Honor the configured Windows sandbox level for managed networking (#37875)

## Why

Managed networking implicitly selected the elevated Windows sandbox backend,
even when the sandbox was configured to use a restricted token.

## What changed

- Select the Windows sandbox backend solely from `WindowsSandboxLevel`.
- Reject managed networking with a restricted-token sandbox before spawning a
  process, since managed networking requires the elevated backend.
- Cover the rejection through sandbox preparation, unified exec, and Windows
  sandbox session tests.

GitOrigin-RevId: 308858652d7b629af623d22896dafde3a23d3758

codex-rs/core/src/exec.rs

@@ -406,10 +406,8 @@ pub fn build_exec_request(
             )
         })
         .map_err(CodexErr::from)?;
-    let use_windows_elevated_backend = windows_sandbox_uses_elevated_backend(
-        exec_req.windows_sandbox_level,
-        exec_req.network.is_some(),
-    );
+    let use_windows_elevated_backend =
+        windows_sandbox_uses_elevated_backend(exec_req.windows_sandbox_level);
     exec_req.windows_sandbox_filesystem_overrides = if use_windows_elevated_backend {
         resolve_windows_elevated_filesystem_overrides(
             exec_req.sandbox,
@@ -665,7 +663,7 @@ async fn exec_windows_sandbox(
     let command_path = command.first().cloned();
     let sandbox_level = windows_sandbox_level;
     let proxy_enforced = network.is_some();
-    let use_elevated = windows_sandbox_uses_elevated_backend(sandbox_level, proxy_enforced);
+    let use_elevated = windows_sandbox_uses_elevated_backend(sandbox_level);
     let additional_deny_write_paths = windows_sandbox_filesystem_overrides
         .map(|overrides| overrides.additional_deny_write_paths.clone())
         .unwrap_or_default();

codex-rs/core/src/exec_tests.rs

@@ -398,18 +398,12 @@ fn windows_restricted_token_supports_read_only_profiles() {
 }
 
 #[test]
-fn windows_proxy_enforcement_uses_elevated_backend() {
+fn windows_sandbox_backend_honors_unelevated_configuration() {
     assert!(!windows_sandbox_uses_elevated_backend(
-        WindowsSandboxLevel::RestrictedToken,
-        /*proxy_enforced*/ false,
+        WindowsSandboxLevel::RestrictedToken
     ));
     assert!(windows_sandbox_uses_elevated_backend(
-        WindowsSandboxLevel::RestrictedToken,
-        /*proxy_enforced*/ true,
-    ));
-    assert!(windows_sandbox_uses_elevated_backend(
-        WindowsSandboxLevel::Elevated,
-        /*proxy_enforced*/ false,
+        WindowsSandboxLevel::Elevated
     ));
 }
 

codex-rs/core/tests/suite/unified_exec.rs

@@ -1028,6 +1028,43 @@ async fn unified_exec_short_lived_network_denial_emits_failed_end_event() -> Res
     Ok(())
 }
 
+#[cfg(windows)]
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn unified_exec_rejects_unelevated_windows_sandbox_with_managed_network() -> Result<()> {
+    let server = start_mock_server().await;
+    let (test, permission_profile) = unified_exec_network_denial_test(&server).await?;
+    let call_id = "uexec-unelevated-managed-network";
+    let args = json!({
+        "cmd": "echo should not run",
+        "yield_time_ms": 1_000,
+    });
+    let responses = mount_unified_exec_network_denial_responses(&server, call_id, &args).await?;
+
+    submit_unified_exec_turn(
+        &test,
+        "run an unelevated managed-network command",
+        permission_profile,
+    )
+    .await?;
+    wait_for_event(&test.codex, |event| {
+        matches!(event, EventMsg::TurnComplete(_))
+    })
+    .await;
+
+    let output_item = responses
+        .last_request()
+        .expect("model should receive the rejected tool call output")
+        .function_call_output(call_id);
+    let output = extract_output_text(&output_item)
+        .expect("rejected tool call should include model-visible text");
+    assert!(
+        output.contains("managed networking requires the elevated Windows sandbox backend"),
+        "unexpected output: {output}"
+    );
+
+    Ok(())
+}
+
 async fn unified_exec_network_denial_test(
     server: &wiremock::MockServer,
 ) -> Result<(TestCodex, PermissionProfile)> {
@@ -1070,6 +1107,8 @@ allow_local_binding = true
                 .permissions
                 .set_permission_profile(permission_profile_for_config)
                 .expect("set permission profile");
+            #[cfg(windows)]
+            config.set_windows_sandbox_enabled(/*value*/ true);
         });
     let test = builder.build_with_auto_env(server).await?;
     assert!(

codex-rs/exec-server/src/process_sandbox.rs

@@ -248,10 +248,8 @@ pub(crate) async fn prepare_exec_request(
     let windows_sandbox = if sandbox == SandboxType::WindowsRestrictedToken {
         request.arg0 = params.arg0.clone();
         let proxy_enforced = params.enforce_managed_network;
-        let use_elevated = windows_sandbox_uses_elevated_backend(
-            sandbox_context.windows_sandbox_level,
-            proxy_enforced,
-        );
+        let use_elevated =
+            windows_sandbox_uses_elevated_backend(sandbox_context.windows_sandbox_level);
         let filesystem_overrides = if use_elevated {
             resolve_windows_elevated_filesystem_overrides(
                 sandbox,

codex-rs/exec-server/src/process_sandbox_tests.rs

@@ -17,6 +17,8 @@ use codex_sandboxing::landlock::CODEX_LINUX_SANDBOX_ARG0;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_path_uri::PathUri;
 use pretty_assertions::assert_eq;
+#[cfg(windows)]
+use test_case::test_case;
 use tokio::io::AsyncReadExt;
 use tokio::io::AsyncWriteExt;
 use tokio::time::timeout;
@@ -379,8 +381,10 @@ async fn disabled_remote_proxy_config_is_rejected_before_exporting_ports() {
 }
 
 #[cfg(windows)]
+#[test_case(WindowsSandboxLevel::RestrictedToken ; "unelevated is rejected")]
+#[test_case(WindowsSandboxLevel::Elevated ; "elevated is accepted")]
 #[tokio::test]
-async fn managed_network_selects_elevated_windows_spawn() {
+async fn managed_network_honors_windows_sandbox_level(windows_sandbox_level: WindowsSandboxLevel) {
     let cwd: AbsolutePathBuf = std::env::current_dir()
         .expect("current directory")
         .try_into()
@@ -393,7 +397,7 @@ async fn managed_network_selects_elevated_windows_spawn() {
         permissions.clone(),
         cwd_uri.clone(),
     );
-    sandbox.windows_sandbox_level = WindowsSandboxLevel::RestrictedToken;
+    sandbox.windows_sandbox_level = windows_sandbox_level;
     sandbox.windows_sandbox_proxy_settings_mode =
         Some(codex_sandboxing::WindowsSandboxProxySettingsMode::Preserve);
     let proxy_config = RemoteNetworkProxyConfig::from_effective_config(&NetworkProxyConfig {
@@ -417,32 +421,34 @@ async fn managed_network_selects_elevated_windows_spawn() {
         network_proxy: Some(RemoteNetworkProxyLaunchConfig::new(proxy_config)),
     };
 
-    let mut prepared = prepare_exec_request(
+    let prepared = prepare_exec_request(
         &params,
         HashMap::new(),
         Some(&runtime_paths),
         /*network_policy_decider*/ None,
     )
-    .await
-    .expect("prepare sandboxed request");
-    {
-        let spawn = prepared
-            .windows_sandbox_spawn_request()
-            .expect("Windows sandbox spawn request");
+    .await;
 
-        assert_eq!(
-            spawn.windows_sandbox_level,
-            WindowsSandboxLevel::RestrictedToken
+    if windows_sandbox_level == WindowsSandboxLevel::RestrictedToken {
+        let error = prepared
+            .err()
+            .expect("managed networking must reject an unelevated Windows sandbox");
+        assert_eq!(error.code, -32602);
+        assert!(
+            error
+                .message
+                .contains("managed networking requires the elevated Windows sandbox backend")
         );
-        assert!(spawn.proxy_enforced);
-        assert!(spawn.network_proxy_restricting_sid.is_some());
-        assert_eq!(
-            spawn.proxy_settings_mode,
-            codex_sandboxing::WindowsSandboxProxySettingsMode::Preserve
-        );
-        assert_eq!(spawn.permission_profile, &permissions);
-        assert_eq!(spawn.workspace_roots, std::slice::from_ref(&cwd));
+        return;
     }
+
+    let mut prepared = prepared.expect("managed networking accepts an elevated Windows sandbox");
+    let spawn = prepared
+        .windows_sandbox_spawn_request()
+        .expect("Windows sandbox spawn request");
+    assert_eq!(spawn.windows_sandbox_level, WindowsSandboxLevel::Elevated);
+    assert!(spawn.proxy_enforced);
+    assert!(spawn.network_proxy_restricting_sid.is_some());
     prepared
         .network_proxy_handle
         .take()

codex-rs/sandboxing/src/manager.rs

@@ -404,11 +404,20 @@ impl SandboxManager {
                 )
             }
             #[cfg(target_os = "windows")]
-            SandboxType::WindowsRestrictedToken => (
-                os_argv_to_strings(argv),
-                None,
-                Some(pending_sandboxed_request?),
-            ),
+            SandboxType::WindowsRestrictedToken => {
+                if enforce_managed_network && windows_sandbox_level != WindowsSandboxLevel::Elevated
+                {
+                    return Err(SandboxTransformError::WindowsSandboxPreparation(
+                        "managed networking requires the elevated Windows sandbox backend"
+                            .to_string(),
+                    ));
+                }
+                (
+                    os_argv_to_strings(argv),
+                    None,
+                    Some(pending_sandboxed_request?),
+                )
+            }
             #[cfg(not(target_os = "windows"))]
             SandboxType::WindowsRestrictedToken => (
                 os_argv_to_strings(argv),
@@ -524,8 +533,7 @@ fn wrap_windows_sandbox_exec_request_for_direct_spawn(
                 })
         })
         .transpose()?;
-    let use_elevated =
-        windows_sandbox_uses_elevated_backend(request.windows_sandbox_level, proxy_enforced);
+    let use_elevated = windows_sandbox_uses_elevated_backend(request.windows_sandbox_level);
     let overrides = if use_elevated {
         resolve_windows_elevated_filesystem_overrides(
             request.sandbox,

codex-rs/sandboxing/src/windows.rs

@@ -29,14 +29,8 @@ pub struct WindowsSandboxFilesystemOverrides {
     pub additional_deny_write_paths: Vec<AbsolutePathBuf>,
 }
 
-pub fn windows_sandbox_uses_elevated_backend(
-    sandbox_level: WindowsSandboxLevel,
-    proxy_enforced: bool,
-) -> bool {
-    // Windows firewall enforcement is tied to the logon-user sandbox identities, so
-    // proxy-enforced sessions must use that backend even when the configured mode is
-    // the default restricted-token sandbox.
-    proxy_enforced || matches!(sandbox_level, WindowsSandboxLevel::Elevated)
+pub fn windows_sandbox_uses_elevated_backend(sandbox_level: WindowsSandboxLevel) -> bool {
+    matches!(sandbox_level, WindowsSandboxLevel::Elevated)
 }
 
 pub fn permission_profile_supports_windows_restricted_token_sandbox(

codex-rs/windows-sandbox-rs/src/unified_exec/mod.rs

@@ -48,9 +48,7 @@ pub struct WindowsSandboxSessionRequest<'a> {
 pub async fn spawn_windows_sandbox_session_for_level(
     request: WindowsSandboxSessionRequest<'_>,
 ) -> Result<SpawnedProcess> {
-    if request.proxy_enforced
-        || matches!(request.windows_sandbox_level, WindowsSandboxLevel::Elevated)
-    {
+    if matches!(request.windows_sandbox_level, WindowsSandboxLevel::Elevated) {
         backends::elevated::spawn_windows_sandbox_session_elevated_for_permission_profile(
             request.permission_profile,
             request.workspace_roots,
@@ -73,6 +71,9 @@ pub async fn spawn_windows_sandbox_session_for_level(
         )
         .await
     } else {
+        if request.proxy_enforced {
+            bail!("managed networking requires the elevated Windows sandbox backend");
+        }
         if request.network_proxy_restricting_sid.is_some() {
             bail!("network proxy restricting SID requires the elevated Windows sandbox backend");
         }

codex-rs/windows-sandbox-rs/src/unified_exec/tests.rs

@@ -1,6 +1,8 @@
 #![cfg(target_os = "windows")]
 
+use super::WindowsSandboxSessionRequest;
 use super::spawn_windows_sandbox_session_elevated_for_permission_profile;
+use super::spawn_windows_sandbox_session_for_level;
 use super::spawn_windows_sandbox_session_legacy;
 use crate::WindowsSandboxCancellationToken;
 use crate::ipc_framed::Message;
@@ -9,6 +11,7 @@ use crate::ipc_framed::read_frame;
 use crate::run_windows_sandbox_capture;
 use base64::Engine;
 use base64::engine::general_purpose::STANDARD as BASE64;
+use codex_protocol::config_types::WindowsSandboxLevel;
 use codex_protocol::models::PermissionProfile;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_pty::ProcessDriver;
@@ -221,6 +224,43 @@ async fn collect_stdout_and_exit(
     (stdout, exit_code)
 }
 
+#[test]
+fn restricted_token_rejects_managed_network_before_spawn() {
+    current_thread_runtime().block_on(async {
+        let cwd = sandbox_cwd();
+        let codex_home = sandbox_home("restricted-token-managed-network");
+        let permission_profile = PermissionProfile::workspace_write();
+        let error = spawn_windows_sandbox_session_for_level(WindowsSandboxSessionRequest {
+            permission_profile: &permission_profile,
+            workspace_roots: &[],
+            codex_home: codex_home.path(),
+            command: Vec::new(),
+            cwd: cwd.as_path(),
+            env_map: HashMap::new(),
+            windows_sandbox_level: WindowsSandboxLevel::RestrictedToken,
+            proxy_enforced: true,
+            network_proxy_restricting_sid: None,
+            proxy_settings_mode: crate::WindowsSandboxProxySettingsMode::Preserve,
+            timeout_ms: None,
+            read_roots_override: None,
+            read_roots_include_platform_defaults: false,
+            write_roots_override: None,
+            deny_read_paths_override: &[],
+            deny_write_paths_override: &[],
+            tty: false,
+            stdin_open: false,
+            use_private_desktop: false,
+        })
+        .await
+        .expect_err("managed networking must fail before spawning an unelevated sandbox");
+
+        assert_eq!(
+            error.to_string(),
+            "managed networking requires the elevated Windows sandbox backend"
+        );
+    });
+}
+
 #[test]
 fn legacy_non_tty_cmd_emits_output() {
     let _guard = legacy_process_test_guard();