#define LOG_TAG "Zygote"
+#include <sstream>
+
// sys/mount.h has to come before linux/fs.h due to redefinition of MS_RDONLY, MS_BIND, etc
#include <sys/mount.h>
#include <linux/fs.h>
+#include <list>
+#include <string>
+
#include <fcntl.h>
#include <grp.h>
#include <inttypes.h>
+#include <mntent.h>
#include <paths.h>
#include <signal.h>
#include <stdlib.h>
#include "ScopedLocalRef.h"
#include "ScopedPrimitiveArray.h"
#include "ScopedUtfChars.h"
+#include "fd_utils-inl.h"
#include "nativebridge/native_bridge.h"
// Must match values in com.android.internal.os.Zygote.
enum MountExternalKind {
MOUNT_EXTERNAL_NONE = 0,
- MOUNT_EXTERNAL_SINGLEUSER = 1,
- MOUNT_EXTERNAL_MULTIUSER = 2,
- MOUNT_EXTERNAL_MULTIUSER_ALL = 3,
+ MOUNT_EXTERNAL_DEFAULT = 1,
+ MOUNT_EXTERNAL_READ = 2,
+ MOUNT_EXTERNAL_WRITE = 3,
};
static void RuntimeAbort(JNIEnv* env) {
env->FatalError("RuntimeAbort");
}
+static void RuntimeAbort(JNIEnv* env, int line, const char* msg) {
+ std::ostringstream oss;
+ oss << __FILE__ << ":" << line << ": " << msg;
+ env->FatalError(oss.str().c_str());
+}
+
// This signal handler is for zygote mode, since the zygote must reap its children
static void SigChldHandler(int /*signal_number*/) {
pid_t pid;
int status;
+ // It's necessary to save and restore the errno during this function.
+ // Since errno is stored per thread, changing it here modifies the errno
+ // on the thread on which this signal handler executes. If a signal occurs
+ // between a call and an errno check, it's possible to get the errno set
+ // here.
+ // See b/23572286 for extra information.
+ int saved_errno = errno;
+
while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
// Log process-death status that we care about. In general it is
// not safe to call LOG(...) from a signal handler because of
if (pid < 0 && errno != ECHILD) {
ALOGW("Zygote SIGCHLD error in waitpid: %s", strerror(errno));
}
+
+ errno = saved_errno;
}
// Configures the SIGCHLD handler for the zygote process. This is configured
}
}
-// Create a private mount namespace and bind mount appropriate emulated
-// storage for the given user.
-static bool MountEmulatedStorage(uid_t uid, jint mount_mode, bool force_mount_namespace) {
- if (mount_mode == MOUNT_EXTERNAL_NONE && !force_mount_namespace) {
- return true;
- }
-
- // Create a second private mount namespace for our process
- if (unshare(CLONE_NEWNS) == -1) {
- ALOGW("Failed to unshare(): %s", strerror(errno));
- return false;
- }
+static int UnmountTree(const char* path) {
+ size_t path_len = strlen(path);
- if (mount_mode == MOUNT_EXTERNAL_NONE) {
- return true;
- }
-
- // See storage config details at http://source.android.com/tech/storage/
- userid_t user_id = multiuser_get_user_id(uid);
+ FILE* fp = setmntent("/proc/mounts", "r");
+ if (fp == NULL) {
+ ALOGE("Error opening /proc/mounts: %s", strerror(errno));
+ return -errno;
+ }
- // Create bind mounts to expose external storage
- if (mount_mode == MOUNT_EXTERNAL_MULTIUSER || mount_mode == MOUNT_EXTERNAL_MULTIUSER_ALL) {
- // These paths must already be created by init.rc
- const char* source = getenv("EMULATED_STORAGE_SOURCE");
- const char* target = getenv("EMULATED_STORAGE_TARGET");
- const char* legacy = getenv("EXTERNAL_STORAGE");
- if (source == NULL || target == NULL || legacy == NULL) {
- ALOGW("Storage environment undefined; unable to provide external storage");
- return false;
+ // Some volumes can be stacked on each other, so force unmount in
+ // reverse order to give us the best chance of success.
+ std::list<std::string> toUnmount;
+ mntent* mentry;
+ while ((mentry = getmntent(fp)) != NULL) {
+ if (strncmp(mentry->mnt_dir, path, path_len) == 0) {
+ toUnmount.push_front(std::string(mentry->mnt_dir));
+ }
}
+ endmntent(fp);
- // Prepare source paths
+ for (auto path : toUnmount) {
+ if (umount2(path.c_str(), MNT_DETACH)) {
+ ALOGW("Failed to unmount %s: %s", path.c_str(), strerror(errno));
+ }
+ }
+ return 0;
+}
- // /mnt/shell/emulated/0
- const String8 source_user(String8::format("%s/%d", source, user_id));
- // /storage/emulated/0
- const String8 target_user(String8::format("%s/%d", target, user_id));
+// Create a private mount namespace and bind mount appropriate emulated
+// storage for the given user.
+static bool MountEmulatedStorage(uid_t uid, jint mount_mode,
+ bool force_mount_namespace) {
+ // See storage config details at http://source.android.com/tech/storage/
- if (fs_prepare_dir(source_user.string(), 0000, 0, 0) == -1
- || fs_prepare_dir(target_user.string(), 0000, 0, 0) == -1) {
- return false;
+ // Create a second private mount namespace for our process
+ if (unshare(CLONE_NEWNS) == -1) {
+ ALOGW("Failed to unshare(): %s", strerror(errno));
+ return false;
}
- if (mount_mode == MOUNT_EXTERNAL_MULTIUSER_ALL) {
- // Mount entire external storage tree for all users
- if (TEMP_FAILURE_RETRY(mount(source, target, NULL, MS_BIND, NULL)) == -1) {
- ALOGW("Failed to mount %s to %s: %s", source, target, strerror(errno));
- return false;
- }
+ String8 storageSource;
+ if (mount_mode == MOUNT_EXTERNAL_DEFAULT) {
+ storageSource = "/mnt/runtime/default";
+ } else if (mount_mode == MOUNT_EXTERNAL_READ) {
+ storageSource = "/mnt/runtime/read";
+ } else if (mount_mode == MOUNT_EXTERNAL_WRITE) {
+ storageSource = "/mnt/runtime/write";
} else {
- // Only mount user-specific external storage
- if (TEMP_FAILURE_RETRY(mount(source_user.string(), target_user.string(), NULL,
- MS_BIND, NULL)) == -1) {
- ALOGW("Failed to mount %s to %s: %s", source_user.string(), target_user.string(),
- strerror(errno));
+ // Sane default of no storage visible
+ return true;
+ }
+ if (TEMP_FAILURE_RETRY(mount(storageSource.string(), "/storage",
+ NULL, MS_BIND | MS_REC | MS_SLAVE, NULL)) == -1) {
+ ALOGW("Failed to mount %s to /storage: %s", storageSource.string(), strerror(errno));
return false;
- }
}
- if (fs_prepare_dir(legacy, 0000, 0, 0) == -1) {
+ // Mount user-specific symlink helper into place
+ userid_t user_id = multiuser_get_user_id(uid);
+ const String8 userSource(String8::format("/mnt/user/%d", user_id));
+ if (fs_prepare_dir(userSource.string(), 0751, 0, 0) == -1) {
return false;
}
-
- // Finally, mount user-specific path into place for legacy users
- if (TEMP_FAILURE_RETRY(
- mount(target_user.string(), legacy, NULL, MS_BIND | MS_REC, NULL)) == -1) {
- ALOGW("Failed to mount %s to %s: %s", target_user.string(), legacy, strerror(errno));
- return false;
+ if (TEMP_FAILURE_RETRY(mount(userSource.string(), "/storage/self",
+ NULL, MS_BIND, NULL)) == -1) {
+ ALOGW("Failed to mount %s to /storage/self: %s", userSource.string(), strerror(errno));
+ return false;
}
- } else {
- ALOGW("Mount mode %d unsupported", mount_mode);
- return false;
- }
- return true;
+ return true;
}
static bool NeedsNoRandomizeWorkaround() {
}
}
+#ifdef ENABLE_SCHED_BOOST
+static void SetForkLoad(bool boost) {
+ // set scheduler knob to boost forked processes
+ pid_t currentPid = getpid();
+ // fits at most "/proc/XXXXXXX/sched_init_task_load\0"
+ char schedPath[35];
+ snprintf(schedPath, sizeof(schedPath), "/proc/%u/sched_init_task_load", currentPid);
+ int schedBoostFile = open(schedPath, O_WRONLY);
+ if (schedBoostFile < 0) {
+ ALOGW("Unable to set zygote scheduler boost");
+ return;
+ }
+ if (boost) {
+ write(schedBoostFile, "100\0", 4);
+ } else {
+ write(schedBoostFile, "0\0", 2);
+ }
+ close(schedBoostFile);
+}
+#endif
+
+// The list of open zygote file descriptors.
+static FileDescriptorTable* gOpenFdTable = NULL;
+
// Utility routine to fork zygote and specialize the child process.
static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids,
jint debug_flags, jobjectArray javaRlimits,
jstring instructionSet, jstring dataDir) {
SetSigChldHandler();
+#ifdef ENABLE_SCHED_BOOST
+ SetForkLoad(true);
+#endif
+
+ sigset_t sigchld;
+ sigemptyset(&sigchld);
+ sigaddset(&sigchld, SIGCHLD);
+
+ // Temporarily block SIGCHLD during forks. The SIGCHLD handler might
+ // log, which would result in the logging FDs we close being reopened.
+ // This would cause failures because the FDs are not whitelisted.
+ //
+ // Note that the zygote process is single threaded at this point.
+ if (sigprocmask(SIG_BLOCK, &sigchld, NULL) == -1) {
+ ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno));
+ RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_BLOCK, { SIGCHLD }) failed.");
+ }
+
+ // Close any logging related FDs before we start evaluating the list of
+ // file descriptors.
+ __android_log_close();
+
+ // If this is the first fork for this zygote, create the open FD table.
+ // If it isn't, we just need to check whether the list of open files has
+ // changed (and it shouldn't in the normal case).
+ if (gOpenFdTable == NULL) {
+ gOpenFdTable = FileDescriptorTable::Create();
+ if (gOpenFdTable == NULL) {
+ RuntimeAbort(env, __LINE__, "Unable to construct file descriptor table.");
+ }
+ } else if (!gOpenFdTable->Restat()) {
+ RuntimeAbort(env, __LINE__, "Unable to restat file descriptor table.");
+ }
+
pid_t pid = fork();
if (pid == 0) {
// Clean up any descriptors which must be closed immediately
DetachDescriptors(env, fdsToClose);
+ // Re-open all remaining open file descriptors so that they aren't shared
+ // with the zygote across a fork.
+ if (!gOpenFdTable->ReopenOrDetach()) {
+ RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors.");
+ }
+
+ if (sigprocmask(SIG_UNBLOCK, &sigchld, NULL) == -1) {
+ ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno));
+ RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed.");
+ }
+
// Keep capabilities across UID change, unless we're staying root.
if (uid != 0) {
EnableKeepCapabilities(env);
}
DropCapabilitiesBoundingSet(env);
-
+#ifdef _COMPATIBILITY_ENHANCEMENT_PACKAGE_
+ bool use_native_bridge = !is_system_server && android::NativeBridgeAvailable();
+#else
bool use_native_bridge = !is_system_server && (instructionSet != NULL)
- && android::NativeBridgeAvailable();
+ && android::NativeBridgeAvailable();
+#endif
if (use_native_bridge) {
+#ifdef _COMPATIBILITY_ENHANCEMENT_PACKAGE_
+ if (instructionSet != NULL) {
+ ScopedUtfChars isa_string(env, instructionSet);
+ use_native_bridge = android::NeedsNativeBridge(isa_string.c_str());
+ } else {
+ use_native_bridge = android::NeedsNativeBridge(NULL);
+ instructionSet = env->NewStringUTF("arm"
+#ifdef __LP64__
+ "64"
+#endif
+ );
+ }
+#else
ScopedUtfChars isa_string(env, instructionSet);
use_native_bridge = android::NeedsNativeBridge(isa_string.c_str());
- }
+#endif
+ }
+
+#ifndef _COMPATIBILITY_ENHANCEMENT_PACKAGE_
if (use_native_bridge && dataDir == NULL) {
- // dataDir should never be null if we need to use a native bridge.
- // In general, dataDir will never be null for normal applications. It can only happen in
- // special cases (for isolated processes which are not associated with any app). These are
- // launched by the framework and should not be emulated anyway.
- use_native_bridge = false;
- ALOGW("Native bridge will not be used because dataDir == NULL.");
+ // dataDir should never be null if we need to use a native bridge.
+ // In general, dataDir will never be null for normal applications. It can only happen in
+ // special cases (for isolated processes which are not associated with any app). These are
+ // launched by the framework and should not be emulated anyway.
+ use_native_bridge = false;
+ ALOGW("Native bridge will not be used because dataDir == NULL.");
}
+#endif
if (!MountEmulatedStorage(uid, mount_external, use_native_bridge)) {
ALOGW("Failed to mount emulated storage: %s", strerror(errno));
if (use_native_bridge) {
ScopedUtfChars isa_string(env, instructionSet);
- ScopedUtfChars data_dir(env, dataDir);
- android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str());
+#ifdef _COMPATIBILITY_ENHANCEMENT_PACKAGE_
+ if (dataDir != NULL) {
+#endif
+ ScopedUtfChars data_dir(env, dataDir);
+ android::PreInitializeNativeBridge(data_dir.c_str(), isa_string.c_str());
+#ifdef _COMPATIBILITY_ENHANCEMENT_PACKAGE_
+ } else {
+ android::PreInitializeNativeBridge(NULL, isa_string.c_str());
+ }
+#endif
}
int rc = setresgid(gid, gid, gid);
}
} else if (pid > 0) {
// the parent process
+
+ // We blocked SIGCHLD prior to a fork, we unblock it here.
+ if (sigprocmask(SIG_UNBLOCK, &sigchld, NULL) == -1) {
+ ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno));
+ RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed.");
+ }
}
return pid;
}
pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids,
debug_flags, rlimits,
permittedCapabilities, effectiveCapabilities,
- MOUNT_EXTERNAL_NONE, NULL, NULL, true, NULL,
+ MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true, NULL,
NULL, NULL);
if (pid > 0) {
// The zygote process checks whether the child process has died or not.
return pid;
}
+static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) {
+ // Zygote process unmount root storage space initially before every child processes are forked.
+ // Every forked child processes (include SystemServer) only mount their own root storage space
+ // And no need unmount storage operation in MountEmulatedStorage method.
+ // Zygote process does not utilize root storage spaces and unshared its mount namespace from the ART.
+
+ UnmountTree("/storage");
+ return;
+}
+
static JNINativeMethod gMethods[] = {
{ "nativeForkAndSpecialize",
"(II[II[[IILjava/lang/String;Ljava/lang/String;[ILjava/lang/String;Ljava/lang/String;)I",
(void *) com_android_internal_os_Zygote_nativeForkAndSpecialize },
{ "nativeForkSystemServer", "(II[II[[IJJ)I",
- (void *) com_android_internal_os_Zygote_nativeForkSystemServer }
+ (void *) com_android_internal_os_Zygote_nativeForkSystemServer },
+ { "nativeUnmountStorageOnInit", "()V",
+ (void *) com_android_internal_os_Zygote_nativeUnmountStorageOnInit }
};
int register_com_android_internal_os_Zygote(JNIEnv* env) {
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