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-exception 6 // 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 namespace __hwasan { 17 18 enum { NT_LLVM_HWASAN_GLOBALS = 3 }; 19 struct hwasan_global_note { 20 s32 begin_relptr; 21 s32 end_relptr; 22 }; 23 24 // Check that the given library meets the code model requirements for tagged 25 // globals. These properties are not checked at link time so they need to be 26 // checked at runtime. 27 static void CheckCodeModel(ElfW(Addr) base, const ElfW(Phdr) * phdr, 28 ElfW(Half) phnum) { 29 ElfW(Addr) min_addr = -1ull, max_addr = 0; 30 for (unsigned i = 0; i != phnum; ++i) { 31 if (phdr[i].p_type != PT_LOAD) 32 continue; 33 ElfW(Addr) lo = base + phdr[i].p_vaddr, hi = lo + phdr[i].p_memsz; 34 if (min_addr > lo) 35 min_addr = lo; 36 if (max_addr < hi) 37 max_addr = hi; 38 } 39 40 if (max_addr - min_addr > 1ull << 32) { 41 Report("FATAL: HWAddressSanitizer: library size exceeds 2^32\n"); 42 Die(); 43 } 44 if (max_addr > 1ull << 48) { 45 Report("FATAL: HWAddressSanitizer: library loaded above address 2^48\n"); 46 Die(); 47 } 48 } 49 50 ArrayRef<const hwasan_global> HwasanGlobalsFor(ElfW(Addr) base, 51 const ElfW(Phdr) * phdr, 52 ElfW(Half) phnum) { 53 // Read the phdrs from this DSO. 54 for (unsigned i = 0; i != phnum; ++i) { 55 if (phdr[i].p_type != PT_NOTE) 56 continue; 57 58 const char *note = reinterpret_cast<const char *>(base + phdr[i].p_vaddr); 59 const char *nend = note + phdr[i].p_memsz; 60 61 // Traverse all the notes until we find a HWASan note. 62 while (note < nend) { 63 auto *nhdr = reinterpret_cast<const ElfW(Nhdr) *>(note); 64 const char *name = note + sizeof(ElfW(Nhdr)); 65 const char *desc = name + RoundUpTo(nhdr->n_namesz, 4); 66 67 // Discard non-HWASan-Globals notes. 68 if (nhdr->n_type != NT_LLVM_HWASAN_GLOBALS || 69 internal_strcmp(name, "LLVM") != 0) { 70 note = desc + RoundUpTo(nhdr->n_descsz, 4); 71 continue; 72 } 73 74 // Only libraries with instrumented globals need to be checked against the 75 // code model since they use relocations that aren't checked at link time. 76 CheckCodeModel(base, phdr, phnum); 77 78 auto *global_note = reinterpret_cast<const hwasan_global_note *>(desc); 79 auto *globals_begin = reinterpret_cast<const hwasan_global *>( 80 note + global_note->begin_relptr); 81 auto *globals_end = reinterpret_cast<const hwasan_global *>( 82 note + global_note->end_relptr); 83 84 return {globals_begin, globals_end}; 85 } 86 } 87 88 return {}; 89 } 90 91 } // namespace __hwasan 92