428 lines
13 KiB
Rust
428 lines
13 KiB
Rust
use smoltcp::socket::TcpSocket;
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use smoltcp::socket::TcpState;
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use smoltcp::socket::Socket;
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use smoltcp::socket::AnySocket;
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use smoltcp::socket::SocketRef;
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use smoltcp::socket::SocketHandle;
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use smoltcp::socket::SocketSet;
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use smoltcp::socket::TcpSocketBuffer;
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use smoltcp::wire::Ipv4Address;
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use smoltcp::wire::IpEndpoint;
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use smoltcp::Result;
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use smoltcp::Error;
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use smoltcp::iface::EthernetInterface;
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use smoltcp::time::Instant;
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use smoltcp::phy::Device;
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use byteorder::{ByteOrder, NetworkEndian, BigEndian};
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use generic_array::GenericArray;
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use core::convert::TryInto;
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use core::convert::TryFrom;
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use core::cell::RefCell;
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use rand_core::{RngCore, CryptoRng};
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use p256::{EncodedPoint, AffinePoint, ecdh::EphemeralSecret, ecdh::SharedSecret};
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use aes_gcm::{Aes128Gcm, Aes256Gcm};
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use chacha20poly1305::{ChaCha20Poly1305, Key};
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use ccm::{Ccm, consts::*};
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use aes_gcm::aes::Aes128;
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use aes_gcm::{AeadInPlace, NewAead};
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use sha2::{Sha256, Sha384, Sha512, Digest};
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use alloc::vec::{ self, Vec };
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use crate::Error as TlsError;
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use crate::tls_packet::*;
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use crate::parse::parse_tls_repr;
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use crate::cipher_suite::CipherSuite;
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use crate::buffer::TlsBuffer;
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use crate::session::{Session, TlsRole};
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#[derive(Debug, PartialEq, Eq, Clone, Copy)]
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#[allow(non_camel_case_types)]
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pub(crate) enum TlsState {
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START,
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WAIT_SH,
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WAIT_EE,
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WAIT_CERT_CR,
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WAIT_CERT,
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WAIT_CV,
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WAIT_FINISHED,
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CONNECTED,
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}
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// TODO: Group up all session_specific parameters into a separate structure
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pub struct TlsSocket<R: 'static + RngCore + CryptoRng>
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{
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state: RefCell<TlsState>,
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tcp_handle: SocketHandle,
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rng: R,
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secret: RefCell<Option<EphemeralSecret>>, // Used enum Option to allow later init
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session_id: RefCell<Option<[u8; 32]>>, // init session specific field later
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received_change_cipher_spec: RefCell<Option<bool>>,
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cipher: RefCell<Option<CipherSuite>>,
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handshake_sha256: RefCell<Sha256>,
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session: RefCell<Session>,
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}
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impl<R: RngCore + CryptoRng> TlsSocket<R> {
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pub fn new<'a, 'b, 'c>(
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sockets: &mut SocketSet<'a, 'b, 'c>,
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rx_buffer: TcpSocketBuffer<'b>,
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tx_buffer: TcpSocketBuffer<'b>,
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rng: R,
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) -> Self
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where
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'b: 'c,
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{
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let tcp_socket = TcpSocket::new(rx_buffer, tx_buffer);
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let tcp_handle = sockets.add(tcp_socket);
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TlsSocket {
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state: RefCell::new(TlsState::START),
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tcp_handle,
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rng,
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secret: RefCell::new(None),
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session_id: RefCell::new(None),
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received_change_cipher_spec: RefCell::new(None),
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cipher: RefCell::new(None),
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handshake_sha256: RefCell::new(Sha256::new()),
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session: RefCell::new(
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Session::new(TlsRole::Client)
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),
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}
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}
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pub fn tcp_connect<T, U>(
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&mut self,
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sockets: &mut SocketSet,
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remote_endpoint: T,
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local_endpoint: U,
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) -> Result<()>
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where
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T: Into<IpEndpoint>,
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U: Into<IpEndpoint>,
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{
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let mut tcp_socket = sockets.get::<TcpSocket>(self.tcp_handle);
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if tcp_socket.state() == TcpState::Established {
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Ok(())
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} else {
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tcp_socket.connect(remote_endpoint, local_endpoint)
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}
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}
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pub fn tls_connect<DeviceT>(
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&mut self,
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iface: &mut EthernetInterface<DeviceT>,
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sockets: &mut SocketSet,
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now: Instant
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) -> Result<bool>
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where
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DeviceT: for<'d> Device<'d>
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{
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// Check tcp_socket connectivity
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{
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let mut tcp_socket = sockets.get::<TcpSocket>(self.tcp_handle);
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tcp_socket.set_keep_alive(Some(smoltcp::time::Duration::from_millis(1000)));
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if tcp_socket.state() != TcpState::Established {
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return Ok(false);
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}
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}
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// Handle TLS handshake through TLS states
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let state = self.state.clone().into_inner();
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match state {
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// Initiate TLS handshake
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TlsState::START => {
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// Prepare field that is randomised,
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// Supply it to the TLS repr builder.
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let ecdh_secret = EphemeralSecret::random(&mut self.rng);
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let mut random: [u8; 32] = [0; 32];
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let mut session_id: [u8; 32] = [0; 32];
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self.rng.fill_bytes(&mut random);
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self.rng.fill_bytes(&mut session_id);
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let repr = TlsRepr::new()
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.client_hello(&ecdh_secret, random, session_id);
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// Update hash function with client hello handshake
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let mut array = [0; 2048];
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let mut buffer = TlsBuffer::new(&mut array);
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buffer.enqueue_tls_repr(repr)?;
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let slice: &[u8] = buffer.into();
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// Update hash by handshake
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// Update with entire packet except the record layer
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{
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self.handshake_sha256.borrow_mut().update(&slice[5..]);
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}
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self.send_tls_slice(sockets, slice)?;
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// Store session settings, i.e. secret, session_id
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self.secret.replace(Some(ecdh_secret));
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self.session_id.replace(Some(session_id));
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self.received_change_cipher_spec.replace(Some(false));
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// Update the TLS state
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self.state.replace(TlsState::WAIT_SH);
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},
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// TLS Client wait for Server Hello
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// No need to send anything
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TlsState::WAIT_SH => {},
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// TLS Client wait for certificate from TLS server
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// No need to send anything
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// Note: TLS server should normall send SH alongside EE
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// TLS client should jump from WAIT_SH directly to WAIT_CERT_CR directly.
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TlsState::WAIT_EE => {},
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_ => todo!()
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}
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// Poll the network interface
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iface.poll(sockets, now);
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// Read for TLS packet
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let mut array: [u8; 2048] = [0; 2048];
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let mut tls_repr_vec = self.recv_tls_repr(sockets, &mut array)?;
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// Take the TLS representation out of the vector,
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// Process as a queue
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let tls_repr_vec_size = tls_repr_vec.len();
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for index in 0..tls_repr_vec_size {
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let repr = tls_repr_vec.remove(0);
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self.process(repr)?;
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}
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Ok(self.state.clone().into_inner() == TlsState::CONNECTED)
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}
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// Process TLS ingress during handshake
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fn process(&self, repr: TlsRepr) -> Result<()> {
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let state = self.state.clone().into_inner();
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// Change_cipher_spec check:
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// Must receive CCS before recv peer's FINISH message
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// i.e. Must happen after START and before CONNECTED
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//
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// CCS message only exist for compatibility reason,
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// Drop the message and update `received_change_cipher_spec`
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if repr.is_change_cipher_spec() {
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self.received_change_cipher_spec.replace(Some(true));
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return Ok(())
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}
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match state {
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// During WAIT_SH for a TLS client, client should wait for ServerHello
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TlsState::WAIT_SH => {
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// Legacy_protocol must be TLS 1.2
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if repr.version != TlsVersion::Tls12 {
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// Abort communication
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todo!()
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}
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// TODO: Validate SH
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if repr.is_server_hello() {
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// Check SH content:
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// random: Cannot represent HelloRequestRetry
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// (TODO: Support other key shares, e.g. X25519)
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// session_id_echo: should be same as the one sent by client
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// cipher_suite: Store
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// (TODO: Check if such suite was offered)
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// compression_method: Must be null, not supported in TLS 1.3
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//
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// Check extensions:
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// supported_version: Must be TLS 1.3
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// key_share: Store key, must be in secp256r1
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// (TODO: Support other key shares ^)
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let handshake_data = &repr.handshake.as_ref().unwrap().handshake_data;
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if let HandshakeData::ServerHello(server_hello) = handshake_data {
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// Check random: Cannot be SHA-256 of "HelloRetryRequest"
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if server_hello.random == HRR_RANDOM {
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// Abort communication
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todo!()
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}
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// Check session_id_echo
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// The socket should have a session_id after moving from START state
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if self.session_id.clone().into_inner().unwrap() != server_hello.session_id_echo {
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// Abort communication
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todo!()
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}
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// Store the cipher suite
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let selected_cipher = server_hello.cipher_suite;
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if server_hello.compression_method != 0 {
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// Abort communciation
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todo!()
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}
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for extension in server_hello.extensions.iter() {
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if extension.extension_type == ExtensionType::SupportedVersions {
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if let ExtensionData::SupportedVersions(
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SupportedVersions::ServerHello {
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selected_version
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}
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) = extension.extension_data {
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if selected_version != TlsVersion::Tls13 {
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// Abort for choosing not offered TLS version
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todo!()
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}
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} else {
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// Abort for illegal extension
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todo!()
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}
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}
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if extension.extension_type == ExtensionType::KeyShare {
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if let ExtensionData::KeyShareEntry(
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KeyShareEntryContent::KeyShareServerHello {
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server_share
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}
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) = &extension.extension_data {
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// TODO: Use legitimate checking to ensure the chosen
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// group is indeed acceptable, when allowing more (EC)DHE
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// key sharing
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if server_share.group != NamedGroup::secp256r1 {
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// Abort for wrong key sharing
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todo!()
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}
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// Store key
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// It is surely from secp256r1, no other groups are permitted
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// Convert untagged bytes into encoded point on p256 eliptic curve
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// Slice the first byte out of the bytes
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let server_public = EncodedPoint::from_untagged_bytes(
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GenericArray::from_slice(&server_share.key_exchange[1..])
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);
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// TODO: Handle improper shared key
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// Right now is causes a panic, only socket abort is needed
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let secret = self.secret.replace(None);
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let shared = secret.unwrap()
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.diffie_hellman(&server_public)
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.expect("Unsupported key");
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// let cipher = match selected_cipher {
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// CipherSuite::TLS_AES_128_GCM_SHA256 => {
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// Cipher::TLS_AES_128_GCM_SHA256(
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// todo!()
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// )
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// },
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// CipherSuite::TLS_AES_256_GCM_SHA384 => {
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// Cipher::TLS_AES_256_GCM_SHA384(
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// Aes256Gcm::new(shared.as_bytes())
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// )
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// },
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// CipherSuite::TLS_CHACHA20_POLY1305_SHA256 => {
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// Cipher::TLS_CHACHA20_POLY1305_SHA256(
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// ChaCha20Poly1305::new(shared.as_bytes())
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// )
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// },
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// CipherSuite::TLS_AES_128_CCM_SHA256 => {
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// Cipher::TLS_AES_128_CCM_SHA256(
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// todo!()
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// )
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// },
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// // CCM_8 is not supported
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// // TODO: Abort communication
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// CipherSuite::TLS_AES_128_CCM_8_SHA256 => {
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// todo!()
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// }
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// };
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// self.cipher.replace(Some(cipher));
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}
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}
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}
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} else {
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// Handle invalid TLS packet
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todo!()
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}
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// This is indeed a desirable ServerHello TLS repr
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// Reprocess ServerHello into a slice
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// Update SHA256 hasher with the slice
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let mut array = [0; 2048];
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let mut buffer = TlsBuffer::new(&mut array);
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buffer.enqueue_tls_repr(repr);
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let slice: &[u8] = buffer.into();
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{
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self.handshake_sha256
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.borrow_mut()
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.update(&slice[5..]);
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}
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// Update TLS session state
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self.state.replace(TlsState::WAIT_EE);
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}
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},
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// Expect encrypted extensions after receiving SH
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TlsState::WAIT_EE => {
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// ExcepytedExtensions are disguised as ApplicationData
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// Pull out the `payload` from TlsRepr, decrypt as EE
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},
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_ => {},
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}
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Ok(())
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}
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// Generic inner send method, through TCP socket
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fn send_tls_repr(&self, sockets: &mut SocketSet, tls_repr: TlsRepr) -> Result<()> {
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let mut tcp_socket = sockets.get::<TcpSocket>(self.tcp_handle);
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if !tcp_socket.can_send() {
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return Err(Error::Illegal);
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}
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let mut array = [0; 2048];
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let mut buffer = TlsBuffer::new(&mut array);
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buffer.enqueue_tls_repr(tls_repr)?;
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let buffer_size = buffer.get_size();
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tcp_socket.send_slice(buffer.into())
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.and_then(
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|size| if size == buffer_size {
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Ok(())
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} else {
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Err(Error::Truncated)
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}
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)
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}
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// Generic inner send method for buffer IO, through TCP socket
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fn send_tls_slice(&self, sockets: &mut SocketSet, slice: &[u8]) -> Result<()> {
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let mut tcp_socket = sockets.get::<TcpSocket>(self.tcp_handle);
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if !tcp_socket.can_send() {
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return Err(Error::Illegal);
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}
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let buffer_size = slice.len();
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tcp_socket.send_slice(slice)
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.and_then(
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|size| if size == buffer_size {
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Ok(())
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} else {
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Err(Error::Truncated)
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}
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)
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}
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// Generic inner recv method, through TCP socket
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// A TCP packet can contain multiple TLS segments
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fn recv_tls_repr<'a>(&'a self, sockets: &mut SocketSet, byte_array: &'a mut [u8]) -> Result<Vec::<TlsRepr>> {
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let mut tcp_socket = sockets.get::<TcpSocket>(self.tcp_handle);
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if !tcp_socket.can_recv() {
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return Ok((Vec::new()));
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}
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let array_size = tcp_socket.recv_slice(byte_array)?;
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let mut vec: Vec<TlsRepr> = Vec::new();
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let mut bytes: &[u8] = &byte_array[..array_size];
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loop {
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match parse_tls_repr(bytes) {
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Ok((rest, repr)) => {
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vec.push(repr);
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if rest.len() == 0 {
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return Ok(vec);
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} else {
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bytes = rest;
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}
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},
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_ => return Err(Error::Unrecognized),
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};
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}
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}
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}
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