vhost_user_*: Create a vhost::Listener in advance

Changes is vhost crate require VhostUserDaemon users to create and
provide a vhost::Listener in advance. This allows us to adopt
sandboxing strategies in the future, by being able to create the UNIX
socket before switching to a restricted namespace.

Update also the reference to vhost crate in Cargo.lock to point to the
latest commit from the dragonball branch.

Signed-off-by: Sergio Lopez <slp@redhat.com>

Cargo.lock

@@ -1368,7 +1368,7 @@ dependencies = [
 [[package]]
 name = "vhost"
 version = "0.1.0"
-source = "git+https://github.com/cloud-hypervisor/vhost?branch=dragonball#d756e08224973cae7d9191e80adaa59b1101b35a"
+source = "git+https://github.com/cloud-hypervisor/vhost?branch=dragonball#3e80cf531d278aeb7f947335a4eeca655e0f2c54"
 dependencies = [
  "bitflags 1.2.1",
  "libc",

src/bin/vhost_user_fs.rs

@@ -19,7 +19,7 @@ use std::sync::{Arc, Mutex, RwLock};
 use std::{convert, error, fmt, io, process};
 
 use vhost_rs::vhost_user::message::*;
-use vhost_rs::vhost_user::SlaveFsCacheReq;
+use vhost_rs::vhost_user::{Listener, SlaveFsCacheReq};
 use vhost_user_backend::{VhostUserBackend, VhostUserDaemon, Vring};
 use vhost_user_fs::descriptor_utils::Error as VufDescriptorError;
 use vhost_user_fs::descriptor_utils::{Reader, Writer};
@@ -325,8 +325,7 @@ fn main() {
     };
     let xattr: bool = !cmd_arguments.is_present("disable-xattr");
 
-    // Convert into appropriate types
+    let listener = Listener::new(sock, true).unwrap();
-    let sock = String::from(sock);
 
     let fs_cfg = passthrough::Config {
         root_dir: shared_dir.to_string(),
@@ -338,14 +337,10 @@ fn main() {
         VhostUserFsBackend::new(fs, thread_pool_size).unwrap(),
     ));
 
-    let mut daemon = VhostUserDaemon::new(
+    let mut daemon =
-        String::from("vhost-user-fs-backend"),
+        VhostUserDaemon::new(String::from("vhost-user-fs-backend"), fs_backend.clone()).unwrap();
-        sock,
-        fs_backend.clone(),
-    )
-    .unwrap();
 
-    if let Err(e) = daemon.start() {
+    if let Err(e) = daemon.start(listener) {
         error!("Failed to start daemon: {:?}", e);
         process::exit(1);
     }

vhost_user_backend/src/lib.rs

@@ -20,7 +20,7 @@ use vhost_rs::vhost_user::message::{
     VhostUserVirtioFeatures, VhostUserVringAddrFlags, VhostUserVringState,
 };
 use vhost_rs::vhost_user::{
-    Error as VhostUserError, Result as VhostUserResult, SlaveFsCacheReq, SlaveListener,
+    Error as VhostUserError, Listener, Result as VhostUserResult, SlaveFsCacheReq, SlaveListener,
     VhostUserSlaveReqHandler,
 };
 use virtio_bindings::bindings::virtio_ring::VIRTIO_RING_F_EVENT_IDX;
@@ -124,7 +124,6 @@ pub trait VhostUserBackend: Send + Sync + 'static {
 /// in order to run a fully functional vhost-user daemon.
 pub struct VhostUserDaemon<S: VhostUserBackend> {
     name: String,
-    sock_path: String,
     handler: Arc<Mutex<VhostUserHandler<S>>>,
     main_thread: Option<thread::JoinHandle<Result<()>>>,
 }
@@ -136,14 +135,13 @@ impl<S: VhostUserBackend> VhostUserDaemon<S> {
     /// listening onto registered event. Those events can be vring events or
     /// custom events from the backend, but they get to be registered later
     /// during the sequence.
-    pub fn new(name: String, sock_path: String, backend: Arc<RwLock<S>>) -> Result<Self> {
+    pub fn new(name: String, backend: Arc<RwLock<S>>) -> Result<Self> {
         let handler = Arc::new(Mutex::new(
             VhostUserHandler::new(backend).map_err(Error::NewVhostUserHandler)?,
         ));
 
         Ok(VhostUserDaemon {
             name,
-            sock_path,
             handler,
             main_thread: None,
         })
@@ -153,9 +151,8 @@ impl<S: VhostUserBackend> VhostUserDaemon<S> {
     /// all requests coming through this socket. This runs in an infinite loop
     /// that should be terminating once the other end of the socket (the VMM)
     /// disconnects.
-    pub fn start(&mut self) -> Result<()> {
+    pub fn start(&mut self, listener: Listener) -> Result<()> {
-        let mut slave_listener =
+        let mut slave_listener = SlaveListener::new(listener, self.handler.clone())
-            SlaveListener::new(self.sock_path.as_str(), true, self.handler.clone())
             .map_err(Error::CreateSlaveListener)?;
         let mut slave_handler = slave_listener
             .accept()

vhost_user_block/src/lib.rs

@@ -33,6 +33,7 @@ use std::time::Instant;
 use std::vec::Vec;
 use std::{convert, error, fmt, io};
 use vhost_rs::vhost_user::message::*;
+use vhost_rs::vhost_user::Listener;
 use vhost_user_backend::{VhostUserBackend, VhostUserDaemon, Vring};
 use virtio_bindings::bindings::virtio_blk::*;
 use virtio_bindings::bindings::virtio_ring::VIRTIO_RING_F_EVENT_IDX;
@@ -452,12 +453,14 @@ pub fn start_block_backend(backend_command: &str) {
 
     debug!("blk_backend is created!\n");
 
+    let listener = Listener::new(&backend_config.socket, true).unwrap();
+
     let name = "vhost-user-blk-backend";
-    let mut blk_daemon =
+    let mut blk_daemon = VhostUserDaemon::new(name.to_string(), blk_backend.clone()).unwrap();
-        VhostUserDaemon::new(name.to_string(), backend_config.socket, blk_backend.clone()).unwrap();
+
     debug!("blk_daemon is created!\n");
 
-    if let Err(e) = blk_daemon.start() {
+    if let Err(e) = blk_daemon.start(listener) {
         error!(
             "Failed to start daemon for vhost-user-block with error: {:?}\n",
             e

vhost_user_net/src/lib.rs

@@ -26,7 +26,7 @@ use std::process;
 use std::sync::{Arc, Mutex, RwLock};
 use std::vec::Vec;
 use vhost_rs::vhost_user::message::*;
-use vhost_rs::vhost_user::Error as VhostUserError;
+use vhost_rs::vhost_user::{Error as VhostUserError, Listener};
 use vhost_user_backend::{VhostUserBackend, VhostUserDaemon, Vring, VringWorker};
 use virtio_bindings::bindings::virtio_net::*;
 use vm_memory::GuestMemoryMmap;
@@ -428,12 +428,10 @@ pub fn start_net_backend(backend_command: &str) {
         .unwrap(),
     ));
 
-    let mut net_daemon = VhostUserDaemon::new(
+    let listener = Listener::new(&backend_config.socket, true).unwrap();
-        "vhost-user-net-backend".to_string(),
+
-        backend_config.socket.to_string(),
+    let mut net_daemon =
-        net_backend.clone(),
+        VhostUserDaemon::new("vhost-user-net-backend".to_string(), net_backend.clone()).unwrap();
-    )
-    .unwrap();
 
     let mut vring_workers = net_daemon.get_vring_workers();
 
@@ -449,7 +447,7 @@ pub fn start_net_backend(backend_command: &str) {
             .set_vring_worker(Some(vring_workers.remove(0)));
     }
 
-    if let Err(e) = net_daemon.start() {
+    if let Err(e) = net_daemon.start(listener) {
         error!(
             "failed to start daemon for vhost-user-net with error: {:?}",
             e