xpcom/base/RLBoxSandboxPool.h

   1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef SECURITY_RLBOX_SANDBOX_POOL_H_
   8 #define SECURITY_RLBOX_SANDBOX_POOL_H_
   9
  10 #include "nsCOMPtr.h"
  11 #include "nsITimer.h"
  12 #include "nsTArray.h"
  13 #include "nsINamed.h"
  14
  15 #include "mozilla/Mutex.h"
  16 #include "mozilla/rlbox/rlbox_types.hpp"
  17
  18 namespace mozilla {
  19
  20 class RLBoxSandboxDataBase;
  21 class RLBoxSandboxPoolData;
  22
  23 // The RLBoxSandboxPool class is used to manage a pool of sandboxes that are
  24 // reused -- to save sandbox creation time and memory -- and automatically
  25 // destroyed when no longer in used. The sandbox pool is threadsafe and can be
  26 // used to share unused sandboxes across a thread pool.
  27 //
  28 // Each sandbox pool manages a particular kind of sandbox (e.g., expat
  29 // sandboxes, woff2 sandboxes, etc.); this is largely because different
  30 // sandboxes might have different callbacks and attacker assumptions. Hence,
  31 // RLBoxSandboxPool is intended to be subclassed for the different kinds of
  32 // sandbox pools. Each sandbox pool class needs to implement the
  33 // CreateSandboxData() method, which returns a pointer to a RLBoxSandboxDataBase
  34 // object.  RLBoxSandboxDataBase itself should be subclassed to implement
  35 // sandbox-specific details.
  36 class RLBoxSandboxPool : public nsITimerCallback, public nsINamed {
  37  public:
  38   NS_DECL_THREADSAFE_ISUPPORTS
  39   NS_DECL_NSITIMERCALLBACK
  40   NS_DECL_NSINAMED
  41
  42   RLBoxSandboxPool(size_t aDelaySeconds = 10)
  43       : mPool(),
  44         mDelaySeconds(aDelaySeconds),
  45         mMutex("RLBoxSandboxPool::mMutex"){};
  46
  47   void Push(UniquePtr<RLBoxSandboxDataBase> sbx);
  48   // PopOrCreate returns a sandbox from the pool if the pool is not empty and
  49   // tries to mint a new one otherwise. If creating a new sandbox fails, the
  50   // function returns a nullptr. The parameter aMinSize is the minimum size of
  51   // the sandbox memory.
  52   UniquePtr<RLBoxSandboxPoolData> PopOrCreate(uint64_t aMinSize = 0);
  53
  54  protected:
  55   // CreateSandboxData takes a parameter which is the size of the sandbox memory
  56   virtual UniquePtr<RLBoxSandboxDataBase> CreateSandboxData(uint64_t aSize) = 0;
  57   virtual ~RLBoxSandboxPool() = default;
  58
  59  private:
  60   void StartTimer() MOZ_REQUIRES(mMutex);
  61   void CancelTimer() MOZ_REQUIRES(mMutex);
  62
  63   nsTArray<UniquePtr<RLBoxSandboxDataBase>> mPool MOZ_GUARDED_BY(mMutex);
  64   const size_t mDelaySeconds MOZ_GUARDED_BY(mMutex);
  65   nsCOMPtr<nsITimer> mTimer MOZ_GUARDED_BY(mMutex);
  66   mozilla::Mutex mMutex;
  67 };
  68
  69 // The RLBoxSandboxDataBase class serves as the subclass for all sandbox data
  70 // classes, which keep track of the RLBox sandbox and any relevant sandbox data
  71 // (e.g., callbacks).
  72 class RLBoxSandboxDataBase {
  73  public:
  74   const uint64_t mSize;
  75   explicit RLBoxSandboxDataBase(uint64_t aSize) : mSize(aSize) {}
  76   virtual ~RLBoxSandboxDataBase() = default;
  77 };
  78
  79 // This class is used wrap sandbox data objects (RLBoxSandboxDataBase) when they
  80 // are popped from sandbox pools. The wrapper destructor pushes the sandbox back
  81 // into the pool.
  82 class RLBoxSandboxPoolData {
  83  public:
  84   RLBoxSandboxPoolData(UniquePtr<RLBoxSandboxDataBase> aSbxData,
  85                        RefPtr<RLBoxSandboxPool> aPool) {
  86     mSbxData = std::move(aSbxData);
  87     mPool = aPool;
  88     MOZ_COUNT_CTOR(RLBoxSandboxPoolData);
  89   }
  90
  91   RLBoxSandboxDataBase* SandboxData() const { return mSbxData.get(); };
  92
  93   ~RLBoxSandboxPoolData() {
  94     mPool->Push(std::move(mSbxData));
  95     MOZ_COUNT_DTOR(RLBoxSandboxPoolData);
  96   };
  97
  98  private:
  99   UniquePtr<RLBoxSandboxDataBase> mSbxData;
 100   RefPtr<RLBoxSandboxPool> mPool;
 101 };
 102
 103 }  // namespace mozilla
 104
 105 #endif