1 files changed, 106 insertions, 0 deletions
diff --git a/grpc/src/core/lib/security/authorization/grpc_server_authz_filter.cc b/grpc/src/core/lib/security/authorization/grpc_server_authz_filter.cc
new file mode 100644
index 00000000..44823c5f
--- /dev/null
+++ b/grpc/src/core/lib/security/authorization/grpc_server_authz_filter.cc
@@ -0,0 +1,106 @@
+// 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.
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/lib/security/authorization/grpc_server_authz_filter.h"
+
+#include "src/core/lib/channel/promise_based_filter.h"
+#include "src/core/lib/security/authorization/evaluate_args.h"
+#include "src/core/lib/transport/transport.h"
+
+namespace grpc_core {
+
+TraceFlag grpc_authz_trace(false, "grpc_authz_api");
+
+GrpcServerAuthzFilter::GrpcServerAuthzFilter(
+    RefCountedPtr<grpc_auth_context> auth_context, grpc_endpoint* endpoint,
+    RefCountedPtr<grpc_authorization_policy_provider> provider)
+    : auth_context_(std::move(auth_context)),
+      per_channel_evaluate_args_(auth_context_.get(), endpoint),
+      provider_(std::move(provider)) {}
+
+absl::StatusOr<GrpcServerAuthzFilter> GrpcServerAuthzFilter::Create(
+    ChannelArgs args, ChannelFilter::Args) {
+  auto* auth_context = args.GetObject<grpc_auth_context>();
+  auto* provider = args.GetObject<grpc_authorization_policy_provider>();
+  if (provider == nullptr) {
+    return absl::InvalidArgumentError("Failed to get authorization provider.");
+  }
+  // grpc_endpoint isn't needed because the current gRPC authorization policy
+  // does not support any rules that requires looking for source or destination
+  // addresses.
+  return GrpcServerAuthzFilter(
+      auth_context != nullptr ? auth_context->Ref() : nullptr,
+      /*endpoint=*/nullptr, provider->Ref());
+}
+
+bool GrpcServerAuthzFilter::IsAuthorized(
+    const ClientMetadataHandle& initial_metadata) {
+  EvaluateArgs args(initial_metadata.get(), &per_channel_evaluate_args_);
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_authz_trace)) {
+    gpr_log(GPR_DEBUG,
+            "checking request: url_path=%s, transport_security_type=%s, "
+            "uri_sans=[%s], dns_sans=[%s], subject=%s",
+            std::string(args.GetPath()).c_str(),
+            std::string(args.GetTransportSecurityType()).c_str(),
+            absl::StrJoin(args.GetUriSans(), ",").c_str(),
+            absl::StrJoin(args.GetDnsSans(), ",").c_str(),
+            std::string(args.GetSubject()).c_str());
+  }
+  grpc_authorization_policy_provider::AuthorizationEngines engines =
+      provider_->engines();
+  if (engines.deny_engine != nullptr) {
+    AuthorizationEngine::Decision decision =
+        engines.deny_engine->Evaluate(args);
+    if (decision.type == AuthorizationEngine::Decision::Type::kDeny) {
+      if (GRPC_TRACE_FLAG_ENABLED(grpc_authz_trace)) {
+        gpr_log(GPR_INFO, "chand=%p: request denied by policy %s.", this,
+                decision.matching_policy_name.c_str());
+      }
+      return false;
+    }
+  }
+  if (engines.allow_engine != nullptr) {
+    AuthorizationEngine::Decision decision =
+        engines.allow_engine->Evaluate(args);
+    if (decision.type == AuthorizationEngine::Decision::Type::kAllow) {
+      if (GRPC_TRACE_FLAG_ENABLED(grpc_authz_trace)) {
+        gpr_log(GPR_DEBUG, "chand=%p: request allowed by policy %s.", this,
+                decision.matching_policy_name.c_str());
+      }
+      return true;
+    }
+  }
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_authz_trace)) {
+    gpr_log(GPR_INFO, "chand=%p: request denied, no matching policy found.",
+            this);
+  }
+  return false;
+}
+
+ArenaPromise<ServerMetadataHandle> GrpcServerAuthzFilter::MakeCallPromise(
+    CallArgs call_args, NextPromiseFactory next_promise_factory) {
+  if (!IsAuthorized(call_args.client_initial_metadata)) {
+    return ArenaPromise<ServerMetadataHandle>(Immediate(ServerMetadataHandle(
+        absl::PermissionDeniedError("Unauthorized RPC request rejected."))));
+  }
+  return next_promise_factory(std::move(call_args));
+}
+
+const grpc_channel_filter GrpcServerAuthzFilter::kFilterVtable =
+    MakePromiseBasedFilter<GrpcServerAuthzFilter, FilterEndpoint::kServer>(
+        "grpc-server-authz");
+
+}  // namespace grpc_core