Fission: HTTPTrigger admission omits RelativeURL / Prefix validation; kubectl apply bypasses CLI checks

`HTTPTriggerSpec.Validate()` validated `Methods`, `FunctionReference`, `Host`, `IngressConfig`, and `CorsConfig`, but silently skipped `RelativeURL` and `Prefix`. Those two fields were validated at the CLI level only (`pkg/fission-cli/cmd/httptrigger/create.go:83`). The post-CRD-modernization webhook for HTTPTrigger was retired in favor of API-server CEL — and CEL had no rules on those fields either — so an HTTPTrigger created via `kubectl apply` or a direct Kubernetes REST API call bypassed every URL-level check. A tenant with HTTPTrigger create permission could therefore create triggers whose `RelativeURL` or `Prefix`: - was empty (with both fields unset, the trigger has no URL), - did not start with `/`, - was exactly `/` (claiming the entire router root), - contained `..` traversal segments (e.g. `/api/../admin`), - collided with router-owned routes: `/router-healthz`, `/readyz`, `/_version`, `/auth/login`, - collided with the router-internal function prefix `/fission-function/<ns>/<name>`. ### Affected - Project: `github.com/fission/fission` - Versions: all versions through v1.24.0 - Audited commit: `647c141` - Component: `pkg/apis/core/v1/validation.go:HTTPTriggerSpec.Validate` (and the missing CEL on `HTTPTriggerSpec`) - Configuration: default Fix section (paste into the Fix / Patches field) Fixed in [v1.25.0](https://github.com/fission/fission/releases/tag/v1.25.0) by: - [PR #3464](https://github.com/fission/fission/pull/3464) (commit [`0deed6bf`](https://github.com/fission/fission/commit/0deed6bf2af2a0c0c6094b25e1a0afad36773e3b)) — enforce the path-safety invariants at both admission layers so the API server's CEL evaluation and the Go-side `HTTPTriggerSpec.Validate()` agree: - Three `+kubebuilder:validation:XValidation` rules on `HTTPTriggerSpec` (the API server's CEL admission gate, regenerated into `crds/v1/fission.io_httptriggers.yaml`): - at least one of `relativeurl` or `prefix` must be non-empty; - `relativeurl`, when set, must start with `/`, must not be `/`, must contain no `..` segment, must not be in the reserved exact-path set, and must not start with `/fission-function/`; - `prefix`, when set, the same rules guarded by `has(self.prefix)`. - `validateTriggerPath` helper in `pkg/apis/core/v1/validation.go`, invoked from `HTTPTriggerSpec.Validate()`, mirrors the CEL rules so the CLI's early rejection and the router reconciler's status-Condition path match what the API server admits. Regression coverage: a new `TestHTTPTriggerSpecValidate_Path` table in `pkg/apis/core/v1/validation_validators_test.go` exercises every PoC case from the advisory plus literal `..`-prefixed-segment positives that must remain allowed.