feat(unstable): --unstable-unsafe-proto (#21313)

Closes #21276

cli/args/flags.rs

@@ -844,45 +844,11 @@ pub fn flags_from_vec(args: Vec<String>) -> clap::error::Result<Flags> {
   if matches.get_flag("unstable") {
     flags.unstable = true;
   }
-  if matches.get_flag("unstable-broadcast-channel") {
-    flags.unstable_features.push(
-      deno_runtime::deno_broadcast_channel::UNSTABLE_FEATURE_NAME.to_string(),
-    );
-  }
-  if matches.get_flag("unstable-ffi") {
-    flags
-      .unstable_features
-      .push(deno_runtime::deno_ffi::UNSTABLE_FEATURE_NAME.to_string());
-  }
-  if matches.get_flag("unstable-fs") {
-    flags
-      .unstable_features
-      .push(deno_runtime::deno_fs::UNSTABLE_FEATURE_NAME.to_string());
-  }
-  if matches.get_flag("unstable-http") {
-    flags
-      .unstable_features
-      .push(deno_runtime::ops::http::UNSTABLE_FEATURE_NAME.to_string());
-  }
-  if matches.get_flag("unstable-kv") {
-    flags
-      .unstable_features
-      .push(deno_runtime::deno_kv::UNSTABLE_FEATURE_NAME.to_string());
-  }
-  if matches.get_flag("unstable-net") {
-    flags
-      .unstable_features
-      .push(deno_runtime::deno_net::UNSTABLE_FEATURE_NAME.to_string());
-  }
-  if matches.get_flag("unstable-worker-options") {
-    flags
-      .unstable_features
-      .push(deno_runtime::ops::worker_host::UNSTABLE_FEATURE_NAME.to_string());
-  }
-  if matches.get_flag("unstable-cron") {
-    flags
-      .unstable_features
-      .push(deno_runtime::deno_cron::UNSTABLE_FEATURE_NAME.to_string());
+
+  for (name, _, _) in crate::UNSTABLE_GRANULAR_FLAGS {
+    if matches.get_flag(&format!("unstable-{}", name)) {
+      flags.unstable_features.push(name.to_string());
+    }
   }
 
   flags.unstable_bare_node_builtins =

cli/main.rs

@@ -310,6 +310,11 @@ pub(crate) static UNSTABLE_GRANULAR_FLAGS: &[(
     "Enable unstable Deno.cron API",
     8,
   ),
+  (
+    "unsafe-proto",
+    "Enable unsafe __proto__ support. This is a security risk.",
+    9,
+  ),
 ];
 
 pub(crate) fn unstable_exit_cb(_feature: &str, api_name: &str) {

cli/tests/integration/run_tests.rs

@@ -4716,3 +4716,17 @@ itest!(workspaces_nested_member {
   http_server: true,
   exit_code: 1,
 });
+
+itest!(unsafe_proto {
+  args: "run -A run/unsafe_proto/main.js",
+  output: "run/unsafe_proto/main.out",
+  http_server: false,
+  exit_code: 0,
+});
+
+itest!(unsafe_proto_flag {
+  args: "run -A --unstable-unsafe-proto run/unsafe_proto/main.js",
+  output: "run/unsafe_proto/main_with_unsafe_proto_flag.out",
+  http_server: false,
+  exit_code: 0,
+});

cli/tests/testdata/run/unsafe_proto/main.js

@@ -0,0 +1,5 @@
+console.log(Object.hasOwn(Object.prototype, "__proto__"));
+
+new Worker(import.meta.resolve("./worker.js"), {
+  type: "module",
+});

cli/tests/testdata/run/unsafe_proto/main.out

@@ -0,0 +1,2 @@
+false
+false

cli/tests/testdata/run/unsafe_proto/main_with_unsafe_proto_flag.out

@@ -0,0 +1,2 @@
+true
+true

cli/tests/testdata/run/unsafe_proto/worker.js

@@ -0,0 +1,2 @@
+console.log(Object.hasOwn(Object.prototype, "__proto__"));
+close();

cli/worker.rs

@@ -570,7 +570,8 @@ impl CliMainWorkerFactory {
     // TODO(bartlomieju): this is cruft, update FeatureChecker to spit out
     // list of enabled features.
     let feature_checker = shared.feature_checker.clone();
-    let mut unstable_features = Vec::with_capacity(8);
+    let mut unstable_features =
+      Vec::with_capacity(crate::UNSTABLE_GRANULAR_FLAGS.len());
     for (feature_name, _, id) in crate::UNSTABLE_GRANULAR_FLAGS {
       if feature_checker.check(feature_name) {
         unstable_features.push(*id);
@@ -768,7 +769,8 @@ fn create_web_worker_callback(
     // TODO(bartlomieju): this is cruft, update FeatureChecker to spit out
     // list of enabled features.
     let feature_checker = shared.feature_checker.clone();
-    let mut unstable_features = Vec::with_capacity(8);
+    let mut unstable_features =
+      Vec::with_capacity(crate::UNSTABLE_GRANULAR_FLAGS.len());
     for (feature_name, _, id) in crate::UNSTABLE_GRANULAR_FLAGS {
       if feature_checker.check(feature_name) {
         unstable_features.push(*id);

runtime/js/90_deno_ns.js

@@ -208,6 +208,8 @@ const denoNsUnstableById = {
   8: {
     cron: cron.cron,
   },
+  // Unsafe proto
+  // 9: {},
 };
 
 // when editing this list, also update unstableDenoProps in cli/tsc/99_main_compiler.js

runtime/js/99_main.js

@@ -1,9 +1,5 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
-// Removes the `__proto__` for security reasons.
-// https://tc39.es/ecma262/#sec-get-object.prototype.__proto__
-delete Object.prototype.__proto__;
-
 // Remove Intl.v8BreakIterator because it is a non-standard API.
 delete Intl.v8BreakIterator;
 
@@ -14,6 +10,7 @@ const primordials = globalThis.__bootstrap.primordials;
 const {
   ArrayPrototypeFilter,
   ArrayPrototypeIndexOf,
+  ArrayPrototypeIncludes,
   ArrayPrototypeMap,
   ArrayPrototypePush,
   ArrayPrototypeShift,
@@ -570,6 +567,12 @@ function bootstrapMainRuntime(runtimeOptions) {
     }
   }
 
+  if (!ArrayPrototypeIncludes(unstableFeatures, /* unsafe-proto */ 9)) {
+    // Removes the `__proto__` for security reasons.
+    // https://tc39.es/ecma262/#sec-get-object.prototype.__proto__
+    delete Object.prototype.__proto__;
+  }
+
   // Setup `Deno` global - we're actually overriding already existing global
   // `Deno` with `Deno` namespace from "./deno.ts".
   ObjectDefineProperty(globalThis, "Deno", util.readOnly(finalDenoNs));
@@ -668,6 +671,13 @@ function bootstrapWorkerRuntime(
       ObjectAssign(finalDenoNs, denoNsUnstableById[id]);
     }
   }
+
+  if (!ArrayPrototypeIncludes(unstableFeatures, /* unsafe-proto */ 9)) {
+    // Removes the `__proto__` for security reasons.
+    // https://tc39.es/ecma262/#sec-get-object.prototype.__proto__
+    delete Object.prototype.__proto__;
+  }
+
   ObjectDefineProperties(finalDenoNs, {
     pid: util.getterOnly(opPid),
     noColor: util.getterOnly(() => ops.op_bootstrap_no_color()),