484 lines
19 KiB
Rust
484 lines
19 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, parse_handshake };
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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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tcp_handle: SocketHandle,
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rng: R,
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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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tcp_handle,
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rng,
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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 tls_state = {
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self.session.borrow().get_tls_state()
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};
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match tls_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.clone());
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// Update hash function with client hello handshake
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let mut array = [0; 512];
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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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// Send the packet
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self.send_tls_slice(sockets, slice)?;
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// Update TLS session
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self.session.borrow_mut().client_update_for_ch(
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ecdh_secret,
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session_id,
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&slice[5..]
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);
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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 normally 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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// TLS Client wait for server's certificate
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// No need to send anything
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TlsState::WAIT_CERT_CR => {},
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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.session.borrow().has_completed_handshake())
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}
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// Process TLS ingress during handshake
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fn process(&self, mut repr: TlsRepr) -> Result<()> {
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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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// Note: CSS doesn't count as a proper record, no need to increment sequence number
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if repr.is_change_cipher_spec() {
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let mut session = self.session.borrow_mut();
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session.receive_change_cipher_spec();
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return Ok(())
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}
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let tls_state = {
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self.session.borrow().get_tls_state()
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};
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match tls_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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// "Cache" for ECDHE server public info
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let mut server_public: Option<EncodedPoint> = None;
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let mut selected_cipher: Option<CipherSuite> = None;
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// Process the handshake data within ServerHello
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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.borrow().verify_session_id_echo(server_hello.session_id_echo) {
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// Abort communication
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todo!()
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}
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// Note the selected cipher suite
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selected_cipher.replace(server_hello.cipher_suite);
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// TLSv13 forbidden key compression
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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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server_public.replace(
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EncodedPoint::from_untagged_bytes(
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GenericArray::from_slice(&server_share.key_exchange[1..])
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)
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);
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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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// Check that both selected_cipher and server_public were received
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if selected_cipher.is_none() || server_public.is_none() {
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// Abort communication
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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 session with required parameter
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let mut array = [0; 512];
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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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let mut session = self.session.borrow_mut();
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session.client_update_for_sh(
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selected_cipher.unwrap(),
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server_public.unwrap(),
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&slice[5..]
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);
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// Key exchange occurred, seq_num is set to 0
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// Do NOT update seq_num again. Early return.
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return Ok(());
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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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// Check that the packet is classified as application data
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if !repr.is_application_data() {
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// Abort communication, this affect IV calculation
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todo!()
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}
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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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let mut payload = repr.payload.take().unwrap();
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log::info!("Encrypted payload: {:?}", payload);
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let mut array: [u8; 5] = [0; 5];
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let mut buffer = TlsBuffer::new(&mut array);
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buffer.write_u8(repr.content_type.into())?;
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buffer.write_u16(repr.version.into())?;
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buffer.write_u16(repr.length)?;
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let associated_data: &[u8] = buffer.into();
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log::info!("Associated Data: {:?}", associated_data);
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{
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self.session.borrow_mut().decrypt_in_place(
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associated_data,
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&mut payload
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);
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}
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log::info!("decrypted EE");
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log::info!("{:?}", payload);
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// TODO: Parse payload of EE
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let parse_result = parse_handshake(&payload);
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let (_, encrypted_extensions_handshake) = parse_result
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.map_err(|_| Error::Unrecognized)?;
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// TODO: Process payload
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// Practically, nothing will be done about cookies/server name
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// Extension processing is therefore skipped
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log::info!("Parsed EE");
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self.session.borrow_mut().client_update_for_ee();
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},
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// In this stage, wait for a certificate from server
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// Parse the certificate and check its content
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TlsState::WAIT_CERT_CR => {
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// Check that the packet is classified as application data
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// Certificates transfer is disguised as application data
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if !repr.is_application_data() {
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// Abort communication, this affect IV calculation
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todo!()
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}
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// Pull out the `payload` from TlsRepr, decrypt as EE
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let mut payload = repr.payload.take().unwrap();
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// Instantiate associated data and decrypt
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let mut array: [u8; 5] = [0; 5];
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let mut buffer = TlsBuffer::new(&mut array);
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buffer.write_u8(repr.content_type.into())?;
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buffer.write_u16(repr.version.into())?;
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buffer.write_u16(repr.length)?;
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let associated_data: &[u8] = buffer.into();
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{
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self.session.borrow_mut().decrypt_in_place(
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associated_data,
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&mut payload
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);
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}
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log::info!("Decrypted payload {:?}", payload);
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},
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_ => {},
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}
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// A TLS Record was received and processed and verified
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// Increment sequence number
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self.session.borrow_mut().increment_sequence_number();
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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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// Force send to return if send is unsuccessful
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// Only update sequence number if the send is successful
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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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self.session.borrow_mut().increment_sequence_number();
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Ok(())
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}
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// Generic inner send method for buffer IO, through TCP socket
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// Usage: Push a slice representation of ONE TLS packet
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// This function will only increment sequence number by 1
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// Repeatedly call this function if sending multiple TLS packets is needed
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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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self.session.borrow_mut().increment_sequence_number();
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Ok(())
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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 records (including 0)
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// Therefore, sequence nubmer incrementation is not completed here
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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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