Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 1 | //===-- linux.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 "platform.h" |
| 10 | |
| 11 | #if SCUDO_LINUX |
| 12 | |
| 13 | #include "common.h" |
| 14 | #include "linux.h" |
| 15 | #include "mutex.h" |
| 16 | #include "string_utils.h" |
| 17 | |
| 18 | #include <errno.h> |
| 19 | #include <fcntl.h> |
| 20 | #include <linux/futex.h> |
| 21 | #include <sched.h> |
| 22 | #include <stdlib.h> |
| 23 | #include <string.h> |
| 24 | #include <sys/mman.h> |
| 25 | #include <sys/stat.h> |
| 26 | #include <sys/syscall.h> |
| 27 | #include <sys/time.h> |
| 28 | #include <time.h> |
| 29 | #include <unistd.h> |
| 30 | |
| 31 | #if SCUDO_ANDROID |
| 32 | #include <sys/prctl.h> |
| 33 | // Definitions of prctl arguments to set a vma name in Android kernels. |
| 34 | #define ANDROID_PR_SET_VMA 0x53564d41 |
| 35 | #define ANDROID_PR_SET_VMA_ANON_NAME 0 |
| 36 | #endif |
| 37 | |
| 38 | namespace scudo { |
| 39 | |
| 40 | uptr getPageSize() { return static_cast<uptr>(sysconf(_SC_PAGESIZE)); } |
| 41 | |
| 42 | void NORETURN die() { abort(); } |
| 43 | |
| 44 | void *map(void *Addr, uptr Size, UNUSED const char *Name, uptr Flags, |
| 45 | UNUSED MapPlatformData *Data) { |
| 46 | int MmapFlags = MAP_PRIVATE | MAP_ANONYMOUS; |
| 47 | int MmapProt; |
| 48 | if (Flags & MAP_NOACCESS) { |
| 49 | MmapFlags |= MAP_NORESERVE; |
| 50 | MmapProt = PROT_NONE; |
| 51 | } else { |
| 52 | MmapProt = PROT_READ | PROT_WRITE; |
Peter Collingbourne | cc3d493 | 2020-12-21 18:39:03 -0800 | [diff] [blame] | 53 | } |
Peter Collingbourne | 9ece409 | 2020-12-17 21:02:01 -0800 | [diff] [blame] | 54 | #if defined(__aarch64__) |
| 55 | #ifndef PROT_MTE |
| 56 | #define PROT_MTE 0x20 |
| 57 | #endif |
Peter Collingbourne | cc3d493 | 2020-12-21 18:39:03 -0800 | [diff] [blame] | 58 | if (Flags & MAP_MEMTAG) |
| 59 | MmapProt |= PROT_MTE; |
Dynamic Tools Team | 48429c7 | 2019-12-04 17:46:15 -0800 | [diff] [blame] | 60 | #endif |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 61 | if (Addr) { |
| 62 | // Currently no scenario for a noaccess mapping with a fixed address. |
| 63 | DCHECK_EQ(Flags & MAP_NOACCESS, 0); |
| 64 | MmapFlags |= MAP_FIXED; |
| 65 | } |
| 66 | void *P = mmap(Addr, Size, MmapProt, MmapFlags, -1, 0); |
| 67 | if (P == MAP_FAILED) { |
| 68 | if (!(Flags & MAP_ALLOWNOMEM) || errno != ENOMEM) |
Kostya Kortchinsky | c79ab1b | 2021-05-24 09:26:21 -0700 | [diff] [blame] | 69 | dieOnMapUnmapError(errno == ENOMEM ? Size : 0); |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 70 | return nullptr; |
| 71 | } |
| 72 | #if SCUDO_ANDROID |
Peter Collingbourne | cc3d493 | 2020-12-21 18:39:03 -0800 | [diff] [blame] | 73 | if (Name) |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 74 | prctl(ANDROID_PR_SET_VMA, ANDROID_PR_SET_VMA_ANON_NAME, P, Size, Name); |
| 75 | #endif |
| 76 | return P; |
| 77 | } |
| 78 | |
| 79 | void unmap(void *Addr, uptr Size, UNUSED uptr Flags, |
| 80 | UNUSED MapPlatformData *Data) { |
| 81 | if (munmap(Addr, Size) != 0) |
| 82 | dieOnMapUnmapError(); |
| 83 | } |
| 84 | |
Peter Collingbourne | cc3d493 | 2020-12-21 18:39:03 -0800 | [diff] [blame] | 85 | void setMemoryPermission(uptr Addr, uptr Size, uptr Flags, |
| 86 | UNUSED MapPlatformData *Data) { |
| 87 | int Prot = (Flags & MAP_NOACCESS) ? PROT_NONE : (PROT_READ | PROT_WRITE); |
| 88 | if (mprotect(reinterpret_cast<void *>(Addr), Size, Prot) != 0) |
| 89 | dieOnMapUnmapError(); |
| 90 | } |
| 91 | |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 92 | void releasePagesToOS(uptr BaseAddress, uptr Offset, uptr Size, |
| 93 | UNUSED MapPlatformData *Data) { |
| 94 | void *Addr = reinterpret_cast<void *>(BaseAddress + Offset); |
Vitaly Buka | 6c5c1bb | 2021-05-28 01:53:42 -0700 | [diff] [blame^] | 95 | |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 96 | while (madvise(Addr, Size, MADV_DONTNEED) == -1 && errno == EAGAIN) { |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | // Calling getenv should be fine (c)(tm) at any time. |
| 101 | const char *getEnv(const char *Name) { return getenv(Name); } |
| 102 | |
| 103 | namespace { |
| 104 | enum State : u32 { Unlocked = 0, Locked = 1, Sleeping = 2 }; |
| 105 | } |
| 106 | |
| 107 | bool HybridMutex::tryLock() { |
| 108 | return atomic_compare_exchange(&M, Unlocked, Locked) == Unlocked; |
| 109 | } |
| 110 | |
| 111 | // The following is based on https://akkadia.org/drepper/futex.pdf. |
| 112 | void HybridMutex::lockSlow() { |
| 113 | u32 V = atomic_compare_exchange(&M, Unlocked, Locked); |
| 114 | if (V == Unlocked) |
| 115 | return; |
| 116 | if (V != Sleeping) |
| 117 | V = atomic_exchange(&M, Sleeping, memory_order_acquire); |
| 118 | while (V != Unlocked) { |
| 119 | syscall(SYS_futex, reinterpret_cast<uptr>(&M), FUTEX_WAIT_PRIVATE, Sleeping, |
| 120 | nullptr, nullptr, 0); |
| 121 | V = atomic_exchange(&M, Sleeping, memory_order_acquire); |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | void HybridMutex::unlock() { |
| 126 | if (atomic_fetch_sub(&M, 1U, memory_order_release) != Locked) { |
| 127 | atomic_store(&M, Unlocked, memory_order_release); |
| 128 | syscall(SYS_futex, reinterpret_cast<uptr>(&M), FUTEX_WAKE_PRIVATE, 1, |
| 129 | nullptr, nullptr, 0); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | u64 getMonotonicTime() { |
| 134 | timespec TS; |
| 135 | clock_gettime(CLOCK_MONOTONIC, &TS); |
| 136 | return static_cast<u64>(TS.tv_sec) * (1000ULL * 1000 * 1000) + |
| 137 | static_cast<u64>(TS.tv_nsec); |
| 138 | } |
| 139 | |
| 140 | u32 getNumberOfCPUs() { |
| 141 | cpu_set_t CPUs; |
Dynamic Tools Team | 7fef730 | 2020-01-20 09:50:22 -0800 | [diff] [blame] | 142 | // sched_getaffinity can fail for a variety of legitimate reasons (lack of |
| 143 | // CAP_SYS_NICE, syscall filtering, etc), in which case we shall return 0. |
| 144 | if (sched_getaffinity(0, sizeof(cpu_set_t), &CPUs) != 0) |
| 145 | return 0; |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 146 | return static_cast<u32>(CPU_COUNT(&CPUs)); |
| 147 | } |
| 148 | |
Dynamic Tools Team | 0d7d2ae | 2020-04-21 15:30:50 -0700 | [diff] [blame] | 149 | u32 getThreadID() { |
| 150 | #if SCUDO_ANDROID |
| 151 | return static_cast<u32>(gettid()); |
| 152 | #else |
| 153 | return static_cast<u32>(syscall(SYS_gettid)); |
| 154 | #endif |
| 155 | } |
| 156 | |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 157 | // Blocking is possibly unused if the getrandom block is not compiled in. |
| 158 | bool getRandom(void *Buffer, uptr Length, UNUSED bool Blocking) { |
| 159 | if (!Buffer || !Length || Length > MaxRandomLength) |
| 160 | return false; |
| 161 | ssize_t ReadBytes; |
| 162 | #if defined(SYS_getrandom) |
| 163 | #if !defined(GRND_NONBLOCK) |
| 164 | #define GRND_NONBLOCK 1 |
| 165 | #endif |
| 166 | // Up to 256 bytes, getrandom will not be interrupted. |
| 167 | ReadBytes = |
| 168 | syscall(SYS_getrandom, Buffer, Length, Blocking ? 0 : GRND_NONBLOCK); |
| 169 | if (ReadBytes == static_cast<ssize_t>(Length)) |
| 170 | return true; |
| 171 | #endif // defined(SYS_getrandom) |
| 172 | // Up to 256 bytes, a read off /dev/urandom will not be interrupted. |
| 173 | // Blocking is moot here, O_NONBLOCK has no effect when opening /dev/urandom. |
| 174 | const int FileDesc = open("/dev/urandom", O_RDONLY); |
| 175 | if (FileDesc == -1) |
| 176 | return false; |
| 177 | ReadBytes = read(FileDesc, Buffer, Length); |
| 178 | close(FileDesc); |
| 179 | return (ReadBytes == static_cast<ssize_t>(Length)); |
| 180 | } |
| 181 | |
Dynamic Tools Team | 0f81190 | 2020-01-28 09:38:59 -0800 | [diff] [blame] | 182 | // Allocation free syslog-like API. |
| 183 | extern "C" WEAK int async_safe_write_log(int pri, const char *tag, |
| 184 | const char *msg); |
| 185 | |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 186 | void outputRaw(const char *Buffer) { |
Dynamic Tools Team | 0f81190 | 2020-01-28 09:38:59 -0800 | [diff] [blame] | 187 | if (&async_safe_write_log) { |
| 188 | constexpr s32 AndroidLogInfo = 4; |
Dynamic Tools Team | ee9ca98 | 2020-04-13 07:25:35 -0700 | [diff] [blame] | 189 | constexpr uptr MaxLength = 1024U; |
| 190 | char LocalBuffer[MaxLength]; |
| 191 | while (strlen(Buffer) > MaxLength) { |
| 192 | uptr P; |
| 193 | for (P = MaxLength - 1; P > 0; P--) { |
| 194 | if (Buffer[P] == '\n') { |
| 195 | memcpy(LocalBuffer, Buffer, P); |
| 196 | LocalBuffer[P] = '\0'; |
| 197 | async_safe_write_log(AndroidLogInfo, "scudo", LocalBuffer); |
| 198 | Buffer = &Buffer[P + 1]; |
| 199 | break; |
| 200 | } |
| 201 | } |
| 202 | // If no newline was found, just log the buffer. |
| 203 | if (P == 0) |
| 204 | break; |
| 205 | } |
Dynamic Tools Team | 0f81190 | 2020-01-28 09:38:59 -0800 | [diff] [blame] | 206 | async_safe_write_log(AndroidLogInfo, "scudo", Buffer); |
| 207 | } else { |
Fangrui Song | 6712ba9 | 2020-10-12 09:57:12 -0700 | [diff] [blame] | 208 | (void)write(2, Buffer, strlen(Buffer)); |
Dynamic Tools Team | 0f81190 | 2020-01-28 09:38:59 -0800 | [diff] [blame] | 209 | } |
Dynamic Tools Team | 517193e | 2019-09-11 14:48:41 +0000 | [diff] [blame] | 210 | } |
| 211 | |
| 212 | extern "C" WEAK void android_set_abort_message(const char *); |
| 213 | |
| 214 | void setAbortMessage(const char *Message) { |
| 215 | if (&android_set_abort_message) |
| 216 | android_set_abort_message(Message); |
| 217 | } |
| 218 | |
| 219 | } // namespace scudo |
| 220 | |
| 221 | #endif // SCUDO_LINUX |