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// Copyright 2020 Alyssa Ross. All rights reserved.
// Copyright 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use std::convert::TryInto;
use std::error::Error;
use std::io::prelude::*;
use std::io::IoSlice;
use std::net::Shutdown;
use std::os::unix::net::{UnixListener, UnixStream};
use std::os::unix::prelude::*;
use std::thread::{self, JoinHandle};
use sys_util::{error, EventFd, MemfdSeals, PollContext, PollToken, ScmSocket, SharedMemory};
use crate::Server;
fn create_memfd(name: [u8; 224], size: u64) -> Result<SharedMemory, Box<dyn Error>> {
let mut full_name: Vec<u8> = b"crosvm-guest-memfd-".to_vec();
full_name.extend(
name.iter()
.map(|x| *x)
.take_while(|b| *b != 0 && *b != b'/'),
);
let size: usize = size.try_into()?;
let mut seals = MemfdSeals::new();
seals.set_grow_seal();
seals.set_shrink_seal();
seals.set_seal_seal();
let mut memfd = SharedMemory::named(full_name)?;
memfd.set_size(size as u64)?;
memfd.add_seals(seals)?;
Ok(memfd)
}
fn do_request(mut conn: UnixStream) -> Result<(), Box<dyn Error>> {
let mut name = [0; 224];
conn.read_exact(&mut name)?;
let mut size = [0; 8];
conn.read_exact(&mut size)?;
let size = u64::from_le_bytes(size);
let _ = conn.shutdown(Shutdown::Read);
match create_memfd(name, size) {
Ok(memfd) => conn.send_with_fd(&[IoSlice::new(&[0x00])], memfd.as_raw_fd())?,
Err(_) => conn.write(&[0x01])?,
};
Ok(())
}
fn run(wl_socket: UnixListener, kill_evt: EventFd) {
#[derive(Debug, PollToken)]
enum Token {
Socket,
Kill,
}
let poll_ctx =
match PollContext::build_with(&[(&wl_socket, Token::Socket), (&kill_evt, Token::Kill)]) {
Ok(pc) => pc,
Err(e) => {
error!("failed creating PollContext: {}", e);
return;
}
};
'poll: loop {
let events = match poll_ctx.wait() {
Ok(v) => v,
Err(e) => {
error!("failed polling for events: {}", e);
break;
}
};
for event in &events {
match event.token() {
Token::Socket => {
let conn = match wl_socket.accept() {
Ok((conn, _)) => conn,
Err(e) => {
error!("Failed to accept memfd connection: {}", e);
continue;
}
};
if let Err(e) = do_request(conn) {
error!("Failed to service memfd request: {}", e);
}
}
Token::Kill => break 'poll,
}
}
}
}
#[derive(Debug)]
pub struct MemfdServer {
kill_evt: Option<EventFd>,
worker_thread: Option<JoinHandle<()>>,
wl_socket: Option<UnixListener>,
}
impl MemfdServer {
pub fn new(wl_socket: UnixListener) -> Self {
Self {
kill_evt: None,
worker_thread: None,
wl_socket: Some(wl_socket),
}
}
}
impl Drop for MemfdServer {
fn drop(&mut self) {
if let Some(kill_evt) = self.kill_evt.take() {
// Ignore the result because there is nothing we can do about it.
let _ = kill_evt.write(1);
}
if let Some(worker_thread) = self.worker_thread.take() {
let _ = worker_thread.join();
}
}
}
impl Server for MemfdServer {
fn keep_fds(&self) -> Vec<RawFd> {
self.wl_socket.iter().map(AsRawFd::as_raw_fd).collect()
}
fn activate(&mut self) {
let wl_socket = match self.wl_socket.take() {
Some(wl) => wl,
None => return,
};
let (self_kill_evt, kill_evt) = match EventFd::new().and_then(|e| Ok((e.try_clone()?, e))) {
Ok(v) => v,
Err(e) => {
error!("failed creating kill EventFd pair: {}", e);
return;
}
};
self.kill_evt = Some(self_kill_evt);
let worker_result = thread::Builder::new()
.name("memfd-server".to_string())
.spawn(move || run(wl_socket, kill_evt));
match worker_result {
Err(e) => {
error!("failed to spawn memfd server worker: {}", e);
return;
}
Ok(join_handle) => {
self.worker_thread = Some(join_handle);
}
}
}
}
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