Reland "lacros: Check user dir is not accessed pre-login"

This is a reland of commit c444bc1

The original change was causing a compilation error in some builds,
as the argument inside the DCHECKs refers to IsInitializedUserDataDir,
which is not declared/defined in non-debug builds.

This CL changes:
- The complex !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON) condition
  to the more readable DCHECK_IS_ON().
- Wraps the DCHECKs into `#if DCHECK_IS_ON()` blocks to avoid
  the previously mentioned compilation errors.

Original change's description:
> lacros: Check user dir is not accessed pre-login
>
> As part of the effort to execute more operations at login screen
> before blocking waiting for the user to login, we want to remove
> accesses to the cryptohome that happen early in the initialization
> process.
>
> This change ensures (via DCHECKs) that any access to the cryptohome
> happens after user dir initialization when prelaunching.
>
> BUG=1495212
> TEST=CQ
> tast run ${DUT} lacros.Basic
> tast run ${DUT} lacros.LoginScreenLaunch.rootfs
>
> Change-Id: Id6df5e28216beb8058e8349ca849bf53e9f46daf
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4944753
> Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
> Reviewed-by: Marc Treib <treib@chromium.org>
> Commit-Queue: Andrea Orru <andreaorru@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1214708}

BUG=1495212

Change-Id: Ie34ff8e25a551b33ed9b3d7b7e825ef6bdf70f3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4975550
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Andrea Orru <andreaorru@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1216769}

chrome/app/chrome_main_delegate.cc

@@ -570,6 +570,12 @@ struct MainFunction {
 
 // Initializes the user data dir. Must be called before InitializeLocalState().
 void InitializeUserDataDir(base::CommandLine* command_line) {
+#if BUILDFLAG(IS_CHROMEOS_LACROS) && DCHECK_IS_ON()
+  // In debug builds of Lacros, we keep track of when the user data dir
+  // is initialized, to ensure the cryptohome is not accessed before login
+  // when prelaunching at login screen.
+  chromeos::lacros_paths::SetInitializedUserDataDir();
+#endif
 #if BUILDFLAG(IS_WIN)
   // Reach out to chrome_elf for the truth on the user data directory.
   // Note that in tests, this links to chrome_elf_test_stubs.
@@ -1425,13 +1431,14 @@ void ChromeMainDelegate::PreSandboxStartup() {
   base::CPU cpu_info;
 #endif
 
+  // Initialize the user data dir for any process type that needs it.
   bool initialize_user_data_dir = chrome::ProcessNeedsProfileDir(process_type);
 #if BUILDFLAG(IS_CHROMEOS_LACROS)
   // In Lacros, when prelaunching at login screen, we postpone the
   // initialization of the user data directory.
+  // We verify that no access happens before login via DCHECKs.
   initialize_user_data_dir &= !chromeos::IsLaunchedWithPostLoginParams();
 #endif
-  // Initialize the user data dir for any process type that needs it.
   if (initialize_user_data_dir) {
     InitializeUserDataDir(base::CommandLine::ForCurrentProcess());
   }

chrome/common/BUILD.gn

@@ -669,6 +669,7 @@ static_library("constants") {
     deps += [
       "//chromeos/crosapi/cpp:crosapi_constants",
       "//chromeos/lacros:lacros_paths",
+      "//chromeos/startup",
     ]
     public_deps += [ "//chromeos/crosapi/mojom" ]
   } else if (is_linux || is_chromeos) {

chrome/common/DEPS

@@ -5,6 +5,7 @@ include_rules = [
   "+chrome/services/file_util/public",
   "+chromeos/crosapi",
   "+chromeos/lacros/lacros_paths.h",
+  "+chromeos/startup/startup.h",
   "+components/autofill/content/common",
   "+components/autofill/core/common",
   "+components/bookmarks/common",

chrome/common/chrome_paths.cc

@@ -47,6 +47,7 @@
 #include "chrome/common/chrome_switches.h"
 #include "chromeos/crosapi/cpp/crosapi_constants.h"  // nogncheck
 #include "chromeos/lacros/lacros_paths.h"
+#include "chromeos/startup/startup.h"  // nogncheck
 #endif
 
 namespace {
@@ -186,6 +187,12 @@ bool PathProvider(int key, base::FilePath* result) {
   base::FilePath cur;
   switch (key) {
     case chrome::DIR_USER_DATA:
+#if BUILDFLAG(IS_CHROMEOS_LACROS) && DCHECK_IS_ON()
+      // Check that the user data directory is not accessed before
+      // initialization when prelaunching at login screen.
+      DCHECK(chromeos::lacros_paths::IsInitializedUserDataDir() ||
+             !chromeos::IsLaunchedWithPostLoginParams());
+#endif
       if (!GetDefaultUserDataDirectory(&cur)) {
         return false;
       }

chromeos/lacros/lacros_paths.cc

@@ -17,6 +17,11 @@ struct LacrosPaths {
   base::FilePath ash_resource_dir;
 };
 
+#if DCHECK_IS_ON()
+// Keep track of whether the user data directory was initialized.
+bool g_initialized_user_data_dir = false;
+#endif
+
 LacrosPaths& GetLacrosPaths() {
   static base::NoDestructor<LacrosPaths> lacros_paths;
   return *lacros_paths;
@@ -35,6 +40,11 @@ bool PathProvider(int key, base::FilePath* result) {
       }
       return true;
     case chromeos::lacros_paths::USER_DATA_DIR:
+#if DCHECK_IS_ON()
+      // Check that the user data directory is not accessed before
+      // initialization.
+      DCHECK(chromeos::lacros_paths::IsInitializedUserDataDir());
+#endif
       // The value for USER_DATA_DIR should be consistent with ash-side
       // UserDataDir defined in browser_util::GetUserDataDir().
       if (base::SysInfo::IsRunningOnChromeOS()) {
@@ -53,6 +63,17 @@ bool PathProvider(int key, base::FilePath* result) {
 namespace chromeos {
 namespace lacros_paths {
 
+#if DCHECK_IS_ON()
+bool IsInitializedUserDataDir() {
+  return g_initialized_user_data_dir;
+}
+
+void SetInitializedUserDataDir() {
+  DCHECK(!g_initialized_user_data_dir);
+  g_initialized_user_data_dir = true;
+}
+#endif
+
 void RegisterPathProvider() {
   base::PathService::RegisterProvider(PathProvider, PATH_START, PATH_END);
 }

chromeos/lacros/lacros_paths.h

@@ -5,6 +5,8 @@
 #ifndef CHROMEOS_LACROS_LACROS_PATHS_H_
 #define CHROMEOS_LACROS_LACROS_PATHS_H_
 
+#include "base/dcheck_is_on.h"
+
 namespace base {
 class FilePath;
 }
@@ -30,6 +32,15 @@ enum {
   PATH_END
 };
 
+#if DCHECK_IS_ON()
+// Returns true if the user data directory has been initialized,
+// false otherwise.
+bool IsInitializedUserDataDir();
+
+// Signals that the user data directory has been initialized.
+void SetInitializedUserDataDir();
+#endif
+
 // Call once to register the provide for the path keys defined above.
 void RegisterPathProvider();