Fixes#1327Fixes#1567Closes#2264
Wires the S3 gateway up to the standalone IAM service so identity policies, not just bucket policies and ACLs, are enforced on the S3 data plane. The gateway authenticates SigV4 requests by calling new private derive-signing-key and resolve-identity endpoints on the IAM service instead of holding secrets itself, and evaluates identity policy through the same PolicyEvaluator path added to auth.VerifyAccess, combined with the bucket policy using explicit-deny-wins precedence. The private endpoints are served over their own mTLS listener (new iamapi/private package, genmtlscerts.sh to generate test material, and client-cert support in internal/netutil), separate from the public IAM API. As part of this the vendored aws/signer/v4 package is deleted and replaced by a pure-Go SigV4 implementation in internal/sigv4auth, which now reads canonical request data directly off the fiber.Ctx instead of reconstructing an http.Request, and is shared by both the S3 request-signing verification and the new private-endpoint signing.
DeleteObjects moves from an all-or-nothing authorization check to true partial success: VerifyObjectsAccess evaluates every object in a batch independently against both the identity policy and any object lock, so a denial or a locked object only removes that key from the batch instead of failing the whole request. It also batches the identity-policy round trip and the bucket-policy fetch once per request rather than once per object, and separates plain deletes from versioned ones since a versioned delete needs s3:DeleteObjectVersion rather than s3:DeleteObject. Object lock handling got a few correctness fixes alongside this: a bypass is now modeled as BypassNone/BypassRequested/BypassOverwrite rather than a single bool, because root's blanket ability to override a GOVERNANCE retention should only apply when the client actually asked to bypass it (DeleteObject/DeleteObjects/PutObjectRetention), not when the gateway is silently replacing a locked object via an overwrite, which needs the permission from everyone including root. Retention changes are now correctly classified as an extension (allowed under plain s3:PutObjectRetention) versus a weakening (date or mode change, which needs the bypass permission), and a COMPLIANCE lock can never be weakened by anyone regardless of permissions, matching AWS. Separately, VerifyObjectCopyAccess had a readonly-mode gap: it returned early for root/admin before ever calling VerifyAccess, so the readonly check inside VerifyAccess never ran for them on CopyObject; access checks are now ordered so the readonly gate always applies before any root/admin bypass, for copy as well as every other write path.
Bucket policies also gained Condition block support, via a new shared internal/condition package moved out of the IAM policy package since both bucket and identity policies share the same evaluation semantics. It implements the full AWS operator set — String{Equals,NotEquals,EqualsIgnoreCase,NotEqualsIgnoreCase,Like,NotLike}, Numeric{Equals,NotEquals,LessThan,LessThanEquals,GreaterThan,GreaterThanEquals}, Date{Equals,NotEquals,LessThan,LessThanEquals,GreaterThan,GreaterThanEquals}, Bool, BinaryEquals, Arn{Equals,Like,NotEquals,NotLike}, IpAddress/NotIpAddress, and Null — along with the ForAllValues/ForAnyValue set qualifiers and the IfExists modifier. A new requestConditionContext builds the per-request keys a bucket policy's Condition block can reference — aws:SourceIp, aws:SecureTransport, aws:CurrentTime, aws:EpochTime, aws:UserAgent, aws:Referer, s3:prefix, s3:delimiter, s3:max-keys, s3:x-amz-acl, s3:VersionId — following AWS's own per-action rules for which keys a given S3 operation actually populates. Identity-derived keys such as aws:PrincipalArn and aws:username are deliberately left unwired here, since the gateway has no way to know them; the standalone IAM service fills those in itself when it evaluates an identity policy.
Also added new integration test suites for S3-side IAM: s3_iam_access_control.go and s3_iam_session_access_control.go cover identity-policy enforcement and session-credential requests against real S3 operations, alongside expanded OIDC/web-identity coverage and a new runoidctests.sh runner wired into the OIDC GitHub Actions workflow.
Fixes#2180Fixes#2181
Migrate the gateway from Fiber v2 to Fiber v3.3.0 and update the affected server, middleware, handler, controller, and test code for the new APIs.
Replace the deprecated Fiber filesystem middleware used by the WebUI with the Fiber v3 static middleware, serving the embedded WebUI assets from an fs.Sub filesystem.
Fix the request header limit handling regression by adding a temporary handler for Fiber v3/fasthttp small-buffer errors so oversized request headers return the expected regulated S3 error response.
Fix the debuglogger panic by reworking the boxed key/value formatter used for debug request and response dumps. The formatter now handles long header keys and values without producing invalid wrap widths, negative padding, or out-of-range string slices.
Validate required signed headers for both Authorization-header SigV4 requests and presigned URLs. The required signed header set is now `host` plus every incoming header with the `x-amz-` prefix.
During request reconstruction, signed headers and explicitly ignored headers are copied into the generated request used for signature verification. If an incoming `x-amz-*` header is present but missing from the client-provided `SignedHeaders`, return `AccessDenied` with a `HeadersNotSigned` field. The `host` header remains part of the canonical request and signed header calculation.
Previously, a client could sign a request without an S3 control header and then add that header after signing. For example, a presigned `PUT` URL could be generated with only `host` signed, then the actual request could include an unsigned `X-Amz-Tagging` or `X-Amz-Copy-Source` header. Because the verifier reconstructed the request only from `SignedHeaders`, that extra header was omitted from signature calculation and could pass authentication even though it changed the request semantics. This is now rejected with `AccessDenied`.
Expose v4 helper methods for checking required and ignored headers, and update canonical header signing so ignored headers can still be included when a client explicitly lists them in `SignedHeaders`, while `Authorization` remains excluded from signature calculation.
niksis02