107 lines
3.6 KiB
Rust
107 lines
3.6 KiB
Rust
use crate::proxy::udp_packet_helper::UdpPacketHelper;
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use crate::proxy::Proxy;
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use anyhow::Context;
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use anyhow::Result;
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use ipnet::Ipv4Net;
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use smoltcp::wire::{
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ArpPacket, EthernetFrame, EthernetProtocol, IpProtocol, Ipv4Packet, UdpPacket,
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};
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use std::net::Ipv4Addr;
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impl Proxy<'_> {
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pub(crate) fn process_frame_from_vm(&mut self, frame: EthernetFrame<&[u8]>) -> Result<()> {
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if self.allowed_from_vm(&frame).is_none() {
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// Block packet by not forwarding it to the host
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return Ok(());
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}
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self.host
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.write(frame.as_ref())
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.map(|_| ())
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.context("failed to write to the host")
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}
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fn allowed_from_vm(&self, frame: &EthernetFrame<&[u8]>) -> Option<()> {
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if frame.src_addr() != self.vm_mac_address {
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return 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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self.allowed_from_vm_arp(arp_pkt)
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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_from_vm_ipv4(ipv4_pkt)
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}
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_ => None,
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}
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}
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fn allowed_from_vm_arp(&self, arp_pkt: ArpPacket<&[u8]>) -> Option<()> {
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if arp_pkt.source_hardware_addr() != self.vm_mac_address.0 {
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return None;
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}
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let source_protocol_addr: [u8; 4] = arp_pkt.source_protocol_addr().try_into().unwrap();
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let source_protocol_addr = Ipv4Addr::from(source_protocol_addr);
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if let Some(lease) = self.dhcp_snooper.lease() {
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if lease.valid_ip_source(source_protocol_addr.into()) {
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return Some(());
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}
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} else if source_protocol_addr.is_unspecified() {
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return Some(());
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}
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None
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}
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fn allowed_from_vm_ipv4(&self, ipv4_pkt: Ipv4Packet<&[u8]>) -> Option<()> {
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// Have we learned the VM's IP from the DHCP snooping?
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if let Some(lease) = &self.dhcp_snooper.lease() {
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// If so, allow all global traffic
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let dst_addr = Ipv4Addr::from(ipv4_pkt.dst_addr().0);
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let dst_is_global = ip_network::IpNetwork::from(dst_addr).is_global();
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if lease.valid_ip_source(ipv4_pkt.src_addr()) && dst_is_global {
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return Some(());
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}
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// Also allow all traffic to the user-specified CIDRs
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let dst_net = Ipv4Net::from(dst_addr);
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// Use get_lpm() instead of get_spm() to work around prefix-trie
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// not handling prefixes like 0.0.0.0/0 correctly[1]
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//
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// [1]: https://github.com/tiborschneider/prefix-trie/issues/8
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if self.allow.get_lpm(&dst_net).is_some() {
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return Some(());
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}
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}
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// Allow communication with host
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if ipv4_pkt.dst_addr() == self.host.gateway_ip {
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return Some(());
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}
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if ipv4_pkt.next_header() == IpProtocol::Udp {
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let udp_pkt = UdpPacket::new_checked(ipv4_pkt.payload()).ok()?;
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// Allow DNS communication with the DNS-servers provided by DHCP
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if udp_pkt.is_dns_request() && self.dhcp_snooper.valid_dns_target(&ipv4_pkt.dst_addr())
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{
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return Some(());
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}
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// Allow DHCP communication with the bootpd(8) on host via broadcast address
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if udp_pkt.is_dhcp_request() && ipv4_pkt.dst_addr().is_broadcast() {
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return Some(());
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}
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}
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None
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}
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}
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