fix(core-dsr): scope DSR operations to the caller's own subject

Non-admin callers may export/rectify/restrict/delete ONLY their own
subjectId; a mismatch is rejected with FORBIDDEN instead of being
honored verbatim (IDOR, audit finding A1). Cross-subject operations
require the admin role; cascade-hard stays admin-only on top.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/core-dsr/src/__tests__/dsr.router.test.ts

@@ -208,6 +208,93 @@ describe("dsrRouter.restrict", () => {
   });
 });
 
+describe("dsrRouter subject scoping (A1 — IDOR)", () => {
+  it("rejects a non-admin export for another subject with FORBIDDEN", async () => {
+    const binding = makeBinding();
+    const caller = makeCaller(binding, authenticatedUser);
+    await expect(
+      caller.export({ subjectId: "bob", format: "json" }),
+    ).rejects.toMatchObject({ code: "FORBIDDEN" });
+    expect(binding.dataExport.calls).toHaveLength(0);
+  });
+
+  it("rejects a non-admin delete for another subject with FORBIDDEN", async () => {
+    const binding = makeBinding();
+    const caller = makeCaller(binding, authenticatedUser);
+    await expect(
+      caller.delete({ subjectId: "bob", mode: "soft" }),
+    ).rejects.toMatchObject({ code: "FORBIDDEN" });
+    expect(binding.dataDelete.calls).toHaveLength(0);
+  });
+
+  it("rejects a non-admin rectify for another subject with FORBIDDEN", async () => {
+    const binding = makeBinding();
+    const caller = makeCaller(binding, authenticatedUser);
+    await expect(
+      caller.rectify({
+        subjectId: "bob",
+        collection: "users",
+        field: "name",
+        value: "x",
+      }),
+    ).rejects.toMatchObject({ code: "FORBIDDEN" });
+    expect(binding.dataRectify.calls).toHaveLength(0);
+  });
+
+  it("rejects a non-admin restrict for another subject with FORBIDDEN", async () => {
+    const binding = makeBinding();
+    const caller = makeCaller(binding, authenticatedUser);
+    await expect(
+      caller.restrict({ subjectId: "bob", granted: true }),
+    ).rejects.toMatchObject({ code: "FORBIDDEN" });
+    expect(binding.processingRestriction.sets).toHaveLength(0);
+  });
+
+  it("rejects a non-admin user without an id acting on any subject", async () => {
+    const binding = makeBinding();
+    const caller = makeCaller(binding, { roles: ["user"] });
+    await expect(
+      caller.export({ subjectId: "alice", format: "json" }),
+    ).rejects.toMatchObject({ code: "FORBIDDEN" });
+  });
+
+  it("allows a non-admin to act on themselves for every operation", async () => {
+    const binding = makeBinding();
+    const caller = makeCaller(binding, authenticatedUser);
+    await caller.export({ subjectId: "alice", format: "json" });
+    await caller.delete({ subjectId: "alice", mode: "soft" });
+    await caller.rectify({
+      subjectId: "alice",
+      collection: "users",
+      field: "name",
+      value: "Alice",
+    });
+    await caller.restrict({ subjectId: "alice", granted: true });
+    expect(binding.dataExport.calls).toHaveLength(1);
+    expect(binding.dataDelete.calls).toHaveLength(1);
+    expect(binding.dataRectify.calls).toHaveLength(1);
+    expect(binding.processingRestriction.sets).toHaveLength(1);
+  });
+
+  it("allows an admin to act cross-subject on every operation", async () => {
+    const binding = makeBinding();
+    const caller = makeCaller(binding, adminUser);
+    await caller.export({ subjectId: "alice", format: "json" });
+    await caller.delete({ subjectId: "alice", mode: "soft" });
+    await caller.rectify({
+      subjectId: "alice",
+      collection: "users",
+      field: "name",
+      value: "Alice",
+    });
+    await caller.restrict({ subjectId: "alice", granted: true });
+    expect(binding.dataExport.calls).toHaveLength(1);
+    expect(binding.dataDelete.calls).toHaveLength(1);
+    expect(binding.dataRectify.calls).toHaveLength(1);
+    expect(binding.processingRestriction.sets).toHaveLength(1);
+  });
+});
+
 describe("dsrRouter singleton guard", () => {
   it("throws when procedures are called without a real DsrBinding", async () => {
     // The singleton uses a Proxy that throws on any binding property access.

packages/core-dsr/src/dsr.router.ts

@@ -29,6 +29,28 @@ const dsrProcedure = t.procedure
   .use(requireAuthenticated)
   .use(defineErrorMiddleware([]));
 
+/**
+ * Subject-scope guard (audit finding A1 — DSR IDOR).
+ *
+ * Non-admin callers may act ONLY on themselves: a request whose
+ * `input.subjectId` differs from the authenticated user's id is rejected
+ * with FORBIDDEN (rejected, not silently rewritten, so the mismatch is
+ * visible to the caller). Any cross-subject operation requires the
+ * "admin" role.
+ */
+function assertSubjectScope(user: DsrTrpcUser, subjectId: string): void {
+  if (user.roles?.includes("admin")) return;
+  if (user.id !== undefined && user.id === subjectId) return;
+  throw new TRPCError({
+    code: "FORBIDDEN",
+    message: "DSR operations on another subject require the admin role",
+  });
+}
+
+function userFromCtx(ctx: object): DsrTrpcUser {
+  return (ctx as { user: DsrTrpcUser }).user;
+}
+
 /**
  * Creates the DSR tRPC router.
  *
@@ -54,7 +76,8 @@ export function createDsrRouter(binding: DsrBinding) {
           })
           .strict(),
       )
-      .query(async ({ input }) => {
+      .query(async ({ ctx, input }) => {
+        assertSubjectScope(userFromCtx(ctx), input.subjectId);
         const res = await createExportHandler(binding.dataExport)(input);
         return res.body;
       }),
@@ -69,15 +92,14 @@ export function createDsrRouter(binding: DsrBinding) {
           .strict(),
       )
       .mutation(async ({ ctx, input }) => {
-        if (input.mode === "cascade-hard") {
-          const user = (ctx as { user: DsrTrpcUser }).user;
-          if (!user.roles?.includes("admin")) {
+        const user = userFromCtx(ctx);
+        assertSubjectScope(user, input.subjectId);
+        if (input.mode === "cascade-hard" && !user.roles?.includes("admin")) {
           throw new TRPCError({
             code: "FORBIDDEN",
             message: "Admin role required for cascade-hard deletion",
           });
         }
-        }
         const res = await createDeleteHandler(binding.dataDelete)(input);
         return res.body;
       }),
@@ -93,7 +115,8 @@ export function createDsrRouter(binding: DsrBinding) {
           })
           .strict(),
       )
-      .mutation(async ({ input }) => {
+      .mutation(async ({ ctx, input }) => {
+        assertSubjectScope(userFromCtx(ctx), input.subjectId);
         // tRPC infers z.unknown() as value?: unknown; cast to assert presence
         const res = await createRectifyHandler(binding.dataRectify)(
           input as RectifyHandlerInput,
@@ -110,7 +133,8 @@ export function createDsrRouter(binding: DsrBinding) {
           })
           .strict(),
       )
-      .mutation(async ({ input }) => {
+      .mutation(async ({ ctx, input }) => {
+        assertSubjectScope(userFromCtx(ctx), input.subjectId);
         const res = await createRestrictHandler(binding.processingRestriction)(
           input,
         );