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Commit 99266924 authored by Ömer Nebil Yaveroğlu's avatar Ömer Nebil Yaveroğlu Committed by Android (Google) Code Review
Browse files

Merge "Implement a tracked bit reader (BitTrackedInputStream) which is capable... 

Merge "Implement a tracked bit reader (BitTrackedInputStream) which is capable of moving the file reading cursor forward when needed."
parents c20fe0cc 918e0ec5

services/core/java/com/android/server/integrity/model/BitTrackedInputStream.java

0 → 100644
+69 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2020 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.model;



import java.io.IOException;

import java.io.InputStream;



/**

 * An input stream that tracks the total number read bytes since construction and allows moving

 * fast forward to a certain byte any time during the execution.

 *

 * This class is used for efficient reading of rules based on the rule indexing.

 */

public class BitTrackedInputStream extends BitInputStream {



    private static int sReadBitsCount;



    /** Constructor with byte array. */

    public BitTrackedInputStream(byte[] inputStream) {

        super(inputStream);

        sReadBitsCount = 0;

    }



    /** Constructor with input stream. */

    public BitTrackedInputStream(InputStream inputStream) {

        super(inputStream);

        sReadBitsCount = 0;

    }



    /** Obtains an integer value of the next {@code numOfBits}. */

    @Override

    public int getNext(int numOfBits) throws IOException {

        sReadBitsCount += numOfBits;

        return super.getNext(numOfBits);

    }



    /** Returns the current cursor position showing the number of bits that are read. */

    public int getReadBitsCount() {

        return sReadBitsCount;

    }



    /**

     * Sets the cursor to the specified byte location.

     *

     * Note that the integer parameter specifies the location in bytes -- not bits.

     */

    public void setCursorToByteLocation(int byteLocation) throws IOException {

        int bitCountToRead = byteLocation * 8 - sReadBitsCount;

        if (bitCountToRead < 0) {

            throw new IllegalStateException("The byte position is already read.");

        }

        super.getNext(bitCountToRead);

        sReadBitsCount = byteLocation * 8;

    }

}

services/core/java/com/android/server/integrity/serializer/ByteTrackedOutputStream.java→services/core/java/com/android/server/integrity/model/ByteTrackedOutputStream.java

+1 −1
Original line number Diff line number Diff line
@@ -14,7 +14,7 @@ 
 * limitations under the License.

 */



package com.android.server.integrity.serializer;

package com.android.server.integrity.model;



import java.io.IOException;

import java.io.OutputStream;

services/core/java/com/android/server/integrity/parser/RuleBinaryParser.java

+33 −32
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ import android.content.integrity.CompoundFormula; 
import android.content.integrity.Formula;

import android.content.integrity.Rule;



import com.android.server.integrity.model.BitInputStream;

import com.android.server.integrity.model.BitTrackedInputStream;



import java.io.IOException;

import java.io.InputStream;
@@ -47,13 +47,11 @@ 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);

            BitTrackedInputStream bitTrackedInputStream = new BitTrackedInputStream(ruleBytes);

            return parseRules(bitTrackedInputStream);

        } catch (Exception e) {

            throw new RuleParseException(e.getMessage(), e);

        }
@@ -62,46 +60,46 @@ public class RuleBinaryParser implements RuleParser { 
    @Override

    public List<Rule> parse(InputStream inputStream) throws RuleParseException {

        try {

            BitInputStream bitInputStream = new BitInputStream(inputStream);

            return parseRules(bitInputStream);

            BitTrackedInputStream bitTrackedInputStream = new BitTrackedInputStream(inputStream);

            return parseRules(bitTrackedInputStream);

        } catch (Exception e) {

            throw new RuleParseException(e.getMessage(), e);

        }

    }



    private List<Rule> parseRules(BitInputStream bitInputStream) throws IOException {

    private List<Rule> parseRules(BitTrackedInputStream bitTrackedInputStream) throws IOException {

        List<Rule> parsedRules = new ArrayList<>();



        // Read the rule binary file format version.

        bitInputStream.getNext(FORMAT_VERSION_BITS);

        bitTrackedInputStream.getNext(FORMAT_VERSION_BITS);



        while (bitInputStream.hasNext()) {

            if (bitInputStream.getNext(SIGNAL_BIT) == 1) {

                parsedRules.add(parseRule(bitInputStream));

        while (bitTrackedInputStream.hasNext()) {

            if (bitTrackedInputStream.getNext(SIGNAL_BIT) == 1) {

                parsedRules.add(parseRule(bitTrackedInputStream));

            }

        }



        return parsedRules;

    }



    private Rule parseRule(BitInputStream bitInputStream) throws IOException {

        Formula formula = parseFormula(bitInputStream);

        int effect = bitInputStream.getNext(EFFECT_BITS);

    private Rule parseRule(BitTrackedInputStream bitTrackedInputStream) throws IOException {

        Formula formula = parseFormula(bitTrackedInputStream);

        int effect = bitTrackedInputStream.getNext(EFFECT_BITS);



        if (bitInputStream.getNext(SIGNAL_BIT) != 1) {

        if (bitTrackedInputStream.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);

    private Formula parseFormula(BitTrackedInputStream bitTrackedInputStream) throws IOException {

        int separator = bitTrackedInputStream.getNext(SEPARATOR_BITS);

        switch (separator) {

            case ATOMIC_FORMULA_START:

                return parseAtomicFormula(bitInputStream);

                return parseAtomicFormula(bitTrackedInputStream);

            case COMPOUND_FORMULA_START:

                return parseCompoundFormula(bitInputStream);

                return parseCompoundFormula(bitTrackedInputStream);

            case COMPOUND_FORMULA_END:

                return null;

            default:
@@ -110,37 +108,40 @@ public class RuleBinaryParser implements RuleParser { 
        }

    }



    private CompoundFormula parseCompoundFormula(BitInputStream bitInputStream) throws IOException {

        int connector = bitInputStream.getNext(CONNECTOR_BITS);

    private CompoundFormula parseCompoundFormula(BitTrackedInputStream bitTrackedInputStream)

            throws IOException {

        int connector = bitTrackedInputStream.getNext(CONNECTOR_BITS);

        List<Formula> formulas = new ArrayList<>();



        Formula parsedFormula = parseFormula(bitInputStream);

        Formula parsedFormula = parseFormula(bitTrackedInputStream);

        while (parsedFormula != null) {

            formulas.add(parsedFormula);

            parsedFormula = parseFormula(bitInputStream);

            parsedFormula = parseFormula(bitTrackedInputStream);

        }



        return new CompoundFormula(connector, formulas);

    }



    private AtomicFormula parseAtomicFormula(BitInputStream bitInputStream) throws IOException {

        int key = bitInputStream.getNext(KEY_BITS);

        int operator = bitInputStream.getNext(OPERATOR_BITS);

    private AtomicFormula parseAtomicFormula(BitTrackedInputStream bitTrackedInputStream)

            throws IOException {

        int key = bitTrackedInputStream.getNext(KEY_BITS);

        int operator = bitTrackedInputStream.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);

                boolean isHashedValue = bitTrackedInputStream.getNext(IS_HASHED_BITS) == 1;

                int valueSize = bitTrackedInputStream.getNext(VALUE_SIZE_BITS);

                String stringValue = getStringValue(bitTrackedInputStream, valueSize,

                        isHashedValue);

                return new AtomicFormula.StringAtomicFormula(key, stringValue, isHashedValue);

            case AtomicFormula.VERSION_CODE:

                int intValue = getIntValue(bitInputStream);

                int intValue = getIntValue(bitTrackedInputStream);

                return new AtomicFormula.IntAtomicFormula(key, operator, intValue);

            case AtomicFormula.PRE_INSTALLED:

                boolean booleanValue = getBooleanValue(bitInputStream);

                boolean booleanValue = getBooleanValue(bitTrackedInputStream);

                return new AtomicFormula.BooleanAtomicFormula(key, booleanValue);

            default:

                throw new IllegalArgumentException(String.format("Unknown key: %d", key));

services/core/java/com/android/server/integrity/serializer/RuleBinarySerializer.java

+3 −1
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ import android.content.integrity.Rule; 
import com.android.internal.util.Preconditions;

import com.android.server.integrity.IntegrityUtils;

import com.android.server.integrity.model.BitOutputStream;

import com.android.server.integrity.model.ByteTrackedOutputStream;



import java.io.ByteArrayOutputStream;

import java.io.IOException;
@@ -109,7 +110,8 @@ public class RuleBinarySerializer implements RuleSerializer { 
    }



    private void serializeRuleFileMetadata(Optional<Integer> formatVersion,

            ByteTrackedOutputStream outputStream) throws IOException {

            ByteTrackedOutputStream outputStream)

            throws IOException {

        int formatVersionValue = formatVersion.orElse(DEFAULT_FORMAT_VERSION);



        BitOutputStream bitOutputStream = new BitOutputStream();

services/tests/servicestests/src/com/android/server/integrity/model/BitTrackedInputStreamTest.java

0 → 100644
+142 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2020 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.model;



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.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.VALUE_SIZE_BITS;

import static com.android.server.integrity.utils.TestUtils.getBits;

import static com.android.server.integrity.utils.TestUtils.getBytes;

import static com.android.server.integrity.utils.TestUtils.getValueBits;



import static com.google.common.truth.Truth.assertThat;



import static org.testng.Assert.assertThrows;



import android.content.integrity.AtomicFormula;

import android.content.integrity.CompoundFormula;

import android.content.integrity.Rule;



import com.android.server.integrity.parser.BinaryFileOperations;



import org.junit.Test;

import org.junit.runner.RunWith;

import org.junit.runners.JUnit4;



import java.io.IOException;



@RunWith(JUnit4.class)

public class BitTrackedInputStreamTest {

    private static final String COMPOUND_FORMULA_START_BITS =

            getBits(COMPOUND_FORMULA_START, SEPARATOR_BITS);

    private static final String COMPOUND_FORMULA_END_BITS =

            getBits(COMPOUND_FORMULA_END, SEPARATOR_BITS);

    private static final String ATOMIC_FORMULA_START_BITS =

            getBits(ATOMIC_FORMULA_START, SEPARATOR_BITS);

    private static final String NOT = getBits(CompoundFormula.NOT, CONNECTOR_BITS);

    private static final String PACKAGE_NAME = getBits(AtomicFormula.PACKAGE_NAME, KEY_BITS);

    private static final String EQ = getBits(AtomicFormula.EQ, OPERATOR_BITS);

    private static final String DENY = getBits(Rule.DENY, EFFECT_BITS);



    private static final String IS_NOT_HASHED = "0";

    private static final String START_BIT = "1";

    private static final String END_BIT = "1";



    @Test

    public void testBitOperationsCountBitsCorrectly() throws IOException {

        String packageName = "com.test.app";

        byte[] testInput =

                getBytes(

                        START_BIT

                                + COMPOUND_FORMULA_START_BITS

                                + NOT

                                + ATOMIC_FORMULA_START_BITS

                                + PACKAGE_NAME

                                + EQ

                                + IS_NOT_HASHED

                                + getBits(packageName.length(), VALUE_SIZE_BITS)

                                + getValueBits(packageName)

                                + COMPOUND_FORMULA_END_BITS

                                + DENY

                                + END_BIT);



        BitTrackedInputStream bitTrackedInputStream = new BitTrackedInputStream(testInput);



        // Right after construction, the read bits count should be 0.

        assertThat(bitTrackedInputStream.getReadBitsCount()).isEqualTo(0);



        // Get next 10 bits should result with 10 bits read.

        bitTrackedInputStream.getNext(10);

        assertThat(bitTrackedInputStream.getReadBitsCount()).isEqualTo(10);



        // When we move the cursor 8 bytes, we should point to 64 bits.

        bitTrackedInputStream.setCursorToByteLocation(8);

        assertThat(bitTrackedInputStream.getReadBitsCount()).isEqualTo(64);



        // Read until the end and the total size of the input stream should be available.

        while (bitTrackedInputStream.hasNext()) {

            bitTrackedInputStream.getNext(1);

        }

        assertThat(bitTrackedInputStream.getReadBitsCount()).isEqualTo(128);

    }



    @Test

    public void testBitInputStreamOperationsStillWork() throws IOException {

        String packageName = "com.test.app";

        byte[] testInput =

                getBytes(

                        IS_NOT_HASHED

                                + getBits(packageName.length(), VALUE_SIZE_BITS)

                                + getValueBits(packageName));



        BitTrackedInputStream bitTrackedInputStream = new BitTrackedInputStream(testInput);

        assertThat(bitTrackedInputStream.getReadBitsCount()).isEqualTo(0);



        // Read until the string parameter.

        String stringValue = BinaryFileOperations.getStringValue(bitTrackedInputStream);



        // Verify that the read bytes are counted.

        assertThat(stringValue).isEqualTo(packageName);

        assertThat(bitTrackedInputStream.getReadBitsCount()).isGreaterThan(0);

    }



    @Test

    public void testBitTrackedInputStream_moveCursorForwardFailsIfAlreadyRead() throws IOException {

        String packageName = "com.test.app";

        byte[] testInput =

                getBytes(

                        IS_NOT_HASHED

                                + getBits(packageName.length(), VALUE_SIZE_BITS)

                                + getValueBits(packageName));



        BitTrackedInputStream bitTrackedInputStream = new BitTrackedInputStream(testInput);



        // Read more than two bytes.

        bitTrackedInputStream.getNext(20);



        // Ask to move the cursor to the second byte.

        assertThrows(

                IllegalStateException.class,

                () -> bitTrackedInputStream.setCursorToByteLocation(2));

    }

}