xpcom/base/RLBoxSandboxPool.cpp

   1 /* -*- Mode: C++; tab-width: 8; 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 #include "nsThreadUtils.h"
   8 #include "mozilla/ClearOnShutdown.h"
   9 #include "mozilla/DebugOnly.h"
  10 #include "mozilla/RLBoxSandboxPool.h"
  11 #ifdef MOZ_USING_WASM_SANDBOXING
  12 #  include "mozilla/rlbox/rlbox_config.h"
  13 #  include "mozilla/rlbox/rlbox_wasm2c_sandbox.hpp"
  14 #endif
  15
  16 using namespace mozilla;
  17
  18 NS_IMPL_ISUPPORTS(RLBoxSandboxPool, nsITimerCallback, nsINamed)
  19
  20 void RLBoxSandboxPool::StartTimer() {
  21   mMutex.AssertCurrentThreadOwns();
  22   MOZ_ASSERT(!mTimer, "timer already initialized");
  23   if (NS_IsMainThread() &&
  24       PastShutdownPhase(ShutdownPhase::AppShutdownConfirmed)) {
  25     // If we're shutting down, setting the time might fail, and we don't need it
  26     // (since all the memory will be cleaned up soon anyway). Note that
  27     // PastShutdownPhase() can only be called on the main thread, but that's
  28     // fine, because other threads will have joined already by the point timers
  29     // start failing to register.
  30     mPool.Clear();
  31     return;
  32   }
  33   DebugOnly<nsresult> rv = NS_NewTimerWithCallback(
  34       getter_AddRefs(mTimer), this, mDelaySeconds * 1000,
  35       nsITimer::TYPE_ONE_SHOT, GetMainThreadSerialEventTarget());
  36   MOZ_ASSERT(NS_SUCCEEDED(rv), "failed to create timer");
  37 }
  38
  39 void RLBoxSandboxPool::CancelTimer() {
  40   mMutex.AssertCurrentThreadOwns();
  41   if (mTimer) {
  42     mTimer->Cancel();
  43     mTimer = nullptr;
  44   }
  45 }
  46
  47 NS_IMETHODIMP RLBoxSandboxPool::Notify(nsITimer* aTimer) {
  48   MutexAutoLock lock(mMutex);
  49
  50   mPool.Clear();
  51   mTimer = nullptr;
  52
  53   return NS_OK;
  54 }
  55
  56 NS_IMETHODIMP RLBoxSandboxPool::GetName(nsACString& aName) {
  57   aName.AssignLiteral("RLBoxSandboxPool");
  58   return NS_OK;
  59 }
  60
  61 void RLBoxSandboxPool::Push(UniquePtr<RLBoxSandboxDataBase> sbxData) {
  62   MutexAutoLock lock(mMutex);
  63
  64   mPool.AppendElement(std::move(sbxData));
  65   if (!mTimer) {
  66     StartTimer();
  67   }
  68 }
  69
  70 UniquePtr<RLBoxSandboxPoolData> RLBoxSandboxPool::PopOrCreate(
  71     uint64_t aMinSize) {
  72   MutexAutoLock lock(mMutex);
  73
  74   UniquePtr<RLBoxSandboxDataBase> sbxData;
  75
  76   if (!mPool.IsEmpty()) {
  77     const int64_t lastIndex = ReleaseAssertedCast<int64_t>(mPool.Length()) - 1;
  78     for (int64_t i = lastIndex; i >= 0; i--) {
  79       if (mPool[i]->mSize >= aMinSize) {
  80         sbxData = std::move(mPool[i]);
  81         mPool.RemoveElementAt(i);
  82
  83         // If we reuse a sandbox from the pool, reset the timer to clear the
  84         // pool
  85         CancelTimer();
  86         if (!mPool.IsEmpty()) {
  87           StartTimer();
  88         }
  89         break;
  90       }
  91     }
  92   }
  93
  94   if (!sbxData) {
  95 #ifdef MOZ_USING_WASM_SANDBOXING
  96     // RLBox's wasm sandboxes have a limited platform dependent capacity. We
  97     // track this capacity in this pool. Note the noop sandboxes have no
  98     // capacity limit but this design assumes that all sandboxes use the wasm
  99     // sandbox limit.
 100     const uint64_t defaultCapacityForSandbox =
 101         wasm_rt_get_default_max_linear_memory_size();
 102     const uint64_t minSandboxCapacity =
 103         std::max(aMinSize, defaultCapacityForSandbox);
 104     const uint64_t chosenAdjustedCapacity =
 105         rlbox::rlbox_wasm2c_sandbox::rlbox_wasm2c_get_adjusted_heap_size(
 106             minSandboxCapacity);
 107 #else
 108     // If sandboxing is disabled altogether we just set a limit of 4gb.
 109     // This is not actually enforced by the noop sandbox.
 110     const uint64_t chosenAdjustedCapacity = static_cast<uint64_t>(1) << 32;
 111 #endif
 112     sbxData = CreateSandboxData(chosenAdjustedCapacity);
 113     NS_ENSURE_TRUE(sbxData, nullptr);
 114   }
 115
 116   return MakeUnique<RLBoxSandboxPoolData>(std::move(sbxData), this);
 117 }