git@UCC - tpg/acess2.git/blob - Usermode/Libraries/ld-acess.so

29 //static const char *csaDT_NAMES[] = {"DT_NULL", "DT_NEEDED", "DT_PLTRELSZ", "DT_PLTGOT", "DT_HASH", "DT_STRTAB", "DT_SYMTAB", "DT_RELA", "DT_RELASZ", "DT_RELAENT", "DT_STRSZ", "DT_SYMENT", "DT_INIT", "DT_FINI", "DT_SONAME", "DT_RPATH", "DT_SYMBOLIC", "DT_REL", "DT_RELSZ", "DT_RELENT", "DT_PLTREL", "DT_DEBUG", "DT_TEXTREL", "DT_JMPREL"};

30 static const char *csaR_NAMES[] = {"R_386_NONE", "R_386_32", "R_386_PC32", "R_386_GOT32", "R_386_PLT32", "R_386_COPY", "R_386_GLOB_DAT", "R_386_JMP_SLOT", "R_386_RELATIVE", "R_386_GOTOFF", "R_386_GOTPC", "R_386_LAST"};

31 #endif

32

33 // === PROTOTYPES ===

34 void *ElfRelocate(void *Base, char **envp, const char *Filename);

35 int ElfGetSymbol(void *Base, const char *Name, void **Ret, size_t *Size);

36 void *Elf32Relocate(void *Base, char **envp, const char *Filename);

37 int Elf32GetSymbol(void *Base, const char *Name, void **Ret, size_t *Size);

38 void elf_doRelocate_386(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff);

39 void elf_doRelocate_arm(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff);

40 #ifdef SUPPORT_ELF64

41 void *Elf64Relocate(void *Base, char **envp, const char *Filename);

42 int Elf64GetSymbol(void *Base, const char *Name, void **Ret, size_t *Size);

43 #endif

44 uint32_t ElfHashString(const char *name);

45

46 // === CODE ===

47 /**

48 * \fn int ElfRelocate(void *Base, char **envp, const char *Filename)

49 * \brief Relocates a loaded ELF Executable

50 */

51 void *ElfRelocate(void *Base, char **envp, const char *Filename)

52 {

53 Elf32_Ehdr *hdr = Base;

54

55 switch(hdr->e_ident[4])

56 {

57 case ELFCLASS32:

58 return Elf32Relocate(Base, envp, Filename);

59 #ifdef SUPPORT_ELF64

60 case ELFCLASS64:

61 return Elf64Relocate(Base, envp, Filename);

62 #endif

63 default:

64 SysDebug("ld-acess - ElfRelocate: Unknown file class %i", hdr->e_ident[4]);

65 return NULL;

66 }

67 }

68

69 /**

70 * \fn int ElfGetSymbol(Uint Base, const char *name, void **ret)

71 */

72 int ElfGetSymbol(void *Base, const char *Name, void **ret, size_t *Size)

73 {

74 Elf32_Ehdr *hdr = Base;

75

76 switch(hdr->e_ident[4])

77 {

78 case ELFCLASS32:

79 return Elf32GetSymbol(Base, Name, ret, Size);

80 #ifdef SUPPORT_ELF64

81 case ELFCLASS64:

82 return Elf64GetSymbol(Base, Name, ret, Size);

83 #endif

84 default:

85 SysDebug("ld-acess - ElfRelocate: Unknown file class %i", hdr->e_ident[4]);

86 return 0;

87 }

88 }

89

90 void elf_doRelocate_386(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff)

91 {

92 intptr_t val;

93 switch( type )

94 {

95 // Standard 32 Bit Relocation (S+A)

96 case R_386_32:

97 val = (intptr_t) GetSymbol(Sym, NULL);

98 DEBUGS(" elf_doRelocate: R_386_32 *0x%x += 0x%x('%s')",

99 ptr, val, Sym);

100 *ptr = val + addend;

101 break;

102

103 // 32 Bit Relocation wrt. Offset (S+A-P)

104 case R_386_PC32:

105 DEBUGS(" elf_doRelocate: '%s'", Sym);

106 val = (intptr_t) GetSymbol(Sym, NULL);

107 DEBUGS(" elf_doRelocate: R_386_PC32 *0x%x = 0x%x + 0x%x - 0x%x",

108 ptr, *ptr, val, (intptr_t)ptr );

109 *ptr = val + addend - (intptr_t)ptr;

110 //*ptr = val + addend - ((Uint)ptr - iBaseDiff);

111 break;

112

113 // Absolute Value of a symbol (S)

114 case R_386_GLOB_DAT:

115 case R_386_JMP_SLOT:

116 DEBUGS(" elf_doRelocate: '%s'", Sym);

117 val = (intptr_t) GetSymbol( Sym, NULL );

118 DEBUGS(" elf_doRelocate: %s *0x%x = 0x%x", csaR_NAMES[type], ptr, val);

119 *ptr = val;

120 break;

121

122 // Base Address (B+A)

123 case R_386_RELATIVE:

124 DEBUGS(" elf_doRelocate: R_386_RELATIVE *0x%x = 0x%x + 0x%x", ptr, iBaseDiff, addend);

125 *ptr = iBaseDiff + addend;

126 break;

127

128 case R_386_COPY: {

129 size_t size;

130 void *src = GetSymbol(Sym, &size);

131 DEBUGS(" elf_doRelocate_386: R_386_COPY (%p, %p, %i)", ptr, src, size);

132 memcpy(ptr, src, size);

133 break; }

134

135 default:

136 SysDebug("elf_doRelocate_386: Unknown relocation %i", type);

137 break;

138 }

139 }

140

141 void elf_doRelocate_arm(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff)

142 {

143 uint32_t val;

144 switch(type)

145 {

146 // (S + A) | T

147 case R_ARM_ABS32:

148 DEBUGS(" elf_doRelocate_arm: R_ARM_ABS32 %p (%s + %x)", ptr, Sym, addend);

149 val = (intptr_t)GetSymbol(Sym, NULL);

150 *ptr = val + addend;

151 break;

152 case R_ARM_GLOB_DAT:

153 DEBUGS(" elf_doRelocate_arm: R_ARM_GLOB_DAT %p (%s + %x)", ptr, Sym, addend);

154 val = (intptr_t)GetSymbol(Sym, NULL);

155 *ptr = val + addend;

156 break;

157 case R_ARM_JUMP_SLOT:

158 if(!bRela) addend = 0;

159 DEBUGS(" elf_doRelocate_arm: R_ARM_JUMP_SLOT %p (%s + %x)", ptr, Sym, addend);

160 val = (intptr_t)GetSymbol(Sym, NULL);

161 *ptr = val + addend;

162 break;

163 // Copy

164 case R_ARM_COPY: {

165 size_t size;

166 void *src = GetSymbol(Sym, &size);

167 DEBUGS(" elf_doRelocate_arm: R_ARM_COPY (%p, %p, %i)", ptr, src, size);

168 memcpy(ptr, src, size);

169 break; }

170 // Delta between link and runtime locations + A

171 case R_ARM_RELATIVE:

172 if(Sym[0] != '\0') {

173 // TODO: Get delta for a symbol

174 SysDebug("elf_doRelocate_arm: TODO - Implment R_ARM_RELATIVE for symbols");

175 }

176 else {

177 *ptr = iBaseDiff + addend;

178 }

179 break;

180 default:

181 SysDebug("elf_doRelocate_arm: Unknown Relocation, %i", type);

182 break;

183 }

184 }

185

186 void *Elf32Relocate(void *Base, char **envp, const char *Filename)

187 {

188 Elf32_Ehdr *hdr = Base;

189 Elf32_Phdr *phtab;

190 int i, j; // Counters

191 char *libPath;

192 intptr_t iRealBase = -1;

193 intptr_t iBaseDiff;

194 int iSegmentCount;

195 // int iSymCount;

196 Elf32_Rel *rel = NULL;

197 Elf32_Rela *rela = NULL;

198 void *plt = NULL;

199 int relSz=0, relEntSz=8;

200 int relaSz=0, relaEntSz=8;

201 int pltSz=0, pltType=0;

202 Elf32_Dyn *dynamicTab = NULL; // Dynamic Table Pointer

203 char *dynstrtab = NULL; // .dynamic String Table

204 Elf32_Sym *dynsymtab;

205 void (*do_relocate)(uint32_t t_info, uint32_t *ptr, Elf32_Addr addend, int Type, int bRela, const char *Sym, intptr_t iBaseDiff);

206 auto void _doRelocate(uint32_t r_info, uint32_t *ptr, int bRela, Elf32_Addr addend);

207

208 DEBUGS("ElfRelocate: (Base=0x%x)", Base);

209

210 // Check magic header

211

212

213 // Parse Program Header to get Dynamic Table

214 phtab = (void*)( (uintptr_t)Base + hdr->phoff );

215 iSegmentCount = hdr->phentcount;

216 for(i=0;i<iSegmentCount;i++)

217 {

218 // Determine linked base address

219 if(phtab[i].Type == PT_LOAD && iRealBase > phtab[i].VAddr)

220 iRealBase = phtab[i].VAddr;

221

222 // Find Dynamic Section

223 if(phtab[i].Type == PT_DYNAMIC) {

224 if(dynamicTab) {

225 DEBUGS(" WARNING - elf_relocate: Multiple PT_DYNAMIC segments");

226 continue;

227 }

228 dynamicTab = (void *) (intptr_t) phtab[i].VAddr;

229 j = i; // Save Dynamic Table ID

230 }

231 }

232

233 // Page Align real base

234 iRealBase &= ~0xFFF;

235 DEBUGS(" elf_relocate: True Base = 0x%x, Compiled Base = 0x%x", Base, iRealBase);

236

237 // Adjust "Real" Base

238 iBaseDiff = (intptr_t)Base - iRealBase;

239

240 // hdr->entrypoint += iBaseDiff; // Adjust Entrypoint

241

242 // Check if a PT_DYNAMIC segement was found

243 if(!dynamicTab) {

244 SysDebug(" elf_relocate: No PT_DYNAMIC segment in image %p, returning", Base);

245 return (void *)(intptr_t)(hdr->entrypoint + iBaseDiff);

246 }

247

248 // Adjust Dynamic Table

249 dynamicTab = (void *)( (intptr_t)dynamicTab + iBaseDiff );

250

251 // === Get Symbol table and String Table ===

252 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)

253 {

254 switch(dynamicTab[j].d_tag)

255 {

256 // --- Symbol Table ---

257 case DT_SYMTAB:

258 DEBUGS(" elf_relocate: DYNAMIC Symbol Table 0x%x (0x%x)",

259 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);

260 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;

261 dynsymtab = (void*)(intptr_t)dynamicTab[j].d_val;

262 break;

263 // --- String Table ---

264 case DT_STRTAB:

265 DEBUGS(" elf_relocate: DYNAMIC String Table 0x%x (0x%x)",

266 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);

267 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;

268 dynstrtab = (void*)(intptr_t)dynamicTab[j].d_val;

269 break;

270 // --- Hash Table --

271 case DT_HASH:

272 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;

273 // iSymCount = ((Elf32_Word*)(intptr_t)dynamicTab[j].d_val)[1];

274 break;

275 }

276 }

277

278 if(dynsymtab == NULL) {

279 SysDebug("ld-acess.so - WARNING: No Dynamic Symbol table in %p, returning", hdr);

280 return (void *)(intptr_t) (hdr->entrypoint + iBaseDiff);

281 }

282

283 // === Add to loaded list (can be imported now) ===

284 AddLoaded( Filename, Base );

285

286 // === Parse Relocation Data ===

287 DEBUGS(" elf_relocate: dynamicTab = 0x%x", dynamicTab);

288 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)

289 {

290 switch(dynamicTab[j].d_tag)

291 {

292 // --- Shared Library Name ---

293 case DT_SONAME:

294 DEBUGS(" elf_relocate: .so Name '%s'", dynstrtab+dynamicTab[j].d_val);

295 break;

296 // --- Needed Library ---

297 case DT_NEEDED:

298 libPath = dynstrtab + dynamicTab[j].d_val;

299 DEBUGS(" Required Library '%s'", libPath);

300 if(LoadLibrary(libPath, NULL, envp) == 0) {

301 #if DEBUG

302 DEBUGS(" elf_relocate: Unable to load '%s'", libPath);

303 #else

304 SysDebug("Unable to load required library '%s'", libPath);

305 #endif

306 return 0;

307 }

308 DEBUGS(" Lib loaded");

309 break;

310 // --- PLT/GOT ---

311 // case DT_PLTGOT: pltgot = (void*)(iBaseDiff + dynamicTab[j].d_val); break;

312 case DT_JMPREL: plt = (void*)(iBaseDiff + dynamicTab[j].d_val); break;

313 case DT_PLTREL: pltType = dynamicTab[j].d_val; break;

314 case DT_PLTRELSZ: pltSz = dynamicTab[j].d_val; break;

315

316 // --- Relocation ---

317 case DT_REL: rel = (void*)(iBaseDiff + dynamicTab[j].d_val); break;

318 case DT_RELSZ: relSz = dynamicTab[j].d_val; break;

319 case DT_RELENT: relEntSz = dynamicTab[j].d_val; break;

320 case DT_RELA: rela = (void*)(iBaseDiff + dynamicTab[j].d_val); break;

321 case DT_RELASZ: relaSz = dynamicTab[j].d_val; break;

322 case DT_RELAENT: relaEntSz = dynamicTab[j].d_val; break;

323

324 // --- Symbol Table ---

325 case DT_SYMTAB:

326 // --- Hash Table ---

327 case DT_HASH:

328 // --- String Table ---

329 case DT_STRTAB:

330 break;

331

332 // --- Unknown ---

333 default:

334 if(dynamicTab[j].d_tag > DT_JMPREL) continue;

335 //DEBUGS(" elf_relocate: %i-%i = %s,0x%x",

336 // i,j, csaDT_NAMES[dynamicTab[j].d_tag],dynamicTab[j].d_val);

337 break;

338 }

339 }

340

341 DEBUGS(" elf_relocate: Beginning Relocation");

342

343 void _doRelocate(uint32_t r_info, uint32_t *ptr, int bRela, Elf32_Addr addend)

344 {

345 int type = ELF32_R_TYPE(r_info);

346 int sym = ELF32_R_SYM(r_info);

347 const char *symname = dynstrtab + dynsymtab[sym].nameOfs;

348 do_relocate(r_info, ptr, addend, type, bRela, symname, iBaseDiff);

349 }

350

351 switch(hdr->machine)

352 {

353 case EM_386:

354 do_relocate = elf_doRelocate_386;

355 break;

356 case EM_ARM:

357 do_relocate = elf_doRelocate_arm;

358 break;

359 default:

360 SysDebug("Elf32Relocate: Unknown machine type %i", hdr->machine);

361 break;

362 }

363

364 DEBUGS("do_relocate = %p (%p or %p)", do_relocate, &elf_doRelocate_386, &elf_doRelocate_arm);

365

366 // Parse Relocation Entries

367 if(rel && relSz)

368 {

369 Elf32_Word *ptr;

370 DEBUGS(" elf_relocate: rel=0x%x, relSz=0x%x, relEntSz=0x%x", rel, relSz, relEntSz);

371 j = relSz / relEntSz;

372 for( i = 0; i < j; i++ )

373 {

374 //DEBUGS(" Rel %i: 0x%x+0x%x", i, iBaseDiff, rel[i].r_offset);

375 ptr = (void*)(iBaseDiff + rel[i].r_offset);

376 _doRelocate(rel[i].r_info, ptr, 0, *ptr);

377 }

378 }

379 // Parse Relocation Entries

380 if(rela && relaSz)

381 {

382 Elf32_Word *ptr;

383 DEBUGS(" elf_relocate: rela=0x%x, relaSz=0x%x, relaEntSz=0x%x", rela, relaSz, relaEntSz);

384 j = relaSz / relaEntSz;

385 for( i = 0; i < j; i++ )

386 {

387 ptr = (void*)(iBaseDiff + rela[i].r_offset);

388 _doRelocate(rel[i].r_info, ptr, 1, rela[i].r_addend);

389 }

390 }

391

392 // === Process PLT (Procedure Linkage Table) ===

393 if(plt && pltSz)

394 {

395 Elf32_Word *ptr;

396 DEBUGS(" elf_relocate: Relocate PLT, plt=0x%x", plt);

397 if(pltType == DT_REL)

398 {

399 Elf32_Rel *pltRel = plt;

400 j = pltSz / sizeof(Elf32_Rel);

401 DEBUGS(" elf_relocate: PLT Reloc Type = Rel, %i entries", j);

402 for(i=0;i<j;i++)

403 {

404 ptr = (void*)(iBaseDiff + pltRel[i].r_offset);

405 _doRelocate(pltRel[i].r_info, ptr, 0, *ptr);

406 }

407 }

408 else

409 {

410 Elf32_Rela *pltRela = plt;

411 j = pltSz / sizeof(Elf32_Rela);

412 DEBUGS(" elf_relocate: PLT Reloc Type = Rela, %i entries", j);

413 for(i=0;i<j;i++)

414 {

415 ptr = (void*)(iRealBase + pltRela[i].r_offset);

416 _doRelocate(pltRela[i].r_info, ptr, 1, pltRela[i].r_addend);

417 }

418 }

419 }

420

421 DEBUGS("ElfRelocate: RETURN 0x%x to %p", hdr->entrypoint + iBaseDiff, __builtin_return_address(0));

422 return (void*)(intptr_t)( hdr->entrypoint + iBaseDiff );

423 }

424

425 int Elf32GetSymbol(void *Base, const char *Name, void **ret, size_t *Size)

426 {

427 Elf32_Ehdr *hdr = Base;

428 Elf32_Sym *symtab = NULL;

429 int nbuckets = 0;

430 Elf32_Word *pBuckets = NULL;

431 Elf32_Word *pChains;

432 uint32_t iNameHash;

433 const char *dynstrtab = NULL;

434 uintptr_t iBaseDiff = -1;

435 Elf32_Phdr *phtab;

436 Elf32_Dyn *dynTab = NULL;

437 int i;

438

439 // Locate the tables

440 phtab = (void*)( (uintptr_t)Base + hdr->phoff );

441 for( i = 0; i < hdr->phentcount; i ++ )

442 {

443 if(phtab[i].Type == PT_LOAD && iBaseDiff > phtab[i].VAddr)

444 iBaseDiff = phtab[i].VAddr;

445 if( phtab[i].Type == PT_DYNAMIC ) {

446 dynTab = (void*)(intptr_t)phtab[i].VAddr;

447 }

448 }

449 if( !dynTab ) {

450 SysDebug("ERROR - Unable to find DYNAMIC segment in %p", Base);

451 return 0;

452 }

453 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff

454 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );

455 for( i = 0; dynTab[i].d_tag != DT_NULL; i++)

456 {

457 switch(dynTab[i].d_tag)

458 {

459 // --- Symbol Table ---

460 case DT_SYMTAB:

461 symtab = (void*)(intptr_t) dynTab[i].d_val; // Rebased in Relocate

462 break;

463 case DT_STRTAB:

464 dynstrtab = (void*)(intptr_t) dynTab[i].d_val;

465 break;

466 // --- Hash Table --

467 case DT_HASH:

468 pBuckets = (void*)(intptr_t) dynTab[i].d_val;

469 break;

470 }

471 }

472

473 if( !symtab ) {

474 SysDebug("ERRO - No DT_SYMTAB in %p", Base);

475 return 0;

476 }

477 if( !pBuckets ) {

478 SysDebug("ERRO - No DT_HASH in %p", Base);

479 return 0;

480 }

481 if( !dynstrtab ) {

482 SysDebug("ERRO - No DT_STRTAB in %p", Base);

483 return 0;

484 }

485

486 // ... ok... maybe they haven't been relocated

487 if( (uintptr_t)symtab < (uintptr_t)Base )

488 {

489 symtab = (void*)( (uintptr_t)symtab + iBaseDiff );

490 pBuckets = (void*)( (uintptr_t)pBuckets + iBaseDiff );

491 dynstrtab = (void*)( (uintptr_t)dynstrtab + iBaseDiff );

492 SysDebug("Executable not yet relocated");

493 }

494

495 nbuckets = pBuckets[0];

496 // iSymCount = pBuckets[1];

497 pBuckets = &pBuckets[2];

498 pChains = &pBuckets[ nbuckets ];

499

500 // Get hash

501 iNameHash = ElfHashString(Name);

502 iNameHash %= nbuckets;

503

504 // Walk Chain

505 i = pBuckets[ iNameHash ];

506 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].nameOfs, Name) == 0) {

507 *ret = (void*)( (uintptr_t) symtab[ i ].value + iBaseDiff );

508 if(Size) *Size = symtab[i].size;

509 return 1;

510 }

511

512 while(pChains[i] != STN_UNDEF)

513 {

514 i = pChains[i];

515 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[ i ].nameOfs, Name) == 0) {

516 *ret = (void*)( (uintptr_t)symtab[ i ].value + iBaseDiff );

517 if(Size) *Size = symtab[i].size;

518 return 1;

519 }

520 }

521

522 return 0;

523 }

524

525 #ifdef SUPPORT_ELF64

526 void *Elf64Relocate(void *Base, char **envp, const char *Filename)

527 {

528 int i;

529 Elf64_Ehdr *hdr = Base;

530 Elf64_Phdr *phtab;

531 Elf64_Dyn *dyntab = NULL;

532 Elf64_Addr compiledBase = -1, baseDiff;

533 Elf64_Sym *symtab = NULL;

534 char *strtab = NULL;

535 Elf64_Word *hashtab = NULL;

536 Elf64_Rel *rel = NULL;

537 int rel_count = 0;

538 Elf64_Rela *rela = NULL;

539 int rela_count = 0;

540 void *pltrel = NULL;

541 int plt_size = 0, plt_type = 0;

542

543 DEBUGS("Elf64Relocate: hdr = {");

544 DEBUGS("Elf64Relocate: e_ident = '%.16s'", hdr->e_ident);

545 DEBUGS("Elf64Relocate: e_type = 0x%x", hdr->e_type);

546 DEBUGS("Elf64Relocate: e_machine = 0x%x", hdr->e_machine);

547 DEBUGS("Elf64Relocate: e_version = 0x%x", hdr->e_version);

548 DEBUGS("Elf64Relocate: e_entry = %p", hdr->e_entry);

549 DEBUGS("Elf64Relocate: e_phoff = 0x%llx", hdr->e_phoff);

550 DEBUGS("Elf64Relocate: e_shoff = 0x%llx", hdr->e_shoff);

551 DEBUGS("Elf64Relocate: e_flags = 0x%x", hdr->e_flags);

552 DEBUGS("Elf64Relocate: e_ehsize = 0x%x", hdr->e_ehsize);

553 DEBUGS("Elf64Relocate: e_phentsize = 0x%x", hdr->e_phentsize);

554 DEBUGS("Elf64Relocate: e_phnum = %i", hdr->e_phnum);

555

556 // Scan for the dynamic table (and find the compiled base)

557 phtab = (void*)((uintptr_t)Base + hdr->e_phoff);

558 for( i = 0; i < hdr->e_phnum; i ++ )

559 {

560 if(phtab[i].p_type == PT_DYNAMIC)

561 dyntab = (void *)(intptr_t)phtab[i].p_vaddr;

562 if(phtab[i].p_type == PT_LOAD && compiledBase > phtab[i].p_vaddr)

563 compiledBase = phtab[i].p_vaddr;

564 }

565

566 baseDiff = (uintptr_t)Base - compiledBase;

567

568 DEBUGS("baseDiff = %p", baseDiff);

569

570 if(dyntab == NULL) {

571 SysDebug(" Elf64Relocate: No PT_DYNAMIC segment in image %p, returning", Base);

572 return (void *)(uintptr_t)(hdr->e_entry + baseDiff);

573 }

574

575 dyntab = (void *)(uintptr_t)((uintptr_t)dyntab + baseDiff);

576

577 // Parse the dynamic table (first pass)

578 // - Search for String, Symbol and Hash tables

579 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)

580 {

581 switch(dyntab[i].d_tag)

582 {

583 case DT_SYMTAB:

584 dyntab[i].d_un.d_ptr += baseDiff;

585 symtab = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;

586 break;

587 case DT_STRTAB:

588 dyntab[i].d_un.d_ptr += baseDiff;

589 strtab = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;

590 break;

591 case DT_HASH:

592 dyntab[i].d_un.d_ptr += baseDiff;

593 hashtab = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;

594 break;

595 }

596 }

597

598 if( !symtab || !strtab || !hashtab ) {

599 SysDebug("ld-acess - Elf64Relocate: Missing Symbol, string or hash table");

600 return NULL;

601 }

602

603 // Ready for symbol use

604 AddLoaded( Filename, Base );

605

606 // Second pass on dynamic table

607 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)

608 {

609 DEBUGS("dyntab[%i].d_tag = %i", i, dyntab[i].d_tag);

610 switch(dyntab[i].d_tag)

611 {

612 case DT_SONAME: break;

613

614 case DT_NEEDED: {

615 char *libPath = strtab + dyntab[i].d_un.d_val;

616 DEBUGS("Elf64Relocate: libPath = '%s'", libPath);

617 if(LoadLibrary(libPath, NULL, envp) == 0) {

618 SysDebug("ld-acess - Elf64Relocate: Unable to load '%s'", libPath);

619 return NULL;

620 }

621 } break;

622

623 // Relocation entries

624 case DT_REL:

625 dyntab[i].d_un.d_ptr += baseDiff;

626 rel = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;

627 break;

628 case DT_RELSZ:

629 rel_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rel);

630 break;

631 case DT_RELENT:

632 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rel) ) {

633 SysDebug("ld-acess - Elf64Relocate: DT_RELENT(%i) != sizeof(Elf64_Rel)(%i)",

634 dyntab[i].d_un.d_val, sizeof(Elf64_Rel));

635 return NULL;

636 }

637 break;

638 case DT_RELA:

639 dyntab[i].d_un.d_ptr += baseDiff;

640 rela = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;

641 break;

642 case DT_RELASZ:

643 rela_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rela);

644 break;

645 case DT_RELAENT:

646 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rela) ) {

647 SysDebug("ld-acess - Elf64Relocate: DT_RELAENT(%i) != sizeof(Elf64_Rela)(%i)",

648 dyntab[i].d_un.d_val, sizeof(Elf64_Rela));

649 return NULL;

650 }

651 break;

652 case DT_JMPREL:

653 dyntab[i].d_un.d_ptr += baseDiff;

654 pltrel = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;

655 break;

656 case DT_PLTREL:

657 plt_type = dyntab[i].d_un.d_val;

658 break;

659 case DT_PLTRELSZ:

660 plt_size = dyntab[i].d_un.d_val;

661 break;

662 }

663 }

664

665 // Relocation function

666 void _Elf64DoReloc(Elf64_Xword r_info, void *ptr, Elf64_Sxword addend)

667 {

668 int sym = ELF64_R_SYM(r_info);

669 int type = ELF64_R_TYPE(r_info);

670 const char *symname = strtab + symtab[sym].st_name;

671 switch( type )

672 {

673 case R_X86_64_NONE:

674 break;

675 case R_X86_64_64:

676 *(uint64_t*)ptr = (uintptr_t)GetSymbol(symname, NULL) + addend;

677 break;

678 case R_X86_64_COPY: {

679 size_t size;

680 void *symptr = GetSymbol(symname, &size);

681 memcpy(ptr, symptr, size);

682 } break;

683 case R_X86_64_GLOB_DAT:

684 *(uint64_t*)ptr = (uintptr_t)GetSymbol(symname, NULL);

685 break;

686 case R_X86_64_JUMP_SLOT:

687 *(uint64_t*)ptr = (uintptr_t)GetSymbol(symname, NULL);

688 break;

689 case R_X86_64_RELATIVE:

690 *(uint64_t*)ptr = (uintptr_t)Base + addend;

691 break;

692 default:

693 SysDebug("ld-acess - _Elf64DoReloc: Unknown relocation type %i", type);

694 break;

695 }

696 }

697

698 if( rel )

699 {

700 DEBUGS("rel_count = %i", rel_count);

701 for( i = 0; i < rel_count; i ++ )

702 {

703 uint64_t *ptr = (void *)(uintptr_t)( rel[i].r_offset + baseDiff );

704 _Elf64DoReloc( rel[i].r_info, ptr, *ptr);

705 }

706 }

707

708 if( rela )

709 {

710 DEBUGS("rela_count = %i", rela_count);

711 for( i = 0; i < rela_count; i ++ )

712 {

713 uint64_t *ptr = (void *)(uintptr_t)( rela[i].r_offset + baseDiff );

714 _Elf64DoReloc( rela[i].r_info, ptr, rela[i].r_addend );

715 }

716 }

717

718 if( pltrel && plt_type )

719 {

720 if( plt_type == DT_REL ) {

721 Elf64_Rel *plt = pltrel;

722 int count = plt_size / sizeof(Elf64_Rel);

723 DEBUGS("plt rel count = %i", count);

724 for( i = 0; i < count; i ++ )

725 {

726 uint64_t *ptr = (void *)(uintptr_t)( plt[i].r_offset + baseDiff );

727 _Elf64DoReloc( plt[i].r_info, ptr, *ptr);

728 }

729 }

730 else {

731 Elf64_Rela *plt = pltrel;

732 int count = plt_size / sizeof(Elf64_Rela);

733 DEBUGS("plt rela count = %i", count);

734 for( i = 0; i < count; i ++ )

735 {

736 uint64_t *ptr = (void *)(uintptr_t)( plt[i].r_offset + baseDiff );

737 _Elf64DoReloc( plt[i].r_info, ptr, plt[i].r_addend);

738 }

739 }

740 }

741

742 {

743 void *ret = (void *)(uintptr_t)(hdr->e_entry + baseDiff);

744 DEBUGS("Elf64Relocate: Relocations done, return %p", ret);

745 return ret;

746 }

747 }

748

749 int Elf64GetSymbol(void *Base, const char *Name, void **Ret, size_t *Size)

750 {

751 Elf64_Ehdr *hdr = Base;

752 Elf64_Sym *symtab;

753 int nbuckets = 0;

754 // int iSymCount = 0;

755 int i;

756 Elf64_Word *pBuckets;

757 Elf64_Word *pChains;

758 uint32_t iNameHash;

759 const char *dynstrtab;

760 uintptr_t iBaseDiff = -1;

761

762 dynstrtab = NULL;

763 pBuckets = NULL;

764 symtab = NULL;

765

766 // Catch the current executable

767 if( !pBuckets )

768 {

769 Elf64_Phdr *phtab;

770 Elf64_Dyn *dynTab = NULL;

771 int j;

772

773 // Locate the tables

774 phtab = (void*)( (intptr_t)Base + hdr->e_phoff );

775 for( i = 0; i < hdr->e_phnum; i ++ )

776 {

777 if(phtab[i].p_type == PT_LOAD && iBaseDiff > phtab[i].p_vaddr)

778 iBaseDiff = phtab[i].p_vaddr;

779 if( phtab[i].p_type == PT_DYNAMIC ) {

780 dynTab = (void*)(intptr_t)phtab[i].p_vaddr;

781 }

782 }

783 if( !dynTab ) {

784 SysDebug("ERROR - Unable to find DYNAMIC segment in %p", Base);

785 return 0;

786 }

787 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff

788 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );

789

790 for( j = 0; dynTab[j].d_tag != DT_NULL; j++)

791 {

792 switch(dynTab[j].d_tag)

793 {

794 // --- Symbol Table ---

795 case DT_SYMTAB:

796 symtab = (void*)(intptr_t) dynTab[j].d_un.d_val; // Rebased in Relocate

797 break;

798 case DT_STRTAB:

799 dynstrtab = (void*)(intptr_t) dynTab[j].d_un.d_val;

800 break;

801 // --- Hash Table --

802 case DT_HASH:

803 pBuckets = (void*)(intptr_t) dynTab[j].d_un.d_val;

804 break;

805 }

806 }

807 }

808

809 nbuckets = pBuckets[0];

810 // iSymCount = pBuckets[1];

811 pBuckets = &pBuckets[2];

812 pChains = &pBuckets[ nbuckets ];

813

814 // Get hash

815 iNameHash = ElfHashString(Name);

816 iNameHash %= nbuckets;

817

818 // Walk Chain

819 i = pBuckets[ iNameHash ];

820 if(symtab[i].st_shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].st_name, Name) == 0) {

821 *Ret = (void*)( (intptr_t)symtab[i].st_value + iBaseDiff );

822 if(Size) *Size = symtab[i].st_size;

823 DEBUGS("%s = %p", Name, *Ret);

824 return 1;

825 }

826

827 while(pChains[i] != STN_UNDEF)

828 {

829 i = pChains[i];

830 if(symtab[i].st_shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].st_name, Name) == 0) {

831 *Ret = (void*)((intptr_t)symtab[i].st_value + iBaseDiff);

832 if(Size) *Size = symtab[i].st_size;

833 DEBUGS("%s = %p", Name, *Ret);

834 return 1;

835 }

836 }

837

838 return 0;

839 }

840 #endif

841

842

843 uint32_t ElfHashString(const char *name)

844 {

845 uint32_t h = 0, g;

846 while(*name)

847 {

848 h = (h << 4) + *(uint8_t*)name++;

849 if( (g = h & 0xf0000000) )

850 h ^= g >> 24;

851 h &= ~g;

852 }

853 return h;

854 }

855