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 #include "sanitizer_common/sanitizer_array_ref.h"
17
18 namespace __hwasan {
19
20 enum { NT_LLVM_HWASAN_GLOBALS = 3 };
21 struct 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 tagged
27 // globals. These properties are not checked at link time so they need to be
28 // checked at runtime.
CheckCodeModel(ElfW (Addr)base,const ElfW (Phdr)* phdr,ElfW (Half)phnum)29 static 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
HwasanGlobalsFor(ElfW (Addr)base,const ElfW (Phdr)* phdr,ElfW (Half)phnum)52 ArrayRef<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 // Only libraries with instrumented globals need to be checked against the
77 // code model since they use relocations that aren't checked at link time.
78 CheckCodeModel(base, phdr, phnum);
79
80 auto *global_note = reinterpret_cast<const hwasan_global_note *>(desc);
81 auto *globals_begin = reinterpret_cast<const hwasan_global *>(
82 note + global_note->begin_relptr);
83 auto *globals_end = reinterpret_cast<const hwasan_global *>(
84 note + global_note->end_relptr);
85
86 return {globals_begin, globals_end};
87 }
88 }
89
90 return {};
91 }
92
93 } // namespace __hwasan
94