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rbac.go
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rbac.go
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/*
*
* Copyright 2021 gRPC authors.
*
* 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 rbac implements the Envoy RBAC HTTP filter.
package rbac
import (
"context"
"errors"
"fmt"
"strings"
"github.com/golang/protobuf/proto"
"github.com/golang/protobuf/ptypes"
"google.golang.org/grpc/internal"
"google.golang.org/grpc/internal/resolver"
"google.golang.org/grpc/internal/xds/rbac"
"google.golang.org/grpc/xds/internal/httpfilter"
"google.golang.org/protobuf/types/known/anypb"
v3rbacpb "github.com/envoyproxy/go-control-plane/envoy/config/rbac/v3"
rpb "github.com/envoyproxy/go-control-plane/envoy/extensions/filters/http/rbac/v3"
)
func init() {
httpfilter.Register(builder{})
// TODO: Remove these once the RBAC env var is removed.
internal.RegisterRBACHTTPFilterForTesting = func() {
httpfilter.Register(builder{})
}
internal.UnregisterRBACHTTPFilterForTesting = func() {
for _, typeURL := range builder.TypeURLs(builder{}) {
httpfilter.UnregisterForTesting(typeURL)
}
}
}
type builder struct {
}
type config struct {
httpfilter.FilterConfig
chainEngine *rbac.ChainEngine
}
func (builder) TypeURLs() []string {
return []string{
"type.googleapis.com/envoy.extensions.filters.http.rbac.v3.RBAC",
"type.googleapis.com/envoy.extensions.filters.http.rbac.v3.RBACPerRoute",
}
}
// Parsing is the same for the base config and the override config.
func parseConfig(rbacCfg *rpb.RBAC) (httpfilter.FilterConfig, error) {
// All the validation logic described in A41.
for _, policy := range rbacCfg.GetRules().GetPolicies() {
// "Policy.condition and Policy.checked_condition must cause a
// validation failure if present." - A41
if policy.Condition != nil {
return nil, errors.New("rbac: Policy.condition is present")
}
if policy.CheckedCondition != nil {
return nil, errors.New("rbac: policy.CheckedCondition is present")
}
// "It is also a validation failure if Permission or Principal has a
// header matcher for a grpc- prefixed header name or :scheme." - A41
for _, principal := range policy.Principals {
name := principal.GetHeader().GetName()
if name == ":scheme" || strings.HasPrefix(name, "grpc-") {
return nil, fmt.Errorf("rbac: principal header matcher for %v is :scheme or starts with grpc", name)
}
}
for _, permission := range policy.Permissions {
name := permission.GetHeader().GetName()
if name == ":scheme" || strings.HasPrefix(name, "grpc-") {
return nil, fmt.Errorf("rbac: permission header matcher for %v is :scheme or starts with grpc", name)
}
}
}
// "Envoy aliases :authority and Host in its header map implementation, so
// they should be treated equivalent for the RBAC matchers; there must be no
// behavior change depending on which of the two header names is used in the
// RBAC policy." - A41. Loop through config's principals and policies, change
// any header matcher with value "host" to :authority", as that is what
// grpc-go shifts both headers to in transport layer.
for _, policy := range rbacCfg.GetRules().GetPolicies() {
for _, principal := range policy.Principals {
if principal.GetHeader().GetName() == "host" {
principal.GetHeader().Name = ":authority"
}
}
for _, permission := range policy.Permissions {
if permission.GetHeader().GetName() == "host" {
permission.GetHeader().Name = ":authority"
}
}
}
// Two cases where this HTTP Filter is a no op:
// "If absent, no enforcing RBAC policy will be applied" - RBAC
// Documentation for Rules field.
// "At this time, if the RBAC.action is Action.LOG then the policy will be
// completely ignored, as if RBAC was not configurated." - A41
if rbacCfg.Rules == nil || rbacCfg.GetRules().GetAction() == v3rbacpb.RBAC_LOG {
return config{}, nil
}
// TODO(gregorycooke) - change the call chain to here so we have the filter
// name to input here instead of an empty string. It will come from here:
// https://github.com/grpc/grpc-go/blob/eff0942e95d93112921414aee758e619ec86f26f/xds/internal/xdsclient/xdsresource/unmarshal_lds.go#L199
ce, err := rbac.NewChainEngine([]*v3rbacpb.RBAC{rbacCfg.GetRules()}, "")
if err != nil {
// "At this time, if the RBAC.action is Action.LOG then the policy will be
// completely ignored, as if RBAC was not configurated." - A41
if rbacCfg.GetRules().GetAction() != v3rbacpb.RBAC_LOG {
return nil, fmt.Errorf("rbac: error constructing matching engine: %v", err)
}
}
return config{chainEngine: ce}, nil
}
func (builder) ParseFilterConfig(cfg proto.Message) (httpfilter.FilterConfig, error) {
if cfg == nil {
return nil, fmt.Errorf("rbac: nil configuration message provided")
}
any, ok := cfg.(*anypb.Any)
if !ok {
return nil, fmt.Errorf("rbac: error parsing config %v: unknown type %T", cfg, cfg)
}
msg := new(rpb.RBAC)
if err := ptypes.UnmarshalAny(any, msg); err != nil {
return nil, fmt.Errorf("rbac: error parsing config %v: %v", cfg, err)
}
return parseConfig(msg)
}
func (builder) ParseFilterConfigOverride(override proto.Message) (httpfilter.FilterConfig, error) {
if override == nil {
return nil, fmt.Errorf("rbac: nil configuration message provided")
}
any, ok := override.(*anypb.Any)
if !ok {
return nil, fmt.Errorf("rbac: error parsing override config %v: unknown type %T", override, override)
}
msg := new(rpb.RBACPerRoute)
if err := ptypes.UnmarshalAny(any, msg); err != nil {
return nil, fmt.Errorf("rbac: error parsing override config %v: %v", override, err)
}
return parseConfig(msg.Rbac)
}
func (builder) IsTerminal() bool {
return false
}
var _ httpfilter.ServerInterceptorBuilder = builder{}
// BuildServerInterceptor is an optional interface builder implements in order
// to signify it works server side.
func (builder) BuildServerInterceptor(cfg httpfilter.FilterConfig, override httpfilter.FilterConfig) (resolver.ServerInterceptor, error) {
if cfg == nil {
return nil, fmt.Errorf("rbac: nil config provided")
}
c, ok := cfg.(config)
if !ok {
return nil, fmt.Errorf("rbac: incorrect config type provided (%T): %v", cfg, cfg)
}
if override != nil {
// override completely replaces the listener configuration; but we
// still validate the listener config type.
c, ok = override.(config)
if !ok {
return nil, fmt.Errorf("rbac: incorrect override config type provided (%T): %v", override, override)
}
}
// RBAC HTTP Filter is a no op from one of these two cases:
// "If absent, no enforcing RBAC policy will be applied" - RBAC
// Documentation for Rules field.
// "At this time, if the RBAC.action is Action.LOG then the policy will be
// completely ignored, as if RBAC was not configurated." - A41
if c.chainEngine == nil {
return nil, nil
}
return &interceptor{chainEngine: c.chainEngine}, nil
}
type interceptor struct {
chainEngine *rbac.ChainEngine
}
func (i *interceptor) AllowRPC(ctx context.Context) error {
return i.chainEngine.IsAuthorized(ctx)
}