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