Implement hmac-sha2-256

README.md

@@ -6,17 +6,19 @@ A ssh client and server written entirely on rust, primarily targeted at [Redox O
 
 Currently implemented features, ordered by priority:
 
-  - [ ] SSH Server
+  - [x] SSH Server
   - [ ] SSH Client
-  - [ ] Key Exchange algorithms
+  - Key Exchange algorithms
     - [ ] `diffie-hellman-group-exchange-sha1`
     - [x] `curve25519-sha256`
-  - [ ] Public Key algorithms
+  - Public Key algorithms
     - [ ] `ssh-rsa`
     - [x] `ssh-ed25519`
-  - [ ] Encryption algorithms
-    - [ ] `aes256-ctr`
+  - Encryption algorithms
+    - [x] `aes256-ctr`
     - [ ] `aes256-gcm`
+  - MAC algorithms
+    - [x] `hmac-sha2-256`
   - [ ] Port forwarding
   - [ ] SCP File Transfers
 

src/algorithm.rs

@@ -21,7 +21,7 @@ pub static ENCRYPTION: &[EncryptionAlgorithm] =
     &[EncryptionAlgorithm::AES256_CTR];
 
 /// Slice of implemented MAC algorithms, ordered by preference
-pub static MAC: &[MacAlgorithm] = &[MacAlgorithm::HMAC_SHA2_512];
+pub static MAC: &[MacAlgorithm] = &[MacAlgorithm::HMAC_SHA2_256];
 
 /// Slice of implemented compression algorithms, ordered by preference
 pub static COMPRESSION: &[CompressionAlgorithm] =

src/connection.rs

@@ -5,6 +5,7 @@ use std::sync::Arc;
 use encryption::{AesCtr, Decryptor, Encryption};
 use error::{ConnectionError, ConnectionResult};
 use key_exchange::{self, KexResult, KeyExchange};
+use mac::{Hmac, MacAlgorithm};
 use message::MessageType;
 use packet::{Packet, ReadPacketExt, WritePacketExt};
 use server::ServerConfig;
@@ -38,6 +39,8 @@ pub struct Connection {
     stream: Box<Write>,
     session_id: Option<Vec<u8>>,
     encryption: Option<(Box<Encryption>, Box<Encryption>)>,
+    mac: Option<(Box<MacAlgorithm>, Box<MacAlgorithm>)>,
+    seq: (u32, u32),
 }
 
 impl<'a> Connection {
@@ -50,6 +53,8 @@ impl<'a> Connection {
             stream: Box::new(stream),
             session_id: None,
             encryption: None,
+            mac: None,
+            seq: (0, 0),
         }
     }
 
@@ -61,20 +66,58 @@ impl<'a> Connection {
 
         loop {
             let packet = if let Some((ref mut c2s, _)) = self.encryption {
-                println!("decrypting!!!");
                 let mut decryptor = Decryptor::new(&mut **c2s, &mut reader);
                 Packet::read_from(&mut decryptor)?
             }
             else {
                 Packet::read_from(&mut reader)?
             };
-            trace!("Packet received: {:?}", packet);
+
+            if let Some((ref mut mac, _)) = self.mac {
+                let mut sig = vec![0; mac.size()];
+                reader.read_exact(&mut sig)?;
+
+                let mut sig_cmp = vec![0; mac.size()];
+                mac.sign(packet.data(), self.seq.0, sig_cmp.as_mut_slice());
+
+                if sig != sig_cmp {
+                    return Err(ConnectionError::IntegrityError);
+                }
+            }
+
+            trace!("Packet {} received: {:?}", self.seq.0, packet);
             self.process(packet)?;
+
+            self.seq.0 += 1;
         }
     }
 
-    pub fn send(&mut self, packet: &Packet) -> io::Result<()> {
-        packet.write_to(&mut self.stream)
+    pub fn send(&mut self, packet: Packet) -> io::Result<()> {
+        trace!("Sending packet {}: {:?}", self.seq.1, packet);
+
+        let packet = packet.to_raw()?;
+
+        if let Some((_, ref mut s2c)) = self.encryption {
+
+            let mut encrypted = vec![0; packet.data().len()];
+            s2c.encrypt(packet.data(), encrypted.as_mut_slice());
+
+            // Sending encrypted packet
+            self.stream.write_all(encrypted.as_slice())?;
+        }
+        else {
+            packet.write_to(&mut self.stream)?;
+        }
+
+        self.seq.1 += 1;
+
+        if let Some((_, ref mut mac)) = self.mac {
+            let mut sig = vec![0; mac.size()];
+            mac.sign(packet.data(), self.seq.1, sig.as_mut_slice());
+            self.stream.write_all(sig.as_slice())?;
+        }
+
+        Ok(())
     }
 
     fn send_id(&mut self) -> io::Result<()> {
@@ -134,18 +177,18 @@ impl<'a> Connection {
         match packet.msg_type()
         {
             MessageType::KexInit => {
-                println!("Starting Key Exchange!");
+                debug!("Starting key exchange");
                 self.kex_init(packet)
             }
             MessageType::NewKeys => {
-                println!("Switching to new Keys");
+                debug!("Switching to new keys");
 
                 let iv_c2s = self.generate_key(b"A", 256)?;
                 let iv_s2c = self.generate_key(b"B", 256)?;
                 let enc_c2s = self.generate_key(b"C", 256)?;
                 let enc_s2c = self.generate_key(b"D", 256)?;
-                let int_c2s = self.generate_key(b"E", 256)?;
-                let int_s2c = self.generate_key(b"F", 256)?;
+                let mac_c2s = self.generate_key(b"E", 256)?;
+                let mac_s2c = self.generate_key(b"F", 256)?;
 
                 self.encryption =
                     Some((
@@ -157,6 +200,29 @@ impl<'a> Connection {
                         ),
                     ));
 
+                self.mac = Some((
+                    Box::new(Hmac::new(mac_c2s.as_slice())),
+                    Box::new(Hmac::new(mac_s2c.as_slice())),
+                ));
+
+                Ok(())
+            }
+            MessageType::ServiceRequest => {
+                let mut reader = packet.reader();
+                let name = reader.read_string()?;
+
+                trace!(
+                    "{:?}",
+                    ::std::str::from_utf8(&name.as_slice()).unwrap()
+                );
+
+                let mut res = Packet::new(MessageType::ServiceAccept);
+                res.with_writer(&|w| {
+                    w.write_bytes(name.as_slice())?;
+                    Ok(())
+                })?;
+
+                self.send(res)?;
                 Ok(())
             }
             MessageType::KeyExchange(_) => {
@@ -168,7 +234,7 @@ impl<'a> Connection {
                 {
                     KexResult::Done(packet) => {
                         self.state = ConnectionState::Established;
-                        self.send(&packet)?;
+                        self.send(packet)?;
 
                         if self.session_id.is_none() {
                             self.session_id =
@@ -176,11 +242,11 @@ impl<'a> Connection {
                         }
 
                         let packet = Packet::new(MessageType::NewKeys);
-                        self.send(&packet)?;
+                        self.send(packet)?;
                         Ok(())
                     }
                     KexResult::Ok(packet) => {
-                        self.send(&packet)?;
+                        self.send(packet)?;
                         Ok(())
                     }
                     KexResult::Error => Err(ConnectionError::KeyExchangeError),
@@ -190,8 +256,8 @@ impl<'a> Connection {
                 Ok(())
             }
             _ => {
-                println!("Unhandled packet: {:?}", packet);
-                Err(ConnectionError::KeyExchangeError)
+                error!("Unhandled packet: {:?}", packet);
+                Err(ConnectionError::ProtocolError)
             }
         }
     }
@@ -220,11 +286,11 @@ impl<'a> Connection {
             let mac_algo = negotiate(MAC, mac_algos_s2c.as_slice())?;
             let comp_algo = negotiate(COMPRESSION, comp_algos_s2c.as_slice())?;
 
-            println!("Negotiated Kex Algorithm: {:?}", kex_algo);
-            println!("Negotiated Host Key Algorithm: {:?}", srv_host_key_algo);
-            println!("Negotiated Encryption Algorithm: {:?}", enc_algo);
-            println!("Negotiated Mac Algorithm: {:?}", mac_algo);
-            println!("Negotiated Comp Algorithm: {:?}", comp_algo);
+            debug!("Negotiated Kex Algorithm: {:?}", kex_algo);
+            debug!("Negotiated Host Key Algorithm: {:?}", srv_host_key_algo);
+            debug!("Negotiated Encryption Algorithm: {:?}", enc_algo);
+            debug!("Negotiated Mac Algorithm: {:?}", mac_algo);
+            debug!("Negotiated Comp Algorithm: {:?}", comp_algo);
         }
 
         // Save payload for hash generation

src/encryption/aes_ctr.rs

@@ -9,16 +9,18 @@ pub struct AesCtr {
 
 impl AesCtr {
     pub fn new(key: &[u8], iv: &[u8]) -> AesCtr {
-        AesCtr { cipher: ctr(KeySize::KeySize256, key, iv) }
+        AesCtr { cipher: ctr(KeySize::KeySize256, key, &iv[0..16]) }
     }
 }
 
 impl Encryption for AesCtr {
     fn encrypt(&mut self, data: &[u8], buf: &mut [u8]) {
+        trace!("Encrypting {} -> {}", data.len(), buf.len());
         self.cipher.process(data, buf);
     }
 
     fn decrypt(&mut self, data: &[u8], buf: &mut [u8]) {
-        self.encrypt(data, buf);
+        trace!("Decrypting {} -> {}", data.len(), buf.len());
+        self.cipher.process(data, buf);
     }
 }

src/encryption/mod.rs

@@ -27,8 +27,11 @@ impl<'a> Decryptor<'a> {
 impl<'a> Read for Decryptor<'a> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         let mut tmp = vec![0; buf.len()];
-        self.stream.read(tmp.as_mut_slice())?;
-        self.encryption.decrypt(tmp.as_slice(), buf);
-        Ok(buf.len())
+        let count = self.stream.read(tmp.as_mut_slice())?;
+        self.encryption.decrypt(
+            &tmp.as_slice()[0..count],
+            &mut buf[0..count],
+        );
+        Ok(count)
     }
 }

src/error.rs

@@ -12,6 +12,7 @@ pub enum ConnectionError {
     NegotiationError,
     KeyExchangeError,
     KeyGenerationError,
+    IntegrityError,
 }
 
 impl fmt::Display for ConnectionError {
@@ -30,6 +31,7 @@ impl Error for ConnectionError {
             &NegotiationError => "negotiation error",
             &KeyExchangeError => "key exchange error",
             &KeyGenerationError => "key generation error",
+            &IntegrityError => "integrity error",
         }
     }
 }

src/key_exchange/curve25519.rs

@@ -12,7 +12,7 @@ const ECDH_KEX_INIT: u8 = 30;
 const ECDH_KEX_REPLY: u8 = 31;
 
 pub struct Curve25519 {
-    shared_secret: Option<[u8; 32]>,
+    shared_secret: Option<Vec<u8>>,
     exchange_hash: Option<Vec<u8>>,
 }
 
@@ -65,7 +65,6 @@ impl KeyExchange for Curve25519 {
                     key
                 };
 
-                println!("Received qc: {:?}", client_public);
                 let mut packet =
                     Packet::new(MessageType::KeyExchange(ECDH_KEX_REPLY));
 
@@ -82,8 +81,14 @@ impl KeyExchange for Curve25519 {
                 };
 
                 let server_public = curve25519::curve25519_base(&server_secret);
-                let shared_secret =
-                    curve25519::curve25519(&server_secret, &client_public);
+                let shared_secret = {
+                    let mut buf = Vec::new();
+                    buf.write_mpint(BigInt::from_bytes_be(
+                        Sign::Plus,
+                        &curve25519::curve25519(&server_secret, &client_public),
+                    ));
+                    buf
+                };
 
                 let hash_data = {
                     let mut buf = Vec::new();
@@ -104,9 +109,7 @@ impl KeyExchange for Curve25519 {
                         buf.write_bytes(item);
                     }
 
-                    buf.write_mpint(
-                        BigInt::from_bytes_be(Sign::Plus, &shared_secret),
-                    );
+                    buf.write_raw_bytes(&shared_secret);
 
                     buf
                 };
@@ -115,10 +118,6 @@ impl KeyExchange for Curve25519 {
                 let hash = self.hash(&[hash_data.as_slice()]);
                 let signature = config.as_ref().key.sign(&hash).unwrap();
 
-                println!("Hash: {:?}", hash);
-                println!("Public Key: {:?}", public_key);
-                println!("Signature: {:?}", signature);
-
                 packet
                     .with_writer(&|w| {
                         w.write_bytes(public_key.as_slice())?;

src/lib.rs

@@ -12,6 +12,7 @@ mod message;
 mod connection;
 mod key_exchange;
 mod encryption;
+mod mac;
 
 pub mod public_key;
 pub mod server;

src/mac/hmac.rs

@@ -0,0 +1,35 @@
+use crypto::hmac::Hmac as rcHmac;
+use crypto::mac::Mac;
+use crypto::sha2::Sha256;
+use mac::MacAlgorithm;
+
+pub struct Hmac {
+    hmac: Box<rcHmac<Sha256>>,
+}
+
+impl Hmac {
+    pub fn new(key: &[u8]) -> Hmac {
+        let digest = Sha256::new();
+        Hmac { hmac: Box::new(rcHmac::new(digest, key)) }
+    }
+}
+
+impl MacAlgorithm for Hmac {
+    fn size(&self) -> usize {
+        32
+    }
+
+    fn sign(&mut self, data: &[u8], seq: u32, buf: &mut [u8]) {
+        let sequence = &[
+            ((seq & 0xff000000) >> 24) as u8,
+            ((seq & 0x00ff0000) >> 16) as u8,
+            ((seq & 0x0000ff00) >> 8) as u8,
+            ((seq & 0x000000ff)) as u8,
+        ];
+
+        self.hmac.input(sequence);
+        self.hmac.input(data);
+        self.hmac.raw_result(buf);
+        self.hmac.reset();
+    }
+}

src/mac/mod.rs

@@ -0,0 +1,8 @@
+mod hmac;
+
+pub use self::hmac::Hmac;
+
+pub trait MacAlgorithm {
+    fn size(&self) -> usize;
+    fn sign(&mut self, data: &[u8], seq: u32, buf: &mut [u8]);
+}

src/packet.rs

@@ -8,85 +8,137 @@ use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
 use message::MessageType;
 use num_bigint::BigInt;
 
-pub struct Packet {
-    payload: Vec<u8>,
+pub enum Packet {
+    Raw(Vec<u8>, usize),
+    Payload(Vec<u8>),
 }
 
 impl Packet {
     pub fn new(msg_type: MessageType) -> Packet {
-        Packet { payload: (&[msg_type.into()]).to_vec() }
+        Packet::Payload([msg_type.into()].to_vec())
     }
 
     pub fn msg_type(&self) -> MessageType {
-        self.payload[0].into()
-    }
-
-    pub fn payload(self) -> Vec<u8> {
-        self.payload
+        match self
+        {
+            &Packet::Raw(ref data, _) => data[5],
+            &Packet::Payload(ref data) => data[0],
+        }.into()
     }
 
     pub fn read_from<R: io::Read>(stream: &mut R) -> Result<Packet> {
-        let mac_len = 0;
-
-        trace!("Waiting for incoming packet...");
-        let packet_len = stream.read_u32::<BigEndian>()? as usize;
-        trace!("Read incoming packet ({} bytes)", packet_len);
-
-        let padding_len = stream.read_u8()? as usize;
-        let payload_len = packet_len - padding_len - 1;
-        trace!("Padding: {} bytes", padding_len);
+        let packet_len = stream.read_uint32()? as usize;
+        trace!("Reading incoming packet ({} bytes)", packet_len);
 
         // TODO: Prevent packets that are too large
 
-        let mut payload = Vec::with_capacity(payload_len);
-        let mut padding = Vec::with_capacity(padding_len);
-        // let mut mac = Vec::with_capacity(mac_len);
+        let mut raw = Vec::with_capacity(packet_len + 4);
+        raw.write_uint32(packet_len as u32)?;
 
-        trace!("Reading packet...");
-        stream.take(payload_len as u64).read_to_end(&mut payload)?;
-        trace!("Reading payload...");
-        stream.take(padding_len as u64).read_to_end(&mut padding)?;
+        let count = stream.take(packet_len as u64).read_to_end(&mut raw)?;
 
-        // if mac_len > 0 {
-        //     stream.take(mac_len as u64).read_to_end(&mut mac);
-        // }
-
-        Ok(Packet { payload: payload })
+        if count == packet_len {
+            let padding_len = raw[4] as usize;
+            let payload_len = packet_len - padding_len - 1;
+            // TODO: Verify packet size (mod 8)
+            Ok(Packet::Raw(raw, payload_len))
+        }
+        else {
+            Err(io::Error::new(io::ErrorKind::BrokenPipe, "broken stream"))
+        }
     }
 
     pub fn write_to<W: io::Write>(&self, stream: &mut W) -> Result<()> {
-        let padding_len = self.padding_len();
-        let packet_len = self.payload.len() + padding_len + 1;
+        match self
+        {
+            &Packet::Raw(ref data, _) => {
+                stream.write_all(data)?;
+                stream.flush()
+            }
+            &Packet::Payload(ref payload) => {
+                let padding_len = self.padding_len();
+                let packet_len = payload.len() + padding_len + 1;
 
-        stream.write_u32::<BigEndian>(packet_len as u32)?;
-        stream.write_u8(padding_len as u8)?;
-        stream.write(&self.payload)?;
-        stream.write(&[0u8; 255][..padding_len])?;
-        stream.flush()?;
+                stream.write_u32::<BigEndian>(packet_len as u32)?;
+                stream.write_u8(padding_len as u8)?;
+                stream.write_all(&payload)?;
+                stream.write_all(&[0u8; 255][..padding_len])?;
 
-        Ok(())
+                stream.flush()
+            }
+        }
+    }
+
+    pub fn payload(self) -> Vec<u8> {
+        match self
+        {
+            Packet::Raw(data, payload_len) => data[5..payload_len + 5].to_vec(),
+            Packet::Payload(payload) => payload,
+        }
+    }
+
+    pub fn data<'a>(&'a self) -> &'a [u8] {
+        match self
+        {
+            &Packet::Raw(ref data, _) => &data,
+            &Packet::Payload(ref payload) => &payload,
+        }
+    }
+
+    pub fn to_raw(self) -> Result<Packet> {
+        match self
+        {
+            Packet::Raw(_, _) => Ok(self),
+            Packet::Payload(ref payload) => {
+                let mut buf = Vec::with_capacity(payload.len());
+                self.write_to(&mut buf)?;
+                Ok(Packet::Raw(buf, payload.len()))
+            }
+        }
     }
 
     pub fn writer<'a>(&'a mut self) -> &'a mut Write {
-        &mut self.payload
+        match self
+        {
+            &mut Packet::Raw(ref mut data, _) => data,
+            &mut Packet::Payload(ref mut payload) => payload,
+        }
     }
 
     pub fn with_writer(&mut self, f: &Fn(&mut Write) -> Result<()>)
         -> Result<()> {
-        f(&mut self.payload)
+        f(self.writer())
     }
 
     pub fn reader<'a>(&'a self) -> BufReader<&'a [u8]> {
-        BufReader::new(&self.payload.as_slice()[1..])
+        match self
+        {
+            &Packet::Raw(ref data, payload_len) => {
+                BufReader::new(&data.as_slice()[6..payload_len + 5])
+            }
+            &Packet::Payload(ref payload) => {
+                BufReader::new(&payload.as_slice()[1..])
+            }
+        }
+    }
+
+    pub fn payload_len(&self) -> usize {
+        match self
+        {
+            &Packet::Raw(_, payload_len) => payload_len,
+            &Packet::Payload(ref payload) => payload.len(),
+        }
     }
 
     pub fn padding_len(&self) -> usize {
+        let align = 32;
+
         // Calculate the padding to reach a multiple of 8 bytes
-        let padding_len = 8 - ((self.payload.len() + 5) % 8);
+        let padding_len = align - ((self.payload_len() + 5) % align);
 
         // The padding has to be at least 4 bytes long
         if padding_len < 4 {
-            padding_len + 8
+            padding_len + align
         }
         else {
             padding_len
@@ -200,7 +252,7 @@ impl fmt::Debug for Packet {
             f,
             "Packet({:?}, {} bytes)",
             self.msg_type(),
-            self.payload.len()
+            self.payload_len()
         )
     }
 }