Don't inherit vm payload socket and stdio from MM

Because child processes don't and shouldn't need the socket / stdio.

Bug: 259241719
Test: atest MicrodroidHostTestCases MicrodroidTestApp
Change-Id: I309c6f0e869ab079a8fc577efb62b5e57754c274
diff --git a/microdroid_manager/src/main.rs b/microdroid_manager/src/main.rs
index 762a149..0ac4167 100644
--- a/microdroid_manager/src/main.rs
+++ b/microdroid_manager/src/main.rs
@@ -28,7 +28,10 @@
 use android_system_virtualmachineservice::aidl::android::system::virtualmachineservice::IVirtualMachineService::{
         IVirtualMachineService, VM_BINDER_SERVICE_PORT,
 };
-use android_system_virtualization_payload::aidl::android::system::virtualization::payload::IVmPayloadService::VM_APK_CONTENTS_PATH;
+use android_system_virtualization_payload::aidl::android::system::virtualization::payload::IVmPayloadService::{
+    VM_APK_CONTENTS_PATH,
+    VM_PAYLOAD_SERVICE_SOCKET_NAME,
+};
 use anyhow::{anyhow, bail, ensure, Context, Error, Result};
 use apkverify::{get_public_key_der, verify, V4Signature};
 use binder::Strong;
@@ -36,14 +39,16 @@
 use glob::glob;
 use itertools::sorted;
 use libc::VMADDR_CID_HOST;
-use log::{error, info};
+use log::{error, info, warn};
 use microdroid_metadata::{write_metadata, Metadata, PayloadMetadata};
 use microdroid_payload_config::{OsConfig, Task, TaskType, VmPayloadConfig};
+use nix::fcntl::{fcntl, F_SETFD, FdFlag};
 use nix::sys::signal::Signal;
 use openssl::sha::Sha512;
 use payload::{get_apex_data_from_payload, load_metadata, to_metadata};
 use rand::Fill;
 use rpcbinder::get_vsock_rpc_interface;
+use rustutils::sockets::android_get_control_socket;
 use rustutils::system_properties;
 use rustutils::system_properties::PropertyWatcher;
 use std::borrow::Cow::{Borrowed, Owned};
@@ -174,10 +179,22 @@
     })
 }
 
+fn set_cloexec_on_vm_payload_service_socket() -> Result<()> {
+    let fd = android_get_control_socket(VM_PAYLOAD_SERVICE_SOCKET_NAME)?;
+
+    fcntl(fd, F_SETFD(FdFlag::FD_CLOEXEC))?;
+
+    Ok(())
+}
+
 fn try_main() -> Result<()> {
     let _ = kernlog::init();
     info!("started.");
 
+    if let Err(e) = set_cloexec_on_vm_payload_service_socket() {
+        warn!("Failed to set cloexec on vm payload socket: {:?}", e);
+    }
+
     load_crashkernel_if_supported().context("Failed to load crashkernel")?;
 
     swap::init_swap().context("Failed to initialise swap")?;
@@ -726,8 +743,7 @@
     Ok(())
 }
 
-/// Executes the given task. Stdout of the task is piped into the vsock stream to the
-/// virtualizationservice in the host side.
+/// Executes the given task.
 fn exec_task(task: &Task, service: &Strong<dyn IVirtualMachineService>) -> Result<i32> {
     info!("executing main task {:?}...", task);
     let mut command = match task.type_ {
@@ -738,6 +754,7 @@
             command
         }
     };
+    command.stdin(Stdio::null()).stdout(Stdio::null()).stderr(Stdio::null());
 
     info!("notifying payload started");
     service.notifyPayloadStarted()?;