1 /*- 2 * Copyright (c) 1998-2000 Doug Rabson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_gdb.h" 31 #include "opt_mac.h" 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #ifdef GPROF 36 #include <sys/gmon.h> 37 #endif 38 #include <sys/kernel.h> 39 #include <sys/lock.h> 40 #include <sys/mac.h> 41 #include <sys/malloc.h> 42 #include <sys/mutex.h> 43 #include <sys/mount.h> 44 #include <sys/proc.h> 45 #include <sys/namei.h> 46 #include <sys/fcntl.h> 47 #include <sys/vnode.h> 48 #include <sys/linker.h> 49 50 #include <machine/elf.h> 51 52 #include <vm/vm.h> 53 #include <vm/vm_param.h> 54 #ifdef SPARSE_MAPPING 55 #include <vm/vm_object.h> 56 #include <vm/vm_kern.h> 57 #include <vm/vm_extern.h> 58 #endif 59 #include <vm/pmap.h> 60 #include <vm/vm_map.h> 61 62 #include <sys/link_elf.h> 63 64 #include "linker_if.h" 65 66 #define MAXSEGS 4 67 68 typedef struct elf_file { 69 struct linker_file lf; /* Common fields */ 70 int preloaded; /* Was file pre-loaded */ 71 caddr_t address; /* Relocation address */ 72 #ifdef SPARSE_MAPPING 73 vm_object_t object; /* VM object to hold file pages */ 74 #endif 75 Elf_Dyn* dynamic; /* Symbol table etc. */ 76 Elf_Hashelt nbuckets; /* DT_HASH info */ 77 Elf_Hashelt nchains; 78 const Elf_Hashelt* buckets; 79 const Elf_Hashelt* chains; 80 caddr_t hash; 81 caddr_t strtab; /* DT_STRTAB */ 82 int strsz; /* DT_STRSZ */ 83 const Elf_Sym* symtab; /* DT_SYMTAB */ 84 Elf_Addr* got; /* DT_PLTGOT */ 85 const Elf_Rel* pltrel; /* DT_JMPREL */ 86 int pltrelsize; /* DT_PLTRELSZ */ 87 const Elf_Rela* pltrela; /* DT_JMPREL */ 88 int pltrelasize; /* DT_PLTRELSZ */ 89 const Elf_Rel* rel; /* DT_REL */ 90 int relsize; /* DT_RELSZ */ 91 const Elf_Rela* rela; /* DT_RELA */ 92 int relasize; /* DT_RELASZ */ 93 caddr_t modptr; 94 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 95 long ddbsymcnt; /* Number of symbols */ 96 caddr_t ddbstrtab; /* String table */ 97 long ddbstrcnt; /* number of bytes in string table */ 98 caddr_t symbase; /* malloc'ed symbold base */ 99 caddr_t strbase; /* malloc'ed string base */ 100 #ifdef GDB 101 struct link_map gdb; /* hooks for gdb */ 102 #endif 103 } *elf_file_t; 104 105 static int link_elf_link_common_finish(linker_file_t); 106 static int link_elf_link_preload(linker_class_t cls, 107 const char*, linker_file_t*); 108 static int link_elf_link_preload_finish(linker_file_t); 109 static int link_elf_load_file(linker_class_t, const char*, linker_file_t*); 110 static int link_elf_lookup_symbol(linker_file_t, const char*, 111 c_linker_sym_t*); 112 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 113 static int link_elf_search_symbol(linker_file_t, caddr_t value, 114 c_linker_sym_t* sym, long* diffp); 115 116 static void link_elf_unload_file(linker_file_t); 117 static void link_elf_unload_preload(linker_file_t); 118 static int link_elf_lookup_set(linker_file_t, const char *, 119 void ***, void ***, int *); 120 static int link_elf_each_function_name(linker_file_t, 121 int (*)(const char *, void *), 122 void *); 123 static void link_elf_reloc_local(linker_file_t); 124 static Elf_Addr elf_lookup(linker_file_t lf, Elf_Size symidx, int deps); 125 126 static kobj_method_t link_elf_methods[] = { 127 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol), 128 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values), 129 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol), 130 KOBJMETHOD(linker_unload, link_elf_unload_file), 131 KOBJMETHOD(linker_load_file, link_elf_load_file), 132 KOBJMETHOD(linker_link_preload, link_elf_link_preload), 133 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish), 134 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set), 135 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name), 136 { 0, 0 } 137 }; 138 139 static struct linker_class link_elf_class = { 140 #if ELF_TARG_CLASS == ELFCLASS32 141 "elf32", 142 #else 143 "elf64", 144 #endif 145 link_elf_methods, sizeof(struct elf_file) 146 }; 147 148 static int parse_dynamic(elf_file_t ef); 149 static int relocate_file(elf_file_t ef); 150 static int link_elf_preload_parse_symbols(elf_file_t ef); 151 152 #ifdef GDB 153 static void r_debug_state(struct r_debug *dummy_one, 154 struct link_map *dummy_two); 155 156 /* 157 * A list of loaded modules for GDB to use for loading symbols. 158 */ 159 struct r_debug r_debug; 160 161 #define GDB_STATE(s) r_debug.r_state = s; r_debug_state(NULL, NULL); 162 163 /* 164 * Function for the debugger to set a breakpoint on to gain control. 165 */ 166 static void 167 r_debug_state(struct r_debug *dummy_one __unused, 168 struct link_map *dummy_two __unused) 169 { 170 } 171 172 static void 173 link_elf_add_gdb(struct link_map *l) 174 { 175 struct link_map *prev; 176 177 l->l_next = NULL; 178 179 if (r_debug.r_map == NULL) { 180 /* Add first. */ 181 l->l_prev = NULL; 182 r_debug.r_map = l; 183 } else { 184 /* Append to list. */ 185 for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next) 186 ; 187 l->l_prev = prev; 188 prev->l_next = l; 189 } 190 } 191 192 static void 193 link_elf_delete_gdb(struct link_map *l) 194 { 195 if (l->l_prev == NULL) { 196 /* Remove first. */ 197 if ((r_debug.r_map = l->l_next) != NULL) 198 l->l_next->l_prev = NULL; 199 } else { 200 /* Remove any but first. */ 201 if ((l->l_prev->l_next = l->l_next) != NULL) 202 l->l_next->l_prev = l->l_prev; 203 } 204 } 205 #endif /* GDB */ 206 207 #ifdef __ia64__ 208 Elf_Addr link_elf_get_gp(linker_file_t); 209 #endif 210 211 /* 212 * The kernel symbol table starts here. 213 */ 214 extern struct _dynamic _DYNAMIC; 215 216 static void 217 link_elf_error(const char *s) 218 { 219 printf("kldload: %s\n", s); 220 } 221 222 /* 223 * Actions performed after linking/loading both the preloaded kernel and any 224 * modules; whether preloaded or dynamicly loaded. 225 */ 226 static int 227 link_elf_link_common_finish(linker_file_t lf) 228 { 229 #ifdef GDB 230 elf_file_t ef = (elf_file_t)lf; 231 char *newfilename; 232 #endif 233 int error; 234 235 /* Notify MD code that a module is being loaded. */ 236 error = elf_cpu_load_file(lf); 237 if (error) 238 return (error); 239 240 #ifdef GDB 241 GDB_STATE(RT_ADD); 242 ef->gdb.l_addr = lf->address; 243 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK); 244 strcpy(newfilename, lf->filename); 245 ef->gdb.l_name = newfilename; 246 ef->gdb.l_ld = ef->dynamic; 247 link_elf_add_gdb(&ef->gdb); 248 GDB_STATE(RT_CONSISTENT); 249 #endif 250 251 return (0); 252 } 253 254 static void 255 link_elf_init(void* arg) 256 { 257 Elf_Dyn *dp; 258 caddr_t modptr, baseptr, sizeptr; 259 elf_file_t ef; 260 char *modname; 261 262 linker_add_class(&link_elf_class); 263 264 dp = (Elf_Dyn*) &_DYNAMIC; 265 modname = NULL; 266 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel"); 267 if (modptr == NULL) 268 modptr = preload_search_by_type("elf kernel"); 269 if (modptr) 270 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 271 if (modname == NULL) 272 modname = "kernel"; 273 linker_kernel_file = linker_make_file(modname, &link_elf_class); 274 if (linker_kernel_file == NULL) 275 panic("link_elf_init: Can't create linker structures for kernel"); 276 277 ef = (elf_file_t) linker_kernel_file; 278 ef->preloaded = 1; 279 ef->address = 0; 280 #ifdef SPARSE_MAPPING 281 ef->object = 0; 282 #endif 283 ef->dynamic = dp; 284 285 if (dp) 286 parse_dynamic(ef); 287 linker_kernel_file->address = (caddr_t) KERNBASE; 288 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 289 290 if (modptr) { 291 ef->modptr = modptr; 292 baseptr = preload_search_info(modptr, MODINFO_ADDR); 293 if (baseptr) 294 linker_kernel_file->address = *(caddr_t *)baseptr; 295 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 296 if (sizeptr) 297 linker_kernel_file->size = *(size_t *)sizeptr; 298 } 299 (void)link_elf_preload_parse_symbols(ef); 300 301 #ifdef GDB 302 r_debug.r_map = NULL; 303 r_debug.r_brk = r_debug_state; 304 r_debug.r_state = RT_CONSISTENT; 305 #endif 306 307 (void)link_elf_link_common_finish(linker_kernel_file); 308 } 309 310 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, 0); 311 312 static int 313 link_elf_preload_parse_symbols(elf_file_t ef) 314 { 315 caddr_t pointer; 316 caddr_t ssym, esym, base; 317 caddr_t strtab; 318 int strcnt; 319 Elf_Sym* symtab; 320 int symcnt; 321 322 if (ef->modptr == NULL) 323 return 0; 324 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 325 if (pointer == NULL) 326 return 0; 327 ssym = *(caddr_t *)pointer; 328 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 329 if (pointer == NULL) 330 return 0; 331 esym = *(caddr_t *)pointer; 332 333 base = ssym; 334 335 symcnt = *(long *)base; 336 base += sizeof(long); 337 symtab = (Elf_Sym *)base; 338 base += roundup(symcnt, sizeof(long)); 339 340 if (base > esym || base < ssym) { 341 printf("Symbols are corrupt!\n"); 342 return EINVAL; 343 } 344 345 strcnt = *(long *)base; 346 base += sizeof(long); 347 strtab = base; 348 base += roundup(strcnt, sizeof(long)); 349 350 if (base > esym || base < ssym) { 351 printf("Symbols are corrupt!\n"); 352 return EINVAL; 353 } 354 355 ef->ddbsymtab = symtab; 356 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 357 ef->ddbstrtab = strtab; 358 ef->ddbstrcnt = strcnt; 359 360 return 0; 361 } 362 363 static int 364 parse_dynamic(elf_file_t ef) 365 { 366 Elf_Dyn *dp; 367 int plttype = DT_REL; 368 369 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 370 switch (dp->d_tag) { 371 case DT_HASH: 372 { 373 /* From src/libexec/rtld-elf/rtld.c */ 374 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 375 (ef->address + dp->d_un.d_ptr); 376 ef->nbuckets = hashtab[0]; 377 ef->nchains = hashtab[1]; 378 ef->buckets = hashtab + 2; 379 ef->chains = ef->buckets + ef->nbuckets; 380 break; 381 } 382 case DT_STRTAB: 383 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 384 break; 385 case DT_STRSZ: 386 ef->strsz = dp->d_un.d_val; 387 break; 388 case DT_SYMTAB: 389 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 390 break; 391 case DT_SYMENT: 392 if (dp->d_un.d_val != sizeof(Elf_Sym)) 393 return ENOEXEC; 394 break; 395 case DT_PLTGOT: 396 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 397 break; 398 case DT_REL: 399 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 400 break; 401 case DT_RELSZ: 402 ef->relsize = dp->d_un.d_val; 403 break; 404 case DT_RELENT: 405 if (dp->d_un.d_val != sizeof(Elf_Rel)) 406 return ENOEXEC; 407 break; 408 case DT_JMPREL: 409 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 410 break; 411 case DT_PLTRELSZ: 412 ef->pltrelsize = dp->d_un.d_val; 413 break; 414 case DT_RELA: 415 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 416 break; 417 case DT_RELASZ: 418 ef->relasize = dp->d_un.d_val; 419 break; 420 case DT_RELAENT: 421 if (dp->d_un.d_val != sizeof(Elf_Rela)) 422 return ENOEXEC; 423 break; 424 case DT_PLTREL: 425 plttype = dp->d_un.d_val; 426 if (plttype != DT_REL && plttype != DT_RELA) 427 return ENOEXEC; 428 break; 429 #ifdef GDB 430 case DT_DEBUG: 431 dp->d_un.d_ptr = (Elf_Addr) &r_debug; 432 break; 433 #endif 434 } 435 } 436 437 if (plttype == DT_RELA) { 438 ef->pltrela = (const Elf_Rela *) ef->pltrel; 439 ef->pltrel = NULL; 440 ef->pltrelasize = ef->pltrelsize; 441 ef->pltrelsize = 0; 442 } 443 444 ef->ddbsymtab = ef->symtab; 445 ef->ddbsymcnt = ef->nchains; 446 ef->ddbstrtab = ef->strtab; 447 ef->ddbstrcnt = ef->strsz; 448 449 return 0; 450 } 451 452 static int 453 link_elf_link_preload(linker_class_t cls, 454 const char* filename, linker_file_t *result) 455 { 456 caddr_t modptr, baseptr, sizeptr, dynptr; 457 char *type; 458 elf_file_t ef; 459 linker_file_t lf; 460 int error; 461 vm_offset_t dp; 462 463 /* Look to see if we have the file preloaded */ 464 modptr = preload_search_by_name(filename); 465 if (modptr == NULL) 466 return ENOENT; 467 468 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 469 baseptr = preload_search_info(modptr, MODINFO_ADDR); 470 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 471 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 472 if (type == NULL || 473 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 && 474 strcmp(type, "elf module") != 0)) 475 return (EFTYPE); 476 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 477 return (EINVAL); 478 479 lf = linker_make_file(filename, &link_elf_class); 480 if (lf == NULL) { 481 return ENOMEM; 482 } 483 484 ef = (elf_file_t) lf; 485 ef->preloaded = 1; 486 ef->modptr = modptr; 487 ef->address = *(caddr_t *)baseptr; 488 #ifdef SPARSE_MAPPING 489 ef->object = 0; 490 #endif 491 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 492 ef->dynamic = (Elf_Dyn *)dp; 493 lf->address = ef->address; 494 lf->size = *(size_t *)sizeptr; 495 496 error = parse_dynamic(ef); 497 if (error) { 498 linker_file_unload(lf, LINKER_UNLOAD_FORCE); 499 return error; 500 } 501 link_elf_reloc_local(lf); 502 *result = lf; 503 return (0); 504 } 505 506 static int 507 link_elf_link_preload_finish(linker_file_t lf) 508 { 509 elf_file_t ef; 510 int error; 511 512 ef = (elf_file_t) lf; 513 #if 0 /* this will be more trouble than it's worth for now */ 514 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 515 if (dp->d_tag != DT_NEEDED) 516 continue; 517 modname = ef->strtab + dp->d_un.d_val; 518 error = linker_load_module(modname, lf); 519 if (error) 520 goto out; 521 } 522 #endif 523 error = relocate_file(ef); 524 if (error) 525 return error; 526 (void)link_elf_preload_parse_symbols(ef); 527 528 return (link_elf_link_common_finish(lf)); 529 } 530 531 static int 532 link_elf_load_file(linker_class_t cls, const char* filename, 533 linker_file_t* result) 534 { 535 struct nameidata nd; 536 struct thread* td = curthread; /* XXX */ 537 Elf_Ehdr *hdr; 538 caddr_t firstpage; 539 int nbytes, i; 540 Elf_Phdr *phdr; 541 Elf_Phdr *phlimit; 542 Elf_Phdr *segs[MAXSEGS]; 543 int nsegs; 544 Elf_Phdr *phdyn; 545 Elf_Phdr *phphdr; 546 caddr_t mapbase; 547 size_t mapsize; 548 Elf_Off base_offset; 549 Elf_Addr base_vaddr; 550 Elf_Addr base_vlimit; 551 int error = 0; 552 int resid, flags; 553 elf_file_t ef; 554 linker_file_t lf; 555 Elf_Shdr *shdr; 556 int symtabindex; 557 int symstrindex; 558 int symcnt; 559 int strcnt; 560 int vfslocked; 561 562 shdr = NULL; 563 lf = NULL; 564 565 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, filename, td); 566 flags = FREAD; 567 error = vn_open(&nd, &flags, 0, -1); 568 if (error) 569 return error; 570 vfslocked = NDHASGIANT(&nd); 571 NDFREE(&nd, NDF_ONLY_PNBUF); 572 #ifdef MAC 573 error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp); 574 if (error) { 575 firstpage = NULL; 576 goto out; 577 } 578 #endif 579 580 /* 581 * Read the elf header from the file. 582 */ 583 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK); 584 if (firstpage == NULL) { 585 error = ENOMEM; 586 goto out; 587 } 588 hdr = (Elf_Ehdr *)firstpage; 589 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0, 590 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 591 &resid, td); 592 nbytes = PAGE_SIZE - resid; 593 if (error) 594 goto out; 595 596 if (!IS_ELF(*hdr)) { 597 error = ENOEXEC; 598 goto out; 599 } 600 601 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 602 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 603 link_elf_error("Unsupported file layout"); 604 error = ENOEXEC; 605 goto out; 606 } 607 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 608 || hdr->e_version != EV_CURRENT) { 609 link_elf_error("Unsupported file version"); 610 error = ENOEXEC; 611 goto out; 612 } 613 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 614 link_elf_error("Unsupported file type"); 615 error = ENOEXEC; 616 goto out; 617 } 618 if (hdr->e_machine != ELF_TARG_MACH) { 619 link_elf_error("Unsupported machine"); 620 error = ENOEXEC; 621 goto out; 622 } 623 624 /* 625 * We rely on the program header being in the first page. This is 626 * not strictly required by the ABI specification, but it seems to 627 * always true in practice. And, it simplifies things considerably. 628 */ 629 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 630 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 631 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 632 link_elf_error("Unreadable program headers"); 633 634 /* 635 * Scan the program header entries, and save key information. 636 * 637 * We rely on there being exactly two load segments, text and data, 638 * in that order. 639 */ 640 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 641 phlimit = phdr + hdr->e_phnum; 642 nsegs = 0; 643 phdyn = NULL; 644 phphdr = NULL; 645 while (phdr < phlimit) { 646 switch (phdr->p_type) { 647 648 case PT_LOAD: 649 if (nsegs == MAXSEGS) { 650 link_elf_error("Too many sections"); 651 error = ENOEXEC; 652 goto out; 653 } 654 /* 655 * XXX: We just trust they come in right order ?? 656 */ 657 segs[nsegs] = phdr; 658 ++nsegs; 659 break; 660 661 case PT_PHDR: 662 phphdr = phdr; 663 break; 664 665 case PT_DYNAMIC: 666 phdyn = phdr; 667 break; 668 669 case PT_INTERP: 670 link_elf_error("Unsupported file type"); 671 error = ENOEXEC; 672 goto out; 673 } 674 675 ++phdr; 676 } 677 if (phdyn == NULL) { 678 link_elf_error("Object is not dynamically-linked"); 679 error = ENOEXEC; 680 goto out; 681 } 682 if (nsegs == 0) { 683 link_elf_error("No sections"); 684 error = ENOEXEC; 685 goto out; 686 } 687 688 /* 689 * Allocate the entire address space of the object, to stake out our 690 * contiguous region, and to establish the base address for relocation. 691 */ 692 base_offset = trunc_page(segs[0]->p_offset); 693 base_vaddr = trunc_page(segs[0]->p_vaddr); 694 base_vlimit = round_page(segs[nsegs - 1]->p_vaddr + 695 segs[nsegs - 1]->p_memsz); 696 mapsize = base_vlimit - base_vaddr; 697 698 lf = linker_make_file(filename, &link_elf_class); 699 if (!lf) { 700 error = ENOMEM; 701 goto out; 702 } 703 704 ef = (elf_file_t) lf; 705 #ifdef SPARSE_MAPPING 706 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 707 if (ef->object == NULL) { 708 error = ENOMEM; 709 goto out; 710 } 711 ef->address = (caddr_t) vm_map_min(kernel_map); 712 error = vm_map_find(kernel_map, ef->object, 0, 713 (vm_offset_t *) &ef->address, 714 mapsize, 1, 715 VM_PROT_ALL, VM_PROT_ALL, 0); 716 if (error) { 717 vm_object_deallocate(ef->object); 718 ef->object = 0; 719 goto out; 720 } 721 #else 722 ef->address = malloc(mapsize, M_LINKER, M_WAITOK); 723 if (!ef->address) { 724 error = ENOMEM; 725 goto out; 726 } 727 #endif 728 mapbase = ef->address; 729 730 /* 731 * Read the text and data sections and zero the bss. 732 */ 733 for (i = 0; i < nsegs; i++) { 734 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 735 error = vn_rdwr(UIO_READ, nd.ni_vp, 736 segbase, segs[i]->p_filesz, segs[i]->p_offset, 737 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 738 &resid, td); 739 if (error) { 740 goto out; 741 } 742 bzero(segbase + segs[i]->p_filesz, 743 segs[i]->p_memsz - segs[i]->p_filesz); 744 745 #ifdef SPARSE_MAPPING 746 /* 747 * Wire down the pages 748 */ 749 error = vm_map_wire(kernel_map, 750 (vm_offset_t) segbase, 751 (vm_offset_t) segbase + segs[i]->p_memsz, 752 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES); 753 if (error != KERN_SUCCESS) { 754 error = ENOMEM; 755 goto out; 756 } 757 #endif 758 } 759 760 #ifdef GPROF 761 /* Update profiling information with the new text segment. */ 762 mtx_lock(&Giant); 763 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr + 764 segs[0]->p_memsz)); 765 mtx_unlock(&Giant); 766 #endif 767 768 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 769 770 lf->address = ef->address; 771 lf->size = mapsize; 772 773 error = parse_dynamic(ef); 774 if (error) 775 goto out; 776 link_elf_reloc_local(lf); 777 778 error = linker_load_dependencies(lf); 779 if (error) 780 goto out; 781 #if 0 /* this will be more trouble than it's worth for now */ 782 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 783 if (dp->d_tag != DT_NEEDED) 784 continue; 785 modname = ef->strtab + dp->d_un.d_val; 786 error = linker_load_module(modname, lf); 787 if (error) 788 goto out; 789 } 790 #endif 791 error = relocate_file(ef); 792 if (error) 793 goto out; 794 795 /* Try and load the symbol table if it's present. (you can strip it!) */ 796 nbytes = hdr->e_shnum * hdr->e_shentsize; 797 if (nbytes == 0 || hdr->e_shoff == 0) 798 goto nosyms; 799 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 800 if (shdr == NULL) { 801 error = ENOMEM; 802 goto out; 803 } 804 error = vn_rdwr(UIO_READ, nd.ni_vp, 805 (caddr_t)shdr, nbytes, hdr->e_shoff, 806 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 807 &resid, td); 808 if (error) 809 goto out; 810 symtabindex = -1; 811 symstrindex = -1; 812 for (i = 0; i < hdr->e_shnum; i++) { 813 if (shdr[i].sh_type == SHT_SYMTAB) { 814 symtabindex = i; 815 symstrindex = shdr[i].sh_link; 816 } 817 } 818 if (symtabindex < 0 || symstrindex < 0) 819 goto nosyms; 820 821 symcnt = shdr[symtabindex].sh_size; 822 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK); 823 strcnt = shdr[symstrindex].sh_size; 824 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK); 825 826 if (ef->symbase == NULL || ef->strbase == NULL) { 827 error = ENOMEM; 828 goto out; 829 } 830 error = vn_rdwr(UIO_READ, nd.ni_vp, 831 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 832 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 833 &resid, td); 834 if (error) 835 goto out; 836 error = vn_rdwr(UIO_READ, nd.ni_vp, 837 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 838 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 839 &resid, td); 840 if (error) 841 goto out; 842 843 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 844 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 845 ef->ddbstrcnt = strcnt; 846 ef->ddbstrtab = ef->strbase; 847 848 error = link_elf_link_common_finish(lf); 849 if (error) 850 goto out; 851 852 nosyms: 853 854 *result = lf; 855 856 out: 857 if (error && lf) 858 linker_file_unload(lf, LINKER_UNLOAD_FORCE); 859 if (shdr) 860 free(shdr, M_LINKER); 861 if (firstpage) 862 free(firstpage, M_LINKER); 863 VOP_UNLOCK(nd.ni_vp, 0, td); 864 vn_close(nd.ni_vp, FREAD, td->td_ucred, td); 865 VFS_UNLOCK_GIANT(vfslocked); 866 867 return error; 868 } 869 870 static void 871 link_elf_unload_file(linker_file_t file) 872 { 873 elf_file_t ef = (elf_file_t) file; 874 875 #ifdef GDB 876 if (ef->gdb.l_ld) { 877 GDB_STATE(RT_DELETE); 878 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER); 879 link_elf_delete_gdb(&ef->gdb); 880 GDB_STATE(RT_CONSISTENT); 881 } 882 #endif 883 884 /* Notify MD code that a module is being unloaded. */ 885 elf_cpu_unload_file(file); 886 887 if (ef->preloaded) { 888 link_elf_unload_preload(file); 889 return; 890 } 891 892 #ifdef SPARSE_MAPPING 893 if (ef->object) { 894 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 895 (vm_offset_t) ef->address 896 + (ef->object->size << PAGE_SHIFT)); 897 } 898 #else 899 if (ef->address) 900 free(ef->address, M_LINKER); 901 #endif 902 if (ef->symbase) 903 free(ef->symbase, M_LINKER); 904 if (ef->strbase) 905 free(ef->strbase, M_LINKER); 906 } 907 908 static void 909 link_elf_unload_preload(linker_file_t file) 910 { 911 if (file->filename) 912 preload_delete_name(file->filename); 913 } 914 915 static const char * 916 symbol_name(elf_file_t ef, Elf_Size r_info) 917 { 918 const Elf_Sym *ref; 919 920 if (ELF_R_SYM(r_info)) { 921 ref = ef->symtab + ELF_R_SYM(r_info); 922 return ef->strtab + ref->st_name; 923 } else 924 return NULL; 925 } 926 927 static int 928 relocate_file(elf_file_t ef) 929 { 930 const Elf_Rel *rellim; 931 const Elf_Rel *rel; 932 const Elf_Rela *relalim; 933 const Elf_Rela *rela; 934 const char *symname; 935 936 /* Perform relocations without addend if there are any: */ 937 rel = ef->rel; 938 if (rel) { 939 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 940 while (rel < rellim) { 941 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 942 elf_lookup)) { 943 symname = symbol_name(ef, rel->r_info); 944 printf("link_elf: symbol %s undefined\n", symname); 945 return ENOENT; 946 } 947 rel++; 948 } 949 } 950 951 /* Perform relocations with addend if there are any: */ 952 rela = ef->rela; 953 if (rela) { 954 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 955 while (rela < relalim) { 956 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 957 elf_lookup)) { 958 symname = symbol_name(ef, rela->r_info); 959 printf("link_elf: symbol %s undefined\n", symname); 960 return ENOENT; 961 } 962 rela++; 963 } 964 } 965 966 /* Perform PLT relocations without addend if there are any: */ 967 rel = ef->pltrel; 968 if (rel) { 969 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 970 while (rel < rellim) { 971 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 972 elf_lookup)) { 973 symname = symbol_name(ef, rel->r_info); 974 printf("link_elf: symbol %s undefined\n", symname); 975 return ENOENT; 976 } 977 rel++; 978 } 979 } 980 981 /* Perform relocations with addend if there are any: */ 982 rela = ef->pltrela; 983 if (rela) { 984 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 985 while (rela < relalim) { 986 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 987 elf_lookup)) { 988 symname = symbol_name(ef, rela->r_info); 989 printf("link_elf: symbol %s undefined\n", symname); 990 return ENOENT; 991 } 992 rela++; 993 } 994 } 995 996 return 0; 997 } 998 999 /* 1000 * Hash function for symbol table lookup. Don't even think about changing 1001 * this. It is specified by the System V ABI. 1002 */ 1003 static unsigned long 1004 elf_hash(const char *name) 1005 { 1006 const unsigned char *p = (const unsigned char *) name; 1007 unsigned long h = 0; 1008 unsigned long g; 1009 1010 while (*p != '\0') { 1011 h = (h << 4) + *p++; 1012 if ((g = h & 0xf0000000) != 0) 1013 h ^= g >> 24; 1014 h &= ~g; 1015 } 1016 return h; 1017 } 1018 1019 static int 1020 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 1021 { 1022 elf_file_t ef = (elf_file_t) lf; 1023 unsigned long symnum; 1024 const Elf_Sym* symp; 1025 const char *strp; 1026 unsigned long hash; 1027 int i; 1028 1029 /* If we don't have a hash, bail. */ 1030 if (ef->buckets == NULL || ef->nbuckets == 0) { 1031 printf("link_elf_lookup_symbol: missing symbol hash table\n"); 1032 return ENOENT; 1033 } 1034 1035 /* First, search hashed global symbols */ 1036 hash = elf_hash(name); 1037 symnum = ef->buckets[hash % ef->nbuckets]; 1038 1039 while (symnum != STN_UNDEF) { 1040 if (symnum >= ef->nchains) { 1041 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 1042 return ENOENT; 1043 } 1044 1045 symp = ef->symtab + symnum; 1046 if (symp->st_name == 0) { 1047 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 1048 return ENOENT; 1049 } 1050 1051 strp = ef->strtab + symp->st_name; 1052 1053 if (strcmp(name, strp) == 0) { 1054 if (symp->st_shndx != SHN_UNDEF || 1055 (symp->st_value != 0 && 1056 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 1057 *sym = (c_linker_sym_t) symp; 1058 return 0; 1059 } else 1060 return ENOENT; 1061 } 1062 1063 symnum = ef->chains[symnum]; 1064 } 1065 1066 /* If we have not found it, look at the full table (if loaded) */ 1067 if (ef->symtab == ef->ddbsymtab) 1068 return ENOENT; 1069 1070 /* Exhaustive search */ 1071 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 1072 strp = ef->ddbstrtab + symp->st_name; 1073 if (strcmp(name, strp) == 0) { 1074 if (symp->st_shndx != SHN_UNDEF || 1075 (symp->st_value != 0 && 1076 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 1077 *sym = (c_linker_sym_t) symp; 1078 return 0; 1079 } else 1080 return ENOENT; 1081 } 1082 } 1083 1084 return ENOENT; 1085 } 1086 1087 static int 1088 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 1089 { 1090 elf_file_t ef = (elf_file_t) lf; 1091 const Elf_Sym* es = (const Elf_Sym*) sym; 1092 1093 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) { 1094 symval->name = ef->strtab + es->st_name; 1095 symval->value = (caddr_t) ef->address + es->st_value; 1096 symval->size = es->st_size; 1097 return 0; 1098 } 1099 if (ef->symtab == ef->ddbsymtab) 1100 return ENOENT; 1101 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) { 1102 symval->name = ef->ddbstrtab + es->st_name; 1103 symval->value = (caddr_t) ef->address + es->st_value; 1104 symval->size = es->st_size; 1105 return 0; 1106 } 1107 return ENOENT; 1108 } 1109 1110 static int 1111 link_elf_search_symbol(linker_file_t lf, caddr_t value, 1112 c_linker_sym_t* sym, long* diffp) 1113 { 1114 elf_file_t ef = (elf_file_t) lf; 1115 u_long off = (uintptr_t) (void *) value; 1116 u_long diff = off; 1117 u_long st_value; 1118 const Elf_Sym* es; 1119 const Elf_Sym* best = 0; 1120 int i; 1121 1122 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 1123 if (es->st_name == 0) 1124 continue; 1125 st_value = es->st_value + (uintptr_t) (void *) ef->address; 1126 if (off >= st_value) { 1127 if (off - st_value < diff) { 1128 diff = off - st_value; 1129 best = es; 1130 if (diff == 0) 1131 break; 1132 } else if (off - st_value == diff) { 1133 best = es; 1134 } 1135 } 1136 } 1137 if (best == 0) 1138 *diffp = off; 1139 else 1140 *diffp = diff; 1141 *sym = (c_linker_sym_t) best; 1142 1143 return 0; 1144 } 1145 1146 /* 1147 * Look up a linker set on an ELF system. 1148 */ 1149 static int 1150 link_elf_lookup_set(linker_file_t lf, const char *name, 1151 void ***startp, void ***stopp, int *countp) 1152 { 1153 c_linker_sym_t sym; 1154 linker_symval_t symval; 1155 char *setsym; 1156 void **start, **stop; 1157 int len, error = 0, count; 1158 1159 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1160 setsym = malloc(len, M_LINKER, M_WAITOK); 1161 if (setsym == NULL) 1162 return ENOMEM; 1163 1164 /* get address of first entry */ 1165 snprintf(setsym, len, "%s%s", "__start_set_", name); 1166 error = link_elf_lookup_symbol(lf, setsym, &sym); 1167 if (error) 1168 goto out; 1169 link_elf_symbol_values(lf, sym, &symval); 1170 if (symval.value == 0) { 1171 error = ESRCH; 1172 goto out; 1173 } 1174 start = (void **)symval.value; 1175 1176 /* get address of last entry */ 1177 snprintf(setsym, len, "%s%s", "__stop_set_", name); 1178 error = link_elf_lookup_symbol(lf, setsym, &sym); 1179 if (error) 1180 goto out; 1181 link_elf_symbol_values(lf, sym, &symval); 1182 if (symval.value == 0) { 1183 error = ESRCH; 1184 goto out; 1185 } 1186 stop = (void **)symval.value; 1187 1188 /* and the number of entries */ 1189 count = stop - start; 1190 1191 /* and copy out */ 1192 if (startp) 1193 *startp = start; 1194 if (stopp) 1195 *stopp = stop; 1196 if (countp) 1197 *countp = count; 1198 1199 out: 1200 free(setsym, M_LINKER); 1201 return error; 1202 } 1203 1204 static int 1205 link_elf_each_function_name(linker_file_t file, 1206 int (*callback)(const char *, void *), void *opaque) { 1207 elf_file_t ef = (elf_file_t)file; 1208 const Elf_Sym* symp; 1209 int i, error; 1210 1211 /* Exhaustive search */ 1212 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 1213 if (symp->st_value != 0 && 1214 ELF_ST_TYPE(symp->st_info) == STT_FUNC) { 1215 error = callback(ef->ddbstrtab + symp->st_name, opaque); 1216 if (error) 1217 return (error); 1218 } 1219 } 1220 return (0); 1221 } 1222 1223 #ifdef __ia64__ 1224 /* 1225 * Each KLD has its own GP. The GP value for each load module is given by 1226 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but 1227 * don't have direct access to the ELF file structure. The link_elf_get_gp() 1228 * function returns the GP given a pointer to a generic linker file struct. 1229 */ 1230 Elf_Addr 1231 link_elf_get_gp(linker_file_t lf) 1232 { 1233 elf_file_t ef = (elf_file_t)lf; 1234 return (Elf_Addr)ef->got; 1235 } 1236 #endif 1237 1238 const Elf_Sym * 1239 elf_get_sym(linker_file_t lf, Elf_Size symidx) 1240 { 1241 elf_file_t ef = (elf_file_t)lf; 1242 1243 if (symidx >= ef->nchains) 1244 return (NULL); 1245 return (ef->symtab + symidx); 1246 } 1247 1248 const char * 1249 elf_get_symname(linker_file_t lf, Elf_Size symidx) 1250 { 1251 elf_file_t ef = (elf_file_t)lf; 1252 const Elf_Sym *sym; 1253 1254 if (symidx >= ef->nchains) 1255 return (NULL); 1256 sym = ef->symtab + symidx; 1257 return (ef->strtab + sym->st_name); 1258 } 1259 1260 /* 1261 * Symbol lookup function that can be used when the symbol index is known (ie 1262 * in relocations). It uses the symbol index instead of doing a fully fledged 1263 * hash table based lookup when such is valid. For example for local symbols. 1264 * This is not only more efficient, it's also more correct. It's not always 1265 * the case that the symbol can be found through the hash table. 1266 */ 1267 static Elf_Addr 1268 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps) 1269 { 1270 elf_file_t ef = (elf_file_t)lf; 1271 const Elf_Sym *sym; 1272 const char *symbol; 1273 1274 /* Don't even try to lookup the symbol if the index is bogus. */ 1275 if (symidx >= ef->nchains) 1276 return (0); 1277 1278 sym = ef->symtab + symidx; 1279 1280 /* 1281 * Don't do a full lookup when the symbol is local. It may even 1282 * fail because it may not be found through the hash table. 1283 */ 1284 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1285 /* Force lookup failure when we have an insanity. */ 1286 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1287 return (0); 1288 return ((Elf_Addr)ef->address + sym->st_value); 1289 } 1290 1291 /* 1292 * XXX we can avoid doing a hash table based lookup for global 1293 * symbols as well. This however is not always valid, so we'll 1294 * just do it the hard way for now. Performance tweaks can 1295 * always be added. 1296 */ 1297 1298 symbol = ef->strtab + sym->st_name; 1299 1300 /* Force a lookup failure if the symbol name is bogus. */ 1301 if (*symbol == 0) 1302 return (0); 1303 1304 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps)); 1305 } 1306 1307 static void 1308 link_elf_reloc_local(linker_file_t lf) 1309 { 1310 const Elf_Rel *rellim; 1311 const Elf_Rel *rel; 1312 const Elf_Rela *relalim; 1313 const Elf_Rela *rela; 1314 elf_file_t ef = (elf_file_t)lf; 1315 1316 /* Perform relocations without addend if there are any: */ 1317 if ((rel = ef->rel) != NULL) { 1318 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1319 while (rel < rellim) { 1320 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1321 elf_lookup); 1322 rel++; 1323 } 1324 } 1325 1326 /* Perform relocations with addend if there are any: */ 1327 if ((rela = ef->rela) != NULL) { 1328 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1329 while (rela < relalim) { 1330 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1331 elf_lookup); 1332 rela++; 1333 } 1334 } 1335 } 1336