1 /* $OpenBSD: rtld_machine.c,v 1.10 2003/07/28 03:11:00 drahn 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 18 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 21 * 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 * Copyright (c) 2000 Eduardo Horvath. 31 * Copyright (c) 1999 The NetBSD Foundation, Inc. 32 * All rights reserved. 33 * 34 * This code is derived from software contributed to The NetBSD Foundation 35 * by Paul Kranenburg. 36 * 37 * Redistribution and use in source and binary forms, with or without 38 * modification, are permitted provided that the following conditions 39 * are met: 40 * 1. Redistributions of source code must retain the above copyright 41 * notice, this list of conditions and the following disclaimer. 42 * 2. Redistributions in binary form must reproduce the above copyright 43 * notice, this list of conditions and the following disclaimer in the 44 * documentation and/or other materials provided with the distribution. 45 * 3. All advertising materials mentioning features or use of this software 46 * must display the following acknowledgement: 47 * This product includes software developed by the NetBSD 48 * Foundation, Inc. and its contributors. 49 * 4. Neither the name of The NetBSD Foundation nor the names of its 50 * contributors may be used to endorse or promote products derived 51 * from this software without specific prior written permission. 52 * 53 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 54 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 55 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 56 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 57 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 58 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 59 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 60 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 61 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 62 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 63 * POSSIBILITY OF SUCH DAMAGE. 64 */ 65 66 #define _DYN_LOADER 67 68 #include <sys/types.h> 69 #include <sys/cdefs.h> 70 #include <sys/mman.h> 71 72 #include <nlist.h> 73 #include <link.h> 74 #include <signal.h> 75 76 #include "syscall.h" 77 #include "archdep.h" 78 #include "resolve.h" 79 80 void 81 _dl_bcopy(const void *src, void *dest, int size) 82 { 83 const unsigned char *psrc = src; 84 unsigned char *pdest = dest; 85 int i; 86 87 for (i = 0; i < size; i++) 88 pdest[i] = psrc[i]; 89 } 90 91 /* 92 * The following table holds for each relocation type: 93 * - the width in bits of the memory location the relocation 94 * applies to (not currently used) 95 * - the number of bits the relocation value must be shifted to the 96 * right (i.e. discard least significant bits) to fit into 97 * the appropriate field in the instruction word. 98 * - flags indicating whether 99 * * the relocation involves a symbol 100 * * the relocation is relative to the current position 101 * * the relocation is for a GOT entry 102 * * the relocation is relative to the load address 103 * 104 */ 105 #define _RF_S 0x80000000 /* Resolve symbol */ 106 #define _RF_A 0x40000000 /* Use addend */ 107 #define _RF_P 0x20000000 /* Location relative */ 108 #define _RF_G 0x10000000 /* GOT offset */ 109 #define _RF_B 0x08000000 /* Load address relative */ 110 #define _RF_U 0x04000000 /* Unaligned */ 111 #define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */ 112 #define _RF_RS(s) ((s) & 0xff) /* right shift */ 113 static int reloc_target_flags[] = { 114 0, /* NONE */ 115 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32*/ 116 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC32 */ 117 _RF_G| _RF_SZ(32) | _RF_RS(00), /* GOT32 */ 118 _RF_A| _RF_SZ(32) | _RF_RS(0), /* PLT32 */ 119 _RF_S| _RF_SZ(32) | _RF_RS(0), /* COPY */ 120 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */ 121 _RF_S| _RF_SZ(32) | _RF_RS(0), /* JUMP_SLOT */ 122 _RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */ 123 0, /* GOTOFF XXX */ 124 0, /* GOTPC XXX */ 125 0, /* DUMMY 11 */ 126 0, /* DUMMY 12 */ 127 0, /* DUMMY 13 */ 128 0, /* DUMMY 14 */ 129 0, /* DUMMY 15 */ 130 0, /* DUMMY 16 */ 131 0, /* DUMMY 17 */ 132 0, /* DUMMY 18 */ 133 0, /* DUMMY 19 */ 134 _RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */ 135 _RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* PC_16 */ 136 _RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */ 137 _RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* RELOC_PC8 */ 138 }; 139 140 #define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0) 141 #define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0) 142 #define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0) 143 #define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0) 144 #define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0) 145 #define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff) 146 #define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff) 147 148 static long reloc_target_bitmask[] = { 149 #define _BM(x) (~(-(1ULL << (x)))) 150 0, /* NONE */ 151 _BM(32), /* RELOC_32*/ 152 _BM(32), /* PC32 */ 153 _BM(32), /* GOT32 */ 154 _BM(32), /* PLT32 */ 155 0, /* COPY */ 156 _BM(32), /* GLOB_DAT */ 157 _BM(32), /* JUMP_SLOT */ 158 _BM(32), /* RELATIVE */ 159 0, /* GOTOFF XXX */ 160 0, /* GOTPC XXX */ 161 0, /* DUMMY 11 */ 162 0, /* DUMMY 12 */ 163 0, /* DUMMY 13 */ 164 0, /* DUMMY 14 */ 165 0, /* DUMMY 15 */ 166 0, /* DUMMY 16 */ 167 0, /* DUMMY 17 */ 168 0, /* DUMMY 18 */ 169 0, /* DUMMY 19 */ 170 _BM(16), /* RELOC_16 */ 171 _BM(8), /* PC_16 */ 172 _BM(8), /* RELOC_8 */ 173 _BM(8), /* RELOC_PC8 */ 174 #undef _BM 175 }; 176 #define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t]) 177 178 void _dl_reloc_plt(Elf_Addr *where, Elf_Addr value); 179 180 int 181 _dl_md_reloc(elf_object_t *object, int rel, int relsz) 182 { 183 long i; 184 long numrel; 185 long fails = 0; 186 Elf_Addr loff; 187 Elf_Rel *rels; 188 struct load_list *llist; 189 190 loff = object->load_offs; 191 numrel = object->Dyn.info[relsz] / sizeof(Elf32_Rel); 192 rels = (Elf32_Rel *)(object->Dyn.info[rel]); 193 if (rels == NULL) 194 return(0); 195 196 /* 197 * unprotect some segments if we need it. 198 */ 199 if ((rel == DT_REL || rel == DT_RELA)) { 200 for (llist = object->load_list; llist != NULL; llist = llist->next) { 201 if (!(llist->prot & PROT_WRITE)) 202 _dl_mprotect(llist->start, llist->size, 203 llist->prot|PROT_WRITE); 204 } 205 } 206 207 for (i = 0; i < numrel; i++, rels++) { 208 Elf_Addr *where, value, ooff, mask; 209 Elf_Word type; 210 const Elf_Sym *sym, *this; 211 const char *symn; 212 213 type = ELF_R_TYPE(rels->r_info); 214 215 if (type == R_TYPE(NONE)) 216 continue; 217 218 if (type == R_TYPE(JUMP_SLOT) && rel != DT_JMPREL) 219 continue; 220 221 where = (Elf_Addr *)(rels->r_offset + loff); 222 223 if (RELOC_USE_ADDEND(type)) 224 value = *where & RELOC_VALUE_BITMASK(type); 225 else 226 value = 0; 227 228 sym = NULL; 229 symn = NULL; 230 if (RELOC_RESOLVE_SYMBOL(type)) { 231 sym = object->dyn.symtab; 232 sym += ELF_R_SYM(rels->r_info); 233 symn = object->dyn.strtab + sym->st_name; 234 235 if (sym->st_shndx != SHN_UNDEF && 236 ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 237 value += loff; 238 } else { 239 this = NULL; 240 ooff = _dl_find_symbol(symn, _dl_objects, 241 &this, SYM_SEARCH_ALL|SYM_WARNNOTFOUND| 242 ((type == R_TYPE(JUMP_SLOT))? 243 SYM_PLT:SYM_NOTPLT), 244 sym->st_size, object->load_name); 245 if (this == NULL) { 246 resolve_failed: 247 _dl_printf("%s: %s: can't resolve " 248 "reference '%s'\n", 249 _dl_progname, object->load_name, 250 symn); 251 fails++; 252 continue; 253 } 254 value += (Elf_Addr)(ooff + this->st_value); 255 } 256 } 257 258 if (type == R_TYPE(JUMP_SLOT)) { 259 _dl_reloc_plt((Elf_Word *)where, value); 260 continue; 261 } 262 263 if (type == R_TYPE(COPY)) { 264 void *dstaddr = where; 265 const void *srcaddr; 266 const Elf_Sym *dstsym = sym, *srcsym = NULL; 267 size_t size = dstsym->st_size; 268 Elf_Addr soff; 269 270 soff = _dl_find_symbol(symn, object->next, &srcsym, 271 SYM_SEARCH_ALL|SYM_WARNNOTFOUND| 272 ((type == R_TYPE(JUMP_SLOT)) ? SYM_PLT:SYM_NOTPLT), 273 size, object->load_name); 274 if (srcsym == NULL) 275 goto resolve_failed; 276 277 srcaddr = (void *)(soff + srcsym->st_value); 278 _dl_bcopy(srcaddr, dstaddr, size); 279 continue; 280 } 281 282 if (RELOC_PC_RELATIVE(type)) 283 value -= (Elf_Addr)where; 284 if (RELOC_BASE_RELATIVE(type)) 285 value += loff; 286 287 mask = RELOC_VALUE_BITMASK(type); 288 value >>= RELOC_VALUE_RIGHTSHIFT(type); 289 value &= mask; 290 291 if (RELOC_UNALIGNED(type)) { 292 /* Handle unaligned relocations. */ 293 Elf_Addr tmp = 0; 294 char *ptr = (char *)where; 295 int i, size = RELOC_TARGET_SIZE(type)/8; 296 297 /* Read it in one byte at a time. */ 298 for (i=0; i<size; i++) 299 tmp = (tmp << 8) | ptr[i]; 300 301 tmp &= ~mask; 302 tmp |= value; 303 304 /* Write it back out. */ 305 for (i=0; i<size; i++) 306 ptr[i] = ((tmp >> (8*i)) & 0xff); 307 } else if (RELOC_TARGET_SIZE(type) > 32) { 308 *where &= ~mask; 309 *where |= value; 310 } else { 311 Elf32_Addr *where32 = (Elf32_Addr *)where; 312 313 *where32 &= ~mask; 314 *where32 |= value; 315 } 316 } 317 318 /* reprotect the unprotected segments */ 319 if ((rel == DT_REL || rel == DT_RELA)) { 320 for (llist = object->load_list; llist != NULL; llist = llist->next) { 321 if (!(llist->prot & PROT_WRITE)) 322 _dl_mprotect(llist->start, llist->size, 323 llist->prot); 324 } 325 } 326 327 return (fails); 328 } 329 330 #if 0 331 struct jmpslot { 332 u_short opcode; 333 u_short addr[2]; 334 u_short reloc_index; 335 #define JMPSLOT_RELOC_MASK 0xffff 336 }; 337 #define JUMP 0xe990 /* NOP + JMP opcode */ 338 #endif 339 340 void 341 _dl_reloc_plt(Elf_Addr *where, Elf_Addr value) 342 { 343 *where = value; 344 } 345 346 /* 347 * Resolve a symbol at run-time. 348 */ 349 Elf_Addr 350 _dl_bind(elf_object_t *object, int index) 351 { 352 Elf_Rel *rel; 353 Elf_Word *addr; 354 const Elf_Sym *sym, *this; 355 const char *symn; 356 Elf_Addr ooff; 357 sigset_t omask, nmask; 358 359 rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]); 360 361 rel += index/sizeof(Elf_Rel); 362 363 sym = object->dyn.symtab; 364 sym += ELF_R_SYM(rel->r_info); 365 symn = object->dyn.strtab + sym->st_name; 366 367 addr = (Elf_Word *)(object->load_offs + rel->r_offset); 368 this = NULL; 369 ooff = _dl_find_symbol(symn, _dl_objects, &this, 370 SYM_SEARCH_ALL|SYM_WARNNOTFOUND|SYM_PLT, 0, object->load_name); 371 if (this == NULL) { 372 _dl_printf("lazy binding failed!\n"); 373 *((int *)0) = 0; /* XXX */ 374 } 375 376 /* if GOT is protected, allow the write */ 377 if (object->got_size != 0) { 378 sigfillset(&nmask); 379 _dl_sigprocmask(SIG_BLOCK, &nmask, &omask); 380 _dl_mprotect((void*)object->got_start, object->got_size, 381 PROT_READ|PROT_WRITE); 382 } 383 384 _dl_reloc_plt(addr, ooff + this->st_value); 385 386 /* put the GOT back to RO */ 387 if (object->got_size != 0) { 388 _dl_mprotect((void*)object->got_start, object->got_size, 389 PROT_READ); 390 _dl_sigprocmask(SIG_SETMASK, &omask, NULL); 391 } 392 393 return((Elf_Addr)ooff + this->st_value); 394 } 395 396 void 397 _dl_md_reloc_got(elf_object_t *object, int lazy) 398 { 399 extern void _dl_bind_start(void); /* XXX */ 400 Elf_Addr *pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT]; 401 int i, num; 402 Elf_Rel *rel; 403 struct load_list *llist; 404 Elf_Addr ooff; 405 const Elf_Sym *this; 406 407 if (pltgot == NULL) 408 return; /* it is possible to have no PLT/GOT relocations */ 409 410 pltgot[1] = (Elf_Addr)object; 411 pltgot[2] = (Elf_Addr)&_dl_bind_start; 412 413 if (object->Dyn.info[DT_PLTREL] != DT_REL) 414 return; 415 416 object->got_addr = NULL; 417 object->got_size = 0; 418 this = NULL; 419 ooff = _dl_find_symbol("__got_start", object, &this, 420 SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, 0, NULL); 421 if (this != NULL) 422 object->got_addr = ooff + this->st_value; 423 424 this = NULL; 425 ooff = _dl_find_symbol("__got_end", object, &this, 426 SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, 0, NULL); 427 if (this != NULL) 428 object->got_size = ooff + this->st_value - object->got_addr; 429 430 if (object->got_addr == NULL) 431 object->got_start = NULL; 432 else { 433 object->got_start = ELF_TRUNC(object->got_addr, _dl_pagesz); 434 object->got_size += object->got_addr - object->got_start; 435 object->got_size = ELF_ROUND(object->got_size, _dl_pagesz); 436 } 437 438 if (!lazy) { 439 _dl_md_reloc(object, DT_JMPREL, DT_PLTRELSZ); 440 return; 441 } 442 443 rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]); 444 num = (object->Dyn.info[DT_PLTRELSZ]); 445 for (llist = object->load_list; llist != NULL; llist = llist->next) { 446 if (!(llist->prot & PROT_WRITE)) 447 _dl_mprotect(llist->start, llist->size, 448 llist->prot|PROT_WRITE); 449 } 450 for (i = 0; i < num/sizeof(Elf_Rel); i++, rel++) { 451 Elf_Addr *where; 452 where = (Elf_Addr *)(rel->r_offset + object->load_offs); 453 *where += object->load_offs; 454 } 455 for (llist = object->load_list; llist != NULL; llist = llist->next) { 456 if (!(llist->prot & PROT_WRITE)) 457 _dl_mprotect(llist->start, llist->size, 458 llist->prot); 459 } 460 461 /* PLT is already RO on i386, no point in mprotecting it, just GOT */ 462 if (object->got_size != 0) 463 _dl_mprotect((void*)object->got_start, object->got_size, 464 PROT_READ); 465 } 466