From 2e1245013f5bdfcad8a8f93cc67e6bdaf70b804e Mon Sep 17 00:00:00 2001
From: Jackal Guo <jackalguo@google.com>
Date: Tue, 13 Dec 2022 15:06:00 +0800
Subject: [PATCH] Handle update-ownership tag

For update ownership enforcement, using the config to enable the
enforcement for the system apps.

A config is expected to have "update-ownership" tags per package:
```
<config>
    <update-ownership package="foo" installer="bar" />
</config>
```

Bug: 244413073
Test: atest FrameworksServicesTests:SystemConfigTest
Change-Id: I38e996eb885a130f72f656b27731d9f31b16b366
---
 .../java/com/android/server/SystemConfig.java | 25 +++++++++
 .../server/systemconfig/SystemConfigTest.java | 52 +++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/services/core/java/com/android/server/SystemConfig.java b/services/core/java/com/android/server/SystemConfig.java
index 75788f219d589..2fc07129435be 100644
--- a/services/core/java/com/android/server/SystemConfig.java
+++ b/services/core/java/com/android/server/SystemConfig.java
@@ -329,6 +329,8 @@ public class SystemConfig {
     private final Set<String> mInstallConstraintsAllowlist = new ArraySet<>();
 
     private String mModulesInstallerPackageName;
+    // Update ownership for system applications and the installers eligible to update them.
+    private final ArrayMap<String, String> mUpdateOwnersForSystemApps = new ArrayMap<>();
 
     /**
      * Map of system pre-defined, uniquely named actors; keys are namespace,
@@ -475,6 +477,13 @@ public class SystemConfig {
         return mModulesInstallerPackageName;
     }
 
+    /**
+     * Gets the update owner of the given package from "update-ownership" tags in sysconfig.
+     */
+    public @Nullable String getSystemAppUpdateOwnerPackageName(@NonNull String packageName) {
+        return mUpdateOwnersForSystemApps.get(packageName);
+    }
+
     public ArraySet<String> getAppDataIsolationWhitelistedApps() {
         return mAppDataIsolationWhitelistedApps;
     }
@@ -1405,6 +1414,22 @@ public class SystemConfig {
                         }
                         XmlUtils.skipCurrentTag(parser);
                     } break;
+                    case "update-ownership": {
+                        final String packageName = parser.getAttributeValue(null /* namespace */,
+                                "package");
+                        final String installerName = parser.getAttributeValue(null /* namespace */,
+                                "installer");
+                        if (TextUtils.isEmpty(packageName)) {
+                            Slog.w(TAG, "<" + name + "> without valid package in " + permFile
+                                    + " at " + parser.getPositionDescription());
+                        } else if (TextUtils.isEmpty(installerName)) {
+                            Slog.w(TAG, "<" + name + "> without valid installer in " + permFile
+                                    + " at " + parser.getPositionDescription());
+                        } else {
+                            mUpdateOwnersForSystemApps.put(packageName, installerName);
+                        }
+                        XmlUtils.skipCurrentTag(parser);
+                    } break;
                     default: {
                         Slog.w(TAG, "Tag " + name + " is unknown in "
                                 + permFile + " at " + parser.getPositionDescription());
diff --git a/services/tests/servicestests/src/com/android/server/systemconfig/SystemConfigTest.java b/services/tests/servicestests/src/com/android/server/systemconfig/SystemConfigTest.java
index 16c213c77d108..d073f5bfebe47 100644
--- a/services/tests/servicestests/src/com/android/server/systemconfig/SystemConfigTest.java
+++ b/services/tests/servicestests/src/com/android/server/systemconfig/SystemConfigTest.java
@@ -594,6 +594,58 @@ public class SystemConfigTest {
         assertFooIsOnlySharedLibrary();
     }
 
+    /**
+     * Tests that readPermissions works correctly for the tag: {@code update-ownership}.
+     */
+    @Test
+    public void readPermissions_updateOwnership_successful() throws IOException {
+        final String contents =
+                "<config>\n"
+                        + "    <update-ownership package=\"com.foo\" installer=\"com.bar\" />\n"
+                        + "</config>";
+        final File folder = createTempSubfolder("folder");
+        createTempFile(folder, "update_ownership.xml", contents);
+
+        readPermissions(folder, /* Grant all permission flags */ ~0);
+
+        assertThat(mSysConfig.getSystemAppUpdateOwnerPackageName("com.foo"))
+                .isEqualTo("com.bar");
+    }
+
+    /**
+     * Tests that readPermissions works correctly for the tag: {@code update-ownership}.
+     */
+    @Test
+    public void readPermissions_updateOwnership_noPackage() throws IOException {
+        final String contents =
+                "<config>\n"
+                        + "    <update-ownership />\n"
+                        + "</config>";
+        final File folder = createTempSubfolder("folder");
+        createTempFile(folder, "update_ownership.xml", contents);
+
+        readPermissions(folder, /* Grant all permission flags */ ~0);
+
+        assertThat(mSysConfig.getSystemAppUpdateOwnerPackageName("com.foo")).isNull();
+    }
+
+    /**
+     * Tests that readPermissions works correctly for the tag: {@code update-ownership}.
+     */
+    @Test
+    public void readPermissions_updateOwnership_noInstaller() throws IOException {
+        final String contents =
+                "<config>\n"
+                        + "    <update-ownership package=\"com.foo\" />\n"
+                        + "</config>";
+        final File folder = createTempSubfolder("folder");
+        createTempFile(folder, "update_ownership.xml", contents);
+
+        readPermissions(folder, /* Grant all permission flags */ ~0);
+
+        assertThat(mSysConfig.getSystemAppUpdateOwnerPackageName("com.foo")).isNull();
+    }
+
     private void parseSharedLibraries(String contents) throws IOException {
         File folder = createTempSubfolder("permissions_folder");
         createTempFile(folder, "permissions.xml", contents);