mt6735: Add PersistentStorage and UniqueDeviceId.

Adds cmhw implementations for the unique device id interface using the
EMMC id and persist storage in /persist_s.

Change-Id: Ic2dba55586453b31f31844b344ad43480472e13a

cmhw/org/cyanogenmod/hardware/PersistentStorage.java

@@ -0,0 +1,196 @@
+/*
+ * Copyright (C) 2015 The CyanogenMod 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.
+ */
+
+package org.cyanogenmod.hardware;
+
+import android.os.FileUtils;
+import android.util.Slog;
+
+import java.io.File;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.security.MessageDigest;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+/**
+ * Support for storage of key-value pairs which persists across device wipes /
+ * factory resets. This is used for various security related features. A
+ * reasonable implementation of this needs to store items on a partition which
+ * is unaffected by factory reset. The actual format of the storage is left up
+ * to the implementation. The implementation in this file is suitable for
+ * devices which have a /persist partition (recent QCOM devices fit this
+ * criteria).
+ */
+public class PersistentStorage {
+
+    public static final int MAX_KEY_LEN = 64;
+    public static final int MAX_VALUE_LEN = 4096;
+
+    private static final String TAG = "PersistentStorage";
+
+    private static final String PERSIST_DATA_PATH = "/protect_s/properties";
+
+    private static final boolean DEBUG = false;
+
+    private static final ReadWriteLock rwl = new ReentrantReadWriteLock();
+
+    /**
+     * Whether device supports persistent properties
+     *
+     * @return boolean Supported devices must return always true
+     */
+    public static boolean isSupported() {
+        final File file = new File(PERSIST_DATA_PATH);
+        return file.exists() && file.isDirectory() && file.canRead() && file.canWrite();
+    }
+
+    /**
+     * Gets an array of bytes from persistent storage.
+     *
+     * @param key
+     * @return previously stored byte array, null if not found
+     */
+    public static byte[] get(String key) {
+        if (!isSupported() || key.length() > MAX_KEY_LEN) {
+            return null;
+        }
+
+        final String encodedKey = encode(key);
+        if (encodedKey == null) {
+            return null;
+        }
+
+        FileInputStream fis = null;
+
+        try {
+            rwl.readLock().lock();
+
+            final File prop = new File(PERSIST_DATA_PATH + "/" + encodedKey);
+
+            if (!prop.exists()) {
+                if (DEBUG) {
+                    Slog.e(TAG, "Unable to read from " + prop.getAbsolutePath());
+                }
+                return null;
+            }
+
+            final byte[] buffer = new byte[MAX_VALUE_LEN];
+            fis = new FileInputStream(prop);
+            ByteArrayOutputStream bos = new ByteArrayOutputStream();
+            int len = fis.read(buffer);
+            bos.write(buffer, 0, len);
+            return bos.toByteArray();
+
+        } catch (Exception e) {
+            Slog.e(TAG, e.getMessage(), e);
+        } finally {
+            if (fis != null) {
+                try {
+                    fis.close();
+                } catch (IOException ex) {
+                    // skip it
+                }
+            }
+            rwl.readLock().unlock();
+        }
+
+        return null;
+    }
+
+    /**
+     * Writes a byte array to persistent storage.
+     *
+     * The storage of the data is implementation specific. In this implementation,
+     * we hash the key with SHA-256 and use the hex string as the stored key.
+     *
+     * Implementations should delete the key if a null buffer is passed.
+     *
+     * @param key
+     * @param buffer
+     * @return true if the operation succeeded
+     */
+    public static boolean set(String key, byte[] buffer) {
+        if (!isSupported() ||
+                key == null || key.length() > MAX_KEY_LEN ||
+                (buffer != null && buffer.length > MAX_VALUE_LEN)) {
+            return false;
+        }
+
+        final String encodedKey = encode(key);
+        if (encodedKey == null) {
+            return false;
+        }
+
+        try {
+            rwl.writeLock().lock();
+
+            final File prop = new File(PERSIST_DATA_PATH + "/" + encodedKey);
+
+            File tmp = null;
+            if (buffer != null) {
+                tmp = File.createTempFile(key, "tmp",
+                        new File(PERSIST_DATA_PATH));
+                if (!FileUtils.copyToFile(new ByteArrayInputStream(buffer), tmp)) {
+                    Slog.e(TAG, "Unable to create temporary file!");
+                    return false;
+                }
+            }
+
+            if (prop.exists()) {
+                prop.delete();
+            }
+
+            if (tmp != null) {
+                tmp.renameTo(prop);
+            }
+
+        } catch (Exception e) {
+            Slog.e(TAG, e.getMessage(), e);
+            return false;
+
+        } finally {
+            rwl.writeLock().unlock();
+        }
+        return true;
+    }
+
+    /**
+     * Used for encoding keys with SHA-256
+     *
+     * @param key
+     * @return
+     */
+    private static String encode(String key) {
+        try {
+            MessageDigest d = MessageDigest.getInstance("SHA-256");
+            byte[] hash = d.digest(key.getBytes("UTF-8"));
+            StringBuilder encoded = new StringBuilder();
+
+            for (byte b : hash) {
+                encoded.append(String.format("%02x", b & 0xff));
+            }
+
+            return encoded.toString();
+        } catch (Exception e) {
+            Slog.e(TAG, e.getMessage(), e);
+        }
+        return null;
+    }
+}

cmhw/org/cyanogenmod/hardware/UniqueDeviceId.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2016 The CyanogenMod 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.
+ */
+
+package org.cyanogenmod.hardware;
+
+import org.cyanogenmod.hardware.util.FileUtils;
+
+/**
+ * Generate a unique but deterministic ID for this hardware, based on unchangeable
+ * hardware serial numbers.
+ */
+public class UniqueDeviceId {
+    private static final int TYPE_MMC0_CID = 0;
+
+    private static String sUniqueId = null;
+
+    /**
+     * Whether device supports reporting a unique device id.
+     *
+     * @return boolean Supported devices must return always true
+     */
+    public static boolean isSupported() {
+        return getUniqueDeviceIdInternal() != null;
+    }
+
+    /**
+     * This method retreives a unique ID for the device.
+     *
+     * @return String The unique device ID
+     */
+    public static String getUniqueDeviceId() {
+        return getUniqueDeviceIdInternal();
+    }
+
+    private static String getUniqueDeviceIdInternal() {
+        if (sUniqueId != null) {
+            return sUniqueId;
+        }
+
+        String sMmcType = FileUtils.readOneLine("/sys/block/mmcblk0/device/type");
+        String sCid = FileUtils.readOneLine("/sys/block/mmcblk0/device/cid");
+        if ("MMC".equals(sMmcType) && sCid != null) {
+            sCid = sCid.trim();
+            if (sCid.length() == 32) {
+                sUniqueId = String.format("%03x00000%32s", TYPE_MMC0_CID, sCid);
+                return sUniqueId;
+            }
+        }
+
+        /* Any additional types should be added here. */
+
+        return null;
+    }
+}

rootdir/init.mt6735.rc

@@ -97,6 +97,8 @@ on post-fs
     chown system system /protect_s
     chmod 0770 /protect_s
 
+    mkdir /protect_s/properties 0770 system system
+
     mkdir /nvdata/APCFG 0770 system camera
     mkdir /nvdata/APCFG/APRDCL 0770 system camera
     mkdir /nvdata/APCFG/APRDEB 0770 system camera

sepolicy/file_contexts

@@ -234,6 +234,7 @@
 /dev/shf                 u:object_r:shf_device:s0
 /protect_f(/.*)?         u:object_r:protect_f_data_file:s0
 /protect_s(/.*)?         u:object_r:protect_s_data_file:s0
+/protect_s/properties(/.*)?                                     u:object_r:persist_property_file:s0 
 /persist(/.*)?         u:object_r:persist_data_file:s0
 /dev/ttyACM0        u:object_r:ttyACM_device:s0
 /dev/hrm       u:object_r:hrm_device:s0

sepolicy/system_server.te

@@ -154,6 +154,8 @@ allow system_server zygote:unix_stream_socket { getopt getattr };
 # Purpose : for kill-switch should only grant to access frp partition, to be fix
 allow system_server platformblk_device:dir search;
 
+# Persist
+allow system_server protect_s_data_file:dir r_dir_perms;
 
 # Debugfs
 allow system_server debugfs:dir { read open };