rbd: add aws-sts-metdata encryption type

With Amazon STS and kubernetes cluster is configured with
OIDC identity provider, credentials to access Amazon KMS
can be fetched using oidc-token(serviceaccount token).
Each tenant/namespace needs to create a secret with aws region,
role and CMK ARN.
Ceph-CSI will assume the given role with oidc token and access
aws KMS, with given CMK to encrypt/decrypt DEK which will stored
in the image metdata.

Refer: https://docs.aws.amazon.com/STS/latest/APIReference/welcome.html
Resolves: #2879

Signed-off-by: Rakshith R <rar@redhat.com>

vendor/github.com/aws/smithy-go/middleware/step_build.go

@@ -0,0 +1,211 @@
+package middleware
+
+import (
+	"context"
+)
+
+// BuildInput provides the input parameters for the BuildMiddleware to consume.
+// BuildMiddleware may modify the Request value before forwarding the input
+// along to the next BuildHandler.
+type BuildInput struct {
+	Request interface{}
+}
+
+// BuildOutput provides the result returned by the next BuildHandler.
+type BuildOutput struct {
+	Result interface{}
+}
+
+// BuildHandler provides the interface for the next handler the
+// BuildMiddleware will call in the middleware chain.
+type BuildHandler interface {
+	HandleBuild(ctx context.Context, in BuildInput) (
+		out BuildOutput, metadata Metadata, err error,
+	)
+}
+
+// BuildMiddleware provides the interface for middleware specific to the
+// serialize step. Delegates to the next BuildHandler for further
+// processing.
+type BuildMiddleware interface {
+	// Unique ID for the middleware in theBuildStep. The step does not allow
+	// duplicate IDs.
+	ID() string
+
+	// Invokes the middleware behavior which must delegate to the next handler
+	// for the middleware chain to continue. The method must return a result or
+	// error to its caller.
+	HandleBuild(ctx context.Context, in BuildInput, next BuildHandler) (
+		out BuildOutput, metadata Metadata, err error,
+	)
+}
+
+// BuildMiddlewareFunc returns a BuildMiddleware with the unique ID provided,
+// and the func to be invoked.
+func BuildMiddlewareFunc(id string, fn func(context.Context, BuildInput, BuildHandler) (BuildOutput, Metadata, error)) BuildMiddleware {
+	return buildMiddlewareFunc{
+		id: id,
+		fn: fn,
+	}
+}
+
+type buildMiddlewareFunc struct {
+	// Unique ID for the middleware.
+	id string
+
+	// Middleware function to be called.
+	fn func(context.Context, BuildInput, BuildHandler) (BuildOutput, Metadata, error)
+}
+
+// ID returns the unique ID for the middleware.
+func (s buildMiddlewareFunc) ID() string { return s.id }
+
+// HandleBuild invokes the middleware Fn.
+func (s buildMiddlewareFunc) HandleBuild(ctx context.Context, in BuildInput, next BuildHandler) (
+	out BuildOutput, metadata Metadata, err error,
+) {
+	return s.fn(ctx, in, next)
+}
+
+var _ BuildMiddleware = (buildMiddlewareFunc{})
+
+// BuildStep provides the ordered grouping of BuildMiddleware to be invoked on
+// a handler.
+type BuildStep struct {
+	ids *orderedIDs
+}
+
+// NewBuildStep returns a BuildStep ready to have middleware for
+// initialization added to it.
+func NewBuildStep() *BuildStep {
+	return &BuildStep{
+		ids: newOrderedIDs(),
+	}
+}
+
+var _ Middleware = (*BuildStep)(nil)
+
+// ID returns the unique name of the step as a middleware.
+func (s *BuildStep) ID() string {
+	return "Build stack step"
+}
+
+// HandleMiddleware invokes the middleware by decorating the next handler
+// provided. Returns the result of the middleware and handler being invoked.
+//
+// Implements Middleware interface.
+func (s *BuildStep) HandleMiddleware(ctx context.Context, in interface{}, next Handler) (
+	out interface{}, metadata Metadata, err error,
+) {
+	order := s.ids.GetOrder()
+
+	var h BuildHandler = buildWrapHandler{Next: next}
+	for i := len(order) - 1; i >= 0; i-- {
+		h = decoratedBuildHandler{
+			Next: h,
+			With: order[i].(BuildMiddleware),
+		}
+	}
+
+	sIn := BuildInput{
+		Request: in,
+	}
+
+	res, metadata, err := h.HandleBuild(ctx, sIn)
+	return res.Result, metadata, err
+}
+
+// Get retrieves the middleware identified by id. If the middleware is not present, returns false.
+func (s *BuildStep) Get(id string) (BuildMiddleware, bool) {
+	get, ok := s.ids.Get(id)
+	if !ok {
+		return nil, false
+	}
+	return get.(BuildMiddleware), ok
+}
+
+// Add injects the middleware to the relative position of the middleware group.
+// Returns an error if the middleware already exists.
+func (s *BuildStep) Add(m BuildMiddleware, pos RelativePosition) error {
+	return s.ids.Add(m, pos)
+}
+
+// Insert injects the middleware relative to an existing middleware id.
+// Returns an error if the original middleware does not exist, or the middleware
+// being added already exists.
+func (s *BuildStep) Insert(m BuildMiddleware, relativeTo string, pos RelativePosition) error {
+	return s.ids.Insert(m, relativeTo, pos)
+}
+
+// Swap removes the middleware by id, replacing it with the new middleware.
+// Returns the middleware removed, or an error if the middleware to be removed
+// doesn't exist.
+func (s *BuildStep) Swap(id string, m BuildMiddleware) (BuildMiddleware, error) {
+	removed, err := s.ids.Swap(id, m)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(BuildMiddleware), nil
+}
+
+// Remove removes the middleware by id. Returns error if the middleware
+// doesn't exist.
+func (s *BuildStep) Remove(id string) (BuildMiddleware, error) {
+	removed, err := s.ids.Remove(id)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(BuildMiddleware), nil
+}
+
+// List returns a list of the middleware in the step.
+func (s *BuildStep) List() []string {
+	return s.ids.List()
+}
+
+// Clear removes all middleware in the step.
+func (s *BuildStep) Clear() {
+	s.ids.Clear()
+}
+
+type buildWrapHandler struct {
+	Next Handler
+}
+
+var _ BuildHandler = (*buildWrapHandler)(nil)
+
+// Implements BuildHandler, converts types and delegates to underlying
+// generic handler.
+func (w buildWrapHandler) HandleBuild(ctx context.Context, in BuildInput) (
+	out BuildOutput, metadata Metadata, err error,
+) {
+	res, metadata, err := w.Next.Handle(ctx, in.Request)
+	return BuildOutput{
+		Result: res,
+	}, metadata, err
+}
+
+type decoratedBuildHandler struct {
+	Next BuildHandler
+	With BuildMiddleware
+}
+
+var _ BuildHandler = (*decoratedBuildHandler)(nil)
+
+func (h decoratedBuildHandler) HandleBuild(ctx context.Context, in BuildInput) (
+	out BuildOutput, metadata Metadata, err error,
+) {
+	return h.With.HandleBuild(ctx, in, h.Next)
+}
+
+// BuildHandlerFunc provides a wrapper around a function to be used as a build middleware handler.
+type BuildHandlerFunc func(context.Context, BuildInput) (BuildOutput, Metadata, error)
+
+// HandleBuild invokes the wrapped function with the provided arguments.
+func (b BuildHandlerFunc) HandleBuild(ctx context.Context, in BuildInput) (BuildOutput, Metadata, error) {
+	return b(ctx, in)
+}
+
+var _ BuildHandler = BuildHandlerFunc(nil)