform/named_platform_channel.h"
 #include "remoting/base/username.h"
 
+#if BUILDFLAG(IS_LINUX)
+#include "base/nix/xdg_util.h"
+#include "remoting/base/file_path_util_linux.h"
+#endif
+
 namespace remoting {
 
 namespace {
@@ -23,21 +28,9 @@
 // might also be running.
 constexpr char kChromotingHostServicesIpcName[] =
     "chromoting.host_services_debug_mojo_ipc";
-
-#if BUILDFLAG(IS_LINUX)
-constexpr char kLegacyChromotingHostServicesIpcNamePattern[] =
-    "chromoting.%s.host_services_debug_mojo_ipc";
-#endif
-
 #else  // defined(NDEBUG)
 constexpr char kChromotingHostServicesIpcName[] =
     "chromoting.host_services_mojo_ipc";
-
-#if BUILDFLAG(IS_LINUX)
-constexpr char kLegacyChromotingHostServicesIpcNamePattern[] =
-    "chromoting.%s.host_services_mojo_ipc";
-#endif
-
 #endif
 
 #if BUILDFLAG(IS_MAC)
@@ -69,6 +62,14 @@
 
 #endif
 
+mojo::NamedPlatformChannel::ServerName GetServerName(std::string_view name) {
+#if BUILDFLAG(IS_LINUX)
+  return GetVarLibDir().Append(name).value();
+#else
+  return mojo::NamedPlatformChannel::ServerNameFromUTF8(name);
+#endif
+}
+
 }  // namespace
 
 const base::FilePath::CharType kHostBinaryName[] =
@@ -100,23 +101,25 @@
 const mojo::NamedPlatformChannel::ServerName&
 GetChromotingHostServicesServerName() {
   static const base::NoDestructor<mojo::NamedPlatformChannel::ServerName>
-      server_name(
-          named_mojo_ipc_server::WorkingDirectoryIndependentServerNameFromUTF8(
-              kChromotingHostServicesIpcName));
+      server_name(GetServerName(kChromotingHostServicesIpcName));
   return *server_name;
 }
 
 #if BUILDFLAG(IS_LINUX)
 const mojo::NamedPlatformChannel::ServerName&
 GetLegacyChromotingHostServicesServerName() {
-  // The legacy Linux single-process host is run as the login user, so we put
-  // the username in the path in case there are multiple host services running
-  // on the same machine.
   static const base::NoDestructor<mojo::NamedPlatformChannel::ServerName>
-      server_name(
-          named_mojo_ipc_server::WorkingDirectoryIndependentServerNameFromUTF8(
-              base::StringPrintf(kLegacyChromotingHostServicesIpcNamePattern,
-                                 GetUsername().c_str())));
+      server_name([]() {
+        // The legacy Linux single-process host is run as the login user, so we
+        // put it in the user's XDG_RUNTIME_DIR instead.