backend/src/services/db.service.ts

@@ -176,6 +176,49 @@ export interface RepetitionRule {
 // Add new entries at the END. Never edit or remove existing entries.
 // Convention for id: "YYYYMMDD_short_description"
 // ---------------------------------------------------------------------------
+/**
+ * Per-table allowlists of columns the HTTP `PUT /artists|albums|tracks/:id`
+ * endpoints may write.
+ *
+ * These endpoints pass `request.body as any` straight through, and the update
+ * builders interpolate `Object.keys(body)` into the SET clause as quoted
+ * identifiers — so without an allowlist a crafted key both closes the quoted
+ * identifier (SQL injection) and mass-assigns columns that are not user-editable.
+ *
+ * Deliberately excluded:
+ *  - `tracks.path` / `tracks.hash` / `tracks.mtime` — owned by the scanner; the
+ *    path is the only link to the file on the read-only `/music` bind.
+ *  - `tracks.state` / `quarantined_at` / `deleted_at` — owned by the dislike
+ *    lifecycle and the integrity sweep, not by metadata editing.
+ *  - `play_count` / `skip_count` / `dislike_count` / `last_played_at` — learning
+ *    signal; forgeable counters would poison the recommendation engine.
+ *  - `source_type` — decides library vs. recommendation semantics.
+ *  - `id` / `created_at` / `updated_at` and every generated column
+ *    (`normalized_name`, `normalized_artist` — Postgres rejects writes anyway).
+ */
+const UPDATABLE_COLUMNS = {
+  artists: ['name', 'canonical_name', 'sort_name', 'mbid', 'discogs_id', 'image_path'],
+  albums: ['artist_id', 'title', 'year', 'release_date', 'artwork_id', 'mbid'],
+  tracks: ['title', 'artist', 'album_id', 'duration', 'release_date'],
+} as const;
+
+/**
+ * Filter a partial update payload down to the allowlisted, defined columns for
+ * `table`. Unknown keys are dropped silently rather than raising: the callers
+ * take `Partial<T>` and the routes do no error mapping, so a 500 on an extra
+ * key would be worse than a no-op. The subsequent "No fields to update" throw
+ * still surfaces a payload that was *entirely* rejected.
+ */
+function allowedFields<T extends object>(
+  table: keyof typeof UPDATABLE_COLUMNS,
+  data: T
+): (keyof T & string)[] {
+  const allowed = UPDATABLE_COLUMNS[table] as readonly string[];
+  return Object.keys(data).filter(
+    (k) => allowed.includes(k) && (data as any)[k] !== undefined
+  ) as (keyof T & string)[];
+}
+
 const MIGRATIONS: { id: string; sql: string }[] = [
   {
     id: '20260608_track_artists',
@@ -1244,7 +1287,7 @@ export class DbService {
   }
 
   async updateArtist(id: string, data: Partial<Artist>): Promise<Artist> {
-    const fields = Object.keys(data).filter(k => data[k as keyof Artist] !== undefined);
+    const fields = allowedFields('artists', data);
     if (fields.length === 0) throw new Error('No fields to update');
 
     // Normalize name if it's being updated (the normalized_name generated column
@@ -1277,7 +1320,7 @@ export class DbService {
   }
 
   async updateAlbum(id: string, data: Partial<Album>): Promise<Album> {
-    const fields = Object.keys(data).filter(k => data[k as keyof Album] !== undefined);
+    const fields = allowedFields('albums', data);
     if (fields.length === 0) throw new Error('No fields to update');
     
     const setClause = fields.map((f, i) => `"${f}" = $${i + 2}`).join(', ');
@@ -1320,7 +1363,7 @@ export class DbService {
   }
 
   async updateTrack(id: string, data: Partial<Track>): Promise<Track> {
-    const fields = Object.keys(data).filter(k => data[k as keyof Track] !== undefined);
+    const fields = allowedFields('tracks', data);
     if (fields.length === 0) throw new Error('No fields to update');
     
     const setClause = fields.map((f, i) => `"${f}" = $${i + 2}`).join(', ');