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/segments.h> 39 #include <machine/sysarch.h> 40 41 #include <dlfcn.h> 42 #include <err.h> 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <stdarg.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <unistd.h> 50 51 #include "debug.h" 52 #include "rtld.h" 53 #include "rtld_tls.h" 54 55 /* 56 * Process the special R_386_COPY relocations in the main program. These 57 * copy data from a shared object into a region in the main program's BSS 58 * segment. 59 * 60 * Returns 0 on success, -1 on failure. 61 */ 62 int 63 do_copy_relocations(Obj_Entry *dstobj) 64 { 65 const Elf_Rel *rellim; 66 const Elf_Rel *rel; 67 68 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */ 69 70 rellim = (const Elf_Rel *)((const char *)dstobj->rel + dstobj->relsize); 71 for (rel = dstobj->rel; rel < rellim; rel++) { 72 if (ELF_R_TYPE(rel->r_info) == R_386_COPY) { 73 void *dstaddr; 74 const Elf_Sym *dstsym; 75 const char *name; 76 size_t size; 77 const void *srcaddr; 78 const Elf_Sym *srcsym; 79 const Obj_Entry *srcobj, *defobj; 80 SymLook req; 81 int res; 82 83 dstaddr = (void *)(dstobj->relocbase + rel->r_offset); 84 dstsym = dstobj->symtab + ELF_R_SYM(rel->r_info); 85 name = dstobj->strtab + dstsym->st_name; 86 size = dstsym->st_size; 87 symlook_init(&req, name); 88 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rel->r_info)); 89 req.flags = SYMLOOK_EARLY; 90 91 for (srcobj = globallist_next(dstobj); srcobj != NULL; 92 srcobj = globallist_next(srcobj)) { 93 res = symlook_obj(&req, srcobj); 94 if (res == 0) { 95 srcsym = req.sym_out; 96 defobj = req.defobj_out; 97 break; 98 } 99 } 100 101 if (srcobj == NULL) { 102 _rtld_error("Undefined symbol \"%s\" referenced from COPY" 103 " relocation in %s", name, dstobj->path); 104 return -1; 105 } 106 107 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value); 108 memcpy(dstaddr, srcaddr, size); 109 } 110 } 111 112 return 0; 113 } 114 115 /* Initialize the special GOT entries. */ 116 void 117 init_pltgot(Obj_Entry *obj) 118 { 119 if (obj->pltgot != NULL) { 120 obj->pltgot[1] = (Elf_Addr) obj; 121 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 122 } 123 } 124 125 /* Process the non-PLT relocations. */ 126 int 127 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, 128 RtldLockState *lockstate) 129 { 130 const Elf_Rel *rellim; 131 const Elf_Rel *rel; 132 SymCache *cache; 133 const Elf_Sym *def; 134 const Obj_Entry *defobj; 135 Elf_Addr *where, symval, add; 136 int r; 137 138 r = -1; 139 /* 140 * The dynamic loader may be called from a thread, we have 141 * limited amounts of stack available so we cannot use alloca(). 142 */ 143 if (obj != obj_rtld) { 144 cache = calloc(obj->dynsymcount, sizeof(SymCache)); 145 /* No need to check for NULL here */ 146 } else 147 cache = NULL; 148 149 /* Appease some compilers. */ 150 symval = 0; 151 def = NULL; 152 153 rellim = (const Elf_Rel *)((const char *)obj->rel + obj->relsize); 154 for (rel = obj->rel; rel < rellim; rel++) { 155 switch (ELF_R_TYPE(rel->r_info)) { 156 case R_386_32: 157 case R_386_PC32: 158 case R_386_GLOB_DAT: 159 case R_386_TLS_TPOFF: 160 case R_386_TLS_TPOFF32: 161 case R_386_TLS_DTPMOD32: 162 case R_386_TLS_DTPOFF32: 163 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, 164 flags, cache, lockstate); 165 if (def == NULL) 166 goto done; 167 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 168 switch (ELF_R_TYPE(rel->r_info)) { 169 case R_386_32: 170 case R_386_PC32: 171 case R_386_GLOB_DAT: 172 if ((flags & SYMLOOK_IFUNC) == 0) { 173 obj->non_plt_gnu_ifunc = true; 174 continue; 175 } 176 symval = (Elf_Addr)rtld_resolve_ifunc( 177 defobj, def); 178 break; 179 case R_386_TLS_TPOFF: 180 case R_386_TLS_TPOFF32: 181 case R_386_TLS_DTPMOD32: 182 case R_386_TLS_DTPOFF32: 183 _rtld_error("%s: IFUNC for TLS reloc", 184 obj->path); 185 goto done; 186 } 187 } else { 188 if ((flags & SYMLOOK_IFUNC) != 0) 189 continue; 190 symval = (Elf_Addr)defobj->relocbase + 191 def->st_value; 192 } 193 break; 194 default: 195 if ((flags & SYMLOOK_IFUNC) != 0) 196 continue; 197 break; 198 } 199 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 200 201 switch (ELF_R_TYPE(rel->r_info)) { 202 case R_386_NONE: 203 break; 204 case R_386_32: 205 *where += symval; 206 break; 207 case R_386_PC32: 208 /* 209 * I don't think the dynamic linker should ever 210 * see this type of relocation. But the 211 * binutils-2.6 tools sometimes generate it. 212 */ 213 *where += symval - (Elf_Addr)where; 214 break; 215 case R_386_COPY: 216 /* 217 * These are deferred until all other 218 * relocations have been done. All we do here 219 * is make sure that the COPY relocation is 220 * not in a shared library. They are allowed 221 * only in executable files. 222 */ 223 if (!obj->mainprog) { 224 _rtld_error("%s: Unexpected R_386_COPY " 225 "relocation in shared library", obj->path); 226 goto done; 227 } 228 break; 229 case R_386_GLOB_DAT: 230 *where = symval; 231 break; 232 case R_386_RELATIVE: 233 *where += (Elf_Addr)obj->relocbase; 234 break; 235 case R_386_TLS_TPOFF: 236 case R_386_TLS_TPOFF32: 237 /* 238 * We lazily allocate offsets for static TLS 239 * as we see the first relocation that 240 * references the TLS block. This allows us to 241 * support (small amounts of) static TLS in 242 * dynamically loaded modules. If we run out 243 * of space, we generate an error. 244 */ 245 if (!defobj->tls_done) { 246 if (!allocate_tls_offset( 247 __DECONST(Obj_Entry *, defobj))) { 248 _rtld_error("%s: No space available " 249 "for static Thread Local Storage", 250 obj->path); 251 goto done; 252 } 253 } 254 add = (Elf_Addr)(def->st_value - defobj->tlsoffset); 255 if (ELF_R_TYPE(rel->r_info) == R_386_TLS_TPOFF) 256 *where += add; 257 else 258 *where -= add; 259 break; 260 case R_386_TLS_DTPMOD32: 261 *where += (Elf_Addr)defobj->tlsindex; 262 break; 263 case R_386_TLS_DTPOFF32: 264 *where += (Elf_Addr) def->st_value; 265 break; 266 case R_386_IRELATIVE: 267 obj->irelative_nonplt = true; 268 break; 269 default: 270 _rtld_error("%s: Unsupported relocation type %d" 271 " in non-PLT relocations\n", obj->path, 272 ELF_R_TYPE(rel->r_info)); 273 goto done; 274 } 275 } 276 r = 0; 277 done: 278 free(cache); 279 return (r); 280 } 281 282 /* Process the PLT relocations. */ 283 int 284 reloc_plt(Obj_Entry *obj, int flags __unused, RtldLockState *lockstate __unused) 285 { 286 const Elf_Rel *rellim; 287 const Elf_Rel *rel; 288 289 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize); 290 for (rel = obj->pltrel; rel < rellim; rel++) { 291 Elf_Addr *where/*, val*/; 292 293 switch (ELF_R_TYPE(rel->r_info)) { 294 case R_386_JMP_SLOT: 295 /* Relocate the GOT slot pointing into the PLT. */ 296 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 297 *where += (Elf_Addr)obj->relocbase; 298 break; 299 300 case R_386_IRELATIVE: 301 obj->irelative = true; 302 break; 303 304 default: 305 _rtld_error("Unknown relocation type %x in PLT", 306 ELF_R_TYPE(rel->r_info)); 307 return (-1); 308 } 309 } 310 return 0; 311 } 312 313 /* Relocate the jump slots in an object. */ 314 int 315 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) 316 { 317 const Elf_Rel *rellim; 318 const Elf_Rel *rel; 319 320 if (obj->jmpslots_done) 321 return 0; 322 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize); 323 for (rel = obj->pltrel; rel < rellim; rel++) { 324 Elf_Addr *where, target; 325 const Elf_Sym *def; 326 const Obj_Entry *defobj; 327 328 switch (ELF_R_TYPE(rel->r_info)) { 329 case R_386_JMP_SLOT: 330 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 331 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, 332 SYMLOOK_IN_PLT | flags, NULL, lockstate); 333 if (def == NULL) 334 return (-1); 335 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 336 obj->gnu_ifunc = true; 337 continue; 338 } 339 target = (Elf_Addr)(defobj->relocbase + def->st_value); 340 reloc_jmpslot(where, target, defobj, obj, rel); 341 break; 342 343 case R_386_IRELATIVE: 344 break; 345 346 default: 347 _rtld_error("Unknown relocation type %x in PLT", 348 ELF_R_TYPE(rel->r_info)); 349 return (-1); 350 } 351 } 352 353 obj->jmpslots_done = true; 354 return 0; 355 } 356 357 /* Fixup the jump slot at "where" to transfer control to "target". */ 358 Elf_Addr 359 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, 360 const Obj_Entry *obj __unused, const Obj_Entry *refobj __unused, 361 const Elf_Rel *rel __unused) 362 { 363 #ifdef dbg 364 dbg("reloc_jmpslot: *%p = %p", where, (void *)target); 365 #endif 366 if (!ld_bind_not) 367 *where = target; 368 return (target); 369 } 370 371 static void 372 reloc_iresolve_one(Obj_Entry *obj, const Elf_Rel *rel, 373 RtldLockState *lockstate) 374 { 375 Elf_Addr *where, target; 376 377 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 378 lock_release(rtld_bind_lock, lockstate); 379 target = call_ifunc_resolver(obj->relocbase + *where); 380 wlock_acquire(rtld_bind_lock, lockstate); 381 *where = target; 382 } 383 384 int 385 reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate) 386 { 387 const Elf_Rel *rellim; 388 const Elf_Rel *rel; 389 390 if (!obj->irelative) 391 return (0); 392 obj->irelative = false; 393 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize); 394 for (rel = obj->pltrel; rel < rellim; rel++) { 395 if (ELF_R_TYPE(rel->r_info) == R_386_IRELATIVE) 396 reloc_iresolve_one(obj, rel, lockstate); 397 } 398 return (0); 399 } 400 401 int 402 reloc_iresolve_nonplt(Obj_Entry *obj, RtldLockState *lockstate) 403 { 404 const Elf_Rel *rellim; 405 const Elf_Rel *rel; 406 407 if (!obj->irelative_nonplt) 408 return (0); 409 obj->irelative_nonplt = false; 410 rellim = (const Elf_Rel *)((const char *)obj->rel + obj->relsize); 411 for (rel = obj->rel; rel < rellim; rel++) { 412 if (ELF_R_TYPE(rel->r_info) == R_386_IRELATIVE) 413 reloc_iresolve_one(obj, rel, lockstate); 414 } 415 return (0); 416 } 417 418 int 419 reloc_gnu_ifunc(Obj_Entry *obj, int flags, RtldLockState *lockstate) 420 { 421 const Elf_Rel *rellim; 422 const Elf_Rel *rel; 423 424 if (!obj->gnu_ifunc) 425 return (0); 426 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize); 427 for (rel = obj->pltrel; rel < rellim; rel++) { 428 Elf_Addr *where, target; 429 const Elf_Sym *def; 430 const Obj_Entry *defobj; 431 432 switch (ELF_R_TYPE(rel->r_info)) { 433 case R_386_JMP_SLOT: 434 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 435 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, 436 SYMLOOK_IN_PLT | flags, NULL, lockstate); 437 if (def == NULL) 438 return (-1); 439 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC) 440 continue; 441 lock_release(rtld_bind_lock, lockstate); 442 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); 443 wlock_acquire(rtld_bind_lock, lockstate); 444 reloc_jmpslot(where, target, defobj, obj, rel); 445 break; 446 } 447 } 448 449 obj->gnu_ifunc = false; 450 return (0); 451 } 452 453 uint32_t cpu_feature, cpu_feature2, cpu_stdext_feature, cpu_stdext_feature2; 454 455 static void 456 rtld_cpuid_count(int idx, int cnt, u_int *p) 457 { 458 459 __asm __volatile( 460 " pushl %%ebx\n" 461 " cpuid\n" 462 " movl %%ebx,%1\n" 463 " popl %%ebx\n" 464 : "=a" (p[0]), "=r" (p[1]), "=c" (p[2]), "=d" (p[3]) 465 : "0" (idx), "2" (cnt)); 466 } 467 468 void 469 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused) 470 { 471 u_int p[4], cpu_high; 472 int cpuid_supported; 473 474 __asm __volatile( 475 " pushfl\n" 476 " popl %%eax\n" 477 " movl %%eax,%%ecx\n" 478 " xorl $0x200000,%%eax\n" 479 " pushl %%eax\n" 480 " popfl\n" 481 " pushfl\n" 482 " popl %%eax\n" 483 " xorl %%eax,%%ecx\n" 484 " je 1f\n" 485 " movl $1,%0\n" 486 " jmp 2f\n" 487 "1: movl $0,%0\n" 488 "2:\n" 489 : "=r" (cpuid_supported) : : "eax", "ecx"); 490 if (!cpuid_supported) 491 return; 492 493 rtld_cpuid_count(1, 0, p); 494 cpu_feature = p[3]; 495 cpu_feature2 = p[2]; 496 rtld_cpuid_count(0, 0, p); 497 cpu_high = p[0]; 498 if (cpu_high >= 7) { 499 rtld_cpuid_count(7, 0, p); 500 cpu_stdext_feature = p[1]; 501 cpu_stdext_feature2 = p[2]; 502 } 503 } 504 505 void 506 allocate_initial_tls(Obj_Entry *objs) 507 { 508 void* tls; 509 510 /* 511 * Fix the size of the static TLS block by using the maximum 512 * offset allocated so far and adding a bit for dynamic modules to 513 * use. 514 */ 515 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA; 516 tls = allocate_tls(objs, NULL, 3*sizeof(Elf_Addr), sizeof(Elf_Addr)); 517 i386_set_gsbase(tls); 518 } 519 520 /* GNU ABI */ 521 __attribute__((__regparm__(1))) 522 void * 523 ___tls_get_addr(tls_index *ti) 524 { 525 Elf_Addr **dtvp; 526 527 dtvp = _get_tp(); 528 return (tls_get_addr_common(dtvp, ti->ti_module, ti->ti_offset)); 529 } 530 531 /* Sun ABI */ 532 void * 533 __tls_get_addr(tls_index *ti) 534 { 535 Elf_Addr **dtvp; 536 537 dtvp = _get_tp(); 538 return (tls_get_addr_common(dtvp, ti->ti_module, ti->ti_offset)); 539 } 540 541 size_t 542 calculate_first_tls_offset(size_t size, size_t align, size_t offset) 543 { 544 size_t res; 545 546 res = roundup(size, align); 547 offset &= align - 1; 548 if (offset != 0) 549 res += align - offset; 550 return (res); 551 } 552 553 size_t 554 calculate_tls_offset(size_t prev_offset, size_t prev_size __unused, size_t size, 555 size_t align, size_t offset) 556 { 557 size_t res; 558 559 res = roundup(prev_offset + size, align); 560 offset &= align - 1; 561 if (offset != 0) 562 res += align - offset; 563 return (res); 564 } 565 size_t 566 calculate_tls_end(size_t off, size_t size __unused) 567 { 568 return (off); 569 } 570