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authorAlex Auvolat <alex@adnab.me>2023-05-18 00:06:03 +0200
committerAlex Auvolat <alex@adnab.me>2023-05-18 11:18:06 +0200
commit746b0090e4ad02e98b08aa1cfefd77a22d9490fe (patch)
tree83b126a76f3d0e5586a6f92b61b1e6c95938a629 /src/api/signature/payload.rs
parentc26a4308b4454e2f36e2824280b9f587a6918fa9 (diff)
downloadgarage-746b0090e4ad02e98b08aa1cfefd77a22d9490fe.tar.gz
garage-746b0090e4ad02e98b08aa1cfefd77a22d9490fe.zip
k2v signature verification: double urlencoding (see comment in source code)
Diffstat (limited to 'src/api/signature/payload.rs')
-rw-r--r--src/api/signature/payload.rs40
1 files changed, 38 insertions, 2 deletions
diff --git a/src/api/signature/payload.rs b/src/api/signature/payload.rs
index 4c7934e5..c945ab11 100644
--- a/src/api/signature/payload.rs
+++ b/src/api/signature/payload.rs
@@ -19,7 +19,7 @@ use crate::signature::error::*;
pub async fn check_payload_signature(
garage: &Garage,
- service: &str,
+ service: &'static str,
request: &Request<Body>,
) -> Result<(Option<Key>, Option<Hash>), Error> {
let mut headers = HashMap::new();
@@ -51,6 +51,7 @@ pub async fn check_payload_signature(
};
let canonical_request = canonical_request(
+ service,
request.method(),
request.uri(),
&headers,
@@ -231,15 +232,50 @@ pub fn string_to_sign(datetime: &DateTime<Utc>, scope_string: &str, canonical_re
}
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(),
- uri.path(),
+ &path,
&canonical_query_string(uri),
&canonical_header_string(headers, signed_headers),
"",