From 10d19e98081bec0e2ee5274f2c46d02d036ce89f Mon Sep 17 00:00:00 2001
From: Daniel Cashman <dcashman@google.com>
Date: Wed, 28 Mar 2018 15:58:14 -0700
Subject: [PATCH] Require signing cert history certs to be unique.

Bug: 73943012
Test: android.appsecurity.cts.PkgInstallSignatureVerificationTest
Change-Id: Id7e91c60f1619ef793d73a9dd736debf7ad2ae0c
(cherry picked from commit ef05408bcdcb32d005f91ca295a1e514845a58f4)
---
 .../util/apk/ApkSignatureSchemeV3Verifier.java     |  8 +++++++
 .../android/util/apk/VerbatimX509Certificate.java  | 28 ++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/core/java/android/util/apk/ApkSignatureSchemeV3Verifier.java b/core/java/android/util/apk/ApkSignatureSchemeV3Verifier.java
index 4431bcef1ff4..758cd2b877f2 100644
--- a/core/java/android/util/apk/ApkSignatureSchemeV3Verifier.java
+++ b/core/java/android/util/apk/ApkSignatureSchemeV3Verifier.java
@@ -62,6 +62,7 @@ import java.security.spec.InvalidKeySpecException;
 import java.security.spec.X509EncodedKeySpec;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 
@@ -457,6 +458,7 @@ public class ApkSignatureSchemeV3Verifier {
 
             // get the version code, but don't do anything with it: creator knew about all our flags
             porBuf.getInt();
+            HashSet<X509Certificate> certHistorySet = new HashSet<>();
             while (porBuf.hasRemaining()) {
                 levelCount++;
                 ByteBuffer level = getLengthPrefixedSlice(porBuf);
@@ -495,6 +497,12 @@ public class ApkSignatureSchemeV3Verifier {
                 lastCert = new VerbatimX509Certificate(lastCert, encodedCert);
 
                 lastSigAlgorithm = sigAlgorithm;
+                if (certHistorySet.contains(lastCert)) {
+                    throw new SecurityException("Encountered duplicate entries in "
+                            + "Proof-of-rotation record at certificate #" + levelCount + ".  All "
+                            + "signing certificates should be unique");
+                }
+                certHistorySet.add(lastCert);
                 certs.add(lastCert);
                 flagsList.add(flags);
             }
diff --git a/core/java/android/util/apk/VerbatimX509Certificate.java b/core/java/android/util/apk/VerbatimX509Certificate.java
index 9984c6d26c64..391c5fc39416 100644
--- a/core/java/android/util/apk/VerbatimX509Certificate.java
+++ b/core/java/android/util/apk/VerbatimX509Certificate.java
@@ -18,6 +18,7 @@ package android.util.apk;
 
 import java.security.cert.CertificateEncodingException;
 import java.security.cert.X509Certificate;
+import java.util.Arrays;
 
 /**
  * For legacy reasons we need to return exactly the original encoded certificate bytes, instead
@@ -25,6 +26,7 @@ import java.security.cert.X509Certificate;
  */
 class VerbatimX509Certificate extends WrappedX509Certificate {
     private final byte[] mEncodedVerbatim;
+    private int mHash = -1;
 
     VerbatimX509Certificate(X509Certificate wrapped, byte[] encodedVerbatim) {
         super(wrapped);
@@ -35,4 +37,30 @@ class VerbatimX509Certificate extends WrappedX509Certificate {
     public byte[] getEncoded() throws CertificateEncodingException {
         return mEncodedVerbatim;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof VerbatimX509Certificate)) return false;
+
+        try {
+            byte[] a = this.getEncoded();
+            byte[] b = ((VerbatimX509Certificate) o).getEncoded();
+            return Arrays.equals(a, b);
+        } catch (CertificateEncodingException e) {
+            return false;
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        if (mHash == -1) {
+            try {
+                mHash = Arrays.hashCode(this.getEncoded());
+            } catch (CertificateEncodingException e) {
+                mHash = 0;
+            }
+        }
+        return mHash;
+    }
 }
-- 
2.11.0