This commit is contained in:
nora 2024-08-09 15:40:01 +02:00
parent bec3621c73
commit e1b2a6e1e5
4 changed files with 187 additions and 17 deletions

8
Cargo.lock generated
View file

@ -215,7 +215,9 @@ dependencies = [
"crypto-bigint",
"ed25519-dalek",
"eyre",
"hex-literal",
"rand",
"rand_core",
"sha2",
"tokio",
"tracing",
@ -262,6 +264,12 @@ version = "0.3.9"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
[[package]]
name = "hex-literal"
version = "0.4.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "6fe2267d4ed49bc07b63801559be28c718ea06c4738b7a03c94df7386d2cde46"
[[package]]
name = "indenter"
version = "0.3.3"

View file

@ -8,8 +8,12 @@ crypto-bigint = "0.5.5"
ed25519-dalek = { version = "2.1.1" }
eyre = "0.6.12"
rand = "0.8.5"
rand_core = "0.6.4"
sha2 = "0.10.8"
tokio = { version = "1.39.2", features = ["full"] }
tracing = "0.1.40"
tracing-subscriber = { version = "0.3.18", features = ["env-filter"] }
x25519-dalek = "2.0.1"
[dev-dependencies]
hex-literal = "0.4.1"

View file

@ -25,22 +25,22 @@ macro_rules! client_error {
};
}
use core::str;
use std::{io::Write, mem::take};
use std::mem::take;
use client_error;
use ed25519_dalek::ed25519::signature::Signer;
use eyre::Context;
use parse::{MpInt, NameList, Parser, Writer};
use rand::RngCore;
use sha2::Digest;
use x25519_dalek::{EphemeralSecret, PublicKey};
// This is definitely who we are.
pub const SERVER_IDENTIFICATION: &[u8] = b"SSH-2.0-OpenSSH_9.7\r\n";
#[derive(Default)]
pub struct ServerConnection {
state: ServerState,
send_queue: Vec<Msg>,
rng: Box<dyn SshRng + Send + Sync>,
}
enum ServerState {
@ -63,10 +63,44 @@ enum ServerState {
ServiceRequest {},
}
impl Default for ServerState {
fn default() -> Self {
Self::ProtoExchange {
received: Vec::new(),
pub trait SshRng {
fn fill_bytes(&mut self, dest: &mut [u8]);
}
struct SshRngRandAdapter<'a>(&'a mut dyn SshRng);
impl rand::CryptoRng for SshRngRandAdapter<'_> {}
impl rand::RngCore for SshRngRandAdapter<'_> {
fn next_u32(&mut self) -> u32 {
self.next_u64() as u32
}
fn next_u64(&mut self) -> u64 {
rand_core::impls::next_u64_via_fill(self)
}
fn fill_bytes(&mut self, dest: &mut [u8]) {
self.0.fill_bytes(dest);
}
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> std::result::Result<(), rand::Error> {
Ok(self.fill_bytes(dest))
}
}
pub struct ThreadRngRand;
impl SshRng for ThreadRngRand {
fn fill_bytes(&mut self, dest: &mut [u8]) {
rand::thread_rng().fill_bytes(dest);
}
}
impl ServerConnection {
pub fn new(rng: impl SshRng + Send + Sync + 'static) -> Self {
Self {
state: ServerState::ProtoExchange {
received: Vec::new(),
},
send_queue: Vec::new(),
rng: Box::new(rng),
}
}
}
@ -197,7 +231,8 @@ impl ServerConnection {
Some((consumed, data)) => {
let dh = DhKeyExchangeInitPacket::parse(&data.payload)?;
let secret = EphemeralSecret::random_from_rng(rand::thread_rng());
let secret =
EphemeralSecret::random_from_rng(SshRngRandAdapter(&mut *self.rng));
let server_public_key = PublicKey::from(&secret); // f
let client_public_key = dh.e; // e
@ -210,11 +245,9 @@ impl ServerConnection {
data: PUB_HOSTKEY_BYTES,
};
let dump = std::fs::File::create("debug.bin").wrap_err("opening debug.bin")?;
let mut hash = sha2::Sha256::new();
let add_hash = |hash: &mut sha2::Sha256, bytes: &[u8]| {
hash.update(bytes);
(&dump).write_all(bytes).unwrap();
};
let hash_string = |hash: &mut sha2::Sha256, bytes: &[u8]| {
add_hash(hash, &u32::to_be_bytes(bytes.len() as u32));
@ -325,7 +358,7 @@ enum MsgKind {
impl Msg {
// TODO: MAKE THIS ZERO ALLOC AAAAAA
pub fn to_bytes_inefficient(self) -> Vec<u8> {
pub fn to_bytes(self) -> Vec<u8> {
match self.0 {
MsgKind::ServerProtocolInfo => SERVER_IDENTIFICATION.to_vec(),
MsgKind::Packet(v) => v.to_bytes(),
@ -619,7 +652,9 @@ const PRIVKEY_BYTES: &[u8; 32] = &[
#[cfg(test)]
mod tests {
use crate::{MsgKind, PacketParser, ServerConnection};
use hex_literal::hex;
use crate::{MsgKind, PacketParser, ServerConnection, SshRng};
trait OptionExt {
fn unwrap_none(self);
@ -631,9 +666,24 @@ mod tests {
}
}
struct NoRng;
impl SshRng for NoRng {
fn fill_bytes(&mut self, _: &mut [u8]) {
unreachable!()
}
}
struct HardcodedRng(Vec<u8>);
impl SshRng for HardcodedRng {
fn fill_bytes(&mut self, dest: &mut [u8]) {
dest.copy_from_slice(&self.0[..dest.len()]);
self.0.splice(0..dest.len(), []);
}
}
#[test]
fn protocol_exchange() {
let mut con = ServerConnection::default();
let mut con = ServerConnection::new(NoRng);
con.recv_bytes(b"SSH-2.0-OpenSSH_9.7\r\n").unwrap();
let msg = con.next_message_to_send().unwrap();
assert_eq!(msg.0, MsgKind::ServerProtocolInfo);
@ -641,7 +691,7 @@ mod tests {
#[test]
fn protocol_exchange_slow_client() {
let mut con = ServerConnection::default();
let mut con = ServerConnection::new(NoRng);
con.recv_bytes(b"SSH-2.0-").unwrap();
con.recv_bytes(b"OpenSSH_9.7\r\n").unwrap();
let msg = con.next_message_to_send().unwrap();
@ -678,4 +728,112 @@ mod tests {
assert_eq!(consumed, 6);
assert_eq!(data, &[1, 2]);
}
#[test]
fn handshake() {
#[rustfmt::skip]
let rng = vec![
0x14, 0xa2, 0x04, 0xa5, 0x4b, 0x2f, 0x5f, 0xa7, 0xff, 0x53, 0x13, 0x67, 0x57, 0x67, 0xbc, 0x55,
0x3f, 0xc0, 0x6c, 0x0d, 0x07, 0x8f, 0xe2, 0x75, 0x95, 0x18, 0x4b, 0xd2, 0xcb, 0xd0, 0x64, 0x06,
];
struct Part {
client: &'static [u8],
server: &'static [u8],
}
// Extracted from a real OpenSSH client using this server (with hardcoded creds) using Wireshark.
let conversation = [
Part {
client: &hex!("5353482d322e302d4f70656e5353485f392e370d0a"),
server: &hex!("5353482d322e302d4f70656e5353485f392e370d0a"),
},
// KEX Init
Part {
client: &hex!(
"
000005fc071401af35150e67f2bc6dc4bc6b5330901900000131736e74727570373631783235353
1392d736861353132406f70656e7373682e636f6d2c637572766532353531392d7368613235362c
637572766532353531392d736861323536406c69627373682e6f72672c656364682d736861322d6
e697374703235362c656364682d736861322d6e697374703338342c656364682d736861322d6e69
7374703532312c6469666669652d68656c6c6d616e2d67726f75702d65786368616e67652d73686
13235362c6469666669652d68656c6c6d616e2d67726f757031362d7368613531322c6469666669
652d68656c6c6d616e2d67726f757031382d7368613531322c6469666669652d68656c6c6d616e2
d67726f757031342d7368613235362c6578742d696e666f2d632c6b65782d7374726963742d632d
763030406f70656e7373682e636f6d000001cf7373682d656432353531392d636572742d7630314
06f70656e7373682e636f6d2c65636473612d736861322d6e697374703235362d636572742d7630
31406f70656e7373682e636f6d2c65636473612d736861322d6e697374703338342d636572742d7
63031406f70656e7373682e636f6d2c65636473612d736861322d6e697374703532312d63657274
2d763031406f70656e7373682e636f6d2c736b2d7373682d656432353531392d636572742d76303
1406f70656e7373682e636f6d2c736b2d65636473612d736861322d6e697374703235362d636572
742d763031406f70656e7373682e636f6d2c7273612d736861322d3531322d636572742d7630314
06f70656e7373682e636f6d2c7273612d736861322d3235362d636572742d763031406f70656e73
73682e636f6d2c7373682d656432353531392c65636473612d736861322d6e697374703235362c6
5636473612d736861322d6e697374703338342c65636473612d736861322d6e697374703532312c
736b2d7373682d65643235353139406f70656e7373682e636f6d2c736b2d65636473612d7368613
22d6e69737470323536406f70656e7373682e636f6d2c7273612d736861322d3531322c7273612d
736861322d3235360000006c63686163686132302d706f6c7931333035406f70656e7373682e636
f6d2c6165733132382d6374722c6165733139322d6374722c6165733235362d6374722c61657331
32382d67636d406f70656e7373682e636f6d2c6165733235362d67636d406f70656e7373682e636
f6d0000006c63686163686132302d706f6c7931333035406f70656e7373682e636f6d2c61657331
32382d6374722c6165733139322d6374722c6165733235362d6374722c6165733132382d67636d4
06f70656e7373682e636f6d2c6165733235362d67636d406f70656e7373682e636f6d000000d575
6d61632d36342d65746d406f70656e7373682e636f6d2c756d61632d3132382d65746d406f70656
e7373682e636f6d2c686d61632d736861322d3235362d65746d406f70656e7373682e636f6d2c68
6d61632d736861322d3531322d65746d406f70656e7373682e636f6d2c686d61632d736861312d6
5746d406f70656e7373682e636f6d2c756d61632d3634406f70656e7373682e636f6d2c756d6163
2d313238406f70656e7373682e636f6d2c686d61632d736861322d3235362c686d61632d7368613
22d3531322c686d61632d73686131000000d5756d61632d36342d65746d406f70656e7373682e63
6f6d2c756d61632d3132382d65746d406f70656e7373682e636f6d2c686d61632d736861322d323
5362d65746d406f70656e7373682e636f6d2c686d61632d736861322d3531322d65746d406f7065
6e7373682e636f6d2c686d61632d736861312d65746d406f70656e7373682e636f6d2c756d61632
d3634406f70656e7373682e636f6d2c756d61632d313238406f70656e7373682e636f6d2c686d61
632d736861322d3235362c686d61632d736861322d3531322c686d61632d736861310000001a6e6
f6e652c7a6c6962406f70656e7373682e636f6d2c7a6c69620000001a6e6f6e652c7a6c6962406f
70656e7373682e636f6d2c7a6c69620000000000000000000000000000000000000000
"
),
server: &hex!(
"
000000c40d140000000000000000000000000000000000000011637572766532353531392d73686
13235360000000b7373682d656432353531390000001d63686163686132302d706f6c7931333035
406f70656e7373682e636f6d0000001d63686163686132302d706f6c7931333035406f70656e737
3682e636f6d0000000d686d61632d736861322d3235360000000d686d61632d736861322d323536
000000046e6f6e65000000046e6f6e6500000000000000000000000000000000000000000000000
00000
"
),
},
// ECDH KEX Init
Part {
client: &hex!(
"
0000002c061e0000002086ac62fd02ac3333e2470f6024d0027696b29056f281f6fde0c05956fcf
d3a53000000000000
"
),
server: &hex!(
"
000000bc081f000000330000000b7373682d6564323535313900000020e939cdfa6fc0d737333b5
34e913dd332c8d5179fe00c3045575217224b19b8f6000000203b92eb7008cc13056bc9f198049f
75d5832f3650969dfcccd80841431b350160000000530000000b7373682d6564323535313900000
04096ba808246f3b76270475d495330bfe174043609e81be35eadcabc0537ddcf8c4502831e9fef
f2ef0e49cbe93e1747c01e2c9a6d19839648694defeb2adc77060000000000000000
"
),
},
// New Keys
Part {
client: &hex!("0000000c0a1500000000000000000000"),
server: &hex!("0000000c0a1500000000000000000000"),
},
];
let mut con = ServerConnection::new(HardcodedRng(rng));
for part in conversation {
con.recv_bytes(&part.client).unwrap();
let bytes = con.next_message_to_send().unwrap().to_bytes();
assert_eq!(part.server, bytes);
}
}
}

View file

@ -1,7 +1,7 @@
use std::net::SocketAddr;
use eyre::{Context, Result};
use fakessh::{ServerConnection, SshError};
use fakessh::{ServerConnection, SshError, ThreadRngRand};
use tokio::{
io::{AsyncReadExt, AsyncWriteExt},
net::{TcpListener, TcpStream},
@ -32,7 +32,7 @@ async fn handle_connection(next: (TcpStream, SocketAddr)) -> Result<()> {
info!(?addr, "Received a new connection");
let mut state = ServerConnection::default();
let mut state = ServerConnection::new(ThreadRngRand);
loop {
let mut buf = [0; 1024];
@ -57,7 +57,7 @@ async fn handle_connection(next: (TcpStream, SocketAddr)) -> Result<()> {
}
while let Some(msg) = state.next_message_to_send() {
conn.write_all(&msg.to_bytes_inefficient())
conn.write_all(&msg.to_bytes())
.await
.wrap_err("writing response")?;
}