Merge "vold: Support Storage keys for FBE" am: 8cfb530357

Change-Id: I933a31eefe57b8b06513ca3e7a2ee874a1b680a1

FsCrypt.cpp

@@ -208,6 +208,19 @@ static bool get_data_file_encryption_options(EncryptionOptions* options) {
     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 =
@@ -231,7 +244,7 @@ static bool read_and_install_user_ce_key(userid_t user_id,
     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;
@@ -261,8 +274,8 @@ static bool create_and_install_user_keys(userid_t user_id, bool create_ephemeral
     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);
@@ -282,10 +295,10 @@ static bool create_and_install_user_keys(userid_t user_id, bool create_ephemeral
             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;
@@ -338,7 +351,7 @@ static bool load_all_de_keys() {
             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;
         }
@@ -360,12 +373,11 @@ bool fscrypt_initialize_systemwide_keys() {
 
     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)) {
@@ -380,10 +392,9 @@ bool fscrypt_initialize_systemwide_keys() {
     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;
@@ -590,8 +601,9 @@ static bool read_or_create_volkey(const std::string& misc_path, const std::strin
     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;
 }
 

KeyStorage.cpp

@@ -135,6 +135,30 @@ static bool generateKeymasterKey(Keymaster& keymaster, const KeyAuthentication&
            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()

KeyStorage.h

@@ -68,6 +68,11 @@ bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, KeyBuffe
 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
 

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 @@ bool randomKey(KeyBuffer* key) {
     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 @@ bool installKey(const std::string& mountpoint, const EncryptionOptions& options,
             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 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) {
+                 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 @@ bool retrieveKey(bool create_if_absent, const KeyAuthentication& key_authenticat
             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;

KeyUtil.h

@@ -32,6 +32,8 @@ using namespace android::fscrypt;
 
 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 installKey(const std::string& mountpoint, const EncryptionOptions& options,
 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

Keymaster.cpp

@@ -138,6 +138,27 @@ bool Keymaster::generateKey(const km::AuthorizationSet& inParams, std::string* k
     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);

Keymaster.h

@@ -114,6 +114,8 @@ class Keymaster {
     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.

MetadataCrypt.cpp

@@ -113,6 +113,23 @@ static void commit_key(const std::string& dir) {
     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 @@ static bool read_key(const FstabEntry& data_rec, bool create_if_absent, KeyBuffe
             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;
 }

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