path: root/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_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 {

void EnterSymbolizer() {
  Thread *t = GetCurrentThread();
  CHECK(t);
  t->EnterSymbolizer();
}
void ExitSymbolizer() {
  Thread *t = GetCurrentThread();
  CHECK(t);
  t->LeaveSymbolizer();
}
bool IsInSymbolizer() {
  Thread *t = GetCurrentThread();
  return t && t->InSymbolizer();
}

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;

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::MaybeCallUbsanDefaultOptions();
  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 HWAsanCheckFailed(const char *file, int line, const char *cond,
                              u64 v1, u64 v2) {
  Report("HWAddressSanitizer CHECK failed: %s:%d \"%s\" (0x%zx, 0x%zx)\n", file,
         line, cond, (uptr)v1, (uptr)v2);
  PRINT_CURRENT_STACK_CHECK();
  Die();
}

static constexpr uptr kMemoryUsageBufferSize = 4096;

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 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(kMemoryUsageBufferSize);
  HwasanFormatMemoryUsage(s);
  internal_strncpy(memory_usage_buffer, s.data(), kMemoryUsageBufferSize - 1);
  memory_usage_buffer[kMemoryUsageBufferSize - 1] = '\0';
}
#else
void UpdateMemoryUsage() {}
#endif

} // 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.
    size = 0;
    return;
  }
  if (!StackTrace::WillUseFastUnwind(request_fast)) {
    // Block reports from our interceptors during _Unwind_Backtrace.
    SymbolizerScope sym_scope;
    return Unwind(max_depth, pc, bp, context, 0, 0, request_fast);
  }
  if (StackTrace::WillUseFastUnwind(request_fast))
    Unwind(max_depth, pc, bp, nullptr, t->stack_top(), t->stack_bottom(), true);
  else
    Unwind(max_depth, pc, 0, context, 0, 0, false);
}

struct hwasan_global {
  s32 gv_relptr;
  u32 info;
};

static void InitGlobals(const hwasan_global *begin, const hwasan_global *end) {
  for (auto *desc = begin; desc != end; ++desc) {
    uptr gv = reinterpret_cast<uptr>(desc) + desc->gv_relptr;
    uptr size = desc->info & 0xffffff;
    uptr full_granule_size = RoundDownTo(size, 16);
    u8 tag = desc->info >> 24;
    TagMemoryAligned(gv, full_granule_size, tag);
    if (size % 16)
      TagMemoryAligned(gv + full_granule_size, 16, size % 16);
  }
}

enum { NT_LLVM_HWASAN_GLOBALS = 3 };

struct hwasan_global_note {
  s32 begin_relptr;
  s32 end_relptr;
};

// Check that the given library meets the code model requirements for tagged
// globals. These properties are not checked at link time so they need to be
// checked at runtime.
static void CheckCodeModel(ElfW(Addr) base, const ElfW(Phdr) * phdr,
                           ElfW(Half) phnum) {
  ElfW(Addr) min_addr = -1ull, max_addr = 0;
  for (unsigned i = 0; i != phnum; ++i) {
    if (phdr[i].p_type != PT_LOAD)
      continue;
    ElfW(Addr) lo = base + phdr[i].p_vaddr, hi = lo + phdr[i].p_memsz;
    if (min_addr > lo)
      min_addr = lo;
    if (max_addr < hi)
      max_addr = hi;
  }

  if (max_addr - min_addr > 1ull << 32) {
    Report("FATAL: HWAddressSanitizer: library size exceeds 2^32\n");
    Die();
  }
  if (max_addr > 1ull << 48) {
    Report("FATAL: HWAddressSanitizer: library loaded above address 2^48\n");
    Die();
  }
}

static void InitGlobalsFromPhdrs(ElfW(Addr) base, const ElfW(Phdr) * phdr,
                                 ElfW(Half) phnum) {
  for (unsigned i = 0; i != phnum; ++i) {
    if (phdr[i].p_type != PT_NOTE)
      continue;
    const char *note = reinterpret_cast<const char *>(base + phdr[i].p_vaddr);
    const char *nend = note + phdr[i].p_memsz;
    while (note < nend) {
      auto *nhdr = reinterpret_cast<const ElfW(Nhdr) *>(note);
      const char *name = note + sizeof(ElfW(Nhdr));
      const char *desc = name + RoundUpTo(nhdr->n_namesz, 4);
      if (nhdr->n_type != NT_LLVM_HWASAN_GLOBALS ||
          internal_strcmp(name, "LLVM") != 0) {
        note = desc + RoundUpTo(nhdr->n_descsz, 4);
        continue;
      }

      // Only libraries with instrumented globals need to be checked against the
      // code model since they use relocations that aren't checked at link time.
      CheckCodeModel(base, phdr, phnum);

      auto *global_note = reinterpret_cast<const hwasan_global_note *>(desc);
      auto *global_begin = reinterpret_cast<const hwasan_global *>(
          note + global_note->begin_relptr);
      auto *global_end = reinterpret_cast<const hwasan_global *>(
          note + global_note->end_relptr);
      InitGlobals(global_begin, global_end);
      return;
    }
  }
}

static void InitLoadedGlobals() {
  dl_iterate_phdr(
      [](dl_phdr_info *info, size_t size, void *data) {
        InitGlobalsFromPhdrs(info->dlpi_addr, info->dlpi_phdr,
                             info->dlpi_phnum);
        return 0;
      },
      nullptr);
}

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

  InitPrctl();

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

  InitThreads();
  hwasanThreadList().CreateCurrentThread();

  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;
  InitGlobalsFromPhdrs(
      0,
      reinterpret_cast<const ElfW(Phdr) *>(
          reinterpret_cast<const char *>(&__ehdr_start) + __ehdr_start.e_phoff),
      __ehdr_start.e_phnum);
}

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.
  SetCheckFailedCallback(HWAsanCheckFailed);

  __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()->InitRandomState();

  MadviseShadow();

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

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

  Symbolizer::GetOrInit()->AddHooks(EnterSymbolizer, ExitSymbolizer);

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

  HwasanTSDInit();
  HwasanTSDThreadInit();

  HwasanAllocatorInit();

#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) {
  InitGlobalsFromPhdrs(base, phdr, phnum);
}

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)
    Printf("  %zx: %x\n", ShadowToMem(s), *(tag_t *)s);
}

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(kMemoryUsageBufferSize);
  HwasanFormatMemoryUsage(s);
  Printf("%s\n", s.data());
}

static const u8 kFallbackTag = 0xBB;

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();
}
} // extern "C"