static void com_android_internal_os_Zygote_nativeAllowFileAcrossFork(
JNIEnv* env, jclass, jstring path) {
ScopedUtfChars path_native(env, path);
const char* path_cstr = path_native.c_str();
if (!path_cstr) {
RuntimeAbort(env, __LINE__, "path_cstr == nullptr");
}
FileDescriptorWhitelist::Get()->Allow(path_cstr);
}
int register_com_android_internal_os_Zygote(JNIEnv* env) {
gZygoteClass = (jclass) env->NewGlobalRef(env->FindClass(kZygoteClassName));
if (gZygoteClass == NULL) {
RuntimeAbort(env);
}
gCallPostForkChildHooks = env->GetStaticMethodID(gZygoteClass, "callPostForkChildHooks", "(I)V");
return AndroidRuntime::registerNativeMethods(env, "com/android/internal/os/Zygote",
gMethods, NELEM(gMethods));
}
static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) {
// Zygote process unmount root storage space initially before every child processes are forked.
// Every forked child processes (include SystemServer) only mount their own root storage space
// and no need unmount storage operation in MountEmulatedStorage method.
// Zygote process does not utilize root storage spaces and unshares its mount namespace below.
// See storage config details at http://source.android.com/tech/storage/
// Create private mount namespace shared by all children
if (unshare(CLONE_NEWNS) == -1) {
RuntimeAbort(env, __LINE__, "Failed to unshare()");
return;
}
// Mark rootfs as being a slave so that changes from default
// namespace only flow into our children.
if (mount("rootfs", "/", nullptr, (MS_SLAVE | MS_REC), nullptr) == -1) {
RuntimeAbort(env, __LINE__, "Failed to mount() rootfs as MS_SLAVE");
return;
}
// Create a staging tmpfs that is shared by our children; they will
// bind mount storage into their respective private namespaces, which
// are isolated from each other.
const char* target_base = getenv("EMULATED_STORAGE_TARGET");
if (target_base != nullptr) {
#define STRINGIFY_UID(x) __STRING(x)
if (mount("tmpfs", target_base, "tmpfs", MS_NOSUID | MS_NODEV,
"uid=0,gid=" STRINGIFY_UID(AID_SDCARD_R) ",mode=0751") == -1) {
ALOGE("Failed to mount tmpfs to %s", target_base);
RuntimeAbort(env, __LINE__, "Failed to mount tmpfs");
return;
}
#undef STRINGIFY_UID
}
UnmountTree("/storage");
}
static jint com_android_internal_os_Zygote_nativeForkSystemServer(
JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids,
jint runtime_flags, jobjectArray rlimits, jlong permitted_capabilities,
jlong effective_capabilities) {
pid_t pid = ForkCommon(env, true,
/* managed_fds_to_close= */ nullptr,
/* managed_fds_to_ignore= */ nullptr);
if (pid == 0) {
SpecializeCommon(env, uid, gid, gids, runtime_flags, rlimits,
permitted_capabilities, effective_capabilities,
MOUNT_EXTERNAL_DEFAULT, nullptr, nullptr, true,
false, nullptr, nullptr);
} else if (pid > 0) {
// The zygote process checks whether the child process has died or not.
ALOGI("System server process %d has been created", pid);
gSystemServerPid = pid;
// There is a slight window that the system server process has crashed
// but it went unnoticed because we haven't published its pid yet. So
// we recheck here just to make sure that all is well.
int status;
if (waitpid(pid, &status, WNOHANG) == pid) {
ALOGE("System server process %d has died. Restarting Zygote!", pid);
RuntimeAbort(env, __LINE__, "System server process has died. Restarting Zygote!");
}
bool low_ram_device = GetBoolProperty("ro.config.low_ram", false);
bool per_app_memcg = GetBoolProperty("ro.config.per_app_memcg", low_ram_device);
if (per_app_memcg) {
// Assign system_server to the correct memory cgroup.
// Not all devices mount /dev/memcg so check for the file first
// to avoid unnecessarily printing errors and denials in the logs.
if (!access("/dev/memcg/system/tasks", F_OK) &&
!WriteStringToFile(StringPrintf("%d", pid), "/dev/memcg/system/tasks")) {
ALOGE("couldn't write %d to /dev/memcg/system/tasks", pid);
}
}
}
return pid;
}
static jint com_android_internal_os_Zygote_nativeForkSystemServer(
JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids,
jint debug_flags, jobjectArray rlimits, jlong permittedCapabilities,
jlong effectiveCapabilities) {
pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids,
debug_flags, rlimits,
permittedCapabilities, effectiveCapabilities,
MOUNT_EXTERNAL_NONE, NULL, NULL, true, NULL);
if (pid > 0) {
// The zygote process checks whether the child process has died or not.
ALOGI("System server process %d has been created", pid);
gSystemServerPid = pid;
// There is a slight window that the system server process has crashed
// but it went unnoticed because we haven't published its pid yet. So
// we recheck here just to make sure that all is well.
int status;
if (waitpid(pid, &status, WNOHANG) == pid) {
ALOGE("System server process %d has died. Restarting Zygote!", pid);
RuntimeAbort(env);
}
}
return pid;
}
static jint com_android_internal_os_Zygote_nativeForkAndSpecialize(
JNIEnv* env, jclass, jint uid, jint gid, jintArray gids,
jint debug_flags, jobjectArray rlimits,
jint mount_external, jstring se_info, jstring se_name,
jintArray fdsToClose, jstring instructionSet, jstring appDataDir) {
jlong capabilities = 0;
// Grant CAP_WAKE_ALARM to the Bluetooth process.
if (uid == AID_BLUETOOTH) {
capabilities |= (1LL << CAP_WAKE_ALARM);
}
// Grant CAP_BLOCK_SUSPEND to processes that belong to GID "wakelock"
bool gid_wakelock_found = false;
if (gid == AID_WAKELOCK) {
gid_wakelock_found = true;
} else if (gids != NULL) {
jsize gids_num = env->GetArrayLength(gids);
ScopedIntArrayRO ar(env, gids);
if (ar.get() == NULL) {
RuntimeAbort(env, __LINE__, "Bad gids array");
}
for (int i = 0; i < gids_num; i++) {
if (ar[i] == AID_WAKELOCK) {
gid_wakelock_found = true;
break;
}
}
}
if (gid_wakelock_found) {
capabilities |= (1LL << CAP_BLOCK_SUSPEND);
}
return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags,
rlimits, capabilities, capabilities, mount_external, se_info,
se_name, false, fdsToClose, instructionSet, appDataDir);
}
