99 lines · cpp
1//===-- hwasan_globals.cpp ------------------------------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8//9// This file is a part of HWAddressSanitizer.10//11// HWAddressSanitizer globals-specific runtime.12//===----------------------------------------------------------------------===//13 14#include "hwasan_globals.h"15 16#include "sanitizer_common/sanitizer_array_ref.h"17 18namespace __hwasan {19 20enum { NT_LLVM_HWASAN_GLOBALS = 3 };21struct hwasan_global_note {22 s32 begin_relptr;23 s32 end_relptr;24};25 26// Check that the given library meets the code model requirements for tagged27// globals. These properties are not checked at link time so they need to be28// checked at runtime.29static void CheckCodeModel(ElfW(Addr) base, const ElfW(Phdr) * phdr,30 ElfW(Half) phnum) {31 ElfW(Addr) min_addr = -1ull, max_addr = 0;32 for (unsigned i = 0; i != phnum; ++i) {33 if (phdr[i].p_type != PT_LOAD)34 continue;35 ElfW(Addr) lo = base + phdr[i].p_vaddr, hi = lo + phdr[i].p_memsz;36 if (min_addr > lo)37 min_addr = lo;38 if (max_addr < hi)39 max_addr = hi;40 }41 42 if (max_addr - min_addr > 1ull << 32) {43 Report("FATAL: HWAddressSanitizer: library size exceeds 2^32\n");44 Die();45 }46 if (max_addr > 1ull << 48) {47 Report("FATAL: HWAddressSanitizer: library loaded above address 2^48\n");48 Die();49 }50}51 52ArrayRef<const hwasan_global> HwasanGlobalsFor(ElfW(Addr) base,53 const ElfW(Phdr) * phdr,54 ElfW(Half) phnum) {55 // Read the phdrs from this DSO.56 for (unsigned i = 0; i != phnum; ++i) {57 if (phdr[i].p_type != PT_NOTE)58 continue;59 60 const char *note = reinterpret_cast<const char *>(base + phdr[i].p_vaddr);61 const char *nend = note + phdr[i].p_memsz;62 63 // Traverse all the notes until we find a HWASan note.64 while (note < nend) {65 auto *nhdr = reinterpret_cast<const ElfW(Nhdr) *>(note);66 const char *name = note + sizeof(ElfW(Nhdr));67 const char *desc = name + RoundUpTo(nhdr->n_namesz, 4);68 69 // Discard non-HWASan-Globals notes.70 if (nhdr->n_type != NT_LLVM_HWASAN_GLOBALS ||71 internal_strcmp(name, "LLVM") != 0) {72 note = desc + RoundUpTo(nhdr->n_descsz, 4);73 continue;74 }75 76 auto *global_note = reinterpret_cast<const hwasan_global_note *>(desc);77 auto *globals_begin = reinterpret_cast<const hwasan_global *>(78 note + global_note->begin_relptr);79 auto *globals_end = reinterpret_cast<const hwasan_global *>(80 note + global_note->end_relptr);81 82 // Only libraries with instrumented globals need to be checked against the83 // code model since they use relocations that aren't checked at link time.84 //85 // There is always a HWASan globals note ("Create the note even if we86 // aren't instrumenting globals." - HWAddressSanitizer.cpp), but we can87 // elide the code model check if there are no globals.88 if (globals_begin != globals_end)89 CheckCodeModel(base, phdr, phnum);90 91 return {globals_begin, globals_end};92 }93 }94 95 return {};96}97 98} // namespace __hwasan99