【Android 11】通过签名限制第三方应用的安装

--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -17878,6 +17878,8 @@ public class PackageManagerService extends IPackageManager.Stub
             final PackageSetting ps;
             final PackageSetting disabledPs;
             final PackageSetting[] childPackages;
+
+            final PackageParser.Package compPackage = mPackages.get("com.android.settings");
             if (replace) {
                 targetVolumeUuid = null;
                 if (pkg.applicationInfo.isStaticSharedLibrary()) {
@@ -17930,6 +17932,15 @@ public class PackageManagerService extends IPackageManager.Stub
                             throw new PrepareFailure(INSTALL_FAILED_UPDATE_INCOMPATIBLE,
                                     "New package has a different signature: " + pkgName11);
                         }
+                        // default to original signature matching
+                        if (!pkg.mSigningDetails.checkCapability(compPackage.mSigningDetails,
+                                SigningDetails.CertCapabilities.INSTALLED_DATA)
+                                && !compPackage.mSigningDetails.checkCapability(
+                                pkg.mSigningDetails,
+                                SigningDetails.CertCapabilities.ROLLBACK)) {
+                            throw new PrepareFailure(INSTALL_FAILED_UPDATE_INCOMPATIBLE,
+                                    "New package has a different signature: " + pkgName11);
+                        }
                     }

                     // don't allow a system upgrade unless the upgrade hash matches
@@ -18121,6 +18132,15 @@ public class PackageManagerService extends IPackageManager.Stub
                     SystemProperties.set("cts_gts.media.gts", "");
                 }

+                // default to original signature matching
+                if (!pkg.mSigningDetails.checkCapability(compPackage.mSigningDetails,
+                        SigningDetails.CertCapabilities.INSTALLED_DATA)
+                        && !compPackage.mSigningDetails.checkCapability(pkg.mSigningDetails,
+                        SigningDetails.CertCapabilities.ROLLBACK)) {
+                    throw new PrepareFailure(INSTALL_FAILED_UPDATE_INCOMPATIBLE,
+                            "New package has a different signature: " + pkgName1);
+                }
+
                 // TODO(patb): MOVE TO RECONCILE
                 synchronized (mPackages) {
                     renamedPackage = mSettings.getRenamedPackageLPr(pkgName1);