| /* |
| * Copyright (C) 2019 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.integrity.parser; |
| |
| import static com.android.server.integrity.model.ComponentBitSize.ATOMIC_FORMULA_START; |
| import static com.android.server.integrity.model.ComponentBitSize.COMPOUND_FORMULA_END; |
| import static com.android.server.integrity.model.ComponentBitSize.COMPOUND_FORMULA_START; |
| import static com.android.server.integrity.model.ComponentBitSize.CONNECTOR_BITS; |
| import static com.android.server.integrity.model.ComponentBitSize.EFFECT_BITS; |
| import static com.android.server.integrity.model.ComponentBitSize.FORMAT_VERSION_BITS; |
| import static com.android.server.integrity.model.ComponentBitSize.IS_HASHED_BITS; |
| import static com.android.server.integrity.model.ComponentBitSize.KEY_BITS; |
| import static com.android.server.integrity.model.ComponentBitSize.OPERATOR_BITS; |
| import static com.android.server.integrity.model.ComponentBitSize.SEPARATOR_BITS; |
| import static com.android.server.integrity.model.ComponentBitSize.SIGNAL_BIT; |
| import static com.android.server.integrity.model.ComponentBitSize.VALUE_SIZE_BITS; |
| |
| import android.content.integrity.AtomicFormula; |
| import android.content.integrity.CompoundFormula; |
| import android.content.integrity.Formula; |
| import android.content.integrity.Rule; |
| |
| import com.android.server.integrity.IntegrityUtils; |
| import com.android.server.integrity.model.BitInputStream; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.nio.ByteBuffer; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** A helper class to parse rules into the {@link Rule} model from Binary representation. */ |
| public class RuleBinaryParser implements RuleParser { |
| |
| private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray(); |
| |
| @Override |
| public List<Rule> parse(byte[] ruleBytes) throws RuleParseException { |
| try { |
| BitInputStream bitInputStream = new BitInputStream(ruleBytes); |
| return parseRules(bitInputStream); |
| } catch (Exception e) { |
| throw new RuleParseException(e.getMessage(), e); |
| } |
| } |
| |
| @Override |
| public List<Rule> parse(InputStream inputStream) throws RuleParseException { |
| try { |
| BitInputStream bitInputStream = new BitInputStream(inputStream); |
| return parseRules(bitInputStream); |
| } catch (Exception e) { |
| throw new RuleParseException(e.getMessage(), e); |
| } |
| } |
| |
| private List<Rule> parseRules(BitInputStream bitInputStream) throws IOException { |
| List<Rule> parsedRules = new ArrayList<>(); |
| |
| // Read the rule binary file format version. |
| bitInputStream.getNext(FORMAT_VERSION_BITS); |
| |
| while (bitInputStream.hasNext()) { |
| if (bitInputStream.getNext(SIGNAL_BIT) == 1) { |
| parsedRules.add(parseRule(bitInputStream)); |
| } |
| } |
| |
| return parsedRules; |
| } |
| |
| private Rule parseRule(BitInputStream bitInputStream) throws IOException { |
| Formula formula = parseFormula(bitInputStream); |
| int effect = bitInputStream.getNext(EFFECT_BITS); |
| |
| if (bitInputStream.getNext(SIGNAL_BIT) != 1) { |
| throw new IllegalArgumentException("A rule must end with a '1' bit."); |
| } |
| |
| return new Rule(formula, effect); |
| } |
| |
| private Formula parseFormula(BitInputStream bitInputStream) throws IOException { |
| int separator = bitInputStream.getNext(SEPARATOR_BITS); |
| switch (separator) { |
| case ATOMIC_FORMULA_START: |
| return parseAtomicFormula(bitInputStream); |
| case COMPOUND_FORMULA_START: |
| return parseCompoundFormula(bitInputStream); |
| case COMPOUND_FORMULA_END: |
| return null; |
| default: |
| throw new IllegalArgumentException( |
| String.format("Unknown formula separator: %s", separator)); |
| } |
| } |
| |
| private CompoundFormula parseCompoundFormula(BitInputStream bitInputStream) throws IOException { |
| int connector = bitInputStream.getNext(CONNECTOR_BITS); |
| List<Formula> formulas = new ArrayList<>(); |
| |
| Formula parsedFormula = parseFormula(bitInputStream); |
| while (parsedFormula != null) { |
| formulas.add(parsedFormula); |
| parsedFormula = parseFormula(bitInputStream); |
| } |
| |
| return new CompoundFormula(connector, formulas); |
| } |
| |
| private AtomicFormula parseAtomicFormula(BitInputStream bitInputStream) throws IOException { |
| int key = bitInputStream.getNext(KEY_BITS); |
| int operator = bitInputStream.getNext(OPERATOR_BITS); |
| |
| switch (key) { |
| case AtomicFormula.PACKAGE_NAME: |
| case AtomicFormula.APP_CERTIFICATE: |
| case AtomicFormula.INSTALLER_NAME: |
| case AtomicFormula.INSTALLER_CERTIFICATE: |
| boolean isHashedValue = bitInputStream.getNext(IS_HASHED_BITS) == 1; |
| int valueSize = bitInputStream.getNext(VALUE_SIZE_BITS); |
| String stringValue = getStringValue(bitInputStream, valueSize, isHashedValue); |
| return new AtomicFormula.StringAtomicFormula(key, stringValue, isHashedValue); |
| case AtomicFormula.VERSION_CODE: |
| int intValue = getIntValue(bitInputStream); |
| return new AtomicFormula.IntAtomicFormula(key, operator, intValue); |
| case AtomicFormula.PRE_INSTALLED: |
| boolean booleanValue = getBooleanValue(bitInputStream); |
| return new AtomicFormula.BooleanAtomicFormula(key, booleanValue); |
| default: |
| throw new IllegalArgumentException(String.format("Unknown key: %d", key)); |
| } |
| } |
| |
| // Get value string from stream. |
| // If the value is not hashed, get its raw form directly. |
| // If the value is hashed, get the hex-encoding of the value. Serialized values are in raw form. |
| // All hashed values are hex-encoded. |
| private static String getStringValue( |
| BitInputStream bitInputStream, int valueSize, boolean isHashedValue) |
| throws IOException { |
| if (!isHashedValue) { |
| StringBuilder value = new StringBuilder(); |
| while (valueSize-- > 0) { |
| value.append((char) bitInputStream.getNext(/* numOfBits= */ 8)); |
| } |
| return value.toString(); |
| } |
| ByteBuffer byteBuffer = ByteBuffer.allocate(valueSize); |
| while (valueSize-- > 0) { |
| byteBuffer.put((byte) (bitInputStream.getNext(/* numOfBits= */ 8) & 0xFF)); |
| } |
| return IntegrityUtils.getHexDigest(byteBuffer.array()); |
| } |
| |
| private static int getIntValue(BitInputStream bitInputStream) throws IOException { |
| return bitInputStream.getNext(/* numOfBits= */ 32); |
| } |
| |
| private static boolean getBooleanValue(BitInputStream bitInputStream) throws IOException { |
| return bitInputStream.getNext(/* numOfBits= */ 1) == 1; |
| } |
| } |