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server: simplify verifing function #4

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Jan 7, 2024
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2 changes: 1 addition & 1 deletion crypto/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ mod verifing;
pub use builder::build_packet;
pub use keygen::rsa_keygen;
pub use protocol::NetGuardData;
pub use verifing::verify_packet;
pub use verifing::verify_knock_packet;

/// Arbitrary maximum for the auth packet
pub const MAX_PACKET_SIZE: usize = 2048;
2 changes: 1 addition & 1 deletion crypto/src/verifing.rs
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ use rsa::signature::Verifier;
use crate::builder::sha256_digest;
use crate::{NetGuardData, MAX_PACKET_SIZE};

pub fn verify_packet(
pub fn verify_knock_packet(
payload: &[u8],
verifying_key: &VerifyingKey<Sha256>,
allow_skew_seconds: u64,
Expand Down
2 changes: 1 addition & 1 deletion server/src/config.rs
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ pub struct Auth {
pub allow_skew: u64,
}

#[derive(Debug, Deserialize, Hash, Eq, PartialEq)]
#[derive(Debug, Clone, Deserialize, Hash, Eq, PartialEq)]
#[serde(rename_all = "lowercase")]
pub enum Protocol {
Tcp,
Expand Down
68 changes: 33 additions & 35 deletions server/src/worker.rs
Original file line number Diff line number Diff line change
Expand Up @@ -154,40 +154,17 @@ impl Worker {
let udp_header = UdpPacket::new(payload).ok_or(anyhow!("Malformed UDP packet"))?;
let src_port = udp_header.get_source();
let dst_port = udp_header.get_destination();
let mut entry = ConntrackEntry::new(src_ip, dst_ip, dst_port, Protocol::Udp);
let payload = udp_header.payload();

debug!("nfq {queue_num} UDP packet from {src_ip}:{src_port} to {dst_ip}:{dst_port}");

if self.is_auth_port(Protocol::Udp, dst_port) {
let payload = udp_header.payload();

match crypto::verify_packet(payload, &self.verifying_key, self.config.auth.allow_skew) {
Ok(knock_info) => {
entry.dst_port = knock_info.unlock_port;

info!(
"nfq {queue_num} allow {:?}, timestamp: {}",
entry, knock_info.timestamp
);

self.conntrack_map.add_entry(entry)?;
}
Err(e) => {
debug!("nfq {queue_num} malformed auth packet from {src_ip}:{src_port}: {e}")
}
}
} else if let Some(inst) = self.conntrack_map.get_timestamp(&entry)? {
// avoid updating timestamp every time
if Instant::now().duration_since(inst).as_secs() > 0 {
self.conntrack_map.update_timestamp(entry)?;
}

return Ok(Verdict::Accept);
let verdict =
self.verify_packet(src_ip, src_port, dst_ip, dst_port, Protocol::Udp, payload)?;
if verdict != Verdict::Accept {
sender.emit_icmpv4_unreachable(&src_ip, ip_packet, &udp_header)?;
}

sender.emit_icmpv4_unreachable(&src_ip, ip_packet, &udp_header)?;

Ok(Verdict::Drop)
Ok(verdict)
}

fn tcp_packet_handler(
Expand All @@ -201,14 +178,37 @@ impl Worker {
let tcp_header = TcpPacket::new(payload).ok_or(anyhow!("Malformed TCP packet"))?;
let src_port = tcp_header.get_source();
let dst_port = tcp_header.get_destination();
let mut entry = ConntrackEntry::new(src_ip, dst_ip, dst_port, Protocol::Tcp);
let payload = tcp_header.payload();

debug!("nfq {queue_num} TCP packet from {src_ip}:{src_port} to {dst_ip}:{dst_port}");

if self.is_auth_port(Protocol::Tcp, dst_port) {
let payload = tcp_header.payload();
let verdict =
self.verify_packet(src_ip, src_port, dst_ip, dst_port, Protocol::Tcp, payload)?;
if verdict != Verdict::Accept {
sender.emit_tcp_rst(&src_ip, &dst_ip, &tcp_header)?;
}

Ok(verdict)
}

match crypto::verify_packet(payload, &self.verifying_key, self.config.auth.allow_skew) {
fn verify_packet(
&self,
src_ip: IpAddr,
src_port: u16,
dst_ip: IpAddr,
dst_port: u16,
protocol: Protocol,
payload: &[u8],
) -> Result<Verdict> {
let queue_num = self.queue_num;
let mut entry = ConntrackEntry::new(src_ip, dst_ip, dst_port, protocol.clone());

if self.is_auth_port(protocol, dst_port) {
match crypto::verify_knock_packet(
payload,
&self.verifying_key,
self.config.auth.allow_skew,
) {
Ok(knock_info) => {
entry.dst_port = knock_info.unlock_port;

Expand All @@ -232,8 +232,6 @@ impl Worker {
return Ok(Verdict::Accept);
}

sender.emit_tcp_rst(&src_ip, &dst_ip, &tcp_header)?;

Ok(Verdict::Drop)
}

Expand Down