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 kHighMemStart; 73 uptr kHighMemEnd; 74 75 static void PrintRange(uptr start, uptr end, const char *name) { 76 Printf("|| [%p, %p] || %.*s ||\n", (void *)start, (void *)end, 10, name); 77 } 78 79 static void PrintAddressSpaceLayout() { 80 PrintRange(kHighMemStart, kHighMemEnd, "HighMem"); 81 if (kHighShadowEnd + 1 < kHighMemStart) 82 PrintRange(kHighShadowEnd + 1, kHighMemStart - 1, "ShadowGap"); 83 else 84 CHECK_EQ(kHighShadowEnd + 1, kHighMemStart); 85 PrintRange(kHighShadowStart, kHighShadowEnd, "HighShadow"); 86 if (kLowShadowEnd + 1 < kHighShadowStart) 87 PrintRange(kLowShadowEnd + 1, kHighShadowStart - 1, "ShadowGap"); 88 else 89 CHECK_EQ(kLowMemEnd + 1, kHighShadowStart); 90 PrintRange(kLowShadowStart, kLowShadowEnd, "LowShadow"); 91 if (kLowMemEnd + 1 < kLowShadowStart) 92 PrintRange(kLowMemEnd + 1, kLowShadowStart - 1, "ShadowGap"); 93 else 94 CHECK_EQ(kLowMemEnd + 1, kLowShadowStart); 95 PrintRange(kLowMemStart, kLowMemEnd, "LowMem"); 96 CHECK_EQ(0, kLowMemStart); 97 } 98 99 static uptr GetHighMemEnd() { 100 // HighMem covers the upper part of the address space. 101 uptr max_address = GetMaxUserVirtualAddress(); 102 // Adjust max address to make sure that kHighMemEnd and kHighMemStart are 103 // properly aligned: 104 max_address |= (GetMmapGranularity() << kShadowScale) - 1; 105 return max_address; 106 } 107 108 static void InitializeShadowBaseAddress(uptr shadow_size_bytes) { 109 __hwasan_shadow_memory_dynamic_address = 110 FindDynamicShadowStart(shadow_size_bytes); 111 } 112 113 void InitializeOsSupport() { 114 #define PR_SET_TAGGED_ADDR_CTRL 55 115 #define PR_GET_TAGGED_ADDR_CTRL 56 116 #define PR_TAGGED_ADDR_ENABLE (1UL << 0) 117 // Check we're running on a kernel that can use the tagged address ABI. 118 int local_errno = 0; 119 if (internal_iserror(internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0), 120 &local_errno) && 121 local_errno == EINVAL) { 122 # if SANITIZER_ANDROID || defined(HWASAN_ALIASING_MODE) 123 // Some older Android kernels have the tagged pointer ABI on 124 // unconditionally, and hence don't have the tagged-addr prctl while still 125 // allow the ABI. 126 // If targeting Android and the prctl is not around we assume this is the 127 // case. 128 return; 129 # else 130 if (flags()->fail_without_syscall_abi) { 131 Printf( 132 "FATAL: " 133 "HWAddressSanitizer requires a kernel with tagged address ABI.\n"); 134 Die(); 135 } 136 # endif 137 } 138 139 // Turn on the tagged address ABI. 140 if ((internal_iserror(internal_prctl(PR_SET_TAGGED_ADDR_CTRL, 141 PR_TAGGED_ADDR_ENABLE, 0, 0, 0)) || 142 !internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0))) { 143 # if defined(__x86_64__) && !defined(HWASAN_ALIASING_MODE) 144 // Try the new prctl API for Intel LAM. The API is based on a currently 145 // unsubmitted patch to the Linux kernel (as of May 2021) and is thus 146 // subject to change. Patch is here: 147 // https://lore.kernel.org/linux-mm/20210205151631.43511-12-kirill.shutemov@linux.intel.com/ 148 int tag_bits = kTagBits; 149 int tag_shift = kAddressTagShift; 150 if (!internal_iserror( 151 internal_prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 152 reinterpret_cast<unsigned long>(&tag_bits), 153 reinterpret_cast<unsigned long>(&tag_shift), 0))) { 154 CHECK_EQ(tag_bits, kTagBits); 155 CHECK_EQ(tag_shift, kAddressTagShift); 156 return; 157 } 158 # endif // defined(__x86_64__) && !defined(HWASAN_ALIASING_MODE) 159 if (flags()->fail_without_syscall_abi) { 160 Printf( 161 "FATAL: HWAddressSanitizer failed to enable tagged address syscall " 162 "ABI.\nSuggest check `sysctl abi.tagged_addr_disabled` " 163 "configuration.\n"); 164 Die(); 165 } 166 } 167 #undef PR_SET_TAGGED_ADDR_CTRL 168 #undef PR_GET_TAGGED_ADDR_CTRL 169 #undef PR_TAGGED_ADDR_ENABLE 170 } 171 172 bool InitShadow() { 173 // Define the entire memory range. 174 kHighMemEnd = GetHighMemEnd(); 175 176 // Determine shadow memory base offset. 177 InitializeShadowBaseAddress(MemToShadowSize(kHighMemEnd)); 178 179 // Place the low memory first. 180 kLowMemEnd = __hwasan_shadow_memory_dynamic_address - 1; 181 kLowMemStart = 0; 182 183 // Define the low shadow based on the already placed low memory. 184 kLowShadowEnd = MemToShadow(kLowMemEnd); 185 kLowShadowStart = __hwasan_shadow_memory_dynamic_address; 186 187 // High shadow takes whatever memory is left up there (making sure it is not 188 // interfering with low memory in the fixed case). 189 kHighShadowEnd = MemToShadow(kHighMemEnd); 190 kHighShadowStart = Max(kLowMemEnd, MemToShadow(kHighShadowEnd)) + 1; 191 192 // High memory starts where allocated shadow allows. 193 kHighMemStart = ShadowToMem(kHighShadowStart); 194 195 // Check the sanity of the defined memory ranges (there might be gaps). 196 CHECK_EQ(kHighMemStart % GetMmapGranularity(), 0); 197 CHECK_GT(kHighMemStart, kHighShadowEnd); 198 CHECK_GT(kHighShadowEnd, kHighShadowStart); 199 CHECK_GT(kHighShadowStart, kLowMemEnd); 200 CHECK_GT(kLowMemEnd, kLowMemStart); 201 CHECK_GT(kLowShadowEnd, kLowShadowStart); 202 CHECK_GT(kLowShadowStart, kLowMemEnd); 203 204 if (Verbosity()) 205 PrintAddressSpaceLayout(); 206 207 // Reserve shadow memory. 208 ReserveShadowMemoryRange(kLowShadowStart, kLowShadowEnd, "low shadow"); 209 ReserveShadowMemoryRange(kHighShadowStart, kHighShadowEnd, "high shadow"); 210 211 // Protect all the gaps. 212 ProtectGap(0, Min(kLowMemStart, kLowShadowStart)); 213 if (kLowMemEnd + 1 < kLowShadowStart) 214 ProtectGap(kLowMemEnd + 1, kLowShadowStart - kLowMemEnd - 1); 215 if (kLowShadowEnd + 1 < kHighShadowStart) 216 ProtectGap(kLowShadowEnd + 1, kHighShadowStart - kLowShadowEnd - 1); 217 if (kHighShadowEnd + 1 < kHighMemStart) 218 ProtectGap(kHighShadowEnd + 1, kHighMemStart - kHighShadowEnd - 1); 219 220 return true; 221 } 222 223 void InitThreads() { 224 CHECK(__hwasan_shadow_memory_dynamic_address); 225 uptr guard_page_size = GetMmapGranularity(); 226 uptr thread_space_start = 227 __hwasan_shadow_memory_dynamic_address - (1ULL << kShadowBaseAlignment); 228 uptr thread_space_end = 229 __hwasan_shadow_memory_dynamic_address - guard_page_size; 230 ReserveShadowMemoryRange(thread_space_start, thread_space_end - 1, 231 "hwasan threads", /*madvise_shadow*/ false); 232 ProtectGap(thread_space_end, 233 __hwasan_shadow_memory_dynamic_address - thread_space_end); 234 InitThreadList(thread_space_start, thread_space_end - thread_space_start); 235 hwasanThreadList().CreateCurrentThread(); 236 } 237 238 bool MemIsApp(uptr p) { 239 // Memory outside the alias range has non-zero tags. 240 # if !defined(HWASAN_ALIASING_MODE) 241 CHECK(GetTagFromPointer(p) == 0); 242 # endif 243 244 return p >= kHighMemStart || (p >= kLowMemStart && p <= kLowMemEnd); 245 } 246 247 void InstallAtExitHandler() { 248 atexit(HwasanAtExit); 249 } 250 251 // ---------------------- TSD ---------------- {{{1 252 253 extern "C" void __hwasan_thread_enter() { 254 hwasanThreadList().CreateCurrentThread()->InitRandomState(); 255 } 256 257 extern "C" void __hwasan_thread_exit() { 258 Thread *t = GetCurrentThread(); 259 // Make sure that signal handler can not see a stale current thread pointer. 260 atomic_signal_fence(memory_order_seq_cst); 261 if (t) 262 hwasanThreadList().ReleaseThread(t); 263 } 264 265 #if HWASAN_WITH_INTERCEPTORS 266 static pthread_key_t tsd_key; 267 static bool tsd_key_inited = false; 268 269 void HwasanTSDThreadInit() { 270 if (tsd_key_inited) 271 CHECK_EQ(0, pthread_setspecific(tsd_key, 272 (void *)GetPthreadDestructorIterations())); 273 } 274 275 void HwasanTSDDtor(void *tsd) { 276 uptr iterations = (uptr)tsd; 277 if (iterations > 1) { 278 CHECK_EQ(0, pthread_setspecific(tsd_key, (void *)(iterations - 1))); 279 return; 280 } 281 __hwasan_thread_exit(); 282 } 283 284 void HwasanTSDInit() { 285 CHECK(!tsd_key_inited); 286 tsd_key_inited = true; 287 CHECK_EQ(0, pthread_key_create(&tsd_key, HwasanTSDDtor)); 288 } 289 #else 290 void HwasanTSDInit() {} 291 void HwasanTSDThreadInit() {} 292 #endif 293 294 #if SANITIZER_ANDROID 295 uptr *GetCurrentThreadLongPtr() { 296 return (uptr *)get_android_tls_ptr(); 297 } 298 #else 299 uptr *GetCurrentThreadLongPtr() { 300 return &__hwasan_tls; 301 } 302 #endif 303 304 #if SANITIZER_ANDROID 305 void AndroidTestTlsSlot() { 306 uptr kMagicValue = 0x010203040A0B0C0D; 307 uptr *tls_ptr = GetCurrentThreadLongPtr(); 308 uptr old_value = *tls_ptr; 309 *tls_ptr = kMagicValue; 310 dlerror(); 311 if (*(uptr *)get_android_tls_ptr() != kMagicValue) { 312 Printf( 313 "ERROR: Incompatible version of Android: TLS_SLOT_SANITIZER(6) is used " 314 "for dlerror().\n"); 315 Die(); 316 } 317 *tls_ptr = old_value; 318 } 319 #else 320 void AndroidTestTlsSlot() {} 321 #endif 322 323 static AccessInfo GetAccessInfo(siginfo_t *info, ucontext_t *uc) { 324 // Access type is passed in a platform dependent way (see below) and encoded 325 // as 0xXY, where X&1 is 1 for store, 0 for load, and X&2 is 1 if the error is 326 // recoverable. Valid values of Y are 0 to 4, which are interpreted as 327 // log2(access_size), and 0xF, which means that access size is passed via 328 // platform dependent register (see below). 329 #if defined(__aarch64__) 330 // Access type is encoded in BRK immediate as 0x900 + 0xXY. For Y == 0xF, 331 // access size is stored in X1 register. Access address is always in X0 332 // register. 333 uptr pc = (uptr)info->si_addr; 334 const unsigned code = ((*(u32 *)pc) >> 5) & 0xffff; 335 if ((code & 0xff00) != 0x900) 336 return AccessInfo{}; // Not ours. 337 338 const bool is_store = code & 0x10; 339 const bool recover = code & 0x20; 340 const uptr addr = uc->uc_mcontext.regs[0]; 341 const unsigned size_log = code & 0xf; 342 if (size_log > 4 && size_log != 0xf) 343 return AccessInfo{}; // Not ours. 344 const uptr size = size_log == 0xf ? uc->uc_mcontext.regs[1] : 1U << size_log; 345 346 #elif defined(__x86_64__) 347 // Access type is encoded in the instruction following INT3 as 348 // NOP DWORD ptr [EAX + 0x40 + 0xXY]. For Y == 0xF, access size is stored in 349 // RSI register. Access address is always in RDI register. 350 uptr pc = (uptr)uc->uc_mcontext.gregs[REG_RIP]; 351 uint8_t *nop = (uint8_t*)pc; 352 if (*nop != 0x0f || *(nop + 1) != 0x1f || *(nop + 2) != 0x40 || 353 *(nop + 3) < 0x40) 354 return AccessInfo{}; // Not ours. 355 const unsigned code = *(nop + 3); 356 357 const bool is_store = code & 0x10; 358 const bool recover = code & 0x20; 359 const uptr addr = uc->uc_mcontext.gregs[REG_RDI]; 360 const unsigned size_log = code & 0xf; 361 if (size_log > 4 && size_log != 0xf) 362 return AccessInfo{}; // Not ours. 363 const uptr size = 364 size_log == 0xf ? uc->uc_mcontext.gregs[REG_RSI] : 1U << size_log; 365 366 #else 367 # error Unsupported architecture 368 #endif 369 370 return AccessInfo{addr, size, is_store, !is_store, recover}; 371 } 372 373 static bool HwasanOnSIGTRAP(int signo, siginfo_t *info, ucontext_t *uc) { 374 AccessInfo ai = GetAccessInfo(info, uc); 375 if (!ai.is_store && !ai.is_load) 376 return false; 377 378 SignalContext sig{info, uc}; 379 HandleTagMismatch(ai, StackTrace::GetNextInstructionPc(sig.pc), sig.bp, uc); 380 381 #if defined(__aarch64__) 382 uc->uc_mcontext.pc += 4; 383 #elif defined(__x86_64__) 384 #else 385 # error Unsupported architecture 386 #endif 387 return true; 388 } 389 390 static void OnStackUnwind(const SignalContext &sig, const void *, 391 BufferedStackTrace *stack) { 392 stack->Unwind(StackTrace::GetNextInstructionPc(sig.pc), sig.bp, sig.context, 393 common_flags()->fast_unwind_on_fatal); 394 } 395 396 void HwasanOnDeadlySignal(int signo, void *info, void *context) { 397 // Probably a tag mismatch. 398 if (signo == SIGTRAP) 399 if (HwasanOnSIGTRAP(signo, (siginfo_t *)info, (ucontext_t*)context)) 400 return; 401 402 HandleDeadlySignal(info, context, GetTid(), &OnStackUnwind, nullptr); 403 } 404 405 void Thread::InitStackAndTls(const InitState *) { 406 uptr tls_size; 407 uptr stack_size; 408 GetThreadStackAndTls(IsMainThread(), &stack_bottom_, &stack_size, &tls_begin_, 409 &tls_size); 410 stack_top_ = stack_bottom_ + stack_size; 411 tls_end_ = tls_begin_ + tls_size; 412 } 413 414 uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) { 415 CHECK(IsAligned(p, kShadowAlignment)); 416 CHECK(IsAligned(size, kShadowAlignment)); 417 uptr shadow_start = MemToShadow(p); 418 uptr shadow_size = MemToShadowSize(size); 419 420 uptr page_size = GetPageSizeCached(); 421 uptr page_start = RoundUpTo(shadow_start, page_size); 422 uptr page_end = RoundDownTo(shadow_start + shadow_size, page_size); 423 uptr threshold = common_flags()->clear_shadow_mmap_threshold; 424 if (SANITIZER_LINUX && 425 UNLIKELY(page_end >= page_start + threshold && tag == 0)) { 426 internal_memset((void *)shadow_start, tag, page_start - shadow_start); 427 internal_memset((void *)page_end, tag, 428 shadow_start + shadow_size - page_end); 429 // For an anonymous private mapping MADV_DONTNEED will return a zero page on 430 // Linux. 431 ReleaseMemoryPagesToOSAndZeroFill(page_start, page_end); 432 } else { 433 internal_memset((void *)shadow_start, tag, shadow_size); 434 } 435 return AddTagToPointer(p, tag); 436 } 437 438 } // namespace __hwasan 439 440 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD 441