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 <errno.h>
16 #include <pthread.h>
17 #include <stdint.h>
18 #include <stdlib.h>
19 #include <sys/mman.h>
20 #include <time.h>
21 #include <unistd.h>
22
23 #ifdef ANDROID
24 #include <sys/prctl.h>
25 #define PR_SET_VMA 0x53564d41
26 #define PR_SET_VMA_ANON_NAME 0
27 #endif // ANDROID
28
29 namespace {
MaybeSetMappingName(void * Mapping,size_t Size,const char * Name)30 void MaybeSetMappingName(void *Mapping, size_t Size, const char *Name) {
31 #ifdef ANDROID
32 prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, Mapping, Size, Name);
33 #endif // ANDROID
34 // Anonymous mapping names are only supported on Android.
35 return;
36 }
37 } // anonymous namespace
38
39 namespace gwp_asan {
40
initPRNG()41 void GuardedPoolAllocator::initPRNG() {
42 getThreadLocals()->RandomState =
43 static_cast<uint32_t>(time(nullptr) + getThreadID());
44 }
45
map(size_t Size,const char * Name) const46 void *GuardedPoolAllocator::map(size_t Size, const char *Name) const {
47 assert((Size % State.PageSize) == 0);
48 void *Ptr = mmap(nullptr, Size, PROT_READ | PROT_WRITE,
49 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
50 checkWithErrorCode(Ptr != MAP_FAILED,
51 "Failed to map guarded pool allocator memory", errno);
52 MaybeSetMappingName(Ptr, Size, Name);
53 return Ptr;
54 }
55
unmap(void * Ptr,size_t Size) const56 void GuardedPoolAllocator::unmap(void *Ptr, size_t Size) const {
57 assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0);
58 assert((Size % State.PageSize) == 0);
59 checkWithErrorCode(munmap(Ptr, Size) == 0,
60 "Failed to unmap guarded pool allocator memory.", errno);
61 }
62
reserveGuardedPool(size_t Size)63 void *GuardedPoolAllocator::reserveGuardedPool(size_t Size) {
64 assert((Size % State.PageSize) == 0);
65 void *Ptr =
66 mmap(nullptr, Size, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
67 checkWithErrorCode(Ptr != MAP_FAILED,
68 "Failed to reserve guarded pool allocator memory", errno);
69 MaybeSetMappingName(Ptr, Size, kGwpAsanGuardPageName);
70 return Ptr;
71 }
72
unreserveGuardedPool()73 void GuardedPoolAllocator::unreserveGuardedPool() {
74 unmap(reinterpret_cast<void *>(State.GuardedPagePool),
75 State.GuardedPagePoolEnd - State.GuardedPagePool);
76 }
77
allocateInGuardedPool(void * Ptr,size_t Size) const78 void GuardedPoolAllocator::allocateInGuardedPool(void *Ptr, size_t Size) const {
79 assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0);
80 assert((Size % State.PageSize) == 0);
81 checkWithErrorCode(mprotect(Ptr, Size, PROT_READ | PROT_WRITE) == 0,
82 "Failed to allocate in guarded pool allocator memory",
83 errno);
84 MaybeSetMappingName(Ptr, Size, kGwpAsanAliveSlotName);
85 }
86
deallocateInGuardedPool(void * Ptr,size_t Size) const87 void GuardedPoolAllocator::deallocateInGuardedPool(void *Ptr,
88 size_t Size) const {
89 assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0);
90 assert((Size % State.PageSize) == 0);
91 // mmap() a PROT_NONE page over the address to release it to the system, if
92 // we used mprotect() here the system would count pages in the quarantine
93 // against the RSS.
94 checkWithErrorCode(
95 mmap(Ptr, Size, PROT_NONE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1,
96 0) != MAP_FAILED,
97 "Failed to deallocate in guarded pool allocator memory", errno);
98 MaybeSetMappingName(Ptr, Size, kGwpAsanGuardPageName);
99 }
100
getPlatformPageSize()101 size_t GuardedPoolAllocator::getPlatformPageSize() {
102 return sysconf(_SC_PAGESIZE);
103 }
104
installAtFork()105 void GuardedPoolAllocator::installAtFork() {
106 static bool AtForkInstalled = false;
107 if (AtForkInstalled)
108 return;
109 AtForkInstalled = true;
110 auto Disable = []() {
111 if (auto *S = getSingleton())
112 S->disable();
113 };
114 auto Enable = []() {
115 if (auto *S = getSingleton())
116 S->enable();
117 };
118 pthread_atfork(Disable, Enable, Enable);
119 }
120 } // namespace gwp_asan
121