| /* |
| * Copyright (C) 2008 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. |
| */ |
| |
| #define LOG_TAG "Zygote" |
| |
| // sys/mount.h has to come before linux/fs.h due to redefinition of MS_RDONLY, MS_BIND, etc |
| #include <sys/mount.h> |
| #include <linux/fs.h> |
| |
| #include <fcntl.h> |
| #include <grp.h> |
| #include <inttypes.h> |
| #include <paths.h> |
| #include <signal.h> |
| #include <stdlib.h> |
| #include <sys/capability.h> |
| #include <sys/personality.h> |
| #include <sys/prctl.h> |
| #include <sys/resource.h> |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| #include <sys/utsname.h> |
| #include <sys/wait.h> |
| #include <unistd.h> |
| |
| #include <cutils/fs.h> |
| #include <cutils/multiuser.h> |
| #include <cutils/sched_policy.h> |
| #include <private/android_filesystem_config.h> |
| #include <utils/String8.h> |
| #include <selinux/android.h> |
| #include <processgroup/processgroup.h> |
| |
| #include "core_jni_helpers.h" |
| #include "JNIHelp.h" |
| #include "ScopedLocalRef.h" |
| #include "ScopedPrimitiveArray.h" |
| #include "ScopedUtfChars.h" |
| |
| #include "nativebridge/native_bridge.h" |
| |
| namespace { |
| |
| using android::String8; |
| |
| static pid_t gSystemServerPid = 0; |
| |
| static const char kZygoteClassName[] = "com/android/internal/os/Zygote"; |
| static jclass gZygoteClass; |
| static jmethodID gCallPostForkChildHooks; |
| |
| // Must match values in com.android.internal.os.Zygote. |
| enum MountExternalKind { |
| MOUNT_EXTERNAL_NONE = 0, |
| MOUNT_EXTERNAL_SINGLEUSER = 1, |
| MOUNT_EXTERNAL_MULTIUSER = 2, |
| MOUNT_EXTERNAL_MULTIUSER_ALL = 3, |
| }; |
| |
| static void RuntimeAbort(JNIEnv* env) { |
| env->FatalError("RuntimeAbort"); |
| } |
| |
| // This signal handler is for zygote mode, since the zygote must reap its children |
| static void SigChldHandler(int /*signal_number*/) { |
| pid_t pid; |
| int status; |
| |
| while ((pid = waitpid(-1, &status, WNOHANG)) > 0) { |
| // Log process-death status that we care about. In general it is |
| // not safe to call LOG(...) from a signal handler because of |
| // possible reentrancy. However, we know a priori that the |
| // current implementation of LOG() is safe to call from a SIGCHLD |
| // handler in the zygote process. If the LOG() implementation |
| // changes its locking strategy or its use of syscalls within the |
| // lazy-init critical section, its use here may become unsafe. |
| if (WIFEXITED(status)) { |
| if (WEXITSTATUS(status)) { |
| ALOGI("Process %d exited cleanly (%d)", pid, WEXITSTATUS(status)); |
| } |
| } else if (WIFSIGNALED(status)) { |
| if (WTERMSIG(status) != SIGKILL) { |
| ALOGI("Process %d exited due to signal (%d)", pid, WTERMSIG(status)); |
| } |
| if (WCOREDUMP(status)) { |
| ALOGI("Process %d dumped core.", pid); |
| } |
| } |
| |
| // If the just-crashed process is the system_server, bring down zygote |
| // so that it is restarted by init and system server will be restarted |
| // from there. |
| if (pid == gSystemServerPid) { |
| ALOGE("Exit zygote because system server (%d) has terminated", pid); |
| kill(getpid(), SIGKILL); |
| } |
| } |
| |
| // Note that we shouldn't consider ECHILD an error because |
| // the secondary zygote might have no children left to wait for. |
| if (pid < 0 && errno != ECHILD) { |
| ALOGW("Zygote SIGCHLD error in waitpid: %s", strerror(errno)); |
| } |
| } |
| |
| // Configures the SIGCHLD handler for the zygote process. This is configured |
| // very late, because earlier in the runtime we may fork() and exec() |
| // other processes, and we want to waitpid() for those rather than |
| // have them be harvested immediately. |
| // |
| // This ends up being called repeatedly before each fork(), but there's |
| // no real harm in that. |
| static void SetSigChldHandler() { |
| struct sigaction sa; |
| memset(&sa, 0, sizeof(sa)); |
| sa.sa_handler = SigChldHandler; |
| |
| int err = sigaction(SIGCHLD, &sa, NULL); |
| if (err < 0) { |
| ALOGW("Error setting SIGCHLD handler: %s", strerror(errno)); |
| } |
| } |
| |
| // Sets the SIGCHLD handler back to default behavior in zygote children. |
| static void UnsetSigChldHandler() { |
| struct sigaction sa; |
| memset(&sa, 0, sizeof(sa)); |
| sa.sa_handler = SIG_DFL; |
| |
| int err = sigaction(SIGCHLD, &sa, NULL); |
| if (err < 0) { |
| ALOGW("Error unsetting SIGCHLD handler: %s", strerror(errno)); |
| } |
| } |
| |
| // Calls POSIX setgroups() using the int[] object as an argument. |
| // A NULL argument is tolerated. |
| static void SetGids(JNIEnv* env, jintArray javaGids) { |
| if (javaGids == NULL) { |
| return; |
| } |
| |
| ScopedIntArrayRO gids(env, javaGids); |
| if (gids.get() == NULL) { |
| RuntimeAbort(env); |
| } |
| int rc = setgroups(gids.size(), reinterpret_cast<const gid_t*>(&gids[0])); |
| if (rc == -1) { |
| ALOGE("setgroups failed"); |
| RuntimeAbort(env); |
| } |
| } |
| |
| // Sets the resource limits via setrlimit(2) for the values in the |
| // two-dimensional array of integers that's passed in. The second dimension |
| // contains a tuple of length 3: (resource, rlim_cur, rlim_max). NULL is |
| // treated as an empty array. |
| static void SetRLimits(JNIEnv* env, jobjectArray javaRlimits) { |
| if (javaRlimits == NULL) { |
| return; |
| } |
| |
| rlimit rlim; |
| memset(&rlim, 0, sizeof(rlim)); |
| |
| for (int i = 0; i < env->GetArrayLength(javaRlimits); ++i) { |
| ScopedLocalRef<jobject> javaRlimitObject(env, env->GetObjectArrayElement(javaRlimits, i)); |
| ScopedIntArrayRO javaRlimit(env, reinterpret_cast<jintArray>(javaRlimitObject.get())); |
| if (javaRlimit.size() != 3) { |
| ALOGE("rlimits array must have a second dimension of size 3"); |
| RuntimeAbort(env); |
| } |
| |
| rlim.rlim_cur = javaRlimit[1]; |
| rlim.rlim_max = javaRlimit[2]; |
| |
| int rc = setrlimit(javaRlimit[0], &rlim); |
| if (rc == -1) { |
| ALOGE("setrlimit(%d, {%ld, %ld}) failed", javaRlimit[0], rlim.rlim_cur, |
| rlim.rlim_max); |
| RuntimeAbort(env); |
| } |
| } |
| } |
| |
| // The debug malloc library needs to know whether it's the zygote or a child. |
| extern "C" int gMallocLeakZygoteChild; |
| |
| static void EnableKeepCapabilities(JNIEnv* env) { |
| int rc = prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0); |
| if (rc == -1) { |
| ALOGE("prctl(PR_SET_KEEPCAPS) failed"); |
| RuntimeAbort(env); |
| } |
| } |
| |
| static void DropCapabilitiesBoundingSet(JNIEnv* env) { |
| for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) { |
| int rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); |
| if (rc == -1) { |
| if (errno == EINVAL) { |
| ALOGE("prctl(PR_CAPBSET_DROP) failed with EINVAL. Please verify " |
| "your kernel is compiled with file capabilities support"); |
| } else { |
| ALOGE("prctl(PR_CAPBSET_DROP) failed"); |
| RuntimeAbort(env); |
| } |
| } |
| } |
| } |
| |
| static void SetCapabilities(JNIEnv* env, int64_t permitted, int64_t effective) { |
| __user_cap_header_struct capheader; |
| memset(&capheader, 0, sizeof(capheader)); |
| capheader.version = _LINUX_CAPABILITY_VERSION_3; |
| capheader.pid = 0; |
| |
| __user_cap_data_struct capdata[2]; |
| memset(&capdata, 0, sizeof(capdata)); |
| capdata[0].effective = effective; |
| capdata[1].effective = effective >> 32; |
| capdata[0].permitted = permitted; |
| capdata[1].permitted = permitted >> 32; |
| |
| if (capset(&capheader, &capdata[0]) == -1) { |
| ALOGE("capset(%" PRId64 ", %" PRId64 ") failed", permitted, effective); |
| RuntimeAbort(env); |
| } |
| } |
| |
| static void SetSchedulerPolicy(JNIEnv* env) { |
| errno = -set_sched_policy(0, SP_DEFAULT); |
| if (errno != 0) { |
| ALOGE("set_sched_policy(0, SP_DEFAULT) failed"); |
| RuntimeAbort(env); |
| } |
| } |
| |
| // Create a private mount namespace and bind mount appropriate emulated |
| // storage for the given user. |
| static bool MountEmulatedStorage(uid_t uid, jint mount_mode, bool force_mount_namespace) { |
| if (mount_mode == MOUNT_EXTERNAL_NONE && !force_mount_namespace) { |
| return true; |
| } |
| |
| // Create a second private mount namespace for our process |
| if (unshare(CLONE_NEWNS) == -1) { |
| ALOGW("Failed to unshare(): %s", strerror(errno)); |
| return false; |
| } |
| |
| if (mount_mode == MOUNT_EXTERNAL_NONE) { |
| return true; |
| } |
| |
| // See storage config details at http://source.android.com/tech/storage/ |
| userid_t user_id = multiuser_get_user_id(uid); |
| |
| // Create bind mounts to expose external storage |
| if (mount_mode == MOUNT_EXTERNAL_MULTIUSER || mount_mode == MOUNT_EXTERNAL_MULTIUSER_ALL) { |
| // These paths must already be created by init.rc |
| const char* source = getenv("EMULATED_STORAGE_SOURCE"); |
| const char* target = getenv("EMULATED_STORAGE_TARGET"); |
| const char* legacy = getenv("EXTERNAL_STORAGE"); |
| if (source == NULL || target == NULL || legacy == NULL) { |
| ALOGW("Storage environment undefined; unable to provide external storage"); |
| return false; |
| } |
| |
| // Prepare source paths |
| |
| // /mnt/shell/emulated/0 |
| const String8 source_user(String8::format("%s/%d", source, user_id)); |
| // /storage/emulated/0 |
| const String8 target_user(String8::format("%s/%d", target, user_id)); |
| |
| if (fs_prepare_dir(source_user.string(), 0000, 0, 0) == -1 |
| || fs_prepare_dir(target_user.string(), 0000, 0, 0) == -1) { |
| return false; |
| } |
| |
| if (mount_mode == MOUNT_EXTERNAL_MULTIUSER_ALL) { |
| // Mount entire external storage tree for all users |
| if (TEMP_FAILURE_RETRY(mount(source, target, NULL, MS_BIND, NULL)) == -1) { |
| ALOGW("Failed to mount %s to %s: %s", source, target, strerror(errno)); |
| return false; |
| } |
| } else { |
| // Only mount user-specific external storage |
| if (TEMP_FAILURE_RETRY(mount(source_user.string(), target_user.string(), NULL, |
| MS_BIND, NULL)) == -1) { |
| ALOGW("Failed to mount %s to %s: %s", source_user.string(), target_user.string(), |
| strerror(errno)); |
| return false; |
| } |
| } |
| |
| if (fs_prepare_dir(legacy, 0000, 0, 0) == -1) { |
| return false; |
| } |
| |
| // Finally, mount user-specific path into place for legacy users |
| if (TEMP_FAILURE_RETRY( |
| mount(target_user.string(), legacy, NULL, MS_BIND | MS_REC, NULL)) == -1) { |
| ALOGW("Failed to mount %s to %s: %s", target_user.string(), legacy, strerror(errno)); |
| return false; |
| } |
| } else { |
| ALOGW("Mount mode %d unsupported", mount_mode); |
| return false; |
| } |
| |
| return true; |
| } |
| |
| static bool NeedsNoRandomizeWorkaround() { |
| #if !defined(__arm__) |
| return false; |
| #else |
| int major; |
| int minor; |
| struct utsname uts; |
| if (uname(&uts) == -1) { |
| return false; |
| } |
| |
| if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) { |
| return false; |
| } |
| |
| // Kernels before 3.4.* need the workaround. |
| return (major < 3) || ((major == 3) && (minor < 4)); |
| #endif |
| } |
| |
| // Utility to close down the Zygote socket file descriptors while |
| // the child is still running as root with Zygote's privileges. Each |
| // descriptor (if any) is closed via dup2(), replacing it with a valid |
| // (open) descriptor to /dev/null. |
| |
| static void DetachDescriptors(JNIEnv* env, jintArray fdsToClose) { |
| if (!fdsToClose) { |
| return; |
| } |
| jsize count = env->GetArrayLength(fdsToClose); |
| ScopedIntArrayRO ar(env, fdsToClose); |
| if (ar.get() == NULL) { |
| ALOGE("Bad fd array"); |
| RuntimeAbort(env); |
| } |
| jsize i; |
| int devnull; |
| for (i = 0; i < count; i++) { |
| devnull = open("/dev/null", O_RDWR); |
| if (devnull < 0) { |
| ALOGE("Failed to open /dev/null: %s", strerror(errno)); |
| RuntimeAbort(env); |
| continue; |
| } |
| ALOGV("Switching descriptor %d to /dev/null: %s", ar[i], strerror(errno)); |
| if (dup2(devnull, ar[i]) < 0) { |
| ALOGE("Failed dup2() on descriptor %d: %s", ar[i], strerror(errno)); |
| RuntimeAbort(env); |
| } |
| close(devnull); |
| } |
| } |
| |
| void SetThreadName(const char* thread_name) { |
| bool hasAt = false; |
| bool hasDot = false; |
| const char* s = thread_name; |
| while (*s) { |
| if (*s == '.') { |
| hasDot = true; |
| } else if (*s == '@') { |
| hasAt = true; |
| } |
| s++; |
| } |
| const int len = s - thread_name; |
| if (len < 15 || hasAt || !hasDot) { |
| s = thread_name; |
| } else { |
| s = thread_name + len - 15; |
| } |
| // pthread_setname_np fails rather than truncating long strings. |
| char buf[16]; // MAX_TASK_COMM_LEN=16 is hard-coded into bionic |
| strlcpy(buf, s, sizeof(buf)-1); |
| errno = pthread_setname_np(pthread_self(), buf); |
| if (errno != 0) { |
| ALOGW("Unable to set the name of current thread to '%s': %s", buf, strerror(errno)); |
| } |
| } |
| |
| // Utility routine to fork zygote and specialize the child process. |
| static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids, |
| jint debug_flags, jobjectArray javaRlimits, |
| jlong permittedCapabilities, jlong effectiveCapabilities, |
| jint mount_external, |
| jstring java_se_info, jstring java_se_name, |
| bool is_system_server, jintArray fdsToClose, |
| jstring instructionSet, jstring dataDir) { |
| SetSigChldHandler(); |
| |
| pid_t pid = fork(); |
| |
| if (pid == 0) { |
| // The child process. |
| gMallocLeakZygoteChild = 1; |
| |
| // Clean up any descriptors which must be closed immediately |
| DetachDescriptors(env, fdsToClose); |
| |
| // Keep capabilities across UID change, unless we're staying root. |
| if (uid != 0) { |
| EnableKeepCapabilities(env); |
| } |
| |
| DropCapabilitiesBoundingSet(env); |
| |
| bool use_native_bridge = !is_system_server && (instructionSet != NULL) |
| && android::NativeBridgeAvailable(); |
| if (use_native_bridge) { |
| ScopedUtfChars isa_string(env, instructionSet); |
| use_native_bridge = android::NeedsNativeBridge(isa_string.c_str()); |
| } |
| if (use_native_bridge && dataDir == NULL) { |
| // dataDir should never be null if we need to use a native bridge. |
| // In general, dataDir will never be null for normal applications. It can only happen in |
| // special cases (for isolated processes which are not associated with any app). These are |
| // launched by the framework and should not be emulated anyway. |
| use_native_bridge = false; |
| ALOGW("Native bridge will not be used because dataDir == NULL."); |
| } |
| |
| if (!MountEmulatedStorage(uid, mount_external, use_native_bridge)) { |
| ALOGW("Failed to mount emulated storage: %s", strerror(errno)); |
| if (errno == ENOTCONN || errno == EROFS) { |
| // When device is actively encrypting, we get ENOTCONN here |
| // since FUSE was mounted before the framework restarted. |
| // When encrypted device is booting, we get EROFS since |
| // FUSE hasn't been created yet by init. |
| // In either case, continue without external storage. |
| } else { |
| ALOGE("Cannot continue without emulated storage"); |
| RuntimeAbort(env); |
| } |
| } |
| |
| if (!is_system_server) { |
| int rc = createProcessGroup(uid, getpid()); |
| if (rc != 0) { |
| if (rc == -EROFS) { |
| ALOGW("createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?"); |
| } else { |
| ALOGE("createProcessGroup(%d, %d) failed: %s", uid, pid, strerror(-rc)); |
| } |
| } |
| } |
| |
| SetGids(env, javaGids); |
| |
| SetRLimits(env, javaRlimits); |
| |
| if (use_native_bridge) { |
| ScopedUtfChars isa_string(env, instructionSet); |
| ScopedUtfChars data_dir(env, dataDir); |
| android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str()); |
| } |
| |
| int rc = setresgid(gid, gid, gid); |
| if (rc == -1) { |
| ALOGE("setresgid(%d) failed: %s", gid, strerror(errno)); |
| RuntimeAbort(env); |
| } |
| |
| rc = setresuid(uid, uid, uid); |
| if (rc == -1) { |
| ALOGE("setresuid(%d) failed: %s", uid, strerror(errno)); |
| RuntimeAbort(env); |
| } |
| |
| if (NeedsNoRandomizeWorkaround()) { |
| // Work around ARM kernel ASLR lossage (http://b/5817320). |
| int old_personality = personality(0xffffffff); |
| int new_personality = personality(old_personality | ADDR_NO_RANDOMIZE); |
| if (new_personality == -1) { |
| ALOGW("personality(%d) failed: %s", new_personality, strerror(errno)); |
| } |
| } |
| |
| SetCapabilities(env, permittedCapabilities, effectiveCapabilities); |
| |
| SetSchedulerPolicy(env); |
| |
| const char* se_info_c_str = NULL; |
| ScopedUtfChars* se_info = NULL; |
| if (java_se_info != NULL) { |
| se_info = new ScopedUtfChars(env, java_se_info); |
| se_info_c_str = se_info->c_str(); |
| if (se_info_c_str == NULL) { |
| ALOGE("se_info_c_str == NULL"); |
| RuntimeAbort(env); |
| } |
| } |
| const char* se_name_c_str = NULL; |
| ScopedUtfChars* se_name = NULL; |
| if (java_se_name != NULL) { |
| se_name = new ScopedUtfChars(env, java_se_name); |
| se_name_c_str = se_name->c_str(); |
| if (se_name_c_str == NULL) { |
| ALOGE("se_name_c_str == NULL"); |
| RuntimeAbort(env); |
| } |
| } |
| rc = selinux_android_setcontext(uid, is_system_server, se_info_c_str, se_name_c_str); |
| if (rc == -1) { |
| ALOGE("selinux_android_setcontext(%d, %d, \"%s\", \"%s\") failed", uid, |
| is_system_server, se_info_c_str, se_name_c_str); |
| RuntimeAbort(env); |
| } |
| |
| // Make it easier to debug audit logs by setting the main thread's name to the |
| // nice name rather than "app_process". |
| if (se_info_c_str == NULL && is_system_server) { |
| se_name_c_str = "system_server"; |
| } |
| if (se_info_c_str != NULL) { |
| SetThreadName(se_name_c_str); |
| } |
| |
| delete se_info; |
| delete se_name; |
| |
| UnsetSigChldHandler(); |
| |
| env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags, |
| is_system_server ? NULL : instructionSet); |
| if (env->ExceptionCheck()) { |
| ALOGE("Error calling post fork hooks."); |
| RuntimeAbort(env); |
| } |
| } else if (pid > 0) { |
| // the parent process |
| } |
| return pid; |
| } |
| } // anonymous namespace |
| |
| namespace android { |
| |
| 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) { |
| // Grant CAP_WAKE_ALARM to the Bluetooth process. |
| jlong capabilities = 0; |
| if (uid == AID_BLUETOOTH) { |
| capabilities |= (1LL << CAP_WAKE_ALARM); |
| } |
| |
| return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags, |
| rlimits, capabilities, capabilities, mount_external, se_info, |
| se_name, false, fdsToClose, instructionSet, appDataDir); |
| } |
| |
| 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, |
| NULL, 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 JNINativeMethod gMethods[] = { |
| { "nativeForkAndSpecialize", |
| "(II[II[[IILjava/lang/String;Ljava/lang/String;[ILjava/lang/String;Ljava/lang/String;)I", |
| (void *) com_android_internal_os_Zygote_nativeForkAndSpecialize }, |
| { "nativeForkSystemServer", "(II[II[[IJJ)I", |
| (void *) com_android_internal_os_Zygote_nativeForkSystemServer } |
| }; |
| |
| int register_com_android_internal_os_Zygote(JNIEnv* env) { |
| gZygoteClass = MakeGlobalRefOrDie(env, FindClassOrDie(env, kZygoteClassName)); |
| gCallPostForkChildHooks = GetStaticMethodIDOrDie(env, gZygoteClass, "callPostForkChildHooks", |
| "(ILjava/lang/String;)V"); |
| |
| return RegisterMethodsOrDie(env, "com/android/internal/os/Zygote", gMethods, NELEM(gMethods)); |
| } |
| } // namespace android |
| |