Restrict people, genres, studios and artists to names backed by an item the user can access

Jellyfin.Server.Implementations/Item/BaseItemRepository.TranslateQuery.cs

@@ -1050,14 +1050,29 @@ public sealed partial class BaseItemRepository
         {
             var includedItemByNameTypes = GetItemByNameTypesInQuery(filter);
             var enableItemsByName = (filter.IncludeItemsByName ?? false) && includedItemByNameTypes.Count > 0;
-            if (enableItemsByName && includedItemByNameTypes.Count > 0)
+
+            // A by-name item belongs to no library, so it has no TopParentId to test and the filter
+            // below would drop it. Items-by-name queries exempt the whole group; a query that names a
+            // by-name type explicitly gets the same exemption, since it is asking for those items.
+            var exemptedItemByNameTypes = enableItemsByName
+                ? includedItemByNameTypes
+                : _itemByNameKinds.Where(filter.IncludeItemTypes.Contains).Select(e => _itemTypeLookup.BaseItemKindNames[e]!).ToList();
+
+            if (exemptedItemByNameTypes.Count > 0)
             {
-                baseQuery = baseQuery.Where(e => includedItemByNameTypes.Contains(e.Type) || queryTopParentIds.Any(w => w == e.TopParentId!.Value));
+                baseQuery = baseQuery.Where(e => exemptedItemByNameTypes.Contains(e.Type) || queryTopParentIds.Any(w => w == e.TopParentId!.Value));
             }
             else
             {
                 baseQuery = baseQuery.WhereOneOrMany(queryTopParentIds, e => e.TopParentId!.Value);
             }
+
+            // That exemption is what lets a by-name item from a library the user cannot open show up
+            // in search. Decide those on the items behind the name instead.
+            if (filter.UserHasContentRestrictions && exemptedItemByNameTypes.Count > 0)
+            {
+                baseQuery = ApplyItemByNameAccessFiltering(baseQuery, context, filter, exemptedItemByNameTypes, queryTopParentIds);
+            }
         }
 
         if (filter.AncestorIds.Length > 0)
@@ -1272,4 +1287,47 @@ public sealed partial class BaseItemRepository
 
         return baseQuery;
     }
+
+    /// <summary>
+    /// Keeps a by-name row only when at least one item behind its name is reachable for the user.
+    /// </summary>
+    private IQueryable<BaseItemEntity> ApplyItemByNameAccessFiltering(
+        IQueryable<BaseItemEntity> baseQuery,
+        JellyfinDbContext context,
+        InternalItemsQuery filter,
+        IReadOnlyList<string> itemByNameTypes,
+        Guid[] topParentIds)
+    {
+        // IncludeOwnedItems: a credit on an alternate version of a reachable movie still counts.
+        var accessibleItems = ApplyAccessFiltering(
+            context,
+            context.BaseItems.AsNoTracking(),
+            new InternalItemsQuery(filter.User) { TopParentIds = topParentIds, IncludeOwnedItems = true });
+
+        // Each predicate is written outside-in - name row, then link table, then item - and with nested
+        // Any() rather than a Contains over the accessible ids, which would materialise all of them
+        // before the first row. That keeps every step an index seek.
+        var personType = _itemTypeLookup.BaseItemKindNames[BaseItemKind.Person];
+        if (itemByNameTypes.Contains(personType))
+        {
+            baseQuery = baseQuery.Where(e => e.Type != personType
+                || context.Peoples.Any(p => p.Name == e.Name
+                    && context.PeopleBaseItemMap.Any(m => m.PeopleId == p.Id && accessibleItems.Any(i => i.Id == m.ItemId))));
+        }
+
+        foreach (var (kind, valueTypes) in _itemByNameValueTypes)
+        {
+            var typeName = _itemTypeLookup.BaseItemKindNames[kind];
+            if (!itemByNameTypes.Contains(typeName))
+            {
+                continue;
+            }
+
+            baseQuery = baseQuery.Where(e => e.Type != typeName
+                || context.ItemValues.Any(v => valueTypes.Contains(v.Type) && v.CleanValue == e.CleanName
+                    && context.ItemValuesMap.Any(m => m.ItemValueId == v.ItemValueId && accessibleItems.Any(i => i.Id == m.ItemId))));
+        }
+
+        return baseQuery;
+    }
 }