com_android_internal_os_Zygote.cpp revision a0d2e6f4b7c9f3375d89b11532cb8e6e09b5c13b
1/* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#define LOG_TAG "Zygote" 18 19// sys/mount.h has to come before linux/fs.h due to redefinition of MS_RDONLY, MS_BIND, etc 20#include <sys/mount.h> 21#include <linux/fs.h> 22 23#include <list> 24#include <sstream> 25#include <string> 26 27#include <fcntl.h> 28#include <grp.h> 29#include <inttypes.h> 30#include <mntent.h> 31#include <paths.h> 32#include <signal.h> 33#include <stdlib.h> 34#include <sys/capability.h> 35#include <sys/cdefs.h> 36#include <sys/personality.h> 37#include <sys/prctl.h> 38#include <sys/resource.h> 39#include <sys/stat.h> 40#include <sys/types.h> 41#include <sys/utsname.h> 42#include <sys/wait.h> 43#include <unistd.h> 44 45#include <cutils/fs.h> 46#include <cutils/multiuser.h> 47#include <cutils/sched_policy.h> 48#include <private/android_filesystem_config.h> 49#include <utils/String8.h> 50#include <selinux/android.h> 51#include <processgroup/processgroup.h> 52 53#include "core_jni_helpers.h" 54#include "JNIHelp.h" 55#include "ScopedLocalRef.h" 56#include "ScopedPrimitiveArray.h" 57#include "ScopedUtfChars.h" 58#include "fd_utils-inl.h" 59 60#include "nativebridge/native_bridge.h" 61 62namespace { 63 64using android::String8; 65 66static pid_t gSystemServerPid = 0; 67 68static const char kZygoteClassName[] = "com/android/internal/os/Zygote"; 69static jclass gZygoteClass; 70static jmethodID gCallPostForkChildHooks; 71 72// Must match values in com.android.internal.os.Zygote. 73enum MountExternalKind { 74 MOUNT_EXTERNAL_NONE = 0, 75 MOUNT_EXTERNAL_DEFAULT = 1, 76 MOUNT_EXTERNAL_READ = 2, 77 MOUNT_EXTERNAL_WRITE = 3, 78}; 79 80static void RuntimeAbort(JNIEnv* env, int line, const char* msg) { 81 std::ostringstream oss; 82 oss << __FILE__ << ":" << line << ": " << msg; 83 env->FatalError(oss.str().c_str()); 84} 85 86// This signal handler is for zygote mode, since the zygote must reap its children 87static void SigChldHandler(int /*signal_number*/) { 88 pid_t pid; 89 int status; 90 91 // It's necessary to save and restore the errno during this function. 92 // Since errno is stored per thread, changing it here modifies the errno 93 // on the thread on which this signal handler executes. If a signal occurs 94 // between a call and an errno check, it's possible to get the errno set 95 // here. 96 // See b/23572286 for extra information. 97 int saved_errno = errno; 98 99 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) { 100 // Log process-death status that we care about. In general it is 101 // not safe to call LOG(...) from a signal handler because of 102 // possible reentrancy. However, we know a priori that the 103 // current implementation of LOG() is safe to call from a SIGCHLD 104 // handler in the zygote process. If the LOG() implementation 105 // changes its locking strategy or its use of syscalls within the 106 // lazy-init critical section, its use here may become unsafe. 107 if (WIFEXITED(status)) { 108 if (WEXITSTATUS(status)) { 109 ALOGI("Process %d exited cleanly (%d)", pid, WEXITSTATUS(status)); 110 } 111 } else if (WIFSIGNALED(status)) { 112 if (WTERMSIG(status) != SIGKILL) { 113 ALOGI("Process %d exited due to signal (%d)", pid, WTERMSIG(status)); 114 } 115 if (WCOREDUMP(status)) { 116 ALOGI("Process %d dumped core.", pid); 117 } 118 } 119 120 // If the just-crashed process is the system_server, bring down zygote 121 // so that it is restarted by init and system server will be restarted 122 // from there. 123 if (pid == gSystemServerPid) { 124 ALOGE("Exit zygote because system server (%d) has terminated", pid); 125 kill(getpid(), SIGKILL); 126 } 127 } 128 129 // Note that we shouldn't consider ECHILD an error because 130 // the secondary zygote might have no children left to wait for. 131 if (pid < 0 && errno != ECHILD) { 132 ALOGW("Zygote SIGCHLD error in waitpid: %s", strerror(errno)); 133 } 134 135 errno = saved_errno; 136} 137 138// Configures the SIGCHLD handler for the zygote process. This is configured 139// very late, because earlier in the runtime we may fork() and exec() 140// other processes, and we want to waitpid() for those rather than 141// have them be harvested immediately. 142// 143// This ends up being called repeatedly before each fork(), but there's 144// no real harm in that. 145static void SetSigChldHandler() { 146 struct sigaction sa; 147 memset(&sa, 0, sizeof(sa)); 148 sa.sa_handler = SigChldHandler; 149 150 int err = sigaction(SIGCHLD, &sa, NULL); 151 if (err < 0) { 152 ALOGW("Error setting SIGCHLD handler: %s", strerror(errno)); 153 } 154} 155 156// Sets the SIGCHLD handler back to default behavior in zygote children. 157static void UnsetSigChldHandler() { 158 struct sigaction sa; 159 memset(&sa, 0, sizeof(sa)); 160 sa.sa_handler = SIG_DFL; 161 162 int err = sigaction(SIGCHLD, &sa, NULL); 163 if (err < 0) { 164 ALOGW("Error unsetting SIGCHLD handler: %s", strerror(errno)); 165 } 166} 167 168// Calls POSIX setgroups() using the int[] object as an argument. 169// A NULL argument is tolerated. 170static void SetGids(JNIEnv* env, jintArray javaGids) { 171 if (javaGids == NULL) { 172 return; 173 } 174 175 ScopedIntArrayRO gids(env, javaGids); 176 if (gids.get() == NULL) { 177 RuntimeAbort(env, __LINE__, "Getting gids int array failed"); 178 } 179 int rc = setgroups(gids.size(), reinterpret_cast<const gid_t*>(&gids[0])); 180 if (rc == -1) { 181 std::ostringstream oss; 182 oss << "setgroups failed: " << strerror(errno) << ", gids.size=" << gids.size(); 183 RuntimeAbort(env, __LINE__, oss.str().c_str()); 184 } 185} 186 187// Sets the resource limits via setrlimit(2) for the values in the 188// two-dimensional array of integers that's passed in. The second dimension 189// contains a tuple of length 3: (resource, rlim_cur, rlim_max). NULL is 190// treated as an empty array. 191static void SetRLimits(JNIEnv* env, jobjectArray javaRlimits) { 192 if (javaRlimits == NULL) { 193 return; 194 } 195 196 rlimit rlim; 197 memset(&rlim, 0, sizeof(rlim)); 198 199 for (int i = 0; i < env->GetArrayLength(javaRlimits); ++i) { 200 ScopedLocalRef<jobject> javaRlimitObject(env, env->GetObjectArrayElement(javaRlimits, i)); 201 ScopedIntArrayRO javaRlimit(env, reinterpret_cast<jintArray>(javaRlimitObject.get())); 202 if (javaRlimit.size() != 3) { 203 RuntimeAbort(env, __LINE__, "rlimits array must have a second dimension of size 3"); 204 } 205 206 rlim.rlim_cur = javaRlimit[1]; 207 rlim.rlim_max = javaRlimit[2]; 208 209 int rc = setrlimit(javaRlimit[0], &rlim); 210 if (rc == -1) { 211 ALOGE("setrlimit(%d, {%ld, %ld}) failed", javaRlimit[0], rlim.rlim_cur, 212 rlim.rlim_max); 213 RuntimeAbort(env, __LINE__, "setrlimit failed"); 214 } 215 } 216} 217 218// The debug malloc library needs to know whether it's the zygote or a child. 219extern "C" int gMallocLeakZygoteChild; 220 221static void EnableKeepCapabilities(JNIEnv* env) { 222 int rc = prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0); 223 if (rc == -1) { 224 RuntimeAbort(env, __LINE__, "prctl(PR_SET_KEEPCAPS) failed"); 225 } 226} 227 228static void DropCapabilitiesBoundingSet(JNIEnv* env) { 229 for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) { 230 int rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); 231 if (rc == -1) { 232 if (errno == EINVAL) { 233 ALOGE("prctl(PR_CAPBSET_DROP) failed with EINVAL. Please verify " 234 "your kernel is compiled with file capabilities support"); 235 } else { 236 RuntimeAbort(env, __LINE__, "prctl(PR_CAPBSET_DROP) failed"); 237 } 238 } 239 } 240} 241 242static void SetCapabilities(JNIEnv* env, int64_t permitted, int64_t effective) { 243 __user_cap_header_struct capheader; 244 memset(&capheader, 0, sizeof(capheader)); 245 capheader.version = _LINUX_CAPABILITY_VERSION_3; 246 capheader.pid = 0; 247 248 __user_cap_data_struct capdata[2]; 249 memset(&capdata, 0, sizeof(capdata)); 250 capdata[0].effective = effective; 251 capdata[1].effective = effective >> 32; 252 capdata[0].permitted = permitted; 253 capdata[1].permitted = permitted >> 32; 254 255 if (capset(&capheader, &capdata[0]) == -1) { 256 ALOGE("capset(%" PRId64 ", %" PRId64 ") failed", permitted, effective); 257 RuntimeAbort(env, __LINE__, "capset failed"); 258 } 259} 260 261static void SetSchedulerPolicy(JNIEnv* env) { 262 errno = -set_sched_policy(0, SP_DEFAULT); 263 if (errno != 0) { 264 ALOGE("set_sched_policy(0, SP_DEFAULT) failed"); 265 RuntimeAbort(env, __LINE__, "set_sched_policy(0, SP_DEFAULT) failed"); 266 } 267} 268 269static int UnmountTree(const char* path) { 270 size_t path_len = strlen(path); 271 272 FILE* fp = setmntent("/proc/mounts", "r"); 273 if (fp == NULL) { 274 ALOGE("Error opening /proc/mounts: %s", strerror(errno)); 275 return -errno; 276 } 277 278 // Some volumes can be stacked on each other, so force unmount in 279 // reverse order to give us the best chance of success. 280 std::list<std::string> toUnmount; 281 mntent* mentry; 282 while ((mentry = getmntent(fp)) != NULL) { 283 if (strncmp(mentry->mnt_dir, path, path_len) == 0) { 284 toUnmount.push_front(std::string(mentry->mnt_dir)); 285 } 286 } 287 endmntent(fp); 288 289 for (auto path : toUnmount) { 290 if (umount2(path.c_str(), MNT_DETACH)) { 291 ALOGW("Failed to unmount %s: %s", path.c_str(), strerror(errno)); 292 } 293 } 294 return 0; 295} 296 297// Create a private mount namespace and bind mount appropriate emulated 298// storage for the given user. 299static bool MountEmulatedStorage(uid_t uid, jint mount_mode, 300 bool force_mount_namespace) { 301 // See storage config details at http://source.android.com/tech/storage/ 302 303 String8 storageSource; 304 if (mount_mode == MOUNT_EXTERNAL_DEFAULT) { 305 storageSource = "/mnt/runtime/default"; 306 } else if (mount_mode == MOUNT_EXTERNAL_READ) { 307 storageSource = "/mnt/runtime/read"; 308 } else if (mount_mode == MOUNT_EXTERNAL_WRITE) { 309 storageSource = "/mnt/runtime/write"; 310 } else if (!force_mount_namespace) { 311 // Sane default of no storage visible 312 return true; 313 } 314 315 // Create a second private mount namespace for our process 316 if (unshare(CLONE_NEWNS) == -1) { 317 ALOGW("Failed to unshare(): %s", strerror(errno)); 318 return false; 319 } 320 321 if (TEMP_FAILURE_RETRY(mount(storageSource.string(), "/storage", 322 NULL, MS_BIND | MS_REC | MS_SLAVE, NULL)) == -1) { 323 ALOGW("Failed to mount %s to /storage: %s", storageSource.string(), strerror(errno)); 324 return false; 325 } 326 327 // Mount user-specific symlink helper into place 328 userid_t user_id = multiuser_get_user_id(uid); 329 const String8 userSource(String8::format("/mnt/user/%d", user_id)); 330 if (fs_prepare_dir(userSource.string(), 0751, 0, 0) == -1) { 331 return false; 332 } 333 if (TEMP_FAILURE_RETRY(mount(userSource.string(), "/storage/self", 334 NULL, MS_BIND, NULL)) == -1) { 335 ALOGW("Failed to mount %s to /storage/self: %s", userSource.string(), strerror(errno)); 336 return false; 337 } 338 339 return true; 340} 341 342static bool NeedsNoRandomizeWorkaround() { 343#if !defined(__arm__) 344 return false; 345#else 346 int major; 347 int minor; 348 struct utsname uts; 349 if (uname(&uts) == -1) { 350 return false; 351 } 352 353 if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) { 354 return false; 355 } 356 357 // Kernels before 3.4.* need the workaround. 358 return (major < 3) || ((major == 3) && (minor < 4)); 359#endif 360} 361 362// Utility to close down the Zygote socket file descriptors while 363// the child is still running as root with Zygote's privileges. Each 364// descriptor (if any) is closed via dup2(), replacing it with a valid 365// (open) descriptor to /dev/null. 366 367static void DetachDescriptors(JNIEnv* env, jintArray fdsToClose) { 368 if (!fdsToClose) { 369 return; 370 } 371 jsize count = env->GetArrayLength(fdsToClose); 372 ScopedIntArrayRO ar(env, fdsToClose); 373 if (ar.get() == NULL) { 374 RuntimeAbort(env, __LINE__, "Bad fd array"); 375 } 376 jsize i; 377 int devnull; 378 for (i = 0; i < count; i++) { 379 devnull = open("/dev/null", O_RDWR); 380 if (devnull < 0) { 381 ALOGE("Failed to open /dev/null: %s", strerror(errno)); 382 RuntimeAbort(env, __LINE__, "Failed to open /dev/null"); 383 continue; 384 } 385 ALOGV("Switching descriptor %d to /dev/null: %s", ar[i], strerror(errno)); 386 if (dup2(devnull, ar[i]) < 0) { 387 ALOGE("Failed dup2() on descriptor %d: %s", ar[i], strerror(errno)); 388 RuntimeAbort(env, __LINE__, "Failed dup2()"); 389 } 390 close(devnull); 391 } 392} 393 394void SetThreadName(const char* thread_name) { 395 bool hasAt = false; 396 bool hasDot = false; 397 const char* s = thread_name; 398 while (*s) { 399 if (*s == '.') { 400 hasDot = true; 401 } else if (*s == '@') { 402 hasAt = true; 403 } 404 s++; 405 } 406 const int len = s - thread_name; 407 if (len < 15 || hasAt || !hasDot) { 408 s = thread_name; 409 } else { 410 s = thread_name + len - 15; 411 } 412 // pthread_setname_np fails rather than truncating long strings. 413 char buf[16]; // MAX_TASK_COMM_LEN=16 is hard-coded into bionic 414 strlcpy(buf, s, sizeof(buf)-1); 415 errno = pthread_setname_np(pthread_self(), buf); 416 if (errno != 0) { 417 ALOGW("Unable to set the name of current thread to '%s': %s", buf, strerror(errno)); 418 } 419} 420 421#ifdef ENABLE_SCHED_BOOST 422static void SetForkLoad(bool boost) { 423 // set scheduler knob to boost forked processes 424 pid_t currentPid = getpid(); 425 // fits at most "/proc/XXXXXXX/sched_init_task_load\0" 426 char schedPath[35]; 427 snprintf(schedPath, sizeof(schedPath), "/proc/%u/sched_init_task_load", currentPid); 428 int schedBoostFile = open(schedPath, O_WRONLY); 429 if (schedBoostFile < 0) { 430 ALOGW("Unable to set zygote scheduler boost"); 431 return; 432 } 433 if (boost) { 434 write(schedBoostFile, "100\0", 4); 435 } else { 436 write(schedBoostFile, "0\0", 2); 437 } 438 close(schedBoostFile); 439} 440#endif 441 442// The list of open zygote file descriptors. 443static FileDescriptorTable* gOpenFdTable = NULL; 444 445// Utility routine to fork zygote and specialize the child process. 446static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids, 447 jint debug_flags, jobjectArray javaRlimits, 448 jlong permittedCapabilities, jlong effectiveCapabilities, 449 jint mount_external, 450 jstring java_se_info, jstring java_se_name, 451 bool is_system_server, jintArray fdsToClose, 452 jstring instructionSet, jstring dataDir) { 453 SetSigChldHandler(); 454 455#ifdef ENABLE_SCHED_BOOST 456 SetForkLoad(true); 457#endif 458 459 // Close any logging related FDs before we start evaluating the list of 460 // file descriptors. 461 __android_log_close(); 462 463 // If this is the first fork for this zygote, create the open FD table. 464 // If it isn't, we just need to check whether the list of open files has 465 // changed (and it shouldn't in the normal case). 466 if (gOpenFdTable == NULL) { 467 gOpenFdTable = FileDescriptorTable::Create(); 468 if (gOpenFdTable == NULL) { 469 RuntimeAbort(env, __LINE__, "Unable to construct file descriptor table."); 470 } 471 } else if (!gOpenFdTable->Restat()) { 472 RuntimeAbort(env, __LINE__, "Unable to restat file descriptor table."); 473 } 474 475 pid_t pid = fork(); 476 477 if (pid == 0) { 478 // The child process. 479 gMallocLeakZygoteChild = 1; 480 481 // Clean up any descriptors which must be closed immediately 482 DetachDescriptors(env, fdsToClose); 483 484 // Re-open all remaining open file descriptors so that they aren't shared 485 // with the zygote across a fork. 486 if (!gOpenFdTable->ReopenOrDetach()) { 487 RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors."); 488 } 489 490 // Keep capabilities across UID change, unless we're staying root. 491 if (uid != 0) { 492 EnableKeepCapabilities(env); 493 } 494 495 DropCapabilitiesBoundingSet(env); 496 497 bool use_native_bridge = !is_system_server && (instructionSet != NULL) 498 && android::NativeBridgeAvailable(); 499 if (use_native_bridge) { 500 ScopedUtfChars isa_string(env, instructionSet); 501 use_native_bridge = android::NeedsNativeBridge(isa_string.c_str()); 502 } 503 if (use_native_bridge && dataDir == NULL) { 504 // dataDir should never be null if we need to use a native bridge. 505 // In general, dataDir will never be null for normal applications. It can only happen in 506 // special cases (for isolated processes which are not associated with any app). These are 507 // launched by the framework and should not be emulated anyway. 508 use_native_bridge = false; 509 ALOGW("Native bridge will not be used because dataDir == NULL."); 510 } 511 512 if (!MountEmulatedStorage(uid, mount_external, use_native_bridge)) { 513 ALOGW("Failed to mount emulated storage: %s", strerror(errno)); 514 if (errno == ENOTCONN || errno == EROFS) { 515 // When device is actively encrypting, we get ENOTCONN here 516 // since FUSE was mounted before the framework restarted. 517 // When encrypted device is booting, we get EROFS since 518 // FUSE hasn't been created yet by init. 519 // In either case, continue without external storage. 520 } else { 521 RuntimeAbort(env, __LINE__, "Cannot continue without emulated storage"); 522 } 523 } 524 525 if (!is_system_server) { 526 int rc = createProcessGroup(uid, getpid()); 527 if (rc != 0) { 528 if (rc == -EROFS) { 529 ALOGW("createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?"); 530 } else { 531 ALOGE("createProcessGroup(%d, %d) failed: %s", uid, pid, strerror(-rc)); 532 } 533 } 534 } 535 536 SetGids(env, javaGids); 537 538 SetRLimits(env, javaRlimits); 539 540 if (use_native_bridge) { 541 ScopedUtfChars isa_string(env, instructionSet); 542 ScopedUtfChars data_dir(env, dataDir); 543 android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str()); 544 } 545 546 int rc = setresgid(gid, gid, gid); 547 if (rc == -1) { 548 ALOGE("setresgid(%d) failed: %s", gid, strerror(errno)); 549 RuntimeAbort(env, __LINE__, "setresgid failed"); 550 } 551 552 rc = setresuid(uid, uid, uid); 553 if (rc == -1) { 554 ALOGE("setresuid(%d) failed: %s", uid, strerror(errno)); 555 RuntimeAbort(env, __LINE__, "setresuid failed"); 556 } 557 558 if (NeedsNoRandomizeWorkaround()) { 559 // Work around ARM kernel ASLR lossage (http://b/5817320). 560 int old_personality = personality(0xffffffff); 561 int new_personality = personality(old_personality | ADDR_NO_RANDOMIZE); 562 if (new_personality == -1) { 563 ALOGW("personality(%d) failed: %s", new_personality, strerror(errno)); 564 } 565 } 566 567 SetCapabilities(env, permittedCapabilities, effectiveCapabilities); 568 569 SetSchedulerPolicy(env); 570 571 const char* se_info_c_str = NULL; 572 ScopedUtfChars* se_info = NULL; 573 if (java_se_info != NULL) { 574 se_info = new ScopedUtfChars(env, java_se_info); 575 se_info_c_str = se_info->c_str(); 576 if (se_info_c_str == NULL) { 577 RuntimeAbort(env, __LINE__, "se_info_c_str == NULL"); 578 } 579 } 580 const char* se_name_c_str = NULL; 581 ScopedUtfChars* se_name = NULL; 582 if (java_se_name != NULL) { 583 se_name = new ScopedUtfChars(env, java_se_name); 584 se_name_c_str = se_name->c_str(); 585 if (se_name_c_str == NULL) { 586 RuntimeAbort(env, __LINE__, "se_name_c_str == NULL"); 587 } 588 } 589 rc = selinux_android_setcontext(uid, is_system_server, se_info_c_str, se_name_c_str); 590 if (rc == -1) { 591 ALOGE("selinux_android_setcontext(%d, %d, \"%s\", \"%s\") failed", uid, 592 is_system_server, se_info_c_str, se_name_c_str); 593 RuntimeAbort(env, __LINE__, "selinux_android_setcontext failed"); 594 } 595 596 // Make it easier to debug audit logs by setting the main thread's name to the 597 // nice name rather than "app_process". 598 if (se_info_c_str == NULL && is_system_server) { 599 se_name_c_str = "system_server"; 600 } 601 if (se_info_c_str != NULL) { 602 SetThreadName(se_name_c_str); 603 } 604 605 delete se_info; 606 delete se_name; 607 608 UnsetSigChldHandler(); 609 610 env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags, 611 is_system_server, instructionSet); 612 if (env->ExceptionCheck()) { 613 RuntimeAbort(env, __LINE__, "Error calling post fork hooks."); 614 } 615 } else if (pid > 0) { 616 // the parent process 617 618#ifdef ENABLE_SCHED_BOOST 619 // unset scheduler knob 620 SetForkLoad(false); 621#endif 622 623 } 624 return pid; 625} 626} // anonymous namespace 627 628namespace android { 629 630static jint com_android_internal_os_Zygote_nativeForkAndSpecialize( 631 JNIEnv* env, jclass, jint uid, jint gid, jintArray gids, 632 jint debug_flags, jobjectArray rlimits, 633 jint mount_external, jstring se_info, jstring se_name, 634 jintArray fdsToClose, jstring instructionSet, jstring appDataDir) { 635 jlong capabilities = 0; 636 637 // Grant CAP_WAKE_ALARM to the Bluetooth process. 638 // Additionally, allow bluetooth to open packet sockets so it can start the DHCP client. 639 // TODO: consider making such functionality an RPC to netd. 640 if (multiuser_get_app_id(uid) == AID_BLUETOOTH) { 641 capabilities |= (1LL << CAP_WAKE_ALARM); 642 capabilities |= (1LL << CAP_NET_RAW); 643 capabilities |= (1LL << CAP_NET_BIND_SERVICE); 644 } 645 646 // Grant CAP_BLOCK_SUSPEND to processes that belong to GID "wakelock" 647 bool gid_wakelock_found = false; 648 if (gid == AID_WAKELOCK) { 649 gid_wakelock_found = true; 650 } else if (gids != NULL) { 651 jsize gids_num = env->GetArrayLength(gids); 652 ScopedIntArrayRO ar(env, gids); 653 if (ar.get() == NULL) { 654 RuntimeAbort(env, __LINE__, "Bad gids array"); 655 } 656 for (int i = 0; i < gids_num; i++) { 657 if (ar[i] == AID_WAKELOCK) { 658 gid_wakelock_found = true; 659 break; 660 } 661 } 662 } 663 if (gid_wakelock_found) { 664 capabilities |= (1LL << CAP_BLOCK_SUSPEND); 665 } 666 667 return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags, 668 rlimits, capabilities, capabilities, mount_external, se_info, 669 se_name, false, fdsToClose, instructionSet, appDataDir); 670} 671 672static jint com_android_internal_os_Zygote_nativeForkSystemServer( 673 JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids, 674 jint debug_flags, jobjectArray rlimits, jlong permittedCapabilities, 675 jlong effectiveCapabilities) { 676 pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids, 677 debug_flags, rlimits, 678 permittedCapabilities, effectiveCapabilities, 679 MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true, NULL, 680 NULL, NULL); 681 if (pid > 0) { 682 // The zygote process checks whether the child process has died or not. 683 ALOGI("System server process %d has been created", pid); 684 gSystemServerPid = pid; 685 // There is a slight window that the system server process has crashed 686 // but it went unnoticed because we haven't published its pid yet. So 687 // we recheck here just to make sure that all is well. 688 int status; 689 if (waitpid(pid, &status, WNOHANG) == pid) { 690 ALOGE("System server process %d has died. Restarting Zygote!", pid); 691 RuntimeAbort(env, __LINE__, "System server process has died. Restarting Zygote!"); 692 } 693 } 694 return pid; 695} 696 697static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) { 698 // Zygote process unmount root storage space initially before every child processes are forked. 699 // Every forked child processes (include SystemServer) only mount their own root storage space 700 // and no need unmount storage operation in MountEmulatedStorage method. 701 // Zygote process does not utilize root storage spaces and unshares its mount namespace below. 702 703 // See storage config details at http://source.android.com/tech/storage/ 704 // Create private mount namespace shared by all children 705 if (unshare(CLONE_NEWNS) == -1) { 706 RuntimeAbort(env, __LINE__, "Failed to unshare()"); 707 return; 708 } 709 710 // Mark rootfs as being a slave so that changes from default 711 // namespace only flow into our children. 712 if (mount("rootfs", "/", nullptr, (MS_SLAVE | MS_REC), nullptr) == -1) { 713 RuntimeAbort(env, __LINE__, "Failed to mount() rootfs as MS_SLAVE"); 714 return; 715 } 716 717 // Create a staging tmpfs that is shared by our children; they will 718 // bind mount storage into their respective private namespaces, which 719 // are isolated from each other. 720 const char* target_base = getenv("EMULATED_STORAGE_TARGET"); 721 if (target_base != nullptr) { 722#define STRINGIFY_UID(x) __STRING(x) 723 if (mount("tmpfs", target_base, "tmpfs", MS_NOSUID | MS_NODEV, 724 "uid=0,gid=" STRINGIFY_UID(AID_SDCARD_R) ",mode=0751") == -1) { 725 ALOGE("Failed to mount tmpfs to %s", target_base); 726 RuntimeAbort(env, __LINE__, "Failed to mount tmpfs"); 727 return; 728 } 729#undef STRINGIFY_UID 730 } 731 732 UnmountTree("/storage"); 733} 734 735static const JNINativeMethod gMethods[] = { 736 { "nativeForkAndSpecialize", 737 "(II[II[[IILjava/lang/String;Ljava/lang/String;[ILjava/lang/String;Ljava/lang/String;)I", 738 (void *) com_android_internal_os_Zygote_nativeForkAndSpecialize }, 739 { "nativeForkSystemServer", "(II[II[[IJJ)I", 740 (void *) com_android_internal_os_Zygote_nativeForkSystemServer }, 741 { "nativeUnmountStorageOnInit", "()V", 742 (void *) com_android_internal_os_Zygote_nativeUnmountStorageOnInit } 743}; 744 745int register_com_android_internal_os_Zygote(JNIEnv* env) { 746 gZygoteClass = MakeGlobalRefOrDie(env, FindClassOrDie(env, kZygoteClassName)); 747 gCallPostForkChildHooks = GetStaticMethodIDOrDie(env, gZygoteClass, "callPostForkChildHooks", 748 "(IZLjava/lang/String;)V"); 749 750 return RegisterMethodsOrDie(env, "com/android/internal/os/Zygote", gMethods, NELEM(gMethods)); 751} 752} // namespace android 753 754