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/*
* 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.
*/
#include <grp.h>
#include <paths.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "cutils/sched_policy.h"
#include "debugger.h"
#include "jni_internal.h"
#include "JNIHelp.h"
#include "ScopedLocalRef.h"
#include "ScopedPrimitiveArray.h"
#include "ScopedUtfChars.h"
#include "thread.h"
#if defined(HAVE_PRCTL)
#include <sys/prctl.h>
#endif
#include <selinux/android.h>
#if defined(__linux__)
#include <sys/personality.h>
#include <sys/utsname.h>
#endif
namespace art {
static pid_t gSystemServerPid = 0;
// Must match values in dalvik.system.Zygote.
enum MountExternalKind {
MOUNT_EXTERNAL_NONE = 0,
MOUNT_EXTERNAL_SINGLEUSER = 1,
MOUNT_EXTERNAL_MULTIUSER = 2,
};
static void Zygote_nativeExecShell(JNIEnv* env, jclass, jstring javaCommand) {
ScopedUtfChars command(env, javaCommand);
if (command.c_str() == NULL) {
return;
}
const char* argp[] = {_PATH_BSHELL, "-c", command.c_str(), NULL};
LOG(INFO) << "Exec: " << argp[0] << ' ' << argp[1] << ' ' << argp[2];
execv(_PATH_BSHELL, const_cast<char**>(argp));
exit(127);
}
// 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)) {
LOG(INFO) << "Process " << pid << " exited cleanly (" << WEXITSTATUS(status) << ")";
} else if (false) {
LOG(INFO) << "Process " << pid << " exited cleanly (" << WEXITSTATUS(status) << ")";
}
} else if (WIFSIGNALED(status)) {
if (WTERMSIG(status) != SIGKILL) {
LOG(INFO) << "Process " << pid << " terminated by signal (" << WTERMSIG(status) << ")";
} else if (false) {
LOG(INFO) << "Process " << pid << " terminated by signal (" << WTERMSIG(status) << ")";
}
#ifdef WCOREDUMP
if (WCOREDUMP(status)) {
LOG(INFO) << "Process " << pid << " dumped core";
}
#endif /* ifdef WCOREDUMP */
}
// 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) {
LOG(ERROR) << "Exit zygote because system server (" << pid << ") has terminated";
kill(getpid(), SIGKILL);
}
}
if (pid < 0) {
PLOG(WARNING) << "Zygote SIGCHLD error in waitpid";
}
}
// 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) {
PLOG(WARNING) << "Error setting SIGCHLD handler";
}
}
// 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) {
PLOG(WARNING) << "Error unsetting SIGCHLD handler";
}
}
// 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;
}
COMPILE_ASSERT(sizeof(gid_t) == sizeof(jint), sizeof_gid_and_jint_are_differerent);
ScopedIntArrayRO gids(env, javaGids);
CHECK(gids.get() != NULL);
int rc = setgroups(gids.size(), reinterpret_cast<const gid_t*>(&gids[0]));
if (rc == -1) {
PLOG(FATAL) << "setgroups failed";
}
}
// 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) {
LOG(FATAL) << "rlimits array must have a second dimension of size 3";
}
rlim.rlim_cur = javaRlimit[1];
rlim.rlim_max = javaRlimit[2];
int rc = setrlimit(javaRlimit[0], &rlim);
if (rc == -1) {
PLOG(FATAL) << "setrlimit(" << javaRlimit[0] << ", "
<< "{" << rlim.rlim_cur << ", " << rlim.rlim_max << "}) failed";
}
}
}
#if defined(HAVE_ANDROID_OS)
// The debug malloc library needs to know whether it's the zygote or a child.
extern "C" int gMallocLeakZygoteChild;
static void EnableDebugger() {
// To let a non-privileged gdbserver attach to this
// process, we must set our dumpable flag.
if (prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) == -1) {
PLOG(ERROR) << "prctl(PR_SET_DUMPABLE) failed for pid " << getpid();
}
// We don't want core dumps, though, so set the core dump size to 0.
rlimit rl;
rl.rlim_cur = 0;
rl.rlim_max = RLIM_INFINITY;
if (setrlimit(RLIMIT_CORE, &rl) == -1) {
PLOG(ERROR) << "setrlimit(RLIMIT_CORE) failed for pid " << getpid();
}
}
static void EnableKeepCapabilities() {
int rc = prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);
if (rc == -1) {
PLOG(FATAL) << "prctl(PR_SET_KEEPCAPS) failed";
}
}
static void SetCapabilities(int64_t permitted, int64_t effective) {
__user_cap_header_struct capheader;
__user_cap_data_struct capdata;
memset(&capheader, 0, sizeof(capheader));
memset(&capdata, 0, sizeof(capdata));
capheader.version = _LINUX_CAPABILITY_VERSION;
capheader.pid = 0;
capdata.effective = effective;
capdata.permitted = permitted;
if (capset(&capheader, &capdata) != 0) {
PLOG(FATAL) << "capset(" << permitted << ", " << effective << ") failed";
}
}
static void SetSchedulerPolicy() {
errno = -set_sched_policy(0, SP_DEFAULT);
if (errno != 0) {
PLOG(FATAL) << "set_sched_policy(0, SP_DEFAULT) failed";
}
}
#else
static int gMallocLeakZygoteChild = 0;
static void EnableDebugger() {}
static void EnableKeepCapabilities() {}
static void SetCapabilities(int64_t, int64_t) {}
static void SetSchedulerPolicy() {}
#endif
static void EnableDebugFeatures(uint32_t debug_flags) {
// Must match values in dalvik.system.Zygote.
enum {
DEBUG_ENABLE_DEBUGGER = 1,
DEBUG_ENABLE_CHECKJNI = 1 << 1,
DEBUG_ENABLE_ASSERT = 1 << 2,
DEBUG_ENABLE_SAFEMODE = 1 << 3,
DEBUG_ENABLE_JNI_LOGGING = 1 << 4,
};
if ((debug_flags & DEBUG_ENABLE_CHECKJNI) != 0) {
Runtime* runtime = Runtime::Current();
JavaVMExt* vm = runtime->GetJavaVM();
if (!vm->check_jni) {
LOG(DEBUG) << "Late-enabling -Xcheck:jni";
vm->SetCheckJniEnabled(true);
// There's only one thread running at this point, so only one JNIEnv to fix up.
Thread::Current()->GetJniEnv()->SetCheckJniEnabled(true);
} else {
LOG(DEBUG) << "Not late-enabling -Xcheck:jni (already on)";
}
debug_flags &= ~DEBUG_ENABLE_CHECKJNI;
}
if ((debug_flags & DEBUG_ENABLE_JNI_LOGGING) != 0) {
gLogVerbosity.third_party_jni = true;
debug_flags &= ~DEBUG_ENABLE_JNI_LOGGING;
}
Dbg::SetJdwpAllowed((debug_flags & DEBUG_ENABLE_DEBUGGER) != 0);
if ((debug_flags & DEBUG_ENABLE_DEBUGGER) != 0) {
EnableDebugger();
}
debug_flags &= ~DEBUG_ENABLE_DEBUGGER;
// These two are for backwards compatibility with Dalvik.
debug_flags &= ~DEBUG_ENABLE_ASSERT;
debug_flags &= ~DEBUG_ENABLE_SAFEMODE;
if (debug_flags != 0) {
LOG(ERROR) << StringPrintf("Unknown bits set in debug_flags: %#x", debug_flags);
}
}
// Create private mount space for this process and mount SD card
// into it, based on the active user.
static void MountExternalStorage(uid_t uid, jint mount_external) {
if (mount_external == MOUNT_EXTERNAL_NONE) {
return;
}
#if 0
userid_t user_id = multiuser_getUserId(uid);
// Create private mount namespace for our process.
if (unshare(CLONE_NEWNS) == -1) {
PLOG(FATAL) << "unshare(CLONE_NEWNS) failed";
}
// Mark rootfs as being a slave in our process so that changes
// from parent namespace flow into our process.
if (mount("rootfs", "/", NULL, (MS_SLAVE | MS_REC), NULL) == -1) {
PLOG(FATAL) << "mount(\"rootfs\", \"/\", NULL, (MS_SLAVE | MS_REC), NULL) failed";
}
// Create bind mount from specific path.
if (mount_external == MOUNT_EXTERNAL_SINGLEUSER) {
if (mount(EXTERNAL_STORAGE_SYSTEM, EXTERNAL_STORAGE_APP, "none", MS_BIND, NULL) == -1) {
PLOG(FATAL) << "mount(\"" << EXTERNAL_STORAGE_SYSTEM << "\", \"" << EXTERNAL_STORAGE_APP << "\", \"none\", MS_BIND, NULL) failed";
}
} else if (mount_external == MOUNT_EXTERNAL_MULTIUSER) {
// Assume path has already been created by installd.
std::string source_path(StringPrintf("%s/%d", EXTERNAL_STORAGE_SYSTEM, user_id));
if (mount(source_path.c_str(), EXTERNAL_STORAGE_APP, "none", MS_BIND, NULL) == -1) {
PLOG(FATAL) << "mount(\"" << source_path.c_str() << "\", \"" << EXTERNAL_STORAGE_APP << "\", \"none\", MS_BIND, NULL) failed";
}
} else {
LOG(FATAL) << "Mount mode unsupported: " << mount_external;
}
#else
UNUSED(uid);
UNIMPLEMENTED(FATAL);
#endif
}
#if defined(__linux__)
static bool NeedsNoRandomizeWorkaround() {
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 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) {
Runtime* runtime = Runtime::Current();
CHECK(runtime->IsZygote()) << "runtime instance not started with -Xzygote";
if (!runtime->PreZygoteFork()) {
LOG(FATAL) << "pre-fork heap failed";
}
SetSigChldHandler();
// Grab thread before fork potentially makes Thread::pthread_key_self_ unusable.
Thread* self = Thread::Current();
// dvmDumpLoaderStats("zygote"); // TODO: ?
pid_t pid = fork();
if (pid == 0) {
// The child process.
gMallocLeakZygoteChild = 1;
// Keep capabilities across UID change, unless we're staying root.
if (uid != 0) {
EnableKeepCapabilities();
}
MountExternalStorage(uid, mount_external);
SetGids(env, javaGids);
SetRLimits(env, javaRlimits);
int rc = setgid(gid);
if (rc == -1) {
PLOG(FATAL) << "setgid(" << gid << ") failed";
}
rc = setuid(uid);
if (rc == -1) {
PLOG(FATAL) << "setuid(" << uid << ") failed";
}
#if defined(__linux__)
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) {
PLOG(WARNING) << "personality(" << new_personality << ") failed";
}
}
#endif
SetCapabilities(permittedCapabilities, effectiveCapabilities);
SetSchedulerPolicy();
#if defined(HAVE_ANDROID_OS)
{
const char* se_info_c_str = NULL;
UniquePtr<ScopedUtfChars> se_info;
if (java_se_info != NULL) {
se_info.reset(new ScopedUtfChars(env, java_se_info));
se_info_c_str = se_info->c_str();
CHECK(se_info_c_str != NULL);
}
const char* se_name_c_str = NULL;
UniquePtr<ScopedUtfChars> se_name;
if (java_se_name != NULL) {
se_name.reset(new ScopedUtfChars(env, java_se_name));
se_name_c_str = se_name->c_str();
CHECK(se_name_c_str != NULL);
}
rc = selinux_android_setcontext(uid, is_system_server, se_info_c_str, se_name_c_str);
if (rc == -1) {
PLOG(FATAL) << "selinux_android_setcontext(" << uid << ", "
<< (is_system_server ? "true" : "false") << ", "
<< "\"" << se_info_c_str << "\", \"" << se_name_c_str << "\") failed";
}
}
#else
UNUSED(is_system_server);
UNUSED(java_se_info);
UNUSED(java_se_name);
#endif
// Our system thread ID, etc, has changed so reset Thread state.
self->InitAfterFork();
EnableDebugFeatures(debug_flags);
UnsetSigChldHandler();
runtime->DidForkFromZygote();
} else if (pid > 0) {
// the parent process
}
return pid;
}
static jint 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) {
return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags, rlimits, 0, 0, mount_external, se_info, se_name, false);
}
static jint 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);
if (pid > 0) {
// The zygote process checks whether the child process has died or not.
LOG(INFO) << "System server process " << pid << " has been created";
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) {
LOG(FATAL) << "System server process " << pid << " has died. Restarting Zygote!";
}
}
return pid;
}
static JNINativeMethod gMethods[] = {
NATIVE_METHOD(Zygote, nativeExecShell, "(Ljava/lang/String;)V"),
//NATIVE_METHOD(Zygote, nativeFork, "()I"),
NATIVE_METHOD(Zygote, nativeForkAndSpecialize, "(II[II[[IILjava/lang/String;Ljava/lang/String;)I"),
NATIVE_METHOD(Zygote, nativeForkSystemServer, "(II[II[[IJJ)I"),
};
void register_dalvik_system_Zygote(JNIEnv* env) {
REGISTER_NATIVE_METHODS("dalvik/system/Zygote");
}
} // namespace art