Merge "Retry deleting dm devices."
diff --git a/FsCrypt.cpp b/FsCrypt.cpp
index 4163f4f..0619fba 100644
--- a/FsCrypt.cpp
+++ b/FsCrypt.cpp
@@ -211,6 +211,19 @@
     return true;
 }
 
+static bool install_storage_key(const std::string& mountpoint, const EncryptionOptions& options,
+                                const KeyBuffer& key, EncryptionPolicy* policy) {
+    KeyBuffer ephemeral_wrapped_key;
+    if (options.use_hw_wrapped_key) {
+        if (!exportWrappedStorageKey(key, &ephemeral_wrapped_key)) {
+            LOG(ERROR) << "Failed to get ephemeral wrapped key";
+            return false;
+        }
+    }
+    return installKey(mountpoint, options, options.use_hw_wrapped_key ? ephemeral_wrapped_key : key,
+                      policy);
+}
+
 // Retrieve the options to use for encryption policies on adoptable storage.
 static bool get_volume_file_encryption_options(EncryptionOptions* options) {
     auto contents_mode =
@@ -234,7 +247,7 @@
     KeyBuffer ce_key;
     if (!read_and_fixate_user_ce_key(user_id, auth, &ce_key)) return false;
     EncryptionPolicy ce_policy;
-    if (!installKey(DATA_MNT_POINT, options, ce_key, &ce_policy)) return false;
+    if (!install_storage_key(DATA_MNT_POINT, options, ce_key, &ce_policy)) return false;
     s_ce_policies[user_id] = ce_policy;
     LOG(DEBUG) << "Installed ce key for user " << user_id;
     return true;
@@ -264,8 +277,8 @@
     EncryptionOptions options;
     if (!get_data_file_encryption_options(&options)) return false;
     KeyBuffer de_key, ce_key;
-    if (!android::vold::randomKey(&de_key)) return false;
-    if (!android::vold::randomKey(&ce_key)) return false;
+    if (!generateStorageKey(options, &de_key)) return false;
+    if (!generateStorageKey(options, &ce_key)) return false;
     if (create_ephemeral) {
         // If the key should be created as ephemeral, don't store it.
         s_ephemeral_users.insert(user_id);
@@ -285,10 +298,10 @@
             return false;
     }
     EncryptionPolicy de_policy;
-    if (!installKey(DATA_MNT_POINT, options, de_key, &de_policy)) return false;
+    if (!install_storage_key(DATA_MNT_POINT, options, de_key, &de_policy)) return false;
     s_de_policies[user_id] = de_policy;
     EncryptionPolicy ce_policy;
-    if (!installKey(DATA_MNT_POINT, options, ce_key, &ce_policy)) return false;
+    if (!install_storage_key(DATA_MNT_POINT, options, ce_key, &ce_policy)) return false;
     s_ce_policies[user_id] = ce_policy;
     LOG(DEBUG) << "Created keys for user " << user_id;
     return true;
@@ -341,7 +354,7 @@
             KeyBuffer de_key;
             if (!android::vold::retrieveKey(key_path, kEmptyAuthentication, &de_key)) return false;
             EncryptionPolicy de_policy;
-            if (!installKey(DATA_MNT_POINT, options, de_key, &de_policy)) return false;
+            if (!install_storage_key(DATA_MNT_POINT, options, de_key, &de_policy)) return false;
             s_de_policies[user_id] = de_policy;
             LOG(DEBUG) << "Installed de key for user " << user_id;
         }
@@ -363,12 +376,11 @@
 
     KeyBuffer device_key;
     if (!android::vold::retrieveKey(true, kEmptyAuthentication, device_key_path, device_key_temp,
-                                    &device_key))
+                                    options, &device_key))
         return false;
 
     EncryptionPolicy device_policy;
-    if (!android::vold::installKey(DATA_MNT_POINT, options, device_key, &device_policy))
-        return false;
+    if (!install_storage_key(DATA_MNT_POINT, options, device_key, &device_policy)) return false;
 
     std::string options_string;
     if (!OptionsToString(device_policy.options, &options_string)) {
@@ -383,10 +395,9 @@
     LOG(INFO) << "Wrote system DE key reference to:" << ref_filename;
 
     KeyBuffer per_boot_key;
-    if (!android::vold::randomKey(&per_boot_key)) return false;
+    if (!generateStorageKey(options, &per_boot_key)) return false;
     EncryptionPolicy per_boot_policy;
-    if (!android::vold::installKey(DATA_MNT_POINT, options, per_boot_key, &per_boot_policy))
-        return false;
+    if (!install_storage_key(DATA_MNT_POINT, options, per_boot_key, &per_boot_policy)) return false;
     std::string per_boot_ref_filename = std::string("/data") + fscrypt_key_per_boot_ref;
     if (!android::vold::writeStringToFile(per_boot_policy.key_raw_ref, per_boot_ref_filename))
         return false;
@@ -593,8 +604,9 @@
     EncryptionOptions options;
     if (!get_volume_file_encryption_options(&options)) return false;
     KeyBuffer key;
-    if (!android::vold::retrieveKey(true, auth, key_path, key_path + "_tmp", &key)) return false;
-    if (!android::vold::installKey(BuildDataPath(volume_uuid), options, key, policy)) return false;
+    if (!android::vold::retrieveKey(true, auth, key_path, key_path + "_tmp", options, &key))
+        return false;
+    if (!install_storage_key(BuildDataPath(volume_uuid), options, key, policy)) return false;
     return true;
 }
 
diff --git a/KeyStorage.cpp b/KeyStorage.cpp
index dbf190d..a7582c2 100644
--- a/KeyStorage.cpp
+++ b/KeyStorage.cpp
@@ -135,6 +135,30 @@
            keymaster.generateKey(paramBuilder, key);
 }
 
+bool generateWrappedStorageKey(KeyBuffer* key) {
+    Keymaster keymaster;
+    if (!keymaster) return false;
+    std::string key_temp;
+    auto paramBuilder = km::AuthorizationSetBuilder().AesEncryptionKey(AES_KEY_BYTES * 8);
+    paramBuilder.Authorization(km::TAG_ROLLBACK_RESISTANCE);
+    paramBuilder.Authorization(km::TAG_STORAGE_KEY);
+    if (!keymaster.generateKey(paramBuilder, &key_temp)) return false;
+    *key = KeyBuffer(key_temp.size());
+    memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
+    return true;
+}
+
+bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key) {
+    Keymaster keymaster;
+    if (!keymaster) return false;
+    std::string key_temp;
+
+    if (!keymaster.exportKey(kmKey, &key_temp)) return false;
+    *key = KeyBuffer(key_temp.size());
+    memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
+    return true;
+}
+
 static std::pair<km::AuthorizationSet, km::HardwareAuthToken> beginParams(
     const KeyAuthentication& auth, const std::string& appId) {
     auto paramBuilder = km::AuthorizationSetBuilder()
diff --git a/KeyStorage.h b/KeyStorage.h
index 276b6b9..f9d3ec6 100644
--- a/KeyStorage.h
+++ b/KeyStorage.h
@@ -68,6 +68,11 @@
 bool destroyKey(const std::string& dir);
 
 bool runSecdiscardSingle(const std::string& file);
+
+// Generate wrapped storage key using keymaster. Uses STORAGE_KEY tag in keymaster.
+bool generateWrappedStorageKey(KeyBuffer* key);
+// Export the per-boot boot wrapped storage key using keymaster.
+bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key);
 }  // namespace vold
 }  // namespace android
 
diff --git a/KeyUtil.cpp b/KeyUtil.cpp
index d4a653b..ae4d70b 100644
--- a/KeyUtil.cpp
+++ b/KeyUtil.cpp
@@ -29,6 +29,7 @@
 #include <android-base/logging.h>
 #include <keyutils.h>
 
+#include <fscrypt_uapi.h>
 #include "KeyStorage.h"
 #include "Utils.h"
 
@@ -45,6 +46,13 @@
     return true;
 }
 
+bool generateStorageKey(const EncryptionOptions& options, KeyBuffer* key) {
+    if (options.use_hw_wrapped_key) {
+        return generateWrappedStorageKey(key);
+    }
+    return randomKey(key);
+}
+
 // Return true if the kernel supports the ioctls to add/remove fscrypt keys
 // directly to/from the filesystem.
 bool isFsKeyringSupported(void) {
@@ -222,6 +230,7 @@
             return false;
     }
 
+    if (options.use_hw_wrapped_key) arg->flags |= FSCRYPT_ADD_KEY_FLAG_WRAPPED;
     // Provide the raw key.
     arg->raw_size = key.size();
     memcpy(arg->raw, key.data(), key.size());
@@ -307,8 +316,8 @@
 }
 
 bool retrieveKey(bool create_if_absent, const KeyAuthentication& key_authentication,
-                 const std::string& key_path, const std::string& tmp_path, KeyBuffer* key,
-                 bool keepOld) {
+                 const std::string& key_path, const std::string& tmp_path,
+                 const EncryptionOptions& options, KeyBuffer* key, bool keepOld) {
     if (pathExists(key_path)) {
         LOG(DEBUG) << "Key exists, using: " << key_path;
         if (!retrieveKey(key_path, key_authentication, key, keepOld)) return false;
@@ -318,7 +327,7 @@
             return false;
         }
         LOG(INFO) << "Creating new key in " << key_path;
-        if (!randomKey(key)) return false;
+        if (!generateStorageKey(options, key)) return false;
         if (!storeKeyAtomically(key_path, tmp_path, key_authentication, *key)) return false;
     }
     return true;
diff --git a/KeyUtil.h b/KeyUtil.h
index be5a2ed..878b4ab 100644
--- a/KeyUtil.h
+++ b/KeyUtil.h
@@ -32,6 +32,8 @@
 
 bool randomKey(KeyBuffer* key);
 
+bool generateStorageKey(const EncryptionOptions& options, KeyBuffer* key);
+
 bool isFsKeyringSupported(void);
 
 // Install a file-based encryption key to the kernel, for use by encrypted files
@@ -57,8 +59,8 @@
 bool evictKey(const std::string& mountpoint, const EncryptionPolicy& policy);
 
 bool retrieveKey(bool create_if_absent, const KeyAuthentication& key_authentication,
-                 const std::string& key_path, const std::string& tmp_path, KeyBuffer* key,
-                 bool keepOld = true);
+                 const std::string& key_path, const std::string& tmp_path,
+                 const EncryptionOptions& options, KeyBuffer* key, bool keepOld = true);
 
 }  // namespace vold
 }  // namespace android
diff --git a/Keymaster.cpp b/Keymaster.cpp
index abee9b2..c3f2912 100644
--- a/Keymaster.cpp
+++ b/Keymaster.cpp
@@ -138,6 +138,27 @@
     return true;
 }
 
+bool Keymaster::exportKey(const KeyBuffer& kmKey, std::string* key) {
+    auto kmKeyBlob = km::support::blob2hidlVec(std::string(kmKey.data(), kmKey.size()));
+    km::ErrorCode km_error;
+    auto hidlCb = [&](km::ErrorCode ret, const hidl_vec<uint8_t>& exportedKeyBlob) {
+        km_error = ret;
+        if (km_error != km::ErrorCode::OK) return;
+        if (key)
+            key->assign(reinterpret_cast<const char*>(&exportedKeyBlob[0]), exportedKeyBlob.size());
+    };
+    auto error = mDevice->exportKey(km::KeyFormat::RAW, kmKeyBlob, {}, {}, hidlCb);
+    if (!error.isOk()) {
+        LOG(ERROR) << "export_key failed: " << error.description();
+        return false;
+    }
+    if (km_error != km::ErrorCode::OK) {
+        LOG(ERROR) << "export_key failed, code " << int32_t(km_error);
+        return false;
+    }
+    return true;
+}
+
 bool Keymaster::deleteKey(const std::string& key) {
     auto keyBlob = km::support::blob2hidlVec(key);
     auto error = mDevice->deleteKey(keyBlob);
diff --git a/Keymaster.h b/Keymaster.h
index 78f66a3..4a9ed02 100644
--- a/Keymaster.h
+++ b/Keymaster.h
@@ -114,6 +114,8 @@
     explicit operator bool() { return mDevice.get() != nullptr; }
     // Generate a key in the keymaster from the given params.
     bool generateKey(const km::AuthorizationSet& inParams, std::string* key);
+    // Exports a keymaster key with STORAGE_KEY tag wrapped with a per-boot ephemeral key
+    bool exportKey(const KeyBuffer& kmKey, std::string* key);
     // If the keymaster supports it, permanently delete a key.
     bool deleteKey(const std::string& key);
     // Replace stored key blob in response to KM_ERROR_KEY_REQUIRES_UPGRADE.
diff --git a/MetadataCrypt.cpp b/MetadataCrypt.cpp
index acd5b59..76ea9eb 100644
--- a/MetadataCrypt.cpp
+++ b/MetadataCrypt.cpp
@@ -113,6 +113,23 @@
     LOG(INFO) << "Old Key deleted: " << dir;
 }
 
+static bool retrieveMetadataKey(bool create_if_absent, const std::string& key_path,
+                                const std::string& tmp_path, KeyBuffer* key, bool keepOld) {
+    if (pathExists(key_path)) {
+        LOG(DEBUG) << "Key exists, using: " << key_path;
+        if (!retrieveKey(key_path, kEmptyAuthentication, key, keepOld)) return false;
+    } else {
+        if (!create_if_absent) {
+            LOG(ERROR) << "No key found in " << key_path;
+            return false;
+        }
+        LOG(INFO) << "Creating new key in " << key_path;
+        if (!randomKey(key)) return false;
+        if (!storeKeyAtomically(key_path, tmp_path, kEmptyAuthentication, *key)) return false;
+    }
+    return true;
+}
+
 static bool read_key(const FstabEntry& data_rec, bool create_if_absent, KeyBuffer* key) {
     if (data_rec.metadata_key_dir.empty()) {
         LOG(ERROR) << "Failed to get metadata_key_dir";
@@ -143,9 +160,7 @@
             unlink(newKeyPath.c_str());
     }
     bool needs_cp = cp_needsCheckpoint();
-    if (!android::vold::retrieveKey(create_if_absent, kEmptyAuthentication, dir, temp, key,
-                                    needs_cp))
-        return false;
+    if (!retrieveMetadataKey(create_if_absent, dir, temp, key, needs_cp)) return false;
     if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
     return true;
 }
diff --git a/VoldNativeService.cpp b/VoldNativeService.cpp
index 3643c74..dbe1d98 100644
--- a/VoldNativeService.cpp
+++ b/VoldNativeService.cpp
@@ -458,14 +458,12 @@
     return translate(VolumeManager::Instance()->remountUid(uid, remountMode));
 }
 
-binder::Status VoldNativeService::setupAppDir(const std::string& path,
-                                              const std::string& appDirRoot, int32_t appUid) {
+binder::Status VoldNativeService::setupAppDir(const std::string& path, int32_t appUid) {
     ENFORCE_SYSTEM_OR_ROOT;
     CHECK_ARGUMENT_PATH(path);
-    CHECK_ARGUMENT_PATH(appDirRoot);
     ACQUIRE_LOCK;
 
-    return translate(VolumeManager::Instance()->setupAppDir(path, appDirRoot, appUid));
+    return translate(VolumeManager::Instance()->setupAppDir(path, appUid));
 }
 
 binder::Status VoldNativeService::createObb(const std::string& sourcePath,
diff --git a/VoldNativeService.h b/VoldNativeService.h
index 7de2a67..36b2717 100644
--- a/VoldNativeService.h
+++ b/VoldNativeService.h
@@ -65,8 +65,7 @@
 
     binder::Status remountUid(int32_t uid, int32_t remountMode);
 
-    binder::Status setupAppDir(const std::string& path, const std::string& appDirRoot,
-                               int32_t appUid);
+    binder::Status setupAppDir(const std::string& path, int32_t appUid);
 
     binder::Status createObb(const std::string& sourcePath, const std::string& sourceKey,
                              int32_t ownerGid, std::string* _aidl_return);
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index c141d2a..9eb7852 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -823,8 +823,7 @@
     return 0;
 }
 
-int VolumeManager::setupAppDir(const std::string& path, const std::string& appDirRoot,
-                               int32_t appUid) {
+int VolumeManager::setupAppDir(const std::string& path, int32_t appUid) {
     // Only offer to create directories for paths managed by vold
     if (!StartsWith(path, "/storage/")) {
         LOG(ERROR) << "Failed to find mounted volume for " << path;
diff --git a/VolumeManager.h b/VolumeManager.h
index eb48736..5a2a481 100644
--- a/VolumeManager.h
+++ b/VolumeManager.h
@@ -133,20 +133,27 @@
 
     /*
      * Creates a directory 'path' for an application, automatically creating
-     * directories along the given path if they don't exist yet. 'appDirRoot'
-     * is the "root" directory for app-specific directories of this kind;
-     * 'path' must always start with 'appDirRoot'.
+     * directories along the given path if they don't exist yet.
      *
      * Example:
      *   path = /storage/emulated/0/Android/data/com.foo/files/
-     *   appDirRoot = /storage/emulated/0/Android/data/
      *
-     * This function will set the UID of all app-specific directories below
-     * 'appDirRoot' to the 'appUid' argument. In the given example, the UID
+     * This function will first match the first part of the path with the volume
+     * root of any known volumes; in this case, "/storage/emulated/0" matches
+     * with the volume root of the emulated volume for user 0.
+     *
+     * The subseqent part of the path must start with one of the well-known
+     * Android/ data directories, /Android/data, /Android/obb or
+     * /Android/media.
+     *
+     * The final part of the path is application specific. This function will
+     * create all directories, including the application-specific ones, and
+     * set the UID of all app-specific directories below the well-known data
+     * directories to the 'appUid' argument. In the given example, the UID
      * of /storage/emulated/0/Android/data/com.foo and
      * /storage/emulated/0/Android/data/com.foo/files would be set to 'appUid'.
      *
-     * The UID of the parent directories will be set according to the
+     * The UID/GID of the parent directories will be set according to the
      * requirements of the underlying filesystem and are of no concern to the
      * caller.
      *
@@ -155,7 +162,7 @@
      * and ignored, unless the path ends with "/".  Also ensures that path
      * belongs to a volume managed by vold.
      */
-    int setupAppDir(const std::string& path, const std::string& appDirRoot, int32_t appUid);
+    int setupAppDir(const std::string& path, int32_t appUid);
 
     int createObb(const std::string& path, const std::string& key, int32_t ownerGid,
                   std::string* outVolId);
diff --git a/binder/android/os/IVold.aidl b/binder/android/os/IVold.aidl
index f1e463a..29a63af 100644
--- a/binder/android/os/IVold.aidl
+++ b/binder/android/os/IVold.aidl
@@ -54,7 +54,7 @@
 
     void remountUid(int uid, int remountMode);
 
-    void setupAppDir(@utf8InCpp String path, @utf8InCpp String appDirRoot, int appUid);
+    void setupAppDir(@utf8InCpp String path, int appUid);
 
     @utf8InCpp String createObb(@utf8InCpp String sourcePath, @utf8InCpp String sourceKey,
                                 int ownerGid);
diff --git a/cryptfs.cpp b/cryptfs.cpp
index c06de0a..1596460 100644
--- a/cryptfs.cpp
+++ b/cryptfs.cpp
@@ -74,6 +74,7 @@
 using android::base::ParseUint;
 using android::base::StringPrintf;
 using android::fs_mgr::GetEntryForMountPoint;
+using android::vold::KeyBuffer;
 using namespace android::dm;
 using namespace std::chrono_literals;
 
@@ -1926,8 +1927,13 @@
  * as any metadata is been stored in a separate, small partition.  We
  * assume it must be using our same crypt type and keysize.
  */
-int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev, const unsigned char* key,
+int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev, const KeyBuffer& key,
                              std::string* out_crypto_blkdev) {
+    if (key.size() != cryptfs_get_keysize()) {
+        SLOGE("Raw keysize %zu does not match crypt keysize %" PRIu32, key.size(),
+              cryptfs_get_keysize());
+        return -1;
+    }
     uint64_t nr_sec = 0;
     if (android::vold::GetBlockDev512Sectors(real_blkdev, &nr_sec) != android::OK) {
         SLOGE("Failed to get size of %s: %s", real_blkdev, strerror(errno));
@@ -1945,7 +1951,8 @@
         android::base::GetBoolProperty("ro.crypto.allow_encrypt_override", false))
         flags |= CREATE_CRYPTO_BLK_DEV_FLAGS_ALLOW_ENCRYPT_OVERRIDE;
 
-    return create_crypto_blk_dev(&ext_crypt_ftr, key, real_blkdev, out_crypto_blkdev, label, flags);
+    return create_crypto_blk_dev(&ext_crypt_ftr, reinterpret_cast<const unsigned char*>(key.data()),
+                                 real_blkdev, out_crypto_blkdev, label, flags);
 }
 
 /*
diff --git a/cryptfs.h b/cryptfs.h
index 98ba7d6..463db7f 100644
--- a/cryptfs.h
+++ b/cryptfs.h
@@ -25,6 +25,8 @@
 
 #include <cutils/properties.h>
 
+#include "KeyBuffer.h"
+
 #define CRYPT_FOOTER_OFFSET 0x4000
 
 /* Return values for cryptfs_crypto_complete */
@@ -62,8 +64,8 @@
 int cryptfs_enable(int type, const char* passwd, int no_ui);
 int cryptfs_changepw(int type, const char* newpw);
 int cryptfs_enable_default(int no_ui);
-int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev, const unsigned char* key,
-                             std::string* out_crypto_blkdev);
+int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev,
+                             const android::vold::KeyBuffer& key, std::string* out_crypto_blkdev);
 int cryptfs_revert_ext_volume(const char* label);
 int cryptfs_getfield(const char* fieldname, char* value, int len);
 int cryptfs_setfield(const char* fieldname, const char* value);
diff --git a/fscrypt_uapi.h b/fscrypt_uapi.h
new file mode 100644
index 0000000..08592e0
--- /dev/null
+++ b/fscrypt_uapi.h
@@ -0,0 +1,19 @@
+#ifndef _UAPI_LINUX_FSCRYPT_VOLD_H
+#define _UAPI_LINUX_FSCRYPT_VOLD_H
+
+#include <linux/fscrypt.h>
+#include <linux/types.h>
+
+#define FSCRYPT_ADD_KEY_FLAG_WRAPPED 0x01
+
+struct sys_fscrypt_add_key_arg {
+    struct fscrypt_key_specifier key_spec;
+    __u32 raw_size;
+    __u32 __reserved[8];
+    __u32 flags;
+    __u8 raw[];
+};
+
+#define fscrypt_add_key_arg sys_fscrypt_add_key_arg
+
+#endif  //_UAPI_LINUX_FSCRYPT_VOLD_H
diff --git a/model/Disk.cpp b/model/Disk.cpp
index f8357a9..3f3a84d 100644
--- a/model/Disk.cpp
+++ b/model/Disk.cpp
@@ -227,7 +227,8 @@
 
     LOG(DEBUG) << "Found key for GUID " << normalizedGuid;
 
-    auto vol = std::shared_ptr<VolumeBase>(new PrivateVolume(device, keyRaw));
+    auto keyBuffer = KeyBuffer(keyRaw.begin(), keyRaw.end());
+    auto vol = std::shared_ptr<VolumeBase>(new PrivateVolume(device, keyBuffer));
     if (mJustPartitioned) {
         LOG(DEBUG) << "Device just partitioned; silently formatting";
         vol->setSilent(true);
diff --git a/model/PrivateVolume.cpp b/model/PrivateVolume.cpp
index 03aa5fa..650888e 100644
--- a/model/PrivateVolume.cpp
+++ b/model/PrivateVolume.cpp
@@ -43,7 +43,7 @@
 
 static const unsigned int kMajorBlockMmc = 179;
 
-PrivateVolume::PrivateVolume(dev_t device, const std::string& keyRaw)
+PrivateVolume::PrivateVolume(dev_t device, const KeyBuffer& keyRaw)
     : VolumeBase(Type::kPrivate), mRawDevice(device), mKeyRaw(keyRaw) {
     setId(StringPrintf("private:%u,%u", major(device), minor(device)));
     mRawDevPath = StringPrintf("/dev/block/vold/%s", getId().c_str());
@@ -64,19 +64,13 @@
     if (CreateDeviceNode(mRawDevPath, mRawDevice)) {
         return -EIO;
     }
-    if (mKeyRaw.size() != cryptfs_get_keysize()) {
-        PLOG(ERROR) << getId() << " Raw keysize " << mKeyRaw.size()
-                    << " does not match crypt keysize " << cryptfs_get_keysize();
-        return -EIO;
-    }
 
     // Recover from stale vold by tearing down any old mappings
     cryptfs_revert_ext_volume(getId().c_str());
 
     // TODO: figure out better SELinux labels for private volumes
 
-    unsigned char* key = (unsigned char*)mKeyRaw.data();
-    int res = cryptfs_setup_ext_volume(getId().c_str(), mRawDevPath.c_str(), key, &mDmDevPath);
+    int res = cryptfs_setup_ext_volume(getId().c_str(), mRawDevPath.c_str(), mKeyRaw, &mDmDevPath);
     if (res != 0) {
         PLOG(ERROR) << getId() << " failed to setup cryptfs";
         return -EIO;
diff --git a/model/PrivateVolume.h b/model/PrivateVolume.h
index 656172f..9780485 100644
--- a/model/PrivateVolume.h
+++ b/model/PrivateVolume.h
@@ -37,7 +37,7 @@
  */
 class PrivateVolume : public VolumeBase {
   public:
-    PrivateVolume(dev_t device, const std::string& keyRaw);
+    PrivateVolume(dev_t device, const KeyBuffer& keyRaw);
     virtual ~PrivateVolume();
     const std::string& getFsType() const { return mFsType; };
     const std::string& getRawDevPath() const { return mRawDevPath; };
@@ -65,7 +65,7 @@
     std::string mPath;
 
     /* Encryption key as raw bytes */
-    std::string mKeyRaw;
+    KeyBuffer mKeyRaw;
 
     /* Filesystem type */
     std::string mFsType;