rtld_machine.c revision 1.7
1/* $OpenBSD: rtld_machine.c,v 1.7 2003/02/02 16:57:58 deraadt Exp $ */ 2 3/* 4 * Copyright (c) 2002 Dale Rahn 5 * Copyright (c) 2001 Niklas Hallqvist 6 * Copyright (c) 2001 Artur Grabowski 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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed under OpenBSD by 19 * Dale Rahn. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 24 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 25 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 27 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35/*- 36 * Copyright (c) 2000 Eduardo Horvath. 37 * Copyright (c) 1999 The NetBSD Foundation, Inc. 38 * All rights reserved. 39 * 40 * This code is derived from software contributed to The NetBSD Foundation 41 * by Paul Kranenburg. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. All advertising materials mentioning features or use of this software 52 * must display the following acknowledgement: 53 * This product includes software developed by the NetBSD 54 * Foundation, Inc. and its contributors. 55 * 4. Neither the name of The NetBSD Foundation nor the names of its 56 * contributors may be used to endorse or promote products derived 57 * from this software without specific prior written permission. 58 * 59 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 60 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 61 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 62 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 63 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 64 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 65 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 66 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 67 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 68 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 69 * POSSIBILITY OF SUCH DAMAGE. 70 */ 71 72#define _DYN_LOADER 73 74#include <sys/types.h> 75#include <sys/cdefs.h> 76#include <sys/mman.h> 77 78#include <nlist.h> 79#include <link.h> 80#include <signal.h> 81 82#include "syscall.h" 83#include "archdep.h" 84#include "resolve.h" 85 86void 87_dl_bcopy(const void *src, void *dest, int size) 88{ 89 const unsigned char *psrc = src; 90 unsigned char *pdest = dest; 91 int i; 92 93 for (i = 0; i < size; i++) 94 pdest[i] = psrc[i]; 95} 96 97/* 98 * The following table holds for each relocation type: 99 * - the width in bits of the memory location the relocation 100 * applies to (not currently used) 101 * - the number of bits the relocation value must be shifted to the 102 * right (i.e. discard least significant bits) to fit into 103 * the appropriate field in the instruction word. 104 * - flags indicating whether 105 * * the relocation involves a symbol 106 * * the relocation is relative to the current position 107 * * the relocation is for a GOT entry 108 * * the relocation is relative to the load address 109 * 110 */ 111#define _RF_S 0x80000000 /* Resolve symbol */ 112#define _RF_A 0x40000000 /* Use addend */ 113#define _RF_P 0x20000000 /* Location relative */ 114#define _RF_G 0x10000000 /* GOT offset */ 115#define _RF_B 0x08000000 /* Load address relative */ 116#define _RF_U 0x04000000 /* Unaligned */ 117#define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */ 118#define _RF_RS(s) ((s) & 0xff) /* right shift */ 119static int reloc_target_flags[] = { 120 0, /* NONE */ 121 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32*/ 122 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC32 */ 123 _RF_G| _RF_SZ(32) | _RF_RS(00), /* GOT32 */ 124 _RF_A| _RF_SZ(32) | _RF_RS(0), /* PLT32 */ 125 _RF_S| _RF_SZ(32) | _RF_RS(0), /* COPY */ 126 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */ 127 _RF_S| _RF_SZ(32) | _RF_RS(0), /* JUMP_SLOT */ 128 _RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */ 129 0, /* GOTOFF XXX */ 130 0, /* GOTPC XXX */ 131 0, /* DUMMY 11 */ 132 0, /* DUMMY 12 */ 133 0, /* DUMMY 13 */ 134 0, /* DUMMY 14 */ 135 0, /* DUMMY 15 */ 136 0, /* DUMMY 16 */ 137 0, /* DUMMY 17 */ 138 0, /* DUMMY 18 */ 139 0, /* DUMMY 19 */ 140 _RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */ 141 _RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* PC_16 */ 142 _RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */ 143 _RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* RELOC_PC8 */ 144}; 145 146#define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0) 147#define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0) 148#define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0) 149#define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0) 150#define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0) 151#define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff) 152#define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff) 153 154static long reloc_target_bitmask[] = { 155#define _BM(x) (~(-(1ULL << (x)))) 156 0, /* NONE */ 157 _BM(32), /* RELOC_32*/ 158 _BM(32), /* PC32 */ 159 _BM(32), /* GOT32 */ 160 _BM(32), /* PLT32 */ 161 0, /* COPY */ 162 _BM(32), /* GLOB_DAT */ 163 _BM(32), /* JUMP_SLOT */ 164 _BM(32), /* RELATIVE */ 165 0, /* GOTOFF XXX */ 166 0, /* GOTPC XXX */ 167 0, /* DUMMY 11 */ 168 0, /* DUMMY 12 */ 169 0, /* DUMMY 13 */ 170 0, /* DUMMY 14 */ 171 0, /* DUMMY 15 */ 172 0, /* DUMMY 16 */ 173 0, /* DUMMY 17 */ 174 0, /* DUMMY 18 */ 175 0, /* DUMMY 19 */ 176 _BM(16), /* RELOC_16 */ 177 _BM(8), /* PC_16 */ 178 _BM(8), /* RELOC_8 */ 179 _BM(8), /* RELOC_PC8 */ 180#undef _BM 181}; 182#define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t]) 183 184void _dl_reloc_plt(Elf_Addr *where, Elf_Addr value); 185 186int 187_dl_md_reloc(elf_object_t *object, int rel, int relsz) 188{ 189 long i; 190 long numrel; 191 long fails = 0; 192 Elf_Addr loff; 193 Elf_Rel *rels; 194 struct load_list *llist; 195 196 loff = object->load_offs; 197 numrel = object->Dyn.info[relsz] / sizeof(Elf32_Rel); 198 rels = (Elf32_Rel *)(object->Dyn.info[rel]); 199 if (rels == NULL) 200 return(0); 201 202 /* 203 * unprotect some segments if we need it. 204 */ 205 if ((rel == DT_REL || rel == DT_RELA)) { 206 for (llist = object->load_list; llist != NULL; llist = llist->next) { 207 if (!(llist->prot & PROT_WRITE)) 208 _dl_mprotect(llist->start, llist->size, 209 llist->prot|PROT_WRITE); 210 } 211 } 212 213 for (i = 0; i < numrel; i++, rels++) { 214 Elf_Addr *where, value, ooff, mask; 215 Elf_Word type; 216 const Elf_Sym *sym, *this; 217 const char *symn; 218 219 type = ELF_R_TYPE(rels->r_info); 220 221 if (type == R_TYPE(NONE)) 222 continue; 223 224 if (type == R_TYPE(JUMP_SLOT) && rel != DT_JMPREL) 225 continue; 226 227 where = (Elf_Addr *)(rels->r_offset + loff); 228 229 if (RELOC_USE_ADDEND(type)) 230 value = *where & RELOC_VALUE_BITMASK(type); 231 else 232 value = 0; 233 234 sym = NULL; 235 symn = NULL; 236 if (RELOC_RESOLVE_SYMBOL(type)) { 237 sym = object->dyn.symtab; 238 sym += ELF_R_SYM(rels->r_info); 239 symn = object->dyn.strtab + sym->st_name; 240 241 if (sym->st_shndx != SHN_UNDEF && 242 ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 243 value += loff; 244 } else { 245 this = NULL; 246 ooff = _dl_find_symbol(symn, _dl_objects, 247 &this, SYM_SEARCH_ALL|SYM_WARNNOTFOUND| 248 ((type == R_TYPE(JUMP_SLOT))? 249 SYM_PLT:SYM_NOTPLT), 250 sym->st_size, object->load_name); 251 if (this == NULL) { 252resolve_failed: 253 _dl_printf("%s: %s: can't resolve " 254 "reference '%s'\n", 255 _dl_progname, object->load_name, 256 symn); 257 fails++; 258 continue; 259 } 260 value += (Elf_Addr)(ooff + this->st_value); 261 } 262 } 263 264 if (type == R_TYPE(JUMP_SLOT)) { 265 _dl_reloc_plt((Elf_Word *)where, value); 266 continue; 267 } 268 269 if (type == R_TYPE(COPY)) { 270 void *dstaddr = where; 271 const void *srcaddr; 272 const Elf_Sym *dstsym = sym, *srcsym = NULL; 273 size_t size = dstsym->st_size; 274 Elf_Addr soff; 275 276 soff = _dl_find_symbol(symn, object->next, &srcsym, 277 SYM_SEARCH_ALL|SYM_WARNNOTFOUND| 278 ((type == R_TYPE(JUMP_SLOT)) ? SYM_PLT:SYM_NOTPLT), 279 size, object->load_name); 280 if (srcsym == NULL) 281 goto resolve_failed; 282 283 srcaddr = (void *)(soff + srcsym->st_value); 284 _dl_bcopy(srcaddr, dstaddr, size); 285 continue; 286 } 287 288 if (RELOC_PC_RELATIVE(type)) 289 value -= (Elf_Addr)where; 290 if (RELOC_BASE_RELATIVE(type)) 291 value += loff; 292 293 mask = RELOC_VALUE_BITMASK(type); 294 value >>= RELOC_VALUE_RIGHTSHIFT(type); 295 value &= mask; 296 297 if (RELOC_UNALIGNED(type)) { 298 /* Handle unaligned relocations. */ 299 Elf_Addr tmp = 0; 300 char *ptr = (char *)where; 301 int i, size = RELOC_TARGET_SIZE(type)/8; 302 303 /* Read it in one byte at a time. */ 304 for (i=0; i<size; i++) 305 tmp = (tmp << 8) | ptr[i]; 306 307 tmp &= ~mask; 308 tmp |= value; 309 310 /* Write it back out. */ 311 for (i=0; i<size; i++) 312 ptr[i] = ((tmp >> (8*i)) & 0xff); 313 } else if (RELOC_TARGET_SIZE(type) > 32) { 314 *where &= ~mask; 315 *where |= value; 316 } else { 317 Elf32_Addr *where32 = (Elf32_Addr *)where; 318 319 *where32 &= ~mask; 320 *where32 |= value; 321 } 322 } 323 324 /* reprotect the unprotected segments */ 325 if ((rel == DT_REL || rel == DT_RELA)) { 326 for (llist = object->load_list; llist != NULL; llist = llist->next) { 327 if (!(llist->prot & PROT_WRITE)) 328 _dl_mprotect(llist->start, llist->size, 329 llist->prot); 330 } 331 } 332 333 return (fails); 334} 335 336#if 0 337struct jmpslot { 338 u_short opcode; 339 u_short addr[2]; 340 u_short reloc_index; 341#define JMPSLOT_RELOC_MASK 0xffff 342}; 343#define JUMP 0xe990 /* NOP + JMP opcode */ 344#endif 345 346void 347_dl_reloc_plt(Elf_Addr *where, Elf_Addr value) 348{ 349 *where = value; 350} 351 352/* 353 * Resolve a symbol at run-time. 354 */ 355Elf_Addr 356_dl_bind(elf_object_t *object, int index) 357{ 358 Elf_Rel *rel; 359 Elf_Word *addr; 360 const Elf_Sym *sym, *this; 361 const char *symn; 362 Elf_Addr ooff; 363 sigset_t omask, nmask; 364 365 rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]); 366 367 rel += index/sizeof(Elf_Rel); 368 369 sym = object->dyn.symtab; 370 sym += ELF_R_SYM(rel->r_info); 371 symn = object->dyn.strtab + sym->st_name; 372 373 addr = (Elf_Word *)(object->load_offs + rel->r_offset); 374 this = NULL; 375 ooff = _dl_find_symbol(symn, _dl_objects, &this, 376 SYM_SEARCH_ALL|SYM_WARNNOTFOUND|SYM_PLT, 0, object->load_name); 377 if (this == NULL) { 378 _dl_printf("lazy binding failed!\n"); 379 *((int *)0) = 0; /* XXX */ 380 } 381 382 /* if GOT is protected, allow the write */ 383 if (object->got_addr != NULL && object->got_size != 0) { 384 sigfillset(&nmask); 385 _dl_sigprocmask(SIG_BLOCK, &nmask, &omask); 386 _dl_mprotect((void*)object->got_addr, object->got_size, 387 PROT_READ|PROT_WRITE); 388 } 389 390 _dl_reloc_plt(addr, ooff + this->st_value); 391 392 /* put the GOT back to RO */ 393 if (object->got_addr != NULL && object->got_size != 0) { 394 _dl_mprotect((void*)object->got_addr, object->got_size, 395 PROT_READ); 396 _dl_sigprocmask(SIG_SETMASK, &omask, NULL); 397 } 398 399 return((Elf_Addr)ooff + this->st_value); 400} 401 402void 403_dl_md_reloc_got(elf_object_t *object, int lazy) 404{ 405 extern void _dl_bind_start(void); /* XXX */ 406 Elf_Addr *pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT]; 407 int i, num; 408 Elf_Rel *rel; 409 struct load_list *llist; 410 Elf_Addr ooff; 411 const Elf_Sym *this; 412 413 if (pltgot == NULL) 414 return; /* it is possible to have no PLT/GOT relocations */ 415 416 pltgot[1] = (Elf_Addr)object; 417 pltgot[2] = (Elf_Addr)&_dl_bind_start; 418 419 if (object->Dyn.info[DT_PLTREL] != DT_REL) 420 return; 421 422 this = NULL; 423 ooff = _dl_find_symbol("__got_start", object, &this, 424 SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, SYM_NOTPLT, 425 NULL); 426 if (this != NULL) 427 object->got_addr = ooff + this->st_value; 428 429 this = NULL; 430 ooff = _dl_find_symbol("__got_end", object, &this, 431 SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, SYM_NOTPLT, 432 NULL); 433 if (this != NULL) 434 object->got_size = ooff + this->st_value - object->got_addr; 435 436 this = NULL; 437 ooff = _dl_find_symbol("__plt_start", object, &this, 438 SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, SYM_NOTPLT, 439 NULL); 440 if (this != NULL) 441 object->plt_addr = ooff + this->st_value; 442 443 this = NULL; 444 ooff = _dl_find_symbol("__plt_end", object, &this, 445 SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, SYM_NOTPLT, 446 NULL); 447 if (this != NULL) 448 object->plt_size = ooff + this->st_value - object->plt_addr; 449 450 if (!lazy) { 451 _dl_md_reloc(object, DT_JMPREL, DT_PLTRELSZ); 452 return; 453 } 454 455 rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]); 456 num = (object->Dyn.info[DT_PLTRELSZ]); 457 for (llist = object->load_list; llist != NULL; llist = llist->next) { 458 if (!(llist->prot & PROT_WRITE)) 459 _dl_mprotect(llist->start, llist->size, 460 llist->prot|PROT_WRITE); 461 } 462 for (i = 0; i < num/sizeof(Elf_Rel); i++, rel++) { 463 Elf_Addr *where; 464 where = (Elf_Addr *)(rel->r_offset + object->load_offs); 465 *where += object->load_offs; 466 } 467 for (llist = object->load_list; llist != NULL; llist = llist->next) { 468 if (!(llist->prot & PROT_WRITE)) 469 _dl_mprotect(llist->start, llist->size, 470 llist->prot); 471 } 472 473 /* PLT is already RO on i386, no point in mprotecting it, just GOT */ 474 if (object->got_addr != NULL && object->got_size != 0) 475 _dl_mprotect((void*)object->got_addr, object->got_size, 476 PROT_READ); 477} 478