1 //===-- hwasan_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 /// \file 10 /// This file is a part of HWAddressSanitizer and contains Linux-, NetBSD- and 11 /// FreeBSD-specific code. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #include "sanitizer_common/sanitizer_platform.h" 16 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD 17 18 #include "hwasan.h" 19 #include "hwasan_dynamic_shadow.h" 20 #include "hwasan_interface_internal.h" 21 #include "hwasan_mapping.h" 22 #include "hwasan_report.h" 23 #include "hwasan_thread.h" 24 #include "hwasan_thread_list.h" 25 26 #include <dlfcn.h> 27 #include <elf.h> 28 #include <link.h> 29 #include <pthread.h> 30 #include <signal.h> 31 #include <stdio.h> 32 #include <stdlib.h> 33 #include <sys/resource.h> 34 #include <sys/time.h> 35 #include <unistd.h> 36 #include <unwind.h> 37 #include <sys/prctl.h> 38 #include <errno.h> 39 40 #include "sanitizer_common/sanitizer_common.h" 41 #include "sanitizer_common/sanitizer_procmaps.h" 42 43 // Configurations of HWASAN_WITH_INTERCEPTORS and SANITIZER_ANDROID. 44 // 45 // HWASAN_WITH_INTERCEPTORS=OFF, SANITIZER_ANDROID=OFF 46 // Not currently tested. 47 // HWASAN_WITH_INTERCEPTORS=OFF, SANITIZER_ANDROID=ON 48 // Integration tests downstream exist. 49 // HWASAN_WITH_INTERCEPTORS=ON, SANITIZER_ANDROID=OFF 50 // Tested with check-hwasan on x86_64-linux. 51 // HWASAN_WITH_INTERCEPTORS=ON, SANITIZER_ANDROID=ON 52 // Tested with check-hwasan on aarch64-linux-android. 53 #if !SANITIZER_ANDROID 54 SANITIZER_INTERFACE_ATTRIBUTE 55 THREADLOCAL uptr __hwasan_tls; 56 #endif 57 58 namespace __hwasan { 59 60 // With the zero shadow base we can not actually map pages starting from 0. 61 // This constant is somewhat arbitrary. 62 constexpr uptr kZeroBaseShadowStart = 0; 63 constexpr uptr kZeroBaseMaxShadowStart = 1 << 18; 64 65 static void ProtectGap(uptr addr, uptr size) { 66 __sanitizer::ProtectGap(addr, size, kZeroBaseShadowStart, 67 kZeroBaseMaxShadowStart); 68 } 69 70 uptr kLowMemStart; 71 uptr kLowMemEnd; 72 uptr kLowShadowEnd; 73 uptr kLowShadowStart; 74 uptr kHighShadowStart; 75 uptr kHighShadowEnd; 76 uptr kHighMemStart; 77 uptr kHighMemEnd; 78 79 uptr kAliasRegionStart; // Always 0 on non-x86. 80 81 static void PrintRange(uptr start, uptr end, const char *name) { 82 Printf("|| [%p, %p] || %.*s ||\n", (void *)start, (void *)end, 10, name); 83 } 84 85 static void PrintAddressSpaceLayout() { 86 PrintRange(kHighMemStart, kHighMemEnd, "HighMem"); 87 if (kHighShadowEnd + 1 < kHighMemStart) 88 PrintRange(kHighShadowEnd + 1, kHighMemStart - 1, "ShadowGap"); 89 else 90 CHECK_EQ(kHighShadowEnd + 1, kHighMemStart); 91 PrintRange(kHighShadowStart, kHighShadowEnd, "HighShadow"); 92 if (kLowShadowEnd + 1 < kHighShadowStart) 93 PrintRange(kLowShadowEnd + 1, kHighShadowStart - 1, "ShadowGap"); 94 else 95 CHECK_EQ(kLowMemEnd + 1, kHighShadowStart); 96 PrintRange(kLowShadowStart, kLowShadowEnd, "LowShadow"); 97 if (kLowMemEnd + 1 < kLowShadowStart) 98 PrintRange(kLowMemEnd + 1, kLowShadowStart - 1, "ShadowGap"); 99 else 100 CHECK_EQ(kLowMemEnd + 1, kLowShadowStart); 101 PrintRange(kLowMemStart, kLowMemEnd, "LowMem"); 102 CHECK_EQ(0, kLowMemStart); 103 } 104 105 static uptr GetHighMemEnd() { 106 // HighMem covers the upper part of the address space. 107 uptr max_address = GetMaxUserVirtualAddress(); 108 // Adjust max address to make sure that kHighMemEnd and kHighMemStart are 109 // properly aligned: 110 max_address |= (GetMmapGranularity() << kShadowScale) - 1; 111 return max_address; 112 } 113 114 static void InitializeShadowBaseAddress(uptr shadow_size_bytes) { 115 __hwasan_shadow_memory_dynamic_address = 116 FindDynamicShadowStart(shadow_size_bytes); 117 } 118 119 void InitPrctl() { 120 #define PR_SET_TAGGED_ADDR_CTRL 55 121 #define PR_GET_TAGGED_ADDR_CTRL 56 122 #define PR_TAGGED_ADDR_ENABLE (1UL << 0) 123 // Check we're running on a kernel that can use the tagged address ABI. 124 int local_errno = 0; 125 if (internal_iserror(internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0), 126 &local_errno) && 127 local_errno == EINVAL) { 128 #if SANITIZER_ANDROID || defined(__x86_64__) 129 // Some older Android kernels have the tagged pointer ABI on 130 // unconditionally, and hence don't have the tagged-addr prctl while still 131 // allow the ABI. 132 // If targeting Android and the prctl is not around we assume this is the 133 // case. 134 return; 135 #else 136 if (flags()->fail_without_syscall_abi) { 137 Printf( 138 "FATAL: " 139 "HWAddressSanitizer requires a kernel with tagged address ABI.\n"); 140 Die(); 141 } 142 #endif 143 } 144 145 // Turn on the tagged address ABI. 146 if ((internal_iserror(internal_prctl(PR_SET_TAGGED_ADDR_CTRL, 147 PR_TAGGED_ADDR_ENABLE, 0, 0, 0)) || 148 !internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0)) && 149 flags()->fail_without_syscall_abi) { 150 Printf( 151 "FATAL: HWAddressSanitizer failed to enable tagged address syscall " 152 "ABI.\nSuggest check `sysctl abi.tagged_addr_disabled` " 153 "configuration.\n"); 154 Die(); 155 } 156 #undef PR_SET_TAGGED_ADDR_CTRL 157 #undef PR_GET_TAGGED_ADDR_CTRL 158 #undef PR_TAGGED_ADDR_ENABLE 159 } 160 161 bool InitShadow() { 162 // Define the entire memory range. 163 kHighMemEnd = GetHighMemEnd(); 164 165 // Determine shadow memory base offset. 166 InitializeShadowBaseAddress(MemToShadowSize(kHighMemEnd)); 167 168 // Place the low memory first. 169 kLowMemEnd = __hwasan_shadow_memory_dynamic_address - 1; 170 kLowMemStart = 0; 171 172 // Define the low shadow based on the already placed low memory. 173 kLowShadowEnd = MemToShadow(kLowMemEnd); 174 kLowShadowStart = __hwasan_shadow_memory_dynamic_address; 175 176 // High shadow takes whatever memory is left up there (making sure it is not 177 // interfering with low memory in the fixed case). 178 kHighShadowEnd = MemToShadow(kHighMemEnd); 179 kHighShadowStart = Max(kLowMemEnd, MemToShadow(kHighShadowEnd)) + 1; 180 181 // High memory starts where allocated shadow allows. 182 kHighMemStart = ShadowToMem(kHighShadowStart); 183 184 #if defined(__x86_64__) 185 constexpr uptr kAliasRegionOffset = 1ULL << (kTaggableRegionCheckShift - 1); 186 kAliasRegionStart = 187 __hwasan_shadow_memory_dynamic_address + kAliasRegionOffset; 188 189 CHECK_EQ(kAliasRegionStart >> kTaggableRegionCheckShift, 190 __hwasan_shadow_memory_dynamic_address >> kTaggableRegionCheckShift); 191 CHECK_EQ( 192 (kAliasRegionStart + kAliasRegionOffset - 1) >> kTaggableRegionCheckShift, 193 __hwasan_shadow_memory_dynamic_address >> kTaggableRegionCheckShift); 194 #endif 195 196 // Check the sanity of the defined memory ranges (there might be gaps). 197 CHECK_EQ(kHighMemStart % GetMmapGranularity(), 0); 198 CHECK_GT(kHighMemStart, kHighShadowEnd); 199 CHECK_GT(kHighShadowEnd, kHighShadowStart); 200 CHECK_GT(kHighShadowStart, kLowMemEnd); 201 CHECK_GT(kLowMemEnd, kLowMemStart); 202 CHECK_GT(kLowShadowEnd, kLowShadowStart); 203 CHECK_GT(kLowShadowStart, kLowMemEnd); 204 205 if (Verbosity()) 206 PrintAddressSpaceLayout(); 207 208 // Reserve shadow memory. 209 ReserveShadowMemoryRange(kLowShadowStart, kLowShadowEnd, "low shadow"); 210 ReserveShadowMemoryRange(kHighShadowStart, kHighShadowEnd, "high shadow"); 211 212 // Protect all the gaps. 213 ProtectGap(0, Min(kLowMemStart, kLowShadowStart)); 214 if (kLowMemEnd + 1 < kLowShadowStart) 215 ProtectGap(kLowMemEnd + 1, kLowShadowStart - kLowMemEnd - 1); 216 if (kLowShadowEnd + 1 < kHighShadowStart) 217 ProtectGap(kLowShadowEnd + 1, kHighShadowStart - kLowShadowEnd - 1); 218 if (kHighShadowEnd + 1 < kHighMemStart) 219 ProtectGap(kHighShadowEnd + 1, kHighMemStart - kHighShadowEnd - 1); 220 221 return true; 222 } 223 224 void InitThreads() { 225 CHECK(__hwasan_shadow_memory_dynamic_address); 226 uptr guard_page_size = GetMmapGranularity(); 227 uptr thread_space_start = 228 __hwasan_shadow_memory_dynamic_address - (1ULL << kShadowBaseAlignment); 229 uptr thread_space_end = 230 __hwasan_shadow_memory_dynamic_address - guard_page_size; 231 ReserveShadowMemoryRange(thread_space_start, thread_space_end - 1, 232 "hwasan threads", /*madvise_shadow*/ false); 233 ProtectGap(thread_space_end, 234 __hwasan_shadow_memory_dynamic_address - thread_space_end); 235 InitThreadList(thread_space_start, thread_space_end - thread_space_start); 236 } 237 238 bool MemIsApp(uptr p) { 239 #if !defined(__x86_64__) // Memory outside the alias range has non-zero tags. 240 CHECK(GetTagFromPointer(p) == 0); 241 #endif 242 return p >= kHighMemStart || (p >= kLowMemStart && p <= kLowMemEnd); 243 } 244 245 static void HwasanAtExit(void) { 246 if (common_flags()->print_module_map) 247 DumpProcessMap(); 248 if (flags()->print_stats && (flags()->atexit || hwasan_report_count > 0)) 249 ReportStats(); 250 if (hwasan_report_count > 0) { 251 // ReportAtExitStatistics(); 252 if (common_flags()->exitcode) 253 internal__exit(common_flags()->exitcode); 254 } 255 } 256 257 void InstallAtExitHandler() { 258 atexit(HwasanAtExit); 259 } 260 261 // ---------------------- TSD ---------------- {{{1 262 263 extern "C" void __hwasan_thread_enter() { 264 hwasanThreadList().CreateCurrentThread()->InitRandomState(); 265 } 266 267 extern "C" void __hwasan_thread_exit() { 268 Thread *t = GetCurrentThread(); 269 // Make sure that signal handler can not see a stale current thread pointer. 270 atomic_signal_fence(memory_order_seq_cst); 271 if (t) 272 hwasanThreadList().ReleaseThread(t); 273 } 274 275 #if HWASAN_WITH_INTERCEPTORS 276 static pthread_key_t tsd_key; 277 static bool tsd_key_inited = false; 278 279 void HwasanTSDThreadInit() { 280 if (tsd_key_inited) 281 CHECK_EQ(0, pthread_setspecific(tsd_key, 282 (void *)GetPthreadDestructorIterations())); 283 } 284 285 void HwasanTSDDtor(void *tsd) { 286 uptr iterations = (uptr)tsd; 287 if (iterations > 1) { 288 CHECK_EQ(0, pthread_setspecific(tsd_key, (void *)(iterations - 1))); 289 return; 290 } 291 __hwasan_thread_exit(); 292 } 293 294 void HwasanTSDInit() { 295 CHECK(!tsd_key_inited); 296 tsd_key_inited = true; 297 CHECK_EQ(0, pthread_key_create(&tsd_key, HwasanTSDDtor)); 298 } 299 #else 300 void HwasanTSDInit() {} 301 void HwasanTSDThreadInit() {} 302 #endif 303 304 #if SANITIZER_ANDROID 305 uptr *GetCurrentThreadLongPtr() { 306 return (uptr *)get_android_tls_ptr(); 307 } 308 #else 309 uptr *GetCurrentThreadLongPtr() { 310 return &__hwasan_tls; 311 } 312 #endif 313 314 #if SANITIZER_ANDROID 315 void AndroidTestTlsSlot() { 316 uptr kMagicValue = 0x010203040A0B0C0D; 317 uptr *tls_ptr = GetCurrentThreadLongPtr(); 318 uptr old_value = *tls_ptr; 319 *tls_ptr = kMagicValue; 320 dlerror(); 321 if (*(uptr *)get_android_tls_ptr() != kMagicValue) { 322 Printf( 323 "ERROR: Incompatible version of Android: TLS_SLOT_SANITIZER(6) is used " 324 "for dlerror().\n"); 325 Die(); 326 } 327 *tls_ptr = old_value; 328 } 329 #else 330 void AndroidTestTlsSlot() {} 331 #endif 332 333 Thread *GetCurrentThread() { 334 uptr *ThreadLongPtr = GetCurrentThreadLongPtr(); 335 if (UNLIKELY(*ThreadLongPtr == 0)) 336 return nullptr; 337 auto *R = (StackAllocationsRingBuffer *)ThreadLongPtr; 338 return hwasanThreadList().GetThreadByBufferAddress((uptr)R->Next()); 339 } 340 341 struct AccessInfo { 342 uptr addr; 343 uptr size; 344 bool is_store; 345 bool is_load; 346 bool recover; 347 }; 348 349 static AccessInfo GetAccessInfo(siginfo_t *info, ucontext_t *uc) { 350 // Access type is passed in a platform dependent way (see below) and encoded 351 // as 0xXY, where X&1 is 1 for store, 0 for load, and X&2 is 1 if the error is 352 // recoverable. Valid values of Y are 0 to 4, which are interpreted as 353 // log2(access_size), and 0xF, which means that access size is passed via 354 // platform dependent register (see below). 355 #if defined(__aarch64__) 356 // Access type is encoded in BRK immediate as 0x900 + 0xXY. For Y == 0xF, 357 // access size is stored in X1 register. Access address is always in X0 358 // register. 359 uptr pc = (uptr)info->si_addr; 360 const unsigned code = ((*(u32 *)pc) >> 5) & 0xffff; 361 if ((code & 0xff00) != 0x900) 362 return AccessInfo{}; // Not ours. 363 364 const bool is_store = code & 0x10; 365 const bool recover = code & 0x20; 366 const uptr addr = uc->uc_mcontext.regs[0]; 367 const unsigned size_log = code & 0xf; 368 if (size_log > 4 && size_log != 0xf) 369 return AccessInfo{}; // Not ours. 370 const uptr size = size_log == 0xf ? uc->uc_mcontext.regs[1] : 1U << size_log; 371 372 #elif defined(__x86_64__) 373 // Access type is encoded in the instruction following INT3 as 374 // NOP DWORD ptr [EAX + 0x40 + 0xXY]. For Y == 0xF, access size is stored in 375 // RSI register. Access address is always in RDI register. 376 uptr pc = (uptr)uc->uc_mcontext.gregs[REG_RIP]; 377 uint8_t *nop = (uint8_t*)pc; 378 if (*nop != 0x0f || *(nop + 1) != 0x1f || *(nop + 2) != 0x40 || 379 *(nop + 3) < 0x40) 380 return AccessInfo{}; // Not ours. 381 const unsigned code = *(nop + 3); 382 383 const bool is_store = code & 0x10; 384 const bool recover = code & 0x20; 385 const uptr addr = uc->uc_mcontext.gregs[REG_RDI]; 386 const unsigned size_log = code & 0xf; 387 if (size_log > 4 && size_log != 0xf) 388 return AccessInfo{}; // Not ours. 389 const uptr size = 390 size_log == 0xf ? uc->uc_mcontext.gregs[REG_RSI] : 1U << size_log; 391 392 #else 393 # error Unsupported architecture 394 #endif 395 396 return AccessInfo{addr, size, is_store, !is_store, recover}; 397 } 398 399 static void HandleTagMismatch(AccessInfo ai, uptr pc, uptr frame, 400 ucontext_t *uc, uptr *registers_frame = nullptr) { 401 InternalMmapVector<BufferedStackTrace> stack_buffer(1); 402 BufferedStackTrace *stack = stack_buffer.data(); 403 stack->Reset(); 404 stack->Unwind(pc, frame, uc, common_flags()->fast_unwind_on_fatal); 405 406 // The second stack frame contains the failure __hwasan_check function, as 407 // we have a stack frame for the registers saved in __hwasan_tag_mismatch that 408 // we wish to ignore. This (currently) only occurs on AArch64, as x64 409 // implementations use SIGTRAP to implement the failure, and thus do not go 410 // through the stack saver. 411 if (registers_frame && stack->trace && stack->size > 0) { 412 stack->trace++; 413 stack->size--; 414 } 415 416 bool fatal = flags()->halt_on_error || !ai.recover; 417 ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store, fatal, 418 registers_frame); 419 } 420 421 static bool HwasanOnSIGTRAP(int signo, siginfo_t *info, ucontext_t *uc) { 422 AccessInfo ai = GetAccessInfo(info, uc); 423 if (!ai.is_store && !ai.is_load) 424 return false; 425 426 SignalContext sig{info, uc}; 427 HandleTagMismatch(ai, StackTrace::GetNextInstructionPc(sig.pc), sig.bp, uc); 428 429 #if defined(__aarch64__) 430 uc->uc_mcontext.pc += 4; 431 #elif defined(__x86_64__) 432 #else 433 # error Unsupported architecture 434 #endif 435 return true; 436 } 437 438 static void OnStackUnwind(const SignalContext &sig, const void *, 439 BufferedStackTrace *stack) { 440 stack->Unwind(StackTrace::GetNextInstructionPc(sig.pc), sig.bp, sig.context, 441 common_flags()->fast_unwind_on_fatal); 442 } 443 444 void HwasanOnDeadlySignal(int signo, void *info, void *context) { 445 // Probably a tag mismatch. 446 if (signo == SIGTRAP) 447 if (HwasanOnSIGTRAP(signo, (siginfo_t *)info, (ucontext_t*)context)) 448 return; 449 450 HandleDeadlySignal(info, context, GetTid(), &OnStackUnwind, nullptr); 451 } 452 453 454 } // namespace __hwasan 455 456 // Entry point for interoperability between __hwasan_tag_mismatch (ASM) and the 457 // rest of the mismatch handling code (C++). 458 void __hwasan_tag_mismatch4(uptr addr, uptr access_info, uptr *registers_frame, 459 size_t outsize) { 460 __hwasan::AccessInfo ai; 461 ai.is_store = access_info & 0x10; 462 ai.is_load = !ai.is_store; 463 ai.recover = access_info & 0x20; 464 ai.addr = addr; 465 if ((access_info & 0xf) == 0xf) 466 ai.size = outsize; 467 else 468 ai.size = 1 << (access_info & 0xf); 469 470 __hwasan::HandleTagMismatch(ai, (uptr)__builtin_return_address(0), 471 (uptr)__builtin_frame_address(0), nullptr, 472 registers_frame); 473 __builtin_unreachable(); 474 } 475 476 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD 477