210 lines
7.1 KiB
Rust
210 lines
7.1 KiB
Rust
#![no_main]
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#[macro_use] extern crate libfuzzer_sys;
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extern crate smoltcp;
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use std as core;
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extern crate getopts;
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use core::cmp;
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use smoltcp::phy::Loopback;
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use smoltcp::wire::{EthernetAddress, EthernetFrame, EthernetProtocol};
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use smoltcp::wire::{IpAddress, IpCidr, Ipv4Packet, Ipv6Packet, TcpPacket};
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use smoltcp::iface::{NeighborCache, EthernetInterfaceBuilder};
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use smoltcp::socket::{SocketSet, TcpSocket, TcpSocketBuffer};
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use smoltcp::time::{Duration, Instant};
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mod utils {
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include!("../utils.rs");
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}
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mod mock {
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use std::sync::Arc;
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use std::sync::atomic::{Ordering, AtomicUsize};
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use smoltcp::time::{Duration, Instant};
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// should be AtomicU64 but that's unstable
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#[derive(Debug, Clone)]
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pub struct Clock(Arc<AtomicUsize>);
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impl Clock {
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pub fn new() -> Clock {
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Clock(Arc::new(AtomicUsize::new(0)))
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}
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pub fn advance(&self, duration: Duration) {
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self.0.fetch_add(duration.total_millis() as usize, Ordering::SeqCst);
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}
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pub fn elapsed(&self) -> Instant {
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Instant::from_millis(self.0.load(Ordering::SeqCst) as i64)
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}
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}
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}
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struct TcpHeaderFuzzer([u8; 56], usize);
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impl TcpHeaderFuzzer {
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// The fuzzer won't fuzz any packets with the SYN flag set in order to make sure the connection
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// is established before the fuzzed headers arrive.
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//
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// It will also not fuzz the source and dest port so it reaches the open socket.
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//
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// Otherwise, it replaces the entire rest of the TCP header with the fuzzer's output.
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pub fn new(data: &[u8]) -> TcpHeaderFuzzer {
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let copy_len = cmp::min(data.len(), 56 /* max TCP header length without port numbers*/);
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let mut fuzzer = TcpHeaderFuzzer([0; 56], copy_len);
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fuzzer.0[..copy_len].copy_from_slice(&data[..copy_len]);
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fuzzer
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}
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}
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impl smoltcp::phy::Fuzzer for TcpHeaderFuzzer {
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fn fuzz_packet(&self, frame_data: &mut [u8]) {
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if self.1 == 0 {
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return;
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}
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let tcp_packet_offset = {
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let eth_frame = EthernetFrame::new_unchecked(&frame_data);
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EthernetFrame::<&mut [u8]>::header_len() + match eth_frame.ethertype() {
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EthernetProtocol::Ipv4 =>
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Ipv4Packet::new_unchecked(eth_frame.payload()).header_len() as usize,
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EthernetProtocol::Ipv6 =>
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Ipv6Packet::new_unchecked(eth_frame.payload()).header_len() as usize,
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_ => return
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}
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};
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let tcp_is_syn = {
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let tcp_packet = TcpPacket::new_checked(&frame_data[tcp_packet_offset..]).unwrap();
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tcp_packet.syn()
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};
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if tcp_is_syn {
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return;
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}
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if !frame_data.ends_with(b"abcdef") {
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return;
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}
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let tcp_header_len = {
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let tcp_packet = &frame_data[tcp_packet_offset..];
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(tcp_packet[12] as usize >> 4) * 4
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};
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let tcp_packet = &mut frame_data[tcp_packet_offset+4..];
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let replacement_data = &self.0[..self.1];
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let copy_len = cmp::min(replacement_data.len(), tcp_header_len);
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assert!(copy_len < tcp_packet.len());
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tcp_packet[..copy_len].copy_from_slice(&replacement_data[..copy_len]);
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}
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}
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struct EmptyFuzzer();
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impl smoltcp::phy::Fuzzer for EmptyFuzzer {
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fn fuzz_packet(&self, _: &mut [u8]) {}
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}
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fuzz_target!(|data: &[u8]| {
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let clock = mock::Clock::new();
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let device = {
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let (mut opts, mut free) = utils::create_options();
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utils::add_middleware_options(&mut opts, &mut free);
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let mut matches = utils::parse_options(&opts, free);
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let device = utils::parse_middleware_options(&mut matches, Loopback::new(),
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/*loopback=*/true);
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smoltcp::phy::FuzzInjector::new(device,
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EmptyFuzzer(),
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TcpHeaderFuzzer::new(data))
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};
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let mut neighbor_cache_entries = [None; 8];
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let neighbor_cache = NeighborCache::new(&mut neighbor_cache_entries[..]);
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let ip_addrs = [IpCidr::new(IpAddress::v4(127, 0, 0, 1), 8)];
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let mut iface = EthernetInterfaceBuilder::new(device)
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.ethernet_addr(EthernetAddress::default())
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.neighbor_cache(neighbor_cache)
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.ip_addrs(ip_addrs)
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.finalize();
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let server_socket = {
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// It is not strictly necessary to use a `static mut` and unsafe code here, but
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// on embedded systems that smoltcp targets it is far better to allocate the data
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// statically to verify that it fits into RAM rather than get undefined behavior
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// when stack overflows.
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static mut TCP_SERVER_RX_DATA: [u8; 1024] = [0; 1024];
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static mut TCP_SERVER_TX_DATA: [u8; 1024] = [0; 1024];
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let tcp_rx_buffer = TcpSocketBuffer::new(unsafe { &mut TCP_SERVER_RX_DATA[..] });
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let tcp_tx_buffer = TcpSocketBuffer::new(unsafe { &mut TCP_SERVER_TX_DATA[..] });
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TcpSocket::new(tcp_rx_buffer, tcp_tx_buffer)
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};
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let client_socket = {
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static mut TCP_CLIENT_RX_DATA: [u8; 1024] = [0; 1024];
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static mut TCP_CLIENT_TX_DATA: [u8; 1024] = [0; 1024];
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let tcp_rx_buffer = TcpSocketBuffer::new(unsafe { &mut TCP_CLIENT_RX_DATA[..] });
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let tcp_tx_buffer = TcpSocketBuffer::new(unsafe { &mut TCP_CLIENT_TX_DATA[..] });
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TcpSocket::new(tcp_rx_buffer, tcp_tx_buffer)
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};
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let mut socket_set_entries: [_; 2] = Default::default();
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let mut socket_set = SocketSet::new(&mut socket_set_entries[..]);
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let server_handle = socket_set.add(server_socket);
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let client_handle = socket_set.add(client_socket);
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let mut did_listen = false;
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let mut did_connect = false;
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let mut done = false;
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while !done && clock.elapsed() < Instant::from_millis(4_000) {
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let _ = iface.poll(&mut socket_set, clock.elapsed());
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{
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let mut socket = socket_set.get::<TcpSocket>(server_handle);
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if !socket.is_active() && !socket.is_listening() {
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if !did_listen {
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socket.listen(1234).unwrap();
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did_listen = true;
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}
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}
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if socket.can_recv() {
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socket.close();
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done = true;
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}
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}
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{
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let mut socket = socket_set.get::<TcpSocket>(client_handle);
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if !socket.is_open() {
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if !did_connect {
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socket.connect((IpAddress::v4(127, 0, 0, 1), 1234),
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(IpAddress::Unspecified, 65000)).unwrap();
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did_connect = true;
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}
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}
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if socket.can_send() {
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socket.send_slice(b"0123456789abcdef0123456789abcdef0123456789abcdef").unwrap();
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socket.close();
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}
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}
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match iface.poll_delay(&socket_set, clock.elapsed()) {
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Some(Duration { millis: 0 }) => {},
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Some(delay) => {
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clock.advance(delay)
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},
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None => clock.advance(Duration::from_millis(1))
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}
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}
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});
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