1 files changed, 307 insertions, 0 deletions
diff --git a/src/api/signature.rs b/src/api/signature.rs
new file mode 100644
index 00000000..2e82269c
--- /dev/null
+++ b/src/api/signature.rs
@@ -0,0 +1,307 @@
+use std::collections::HashMap;
+
+use chrono::{DateTime, Duration, NaiveDateTime, Utc};
+use hmac::{Hmac, Mac};
+use hyper::{Body, Method, Request};
+use sha2::{Digest, Sha256};
+
+use garage_table::*;
+use garage_util::error::Error;
+
+use garage_core::garage::Garage;
+use garage_core::key_table::*;
+
+const SHORT_DATE: &str = "%Y%m%d";
+const LONG_DATETIME: &str = "%Y%m%dT%H%M%SZ";
+
+type HmacSha256 = Hmac<Sha256>;
+
+pub async fn check_signature(garage: &Garage, request: &Request<Body>) -> Result<Key, Error> {
+	let mut headers = HashMap::new();
+	for (key, val) in request.headers() {
+		headers.insert(key.to_string(), val.to_str()?.to_string());
+	}
+	if let Some(query) = request.uri().query() {
+		let query_pairs = url::form_urlencoded::parse(query.as_bytes());
+		for (key, val) in query_pairs {
+			headers.insert(key.to_lowercase(), val.to_string());
+		}
+	}
+
+	let authorization = if let Some(authorization) = headers.get("authorization") {
+		parse_authorization(authorization, &headers)?
+	} else {
+		parse_query_authorization(&headers)?
+	};
+
+	let date = headers
+		.get("x-amz-date")
+		.ok_or(Error::BadRequest("Missing X-Amz-Date field".into()))?;
+	let date: NaiveDateTime = NaiveDateTime::parse_from_str(date, LONG_DATETIME)
+		.map_err(|e| Error::BadRequest(format!("Invalid date: {}", e)))?
+		.into();
+	let date: DateTime<Utc> = DateTime::from_utc(date, Utc);
+
+	if Utc::now() - date > Duration::hours(24) {
+		return Err(Error::BadRequest(format!("Date is too old")));
+	}
+
+	let scope = format!(
+		"{}/{}/s3/aws4_request",
+		date.format(SHORT_DATE),
+		garage.config.s3_api.s3_region
+	);
+	if authorization.scope != scope {
+		return Err(Error::BadRequest(format!(
+			"Invalid scope in authorization field, expected: {}",
+			scope
+		)));
+	}
+
+	let key = garage
+		.key_table
+		.get(&EmptyKey, &authorization.key_id)
+		.await?
+		.filter(|k| !k.deleted)
+		.ok_or(Error::Forbidden(format!(
+			"No such key: {}",
+			authorization.key_id
+		)))?;
+
+	let canonical_request = canonical_request(
+		request.method(),
+		&request.uri().path().to_string(),
+		&canonical_query_string(&request.uri()),
+		&headers,
+		&authorization.signed_headers,
+		&authorization.content_sha256,
+	);
+	let string_to_sign = string_to_sign(&date, &scope, &canonical_request);
+
+	let mut hmac = signing_hmac(
+		&date,
+		&key.secret_key,
+		&garage.config.s3_api.s3_region,
+		"s3",
+	)
+	.map_err(|e| Error::Message(format!("Unable to build signing HMAC: {}", e)))?;
+	hmac.input(string_to_sign.as_bytes());
+	let signature = hex::encode(hmac.result().code());
+
+	if authorization.signature != signature {
+		return Err(Error::Forbidden(format!("Invalid signature")));
+	}
+
+	Ok(key)
+}
+
+struct Authorization {
+	key_id: String,
+	scope: String,
+	signed_headers: String,
+	signature: String,
+	content_sha256: String,
+}
+
+fn parse_authorization(
+	authorization: &str,
+	headers: &HashMap<String, String>,
+) -> Result<Authorization, Error> {
+	let first_space = authorization
+		.find(' ')
+		.ok_or(Error::BadRequest("Authorization field too short".into()))?;
+	let (auth_kind, rest) = authorization.split_at(first_space);
+
+	if auth_kind != "AWS4-HMAC-SHA256" {
+		return Err(Error::BadRequest("Unsupported authorization method".into()));
+	}
+
+	let mut auth_params = HashMap::new();
+	for auth_part in rest.split(',') {
+		let auth_part = auth_part.trim();
+		let eq = auth_part.find('=').ok_or(Error::BadRequest(format!(
+			"Missing =value in authorization field {}",
+			auth_part
+		)))?;
+		let (key, value) = auth_part.split_at(eq);
+		auth_params.insert(key.to_string(), value.trim_start_matches('=').to_string());
+	}
+
+	let cred = auth_params
+		.get("Credential")
+		.ok_or(Error::BadRequest(format!(
+			"Could not find Credential in Authorization field"
+		)))?;
+	let (key_id, scope) = parse_credential(cred)?;
+
+	let content_sha256 = headers
+		.get("x-amz-content-sha256")
+		.ok_or(Error::BadRequest(
+			"Missing X-Amz-Content-Sha256 field".into(),
+		))?;
+
+	let auth = Authorization {
+		key_id,
+		scope,
+		signed_headers: auth_params
+			.get("SignedHeaders")
+			.ok_or(Error::BadRequest(format!(
+				"Could not find SignedHeaders in Authorization field"
+			)))?
+			.to_string(),
+		signature: auth_params
+			.get("Signature")
+			.ok_or(Error::BadRequest(format!(
+				"Could not find Signature in Authorization field"
+			)))?
+			.to_string(),
+		content_sha256: content_sha256.to_string(),
+	};
+	Ok(auth)
+}
+
+fn parse_query_authorization(headers: &HashMap<String, String>) -> Result<Authorization, Error> {
+	let algo = headers
+		.get("x-amz-algorithm")
+		.ok_or(Error::BadRequest(format!(
+			"X-Amz-Algorithm not found in query parameters"
+		)))?;
+	if algo != "AWS4-HMAC-SHA256" {
+		return Err(Error::BadRequest(format!(
+			"Unsupported authorization method"
+		)));
+	}
+
+	let cred = headers
+		.get("x-amz-credential")
+		.ok_or(Error::BadRequest(format!(
+			"X-Amz-Credential not found in query parameters"
+		)))?;
+	let (key_id, scope) = parse_credential(cred)?;
+	let signed_headers = headers
+		.get("x-amz-signedheaders")
+		.ok_or(Error::BadRequest(format!(
+			"X-Amz-SignedHeaders not found in query parameters"
+		)))?;
+	let signature = headers
+		.get("x-amz-signature")
+		.ok_or(Error::BadRequest(format!(
+			"X-Amz-Signature not found in query parameters"
+		)))?;
+
+	Ok(Authorization {
+		key_id,
+		scope,
+		signed_headers: signed_headers.to_string(),
+		signature: signature.to_string(),
+		content_sha256: "UNSIGNED-PAYLOAD".to_string(),
+	})
+}
+
+fn parse_credential(cred: &str) -> Result<(String, String), Error> {
+	let first_slash = cred.find('/').ok_or(Error::BadRequest(format!(
+		"Credentials does not contain / in authorization field"
+	)))?;
+	let (key_id, scope) = cred.split_at(first_slash);
+	Ok((
+		key_id.to_string(),
+		scope.trim_start_matches('/').to_string(),
+	))
+}
+
+fn string_to_sign(datetime: &DateTime<Utc>, scope_string: &str, canonical_req: &str) -> String {
+	let mut hasher = Sha256::default();
+	hasher.input(canonical_req.as_bytes());
+	[
+		"AWS4-HMAC-SHA256",
+		&datetime.format(LONG_DATETIME).to_string(),
+		scope_string,
+		&hex::encode(hasher.result().as_slice()),
+	]
+	.join("\n")
+}
+
+fn signing_hmac(
+	datetime: &DateTime<Utc>,
+	secret_key: &str,
+	region: &str,
+	service: &str,
+) -> Result<HmacSha256, crypto_mac::InvalidKeyLength> {
+	let secret = String::from("AWS4") + secret_key;
+	let mut date_hmac = HmacSha256::new_varkey(secret.as_bytes())?;
+	date_hmac.input(datetime.format(SHORT_DATE).to_string().as_bytes());
+	let mut region_hmac = HmacSha256::new_varkey(&date_hmac.result().code())?;
+	region_hmac.input(region.as_bytes());
+	let mut service_hmac = HmacSha256::new_varkey(&region_hmac.result().code())?;
+	service_hmac.input(service.as_bytes());
+	let mut signing_hmac = HmacSha256::new_varkey(&service_hmac.result().code())?;
+	signing_hmac.input(b"aws4_request");
+	let hmac = HmacSha256::new_varkey(&signing_hmac.result().code())?;
+	Ok(hmac)
+}
+
+fn canonical_request(
+	method: &Method,
+	url_path: &str,
+	canonical_query_string: &str,
+	headers: &HashMap<String, String>,
+	signed_headers: &str,
+	content_sha256: &str,
+) -> String {
+	[
+		method.as_str(),
+		url_path,
+		canonical_query_string,
+		&canonical_header_string(&headers, signed_headers),
+		"",
+		signed_headers,
+		content_sha256,
+	]
+	.join("\n")
+}
+
+fn canonical_header_string(headers: &HashMap<String, String>, signed_headers: &str) -> String {
+	let signed_headers_vec = signed_headers.split(';').collect::<Vec<_>>();
+	let mut items = headers
+		.iter()
+		.filter(|(key, _)| signed_headers_vec.contains(&key.as_str()))
+		.map(|(key, value)| key.to_lowercase() + ":" + value.trim())
+		.collect::<Vec<_>>();
+	items.sort();
+	items.join("\n")
+}
+
+fn canonical_query_string(uri: &hyper::Uri) -> String {
+	if let Some(query) = uri.query() {
+		let query_pairs = url::form_urlencoded::parse(query.as_bytes());
+		let mut items = query_pairs
+			.filter(|(key, _)| key != "X-Amz-Signature")
+			.map(|(key, value)| uri_encode(&key, true) + "=" + &uri_encode(&value, true))
+			.collect::<Vec<_>>();
+		items.sort();
+		items.join("&")
+	} else {
+		"".to_string()
+	}
+}
+
+fn uri_encode(string: &str, encode_slash: bool) -> String {
+	let mut result = String::with_capacity(string.len() * 2);
+	for c in string.chars() {
+		match c {
+			'a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '-' | '~' | '.' => result.push(c),
+			'/' if encode_slash => result.push_str("%2F"),
+			'/' if !encode_slash => result.push('/'),
+			_ => {
+				result.push('%');
+				result.push_str(
+					&format!("{}", c)
+						.bytes()
+						.map(|b| format!("{:02X}", b))
+						.collect::<String>(),
+				);
+			}
+		}
+	}
+	result
+}