use std::collections::HashMap; use std::convert::TryFrom; use chrono::{DateTime, Duration, NaiveDateTime, TimeZone, Utc}; use hmac::Mac; use hyper::header::{HeaderMap, HeaderName, HeaderValue, AUTHORIZATION, CONTENT_TYPE, HOST}; use hyper::{body::Incoming as IncomingBody, Method, Request}; use sha2::{Digest, Sha256}; use garage_table::*; use garage_util::data::Hash; use garage_model::garage::Garage; use garage_model::key_table::*; use super::LONG_DATETIME; use super::{compute_scope, signing_hmac}; use crate::encoding::uri_encode; use crate::signature::error::*; pub const X_AMZ_ALGORITHM: HeaderName = HeaderName::from_static("x-amz-algorithm"); pub const X_AMZ_CREDENTIAL: HeaderName = HeaderName::from_static("x-amz-credential"); pub const X_AMZ_DATE: HeaderName = HeaderName::from_static("x-amz-date"); pub const X_AMZ_EXPIRES: HeaderName = HeaderName::from_static("x-amz-expires"); pub const X_AMZ_SIGNEDHEADERS: HeaderName = HeaderName::from_static("x-amz-signedheaders"); pub const X_AMZ_SIGNATURE: HeaderName = HeaderName::from_static("x-amz-signature"); pub const X_AMZ_CONTENT_SH256: HeaderName = HeaderName::from_static("x-amz-content-sha256"); pub const AWS4_HMAC_SHA256: &str = "AWS4-HMAC-SHA256"; pub const UNSIGNED_PAYLOAD: &str = "UNSIGNED-PAYLOAD"; pub const STREAMING_AWS4_HMAC_SHA256_PAYLOAD: &str = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD"; pub type QueryMap = HashMap; pub async fn check_payload_signature( garage: &Garage, request: &mut Request, service: &'static str, ) -> Result<(Option, Option), Error> { let query = parse_query_map(request.uri())?; if query.contains_key(X_AMZ_ALGORITHM.as_str()) { // We check for presigned-URL-style authentification first, because // the browser or someting else could inject an Authorization header // that is totally unrelated to AWS signatures. check_presigned_signature(garage, service, request, query).await } else if request.headers().contains_key(AUTHORIZATION) { check_standard_signature(garage, service, request, query).await } else { // Unsigned (anonymous) request let content_sha256 = request .headers() .get("x-amz-content-sha256") .filter(|c| c.as_bytes() != UNSIGNED_PAYLOAD.as_bytes()); if let Some(content_sha256) = content_sha256 { let sha256 = hex::decode(content_sha256) .ok() .and_then(|bytes| Hash::try_from(&bytes)) .ok_or_bad_request("Invalid content sha256 hash")?; Ok((None, Some(sha256))) } else { Ok((None, None)) } } } async fn check_standard_signature( garage: &Garage, service: &'static str, request: &Request, query: QueryMap, ) -> Result<(Option, Option), Error> { let authorization = Authorization::parse_header(request.headers())?; // Verify that all necessary request headers are included in signed_headers // For standard AWSv4 signatures, the following must be included: // - the Host header (mandatory) // - the Content-Type header, if it is used in the request // - all x-amz-* headers used in the request let signed_headers = split_signed_headers(&authorization)?; verify_signed_headers(request.headers(), &signed_headers, &[CONTENT_TYPE])?; let canonical_request = canonical_request( service, request.method(), request.uri().path(), &query, request.headers(), &signed_headers, &authorization.content_sha256, )?; let string_to_sign = string_to_sign( &authorization.date, &authorization.scope, &canonical_request, ); trace!("canonical request:\n{}", canonical_request); trace!("string to sign:\n{}", string_to_sign); let key = verify_v4(garage, service, &authorization, string_to_sign.as_bytes()).await?; let content_sha256 = if authorization.content_sha256 == UNSIGNED_PAYLOAD { None } else if authorization.content_sha256 == STREAMING_AWS4_HMAC_SHA256_PAYLOAD { let bytes = hex::decode(authorization.signature).ok_or_bad_request("Invalid signature")?; Some(Hash::try_from(&bytes).ok_or_bad_request("Invalid signature")?) } else { let bytes = hex::decode(authorization.content_sha256) .ok_or_bad_request("Invalid content sha256 hash")?; Some(Hash::try_from(&bytes).ok_or_bad_request("Invalid content sha256 hash")?) }; Ok((Some(key), content_sha256)) } async fn check_presigned_signature( garage: &Garage, service: &'static str, request: &mut Request, mut query: QueryMap, ) -> Result<(Option, Option), Error> { let algorithm = query.get(X_AMZ_ALGORITHM.as_str()).unwrap(); let authorization = Authorization::parse_presigned(algorithm, &query)?; // Verify that all necessary request headers are included in signed_headers // For AWSv4 pre-signed URLs, the following must be incldued: // - the Host header (mandatory) // - all x-amz-* headers used in the request let signed_headers = split_signed_headers(&authorization)?; verify_signed_headers(request.headers(), &signed_headers, &[])?; // The X-Amz-Signature value is passed as a query parameter, // but the signature cannot be computed from a string that contains itself. // AWS specifies that all query params except X-Amz-Signature are included // in the canonical request. query.remove(X_AMZ_SIGNATURE.as_str()); let canonical_request = canonical_request( service, request.method(), request.uri().path(), &query, request.headers(), &signed_headers, &authorization.content_sha256, )?; let string_to_sign = string_to_sign( &authorization.date, &authorization.scope, &canonical_request, ); trace!("canonical request (presigned url):\n{}", canonical_request); trace!("string to sign (presigned url):\n{}", string_to_sign); let key = verify_v4(garage, service, &authorization, string_to_sign.as_bytes()).await?; // In the page on presigned URLs, AWS specifies that if a signed query // parameter and a signed header of the same name have different values, // then an InvalidRequest error is raised. let headers_mut = request.headers_mut(); for (name, value) in query.iter() { let name = HeaderName::from_bytes(name.as_bytes()).ok_or_bad_request("Invalid header name")?; if let Some(existing) = headers_mut.get(&name) { if signed_headers.contains(&name) && existing.as_bytes() != value.as_bytes() { return Err(Error::bad_request(format!( "Conflicting values for `{}` in query parameters and request headers", name ))); } } if name.as_str().starts_with("x-amz-") { // Query parameters that start by x-amz- are actually intended to stand in for // headers that can't be added at the time the request is made. // What we do is just add them to the Request object as regular headers, // that will be handled downstream as if they were included like in a normal request. // (Here we allow such query parameters to override headers with the same name // that are not signed, however there is not much reason that this would happen) headers_mut.insert( name, HeaderValue::from_bytes(value.as_bytes()) .ok_or_bad_request("invalid query parameter value")?, ); } } // Presigned URLs always use UNSIGNED-PAYLOAD, // so there is no sha256 hash to return. Ok((Some(key), None)) } pub fn parse_query_map(uri: &http::uri::Uri) -> Result { let mut query = QueryMap::new(); if let Some(query_str) = uri.query() { let query_pairs = url::form_urlencoded::parse(query_str.as_bytes()); for (key, val) in query_pairs { if query.insert(key.to_string(), val.into_owned()).is_some() { return Err(Error::bad_request(format!( "duplicate query parameter: `{}`", key ))); } } } Ok(query) } fn parse_credential(cred: &str) -> Result<(String, String), Error> { let first_slash = cred .find('/') .ok_or_bad_request("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 split_signed_headers(authorization: &Authorization) -> Result, Error> { let mut signed_headers = authorization .signed_headers .split(';') .map(HeaderName::try_from) .collect::, _>>() .ok_or_bad_request("invalid header name")?; signed_headers.sort_by(|h1, h2| h1.as_str().cmp(h2.as_str())); Ok(signed_headers) } fn verify_signed_headers( headers: &HeaderMap, signed_headers: &[HeaderName], extra_headers: &[HeaderName], ) -> Result<(), Error> { if !signed_headers.contains(&HOST) { return Err(Error::bad_request("Header `Host` should be signed")); } for (name, _) in headers.iter() { if name.as_str().starts_with("x-amz-") || extra_headers.contains(name) { if !signed_headers.contains(name) { return Err(Error::bad_request(format!( "Header `{}` should be signed", name ))); } } } Ok(()) } pub fn string_to_sign(datetime: &DateTime, scope_string: &str, canonical_req: &str) -> String { let mut hasher = Sha256::default(); hasher.update(canonical_req.as_bytes()); [ AWS4_HMAC_SHA256, &datetime.format(LONG_DATETIME).to_string(), scope_string, &hex::encode(hasher.finalize().as_slice()), ] .join("\n") } pub fn canonical_request( service: &'static str, method: &Method, canonical_uri: &str, query: &QueryMap, headers: &HeaderMap, signed_headers: &[HeaderName], content_sha256: &str, ) -> Result { // There seems to be evidence that in AWSv4 signatures, the path component is url-encoded // a second time when building the canonical request, as specified in this documentation page: // -> https://docs.aws.amazon.com/rolesanywhere/latest/userguide/authentication-sign-process.html // However this documentation page is for a specific service ("roles anywhere"), and // in the S3 service we know for a fact that there is no double-urlencoding, because all of // the tests we made with external software work without it. // // The theory is that double-urlencoding occurs for all services except S3, // which is what is implemented in rusoto_signature: // -> https://docs.rs/rusoto_signature/latest/src/rusoto_signature/signature.rs.html#464 // // Digging into the code of the official AWS Rust SDK, we learn that double-URI-encoding can // be set or unset on a per-request basis (the signature crates, aws-sigv4 and aws-sig-auth, // are agnostic to this). Grepping the codebase confirms that S3 is the only API for which // double_uri_encode is set to false, meaning it is true (its default value) for all other // AWS services. We will therefore implement this behavior in Garage as well. // // Note that this documentation page, which is touted as the "authoritative reference" on // AWSv4 signatures, makes no mention of either single- or double-urlencoding: // -> https://docs.aws.amazon.com/IAM/latest/UserGuide/create-signed-request.html // This page of the S3 documentation does also not mention anything specific: // -> https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-header-based-auth.html // // Note that there is also the issue of path normalization, which I hope is unrelated to the // one of URI-encoding. At least in aws-sigv4 both parameters can be set independently, // and rusoto_signature does not seem to do any effective path normalization, even though // it mentions it in the comments (same link to the souce code as above). // We make the explicit choice of NOT normalizing paths in the K2V API because doing so // would make non-normalized paths invalid K2V partition keys, and we don't want that. let canonical_uri: std::borrow::Cow = if service != "s3" { uri_encode(canonical_uri, false).into() } else { canonical_uri.into() }; // Canonical query string from passed HeaderMap let canonical_query_string = { let mut items = Vec::with_capacity(query.len()); for (key, value) in query.iter() { items.push(uri_encode(&key, true) + "=" + &uri_encode(&value, true)); } items.sort(); items.join("&") }; // Canonical header string calculated from signed headers let canonical_header_string = signed_headers .iter() .map(|name| { let value = headers .get(name) .ok_or_bad_request(format!("signed header `{}` is not present", name))? .to_str()?; Ok(format!("{}:{}", name.as_str(), value.trim())) }) .collect::, Error>>()? .join("\n"); let signed_headers = signed_headers.join(";"); let list = [ method.as_str(), &canonical_uri, &canonical_query_string, &canonical_header_string, "", &signed_headers, content_sha256, ]; Ok(list.join("\n")) } pub fn parse_date(date: &str) -> Result, Error> { let date: NaiveDateTime = NaiveDateTime::parse_from_str(date, LONG_DATETIME).ok_or_bad_request("Invalid date")?; Ok(Utc.from_utc_datetime(&date)) } pub async fn verify_v4( garage: &Garage, service: &str, auth: &Authorization, payload: &[u8], ) -> Result { let scope_expected = compute_scope(&auth.date, &garage.config.s3_api.s3_region, service); if auth.scope != scope_expected { return Err(Error::AuthorizationHeaderMalformed(auth.scope.to_string())); } let key = garage .key_table .get(&EmptyKey, &auth.key_id) .await? .filter(|k| !k.state.is_deleted()) .ok_or_else(|| Error::forbidden(format!("No such key: {}", &auth.key_id)))?; let key_p = key.params().unwrap(); let mut hmac = signing_hmac( &auth.date, &key_p.secret_key, &garage.config.s3_api.s3_region, service, ) .ok_or_internal_error("Unable to build signing HMAC")?; hmac.update(payload); let our_signature = hex::encode(hmac.finalize().into_bytes()); if auth.signature != our_signature { return Err(Error::forbidden("Invalid signature".to_string())); } Ok(key) } // ============ Authorization header, or X-Amz-* query params ========= pub struct Authorization { key_id: String, scope: String, signed_headers: String, signature: String, content_sha256: String, date: DateTime, } impl Authorization { fn parse_header(headers: &HeaderMap) -> Result { let authorization = headers .get(AUTHORIZATION) .ok_or_bad_request("Missing authorization header")? .to_str()?; let (auth_kind, rest) = authorization .split_once(' ') .ok_or_bad_request("Authorization field to short")?; if auth_kind != AWS4_HMAC_SHA256 { return Err(Error::bad_request("Unsupported authorization method")); } 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_bad_request("Field without value in authorization header")?; 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_bad_request("Could not find Credential in Authorization field")?; let signed_headers = auth_params .get("SignedHeaders") .ok_or_bad_request("Could not find SignedHeaders in Authorization field")? .to_string(); let signature = auth_params .get("Signature") .ok_or_bad_request("Could not find Signature in Authorization field")? .to_string(); let content_sha256 = headers .get(X_AMZ_CONTENT_SH256) .ok_or_bad_request("Missing X-Amz-Content-Sha256 field")?; let date = headers .get(X_AMZ_DATE) .ok_or_bad_request("Missing X-Amz-Date field") .map_err(Error::from)? .to_str()?; let date = parse_date(date)?; if Utc::now() - date > Duration::hours(24) { return Err(Error::bad_request("Date is too old".to_string())); } let (key_id, scope) = parse_credential(cred)?; let auth = Authorization { key_id, scope, signed_headers, signature, content_sha256: content_sha256.to_str()?.to_string(), date, }; Ok(auth) } fn parse_presigned(algorithm: &str, query: &QueryMap) -> Result { if algorithm != AWS4_HMAC_SHA256 { return Err(Error::bad_request( "Unsupported authorization method".to_string(), )); } let cred = query .get(X_AMZ_CREDENTIAL.as_str()) .ok_or_bad_request("X-Amz-Credential not found in query parameters")?; let signed_headers = query .get(X_AMZ_SIGNEDHEADERS.as_str()) .ok_or_bad_request("X-Amz-SignedHeaders not found in query parameters")?; let signature = query .get(X_AMZ_SIGNATURE.as_str()) .ok_or_bad_request("X-Amz-Signature not found in query parameters")?; let duration = query .get(X_AMZ_EXPIRES.as_str()) .ok_or_bad_request("X-Amz-Expires not found in query parameters")? .parse() .map_err(|_| Error::bad_request("X-Amz-Expires is not a number".to_string()))?; if duration > 7 * 24 * 3600 { return Err(Error::bad_request( "X-Amz-Expires may not exceed a week".to_string(), )); } let date = query .get(X_AMZ_DATE.as_str()) .ok_or_bad_request("Missing X-Amz-Date field")?; let date = parse_date(date)?; if Utc::now() - date > Duration::seconds(duration) { return Err(Error::bad_request("Date is too old".to_string())); } let (key_id, scope) = parse_credential(cred)?; Ok(Authorization { key_id, scope, signed_headers: signed_headers.to_string(), signature: signature.to_string(), content_sha256: UNSIGNED_PAYLOAD.to_string(), date, }) } pub(crate) fn parse_form(params: &HeaderMap) -> Result { let algorithm = params .get(X_AMZ_ALGORITHM) .ok_or_bad_request("Missing X-Amz-Algorithm header")? .to_str()?; if algorithm != AWS4_HMAC_SHA256 { return Err(Error::bad_request( "Unsupported authorization method".to_string(), )); } let credential = params .get(X_AMZ_CREDENTIAL) .ok_or_else(|| Error::forbidden("Garage does not support anonymous access yet"))? .to_str()?; let signature = params .get(X_AMZ_SIGNATURE) .ok_or_bad_request("No signature was provided")? .to_str()? .to_string(); let date = params .get(X_AMZ_DATE) .ok_or_bad_request("No date was provided")? .to_str()?; let date = parse_date(date)?; if Utc::now() - date > Duration::hours(24) { return Err(Error::bad_request("Date is too old".to_string())); } let (key_id, scope) = parse_credential(credential)?; let auth = Authorization { key_id, scope, signed_headers: "".to_string(), signature, content_sha256: UNSIGNED_PAYLOAD.to_string(), date, }; Ok(auth) } }