114 lines
3.6 KiB
Rust
114 lines
3.6 KiB
Rust
use crate::proxy::udp_packet_helper::UdpPacketHelper;
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use crate::proxy::{Action, Proxy};
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use anyhow::{Context, Result};
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use ipnet::Ipv4Net;
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use smoltcp::wire::{ArpPacket, EthernetFrame, EthernetProtocol, Ipv4Packet, UdpPacket};
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use std::net::Ipv4Addr;
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impl Proxy<'_> {
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pub(crate) fn process_frame_from_host(&mut self, frame: &EthernetFrame<&[u8]>) -> Result<()> {
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if self.allowed_from_host(frame).is_none() {
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// Block packet by not forwarding it to the VM
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return Ok(());
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}
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// Snoop bootpd(8) replies from the host to
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// figure out the IP assigned to the VM
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if frame.dst_addr() == self.vm_mac_address {
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self.snoop(frame);
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}
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match self.vm.write(frame.as_ref()) {
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Ok(_) => Ok(()),
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Err(err) => {
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if let Some(libc::ENOBUFS) = err.raw_os_error() {
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if !self.enobufs_encountered {
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sentry::capture_message(
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"No buffer space available in VM's socket",
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sentry::Level::Warning,
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);
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self.enobufs_encountered = true;
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}
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return Ok(());
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}
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Err(err).context("failed to write to the VM")
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}
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}
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}
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pub(crate) fn allowed_from_host(&self, frame: &EthernetFrame<&[u8]>) -> Option<()> {
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if frame.src_addr() == self.host.gateway_mac {
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return allowed_host_ethertype(frame);
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}
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match self.rules_mac.get(frame.src_addr().as_bytes()) {
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Some(Action::Block) => return None,
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Some(Action::Allow) => return allowed_host_ethertype(frame),
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None => {}
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}
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match frame.ethertype() {
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EthernetProtocol::Arp => {
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let arp_pkt = ArpPacket::new_checked(frame.payload()).ok()?;
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let source_protocol_addr: [u8; 4] =
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arp_pkt.source_protocol_addr().try_into().ok()?;
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self.allowed_peer_ip_from_host(Ipv4Addr::from(source_protocol_addr))
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}
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EthernetProtocol::Ipv4 => {
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let ipv4_pkt = Ipv4Packet::new_checked(frame.payload()).ok()?;
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self.allowed_peer_ip_from_host(ipv4_pkt.src_addr())
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}
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_ => None,
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}
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}
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fn allowed_peer_ip_from_host(&self, peer_ip: Ipv4Addr) -> Option<()> {
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let peer_net = Ipv4Net::from(peer_ip);
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match self.rules.get_lpm(&peer_net).map(|(_, action)| action) {
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Some(Action::Allow) => Some(()),
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Some(Action::Block) | None => None,
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}
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}
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fn snoop(&mut self, frame: &EthernetFrame<&[u8]>) {
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if frame.ethertype() != EthernetProtocol::Ipv4 {
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return;
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}
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let ipv4_pkt = match Ipv4Packet::new_checked(frame.payload()) {
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Ok(ipv4_pkt) => ipv4_pkt,
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_ => return,
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};
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if ipv4_pkt.src_addr() != self.host.gateway_ip {
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return;
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}
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if ipv4_pkt.next_header() != smoltcp::wire::IpProtocol::Udp {
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return;
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}
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let udp_pkt = match UdpPacket::new_checked(ipv4_pkt.payload()) {
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Ok(udp_pkt) => udp_pkt,
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Err(_) => return,
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};
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if !udp_pkt.is_dhcp_response() {
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return;
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}
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self.dhcp_snooper.register_dhcp_reply(udp_pkt.payload());
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}
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}
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fn allowed_host_ethertype(frame: &EthernetFrame<&[u8]>) -> Option<()> {
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match frame.ethertype() {
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EthernetProtocol::Arp | EthernetProtocol::Ipv4 => Some(()),
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_ => None,
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}
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}
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