diff --git a/Cargo.lock b/Cargo.lock index a800e28..daca4d0 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -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" diff --git a/Cargo.toml b/Cargo.toml index a80fee5..d00cea9 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -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" diff --git a/src/lib.rs b/src/lib.rs index 4a42238..5ad8c3f 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -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, + rng: Box, } 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 { + pub fn to_bytes(self) -> Vec { 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); + 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); + } + } } diff --git a/src/main.rs b/src/main.rs index 429ffd9..f1a93ba 100644 --- a/src/main.rs +++ b/src/main.rs @@ -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")?; }