core/jni/com_android_internal_os_Zygote.cpp - platform/frameworks/base - Git at Google

 /*
  * 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 <grp.h>
 #include <fcntl.h>
 #include <paths.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <unistd.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 <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 <inttypes.h>

 #include "android_runtime/AndroidRuntime.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");
       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: %d", 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: %d", 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, {%d, %d}) 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(%lld, %lld) 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(): %d", 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 :%d", source, target, 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: %d", source_user.string(), target_user.string(), 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: %d", target_user.string(), legacy, 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);
   jint *ar = env->GetIntArrayElements(fdsToClose, 0);
   if (!ar) {
       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");
       RuntimeAbort(env);
       continue;
     }
     ALOGV("Switching descriptor %d to /dev/null: %d", ar[i], errno);
     if (dup2(devnull, ar[i]) < 0) {
       ALOGE("Failed dup2() on descriptor %d", ar[i]);
       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'", buf);
   }
 }

   // Temporary timing check.
 uint64_t MsTime() {
   timespec now;
   clock_gettime(CLOCK_MONOTONIC, &now);
   return static_cast<uint64_t>(now.tv_sec) * UINT64_C(1000) + now.tv_nsec / UINT64_C(1000000);
 }


 void ckTime(uint64_t start, const char* where) {
   uint64_t now = MsTime();
   if ((now-start) > 1000) {
     // If we are taking more than a second, log about it.
     ALOGW("Slow operation: %"PRIu64" ms in %s", (uint64_t)(now-start), where);
   }
 }

 // 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) {
   uint64_t start = MsTime();
   SetSigChldHandler();
   ckTime(start, "ForkAndSpecializeCommon: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);

     ckTime(start, "ForkAndSpecializeCommon:Fork and detach");

     // 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", gid);
       RuntimeAbort(env);
     }

     rc = setresuid(uid, uid, uid);
     if (rc == -1) {
       ALOGE("setresuid(%d) failed", uid);
       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", new_personality);
         }
     }

     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();

     ckTime(start, "ForkAndSpecializeCommon:child process setup");

     env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags,
                               is_system_server ? NULL : instructionSet);
     ckTime(start, "ForkAndSpecializeCommon:PostForkChildHooks returns");
     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 = (jclass) env->NewGlobalRef(env->FindClass(kZygoteClassName));
   if (gZygoteClass == NULL) {
     RuntimeAbort(env);
   }
   gCallPostForkChildHooks = env->GetStaticMethodID(gZygoteClass, "callPostForkChildHooks",
                                                    "(ILjava/lang/String;)V");

   return AndroidRuntime::registerNativeMethods(env, "com/android/internal/os/Zygote",
       gMethods, NELEM(gMethods));
 }
 }  // namespace android
	/*
	* 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 <grp.h>
	#include <fcntl.h>
	#include <paths.h>
	#include <signal.h>
	#include <stdlib.h>
	#include <unistd.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 <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 <inttypes.h>

	#include "android_runtime/AndroidRuntime.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");
	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: %d", 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: %d", 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, {%d, %d}) 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(%lld, %lld) 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(): %d", 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 :%d", source, target, 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: %d", source_user.string(), target_user.string(), 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: %d", target_user.string(), legacy, 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);
	jint *ar = env->GetIntArrayElements(fdsToClose, 0);
	if (!ar) {
	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");
	RuntimeAbort(env);
	continue;
	}
	ALOGV("Switching descriptor %d to /dev/null: %d", ar[i], errno);
	if (dup2(devnull, ar[i]) < 0) {
	ALOGE("Failed dup2() on descriptor %d", ar[i]);
	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'", buf);
	}
	}

	// Temporary timing check.
	uint64_t MsTime() {
	timespec now;
	clock_gettime(CLOCK_MONOTONIC, &now);
	return static_cast<uint64_t>(now.tv_sec) * UINT64_C(1000) + now.tv_nsec / UINT64_C(1000000);
	}


	void ckTime(uint64_t start, const char* where) {
	uint64_t now = MsTime();
	if ((now-start) > 1000) {
	// If we are taking more than a second, log about it.
	ALOGW("Slow operation: %"PRIu64" ms in %s", (uint64_t)(now-start), where);
	}
	}

	// 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) {
	uint64_t start = MsTime();
	SetSigChldHandler();
	ckTime(start, "ForkAndSpecializeCommon: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);

	ckTime(start, "ForkAndSpecializeCommon:Fork and detach");

	// 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", gid);
	RuntimeAbort(env);
	}

	rc = setresuid(uid, uid, uid);
	if (rc == -1) {
	ALOGE("setresuid(%d) failed", uid);
	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", new_personality);
	}
	}

	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();

	ckTime(start, "ForkAndSpecializeCommon:child process setup");

	env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags,
	is_system_server ? NULL : instructionSet);
	ckTime(start, "ForkAndSpecializeCommon:PostForkChildHooks returns");
	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 = (jclass) env->NewGlobalRef(env->FindClass(kZygoteClassName));
	if (gZygoteClass == NULL) {
	RuntimeAbort(env);
	}
	gCallPostForkChildHooks = env->GetStaticMethodID(gZygoteClass, "callPostForkChildHooks",
	"(ILjava/lang/String;)V");

	return AndroidRuntime::registerNativeMethods(env, "com/android/internal/os/Zygote",
	gMethods, NELEM(gMethods));
	}
	} // namespace android