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
28 namespace {
MaybeSetMappingName(void * Mapping,size_t Size,const char * Name)29 void 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
38 namespace gwp_asan {
39
initPRNG()40 void GuardedPoolAllocator::initPRNG() {
41 getThreadLocals()->RandomState =
42 static_cast<uint32_t>(time(nullptr) + getThreadID());
43 }
44
map(size_t Size,const char * Name) const45 void *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
unmap(void * Ptr,size_t Size) const54 void 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
reserveGuardedPool(size_t Size)61 void *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
unreserveGuardedPool()70 void GuardedPoolAllocator::unreserveGuardedPool() {
71 unmap(reinterpret_cast<void *>(State.GuardedPagePool),
72 State.GuardedPagePoolEnd - State.GuardedPagePool);
73 }
74
allocateInGuardedPool(void * Ptr,size_t Size) const75 void 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
deallocateInGuardedPool(void * Ptr,size_t Size) const83 void 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
getPlatformPageSize()96 size_t GuardedPoolAllocator::getPlatformPageSize() {
97 return sysconf(_SC_PAGESIZE);
98 }
99
installAtFork()100 void GuardedPoolAllocator::installAtFork() {
101 auto Disable = []() {
102 if (auto *S = getSingleton())
103 S->disable();
104 };
105 auto Enable = []() {
106 if (auto *S = getSingleton())
107 S->enable();
108 };
109 pthread_atfork(Disable, Enable, Enable);
110 }
111 } // namespace gwp_asan
112