initial work towards server-side support

This commit is contained in:
lumi 2017-03-16 20:04:22 +01:00
commit 4b9f2376af
10 changed files with 759 additions and 260 deletions

239
sasl/src/server/mod.rs Normal file
View file

@ -0,0 +1,239 @@
use common::scram::ScramProvider;
use common::{Credentials, Identity};
pub trait Validator {
fn validate_credentials(&self, credentials: &Credentials) -> Result<Identity, String>;
fn request_pbkdf2<S: ScramProvider>(&self) -> Result<(Vec<u8>, usize, Vec<u8>), String>;
}
pub trait Mechanism<V: Validator> {
fn name(&self) -> &str;
fn respond(&mut self, payload: &[u8]) -> Result<Response, String>;
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Response {
Success(Identity, Vec<u8>),
Proceed(Vec<u8>),
}
pub mod mechanisms {
mod plain {
use common::{ChannelBinding, Credentials, Identity, Secret};
use server::{Mechanism, Response, Validator};
pub struct Plain<V: Validator> {
validator: V,
}
impl<V: Validator> Plain<V> {
pub fn new(validator: V) -> Plain<V> {
Plain {
validator: validator,
}
}
}
impl<V: Validator> Mechanism<V> for Plain<V> {
fn name(&self) -> &str {
"PLAIN"
}
fn respond(&mut self, payload: &[u8]) -> Result<Response, String> {
let mut sp = payload.split(|&b| b == 0);
sp.next();
let username = sp
.next()
.ok_or_else(|| "no username specified".to_owned())?;
let username =
String::from_utf8(username.to_vec()).map_err(|_| "error decoding username")?;
let password = sp
.next()
.ok_or_else(|| "no password specified".to_owned())?;
let password =
String::from_utf8(password.to_vec()).map_err(|_| "error decoding password")?;
let creds = Credentials {
identity: Identity::Username(username),
secret: Secret::password_plain(password),
channel_binding: ChannelBinding::None,
};
let ret = self.validator.validate_credentials(&creds)?;
Ok(Response::Success(ret, Vec::new()))
}
}
}
mod scram {
use std::marker::PhantomData;
use base64;
use common::scram::{generate_nonce, ScramProvider};
use common::{parse_frame, xor, ChannelBinding, Credentials, Identity, Secret};
use server::{Mechanism, Response, Validator};
enum ScramState {
Init,
SentChallenge {
initial_client_message: Vec<u8>,
initial_server_message: Vec<u8>,
gs2_header: Vec<u8>,
server_nonce: String,
username: String,
salted_password: Vec<u8>,
},
Done,
}
pub struct Scram<S: ScramProvider, V: Validator> {
name: String,
state: ScramState,
channel_binding: ChannelBinding,
validator: V,
_marker: PhantomData<S>,
}
impl<S: ScramProvider, V: Validator> Scram<S, V> {
pub fn new(validator: V, channel_binding: ChannelBinding) -> Scram<S, V> {
Scram {
name: format!("SCRAM-{}", S::name()),
state: ScramState::Init,
channel_binding: channel_binding,
validator: validator,
_marker: PhantomData,
}
}
}
impl<S: ScramProvider, V: Validator> Mechanism<V> for Scram<S, V> {
fn name(&self) -> &str {
&self.name
}
fn respond(&mut self, payload: &[u8]) -> Result<Response, String> {
let next_state;
let ret;
match self.state {
ScramState::Init => {
// TODO: really ugly, mostly because parse_frame takes a &[u8] and i don't
// want to double validate utf-8
//
// NEED TO CHANGE THIS THOUGH. IT'S AWFUL.
let mut commas = 0;
let mut idx = 0;
for &b in payload {
idx += 1;
if b == 0x2C {
commas += 1;
if commas >= 2 {
break;
}
}
}
if commas < 2 {
return Err("failed to decode message".to_owned());
}
let gs2_header = payload[..idx].to_vec();
let rest = payload[idx..].to_vec();
// TODO: process gs2 header properly, not this ugly stuff
match self.channel_binding {
ChannelBinding::None | ChannelBinding::Unsupported => {
// Not supported.
if gs2_header[0] != 0x79 {
// ord("y")
return Err("channel binding not supported".to_owned());
}
}
ref other => {
// Supported.
if gs2_header[0] == 0x79 {
// ord("y")
return Err("channel binding is supported".to_owned());
} else if !other.supports("tls-unique") {
// TODO: grab the data
return Err("channel binding mechanism incorrect".to_owned());
}
}
}
let frame = parse_frame(&rest)
.map_err(|_| "can't decode initial message".to_owned())?;
let username = frame.get("n").ok_or_else(|| "no username".to_owned())?;
let client_nonce = frame.get("r").ok_or_else(|| "no nonce".to_owned())?;
let mut server_nonce = String::new();
server_nonce += client_nonce;
server_nonce +=
&generate_nonce().map_err(|_| "failed to generate nonce".to_owned())?;
let (salt, iterations, data) = self.validator.request_pbkdf2::<S>()?;
let mut buf = Vec::new();
buf.extend(b"r=");
buf.extend(server_nonce.bytes());
buf.extend(b",s=");
buf.extend(base64::encode(&salt).bytes());
buf.extend(b",i=");
buf.extend(iterations.to_string().bytes());
ret = Response::Proceed(buf.clone());
next_state = ScramState::SentChallenge {
server_nonce: server_nonce,
username: username.to_owned(),
salted_password: data,
initial_client_message: rest,
initial_server_message: buf,
gs2_header: gs2_header,
};
}
ScramState::SentChallenge {
server_nonce: ref server_nonce,
username: ref username,
salted_password: ref salted_password,
gs2_header: ref gs2_header,
initial_client_message: ref initial_client_message,
initial_server_message: ref initial_server_message,
} => {
let frame =
parse_frame(payload).map_err(|_| "can't decode response".to_owned())?;
let mut cb_data: Vec<u8> = Vec::new();
cb_data.extend(gs2_header);
cb_data.extend(self.channel_binding.data());
let mut client_final_message_bare = Vec::new();
client_final_message_bare.extend(b"c=");
client_final_message_bare.extend(base64::encode(&cb_data).bytes());
client_final_message_bare.extend(b",r=");
client_final_message_bare.extend(server_nonce.bytes());
let client_key = S::hmac(b"Client Key", &salted_password);
let server_key = S::hmac(b"Server Key", &salted_password);
let stored_key = S::hash(&client_key);
let mut auth_message = Vec::new();
auth_message.extend(initial_client_message);
auth_message.extend(b",");
auth_message.extend(initial_server_message);
auth_message.extend(b",");
auth_message.extend(client_final_message_bare.clone());
let stored_key = S::hash(&client_key);
let client_signature = S::hmac(&auth_message, &stored_key);
let client_proof = xor(&client_key, &client_signature);
let sent_proof = frame.get("p").ok_or_else(|| "no proof".to_owned())?;
let sent_proof = base64::decode(sent_proof)
.map_err(|_| "can't decode proof".to_owned())?;
if client_proof != sent_proof {
return Err("authentication failed".to_owned());
}
let server_signature = S::hmac(&auth_message, &server_key);
let mut buf = Vec::new();
buf.extend(b"v=");
buf.extend(base64::encode(&server_signature).bytes());
ret = Response::Success(Identity::Username(username.to_owned()), buf);
next_state = ScramState::Done;
}
ScramState::Done => {
return Err("sasl session is already over".to_owned());
}
}
self.state = next_state;
Ok(ret)
}
}
}
pub use self::plain::Plain;
pub use self::scram::Scram;
}