Workaround Gitiles bug on All-Users visibility

Gitiles has special FilteredRepository wrapper that
allows to carefully hide refs based on the project's ACLs.
There is however an optimisation that skips the filtering
in case a user has READ permissions on every ACLs patterns.

When the target repository is All-Users, the optimisation
turns into a security issue because it allows seeing everything
that belongs to everyone:
- draft comments
- PII of all users
- external ids
- draft edits

Block Gitiles or any other part of Gerrit to abuse of this
power when the target repository is All-Users, where nobody
can be authorised to skip the ACLs evaluation.

Cover the additional special case of the All-Users project
access with two explicit positive and negative tests,
so that the security check is covered.

Bug: Issue 13621
Change-Id: Ia6ea1a9fd5473adff534204aea7d8f25324a45b7
(cherry picked from commit 45071d6977)

gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectControl.java

@@ -39,6 +39,7 @@ import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.account.GroupMembership;
+import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.config.GitReceivePackGroups;
 import com.google.gerrit.server.config.GitUploadPackGroups;
 import com.google.gerrit.server.git.GitRepositoryManager;
@@ -140,6 +141,7 @@ public class ProjectControl {
   private final RefVisibilityControl refVisibilityControl;
   private final VisibleRefFilter.Factory visibleRefFilterFactory;
   private final GitRepositoryManager gitRepositoryManager;
+  private final AllUsersName allUsersName;
 
   private List<SectionMatcher> allSections;
   private Map<String, RefControl> refControls;
@@ -156,6 +158,7 @@ public class ProjectControl {
       RefVisibilityControl refVisibilityControl,
       GitRepositoryManager gitRepositoryManager,
       VisibleRefFilter.Factory visibleRefFilterFactory,
+      AllUsersName allUsersName,
       @Assisted CurrentUser who,
       @Assisted ProjectState ps) {
     this.changeControlFactory = changeControlFactory;
@@ -167,6 +170,7 @@ public class ProjectControl {
     this.refVisibilityControl = refVisibilityControl;
     this.gitRepositoryManager = gitRepositoryManager;
     this.visibleRefFilterFactory = visibleRefFilterFactory;
+    this.allUsersName = allUsersName;
     user = who;
     state = ps;
   }
@@ -262,7 +266,9 @@ public class ProjectControl {
   }
 
   private boolean allRefsAreVisible(Set<String> ignore) {
-    return user.isInternalUser() || canPerformOnAllRefs(Permission.READ, ignore);
+    return user.isInternalUser()
+        || (!getProject().getNameKey().equals(allUsersName)
+            && canPerformOnAllRefs(Permission.READ, ignore));
   }
 
   /** Returns whether the project is hidden. */

gerrit-server/src/test/java/com/google/gerrit/server/project/RefControlTest.java

@@ -61,6 +61,7 @@ import com.google.gerrit.server.git.TransferConfig;
 import com.google.gerrit.server.git.VisibleRefFilter;
 import com.google.gerrit.server.index.SingleVersionModule.SingleVersionListener;
 import com.google.gerrit.server.permissions.PermissionBackend;
+import com.google.gerrit.server.permissions.PermissionBackendException;
 import com.google.gerrit.server.permissions.ProjectPermission;
 import com.google.gerrit.server.permissions.RefPermission;
 import com.google.gerrit.server.permissions.RefVisibilityControl;
@@ -110,6 +111,16 @@ public class RefControlTest {
     assertThat(u.controlForRef(ref).isOwner()).named("NOT OWN " + ref).isFalse();
   }
 
+  private void assertAllRefsAreVisible(ProjectControl u) throws PermissionBackendException {
+    assertThat(u.asForProject().test(ProjectPermission.READ)).named("all refs visible").isTrue();
+  }
+
+  private void assertAllRefsAreNotVisible(ProjectControl u) throws PermissionBackendException {
+    assertThat(u.asForProject().test(ProjectPermission.READ))
+        .named("all refs NOT visible")
+        .isFalse();
+  }
+
   private void assertCanAccess(ProjectControl u) {
     boolean access = u.asForProject().testOrFalse(ProjectPermission.ACCESS);
     assertThat(access).named("can access").isTrue();
@@ -199,6 +210,7 @@ public class RefControlTest {
   private final Map<Project.NameKey, ProjectState> all = new HashMap<>();
   private Project.NameKey localKey = new Project.NameKey("local");
   private ProjectConfig local;
+  private ProjectConfig allUsers;
   private Project.NameKey parentKey = new Project.NameKey("parent");
   private ProjectConfig parent;
   private InMemoryRepositoryManager repoManager;
@@ -230,7 +242,7 @@ public class RefControlTest {
 
           @Override
           public ProjectState getAllUsers() {
-            return null;
+            return get(allUsersName);
           }
 
           @Override
@@ -290,6 +302,11 @@ public class RefControlTest {
       LabelType cr = Util.codeReview();
       allProjects.getLabelSections().put(cr.getName(), cr);
       add(allProjects);
+
+      Repository allUsersRepo = repoManager.createRepository(allUsersName);
+      allUsers = new ProjectConfig(new Project.NameKey(allUsersName.get()));
+      allUsers.load(allUsersRepo);
+      add(allUsers);
     } catch (IOException | ConfigInvalidException e) {
       throw new RuntimeException(e);
     }
@@ -363,6 +380,24 @@ public class RefControlTest {
     assertAdminsAreOwnersAndDevsAreNot();
   }
 
+  @Test
+  public void allRefsAreVisibleForRegularProject() throws Exception {
+    allow(local, READ, DEVS, "refs/*");
+    allow(local, READ, DEVS, "refs/groups/*");
+    allow(local, READ, DEVS, "refs/users/default");
+
+    assertAllRefsAreVisible(user(local, DEVS));
+  }
+
+  @Test
+  public void allRefsAreNotVisibleForAllUsers() throws Exception {
+    allow(allUsers, READ, DEVS, "refs/*");
+    allow(allUsers, READ, DEVS, "refs/groups/*");
+    allow(allUsers, READ, DEVS, "refs/users/default");
+
+    assertAllRefsAreNotVisible(user(allUsers, DEVS));
+  }
+
   @Test
   public void branchDelegation1() {
     allow(local, OWNER, ADMIN, "refs/*");
@@ -897,6 +932,7 @@ public class RefControlTest {
         refVisibilityControl,
         gitRepositoryManager,
         visibleRefFilterFactory,
+        allUsersName,
         new MockUser(name, memberOf),
         newProjectState(local));
   }