ueventd: require opt-in for modalias handling

Some devices have modules.alias and modules.dep for modprobe and other
purposes but do not want to opt into ueventd auto loading their
modules.  Therefore we add a flag that can be added to ueventd
configuration files to opt into this behavior.

Bug: 111916071
Bug: 112048758
Test: check that modules are loaded with this opt-in
Test: check that modules are not loaded without this opt-in
Change-Id: Ifb281b273059b4671eea1ca5bc726c9e79f3adfb

Author: Tom Cherry

init/devices.cpp

@@ -372,7 +372,7 @@ void DeviceHandler::HandleDevice(const std::string& action, const std::string& d
     }
 }
 
-void DeviceHandler::HandleDeviceEvent(const Uevent& uevent) {
+void DeviceHandler::HandleUevent(const Uevent& uevent) {
     if (uevent.action == "add" || uevent.action == "change" || uevent.action == "online") {
         FixupSysPermissions(uevent.path, uevent.subsystem);
     }
@@ -418,6 +418,10 @@ void DeviceHandler::HandleDeviceEvent(const Uevent& uevent) {
     HandleDevice(uevent.action, devpath, block, uevent.major, uevent.minor, links);
 }
 
+void DeviceHandler::ColdbootDone() {
+    skip_restorecon_ = true;
+}
+
 DeviceHandler::DeviceHandler(std::vector<Permissions> dev_permissions,
                              std::vector<SysfsPermissions> sysfs_permissions,
                              std::vector<Subsystem> subsystems, std::set<std::string> boot_devices,

init/devices.h

@@ -29,6 +29,7 @@
 #include <selinux/label.h>
 
 #include "uevent.h"
+#include "uevent_handler.h"
 
 namespace android {
 namespace init {
@@ -105,19 +106,20 @@ class Subsystem {
     std::string dir_name_ = "/dev";
 };
 
-class DeviceHandler {
+class DeviceHandler : public UeventHandler {
   public:
     friend class DeviceHandlerTester;
 
     DeviceHandler();
     DeviceHandler(std::vector<Permissions> dev_permissions,
                   std::vector<SysfsPermissions> sysfs_permissions, std::vector<Subsystem> subsystems,
                   std::set<std::string> boot_devices, bool skip_restorecon);
+    virtual ~DeviceHandler() = default;
 
-    void HandleDeviceEvent(const Uevent& uevent);
+    void HandleUevent(const Uevent& uevent) override;
+    void ColdbootDone() override;
 
     std::vector<std::string> GetBlockDeviceSymlinks(const Uevent& uevent) const;
-    void set_skip_restorecon(bool value) { skip_restorecon_ = value; }
 
   private:
     bool FindPlatformDevice(std::string path, std::string* platform_device_path) const;

init/firmware_handler.cpp

@@ -35,8 +35,6 @@ using android::base::WriteFully;
 namespace android {
 namespace init {
 
-std::vector<std::string> firmware_directories;
-
 static void LoadFirmware(const Uevent& uevent, const std::string& root, int fw_fd, size_t fw_size,
                          int loading_fd, int data_fd) {
     // Start transfer.
@@ -58,7 +56,10 @@ static bool IsBooting() {
     return access("/dev/.booting", F_OK) == 0;
 }
 
-static void ProcessFirmwareEvent(const Uevent& uevent) {
+FirmwareHandler::FirmwareHandler(std::vector<std::string> firmware_directories)
+    : firmware_directories_(std::move(firmware_directories)) {}
+
+void FirmwareHandler::ProcessFirmwareEvent(const Uevent& uevent) {
     int booting = IsBooting();
 
     LOG(INFO) << "firmware: loading '" << uevent.firmware << "' for '" << uevent.path << "'";
@@ -80,7 +81,7 @@ static void ProcessFirmwareEvent(const Uevent& uevent) {
     }
 
 try_loading_again:
-    for (const auto& firmware_directory : firmware_directories) {
+    for (const auto& firmware_directory : firmware_directories_) {
         std::string file = firmware_directory + uevent.firmware;
         unique_fd fw_fd(open(file.c_str(), O_RDONLY | O_CLOEXEC));
         struct stat sb;
@@ -104,7 +105,7 @@ static void ProcessFirmwareEvent(const Uevent& uevent) {
     write(loading_fd, "-1", 2);
 }
 
-void HandleFirmwareEvent(const Uevent& uevent) {
+void FirmwareHandler::HandleUevent(const Uevent& uevent) {
     if (uevent.subsystem != "firmware" || uevent.action != "add") return;
 
     // Loading the firmware in a child means we can do that in parallel...

init/firmware_handler.h

@@ -21,13 +21,23 @@
 #include <vector>
 
 #include "uevent.h"
+#include "uevent_handler.h"
 
 namespace android {
 namespace init {
 
-extern std::vector<std::string> firmware_directories;
+class FirmwareHandler : public UeventHandler {
+  public:
+    explicit FirmwareHandler(std::vector<std::string> firmware_directories);
+    virtual ~FirmwareHandler() = default;
 
-void HandleFirmwareEvent(const Uevent& uevent);
+    void HandleUevent(const Uevent& uevent) override;
+
+  private:
+    void ProcessFirmwareEvent(const Uevent& uevent);
+
+    std::vector<std::string> firmware_directories_;
+};
 
 }  // namespace init
 }  // namespace android

init/first_stage_mount.cpp

@@ -206,7 +206,7 @@ bool FirstStageMount::InitRequiredDevices() {
         bool found = false;
         auto dm_callback = [this, &dm_path, &found](const Uevent& uevent) {
             if (uevent.path == dm_path) {
-                device_handler_->HandleDeviceEvent(uevent);
+                device_handler_->HandleUevent(uevent);
                 found = true;
                 return ListenerAction::kStop;
             }
@@ -273,7 +273,7 @@ ListenerAction FirstStageMount::HandleBlockDevice(const std::string& name, const
             lp_metadata_partition_ = links[0];
         }
         required_devices_partition_names_.erase(iter);
-        device_handler_->HandleDeviceEvent(uevent);
+        device_handler_->HandleUevent(uevent);
         if (required_devices_partition_names_.empty()) {
             return ListenerAction::kStop;
         } else {
@@ -310,7 +310,7 @@ bool FirstStageMount::InitMappedDevice(const std::string& dm_device) {
     auto verity_callback = [&device_name, &dm_device, this, &found](const Uevent& uevent) {
         if (uevent.device_name == device_name) {
             LOG(VERBOSE) << "Creating device-mapper device : " << dm_device;
-            device_handler_->HandleDeviceEvent(uevent);
+            device_handler_->HandleUevent(uevent);
             found = true;
             return ListenerAction::kStop;
         }

init/modalias_handler.cpp

@@ -139,7 +139,7 @@ Result<Success> ModaliasHandler::InsmodWithDeps(const std::string& module_name,
     return Insmod(dependencies[0], args);
 }
 
-void ModaliasHandler::HandleModaliasEvent(const Uevent& uevent) {
+void ModaliasHandler::HandleUevent(const Uevent& uevent) {
     if (uevent.modalias.empty()) return;
 
     for (const auto& [alias, module] : module_aliases_) {

init/modalias_handler.h

@@ -16,22 +16,23 @@
 
 #pragma once
 
-#include "result.h"
-#include "uevent.h"
-
 #include <string>
 #include <unordered_map>
 #include <vector>
 
+#include "result.h"
+#include "uevent.h"
+#include "uevent_handler.h"
+
 namespace android {
 namespace init {
 
-class ModaliasHandler {
+class ModaliasHandler : public UeventHandler {
   public:
     ModaliasHandler();
-    ~ModaliasHandler(){};
+    virtual ~ModaliasHandler() = default;
 
-    void HandleModaliasEvent(const Uevent& uevent);
+    void HandleUevent(const Uevent& uevent) override;
 
   private:
     Result<Success> InsmodWithDeps(const std::string& module_name, const std::string& args);

init/uevent_handler.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "uevent.h"
+
+namespace android {
+namespace init {
+
+class UeventHandler {
+  public:
+    virtual ~UeventHandler() = default;
+
+    virtual void HandleUevent(const Uevent& uevent) = 0;
+
+    virtual void ColdbootDone() {}
+};
+
+}  // namespace init
+}  // namespace android

init/ueventd.cpp

@@ -38,6 +38,7 @@
 #include "firmware_handler.h"
 #include "modalias_handler.h"
 #include "selinux.h"
+#include "uevent_handler.h"
 #include "uevent_listener.h"
 #include "ueventd_parser.h"
 #include "util.h"
@@ -107,11 +108,10 @@ namespace init {
 
 class ColdBoot {
   public:
-    ColdBoot(UeventListener& uevent_listener, DeviceHandler& device_handler,
-             ModaliasHandler& modalias_handler)
+    ColdBoot(UeventListener& uevent_listener,
+             std::vector<std::unique_ptr<UeventHandler>>& uevent_handlers)
         : uevent_listener_(uevent_listener),
-          device_handler_(device_handler),
-          modalias_handler_(modalias_handler),
+          uevent_handlers_(uevent_handlers),
           num_handler_subprocesses_(std::thread::hardware_concurrency() ?: 4) {}
 
     void Run();
@@ -124,8 +124,7 @@ class ColdBoot {
     void WaitForSubProcesses();
 
     UeventListener& uevent_listener_;
-    DeviceHandler& device_handler_;
-    ModaliasHandler& modalias_handler_;
+    std::vector<std::unique_ptr<UeventHandler>>& uevent_handlers_;
 
     unsigned int num_handler_subprocesses_;
     std::vector<Uevent> uevent_queue_;
@@ -136,16 +135,16 @@ class ColdBoot {
 void ColdBoot::UeventHandlerMain(unsigned int process_num, unsigned int total_processes) {
     for (unsigned int i = process_num; i < uevent_queue_.size(); i += total_processes) {
         auto& uevent = uevent_queue_[i];
-        device_handler_.HandleDeviceEvent(uevent);
-        modalias_handler_.HandleModaliasEvent(uevent);
+
+        for (auto& uevent_handler : uevent_handlers_) {
+            uevent_handler->HandleUevent(uevent);
+        }
     }
     _exit(EXIT_SUCCESS);
 }
 
 void ColdBoot::RegenerateUevents() {
     uevent_listener_.RegenerateUevents([this](const Uevent& uevent) {
-        HandleFirmwareEvent(uevent);
-
         uevent_queue_.emplace_back(std::move(uevent));
         return ListenerAction::kContinue;
     });
@@ -168,7 +167,6 @@ void ColdBoot::ForkSubProcesses() {
 
 void ColdBoot::DoRestoreCon() {
     selinux_android_restorecon("/sys", SELINUX_ANDROID_RESTORECON_RECURSE);
-    device_handler_.set_skip_restorecon(false);
 }
 
 void ColdBoot::WaitForSubProcesses() {
@@ -234,8 +232,7 @@ int ueventd_main(int argc, char** argv) {
     SelinuxSetupKernelLogging();
     SelabelInitialize();
 
-    DeviceHandler device_handler;
-    ModaliasHandler modalias_handler;
+    std::vector<std::unique_ptr<UeventHandler>> uevent_handlers;
     UeventListener uevent_listener;
 
     {
@@ -248,30 +245,38 @@ int ueventd_main(int argc, char** argv) {
                 ParseConfig({"/ueventd.rc", "/vendor/ueventd.rc", "/odm/ueventd.rc",
                              "/ueventd." + hardware + ".rc"});
 
-        device_handler = DeviceHandler{std::move(ueventd_configuration.dev_permissions),
-                                       std::move(ueventd_configuration.sysfs_permissions),
-                                       std::move(ueventd_configuration.subsystems),
-                                       fs_mgr_get_boot_devices(), true};
+        uevent_handlers.emplace_back(std::make_unique<DeviceHandler>(
+                std::move(ueventd_configuration.dev_permissions),
+                std::move(ueventd_configuration.sysfs_permissions),
+                std::move(ueventd_configuration.subsystems), fs_mgr_get_boot_devices(), true));
+        uevent_handlers.emplace_back(std::make_unique<FirmwareHandler>(
+                std::move(ueventd_configuration.firmware_directories)));
 
-        firmware_directories = ueventd_configuration.firmware_directories;
+        if (ueventd_configuration.enable_modalias_handling) {
+            uevent_handlers.emplace_back(std::make_unique<ModaliasHandler>());
+        }
     }
 
     if (access(COLDBOOT_DONE, F_OK) != 0) {
-        ColdBoot cold_boot(uevent_listener, device_handler, modalias_handler);
+        ColdBoot cold_boot(uevent_listener, uevent_handlers);
         cold_boot.Run();
     }
 
+    for (auto& uevent_handler : uevent_handlers) {
+        uevent_handler->ColdbootDone();
+    }
+
     // We use waitpid() in ColdBoot, so we can't ignore SIGCHLD until now.
     signal(SIGCHLD, SIG_IGN);
     // Reap and pending children that exited between the last call to waitpid() and setting SIG_IGN
     // for SIGCHLD above.
     while (waitpid(-1, nullptr, WNOHANG) > 0) {
     }
 
-    uevent_listener.Poll([&device_handler, &modalias_handler](const Uevent& uevent) {
-        HandleFirmwareEvent(uevent);
-        modalias_handler.HandleModaliasEvent(uevent);
-        device_handler.HandleDeviceEvent(uevent);
+    uevent_listener.Poll([&uevent_handlers](const Uevent& uevent) {
+        for (auto& uevent_handler : uevent_handlers) {
+            uevent_handler->HandleUevent(uevent);
+        }
         return ListenerAction::kContinue;
     });
 

init/ueventd_parser.cpp

@@ -84,6 +84,23 @@ Result<Success> ParseFirmwareDirectoriesLine(std::vector<std::string>&& args,
     return Success();
 }
 
+Result<Success> ParseModaliasHandlingLine(std::vector<std::string>&& args,
+                                          bool* enable_modalias_handling) {
+    if (args.size() != 2) {
+        return Error() << "modalias_handling lines take exactly one parameter";
+    }
+
+    if (args[1] == "enabled") {
+        *enable_modalias_handling = true;
+    } else if (args[1] == "disabled") {
+        *enable_modalias_handling = false;
+    } else {
+        return Error() << "modalias_handling takes either 'enabled' or 'disabled' as a parameter";
+    }
+
+    return Success();
+}
+
 class SubsystemParser : public SectionParser {
   public:
     SubsystemParser(std::vector<Subsystem>* subsystems) : subsystems_(subsystems) {}
@@ -182,6 +199,9 @@ UeventdConfiguration ParseConfig(const std::vector<std::string>& configs) {
     parser.AddSingleLineParser("firmware_directories",
                                std::bind(ParseFirmwareDirectoriesLine, _1,
                                          &ueventd_configuration.firmware_directories));
+    parser.AddSingleLineParser("modalias_handling",
+                               std::bind(ParseModaliasHandlingLine, _1,
+                                         &ueventd_configuration.enable_modalias_handling));
 
     for (const auto& config : configs) {
         parser.ParseConfig(config);

init/ueventd_parser.h

@@ -30,6 +30,7 @@ struct UeventdConfiguration {
     std::vector<SysfsPermissions> sysfs_permissions;
     std::vector<Permissions> dev_permissions;
     std::vector<std::string> firmware_directories;
+    bool enable_modalias_handling = false;
 };
 
 UeventdConfiguration ParseConfig(const std::vector<std::string>& configs);