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51ed9ec971
Use misc methods of avoiding unnecesary header includes. Replace int typedefs with int##_t from stdint.h. Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h. Normalize QT_VERSION ifs where possible. Resolve some indirect dependencies as direct ones. Remove extern declarations from .cpp files.
256 lines
8.8 KiB
C++
256 lines
8.8 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2013 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_ALLOCATORS_H
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#define BITCOIN_ALLOCATORS_H
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#include <map>
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#include <string>
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#include <string.h>
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#include <boost/thread/mutex.hpp>
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#include <boost/thread/once.hpp>
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#include <openssl/crypto.h> // for OPENSSL_cleanse()
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/**
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* Thread-safe class to keep track of locked (ie, non-swappable) memory pages.
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*
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* Memory locks do not stack, that is, pages which have been locked several times by calls to mlock()
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* will be unlocked by a single call to munlock(). This can result in keying material ending up in swap when
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* those functions are used naively. This class simulates stacking memory locks by keeping a counter per page.
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*
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* @note By using a map from each page base address to lock count, this class is optimized for
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* small objects that span up to a few pages, mostly smaller than a page. To support large allocations,
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* something like an interval tree would be the preferred data structure.
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*/
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template <class Locker> class LockedPageManagerBase
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{
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public:
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LockedPageManagerBase(size_t page_size):
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page_size(page_size)
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{
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// Determine bitmask for extracting page from address
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assert(!(page_size & (page_size-1))); // size must be power of two
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page_mask = ~(page_size - 1);
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}
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~LockedPageManagerBase()
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{
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assert(this->GetLockedPageCount() == 0);
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}
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// For all pages in affected range, increase lock count
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void LockRange(void *p, size_t size)
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{
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boost::mutex::scoped_lock lock(mutex);
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if(!size) return;
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const size_t base_addr = reinterpret_cast<size_t>(p);
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const size_t start_page = base_addr & page_mask;
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const size_t end_page = (base_addr + size - 1) & page_mask;
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for(size_t page = start_page; page <= end_page; page += page_size)
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{
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Histogram::iterator it = histogram.find(page);
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if(it == histogram.end()) // Newly locked page
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{
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locker.Lock(reinterpret_cast<void*>(page), page_size);
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histogram.insert(std::make_pair(page, 1));
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}
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else // Page was already locked; increase counter
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{
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it->second += 1;
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}
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}
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}
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// For all pages in affected range, decrease lock count
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void UnlockRange(void *p, size_t size)
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{
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boost::mutex::scoped_lock lock(mutex);
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if(!size) return;
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const size_t base_addr = reinterpret_cast<size_t>(p);
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const size_t start_page = base_addr & page_mask;
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const size_t end_page = (base_addr + size - 1) & page_mask;
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for(size_t page = start_page; page <= end_page; page += page_size)
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{
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Histogram::iterator it = histogram.find(page);
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assert(it != histogram.end()); // Cannot unlock an area that was not locked
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// Decrease counter for page, when it is zero, the page will be unlocked
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it->second -= 1;
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if(it->second == 0) // Nothing on the page anymore that keeps it locked
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{
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// Unlock page and remove the count from histogram
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locker.Unlock(reinterpret_cast<void*>(page), page_size);
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histogram.erase(it);
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}
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}
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}
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// Get number of locked pages for diagnostics
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int GetLockedPageCount()
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{
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boost::mutex::scoped_lock lock(mutex);
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return histogram.size();
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}
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private:
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Locker locker;
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boost::mutex mutex;
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size_t page_size, page_mask;
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// map of page base address to lock count
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typedef std::map<size_t,int> Histogram;
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Histogram histogram;
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};
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/**
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* OS-dependent memory page locking/unlocking.
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* Defined as policy class to make stubbing for test possible.
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*/
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class MemoryPageLocker
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{
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public:
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/** Lock memory pages.
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* addr and len must be a multiple of the system page size
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*/
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bool Lock(const void *addr, size_t len);
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/** Unlock memory pages.
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* addr and len must be a multiple of the system page size
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*/
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bool Unlock(const void *addr, size_t len);
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};
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/**
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* Singleton class to keep track of locked (ie, non-swappable) memory pages, for use in
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* std::allocator templates.
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*
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* Some implementations of the STL allocate memory in some constructors (i.e., see
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* MSVC's vector<T> implementation where it allocates 1 byte of memory in the allocator.)
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* Due to the unpredictable order of static initializers, we have to make sure the
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* LockedPageManager instance exists before any other STL-based objects that use
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* secure_allocator are created. So instead of having LockedPageManager also be
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* static-intialized, it is created on demand.
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*/
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class LockedPageManager: public LockedPageManagerBase<MemoryPageLocker>
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{
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public:
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static LockedPageManager& Instance()
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{
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boost::call_once(LockedPageManager::CreateInstance, LockedPageManager::init_flag);
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return *LockedPageManager::_instance;
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}
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private:
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LockedPageManager();
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static void CreateInstance()
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{
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// Using a local static instance guarantees that the object is initialized
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// when it's first needed and also deinitialized after all objects that use
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// it are done with it. I can think of one unlikely scenario where we may
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// have a static deinitialization order/problem, but the check in
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// LockedPageManagerBase's destructor helps us detect if that ever happens.
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static LockedPageManager instance;
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LockedPageManager::_instance = &instance;
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}
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static LockedPageManager* _instance;
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static boost::once_flag init_flag;
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};
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//
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// Functions for directly locking/unlocking memory objects.
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// Intended for non-dynamically allocated structures.
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//
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template<typename T> void LockObject(const T &t) {
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LockedPageManager::Instance().LockRange((void*)(&t), sizeof(T));
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}
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template<typename T> void UnlockObject(const T &t) {
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OPENSSL_cleanse((void*)(&t), sizeof(T));
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LockedPageManager::Instance().UnlockRange((void*)(&t), sizeof(T));
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}
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//
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// Allocator that locks its contents from being paged
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// out of memory and clears its contents before deletion.
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//
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template<typename T>
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struct secure_allocator : public std::allocator<T>
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{
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// MSVC8 default copy constructor is broken
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typedef std::allocator<T> base;
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typedef typename base::size_type size_type;
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typedef typename base::difference_type difference_type;
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typedef typename base::pointer pointer;
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typedef typename base::const_pointer const_pointer;
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typedef typename base::reference reference;
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typedef typename base::const_reference const_reference;
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typedef typename base::value_type value_type;
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secure_allocator() throw() {}
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secure_allocator(const secure_allocator& a) throw() : base(a) {}
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template <typename U>
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secure_allocator(const secure_allocator<U>& a) throw() : base(a) {}
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~secure_allocator() throw() {}
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template<typename _Other> struct rebind
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{ typedef secure_allocator<_Other> other; };
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T* allocate(std::size_t n, const void *hint = 0)
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{
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T *p;
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p = std::allocator<T>::allocate(n, hint);
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if (p != NULL)
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LockedPageManager::Instance().LockRange(p, sizeof(T) * n);
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return p;
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}
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void deallocate(T* p, std::size_t n)
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{
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if (p != NULL)
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{
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OPENSSL_cleanse(p, sizeof(T) * n);
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LockedPageManager::Instance().UnlockRange(p, sizeof(T) * n);
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}
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std::allocator<T>::deallocate(p, n);
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}
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};
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//
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// Allocator that clears its contents before deletion.
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//
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template<typename T>
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struct zero_after_free_allocator : public std::allocator<T>
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{
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// MSVC8 default copy constructor is broken
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typedef std::allocator<T> base;
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typedef typename base::size_type size_type;
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typedef typename base::difference_type difference_type;
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typedef typename base::pointer pointer;
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typedef typename base::const_pointer const_pointer;
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typedef typename base::reference reference;
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typedef typename base::const_reference const_reference;
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typedef typename base::value_type value_type;
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zero_after_free_allocator() throw() {}
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zero_after_free_allocator(const zero_after_free_allocator& a) throw() : base(a) {}
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template <typename U>
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zero_after_free_allocator(const zero_after_free_allocator<U>& a) throw() : base(a) {}
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~zero_after_free_allocator() throw() {}
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template<typename _Other> struct rebind
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{ typedef zero_after_free_allocator<_Other> other; };
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void deallocate(T* p, std::size_t n)
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{
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if (p != NULL)
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OPENSSL_cleanse(p, sizeof(T) * n);
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std::allocator<T>::deallocate(p, n);
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}
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};
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// This is exactly like std::string, but with a custom allocator.
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typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;
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#endif
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