reloc.c revision 1.41
1 /* $NetBSD: reloc.c,v 1.41 2001/08/14 20:17:25 eeh Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by John Polstra. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 /* 35 * Dynamic linker for ELF. 36 * 37 * John Polstra <jdp (at) polstra.com>. 38 */ 39 40 #include <err.h> 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <stdarg.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <unistd.h> 48 #include <sys/types.h> 49 #include <sys/mman.h> 50 #include <dirent.h> 51 52 #include "debug.h" 53 #include "rtld.h" 54 55 #ifndef RTLD_INHIBIT_COPY_RELOCS 56 static int _rtld_do_copy_relocation __P((const Obj_Entry *, const Elf_Rela *, 57 bool)); 58 59 /* 60 * XXX: These don't work for the alpha and i386; don't know about powerpc 61 * The alpha and the i386 avoid the problem by compiling everything PIC. 62 * These relocation are supposed to be writing the address of the 63 * function to be called on the bss.rel or bss.rela segment, but: 64 * - st_size == 0 65 * - on the i386 at least the call instruction is a direct call 66 * not an indirect call. 67 */ 68 static int 69 _rtld_do_copy_relocation(dstobj, rela, dodebug) 70 const Obj_Entry *dstobj; 71 const Elf_Rela *rela; 72 bool dodebug; 73 { 74 void *dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 75 const Elf_Sym *dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 76 const char *name = dstobj->strtab + dstsym->st_name; 77 unsigned long hash = _rtld_elf_hash(name); 78 size_t size = dstsym->st_size; 79 const void *srcaddr; 80 const Elf_Sym *srcsym = NULL; 81 Obj_Entry *srcobj; 82 83 for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) 84 if ((srcsym = _rtld_symlook_obj(name, hash, srcobj, 85 false)) != NULL) 86 break; 87 88 if (srcobj == NULL) { 89 _rtld_error("Undefined symbol \"%s\" referenced from COPY" 90 " relocation in %s", name, dstobj->path); 91 return (-1); 92 } 93 srcaddr = (const void *)(srcobj->relocbase + srcsym->st_value); 94 (void)memcpy(dstaddr, srcaddr, size); 95 rdbg(dodebug, ("COPY %s %s %s --> src=%p dst=%p *dst= %p size %ld", 96 dstobj->path, srcobj->path, name, (void *)srcaddr, 97 (void *)dstaddr, (void *)*(long *)dstaddr, (long)size)); 98 return (0); 99 } 100 #endif /* RTLD_INHIBIT_COPY_RELOCS */ 101 102 103 /* 104 * Process the special R_xxx_COPY relocations in the main program. These 105 * copy data from a shared object into a region in the main program's BSS 106 * segment. 107 * 108 * Returns 0 on success, -1 on failure. 109 */ 110 int 111 _rtld_do_copy_relocations(dstobj, dodebug) 112 const Obj_Entry *dstobj; 113 bool dodebug; 114 { 115 #ifndef RTLD_INHIBIT_COPY_RELOCS 116 117 /* COPY relocations are invalid elsewhere */ 118 assert(dstobj->mainprog); 119 120 if (dstobj->rel != NULL) { 121 const Elf_Rel *rel; 122 for (rel = dstobj->rel; rel < dstobj->rellim; ++rel) { 123 if (ELF_R_TYPE(rel->r_info) == R_TYPE(COPY)) { 124 Elf_Rela ourrela; 125 ourrela.r_info = rel->r_info; 126 ourrela.r_offset = rel->r_offset; 127 ourrela.r_addend = 0; 128 if (_rtld_do_copy_relocation(dstobj, 129 &ourrela, dodebug) < 0) 130 return (-1); 131 } 132 } 133 } 134 if (dstobj->rela != NULL) { 135 const Elf_Rela *rela; 136 for (rela = dstobj->rela; rela < dstobj->relalim; ++rela) { 137 if (ELF_R_TYPE(rela->r_info) == R_TYPE(COPY)) { 138 if (_rtld_do_copy_relocation(dstobj, rela, 139 dodebug) < 0) 140 return (-1); 141 } 142 } 143 } 144 #endif /* RTLD_INHIBIT_COPY_RELOCS */ 145 146 return (0); 147 } 148 149 150 #if !defined(__sparc__) && !defined(__x86_64__) 151 152 #if defined(__alpha__) || defined(__i386__) || defined(__m68k__) 153 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[]; 154 extern Elf_Dyn _DYNAMIC; 155 #endif 156 157 int 158 _rtld_relocate_nonplt_object(obj, rela, dodebug) 159 Obj_Entry *obj; 160 const Elf_Rela *rela; 161 bool dodebug; 162 { 163 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 164 const Elf_Sym *def; 165 const Obj_Entry *defobj; 166 #if defined(__alpha__) || defined(__arm__) || defined(__i386__) || \ 167 defined(__m68k__) || defined(__powerpc__) || defined(__vax__) 168 Elf_Addr tmp; 169 #endif 170 171 switch (ELF_R_TYPE(rela->r_info)) { 172 173 case R_TYPE(NONE): 174 break; 175 176 #if defined(__i386__) 177 case R_TYPE(GOT32): 178 179 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 180 &defobj, false); 181 if (def == NULL) 182 return -1; 183 184 tmp = (Elf_Addr)(defobj->relocbase + def->st_value); 185 if (*where != tmp) 186 *where = tmp; 187 rdbg(dodebug, ("GOT32 %s in %s --> %p in %s", 188 defobj->strtab + def->st_name, obj->path, 189 (void *)*where, defobj->path)); 190 break; 191 192 case R_TYPE(PC32): 193 /* 194 * I don't think the dynamic linker should ever see this 195 * type of relocation. But the binutils-2.6 tools sometimes 196 * generate it. 197 */ 198 199 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 200 &defobj, false); 201 if (def == NULL) 202 return -1; 203 204 *where += (Elf_Addr)(defobj->relocbase + def->st_value) - 205 (Elf_Addr)where; 206 rdbg(dodebug, ("PC32 %s in %s --> %p in %s", 207 defobj->strtab + def->st_name, obj->path, 208 (void *)*where, defobj->path)); 209 break; 210 211 case R_TYPE(32): 212 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 213 &defobj, false); 214 if (def == NULL) 215 return -1; 216 217 *where += (Elf_Addr)(defobj->relocbase + def->st_value); 218 rdbg(dodebug, ("32 %s in %s --> %p in %s", 219 defobj->strtab + def->st_name, obj->path, 220 (void *)*where, defobj->path)); 221 break; 222 #endif /* __i386__ */ 223 224 #if defined(__m68k__) 225 case R_TYPE(GOT32): 226 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 227 &defobj, false); 228 if (def == NULL) 229 return -1; 230 231 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 232 rela->r_addend); 233 if (*where != tmp) 234 *where = tmp; 235 rdbg(dodebug, ("GOT32 %s in %s --> %p in %s", 236 defobj->strtab + def->st_name, obj->path, 237 (void *)*where, defobj->path)); 238 break; 239 240 case R_TYPE(PC32): 241 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 242 &defobj, false); 243 if (def == NULL) 244 return -1; 245 246 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 247 rela->r_addend) - (Elf_Addr)where; 248 if (*where != tmp) 249 *where = tmp; 250 rdbg(dodebug, ("PC32 %s in %s --> %p in %s", 251 defobj->strtab + def->st_name, obj->path, 252 (void *)*where, defobj->path)); 253 break; 254 255 case R_TYPE(32): 256 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 257 &defobj, false); 258 if (def == NULL) 259 return -1; 260 261 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 262 rela->r_addend); 263 if (*where != tmp) 264 *where = tmp; 265 rdbg(dodebug, ("32 %s in %s --> %p in %s", 266 defobj->strtab + def->st_name, obj->path, 267 (void *)*where, defobj->path)); 268 break; 269 #endif /* __m68k__ */ 270 271 #if defined(__alpha__) 272 case R_TYPE(REFQUAD): 273 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 274 &defobj, false); 275 if (def == NULL) 276 return -1; 277 278 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + 279 *where + rela->r_addend; 280 if (*where != tmp) 281 *where = tmp; 282 rdbg(dodebug, ("REFQUAD %s in %s --> %p in %s", 283 defobj->strtab + def->st_name, obj->path, 284 (void *)*where, defobj->path)); 285 break; 286 #endif /* __alpha__ */ 287 288 #if defined(__alpha__) || defined(__i386__) || defined(__m68k__) 289 case R_TYPE(GLOB_DAT): 290 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 291 &defobj, false); 292 if (def == NULL) 293 return -1; 294 295 if (*where != (Elf_Addr)(defobj->relocbase + def->st_value)) 296 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 297 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p in %s", 298 defobj->strtab + def->st_name, obj->path, 299 (void *)*where, defobj->path)); 300 break; 301 302 case R_TYPE(RELATIVE): 303 if (!dodebug || 304 (caddr_t)where < (caddr_t)_GLOBAL_OFFSET_TABLE_ || 305 (caddr_t)where >= (caddr_t)&_DYNAMIC) { 306 *where += (Elf_Addr)obj->relocbase; 307 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 308 (void *)*where)); 309 } 310 else 311 rdbg(dodebug, ("RELATIVE in %s stays at %p", 312 obj->path, (void *)*where)); 313 break; 314 315 case R_TYPE(COPY): 316 /* 317 * These are deferred until all other relocations have 318 * been done. All we do here is make sure that the COPY 319 * relocation is not in a shared library. They are allowed 320 * only in executable files. 321 */ 322 if (!obj->mainprog) { 323 _rtld_error( 324 "%s: Unexpected R_COPY relocation in shared library", 325 obj->path); 326 return -1; 327 } 328 rdbg(dodebug, ("COPY (avoid in main)")); 329 break; 330 #endif /* __i386__ || __alpha__ || __m68k__ */ 331 332 #if defined(__mips__) 333 case R_TYPE(REL32): 334 /* 32-bit PC-relative reference */ 335 def = obj->symtab + ELF_R_SYM(rela->r_info); 336 337 if (ELFDEFNNAME(ST_BIND)(def->st_info) == STB_LOCAL && 338 (ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_SECTION || 339 ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_NOTYPE)) { 340 *where += (Elf_Addr)obj->relocbase; 341 rdbg(dodebug, ("REL32 in %s --> %p", obj->path, 342 (void *)*where)); 343 } else { 344 /* XXX maybe do something re: bootstrapping? */ 345 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, 346 NULL, obj, &defobj, false); 347 if (def == NULL) 348 return -1; 349 *where += (Elf_Addr)(defobj->relocbase + def->st_value); 350 rdbg(dodebug, ("REL32 %s in %s --> %p in %s", 351 defobj->strtab + def->st_name, obj->path, 352 (void *)*where, defobj->path)); 353 } 354 break; 355 356 #endif /* __mips__ */ 357 358 #if defined(__powerpc__) || defined(__vax__) 359 case R_TYPE(32): /* word32 S + A */ 360 case R_TYPE(GLOB_DAT): /* word32 S + A */ 361 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 362 &defobj, false); 363 if (def == NULL) 364 return -1; 365 366 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 367 rela->r_addend); 368 369 if (*where != tmp) 370 *where = tmp; 371 rdbg(dodebug, ("32/GLOB_DAT %s in %s --> %p in %s", 372 defobj->strtab + def->st_name, obj->path, 373 (void *)*where, defobj->path)); 374 break; 375 376 case R_TYPE(COPY): 377 rdbg(dodebug, ("COPY")); 378 break; 379 380 case R_TYPE(JMP_SLOT): 381 rdbg(dodebug, ("JMP_SLOT")); 382 break; 383 384 case R_TYPE(RELATIVE): /* word32 B + A */ 385 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 386 if (*where != tmp) 387 *where = tmp; 388 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 389 (void *)*where)); 390 break; 391 #endif /* __powerpc__ || __vax__ */ 392 393 #if defined(__powerpc__) 394 case R_TYPE(16_LO): /* #lo(S + A) */ 395 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 396 if (*(Elf32_Half *)where != tmp) 397 *(Elf32_Half *)where = tmp; 398 rdbg(dodebug, ("16_LO in %s --> %p", obj->path, 399 (void *)*where)); 400 break; 401 402 case R_TYPE(16_HI): /* #hi(S + A) */ 403 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend) >> 16; 404 if (*(Elf32_Half *)where != tmp) 405 *(Elf32_Half *)where = tmp; 406 rdbg(dodebug, ("16_HI in %s --> %p", obj->path, 407 (void *)*where)); 408 break; 409 410 case R_TYPE(16_HA): /* #ha(S + A) */ 411 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend + 0x8000) 412 >> 16; 413 if (*(Elf32_Half *)where != tmp) 414 *(Elf32_Half *)where = tmp; 415 rdbg(dodebug, ("16_HA in %s --> %p", obj->path, 416 (void *)*where)); 417 break; 418 #endif /* __powerpc__ */ 419 420 #if defined(__arm__) 421 case R_TYPE(GLOB_DAT): /* word32 B + S */ 422 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 423 &defobj, false); 424 if (def == NULL) 425 return -1; 426 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 427 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p @ %p in %s", 428 defobj->strtab + def->st_name, obj->path, 429 (void *)*where, where, defobj->path)); 430 break; 431 432 case R_TYPE(COPY): 433 rdbg(dodebug, ("COPY")); 434 break; 435 436 case R_TYPE(JUMP_SLOT): 437 rdbg(dodebug, ("JUMP_SLOT")); 438 break; 439 440 case R_TYPE(ABS32): /* word32 B + S + A */ 441 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 442 &defobj, false); 443 if (def == NULL) 444 return -1; 445 *where += (Elf_Addr)defobj->relocbase + def->st_value; 446 rdbg(dodebug, ("ABS32 %s in %s --> %p @ %p in %s", 447 defobj->strtab + def->st_name, obj->path, 448 (void *)*where, where, defobj->path)); 449 break; 450 451 case R_TYPE(RELATIVE): /* word32 B + A */ 452 *where += (Elf_Addr)obj->relocbase; 453 rdbg(dodebug, ("RELATIVE in %s --> %p @ %p", obj->path, 454 (void *)*where, where)); 455 break; 456 457 case R_TYPE(PC24): { /* word32 S - P + A */ 458 Elf32_Sword addend; 459 460 /* 461 * Extract addend and sign-extend if needed. 462 */ 463 addend = *where; 464 if (addend & 0x00800000) 465 addend |= 0xff000000; 466 467 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 468 &defobj, false); 469 if (def == NULL) 470 return -1; 471 tmp = (Elf_Addr)obj->relocbase + def->st_value 472 - (Elf_Addr)where + (addend << 2); 473 if ((tmp & 0xfe000000) != 0xfe000000 && (tmp & 0xfe000000) != 0) { 474 _rtld_error( 475 "%s: R_ARM_PC24 relocation @ %p to %s failed " 476 "(displacement %ld (%#lx) out of range)", 477 obj->path, where, defobj->strtab + def->st_name, 478 (long) tmp, (long) tmp); 479 return -1; 480 } 481 tmp >>= 2; 482 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 483 rdbg(dodebug, ("PC24 %s in %s --> %p @ %p in %s", 484 defobj->strtab + def->st_name, obj->path, 485 (void *)*where, where, defobj->path)); 486 break; 487 } 488 #endif 489 490 default: 491 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 492 &defobj, true); 493 rdbg(dodebug, ("sym = %lu, type = %lu, offset = %p, " 494 "addend = %p, contents = %p, symbol = %s", 495 (u_long)ELF_R_SYM(rela->r_info), 496 (u_long)ELF_R_TYPE(rela->r_info), 497 (void *)rela->r_offset, (void *)rela->r_addend, 498 (void *)*where, 499 def ? defobj->strtab + def->st_name : "??")); 500 _rtld_error("%s: Unsupported relocation type %ld " 501 "in non-PLT relocations\n", 502 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 503 return -1; 504 } 505 return 0; 506 } 507 508 509 510 int 511 _rtld_relocate_plt_object(obj, rela, addrp, bind_now, dodebug) 512 Obj_Entry *obj; 513 const Elf_Rela *rela; 514 caddr_t *addrp; 515 bool bind_now; 516 bool dodebug; 517 { 518 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 519 Elf_Addr new_value; 520 521 /* Fully resolve procedure addresses now */ 522 523 #if defined(__powerpc__) 524 return _rtld_reloc_powerpc_plt(obj, rela, bind_now); 525 #endif 526 527 #if defined(__alpha__) || defined(__arm__) || defined(__i386__) || \ 528 defined(__m68k__) || defined(__vax__) 529 if (bind_now || obj->pltgot == NULL) { 530 const Elf_Sym *def; 531 const Obj_Entry *defobj; 532 533 #if !defined(__arm__) 534 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 535 #else 536 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT)); 537 #endif 538 539 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 540 &defobj, true); 541 if (def == NULL) 542 return -1; 543 544 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 545 #if defined(__vax__) 546 new_value += rela->r_addend; 547 #endif 548 rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p", 549 (int)bind_now, 550 defobj->strtab + def->st_name, 551 (void *)*where, (void *)new_value)); 552 } else 553 #endif /* __alpha__ || __i386__ || __m68k__ || __vax__ */ 554 if (!obj->mainprog) { 555 /* Just relocate the GOT slots pointing into the PLT */ 556 new_value = *where + (Elf_Addr)(obj->relocbase); 557 rdbg(dodebug, ("fixup !main in %s --> %p", obj->path, 558 (void *)*where)); 559 } else { 560 return 0; 561 } 562 /* 563 * Since this page is probably copy-on-write, let's not write 564 * it unless we really really have to. 565 */ 566 if (*where != new_value) 567 *where = new_value; 568 if (addrp != NULL) { 569 *addrp = *(caddr_t *)(obj->relocbase + rela->r_offset); 570 #if defined(__vax__) 571 *addrp -= rela->r_addend; 572 #endif 573 } 574 return 0; 575 } 576 #endif /* __sparc__ */ 577 578 caddr_t 579 _rtld_bind(obj, reloff) 580 Obj_Entry *obj; 581 Elf_Word reloff; 582 { 583 const Elf_Rela *rela; 584 Elf_Rela ourrela; 585 caddr_t addr; 586 587 if (obj->pltrel != NULL) { 588 const Elf_Rel *rel; 589 590 rel = (const Elf_Rel *)((caddr_t) obj->pltrel + reloff); 591 ourrela.r_info = rel->r_info; 592 ourrela.r_offset = rel->r_offset; 593 ourrela.r_addend = 0; 594 rela = &ourrela; 595 } else { 596 rela = (const Elf_Rela *)((caddr_t) obj->pltrela + reloff); 597 #ifdef __sparc64__ 598 if (ELF_R_TYPE(obj->pltrela->r_info) == R_TYPE(JMP_SLOT)) { 599 /* 600 * XXXX 601 * 602 * The first for PLT entries are reserved. There 603 * is some disagreement whether they should have 604 * associated relocation entries. Both the SPARC 605 * 32-bit and 64-bit ELF specifications say that 606 * they should have relocation entries, but the 607 * 32-bit SPARC binutils do not generate them, 608 * and now the 64-bit SPARC binutils have stopped 609 * generating them too. 610 * 611 * So, to provide binary compatibility, we will 612 * check the first entry, if it is reserved it 613 * should not be of the type JMP_SLOT. If it 614 * is JMP_SLOT, then the 4 reserved entries were 615 * not generated and our index is 4 entries too far. 616 */ 617 rela -= 4; 618 } 619 #endif 620 } 621 622 if (_rtld_relocate_plt_object(obj, rela, &addr, true, true) < 0) 623 _rtld_die(); 624 625 return addr; 626 } 627 628 /* 629 * Relocate newly-loaded shared objects. The argument is a pointer to 630 * the Obj_Entry for the first such object. All objects from the first 631 * to the end of the list of objects are relocated. Returns 0 on success, 632 * or -1 on failure. 633 */ 634 int 635 _rtld_relocate_objects(first, bind_now, dodebug) 636 Obj_Entry *first; 637 bool bind_now; 638 bool dodebug; 639 { 640 Obj_Entry *obj; 641 int ok = 1; 642 643 for (obj = first; obj != NULL; obj = obj->next) { 644 if (obj->nbuckets == 0 || obj->nchains == 0 || 645 obj->buckets == NULL || obj->symtab == NULL || 646 obj->strtab == NULL) { 647 _rtld_error("%s: Shared object has no run-time" 648 " symbol table", obj->path); 649 return -1; 650 } 651 rdbg(dodebug, (" relocating %s (%ld/%ld rel/rela, " 652 "%ld/%ld plt rel/rela)", 653 obj->path, 654 (long)(obj->rellim - obj->rel), 655 (long)(obj->relalim - obj->rela), 656 (long)(obj->pltrellim - obj->pltrel), 657 (long)(obj->pltrelalim - obj->pltrela))); 658 659 if (obj->textrel) { 660 /* 661 * There are relocations to the write-protected text 662 * segment. 663 */ 664 if (mprotect(obj->mapbase, obj->textsize, 665 PROT_READ | PROT_WRITE | PROT_EXEC) == -1) { 666 _rtld_error("%s: Cannot write-enable text " 667 "segment: %s", obj->path, xstrerror(errno)); 668 return -1; 669 } 670 } 671 if (obj->rel != NULL) { 672 /* Process the non-PLT relocations. */ 673 const Elf_Rel *rel; 674 for (rel = obj->rel; rel < obj->rellim; ++rel) { 675 Elf_Rela ourrela; 676 ourrela.r_info = rel->r_info; 677 ourrela.r_offset = rel->r_offset; 678 #if defined(__mips__) 679 /* rel->r_offset is not valid on mips? */ 680 if (ELF_R_TYPE(ourrela.r_info) == R_TYPE(NONE)) 681 ourrela.r_addend = 0; 682 else 683 #endif 684 ourrela.r_addend = 685 *(Elf_Word *)(obj->relocbase + 686 rel->r_offset); 687 688 if (_rtld_relocate_nonplt_object(obj, &ourrela, 689 dodebug) < 0) 690 ok = 0; 691 } 692 } 693 if (obj->rela != NULL) { 694 /* Process the non-PLT relocations. */ 695 const Elf_Rela *rela; 696 for (rela = obj->rela; rela < obj->relalim; ++rela) { 697 if (_rtld_relocate_nonplt_object(obj, rela, 698 dodebug) < 0) 699 ok = 0; 700 } 701 } 702 if (obj->textrel) { /* Re-protected the text segment. */ 703 if (mprotect(obj->mapbase, obj->textsize, 704 PROT_READ | PROT_EXEC) == -1) { 705 _rtld_error("%s: Cannot write-protect text " 706 "segment: %s", obj->path, xstrerror(errno)); 707 return -1; 708 } 709 } 710 /* Process the PLT relocations. */ 711 if (obj->pltrel != NULL) { 712 const Elf_Rel *rel; 713 for (rel = obj->pltrel; rel < obj->pltrellim; ++rel) { 714 Elf_Rela ourrela; 715 ourrela.r_info = rel->r_info; 716 ourrela.r_offset = rel->r_offset; 717 ourrela.r_addend = 718 *(Elf_Word *)(obj->relocbase + 719 rel->r_offset); 720 if (_rtld_relocate_plt_object(obj, &ourrela, 721 NULL, bind_now, dodebug) < 0) 722 ok = 0; 723 } 724 } 725 if (obj->pltrela != NULL) { 726 const Elf_Rela *rela; 727 for (rela = obj->pltrela; rela < obj->pltrelalim; 728 ++rela) { 729 if (_rtld_relocate_plt_object(obj, rela, 730 NULL, bind_now, dodebug) < 0) 731 ok = 0; 732 } 733 } 734 if (!ok) 735 return -1; 736 737 738 /* Set some sanity-checking numbers in the Obj_Entry. */ 739 obj->magic = RTLD_MAGIC; 740 obj->version = RTLD_VERSION; 741 742 /* Fill in the dynamic linker entry points. */ 743 obj->dlopen = _rtld_dlopen; 744 obj->dlsym = _rtld_dlsym; 745 obj->dlerror = _rtld_dlerror; 746 obj->dlclose = _rtld_dlclose; 747 obj->dladdr = _rtld_dladdr; 748 749 /* Set the special PLTGOT entries. */ 750 if (obj->pltgot != NULL) { 751 #if defined(__arm__) || defined(__i386__) || defined(__m68k__) || \ 752 defined(__x86_64__) 753 obj->pltgot[1] = (Elf_Addr) obj; 754 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 755 #endif 756 #if defined(__alpha__) 757 /* 758 * This function will be called to perform the 759 * relocation. 760 */ 761 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 762 /* Identify this shared object */ 763 obj->pltgot[3] = (Elf_Addr) obj; 764 #endif 765 #if defined(__mips__) 766 _rtld_relocate_mips_got(obj); 767 768 obj->pltgot[0] = (Elf_Addr) & _rtld_bind_start; 769 /* XXX only if obj->pltgot[1] & 0x80000000 ?? */ 770 obj->pltgot[1] |= (Elf_Addr) obj; 771 #endif 772 #if defined(__powerpc__) 773 _rtld_setup_powerpc_plt(obj); 774 #endif 775 #if defined(__sparc__) 776 #if defined(__arch64__) || defined(__sparc_v9__) 777 /* 778 * On sparc64 we got troubles. 779 * 780 * Instructions are 4 bytes long. 781 * Elf[64]_Addr is 8 bytes long, so are our pltglot[] 782 * array entries. 783 * Each PLT entry jumps to PLT0 to enter the dynamic 784 * linker. 785 * Loading an arbitrary 64-bit pointer takes 6 786 * instructions and 2 registers. 787 * 788 * Somehow we need to issue a save to get a new stack 789 * frame, load the address of the dynamic linker, and 790 * jump there, in 8 instructions or less. 791 * 792 * Oh, we need to fill out both PLT0 and PLT1. 793 */ 794 { 795 Elf_Word *entry = (Elf_Word *)obj->pltgot; 796 extern void _rtld_install_plt __P((Elf_Word *, 797 Elf_Addr)); 798 extern void _rtld_bind_start_0 __P((long, 799 long)); 800 extern void _rtld_bind_start_1 __P((long, 801 long)); 802 803 /* Install in entries 0 and 1 */ 804 _rtld_install_plt(&entry[0], 805 (Elf_Addr)&_rtld_bind_start_0); 806 _rtld_install_plt(&entry[8], 807 (Elf_Addr)&_rtld_bind_start_1); 808 809 /* 810 * Install the object reference in first slot 811 * of entry 2. 812 */ 813 obj->pltgot[8] = (Elf_Addr) obj; 814 } 815 #else 816 /* 817 * PLTGOT is the PLT on the sparc. 818 * The first entry holds the call the dynamic linker. 819 * We construct a `call' sequence that transfers 820 * to `_rtld_bind_start()'. 821 * The second entry holds the object identification. 822 * Note: each PLT entry is three words long. 823 */ 824 #define SAVE 0x9de3bfc0 /* i.e. `save %sp,-64,%sp' */ 825 #define CALL 0x40000000 826 #define NOP 0x01000000 827 obj->pltgot[0] = SAVE; 828 obj->pltgot[1] = CALL | 829 ((Elf_Addr)&_rtld_bind_start - 830 (Elf_Addr)&obj->pltgot[1]) >> 2; 831 obj->pltgot[2] = NOP; 832 833 obj->pltgot[3] = (Elf_Addr) obj; 834 #endif /* __arch64__ */ 835 #endif /* __sparc__ */ 836 #if defined(__vax__) 837 obj->pltgot[1] = (Elf_Addr) obj; 838 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 839 #endif 840 } 841 } 842 843 return 0; 844 } 845
Indexes created Tue Sep 30 07:10:03 GMT 2025