Fix fatal error caused by not whitelisted files opened in zygote

Bridge/src/main/java/com/elderdrivers/riru/xposed/Main.java

@@ -99,4 +99,10 @@ public class Main implements KeepAll {
     private static native void init(int SDK_version);
 
     public static native String getInstallerPkgName();
+
+    // prevent from fatal error caused by holding not whitelisted file descriptors when fork zygote
+    // https://github.com/rovo89/Xposed/commit/b3ba245ad04cd485699fb1d2ebde7117e58214ff
+    public static native void closeFilesBeforeForkNative();
+
+    public static native void reopenFilesAfterForkNative();
 }

Bridge/src/main/java/com/elderdrivers/riru/xposed/proxy/yahfa/NormalProxy.java

@@ -20,10 +20,12 @@ public class NormalProxy {
         Router.installBootstrapHooks(false);
         // load modules for secondary zygote
         Router.loadModulesSafely();
+        Main.closeFilesBeforeForkNative();
     }
 
     public static void forkAndSpecializePost(int pid, String appDataDir) {
         // TODO consider processes without forkAndSpecializePost called
+        Main.reopenFilesAfterForkNative();
         Router.onEnterChildProcess();
         DynamicBridge.onForkPost();
         if (ConfigManager.isDynamicModulesMode()) {
@@ -44,10 +46,12 @@ public class NormalProxy {
         // because if not global hooks installed in initZygote might not be
         // propagated to processes not forked via forkAndSpecialize
         Router.loadModulesSafely();
+        Main.closeFilesBeforeForkNative();
     }
 
     public static void forkSystemServerPost(int pid) {
         // in system_server process
+        Main.reopenFilesAfterForkNative();
         Router.onEnterChildProcess();
     }
 

Bridge/src/main/java/de/robv/android/xposed/XposedInit.java

@@ -1,6 +1,5 @@
 package de.robv.android.xposed;
 
-import android.annotation.SuppressLint;
 import android.app.AndroidAppHelper;
 import android.os.Build;
 import android.text.TextUtils;
@@ -27,7 +26,6 @@ import dalvik.system.PathClassLoader;
 import de.robv.android.xposed.services.BaseService;
 
 import static com.elderdrivers.riru.xposed.config.InstallerChooser.INSTALLER_DATA_BASE_DIR;
-import static com.elderdrivers.riru.xposed.config.InstallerChooser.INSTALLER_PACKAGE_NAME;
 import static com.elderdrivers.riru.xposed.entry.hooker.XposedBlackListHooker.BLACK_LIST_PACKAGE_NAME;
 import static de.robv.android.xposed.XposedHelpers.closeSilently;
 import static de.robv.android.xposed.XposedHelpers.findClass;
@@ -123,12 +121,10 @@ public final class XposedInit {
      * in <code>assets/xposed_init</code>.
      */
     private static void loadModule(String apk, ClassLoader topClassLoader) {
-        if (BuildConfig.DEBUG)
-            Log.i(TAG, "Loading modules from " + apk);
+        Log.i(TAG, "Loading modules from " + apk);
 
         if (!TextUtils.isEmpty(apk) && apk.contains(BLACK_LIST_PACKAGE_NAME)) {
-            if (BuildConfig.DEBUG)
-                Log.i(TAG, "We are going to take over black list's job...");
+            Log.i(TAG, "We are going to take over black list's job...");
             return;
         }
 
@@ -189,8 +185,7 @@ public final class XposedInit {
                     continue;
 
                 try {
-                    if (BuildConfig.DEBUG)
-                        Log.i(TAG, "  Loading class " + moduleClassName);
+                    Log.i(TAG, "  Loading class " + moduleClassName);
                     Class<?> moduleClass = mcl.loadClass(moduleClassName);
 
                     if (!IXposedMod.class.isAssignableFrom(moduleClass)) {

Core/jni/main/include/fd_utils-inl.h

@@ -0,0 +1,407 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <string>
+#include <unordered_map>
+#include <set>
+#include <vector>
+#include <algorithm>
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <inttypes.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+static const char* kPathPrefixWhitelist[] = {
+        "/data/app/",
+        "/data/app-private/",
+        "/system/app/",
+        "/system/priv-app/",
+        "/vendor/app/",
+        "/vendor/priv-app/",
+        "/dev/binder"
+};
+
+static const char* kFdPath = "/proc/self/fd";
+
+// Keeps track of all relevant information (flags, offset etc.) of an
+// open zygote file descriptor.
+class FileDescriptorInfo {
+public:
+    // Create a FileDescriptorInfo for a given file descriptor. Returns
+    // |NULL| if an error occurred.
+    static FileDescriptorInfo* createFromFd(int fd) {
+        struct stat f_stat;
+        // This should never happen; the zygote should always have the right set
+        // of permissions required to stat all its open files.
+        if (TEMP_FAILURE_RETRY(fstat(fd, &f_stat)) == -1) {
+            LOGE("Unable to stat fd %d : %s", fd, strerror(errno));
+            return NULL;
+        }
+
+        if (S_ISSOCK(f_stat.st_mode)) {
+            std::string socket_name;
+            if (!GetSocketName(fd, &socket_name)) {
+                return NULL;
+            }
+
+            if (!IsWhitelisted(socket_name)) {
+                //LOGE("Socket name not whitelisted : %s (fd=%d)", socket_name.c_str(), fd);
+                return NULL;
+            }
+
+            return new FileDescriptorInfo(fd);
+        }
+
+        std::string file_path;
+        if (!Readlink(fd, &file_path)) {
+            return NULL;
+        }
+
+        if (!IsWhitelisted(file_path)) {
+            //LOGE("Not whitelisted : %s", file_path.c_str());
+            return NULL;
+        }
+
+        // We only handle whitelisted regular files and character devices. Whitelisted
+        // character devices must provide a guarantee of sensible behaviour when
+        // reopened.
+        //
+        // S_ISDIR : Not supported. (We could if we wanted to, but it's unused).
+        // S_ISLINK : Not supported.
+        // S_ISBLK : Not supported.
+        // S_ISFIFO : Not supported. Note that the zygote uses pipes to communicate
+        // with the child process across forks but those should have been closed
+        // before we got to this point.
+        if (!S_ISCHR(f_stat.st_mode) && !S_ISREG(f_stat.st_mode)) {
+            LOGE("Unsupported st_mode %d", f_stat.st_mode);
+            return NULL;
+        }
+
+        // File descriptor flags : currently on FD_CLOEXEC. We can set these
+        // using F_SETFD - we're single threaded at this point of execution so
+        // there won't be any races.
+        const int fd_flags = TEMP_FAILURE_RETRY(fcntl(fd, F_GETFD));
+        if (fd_flags == -1) {
+            LOGE("Failed fcntl(%d, F_GETFD) : %s", fd, strerror(errno));
+            return NULL;
+        }
+
+        // File status flags :
+        // - File access mode : (O_RDONLY, O_WRONLY...) we'll pass these through
+        //   to the open() call.
+        //
+        // - File creation flags : (O_CREAT, O_EXCL...) - there's not much we can
+        //   do about these, since the file has already been created. We shall ignore
+        //   them here.
+        //
+        // - Other flags : We'll have to set these via F_SETFL. On linux, F_SETFL
+        //   can only set O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME, and O_NONBLOCK.
+        //   In particular, it can't set O_SYNC and O_DSYNC. We'll have to test for
+        //   their presence and pass them in to open().
+        int fs_flags = TEMP_FAILURE_RETRY(fcntl(fd, F_GETFL));
+        if (fs_flags == -1) {
+            LOGE("Failed fcntl(%d, F_GETFL) : %s", fd, strerror(errno));
+            return NULL;
+        }
+
+        // File offset : Ignore the offset for non seekable files.
+        const off_t offset = TEMP_FAILURE_RETRY(lseek64(fd, 0, SEEK_CUR));
+
+        // We pass the flags that open accepts to open, and use F_SETFL for
+        // the rest of them.
+        static const int kOpenFlags = (O_RDONLY | O_WRONLY | O_RDWR | O_DSYNC | O_SYNC);
+        int open_flags = fs_flags & (kOpenFlags);
+        fs_flags = fs_flags & (~(kOpenFlags));
+
+        return new FileDescriptorInfo(f_stat, file_path, fd, open_flags, fd_flags, fs_flags, offset);
+    }
+
+    bool Detach() const {
+        const int dev_null_fd = open("/dev/null", O_RDWR);
+        if (dev_null_fd < 0) {
+            LOGE("Failed to open /dev/null : %s", strerror(errno));
+            return false;
+        }
+
+        if (dup2(dev_null_fd, fd) == -1) {
+            LOGE("Failed dup2 on socket descriptor %d : %s", fd, strerror(errno));
+            return false;
+        }
+
+        if (close(dev_null_fd) == -1) {
+            LOGE("Failed close(%d) : %s", dev_null_fd, strerror(errno));
+            return false;
+        }
+
+        return true;
+    }
+
+    bool Reopen() const {
+        if (is_sock) {
+            return true;
+        }
+
+        // NOTE: This might happen if the file was unlinked after being opened.
+        // It's a common pattern in the case of temporary files and the like but
+        // we should not allow such usage from the zygote.
+        const int new_fd = TEMP_FAILURE_RETRY(open(file_path.c_str(), open_flags));
+
+        if (new_fd == -1) {
+            LOGE("Failed open(%s, %d) : %s", file_path.c_str(), open_flags, strerror(errno));
+            return false;
+        }
+
+        if (TEMP_FAILURE_RETRY(fcntl(new_fd, F_SETFD, fd_flags)) == -1) {
+            close(new_fd);
+            LOGE("Failed fcntl(%d, F_SETFD, %x) : %s", new_fd, fd_flags, strerror(errno));
+            return false;
+        }
+
+        if (TEMP_FAILURE_RETRY(fcntl(new_fd, F_SETFL, fs_flags)) == -1) {
+            close(new_fd);
+            LOGE("Failed fcntl(%d, F_SETFL, %x) : %s", new_fd, fs_flags, strerror(errno));
+            return false;
+        }
+
+        if (offset != -1 && TEMP_FAILURE_RETRY(lseek64(new_fd, offset, SEEK_SET)) == -1) {
+            close(new_fd);
+            LOGE("Failed lseek64(%d, SEEK_SET) : %s", new_fd, strerror(errno));
+            return false;
+        }
+
+        if (TEMP_FAILURE_RETRY(dup2(new_fd, fd)) == -1) {
+            close(new_fd);
+            LOGE("Failed dup2(%d, %d) : %s", fd, new_fd, strerror(errno));
+            return false;
+        }
+
+        close(new_fd);
+
+        return true;
+    }
+
+    const int fd;
+    const struct stat stat;
+    const std::string file_path;
+    const int open_flags;
+    const int fd_flags;
+    const int fs_flags;
+    const off_t offset;
+    const bool is_sock;
+
+private:
+    FileDescriptorInfo(int pfd) :
+            fd(pfd),
+            stat(),
+            open_flags(0),
+            fd_flags(0),
+            fs_flags(0),
+            offset(0),
+            is_sock(true) {
+    }
+
+    FileDescriptorInfo(struct stat pstat, const std::string& pfile_path, int pfd, int popen_flags,
+                       int pfd_flags, int pfs_flags, off_t poffset) :
+            fd(pfd),
+            stat(pstat),
+            file_path(pfile_path),
+            open_flags(popen_flags),
+            fd_flags(pfd_flags),
+            fs_flags(pfs_flags),
+            offset(poffset),
+            is_sock(false) {
+    }
+
+    // Returns true iff. a given path is whitelisted.
+    static bool IsWhitelisted(const std::string& path) {
+        for (size_t i = 0; i < (sizeof(kPathPrefixWhitelist) / sizeof(kPathPrefixWhitelist[0])); ++i) {
+            if (path.compare(0, strlen(kPathPrefixWhitelist[i]), kPathPrefixWhitelist[i]) == 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    // TODO: Call android::base::Readlink instead of copying the code here.
+    static bool Readlink(const int fd, std::string* result) {
+        char path[64];
+        snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
+
+        // Code copied from android::base::Readlink starts here :
+
+        // Annoyingly, the readlink system call returns EINVAL for a zero-sized buffer,
+        // and truncates to whatever size you do supply, so it can't be used to query.
+        // We could call lstat first, but that would introduce a race condition that
+        // we couldn't detect.
+        // ext2 and ext4 both have PAGE_SIZE limitations, so we assume that here.
+        char* buf = new char[4096];
+        ssize_t len = readlink(path, buf, 4096);
+        if (len == -1) {
+            delete[] buf;
+            return false;
+        }
+
+        result->assign(buf, len);
+        delete[] buf;
+        return true;
+    }
+
+    // Returns the locally-bound name of the socket |fd|. Returns true
+    // iff. all of the following hold :
+    //
+    // - the socket's sa_family is AF_UNIX.
+    // - the length of the path is greater than zero (i.e, not an unnamed socket).
+    // - the first byte of the path isn't zero (i.e, not a socket with an abstract
+    //   address).
+    static bool GetSocketName(const int fd, std::string* result) {
+        sockaddr_storage ss;
+        sockaddr* addr = reinterpret_cast<sockaddr*>(&ss);
+        socklen_t addr_len = sizeof(ss);
+
+        if (TEMP_FAILURE_RETRY(getsockname(fd, addr, &addr_len)) == -1) {
+            LOGE("Failed getsockname(%d) : %s", fd, strerror(errno));
+            return false;
+        }
+
+#if PLATFORM_SDK_VERSION <= 23
+        if (addr->sa_family == AF_NETLINK) {
+            (*result) = "@netlink@";
+            return true;
+        }
+#endif
+
+        if (addr->sa_family != AF_UNIX) {
+            //LOGE("Unsupported socket (fd=%d) with family %d", fd, addr->sa_family);
+            return false;
+        }
+
+        const sockaddr_un* unix_addr = reinterpret_cast<const sockaddr_un*>(&ss);
+
+        size_t path_len = addr_len - offsetof(struct sockaddr_un, sun_path);
+        // This is an unnamed local socket, we do not accept it.
+        if (path_len == 0) {
+            //LOGE("Unsupported AF_UNIX socket (fd=%d) with empty path.", fd);
+            return false;
+        }
+
+        // This is a local socket with an abstract address, we do not accept it.
+        if (unix_addr->sun_path[0] == '\0') {
+            //LOGE("Unsupported AF_UNIX socket (fd=%d) with abstract address.", fd);
+            return false;
+        }
+
+        // If we're here, sun_path must refer to a null terminated filesystem
+        // pathname (man 7 unix). Remove the terminator before assigning it to an
+        // std::string.
+        if (unix_addr->sun_path[path_len - 1] ==  '\0') {
+            --path_len;
+        }
+
+        result->assign(unix_addr->sun_path, path_len);
+        return true;
+    }
+
+
+    // DISALLOW_COPY_AND_ASSIGN(FileDescriptorInfo);
+    FileDescriptorInfo(const FileDescriptorInfo&);
+    void operator=(const FileDescriptorInfo&);
+};
+
+// A FileDescriptorTable is a collection of FileDescriptorInfo objects
+// keyed by their FDs.
+class FileDescriptorTable {
+public:
+    // Creates a new FileDescriptorTable. This function scans
+    // /proc/self/fd for the list of open file descriptors and collects
+    // information about them. Returns NULL if an error occurs.
+    static FileDescriptorTable* Create() {
+        DIR* d = opendir(kFdPath);
+        if (d == NULL) {
+            LOGE("Unable to open directory %s: %s", kFdPath, strerror(errno));
+            return NULL;
+        }
+        int dir_fd = dirfd(d);
+        dirent* e;
+
+        std::unordered_map<int, FileDescriptorInfo*> open_fd_map;
+        while ((e = readdir(d)) != NULL) {
+            const int fd = ParseFd(e, dir_fd);
+            if (fd == -1) {
+                continue;
+            }
+
+            FileDescriptorInfo* info = FileDescriptorInfo::createFromFd(fd);
+            if (info == NULL) {
+                continue;
+            }
+            info->Detach();
+            open_fd_map[fd] = info;
+        }
+
+        if (closedir(d) == -1) {
+            LOGE("Unable to close directory : %s", strerror(errno));
+            return NULL;
+        }
+        return new FileDescriptorTable(open_fd_map);
+    }
+
+    // Reopens all file descriptors that are contained in the table.
+    void Reopen() {
+        std::unordered_map<int, FileDescriptorInfo*>::const_iterator it;
+        for (it = open_fd_map_.begin(); it != open_fd_map_.end(); ++it) {
+            const FileDescriptorInfo* info = it->second;
+            if (info != NULL) {
+                info->Reopen();
+                delete info;
+            }
+        }
+    }
+
+private:
+    FileDescriptorTable(const std::unordered_map<int, FileDescriptorInfo*>& map)
+            : open_fd_map_(map) {
+    }
+
+    static int ParseFd(dirent* e, int dir_fd) {
+        char* end;
+        const int fd = strtol(e->d_name, &end, 10);
+        if ((*end) != '\0') {
+            return -1;
+        }
+
+        // Don't bother with the standard input/output/error, they're handled
+        // specially post-fork anyway.
+        if (fd <= STDERR_FILENO || fd == dir_fd) {
+            return -1;
+        }
+
+        return fd;
+    }
+
+    // Invariant: All values in this unordered_map are non-NULL.
+    std::unordered_map<int, FileDescriptorInfo*> open_fd_map_;
+
+    // DISALLOW_COPY_AND_ASSIGN(FileDescriptorTable);
+    FileDescriptorTable(const FileDescriptorTable&);
+    void operator=(const FileDescriptorTable&);
+};

Core/jni/main/java_hook/java_hook.cpp

@@ -8,6 +8,7 @@
 #include <inject/config_manager.h>
 #include "java_hook/java_hook.h"
 #include "include/logging.h"
+#include "include/fd_utils-inl.h"
 #include "native_hook/native_hook.h"
 
 extern "C"
@@ -19,6 +20,18 @@ jobject gInjectDexClassLoader;
 
 static bool isInited = false;
 
+static FileDescriptorTable* gClosedFdTable = NULL;
+
+void closeFilesBeforeForkNative(JNIEnv*, jclass) {
+    gClosedFdTable = FileDescriptorTable::Create();
+}
+
+void reopenFilesAfterForkNative(JNIEnv*, jclass) {
+    gClosedFdTable->Reopen();
+    delete gClosedFdTable;
+    gClosedFdTable = NULL;
+}
+
 static JNINativeMethod hookMethods[] = {
         {
                 "init",
@@ -42,6 +55,12 @@ static JNINativeMethod hookMethods[] = {
         },
         {
                 "getInstallerPkgName", "()Ljava/lang/String;", (void *)get_installer_pkg_name
+        },
+        {
+                "closeFilesBeforeForkNative", "()V", (void *)closeFilesBeforeForkNative
+        },
+        {
+                "reopenFilesAfterForkNative", "()V", (void *)reopenFilesAfterForkNative
         }
 };
 
@@ -80,7 +99,7 @@ void loadDexAndInit(JNIEnv *env, const char *dexPath) {
     jclass entry_class = findClassFromLoader(env, myClassLoader, ENTRY_CLASS_NAME);
     if (NULL != entry_class) {
         LOGD("HookEntry Class %p", entry_class);
-        env->RegisterNatives(entry_class, hookMethods, 5);
+        env->RegisterNatives(entry_class, hookMethods, 7);
         isInited = true;
         LOGD("RegisterNatives succeed for HookEntry.");
     } else {