1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403
use std::fmt;
use actix_http::BoxedPayloadStream;
use actix_web::{dev, web::Bytes, Error, FromRequest, HttpRequest};
use async_trait::async_trait;
use derive_more::Display;
use futures_core::future::LocalBoxFuture;
use futures_util::{FutureExt as _, StreamExt as _, TryFutureExt as _};
use local_channel::mpsc;
use tokio::try_join;
use tracing::trace;
/// Define a scheme for deriving and verifying some kind of signature from request parts.
///
/// There are 4 phases to calculating a signature while a request is being received:
/// 1. [Initialize](Self::init): Construct the signature scheme type and perform any pre-body
/// calculation steps with request head parts.
/// 1. [Consume body](Self::consume_chunk): For each body chunk received, fold it to the signature
/// calculation.
/// 1. [Finalize](Self::finalize): Perform post-body calculation steps and finalize signature type.
/// 1. [Verify](Self::verify): Check the _true signature_ against a _candidate signature_; for
/// example, a header added by the client. This phase is optional.
///
/// You'll need to use the [`async-trait`](https://docs.rs/async-trait) when implementing. Annotate
/// your implementations with `#[async_trait(?Send)]`.
///
/// # Bring Your Own Crypto
/// It is up to the implementor to ensure that best security practices are being followed when
/// implementing this trait, and in particular the `verify` method. There is no inherent preference
/// for certain crypto ecosystems though many of the examples shown here will use types from
/// [RustCrypto](https://github.com/RustCrypto).
///
/// # `RequestSignature` Extractor
/// Types that implement this trait can be used with the [`RequestSignature`] extractor to
/// declaratively derive the request signature alongside the desired body extractor.
///
/// # Examples
/// This trait can be used to define:
/// - API authentication schemes that requires a signature to be attached to the request, either
/// with static keys or dynamic, per-user keys that are looked asynchronously from a database.
/// - Request hashes derived from specific parts for cache lookups.
///
/// This example implementation does a simple HMAC calculation on the body using a static key.
/// It does not implement verification.
/// ```
/// use actix_web::{web::Bytes, Error, HttpRequest};
/// use actix_web_lab::extract::RequestSignatureScheme;
/// use async_trait::async_trait;
/// use hmac::{digest::CtOutput, Mac, SimpleHmac};
/// use sha2::Sha256;
///
/// struct AbcApi {
/// /// Running state.
/// hmac: SimpleHmac<Sha256>,
/// }
///
/// #[async_trait(?Send)]
/// impl RequestSignatureScheme for AbcApi {
/// /// The constant-time verifiable output of the HMAC type.
/// type Signature = CtOutput<SimpleHmac<Sha256>>;
/// type Error = Error;
///
/// async fn init(req: &HttpRequest) -> Result<Self, Self::Error> {
/// // acquire HMAC signing key
/// let key = req.app_data::<[u8; 32]>().unwrap();
///
/// // construct HMAC signer
/// let hmac = SimpleHmac::new_from_slice(&key[..]).unwrap();
/// Ok(AbcApi { hmac })
/// }
///
/// async fn consume_chunk(
/// &mut self,
/// _req: &HttpRequest,
/// chunk: Bytes,
/// ) -> Result<(), Self::Error> {
/// // digest body chunk
/// self.hmac.update(&chunk);
/// Ok(())
/// }
///
/// async fn finalize(self, _req: &HttpRequest) -> Result<Self::Signature, Self::Error> {
/// // construct signature type
/// Ok(self.hmac.finalize())
/// }
/// }
/// ```
#[async_trait(?Send)]
pub trait RequestSignatureScheme: Sized {
/// The signature type returned from [`finalize`](Self::finalize) and checked in
/// [`verify`](Self::verify).
///
/// Ideally, this type has constant-time equality capabilities.
type Signature;
/// Error type used by all trait methods to signal missing precondition, processing errors, or
/// verification failures.
///
/// Must be convertible to an error response; i.e., implements [`ResponseError`].
///
/// [`ResponseError`]: https://docs.rs/actix-web/4/actix_web/trait.ResponseError.html
type Error: Into<Error>;
/// Initialize signature scheme for incoming request.
///
/// Possible steps that should be included in `init` implementations:
/// - initialization of signature scheme type
/// - key lookup / initialization
/// - pre-body digest updates
async fn init(req: &HttpRequest) -> Result<Self, Self::Error>;
/// Fold received body chunk into signature.
///
/// If processing the request body one chunk at a time is not equivalent to processing it all at
/// once, then the chunks will need to be added to a buffer.
async fn consume_chunk(&mut self, req: &HttpRequest, chunk: Bytes) -> Result<(), Self::Error>;
/// Finalize and output `Signature` type.
///
/// Possible steps that should be included in `finalize` implementations:
/// - post-body digest updates
/// - signature finalization
async fn finalize(self, req: &HttpRequest) -> Result<Self::Signature, Self::Error>;
/// Verify _true signature_ against _candidate signature_.
///
/// The _true signature_ is what has been calculated during request processing by the other
/// methods in this trait. The _candidate signature_ might be a signature provided by the client
/// in order to prove ownership of a key or some other known signature to validate against.
///
/// Implementations should return `signature` if it is valid and return an error if it is not.
/// The default implementation does no checks and just returns `signature` as-is.
///
/// # Security
/// To avoid timing attacks, equality checks should be constant-time; check the docs of your
/// chosen crypto library.
#[allow(unused_variables)]
#[inline]
fn verify(
signature: Self::Signature,
req: &HttpRequest,
) -> Result<Self::Signature, Self::Error> {
Ok(signature)
}
}
/// Wraps an extractor and calculates a request signature hash alongside.
///
/// Warning: Currently, this will always take the body meaning that if a body extractor is used,
/// this needs to wrap it or else it will not work.
#[derive(Clone)]
pub struct RequestSignature<T, S: RequestSignatureScheme> {
extractor: T,
signature: S::Signature,
}
impl<T, S: RequestSignatureScheme> RequestSignature<T, S> {
/// Returns tuple containing body type, and owned hash.
pub fn into_parts(self) -> (T, S::Signature) {
(self.extractor, self.signature)
}
}
/// Errors that can occur when extracting and processing request signatures.
#[derive(Display)]
#[non_exhaustive]
pub enum RequestSignatureError<T, S>
where
T: FromRequest,
T::Error: fmt::Debug + fmt::Display,
S: RequestSignatureScheme,
S::Error: fmt::Debug + fmt::Display,
{
/// Inner extractor error.
#[display(fmt = "Inner extractor error: {_0}")]
Extractor(T::Error),
/// Signature calculation error.
#[display(fmt = "Signature calculation error: {_0}")]
Signature(S::Error),
}
impl<T, S> fmt::Debug for RequestSignatureError<T, S>
where
T: FromRequest,
T::Error: fmt::Debug + fmt::Display,
S: RequestSignatureScheme,
S::Error: fmt::Debug + fmt::Display,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Extractor(err) => f
.debug_tuple("RequestSignatureError::Extractor")
.field(err)
.finish(),
Self::Signature(err) => f
.debug_tuple("RequestSignatureError::Signature")
.field(err)
.finish(),
}
}
}
impl<T, S> From<RequestSignatureError<T, S>> for actix_web::Error
where
T: FromRequest,
T::Error: fmt::Debug + fmt::Display,
S: RequestSignatureScheme,
S::Error: fmt::Debug + fmt::Display,
{
fn from(err: RequestSignatureError<T, S>) -> Self {
match err {
RequestSignatureError::Extractor(err) => err.into(),
RequestSignatureError::Signature(err) => err.into(),
}
}
}
impl<T, S> FromRequest for RequestSignature<T, S>
where
T: FromRequest + 'static,
T::Error: fmt::Debug + fmt::Display,
S: RequestSignatureScheme + 'static,
S::Error: fmt::Debug + fmt::Display,
{
type Error = RequestSignatureError<T, S>;
type Future = LocalBoxFuture<'static, Result<Self, Self::Error>>;
fn from_request(req: &HttpRequest, payload: &mut dev::Payload) -> Self::Future {
let req = req.clone();
let payload = payload.take();
Box::pin(async move {
let (tx, mut rx) = mpsc::channel();
// wrap payload in stream that reads chunks and clones them (cheaply) back here
let proxy_stream: BoxedPayloadStream = Box::pin(payload.inspect(move |res| {
if let Ok(chunk) = res {
trace!("yielding {} byte chunk", chunk.len());
tx.send(chunk.clone()).unwrap();
}
}));
trace!("creating proxy payload");
let mut proxy_payload = dev::Payload::from(proxy_stream);
let body_fut =
T::from_request(&req, &mut proxy_payload).map_err(RequestSignatureError::Extractor);
trace!("initializing signature scheme");
let mut sig_scheme = S::init(&req)
.await
.map_err(RequestSignatureError::Signature)?;
// run update function as chunks are yielded from channel
let hash_fut = actix_web::rt::spawn({
let req = req.clone();
async move {
while let Some(chunk) = rx.recv().await {
trace!("digesting chunk");
sig_scheme.consume_chunk(&req, chunk).await?;
}
trace!("finalizing signature");
sig_scheme.finalize(&req).await
}
})
.map(Result::unwrap)
.map_err(RequestSignatureError::Signature);
trace!("driving both futures");
let (body, signature) = try_join!(body_fut, hash_fut)?;
trace!("verifying signature");
let signature = S::verify(signature, &req).map_err(RequestSignatureError::Signature)?;
let out = Self {
extractor: body,
signature,
};
Ok(out)
})
}
}
#[cfg(test)]
mod tests {
use std::convert::Infallible;
use actix_web::{
http::StatusCode,
test,
web::{self, Bytes},
App,
};
use digest::{CtOutput, Digest as _};
use hex_literal::hex;
use sha2::Sha256;
use super::*;
use crate::extract::Json;
#[derive(Debug, Default)]
struct JustHash(sha2::Sha256);
#[async_trait(?Send)]
impl RequestSignatureScheme for JustHash {
type Signature = CtOutput<sha2::Sha256>;
type Error = Infallible;
async fn init(head: &HttpRequest) -> Result<Self, Self::Error> {
let mut hasher = Sha256::new();
if let Some(path) = head.uri().path_and_query() {
hasher.update(path.as_str().as_bytes())
}
Ok(Self(hasher))
}
async fn consume_chunk(
&mut self,
_req: &HttpRequest,
chunk: Bytes,
) -> Result<(), Self::Error> {
self.0.update(&chunk);
Ok(())
}
async fn finalize(self, _req: &HttpRequest) -> Result<Self::Signature, Self::Error> {
let hash = self.0.finalize();
Ok(CtOutput::new(hash))
}
}
#[actix_web::test]
async fn correctly_hashes_payload() {
let app = test::init_service(App::new().route(
"/service/path",
web::get().to(|body: RequestSignature<Bytes, JustHash>| async move {
let (_, sig) = body.into_parts();
sig.into_bytes().to_vec()
}),
))
.await;
let req = test::TestRequest::with_uri("/service/path").to_request();
let body = test::call_and_read_body(&app, req).await;
assert_eq!(
body,
hex!("a5441a3d ec265f82 3758d164 1188ab1d d1093972 45012a45 fa66df70 32d02177")
.as_ref()
);
let req = test::TestRequest::with_uri("/service/path")
.set_payload("abc")
.to_request();
let body = test::call_and_read_body(&app, req).await;
assert_eq!(
body,
hex!("555290a8 9e75260d fb0afead 2d5d3d70 f058c85d 1ff98bf3 06807301 7ce4c847")
.as_ref()
);
}
#[actix_web::test]
async fn respects_inner_extractor_errors() {
let app = test::init_service(App::new().route(
"/",
web::get().to(
|body: RequestSignature<Json<u64, 4>, JustHash>| async move {
let (_, sig) = body.into_parts();
sig.into_bytes().to_vec()
},
),
))
.await;
let req = test::TestRequest::default().set_json(1234).to_request();
let body = test::call_and_read_body(&app, req).await;
assert_eq!(
body,
hex!("4f373f6c cadfaba3 1a32cf52 04cf3db9 367609ee 6a7d7113 8e4f28ef 7c1a87a9")
.as_ref()
);
// no body would expect a 400 content type error
let req = test::TestRequest::default().to_request();
let body = test::call_service(&app, req).await;
assert_eq!(body.status(), StatusCode::BAD_REQUEST);
// body too big would expect a 413 request payload too large
let req = test::TestRequest::default().set_json(12345).to_request();
let body = test::call_service(&app, req).await;
assert_eq!(body.status(), StatusCode::PAYLOAD_TOO_LARGE);
}
}