1 // /system/core/init/init.cpp
  2 int main(int argc, char** argv) {
  3     if (!strcmp(basename(argv[0]), "ueventd")) {
  4         return ueventd_main(argc, argv);
  5     }
  6 
  7     if (!strcmp(basename(argv[0]), "watchdogd")) {
  8         return watchdogd_main(argc, argv);
  9     }
 10 
 11     if (argc > 1 && !strcmp(argv[1], "subcontext")) {
 12         InitKernelLogging(argv);
 13         const BuiltinFunctionMap function_map;
 14         return SubcontextMain(argc, argv, &function_map);
 15     }
 16 
 17     if (REBOOT_BOOTLOADER_ON_PANIC) {
 18         InstallRebootSignalHandlers();
 19     }
 20 
 21     bool is_first_stage = (getenv("INIT_SECOND_STAGE") == nullptr);
 22 
 23     if (is_first_stage) {
 24         boot_clock::time_point start_time = boot_clock::now();
 25 
 26         // Clear the umask.
 27         umask(0);
 28 
 29         clearenv();
 30         setenv("PATH", _PATH_DEFPATH, 1);
 31         // Get the basic filesystem setup we need put together in the initramdisk
 32         // on / and then we‘ll let the rc file figure out the rest.
 33         mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755");
 34         mkdir("/dev/pts", 0755);
 35         mkdir("/dev/socket", 0755);
 36         mount("devpts", "/dev/pts", "devpts", 0, NULL);
 37         #define MAKE_STR(x) __STRING(x)
 38         mount("proc", "/proc", "proc", 0, "hidepid=2,gid=" MAKE_STR(AID_READPROC));
 39         // Don‘t expose the raw commandline to unprivileged processes.
 40         chmod("/proc/cmdline", 0440);
 41         gid_t groups[] = { AID_READPROC };
 42         setgroups(arraysize(groups), groups);
 43         mount("sysfs", "/sys", "sysfs", 0, NULL);
 44         mount("selinuxfs", "/sys/fs/selinux", "selinuxfs", 0, NULL);
 45 
 46         mknod("/dev/kmsg", S_IFCHR | 0600, makedev(1, 11));
 47 
 48         if constexpr (WORLD_WRITABLE_KMSG) {
 49             mknod("/dev/kmsg_debug", S_IFCHR | 0622, makedev(1, 11));
 50         }
 51 
 52         mknod("/dev/random", S_IFCHR | 0666, makedev(1, 8));
 53         mknod("/dev/urandom", S_IFCHR | 0666, makedev(1, 9));
 54 
 55         // Mount staging areas for devices managed by vold
 56         // See storage config details at http://source.android.com/devices/storage/
 57         mount("tmpfs", "/mnt", "tmpfs", MS_NOEXEC | MS_NOSUID | MS_NODEV,
 58               "mode=0755,uid=0,gid=1000");
 59         // /mnt/vendor is used to mount vendor-specific partitions that can not be
 60         // part of the vendor partition, e.g. because they are mounted read-write.
 61         mkdir("/mnt/vendor", 0755);
 62 
 63         // Now that tmpfs is mounted on /dev and we have /dev/kmsg, we can actually
 64         // talk to the outside world...
 65         InitKernelLogging(argv);
 66 
 67         LOG(INFO) << "init first stage started!";
 68 
 69         if (!DoFirstStageMount()) {
 70             LOG(FATAL) << "Failed to mount required partitions early ...";
 71         }
 72 
 73         SetInitAvbVersionInRecovery();
 74 
 75         // Enable seccomp if global boot option was passed (otherwise it is enabled in zygote).
 76         global_seccomp();
 77 
 78         // Set up SELinux, loading the SELinux policy.
 79         SelinuxSetupKernelLogging();
 80         SelinuxInitialize();
 81 
 82         // We‘re in the kernel domain, so re-exec init to transition to the init domain now
 83         // that the SELinux policy has been loaded.
 84         if (selinux_android_restorecon("/init", 0) == -1) {
 85             PLOG(FATAL) << "restorecon failed of /init failed";
 86         }
 87 
 88         setenv("INIT_SECOND_STAGE", "true", 1);
 89 
 90         static constexpr uint32_t kNanosecondsPerMillisecond = 1e6;
 91         uint64_t start_ms = start_time.time_since_epoch().count() / kNanosecondsPerMillisecond;
 92         setenv("INIT_STARTED_AT", std::to_string(start_ms).c_str(), 1);
 93 
 94         char* path = argv[0];
 95         char* args[] = { path, nullptr };
 96         execv(path, args);
 97 
 98         // execv() only returns if an error happened, in which case we
 99         // panic and never fall through this conditional.
100         PLOG(FATAL) << "execv(\"" << path << "\") failed";
101     }
102 
103     // At this point we‘re in the second stage of init.
104     InitKernelLogging(argv);
105     LOG(INFO) << "init second stage started!";
106 
107     // Set up a session keyring that all processes will have access to. It
108     // will hold things like FBE encryption keys. No process should override
109     // its session keyring.
110     keyctl_get_keyring_ID(KEY_SPEC_SESSION_KEYRING, 1);
111 
112     // Indicate that booting is in progress to background fw loaders, etc.
113     close(open("/dev/.booting", O_WRONLY | O_CREAT | O_CLOEXEC, 0000));
114 
115     property_init();
116 
117     // If arguments are passed both on the command line and in DT,
118     // properties set in DT always have priority over the command-line ones.
119     process_kernel_dt();
120     process_kernel_cmdline();
121 
122     // Propagate the kernel variables to internal variables
123     // used by init as well as the current required properties.
124     export_kernel_boot_props();
125 
126     // Make the time that init started available for bootstat to log.
127     property_set("ro.boottime.init", getenv("INIT_STARTED_AT"));
128     property_set("ro.boottime.init.selinux", getenv("INIT_SELINUX_TOOK"));
129 
130     // Set libavb version for Framework-only OTA match in Treble build.
131     const char* avb_version = getenv("INIT_AVB_VERSION");
132     if (avb_version) property_set("ro.boot.avb_version", avb_version);
133 
134     // Clean up our environment.
135     unsetenv("INIT_SECOND_STAGE");
136     unsetenv("INIT_STARTED_AT");
137     unsetenv("INIT_SELINUX_TOOK");
138     unsetenv("INIT_AVB_VERSION");
139 
140     // Now set up SELinux for second stage.
141     SelinuxSetupKernelLogging();
142     SelabelInitialize();
143     SelinuxRestoreContext();
144 
145     epoll_fd = epoll_create1(EPOLL_CLOEXEC);
146     if (epoll_fd == -1) {
147         PLOG(FATAL) << "epoll_create1 failed";
148     }
149 
150     sigchld_handler_init();
151 
152     if (!IsRebootCapable()) {
153         // If init does not have the CAP_SYS_BOOT capability, it is running in a container.
154         // In that case, receiving SIGTERM will cause the system to shut down.
155         InstallSigtermHandler();
156     }
157 
158     property_load_boot_defaults();
159     export_oem_lock_status();
160     start_property_service();
161     set_usb_controller();
162 
163     const BuiltinFunctionMap function_map;
164     Action::set_function_map(&function_map);
165 
166     subcontexts = InitializeSubcontexts();
167 
168     ActionManager& am = ActionManager::GetInstance();
169     ServiceList& sm = ServiceList::GetInstance();
170 
171     LoadBootScripts(am, sm);
172 
173     // Turning this on and letting the INFO logging be discarded adds 0.2s to
174     // Nexus 9 boot time, so it‘s disabled by default.
175     if (false) DumpState();
176 
177     am.QueueEventTrigger("early-init");
178 
179     // Queue an action that waits for coldboot done so we know ueventd has set up all of /dev...
180     am.QueueBuiltinAction(wait_for_coldboot_done_action, "wait_for_coldboot_done");
181     // ... so that we can start queuing up actions that require stuff from /dev.
182     am.QueueBuiltinAction(MixHwrngIntoLinuxRngAction, "MixHwrngIntoLinuxRng");
183     am.QueueBuiltinAction(SetMmapRndBitsAction, "SetMmapRndBits");
184     am.QueueBuiltinAction(SetKptrRestrictAction, "SetKptrRestrict");
185     am.QueueBuiltinAction(keychord_init_action, "keychord_init");
186     am.QueueBuiltinAction(console_init_action, "console_init");
187 
188     // Trigger all the boot actions to get us started.
189     am.QueueEventTrigger("init");
190 
191     // Repeat mix_hwrng_into_linux_rng in case /dev/hw_random or /dev/random
192     // wasn‘t ready immediately after wait_for_coldboot_done
193     am.QueueBuiltinAction(MixHwrngIntoLinuxRngAction, "MixHwrngIntoLinuxRng");
194 
195     // Don‘t mount filesystems or start core system services in charger mode.
196     std::string bootmode = GetProperty("ro.bootmode", "");
197     if (bootmode == "charger") {
198         am.QueueEventTrigger("charger");
199     } else {
200         am.QueueEventTrigger("late-init");
201     }
202 
203     // Run all property triggers based on current state of the properties.
204     am.QueueBuiltinAction(queue_property_triggers_action, "queue_property_triggers");
205 
206     while (true) {
207         // By default, sleep until something happens.
208         int epoll_timeout_ms = -1;
209 
210         if (do_shutdown && !shutting_down) {
211             do_shutdown = false;
212             if (HandlePowerctlMessage(shutdown_command)) {
213                 shutting_down = true;
214             }
215         }
216 
217         if (!(waiting_for_prop || Service::is_exec_service_running())) {
218             am.ExecuteOneCommand();
219         }
220         if (!(waiting_for_prop || Service::is_exec_service_running())) {
221             if (!shutting_down) {
222                 auto next_process_restart_time = RestartProcesses();
223 
224                 // If there‘s a process that needs restarting, wake up in time for that.
225                 if (next_process_restart_time) {
226                     epoll_timeout_ms = std::chrono::ceil<std::chrono::milliseconds>(
227                                            *next_process_restart_time - boot_clock::now())
228                                            .count();
229                     if (epoll_timeout_ms < 0) epoll_timeout_ms = 0;
230                 }
231             }
232 
233             // If there‘s more work to do, wake up again immediately.
234             if (am.HasMoreCommands()) epoll_timeout_ms = 0;
235         }
236 
237         epoll_event ev;
238         int nr = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd, &ev, 1, epoll_timeout_ms));
239         if (nr == -1) {
240             PLOG(ERROR) << "epoll_wait failed";
241         } else if (nr == 1) {
242             ((void (*)()) ev.data.ptr)();
243         }
244     }
245 
246     return 0;
247 }