com_android_internal_os_Zygote.cpp revision 6f372daa9d31fb6843a24fe12669a1f73e7ca8ab
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 int rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); 251 if (rc == -1) { 252 if (errno == EINVAL) { 253 ALOGE("prctl(PR_CAPBSET_DROP) failed with EINVAL. Please verify " 254 "your kernel is compiled with file capabilities support"); 255 } else { 256 ALOGE("prctl(PR_CAPBSET_DROP, %d) failed: %s", i, strerror(errno)); 257 RuntimeAbort(env, __LINE__, "prctl(PR_CAPBSET_DROP) failed"); 258 } 259 } 260 } 261} 262 263static void SetInheritable(JNIEnv* env, uint64_t inheritable) { 264 __user_cap_header_struct capheader; 265 memset(&capheader, 0, sizeof(capheader)); 266 capheader.version = _LINUX_CAPABILITY_VERSION_3; 267 capheader.pid = 0; 268 269 __user_cap_data_struct capdata[2]; 270 if (capget(&capheader, &capdata[0]) == -1) { 271 ALOGE("capget failed: %s", strerror(errno)); 272 RuntimeAbort(env, __LINE__, "capget failed"); 273 } 274 275 capdata[0].inheritable = inheritable; 276 capdata[1].inheritable = inheritable >> 32; 277 278 if (capset(&capheader, &capdata[0]) == -1) { 279 ALOGE("capset(inh=%" PRIx64 ") failed: %s", inheritable, strerror(errno)); 280 RuntimeAbort(env, __LINE__, "capset failed"); 281 } 282} 283 284static void SetCapabilities(JNIEnv* env, uint64_t permitted, uint64_t effective, 285 uint64_t inheritable) { 286 __user_cap_header_struct capheader; 287 memset(&capheader, 0, sizeof(capheader)); 288 capheader.version = _LINUX_CAPABILITY_VERSION_3; 289 capheader.pid = 0; 290 291 __user_cap_data_struct capdata[2]; 292 memset(&capdata, 0, sizeof(capdata)); 293 capdata[0].effective = effective; 294 capdata[1].effective = effective >> 32; 295 capdata[0].permitted = permitted; 296 capdata[1].permitted = permitted >> 32; 297 capdata[0].inheritable = inheritable; 298 capdata[1].inheritable = inheritable >> 32; 299 300 if (capset(&capheader, &capdata[0]) == -1) { 301 ALOGE("capset(perm=%" PRIx64 ", eff=%" PRIx64 ", inh=%" PRIx64 ") failed: %s", permitted, 302 effective, inheritable, strerror(errno)); 303 RuntimeAbort(env, __LINE__, "capset failed"); 304 } 305} 306 307static void SetSchedulerPolicy(JNIEnv* env) { 308 errno = -set_sched_policy(0, SP_DEFAULT); 309 if (errno != 0) { 310 ALOGE("set_sched_policy(0, SP_DEFAULT) failed"); 311 RuntimeAbort(env, __LINE__, "set_sched_policy(0, SP_DEFAULT) failed"); 312 } 313} 314 315static int UnmountTree(const char* path) { 316 size_t path_len = strlen(path); 317 318 FILE* fp = setmntent("/proc/mounts", "r"); 319 if (fp == NULL) { 320 ALOGE("Error opening /proc/mounts: %s", strerror(errno)); 321 return -errno; 322 } 323 324 // Some volumes can be stacked on each other, so force unmount in 325 // reverse order to give us the best chance of success. 326 std::list<std::string> toUnmount; 327 mntent* mentry; 328 while ((mentry = getmntent(fp)) != NULL) { 329 if (strncmp(mentry->mnt_dir, path, path_len) == 0) { 330 toUnmount.push_front(std::string(mentry->mnt_dir)); 331 } 332 } 333 endmntent(fp); 334 335 for (auto path : toUnmount) { 336 if (umount2(path.c_str(), MNT_DETACH)) { 337 ALOGW("Failed to unmount %s: %s", path.c_str(), strerror(errno)); 338 } 339 } 340 return 0; 341} 342 343// Create a private mount namespace and bind mount appropriate emulated 344// storage for the given user. 345static bool MountEmulatedStorage(uid_t uid, jint mount_mode, 346 bool force_mount_namespace) { 347 // See storage config details at http://source.android.com/tech/storage/ 348 349 String8 storageSource; 350 if (mount_mode == MOUNT_EXTERNAL_DEFAULT) { 351 storageSource = "/mnt/runtime/default"; 352 } else if (mount_mode == MOUNT_EXTERNAL_READ) { 353 storageSource = "/mnt/runtime/read"; 354 } else if (mount_mode == MOUNT_EXTERNAL_WRITE) { 355 storageSource = "/mnt/runtime/write"; 356 } else if (!force_mount_namespace) { 357 // Sane default of no storage visible 358 return true; 359 } 360 361 // Create a second private mount namespace for our process 362 if (unshare(CLONE_NEWNS) == -1) { 363 ALOGW("Failed to unshare(): %s", strerror(errno)); 364 return false; 365 } 366 367 if (TEMP_FAILURE_RETRY(mount(storageSource.string(), "/storage", 368 NULL, MS_BIND | MS_REC | MS_SLAVE, NULL)) == -1) { 369 ALOGW("Failed to mount %s to /storage: %s", storageSource.string(), strerror(errno)); 370 return false; 371 } 372 373 // Mount user-specific symlink helper into place 374 userid_t user_id = multiuser_get_user_id(uid); 375 const String8 userSource(String8::format("/mnt/user/%d", user_id)); 376 if (fs_prepare_dir(userSource.string(), 0751, 0, 0) == -1) { 377 return false; 378 } 379 if (TEMP_FAILURE_RETRY(mount(userSource.string(), "/storage/self", 380 NULL, MS_BIND, NULL)) == -1) { 381 ALOGW("Failed to mount %s to /storage/self: %s", userSource.string(), strerror(errno)); 382 return false; 383 } 384 385 return true; 386} 387 388static bool NeedsNoRandomizeWorkaround() { 389#if !defined(__arm__) 390 return false; 391#else 392 int major; 393 int minor; 394 struct utsname uts; 395 if (uname(&uts) == -1) { 396 return false; 397 } 398 399 if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) { 400 return false; 401 } 402 403 // Kernels before 3.4.* need the workaround. 404 return (major < 3) || ((major == 3) && (minor < 4)); 405#endif 406} 407 408// Utility to close down the Zygote socket file descriptors while 409// the child is still running as root with Zygote's privileges. Each 410// descriptor (if any) is closed via dup2(), replacing it with a valid 411// (open) descriptor to /dev/null. 412 413static void DetachDescriptors(JNIEnv* env, jintArray fdsToClose) { 414 if (!fdsToClose) { 415 return; 416 } 417 jsize count = env->GetArrayLength(fdsToClose); 418 ScopedIntArrayRO ar(env, fdsToClose); 419 if (ar.get() == NULL) { 420 RuntimeAbort(env, __LINE__, "Bad fd array"); 421 } 422 jsize i; 423 int devnull; 424 for (i = 0; i < count; i++) { 425 devnull = open("/dev/null", O_RDWR); 426 if (devnull < 0) { 427 ALOGE("Failed to open /dev/null: %s", strerror(errno)); 428 RuntimeAbort(env, __LINE__, "Failed to open /dev/null"); 429 continue; 430 } 431 ALOGV("Switching descriptor %d to /dev/null: %s", ar[i], strerror(errno)); 432 if (dup2(devnull, ar[i]) < 0) { 433 ALOGE("Failed dup2() on descriptor %d: %s", ar[i], strerror(errno)); 434 RuntimeAbort(env, __LINE__, "Failed dup2()"); 435 } 436 close(devnull); 437 } 438} 439 440void SetThreadName(const char* thread_name) { 441 bool hasAt = false; 442 bool hasDot = false; 443 const char* s = thread_name; 444 while (*s) { 445 if (*s == '.') { 446 hasDot = true; 447 } else if (*s == '@') { 448 hasAt = true; 449 } 450 s++; 451 } 452 const int len = s - thread_name; 453 if (len < 15 || hasAt || !hasDot) { 454 s = thread_name; 455 } else { 456 s = thread_name + len - 15; 457 } 458 // pthread_setname_np fails rather than truncating long strings. 459 char buf[16]; // MAX_TASK_COMM_LEN=16 is hard-coded into bionic 460 strlcpy(buf, s, sizeof(buf)-1); 461 errno = pthread_setname_np(pthread_self(), buf); 462 if (errno != 0) { 463 ALOGW("Unable to set the name of current thread to '%s': %s", buf, strerror(errno)); 464 } 465} 466 467// The list of open zygote file descriptors. 468static FileDescriptorTable* gOpenFdTable = NULL; 469 470static void FillFileDescriptorVector(JNIEnv* env, 471 jintArray java_fds, 472 std::vector<int>* fds) { 473 CHECK(fds != nullptr); 474 if (java_fds != nullptr) { 475 ScopedIntArrayRO ar(env, java_fds); 476 if (ar.get() == nullptr) { 477 RuntimeAbort(env, __LINE__, "Bad fd array"); 478 } 479 fds->reserve(ar.size()); 480 for (size_t i = 0; i < ar.size(); ++i) { 481 fds->push_back(ar[i]); 482 } 483 } 484} 485 486// Utility routine to fork zygote and specialize the child process. 487static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids, 488 jint debug_flags, jobjectArray javaRlimits, 489 jlong permittedCapabilities, jlong effectiveCapabilities, 490 jint mount_external, 491 jstring java_se_info, jstring java_se_name, 492 bool is_system_server, jintArray fdsToClose, 493 jintArray fdsToIgnore, 494 jstring instructionSet, jstring dataDir) { 495 SetSigChldHandler(); 496 497 sigset_t sigchld; 498 sigemptyset(&sigchld); 499 sigaddset(&sigchld, SIGCHLD); 500 501 // Temporarily block SIGCHLD during forks. The SIGCHLD handler might 502 // log, which would result in the logging FDs we close being reopened. 503 // This would cause failures because the FDs are not whitelisted. 504 // 505 // Note that the zygote process is single threaded at this point. 506 if (sigprocmask(SIG_BLOCK, &sigchld, nullptr) == -1) { 507 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 508 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_BLOCK, { SIGCHLD }) failed."); 509 } 510 511 // Close any logging related FDs before we start evaluating the list of 512 // file descriptors. 513 __android_log_close(); 514 515 // If this is the first fork for this zygote, create the open FD table. 516 // If it isn't, we just need to check whether the list of open files has 517 // changed (and it shouldn't in the normal case). 518 std::vector<int> fds_to_ignore; 519 FillFileDescriptorVector(env, fdsToIgnore, &fds_to_ignore); 520 if (gOpenFdTable == NULL) { 521 gOpenFdTable = FileDescriptorTable::Create(fds_to_ignore); 522 if (gOpenFdTable == NULL) { 523 RuntimeAbort(env, __LINE__, "Unable to construct file descriptor table."); 524 } 525 } else if (!gOpenFdTable->Restat(fds_to_ignore)) { 526 RuntimeAbort(env, __LINE__, "Unable to restat file descriptor table."); 527 } 528 529 ResetNicePriority(env); 530 531 pid_t pid = fork(); 532 533 if (pid == 0) { 534 // The child process. 535 gMallocLeakZygoteChild = 1; 536 537 // Clean up any descriptors which must be closed immediately 538 DetachDescriptors(env, fdsToClose); 539 540 // Re-open all remaining open file descriptors so that they aren't shared 541 // with the zygote across a fork. 542 if (!gOpenFdTable->ReopenOrDetach()) { 543 RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors."); 544 } 545 546 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 547 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 548 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 549 } 550 551 // Keep capabilities across UID change, unless we're staying root. 552 if (uid != 0) { 553 EnableKeepCapabilities(env); 554 } 555 556 SetInheritable(env, permittedCapabilities); 557 DropCapabilitiesBoundingSet(env); 558 559 bool use_native_bridge = !is_system_server && (instructionSet != NULL) 560 && android::NativeBridgeAvailable(); 561 if (use_native_bridge) { 562 ScopedUtfChars isa_string(env, instructionSet); 563 use_native_bridge = android::NeedsNativeBridge(isa_string.c_str()); 564 } 565 if (use_native_bridge && dataDir == NULL) { 566 // dataDir should never be null if we need to use a native bridge. 567 // In general, dataDir will never be null for normal applications. It can only happen in 568 // special cases (for isolated processes which are not associated with any app). These are 569 // launched by the framework and should not be emulated anyway. 570 use_native_bridge = false; 571 ALOGW("Native bridge will not be used because dataDir == NULL."); 572 } 573 574 if (!MountEmulatedStorage(uid, mount_external, use_native_bridge)) { 575 ALOGW("Failed to mount emulated storage: %s", strerror(errno)); 576 if (errno == ENOTCONN || errno == EROFS) { 577 // When device is actively encrypting, we get ENOTCONN here 578 // since FUSE was mounted before the framework restarted. 579 // When encrypted device is booting, we get EROFS since 580 // FUSE hasn't been created yet by init. 581 // In either case, continue without external storage. 582 } else { 583 RuntimeAbort(env, __LINE__, "Cannot continue without emulated storage"); 584 } 585 } 586 587 if (!is_system_server) { 588 int rc = createProcessGroup(uid, getpid()); 589 if (rc != 0) { 590 if (rc == -EROFS) { 591 ALOGW("createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?"); 592 } else { 593 ALOGE("createProcessGroup(%d, %d) failed: %s", uid, pid, strerror(-rc)); 594 } 595 } 596 } 597 598 SetGids(env, javaGids); 599 600 SetRLimits(env, javaRlimits); 601 602 if (use_native_bridge) { 603 ScopedUtfChars isa_string(env, instructionSet); 604 ScopedUtfChars data_dir(env, dataDir); 605 android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str()); 606 } 607 608 int rc = setresgid(gid, gid, gid); 609 if (rc == -1) { 610 ALOGE("setresgid(%d) failed: %s", gid, strerror(errno)); 611 RuntimeAbort(env, __LINE__, "setresgid failed"); 612 } 613 614 rc = setresuid(uid, uid, uid); 615 if (rc == -1) { 616 ALOGE("setresuid(%d) failed: %s", uid, strerror(errno)); 617 RuntimeAbort(env, __LINE__, "setresuid failed"); 618 } 619 620 if (NeedsNoRandomizeWorkaround()) { 621 // Work around ARM kernel ASLR lossage (http://b/5817320). 622 int old_personality = personality(0xffffffff); 623 int new_personality = personality(old_personality | ADDR_NO_RANDOMIZE); 624 if (new_personality == -1) { 625 ALOGW("personality(%d) failed: %s", new_personality, strerror(errno)); 626 } 627 } 628 629 SetCapabilities(env, permittedCapabilities, effectiveCapabilities, permittedCapabilities); 630 631 SetSchedulerPolicy(env); 632 633 const char* se_info_c_str = NULL; 634 ScopedUtfChars* se_info = NULL; 635 if (java_se_info != NULL) { 636 se_info = new ScopedUtfChars(env, java_se_info); 637 se_info_c_str = se_info->c_str(); 638 if (se_info_c_str == NULL) { 639 RuntimeAbort(env, __LINE__, "se_info_c_str == NULL"); 640 } 641 } 642 const char* se_name_c_str = NULL; 643 ScopedUtfChars* se_name = NULL; 644 if (java_se_name != NULL) { 645 se_name = new ScopedUtfChars(env, java_se_name); 646 se_name_c_str = se_name->c_str(); 647 if (se_name_c_str == NULL) { 648 RuntimeAbort(env, __LINE__, "se_name_c_str == NULL"); 649 } 650 } 651 rc = selinux_android_setcontext(uid, is_system_server, se_info_c_str, se_name_c_str); 652 if (rc == -1) { 653 ALOGE("selinux_android_setcontext(%d, %d, \"%s\", \"%s\") failed", uid, 654 is_system_server, se_info_c_str, se_name_c_str); 655 RuntimeAbort(env, __LINE__, "selinux_android_setcontext failed"); 656 } 657 658 // Make it easier to debug audit logs by setting the main thread's name to the 659 // nice name rather than "app_process". 660 if (se_info_c_str == NULL && is_system_server) { 661 se_name_c_str = "system_server"; 662 } 663 if (se_info_c_str != NULL) { 664 SetThreadName(se_name_c_str); 665 } 666 667 delete se_info; 668 delete se_name; 669 670 UnsetSigChldHandler(); 671 672 env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, debug_flags, 673 is_system_server, instructionSet); 674 if (env->ExceptionCheck()) { 675 RuntimeAbort(env, __LINE__, "Error calling post fork hooks."); 676 } 677 } else if (pid > 0) { 678 // the parent process 679 680 // We blocked SIGCHLD prior to a fork, we unblock it here. 681 if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) { 682 ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)); 683 RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed."); 684 } 685 } 686 return pid; 687} 688} // anonymous namespace 689 690namespace android { 691 692static jint com_android_internal_os_Zygote_nativeForkAndSpecialize( 693 JNIEnv* env, jclass, jint uid, jint gid, jintArray gids, 694 jint debug_flags, jobjectArray rlimits, 695 jint mount_external, jstring se_info, jstring se_name, 696 jintArray fdsToClose, 697 jintArray fdsToIgnore, 698 jstring instructionSet, jstring appDataDir) { 699 jlong capabilities = 0; 700 701 // Grant CAP_WAKE_ALARM to the Bluetooth process. 702 // Additionally, allow bluetooth to open packet sockets so it can start the DHCP client. 703 // TODO: consider making such functionality an RPC to netd. 704 if (multiuser_get_app_id(uid) == AID_BLUETOOTH) { 705 capabilities |= (1LL << CAP_WAKE_ALARM); 706 capabilities |= (1LL << CAP_NET_RAW); 707 capabilities |= (1LL << CAP_NET_BIND_SERVICE); 708 } 709 710 // Grant CAP_BLOCK_SUSPEND to processes that belong to GID "wakelock" 711 bool gid_wakelock_found = false; 712 if (gid == AID_WAKELOCK) { 713 gid_wakelock_found = true; 714 } else if (gids != NULL) { 715 jsize gids_num = env->GetArrayLength(gids); 716 ScopedIntArrayRO ar(env, gids); 717 if (ar.get() == NULL) { 718 RuntimeAbort(env, __LINE__, "Bad gids array"); 719 } 720 for (int i = 0; i < gids_num; i++) { 721 if (ar[i] == AID_WAKELOCK) { 722 gid_wakelock_found = true; 723 break; 724 } 725 } 726 } 727 if (gid_wakelock_found) { 728 capabilities |= (1LL << CAP_BLOCK_SUSPEND); 729 } 730 731 return ForkAndSpecializeCommon(env, uid, gid, gids, debug_flags, 732 rlimits, capabilities, capabilities, mount_external, se_info, 733 se_name, false, fdsToClose, fdsToIgnore, instructionSet, appDataDir); 734} 735 736static jint com_android_internal_os_Zygote_nativeForkSystemServer( 737 JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids, 738 jint debug_flags, jobjectArray rlimits, jlong permittedCapabilities, 739 jlong effectiveCapabilities) { 740 pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids, 741 debug_flags, rlimits, 742 permittedCapabilities, effectiveCapabilities, 743 MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true, NULL, 744 NULL, NULL, NULL); 745 if (pid > 0) { 746 // The zygote process checks whether the child process has died or not. 747 ALOGI("System server process %d has been created", pid); 748 gSystemServerPid = pid; 749 // There is a slight window that the system server process has crashed 750 // but it went unnoticed because we haven't published its pid yet. So 751 // we recheck here just to make sure that all is well. 752 int status; 753 if (waitpid(pid, &status, WNOHANG) == pid) { 754 ALOGE("System server process %d has died. Restarting Zygote!", pid); 755 RuntimeAbort(env, __LINE__, "System server process has died. Restarting Zygote!"); 756 } 757 } 758 return pid; 759} 760 761static void com_android_internal_os_Zygote_nativeAllowFileAcrossFork( 762 JNIEnv* env, jclass, jstring path) { 763 ScopedUtfChars path_native(env, path); 764 const char* path_cstr = path_native.c_str(); 765 if (!path_cstr) { 766 RuntimeAbort(env, __LINE__, "path_cstr == NULL"); 767 } 768 FileDescriptorWhitelist::Get()->Allow(path_cstr); 769} 770 771static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) { 772 // Zygote process unmount root storage space initially before every child processes are forked. 773 // Every forked child processes (include SystemServer) only mount their own root storage space 774 // and no need unmount storage operation in MountEmulatedStorage method. 775 // Zygote process does not utilize root storage spaces and unshares its mount namespace below. 776 777 // See storage config details at http://source.android.com/tech/storage/ 778 // Create private mount namespace shared by all children 779 if (unshare(CLONE_NEWNS) == -1) { 780 RuntimeAbort(env, __LINE__, "Failed to unshare()"); 781 return; 782 } 783 784 // Mark rootfs as being a slave so that changes from default 785 // namespace only flow into our children. 786 if (mount("rootfs", "/", nullptr, (MS_SLAVE | MS_REC), nullptr) == -1) { 787 RuntimeAbort(env, __LINE__, "Failed to mount() rootfs as MS_SLAVE"); 788 return; 789 } 790 791 // Create a staging tmpfs that is shared by our children; they will 792 // bind mount storage into their respective private namespaces, which 793 // are isolated from each other. 794 const char* target_base = getenv("EMULATED_STORAGE_TARGET"); 795 if (target_base != nullptr) { 796#define STRINGIFY_UID(x) __STRING(x) 797 if (mount("tmpfs", target_base, "tmpfs", MS_NOSUID | MS_NODEV, 798 "uid=0,gid=" STRINGIFY_UID(AID_SDCARD_R) ",mode=0751") == -1) { 799 ALOGE("Failed to mount tmpfs to %s", target_base); 800 RuntimeAbort(env, __LINE__, "Failed to mount tmpfs"); 801 return; 802 } 803#undef STRINGIFY_UID 804 } 805 806 UnmountTree("/storage"); 807} 808 809static const JNINativeMethod gMethods[] = { 810 { "nativeForkAndSpecialize", 811 "(II[II[[IILjava/lang/String;Ljava/lang/String;[I[ILjava/lang/String;Ljava/lang/String;)I", 812 (void *) com_android_internal_os_Zygote_nativeForkAndSpecialize }, 813 { "nativeForkSystemServer", "(II[II[[IJJ)I", 814 (void *) com_android_internal_os_Zygote_nativeForkSystemServer }, 815 { "nativeAllowFileAcrossFork", "(Ljava/lang/String;)V", 816 (void *) com_android_internal_os_Zygote_nativeAllowFileAcrossFork }, 817 { "nativeUnmountStorageOnInit", "()V", 818 (void *) com_android_internal_os_Zygote_nativeUnmountStorageOnInit } 819}; 820 821int register_com_android_internal_os_Zygote(JNIEnv* env) { 822 gZygoteClass = MakeGlobalRefOrDie(env, FindClassOrDie(env, kZygoteClassName)); 823 gCallPostForkChildHooks = GetStaticMethodIDOrDie(env, gZygoteClass, "callPostForkChildHooks", 824 "(IZLjava/lang/String;)V"); 825 826 return RegisterMethodsOrDie(env, "com/android/internal/os/Zygote", gMethods, NELEM(gMethods)); 827} 828} // namespace android 829