1 /* $NetBSD: mdreloc.c,v 1.55 2018/04/03 21:10:27 joerg Exp $ */ 2 3 /*- 4 * Copyright (c) 1999, 2002 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Paul Kranenburg and by Charles M. Hannum. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifndef lint 34 __RCSID("$NetBSD: mdreloc.c,v 1.55 2018/04/03 21:10:27 joerg Exp $"); 35 #endif /* not lint */ 36 37 #include <machine/elf_support.h> 38 39 #include <errno.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 45 #include "rtldenv.h" 46 #include "debug.h" 47 #include "rtld.h" 48 49 /* 50 * The following table holds for each relocation type: 51 * - the width in bits of the memory location the relocation 52 * applies to (not currently used) 53 * - the number of bits the relocation value must be shifted to the 54 * right (i.e. discard least significant bits) to fit into 55 * the appropriate field in the instruction word. 56 * - flags indicating whether 57 * * the relocation involves a symbol 58 * * the relocation is relative to the current position 59 * * the relocation is for a GOT entry 60 * * the relocation is relative to the load address 61 * 62 */ 63 #define _RF_S 0x80000000 /* Resolve symbol */ 64 #define _RF_A 0x40000000 /* Use addend */ 65 #define _RF_P 0x20000000 /* Location relative */ 66 #define _RF_G 0x10000000 /* GOT offset */ 67 #define _RF_B 0x08000000 /* Load address relative */ 68 #define _RF_U 0x04000000 /* Unaligned */ 69 #define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */ 70 #define _RF_RS(s) ( (s) & 0xff) /* right shift */ 71 static const int reloc_target_flags[R_TYPE(TLS_TPOFF64)+1] = { 72 0, /* NONE */ 73 _RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */ 74 _RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */ 75 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32 */ 76 _RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* DISP_8 */ 77 _RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* DISP_16 */ 78 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* DISP_32 */ 79 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_30 */ 80 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_22 */ 81 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(10), /* HI22 */ 82 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 22 */ 83 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 13 */ 84 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* LO10 */ 85 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT10 */ 86 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT13 */ 87 _RF_G| _RF_SZ(32) | _RF_RS(10), /* GOT22 */ 88 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC10 */ 89 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(10), /* PC22 */ 90 _RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WPLT30 */ 91 _RF_SZ(32) | _RF_RS(0), /* COPY */ 92 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */ 93 _RF_SZ(32) | _RF_RS(0), /* JMP_SLOT */ 94 _RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */ 95 _RF_S|_RF_A| _RF_U| _RF_SZ(32) | _RF_RS(0), /* UA_32 */ 96 97 /* TLS and 64 bit relocs not listed here... */ 98 }; 99 100 #ifdef RTLD_DEBUG_RELOC 101 static const char *reloc_names[] = { 102 "NONE", "RELOC_8", "RELOC_16", "RELOC_32", "DISP_8", 103 "DISP_16", "DISP_32", "WDISP_30", "WDISP_22", "HI22", 104 "22", "13", "LO10", "GOT10", "GOT13", 105 "GOT22", "PC10", "PC22", "WPLT30", "COPY", 106 "GLOB_DAT", "JMP_SLOT", "RELATIVE", "UA_32", 107 108 /* not used with 32bit userland, besides a few of the TLS ones */ 109 "PLT32", 110 "HIPLT22", "LOPLT10", "LOPLT10", "PCPLT22", "PCPLT32", 111 "10", "11", "64", "OLO10", "HH22", 112 "HM10", "LM22", "PC_HH22", "PC_HM10", "PC_LM22", 113 "WDISP16", "WDISP19", "GLOB_JMP", "7", "5", "6", 114 "DISP64", "PLT64", "HIX22", "LOX10", "H44", "M44", 115 "L44", "REGISTER", "UA64", "UA16", 116 "TLS_GD_HI22", "TLS_GD_LO10", "TLS_GD_ADD", "TLS_GD_CALL", 117 "TLS_LDM_HI22", "TLS_LDM_LO10", "TLS_LDM_ADD", "TLS_LDM_CALL", 118 "TLS_LDO_HIX22", "TLS_LDO_LOX10", "TLS_LDO_ADD", "TLS_IE_HI22", 119 "TLS_IE_LO10", "TLS_IE_LD", "TLS_IE_LDX", "TLS_IE_ADD", "TLS_LE_HIX22", 120 "TLS_LE_LOX10", "TLS_DTPMOD32", "TLS_DTPMOD64", "TLS_DTPOFF32", 121 "TLS_DTPOFF64", "TLS_TPOFF32", "TLS_TPOFF64", 122 }; 123 #endif 124 125 #define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0) 126 #define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0) 127 #define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0) 128 #define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0) 129 #define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0) 130 #define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff) 131 #define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff) 132 #define RELOC_TLS(t) (t >= R_TYPE(TLS_GD_HI22)) 133 134 static const int reloc_target_bitmask[] = { 135 #define _BM(x) (~(-(1ULL << (x)))) 136 0, /* NONE */ 137 _BM(8), _BM(16), _BM(32), /* RELOC_8, _16, _32 */ 138 _BM(8), _BM(16), _BM(32), /* DISP8, DISP16, DISP32 */ 139 _BM(30), _BM(22), /* WDISP30, WDISP22 */ 140 _BM(22), _BM(22), /* HI22, _22 */ 141 _BM(13), _BM(10), /* RELOC_13, _LO10 */ 142 _BM(10), _BM(13), _BM(22), /* GOT10, GOT13, GOT22 */ 143 _BM(10), _BM(22), /* _PC10, _PC22 */ 144 _BM(30), 0, /* _WPLT30, _COPY */ 145 -1, -1, -1, /* _GLOB_DAT, JMP_SLOT, _RELATIVE */ 146 _BM(32) /* _UA32 */ 147 #undef _BM 148 }; 149 #define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t]) 150 151 void _rtld_bind_start(void); 152 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 153 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 154 static inline int _rtld_relocate_plt_object(const Obj_Entry *, 155 const Elf_Rela *, Elf_Addr *); 156 157 void 158 _rtld_setup_pltgot(const Obj_Entry *obj) 159 { 160 /* 161 * PLTGOT is the PLT on the sparc. 162 * The first entry holds the call the dynamic linker. 163 * We construct a `call' sequence that transfers 164 * to `_rtld_bind_start()'. 165 * The second entry holds the object identification. 166 * Note: each PLT entry is three words long. 167 */ 168 #define SAVE 0x9de3bfa0 /* i.e. `save %sp,-96,%sp' */ 169 #define CALL 0x40000000 170 #define NOP 0x01000000 171 obj->pltgot[0] = SAVE; 172 obj->pltgot[1] = CALL | 173 ((Elf_Addr) &_rtld_bind_start - (Elf_Addr) &obj->pltgot[1]) >> 2; 174 obj->pltgot[2] = NOP; 175 obj->pltgot[3] = (Elf_Addr) obj; 176 } 177 178 void 179 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 180 { 181 const Elf_Rela *rela = 0, *relalim; 182 Elf_Addr relasz = 0; 183 Elf_Addr *where; 184 185 for (; dynp->d_tag != DT_NULL; dynp++) { 186 switch (dynp->d_tag) { 187 case DT_RELA: 188 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 189 break; 190 case DT_RELASZ: 191 relasz = dynp->d_un.d_val; 192 break; 193 } 194 } 195 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 196 for (; rela < relalim; rela++) { 197 where = (Elf_Addr *)(relocbase + rela->r_offset); 198 *where += (Elf_Addr)(relocbase + rela->r_addend); 199 } 200 } 201 202 int 203 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 204 { 205 const Elf_Rela *rela; 206 const Elf_Sym *def = NULL; 207 const Obj_Entry *defobj = NULL; 208 unsigned long last_symnum = ULONG_MAX; 209 210 for (rela = obj->rela; rela < obj->relalim; rela++) { 211 Elf_Addr *where; 212 Elf_Word type, value, mask; 213 unsigned long symnum; 214 215 where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 216 217 type = ELF_R_TYPE(rela->r_info); 218 if (type == R_TYPE(NONE)) 219 continue; 220 221 /* We do JMP_SLOTs in _rtld_bind() below */ 222 if (type == R_TYPE(JMP_SLOT)) 223 continue; 224 225 /* IFUNC relocations are handled in _rtld_call_ifunc */ 226 if (type == R_TYPE(IRELATIVE)) { 227 if (obj->ifunc_remaining_nonplt == 0) { 228 obj->ifunc_remaining_nonplt = 229 obj->relalim - rela; 230 } 231 continue; 232 } 233 234 /* COPY relocs are also handled elsewhere */ 235 if (type == R_TYPE(COPY)) 236 continue; 237 238 /* 239 * We use the fact that relocation types are an `enum' 240 * Note: R_SPARC_TLS_TPOFF64 is currently numerically largest. 241 */ 242 if (type > R_TYPE(TLS_TPOFF64)) 243 return (-1); 244 245 value = rela->r_addend; 246 247 if (RELOC_RESOLVE_SYMBOL(type) || RELOC_TLS(type)) { 248 symnum = ELF_R_SYM(rela->r_info); 249 if (last_symnum != symnum) { 250 last_symnum = symnum; 251 def = _rtld_find_symdef(symnum, obj, &defobj, 252 false); 253 if (def == NULL) 254 return -1; 255 } 256 } 257 258 /* 259 * Handle TLS relocations here, they are different. 260 */ 261 if (RELOC_TLS(type)) { 262 switch (type) { 263 case R_TYPE(TLS_DTPMOD32): 264 *where = (Elf_Addr)defobj->tlsindex; 265 266 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 267 obj->strtab + 268 obj->symtab[symnum].st_name, 269 obj->path, (void *)*where)); 270 271 break; 272 273 case R_TYPE(TLS_DTPOFF32): 274 *where = (Elf_Addr)(def->st_value 275 + rela->r_addend); 276 277 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 278 obj->strtab + 279 obj->symtab[symnum].st_name, 280 obj->path, (void *)*where)); 281 282 break; 283 284 case R_TYPE(TLS_TPOFF32): 285 if (!defobj->tls_done && 286 _rtld_tls_offset_allocate(obj)) 287 return -1; 288 289 *where = (Elf_Addr)(def->st_value - 290 defobj->tlsoffset + rela->r_addend); 291 292 rdbg(("TLS_TPOFF32 %s in %s --> %p", 293 obj->strtab + 294 obj->symtab[symnum].st_name, 295 obj->path, (void *)*where)); 296 297 break; 298 } 299 continue; 300 } 301 302 /* 303 * If it is no TLS relocation (handled above), we can not 304 * deal with it if it is beyound R_SPARC_6. 305 */ 306 if (type > R_TYPE(6)) 307 return (-1); 308 309 /* 310 * Handle relative relocs here, as an optimization. 311 */ 312 if (type == R_TYPE(RELATIVE)) { 313 *where += (Elf_Addr)(obj->relocbase + value); 314 rdbg(("RELATIVE in %s --> %p", obj->path, 315 (void *)*where)); 316 continue; 317 } 318 319 if (RELOC_RESOLVE_SYMBOL(type)) { 320 /* Add in the symbol's absolute address */ 321 value += (Elf_Word)(defobj->relocbase + def->st_value); 322 } 323 324 if (RELOC_PC_RELATIVE(type)) { 325 value -= (Elf_Word)where; 326 } 327 328 if (RELOC_BASE_RELATIVE(type)) { 329 /* 330 * Note that even though sparcs use `Elf_rela' 331 * exclusively we still need the implicit memory addend 332 * in relocations referring to GOT entries. 333 * Undoubtedly, someone f*cked this up in the distant 334 * past, and now we're stuck with it in the name of 335 * compatibility for all eternity.. 336 * 337 * In any case, the implicit and explicit should be 338 * mutually exclusive. We provide a check for that 339 * here. 340 */ 341 #define DIAGNOSTIC 342 #ifdef DIAGNOSTIC 343 if (value != 0 && *where != 0) { 344 xprintf("BASE_REL(%s): where=%p, *where 0x%x, " 345 "addend=0x%x, base %p\n", 346 obj->path, where, *where, 347 rela->r_addend, obj->relocbase); 348 } 349 #endif 350 value += (Elf_Word)(obj->relocbase + *where); 351 } 352 353 mask = RELOC_VALUE_BITMASK(type); 354 value >>= RELOC_VALUE_RIGHTSHIFT(type); 355 value &= mask; 356 357 if (RELOC_UNALIGNED(type)) { 358 /* Handle unaligned relocations. */ 359 Elf_Addr tmp = 0; 360 char *ptr = (char *)where; 361 int i, size = RELOC_TARGET_SIZE(type)/8; 362 363 /* Read it in one byte at a time. */ 364 for (i=0; i<size; i++) 365 tmp = (tmp << 8) | ptr[i]; 366 367 tmp &= ~mask; 368 tmp |= value; 369 370 /* Write it back out. */ 371 for (i=0; i<size; i++) 372 ptr[i] = ((tmp >> (8*i)) & 0xff); 373 #ifdef RTLD_DEBUG_RELOC 374 value = (Elf_Word)tmp; 375 #endif 376 377 } else { 378 *where &= ~mask; 379 *where |= value; 380 #ifdef RTLD_DEBUG_RELOC 381 value = (Elf_Word)*where; 382 #endif 383 } 384 #ifdef RTLD_DEBUG_RELOC 385 if (RELOC_RESOLVE_SYMBOL(type)) { 386 rdbg(("%s %s in %s --> %p in %s", reloc_names[type], 387 obj->strtab + obj->symtab[symnum].st_name, 388 obj->path, (void *)value, defobj->path)); 389 } else { 390 rdbg(("%s in %s --> %p", reloc_names[type], 391 obj->path, (void *)value)); 392 } 393 #endif 394 } 395 return (0); 396 } 397 398 int 399 _rtld_relocate_plt_lazy(Obj_Entry *obj) 400 { 401 const Elf_Rela *rela; 402 403 for (rela = obj->pltrelalim; rela-- > obj->pltrela; ) { 404 if (ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_IREL)) 405 obj->ifunc_remaining = obj->pltrelalim - rela + 1; 406 } 407 408 return 0; 409 } 410 411 caddr_t 412 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 413 { 414 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff); 415 Elf_Addr value; 416 int err; 417 418 value = 0; /* XXX gcc */ 419 420 _rtld_shared_enter(); 421 err = _rtld_relocate_plt_object(obj, rela, &value); 422 if (err) 423 _rtld_die(); 424 _rtld_shared_exit(); 425 426 return (caddr_t)value; 427 } 428 429 int 430 _rtld_relocate_plt_objects(const Obj_Entry *obj) 431 { 432 const Elf_Rela *rela = obj->pltrela; 433 434 for (; rela < obj->pltrelalim; rela++) 435 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 436 return -1; 437 438 return 0; 439 } 440 441 static inline int 442 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) 443 { 444 const Elf_Sym *def; 445 const Obj_Entry *defobj; 446 Elf_Word *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 447 Elf_Addr value; 448 unsigned long info = rela->r_info; 449 450 if (ELF_R_TYPE(info) == R_TYPE(JMP_IREL)) 451 return 0; 452 453 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 454 455 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 456 if (__predict_false(def == NULL)) 457 return -1; 458 if (__predict_false(def == &_rtld_sym_zero)) 459 return 0; 460 461 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 462 if (tp == NULL) 463 return 0; 464 value = _rtld_resolve_ifunc(defobj, def); 465 } else { 466 value = (Elf_Addr)(defobj->relocbase + def->st_value); 467 } 468 rdbg(("bind now/fixup in %s --> new=%p", 469 defobj->strtab + def->st_name, (void *)value)); 470 471 sparc_write_branch(where + 1, (void *)value); 472 473 if (tp) 474 *tp = value; 475 476 return 0; 477 } 478