🐛 Validate library belongs to same team in link/unlink/sync handlers

Add check-library-team-ownership! helper that verifies both the file
and library share the same team before creating or modifying library
relations. This prevents cross-team library injection where a user
with edit permissions on files in different teams could link them
across team boundaries.

Applied to link-file-to-library, unlink-file-from-library, and
update-file-library-sync-status handlers.

AI-assisted-by: mimo-v2.5

backend/src/app/rpc/commands/files.clj

@@ -1069,6 +1069,25 @@
   [cfg {:keys [::rpc/profile-id] :as params}]
   (db/tx-run! cfg delete-file (assoc params :profile-id profile-id)))
 
+;; --- Library relation helpers
+
+(defn- check-library-team-ownership!
+  "Verify that file and library belong to the same team.
+  Prevents cross-team library relation injection."
+  [conn file-id library-id]
+  (let [sql "SELECT EXISTS (
+               SELECT 1 FROM file AS f
+               JOIN project AS fp ON (fp.id = f.project_id)
+               JOIN file AS l ON (l.id = ?)
+               JOIN project AS lp ON (lp.id = l.project_id)
+               WHERE f.id = ? AND fp.team_id = lp.team_id
+             ) AS ok"
+        row (db/exec-one! conn [sql library-id file-id])]
+    (when-not (:ok row)
+      (ex/raise :type :not-found
+                :code :object-not-found
+                :hint "file and library must belong to the same team"))))
+
 ;; --- MUTATION COMMAND: link-file-to-library
 
 (def sql:link-file-to-library
@@ -1104,6 +1123,7 @@
 
   (check-edition-permissions! conn profile-id file-id)
   (check-edition-permissions! conn profile-id library-id)
+  (check-library-team-ownership! conn file-id library-id)
 
   (let [transitive-deps (bfc/get-libraries cfg [library-id])]
     (when (contains? transitive-deps file-id)
@@ -1135,6 +1155,7 @@
   [{:keys [::db/conn] :as cfg} {:keys [::rpc/profile-id file-id library-id] :as params}]
   (check-edition-permissions! conn profile-id file-id)
   (check-edition-permissions! conn profile-id library-id)
+  (check-library-team-ownership! conn file-id library-id)
   (unlink-file-from-library conn params)
   nil)
 
@@ -1159,6 +1180,7 @@
   [{:keys [::db/conn]} {:keys [::rpc/profile-id file-id library-id] :as params}]
   (check-edition-permissions! conn profile-id file-id)
   (check-edition-permissions! conn profile-id library-id)
+  (check-library-team-ownership! conn file-id library-id)
   (update-sync conn params))
 
 ;; --- MUTATION COMMAND: ignore-sync

backend/test/backend_tests/rpc_file_test.clj

@@ -983,6 +983,38 @@
     (t/is (some? sync))
     (t/is (some? (:synced-at sync)))))
 
+(t/deftest link-file-to-library-rejects-cross-team
+  ;; N1-08: A file in team2 must not be linked to a library in team1,
+  ;; even when the user has edit permissions on both (BOLA / CWE-639).
+  (let [prof1  (th/create-profile* 1)
+        prof2  (th/create-profile* 2)
+        team1  (th/create-team* 1 {:profile-id (:id prof1)})
+        team2  (th/create-team* 2 {:profile-id (:id prof2)})
+        proj1  (th/create-project* 1 {:profile-id (:id prof1)
+                                      :team-id (:id team1)})
+        proj2  (th/create-project* 2 {:profile-id (:id prof2)
+                                      :team-id (:id team2)})
+        lib    (th/create-file* 1 {:project-id (:id proj1)
+                                   :profile-id (:id prof1)
+                                   :is-shared true})
+        file2  (th/create-file* 2 {:project-id (:id proj2)
+                                   :profile-id (:id prof2)})]
+
+    ;; Add prof2 as editor to team1 so they have edit access to the library
+    (th/db-insert! :team-profile-rel {:team-id (:id team1)
+                                      :profile-id (:id prof2)
+                                      :is-owner false
+                                      :is-admin false
+                                      :can-edit true})
+
+    ;; prof2 tries to link file2 (team2) to lib (team1) — must fail
+    (let [data {::th/type :link-file-to-library
+                ::rpc/profile-id (:id prof2)
+                :file-id (:id file2)
+                :library-id (:id lib)}
+          out  (th/command! data)]
+      (t/is (some? (:error out))))))
+
 (t/deftest update-file-library-sync-status-updates-sync-row
   (let [profile  (th/create-profile* 1)
         file1    (th/create-file* 1 {:project-id (:default-project-id profile)