trusted-pointer-scope.h

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// Copyright 2025 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef V8_SANDBOX_TRUSTED_POINTER_SCOPE_H_
#define V8_SANDBOX_TRUSTED_POINTER_SCOPE_H_
 
#include "src/sandbox/isolate.h"
 
namespace v8::internal {
 
class DisallowJavascriptExecution;
 
#ifdef V8_ENABLE_SANDBOX
 
struct TrustedPointerTableEntry;
 
// A TrustedPointerPublishingScope is an optional facility for tracking
// (multiple) newly created TrustedPointerTable entries, and having the
// ability to neuter them afterwards, e.g. if their initialization as a
// group failed in such a way that they should not be made accessible to
// untrusted code (not even via existing in-sandbox corruption).
class TrustedPointerPublishingScope {
 public:
  TrustedPointerPublishingScope(Isolate* isolate,
                                const DisallowJavascriptExecution& no_js);
  ~TrustedPointerPublishingScope();
 
  // Decide whether the tracked pointers should be published or discarded.
  void MarkSuccess() { state_ = State::kSuccess; }
  void MarkFailure() { state_ = State::kFailure; }
 
  void TrackPointer(TrustedPointerTableEntry* entry);
 
 private:
  enum class State : uint8_t { kInProgress, kSuccess, kFailure };
  enum class Storage : uint8_t { kEmpty, kSingleton, kVector };
 
  State state_{State::kInProgress};
  Storage storage_{Storage::kEmpty};
  // We could use a base::SmallVector here, but it'd make the object bigger.
  union {
    TrustedPointerTableEntry* singleton_{nullptr};
    std::vector<TrustedPointerTableEntry*>* vector_;
  };
  Isolate* isolate_;
};
 
// Temporarily disables a TrustedPointerPublishingScope.
class DisableTrustedPointerPublishingScope {
 public:
  explicit DisableTrustedPointerPublishingScope(Isolate* isolate);
  ~DisableTrustedPointerPublishingScope();
 
 private:
  Isolate* isolate_;
  TrustedPointerPublishingScope* saved_{nullptr};
};
 
#else  // V8_ENABLE_SANDBOX
 
class TrustedPointerPublishingScope {
 public:
  TrustedPointerPublishingScope(Isolate* isolate,
                                const DisallowJavascriptExecution& no_js) {}
  void MarkSuccess() {}
  void MarkFailure() {}
};
 
class DisableTrustedPointerPublishingScope {
 public:
  explicit DisableTrustedPointerPublishingScope(Isolate* isolate) {}
};
 
#endif  // V8_ENABLE_SANDBOX
 
}  // namespace v8::internal
 
#endif  // V8_SANDBOX_TRUSTED_POINTER_SCOPE_H_