com_android_internal_os_Zygote.cpp revision a07e5312ccc21dffbfeecee17e5c859e0cb952d1
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/time.h> 41#include <sys/types.h> 42#include <sys/utsname.h> 43#include <sys/wait.h> 44#include <unistd.h> 45 46#include "android-base/logging.h" 47#include <cutils/fs.h> 48#include <cutils/multiuser.h> 49#include <cutils/sched_policy.h> 50#include <private/android_filesystem_config.h> 51#include <utils/String8.h> 52#include <selinux/android.h> 53#include <processgroup/processgroup.h> 54 55#include "core_jni_helpers.h" 56#include "JNIHelp.h" 57#include "ScopedLocalRef.h" 58#include "ScopedPrimitiveArray.h" 59#include "ScopedUtfChars.h" 60#include "fd_utils.h" 61 62#include "nativebridge/native_bridge.h" 63 64namespace { 65 66using android::String8; 67 68static pid_t gSystemServerPid = 0; 69 70static const char kZygoteClassName[] = "com/android/internal/os/Zygote"; 71static jclass gZygoteClass; 72static jmethodID gCallPostForkChildHooks; 73 74// Must match values in com.android.internal.os.Zygote. 75enum MountExternalKind { 76 MOUNT_EXTERNAL_NONE = 0, 77 MOUNT_EXTERNAL_DEFAULT = 1, 78 MOUNT_EXTERNAL_READ = 2, 79 MOUNT_EXTERNAL_WRITE = 3, 80}; 81 82static void RuntimeAbort(JNIEnv* env, int line, const char* msg) { 83 std::ostringstream oss; 84 oss << __FILE__ << ":" << line << ": " << msg; 85 env->FatalError(oss.str().c_str()); 86} 87 88// This signal handler is for zygote mode, since the zygote must reap its children 89static void SigChldHandler(int /*signal_number*/) { 90 pid_t pid; 91 int status; 92 93 // It's necessary to save and restore the errno during this function. 94 // Since errno is stored per thread, changing it here modifies the errno 95 // on the thread on which this signal handler executes. If a signal occurs 96 // between a call and an errno check, it's possible to get the errno set 97 // here. 98 // See b/23572286 for extra information. 99 int saved_errno = errno; 100 101 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) { 102 // Log process-death status that we care about. In general it is 103 // not safe to call LOG(...) from a signal handler because of 104 // possible reentrancy. However, we know a priori that the 105 // current implementation of LOG() is safe to call from a SIGCHLD 106 // handler in the zygote process. If the LOG() implementation 107 // changes its locking strategy or its use of syscalls within the 108 // lazy-init critical section, its use here may become unsafe. 109 if (WIFEXITED(status)) { 110 if (WEXITSTATUS(status)) { 111 ALOGI("Process %d exited cleanly (%d)", pid, WEXITSTATUS(status)); 112 } 113 } else if (WIFSIGNALED(status)) { 114 if (WTERMSIG(status) != SIGKILL) { 115 ALOGI("Process %d exited due to signal (%d)", pid, WTERMSIG(status)); 116 } 117 if (WCOREDUMP(status)) { 118 ALOGI("Process %d dumped core.", pid); 119 } 120 } 121 122 // If the just-crashed process is the system_server, bring down zygote 123 // so that it is restarted by init and system server will be restarted 124 // from there. 125 if (pid == gSystemServerPid) { 126 ALOGE("Exit zygote because system server (%d) has terminated", pid); 127 kill(getpid(), SIGKILL); 128 } 129 } 130 131 // Note that we shouldn't consider ECHILD an error because 132 // the secondary zygote might have no children left to wait for. 133 if (pid < 0 && errno != ECHILD) { 134 ALOGW("Zygote SIGCHLD error in waitpid: %s", strerror(errno)); 135 } 136 137 errno = saved_errno; 138} 139 140// Configures the SIGCHLD handler for the zygote process. This is configured 141// very late, because earlier in the runtime we may fork() and exec() 142// other processes, and we want to waitpid() for those rather than 143// have them be harvested immediately. 144// 145// This ends up being called repeatedly before each fork(), but there's 146// no real harm in that. 147static void SetSigChldHandler() { 148 struct sigaction sa; 149 memset(&sa, 0, sizeof(sa)); 150 sa.sa_handler = SigChldHandler; 151 152 int err = sigaction(SIGCHLD, &sa, NULL); 153 if (err < 0) { 154 ALOGW("Error setting SIGCHLD handler: %s", strerror(errno)); 155 } 156} 157 158// Resets nice priority for zygote process. Zygote priority can be set 159// to high value during boot phase to speed it up. We want to ensure 160// zygote is running at normal priority before childs are forked from it. 161// 162// This ends up being called repeatedly before each fork(), but there's 163// no real harm in that. 164static void ResetNicePriority(JNIEnv* env) { 165 errno = 0; 166 int prio = getpriority(PRIO_PROCESS, 0); 167 if (prio == -1 && errno != 0) { 168 ALOGW("getpriority failed: %s\n", strerror(errno)); 169 } 170 if (prio != 0 && setpriority(PRIO_PROCESS, 0, 0) != 0) { 171 ALOGE("setpriority(%d, 0, 0) failed: %s", PRIO_PROCESS, strerror(errno)); 172 RuntimeAbort(env, __LINE__, "setpriority failed"); 173 } 174} 175 176// Sets the SIGCHLD handler back to default behavior in zygote children. 177static void UnsetSigChldHandler() { 178 struct sigaction sa; 179 memset(&sa, 0, sizeof(sa)); 180 sa.sa_handler = SIG_DFL; 181 182 int err = sigaction(SIGCHLD, &sa, NULL); 183 if (err < 0) { 184 ALOGW("Error unsetting SIGCHLD handler: %s", strerror(errno)); 185 } 186} 187 188// Calls POSIX setgroups() using the int[] object as an argument. 189// A NULL argument is tolerated. 190static void SetGids(JNIEnv* env, jintArray javaGids) { 191 if (javaGids == NULL) { 192 return; 193 } 194 195 ScopedIntArrayRO gids(env, javaGids); 196 if (gids.get() == NULL) { 197 RuntimeAbort(env, __LINE__, "Getting gids int array failed"); 198 } 199 int rc = setgroups(gids.size(), reinterpret_cast<const gid_t*>(&gids[0])); 200 if (rc == -1) { 201 std::ostringstream oss; 202 oss << "setgroups failed: " << strerror(errno) << ", gids.size=" << gids.size(); 203 RuntimeAbort(env, __LINE__, oss.str().c_str()); 204 } 205} 206 207// Sets the resource limits via setrlimit(2) for the values in the 208// two-dimensional array of integers that's passed in. The second dimension 209// contains a tuple of length 3: (resource, rlim_cur, rlim_max). NULL is 210// treated as an empty array. 211static void SetRLimits(JNIEnv* env, jobjectArray javaRlimits) { 212 if (javaRlimits == NULL) { 213 return; 214 } 215 216 rlimit rlim; 217 memset(&rlim, 0, sizeof(rlim)); 218 219 for (int i = 0; i < env->GetArrayLength(javaRlimits); ++i) { 220 ScopedLocalRef<jobject> javaRlimitObject(env, env->GetObjectArrayElement(javaRlimits, i)); 221 ScopedIntArrayRO javaRlimit(env, reinterpret_cast<jintArray>(javaRlimitObject.get())); 222 if (javaRlimit.size() != 3) { 223 RuntimeAbort(env, __LINE__, "rlimits array must have a second dimension of size 3"); 224 } 225 226 rlim.rlim_cur = javaRlimit[1]; 227 rlim.rlim_max = javaRlimit[2]; 228 229 int rc = setrlimit(javaRlimit[0], &rlim); 230 if (rc == -1) { 231 ALOGE("setrlimit(%d, {%ld, %ld}) failed", javaRlimit[0], rlim.rlim_cur, 232 rlim.rlim_max); 233 RuntimeAbort(env, __LINE__, "setrlimit failed"); 234 } 235 } 236} 237 238// The debug malloc library needs to know whether it's the zygote or a child. 239extern "C" int gMallocLeakZygoteChild; 240 241static void EnableKeepCapabilities(JNIEnv* env) { 242 int rc = prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0); 243 if (rc == -1) { 244 RuntimeAbort(env, __LINE__, "prctl(PR_SET_KEEPCAPS) failed"); 245 } 246} 247 248static void DropCapabilitiesBoundingSet(JNIEnv* env) { 249 for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) { 250 // Keep CAP_SYS_PTRACE in our bounding set so crash_dump can gain it. 251 if (i == CAP_SYS_PTRACE) { 252 continue; 253 } 254 255 int rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); 256 if (rc == -1) { 257 if (errno == EINVAL) { 258 ALOGE("prctl(PR_CAPBSET_DROP) failed with EINVAL. Please verify " 259 "your kernel is compiled with file capabilities support"); 260 } else { 261 RuntimeAbort(env, __LINE__, "prctl(PR_CAPBSET_DROP) failed"); 262 } 263 } 264 } 265} 266 267static void SetCapabilities(JNIEnv* env, int64_t permitted, int64_t effective) { 268 __user_cap_header_struct capheader; 269 memset(&capheader, 0, sizeof(capheader)); 270 capheader.version = _LINUX_CAPABILITY_VERSION_3; 271 capheader.pid = 0; 272 273 __user_cap_data_struct capdata[2]; 274 memset(&capdata, 0, sizeof(capdata)); 275 capdata[0].effective = effective; 276 capdata[1].effective = effective >> 32; 277 capdata[0].permitted = permitted; 278 capdata[1].permitted = permitted >> 32; 279 280 if (capset(&capheader, &capdata[0]) == -1) { 281 ALOGE("capset(%" PRId64 ", %" PRId64 ") failed", permitted, effective); 282 RuntimeAbort(env, __LINE__, "capset failed"); 283 } 284} 285 286static void SetSchedulerPolicy(JNIEnv* env) { 287 errno = -set_sched_policy(0, SP_DEFAULT); 288 if (errno != 0) { 289 ALOGE("set_sched_policy(0, SP_DEFAULT) failed"); 290 RuntimeAbort(env, __LINE__, "set_sched_policy(0, SP_DEFAULT) failed"); 291 } 292} 293 294static int UnmountTree(const char* path) { 295 size_t path_len = strlen(path); 296 297 FILE* fp = setmntent("/proc/mounts", "r"); 298 if (fp == NULL) { 299 ALOGE("Error opening /proc/mounts: %s", strerror(errno)); 300 return -errno; 301 } 302 303 // Some volumes can be stacked on each other, so force unmount in 304 // reverse order to give us the best chance of success. 305 std::list<std::string> toUnmount; 306 mntent* mentry; 307 while ((mentry = getmntent(fp)) != NULL) { 308 if (strncmp(mentry->mnt_dir, path, path_len) == 0) { 309 toUnmount.push_front(std::string(mentry->mnt_dir)); 310 } 311 } 312 endmntent(fp); 313 314 for (auto path : toUnmount) { 315 if (umount2(path.c_str(), MNT_DETACH)) { 316 ALOGW("Failed to unmount %s: %s", path.c_str(), strerror(errno)); 317 } 318 } 319 return 0; 320} 321 322// Create a private mount namespace and bind mount appropriate emulated 323// storage for the given user. 324static bool MountEmulatedStorage(uid_t uid, jint mount_mode, 325 bool force_mount_namespace) { 326 // See storage config details at http://source.android.com/tech/storage/ 327 328 String8 storageSource; 329 if (mount_mode == MOUNT_EXTERNAL_DEFAULT) { 330 storageSource = "/mnt/runtime/default"; 331 } else if (mount_mode == MOUNT_EXTERNAL_READ) { 332 storageSource = "/mnt/runtime/read"; 333 } else if (mount_mode == MOUNT_EXTERNAL_WRITE) { 334 storageSource = "/mnt/runtime/write"; 335 } else if (!force_mount_namespace) { 336 // Sane default of no storage visible 337 return true; 338 } 339 340 // Create a second private mount namespace for our process 341 if (unshare(CLONE_NEWNS) == -1) { 342 ALOGW("Failed to unshare(): %s", strerror(errno)); 343 return false; 344 } 345 346 if (TEMP_FAILURE_RETRY(mount(storageSource.string(), "/storage", 347 NULL, MS_BIND | MS_REC | MS_SLAVE, NULL)) == -1) { 348 ALOGW("Failed to mount %s to /storage: %s", storageSource.string(), strerror(errno)); 349 return false; 350 } 351 352 // Mount user-specific symlink helper into place 353 userid_t user_id = multiuser_get_user_id(uid); 354 const String8 userSource(String8::format("/mnt/user/%d", user_id)); 355 if (fs_prepare_dir(userSource.string(), 0751, 0, 0) == -1) { 356 return false; 357 } 358 if (TEMP_FAILURE_RETRY(mount(userSource.string(), "/storage/self", 359 NULL, MS_BIND, NULL)) == -1) { 360 ALOGW("Failed to mount %s to /storage/self: %s", userSource.string(), strerror(errno)); 361 return false; 362 } 363 364 return true; 365} 366 367static bool NeedsNoRandomizeWorkaround() { 368#if !defined(__arm__) 369 return false; 370#else 371 int major; 372 int minor; 373 struct utsname uts; 374 if (uname(&uts) == -1) { 375 return false; 376 } 377 378 if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) { 379 return false; 380 } 381 382 // Kernels before 3.4.* need the workaround. 383 return (major < 3) || ((major == 3) && (minor < 4)); 384#endif 385} 386 387// Utility to close down the Zygote socket file descriptors while 388// the child is still running as root with Zygote's privileges. Each 389// descriptor (if any) is closed via dup2(), replacing it with a valid 390// (open) descriptor to /dev/null. 391 392static void DetachDescriptors(JNIEnv* env, jintArray fdsToClose) { 393 if (!fdsToClose) { 394 return; 395 } 396 jsize count = env->GetArrayLength(fdsToClose); 397 ScopedIntArrayRO ar(env, fdsToClose); 398 if (ar.get() == NULL) { 399 RuntimeAbort(env, __LINE__, "Bad fd array"); 400 } 401 jsize i; 402 int devnull; 403 for (i = 0; i < count; i++) { 404 devnull = open("/dev/null", O_RDWR); 405 if (devnull < 0) { 406 ALOGE("Failed to open /dev/null: %s", strerror(errno)); 407 RuntimeAbort(env, __LINE__, "Failed to open /dev/null"); 408 continue; 409 } 410 ALOGV("Switching descriptor %d to /dev/null: %s", ar[i], strerror(errno)); 411 if (dup2(devnull, ar[i]) < 0) { 412 ALOGE("Failed dup2() on descriptor %d: %s", ar[i], strerror(errno)); 413 RuntimeAbort(env, __LINE__, "Failed dup2()"); 414 } 415 close(devnull); 416 } 417} 418 419void SetThreadName(const char* thread_name) { 420 bool hasAt = false; 421 bool hasDot = false; 422 const char* s = thread_name; 423 while (*s) { 424 if (*s == '.') { 425 hasDot = true; 426 } else if (*s == '@') { 427 hasAt = true; 428 } 429 s++; 430 } 431 const int len = s - thread_name; 432 if (len < 15 || hasAt || !hasDot) { 433 s = thread_name; 434 } else { 435 s = thread_name + len - 15; 436 } 437 // pthread_setname_np fails rather than truncating long strings. 438 char buf[16]; // MAX_TASK_COMM_LEN=16 is hard-coded into bionic 439 strlcpy(buf, s, sizeof(buf)-1); 440 errno = pthread_setname_np(pthread_self(), buf); 441 if (errno != 0) { 442 ALOGW("Unable to set the name of current thread to '%s': %s", buf, strerror(errno)); 443 } 444} 445 446// The list of open zygote file descriptors. 447static FileDescriptorTable* gOpenFdTable = NULL; 448 449static void FillFileDescriptorVector(JNIEnv* env, 450 jintArray java_fds, 451 std::vector<int>* fds) { 452 CHECK(fds != nullptr); 453 if (java_fds != nullptr) { 454 ScopedIntArrayRO ar(env, java_fds); 455 if (ar.get() == nullptr) { 456 RuntimeAbort(env, __LINE__, "Bad fd array"); 457 } 458 fds->reserve(ar.size()); 459 for (size_t i = 0; i < ar.size(); ++i) { 460 fds->push_back(ar[i]); 461 } 462 } 463} 464 465// Utility routine to fork zygote and specialize the child process. 466static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids, 467 jint debug_flags, jobjectArray javaRlimits, 468 jlong permittedCapabilities, jlong effectiveCapabilities, 469 jint mount_external, 470 jstring java_se_info, jstring java_se_name, 471 bool is_system_server, jintArray fdsToClose, 472 jintArray fdsToIgnore, 473 jstring instructionSet, jstring dataDir) { 474 SetSigChldHandler(); 475 476 sigset_t sigchld; 477 sigemptyset(&sigchld); 478 sigaddset(&sigchld, SIGCHLD); 479 480 // Temporarily block SIGCHLD during forks. The SIGCHLD handler might 481 // log, which would result in the logging FDs we close being reopened. 482 // This would cause failures because the FDs are not whitelisted. 483 // 484 // Note that the zygote process is single threaded at this point. 485 if (sigprocmask(SIG_BLOCK, &sigchld, nullptr) == -1) { 486 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 487 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_BLOCK, { SIGCHLD }) failed."); 488 } 489 490 // Close any logging related FDs before we start evaluating the list of 491 // file descriptors. 492 __android_log_close(); 493 494 // If this is the first fork for this zygote, create the open FD table. 495 // If it isn't, we just need to check whether the list of open files has 496 // changed (and it shouldn't in the normal case). 497 std::vector<int> fds_to_ignore; 498 FillFileDescriptorVector(env, fdsToIgnore, &fds_to_ignore); 499 if (gOpenFdTable == NULL) { 500 gOpenFdTable = FileDescriptorTable::Create(fds_to_ignore); 501 if (gOpenFdTable == NULL) { 502 RuntimeAbort(env, __LINE__, "Unable to construct file descriptor table."); 503 } 504 } else if (!gOpenFdTable->Restat(fds_to_ignore)) { 505 RuntimeAbort(env, __LINE__, "Unable to restat file descriptor table."); 506 } 507 508 ResetNicePriority(env); 509 510 pid_t pid = fork(); 511 512 if (pid == 0) { 513 // The child process. 514 gMallocLeakZygoteChild = 1; 515 516 // Clean up any descriptors which must be closed immediately 517 DetachDescriptors(env, fdsToClose); 518 519 // Re-open all remaining open file descriptors so that they aren't shared 520 // with the zygote across a fork. 521 if (!gOpenFdTable->ReopenOrDetach()) { 522 RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors."); 523 } 524 525 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 526 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 527 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 528 } 529 530 // Keep capabilities across UID change, unless we're staying root. 531 if (uid != 0) { 532 EnableKeepCapabilities(env); 533 } 534 535 DropCapabilitiesBoundingSet(env); 536 537 bool use_native_bridge = !is_system_server && (instructionSet != NULL) 538 && android::NativeBridgeAvailable(); 539 if (use_native_bridge) { 540 ScopedUtfChars isa_string(env, instructionSet); 541 use_native_bridge = android::NeedsNativeBridge(isa_string.c_str()); 542 } 543 if (use_native_bridge && dataDir == NULL) { 544 // dataDir should never be null if we need to use a native bridge. 545 // In general, dataDir will never be null for normal applications. It can only happen in 546 // special cases (for isolated processes which are not associated with any app). These are 547 // launched by the framework and should not be emulated anyway. 548 use_native_bridge = false; 549 ALOGW("Native bridge will not be used because dataDir == NULL."); 550 } 551 552 if (!MountEmulatedStorage(uid, mount_external, use_native_bridge)) { 553 ALOGW("Failed to mount emulated storage: %s", strerror(errno)); 554 if (errno == ENOTCONN || errno == EROFS) { 555 // When device is actively encrypting, we get ENOTCONN here 556 // since FUSE was mounted before the framework restarted. 557 // When encrypted device is booting, we get EROFS since 558 // FUSE hasn't been created yet by init. 559 // In either case, continue without external storage. 560 } else { 561 RuntimeAbort(env, __LINE__, "Cannot continue without emulated storage"); 562 } 563 } 564 565 if (!is_system_server) { 566 int rc = createProcessGroup(uid, getpid()); 567 if (rc != 0) { 568 if (rc == -EROFS) { 569 ALOGW("createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?"); 570 } else { 571 ALOGE("createProcessGroup(%d, %d) failed: %s", uid, pid, strerror(-rc)); 572 } 573 } 574 } 575 576 SetGids(env, javaGids); 577 578 SetRLimits(env, javaRlimits); 579 580 if (use_native_bridge) { 581 ScopedUtfChars isa_string(env, instructionSet); 582 ScopedUtfChars data_dir(env, dataDir); 583 android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str()); 584 } 585 586 int rc = setresgid(gid, gid, gid); 587 if (rc == -1) { 588 ALOGE("setresgid(%d) failed: %s", gid, strerror(errno)); 589 RuntimeAbort(env, __LINE__, "setresgid failed"); 590 } 591 592 rc = setresuid(uid, uid, uid); 593 if (rc == -1) { 594 ALOGE("setresuid(%d) failed: %s", uid, strerror(errno)); 595 RuntimeAbort(env, __LINE__, "setresuid failed"); 596 } 597 598 if (NeedsNoRandomizeWorkaround()) { 599 // Work around ARM kernel ASLR lossage (http://b/5817320). 600 int old_personality = personality(0xffffffff); 601 int new_personality = personality(old_personality | ADDR_NO_RANDOMIZE); 602 if (new_personality == -1) { 603 ALOGW("personality(%d) failed: %s", new_personality, strerror(errno)); 604 } 605 } 606 607 SetCapabilities(env, permittedCapabilities, effectiveCapabilities); 608 609 SetSchedulerPolicy(env); 610 611 const char* se_info_c_str = NULL; 612 ScopedUtfChars* se_info = NULL; 613 if (java_se_info != NULL) { 614 se_info = new ScopedUtfChars(env, java_se_info); 615 se_info_c_str = se_info->c_str(); 616 if (se_info_c_str == NULL) { 617 RuntimeAbort(env, __LINE__, "se_info_c_str == NULL"); 618 } 619 } 620 const char* se_name_c_str = NULL; 621 ScopedUtfChars* se_name = NULL; 622 if (java_se_name != NULL) { 623 se_name = new ScopedUtfChars(env, java_se_name); 624 se_name_c_str = se_name->c_str(); 625 if (se_name_c_str == NULL) { 626 RuntimeAbort(env, __LINE__, "se_name_c_str == NULL"); 627 } 628 } 629 rc = selinux_android_setcontext(uid, is_system_server, se_info_c_str, se_name_c_str); 630 if (rc == -1) { 631 ALOGE("selinux_android_setcontext(%d, %d, \"%s\", \"%s\") failed", uid, 632 is_system_server, se_info_c_str, se_name_c_str); 633 RuntimeAbort(env, __LINE__, "selinux_android_setcontext failed"); 634 } 635 636 // Make it easier to debug audit logs by setting the main thread's name to the 637 // nice name rather than "app_process". 638 if (se_info_c_str == NULL && is_system_server) { 639 se_name_c_str = "system_server"; 640 } 641 if (se_info_c_str != NULL) { 642 SetThreadName(se_name_c_str); 643 } 644 645 delete se_info; 646 delete se_name; 647 648 UnsetSigChldHandler(); 649 650 env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags, 651 is_system_server, instructionSet); 652 if (env->ExceptionCheck()) { 653 RuntimeAbort(env, __LINE__, "Error calling post fork hooks."); 654 } 655 } else if (pid > 0) { 656 // the parent process 657 658 // We blocked SIGCHLD prior to a fork, we unblock it here. 659 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 660 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 661 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 662 } 663 } 664 return pid; 665} 666} // anonymous namespace 667 668namespace android { 669 670static jint com_android_internal_os_Zygote_nativeForkAndSpecialize( 671 JNIEnv* env, jclass, jint uid, jint gid, jintArray gids, 672 jint debug_flags, jobjectArray rlimits, 673 jint mount_external, jstring se_info, jstring se_name, 674 jintArray fdsToClose, 675 jintArray fdsToIgnore, 676 jstring instructionSet, jstring appDataDir) { 677 jlong capabilities = 0; 678 679 // Grant CAP_WAKE_ALARM to the Bluetooth process. 680 // Additionally, allow bluetooth to open packet sockets so it can start the DHCP client. 681 // TODO: consider making such functionality an RPC to netd. 682 if (multiuser_get_app_id(uid) == AID_BLUETOOTH) { 683 capabilities |= (1LL << CAP_WAKE_ALARM); 684 capabilities |= (1LL << CAP_NET_RAW); 685 capabilities |= (1LL << CAP_NET_BIND_SERVICE); 686 } 687 688 // Grant CAP_BLOCK_SUSPEND to processes that belong to GID "wakelock" 689 bool gid_wakelock_found = false; 690 if (gid == AID_WAKELOCK) { 691 gid_wakelock_found = true; 692 } else if (gids != NULL) { 693 jsize gids_num = env->GetArrayLength(gids); 694 ScopedIntArrayRO ar(env, gids); 695 if (ar.get() == NULL) { 696 RuntimeAbort(env, __LINE__, "Bad gids array"); 697 } 698 for (int i = 0; i < gids_num; i++) { 699 if (ar[i] == AID_WAKELOCK) { 700 gid_wakelock_found = true; 701 break; 702 } 703 } 704 } 705 if (gid_wakelock_found) { 706 capabilities |= (1LL << CAP_BLOCK_SUSPEND); 707 } 708 709 return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags, 710 rlimits, capabilities, capabilities, mount_external, se_info, 711 se_name, false, fdsToClose, fdsToIgnore, instructionSet, appDataDir); 712} 713 714static jint com_android_internal_os_Zygote_nativeForkSystemServer( 715 JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids, 716 jint debug_flags, jobjectArray rlimits, jlong permittedCapabilities, 717 jlong effectiveCapabilities) { 718 pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids, 719 debug_flags, rlimits, 720 permittedCapabilities, effectiveCapabilities, 721 MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true, NULL, 722 NULL, NULL, NULL); 723 if (pid > 0) { 724 // The zygote process checks whether the child process has died or not. 725 ALOGI("System server process %d has been created", pid); 726 gSystemServerPid = pid; 727 // There is a slight window that the system server process has crashed 728 // but it went unnoticed because we haven't published its pid yet. So 729 // we recheck here just to make sure that all is well. 730 int status; 731 if (waitpid(pid, &status, WNOHANG) == pid) { 732 ALOGE("System server process %d has died. Restarting Zygote!", pid); 733 RuntimeAbort(env, __LINE__, "System server process has died. Restarting Zygote!"); 734 } 735 } 736 return pid; 737} 738 739static void com_android_internal_os_Zygote_nativeAllowFileAcrossFork( 740 JNIEnv* env, jclass, jstring path) { 741 ScopedUtfChars path_native(env, path); 742 const char* path_cstr = path_native.c_str(); 743 if (!path_cstr) { 744 RuntimeAbort(env, __LINE__, "path_cstr == NULL"); 745 } 746 FileDescriptorWhitelist::Get()->Allow(path_cstr); 747} 748 749static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) { 750 // Zygote process unmount root storage space initially before every child processes are forked. 751 // Every forked child processes (include SystemServer) only mount their own root storage space 752 // and no need unmount storage operation in MountEmulatedStorage method. 753 // Zygote process does not utilize root storage spaces and unshares its mount namespace below. 754 755 // See storage config details at http://source.android.com/tech/storage/ 756 // Create private mount namespace shared by all children 757 if (unshare(CLONE_NEWNS) == -1) { 758 RuntimeAbort(env, __LINE__, "Failed to unshare()"); 759 return; 760 } 761 762 // Mark rootfs as being a slave so that changes from default 763 // namespace only flow into our children. 764 if (mount("rootfs", "/", nullptr, (MS_SLAVE | MS_REC), nullptr) == -1) { 765 RuntimeAbort(env, __LINE__, "Failed to mount() rootfs as MS_SLAVE"); 766 return; 767 } 768 769 // Create a staging tmpfs that is shared by our children; they will 770 // bind mount storage into their respective private namespaces, which 771 // are isolated from each other. 772 const char* target_base = getenv("EMULATED_STORAGE_TARGET"); 773 if (target_base != nullptr) { 774#define STRINGIFY_UID(x) __STRING(x) 775 if (mount("tmpfs", target_base, "tmpfs", MS_NOSUID | MS_NODEV, 776 "uid=0,gid=" STRINGIFY_UID(AID_SDCARD_R) ",mode=0751") == -1) { 777 ALOGE("Failed to mount tmpfs to %s", target_base); 778 RuntimeAbort(env, __LINE__, "Failed to mount tmpfs"); 779 return; 780 } 781#undef STRINGIFY_UID 782 } 783 784 UnmountTree("/storage"); 785} 786 787static const JNINativeMethod gMethods[] = { 788 { "nativeForkAndSpecialize", 789 "(II[II[[IILjava/lang/String;Ljava/lang/String;[I[ILjava/lang/String;Ljava/lang/String;)I", 790 (void *) com_android_internal_os_Zygote_nativeForkAndSpecialize }, 791 { "nativeForkSystemServer", "(II[II[[IJJ)I", 792 (void *) com_android_internal_os_Zygote_nativeForkSystemServer }, 793 { "nativeAllowFileAcrossFork", "(Ljava/lang/String;)V", 794 (void *) com_android_internal_os_Zygote_nativeAllowFileAcrossFork }, 795 { "nativeUnmountStorageOnInit", "()V", 796 (void *) com_android_internal_os_Zygote_nativeUnmountStorageOnInit } 797}; 798 799int register_com_android_internal_os_Zygote(JNIEnv* env) { 800 gZygoteClass = MakeGlobalRefOrDie(env, FindClassOrDie(env, kZygoteClassName)); 801 gCallPostForkChildHooks = GetStaticMethodIDOrDie(env, gZygoteClass, "callPostForkChildHooks", 802 "(IZLjava/lang/String;)V"); 803 804 return RegisterMethodsOrDie(env, "com/android/internal/os/Zygote", gMethods, NELEM(gMethods)); 805} 806} // namespace android 807