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Recover apps with malformed certificates.

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There was a window of time in Lollipop where we persisted certificates
after they had passed through a decode/encode cycle.  The well-written
OpenSSL library was liberal when decoding (allowing slightly malformed
certs to be parsed), but then strict when encoding, giving us
different bytes for effectively the same certificate.

A related libcore change (0c990ab4a90b8a5492a67b2b728ac9a4a1ccfa1b)
now returns the original bytes verbatim, fixing both pre-Lollipop
installs and installs after that change.

This change recovers any apps that had been installed during the
window of time described above by doing a one-time check to see if
the certs are effectively equal.

Bug: 18228011
Change-Id: Ib82bd6db718d0490d7a26c9c1014b7c8457a7f2d
This commit is contained in:
Jeff Sharkey
2014-11-12 12:18:11 -08:00
parent 8d88f19bfe
commit d68b87cdd4
4 changed files with 164 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
core/java/android/content/pm/Signature.java
View File

@ -22,12 +22,14 @@ import android.os.Parcelable;
import com.android.internal.util.ArrayUtils;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.lang.ref.SoftReference;
import java.security.PublicKey;
import java.security.cert.Certificate;
import java.security.cert.CertificateEncodingException;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Arrays;
/**
@ -252,4 +254,53 @@ public class Signature implements Parcelable {
return (a.length == b.length) && ArrayUtils.containsAll(a, b)
&& ArrayUtils.containsAll(b, a);
}
/**
* Test if given {@link Signature} sets are effectively equal. In rare
* cases, certificates can have slightly malformed encoding which causes
* exact-byte checks to fail.
* <p>
* To identify effective equality, we bounce the certificates through an
* decode/encode pass before doing the exact-byte check. To reduce attack
* surface area, we only allow a byte size delta of a few bytes.
*
* @throws CertificateException if the before/after length differs
* substantially, usually a signal of something fishy going on.
* @hide
*/
public static boolean areEffectiveMatch(Signature[] a, Signature[] b)
throws CertificateException {
final CertificateFactory cf = CertificateFactory.getInstance("X.509");
final Signature[] aPrime = new Signature[a.length];
for (int i = 0; i < a.length; i++) {
aPrime[i] = bounce(cf, a[i]);
}
final Signature[] bPrime = new Signature[b.length];
for (int i = 0; i < b.length; i++) {
bPrime[i] = bounce(cf, b[i]);
}
return areExactMatch(aPrime, bPrime);
}
/**
* Bounce the given {@link Signature} through a decode/encode cycle.
*
* @throws CertificateException if the before/after length differs
* substantially, usually a signal of something fishy going on.
* @hide
*/
public static Signature bounce(CertificateFactory cf, Signature s) throws CertificateException {
final InputStream is = new ByteArrayInputStream(s.mSignature);
final X509Certificate cert = (X509Certificate) cf.generateCertificate(is);
final Signature sPrime = new Signature(cert.getEncoded());
if (Math.abs(sPrime.mSignature.length - s.mSignature.length) > 2) {
throw new CertificateException("Bounced cert length looks fishy; before "
+ s.mSignature.length + ", after " + sPrime.mSignature.length);
}
return sPrime;
}
}

57
core/tests/coretests/src/android/content/pm/SignatureTest.java Normal file
View File

@ -0,0 +1,57 @@
/*
* Copyright (C) 2014 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 android.content.pm;
import junit.framework.TestCase;
public class SignatureTest extends TestCase {
/** Cert A with valid syntax */
private static final Signature A = new Signature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
/** Cert A with malformed syntax */
private static final Signature M = new Signature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
/** Cert B with valid syntax */
private static final Signature B = new Signature("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");
public void testExactlyEqual() throws Exception {
assertTrue(Signature.areExactMatch(asArray(A), asArray(A)));
assertTrue(Signature.areExactMatch(asArray(M), asArray(M)));
assertFalse(Signature.areExactMatch(asArray(A), asArray(B)));
assertFalse(Signature.areExactMatch(asArray(A), asArray(M)));
assertFalse(Signature.areExactMatch(asArray(M), asArray(A)));
assertTrue(Signature.areExactMatch(asArray(A, M), asArray(M, A)));
}
public void testEffectiveMatch() throws Exception {
assertTrue(Signature.areEffectiveMatch(asArray(A), asArray(A)));
assertTrue(Signature.areEffectiveMatch(asArray(M), asArray(M)));
assertFalse(Signature.areEffectiveMatch(asArray(A), asArray(B)));
assertTrue(Signature.areEffectiveMatch(asArray(A), asArray(M)));
assertTrue(Signature.areEffectiveMatch(asArray(M), asArray(A)));
assertTrue(Signature.areEffectiveMatch(asArray(A, M), asArray(M, A)));
assertTrue(Signature.areEffectiveMatch(asArray(A, B), asArray(M, B)));
assertFalse(Signature.areEffectiveMatch(asArray(A, M), asArray(A, B)));
}
private static Signature[] asArray(Signature... s) {
return s;
}
}

49
services/core/java/com/android/server/pm/PackageManagerService.java
View File

@ -2860,6 +2860,38 @@ public class PackageManagerService extends IPackageManager.Stub {
return PackageManager.SIGNATURE_NO_MATCH;
}
private boolean isRecoverSignatureUpdateNeeded(PackageParser.Package scannedPkg) {
if (isExternal(scannedPkg)) {
return mSettings.isExternalDatabaseVersionOlderThan(
DatabaseVersion.SIGNATURE_MALFORMED_RECOVER);
} else {
return mSettings.isInternalDatabaseVersionOlderThan(
DatabaseVersion.SIGNATURE_MALFORMED_RECOVER);
}
}
private int compareSignaturesRecover(PackageSignatures existingSigs,
PackageParser.Package scannedPkg) {
if (!isRecoverSignatureUpdateNeeded(scannedPkg)) {
return PackageManager.SIGNATURE_NO_MATCH;
}
String msg = null;
try {
if (Signature.areEffectiveMatch(existingSigs.mSignatures, scannedPkg.mSignatures)) {
logCriticalInfo(Log.INFO, "Recovered effectively matching certificates for "
+ scannedPkg.packageName);
return PackageManager.SIGNATURE_MATCH;
}
} catch (CertificateException e) {
msg = e.getMessage();
}
logCriticalInfo(Log.INFO,
"Failed to recover certificates for " + scannedPkg.packageName + ": " + msg);
return PackageManager.SIGNATURE_NO_MATCH;
}
@Override
public String[] getPackagesForUid(int uid) {
uid = UserHandle.getAppId(uid);
@ -4148,7 +4180,8 @@ public class PackageManagerService extends IPackageManager.Stub {
if (ps != null
&& ps.codePath.equals(srcFile)
&& ps.timeStamp == srcFile.lastModified()
&& !isCompatSignatureUpdateNeeded(pkg)) {
&& !isCompatSignatureUpdateNeeded(pkg)
&& !isRecoverSignatureUpdateNeeded(pkg)) {
long mSigningKeySetId = ps.keySetData.getProperSigningKeySet();
if (ps.signatures.mSignatures != null
&& ps.signatures.mSignatures.length != 0
@ -4422,6 +4455,10 @@ public class PackageManagerService extends IPackageManager.Stub {
match = compareSignaturesCompat(pkgSetting.signatures, pkg)
== PackageManager.SIGNATURE_MATCH;
}
if (!match) {
match = compareSignaturesRecover(pkgSetting.signatures, pkg)
== PackageManager.SIGNATURE_MATCH;
}
if (!match) {
throw new PackageManagerException(INSTALL_FAILED_UPDATE_INCOMPATIBLE, "Package "
+ pkg.packageName + " signatures do not match the "
@ -4438,6 +4475,10 @@ public class PackageManagerService extends IPackageManager.Stub {
match = compareSignaturesCompat(pkgSetting.sharedUser.signatures, pkg)
== PackageManager.SIGNATURE_MATCH;
}
if (!match) {
match = compareSignaturesRecover(pkgSetting.sharedUser.signatures, pkg)
== PackageManager.SIGNATURE_MATCH;
}
if (!match) {
throw new PackageManagerException(INSTALL_FAILED_SHARED_USER_INCOMPATIBLE,
"Package " + pkg.packageName
@ -5386,6 +5427,9 @@ public class PackageManagerService extends IPackageManager.Stub {
if (!pkgSetting.keySetData.isUsingUpgradeKeySets() || pkgSetting.sharedUser != null) {
try {
verifySignaturesLP(pkgSetting, pkg);
// We just determined the app is signed correctly, so bring
// over the latest parsed certs.
pkgSetting.signatures.mSignatures = pkg.mSignatures;
} catch (PackageManagerException e) {
if ((parseFlags & PackageParser.PARSE_IS_SYSTEM_DIR) == 0) {
throw e;
@ -5418,7 +5462,8 @@ public class PackageManagerService extends IPackageManager.Stub {
+ pkg.packageName + " upgrade keys do not match the "
+ "previously installed version");
} else {
// signatures may have changed as result of upgrade
// We just determined the app is signed correctly, so bring
// over the latest parsed certs.
pkgSetting.signatures.mSignatures = pkg.mSignatures;
}
}

10
services/core/java/com/android/server/pm/Settings.java
View File

@ -103,7 +103,7 @@ final class Settings {
* Note that care should be taken to make sure all database upgrades are
* idempotent.
*/
private static final int CURRENT_DATABASE_VERSION = DatabaseVersion.SIGNATURE_END_ENTITY;
private static final int CURRENT_DATABASE_VERSION = DatabaseVersion.SIGNATURE_MALFORMED_RECOVER;
/**
* This class contains constants that can be referred to from upgrade code.
@ -121,6 +121,14 @@ final class Settings {
* just the signing certificate.
*/
public static final int SIGNATURE_END_ENTITY = 2;
/**
* There was a window of time in
* {@link android.os.Build.VERSION_CODES#LOLLIPOP} where we persisted
* certificates after potentially mutating them. To switch back to the
* original untouched certificates, we need to force a collection pass.
*/
public static final int SIGNATURE_MALFORMED_RECOVER = 3;
}
private static final boolean DEBUG_STOPPED = false;