// Copyright 2016 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package iam supports the resource-specific operations of Google Cloud
// IAM (Identity and Access Management) for the Google Cloud Libraries.
// See https://cloud.google.com/iam for more about IAM.
//
// Users of the Google Cloud Libraries will typically not use this package
// directly. Instead they will begin with some resource that supports IAM, like
// a pubsub topic, and call its IAM method to get a Handle for that resource.
package iam
import (
"context"
"fmt"
"time"
gax "github.com/googleapis/gax-go/v2"
pb "google.golang.org/genproto/googleapis/iam/v1"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/metadata"
)
// client abstracts the IAMPolicy API to allow multiple implementations.
type client interface {
Get(ctx context.Context, resource string) (*pb.Policy, error)
Set(ctx context.Context, resource string, p *pb.Policy) error
Test(ctx context.Context, resource string, perms []string) ([]string, error)
}
// grpcClient implements client for the standard gRPC-based IAMPolicy service.
type grpcClient struct {
c pb.IAMPolicyClient
}
var withRetry = gax.WithRetry(func() gax.Retryer {
return gax.OnCodes([]codes.Code{
codes.DeadlineExceeded,
codes.Unavailable,
}, gax.Backoff{
Initial: 100 * time.Millisecond,
Max: 60 * time.Second,
Multiplier: 1.3,
})
})
func (g *grpcClient) Get(ctx context.Context, resource string) (*pb.Policy, error) {
var proto *pb.Policy
md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "resource", resource))
ctx = insertMetadata(ctx, md)
err := gax.Invoke(ctx, func(ctx context.Context, _ gax.CallSettings) error {
var err error
proto, err = g.c.GetIamPolicy(ctx, &pb.GetIamPolicyRequest{Resource: resource})
return err
}, withRetry)
if err != nil {
return nil, err
}
return proto, nil
}
func (g *grpcClient) Set(ctx context.Context, resource string, p *pb.Policy) error {
md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "resource", resource))
ctx = insertMetadata(ctx, md)
return gax.Invoke(ctx, func(ctx context.Context, _ gax.CallSettings) error {
_, err := g.c.SetIamPolicy(ctx, &pb.SetIamPolicyRequest{
Resource: resource,
Policy: p,
})
return err
}, withRetry)
}
func (g *grpcClient) Test(ctx context.Context, resource string, perms []string) ([]string, error) {
var res *pb.TestIamPermissionsResponse
md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "resource", resource))
ctx = insertMetadata(ctx, md)
err := gax.Invoke(ctx, func(ctx context.Context, _ gax.CallSettings) error {
var err error
res, err = g.c.TestIamPermissions(ctx, &pb.TestIamPermissionsRequest{
Resource: resource,
Permissions: perms,
})
return err
}, withRetry)
if err != nil {
return nil, err
}
return res.Permissions, nil
}
// A Handle provides IAM operations for a resource.
type Handle struct {
c client
resource string
}
// InternalNewHandle is for use by the Google Cloud Libraries only.
//
// InternalNewHandle returns a Handle for resource.
// The conn parameter refers to a server that must support the IAMPolicy service.
func InternalNewHandle(conn *grpc.ClientConn, resource string) *Handle {
return InternalNewHandleGRPCClient(pb.NewIAMPolicyClient(conn), resource)
}
// InternalNewHandleGRPCClient is for use by the Google Cloud Libraries only.
//
// InternalNewHandleClient returns a Handle for resource using the given
// grpc service that implements IAM as a mixin
func InternalNewHandleGRPCClient(c pb.IAMPolicyClient, resource string) *Handle {
return InternalNewHandleClient(&grpcClient{c: c}, resource)
}
// InternalNewHandleClient is for use by the Google Cloud Libraries only.
//
// InternalNewHandleClient returns a Handle for resource using the given
// client implementation.
func InternalNewHandleClient(c client, resource string) *Handle {
return &Handle{
c: c,
resource: resource,
}
}
// Policy retrieves the IAM policy for the resource.
func (h *Handle) Policy(ctx context.Context) (*Policy, error) {
proto, err := h.c.Get(ctx, h.resource)
if err != nil {
return nil, err
}
return &Policy{InternalProto: proto}, nil
}
// SetPolicy replaces the resource's current policy with the supplied Policy.
//
// If policy was created from a prior call to Get, then the modification will
// only succeed if the policy has not changed since the Get.
func (h *Handle) SetPolicy(ctx context.Context, policy *Policy) error {
return h.c.Set(ctx, h.resource, policy.InternalProto)
}
// TestPermissions returns the subset of permissions that the caller has on the resource.
func (h *Handle) TestPermissions(ctx context.Context, permissions []string) ([]string, error) {
return h.c.Test(ctx, h.resource, permissions)
}
// A RoleName is a name representing a collection of permissions.
type RoleName string
// Common role names.
const (
Owner RoleName = "roles/owner"
Editor RoleName = "roles/editor"
Viewer RoleName = "roles/viewer"
)
const (
// AllUsers is a special member that denotes all users, even unauthenticated ones.
AllUsers = "allUsers"
// AllAuthenticatedUsers is a special member that denotes all authenticated users.
AllAuthenticatedUsers = "allAuthenticatedUsers"
)
// A Policy is a list of Bindings representing roles
// granted to members.
//
// The zero Policy is a valid policy with no bindings.
type Policy struct {
// TODO(jba): when type aliases are available, put Policy into an internal package
// and provide an exported alias here.
// This field is exported for use by the Google Cloud Libraries only.
// It may become unexported in a future release.
InternalProto *pb.Policy
}
// Members returns the list of members with the supplied role.
// The return value should not be modified. Use Add and Remove
// to modify the members of a role.
func (p *Policy) Members(r RoleName) []string {
b := p.binding(r)
if b == nil {
return nil
}
return b.Members
}
// HasRole reports whether member has role r.
func (p *Policy) HasRole(member string, r RoleName) bool {
return memberIndex(member, p.binding(r)) >= 0
}
// Add adds member member to role r if it is not already present.
// A new binding is created if there is no binding for the role.
func (p *Policy) Add(member string, r RoleName) {
b := p.binding(r)
if b == nil {
if p.InternalProto == nil {
p.InternalProto = &pb.Policy{}
}
p.InternalProto.Bindings = append(p.InternalProto.Bindings, &pb.Binding{
Role: string(r),
Members: []string{member},
})
return
}
if memberIndex(member, b) < 0 {
b.Members = append(b.Members, member)
return
}
}
// Remove removes member from role r if it is present.
func (p *Policy) Remove(member string, r RoleName) {
bi := p.bindingIndex(r)
if bi < 0 {
return
}
bindings := p.InternalProto.Bindings
b := bindings[bi]
mi := memberIndex(member, b)
if mi < 0 {
return
}
// Order doesn't matter for bindings or members, so to remove, move the last item
// into the removed spot and shrink the slice.
if len(b.Members) == 1 {
// Remove binding.
last := len(bindings) - 1
bindings[bi] = bindings[last]
bindings[last] = nil
p.InternalProto.Bindings = bindings[:last]
return
}
// Remove member.
// TODO(jba): worry about multiple copies of m?
last := len(b.Members) - 1
b.Members[mi] = b.Members[last]
b.Members[last] = ""
b.Members = b.Members[:last]
}
// Roles returns the names of all the roles that appear in the Policy.
func (p *Policy) Roles() []RoleName {
if p.InternalProto == nil {
return nil
}
var rns []RoleName
for _, b := range p.InternalProto.Bindings {
rns = append(rns, RoleName(b.Role))
}
return rns
}
// binding returns the Binding for the suppied role, or nil if there isn't one.
func (p *Policy) binding(r RoleName) *pb.Binding {
i := p.bindingIndex(r)
if i < 0 {
return nil
}
return p.InternalProto.Bindings[i]
}
func (p *Policy) bindingIndex(r RoleName) int {
if p.InternalProto == nil {
return -1
}
for i, b := range p.InternalProto.Bindings {
if b.Role == string(r) {
return i
}
}
return -1
}
// memberIndex returns the index of m in b's Members, or -1 if not found.
func memberIndex(m string, b *pb.Binding) int {
if b == nil {
return -1
}
for i, mm := range b.Members {
if mm == m {
return i
}
}
return -1
}
// insertMetadata inserts metadata into the given context
func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
out, _ := metadata.FromOutgoingContext(ctx)
out = out.Copy()
for _, md := range mds {
for k, v := range md {
out[k] = append(out[k], v...)
}
}
return metadata.NewOutgoingContext(ctx, out)
}
