1 /*- 2 * Copyright (c) 2014-2015 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * Portions of this software were developed by Andrew Turner 6 * under sponsorship from the FreeBSD Foundation. 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/types.h> 31 32 #include <machine/sysarch.h> 33 34 #include <stdlib.h> 35 36 #include "debug.h" 37 #include "rtld.h" 38 #include "rtld_printf.h" 39 40 /* 41 * It is possible for the compiler to emit relocations for unaligned data. 42 * We handle this situation with these inlines. 43 */ 44 #define RELOC_ALIGNED_P(x) \ 45 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 46 47 /* 48 * This is not the correct prototype, but we only need it for 49 * a function pointer to a simple asm function. 50 */ 51 void *_rtld_tlsdesc_static(void *); 52 void *_rtld_tlsdesc_undef(void *); 53 void *_rtld_tlsdesc_dynamic(void *); 54 55 void _exit(int); 56 57 bool 58 arch_digest_note(struct Struct_Obj_Entry *obj __unused, const Elf_Note *note) 59 { 60 const char *note_name; 61 const uint32_t *note_data; 62 63 note_name = (const char *)(note + 1); 64 /* Only handle GNU notes */ 65 if (note->n_namesz != sizeof(ELF_NOTE_GNU) || 66 strncmp(note_name, ELF_NOTE_GNU, sizeof(ELF_NOTE_GNU)) != 0) 67 return (false); 68 69 /* Only handle GNU property notes */ 70 if (note->n_type != NT_GNU_PROPERTY_TYPE_0) 71 return (false); 72 73 /* 74 * note_data[0] - Type 75 * note_data[1] - Length 76 * note_data[2] - Data 77 * note_data[3] - Padding? 78 */ 79 note_data = (const uint32_t *)(note_name + note->n_namesz); 80 81 /* Only handle AArch64 feature notes */ 82 if (note_data[0] != GNU_PROPERTY_AARCH64_FEATURE_1_AND) 83 return (false); 84 85 /* We expect at least 4 bytes of data */ 86 if (note_data[1] < 4) 87 return (false); 88 89 /* TODO: Only guard if HWCAP2_BTI is set */ 90 if ((note_data[2] & GNU_PROPERTY_AARCH64_FEATURE_1_BTI) != 0) { 91 struct arm64_guard_page_args guard; 92 93 guard.addr = (uintptr_t)obj->mapbase; 94 guard.len = obj->mapsize; 95 96 sysarch(ARM64_GUARD_PAGE, &guard); 97 } 98 99 return (true); 100 } 101 102 void 103 init_pltgot(Obj_Entry *obj) 104 { 105 106 if (obj->pltgot != NULL) { 107 obj->pltgot[1] = (Elf_Addr) obj; 108 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 109 } 110 } 111 112 int 113 do_copy_relocations(Obj_Entry *dstobj) 114 { 115 const Obj_Entry *srcobj, *defobj; 116 const Elf_Rela *relalim; 117 const Elf_Rela *rela; 118 const Elf_Sym *srcsym; 119 const Elf_Sym *dstsym; 120 const void *srcaddr; 121 const char *name; 122 void *dstaddr; 123 SymLook req; 124 size_t size; 125 int res; 126 127 /* 128 * COPY relocs are invalid outside of the main program 129 */ 130 assert(dstobj->mainprog); 131 132 relalim = (const Elf_Rela *)((const char *)dstobj->rela + 133 dstobj->relasize); 134 for (rela = dstobj->rela; rela < relalim; rela++) { 135 if (ELF_R_TYPE(rela->r_info) != R_AARCH64_COPY) 136 continue; 137 138 dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 139 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 140 name = dstobj->strtab + dstsym->st_name; 141 size = dstsym->st_size; 142 143 symlook_init(&req, name); 144 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); 145 req.flags = SYMLOOK_EARLY; 146 147 for (srcobj = globallist_next(dstobj); srcobj != NULL; 148 srcobj = globallist_next(srcobj)) { 149 res = symlook_obj(&req, srcobj); 150 if (res == 0) { 151 srcsym = req.sym_out; 152 defobj = req.defobj_out; 153 break; 154 } 155 } 156 if (srcobj == NULL) { 157 _rtld_error("Undefined symbol \"%s\" referenced from " 158 "COPY relocation in %s", name, dstobj->path); 159 return (-1); 160 } 161 162 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value); 163 memcpy(dstaddr, srcaddr, size); 164 } 165 166 return (0); 167 } 168 169 struct tls_data { 170 Elf_Addr dtv_gen; 171 int tls_index; 172 Elf_Addr tls_offs; 173 }; 174 175 static Elf_Addr 176 reloc_tlsdesc_alloc(int tlsindex, Elf_Addr tlsoffs) 177 { 178 struct tls_data *tlsdesc; 179 180 tlsdesc = xmalloc(sizeof(struct tls_data)); 181 tlsdesc->dtv_gen = tls_dtv_generation; 182 tlsdesc->tls_index = tlsindex; 183 tlsdesc->tls_offs = tlsoffs; 184 185 return ((Elf_Addr)tlsdesc); 186 } 187 188 static void 189 reloc_tlsdesc(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *where, 190 int flags, RtldLockState *lockstate) 191 { 192 const Elf_Sym *def; 193 const Obj_Entry *defobj; 194 Elf_Addr offs; 195 196 197 offs = 0; 198 if (ELF_R_SYM(rela->r_info) != 0) { 199 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, flags, 200 NULL, lockstate); 201 if (def == NULL) 202 rtld_die(); 203 offs = def->st_value; 204 obj = defobj; 205 if (def->st_shndx == SHN_UNDEF) { 206 /* Weak undefined thread variable */ 207 where[0] = (Elf_Addr)_rtld_tlsdesc_undef; 208 where[1] = rela->r_addend; 209 return; 210 } 211 } 212 offs += rela->r_addend; 213 214 if (obj->tlsoffset != 0) { 215 /* Variable is in initialy allocated TLS segment */ 216 where[0] = (Elf_Addr)_rtld_tlsdesc_static; 217 where[1] = obj->tlsoffset + offs; 218 } else { 219 /* TLS offest is unknown at load time, use dynamic resolving */ 220 where[0] = (Elf_Addr)_rtld_tlsdesc_dynamic; 221 where[1] = reloc_tlsdesc_alloc(obj->tlsindex, offs); 222 } 223 } 224 225 /* 226 * Process the PLT relocations. 227 */ 228 int 229 reloc_plt(Obj_Entry *obj, int flags, RtldLockState *lockstate) 230 { 231 const Elf_Rela *relalim; 232 const Elf_Rela *rela; 233 234 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 235 obj->pltrelasize); 236 for (rela = obj->pltrela; rela < relalim; rela++) { 237 Elf_Addr *where; 238 239 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 240 241 switch(ELF_R_TYPE(rela->r_info)) { 242 case R_AARCH64_JUMP_SLOT: 243 *where += (Elf_Addr)obj->relocbase; 244 break; 245 case R_AARCH64_TLSDESC: 246 reloc_tlsdesc(obj, rela, where, SYMLOOK_IN_PLT | flags, 247 lockstate); 248 break; 249 case R_AARCH64_IRELATIVE: 250 obj->irelative = true; 251 break; 252 case R_AARCH64_NONE: 253 break; 254 default: 255 _rtld_error("Unknown relocation type %u in PLT", 256 (unsigned int)ELF_R_TYPE(rela->r_info)); 257 return (-1); 258 } 259 } 260 261 return (0); 262 } 263 264 /* 265 * LD_BIND_NOW was set - force relocation for all jump slots 266 */ 267 int 268 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) 269 { 270 const Obj_Entry *defobj; 271 const Elf_Rela *relalim; 272 const Elf_Rela *rela; 273 const Elf_Sym *def; 274 275 if (obj->jmpslots_done) 276 return (0); 277 278 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 279 obj->pltrelasize); 280 for (rela = obj->pltrela; rela < relalim; rela++) { 281 Elf_Addr *where, target; 282 283 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 284 switch(ELF_R_TYPE(rela->r_info)) { 285 case R_AARCH64_JUMP_SLOT: 286 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 287 &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); 288 if (def == NULL) 289 return (-1); 290 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 291 obj->gnu_ifunc = true; 292 continue; 293 } 294 target = (Elf_Addr)(defobj->relocbase + def->st_value); 295 reloc_jmpslot(where, target, defobj, obj, 296 (const Elf_Rel *)rela); 297 break; 298 } 299 } 300 obj->jmpslots_done = true; 301 302 return (0); 303 } 304 305 static void 306 reloc_iresolve_one(Obj_Entry *obj, const Elf_Rela *rela, 307 RtldLockState *lockstate) 308 { 309 Elf_Addr *where, target, *ptr; 310 311 ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend); 312 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 313 lock_release(rtld_bind_lock, lockstate); 314 target = call_ifunc_resolver(ptr); 315 wlock_acquire(rtld_bind_lock, lockstate); 316 *where = target; 317 } 318 319 int 320 reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 321 { 322 const Elf_Rela *relalim; 323 const Elf_Rela *rela; 324 325 if (!obj->irelative) 326 return (0); 327 obj->irelative = false; 328 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 329 obj->pltrelasize); 330 for (rela = obj->pltrela; rela < relalim; rela++) { 331 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_IRELATIVE) 332 reloc_iresolve_one(obj, rela, lockstate); 333 } 334 return (0); 335 } 336 337 int 338 reloc_iresolve_nonplt(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 339 { 340 const Elf_Rela *relalim; 341 const Elf_Rela *rela; 342 343 if (!obj->irelative_nonplt) 344 return (0); 345 obj->irelative_nonplt = false; 346 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 347 for (rela = obj->rela; rela < relalim; rela++) { 348 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_IRELATIVE) 349 reloc_iresolve_one(obj, rela, lockstate); 350 } 351 return (0); 352 } 353 354 int 355 reloc_gnu_ifunc(Obj_Entry *obj, int flags, 356 struct Struct_RtldLockState *lockstate) 357 { 358 const Elf_Rela *relalim; 359 const Elf_Rela *rela; 360 Elf_Addr *where, target; 361 const Elf_Sym *def; 362 const Obj_Entry *defobj; 363 364 if (!obj->gnu_ifunc) 365 return (0); 366 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 367 for (rela = obj->pltrela; rela < relalim; rela++) { 368 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_JUMP_SLOT) { 369 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 370 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 371 SYMLOOK_IN_PLT | flags, NULL, lockstate); 372 if (def == NULL) 373 return (-1); 374 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC) 375 continue; 376 lock_release(rtld_bind_lock, lockstate); 377 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); 378 wlock_acquire(rtld_bind_lock, lockstate); 379 reloc_jmpslot(where, target, defobj, obj, 380 (const Elf_Rel *)rela); 381 } 382 } 383 obj->gnu_ifunc = false; 384 return (0); 385 } 386 387 Elf_Addr 388 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, 389 const Obj_Entry *defobj __unused, const Obj_Entry *obj __unused, 390 const Elf_Rel *rel) 391 { 392 393 assert(ELF_R_TYPE(rel->r_info) == R_AARCH64_JUMP_SLOT || 394 ELF_R_TYPE(rel->r_info) == R_AARCH64_IRELATIVE); 395 396 if (*where != target && !ld_bind_not) 397 *where = target; 398 return (target); 399 } 400 401 void 402 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused) 403 { 404 405 } 406 407 /* 408 * Process non-PLT relocations 409 */ 410 int 411 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, 412 RtldLockState *lockstate) 413 { 414 const Obj_Entry *defobj; 415 const Elf_Rela *relalim; 416 const Elf_Rela *rela; 417 const Elf_Sym *def; 418 SymCache *cache; 419 Elf_Addr *where, symval; 420 421 /* 422 * The dynamic loader may be called from a thread, we have 423 * limited amounts of stack available so we cannot use alloca(). 424 */ 425 if (obj == obj_rtld) 426 cache = NULL; 427 else 428 cache = calloc(obj->dynsymcount, sizeof(SymCache)); 429 /* No need to check for NULL here */ 430 431 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 432 for (rela = obj->rela; rela < relalim; rela++) { 433 /* 434 * First, resolve symbol for relocations which 435 * reference symbols. 436 */ 437 switch (ELF_R_TYPE(rela->r_info)) { 438 case R_AARCH64_ABS64: 439 case R_AARCH64_GLOB_DAT: 440 case R_AARCH64_TLS_TPREL64: 441 case R_AARCH64_TLS_DTPREL64: 442 case R_AARCH64_TLS_DTPMOD64: 443 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 444 &defobj, flags, cache, lockstate); 445 if (def == NULL) 446 return (-1); 447 /* 448 * If symbol is IFUNC, only perform relocation 449 * when caller allowed it by passing 450 * SYMLOOK_IFUNC flag. Skip the relocations 451 * otherwise. 452 * 453 * Also error out in case IFUNC relocations 454 * are specified for TLS, which cannot be 455 * usefully interpreted. 456 */ 457 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 458 switch (ELF_R_TYPE(rela->r_info)) { 459 case R_AARCH64_ABS64: 460 case R_AARCH64_GLOB_DAT: 461 if ((flags & SYMLOOK_IFUNC) == 0) { 462 obj->non_plt_gnu_ifunc = true; 463 continue; 464 } 465 symval = (Elf_Addr)rtld_resolve_ifunc( 466 defobj, def); 467 break; 468 default: 469 _rtld_error("%s: IFUNC for TLS reloc", 470 obj->path); 471 return (-1); 472 } 473 } else { 474 if ((flags & SYMLOOK_IFUNC) != 0) 475 continue; 476 symval = (Elf_Addr)defobj->relocbase + 477 def->st_value; 478 } 479 break; 480 default: 481 if ((flags & SYMLOOK_IFUNC) != 0) 482 continue; 483 } 484 485 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 486 487 switch (ELF_R_TYPE(rela->r_info)) { 488 case R_AARCH64_ABS64: 489 case R_AARCH64_GLOB_DAT: 490 *where = symval + rela->r_addend; 491 break; 492 case R_AARCH64_COPY: 493 /* 494 * These are deferred until all other relocations have 495 * been done. All we do here is make sure that the 496 * COPY relocation is not in a shared library. They 497 * are allowed only in executable files. 498 */ 499 if (!obj->mainprog) { 500 _rtld_error("%s: Unexpected R_AARCH64_COPY " 501 "relocation in shared library", obj->path); 502 return (-1); 503 } 504 break; 505 case R_AARCH64_TLSDESC: 506 reloc_tlsdesc(obj, rela, where, flags, lockstate); 507 break; 508 case R_AARCH64_TLS_TPREL64: 509 /* 510 * We lazily allocate offsets for static TLS as we 511 * see the first relocation that references the 512 * TLS block. This allows us to support (small 513 * amounts of) static TLS in dynamically loaded 514 * modules. If we run out of space, we generate an 515 * error. 516 */ 517 if (!defobj->tls_static) { 518 if (!allocate_tls_offset( 519 __DECONST(Obj_Entry *, defobj))) { 520 _rtld_error( 521 "%s: No space available for static " 522 "Thread Local Storage", obj->path); 523 return (-1); 524 } 525 } 526 *where = def->st_value + rela->r_addend + 527 defobj->tlsoffset; 528 break; 529 530 /* 531 * !!! BEWARE !!! 532 * ARM ELF ABI defines TLS_DTPMOD64 as 1029, and TLS_DTPREL64 533 * as 1028. But actual bfd linker and the glibc RTLD linker 534 * treats TLS_DTPMOD64 as 1028 and TLS_DTPREL64 1029. 535 */ 536 case R_AARCH64_TLS_DTPREL64: /* efectively is TLS_DTPMOD64 */ 537 *where += (Elf_Addr)defobj->tlsindex; 538 break; 539 case R_AARCH64_TLS_DTPMOD64: /* efectively is TLS_DTPREL64 */ 540 *where += (Elf_Addr)(def->st_value + rela->r_addend); 541 break; 542 case R_AARCH64_RELATIVE: 543 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 544 break; 545 case R_AARCH64_NONE: 546 break; 547 case R_AARCH64_IRELATIVE: 548 obj->irelative_nonplt = true; 549 break; 550 default: 551 rtld_printf("%s: Unhandled relocation %lu\n", 552 obj->path, ELF_R_TYPE(rela->r_info)); 553 return (-1); 554 } 555 } 556 557 return (0); 558 } 559 560 void 561 allocate_initial_tls(Obj_Entry *objs) 562 { 563 564 /* 565 * Fix the size of the static TLS block by using the maximum 566 * offset allocated so far and adding a bit for dynamic modules to 567 * use. 568 */ 569 tls_static_space = tls_last_offset + tls_last_size + 570 ld_static_tls_extra; 571 572 _tcb_set(allocate_tls(objs, NULL, TLS_TCB_SIZE, TLS_TCB_ALIGN)); 573 } 574 575 void * 576 __tls_get_addr(tls_index* ti) 577 { 578 uintptr_t **dtvp; 579 580 dtvp = &_tcb_get()->tcb_dtv; 581 return (tls_get_addr_common(dtvp, ti->ti_module, ti->ti_offset)); 582 } 583