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|
use super::device::DecryptionState;
use super::ip::inner_length;
use super::messages::TransportHeader;
use super::queue::{ParallelJob, Queue, SequentialJob};
use super::types::Callbacks;
use super::{REJECT_AFTER_MESSAGES, SIZE_TAG};
use super::super::{tun, udp, Endpoint};
use alloc::sync::Arc;
use core::sync::atomic::{AtomicBool, Ordering};
use ring::aead::{Aad, LessSafeKey, Nonce, UnboundKey, CHACHA20_POLY1305};
use spin::Mutex;
use zerocopy::{AsBytes, LayoutVerified};
struct Inner<E: Endpoint, C: Callbacks, T: tun::Writer, B: udp::Writer<E>> {
ready: AtomicBool, // job status
buffer: Mutex<(Option<E>, Vec<u8>)>, // endpoint & ciphertext buffer
state: Arc<DecryptionState<E, C, T, B>>, // decryption state (keys and replay protector)
}
pub struct ReceiveJob<E: Endpoint, C: Callbacks, T: tun::Writer, B: udp::Writer<E>>(
Arc<Inner<E, C, T, B>>,
);
impl<E: Endpoint, C: Callbacks, T: tun::Writer, B: udp::Writer<E>> Clone
for ReceiveJob<E, C, T, B>
{
fn clone(&self) -> ReceiveJob<E, C, T, B> {
ReceiveJob(self.0.clone())
}
}
impl<E: Endpoint, C: Callbacks, T: tun::Writer, B: udp::Writer<E>> ReceiveJob<E, C, T, B> {
pub fn new(
buffer: Vec<u8>,
state: Arc<DecryptionState<E, C, T, B>>,
endpoint: E,
) -> ReceiveJob<E, C, T, B> {
ReceiveJob(Arc::new(Inner {
ready: AtomicBool::new(false),
buffer: Mutex::new((Some(endpoint), buffer)),
state,
}))
}
}
impl<E: Endpoint, C: Callbacks, T: tun::Writer, B: udp::Writer<E>> ParallelJob
for ReceiveJob<E, C, T, B>
{
fn queue(&self) -> &Queue<Self> {
&self.0.state.peer.inbound
}
/* The parallel section of an incoming job:
*
* - Decryption.
* - Crypto-key routing lookup.
*
* Note: We truncate the message buffer to 0 bytes in case of authentication failure
* or crypto-key routing failure (attempted impersonation).
*
* Note: We cannot do replay protection in the parallel job,
* since this can cause dropping of packets (leaving the window) due to scheduling.
*/
fn parallel_work(&self) {
debug_assert_eq!(
self.is_ready(),
false,
"doing parallel work on completed job"
);
log::trace!("processing parallel receive job");
// decrypt
{
// closure for locking
let job = &self.0;
let peer = &job.state.peer;
let mut msg = job.buffer.lock();
// process buffer
let ok = (|| {
// cast to header followed by payload
let (header, packet): (LayoutVerified<&mut [u8], TransportHeader>, &mut [u8]) =
match LayoutVerified::new_from_prefix(&mut msg.1[..]) {
Some(v) => v,
None => return false,
};
// create nonce object
let mut nonce = [0u8; 12];
debug_assert_eq!(nonce.len(), CHACHA20_POLY1305.nonce_len());
nonce[4..].copy_from_slice(header.f_counter.as_bytes());
let nonce = Nonce::assume_unique_for_key(nonce);
// do the weird ring AEAD dance
let key = LessSafeKey::new(
UnboundKey::new(&CHACHA20_POLY1305, &job.state.keypair.recv.key[..]).unwrap(),
);
// attempt to open (and authenticate) the body
match key.open_in_place(nonce, Aad::empty(), packet) {
Ok(_) => (),
Err(_) => return false,
}
// check that counter not after reject
if header.f_counter.get() >= REJECT_AFTER_MESSAGES {
return false;
}
// check crypto-key router
packet.len() == SIZE_TAG || peer.device.table.check_route(&peer, &packet)
})();
// remove message in case of failure:
// to indicate failure and avoid later accidental use of unauthenticated data.
if !ok {
msg.1.truncate(0);
}
};
// mark ready
self.0.ready.store(true, Ordering::Release);
}
}
impl<E: Endpoint, C: Callbacks, T: tun::Writer, B: udp::Writer<E>> SequentialJob
for ReceiveJob<E, C, T, B>
{
fn is_ready(&self) -> bool {
self.0.ready.load(Ordering::Acquire)
}
fn sequential_work(self) {
debug_assert_eq!(
self.is_ready(),
true,
"doing sequential work on an incomplete job"
);
log::trace!("processing sequential receive job");
let job = &self.0;
let peer = &job.state.peer;
let mut msg = job.buffer.lock();
let endpoint = msg.0.take();
// cast transport header
let (header, packet): (LayoutVerified<&[u8], TransportHeader>, &[u8]) =
match LayoutVerified::new_from_prefix(&msg.1[..]) {
Some(v) => v,
None => {
// also covers authentication failure (will fail to parse header)
return;
}
};
// check for replay
if !job.state.protector.lock().update(header.f_counter.get()) {
log::debug!("inbound worker: replay detected");
return;
}
// check for confirms key
if !job.state.confirmed.swap(true, Ordering::SeqCst) {
log::debug!("inbound worker: message confirms key");
peer.confirm_key(&job.state.keypair);
}
// update endpoint
*peer.endpoint.lock() = endpoint;
// check if should be written to TUN
// (keep-alive and malformed packets will have no inner length)
if let Some(inner) = inner_length(packet) {
if inner + SIZE_TAG <= packet.len() {
let _ = peer.device.inbound.write(&packet[..inner]).map_err(|e| {
log::debug!("failed to write inbound packet to TUN: {:?}", e);
});
}
}
// trigger callback
C::recv(&peer.opaque, msg.1.len(), true, &job.state.keypair);
}
}
|
