lib/hwasan/hwasan.cpp

//===-- hwasan.cpp --------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of HWAddressSanitizer.
//
// HWAddressSanitizer runtime.
//===----------------------------------------------------------------------===//

#include "hwasan.h"

#include "hwasan_checks.h"
#include "hwasan_dynamic_shadow.h"
#include "hwasan_globals.h"
#include "hwasan_mapping.h"
#include "hwasan_poisoning.h"
#include "hwasan_report.h"
#include "hwasan_thread.h"
#include "hwasan_thread_list.h"
#include "sanitizer_common/sanitizer_atomic.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_flag_parser.h"
#include "sanitizer_common/sanitizer_flags.h"
#include "sanitizer_common/sanitizer_libc.h"
#include "sanitizer_common/sanitizer_procmaps.h"
#include "sanitizer_common/sanitizer_stackdepot.h"
#include "sanitizer_common/sanitizer_stacktrace.h"
#include "sanitizer_common/sanitizer_symbolizer.h"
#include "ubsan/ubsan_flags.h"
#include "ubsan/ubsan_init.h"

// ACHTUNG! No system header includes in this file.

using namespace __sanitizer;

namespace __hwasan {

static Flags hwasan_flags;

Flags *flags() {
  return &hwasan_flags;
}

int hwasan_inited = 0;
int hwasan_instrumentation_inited = 0;
bool hwasan_init_is_running;

int hwasan_report_count = 0;

uptr kLowShadowStart;
uptr kLowShadowEnd;
uptr kHighShadowStart;
uptr kHighShadowEnd;

void Flags::SetDefaults() {
#define HWASAN_FLAG(Type, Name, DefaultValue, Description) Name = DefaultValue;
#include "hwasan_flags.inc"
#undef HWASAN_FLAG
}

static void RegisterHwasanFlags(FlagParser *parser, Flags *f) {
#define HWASAN_FLAG(Type, Name, DefaultValue, Description) \
  RegisterFlag(parser, #Name, Description, &f->Name);
#include "hwasan_flags.inc"
#undef HWASAN_FLAG
}

static void InitializeFlags() {
  SetCommonFlagsDefaults();
  {
    CommonFlags cf;
    cf.CopyFrom(*common_flags());
    cf.external_symbolizer_path = GetEnv("HWASAN_SYMBOLIZER_PATH");
    cf.malloc_context_size = 20;
    cf.handle_ioctl = true;
    // FIXME: test and enable.
    cf.check_printf = false;
    cf.intercept_tls_get_addr = true;
    cf.exitcode = 99;
    // 8 shadow pages ~512kB, small enough to cover common stack sizes.
    cf.clear_shadow_mmap_threshold = 4096 * (SANITIZER_ANDROID ? 2 : 8);
    // Sigtrap is used in error reporting.
    cf.handle_sigtrap = kHandleSignalExclusive;

#if SANITIZER_ANDROID
    // Let platform handle other signals. It is better at reporting them then we
    // are.
    cf.handle_segv = kHandleSignalNo;
    cf.handle_sigbus = kHandleSignalNo;
    cf.handle_abort = kHandleSignalNo;
    cf.handle_sigill = kHandleSignalNo;
    cf.handle_sigfpe = kHandleSignalNo;
#endif
    OverrideCommonFlags(cf);
  }

  Flags *f = flags();
  f->SetDefaults();

  FlagParser parser;
  RegisterHwasanFlags(&parser, f);
  RegisterCommonFlags(&parser);

#if HWASAN_CONTAINS_UBSAN
  __ubsan::Flags *uf = __ubsan::flags();
  uf->SetDefaults();

  FlagParser ubsan_parser;
  __ubsan::RegisterUbsanFlags(&ubsan_parser, uf);
  RegisterCommonFlags(&ubsan_parser);
#endif

  // Override from user-specified string.
  if (__hwasan_default_options)
    parser.ParseString(__hwasan_default_options());
#if HWASAN_CONTAINS_UBSAN
  const char *ubsan_default_options = __ubsan_default_options();
  ubsan_parser.ParseString(ubsan_default_options);
#endif

  parser.ParseStringFromEnv("HWASAN_OPTIONS");
#if HWASAN_CONTAINS_UBSAN
  ubsan_parser.ParseStringFromEnv("UBSAN_OPTIONS");
#endif

  InitializeCommonFlags();

  if (Verbosity()) ReportUnrecognizedFlags();

  if (common_flags()->help) parser.PrintFlagDescriptions();
}

static void CheckUnwind() {
  GET_FATAL_STACK_TRACE_PC_BP(StackTrace::GetCurrentPc(), GET_CURRENT_FRAME());
  stack.Print();
}

static void HwasanFormatMemoryUsage(InternalScopedString &s) {
  HwasanThreadList &thread_list = hwasanThreadList();
  auto thread_stats = thread_list.GetThreadStats();
  auto sds = StackDepotGetStats();
  AllocatorStatCounters asc;
  GetAllocatorStats(asc);
  s.append(
      "HWASAN pid: %d rss: %zd threads: %zd stacks: %zd"
      " thr_aux: %zd stack_depot: %zd uniq_stacks: %zd"
      " heap: %zd",
      internal_getpid(), GetRSS(), thread_stats.n_live_threads,
      thread_stats.total_stack_size,
      thread_stats.n_live_threads * thread_list.MemoryUsedPerThread(),
      sds.allocated, sds.n_uniq_ids, asc[AllocatorStatMapped]);
}

#if SANITIZER_ANDROID
static constexpr uptr kMemoryUsageBufferSize = 4096;

static char *memory_usage_buffer = nullptr;

static void InitMemoryUsage() {
  memory_usage_buffer =
      (char *)MmapOrDie(kMemoryUsageBufferSize, "memory usage string");
  CHECK(memory_usage_buffer);
  memory_usage_buffer[0] = '\0';
  DecorateMapping((uptr)memory_usage_buffer, kMemoryUsageBufferSize,
                  memory_usage_buffer);
}

void UpdateMemoryUsage() {
  if (!flags()->export_memory_stats)
    return;
  if (!memory_usage_buffer)
    InitMemoryUsage();
  InternalScopedString s;
  HwasanFormatMemoryUsage(s);
  internal_strncpy(memory_usage_buffer, s.data(), kMemoryUsageBufferSize - 1);
  memory_usage_buffer[kMemoryUsageBufferSize - 1] = '\0';
}
#else
void UpdateMemoryUsage() {}
#endif

void HwasanAtExit() {
  if (common_flags()->print_module_map)
    DumpProcessMap();
  if (flags()->print_stats && (flags()->atexit || hwasan_report_count > 0))
    ReportStats();
  if (hwasan_report_count > 0) {
    // ReportAtExitStatistics();
    if (common_flags()->exitcode)
      internal__exit(common_flags()->exitcode);
  }
}

void HandleTagMismatch(AccessInfo ai, uptr pc, uptr frame, void *uc,
                       uptr *registers_frame) {
  InternalMmapVector<BufferedStackTrace> stack_buffer(1);
  BufferedStackTrace *stack = stack_buffer.data();
  stack->Reset();
  stack->Unwind(pc, frame, uc, common_flags()->fast_unwind_on_fatal);

  // The second stack frame contains the failure __hwasan_check function, as
  // we have a stack frame for the registers saved in __hwasan_tag_mismatch that
  // we wish to ignore. This (currently) only occurs on AArch64, as x64
  // implementations use SIGTRAP to implement the failure, and thus do not go
  // through the stack saver.
  if (registers_frame && stack->trace && stack->size > 0) {
    stack->trace++;
    stack->size--;
  }

  bool fatal = flags()->halt_on_error || !ai.recover;
  ReportTagMismatch(stack, ai.addr, ai.size, ai.is_store, fatal,
                    registers_frame);
}

void HwasanTagMismatch(uptr addr, uptr access_info, uptr *registers_frame,
                       size_t outsize) {
  __hwasan::AccessInfo ai;
  ai.is_store = access_info & 0x10;
  ai.is_load = !ai.is_store;
  ai.recover = access_info & 0x20;
  ai.addr = addr;
  if ((access_info & 0xf) == 0xf)
    ai.size = outsize;
  else
    ai.size = 1 << (access_info & 0xf);

  HandleTagMismatch(ai, (uptr)__builtin_return_address(0),
                    (uptr)__builtin_frame_address(0), nullptr, registers_frame);
  __builtin_unreachable();
}

Thread *GetCurrentThread() {
  uptr *ThreadLongPtr = GetCurrentThreadLongPtr();
  if (UNLIKELY(*ThreadLongPtr == 0))
    return nullptr;
  auto *R = (StackAllocationsRingBuffer *)ThreadLongPtr;
  return hwasanThreadList().GetThreadByBufferAddress((uptr)R->Next());
}

} // namespace __hwasan

using namespace __hwasan;

void __sanitizer::BufferedStackTrace::UnwindImpl(
    uptr pc, uptr bp, void *context, bool request_fast, u32 max_depth) {
  Thread *t = GetCurrentThread();
  if (!t) {
    // The thread is still being created, or has already been destroyed.
    size = 0;
    return;
  }
  Unwind(max_depth, pc, bp, context, t->stack_top(), t->stack_bottom(),
         request_fast);
}

static bool InitializeSingleGlobal(const hwasan_global &global) {
  uptr full_granule_size = RoundDownTo(global.size(), 16);
  TagMemoryAligned(global.addr(), full_granule_size, global.tag());
  if (global.size() % 16)
    TagMemoryAligned(global.addr() + full_granule_size, 16, global.size() % 16);
  return false;
}

static void InitLoadedGlobals() {
  dl_iterate_phdr(
      [](dl_phdr_info *info, size_t /* size */, void * /* data */) -> int {
        for (const hwasan_global &global : HwasanGlobalsFor(
                 info->dlpi_addr, info->dlpi_phdr, info->dlpi_phnum))
          InitializeSingleGlobal(global);
        return 0;
      },
      nullptr);
}

// Prepare to run instrumented code on the main thread.
static void InitInstrumentation() {
  if (hwasan_instrumentation_inited) return;

  InitializeOsSupport();

  if (!InitShadow()) {
    Printf("FATAL: HWAddressSanitizer cannot mmap the shadow memory.\n");
    DumpProcessMap();
    Die();
  }

  InitThreads();

  hwasan_instrumentation_inited = 1;
}

// Interface.

uptr __hwasan_shadow_memory_dynamic_address;  // Global interface symbol.

// This function was used by the old frame descriptor mechanism. We keep it
// around to avoid breaking ABI.
void __hwasan_init_frames(uptr beg, uptr end) {}

void __hwasan_init_static() {
  InitShadowGOT();
  InitInstrumentation();

  // In the non-static code path we call dl_iterate_phdr here. But at this point
  // libc might not have been initialized enough for dl_iterate_phdr to work.
  // Fortunately, since this is a statically linked executable we can use the
  // linker-defined symbol __ehdr_start to find the only relevant set of phdrs.
  extern ElfW(Ehdr) __ehdr_start;
  for (const hwasan_global &global : HwasanGlobalsFor(
           /* base */ 0,
           reinterpret_cast<const ElfW(Phdr) *>(
               reinterpret_cast<const char *>(&__ehdr_start) +
               __ehdr_start.e_phoff),
           __ehdr_start.e_phnum))
    InitializeSingleGlobal(global);
}

__attribute__((constructor(0))) void __hwasan_init() {
  CHECK(!hwasan_init_is_running);
  if (hwasan_inited) return;
  hwasan_init_is_running = 1;
  SanitizerToolName = "HWAddressSanitizer";

  InitTlsSize();

  CacheBinaryName();
  InitializeFlags();

  // Install tool-specific callbacks in sanitizer_common.
  SetCheckUnwindCallback(CheckUnwind);

  __sanitizer_set_report_path(common_flags()->log_path);

  AndroidTestTlsSlot();

  DisableCoreDumperIfNecessary();

  InitInstrumentation();
  InitLoadedGlobals();

  // Needs to be called here because flags()->random_tags might not have been
  // initialized when InitInstrumentation() was called.
  GetCurrentThread()->EnsureRandomStateInited();

  SetPrintfAndReportCallback(AppendToErrorMessageBuffer);
  // This may call libc -> needs initialized shadow.
  AndroidLogInit();

  InitializeInterceptors();
  InstallDeadlySignalHandlers(HwasanOnDeadlySignal);
  InstallAtExitHandler(); // Needs __cxa_atexit interceptor.

  InitializeCoverage(common_flags()->coverage, common_flags()->coverage_dir);

  HwasanTSDInit();
  HwasanTSDThreadInit();

  HwasanAllocatorInit();
  HwasanInstallAtForkHandler();

#if HWASAN_CONTAINS_UBSAN
  __ubsan::InitAsPlugin();
#endif

  VPrintf(1, "HWAddressSanitizer init done\n");

  hwasan_init_is_running = 0;
  hwasan_inited = 1;
}

void __hwasan_library_loaded(ElfW(Addr) base, const ElfW(Phdr) * phdr,
                             ElfW(Half) phnum) {
  for (const hwasan_global &global : HwasanGlobalsFor(base, phdr, phnum))
    InitializeSingleGlobal(global);
}

void __hwasan_library_unloaded(ElfW(Addr) base, const ElfW(Phdr) * phdr,
                               ElfW(Half) phnum) {
  for (; phnum != 0; ++phdr, --phnum)
    if (phdr->p_type == PT_LOAD)
      TagMemory(base + phdr->p_vaddr, phdr->p_memsz, 0);
}

void __hwasan_print_shadow(const void *p, uptr sz) {
  uptr ptr_raw = UntagAddr(reinterpret_cast<uptr>(p));
  uptr shadow_first = MemToShadow(ptr_raw);
  uptr shadow_last = MemToShadow(ptr_raw + sz - 1);
  Printf("HWASan shadow map for %zx .. %zx (pointer tag %x)\n", ptr_raw,
         ptr_raw + sz, GetTagFromPointer((uptr)p));
  for (uptr s = shadow_first; s <= shadow_last; ++s) {
    tag_t mem_tag = *reinterpret_cast<tag_t *>(s);
    uptr granule_addr = ShadowToMem(s);
    if (mem_tag && mem_tag < kShadowAlignment)
      Printf("  %zx: %02x(%02x)\n", granule_addr, mem_tag,
             *reinterpret_cast<tag_t *>(granule_addr + kShadowAlignment - 1));
    else
      Printf("  %zx: %02x\n", granule_addr, mem_tag);
  }
}

sptr __hwasan_test_shadow(const void *p, uptr sz) {
  if (sz == 0)
    return -1;
  tag_t ptr_tag = GetTagFromPointer((uptr)p);
  uptr ptr_raw = UntagAddr(reinterpret_cast<uptr>(p));
  uptr shadow_first = MemToShadow(ptr_raw);
  uptr shadow_last = MemToShadow(ptr_raw + sz - 1);
  for (uptr s = shadow_first; s <= shadow_last; ++s)
    if (*(tag_t *)s != ptr_tag) {
      sptr offset = ShadowToMem(s) - ptr_raw;
      return offset < 0 ? 0 : offset;
    }
  return -1;
}

u16 __sanitizer_unaligned_load16(const uu16 *p) {
  return *p;
}
u32 __sanitizer_unaligned_load32(const uu32 *p) {
  return *p;
}
u64 __sanitizer_unaligned_load64(const uu64 *p) {
  return *p;
}
void __sanitizer_unaligned_store16(uu16 *p, u16 x) {
  *p = x;
}
void __sanitizer_unaligned_store32(uu32 *p, u32 x) {
  *p = x;
}
void __sanitizer_unaligned_store64(uu64 *p, u64 x) {
  *p = x;
}

void __hwasan_loadN(uptr p, uptr sz) {
  CheckAddressSized<ErrorAction::Abort, AccessType::Load>(p, sz);
}
void __hwasan_load1(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Load, 0>(p);
}
void __hwasan_load2(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Load, 1>(p);
}
void __hwasan_load4(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Load, 2>(p);
}
void __hwasan_load8(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Load, 3>(p);
}
void __hwasan_load16(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Load, 4>(p);
}

void __hwasan_loadN_noabort(uptr p, uptr sz) {
  CheckAddressSized<ErrorAction::Recover, AccessType::Load>(p, sz);
}
void __hwasan_load1_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Load, 0>(p);
}
void __hwasan_load2_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Load, 1>(p);
}
void __hwasan_load4_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Load, 2>(p);
}
void __hwasan_load8_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Load, 3>(p);
}
void __hwasan_load16_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Load, 4>(p);
}

void __hwasan_storeN(uptr p, uptr sz) {
  CheckAddressSized<ErrorAction::Abort, AccessType::Store>(p, sz);
}
void __hwasan_store1(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Store, 0>(p);
}
void __hwasan_store2(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Store, 1>(p);
}
void __hwasan_store4(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Store, 2>(p);
}
void __hwasan_store8(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Store, 3>(p);
}
void __hwasan_store16(uptr p) {
  CheckAddress<ErrorAction::Abort, AccessType::Store, 4>(p);
}

void __hwasan_storeN_noabort(uptr p, uptr sz) {
  CheckAddressSized<ErrorAction::Recover, AccessType::Store>(p, sz);
}
void __hwasan_store1_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Store, 0>(p);
}
void __hwasan_store2_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Store, 1>(p);
}
void __hwasan_store4_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Store, 2>(p);
}
void __hwasan_store8_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Store, 3>(p);
}
void __hwasan_store16_noabort(uptr p) {
  CheckAddress<ErrorAction::Recover, AccessType::Store, 4>(p);
}

void __hwasan_tag_memory(uptr p, u8 tag, uptr sz) {
  TagMemoryAligned(p, sz, tag);
}

uptr __hwasan_tag_pointer(uptr p, u8 tag) {
  return AddTagToPointer(p, tag);
}

void __hwasan_handle_longjmp(const void *sp_dst) {
  uptr dst = (uptr)sp_dst;
  // HWASan does not support tagged SP.
  CHECK(GetTagFromPointer(dst) == 0);

  uptr sp = (uptr)__builtin_frame_address(0);
  static const uptr kMaxExpectedCleanupSize = 64 << 20;  // 64M
  if (dst < sp || dst - sp > kMaxExpectedCleanupSize) {
    Report(
        "WARNING: HWASan is ignoring requested __hwasan_handle_longjmp: "
        "stack top: %p; target %p; distance: %p (%zd)\n"
        "False positive error reports may follow\n",
        (void *)sp, (void *)dst, dst - sp);
    return;
  }
  TagMemory(sp, dst - sp, 0);
}

void __hwasan_handle_vfork(const void *sp_dst) {
  uptr sp = (uptr)sp_dst;
  Thread *t = GetCurrentThread();
  CHECK(t);
  uptr top = t->stack_top();
  uptr bottom = t->stack_bottom();
  if (top == 0 || bottom == 0 || sp < bottom || sp >= top) {
    Report(
        "WARNING: HWASan is ignoring requested __hwasan_handle_vfork: "
        "stack top: %zx; current %zx; bottom: %zx \n"
        "False positive error reports may follow\n",
        top, sp, bottom);
    return;
  }
  TagMemory(bottom, sp - bottom, 0);
}

extern "C" void *__hwasan_extra_spill_area() {
  Thread *t = GetCurrentThread();
  return &t->vfork_spill();
}

void __hwasan_print_memory_usage() {
  InternalScopedString s;
  HwasanFormatMemoryUsage(s);
  Printf("%s\n", s.data());
}

static const u8 kFallbackTag = 0xBB & kTagMask;

u8 __hwasan_generate_tag() {
  Thread *t = GetCurrentThread();
  if (!t) return kFallbackTag;
  return t->GenerateRandomTag();
}

#if !SANITIZER_SUPPORTS_WEAK_HOOKS
extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
const char* __hwasan_default_options() { return ""; }
}  // extern "C"
#endif

extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE
void __sanitizer_print_stack_trace() {
  GET_FATAL_STACK_TRACE_PC_BP(StackTrace::GetCurrentPc(), GET_CURRENT_FRAME());
  stack.Print();
}

// Entry point for interoperability between __hwasan_tag_mismatch (ASM) and the
// rest of the mismatch handling code (C++).
void __hwasan_tag_mismatch4(uptr addr, uptr access_info, uptr *registers_frame,
                            size_t outsize) {
  __hwasan::HwasanTagMismatch(addr, access_info, registers_frame, outsize);
}

} // extern "C"