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/*
* Copyright (C) 2019-2022 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "Integrity.h"
#include "JSCJSValue.h"
#include "StructureID.h"
#include "VM.h"
#include "VMInspector.h"
#include <wtf/Atomics.h>
#include <wtf/Gigacage.h>
namespace JSC {
namespace Integrity {
ALWAYS_INLINE bool Random::shouldAudit(VM& vm)
{
// If auditing is enabled, then the top bit of m_triggerBits is always set
// to 1 on reload. When this top bit reaches the bottom, it does not
// indicate that we should trigger an audit but rather that we've shifted
// out all the available trigger bits and hence, need to reload. Instead,
// reloadAndCheckShouldAuditSlow() will return whether we actually need to
// trigger an audit this turn.
//
// This function can be called concurrently from different threads and can
// be racy. For that reason, we intentionally do not write back to
// m_triggerBits if newTriggerBits is null. This ensures that if
// Options::randomIntegrityAuditRate() is non-zero, then m_triggerBits will
// always have at least 1 bit to trigger a reload.
uint64_t newTriggerBits = m_triggerBits;
bool shouldAudit = newTriggerBits & 1;
newTriggerBits = newTriggerBits >> 1;
if (LIKELY(!shouldAudit)) {
m_triggerBits = newTriggerBits;
return false;
}
if (!newTriggerBits)
return reloadAndCheckShouldAuditSlow(vm);
m_triggerBits = newTriggerBits;
return true;
}
template<AuditLevel auditLevel>
ALWAYS_INLINE void auditCell(VM& vm, JSValue value)
{
if constexpr (auditLevel == AuditLevel::None)
return;
if (value.isCell())
auditCell<auditLevel>(vm, value.asCell());
}
ALWAYS_INLINE void auditCellMinimally(VM& vm, JSCell* cell)
{
if (UNLIKELY(Gigacage::contains(cell)))
auditCellMinimallySlow(vm, cell);
}
ALWAYS_INLINE void auditCellRandomly(VM& vm, JSCell* cell)
{
if (UNLIKELY(vm.integrityRandom().shouldAudit(vm)))
auditCellFully(vm, cell);
}
ALWAYS_INLINE void auditCellFully(VM& vm, JSCell* cell)
{
#if USE(JSVALUE64)
doAudit(vm, cell);
#else
auditCellMinimally(vm, cell);
#endif
}
ALWAYS_INLINE void auditStructureID(StructureID structureID)
{
UNUSED_PARAM(structureID);
#if CPU(ADDRESS64) && !ENABLE(STRUCTURE_ID_WITH_SHIFT)
ASSERT(static_cast<uintptr_t>(structureID.bits()) <= structureHeapAddressSize + StructureID::nukedStructureIDBit);
#endif
#if ENABLE(EXTRA_INTEGRITY_CHECKS) || ASSERT_ENABLED
Structure* structure = structureID.tryDecode();
IA_ASSERT(structure, "structureID.bits 0x%x", structureID.bits());
// structure should be pointing to readable memory. Force a read.
WTF::opaque(*std::bit_cast<uintptr_t*>(structure));
#endif
}
#if USE(JSVALUE64)
JS_EXPORT_PRIVATE VM* doAuditSlow(VM*);
ALWAYS_INLINE VM* doAudit(VM* vm)
{
if (UNLIKELY(!VMInspector::isValidVM(vm)))
return doAuditSlow(vm);
return vm;
}
#endif // USE(JSVALUE64)
} // namespace Integrity
} // namespace JSC
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