use std::collections::HashMap;
use chrono::{DateTime, Duration, NaiveDateTime, Utc};
use hmac::Mac;
use hyper::{Body, 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 async fn check_payload_signature(
garage: &Garage,
service: &'static str,
request: &Request<Body>,
) -> Result<(Option<Key>, Option<Hash>), 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 if let Some(algorithm) = headers.get("x-amz-algorithm") {
parse_query_authorization(algorithm, &headers)?
} else {
let content_sha256 = headers.get("x-amz-content-sha256");
if let Some(content_sha256) = content_sha256.filter(|c| "UNSIGNED-PAYLOAD" != c.as_str()) {
let sha256 = hex::decode(content_sha256)
.ok()
.and_then(|bytes| Hash::try_from(&bytes))
.ok_or_bad_request("Invalid content sha256 hash")?;
return Ok((None, Some(sha256)));
} else {
return Ok((None, None));
}
};
let canonical_request = canonical_request(
service,
request.method(),
request.uri(),
&headers,
&authorization.signed_headers,
&authorization.content_sha256,
);
let (_, scope) = parse_credential(&authorization.credential)?;
let string_to_sign = string_to_sign(&authorization.date, &scope, &canonical_request);
trace!("canonical request:\n{}", canonical_request);
trace!("string to sign:\n{}", string_to_sign);
let key = verify_v4(
garage,
service,
&authorization.credential,
&authorization.date,
&authorization.signature,
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))
}
struct Authorization {
credential: String,
signed_headers: String,
signature: String,
content_sha256: String,
date: DateTime<Utc>,
}
fn parse_authorization(
authorization: &str,
headers: &HashMap<String, String>,
) -> Result<Authorization, Error> {
let first_space = authorization
.find(' ')
.ok_or_bad_request("Authorization field to short")?;
let (auth_kind, rest) = authorization.split_at(first_space);
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 content_sha256 = headers
.get("x-amz-content-sha256")
.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)
.and_then(|d| parse_date(d))?;
if Utc::now() - date > Duration::hours(24) {
return Err(Error::bad_request("Date is too old".to_string()));
}
let auth = Authorization {
credential: cred.to_string(),
signed_headers: auth_params
.get("SignedHeaders")
.ok_or_bad_request("Could not find SignedHeaders in Authorization field")?
.to_string(),
signature: auth_params
.get("Signature")
.ok_or_bad_request("Could not find Signature in Authorization field")?
.to_string(),
content_sha256: content_sha256.to_string(),
date,
};
Ok(auth)
}
fn parse_query_authorization(
algorithm: &str,
headers: &HashMap<String, String>,
) -> Result<Authorization, Error> {
if algorithm != "AWS4-HMAC-SHA256" {
return Err(Error::bad_request(
"Unsupported authorization method".to_string(),
));
}
let cred = headers
.get("x-amz-credential")
.ok_or_bad_request("X-Amz-Credential not found in query parameters")?;
let signed_headers = headers
.get("x-amz-signedheaders")
.ok_or_bad_request("X-Amz-SignedHeaders not found in query parameters")?;
let signature = headers
.get("x-amz-signature")
.ok_or_bad_request("X-Amz-Signature not found in query parameters")?;
let content_sha256 = headers
.get("x-amz-content-sha256")
.map(|x| x.as_str())
.unwrap_or("UNSIGNED-PAYLOAD");
let duration = headers
.get("x-amz-expires")
.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 = headers
.get("x-amz-date")
.ok_or_bad_request("Missing X-Amz-Date field")
.map_err(Error::from)
.and_then(|d| parse_date(d))?;
if Utc::now() - date > Duration::seconds(duration) {
return Err(Error::bad_request("Date is too old".to_string()));
}
Ok(Authorization {
credential: cred.to_string(),
signed_headers: signed_headers.to_string(),
signature: signature.to_string(),
content_sha256: content_sha256.to_string(),
date,
})
}
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(),
))
}
pub fn string_to_sign(datetime: &DateTime<Utc>, 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,
uri: &hyper::Uri,
headers: &HashMap<String, String>,
signed_headers: &str,
content_sha256: &str,
) -> String {
// 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 path: std::borrow::Cow<str> = if service != "s3" {
uri_encode(uri.path(), false).into()
} else {
uri.path().into()
};
[
method.as_str(),
&path,
&canonical_query_string(uri),
&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()))
.collect::<Vec<_>>();
items.sort_by(|(k1, _), (k2, _)| k1.cmp(k2));
items
.iter()
.map(|(key, value)| key.to_lowercase() + ":" + value.trim())
.collect::<Vec<_>>()
.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()
}
}
pub fn parse_date(date: &str) -> Result<DateTime<Utc>, Error> {
let date: NaiveDateTime =
NaiveDateTime::parse_from_str(date, LONG_DATETIME).ok_or_bad_request("Invalid date")?;
Ok(DateTime::from_utc(date, Utc))
}
pub async fn verify_v4(
garage: &Garage,
service: &str,
credential: &str,
date: &DateTime<Utc>,
signature: &str,
payload: &[u8],
) -> Result<Key, Error> {
let (key_id, scope) = parse_credential(credential)?;
let scope_expected = compute_scope(date, &garage.config.s3_api.s3_region, service);
if scope != scope_expected {
return Err(Error::AuthorizationHeaderMalformed(scope.to_string()));
}
let key = garage
.key_table
.get(&EmptyKey, &key_id)
.await?
.filter(|k| !k.state.is_deleted())
.ok_or_else(|| Error::forbidden(format!("No such key: {}", &key_id)))?;
let key_p = key.params().unwrap();
let mut hmac = signing_hmac(
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 signature = hex::decode(&signature).map_err(|_| Error::forbidden("Invalid signature"))?;
if hmac.verify_slice(&signature).is_err() {
return Err(Error::forbidden("Invalid signature"));
}
Ok(key)
}
