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vm-virtio: vsock: Port submodule csm and packet from Firecracker

Browse Source 
This code porting is based off of Firecracker commit
1e1cb6f8f8003e0bdce11d265f0feb23249a03f6

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf 2019-09-04 13:17:20 -07:00
parent 22f91ab3a2
commit df61a8fea2
6 changed files with 1502 additions and 1 deletions
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4
vm-virtio/src/queue.rs
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@ -41,11 +41,13 @@ unsafe impl ByteValued for Descriptor {}
/// A virtio descriptor chain.
pub struct DescriptorChain<'a> {
mem: &'a GuestMemoryMmap,
desc_table: GuestAddress,
queue_size: u16,
ttl: u16, // used to prevent infinite chain cycles
/// Reference to guest memory
pub mem: &'a GuestMemoryMmap,
/// Index into the descriptor table
pub index: u16,

633
vm-virtio/src/vsock/csm/connection.rs Normal file
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@ -0,0 +1,633 @@
// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//
/// The main job of `VsockConnection` is to forward data traffic, back and forth, between a
/// guest-side AF_VSOCK socket and a host-side generic `Read + Write + AsRawFd` stream, while
/// also managing its internal state.
/// To that end, `VsockConnection` implements:
/// - `VsockChannel` for:
/// - moving data from the host stream to a guest-provided RX buffer, via `recv_pkt()`; and
/// - moving data from a guest-provided TX buffer to the host stream, via `send_pkt()`; and
/// - updating its internal state, by absorbing control packets (anything other than
/// VSOCK_OP_RW).
/// - `VsockEpollListener` for getting notified about the availability of data or free buffer
/// space at the host stream.
///
/// Note: there is a certain asymmetry to the RX and TX data flows:
/// - RX transfers do not need any data buffering, since data is read straight from the
/// host stream and into the guest-provided RX buffer;
/// - TX transfers may require some data to be buffered by `VsockConnection`, if the host
/// peer can't keep up with reading the data that we're writing. This is because, once
/// the guest driver provides some data in a virtio TX buffer, the vsock device must
/// consume it. If that data can't be forwarded straight to the host stream, we'll
/// have to store it in a buffer (and flush it at a later time). Vsock flow control
/// ensures that our TX buffer doesn't overflow.
///
// The code in this file is best read with a fresh memory of the vsock protocol inner-workings.
// To help with that, here is a
//
// Short primer on the vsock protocol
// ----------------------------------
//
// 1. Establishing a connection
// A vsock connection is considered established after a two-way handshake:
// - the initiating peer sends a connection request packet (`hdr.op` == VSOCK_OP_REQUEST);
// then
// - the listening peer sends back a connection response packet (`hdr.op` ==
// VSOCK_OP_RESPONSE).
//
// 2. Terminating a connection
// When a peer wants to shut down an established connection, it sends a VSOCK_OP_SHUTDOWN
// packet. Two header flags are used with VSOCK_OP_SHUTDOWN, indicating the sender's
// intention:
// - VSOCK_FLAGS_SHUTDOWN_RCV: the sender will receive no more data for this connection; and
// - VSOCK_FLAGS_SHUTDOWN_SEND: the sender will send no more data for this connection.
// After a shutdown packet, the receiving peer will have some protocol-undefined time to
// flush its buffers, and then forcefully terminate the connection by sending back an RST
// packet. If the shutdown-initiating peer doesn't receive this RST packet during a timeout
// period, it will send one itself, thus terminating the connection.
// Note: a peer can send more than one VSOCK_OP_SHUTDOWN packets. However, read/write
// indications cannot be undone. E.g. once a "no-more-sending" promise was made, it
// cannot be taken back. That is, `hdr.flags` will be ORed between subsequent
// VSOCK_OP_SHUTDOWN packets.
//
// 3. Flow control
// Before sending a data packet (VSOCK_OP_RW), the sender must make sure that the receiver
// has enough free buffer space to store that data. If this condition is not respected, the
// receiving peer's behaviour is undefined. In this implementation, we forcefully terminate
// the connection by sending back a VSOCK_OP_RST packet.
// Note: all buffer space information is computed and stored on a per-connection basis.
// Peers keep each other informed about the free buffer space they have by filling in two
// packet header members with each packet they send:
// - `hdr.buf_alloc`: the total buffer space the peer has allocated for receiving data; and
// - `hdr.fwd_cnt`: the total number of bytes the peer has successfully flushed out of its
// buffer.
// One can figure out how much space its peer has available in its buffer by inspecting the
// difference between how much it has sent to the peer and how much the peer has flushed out
// (i.e. "forwarded", in the vsock spec terminology):
// `peer_free = peer_buf_alloc - (total_bytes_sent_to_peer - peer_fwd_cnt)`.
// Note: the above requires that peers constantly keep each other informed on their buffer
// space situation. However, since there are no receipt acknowledgement packets
// defined for the vsock protocol, packet flow can often be unidirectional (just one
// peer sending data to another), so the sender's information about the receiver's
// buffer space can get quickly outdated. The vsock protocol defines two solutions to
// this problem:
// 1. The sender can explicitly ask for a buffer space (i.e. "credit") update from its
// peer, via a VSOCK_OP_CREDIT_REQUEST packet, to which it will get a
// VSOCK_OP_CREDIT_UPDATE response (or any response will do, really, since credit
// information must be included in any packet);
// 2. The receiver can be proactive, and send VSOCK_OP_CREDIT_UPDATE packet, whenever
// it thinks its peer's information is out of date.
// Our implementation uses the proactive approach.
//
use std::io::{ErrorKind, Read, Write};
use std::num::Wrapping;
use std::os::unix::io::{AsRawFd, RawFd};
use std::time::{Duration, Instant};
use super::super::defs::uapi;
use super::super::packet::VsockPacket;
use super::super::{Result as VsockResult, VsockChannel, VsockEpollListener, VsockError};
use super::defs;
use super::txbuf::TxBuf;
use super::{ConnState, Error, PendingRx, PendingRxSet, Result};
/// A self-managing connection object, that handles communication between a guest-side AF_VSOCK
/// socket and a host-side `Read + Write + AsRawFd` stream.
///
pub struct VsockConnection<S: Read + Write + AsRawFd> {
/// The current connection state.
state: ConnState,
/// The local CID. Most of the time this will be the constant `2` (the vsock host CID).
local_cid: u64,
/// The peer (guest) CID.
peer_cid: u64,
/// The local (host) port.
local_port: u32,
/// The peer (guest) port.
peer_port: u32,
/// The (connected) host-side stream.
stream: S,
/// The TX buffer for this connection.
tx_buf: TxBuf,
/// Total number of bytes that have been successfully written to `self.stream`, either
/// directly, or flushed from `self.tx_buf`.
fwd_cnt: Wrapping<u32>,
/// The amount of buffer space that the peer (guest) has allocated for this connection.
peer_buf_alloc: u32,
/// The total number of bytes that the peer has forwarded away.
peer_fwd_cnt: Wrapping<u32>,
/// The total number of bytes sent to the peer (guest vsock driver)
rx_cnt: Wrapping<u32>,
/// Our `self.fwd_cnt`, as last sent to the peer. This is used to provide proactive credit
/// updates, and let the peer know it's OK to send more data.
last_fwd_cnt_to_peer: Wrapping<u32>,
/// The set of pending RX packet indications that `recv_pkt()` will use to fill in a
/// packet for the peer (guest).
pending_rx: PendingRxSet,
/// Instant when this connection should be scheduled for immediate termination, due to some
/// timeout condition having been fulfilled.
expiry: Option<Instant>,
}
impl<S> VsockChannel for VsockConnection<S>
where
S: Read + Write + AsRawFd,
{
/// Fill in a vsock packet, to be delivered to our peer (the guest driver).
///
/// As per the `VsockChannel` trait, this should only be called when there is data to be
/// fetched from the channel (i.e. `has_pending_rx()` is true). Otherwise, it will error
/// out with `VsockError::NoData`.
/// Pending RX indications are set by other mutable actions performed on the channel. For
/// instance, `send_pkt()` could set an Rst indication, if called with a VSOCK_OP_SHUTDOWN
/// packet, or `notify()` could set a Rw indication (a data packet can be fetched from the
/// channel), if data was ready to be read from the host stream.
///
/// Returns:
/// - `Ok(())`: the packet has been successfully filled in and is ready for delivery;
/// - `Err(VsockError::NoData)`: there was no data available with which to fill in the
/// packet;
/// - `Err(VsockError::PktBufMissing)`: the packet would've been filled in with data, but
/// it is missing the data buffer.
///
fn recv_pkt(&mut self, pkt: &mut VsockPacket) -> VsockResult<()> {
// Perform some generic initialization that is the same for any packet operation (e.g.
// source, destination, credit, etc).
self.init_pkt(pkt);
// If forceful termination is pending, there's no point in checking for anything else.
// It's dead, Jim.
if self.pending_rx.remove(PendingRx::Rst) {
pkt.set_op(uapi::VSOCK_OP_RST);
return Ok(());
}
// Next up: if we're due a connection confirmation, that's all we need to know to fill
// in this packet.
if self.pending_rx.remove(PendingRx::Response) {
self.state = ConnState::Established;
pkt.set_op(uapi::VSOCK_OP_RESPONSE);
return Ok(());
}
// Same thing goes for locally-initiated connections that need to yield a connection
// request.
if self.pending_rx.remove(PendingRx::Request) {
self.expiry =
Some(Instant::now() + Duration::from_millis(defs::CONN_REQUEST_TIMEOUT_MS));
pkt.set_op(uapi::VSOCK_OP_REQUEST);
return Ok(());
}
// A credit update is basically a no-op, so we should only waste a perfectly fine RX
// buffer on it if we really have nothing else to say.
if self.pending_rx.remove(PendingRx::CreditUpdate) && !self.has_pending_rx() {
pkt.set_op(uapi::VSOCK_OP_CREDIT_UPDATE);
self.last_fwd_cnt_to_peer = self.fwd_cnt;
return Ok(());
}
// Alright, if we got to here, we need to cough up a data packet. We've already checked
// for all other pending RX indications.
if !self.pending_rx.remove(PendingRx::Rw) {
return Err(VsockError::NoData);
}
match self.state {
// A data packet is only valid for established connections, and connections for
// which our peer has initiated a graceful shutdown, but can still receive data.
ConnState::Established | ConnState::PeerClosed(false, _) => (),
_ => {
// Any other connection state is invalid at this point, and we need to kill it
// with fire.
pkt.set_op(uapi::VSOCK_OP_RST);
return Ok(());
}
}
// Oh wait, before we start bringing in the big data, can our peer handle receiving so
// much bytey goodness?
if self.need_credit_update_from_peer() {
self.last_fwd_cnt_to_peer = self.fwd_cnt;
pkt.set_op(uapi::VSOCK_OP_CREDIT_REQUEST);
return Ok(());
}
let buf = pkt.buf_mut().ok_or(VsockError::PktBufMissing)?;
// The maximum amount of data we can read in is limited by both the RX buffer size and
// the peer available buffer space.
let max_len = std::cmp::min(buf.len(), self.peer_avail_credit());
// Read data from the stream straight to the RX buffer, for maximum throughput.
match self.stream.read(&mut buf[..max_len]) {
Ok(read_cnt) => {
if read_cnt == 0 {
// A 0-length read means the host stream was closed down. In that case,
// we'll ask our peer to shut down the connection. We can neither send nor
// receive any more data.
self.state = ConnState::LocalClosed;
self.expiry = Some(
Instant::now() + Duration::from_millis(defs::CONN_SHUTDOWN_TIMEOUT_MS),
);
pkt.set_op(uapi::VSOCK_OP_SHUTDOWN)
.set_flag(uapi::VSOCK_FLAGS_SHUTDOWN_RCV)
.set_flag(uapi::VSOCK_FLAGS_SHUTDOWN_SEND);
} else {
// On a successful data read, we fill in the packet with the RW op, and
// length of the read data.
pkt.set_op(uapi::VSOCK_OP_RW).set_len(read_cnt as u32);
}
}
Err(err) => {
// We are not expecting any errors when reading from the underlying stream. If
// any show up, we'll immediately kill this connection.
error!(
"vsock: error reading from backing stream: lp={}, pp={}, err={:?}",
self.local_port, self.peer_port, err
);
pkt.set_op(uapi::VSOCK_OP_RST);
}
};
self.rx_cnt += Wrapping(pkt.len());
self.last_fwd_cnt_to_peer = self.fwd_cnt;
Ok(())
}
/// Deliver a guest-generated packet to this connection.
///
/// This forwards the data in RW packets to the host stream, and absorbs control packets,
/// using them to manage the internal connection state.
///
/// Returns:
/// always `Ok(())`: the packet has been consumed;
///
fn send_pkt(&mut self, pkt: &VsockPacket) -> VsockResult<()> {
// Update the peer credit information.
self.peer_buf_alloc = pkt.buf_alloc();
self.peer_fwd_cnt = Wrapping(pkt.fwd_cnt());
match self.state {
// Most frequent case: this is an established connection that needs to forward some
// data to the host stream. Also works for a connection that has begun shutting
// down, but the peer still has some data to send.
ConnState::Established | ConnState::PeerClosed(_, false)
if pkt.op() == uapi::VSOCK_OP_RW =>
{
if pkt.buf().is_none() {
info!(
"vsock: dropping empty data packet from guest (lp={}, pp={}",
self.local_port, self.peer_port
);
return Ok(());
}
// Unwrapping here is safe, since we just checked `pkt.buf()` above.
let buf_slice = &pkt.buf().unwrap()[..(pkt.len() as usize)];
if let Err(err) = self.send_bytes(buf_slice) {
// If we can't write to the host stream, that's an unrecoverable error, so
// we'll terminate this connection.
warn!(
"vsock: error writing to local stream (lp={}, pp={}): {:?}",
self.local_port, self.peer_port, err
);
self.kill();
return Ok(());
}
// We might've just consumed some data. If that's the case, we might need to
// update the peer on our buffer space situation, so that it can keep sending
// data packets our way.
if self.peer_needs_credit_update() {
self.pending_rx.insert(PendingRx::CreditUpdate);
}
}
// Next up: receiving a response / confirmation for a host-initiated connection.
// We'll move to an Established state, and pass on the good news through the host
// stream.
ConnState::LocalInit if pkt.op() == uapi::VSOCK_OP_RESPONSE => {
self.expiry = None;
self.state = ConnState::Established;
}
// The peer wants to shut down an established connection. If they have nothing
// more to send nor receive, and we don't have to wait to drain our TX buffer, we
// can schedule an RST packet (to terminate the connection on the next recv call).
// Otherwise, we'll arm the kill timer.
ConnState::Established if pkt.op() == uapi::VSOCK_OP_SHUTDOWN => {
let recv_off = pkt.flags() & uapi::VSOCK_FLAGS_SHUTDOWN_RCV != 0;
let send_off = pkt.flags() & uapi::VSOCK_FLAGS_SHUTDOWN_SEND != 0;
self.state = ConnState::PeerClosed(recv_off, send_off);
if recv_off && send_off {
if self.tx_buf.is_empty() {
self.pending_rx.insert(PendingRx::Rst);
} else {
self.expiry = Some(
Instant::now() + Duration::from_millis(defs::CONN_SHUTDOWN_TIMEOUT_MS),
);
}
}
}
// The peer wants to update a shutdown request, with more receive/send indications.
// The same logic as above applies.
ConnState::PeerClosed(ref mut recv_off, ref mut send_off)
if pkt.op() == uapi::VSOCK_OP_SHUTDOWN =>
{
*recv_off = *recv_off || (pkt.flags() & uapi::VSOCK_FLAGS_SHUTDOWN_RCV != 0);
*send_off = *send_off || (pkt.flags() & uapi::VSOCK_FLAGS_SHUTDOWN_SEND != 0);
if *recv_off && *send_off && self.tx_buf.is_empty() {
self.pending_rx.insert(PendingRx::Rst);
}
}
// A credit update from our peer is valid only in a state which allows data
// transfer towards the peer.
ConnState::Established | ConnState::PeerInit | ConnState::PeerClosed(false, _)
if pkt.op() == uapi::VSOCK_OP_CREDIT_UPDATE =>
{
// Nothing to do here; we've already updated peer credit.
}
// A credit request from our peer is valid only in a state which allows data
// transfer from the peer. We'll respond with a credit update packet.
ConnState::Established | ConnState::PeerInit | ConnState::PeerClosed(_, false)
if pkt.op() == uapi::VSOCK_OP_CREDIT_REQUEST =>
{
self.pending_rx.insert(PendingRx::CreditUpdate);
}
_ => {
debug!(
"vsock: dropping invalid TX pkt for connection: state={:?}, pkt.hdr={:?}",
self.state,
pkt.hdr()
);
}
};
Ok(())
}
/// Check if the connection has any pending packet addressed to the peer.
///
fn has_pending_rx(&self) -> bool {
!self.pending_rx.is_empty()
}
}
impl<S> VsockEpollListener for VsockConnection<S>
where
S: Read + Write + AsRawFd,
{
/// Get the file descriptor that this connection wants polled.
///
/// The connection is interested in being notified about EPOLLIN / EPOLLOUT events on the
/// host stream.
///
fn get_polled_fd(&self) -> RawFd {
self.stream.as_raw_fd()
}
/// Get the event set that this connection is interested in.
///
/// A connection will want to be notified when:
/// - data is available to be read from the host stream, so that it can store an RW pending
/// RX indication; and
/// - data can be written to the host stream, and the TX buffer needs to be flushed.
///
fn get_polled_evset(&self) -> epoll::Events {
let mut evset = epoll::Events::empty();
if !self.tx_buf.is_empty() {
// There's data waiting in the TX buffer, so we are interested in being notified
// when writing to the host stream wouldn't block.
evset.insert(epoll::Events::EPOLLOUT);
}
// We're generally interested in being notified when data can be read from the host
// stream, unless we're in a state which doesn't allow moving data from host to guest.
match self.state {
ConnState::Killed | ConnState::LocalClosed | ConnState::PeerClosed(true, _) => (),
_ if self.need_credit_update_from_peer() => (),
_ => evset.insert(epoll::Events::EPOLLIN),
}
evset
}
/// Notify the connection about an event (or set of events) that it was interested in.
///
fn notify(&mut self, evset: epoll::Events) {
if evset.contains(epoll::Events::EPOLLIN) {
// Data can be read from the host stream. Setting a Rw pending indication, so that
// the muxer will know to call `recv_pkt()` later.
self.pending_rx.insert(PendingRx::Rw);
}
if evset.contains(epoll::Events::EPOLLOUT) {
// Data can be written to the host stream. Time to flush out the TX buffer.
//
if self.tx_buf.is_empty() {
info!("vsock: connection received unexpected EPOLLOUT event");
return;
}
let flushed = self
.tx_buf
.flush_to(&mut self.stream)
.unwrap_or_else(|err| {
warn!(
"vsock: error flushing TX buf for (lp={}, pp={}): {:?}",
self.local_port, self.peer_port, err
);
self.kill();
0
});
self.fwd_cnt += Wrapping(flushed as u32);
// If this connection was shutting down, but is waiting to drain the TX buffer
// before forceful termination, the wait might be over.
if self.state == ConnState::PeerClosed(true, true) && self.tx_buf.is_empty() {
self.pending_rx.insert(PendingRx::Rst);
} else if self.peer_needs_credit_update() {
// If we've freed up some more buffer space, we may need to let the peer know it
// can safely send more data our way.
self.pending_rx.insert(PendingRx::CreditUpdate);
}
}
}
}
impl<S> VsockConnection<S>
where
S: Read + Write + AsRawFd,
{
/// Create a new guest-initiated connection object.
///
pub fn new_peer_init(
stream: S,
local_cid: u64,
peer_cid: u64,
local_port: u32,
peer_port: u32,
peer_buf_alloc: u32,
) -> Self {
Self {
local_cid,
peer_cid,
local_port,
peer_port,
stream,
state: ConnState::PeerInit,
tx_buf: TxBuf::new(),
fwd_cnt: Wrapping(0),
peer_buf_alloc,
peer_fwd_cnt: Wrapping(0),
rx_cnt: Wrapping(0),
last_fwd_cnt_to_peer: Wrapping(0),
pending_rx: PendingRxSet::from(PendingRx::Response),
expiry: None,
}
}
/// Create a new host-initiated connection object.
///
pub fn new_local_init(
stream: S,
local_cid: u64,
peer_cid: u64,
local_port: u32,
peer_port: u32,
) -> Self {
Self {
local_cid,
peer_cid,
local_port,
peer_port,
stream,
state: ConnState::LocalInit,
tx_buf: TxBuf::new(),
fwd_cnt: Wrapping(0),
peer_buf_alloc: 0,
peer_fwd_cnt: Wrapping(0),
rx_cnt: Wrapping(0),
last_fwd_cnt_to_peer: Wrapping(0),
pending_rx: PendingRxSet::from(PendingRx::Request),
expiry: None,
}
}
/// Check if there is an expiry (kill) timer set for this connection, sometime in the
/// future.
///
pub fn will_expire(&self) -> bool {
match self.expiry {
None => false,
Some(t) => t > Instant::now(),
}
}
/// Check if this connection needs to be scheduled for forceful termination, due to its
/// kill timer having expired.
///
pub fn has_expired(&self) -> bool {
match self.expiry {
None => false,
Some(t) => t <= Instant::now(),
}
}
/// Get the kill timer value, if one is set.
///
pub fn expiry(&self) -> Option<Instant> {
self.expiry
}
/// Schedule the connection to be forcefully terminated ASAP (i.e. the next time the
/// connection is asked to yield a packet, via `recv_pkt()`).
///
pub fn kill(&mut self) {
self.state = ConnState::Killed;
self.pending_rx.insert(PendingRx::Rst);
}
/// Send some raw data (a byte-slice) to the host stream.
///
/// Raw data can either be sent straight to the host stream, or to our TX buffer, if the
/// former fails.
///
fn send_bytes(&mut self, buf: &[u8]) -> Result<()> {
// If there is data in the TX buffer, that means we're already registered for EPOLLOUT
// events on the underlying stream. Therefore, there's no point in attempting a write
// at this point. `self.notify()` will get called when EPOLLOUT arrives, and it will
// attempt to drain the TX buffer then.
if !self.tx_buf.is_empty() {
return self.tx_buf.push(buf);
}
// The TX buffer is empty, so we can try to write straight to the host stream.
let written = match self.stream.write(buf) {
Ok(cnt) => cnt,
Err(e) => {
// Absorb any would-block errors, since we can always try again later.
if e.kind() == ErrorKind::WouldBlock {
0
} else {
// We don't know how to handle any other write error, so we'll send it up
// the call chain.
return Err(Error::StreamWrite(e));
}
}
};
// Move the "forwarded bytes" counter ahead by how much we were able to send out.
self.fwd_cnt += Wrapping(written as u32);
// If we couldn't write the whole slice, we'll need to push the remaining data to our
// buffer.
if written < buf.len() {
self.tx_buf.push(&buf[written..])?;
}
Ok(())
}
/// Check if the credit information the peer has last received from us is outdated.
///
fn peer_needs_credit_update(&self) -> bool {
(self.fwd_cnt - self.last_fwd_cnt_to_peer).0 as usize >= defs::CONN_CREDIT_UPDATE_THRESHOLD
}
/// Check if we need to ask the peer for a credit update before sending any more data its
/// way.
///
fn need_credit_update_from_peer(&self) -> bool {
self.peer_avail_credit() == 0
}
/// Get the maximum number of bytes that we can send to our peer, without overflowing its
/// buffer.
///
fn peer_avail_credit(&self) -> usize {
(Wrapping(self.peer_buf_alloc as u32) - (self.rx_cnt - self.peer_fwd_cnt)).0 as usize
}
/// Prepare a packet header for transmission to our peer.
///
fn init_pkt<'a>(&self, pkt: &'a mut VsockPacket) -> &'a mut VsockPacket {
// Make sure the header is zeroed-out first.
// This looks sub-optimal, but it is actually optimized-out in the compiled code to be
// faster than a memset().
for b in pkt.hdr_mut() {
*b = 0;
}
pkt.set_src_cid(self.local_cid)
.set_dst_cid(self.peer_cid)
.set_src_port(self.local_port)
.set_dst_port(self.peer_port)
.set_type(uapi::VSOCK_TYPE_STREAM)
.set_buf_alloc(defs::CONN_TX_BUF_SIZE as u32)
.set_fwd_cnt(self.fwd_cnt.0)
}
}

129
vm-virtio/src/vsock/csm/mod.rs Normal file
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@ -0,0 +1,129 @@
// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//
/// This module implements our vsock connection state machine. The heavy lifting is done by
/// `connection::VsockConnection`, while this file only defines some constants and helper structs.
///
mod connection;
mod txbuf;
pub use connection::VsockConnection;
pub mod defs {
/// Vsock connection TX buffer capacity.
pub const CONN_TX_BUF_SIZE: usize = 64 * 1024;
/// After the guest thinks it has filled our TX buffer up to this limit (in bytes), we'll send
/// them a credit update packet, to let them know we can handle more.
pub const CONN_CREDIT_UPDATE_THRESHOLD: usize = CONN_TX_BUF_SIZE - 4 * 4 * 1024;
/// Connection request timeout, in millis.
pub const CONN_REQUEST_TIMEOUT_MS: u64 = 2000;
/// Connection graceful shutdown timeout, in millis.
pub const CONN_SHUTDOWN_TIMEOUT_MS: u64 = 2000;
}
#[derive(Debug)]
pub enum Error {
/// Attempted to push data to a full TX buffer.
TxBufFull,
/// An I/O error occurred, when attempting to flush the connection TX buffer.
TxBufFlush(std::io::Error),
/// An I/O error occurred, when attempting to write data to the host-side stream.
StreamWrite(std::io::Error),
}
type Result<T> = std::result::Result<T, Error>;
/// A vsock connection state.
///
#[derive(Debug, PartialEq)]
pub enum ConnState {
/// The connection has been initiated by the host end, but is yet to be confirmed by the guest.
LocalInit,
/// The connection has been initiated by the guest, but we are yet to confirm it, by sending
/// a response packet (VSOCK_OP_RESPONSE).
PeerInit,
/// The connection handshake has been performed successfully, and data can now be exchanged.
Established,
/// The host (AF_UNIX) socket was closed.
LocalClosed,
/// A VSOCK_OP_SHUTDOWN packet was received from the guest. The tuple represents the guest R/W
/// indication: (will_not_recv_anymore_data, will_not_send_anymore_data).
PeerClosed(bool, bool),
/// The connection is scheduled to be forcefully terminated as soon as possible.
Killed,
}
/// An RX indication, used by `VsockConnection` to schedule future `recv_pkt()` responses.
/// For instance, after being notified that there is available data to be read from the host stream
/// (via `notify()`), the connection will store a `PendingRx::Rw` to be later inspected by
/// `recv_pkt()`.
///
#[derive(Clone, Copy, PartialEq)]
enum PendingRx {
/// We need to yield a connection request packet (VSOCK_OP_REQUEST).
Request = 0,
/// We need to yield a connection response packet (VSOCK_OP_RESPONSE).
Response = 1,
/// We need to yield a forceful connection termination packet (VSOCK_OP_RST).
Rst = 2,
/// We need to yield a data packet (VSOCK_OP_RW), by reading from the AF_UNIX socket.
Rw = 3,
/// We need to yield a credit update packet (VSOCK_OP_CREDIT_UPDATE).
CreditUpdate = 4,
}
impl PendingRx {
/// Transform the enum value into a bitmask, that can be used for set operations.
///
fn into_mask(self) -> u16 {
1u16 << (self as u16)
}
}
/// A set of RX indications (`PendingRx` items).
///
struct PendingRxSet {
data: u16,
}
impl PendingRxSet {
/// Insert an item into the set.
///
fn insert(&mut self, it: PendingRx) {
self.data |= it.into_mask();
}
/// Remove an item from the set and return:
/// - true, if the item was in the set; or
/// - false, if the item wasn't in the set.
///
fn remove(&mut self, it: PendingRx) -> bool {
let ret = self.contains(it);
self.data &= !it.into_mask();
ret
}
/// Check if an item is present in this set.
///
fn contains(&self, it: PendingRx) -> bool {
self.data & it.into_mask() != 0
}
/// Check if the set is empty.
///
fn is_empty(&self) -> bool {
self.data == 0
}
}
/// Create a set containing only one item.
///
impl From<PendingRx> for PendingRxSet {
fn from(it: PendingRx) -> Self {
Self {
data: it.into_mask(),
}
}
}

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// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//
use std::io::Write;
use std::mem;
use std::num::Wrapping;
use super::defs;
use super::{Error, Result};
/// A simple ring-buffer implementation, used by vsock connections to buffer TX (guest -> host)
/// data. Memory for this buffer is allocated lazily, since buffering will only be needed when
/// the host can't read fast enough.
///
pub struct TxBuf {
/// The actual u8 buffer - only allocated after the first push.
data: Option<Box<[u8; Self::SIZE]>>,
/// Ring-buffer head offset - where new data is pushed to.
head: Wrapping<u32>,
/// Ring-buffer tail offset - where data is flushed from.
tail: Wrapping<u32>,
}
impl TxBuf {
/// Total buffer size, in bytes.
///
const SIZE: usize = defs::CONN_TX_BUF_SIZE;
/// Ring-buffer constructor.
///
pub fn new() -> Self {
Self {
data: None,
head: Wrapping(0),
tail: Wrapping(0),
}
}
/// Get the used length of this buffer - number of bytes that have been pushed in, but not
/// yet flushed out.
///
pub fn len(&self) -> usize {
(self.head - self.tail).0 as usize
}
/// Push a byte slice onto the ring-buffer.
///
/// Either the entire source slice will be pushed to the ring-buffer, or none of it, if
/// there isn't enough room, in which case `Err(Error::TxBufFull)` is returned.
///
pub fn push(&mut self, src: &[u8]) -> Result<()> {
// Error out if there's no room to push the entire slice.
if self.len() + src.len() > Self::SIZE {
return Err(Error::TxBufFull);
}
// We're using a closure here to return the boxed slice, instead of a value (i.e.
// `get_or_insert_with()` instead of `get_or_insert()`), because we only want the box
// created when `self.data` is None. If we were to use `get_or_insert(box)`, the box
// argument would always get evaluated (which implies a heap allocation), even though
// it would later be discarded (when `self.data.is_some()`). Apparently, clippy fails
// to see this, and insists on issuing some warning.
#[allow(clippy::redundant_closure)]
let data = self.data.get_or_insert_with(||
// Using uninitialized memory here is quite safe, since we never read from any
// area of the buffer before writing to it. First we push, then we flush only
// what had been prviously pushed.
Box::new(unsafe {mem::uninitialized::<[u8; Self::SIZE]>()}));
// Buffer head, as an offset into the data slice.
let head_ofs = self.head.0 as usize % Self::SIZE;
// Pushing a slice to this buffer can take either one or two slice copies: - one copy,
// if the slice fits between `head_ofs` and `Self::SIZE`; or - two copies, if the
// ring-buffer head wraps around.
// First copy length: we can only go from the head offset up to the total buffer size.
let len = std::cmp::min(Self::SIZE - head_ofs, src.len());
data[head_ofs..(head_ofs + len)].copy_from_slice(&src[..len]);
// If the slice didn't fit, the buffer head will wrap around, and pushing continues
// from the start of the buffer (`&self.data[0]`).
if len < src.len() {
data[..(src.len() - len)].copy_from_slice(&src[len..]);
}
// Either way, we've just pushed exactly `src.len()` bytes, so that's the amount by
// which the (wrapping) buffer head needs to move forward.
self.head += Wrapping(src.len() as u32);
Ok(())
}
/// Flush the contents of the ring-buffer to a writable stream.
///
/// Return the number of bytes that have been transferred out of the ring-buffer and into
/// the writable stream.
///
pub fn flush_to<W>(&mut self, sink: &mut W) -> Result<usize>
where
W: Write,
{
// Nothing to do, if this buffer holds no data.
if self.is_empty() {
return Ok(0);
}
// Buffer tail, as an offset into the buffer data slice.
let tail_ofs = self.tail.0 as usize % Self::SIZE;
// Flushing the buffer can take either one or two writes:
// - one write, if the tail doesn't need to wrap around to reach the head; or
// - two writes, if the tail would wrap around: tail to slice end, then slice end to
// head.
// First write length: the lesser of tail to slice end, or tail to head.
let len_to_write = std::cmp::min(Self::SIZE - tail_ofs, self.len());
// It's safe to unwrap here, since we've already checked if the buffer was empty.
let data = self.data.as_ref().unwrap();
// Issue the first write and absorb any `WouldBlock` error (we can just try again
// later).
let written = sink
.write(&data[tail_ofs..(tail_ofs + len_to_write)])
.map_err(Error::TxBufFlush)?;
// Move the buffer tail ahead by the amount (of bytes) we were able to flush out.
self.tail += Wrapping(written as u32);
// If we weren't able to flush out as much as we tried, there's no point in attempting
// our second write.
if written < len_to_write {
return Ok(written);
}
// Attempt our second write. This will return immediately if a second write isn't
// needed, since checking for an empty buffer is the first thing we do in this
// function.
Ok(written + self.flush_to(sink)?)
}
/// Check if the buffer holds any data that hasn't yet been flushed out.
///
pub fn is_empty(&self) -> bool {
self.len() == 0
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::io::Error as IoError;
use std::io::Result as IoResult;
use std::io::{ErrorKind, Write};
struct TestSink {
data: Vec<u8>,
err: Option<IoError>,
capacity: usize,
}
impl TestSink {
const DEFAULT_CAPACITY: usize = 2 * TxBuf::SIZE;
fn new() -> Self {
Self {
data: Vec::with_capacity(Self::DEFAULT_CAPACITY),
err: None,
capacity: Self::DEFAULT_CAPACITY,
}
}
}
impl Write for TestSink {
fn write(&mut self, src: &[u8]) -> IoResult<usize> {
if self.err.is_some() {
return Err(self.err.take().unwrap());
}
let len_to_push = std::cmp::min(self.capacity - self.data.len(), src.len());
self.data.extend_from_slice(&src[..len_to_push]);
Ok(len_to_push)
}
fn flush(&mut self) -> IoResult<()> {
Ok(())
}
}
impl TestSink {
fn clear(&mut self) {
self.data = Vec::with_capacity(self.capacity);
self.err = None;
}
fn set_err(&mut self, err: IoError) {
self.err = Some(err);
}
fn set_capacity(&mut self, capacity: usize) {
self.capacity = capacity;
if self.data.len() > self.capacity {
self.data.resize(self.capacity, 0);
}
}
}
#[test]
fn test_push_nowrap() {
let mut txbuf = TxBuf::new();
let mut sink = TestSink::new();
assert!(txbuf.is_empty());
assert!(txbuf.data.is_none());
txbuf.push(&[1, 2, 3, 4]).unwrap();
txbuf.push(&[5, 6, 7, 8]).unwrap();
txbuf.flush_to(&mut sink).unwrap();
assert_eq!(sink.data, [1, 2, 3, 4, 5, 6, 7, 8]);
}
#[test]
fn test_push_wrap() {
let mut txbuf = TxBuf::new();
let mut sink = TestSink::new();
let mut tmp: Vec<u8> = Vec::new();
tmp.resize(TxBuf::SIZE - 2, 0);
txbuf.push(tmp.as_slice()).unwrap();
txbuf.flush_to(&mut sink).unwrap();
sink.clear();
txbuf.push(&[1, 2, 3, 4]).unwrap();
assert_eq!(txbuf.flush_to(&mut sink).unwrap(), 4);
assert_eq!(sink.data, [1, 2, 3, 4]);
}
#[test]
fn test_push_error() {
let mut txbuf = TxBuf::new();
let mut tmp = Vec::with_capacity(TxBuf::SIZE);
tmp.resize(TxBuf::SIZE - 1, 0);
txbuf.push(tmp.as_slice()).unwrap();
match txbuf.push(&[1, 2]) {
Err(Error::TxBufFull) => (),
other => panic!("Unexpected result: {:?}", other),
}
}
#[test]
fn test_incomplete_flush() {
let mut txbuf = TxBuf::new();
let mut sink = TestSink::new();
sink.set_capacity(2);
txbuf.push(&[1, 2, 3, 4]).unwrap();
assert_eq!(txbuf.flush_to(&mut sink).unwrap(), 2);
assert_eq!(txbuf.len(), 2);
assert_eq!(sink.data, [1, 2]);
sink.set_capacity(4);
assert_eq!(txbuf.flush_to(&mut sink).unwrap(), 2);
assert!(txbuf.is_empty());
assert_eq!(sink.data, [1, 2, 3, 4]);
}
#[test]
fn test_flush_error() {
const EACCESS: i32 = 13;
let mut txbuf = TxBuf::new();
let mut sink = TestSink::new();
txbuf.push(&[1, 2, 3, 4]).unwrap();
let io_err = IoError::from_raw_os_error(EACCESS);
sink.set_err(io_err);
match txbuf.flush_to(&mut sink) {
Err(Error::TxBufFlush(ref err)) if err.kind() == ErrorKind::PermissionDenied => (),
other => panic!("Unexpected result: {:?}", other),
}
}
}

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// Use of this source code is governed by a BSD-style license that can be
// found in the THIRD-PARTY file.
mod csm;
mod device;
mod packet;
pub use self::device::Vsock;
use std::os::unix::io::RawFd;
use packet::VsockPacket;
mod defs {
/// Max vsock packet data/buffer size.
pub const MAX_PKT_BUF_SIZE: usize = 64 * 1024;
pub mod uapi {
/// Vsock packet operation IDs.
/// Defined in `/include/uapi/linux/virtio_vsock.h`.
///
/// Connection request.
pub const VSOCK_OP_REQUEST: u16 = 1;
/// Connection response.
pub const VSOCK_OP_RESPONSE: u16 = 2;
/// Connection reset.
pub const VSOCK_OP_RST: u16 = 3;
/// Connection clean shutdown.
pub const VSOCK_OP_SHUTDOWN: u16 = 4;
/// Connection data (read/write).
pub const VSOCK_OP_RW: u16 = 5;
/// Flow control credit update.
pub const VSOCK_OP_CREDIT_UPDATE: u16 = 6;
/// Flow control credit update request.
pub const VSOCK_OP_CREDIT_REQUEST: u16 = 7;
/// Vsock packet flags.
/// Defined in `/include/uapi/linux/virtio_vsock.h`.
///
/// Valid with a VSOCK_OP_SHUTDOWN packet: the packet sender will receive no more data.
pub const VSOCK_FLAGS_SHUTDOWN_RCV: u32 = 1;
/// Valid with a VSOCK_OP_SHUTDOWN packet: the packet sender will send no more data.
pub const VSOCK_FLAGS_SHUTDOWN_SEND: u32 = 2;
/// Vsock packet type.
/// Defined in `/include/uapi/linux/virtio_vsock.h`.
///
/// Stream / connection-oriented packet (the only currently valid type).
pub const VSOCK_TYPE_STREAM: u16 = 1;
pub const VSOCK_HOST_CID: u64 = 2;
}
}
#[derive(Debug)]
pub enum VsockError {
/// The vsock data/buffer virtio descriptor length is smaller than expected.
BufDescTooSmall,
/// The vsock data/buffer virtio descriptor is expected, but missing.
BufDescMissing,
/// Chained GuestMemory error.
GuestMemory,
/// Bounds check failed on guest memory pointer.
GuestMemoryBounds,
/// The vsock header descriptor length is too small.
HdrDescTooSmall(u32),
/// The vsock header `len` field holds an invalid value.
InvalidPktLen(u32),
/// A data fetch was attempted when no data was available.
NoData,
/// A data buffer was expected for the provided packet, but it is missing.
PktBufMissing,
/// Encountered an unexpected write-only virtio descriptor.
UnreadableDescriptor,
/// Encountered an unexpected read-only virtio descriptor.
UnwritableDescriptor,
}
type Result<T> = std::result::Result<T, VsockError>;
/// A passive, event-driven object, that needs to be notified whenever an epoll-able event occurs.
/// An event-polling control loop will use `get_polled_fd()` and `get_polled_evset()` to query
/// the listener for the file descriptor and the set of events it's interested in. When such an
/// event occurs, the control loop will route the event to the listener via `notify()`.
///
pub trait VsockEpollListener {
/// Get the file descriptor the listener needs polled.
fn get_polled_fd(&self) -> RawFd;
/// Get the set of events for which the listener wants to be notified.
fn get_polled_evset(&self) -> epoll::Events;
/// Notify the listener that one ore more events have occurred.
fn notify(&mut self, evset: epoll::Events);
}
/// Any channel that handles vsock packet traffic: sending and receiving packets. Since we're
/// implementing the device model here, our responsibility is to always process the sending of
/// packets (i.e. the TX queue). So, any locally generated data, addressed to the driver (e.g.
/// a connection response or RST), will have to be queued, until we get to processing the RX queue.
///
/// Note: `recv_pkt()` and `send_pkt()` are named analogous to `Read::read()` and `Write::write()`,
/// respectively. I.e.
/// - `recv_pkt(&mut pkt)` will read data from the channel, and place it into `pkt`; and
/// - `send_pkt(&pkt)` will fetch data from `pkt`, and place it into the channel.
pub trait VsockChannel {
/// Read/receive an incoming packet from the channel.
fn recv_pkt(&mut self, pkt: &mut VsockPacket) -> Result<()>;
/// Write/send a packet through the channel.
fn send_pkt(&mut self, pkt: &VsockPacket) -> Result<()>;
/// Checks whether there is pending incoming data inside the channel, meaning that a subsequent
/// call to `recv_pkt()` won't fail.
fn has_pending_rx(&self) -> bool;
}
/// The vsock backend, which is basically an epoll-event-driven vsock channel, that needs to be
/// sendable through a mpsc channel (the latter due to how `vmm::EpollContext` works).
/// Currently, the only implementation we have is `crate::virtio::unix::muxer::VsockMuxer`, which
/// translates guest-side vsock connections to host-side Unix domain socket connections.
pub trait VsockBackend: VsockChannel + VsockEpollListener + Send {}

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// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//
/// `VsockPacket` provides a thin wrapper over the buffers exchanged via virtio queues.
/// There are two components to a vsock packet, each using its own descriptor in a
/// virtio queue:
/// - the packet header; and
/// - the packet data/buffer.
/// There is a 1:1 relation between descriptor chains and packets: the first (chain head) holds
/// the header, and an optional second descriptor holds the data. The second descriptor is only
/// present for data packets (VSOCK_OP_RW).
///
/// `VsockPacket` wraps these two buffers and provides direct access to the data stored
/// in guest memory. This is done to avoid unnecessarily copying data from guest memory
/// to temporary buffers, before passing it on to the vsock backend.
///
use byteorder::{ByteOrder, LittleEndian};
use super::super::DescriptorChain;
use super::defs;
use super::{Result, VsockError};
// The vsock packet header is defined by the C struct:
//
// ```C
// struct virtio_vsock_hdr {
// le64 src_cid;
// le64 dst_cid;
// le32 src_port;
// le32 dst_port;
// le32 len;
// le16 type;
// le16 op;
// le32 flags;
// le32 buf_alloc;
// le32 fwd_cnt;
// };
// ```
//
// This structed will occupy the buffer pointed to by the head descriptor. We'll be accessing it
// as a byte slice. To that end, we define below the offsets for each field struct, as well as the
// packed struct size, as a bunch of `usize` consts.
// Note that these offsets are only used privately by the `VsockPacket` struct, the public interface
// consisting of getter and setter methods, for each struct field, that will also handle the correct
// endianess.
/// The vsock packet header struct size (when packed).
pub const VSOCK_PKT_HDR_SIZE: usize = 44;
// Source CID.
const HDROFF_SRC_CID: usize = 0;
// Destination CID.
const HDROFF_DST_CID: usize = 8;
// Source port.
const HDROFF_SRC_PORT: usize = 16;
// Destination port.
const HDROFF_DST_PORT: usize = 20;
// Data length (in bytes) - may be 0, if there is no data buffer.
const HDROFF_LEN: usize = 24;
// Socket type. Currently, only connection-oriented streams are defined by the vsock protocol.
const HDROFF_TYPE: usize = 28;
// Operation ID - one of the VSOCK_OP_* values; e.g.
// - VSOCK_OP_RW: a data packet;
// - VSOCK_OP_REQUEST: connection request;
// - VSOCK_OP_RST: forcefull connection termination;
// etc (see `super::defs::uapi` for the full list).
const HDROFF_OP: usize = 30;
// Additional options (flags) associated with the current operation (`op`).
// Currently, only used with shutdown requests (VSOCK_OP_SHUTDOWN).
const HDROFF_FLAGS: usize = 32;
// Size (in bytes) of the packet sender receive buffer (for the connection to which this packet
// belongs).
const HDROFF_BUF_ALLOC: usize = 36;
// Number of bytes the sender has received and consumed (for the connection to which this packet
// belongs). For instance, for our Unix backend, this counter would be the total number of bytes
// we have successfully written to a backing Unix socket.
const HDROFF_FWD_CNT: usize = 40;
/// The vsock packet, implemented as a wrapper over a virtq descriptor chain:
/// - the chain head, holding the packet header; and
/// - (an optional) data/buffer descriptor, only present for data packets (VSOCK_OP_RW).
///
pub struct VsockPacket {
hdr: *mut u8,
buf: Option<*mut u8>,
buf_size: usize,
}
impl VsockPacket {
/// Create the packet wrapper from a TX virtq chain head.
///
/// The chain head is expected to hold valid packet header data. A following packet buffer
/// descriptor can optionally end the chain. Bounds and pointer checks are performed when
/// creating the wrapper.
///
pub fn from_tx_virtq_head(head: &DescriptorChain) -> Result<Self> {
// All buffers in the TX queue must be readable.
//
if head.is_write_only() {
return Err(VsockError::UnreadableDescriptor);
}
// The packet header should fit inside the head descriptor.
if head.len < VSOCK_PKT_HDR_SIZE as u32 {
return Err(VsockError::HdrDescTooSmall(head.len));
}
let mut pkt = Self {
hdr: head
.mem
.get_host_address(head.addr)
.ok_or_else(|| VsockError::GuestMemory)? as *mut u8,
buf: None,
buf_size: 0,
};
// No point looking for a data/buffer descriptor, if the packet is zero-lengthed.
if pkt.len() == 0 {
return Ok(pkt);
}
// Reject weirdly-sized packets.
//
if pkt.len() > defs::MAX_PKT_BUF_SIZE as u32 {
return Err(VsockError::InvalidPktLen(pkt.len()));
}
// If the packet header showed a non-zero length, there should be a data descriptor here.
let buf_desc = head.next_descriptor().ok_or(VsockError::BufDescMissing)?;
// TX data should be read-only.
if buf_desc.is_write_only() {
return Err(VsockError::UnreadableDescriptor);
}
// The data buffer should be large enough to fit the size of the data, as described by
// the header descriptor.
if buf_desc.len < pkt.len() {
return Err(VsockError::BufDescTooSmall);
}
pkt.buf_size = buf_desc.len as usize;
pkt.buf = Some(
buf_desc
.mem
.get_host_address(buf_desc.addr)
.ok_or_else(|| VsockError::GuestMemory)? as *mut u8,
);
Ok(pkt)
}
/// Create the packet wrapper from an RX virtq chain head.
///
/// There must be two descriptors in the chain, both writable: a header descriptor and a data
/// descriptor. Bounds and pointer checks are performed when creating the wrapper.
///
pub fn from_rx_virtq_head(head: &DescriptorChain) -> Result<Self> {
// All RX buffers must be writable.
//
if !head.is_write_only() {
return Err(VsockError::UnwritableDescriptor);
}
// The packet header should fit inside the head descriptor.
if head.len < VSOCK_PKT_HDR_SIZE as u32 {
return Err(VsockError::HdrDescTooSmall(head.len));
}
// All RX descriptor chains should have a header and a data descriptor.
if !head.has_next() {
return Err(VsockError::BufDescMissing);
}
let buf_desc = head.next_descriptor().ok_or(VsockError::BufDescMissing)?;
Ok(Self {
hdr: head
.mem
.get_host_address(head.addr)
.ok_or_else(|| VsockError::GuestMemory)? as *mut u8,
buf: Some(
buf_desc
.mem
.get_host_address(buf_desc.addr)
.ok_or_else(|| VsockError::GuestMemory)? as *mut u8,
),
buf_size: buf_desc.len as usize,
})
}
/// Provides in-place, byte-slice, access to the vsock packet header.
///
pub fn hdr(&self) -> &[u8] {
// This is safe since bound checks have already been performed when creating the packet
// from the virtq descriptor.
unsafe { std::slice::from_raw_parts(self.hdr as *const u8, VSOCK_PKT_HDR_SIZE) }
}
/// Provides in-place, byte-slice, mutable access to the vsock packet header.
///
pub fn hdr_mut(&mut self) -> &mut [u8] {
// This is safe since bound checks have already been performed when creating the packet
// from the virtq descriptor.
unsafe { std::slice::from_raw_parts_mut(self.hdr, VSOCK_PKT_HDR_SIZE) }
}
/// Provides in-place, byte-slice access to the vsock packet data buffer.
///
/// Note: control packets (e.g. connection request or reset) have no data buffer associated.
/// For those packets, this method will return `None`.
/// Also note: calling `len()` on the returned slice will yield the buffer size, which may be
/// (and often is) larger than the length of the packet data. The packet data length
/// is stored in the packet header, and accessible via `VsockPacket::len()`.
pub fn buf(&self) -> Option<&[u8]> {
self.buf.map(|ptr| {
// This is safe since bound checks have already been performed when creating the packet
// from the virtq descriptor.
unsafe { std::slice::from_raw_parts(ptr as *const u8, self.buf_size) }
})
}
/// Provides in-place, byte-slice, mutable access to the vsock packet data buffer.
///
/// Note: control packets (e.g. connection request or reset) have no data buffer associated.
/// For those packets, this method will return `None`.
/// Also note: calling `len()` on the returned slice will yield the buffer size, which may be
/// (and often is) larger than the length of the packet data. The packet data length
/// is stored in the packet header, and accessible via `VsockPacket::len()`.
pub fn buf_mut(&mut self) -> Option<&mut [u8]> {
self.buf.map(|ptr| {
// This is safe since bound checks have already been performed when creating the packet
// from the virtq descriptor.
unsafe { std::slice::from_raw_parts_mut(ptr, self.buf_size) }
})
}
pub fn src_cid(&self) -> u64 {
LittleEndian::read_u64(&self.hdr()[HDROFF_SRC_CID..])
}
pub fn set_src_cid(&mut self, cid: u64) -> &mut Self {
LittleEndian::write_u64(&mut self.hdr_mut()[HDROFF_SRC_CID..], cid);
self
}
pub fn dst_cid(&self) -> u64 {
LittleEndian::read_u64(&self.hdr()[HDROFF_DST_CID..])
}
pub fn set_dst_cid(&mut self, cid: u64) -> &mut Self {
LittleEndian::write_u64(&mut self.hdr_mut()[HDROFF_DST_CID..], cid);
self
}
pub fn src_port(&self) -> u32 {
LittleEndian::read_u32(&self.hdr()[HDROFF_SRC_PORT..])
}
pub fn set_src_port(&mut self, port: u32) -> &mut Self {
LittleEndian::write_u32(&mut self.hdr_mut()[HDROFF_SRC_PORT..], port);
self
}
pub fn dst_port(&self) -> u32 {
LittleEndian::read_u32(&self.hdr()[HDROFF_DST_PORT..])
}
pub fn set_dst_port(&mut self, port: u32) -> &mut Self {
LittleEndian::write_u32(&mut self.hdr_mut()[HDROFF_DST_PORT..], port);
self
}
pub fn len(&self) -> u32 {
LittleEndian::read_u32(&self.hdr()[HDROFF_LEN..])
}
pub fn set_len(&mut self, len: u32) -> &mut Self {
LittleEndian::write_u32(&mut self.hdr_mut()[HDROFF_LEN..], len);
self
}
pub fn type_(&self) -> u16 {
LittleEndian::read_u16(&self.hdr()[HDROFF_TYPE..])
}
pub fn set_type(&mut self, type_: u16) -> &mut Self {
LittleEndian::write_u16(&mut self.hdr_mut()[HDROFF_TYPE..], type_);
self
}
pub fn op(&self) -> u16 {
LittleEndian::read_u16(&self.hdr()[HDROFF_OP..])
}
pub fn set_op(&mut self, op: u16) -> &mut Self {
LittleEndian::write_u16(&mut self.hdr_mut()[HDROFF_OP..], op);
self
}
pub fn flags(&self) -> u32 {
LittleEndian::read_u32(&self.hdr()[HDROFF_FLAGS..])
}
pub fn set_flags(&mut self, flags: u32) -> &mut Self {
LittleEndian::write_u32(&mut self.hdr_mut()[HDROFF_FLAGS..], flags);
self
}
pub fn set_flag(&mut self, flag: u32) -> &mut Self {
self.set_flags(self.flags() | flag);
self
}
pub fn buf_alloc(&self) -> u32 {
LittleEndian::read_u32(&self.hdr()[HDROFF_BUF_ALLOC..])
}
pub fn set_buf_alloc(&mut self, buf_alloc: u32) -> &mut Self {
LittleEndian::write_u32(&mut self.hdr_mut()[HDROFF_BUF_ALLOC..], buf_alloc);
self
}
pub fn fwd_cnt(&self) -> u32 {
LittleEndian::read_u32(&self.hdr()[HDROFF_FWD_CNT..])
}
pub fn set_fwd_cnt(&mut self, fwd_cnt: u32) -> &mut Self {
LittleEndian::write_u32(&mut self.hdr_mut()[HDROFF_FWD_CNT..], fwd_cnt);
self
}
}