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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_MEMORY_SHARED_MEMORY_SECURITY_POLICY_H_
#define BASE_MEMORY_SHARED_MEMORY_SECURITY_POLICY_H_
#include <stddef.h>
#include "base/base_export.h"
namespace mojo {
namespace core {
class ChannelLinux;
} // namespace core
} // namespace mojo
namespace base {
namespace subtle {
class PlatformSharedMemoryRegion;
} // namespace subtle
// Helper to enforce a limit for the total amount of shared memory that can be
// mapped. This can help prevent an attacker from spraying the address space of
// a process with shared memory mappings to bypass ASLR. For more details, see
// https://googleprojectzero.blogspot.com/2019/04/virtually-unlimited-memory-escaping.html
class BASE_EXPORT SharedMemorySecurityPolicy {
private:
friend class subtle::PlatformSharedMemoryRegion;
friend class SharedMemoryMapping;
friend class mojo::core::ChannelLinux;
// Checks that a mapping with |size| can be created. Returns false if there is
// an overflow in internal calculations, or the max limit has been reached.
[[nodiscard]] static bool AcquireReservationForMapping(size_t size);
// Releases a reservation that was previously acquired.
static void ReleaseReservationForMapping(size_t size);
};
} // namespace base
#endif // BASE_MEMORY_SHARED_MEMORY_SECURITY_POLICY_H_
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