Block APK rejoining shared UID by dropping sharedUserMaxSdkVersion

Not only should the APK not change its sharedUserId declaration, it
shall also not be allowed to rejoin shared UID.

Test: atest SharedUserMigrationTest#testAppInstall
Bug: 221088088
Change-Id: I4b5d76179d9ed17d333f46b4dc4d7d12b470d130

1 files changed, 7 insertions, 0 deletions

diff --git a/services/core/java/com/android/server/pm/InstallPackageHelper.java b/services/core/java/com/android/server/pm/InstallPackageHelper.java
index db0b0c58b046..54c201945be6 100644
--- a/services/core/java/com/android/server/pm/InstallPackageHelper.java
+++ b/services/core/java/com/android/server/pm/InstallPackageHelper.java
@@ -1607,6 +1607,13 @@ final class InstallPackageHelper {
                                         + oldSharedUid + " to " + newSharedUid);
                     }
 
+                    // APK should not re-join shared UID
+                    if (oldPackage.isLeavingSharedUid() && !parsedPackage.isLeavingSharedUid()) {
+                        throw new PrepareFailure(INSTALL_FAILED_UID_CHANGED,
+                                "Package " + parsedPackage.getPackageName()
+                                        + " attempting to rejoin " + newSharedUid);
+                    }
+
                     // In case of rollback, remember per-user/profile install state
                     allUsers = mPm.mUserManager.getUserIds();
                     installedUsers = ps.queryInstalledUsers(allUsers, true);