1//===-- guarded_pool_allocator_posix.cpp ------------------------*- C++ -*-===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8 9#include "gwp_asan/common.h" 10#include "gwp_asan/guarded_pool_allocator.h" 11#include "gwp_asan/platform_specific/guarded_pool_allocator_tls.h" 12#include "gwp_asan/utilities.h" 13 14#include <assert.h> 15#include <pthread.h> 16#include <stdint.h> 17#include <stdlib.h> 18#include <sys/mman.h> 19#include <time.h> 20#include <unistd.h> 21 22#ifdef ANDROID 23#include <sys/prctl.h> 24#define PR_SET_VMA 0x53564d41 25#define PR_SET_VMA_ANON_NAME 0 26#endif // ANDROID 27 28namespace { 29void MaybeSetMappingName(void *Mapping, size_t Size, const char *Name) { 30#ifdef ANDROID 31 prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, Mapping, Size, Name); 32#endif // ANDROID 33 // Anonymous mapping names are only supported on Android. 34 return; 35} 36} // anonymous namespace 37 38namespace gwp_asan { 39 40void GuardedPoolAllocator::initPRNG() { 41 getThreadLocals()->RandomState = 42 static_cast<uint32_t>(time(nullptr) + getThreadID()); 43} 44 45void *GuardedPoolAllocator::map(size_t Size, const char *Name) const { 46 assert((Size % State.PageSize) == 0); 47 void *Ptr = mmap(nullptr, Size, PROT_READ | PROT_WRITE, 48 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); 49 Check(Ptr != MAP_FAILED, "Failed to map guarded pool allocator memory"); 50 MaybeSetMappingName(Ptr, Size, Name); 51 return Ptr; 52} 53 54void GuardedPoolAllocator::unmap(void *Ptr, size_t Size) const { 55 assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0); 56 assert((Size % State.PageSize) == 0); 57 Check(munmap(Ptr, Size) == 0, 58 "Failed to unmap guarded pool allocator memory."); 59} 60 61void *GuardedPoolAllocator::reserveGuardedPool(size_t Size) { 62 assert((Size % State.PageSize) == 0); 63 void *Ptr = 64 mmap(nullptr, Size, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); 65 Check(Ptr != MAP_FAILED, "Failed to reserve guarded pool allocator memory"); 66 MaybeSetMappingName(Ptr, Size, kGwpAsanGuardPageName); 67 return Ptr; 68} 69 70void GuardedPoolAllocator::unreserveGuardedPool() { 71 unmap(reinterpret_cast<void *>(State.GuardedPagePool), 72 State.GuardedPagePoolEnd - State.GuardedPagePool); 73} 74 75void GuardedPoolAllocator::allocateInGuardedPool(void *Ptr, size_t Size) const { 76 assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0); 77 assert((Size % State.PageSize) == 0); 78 Check(mprotect(Ptr, Size, PROT_READ | PROT_WRITE) == 0, 79 "Failed to allocate in guarded pool allocator memory"); 80 MaybeSetMappingName(Ptr, Size, kGwpAsanAliveSlotName); 81} 82 83void GuardedPoolAllocator::deallocateInGuardedPool(void *Ptr, 84 size_t Size) const { 85 assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0); 86 assert((Size % State.PageSize) == 0); 87 // mmap() a PROT_NONE page over the address to release it to the system, if 88 // we used mprotect() here the system would count pages in the quarantine 89 // against the RSS. 90 Check(mmap(Ptr, Size, PROT_NONE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 91 0) != MAP_FAILED, 92 "Failed to deallocate in guarded pool allocator memory"); 93 MaybeSetMappingName(Ptr, Size, kGwpAsanGuardPageName); 94} 95 96size_t GuardedPoolAllocator::getPlatformPageSize() { 97 return sysconf(_SC_PAGESIZE); 98} 99 100void GuardedPoolAllocator::installAtFork() { 101 static bool AtForkInstalled = false; 102 if (AtForkInstalled) 103 return; 104 AtForkInstalled = true; 105 auto Disable = []() { 106 if (auto *S = getSingleton()) 107 S->disable(); 108 }; 109 auto Enable = []() { 110 if (auto *S = getSingleton()) 111 S->enable(); 112 }; 113 pthread_atfork(Disable, Enable, Enable); 114} 115} // namespace gwp_asan 116