src,permission: --allow-wasi & prevent WASI exec

RafaelGSS · RafaelGSS · commit a3db21c5957f · 2024-05-23T17:16:57.000-03:00
diff --git a/doc/api/cli.md b/doc/api/cli.md
@@ -269,6 +269,53 @@ Examples can be found in the [File System Permissions][] documentation.
 
 Relative paths are NOT supported through the CLI flag.
 
+### `--allow-wasi`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1.1 - Active development
+
+When using the [Permission Model][], the process will not be able to create any
+WASI instances by default.
+For security reasons, the call will throw an `ERR_ACCESS_DENIED` unless the
+user explicitly passes the flag `--allow-wasi` in the main Node.js process.
+
+Example:
+
+```js
+const { WASI } = require('node:wasi');
+// Attempt to bypass the permission
+new WASI({
+  version: 'preview1',
+  // Attempt to mount the whole filesystem
+  preopens: {
+    '/': '/',
+  },
+});
+```
+
+```console
+$ node --experimental-permission --allow-fs-read=* index.js
+node:wasi:99
+    const wrap = new _WASI(args, env, preopens, stdio);
+                 ^
+
+Error: Access to this API has been restricted
+    at new WASI (node:wasi:99:18)
+    at Object.<anonymous> (/home/index.js:3:1)
+    at Module._compile (node:internal/modules/cjs/loader:1476:14)
+    at Module._extensions..js (node:internal/modules/cjs/loader:1555:10)
+    at Module.load (node:internal/modules/cjs/loader:1288:32)
+    at Module._load (node:internal/modules/cjs/loader:1104:12)
+    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:191:14)
+    at node:internal/main/run_main_module:30:49 {
+  code: 'ERR_ACCESS_DENIED',
+  permission: 'WASI',
+}
+```
+
 ### `--allow-worker`
 
 <!-- YAML
@@ -878,6 +925,7 @@ following permissions are restricted:
   [`--allow-fs-read`][], [`--allow-fs-write`][] flags
 * Child Process - manageable through [`--allow-child-process`][] flag
 * Worker Threads - manageable through [`--allow-worker`][] flag
+* WASI - manageable through [`--allow-wasi`][] flag
 
 ### `--experimental-policy`
 
@@ -2643,6 +2691,7 @@ one is included in the list below.
 * `--allow-child-process`
 * `--allow-fs-read`
 * `--allow-fs-write`
+* `--allow-wasi`
 * `--allow-worker`
 * `--conditions`, `-C`
 * `--diagnostic-dir`
@@ -3187,6 +3236,7 @@ node --stack-trace-limit=12 -p -e "Error.stackTraceLimit" # prints 12
 [`--allow-child-process`]: #--allow-child-process
 [`--allow-fs-read`]: #--allow-fs-read
 [`--allow-fs-write`]: #--allow-fs-write
+[`--allow-wasi`]: #--allow-wasi
 [`--allow-worker`]: #--allow-worker
 [`--build-snapshot`]: #--build-snapshot
 [`--cpu-prof-dir`]: #--cpu-prof-dir
diff --git a/doc/api/permissions.md b/doc/api/permissions.md
@@ -482,7 +482,7 @@ flag.
 
 When starting Node.js with `--experimental-permission`,
 the ability to access the file system through the `fs` module, spawn processes,
-use `node:worker_threads`, native addons, and enable the runtime inspector
+use `node:worker_threads`, use native addons, use WASI, and enable the runtime inspector
 will be restricted.
 
 ```console
@@ -507,7 +507,7 @@ Allowing access to spawning a process and creating worker threads can be done
 using the [`--allow-child-process`][] and [`--allow-worker`][] respectively.
 
 To allow native addons when using permission model, use the [`--allow-addons`][]
-flag.
+flag. For WASI, use the [`--allow-wasi`][] flag.
 
 #### Runtime API
 
@@ -574,6 +574,7 @@ There are constraints you need to know before using this system:
   * Worker Threads
   * Inspector protocol
   * File system access
+  * WASI
 * The Permission Model is initialized after the Node.js environment is set up.
   However, certain flags such as `--env-file` or `--openssl-config` are designed
   to read files before environment initialization. As a result, such flags are
@@ -598,6 +599,7 @@ There are constraints you need to know before using this system:
 [`--allow-child-process`]: cli.md#--allow-child-process
 [`--allow-fs-read`]: cli.md#--allow-fs-read
 [`--allow-fs-write`]: cli.md#--allow-fs-write
+[`--allow-wasi`]: cli.md#--allow-wasi
 [`--allow-worker`]: cli.md#--allow-worker
 [`--experimental-permission`]: cli.md#--experimental-permission
 [`permission.has()`]: process.md#processpermissionhasscope-reference
diff --git a/doc/node.1 b/doc/node.1
@@ -88,6 +88,9 @@ Allow using native addons when using the permission model.
 .It Fl -allow-child-process
 Allow spawning process when using the permission model.
 .
+.It Fl -allow-wasi
+Allow execution of WASI when using the permission model.
+.
 .It Fl -allow-worker
 Allow creating worker threads when using the permission model.
 .
diff --git a/lib/internal/process/pre_execution.js b/lib/internal/process/pre_execution.js
@@ -550,6 +550,7 @@ function initializePermission() {
     const warnFlags = [
       '--allow-addons',
       '--allow-child-process',
+      '--allow-wasi',
       '--allow-worker',
     ];
     for (const flag of warnFlags) {
@@ -591,6 +592,7 @@ function initializePermission() {
       '--allow-fs-write',
       '--allow-addons',
       '--allow-child-process',
+      '--allow-wasi',
       '--allow-worker',
     ];
     ArrayPrototypeForEach(availablePermissionFlags, (flag) => {
diff --git a/node.gyp b/node.gyp
@@ -151,6 +151,7 @@
       'src/permission/fs_permission.cc',
       'src/permission/inspector_permission.cc',
       'src/permission/permission.cc',
+      'src/permission/wasi_permission.cc',
       'src/permission/worker_permission.cc',
       'src/pipe_wrap.cc',
       'src/process_wrap.cc',
@@ -275,6 +276,7 @@
       'src/permission/fs_permission.h',
       'src/permission/inspector_permission.h',
       'src/permission/permission.h',
+      'src/permission/wasi_permission.h',
       'src/permission/worker_permission.h',
       'src/pipe_wrap.h',
       'src/req_wrap.h',
diff --git a/src/env.cc b/src/env.cc
@@ -921,6 +921,9 @@ Environment::Environment(IsolateData* isolate_data,
       permission()->Apply(
           this, {"*"}, permission::PermissionScope::kWorkerThreads);
     }
+    if (!options_->allow_wasi) {
+      permission()->Apply(this, {"*"}, permission::PermissionScope::kWASI);
+    }
 
     if (!options_->allow_fs_read.empty()) {
       permission()->Apply(this,
diff --git a/src/node_options.cc b/src/node_options.cc
@@ -471,6 +471,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "allow use of child process when any permissions are set",
             &EnvironmentOptions::allow_child_process,
             kAllowedInEnvvar);
+  AddOption("--allow-wasi",
+            "allow wasi when any permissions are set",
+            &EnvironmentOptions::allow_wasi,
+            kAllowedInEnvvar);
   AddOption("--allow-worker",
             "allow worker threads when any permissions are set",
             &EnvironmentOptions::allow_worker_threads,
diff --git a/src/node_options.h b/src/node_options.h
@@ -127,6 +127,7 @@ class EnvironmentOptions : public Options {
   std::vector<std::string> allow_fs_write;
   bool allow_addons = false;
   bool allow_child_process = false;
+  bool allow_wasi = false;
   bool allow_worker_threads = false;
   bool experimental_repl_await = true;
   bool experimental_vm_modules = false;
diff --git a/src/node_wasi.cc b/src/node_wasi.cc
@@ -1,14 +1,15 @@
-#include "env-inl.h"
+#include "node_wasi.h"
 #include "base_object-inl.h"
 #include "debug_utils-inl.h"
+#include "env-inl.h"
 #include "memory_tracker-inl.h"
-#include "node_mem-inl.h"
-#include "util-inl.h"
 #include "node.h"
 #include "node_errors.h"
+#include "node_mem-inl.h"
+#include "permission/permission.h"
+#include "util-inl.h"
 #include "uv.h"
 #include "uvwasi.h"
-#include "node_wasi.h"
 
 namespace node {
 namespace wasi {
@@ -77,6 +78,8 @@ static MaybeLocal<Value> WASIException(Local<Context> context,
 WASI::WASI(Environment* env,
            Local<Object> object,
            uvwasi_options_t* options) : BaseObject(env, object) {
+  THROW_IF_INSUFFICIENT_PERMISSIONS(
+      env, permission::PermissionScope::kWASI, "");
   MakeWeak();
   alloc_info_ = MakeAllocator();
   options->allocator = &alloc_info_;
diff --git a/src/permission/permission.cc b/src/permission/permission.cc
@@ -81,6 +81,7 @@ Permission::Permission() : enabled_(false) {
       std::make_shared<WorkerPermission>();
   std::shared_ptr<PermissionBase> inspector =
       std::make_shared<InspectorPermission>();
+  std::shared_ptr<PermissionBase> wasi = std::make_shared<WASIPermission>();
 #define V(Name, _, __)                                                         \
   nodes_.insert(std::make_pair(PermissionScope::k##Name, fs));
   FILESYSTEM_PERMISSIONS(V)
@@ -97,6 +98,10 @@ Permission::Permission() : enabled_(false) {
   nodes_.insert(std::make_pair(PermissionScope::k##Name, inspector));
   INSPECTOR_PERMISSIONS(V)
 #undef V
+#define V(Name, _, __)                                                         \
+  nodes_.insert(std::make_pair(PermissionScope::k##Name, wasi));
+  WASI_PERMISSIONS(V)
+#undef V
 }
 
 void Permission::ThrowAccessDenied(Environment* env,
diff --git a/src/permission/permission.h b/src/permission/permission.h
@@ -9,6 +9,7 @@
 #include "permission/fs_permission.h"
 #include "permission/inspector_permission.h"
 #include "permission/permission_base.h"
+#include "permission/wasi_permission.h"
 #include "permission/worker_permission.h"
 #include "v8.h"
 
diff --git a/src/permission/permission_base.h b/src/permission/permission_base.h
@@ -21,6 +21,8 @@ namespace permission {
 
 #define CHILD_PROCESS_PERMISSIONS(V) V(ChildProcess, "child", PermissionsRoot)
 
+#define WASI_PERMISSIONS(V) V(WASI, "wasi", PermissionsRoot)
+
 #define WORKER_THREADS_PERMISSIONS(V)                                          \
   V(WorkerThreads, "worker", PermissionsRoot)
 
@@ -29,6 +31,7 @@ namespace permission {
 #define PERMISSIONS(V)                                                         \
   FILESYSTEM_PERMISSIONS(V)                                                    \
   CHILD_PROCESS_PERMISSIONS(V)                                                 \
+  WASI_PERMISSIONS(V)                                                          \
   WORKER_THREADS_PERMISSIONS(V)                                                \
   INSPECTOR_PERMISSIONS(V)
 
diff --git a/src/permission/wasi_permission.cc b/src/permission/wasi_permission.cc
@@ -0,0 +1,24 @@
+#include "permission/wasi_permission.h"
+
+#include <string>
+#include <vector>
+
+namespace node {
+
+namespace permission {
+
+// Currently, WASIPermission manage a single state
+// Once denied, it's always denied
+void WASIPermission::Apply(Environment* env,
+                           const std::vector<std::string>& allow,
+                           PermissionScope scope) {
+  deny_all_ = true;
+}
+
+bool WASIPermission::is_granted(PermissionScope perm,
+                                const std::string_view& param) const {
+  return deny_all_ == false;
+}
+
+}  // namespace permission
+}  // namespace node
diff --git a/src/permission/wasi_permission.h b/src/permission/wasi_permission.h
@@ -0,0 +1,30 @@
+#ifndef SRC_PERMISSION_WASI_PERMISSION_H_
+#define SRC_PERMISSION_WASI_PERMISSION_H_
+
+#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
+
+#include <vector>
+#include "permission/permission_base.h"
+
+namespace node {
+
+namespace permission {
+
+class WASIPermission final : public PermissionBase {
+ public:
+  void Apply(Environment* env,
+             const std::vector<std::string>& allow,
+             PermissionScope scope) override;
+  bool is_granted(PermissionScope perm,
+                  const std::string_view& param = "") const override;
+
+ private:
+  bool deny_all_;
+};
+
+}  // namespace permission
+
+}  // namespace node
+
+#endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
+#endif  // SRC_PERMISSION_WASI_PERMISSION_H_
diff --git a/test/parallel/test-permission-allow-wasi-cli.js b/test/parallel/test-permission-allow-wasi-cli.js
@@ -0,0 +1,22 @@
+// Flags: --experimental-permission --allow-wasi --allow-fs-read=*
+'use strict';
+
+const common = require('../common');
+common.skipIfWorker();
+
+const assert = require('assert');
+const { WASI } = require('wasi');
+
+// Guarantee the initial state
+{
+  assert.ok(process.permission.has('wasi'));
+}
+
+// When a permission is set by cli, the process shouldn't be able
+// to create WASI instance unless --allow-wasi is sent
+{
+  // doesNotThrow
+  new WASI({
+    version: 'preview1',
+  });
+}
diff --git a/test/parallel/test-permission-warning-flags.js b/test/parallel/test-permission-warning-flags.js
@@ -7,6 +7,7 @@ const assert = require('assert');
 const warnFlags = [
   '--allow-addons',
   '--allow-child-process',
+  '--allow-wasi',
   '--allow-worker',
 ];
 
diff --git a/test/parallel/test-permission-wasi.js b/test/parallel/test-permission-wasi.js
@@ -0,0 +1,19 @@
+// Flags: --experimental-permission --allow-fs-read=*
+'use strict';
+
+const common = require('../common');
+const assert = require('node:assert');
+
+const { WASI } = require('wasi');
+
+{
+  assert.throws(() => {
+    new WASI({
+      version: 'preview1',
+      preopens: { '/': '/' },
+    });
+  }, common.expectsError({
+    code: 'ERR_ACCESS_DENIED',
+    permission: 'WASI',
+  }));
+}

Original file line number	Diff line number	Diff line change
`@@ -88,6 +88,9 @@ Allow using native addons when using the permission model.`
`88`	`88`	`.It Fl -allow-child-process`
`89`	`89`	`Allow spawning process when using the permission model.`
`90`	`90`	`.`
	`91`	`+.It Fl -allow-wasi`
	`92`	`+Allow execution of WASI when using the permission model.`
	`93`	`+.`
`91`	`94`	`.It Fl -allow-worker`
`92`	`95`	`Allow creating worker threads when using the permission model.`
`93`	`96`	`.`
Original file line number	Diff line number	Diff line change
`@@ -921,6 +921,9 @@ Environment::Environment(IsolateData* isolate_data,`
`921`	`921`	`permission()->Apply(`
`922`	`922`	`this, {"*"}, permission::PermissionScope::kWorkerThreads);`
`923`	`923`	`}`
	`924`	`+ if (!options_->allow_wasi) {`
	`925`	`+ permission()->Apply(this, {"*"}, permission::PermissionScope::kWASI);`
	`926`	`+ }`
`924`	`927`
`925`	`928`	`if (!options_->allow_fs_read.empty()) {`
`926`	`929`	`permission()->Apply(this,`