1 //===- ELF.h - ELF object file implementation -------------------*- C++ -*-===//
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 declares the ELFFile template class.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef LLVM_OBJECT_ELF_H
14 #define LLVM_OBJECT_ELF_H
15
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/SmallString.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/BinaryFormat/ELF.h"
21 #include "llvm/Object/ELFTypes.h"
22 #include "llvm/Object/Error.h"
23 #include "llvm/Support/Endian.h"
24 #include "llvm/Support/Error.h"
25 #include <cassert>
26 #include <cstddef>
27 #include <cstdint>
28 #include <limits>
29 #include <utility>
30
31 namespace llvm {
32 namespace object {
33
34 struct VerdAux {
35 unsigned Offset;
36 std::string Name;
37 };
38
39 struct VerDef {
40 unsigned Offset;
41 unsigned Version;
42 unsigned Flags;
43 unsigned Ndx;
44 unsigned Cnt;
45 unsigned Hash;
46 std::string Name;
47 std::vector<VerdAux> AuxV;
48 };
49
50 struct VernAux {
51 unsigned Hash;
52 unsigned Flags;
53 unsigned Other;
54 unsigned Offset;
55 std::string Name;
56 };
57
58 struct VerNeed {
59 unsigned Version;
60 unsigned Cnt;
61 unsigned Offset;
62 std::string File;
63 std::vector<VernAux> AuxV;
64 };
65
66 struct VersionEntry {
67 std::string Name;
68 bool IsVerDef;
69 };
70
71 StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
72 uint32_t getELFRelativeRelocationType(uint32_t Machine);
73 StringRef getELFSectionTypeName(uint32_t Machine, uint32_t Type);
74
75 // Subclasses of ELFFile may need this for template instantiation
76 inline std::pair<unsigned char, unsigned char>
getElfArchType(StringRef Object)77 getElfArchType(StringRef Object) {
78 if (Object.size() < ELF::EI_NIDENT)
79 return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
80 (uint8_t)ELF::ELFDATANONE);
81 return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
82 (uint8_t)Object[ELF::EI_DATA]);
83 }
84
85 enum PPCInstrMasks : uint64_t {
86 PADDI_R12_NO_DISP = 0x0610000039800000,
87 ADDIS_R12_TO_R2_NO_DISP = 0x3D820000,
88 ADDI_R12_TO_R2_NO_DISP = 0x39820000,
89 ADDI_R12_TO_R12_NO_DISP = 0x398C0000,
90 PLD_R12_NO_DISP = 0x04100000E5800000,
91 MTCTR_R12 = 0x7D8903A6,
92 BCTR = 0x4E800420,
93 };
94
95 template <class ELFT> class ELFFile;
96
97 template <class T> struct DataRegion {
98 // This constructor is used when we know the start and the size of a data
99 // region. We assume that Arr does not go past the end of the file.
DataRegionDataRegion100 DataRegion(ArrayRef<T> Arr) : First(Arr.data()), Size(Arr.size()) {}
101
102 // Sometimes we only know the start of a data region. We still don't want to
103 // read past the end of the file, so we provide the end of a buffer.
DataRegionDataRegion104 DataRegion(const T *Data, const uint8_t *BufferEnd)
105 : First(Data), BufEnd(BufferEnd) {}
106
107 Expected<T> operator[](uint64_t N) {
108 assert(Size || BufEnd);
109 if (Size) {
110 if (N >= *Size)
111 return createError(
112 "the index is greater than or equal to the number of entries (" +
113 Twine(*Size) + ")");
114 } else {
115 const uint8_t *EntryStart = (const uint8_t *)First + N * sizeof(T);
116 if (EntryStart + sizeof(T) > BufEnd)
117 return createError("can't read past the end of the file");
118 }
119 return *(First + N);
120 }
121
122 const T *First;
123 std::optional<uint64_t> Size;
124 const uint8_t *BufEnd = nullptr;
125 };
126
127 template <class ELFT>
getSecIndexForError(const ELFFile<ELFT> & Obj,const typename ELFT::Shdr & Sec)128 std::string getSecIndexForError(const ELFFile<ELFT> &Obj,
129 const typename ELFT::Shdr &Sec) {
130 auto TableOrErr = Obj.sections();
131 if (TableOrErr)
132 return "[index " + std::to_string(&Sec - &TableOrErr->front()) + "]";
133 // To make this helper be more convenient for error reporting purposes we
134 // drop the error. But really it should never be triggered. Before this point,
135 // our code should have called 'sections()' and reported a proper error on
136 // failure.
137 llvm::consumeError(TableOrErr.takeError());
138 return "[unknown index]";
139 }
140
141 template <class ELFT>
describe(const ELFFile<ELFT> & Obj,const typename ELFT::Shdr & Sec)142 static std::string describe(const ELFFile<ELFT> &Obj,
143 const typename ELFT::Shdr &Sec) {
144 unsigned SecNdx = &Sec - &cantFail(Obj.sections()).front();
145 return (object::getELFSectionTypeName(Obj.getHeader().e_machine,
146 Sec.sh_type) +
147 " section with index " + Twine(SecNdx))
148 .str();
149 }
150
151 template <class ELFT>
getPhdrIndexForError(const ELFFile<ELFT> & Obj,const typename ELFT::Phdr & Phdr)152 std::string getPhdrIndexForError(const ELFFile<ELFT> &Obj,
153 const typename ELFT::Phdr &Phdr) {
154 auto Headers = Obj.program_headers();
155 if (Headers)
156 return ("[index " + Twine(&Phdr - &Headers->front()) + "]").str();
157 // See comment in the getSecIndexForError() above.
158 llvm::consumeError(Headers.takeError());
159 return "[unknown index]";
160 }
161
defaultWarningHandler(const Twine & Msg)162 static inline Error defaultWarningHandler(const Twine &Msg) {
163 return createError(Msg);
164 }
165
166 template <class ELFT>
167 class ELFFile {
168 public:
169 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
170
171 // This is a callback that can be passed to a number of functions.
172 // It can be used to ignore non-critical errors (warnings), which is
173 // useful for dumpers, like llvm-readobj.
174 // It accepts a warning message string and returns a success
175 // when the warning should be ignored or an error otherwise.
176 using WarningHandler = llvm::function_ref<Error(const Twine &Msg)>;
177
base()178 const uint8_t *base() const { return Buf.bytes_begin(); }
end()179 const uint8_t *end() const { return base() + getBufSize(); }
180
getBufSize()181 size_t getBufSize() const { return Buf.size(); }
182
183 private:
184 StringRef Buf;
185 std::vector<Elf_Shdr> FakeSections;
186 SmallString<0> FakeSectionStrings;
187
188 ELFFile(StringRef Object);
189
190 public:
getHeader()191 const Elf_Ehdr &getHeader() const {
192 return *reinterpret_cast<const Elf_Ehdr *>(base());
193 }
194
195 template <typename T>
196 Expected<const T *> getEntry(uint32_t Section, uint32_t Entry) const;
197 template <typename T>
198 Expected<const T *> getEntry(const Elf_Shdr &Section, uint32_t Entry) const;
199
200 Expected<std::vector<VerDef>>
201 getVersionDefinitions(const Elf_Shdr &Sec) const;
202 Expected<std::vector<VerNeed>> getVersionDependencies(
203 const Elf_Shdr &Sec,
204 WarningHandler WarnHandler = &defaultWarningHandler) const;
205 Expected<StringRef> getSymbolVersionByIndex(
206 uint32_t SymbolVersionIndex, bool &IsDefault,
207 SmallVector<std::optional<VersionEntry>, 0> &VersionMap,
208 std::optional<bool> IsSymHidden) const;
209
210 Expected<StringRef>
211 getStringTable(const Elf_Shdr &Section,
212 WarningHandler WarnHandler = &defaultWarningHandler) const;
213 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
214 Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section,
215 Elf_Shdr_Range Sections) const;
216 Expected<StringRef> getLinkAsStrtab(const typename ELFT::Shdr &Sec) const;
217
218 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
219 Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section,
220 Elf_Shdr_Range Sections) const;
221
222 Expected<uint64_t> getDynSymtabSize() const;
223
224 StringRef getRelocationTypeName(uint32_t Type) const;
225 void getRelocationTypeName(uint32_t Type,
226 SmallVectorImpl<char> &Result) const;
227 uint32_t getRelativeRelocationType() const;
228
229 std::string getDynamicTagAsString(unsigned Arch, uint64_t Type) const;
230 std::string getDynamicTagAsString(uint64_t Type) const;
231
232 /// Get the symbol for a given relocation.
233 Expected<const Elf_Sym *> getRelocationSymbol(const Elf_Rel &Rel,
234 const Elf_Shdr *SymTab) const;
235
236 Expected<SmallVector<std::optional<VersionEntry>, 0>>
237 loadVersionMap(const Elf_Shdr *VerNeedSec, const Elf_Shdr *VerDefSec) const;
238
239 static Expected<ELFFile> create(StringRef Object);
240
isLE()241 bool isLE() const {
242 return getHeader().getDataEncoding() == ELF::ELFDATA2LSB;
243 }
244
isMipsELF64()245 bool isMipsELF64() const {
246 return getHeader().e_machine == ELF::EM_MIPS &&
247 getHeader().getFileClass() == ELF::ELFCLASS64;
248 }
249
isMips64EL()250 bool isMips64EL() const { return isMipsELF64() && isLE(); }
251
252 Expected<Elf_Shdr_Range> sections() const;
253
254 Expected<Elf_Dyn_Range> dynamicEntries() const;
255
256 Expected<const uint8_t *>
257 toMappedAddr(uint64_t VAddr,
258 WarningHandler WarnHandler = &defaultWarningHandler) const;
259
symbols(const Elf_Shdr * Sec)260 Expected<Elf_Sym_Range> symbols(const Elf_Shdr *Sec) const {
261 if (!Sec)
262 return ArrayRef<Elf_Sym>(nullptr, nullptr);
263 return getSectionContentsAsArray<Elf_Sym>(*Sec);
264 }
265
relas(const Elf_Shdr & Sec)266 Expected<Elf_Rela_Range> relas(const Elf_Shdr &Sec) const {
267 return getSectionContentsAsArray<Elf_Rela>(Sec);
268 }
269
rels(const Elf_Shdr & Sec)270 Expected<Elf_Rel_Range> rels(const Elf_Shdr &Sec) const {
271 return getSectionContentsAsArray<Elf_Rel>(Sec);
272 }
273
relrs(const Elf_Shdr & Sec)274 Expected<Elf_Relr_Range> relrs(const Elf_Shdr &Sec) const {
275 return getSectionContentsAsArray<Elf_Relr>(Sec);
276 }
277
278 std::vector<Elf_Rel> decode_relrs(Elf_Relr_Range relrs) const;
279
280 Expected<std::vector<Elf_Rela>> android_relas(const Elf_Shdr &Sec) const;
281
282 /// Iterate over program header table.
program_headers()283 Expected<Elf_Phdr_Range> program_headers() const {
284 if (getHeader().e_phnum && getHeader().e_phentsize != sizeof(Elf_Phdr))
285 return createError("invalid e_phentsize: " +
286 Twine(getHeader().e_phentsize));
287
288 uint64_t HeadersSize =
289 (uint64_t)getHeader().e_phnum * getHeader().e_phentsize;
290 uint64_t PhOff = getHeader().e_phoff;
291 if (PhOff + HeadersSize < PhOff || PhOff + HeadersSize > getBufSize())
292 return createError("program headers are longer than binary of size " +
293 Twine(getBufSize()) + ": e_phoff = 0x" +
294 Twine::utohexstr(getHeader().e_phoff) +
295 ", e_phnum = " + Twine(getHeader().e_phnum) +
296 ", e_phentsize = " + Twine(getHeader().e_phentsize));
297
298 auto *Begin = reinterpret_cast<const Elf_Phdr *>(base() + PhOff);
299 return ArrayRef(Begin, Begin + getHeader().e_phnum);
300 }
301
302 /// Get an iterator over notes in a program header.
303 ///
304 /// The program header must be of type \c PT_NOTE.
305 ///
306 /// \param Phdr the program header to iterate over.
307 /// \param Err [out] an error to support fallible iteration, which should
308 /// be checked after iteration ends.
notes_begin(const Elf_Phdr & Phdr,Error & Err)309 Elf_Note_Iterator notes_begin(const Elf_Phdr &Phdr, Error &Err) const {
310 assert(Phdr.p_type == ELF::PT_NOTE && "Phdr is not of type PT_NOTE");
311 ErrorAsOutParameter ErrAsOutParam(&Err);
312 if (Phdr.p_offset + Phdr.p_filesz > getBufSize()) {
313 Err =
314 createError("invalid offset (0x" + Twine::utohexstr(Phdr.p_offset) +
315 ") or size (0x" + Twine::utohexstr(Phdr.p_filesz) + ")");
316 return Elf_Note_Iterator(Err);
317 }
318 return Elf_Note_Iterator(base() + Phdr.p_offset, Phdr.p_filesz, Err);
319 }
320
321 /// Get an iterator over notes in a section.
322 ///
323 /// The section must be of type \c SHT_NOTE.
324 ///
325 /// \param Shdr the section to iterate over.
326 /// \param Err [out] an error to support fallible iteration, which should
327 /// be checked after iteration ends.
notes_begin(const Elf_Shdr & Shdr,Error & Err)328 Elf_Note_Iterator notes_begin(const Elf_Shdr &Shdr, Error &Err) const {
329 assert(Shdr.sh_type == ELF::SHT_NOTE && "Shdr is not of type SHT_NOTE");
330 ErrorAsOutParameter ErrAsOutParam(&Err);
331 if (Shdr.sh_offset + Shdr.sh_size > getBufSize()) {
332 Err =
333 createError("invalid offset (0x" + Twine::utohexstr(Shdr.sh_offset) +
334 ") or size (0x" + Twine::utohexstr(Shdr.sh_size) + ")");
335 return Elf_Note_Iterator(Err);
336 }
337 return Elf_Note_Iterator(base() + Shdr.sh_offset, Shdr.sh_size, Err);
338 }
339
340 /// Get the end iterator for notes.
notes_end()341 Elf_Note_Iterator notes_end() const {
342 return Elf_Note_Iterator();
343 }
344
345 /// Get an iterator range over notes of a program header.
346 ///
347 /// The program header must be of type \c PT_NOTE.
348 ///
349 /// \param Phdr the program header to iterate over.
350 /// \param Err [out] an error to support fallible iteration, which should
351 /// be checked after iteration ends.
notes(const Elf_Phdr & Phdr,Error & Err)352 iterator_range<Elf_Note_Iterator> notes(const Elf_Phdr &Phdr,
353 Error &Err) const {
354 return make_range(notes_begin(Phdr, Err), notes_end());
355 }
356
357 /// Get an iterator range over notes of a section.
358 ///
359 /// The section must be of type \c SHT_NOTE.
360 ///
361 /// \param Shdr the section to iterate over.
362 /// \param Err [out] an error to support fallible iteration, which should
363 /// be checked after iteration ends.
notes(const Elf_Shdr & Shdr,Error & Err)364 iterator_range<Elf_Note_Iterator> notes(const Elf_Shdr &Shdr,
365 Error &Err) const {
366 return make_range(notes_begin(Shdr, Err), notes_end());
367 }
368
369 Expected<StringRef> getSectionStringTable(
370 Elf_Shdr_Range Sections,
371 WarningHandler WarnHandler = &defaultWarningHandler) const;
372 Expected<uint32_t> getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
373 DataRegion<Elf_Word> ShndxTable) const;
374 Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
375 const Elf_Shdr *SymTab,
376 DataRegion<Elf_Word> ShndxTable) const;
377 Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
378 Elf_Sym_Range Symtab,
379 DataRegion<Elf_Word> ShndxTable) const;
380 Expected<const Elf_Shdr *> getSection(uint32_t Index) const;
381
382 Expected<const Elf_Sym *> getSymbol(const Elf_Shdr *Sec,
383 uint32_t Index) const;
384
385 Expected<StringRef>
386 getSectionName(const Elf_Shdr &Section,
387 WarningHandler WarnHandler = &defaultWarningHandler) const;
388 Expected<StringRef> getSectionName(const Elf_Shdr &Section,
389 StringRef DotShstrtab) const;
390 template <typename T>
391 Expected<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr &Sec) const;
392 Expected<ArrayRef<uint8_t>> getSectionContents(const Elf_Shdr &Sec) const;
393 Expected<ArrayRef<uint8_t>> getSegmentContents(const Elf_Phdr &Phdr) const;
394 Expected<std::vector<BBAddrMap>> decodeBBAddrMap(const Elf_Shdr &Sec) const;
395
396 void createFakeSections();
397 };
398
399 using ELF32LEFile = ELFFile<ELF32LE>;
400 using ELF64LEFile = ELFFile<ELF64LE>;
401 using ELF32BEFile = ELFFile<ELF32BE>;
402 using ELF64BEFile = ELFFile<ELF64BE>;
403
404 template <class ELFT>
405 inline Expected<const typename ELFT::Shdr *>
getSection(typename ELFT::ShdrRange Sections,uint32_t Index)406 getSection(typename ELFT::ShdrRange Sections, uint32_t Index) {
407 if (Index >= Sections.size())
408 return createError("invalid section index: " + Twine(Index));
409 return &Sections[Index];
410 }
411
412 template <class ELFT>
413 inline Expected<uint32_t>
getExtendedSymbolTableIndex(const typename ELFT::Sym & Sym,unsigned SymIndex,DataRegion<typename ELFT::Word> ShndxTable)414 getExtendedSymbolTableIndex(const typename ELFT::Sym &Sym, unsigned SymIndex,
415 DataRegion<typename ELFT::Word> ShndxTable) {
416 assert(Sym.st_shndx == ELF::SHN_XINDEX);
417 if (!ShndxTable.First)
418 return createError(
419 "found an extended symbol index (" + Twine(SymIndex) +
420 "), but unable to locate the extended symbol index table");
421
422 Expected<typename ELFT::Word> TableOrErr = ShndxTable[SymIndex];
423 if (!TableOrErr)
424 return createError("unable to read an extended symbol table at index " +
425 Twine(SymIndex) + ": " +
426 toString(TableOrErr.takeError()));
427 return *TableOrErr;
428 }
429
430 template <class ELFT>
431 Expected<uint32_t>
getSectionIndex(const Elf_Sym & Sym,Elf_Sym_Range Syms,DataRegion<Elf_Word> ShndxTable)432 ELFFile<ELFT>::getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
433 DataRegion<Elf_Word> ShndxTable) const {
434 uint32_t Index = Sym.st_shndx;
435 if (Index == ELF::SHN_XINDEX) {
436 Expected<uint32_t> ErrorOrIndex =
437 getExtendedSymbolTableIndex<ELFT>(Sym, &Sym - Syms.begin(), ShndxTable);
438 if (!ErrorOrIndex)
439 return ErrorOrIndex.takeError();
440 return *ErrorOrIndex;
441 }
442 if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
443 return 0;
444 return Index;
445 }
446
447 template <class ELFT>
448 Expected<const typename ELFT::Shdr *>
getSection(const Elf_Sym & Sym,const Elf_Shdr * SymTab,DataRegion<Elf_Word> ShndxTable)449 ELFFile<ELFT>::getSection(const Elf_Sym &Sym, const Elf_Shdr *SymTab,
450 DataRegion<Elf_Word> ShndxTable) const {
451 auto SymsOrErr = symbols(SymTab);
452 if (!SymsOrErr)
453 return SymsOrErr.takeError();
454 return getSection(Sym, *SymsOrErr, ShndxTable);
455 }
456
457 template <class ELFT>
458 Expected<const typename ELFT::Shdr *>
getSection(const Elf_Sym & Sym,Elf_Sym_Range Symbols,DataRegion<Elf_Word> ShndxTable)459 ELFFile<ELFT>::getSection(const Elf_Sym &Sym, Elf_Sym_Range Symbols,
460 DataRegion<Elf_Word> ShndxTable) const {
461 auto IndexOrErr = getSectionIndex(Sym, Symbols, ShndxTable);
462 if (!IndexOrErr)
463 return IndexOrErr.takeError();
464 uint32_t Index = *IndexOrErr;
465 if (Index == 0)
466 return nullptr;
467 return getSection(Index);
468 }
469
470 template <class ELFT>
471 Expected<const typename ELFT::Sym *>
getSymbol(const Elf_Shdr * Sec,uint32_t Index)472 ELFFile<ELFT>::getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
473 auto SymsOrErr = symbols(Sec);
474 if (!SymsOrErr)
475 return SymsOrErr.takeError();
476
477 Elf_Sym_Range Symbols = *SymsOrErr;
478 if (Index >= Symbols.size())
479 return createError("unable to get symbol from section " +
480 getSecIndexForError(*this, *Sec) +
481 ": invalid symbol index (" + Twine(Index) + ")");
482 return &Symbols[Index];
483 }
484
485 template <class ELFT>
486 template <typename T>
487 Expected<ArrayRef<T>>
getSectionContentsAsArray(const Elf_Shdr & Sec)488 ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr &Sec) const {
489 if (Sec.sh_entsize != sizeof(T) && sizeof(T) != 1)
490 return createError("section " + getSecIndexForError(*this, Sec) +
491 " has invalid sh_entsize: expected " + Twine(sizeof(T)) +
492 ", but got " + Twine(Sec.sh_entsize));
493
494 uintX_t Offset = Sec.sh_offset;
495 uintX_t Size = Sec.sh_size;
496
497 if (Size % sizeof(T))
498 return createError("section " + getSecIndexForError(*this, Sec) +
499 " has an invalid sh_size (" + Twine(Size) +
500 ") which is not a multiple of its sh_entsize (" +
501 Twine(Sec.sh_entsize) + ")");
502 if (std::numeric_limits<uintX_t>::max() - Offset < Size)
503 return createError("section " + getSecIndexForError(*this, Sec) +
504 " has a sh_offset (0x" + Twine::utohexstr(Offset) +
505 ") + sh_size (0x" + Twine::utohexstr(Size) +
506 ") that cannot be represented");
507 if (Offset + Size > Buf.size())
508 return createError("section " + getSecIndexForError(*this, Sec) +
509 " has a sh_offset (0x" + Twine::utohexstr(Offset) +
510 ") + sh_size (0x" + Twine::utohexstr(Size) +
511 ") that is greater than the file size (0x" +
512 Twine::utohexstr(Buf.size()) + ")");
513
514 if (Offset % alignof(T))
515 // TODO: this error is untested.
516 return createError("unaligned data");
517
518 const T *Start = reinterpret_cast<const T *>(base() + Offset);
519 return ArrayRef(Start, Size / sizeof(T));
520 }
521
522 template <class ELFT>
523 Expected<ArrayRef<uint8_t>>
getSegmentContents(const Elf_Phdr & Phdr)524 ELFFile<ELFT>::getSegmentContents(const Elf_Phdr &Phdr) const {
525 uintX_t Offset = Phdr.p_offset;
526 uintX_t Size = Phdr.p_filesz;
527
528 if (std::numeric_limits<uintX_t>::max() - Offset < Size)
529 return createError("program header " + getPhdrIndexForError(*this, Phdr) +
530 " has a p_offset (0x" + Twine::utohexstr(Offset) +
531 ") + p_filesz (0x" + Twine::utohexstr(Size) +
532 ") that cannot be represented");
533 if (Offset + Size > Buf.size())
534 return createError("program header " + getPhdrIndexForError(*this, Phdr) +
535 " has a p_offset (0x" + Twine::utohexstr(Offset) +
536 ") + p_filesz (0x" + Twine::utohexstr(Size) +
537 ") that is greater than the file size (0x" +
538 Twine::utohexstr(Buf.size()) + ")");
539 return ArrayRef(base() + Offset, Size);
540 }
541
542 template <class ELFT>
543 Expected<ArrayRef<uint8_t>>
getSectionContents(const Elf_Shdr & Sec)544 ELFFile<ELFT>::getSectionContents(const Elf_Shdr &Sec) const {
545 return getSectionContentsAsArray<uint8_t>(Sec);
546 }
547
548 template <class ELFT>
getRelocationTypeName(uint32_t Type)549 StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
550 return getELFRelocationTypeName(getHeader().e_machine, Type);
551 }
552
553 template <class ELFT>
getRelocationTypeName(uint32_t Type,SmallVectorImpl<char> & Result)554 void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
555 SmallVectorImpl<char> &Result) const {
556 if (!isMipsELF64()) {
557 StringRef Name = getRelocationTypeName(Type);
558 Result.append(Name.begin(), Name.end());
559 } else {
560 // The Mips N64 ABI allows up to three operations to be specified per
561 // relocation record. Unfortunately there's no easy way to test for the
562 // presence of N64 ELFs as they have no special flag that identifies them
563 // as being N64. We can safely assume at the moment that all Mips
564 // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
565 // information to disambiguate between old vs new ABIs.
566 uint8_t Type1 = (Type >> 0) & 0xFF;
567 uint8_t Type2 = (Type >> 8) & 0xFF;
568 uint8_t Type3 = (Type >> 16) & 0xFF;
569
570 // Concat all three relocation type names.
571 StringRef Name = getRelocationTypeName(Type1);
572 Result.append(Name.begin(), Name.end());
573
574 Name = getRelocationTypeName(Type2);
575 Result.append(1, '/');
576 Result.append(Name.begin(), Name.end());
577
578 Name = getRelocationTypeName(Type3);
579 Result.append(1, '/');
580 Result.append(Name.begin(), Name.end());
581 }
582 }
583
584 template <class ELFT>
getRelativeRelocationType()585 uint32_t ELFFile<ELFT>::getRelativeRelocationType() const {
586 return getELFRelativeRelocationType(getHeader().e_machine);
587 }
588
589 template <class ELFT>
590 Expected<SmallVector<std::optional<VersionEntry>, 0>>
loadVersionMap(const Elf_Shdr * VerNeedSec,const Elf_Shdr * VerDefSec)591 ELFFile<ELFT>::loadVersionMap(const Elf_Shdr *VerNeedSec,
592 const Elf_Shdr *VerDefSec) const {
593 SmallVector<std::optional<VersionEntry>, 0> VersionMap;
594
595 // The first two version indexes are reserved.
596 // Index 0 is VER_NDX_LOCAL, index 1 is VER_NDX_GLOBAL.
597 VersionMap.push_back(VersionEntry());
598 VersionMap.push_back(VersionEntry());
599
600 auto InsertEntry = [&](unsigned N, StringRef Version, bool IsVerdef) {
601 if (N >= VersionMap.size())
602 VersionMap.resize(N + 1);
603 VersionMap[N] = {std::string(Version), IsVerdef};
604 };
605
606 if (VerDefSec) {
607 Expected<std::vector<VerDef>> Defs = getVersionDefinitions(*VerDefSec);
608 if (!Defs)
609 return Defs.takeError();
610 for (const VerDef &Def : *Defs)
611 InsertEntry(Def.Ndx & ELF::VERSYM_VERSION, Def.Name, true);
612 }
613
614 if (VerNeedSec) {
615 Expected<std::vector<VerNeed>> Deps = getVersionDependencies(*VerNeedSec);
616 if (!Deps)
617 return Deps.takeError();
618 for (const VerNeed &Dep : *Deps)
619 for (const VernAux &Aux : Dep.AuxV)
620 InsertEntry(Aux.Other & ELF::VERSYM_VERSION, Aux.Name, false);
621 }
622
623 return VersionMap;
624 }
625
626 template <class ELFT>
627 Expected<const typename ELFT::Sym *>
getRelocationSymbol(const Elf_Rel & Rel,const Elf_Shdr * SymTab)628 ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel &Rel,
629 const Elf_Shdr *SymTab) const {
630 uint32_t Index = Rel.getSymbol(isMips64EL());
631 if (Index == 0)
632 return nullptr;
633 return getEntry<Elf_Sym>(*SymTab, Index);
634 }
635
636 template <class ELFT>
637 Expected<StringRef>
getSectionStringTable(Elf_Shdr_Range Sections,WarningHandler WarnHandler)638 ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections,
639 WarningHandler WarnHandler) const {
640 uint32_t Index = getHeader().e_shstrndx;
641 if (Index == ELF::SHN_XINDEX) {
642 // If the section name string table section index is greater than
643 // or equal to SHN_LORESERVE, then the actual index of the section name
644 // string table section is contained in the sh_link field of the section
645 // header at index 0.
646 if (Sections.empty())
647 return createError(
648 "e_shstrndx == SHN_XINDEX, but the section header table is empty");
649
650 Index = Sections[0].sh_link;
651 }
652
653 // There is no section name string table. Return FakeSectionStrings which
654 // is non-empty if we have created fake sections.
655 if (!Index)
656 return FakeSectionStrings;
657
658 if (Index >= Sections.size())
659 return createError("section header string table index " + Twine(Index) +
660 " does not exist");
661 return getStringTable(Sections[Index], WarnHandler);
662 }
663
664 /// This function finds the number of dynamic symbols using a GNU hash table.
665 ///
666 /// @param Table The GNU hash table for .dynsym.
667 template <class ELFT>
668 static Expected<uint64_t>
getDynSymtabSizeFromGnuHash(const typename ELFT::GnuHash & Table,const void * BufEnd)669 getDynSymtabSizeFromGnuHash(const typename ELFT::GnuHash &Table,
670 const void *BufEnd) {
671 using Elf_Word = typename ELFT::Word;
672 if (Table.nbuckets == 0)
673 return Table.symndx + 1;
674 uint64_t LastSymIdx = 0;
675 // Find the index of the first symbol in the last chain.
676 for (Elf_Word Val : Table.buckets())
677 LastSymIdx = std::max(LastSymIdx, (uint64_t)Val);
678 const Elf_Word *It =
679 reinterpret_cast<const Elf_Word *>(Table.values(LastSymIdx).end());
680 // Locate the end of the chain to find the last symbol index.
681 while (It < BufEnd && (*It & 1) == 0) {
682 ++LastSymIdx;
683 ++It;
684 }
685 if (It >= BufEnd) {
686 return createStringError(
687 object_error::parse_failed,
688 "no terminator found for GNU hash section before buffer end");
689 }
690 return LastSymIdx + 1;
691 }
692
693 /// This function determines the number of dynamic symbols. It reads section
694 /// headers first. If section headers are not available, the number of
695 /// symbols will be inferred by parsing dynamic hash tables.
696 template <class ELFT>
getDynSymtabSize()697 Expected<uint64_t> ELFFile<ELFT>::getDynSymtabSize() const {
698 // Read .dynsym section header first if available.
699 Expected<Elf_Shdr_Range> SectionsOrError = sections();
700 if (!SectionsOrError)
701 return SectionsOrError.takeError();
702 for (const Elf_Shdr &Sec : *SectionsOrError) {
703 if (Sec.sh_type == ELF::SHT_DYNSYM) {
704 if (Sec.sh_size % Sec.sh_entsize != 0) {
705 return createStringError(object_error::parse_failed,
706 "SHT_DYNSYM section has sh_size (" +
707 Twine(Sec.sh_size) + ") % sh_entsize (" +
708 Twine(Sec.sh_entsize) + ") that is not 0");
709 }
710 return Sec.sh_size / Sec.sh_entsize;
711 }
712 }
713
714 if (!SectionsOrError->empty()) {
715 // Section headers are available but .dynsym header is not found.
716 // Return 0 as .dynsym does not exist.
717 return 0;
718 }
719
720 // Section headers do not exist. Falling back to infer
721 // upper bound of .dynsym from .gnu.hash and .hash.
722 Expected<Elf_Dyn_Range> DynTable = dynamicEntries();
723 if (!DynTable)
724 return DynTable.takeError();
725 std::optional<uint64_t> ElfHash;
726 std::optional<uint64_t> ElfGnuHash;
727 for (const Elf_Dyn &Entry : *DynTable) {
728 switch (Entry.d_tag) {
729 case ELF::DT_HASH:
730 ElfHash = Entry.d_un.d_ptr;
731 break;
732 case ELF::DT_GNU_HASH:
733 ElfGnuHash = Entry.d_un.d_ptr;
734 break;
735 }
736 }
737 if (ElfGnuHash) {
738 Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfGnuHash);
739 if (!TablePtr)
740 return TablePtr.takeError();
741 const Elf_GnuHash *Table =
742 reinterpret_cast<const Elf_GnuHash *>(TablePtr.get());
743 return getDynSymtabSizeFromGnuHash<ELFT>(*Table, this->Buf.bytes_end());
744 }
745
746 // Search SYSV hash table to try to find the upper bound of dynsym.
747 if (ElfHash) {
748 Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfHash);
749 if (!TablePtr)
750 return TablePtr.takeError();
751 const Elf_Hash *Table = reinterpret_cast<const Elf_Hash *>(TablePtr.get());
752 return Table->nchain;
753 }
754 return 0;
755 }
756
ELFFile(StringRef Object)757 template <class ELFT> ELFFile<ELFT>::ELFFile(StringRef Object) : Buf(Object) {}
758
759 template <class ELFT>
create(StringRef Object)760 Expected<ELFFile<ELFT>> ELFFile<ELFT>::create(StringRef Object) {
761 if (sizeof(Elf_Ehdr) > Object.size())
762 return createError("invalid buffer: the size (" + Twine(Object.size()) +
763 ") is smaller than an ELF header (" +
764 Twine(sizeof(Elf_Ehdr)) + ")");
765 return ELFFile(Object);
766 }
767
768 /// Used by llvm-objdump -d (which needs sections for disassembly) to
769 /// disassemble objects without a section header table (e.g. ET_CORE objects
770 /// analyzed by linux perf or ET_EXEC with llvm-strip --strip-sections).
createFakeSections()771 template <class ELFT> void ELFFile<ELFT>::createFakeSections() {
772 if (!FakeSections.empty())
773 return;
774 auto PhdrsOrErr = program_headers();
775 if (!PhdrsOrErr)
776 return;
777
778 FakeSectionStrings += '\0';
779 for (auto [Idx, Phdr] : llvm::enumerate(*PhdrsOrErr)) {
780 if (Phdr.p_type != ELF::PT_LOAD || !(Phdr.p_flags & ELF::PF_X))
781 continue;
782 Elf_Shdr FakeShdr = {};
783 FakeShdr.sh_type = ELF::SHT_PROGBITS;
784 FakeShdr.sh_flags = ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
785 FakeShdr.sh_addr = Phdr.p_vaddr;
786 FakeShdr.sh_size = Phdr.p_memsz;
787 FakeShdr.sh_offset = Phdr.p_offset;
788 // Create a section name based on the p_type and index.
789 FakeShdr.sh_name = FakeSectionStrings.size();
790 FakeSectionStrings += ("PT_LOAD#" + Twine(Idx)).str();
791 FakeSectionStrings += '\0';
792 FakeSections.push_back(FakeShdr);
793 }
794 }
795
796 template <class ELFT>
sections()797 Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
798 const uintX_t SectionTableOffset = getHeader().e_shoff;
799 if (SectionTableOffset == 0) {
800 if (!FakeSections.empty())
801 return ArrayRef(FakeSections.data(), FakeSections.size());
802 return ArrayRef<Elf_Shdr>();
803 }
804
805 if (getHeader().e_shentsize != sizeof(Elf_Shdr))
806 return createError("invalid e_shentsize in ELF header: " +
807 Twine(getHeader().e_shentsize));
808
809 const uint64_t FileSize = Buf.size();
810 if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize ||
811 SectionTableOffset + (uintX_t)sizeof(Elf_Shdr) < SectionTableOffset)
812 return createError(
813 "section header table goes past the end of the file: e_shoff = 0x" +
814 Twine::utohexstr(SectionTableOffset));
815
816 // Invalid address alignment of section headers
817 if (SectionTableOffset & (alignof(Elf_Shdr) - 1))
818 // TODO: this error is untested.
819 return createError("invalid alignment of section headers");
820
821 const Elf_Shdr *First =
822 reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
823
824 uintX_t NumSections = getHeader().e_shnum;
825 if (NumSections == 0)
826 NumSections = First->sh_size;
827
828 if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
829 return createError("invalid number of sections specified in the NULL "
830 "section's sh_size field (" +
831 Twine(NumSections) + ")");
832
833 const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
834 if (SectionTableOffset + SectionTableSize < SectionTableOffset)
835 return createError(
836 "invalid section header table offset (e_shoff = 0x" +
837 Twine::utohexstr(SectionTableOffset) +
838 ") or invalid number of sections specified in the first section "
839 "header's sh_size field (0x" +
840 Twine::utohexstr(NumSections) + ")");
841
842 // Section table goes past end of file!
843 if (SectionTableOffset + SectionTableSize > FileSize)
844 return createError("section table goes past the end of file");
845 return ArrayRef(First, NumSections);
846 }
847
848 template <class ELFT>
849 template <typename T>
getEntry(uint32_t Section,uint32_t Entry)850 Expected<const T *> ELFFile<ELFT>::getEntry(uint32_t Section,
851 uint32_t Entry) const {
852 auto SecOrErr = getSection(Section);
853 if (!SecOrErr)
854 return SecOrErr.takeError();
855 return getEntry<T>(**SecOrErr, Entry);
856 }
857
858 template <class ELFT>
859 template <typename T>
getEntry(const Elf_Shdr & Section,uint32_t Entry)860 Expected<const T *> ELFFile<ELFT>::getEntry(const Elf_Shdr &Section,
861 uint32_t Entry) const {
862 Expected<ArrayRef<T>> EntriesOrErr = getSectionContentsAsArray<T>(Section);
863 if (!EntriesOrErr)
864 return EntriesOrErr.takeError();
865
866 ArrayRef<T> Arr = *EntriesOrErr;
867 if (Entry >= Arr.size())
868 return createError(
869 "can't read an entry at 0x" +
870 Twine::utohexstr(Entry * static_cast<uint64_t>(sizeof(T))) +
871 ": it goes past the end of the section (0x" +
872 Twine::utohexstr(Section.sh_size) + ")");
873 return &Arr[Entry];
874 }
875
876 template <typename ELFT>
getSymbolVersionByIndex(uint32_t SymbolVersionIndex,bool & IsDefault,SmallVector<std::optional<VersionEntry>,0> & VersionMap,std::optional<bool> IsSymHidden)877 Expected<StringRef> ELFFile<ELFT>::getSymbolVersionByIndex(
878 uint32_t SymbolVersionIndex, bool &IsDefault,
879 SmallVector<std::optional<VersionEntry>, 0> &VersionMap,
880 std::optional<bool> IsSymHidden) const {
881 size_t VersionIndex = SymbolVersionIndex & llvm::ELF::VERSYM_VERSION;
882
883 // Special markers for unversioned symbols.
884 if (VersionIndex == llvm::ELF::VER_NDX_LOCAL ||
885 VersionIndex == llvm::ELF::VER_NDX_GLOBAL) {
886 IsDefault = false;
887 return "";
888 }
889
890 // Lookup this symbol in the version table.
891 if (VersionIndex >= VersionMap.size() || !VersionMap[VersionIndex])
892 return createError("SHT_GNU_versym section refers to a version index " +
893 Twine(VersionIndex) + " which is missing");
894
895 const VersionEntry &Entry = *VersionMap[VersionIndex];
896 // A default version (@@) is only available for defined symbols.
897 if (!Entry.IsVerDef || IsSymHidden.value_or(false))
898 IsDefault = false;
899 else
900 IsDefault = !(SymbolVersionIndex & llvm::ELF::VERSYM_HIDDEN);
901 return Entry.Name.c_str();
902 }
903
904 template <class ELFT>
905 Expected<std::vector<VerDef>>
getVersionDefinitions(const Elf_Shdr & Sec)906 ELFFile<ELFT>::getVersionDefinitions(const Elf_Shdr &Sec) const {
907 Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
908 if (!StrTabOrErr)
909 return StrTabOrErr.takeError();
910
911 Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
912 if (!ContentsOrErr)
913 return createError("cannot read content of " + describe(*this, Sec) + ": " +
914 toString(ContentsOrErr.takeError()));
915
916 const uint8_t *Start = ContentsOrErr->data();
917 const uint8_t *End = Start + ContentsOrErr->size();
918
919 auto ExtractNextAux = [&](const uint8_t *&VerdauxBuf,
920 unsigned VerDefNdx) -> Expected<VerdAux> {
921 if (VerdauxBuf + sizeof(Elf_Verdaux) > End)
922 return createError("invalid " + describe(*this, Sec) +
923 ": version definition " + Twine(VerDefNdx) +
924 " refers to an auxiliary entry that goes past the end "
925 "of the section");
926
927 auto *Verdaux = reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
928 VerdauxBuf += Verdaux->vda_next;
929
930 VerdAux Aux;
931 Aux.Offset = VerdauxBuf - Start;
932 if (Verdaux->vda_name <= StrTabOrErr->size())
933 Aux.Name = std::string(StrTabOrErr->drop_front(Verdaux->vda_name));
934 else
935 Aux.Name = ("<invalid vda_name: " + Twine(Verdaux->vda_name) + ">").str();
936 return Aux;
937 };
938
939 std::vector<VerDef> Ret;
940 const uint8_t *VerdefBuf = Start;
941 for (unsigned I = 1; I <= /*VerDefsNum=*/Sec.sh_info; ++I) {
942 if (VerdefBuf + sizeof(Elf_Verdef) > End)
943 return createError("invalid " + describe(*this, Sec) +
944 ": version definition " + Twine(I) +
945 " goes past the end of the section");
946
947 if (reinterpret_cast<uintptr_t>(VerdefBuf) % sizeof(uint32_t) != 0)
948 return createError(
949 "invalid " + describe(*this, Sec) +
950 ": found a misaligned version definition entry at offset 0x" +
951 Twine::utohexstr(VerdefBuf - Start));
952
953 unsigned Version = *reinterpret_cast<const Elf_Half *>(VerdefBuf);
954 if (Version != 1)
955 return createError("unable to dump " + describe(*this, Sec) +
956 ": version " + Twine(Version) +
957 " is not yet supported");
958
959 const Elf_Verdef *D = reinterpret_cast<const Elf_Verdef *>(VerdefBuf);
960 VerDef &VD = *Ret.emplace(Ret.end());
961 VD.Offset = VerdefBuf - Start;
962 VD.Version = D->vd_version;
963 VD.Flags = D->vd_flags;
964 VD.Ndx = D->vd_ndx;
965 VD.Cnt = D->vd_cnt;
966 VD.Hash = D->vd_hash;
967
968 const uint8_t *VerdauxBuf = VerdefBuf + D->vd_aux;
969 for (unsigned J = 0; J < D->vd_cnt; ++J) {
970 if (reinterpret_cast<uintptr_t>(VerdauxBuf) % sizeof(uint32_t) != 0)
971 return createError("invalid " + describe(*this, Sec) +
972 ": found a misaligned auxiliary entry at offset 0x" +
973 Twine::utohexstr(VerdauxBuf - Start));
974
975 Expected<VerdAux> AuxOrErr = ExtractNextAux(VerdauxBuf, I);
976 if (!AuxOrErr)
977 return AuxOrErr.takeError();
978
979 if (J == 0)
980 VD.Name = AuxOrErr->Name;
981 else
982 VD.AuxV.push_back(*AuxOrErr);
983 }
984
985 VerdefBuf += D->vd_next;
986 }
987
988 return Ret;
989 }
990
991 template <class ELFT>
992 Expected<std::vector<VerNeed>>
getVersionDependencies(const Elf_Shdr & Sec,WarningHandler WarnHandler)993 ELFFile<ELFT>::getVersionDependencies(const Elf_Shdr &Sec,
994 WarningHandler WarnHandler) const {
995 StringRef StrTab;
996 Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
997 if (!StrTabOrErr) {
998 if (Error E = WarnHandler(toString(StrTabOrErr.takeError())))
999 return std::move(E);
1000 } else {
1001 StrTab = *StrTabOrErr;
1002 }
1003
1004 Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
1005 if (!ContentsOrErr)
1006 return createError("cannot read content of " + describe(*this, Sec) + ": " +
1007 toString(ContentsOrErr.takeError()));
1008
1009 const uint8_t *Start = ContentsOrErr->data();
1010 const uint8_t *End = Start + ContentsOrErr->size();
1011 const uint8_t *VerneedBuf = Start;
1012
1013 std::vector<VerNeed> Ret;
1014 for (unsigned I = 1; I <= /*VerneedNum=*/Sec.sh_info; ++I) {
1015 if (VerneedBuf + sizeof(Elf_Verdef) > End)
1016 return createError("invalid " + describe(*this, Sec) +
1017 ": version dependency " + Twine(I) +
1018 " goes past the end of the section");
1019
1020 if (reinterpret_cast<uintptr_t>(VerneedBuf) % sizeof(uint32_t) != 0)
1021 return createError(
1022 "invalid " + describe(*this, Sec) +
1023 ": found a misaligned version dependency entry at offset 0x" +
1024 Twine::utohexstr(VerneedBuf - Start));
1025
1026 unsigned Version = *reinterpret_cast<const Elf_Half *>(VerneedBuf);
1027 if (Version != 1)
1028 return createError("unable to dump " + describe(*this, Sec) +
1029 ": version " + Twine(Version) +
1030 " is not yet supported");
1031
1032 const Elf_Verneed *Verneed =
1033 reinterpret_cast<const Elf_Verneed *>(VerneedBuf);
1034
1035 VerNeed &VN = *Ret.emplace(Ret.end());
1036 VN.Version = Verneed->vn_version;
1037 VN.Cnt = Verneed->vn_cnt;
1038 VN.Offset = VerneedBuf - Start;
1039
1040 if (Verneed->vn_file < StrTab.size())
1041 VN.File = std::string(StrTab.data() + Verneed->vn_file);
1042 else
1043 VN.File = ("<corrupt vn_file: " + Twine(Verneed->vn_file) + ">").str();
1044
1045 const uint8_t *VernauxBuf = VerneedBuf + Verneed->vn_aux;
1046 for (unsigned J = 0; J < Verneed->vn_cnt; ++J) {
1047 if (reinterpret_cast<uintptr_t>(VernauxBuf) % sizeof(uint32_t) != 0)
1048 return createError("invalid " + describe(*this, Sec) +
1049 ": found a misaligned auxiliary entry at offset 0x" +
1050 Twine::utohexstr(VernauxBuf - Start));
1051
1052 if (VernauxBuf + sizeof(Elf_Vernaux) > End)
1053 return createError(
1054 "invalid " + describe(*this, Sec) + ": version dependency " +
1055 Twine(I) +
1056 " refers to an auxiliary entry that goes past the end "
1057 "of the section");
1058
1059 const Elf_Vernaux *Vernaux =
1060 reinterpret_cast<const Elf_Vernaux *>(VernauxBuf);
1061
1062 VernAux &Aux = *VN.AuxV.emplace(VN.AuxV.end());
1063 Aux.Hash = Vernaux->vna_hash;
1064 Aux.Flags = Vernaux->vna_flags;
1065 Aux.Other = Vernaux->vna_other;
1066 Aux.Offset = VernauxBuf - Start;
1067 if (StrTab.size() <= Vernaux->vna_name)
1068 Aux.Name = "<corrupt>";
1069 else
1070 Aux.Name = std::string(StrTab.drop_front(Vernaux->vna_name));
1071
1072 VernauxBuf += Vernaux->vna_next;
1073 }
1074 VerneedBuf += Verneed->vn_next;
1075 }
1076 return Ret;
1077 }
1078
1079 template <class ELFT>
1080 Expected<const typename ELFT::Shdr *>
getSection(uint32_t Index)1081 ELFFile<ELFT>::getSection(uint32_t Index) const {
1082 auto TableOrErr = sections();
1083 if (!TableOrErr)
1084 return TableOrErr.takeError();
1085 return object::getSection<ELFT>(*TableOrErr, Index);
1086 }
1087
1088 template <class ELFT>
1089 Expected<StringRef>
getStringTable(const Elf_Shdr & Section,WarningHandler WarnHandler)1090 ELFFile<ELFT>::getStringTable(const Elf_Shdr &Section,
1091 WarningHandler WarnHandler) const {
1092 if (Section.sh_type != ELF::SHT_STRTAB)
1093 if (Error E = WarnHandler("invalid sh_type for string table section " +
1094 getSecIndexForError(*this, Section) +
1095 ": expected SHT_STRTAB, but got " +
1096 object::getELFSectionTypeName(
1097 getHeader().e_machine, Section.sh_type)))
1098 return std::move(E);
1099
1100 auto V = getSectionContentsAsArray<char>(Section);
1101 if (!V)
1102 return V.takeError();
1103 ArrayRef<char> Data = *V;
1104 if (Data.empty())
1105 return createError("SHT_STRTAB string table section " +
1106 getSecIndexForError(*this, Section) + " is empty");
1107 if (Data.back() != '\0')
1108 return createError("SHT_STRTAB string table section " +
1109 getSecIndexForError(*this, Section) +
1110 " is non-null terminated");
1111 return StringRef(Data.begin(), Data.size());
1112 }
1113
1114 template <class ELFT>
1115 Expected<ArrayRef<typename ELFT::Word>>
getSHNDXTable(const Elf_Shdr & Section)1116 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
1117 auto SectionsOrErr = sections();
1118 if (!SectionsOrErr)
1119 return SectionsOrErr.takeError();
1120 return getSHNDXTable(Section, *SectionsOrErr);
1121 }
1122
1123 template <class ELFT>
1124 Expected<ArrayRef<typename ELFT::Word>>
getSHNDXTable(const Elf_Shdr & Section,Elf_Shdr_Range Sections)1125 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section,
1126 Elf_Shdr_Range Sections) const {
1127 assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
1128 auto VOrErr = getSectionContentsAsArray<Elf_Word>(Section);
1129 if (!VOrErr)
1130 return VOrErr.takeError();
1131 ArrayRef<Elf_Word> V = *VOrErr;
1132 auto SymTableOrErr = object::getSection<ELFT>(Sections, Section.sh_link);
1133 if (!SymTableOrErr)
1134 return SymTableOrErr.takeError();
1135 const Elf_Shdr &SymTable = **SymTableOrErr;
1136 if (SymTable.sh_type != ELF::SHT_SYMTAB &&
1137 SymTable.sh_type != ELF::SHT_DYNSYM)
1138 return createError(
1139 "SHT_SYMTAB_SHNDX section is linked with " +
1140 object::getELFSectionTypeName(getHeader().e_machine, SymTable.sh_type) +
1141 " section (expected SHT_SYMTAB/SHT_DYNSYM)");
1142
1143 uint64_t Syms = SymTable.sh_size / sizeof(Elf_Sym);
1144 if (V.size() != Syms)
1145 return createError("SHT_SYMTAB_SHNDX has " + Twine(V.size()) +
1146 " entries, but the symbol table associated has " +
1147 Twine(Syms));
1148
1149 return V;
1150 }
1151
1152 template <class ELFT>
1153 Expected<StringRef>
getStringTableForSymtab(const Elf_Shdr & Sec)1154 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
1155 auto SectionsOrErr = sections();
1156 if (!SectionsOrErr)
1157 return SectionsOrErr.takeError();
1158 return getStringTableForSymtab(Sec, *SectionsOrErr);
1159 }
1160
1161 template <class ELFT>
1162 Expected<StringRef>
getStringTableForSymtab(const Elf_Shdr & Sec,Elf_Shdr_Range Sections)1163 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec,
1164 Elf_Shdr_Range Sections) const {
1165
1166 if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
1167 return createError(
1168 "invalid sh_type for symbol table, expected SHT_SYMTAB or SHT_DYNSYM");
1169 Expected<const Elf_Shdr *> SectionOrErr =
1170 object::getSection<ELFT>(Sections, Sec.sh_link);
1171 if (!SectionOrErr)
1172 return SectionOrErr.takeError();
1173 return getStringTable(**SectionOrErr);
1174 }
1175
1176 template <class ELFT>
1177 Expected<StringRef>
getLinkAsStrtab(const typename ELFT::Shdr & Sec)1178 ELFFile<ELFT>::getLinkAsStrtab(const typename ELFT::Shdr &Sec) const {
1179 Expected<const typename ELFT::Shdr *> StrTabSecOrErr =
1180 getSection(Sec.sh_link);
1181 if (!StrTabSecOrErr)
1182 return createError("invalid section linked to " + describe(*this, Sec) +
1183 ": " + toString(StrTabSecOrErr.takeError()));
1184
1185 Expected<StringRef> StrTabOrErr = getStringTable(**StrTabSecOrErr);
1186 if (!StrTabOrErr)
1187 return createError("invalid string table linked to " +
1188 describe(*this, Sec) + ": " +
1189 toString(StrTabOrErr.takeError()));
1190 return *StrTabOrErr;
1191 }
1192
1193 template <class ELFT>
1194 Expected<StringRef>
getSectionName(const Elf_Shdr & Section,WarningHandler WarnHandler)1195 ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
1196 WarningHandler WarnHandler) const {
1197 auto SectionsOrErr = sections();
1198 if (!SectionsOrErr)
1199 return SectionsOrErr.takeError();
1200 auto Table = getSectionStringTable(*SectionsOrErr, WarnHandler);
1201 if (!Table)
1202 return Table.takeError();
1203 return getSectionName(Section, *Table);
1204 }
1205
1206 template <class ELFT>
getSectionName(const Elf_Shdr & Section,StringRef DotShstrtab)1207 Expected<StringRef> ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
1208 StringRef DotShstrtab) const {
1209 uint32_t Offset = Section.sh_name;
1210 if (Offset == 0)
1211 return StringRef();
1212 if (Offset >= DotShstrtab.size())
1213 return createError("a section " + getSecIndexForError(*this, Section) +
1214 " has an invalid sh_name (0x" +
1215 Twine::utohexstr(Offset) +
1216 ") offset which goes past the end of the "
1217 "section name string table");
1218 return StringRef(DotShstrtab.data() + Offset);
1219 }
1220
1221 /// This function returns the hash value for a symbol in the .dynsym section
1222 /// Name of the API remains consistent as specified in the libelf
1223 /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
hashSysV(StringRef SymbolName)1224 inline unsigned hashSysV(StringRef SymbolName) {
1225 unsigned h = 0, g;
1226 for (char C : SymbolName) {
1227 h = (h << 4) + C;
1228 g = h & 0xf0000000L;
1229 if (g != 0)
1230 h ^= g >> 24;
1231 h &= ~g;
1232 }
1233 return h;
1234 }
1235
1236 /// This function returns the hash value for a symbol in the .dynsym section
1237 /// for the GNU hash table. The implementation is defined in the GNU hash ABI.
1238 /// REF : https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elf.c#l222
hashGnu(StringRef Name)1239 inline uint32_t hashGnu(StringRef Name) {
1240 uint32_t H = 5381;
1241 for (uint8_t C : Name)
1242 H = (H << 5) + H + C;
1243 return H;
1244 }
1245
1246 } // end namespace object
1247 } // end namespace llvm
1248
1249 #endif // LLVM_OBJECT_ELF_H
1250