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1 
2 // Copyright 2020 gRPC authors.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 //     http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 
16 #ifndef GRPC_CORE_LIB_SECURITY_AUTHORIZATION_CEL_AUTHORIZATION_ENGINE_H
17 #define GRPC_CORE_LIB_SECURITY_AUTHORIZATION_CEL_AUTHORIZATION_ENGINE_H
18 
19 #include <grpc/support/port_platform.h>
20 
21 #include <grpc/support/log.h>
22 #include <map>
23 #include <memory>
24 #include <string>
25 #include <vector>
26 
27 #include "absl/container/flat_hash_set.h"
28 #include "envoy/config/rbac/v3/rbac.upb.h"
29 #include "google/api/expr/v1alpha1/syntax.upb.h"
30 #include "upb/upb.hpp"
31 
32 #include "src/core/lib/security/authorization/evaluate_args.h"
33 #include "src/core/lib/security/authorization/mock_cel/activation.h"
34 
35 namespace grpc_core {
36 
37 // CelAuthorizationEngine makes an AuthorizationDecision to ALLOW or DENY the
38 // current action based on the condition fields in provided RBAC policies.
39 // The engine may be constructed with one or two policies. If two polcies,
40 // the first policy is deny-if-matched and the second is allow-if-matched.
41 // The engine returns UNDECIDED decision if it fails to find a match in any
42 // policy. This engine ignores the principal and permission fields in RBAC
43 // policies. It is the caller's responsibility to provide RBAC policies that
44 // are compatible with this engine.
45 //
46 // Example:
47 // CelAuthorizationEngine* engine =
48 // CelAuthorizationEngine::CreateCelAuthorizationEngine(rbac_policies);
49 // engine->Evaluate(evaluate_args); // returns authorization decision.
50 class CelAuthorizationEngine {
51  public:
52   // rbac_policies must be a vector containing either a single policy of any
53   // kind, or one deny policy and one allow policy, in that order.
54   static std::unique_ptr<CelAuthorizationEngine> CreateCelAuthorizationEngine(
55       const std::vector<envoy_config_rbac_v3_RBAC*>& rbac_policies);
56 
57   // Users should use the CreateCelAuthorizationEngine factory function
58   // instead of calling the CelAuthorizationEngine constructor directly.
59   explicit CelAuthorizationEngine(
60       const std::vector<envoy_config_rbac_v3_RBAC*>& rbac_policies);
61   // TODO(mywang@google.com): add an Evaluate member function.
62 
63  private:
64   enum Action {
65     kAllow,
66     kDeny,
67   };
68 
69   std::unique_ptr<mock_cel::Activation> CreateActivation(
70       const EvaluateArgs& args);
71 
72   std::map<const std::string, const google_api_expr_v1alpha1_Expr*>
73       deny_if_matched_;
74   std::map<const std::string, const google_api_expr_v1alpha1_Expr*>
75       allow_if_matched_;
76   upb::Arena arena_;
77   absl::flat_hash_set<std::string> envoy_attributes_;
78   absl::flat_hash_set<std::string> header_keys_;
79   std::unique_ptr<mock_cel::CelMap> headers_;
80 };
81 
82 }  // namespace grpc_core
83 
84 #endif /* GRPC_CORE_LIB_SECURITY_AUTHORIZATION_CEL_AUTHORIZATION_ENGINE_H */
85