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|
use std::collections::HashMap;
use std::convert::TryFrom;
use chrono::{DateTime, Duration, NaiveDateTime, Utc};
use hmac::Mac;
use hyper::header::{HeaderMap, HeaderName, HeaderValue, AUTHORIZATION, CONTENT_TYPE, HOST};
use hyper::{body::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 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<String, String>;
pub async fn check_payload_signature(
garage: &Garage,
request: &mut Request<Body>,
service: &'static str,
) -> Result<(Option<Key>, Option<Hash>), 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<Body>,
query: QueryMap,
) -> Result<(Option<Key>, Option<Hash>), 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<Body>,
mut query: QueryMap,
) -> Result<(Option<Key>, Option<Hash>), 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<QueryMap, Error> {
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<Vec<HeaderName>, Error> {
let mut signed_headers = authorization
.signed_headers
.split(';')
.map(HeaderName::try_from)
.collect::<Result<Vec<HeaderName>, _>>()
.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<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,
canonical_uri: &str,
query: &QueryMap,
headers: &HeaderMap,
signed_headers: &[HeaderName],
content_sha256: &str,
) -> Result<String, Error> {
// 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<str> = 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::<Result<Vec<String>, 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<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,
auth: &Authorization,
payload: &[u8],
) -> Result<Key, Error> {
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 signature =
hex::decode(&auth.signature).map_err(|_| Error::forbidden("Invalid signature"))?;
if hmac.verify_slice(&signature).is_err() {
return Err(Error::forbidden("Invalid signature"));
}
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<Utc>,
}
impl Authorization {
fn parse_header(headers: &HeaderMap) -> Result<Self, Error> {
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<Self, Error> {
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<Self, Error> {
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)
}
}
|
