Merge "KeyUtil: don't use keepOld=true for system DE and volume keys" am: 4a969dba60 am: 1d692f3b7b
Original change: https://android-review.googlesource.com/c/platform/system/vold/+/1480696
Change-Id: Idec4eb2c0afca69c0b322935397bea009f5683f1
diff --git a/FsCrypt.cpp b/FsCrypt.cpp
index 45edc9d..9189953 100644
--- a/FsCrypt.cpp
+++ b/FsCrypt.cpp
@@ -198,7 +198,7 @@
auto const paths = get_ce_key_paths(directory_path);
for (auto const ce_key_path : paths) {
LOG(DEBUG) << "Trying user CE key " << ce_key_path;
- if (retrieveKey(ce_key_path, auth, ce_key)) {
+ if (retrieveKey(ce_key_path, auth, ce_key, false)) {
LOG(DEBUG) << "Successfully retrieved key";
fixate_user_ce_key(directory_path, ce_key_path, paths);
return true;
@@ -398,7 +398,7 @@
userid_t user_id = std::stoi(entry->d_name);
auto key_path = de_dir + "/" + entry->d_name;
KeyBuffer de_key;
- if (!retrieveKey(key_path, kEmptyAuthentication, &de_key)) return false;
+ if (!retrieveKey(key_path, kEmptyAuthentication, &de_key, false)) return false;
EncryptionPolicy de_policy;
if (!install_storage_key(DATA_MNT_POINT, options, de_key, &de_policy)) return false;
auto ret = s_de_policies.insert({user_id, de_policy});
@@ -432,7 +432,7 @@
KeyBuffer device_key;
if (!retrieveOrGenerateKey(device_key_path, device_key_temp, kEmptyAuthentication,
- makeGen(options), &device_key))
+ makeGen(options), &device_key, false))
return false;
EncryptionPolicy device_policy;
@@ -666,7 +666,7 @@
EncryptionOptions options;
if (!get_volume_file_encryption_options(&options)) return false;
KeyBuffer key;
- if (!retrieveOrGenerateKey(key_path, key_path + "_tmp", auth, makeGen(options), &key))
+ if (!retrieveOrGenerateKey(key_path, key_path + "_tmp", auth, makeGen(options), &key, false))
return false;
if (!install_storage_key(BuildDataPath(volume_uuid), options, key, policy)) return false;
return true;
@@ -685,12 +685,12 @@
auto const directory_path = get_ce_key_directory_path(user_id);
KeyBuffer ce_key;
std::string ce_key_current_path = get_ce_key_current_path(directory_path);
- if (retrieveKey(ce_key_current_path, retrieve_auth, &ce_key)) {
+ if (retrieveKey(ce_key_current_path, retrieve_auth, &ce_key, false)) {
LOG(DEBUG) << "Successfully retrieved key";
// TODO(147732812): Remove this once Locksettingservice is fixed.
// Currently it calls fscrypt_clear_user_key_auth with a secret when lockscreen is
// changed from swipe to none or vice-versa
- } else if (retrieveKey(ce_key_current_path, kEmptyAuthentication, &ce_key)) {
+ } else if (retrieveKey(ce_key_current_path, kEmptyAuthentication, &ce_key, false)) {
LOG(DEBUG) << "Successfully retrieved key with empty auth";
} else {
LOG(ERROR) << "Failed to retrieve key for user " << user_id;
diff --git a/KeyStorage.h b/KeyStorage.h
index f9d3ec6..5228f08 100644
--- a/KeyStorage.h
+++ b/KeyStorage.h
@@ -61,8 +61,20 @@
const KeyAuthentication& auth, const KeyBuffer& key);
// Retrieve the key from the named directory.
+//
+// If the key is wrapped by a Keymaster key that requires an upgrade, then that
+// Keymaster key is upgraded. If |keepOld| is false, then the upgraded
+// Keymaster key replaces the original one. As part of this, the original is
+// deleted from Keymaster; however, if a user data checkpoint is active, this
+// part is delayed until the checkpoint is committed.
+//
+// If instead |keepOld| is true, then the upgraded key doesn't actually replace
+// the original one. This is needed *only* if |dir| isn't located in /data and
+// a user data checkpoint is active. In this case the caller must handle
+// replacing the original key if the checkpoint is committed, and deleting the
+// upgraded key if the checkpoint is rolled back.
bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, KeyBuffer* key,
- bool keepOld = false);
+ bool keepOld);
// Securely destroy the key stored in the named directory and delete the directory.
bool destroyKey(const std::string& dir);
diff --git a/KeyUtil.h b/KeyUtil.h
index 23278c1..0f5bc93 100644
--- a/KeyUtil.h
+++ b/KeyUtil.h
@@ -74,9 +74,11 @@
// responsible for dropping caches.
bool evictKey(const std::string& mountpoint, const EncryptionPolicy& policy);
+// Retrieves the key from the named directory, or generates it if it doesn't
+// exist. In most cases |keepOld| must be false; see retrieveKey() for details.
bool retrieveOrGenerateKey(const std::string& key_path, const std::string& tmp_path,
const KeyAuthentication& key_authentication, const KeyGeneration& gen,
- KeyBuffer* key, bool keepOld = true);
+ KeyBuffer* key, bool keepOld);
// Re-installs a file-based encryption key of fscrypt-provisioning type from the
// global session keyring back into fs keyring of the mountpoint.