com_android_internal_os_Zygote.cpp revision 6d747cacae4f3c39d9360b62aca4ecf01b180727
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 <malloc.h> 31#include <mntent.h> 32#include <paths.h> 33#include <signal.h> 34#include <stdlib.h> 35#include <sys/capability.h> 36#include <sys/cdefs.h> 37#include <sys/personality.h> 38#include <sys/prctl.h> 39#include <sys/resource.h> 40#include <sys/stat.h> 41#include <sys/time.h> 42#include <sys/types.h> 43#include <sys/utsname.h> 44#include <sys/wait.h> 45#include <unistd.h> 46 47#include "android-base/logging.h" 48#include <cutils/fs.h> 49#include <cutils/multiuser.h> 50#include <cutils/sched_policy.h> 51#include <private/android_filesystem_config.h> 52#include <utils/String8.h> 53#include <selinux/android.h> 54#include <processgroup/processgroup.h> 55 56#include "core_jni_helpers.h" 57#include "JNIHelp.h" 58#include "ScopedLocalRef.h" 59#include "ScopedPrimitiveArray.h" 60#include "ScopedUtfChars.h" 61#include "fd_utils.h" 62 63#include "nativebridge/native_bridge.h" 64 65namespace { 66 67using android::String8; 68 69static pid_t gSystemServerPid = 0; 70 71static const char kZygoteClassName[] = "com/android/internal/os/Zygote"; 72static jclass gZygoteClass; 73static jmethodID gCallPostForkChildHooks; 74 75// Must match values in com.android.internal.os.Zygote. 76enum MountExternalKind { 77 MOUNT_EXTERNAL_NONE = 0, 78 MOUNT_EXTERNAL_DEFAULT = 1, 79 MOUNT_EXTERNAL_READ = 2, 80 MOUNT_EXTERNAL_WRITE = 3, 81}; 82 83static void RuntimeAbort(JNIEnv* env, int line, const char* msg) { 84 std::ostringstream oss; 85 oss << __FILE__ << ":" << line << ": " << msg; 86 env->FatalError(oss.str().c_str()); 87} 88 89// This signal handler is for zygote mode, since the zygote must reap its children 90static void SigChldHandler(int /*signal_number*/) { 91 pid_t pid; 92 int status; 93 94 // It's necessary to save and restore the errno during this function. 95 // Since errno is stored per thread, changing it here modifies the errno 96 // on the thread on which this signal handler executes. If a signal occurs 97 // between a call and an errno check, it's possible to get the errno set 98 // here. 99 // See b/23572286 for extra information. 100 int saved_errno = errno; 101 102 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) { 103 // Log process-death status that we care about. In general it is 104 // not safe to call LOG(...) from a signal handler because of 105 // possible reentrancy. However, we know a priori that the 106 // current implementation of LOG() is safe to call from a SIGCHLD 107 // handler in the zygote process. If the LOG() implementation 108 // changes its locking strategy or its use of syscalls within the 109 // lazy-init critical section, its use here may become unsafe. 110 if (WIFEXITED(status)) { 111 ALOGI("Process %d exited cleanly (%d)", pid, WEXITSTATUS(status)); 112 } else if (WIFSIGNALED(status)) { 113 ALOGI("Process %d exited due to signal (%d)", pid, WTERMSIG(status)); 114 if (WCOREDUMP(status)) { 115 ALOGI("Process %d dumped core.", pid); 116 } 117 } 118 119 // If the just-crashed process is the system_server, bring down zygote 120 // so that it is restarted by init and system server will be restarted 121 // from there. 122 if (pid == gSystemServerPid) { 123 ALOGE("Exit zygote because system server (%d) has terminated", pid); 124 kill(getpid(), SIGKILL); 125 } 126 } 127 128 // Note that we shouldn't consider ECHILD an error because 129 // the secondary zygote might have no children left to wait for. 130 if (pid < 0 && errno != ECHILD) { 131 ALOGW("Zygote SIGCHLD error in waitpid: %s", strerror(errno)); 132 } 133 134 errno = saved_errno; 135} 136 137// Configures the SIGCHLD handler for the zygote process. This is configured 138// very late, because earlier in the runtime we may fork() and exec() 139// other processes, and we want to waitpid() for those rather than 140// have them be harvested immediately. 141// 142// This ends up being called repeatedly before each fork(), but there's 143// no real harm in that. 144static void SetSigChldHandler() { 145 struct sigaction sa; 146 memset(&sa, 0, sizeof(sa)); 147 sa.sa_handler = SigChldHandler; 148 149 int err = sigaction(SIGCHLD, &sa, NULL); 150 if (err < 0) { 151 ALOGW("Error setting SIGCHLD handler: %s", strerror(errno)); 152 } 153} 154 155// Sets the SIGCHLD handler back to default behavior in zygote children. 156static void UnsetSigChldHandler() { 157 struct sigaction sa; 158 memset(&sa, 0, sizeof(sa)); 159 sa.sa_handler = SIG_DFL; 160 161 int err = sigaction(SIGCHLD, &sa, NULL); 162 if (err < 0) { 163 ALOGW("Error unsetting SIGCHLD handler: %s", strerror(errno)); 164 } 165} 166 167// Calls POSIX setgroups() using the int[] object as an argument. 168// A NULL argument is tolerated. 169static void SetGids(JNIEnv* env, jintArray javaGids) { 170 if (javaGids == NULL) { 171 return; 172 } 173 174 ScopedIntArrayRO gids(env, javaGids); 175 if (gids.get() == NULL) { 176 RuntimeAbort(env, __LINE__, "Getting gids int array failed"); 177 } 178 int rc = setgroups(gids.size(), reinterpret_cast<const gid_t*>(&gids[0])); 179 if (rc == -1) { 180 std::ostringstream oss; 181 oss << "setgroups failed: " << strerror(errno) << ", gids.size=" << gids.size(); 182 RuntimeAbort(env, __LINE__, oss.str().c_str()); 183 } 184} 185 186// Sets the resource limits via setrlimit(2) for the values in the 187// two-dimensional array of integers that's passed in. The second dimension 188// contains a tuple of length 3: (resource, rlim_cur, rlim_max). NULL is 189// treated as an empty array. 190static void SetRLimits(JNIEnv* env, jobjectArray javaRlimits) { 191 if (javaRlimits == NULL) { 192 return; 193 } 194 195 rlimit rlim; 196 memset(&rlim, 0, sizeof(rlim)); 197 198 for (int i = 0; i < env->GetArrayLength(javaRlimits); ++i) { 199 ScopedLocalRef<jobject> javaRlimitObject(env, env->GetObjectArrayElement(javaRlimits, i)); 200 ScopedIntArrayRO javaRlimit(env, reinterpret_cast<jintArray>(javaRlimitObject.get())); 201 if (javaRlimit.size() != 3) { 202 RuntimeAbort(env, __LINE__, "rlimits array must have a second dimension of size 3"); 203 } 204 205 rlim.rlim_cur = javaRlimit[1]; 206 rlim.rlim_max = javaRlimit[2]; 207 208 int rc = setrlimit(javaRlimit[0], &rlim); 209 if (rc == -1) { 210 ALOGE("setrlimit(%d, {%ld, %ld}) failed", javaRlimit[0], rlim.rlim_cur, 211 rlim.rlim_max); 212 RuntimeAbort(env, __LINE__, "setrlimit failed"); 213 } 214 } 215} 216 217// The debug malloc library needs to know whether it's the zygote or a child. 218extern "C" int gMallocLeakZygoteChild; 219 220static void PreApplicationInit() { 221 // The child process sets this to indicate it's not the zygote. 222 gMallocLeakZygoteChild = 1; 223 224 // Set the jemalloc decay time to 1. 225 mallopt(M_DECAY_TIME, 1); 226} 227 228static void EnableKeepCapabilities(JNIEnv* env) { 229 int rc = prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0); 230 if (rc == -1) { 231 RuntimeAbort(env, __LINE__, "prctl(PR_SET_KEEPCAPS) failed"); 232 } 233} 234 235static void DropCapabilitiesBoundingSet(JNIEnv* env) { 236 for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) { 237 int rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); 238 if (rc == -1) { 239 if (errno == EINVAL) { 240 ALOGE("prctl(PR_CAPBSET_DROP) failed with EINVAL. Please verify " 241 "your kernel is compiled with file capabilities support"); 242 } else { 243 ALOGE("prctl(PR_CAPBSET_DROP, %d) failed: %s", i, strerror(errno)); 244 RuntimeAbort(env, __LINE__, "prctl(PR_CAPBSET_DROP) failed"); 245 } 246 } 247 } 248} 249 250static void SetInheritable(JNIEnv* env, uint64_t inheritable) { 251 __user_cap_header_struct capheader; 252 memset(&capheader, 0, sizeof(capheader)); 253 capheader.version = _LINUX_CAPABILITY_VERSION_3; 254 capheader.pid = 0; 255 256 __user_cap_data_struct capdata[2]; 257 if (capget(&capheader, &capdata[0]) == -1) { 258 ALOGE("capget failed: %s", strerror(errno)); 259 RuntimeAbort(env, __LINE__, "capget failed"); 260 } 261 262 capdata[0].inheritable = inheritable; 263 capdata[1].inheritable = inheritable >> 32; 264 265 if (capset(&capheader, &capdata[0]) == -1) { 266 ALOGE("capset(inh=%" PRIx64 ") failed: %s", inheritable, strerror(errno)); 267 RuntimeAbort(env, __LINE__, "capset failed"); 268 } 269} 270 271static void SetCapabilities(JNIEnv* env, uint64_t permitted, uint64_t effective, 272 uint64_t inheritable) { 273 __user_cap_header_struct capheader; 274 memset(&capheader, 0, sizeof(capheader)); 275 capheader.version = _LINUX_CAPABILITY_VERSION_3; 276 capheader.pid = 0; 277 278 __user_cap_data_struct capdata[2]; 279 memset(&capdata, 0, sizeof(capdata)); 280 capdata[0].effective = effective; 281 capdata[1].effective = effective >> 32; 282 capdata[0].permitted = permitted; 283 capdata[1].permitted = permitted >> 32; 284 capdata[0].inheritable = inheritable; 285 capdata[1].inheritable = inheritable >> 32; 286 287 if (capset(&capheader, &capdata[0]) == -1) { 288 ALOGE("capset(perm=%" PRIx64 ", eff=%" PRIx64 ", inh=%" PRIx64 ") failed: %s", permitted, 289 effective, inheritable, strerror(errno)); 290 RuntimeAbort(env, __LINE__, "capset failed"); 291 } 292} 293 294static void SetSchedulerPolicy(JNIEnv* env) { 295 errno = -set_sched_policy(0, SP_DEFAULT); 296 if (errno != 0) { 297 ALOGE("set_sched_policy(0, SP_DEFAULT) failed"); 298 RuntimeAbort(env, __LINE__, "set_sched_policy(0, SP_DEFAULT) failed"); 299 } 300} 301 302static int UnmountTree(const char* path) { 303 size_t path_len = strlen(path); 304 305 FILE* fp = setmntent("/proc/mounts", "r"); 306 if (fp == NULL) { 307 ALOGE("Error opening /proc/mounts: %s", strerror(errno)); 308 return -errno; 309 } 310 311 // Some volumes can be stacked on each other, so force unmount in 312 // reverse order to give us the best chance of success. 313 std::list<std::string> toUnmount; 314 mntent* mentry; 315 while ((mentry = getmntent(fp)) != NULL) { 316 if (strncmp(mentry->mnt_dir, path, path_len) == 0) { 317 toUnmount.push_front(std::string(mentry->mnt_dir)); 318 } 319 } 320 endmntent(fp); 321 322 for (auto path : toUnmount) { 323 if (umount2(path.c_str(), MNT_DETACH)) { 324 ALOGW("Failed to unmount %s: %s", path.c_str(), strerror(errno)); 325 } 326 } 327 return 0; 328} 329 330// Create a private mount namespace and bind mount appropriate emulated 331// storage for the given user. 332static bool MountEmulatedStorage(uid_t uid, jint mount_mode, 333 bool force_mount_namespace) { 334 // See storage config details at http://source.android.com/tech/storage/ 335 336 String8 storageSource; 337 if (mount_mode == MOUNT_EXTERNAL_DEFAULT) { 338 storageSource = "/mnt/runtime/default"; 339 } else if (mount_mode == MOUNT_EXTERNAL_READ) { 340 storageSource = "/mnt/runtime/read"; 341 } else if (mount_mode == MOUNT_EXTERNAL_WRITE) { 342 storageSource = "/mnt/runtime/write"; 343 } else if (!force_mount_namespace) { 344 // Sane default of no storage visible 345 return true; 346 } 347 348 // Create a second private mount namespace for our process 349 if (unshare(CLONE_NEWNS) == -1) { 350 ALOGW("Failed to unshare(): %s", strerror(errno)); 351 return false; 352 } 353 354 // Handle force_mount_namespace with MOUNT_EXTERNAL_NONE. 355 if (mount_mode == MOUNT_EXTERNAL_NONE) { 356 return true; 357 } 358 359 if (TEMP_FAILURE_RETRY(mount(storageSource.string(), "/storage", 360 NULL, MS_BIND | MS_REC | MS_SLAVE, NULL)) == -1) { 361 ALOGW("Failed to mount %s to /storage: %s", storageSource.string(), strerror(errno)); 362 return false; 363 } 364 365 // Mount user-specific symlink helper into place 366 userid_t user_id = multiuser_get_user_id(uid); 367 const String8 userSource(String8::format("/mnt/user/%d", user_id)); 368 if (fs_prepare_dir(userSource.string(), 0751, 0, 0) == -1) { 369 return false; 370 } 371 if (TEMP_FAILURE_RETRY(mount(userSource.string(), "/storage/self", 372 NULL, MS_BIND, NULL)) == -1) { 373 ALOGW("Failed to mount %s to /storage/self: %s", userSource.string(), strerror(errno)); 374 return false; 375 } 376 377 return true; 378} 379 380static bool NeedsNoRandomizeWorkaround() { 381#if !defined(__arm__) 382 return false; 383#else 384 int major; 385 int minor; 386 struct utsname uts; 387 if (uname(&uts) == -1) { 388 return false; 389 } 390 391 if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) { 392 return false; 393 } 394 395 // Kernels before 3.4.* need the workaround. 396 return (major < 3) || ((major == 3) && (minor < 4)); 397#endif 398} 399 400// Utility to close down the Zygote socket file descriptors while 401// the child is still running as root with Zygote's privileges. Each 402// descriptor (if any) is closed via dup2(), replacing it with a valid 403// (open) descriptor to /dev/null. 404 405static void DetachDescriptors(JNIEnv* env, jintArray fdsToClose) { 406 if (!fdsToClose) { 407 return; 408 } 409 jsize count = env->GetArrayLength(fdsToClose); 410 ScopedIntArrayRO ar(env, fdsToClose); 411 if (ar.get() == NULL) { 412 RuntimeAbort(env, __LINE__, "Bad fd array"); 413 } 414 jsize i; 415 int devnull; 416 for (i = 0; i < count; i++) { 417 devnull = open("/dev/null", O_RDWR); 418 if (devnull < 0) { 419 ALOGE("Failed to open /dev/null: %s", strerror(errno)); 420 RuntimeAbort(env, __LINE__, "Failed to open /dev/null"); 421 continue; 422 } 423 ALOGV("Switching descriptor %d to /dev/null: %s", ar[i], strerror(errno)); 424 if (dup2(devnull, ar[i]) < 0) { 425 ALOGE("Failed dup2() on descriptor %d: %s", ar[i], strerror(errno)); 426 RuntimeAbort(env, __LINE__, "Failed dup2()"); 427 } 428 close(devnull); 429 } 430} 431 432void SetThreadName(const char* thread_name) { 433 bool hasAt = false; 434 bool hasDot = false; 435 const char* s = thread_name; 436 while (*s) { 437 if (*s == '.') { 438 hasDot = true; 439 } else if (*s == '@') { 440 hasAt = true; 441 } 442 s++; 443 } 444 const int len = s - thread_name; 445 if (len < 15 || hasAt || !hasDot) { 446 s = thread_name; 447 } else { 448 s = thread_name + len - 15; 449 } 450 // pthread_setname_np fails rather than truncating long strings. 451 char buf[16]; // MAX_TASK_COMM_LEN=16 is hard-coded into bionic 452 strlcpy(buf, s, sizeof(buf)-1); 453 errno = pthread_setname_np(pthread_self(), buf); 454 if (errno != 0) { 455 ALOGW("Unable to set the name of current thread to '%s': %s", buf, strerror(errno)); 456 } 457} 458 459// The list of open zygote file descriptors. 460static FileDescriptorTable* gOpenFdTable = NULL; 461 462static void FillFileDescriptorVector(JNIEnv* env, 463 jintArray java_fds, 464 std::vector<int>* fds) { 465 CHECK(fds != nullptr); 466 if (java_fds != nullptr) { 467 ScopedIntArrayRO ar(env, java_fds); 468 if (ar.get() == nullptr) { 469 RuntimeAbort(env, __LINE__, "Bad fd array"); 470 } 471 fds->reserve(ar.size()); 472 for (size_t i = 0; i < ar.size(); ++i) { 473 fds->push_back(ar[i]); 474 } 475 } 476} 477 478// Utility routine to fork zygote and specialize the child process. 479static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids, 480 jint debug_flags, jobjectArray javaRlimits, 481 jlong permittedCapabilities, jlong effectiveCapabilities, 482 jint mount_external, 483 jstring java_se_info, jstring java_se_name, 484 bool is_system_server, jintArray fdsToClose, 485 jintArray fdsToIgnore, 486 jstring instructionSet, jstring dataDir) { 487 SetSigChldHandler(); 488 489 sigset_t sigchld; 490 sigemptyset(&sigchld); 491 sigaddset(&sigchld, SIGCHLD); 492 493 // Temporarily block SIGCHLD during forks. The SIGCHLD handler might 494 // log, which would result in the logging FDs we close being reopened. 495 // This would cause failures because the FDs are not whitelisted. 496 // 497 // Note that the zygote process is single threaded at this point. 498 if (sigprocmask(SIG_BLOCK, &sigchld, nullptr) == -1) { 499 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 500 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_BLOCK, { SIGCHLD }) failed."); 501 } 502 503 // Close any logging related FDs before we start evaluating the list of 504 // file descriptors. 505 __android_log_close(); 506 507 // If this is the first fork for this zygote, create the open FD table. 508 // If it isn't, we just need to check whether the list of open files has 509 // changed (and it shouldn't in the normal case). 510 std::vector<int> fds_to_ignore; 511 FillFileDescriptorVector(env, fdsToIgnore, &fds_to_ignore); 512 if (gOpenFdTable == NULL) { 513 gOpenFdTable = FileDescriptorTable::Create(fds_to_ignore); 514 if (gOpenFdTable == NULL) { 515 RuntimeAbort(env, __LINE__, "Unable to construct file descriptor table."); 516 } 517 } else if (!gOpenFdTable->Restat(fds_to_ignore)) { 518 RuntimeAbort(env, __LINE__, "Unable to restat file descriptor table."); 519 } 520 521 pid_t pid = fork(); 522 523 if (pid == 0) { 524 PreApplicationInit(); 525 526 // Clean up any descriptors which must be closed immediately 527 DetachDescriptors(env, fdsToClose); 528 529 // Re-open all remaining open file descriptors so that they aren't shared 530 // with the zygote across a fork. 531 if (!gOpenFdTable->ReopenOrDetach()) { 532 RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors."); 533 } 534 535 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 536 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 537 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 538 } 539 540 // Keep capabilities across UID change, unless we're staying root. 541 if (uid != 0) { 542 EnableKeepCapabilities(env); 543 } 544 545 SetInheritable(env, permittedCapabilities); 546 DropCapabilitiesBoundingSet(env); 547 548 bool use_native_bridge = !is_system_server && (instructionSet != NULL) 549 && android::NativeBridgeAvailable(); 550 if (use_native_bridge) { 551 ScopedUtfChars isa_string(env, instructionSet); 552 use_native_bridge = android::NeedsNativeBridge(isa_string.c_str()); 553 } 554 if (use_native_bridge && dataDir == NULL) { 555 // dataDir should never be null if we need to use a native bridge. 556 // In general, dataDir will never be null for normal applications. It can only happen in 557 // special cases (for isolated processes which are not associated with any app). These are 558 // launched by the framework and should not be emulated anyway. 559 use_native_bridge = false; 560 ALOGW("Native bridge will not be used because dataDir == NULL."); 561 } 562 563 if (!MountEmulatedStorage(uid, mount_external, use_native_bridge)) { 564 ALOGW("Failed to mount emulated storage: %s", strerror(errno)); 565 if (errno == ENOTCONN || errno == EROFS) { 566 // When device is actively encrypting, we get ENOTCONN here 567 // since FUSE was mounted before the framework restarted. 568 // When encrypted device is booting, we get EROFS since 569 // FUSE hasn't been created yet by init. 570 // In either case, continue without external storage. 571 } else { 572 RuntimeAbort(env, __LINE__, "Cannot continue without emulated storage"); 573 } 574 } 575 576 if (!is_system_server) { 577 int rc = createProcessGroup(uid, getpid()); 578 if (rc != 0) { 579 if (rc == -EROFS) { 580 ALOGW("createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?"); 581 } else { 582 ALOGE("createProcessGroup(%d, %d) failed: %s", uid, pid, strerror(-rc)); 583 } 584 } 585 } 586 587 SetGids(env, javaGids); 588 589 SetRLimits(env, javaRlimits); 590 591 if (use_native_bridge) { 592 ScopedUtfChars isa_string(env, instructionSet); 593 ScopedUtfChars data_dir(env, dataDir); 594 android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str()); 595 } 596 597 int rc = setresgid(gid, gid, gid); 598 if (rc == -1) { 599 ALOGE("setresgid(%d) failed: %s", gid, strerror(errno)); 600 RuntimeAbort(env, __LINE__, "setresgid failed"); 601 } 602 603 rc = setresuid(uid, uid, uid); 604 if (rc == -1) { 605 ALOGE("setresuid(%d) failed: %s", uid, strerror(errno)); 606 RuntimeAbort(env, __LINE__, "setresuid failed"); 607 } 608 609 if (NeedsNoRandomizeWorkaround()) { 610 // Work around ARM kernel ASLR lossage (http://b/5817320). 611 int old_personality = personality(0xffffffff); 612 int new_personality = personality(old_personality | ADDR_NO_RANDOMIZE); 613 if (new_personality == -1) { 614 ALOGW("personality(%d) failed: %s", new_personality, strerror(errno)); 615 } 616 } 617 618 SetCapabilities(env, permittedCapabilities, effectiveCapabilities, permittedCapabilities); 619 620 SetSchedulerPolicy(env); 621 622 const char* se_info_c_str = NULL; 623 ScopedUtfChars* se_info = NULL; 624 if (java_se_info != NULL) { 625 se_info = new ScopedUtfChars(env, java_se_info); 626 se_info_c_str = se_info->c_str(); 627 if (se_info_c_str == NULL) { 628 RuntimeAbort(env, __LINE__, "se_info_c_str == NULL"); 629 } 630 } 631 const char* se_name_c_str = NULL; 632 ScopedUtfChars* se_name = NULL; 633 if (java_se_name != NULL) { 634 se_name = new ScopedUtfChars(env, java_se_name); 635 se_name_c_str = se_name->c_str(); 636 if (se_name_c_str == NULL) { 637 RuntimeAbort(env, __LINE__, "se_name_c_str == NULL"); 638 } 639 } 640 rc = selinux_android_setcontext(uid, is_system_server, se_info_c_str, se_name_c_str); 641 if (rc == -1) { 642 ALOGE("selinux_android_setcontext(%d, %d, \"%s\", \"%s\") failed", uid, 643 is_system_server, se_info_c_str, se_name_c_str); 644 RuntimeAbort(env, __LINE__, "selinux_android_setcontext failed"); 645 } 646 647 // Make it easier to debug audit logs by setting the main thread's name to the 648 // nice name rather than "app_process". 649 if (se_info_c_str == NULL && is_system_server) { 650 se_name_c_str = "system_server"; 651 } 652 if (se_info_c_str != NULL) { 653 SetThreadName(se_name_c_str); 654 } 655 656 delete se_info; 657 delete se_name; 658 659 UnsetSigChldHandler(); 660 661 env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags, 662 is_system_server, instructionSet); 663 if (env->ExceptionCheck()) { 664 RuntimeAbort(env, __LINE__, "Error calling post fork hooks."); 665 } 666 } else if (pid > 0) { 667 // the parent process 668 669 // We blocked SIGCHLD prior to a fork, we unblock it here. 670 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 671 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 672 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 673 } 674 } 675 return pid; 676} 677} // anonymous namespace 678 679namespace android { 680 681static void com_android_internal_os_Zygote_nativePreApplicationInit(JNIEnv*, jclass) { 682 PreApplicationInit(); 683} 684 685static jint com_android_internal_os_Zygote_nativeForkAndSpecialize( 686 JNIEnv* env, jclass, jint uid, jint gid, jintArray gids, 687 jint debug_flags, jobjectArray rlimits, 688 jint mount_external, jstring se_info, jstring se_name, 689 jintArray fdsToClose, 690 jintArray fdsToIgnore, 691 jstring instructionSet, jstring appDataDir) { 692 jlong capabilities = 0; 693 694 // Grant CAP_WAKE_ALARM to the Bluetooth process. 695 // Additionally, allow bluetooth to open packet sockets so it can start the DHCP client. 696 // Grant CAP_SYS_NICE to allow Bluetooth to set RT priority for 697 // audio-related threads. 698 // TODO: consider making such functionality an RPC to netd. 699 if (multiuser_get_app_id(uid) == AID_BLUETOOTH) { 700 capabilities |= (1LL << CAP_WAKE_ALARM); 701 capabilities |= (1LL << CAP_NET_RAW); 702 capabilities |= (1LL << CAP_NET_BIND_SERVICE); 703 capabilities |= (1LL << CAP_SYS_NICE); 704 } 705 706 // Grant CAP_BLOCK_SUSPEND to processes that belong to GID "wakelock" 707 bool gid_wakelock_found = false; 708 if (gid == AID_WAKELOCK) { 709 gid_wakelock_found = true; 710 } else if (gids != NULL) { 711 jsize gids_num = env->GetArrayLength(gids); 712 ScopedIntArrayRO ar(env, gids); 713 if (ar.get() == NULL) { 714 RuntimeAbort(env, __LINE__, "Bad gids array"); 715 } 716 for (int i = 0; i < gids_num; i++) { 717 if (ar[i] == AID_WAKELOCK) { 718 gid_wakelock_found = true; 719 break; 720 } 721 } 722 } 723 if (gid_wakelock_found) { 724 capabilities |= (1LL << CAP_BLOCK_SUSPEND); 725 } 726 727 return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags, 728 rlimits, capabilities, capabilities, mount_external, se_info, 729 se_name, false, fdsToClose, fdsToIgnore, instructionSet, appDataDir); 730} 731 732static jint com_android_internal_os_Zygote_nativeForkSystemServer( 733 JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids, 734 jint debug_flags, jobjectArray rlimits, jlong permittedCapabilities, 735 jlong effectiveCapabilities) { 736 pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids, 737 debug_flags, rlimits, 738 permittedCapabilities, effectiveCapabilities, 739 MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true, NULL, 740 NULL, NULL, NULL); 741 if (pid > 0) { 742 // The zygote process checks whether the child process has died or not. 743 ALOGI("System server process %d has been created", pid); 744 gSystemServerPid = pid; 745 // There is a slight window that the system server process has crashed 746 // but it went unnoticed because we haven't published its pid yet. So 747 // we recheck here just to make sure that all is well. 748 int status; 749 if (waitpid(pid, &status, WNOHANG) == pid) { 750 ALOGE("System server process %d has died. Restarting Zygote!", pid); 751 RuntimeAbort(env, __LINE__, "System server process has died. Restarting Zygote!"); 752 } 753 } 754 return pid; 755} 756 757static void com_android_internal_os_Zygote_nativeAllowFileAcrossFork( 758 JNIEnv* env, jclass, jstring path) { 759 ScopedUtfChars path_native(env, path); 760 const char* path_cstr = path_native.c_str(); 761 if (!path_cstr) { 762 RuntimeAbort(env, __LINE__, "path_cstr == NULL"); 763 } 764 FileDescriptorWhitelist::Get()->Allow(path_cstr); 765} 766 767static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) { 768 // Zygote process unmount root storage space initially before every child processes are forked. 769 // Every forked child processes (include SystemServer) only mount their own root storage space 770 // and no need unmount storage operation in MountEmulatedStorage method. 771 // Zygote process does not utilize root storage spaces and unshares its mount namespace below. 772 773 // See storage config details at http://source.android.com/tech/storage/ 774 // Create private mount namespace shared by all children 775 if (unshare(CLONE_NEWNS) == -1) { 776 RuntimeAbort(env, __LINE__, "Failed to unshare()"); 777 return; 778 } 779 780 // Mark rootfs as being a slave so that changes from default 781 // namespace only flow into our children. 782 if (mount("rootfs", "/", nullptr, (MS_SLAVE | MS_REC), nullptr) == -1) { 783 RuntimeAbort(env, __LINE__, "Failed to mount() rootfs as MS_SLAVE"); 784 return; 785 } 786 787 // Create a staging tmpfs that is shared by our children; they will 788 // bind mount storage into their respective private namespaces, which 789 // are isolated from each other. 790 const char* target_base = getenv("EMULATED_STORAGE_TARGET"); 791 if (target_base != nullptr) { 792#define STRINGIFY_UID(x) __STRING(x) 793 if (mount("tmpfs", target_base, "tmpfs", MS_NOSUID | MS_NODEV, 794 "uid=0,gid=" STRINGIFY_UID(AID_SDCARD_R) ",mode=0751") == -1) { 795 ALOGE("Failed to mount tmpfs to %s", target_base); 796 RuntimeAbort(env, __LINE__, "Failed to mount tmpfs"); 797 return; 798 } 799#undef STRINGIFY_UID 800 } 801 802 UnmountTree("/storage"); 803} 804 805static const JNINativeMethod gMethods[] = { 806 { "nativeForkAndSpecialize", 807 "(II[II[[IILjava/lang/String;Ljava/lang/String;[I[ILjava/lang/String;Ljava/lang/String;)I", 808 (void *) com_android_internal_os_Zygote_nativeForkAndSpecialize }, 809 { "nativeForkSystemServer", "(II[II[[IJJ)I", 810 (void *) com_android_internal_os_Zygote_nativeForkSystemServer }, 811 { "nativeAllowFileAcrossFork", "(Ljava/lang/String;)V", 812 (void *) com_android_internal_os_Zygote_nativeAllowFileAcrossFork }, 813 { "nativeUnmountStorageOnInit", "()V", 814 (void *) com_android_internal_os_Zygote_nativeUnmountStorageOnInit }, 815 { "nativePreApplicationInit", "()V", 816 (void *) com_android_internal_os_Zygote_nativePreApplicationInit } 817}; 818 819int register_com_android_internal_os_Zygote(JNIEnv* env) { 820 gZygoteClass = MakeGlobalRefOrDie(env, FindClassOrDie(env, kZygoteClassName)); 821 gCallPostForkChildHooks = GetStaticMethodIDOrDie(env, gZygoteClass, "callPostForkChildHooks", 822 "(IZLjava/lang/String;)V"); 823 824 return RegisterMethodsOrDie(env, "com/android/internal/os/Zygote", gMethods, NELEM(gMethods)); 825} 826} // namespace android 827