blob: 7c0b6a630c2f4a7a08128a78999d7ec14cfb49da [file] [log] [blame]
/*
* 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 "jni_internal.h"
#include "JNIHelp.h"
#include "ScopedLocalRef.h"
#include "ScopedPrimitiveArray.h"
#include "ScopedUtfChars.h"
#include "JniConstants.h" // Last to avoid problems with LOG redefinition.
#include <grp.h>
#include <paths.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "thread.h"
namespace art {
namespace {
static pid_t gSystemServerPid = 0;
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, (char**)argp);
exit(127);
}
// This signal handler is for zygote mode, since the zygote must reap its children
void sigchldHandler(int s) {
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(FATAL) << "Exit zygote because system server (" << pid << ") has terminated";
}
}
if (pid < 0) {
PLOG(WARNING) << "Zygote SIGCHLD error in waitpid";
}
}
// configure 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.
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";
}
}
// Set the SIGCHLD handler back to default behavior in zygote children
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.
int setGids(JNIEnv* env, jintArray javaGids) {
if (javaGids == NULL) {
return 0;
}
COMPILE_ASSERT(sizeof(gid_t) == sizeof(jint), sizeof_gid_and_jint_are_differerent);
ScopedIntArrayRO gids(env, javaGids);
if (gids.get() == NULL) {
return -1;
}
return setgroups(gids.size(), (const gid_t *) &gids[0]);
}
// 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.
//
// -1 is returned on error.
int setRlimits(JNIEnv* env, jobjectArray javaRlimits) {
if (javaRlimits == NULL) {
return 0;
}
struct 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(ERROR) << "rlimits array must have a second dimension of size 3";
return -1;
}
rlim.rlim_cur = javaRlimit[1];
rlim.rlim_max = javaRlimit[2];
int err = setrlimit(javaRlimit[0], &rlim);
if (err < 0) {
return -1;
}
}
return 0;
}
// Set Linux capability flags.
//
// Returns 0 on success, errno on failure.
int setCapabilities(int64_t permitted, int64_t effective) {
#ifdef HAVE_ANDROID_OS
struct __user_cap_header_struct capheader;
struct __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) {
return errno;
}
#endif /*HAVE_ANDROID_OS*/
return 0;
}
#ifdef HAVE_ANDROID_OS
extern "C" int gMallocLeakZygoteChild;
#endif
// Utility routine to fork zygote and specialize the child process.
pid_t forkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids,
jint debugFlags, jobjectArray javaRlimits,
jlong permittedCapabilities, jlong effectiveCapabilities)
{
Runtime* runtime = Runtime::Current();
CHECK(runtime->IsZygote()) << "runtime instance not started with -Xzygote";
if (false) { // TODO: do we need do anything special like !dvmGcPreZygoteFork()?
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
#ifdef HAVE_ANDROID_OS
gMallocLeakZygoteChild = 1;
// keep caps across UID change, unless we're staying root */
if (uid != 0) {
int err = prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);
if (err < 0) {
PLOG(FATAL) << "cannot PR_SET_KEEPCAPS";
}
}
#endif // HAVE_ANDROID_OS
int err = setGids(env, javaGids);
if (err < 0) {
PLOG(FATAL) << "cannot setgroups()";
}
err = setRlimits(env, javaRlimits);
if (err < 0) {
PLOG(FATAL) << "cannot setrlimit()";
}
err = setgid(gid);
if (err < 0) {
PLOG(FATAL) << "cannot setgid(" << gid << ")";
}
err = setuid(uid);
if (err < 0) {
PLOG(FATAL) << "cannot setuid(" << uid << ")";
}
err = setCapabilities(permittedCapabilities, effectiveCapabilities);
if (err != 0) {
PLOG(FATAL) << "cannot set capabilities ("
<< permittedCapabilities << "," << effectiveCapabilities << ")";
}
// Our system thread ID, etc, has changed so reset Thread state.
self->InitAfterFork();
// configure additional debug options
// enableDebugFeatures(debugFlags); // TODO: debugger
unsetSigchldHandler();
runtime->DidForkFromZygote();
} else if (pid > 0) {
// the parent process
}
return pid;
}
jint Zygote_nativeForkAndSpecialize(JNIEnv* env, jclass, jint uid, jint gid, jintArray gids,
jint debugFlags, jobjectArray rlimits) {
return forkAndSpecializeCommon(env, uid, gid, gids, debugFlags, rlimits, 0, 0);
}
jint Zygote_nativeForkSystemServer(JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids,
jint debugFlags, jobjectArray rlimits,
jlong permittedCapabilities, jlong effectiveCapabilities) {
pid_t pid = forkAndSpecializeCommon(env, uid, gid, gids,
debugFlags, rlimits,
permittedCapabilities, effectiveCapabilities);
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[[I)I"),
NATIVE_METHOD(Zygote, nativeForkSystemServer, "(II[II[[IJJ)I"),
};
} // namespace
void register_dalvik_system_Zygote(JNIEnv* env) {
jniRegisterNativeMethods(env, "dalvik/system/Zygote", gMethods, NELEM(gMethods));
}
} // namespace art