1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright 1996, 1997, 1998, 1999 John D. Polstra. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * $FreeBSD$ 28 */ 29 30 /* 31 * Dynamic linker for ELF. 32 * 33 * John Polstra <jdp@polstra.com>. 34 */ 35 36 #include <sys/param.h> 37 #include <sys/mman.h> 38 #include <machine/cpufunc.h> 39 #include <machine/specialreg.h> 40 #include <machine/sysarch.h> 41 42 #include <dlfcn.h> 43 #include <err.h> 44 #include <errno.h> 45 #include <fcntl.h> 46 #include <stdarg.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <unistd.h> 51 52 #include "debug.h" 53 #include "rtld.h" 54 #include "rtld_tls.h" 55 56 /* 57 * Process the special R_X86_64_COPY relocations in the main program. These 58 * copy data from a shared object into a region in the main program's BSS 59 * segment. 60 * 61 * Returns 0 on success, -1 on failure. 62 */ 63 int 64 do_copy_relocations(Obj_Entry *dstobj) 65 { 66 const Elf_Rela *relalim; 67 const Elf_Rela *rela; 68 69 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */ 70 71 relalim = (const Elf_Rela *)((const char *) dstobj->rela + dstobj->relasize); 72 for (rela = dstobj->rela; rela < relalim; rela++) { 73 if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) { 74 void *dstaddr; 75 const Elf_Sym *dstsym; 76 const char *name; 77 size_t size; 78 const void *srcaddr; 79 const Elf_Sym *srcsym; 80 const Obj_Entry *srcobj, *defobj; 81 SymLook req; 82 int res; 83 84 dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 85 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 86 name = dstobj->strtab + dstsym->st_name; 87 size = dstsym->st_size; 88 symlook_init(&req, name); 89 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); 90 req.flags = SYMLOOK_EARLY; 91 92 for (srcobj = globallist_next(dstobj); srcobj != NULL; 93 srcobj = globallist_next(srcobj)) { 94 res = symlook_obj(&req, srcobj); 95 if (res == 0) { 96 srcsym = req.sym_out; 97 defobj = req.defobj_out; 98 break; 99 } 100 } 101 102 if (srcobj == NULL) { 103 _rtld_error("Undefined symbol \"%s\" referenced from COPY" 104 " relocation in %s", name, dstobj->path); 105 return -1; 106 } 107 108 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value); 109 memcpy(dstaddr, srcaddr, size); 110 } 111 } 112 113 return 0; 114 } 115 116 /* Initialize the special GOT entries. */ 117 void 118 init_pltgot(Obj_Entry *obj) 119 { 120 if (obj->pltgot != NULL) { 121 obj->pltgot[1] = (Elf_Addr) obj; 122 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 123 } 124 } 125 126 /* Process the non-PLT relocations. */ 127 int 128 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, 129 RtldLockState *lockstate) 130 { 131 const Elf_Rela *relalim; 132 const Elf_Rela *rela; 133 SymCache *cache; 134 const Elf_Sym *def; 135 const Obj_Entry *defobj; 136 Elf_Addr *where, symval; 137 Elf32_Addr *where32; 138 int r; 139 140 r = -1; 141 symval = 0; 142 def = NULL; 143 144 /* 145 * The dynamic loader may be called from a thread, we have 146 * limited amounts of stack available so we cannot use alloca(). 147 */ 148 if (obj != obj_rtld) { 149 cache = calloc(obj->dynsymcount, sizeof(SymCache)); 150 /* No need to check for NULL here */ 151 } else 152 cache = NULL; 153 154 relalim = (const Elf_Rela *)((const char*)obj->rela + obj->relasize); 155 for (rela = obj->rela; rela < relalim; rela++) { 156 /* 157 * First, resolve symbol for relocations which 158 * reference symbols. 159 */ 160 switch (ELF_R_TYPE(rela->r_info)) { 161 case R_X86_64_64: 162 case R_X86_64_PC32: 163 case R_X86_64_GLOB_DAT: 164 case R_X86_64_TPOFF64: 165 case R_X86_64_TPOFF32: 166 case R_X86_64_DTPMOD64: 167 case R_X86_64_DTPOFF64: 168 case R_X86_64_DTPOFF32: 169 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 170 &defobj, flags, cache, lockstate); 171 if (def == NULL) 172 goto done; 173 /* 174 * If symbol is IFUNC, only perform relocation 175 * when caller allowed it by passing 176 * SYMLOOK_IFUNC flag. Skip the relocations 177 * otherwise. 178 * 179 * Also error out in case IFUNC relocations 180 * are specified for TLS, which cannot be 181 * usefully interpreted. 182 */ 183 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 184 switch (ELF_R_TYPE(rela->r_info)) { 185 case R_X86_64_64: 186 case R_X86_64_PC32: 187 case R_X86_64_GLOB_DAT: 188 if ((flags & SYMLOOK_IFUNC) == 0) { 189 obj->non_plt_gnu_ifunc = true; 190 continue; 191 } 192 symval = (Elf_Addr)rtld_resolve_ifunc( 193 defobj, def); 194 break; 195 case R_X86_64_TPOFF64: 196 case R_X86_64_TPOFF32: 197 case R_X86_64_DTPMOD64: 198 case R_X86_64_DTPOFF64: 199 case R_X86_64_DTPOFF32: 200 _rtld_error("%s: IFUNC for TLS reloc", 201 obj->path); 202 goto done; 203 } 204 } else { 205 if ((flags & SYMLOOK_IFUNC) != 0) 206 continue; 207 symval = (Elf_Addr)defobj->relocbase + 208 def->st_value; 209 } 210 break; 211 default: 212 if ((flags & SYMLOOK_IFUNC) != 0) 213 continue; 214 break; 215 } 216 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 217 where32 = (Elf32_Addr *)where; 218 219 switch (ELF_R_TYPE(rela->r_info)) { 220 case R_X86_64_NONE: 221 break; 222 case R_X86_64_64: 223 *where = symval + rela->r_addend; 224 break; 225 case R_X86_64_PC32: 226 /* 227 * I don't think the dynamic linker should 228 * ever see this type of relocation. But the 229 * binutils-2.6 tools sometimes generate it. 230 */ 231 *where32 = (Elf32_Addr)(unsigned long)(symval + 232 rela->r_addend - (Elf_Addr)where); 233 break; 234 /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */ 235 case R_X86_64_COPY: 236 /* 237 * These are deferred until all other relocations have 238 * been done. All we do here is make sure that the COPY 239 * relocation is not in a shared library. They are 240 * allowed only in executable files. 241 */ 242 if (!obj->mainprog) { 243 _rtld_error("%s: Unexpected R_X86_64_COPY " 244 "relocation in shared library", obj->path); 245 goto done; 246 } 247 break; 248 case R_X86_64_GLOB_DAT: 249 *where = symval; 250 break; 251 case R_X86_64_TPOFF64: 252 /* 253 * We lazily allocate offsets for static TLS 254 * as we see the first relocation that 255 * references the TLS block. This allows us to 256 * support (small amounts of) static TLS in 257 * dynamically loaded modules. If we run out 258 * of space, we generate an error. 259 */ 260 if (!defobj->tls_done) { 261 if (!allocate_tls_offset( 262 __DECONST(Obj_Entry *, defobj))) { 263 _rtld_error("%s: No space available " 264 "for static Thread Local Storage", 265 obj->path); 266 goto done; 267 } 268 } 269 *where = (Elf_Addr)(def->st_value - defobj->tlsoffset + 270 rela->r_addend); 271 break; 272 case R_X86_64_TPOFF32: 273 /* 274 * We lazily allocate offsets for static TLS 275 * as we see the first relocation that 276 * references the TLS block. This allows us to 277 * support (small amounts of) static TLS in 278 * dynamically loaded modules. If we run out 279 * of space, we generate an error. 280 */ 281 if (!defobj->tls_done) { 282 if (!allocate_tls_offset( 283 __DECONST(Obj_Entry *, defobj))) { 284 _rtld_error("%s: No space available " 285 "for static Thread Local Storage", 286 obj->path); 287 goto done; 288 } 289 } 290 *where32 = (Elf32_Addr)(def->st_value - 291 defobj->tlsoffset + rela->r_addend); 292 break; 293 case R_X86_64_DTPMOD64: 294 *where += (Elf_Addr)defobj->tlsindex; 295 break; 296 case R_X86_64_DTPOFF64: 297 *where += (Elf_Addr)(def->st_value + rela->r_addend); 298 break; 299 case R_X86_64_DTPOFF32: 300 *where32 += (Elf32_Addr)(def->st_value + 301 rela->r_addend); 302 break; 303 case R_X86_64_RELATIVE: 304 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 305 break; 306 case R_X86_64_IRELATIVE: 307 obj->irelative_nonplt = true; 308 break; 309 310 /* 311 * missing: 312 * R_X86_64_GOTPCREL, R_X86_64_32, R_X86_64_32S, R_X86_64_16, 313 * R_X86_64_PC16, R_X86_64_8, R_X86_64_PC8 314 */ 315 default: 316 _rtld_error("%s: Unsupported relocation type %u" 317 " in non-PLT relocations\n", obj->path, 318 (unsigned int)ELF_R_TYPE(rela->r_info)); 319 goto done; 320 } 321 } 322 r = 0; 323 done: 324 free(cache); 325 return (r); 326 } 327 328 /* Process the PLT relocations. */ 329 int 330 reloc_plt(Obj_Entry *obj, int flags __unused, RtldLockState *lockstate __unused) 331 { 332 const Elf_Rela *relalim; 333 const Elf_Rela *rela; 334 335 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 336 for (rela = obj->pltrela; rela < relalim; rela++) { 337 Elf_Addr *where; 338 339 switch(ELF_R_TYPE(rela->r_info)) { 340 case R_X86_64_JMP_SLOT: 341 /* Relocate the GOT slot pointing into the PLT. */ 342 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 343 *where += (Elf_Addr)obj->relocbase; 344 break; 345 346 case R_X86_64_IRELATIVE: 347 obj->irelative = true; 348 break; 349 350 default: 351 _rtld_error("Unknown relocation type %x in PLT", 352 (unsigned int)ELF_R_TYPE(rela->r_info)); 353 return (-1); 354 } 355 } 356 return 0; 357 } 358 359 /* Relocate the jump slots in an object. */ 360 int 361 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) 362 { 363 const Elf_Rela *relalim; 364 const Elf_Rela *rela; 365 366 if (obj->jmpslots_done) 367 return 0; 368 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 369 for (rela = obj->pltrela; rela < relalim; rela++) { 370 Elf_Addr *where, target; 371 const Elf_Sym *def; 372 const Obj_Entry *defobj; 373 374 switch (ELF_R_TYPE(rela->r_info)) { 375 case R_X86_64_JMP_SLOT: 376 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 377 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 378 SYMLOOK_IN_PLT | flags, NULL, lockstate); 379 if (def == NULL) 380 return (-1); 381 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 382 obj->gnu_ifunc = true; 383 continue; 384 } 385 target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); 386 reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela); 387 break; 388 389 case R_X86_64_IRELATIVE: 390 break; 391 392 default: 393 _rtld_error("Unknown relocation type %x in PLT", 394 (unsigned int)ELF_R_TYPE(rela->r_info)); 395 return (-1); 396 } 397 } 398 obj->jmpslots_done = true; 399 return 0; 400 } 401 402 /* Fixup the jump slot at "where" to transfer control to "target". */ 403 Elf_Addr 404 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, 405 const struct Struct_Obj_Entry *obj __unused, 406 const struct Struct_Obj_Entry *refobj __unused, 407 const Elf_Rel *rel __unused) 408 { 409 #ifdef dbg 410 dbg("reloc_jmpslot: *%p = %p", where, (void *)target); 411 #endif 412 if (!ld_bind_not) 413 *where = target; 414 return (target); 415 } 416 417 static void 418 reloc_iresolve_one(Obj_Entry *obj, const Elf_Rela *rela, 419 RtldLockState *lockstate) 420 { 421 Elf_Addr *where, target, *ptr; 422 423 ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend); 424 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 425 lock_release(rtld_bind_lock, lockstate); 426 target = call_ifunc_resolver(ptr); 427 wlock_acquire(rtld_bind_lock, lockstate); 428 *where = target; 429 } 430 431 int 432 reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate) 433 { 434 const Elf_Rela *relalim; 435 const Elf_Rela *rela; 436 437 if (!obj->irelative) 438 return (0); 439 obj->irelative = false; 440 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 441 obj->pltrelasize); 442 for (rela = obj->pltrela; rela < relalim; rela++) { 443 if (ELF_R_TYPE(rela->r_info) == R_X86_64_IRELATIVE) 444 reloc_iresolve_one(obj, rela, lockstate); 445 } 446 return (0); 447 } 448 449 int 450 reloc_iresolve_nonplt(Obj_Entry *obj, RtldLockState *lockstate) 451 { 452 const Elf_Rela *relalim; 453 const Elf_Rela *rela; 454 455 if (!obj->irelative_nonplt) 456 return (0); 457 obj->irelative_nonplt = false; 458 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 459 for (rela = obj->rela; rela < relalim; rela++) { 460 if (ELF_R_TYPE(rela->r_info) == R_X86_64_IRELATIVE) 461 reloc_iresolve_one(obj, rela, lockstate); 462 } 463 return (0); 464 } 465 466 int 467 reloc_gnu_ifunc(Obj_Entry *obj, int flags, RtldLockState *lockstate) 468 { 469 const Elf_Rela *relalim; 470 const Elf_Rela *rela; 471 472 if (!obj->gnu_ifunc) 473 return (0); 474 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 475 for (rela = obj->pltrela; rela < relalim; rela++) { 476 Elf_Addr *where, target; 477 const Elf_Sym *def; 478 const Obj_Entry *defobj; 479 480 switch (ELF_R_TYPE(rela->r_info)) { 481 case R_X86_64_JMP_SLOT: 482 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 483 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 484 SYMLOOK_IN_PLT | flags, NULL, lockstate); 485 if (def == NULL) 486 return (-1); 487 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC) 488 continue; 489 lock_release(rtld_bind_lock, lockstate); 490 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); 491 wlock_acquire(rtld_bind_lock, lockstate); 492 reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela); 493 break; 494 } 495 } 496 obj->gnu_ifunc = false; 497 return (0); 498 } 499 500 uint32_t cpu_feature, cpu_feature2, cpu_stdext_feature, cpu_stdext_feature2; 501 502 void 503 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused) 504 { 505 u_int p[4], cpu_high; 506 507 do_cpuid(1, p); 508 cpu_feature = p[3]; 509 cpu_feature2 = p[2]; 510 do_cpuid(0, p); 511 cpu_high = p[0]; 512 if (cpu_high >= 7) { 513 cpuid_count(7, 0, p); 514 cpu_stdext_feature = p[1]; 515 cpu_stdext_feature2 = p[2]; 516 } 517 } 518 519 void 520 pre_init(void) 521 { 522 523 } 524 525 int __getosreldate(void); 526 527 void 528 allocate_initial_tls(Obj_Entry *objs) 529 { 530 void *addr; 531 532 /* 533 * Fix the size of the static TLS block by using the maximum 534 * offset allocated so far and adding a bit for dynamic 535 * modules to use. 536 */ 537 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA; 538 539 addr = allocate_tls(objs, 0, 3 * sizeof(Elf_Addr), sizeof(Elf_Addr)); 540 if (__getosreldate() >= P_OSREL_WRFSBASE && 541 (cpu_stdext_feature & CPUID_STDEXT_FSGSBASE) != 0) 542 wrfsbase((uintptr_t)addr); 543 else 544 sysarch(AMD64_SET_FSBASE, &addr); 545 } 546 547 void *__tls_get_addr(tls_index *ti) 548 { 549 Elf_Addr** segbase; 550 551 __asm __volatile("movq %%fs:0, %0" : "=r" (segbase)); 552 553 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset); 554 } 555 556 size_t 557 calculate_first_tls_offset(size_t size, size_t align, size_t offset) 558 { 559 size_t res; 560 561 res = roundup(size, align); 562 offset &= align - 1; 563 if (offset != 0) 564 res += align - offset; 565 return (res); 566 } 567 568 size_t 569 calculate_tls_offset(size_t prev_offset, size_t prev_size __unused, size_t size, 570 size_t align, size_t offset) 571 { 572 size_t res; 573 574 res = roundup(prev_offset + size, align); 575 offset &= align - 1; 576 if (offset != 0) 577 res += align - offset; 578 return (res); 579 } 580 size_t 581 calculate_tls_end(size_t off, size_t size __unused) 582 { 583 return (off); 584 } 585