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| author | Alex Auvolat <alex@adnab.me> | 2023-05-18 00:06:03 +0200 |
|---|---|---|
| committer | Alex Auvolat <alex@adnab.me> | 2023-05-18 11:18:06 +0200 |
| commit | 746b0090e4ad02e98b08aa1cfefd77a22d9490fe (patch) | |
| tree | 83b126a76f3d0e5586a6f92b61b1e6c95938a629 /src/api/signature/payload.rs | |
| parent | c26a4308b4454e2f36e2824280b9f587a6918fa9 (diff) | |
| download | garage-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.rs | 40 |
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), "", |