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/*
* Copyright (C) 2017 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.
*/
package com.android.server.locksettings.recoverablekeystore.storage;
import android.annotation.Nullable;
import android.util.SparseArray;
import java.util.ArrayList;
import java.util.Arrays;
import javax.security.auth.Destroyable;
/**
* Stores pending recovery sessions in memory. We do not write these to disk, as it contains hashes
* of the user's lock screen.
*
* @hide
*/
public class RecoverySessionStorage implements Destroyable {
private final SparseArray<ArrayList<Entry>> mSessionsByUid = new SparseArray<>();
/**
* Returns the session for the given user with the given id.
*
* @param uid The uid of the recovery agent who created the session.
* @param sessionId The unique identifier for the session.
* @return The session info.
*
* @hide
*/
@Nullable
public Entry get(int uid, String sessionId) {
ArrayList<Entry> userEntries = mSessionsByUid.get(uid);
if (userEntries == null) {
return null;
}
for (Entry entry : userEntries) {
if (sessionId.equals(entry.mSessionId)) {
return entry;
}
}
return null;
}
/**
* Adds a pending session for the given user.
*
* @param uid The uid of the recovery agent who created the session.
* @param entry The session info.
*
* @hide
*/
public void add(int uid, Entry entry) {
if (mSessionsByUid.get(uid) == null) {
mSessionsByUid.put(uid, new ArrayList<>());
}
mSessionsByUid.get(uid).add(entry);
}
/**
* Deletes the session with {@code sessionId} created by app with {@code uid}.
*/
public void remove(int uid, String sessionId) {
if (mSessionsByUid.get(uid) == null) {
return;
}
mSessionsByUid.get(uid).removeIf(session -> session.mSessionId.equals(sessionId));
}
/**
* Removes all sessions associated with the given recovery agent uid.
*
* @param uid The uid of the recovery agent whose sessions to remove.
*
* @hide
*/
public void remove(int uid) {
ArrayList<Entry> entries = mSessionsByUid.get(uid);
if (entries == null) {
return;
}
for (Entry entry : entries) {
entry.destroy();
}
mSessionsByUid.remove(uid);
}
/**
* Returns the total count of pending sessions.
*
* @hide
*/
public int size() {
int size = 0;
int numberOfUsers = mSessionsByUid.size();
for (int i = 0; i < numberOfUsers; i++) {
ArrayList<Entry> entries = mSessionsByUid.valueAt(i);
size += entries.size();
}
return size;
}
/**
* Wipes the memory of any sensitive information (i.e., lock screen hashes and key claimants).
*
* @hide
*/
@Override
public void destroy() {
int numberOfUids = mSessionsByUid.size();
for (int i = 0; i < numberOfUids; i++) {
ArrayList<Entry> entries = mSessionsByUid.valueAt(i);
for (Entry entry : entries) {
entry.destroy();
}
}
}
/**
* Information about a recovery session.
*
* @hide
*/
public static class Entry implements Destroyable {
private final byte[] mLskfHash;
private final byte[] mKeyClaimant;
private final byte[] mVaultParams;
private final String mSessionId;
/**
* @hide
*/
public Entry(String sessionId, byte[] lskfHash, byte[] keyClaimant, byte[] vaultParams) {
mLskfHash = lskfHash;
mSessionId = sessionId;
mKeyClaimant = keyClaimant;
mVaultParams = vaultParams;
}
/**
* Returns the hash of the lock screen associated with the recovery attempt.
*
* @hide
*/
public byte[] getLskfHash() {
return mLskfHash;
}
/**
* Returns the key generated for this recovery attempt (used to decrypt data returned by
* the server).
*
* @hide
*/
public byte[] getKeyClaimant() {
return mKeyClaimant;
}
/**
* Returns the vault params associated with the session.
*
* @hide
*/
public byte[] getVaultParams() {
return mVaultParams;
}
/**
* Overwrites the memory for the lskf hash and key claimant.
*
* @hide
*/
@Override
public void destroy() {
Arrays.fill(mLskfHash, (byte) 0);
Arrays.fill(mKeyClaimant, (byte) 0);
}
}
}
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