docs: update security advisory lessons (#5896)

.agents/skills/security-advisory-lessons/SKILL.md

@@ -66,14 +66,23 @@ For the full pattern map, read [advisory-patterns.md](references/advisory-patter
 
 ### STS, OIDC, and federation flows
 - Every STS endpoint must have an explicit authentication story: SigV4 where required, OIDC token verification for web identity, and role/session policy validation before issuing credentials.
+- For web identity, the JWT is the credential; exemption from SigV4 is not itself an authentication bypass. Treat pre-verification claims only as untrusted routing hints, bound token size, normalize public failures, rate-limit discovery, and issue credentials only after signature, issuer, audience, and expiration checks.
 - JWT session tokens must be signed and verified by a trusted issuer/key path, not by service-account-controlled material or a reused root secret.
 - JWT verification must enforce required claims and expiration for every bearer token path; "allow missing exp" is never acceptable for user-presented credentials.
 - Public OIDC bootstrap and callback routes must treat `Host`, `X-Forwarded-Proto`, redirect targets, `state`, and callback parameters as untrusted; credential-bearing redirects require a configured, allowlisted origin.
 - OIDC discovery and validation URLs are SSRF sinks. Resolve and classify hostnames at connection time, reject rebinding to loopback/private/link-local ranges, and do not rely on literal string checks.
 
-### S3 copy, multipart, and presigned POST
+### IAM policy conditions and plugins
+- Treat request headers as attacker-controlled even after SigV4; callers sign their own spoofed headers. Do not merge them into server-derived condition keys such as identity, groups, version ID, signature version, JWT, or LDAP claims.
+- Keep the condition-key namespace explicit. Reserved server-derived keys must reject or ignore colliding headers, while intentional request-header keys such as `s3:x-amz-*` remain available.
+- Quantified IAM condition tests need partially overlapping multi-value sets. Fully contained and fully disjoint sets cannot distinguish `ForAllValues` from `ForAnyValue` bugs.
+- External policy plugins must receive the same security context as built-in policy evaluation. If OPA or another plugin depends on existing object tags, load and pass `ExistingObjectTag/*` before the plugin decision.
+
+### S3 object actions, copy, multipart, and presigned POST
+- Version-aware object requests need version-aware actions. Explicit `versionId` reads and copy sources must authorize `s3:GetObjectVersion`, not only `s3:GetObject`.
 - Multipart copy must enforce source `GetObject` and destination `PutObject` semantics equivalent to `CopyObject`, including copy-source and policy conditions.
 - Do not let `CreateMultipartUpload`, `UploadPartCopy`, `CompleteMultipartUpload`, or `AbortMultipartUpload` return success without authorization.
+- Fallbacks from version actions to non-version actions must still pass the same public-access-block, anonymous-deny, and post-authorization gates as a direct allow.
 - Presigned POST policies are server-side contracts. Enforce `content-length-range`, key prefix, exact metadata/content-type, and all signed policy conditions.
 
 ### Protocol frontends and IAM parity
@@ -132,6 +141,11 @@ For the full pattern map, read [advisory-patterns.md](references/advisory-patter
 - When touching reader/writer wrappers such as hashing, encryption, compression, or warp readers, verify wrapper order and inspect stored bytes in regression tests.
 - Avoid helper shortcuts that unwrap nested readers and accidentally bypass encryption or integrity layers.
 
+### Object Lock and retention invariants
+- Object Lock state must fail closed when bucket metadata is unreadable, fabricated, or unparsable. Only a confirmed absence of Object Lock configuration may permit unprotected deletes or writes.
+- Do not collapse metadata read faults, missing persisted metadata, parse failures, and genuinely absent Object Lock config into one "not configured" result.
+- Retention enforcement must cover foreground deletes, batch deletes, force-delete helpers, default-retention materialization on PUT, lifecycle expiry, scanner sweeps, and all-versions expiry.
+
 ## Review Prompts
 
 Use these prompts while reviewing a diff:
@@ -148,5 +162,9 @@ Use these prompts while reviewing a diff:
 - Does this outbound validation path resolve attacker-supplied hostnames and reject private, loopback, link-local, and rebound addresses at the actual connection boundary?
 - Is an archive entry, object key, or policy resource normalized differently between authorization and storage?
 - Is the same operation implemented in multiple paths, such as `CopyObject` vs `UploadPartCopy`, and do all paths enforce the same security contract?
+- Does an explicit object version, fallback action, or plugin authorization path pass through the same action and post-authorization gates as the direct S3 path?
+- Can a caller-controlled header populate a condition key that should be derived only by the server?
+- Do condition tests include partially overlapping multi-value inputs for quantified operators?
+- Does unreadable bucket metadata make Object Lock or retention enforcement fail closed rather than disappear?
 - Does a preview or browser-surface fix preserve the original security invariant when adding alternate viewers or file-type detection?
 - Does the test prove the exploit form is denied, or only that the intended form still works?

.agents/skills/security-advisory-lessons/references/advisory-patterns.md

@@ -35,12 +35,21 @@ Update this file only when an advisory adds or changes a reusable lesson, affect
 ### STS, OIDC, and federation flows
 
 - `GHSA-5qfg-mf7r-jp3w` and `GHSA-3473-5353-xhwh`: `AssumeRoleWithWebIdentity` was reachable through unauthenticated `POST /` routing and could issue temporary credentials from crafted web identity input. Lesson: every STS route needs explicit SigV4 or trusted identity-provider validation before role assumption, and unauthenticated exemptions must be narrowed to the exact action with uniform failure responses.
-- `GHSA-ccrv-v8v9-ch9q` and `GHSA-48rf-7j3q-3hfv`: service-account-controlled material could self-sign JWT session tokens with forged policy claims, and missing `exp` was accepted for service-account tokens. Lesson: session tokens must be signed by a trusted issuer/key path, enforce required claims and expiration, and reject self-signed or principal-controlled tokens.
+- `GHSA-jxrr-r6pv-h958`: unsigned JWT issuer data was decoded before verification to select an OIDC provider, and distinguishable failures could expose provider configuration. Lesson: web-identity routing may be unauthenticated, but pre-verification claims are untrusted routing hints; bound and rate-limit the request, normalize public errors, and verify signature, issuer, audience, and expiration before issuing credentials.
+- `GHSA-ccrv-v8v9-ch9q`, `GHSA-48rf-7j3q-3hfv`, and `GHSA-xvfh-7c9g-hpw2`: service-account-controlled material could self-sign JWT session tokens with forged policy claims, and missing `exp` was accepted for service-account tokens. Lesson: session tokens must be signed by a trusted issuer/key path, enforce required claims and expiration, and reject self-signed or principal-controlled tokens.
 - `GHSA-9pjf-w3c2-m32r`, `GHSA-4x2q-cpx9-9h26`, and `GHSA-xvpm-p3f7-34c3`: public OIDC authorize/callback flows trusted request `Host` or forwarded scheme when building credential-bearing redirects. Lesson: OIDC redirects must use configured allowlisted origins and trusted-proxy handling; never derive the post-login credential destination from direct client headers.
 - `GHSA-m479-9x88-94w6`, `GHSA-frwq-mfqx-83p8`, `GHSA-q9q8-rf9r-fg9f`, and `GHSA-j5c2-hhf7-6gf5`: OIDC validation accepted attacker-controlled discovery URLs because hostname checks rejected only literal forbidden IPs, allowing DNS rebinding SSRF. Lesson: outbound federation URL validation must resolve and classify hostnames at the connection boundary and reject loopback, private, link-local, and rebound addresses.
 
-### S3 copy, multipart, and upload policy validation
+### IAM policy conditions and external policy plugins
 
+- `GHSA-6r96-hmgc-726c`: request headers collided with lowercase server-derived condition keys such as `userid`, `groups`, `versionid`, and JWT/LDAP claims. Lesson: never let caller-controlled headers append to or replace server-derived policy context; reserve trusted condition keys and keep intentional request-header keys separate.
+- `GHSA-v9cp-qfw9-9pfp`: quantified negated string conditions applied negation after aggregation, transposing `ForAllValues` and `ForAnyValue` semantics. Lesson: push negation into the per-value predicate for quantified operators and test partially overlapping multi-value sets.
+- `GHSA-5w8r-p896-6vq2`: OPA policy mode skipped `ExistingObjectTag/*` loading, so tagged objects looked untagged to external policies. Lesson: external authorization plugins need the same object-tag and request context as built-in policy evaluation before they decide.
+
+### S3 object actions, copy, multipart, and upload policy validation
+
+- `GHSA-3ppv-fx5m-m749`: explicit `versionId` reads and copy sources authorized `s3:GetObject` instead of `s3:GetObjectVersion`. Lesson: version-specific object access must select version-specific actions for direct reads, `CopyObject`, and `UploadPartCopy`, with tests proving the backend is not reached on denial.
+- `GHSA-x298-9x87-fvjq`: anonymous `ListObjectVersions` fell back to `ListBucket` and returned before public-access-block gates. Lesson: compatibility fallbacks must converge on the same post-authorization checks as direct grants, especially `RestrictPublicBuckets` and anonymous data-plane denies.
 - `GHSA-mx42-j6wv-px98`: `UploadPartCopy` missed source authorization and allowed cross-bucket object exfiltration. Lesson: multipart copy must enforce the same source and destination contract as `CopyObject`.
 - `GHSA-wfxj-ph3v-7mjf`: `UploadPartCopy` checked source and destination independently but missed destination copy-source policy constraints. Lesson: source read and destination write checks are not sufficient when policy constrains allowed copy sources.
 - `GHSA-w5fh-f8xh-5x3p`: presigned POST accepted uploads without enforcing signed policy conditions. Lesson: parse and enforce all POST policy constraints server-side, including size, key prefix, and content type.
@@ -59,7 +68,7 @@ Update this file only when an advisory adds or changes a reusable lesson, affect
 
 ### Secrets, defaults, and cryptographic misuse
 
-- `GHSA-j59h-h7q5-q348`, `GHSA-3wm5-wpm5-hmfm`, `GHSA-6wc8-xm48-qhmx`, `GHSA-9gf3-jx4p-4xxf`, and `GHSA-63xc-c3w3-m2cf`: RustFS shipped known default root credentials that could authenticate to S3, admin APIs, IAM, KMS, console, and token-signing surfaces. Lesson: root credentials must be operator-provided or generated per install; known defaults and warnings are not acceptable for network-reachable deployments.
+- `GHSA-j59h-h7q5-q348`, `GHSA-3wm5-wpm5-hmfm`, `GHSA-6wc8-xm48-qhmx`, `GHSA-9gf3-jx4p-4xxf`, `GHSA-63xc-c3w3-m2cf`, and `GHSA-ch63-6q4v-hwp5`: RustFS shipped known default root credentials that could authenticate to S3, admin APIs, IAM, KMS, console, and token-signing surfaces. Lesson: root credentials must be operator-provided or generated per install; known defaults and warnings are not acceptable for network-reachable deployments.
 - `GHSA-h956-rh7x-ppgj`: gRPC used the hard-coded token `rustfs rpc` on both client and server. Lesson: source-visible shared tokens are authentication bypasses.
 - `GHSA-r5qv-rc46-hv8q`: internode RPC HMAC secret fell back to the public default `rustfsadmin`. Lesson: RPC/internode auth must fail closed instead of silently using public defaults.
 - `GHSA-75fx-qg6f-8rm7` and `GHSA-68cw-96m3-h2cf`: internode RPC secrets were derivable from known root credentials, making raw storage RPC signatures forgeable when explicit RPC secrets were unset. Lesson: RPC auth keys must be independent random secrets, never derived from S3 root credentials, and raw storage RPC should not share the public S3 listener without an internode-only boundary.
@@ -92,6 +101,10 @@ Update this file only when an advisory adds or changes a reusable lesson, affect
 
 - `GHSA-xrrf-67jm-3c2r`: SSE metadata reported encryption while reader composition bypassed `EncryptReader` and stored plaintext. Lesson: test actual bytes on disk and wrapper order, not only API metadata.
 
+### Object Lock and retention invariants
+
+- `GHSA-j548-9grx-fh4f`: Object Lock enforcement treated unreadable, fabricated, or unparsable bucket metadata as absent configuration and allowed retained objects to be deleted or expired. Lesson: retention must fail closed unless Object Lock absence is authoritative, and every delete, lifecycle, scanner, force-delete, and default-retention path needs the same state distinction.
+
 ### Serde deserialization and input validation
 
 - No `#[serde(deny_unknown_fields)]` found across the entire codebase. Lesson: all structs deserialized from untrusted input (S3 API XML/JSON, lifecycle rules, bucket policies, replication configs) should have `#[serde(deny_unknown_fields)]` to reject malformed or adversarial payloads.
@@ -107,11 +120,13 @@ Use these targeted searches when a diff touches security-sensitive code:
 rg -n "validate_admin_request|check_permissions|AdminAction::|deny_only|is_allowed" rustfs crates
 rg -n "authorize_operation|FtpsDriver|SftpDriver|RETR|MKD|SIZE|MDTM|CreateBucket|GetObject|HeadObject" crates/protocols rustfs
 rg -n "UploadPartCopy|upload_part_copy|CompleteMultipart|PostObject|content-length-range|starts-with" rustfs crates
+rg -n "ListBucketVersions|GetObjectVersion|versionId|VersionId|ExistingObjectTag|ForAllValues|ForAnyValue|POLICY_PLUGIN|opa" rustfs crates
 rg -n "normalize_extract_entry_key|Snowball|auto-extract|PathBuf::join|canonicalize|\\.\\.|x-forwarded-for|x-real-ip|SourceIp" rustfs crates
 rg -n "DEFAULT_SECRET|DEFAULT_ACCESS|TEST_PRIVATE_KEY|rustfs rpc|RUSTFS_RPC_SECRET" rustfs crates
 rg -n "TONIC_RPC_PREFIX|verify_rpc_signature|check_auth|NodeServiceServer|x-rustfs-signature" rustfs crates
 rg -n "debug!|trace!|info!|error!|\\?resp|\\?merged_config|session_token|secret_key" rustfs crates
 rg -n "HashReader|EncryptReader|SSE|server-side encryption|Access-Control-Allow-Credentials|Origin" rustfs crates
+rg -n "ObjectLock|object_lock|retention|COMPLIANCE|GOVERNANCE|delete_prefix|lifecycle|scanner" rustfs crates
 rg -n "deny_unknown_fields|serde.default|as u32|as usize|as i32" rustfs crates
 ```
 
@@ -121,9 +136,12 @@ rg -n "deny_unknown_fields|serde.default|as u32|as usize|as i32" rustfs crates
 - Protocol frontend authz fixes: include denied `RETR`, `SIZE`/`MDTM`, `MKD`, bucket probe, and sibling allowed-operation cases, and assert denied paths do not reach the storage backend.
 - IAM fixes: include import/update/list service-account cases with attacker-controlled parent, claims, access key, secret key, and policy.
 - Copy/upload fixes: include cross-bucket, cross-user, source-denied, destination-denied, copy-source-condition, and multipart completion cases.
+- Version-action fixes: include historical UUID, explicit current version, `null`, range, partNumber, presigned, STS/session, service-account, anonymous bucket-policy, copy source, and multipart-copy source cases.
+- Policy-condition fixes: include reserved-key header collisions, missing keys, partially overlapping multi-value sets, plugin mode, and built-in policy mode.
 - Path fixes: include encoded traversal, absolute path, nested traversal, archive entries with `..`, valid object keys that resemble traversal text but should be rejected, and canonical bucket/prefix boundary checks.
 - Logging fixes: assert redacted output for structs and response bodies that may contain credentials.
 - IAM export fixes: assert exported archives omit plaintext user and service-account secrets unless the format deliberately encrypts or seals them.
 - RPC auth fixes: include captured metadata replay across two concrete methods, stale timestamps, wrong path, wrong method surrogate, wrong secret, and valid same-method calls.
 - Browser/CORS fixes: assert no credentials on reflected/default origins, correct behavior for explicit allowlists, and no same-origin script execution for previewed object content.
 - SSE fixes: inspect stored bytes and verify API metadata, read-back behavior, and on-disk ciphertext together.
+- Object Lock fixes: include unreadable metadata, fabricated metadata defaults, unparsable config, confirmed absent config, COMPLIANCE/GOVERNANCE retention, lifecycle expiry, scanner sweeps, and force-delete paths.