Merge "V4 uses V2 digest if V3 is not available." into rvc-dev

core/java/android/os/incremental/V4Signature.java

@@ -72,16 +72,16 @@ public class V4Signature {
      * V4 signature data.
      */
     public static class SigningInfo {
-        public final byte[] v3Digest;  // used to match with the corresponding APK
+        public final byte[] apkDigest;  // used to match with the corresponding APK
         public final byte[] certificate; // ASN.1 DER form
         public final byte[] additionalData; // a free-form binary data blob
         public final byte[] publicKey; // ASN.1 DER, must match the certificate
         public final int signatureAlgorithmId; // see the APK v2 doc for the list
         public final byte[] signature;
 
-        SigningInfo(byte[] v3Digest, byte[] certificate, byte[] additionalData,
+        SigningInfo(byte[] apkDigest, byte[] certificate, byte[] additionalData,
                 byte[] publicKey, int signatureAlgorithmId, byte[] signature) {
-            this.v3Digest = v3Digest;
+            this.apkDigest = apkDigest;
             this.certificate = certificate;
             this.additionalData = additionalData;
             this.publicKey = publicKey;
@@ -94,13 +94,13 @@ public class V4Signature {
          */
         public static SigningInfo fromByteArray(byte[] bytes) throws IOException {
             ByteBuffer buffer = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
-            byte[] v3Digest = readBytes(buffer);
+            byte[] apkDigest = readBytes(buffer);
             byte[] certificate = readBytes(buffer);
             byte[] additionalData = readBytes(buffer);
             byte[] publicKey = readBytes(buffer);
             int signatureAlgorithmId = buffer.getInt();
             byte[] signature = readBytes(buffer);
-            return new SigningInfo(v3Digest, certificate, additionalData, publicKey,
+            return new SigningInfo(apkDigest, certificate, additionalData, publicKey,
                     signatureAlgorithmId, signature);
         }
     }
@@ -150,7 +150,7 @@ public class V4Signature {
         final int size =
                 4/*size*/ + 8/*fileSize*/ + 4/*hash_algorithm*/ + 1/*log2_blocksize*/ + bytesSize(
                         hashingInfo.salt) + bytesSize(hashingInfo.rawRootHash) + bytesSize(
-                        signingInfo.v3Digest) + bytesSize(signingInfo.certificate) + bytesSize(
+                        signingInfo.apkDigest) + bytesSize(signingInfo.certificate) + bytesSize(
                         signingInfo.additionalData);
         ByteBuffer buffer = ByteBuffer.allocate(size).order(ByteOrder.LITTLE_ENDIAN);
         buffer.putInt(size);
@@ -159,7 +159,7 @@ public class V4Signature {
         buffer.put(hashingInfo.log2BlockSize);
         writeBytes(buffer, hashingInfo.salt);
         writeBytes(buffer, hashingInfo.rawRootHash);
-        writeBytes(buffer, signingInfo.v3Digest);
+        writeBytes(buffer, signingInfo.apkDigest);
         writeBytes(buffer, signingInfo.certificate);
         writeBytes(buffer, signingInfo.additionalData);
         return buffer.array();

core/java/android/util/apk/ApkSignatureSchemeV2Verifier.java

@@ -24,6 +24,7 @@ import static android.util.apk.ApkSigningBlockUtils.getSignatureAlgorithmContent
 import static android.util.apk.ApkSigningBlockUtils.getSignatureAlgorithmJcaKeyAlgorithm;
 import static android.util.apk.ApkSigningBlockUtils.getSignatureAlgorithmJcaSignatureAlgorithm;
 import static android.util.apk.ApkSigningBlockUtils.isSupportedSignatureAlgorithm;
+import static android.util.apk.ApkSigningBlockUtils.pickBestDigestForV4;
 import static android.util.apk.ApkSigningBlockUtils.readLengthPrefixedByteArray;
 
 import android.util.ArrayMap;
@@ -117,7 +118,10 @@ public class ApkSignatureSchemeV2Verifier {
         return vSigner.certs;
     }
 
-    private static VerifiedSigner verify(String apkFile, boolean verifyIntegrity)
+    /**
+     * Same as above returns the full signer object, containing additional info e.g. digest.
+     */
+    public static VerifiedSigner verify(String apkFile, boolean verifyIntegrity)
             throws SignatureNotFoundException, SecurityException, IOException {
         try (RandomAccessFile apk = new RandomAccessFile(apkFile, "r")) {
             return verify(apk, verifyIntegrity);
@@ -209,9 +213,11 @@ public class ApkSignatureSchemeV2Verifier {
                     verityDigest, apk.length(), signatureInfo);
         }
 
+        byte[] digest = pickBestDigestForV4(contentDigests);
+
         return new VerifiedSigner(
                 signerCerts.toArray(new X509Certificate[signerCerts.size()][]),
-                verityRootHash);
+                verityRootHash, digest);
     }
 
     private static X509Certificate[] verifySigner(
@@ -426,11 +432,14 @@ public class ApkSignatureSchemeV2Verifier {
      */
     public static class VerifiedSigner {
         public final X509Certificate[][] certs;
-        public final byte[] verityRootHash;
 
-        public VerifiedSigner(X509Certificate[][] certs, byte[] verityRootHash) {
+        public final byte[] verityRootHash;
+        public final byte[] digest;
+
+        public VerifiedSigner(X509Certificate[][] certs, byte[] verityRootHash, byte[] digest) {
             this.certs = certs;
             this.verityRootHash = verityRootHash;
+            this.digest = digest;
         }
 
     }

core/java/android/util/apk/ApkSignatureSchemeV3Verifier.java

@@ -16,8 +16,6 @@
 
 package android.util.apk;
 
-import static android.util.apk.ApkSigningBlockUtils.CONTENT_DIGEST_CHUNKED_SHA256;
-import static android.util.apk.ApkSigningBlockUtils.CONTENT_DIGEST_CHUNKED_SHA512;
 import static android.util.apk.ApkSigningBlockUtils.CONTENT_DIGEST_VERITY_CHUNKED_SHA256;
 import static android.util.apk.ApkSigningBlockUtils.compareSignatureAlgorithm;
 import static android.util.apk.ApkSigningBlockUtils.getContentDigestAlgorithmJcaDigestAlgorithm;
@@ -26,6 +24,7 @@ import static android.util.apk.ApkSigningBlockUtils.getSignatureAlgorithmContent
 import static android.util.apk.ApkSigningBlockUtils.getSignatureAlgorithmJcaKeyAlgorithm;
 import static android.util.apk.ApkSigningBlockUtils.getSignatureAlgorithmJcaSignatureAlgorithm;
 import static android.util.apk.ApkSigningBlockUtils.isSupportedSignatureAlgorithm;
+import static android.util.apk.ApkSigningBlockUtils.pickBestDigestForV4;
 import static android.util.apk.ApkSigningBlockUtils.readLengthPrefixedByteArray;
 
 import android.os.Build;
@@ -213,24 +212,11 @@ public class ApkSignatureSchemeV3Verifier {
                     verityDigest, apk.length(), signatureInfo);
         }
 
-        result.digest = pickBestV3DigestForV4(contentDigests);
+        result.digest = pickBestDigestForV4(contentDigests);
 
         return result;
     }
 
-    // Keep in sync with pickBestV3DigestForV4 in apksigner.V3SchemeVerifier.
-    private static byte[] pickBestV3DigestForV4(Map<Integer, byte[]> contentDigests) {
-        final int[] orderedContentDigestTypes =
-                {CONTENT_DIGEST_CHUNKED_SHA512, CONTENT_DIGEST_VERITY_CHUNKED_SHA256,
-                        CONTENT_DIGEST_CHUNKED_SHA256};
-        for (int contentDigestType : orderedContentDigestTypes) {
-            if (contentDigests.containsKey(contentDigestType)) {
-                return contentDigests.get(contentDigestType);
-            }
-        }
-        return null;
-    }
-
     private static VerifiedSigner verifySigner(
             ByteBuffer signerBlock,
             Map<Integer, byte[]> contentDigests,

core/java/android/util/apk/ApkSignatureSchemeV4Verifier.java

@@ -145,7 +145,7 @@ public class ApkSignatureSchemeV4Verifier {
                     "Public key mismatch between certificate and signature record");
         }
 
-        return new VerifiedSigner(new Certificate[]{certificate}, signingInfo.v3Digest);
+        return new VerifiedSigner(new Certificate[]{certificate}, signingInfo.apkDigest);
     }
 
     /**
@@ -155,11 +155,11 @@ public class ApkSignatureSchemeV4Verifier {
      */
     public static class VerifiedSigner {
         public final Certificate[] certs;
-        public byte[] v3Digest;
+        public byte[] apkDigest;
 
-        public VerifiedSigner(Certificate[] certs, byte[] v3Digest) {
+        public VerifiedSigner(Certificate[] certs, byte[] apkDigest) {
             this.certs = certs;
-            this.v3Digest = v3Digest;
+            this.apkDigest = apkDigest;
         }
 
     }

core/java/android/util/apk/ApkSignatureVerifier.java

@@ -184,27 +184,45 @@ public class ApkSignatureVerifier {
             Signature[] signerSigs = convertToSignatures(signerCerts);
 
             if (verifyFull) {
-                // v4 is an add-on and requires v3 signature to validate against its certificates
+                byte[] nonstreamingDigest = null;
-                ApkSignatureSchemeV3Verifier.VerifiedSigner nonstreaming =
+                Certificate[][] nonstreamingCerts = null;
-                        ApkSignatureSchemeV3Verifier.unsafeGetCertsWithoutVerification(apkPath);
-                Certificate[][] nonstreamingCerts = new Certificate[][]{nonstreaming.certs};
-                Signature[] nonstreamingSigs = convertToSignatures(nonstreamingCerts);
 
+                try {
+                    // v4 is an add-on and requires v2 or v3 signature to validate against its
+                    // certificate and digest
+                    ApkSignatureSchemeV3Verifier.VerifiedSigner v3Signer =
+                            ApkSignatureSchemeV3Verifier.unsafeGetCertsWithoutVerification(apkPath);
+                    nonstreamingDigest = v3Signer.digest;
+                    nonstreamingCerts = new Certificate[][]{v3Signer.certs};
+                } catch (SignatureNotFoundException e) {
+                    try {
+                        ApkSignatureSchemeV2Verifier.VerifiedSigner v2Signer =
+                                ApkSignatureSchemeV2Verifier.verify(apkPath, false);
+                        nonstreamingDigest = v2Signer.digest;
+                        nonstreamingCerts = v2Signer.certs;
+                    } catch (SignatureNotFoundException ee) {
+                        throw new SecurityException(
+                                "V4 verification failed to collect V2/V3 certificates from : "
+                                        + apkPath, ee);
+                    }
+                }
+
+                Signature[] nonstreamingSigs = convertToSignatures(nonstreamingCerts);
                 if (nonstreamingSigs.length != signerSigs.length) {
                     throw new SecurityException(
-                            "Invalid number of certificates: " + nonstreaming.certs.length);
+                            "Invalid number of certificates: " + nonstreamingSigs.length);
                 }
 
                 for (int i = 0, size = signerSigs.length; i < size; ++i) {
                     if (!nonstreamingSigs[i].equals(signerSigs[i])) {
-                        throw new SecurityException("V4 signature certificate does not match V3");
+                        throw new SecurityException(
+                                "V4 signature certificate does not match V2/V3");
                     }
                 }
 
-                // TODO(b/151240006): add support for v2 digest and make it mandatory.
+                if (!ArrayUtils.equals(vSigner.apkDigest, nonstreamingDigest,
-                if (!ArrayUtils.isEmpty(vSigner.v3Digest) && !ArrayUtils.equals(vSigner.v3Digest,
+                        vSigner.apkDigest.length)) {
-                        nonstreaming.digest, vSigner.v3Digest.length)) {
+                    throw new SecurityException("APK digest in V4 signature does not match V2/V3");
-                    throw new SecurityException("V3 digest in V4 signature does not match V3");
                 }
             }
 

core/java/android/util/apk/ApkSigningBlockUtils.java

@@ -421,6 +421,10 @@ final class ApkSigningBlockUtils {
     static final int CONTENT_DIGEST_CHUNKED_SHA512 = 2;
     static final int CONTENT_DIGEST_VERITY_CHUNKED_SHA256 = 3;
 
+    private static final int[] V4_CONTENT_DIGEST_ALGORITHMS =
+            {CONTENT_DIGEST_CHUNKED_SHA512, CONTENT_DIGEST_VERITY_CHUNKED_SHA256,
+                    CONTENT_DIGEST_CHUNKED_SHA256};
+
     static int compareSignatureAlgorithm(int sigAlgorithm1, int sigAlgorithm2) {
         int digestAlgorithm1 = getSignatureAlgorithmContentDigestAlgorithm(sigAlgorithm1);
         int digestAlgorithm2 = getSignatureAlgorithmContentDigestAlgorithm(sigAlgorithm2);
@@ -571,6 +575,21 @@ final class ApkSigningBlockUtils {
         }
     }
 
+    /**
+     * Returns the best digest from the map of available digests.
+     * similarly to compareContentDigestAlgorithm.
+     *
+     * Keep in sync with pickBestDigestForV4 in apksigner's ApkSigningBlockUtils.
+     */
+    static byte[] pickBestDigestForV4(Map<Integer, byte[]> contentDigests) {
+        for (int algo : V4_CONTENT_DIGEST_ALGORITHMS) {
+            if (contentDigests.containsKey(algo)) {
+                return contentDigests.get(algo);
+            }
+        }
+        return null;
+    }
+
     /**
      * Returns new byte buffer whose content is a shared subsequence of this buffer's content
      * between the specified start (inclusive) and end (exclusive) positions. As opposed to