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/malloc.h> 41 #include <sys/mutex.h> 42 #include <sys/mount.h> 43 #include <sys/proc.h> 44 #include <sys/namei.h> 45 #include <sys/fcntl.h> 46 #include <sys/vnode.h> 47 #include <sys/linker.h> 48 49 #include <machine/elf.h> 50 51 #include <security/mac/mac_framework.h> 52 53 #include <vm/vm.h> 54 #include <vm/vm_param.h> 55 #ifdef SPARSE_MAPPING 56 #include <vm/vm_object.h> 57 #include <vm/vm_kern.h> 58 #include <vm/vm_extern.h> 59 #endif 60 #include <vm/pmap.h> 61 #include <vm/vm_map.h> 62 63 #include <sys/link_elf.h> 64 65 #include "linker_if.h" 66 67 #define MAXSEGS 4 68 69 typedef struct elf_file { 70 struct linker_file lf; /* Common fields */ 71 int preloaded; /* Was file pre-loaded */ 72 caddr_t address; /* Relocation address */ 73 #ifdef SPARSE_MAPPING 74 vm_object_t object; /* VM object to hold file pages */ 75 #endif 76 Elf_Dyn* dynamic; /* Symbol table etc. */ 77 Elf_Hashelt nbuckets; /* DT_HASH info */ 78 Elf_Hashelt nchains; 79 const Elf_Hashelt* buckets; 80 const Elf_Hashelt* chains; 81 caddr_t hash; 82 caddr_t strtab; /* DT_STRTAB */ 83 int strsz; /* DT_STRSZ */ 84 const Elf_Sym* symtab; /* DT_SYMTAB */ 85 Elf_Addr* got; /* DT_PLTGOT */ 86 const Elf_Rel* pltrel; /* DT_JMPREL */ 87 int pltrelsize; /* DT_PLTRELSZ */ 88 const Elf_Rela* pltrela; /* DT_JMPREL */ 89 int pltrelasize; /* DT_PLTRELSZ */ 90 const Elf_Rel* rel; /* DT_REL */ 91 int relsize; /* DT_RELSZ */ 92 const Elf_Rela* rela; /* DT_RELA */ 93 int relasize; /* DT_RELASZ */ 94 caddr_t modptr; 95 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 96 long ddbsymcnt; /* Number of symbols */ 97 caddr_t ddbstrtab; /* String table */ 98 long ddbstrcnt; /* number of bytes in string table */ 99 caddr_t symbase; /* malloc'ed symbold base */ 100 caddr_t strbase; /* malloc'ed string base */ 101 #ifdef GDB 102 struct link_map gdb; /* hooks for gdb */ 103 #endif 104 } *elf_file_t; 105 106 static int link_elf_link_common_finish(linker_file_t); 107 static int link_elf_link_preload(linker_class_t cls, 108 const char*, linker_file_t*); 109 static int link_elf_link_preload_finish(linker_file_t); 110 static int link_elf_load_file(linker_class_t, const char*, linker_file_t*); 111 static int link_elf_lookup_symbol(linker_file_t, const char*, 112 c_linker_sym_t*); 113 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 114 static int link_elf_search_symbol(linker_file_t, caddr_t value, 115 c_linker_sym_t* sym, long* diffp); 116 117 static void link_elf_unload_file(linker_file_t); 118 static void link_elf_unload_preload(linker_file_t); 119 static int link_elf_lookup_set(linker_file_t, const char *, 120 void ***, void ***, int *); 121 static int link_elf_each_function_name(linker_file_t, 122 int (*)(const char *, void *), 123 void *); 124 static void link_elf_reloc_local(linker_file_t); 125 static Elf_Addr elf_lookup(linker_file_t lf, Elf_Size symidx, int deps); 126 127 static kobj_method_t link_elf_methods[] = { 128 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol), 129 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values), 130 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol), 131 KOBJMETHOD(linker_unload, link_elf_unload_file), 132 KOBJMETHOD(linker_load_file, link_elf_load_file), 133 KOBJMETHOD(linker_link_preload, link_elf_link_preload), 134 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish), 135 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set), 136 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name), 137 { 0, 0 } 138 }; 139 140 static struct linker_class link_elf_class = { 141 #if ELF_TARG_CLASS == ELFCLASS32 142 "elf32", 143 #else 144 "elf64", 145 #endif 146 link_elf_methods, sizeof(struct elf_file) 147 }; 148 149 static int parse_dynamic(elf_file_t ef); 150 static int relocate_file(elf_file_t ef); 151 static int link_elf_preload_parse_symbols(elf_file_t ef); 152 153 #ifdef GDB 154 static void r_debug_state(struct r_debug *dummy_one, 155 struct link_map *dummy_two); 156 157 /* 158 * A list of loaded modules for GDB to use for loading symbols. 159 */ 160 struct r_debug r_debug; 161 162 #define GDB_STATE(s) r_debug.r_state = s; r_debug_state(NULL, NULL); 163 164 /* 165 * Function for the debugger to set a breakpoint on to gain control. 166 */ 167 static void 168 r_debug_state(struct r_debug *dummy_one __unused, 169 struct link_map *dummy_two __unused) 170 { 171 } 172 173 static void 174 link_elf_add_gdb(struct link_map *l) 175 { 176 struct link_map *prev; 177 178 l->l_next = NULL; 179 180 if (r_debug.r_map == NULL) { 181 /* Add first. */ 182 l->l_prev = NULL; 183 r_debug.r_map = l; 184 } else { 185 /* Append to list. */ 186 for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next) 187 ; 188 l->l_prev = prev; 189 prev->l_next = l; 190 } 191 } 192 193 static void 194 link_elf_delete_gdb(struct link_map *l) 195 { 196 if (l->l_prev == NULL) { 197 /* Remove first. */ 198 if ((r_debug.r_map = l->l_next) != NULL) 199 l->l_next->l_prev = NULL; 200 } else { 201 /* Remove any but first. */ 202 if ((l->l_prev->l_next = l->l_next) != NULL) 203 l->l_next->l_prev = l->l_prev; 204 } 205 } 206 #endif /* GDB */ 207 208 #ifdef __ia64__ 209 Elf_Addr link_elf_get_gp(linker_file_t); 210 #endif 211 212 /* 213 * The kernel symbol table starts here. 214 */ 215 extern struct _dynamic _DYNAMIC; 216 217 static void 218 link_elf_error(const char *s) 219 { 220 printf("kldload: %s\n", s); 221 } 222 223 /* 224 * Actions performed after linking/loading both the preloaded kernel and any 225 * modules; whether preloaded or dynamicly loaded. 226 */ 227 static int 228 link_elf_link_common_finish(linker_file_t lf) 229 { 230 #ifdef GDB 231 elf_file_t ef = (elf_file_t)lf; 232 char *newfilename; 233 #endif 234 int error; 235 236 /* Notify MD code that a module is being loaded. */ 237 error = elf_cpu_load_file(lf); 238 if (error) 239 return (error); 240 241 #ifdef GDB 242 GDB_STATE(RT_ADD); 243 ef->gdb.l_addr = lf->address; 244 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK); 245 strcpy(newfilename, lf->filename); 246 ef->gdb.l_name = newfilename; 247 ef->gdb.l_ld = ef->dynamic; 248 link_elf_add_gdb(&ef->gdb); 249 GDB_STATE(RT_CONSISTENT); 250 #endif 251 252 return (0); 253 } 254 255 static void 256 link_elf_init(void* arg) 257 { 258 Elf_Dyn *dp; 259 caddr_t modptr, baseptr, sizeptr; 260 elf_file_t ef; 261 char *modname; 262 263 linker_add_class(&link_elf_class); 264 265 dp = (Elf_Dyn*) &_DYNAMIC; 266 modname = NULL; 267 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel"); 268 if (modptr == NULL) 269 modptr = preload_search_by_type("elf kernel"); 270 if (modptr) 271 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 272 if (modname == NULL) 273 modname = "kernel"; 274 linker_kernel_file = linker_make_file(modname, &link_elf_class); 275 if (linker_kernel_file == NULL) 276 panic("link_elf_init: Can't create linker structures for kernel"); 277 278 ef = (elf_file_t) linker_kernel_file; 279 ef->preloaded = 1; 280 ef->address = 0; 281 #ifdef SPARSE_MAPPING 282 ef->object = 0; 283 #endif 284 ef->dynamic = dp; 285 286 if (dp) 287 parse_dynamic(ef); 288 linker_kernel_file->address = (caddr_t) KERNBASE; 289 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 290 291 if (modptr) { 292 ef->modptr = modptr; 293 baseptr = preload_search_info(modptr, MODINFO_ADDR); 294 if (baseptr) 295 linker_kernel_file->address = *(caddr_t *)baseptr; 296 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 297 if (sizeptr) 298 linker_kernel_file->size = *(size_t *)sizeptr; 299 } 300 (void)link_elf_preload_parse_symbols(ef); 301 302 #ifdef GDB 303 r_debug.r_map = NULL; 304 r_debug.r_brk = r_debug_state; 305 r_debug.r_state = RT_CONSISTENT; 306 #endif 307 308 (void)link_elf_link_common_finish(linker_kernel_file); 309 } 310 311 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, 0); 312 313 static int 314 link_elf_preload_parse_symbols(elf_file_t ef) 315 { 316 caddr_t pointer; 317 caddr_t ssym, esym, base; 318 caddr_t strtab; 319 int strcnt; 320 Elf_Sym* symtab; 321 int symcnt; 322 323 if (ef->modptr == NULL) 324 return 0; 325 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 326 if (pointer == NULL) 327 return 0; 328 ssym = *(caddr_t *)pointer; 329 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 330 if (pointer == NULL) 331 return 0; 332 esym = *(caddr_t *)pointer; 333 334 base = ssym; 335 336 symcnt = *(long *)base; 337 base += sizeof(long); 338 symtab = (Elf_Sym *)base; 339 base += roundup(symcnt, sizeof(long)); 340 341 if (base > esym || base < ssym) { 342 printf("Symbols are corrupt!\n"); 343 return EINVAL; 344 } 345 346 strcnt = *(long *)base; 347 base += sizeof(long); 348 strtab = base; 349 base += roundup(strcnt, sizeof(long)); 350 351 if (base > esym || base < ssym) { 352 printf("Symbols are corrupt!\n"); 353 return EINVAL; 354 } 355 356 ef->ddbsymtab = symtab; 357 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 358 ef->ddbstrtab = strtab; 359 ef->ddbstrcnt = strcnt; 360 361 return 0; 362 } 363 364 static int 365 parse_dynamic(elf_file_t ef) 366 { 367 Elf_Dyn *dp; 368 int plttype = DT_REL; 369 370 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 371 switch (dp->d_tag) { 372 case DT_HASH: 373 { 374 /* From src/libexec/rtld-elf/rtld.c */ 375 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 376 (ef->address + dp->d_un.d_ptr); 377 ef->nbuckets = hashtab[0]; 378 ef->nchains = hashtab[1]; 379 ef->buckets = hashtab + 2; 380 ef->chains = ef->buckets + ef->nbuckets; 381 break; 382 } 383 case DT_STRTAB: 384 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 385 break; 386 case DT_STRSZ: 387 ef->strsz = dp->d_un.d_val; 388 break; 389 case DT_SYMTAB: 390 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 391 break; 392 case DT_SYMENT: 393 if (dp->d_un.d_val != sizeof(Elf_Sym)) 394 return ENOEXEC; 395 break; 396 case DT_PLTGOT: 397 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 398 break; 399 case DT_REL: 400 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 401 break; 402 case DT_RELSZ: 403 ef->relsize = dp->d_un.d_val; 404 break; 405 case DT_RELENT: 406 if (dp->d_un.d_val != sizeof(Elf_Rel)) 407 return ENOEXEC; 408 break; 409 case DT_JMPREL: 410 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 411 break; 412 case DT_PLTRELSZ: 413 ef->pltrelsize = dp->d_un.d_val; 414 break; 415 case DT_RELA: 416 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 417 break; 418 case DT_RELASZ: 419 ef->relasize = dp->d_un.d_val; 420 break; 421 case DT_RELAENT: 422 if (dp->d_un.d_val != sizeof(Elf_Rela)) 423 return ENOEXEC; 424 break; 425 case DT_PLTREL: 426 plttype = dp->d_un.d_val; 427 if (plttype != DT_REL && plttype != DT_RELA) 428 return ENOEXEC; 429 break; 430 #ifdef GDB 431 case DT_DEBUG: 432 dp->d_un.d_ptr = (Elf_Addr) &r_debug; 433 break; 434 #endif 435 } 436 } 437 438 if (plttype == DT_RELA) { 439 ef->pltrela = (const Elf_Rela *) ef->pltrel; 440 ef->pltrel = NULL; 441 ef->pltrelasize = ef->pltrelsize; 442 ef->pltrelsize = 0; 443 } 444 445 ef->ddbsymtab = ef->symtab; 446 ef->ddbsymcnt = ef->nchains; 447 ef->ddbstrtab = ef->strtab; 448 ef->ddbstrcnt = ef->strsz; 449 450 return 0; 451 } 452 453 static int 454 link_elf_link_preload(linker_class_t cls, 455 const char* filename, linker_file_t *result) 456 { 457 caddr_t modptr, baseptr, sizeptr, dynptr; 458 char *type; 459 elf_file_t ef; 460 linker_file_t lf; 461 int error; 462 vm_offset_t dp; 463 464 /* Look to see if we have the file preloaded */ 465 modptr = preload_search_by_name(filename); 466 if (modptr == NULL) 467 return ENOENT; 468 469 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 470 baseptr = preload_search_info(modptr, MODINFO_ADDR); 471 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 472 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 473 if (type == NULL || 474 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 && 475 strcmp(type, "elf module") != 0)) 476 return (EFTYPE); 477 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 478 return (EINVAL); 479 480 lf = linker_make_file(filename, &link_elf_class); 481 if (lf == NULL) { 482 return ENOMEM; 483 } 484 485 ef = (elf_file_t) lf; 486 ef->preloaded = 1; 487 ef->modptr = modptr; 488 ef->address = *(caddr_t *)baseptr; 489 #ifdef SPARSE_MAPPING 490 ef->object = 0; 491 #endif 492 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 493 ef->dynamic = (Elf_Dyn *)dp; 494 lf->address = ef->address; 495 lf->size = *(size_t *)sizeptr; 496 497 error = parse_dynamic(ef); 498 if (error) { 499 linker_file_unload(lf, LINKER_UNLOAD_FORCE); 500 return error; 501 } 502 link_elf_reloc_local(lf); 503 *result = lf; 504 return (0); 505 } 506 507 static int 508 link_elf_link_preload_finish(linker_file_t lf) 509 { 510 elf_file_t ef; 511 int error; 512 513 ef = (elf_file_t) lf; 514 #if 0 /* this will be more trouble than it's worth for now */ 515 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 516 if (dp->d_tag != DT_NEEDED) 517 continue; 518 modname = ef->strtab + dp->d_un.d_val; 519 error = linker_load_module(modname, lf); 520 if (error) 521 goto out; 522 } 523 #endif 524 error = relocate_file(ef); 525 if (error) 526 return error; 527 (void)link_elf_preload_parse_symbols(ef); 528 529 return (link_elf_link_common_finish(lf)); 530 } 531 532 static int 533 link_elf_load_file(linker_class_t cls, const char* filename, 534 linker_file_t* result) 535 { 536 struct nameidata nd; 537 struct thread* td = curthread; /* XXX */ 538 Elf_Ehdr *hdr; 539 caddr_t firstpage; 540 int nbytes, i; 541 Elf_Phdr *phdr; 542 Elf_Phdr *phlimit; 543 Elf_Phdr *segs[MAXSEGS]; 544 int nsegs; 545 Elf_Phdr *phdyn; 546 Elf_Phdr *phphdr; 547 caddr_t mapbase; 548 size_t mapsize; 549 Elf_Off base_offset; 550 Elf_Addr base_vaddr; 551 Elf_Addr base_vlimit; 552 int error = 0; 553 int resid, flags; 554 elf_file_t ef; 555 linker_file_t lf; 556 Elf_Shdr *shdr; 557 int symtabindex; 558 int symstrindex; 559 int symcnt; 560 int strcnt; 561 int vfslocked; 562 563 shdr = NULL; 564 lf = NULL; 565 566 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, filename, td); 567 flags = FREAD; 568 error = vn_open(&nd, &flags, 0, -1); 569 if (error) 570 return error; 571 vfslocked = NDHASGIANT(&nd); 572 NDFREE(&nd, NDF_ONLY_PNBUF); 573 #ifdef MAC 574 error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp); 575 if (error) { 576 firstpage = NULL; 577 goto out; 578 } 579 #endif 580 581 /* 582 * Read the elf header from the file. 583 */ 584 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK); 585 if (firstpage == NULL) { 586 error = ENOMEM; 587 goto out; 588 } 589 hdr = (Elf_Ehdr *)firstpage; 590 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0, 591 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 592 &resid, td); 593 nbytes = PAGE_SIZE - resid; 594 if (error) 595 goto out; 596 597 if (!IS_ELF(*hdr)) { 598 error = ENOEXEC; 599 goto out; 600 } 601 602 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 603 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 604 link_elf_error("Unsupported file layout"); 605 error = ENOEXEC; 606 goto out; 607 } 608 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 609 || hdr->e_version != EV_CURRENT) { 610 link_elf_error("Unsupported file version"); 611 error = ENOEXEC; 612 goto out; 613 } 614 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 615 link_elf_error("Unsupported file type"); 616 error = ENOEXEC; 617 goto out; 618 } 619 if (hdr->e_machine != ELF_TARG_MACH) { 620 link_elf_error("Unsupported machine"); 621 error = ENOEXEC; 622 goto out; 623 } 624 625 /* 626 * We rely on the program header being in the first page. This is 627 * not strictly required by the ABI specification, but it seems to 628 * always true in practice. And, it simplifies things considerably. 629 */ 630 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 631 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 632 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 633 link_elf_error("Unreadable program headers"); 634 635 /* 636 * Scan the program header entries, and save key information. 637 * 638 * We rely on there being exactly two load segments, text and data, 639 * in that order. 640 */ 641 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 642 phlimit = phdr + hdr->e_phnum; 643 nsegs = 0; 644 phdyn = NULL; 645 phphdr = NULL; 646 while (phdr < phlimit) { 647 switch (phdr->p_type) { 648 649 case PT_LOAD: 650 if (nsegs == MAXSEGS) { 651 link_elf_error("Too many sections"); 652 error = ENOEXEC; 653 goto out; 654 } 655 /* 656 * XXX: We just trust they come in right order ?? 657 */ 658 segs[nsegs] = phdr; 659 ++nsegs; 660 break; 661 662 case PT_PHDR: 663 phphdr = phdr; 664 break; 665 666 case PT_DYNAMIC: 667 phdyn = phdr; 668 break; 669 670 case PT_INTERP: 671 link_elf_error("Unsupported file type"); 672 error = ENOEXEC; 673 goto out; 674 } 675 676 ++phdr; 677 } 678 if (phdyn == NULL) { 679 link_elf_error("Object is not dynamically-linked"); 680 error = ENOEXEC; 681 goto out; 682 } 683 if (nsegs == 0) { 684 link_elf_error("No sections"); 685 error = ENOEXEC; 686 goto out; 687 } 688 689 /* 690 * Allocate the entire address space of the object, to stake out our 691 * contiguous region, and to establish the base address for relocation. 692 */ 693 base_offset = trunc_page(segs[0]->p_offset); 694 base_vaddr = trunc_page(segs[0]->p_vaddr); 695 base_vlimit = round_page(segs[nsegs - 1]->p_vaddr + 696 segs[nsegs - 1]->p_memsz); 697 mapsize = base_vlimit - base_vaddr; 698 699 lf = linker_make_file(filename, &link_elf_class); 700 if (!lf) { 701 error = ENOMEM; 702 goto out; 703 } 704 705 ef = (elf_file_t) lf; 706 #ifdef SPARSE_MAPPING 707 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 708 if (ef->object == NULL) { 709 error = ENOMEM; 710 goto out; 711 } 712 ef->address = (caddr_t) vm_map_min(kernel_map); 713 error = vm_map_find(kernel_map, ef->object, 0, 714 (vm_offset_t *) &ef->address, 715 mapsize, 1, 716 VM_PROT_ALL, VM_PROT_ALL, 0); 717 if (error) { 718 vm_object_deallocate(ef->object); 719 ef->object = 0; 720 goto out; 721 } 722 #else 723 ef->address = malloc(mapsize, M_LINKER, M_WAITOK); 724 if (!ef->address) { 725 error = ENOMEM; 726 goto out; 727 } 728 #endif 729 mapbase = ef->address; 730 731 /* 732 * Read the text and data sections and zero the bss. 733 */ 734 for (i = 0; i < nsegs; i++) { 735 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 736 error = vn_rdwr(UIO_READ, nd.ni_vp, 737 segbase, segs[i]->p_filesz, segs[i]->p_offset, 738 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 739 &resid, td); 740 if (error) { 741 goto out; 742 } 743 bzero(segbase + segs[i]->p_filesz, 744 segs[i]->p_memsz - segs[i]->p_filesz); 745 746 #ifdef SPARSE_MAPPING 747 /* 748 * Wire down the pages 749 */ 750 error = vm_map_wire(kernel_map, 751 (vm_offset_t) segbase, 752 (vm_offset_t) segbase + segs[i]->p_memsz, 753 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES); 754 if (error != KERN_SUCCESS) { 755 error = ENOMEM; 756 goto out; 757 } 758 #endif 759 } 760 761 #ifdef GPROF 762 /* Update profiling information with the new text segment. */ 763 mtx_lock(&Giant); 764 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr + 765 segs[0]->p_memsz)); 766 mtx_unlock(&Giant); 767 #endif 768 769 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 770 771 lf->address = ef->address; 772 lf->size = mapsize; 773 774 error = parse_dynamic(ef); 775 if (error) 776 goto out; 777 link_elf_reloc_local(lf); 778 779 error = linker_load_dependencies(lf); 780 if (error) 781 goto out; 782 #if 0 /* this will be more trouble than it's worth for now */ 783 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 784 if (dp->d_tag != DT_NEEDED) 785 continue; 786 modname = ef->strtab + dp->d_un.d_val; 787 error = linker_load_module(modname, lf); 788 if (error) 789 goto out; 790 } 791 #endif 792 error = relocate_file(ef); 793 if (error) 794 goto out; 795 796 /* Try and load the symbol table if it's present. (you can strip it!) */ 797 nbytes = hdr->e_shnum * hdr->e_shentsize; 798 if (nbytes == 0 || hdr->e_shoff == 0) 799 goto nosyms; 800 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 801 if (shdr == NULL) { 802 error = ENOMEM; 803 goto out; 804 } 805 error = vn_rdwr(UIO_READ, nd.ni_vp, 806 (caddr_t)shdr, nbytes, hdr->e_shoff, 807 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 808 &resid, td); 809 if (error) 810 goto out; 811 symtabindex = -1; 812 symstrindex = -1; 813 for (i = 0; i < hdr->e_shnum; i++) { 814 if (shdr[i].sh_type == SHT_SYMTAB) { 815 symtabindex = i; 816 symstrindex = shdr[i].sh_link; 817 } 818 } 819 if (symtabindex < 0 || symstrindex < 0) 820 goto nosyms; 821 822 symcnt = shdr[symtabindex].sh_size; 823 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK); 824 strcnt = shdr[symstrindex].sh_size; 825 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK); 826 827 if (ef->symbase == NULL || ef->strbase == NULL) { 828 error = ENOMEM; 829 goto out; 830 } 831 error = vn_rdwr(UIO_READ, nd.ni_vp, 832 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 833 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 834 &resid, td); 835 if (error) 836 goto out; 837 error = vn_rdwr(UIO_READ, nd.ni_vp, 838 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 839 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 840 &resid, td); 841 if (error) 842 goto out; 843 844 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 845 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 846 ef->ddbstrcnt = strcnt; 847 ef->ddbstrtab = ef->strbase; 848 849 error = link_elf_link_common_finish(lf); 850 if (error) 851 goto out; 852 853 nosyms: 854 855 *result = lf; 856 857 out: 858 if (error && lf) 859 linker_file_unload(lf, LINKER_UNLOAD_FORCE); 860 if (shdr) 861 free(shdr, M_LINKER); 862 if (firstpage) 863 free(firstpage, M_LINKER); 864 VOP_UNLOCK(nd.ni_vp, 0, td); 865 vn_close(nd.ni_vp, FREAD, td->td_ucred, td); 866 VFS_UNLOCK_GIANT(vfslocked); 867 868 return error; 869 } 870 871 static void 872 link_elf_unload_file(linker_file_t file) 873 { 874 elf_file_t ef = (elf_file_t) file; 875 876 #ifdef GDB 877 if (ef->gdb.l_ld) { 878 GDB_STATE(RT_DELETE); 879 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER); 880 link_elf_delete_gdb(&ef->gdb); 881 GDB_STATE(RT_CONSISTENT); 882 } 883 #endif 884 885 /* Notify MD code that a module is being unloaded. */ 886 elf_cpu_unload_file(file); 887 888 if (ef->preloaded) { 889 link_elf_unload_preload(file); 890 return; 891 } 892 893 #ifdef SPARSE_MAPPING 894 if (ef->object) { 895 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 896 (vm_offset_t) ef->address 897 + (ef->object->size << PAGE_SHIFT)); 898 } 899 #else 900 if (ef->address) 901 free(ef->address, M_LINKER); 902 #endif 903 if (ef->symbase) 904 free(ef->symbase, M_LINKER); 905 if (ef->strbase) 906 free(ef->strbase, M_LINKER); 907 } 908 909 static void 910 link_elf_unload_preload(linker_file_t file) 911 { 912 if (file->filename) 913 preload_delete_name(file->filename); 914 } 915 916 static const char * 917 symbol_name(elf_file_t ef, Elf_Size r_info) 918 { 919 const Elf_Sym *ref; 920 921 if (ELF_R_SYM(r_info)) { 922 ref = ef->symtab + ELF_R_SYM(r_info); 923 return ef->strtab + ref->st_name; 924 } else 925 return NULL; 926 } 927 928 static int 929 relocate_file(elf_file_t ef) 930 { 931 const Elf_Rel *rellim; 932 const Elf_Rel *rel; 933 const Elf_Rela *relalim; 934 const Elf_Rela *rela; 935 const char *symname; 936 937 /* Perform relocations without addend if there are any: */ 938 rel = ef->rel; 939 if (rel) { 940 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 941 while (rel < rellim) { 942 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 943 elf_lookup)) { 944 symname = symbol_name(ef, rel->r_info); 945 printf("link_elf: symbol %s undefined\n", symname); 946 return ENOENT; 947 } 948 rel++; 949 } 950 } 951 952 /* Perform relocations with addend if there are any: */ 953 rela = ef->rela; 954 if (rela) { 955 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 956 while (rela < relalim) { 957 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 958 elf_lookup)) { 959 symname = symbol_name(ef, rela->r_info); 960 printf("link_elf: symbol %s undefined\n", symname); 961 return ENOENT; 962 } 963 rela++; 964 } 965 } 966 967 /* Perform PLT relocations without addend if there are any: */ 968 rel = ef->pltrel; 969 if (rel) { 970 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 971 while (rel < rellim) { 972 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 973 elf_lookup)) { 974 symname = symbol_name(ef, rel->r_info); 975 printf("link_elf: symbol %s undefined\n", symname); 976 return ENOENT; 977 } 978 rel++; 979 } 980 } 981 982 /* Perform relocations with addend if there are any: */ 983 rela = ef->pltrela; 984 if (rela) { 985 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 986 while (rela < relalim) { 987 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 988 elf_lookup)) { 989 symname = symbol_name(ef, rela->r_info); 990 printf("link_elf: symbol %s undefined\n", symname); 991 return ENOENT; 992 } 993 rela++; 994 } 995 } 996 997 return 0; 998 } 999 1000 /* 1001 * Hash function for symbol table lookup. Don't even think about changing 1002 * this. It is specified by the System V ABI. 1003 */ 1004 static unsigned long 1005 elf_hash(const char *name) 1006 { 1007 const unsigned char *p = (const unsigned char *) name; 1008 unsigned long h = 0; 1009 unsigned long g; 1010 1011 while (*p != '\0') { 1012 h = (h << 4) + *p++; 1013 if ((g = h & 0xf0000000) != 0) 1014 h ^= g >> 24; 1015 h &= ~g; 1016 } 1017 return h; 1018 } 1019 1020 static int 1021 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 1022 { 1023 elf_file_t ef = (elf_file_t) lf; 1024 unsigned long symnum; 1025 const Elf_Sym* symp; 1026 const char *strp; 1027 unsigned long hash; 1028 int i; 1029 1030 /* If we don't have a hash, bail. */ 1031 if (ef->buckets == NULL || ef->nbuckets == 0) { 1032 printf("link_elf_lookup_symbol: missing symbol hash table\n"); 1033 return ENOENT; 1034 } 1035 1036 /* First, search hashed global symbols */ 1037 hash = elf_hash(name); 1038 symnum = ef->buckets[hash % ef->nbuckets]; 1039 1040 while (symnum != STN_UNDEF) { 1041 if (symnum >= ef->nchains) { 1042 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 1043 return ENOENT; 1044 } 1045 1046 symp = ef->symtab + symnum; 1047 if (symp->st_name == 0) { 1048 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 1049 return ENOENT; 1050 } 1051 1052 strp = ef->strtab + symp->st_name; 1053 1054 if (strcmp(name, strp) == 0) { 1055 if (symp->st_shndx != SHN_UNDEF || 1056 (symp->st_value != 0 && 1057 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 1058 *sym = (c_linker_sym_t) symp; 1059 return 0; 1060 } else 1061 return ENOENT; 1062 } 1063 1064 symnum = ef->chains[symnum]; 1065 } 1066 1067 /* If we have not found it, look at the full table (if loaded) */ 1068 if (ef->symtab == ef->ddbsymtab) 1069 return ENOENT; 1070 1071 /* Exhaustive search */ 1072 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 1073 strp = ef->ddbstrtab + symp->st_name; 1074 if (strcmp(name, strp) == 0) { 1075 if (symp->st_shndx != SHN_UNDEF || 1076 (symp->st_value != 0 && 1077 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 1078 *sym = (c_linker_sym_t) symp; 1079 return 0; 1080 } else 1081 return ENOENT; 1082 } 1083 } 1084 1085 return ENOENT; 1086 } 1087 1088 static int 1089 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 1090 { 1091 elf_file_t ef = (elf_file_t) lf; 1092 const Elf_Sym* es = (const Elf_Sym*) sym; 1093 1094 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) { 1095 symval->name = ef->strtab + es->st_name; 1096 symval->value = (caddr_t) ef->address + es->st_value; 1097 symval->size = es->st_size; 1098 return 0; 1099 } 1100 if (ef->symtab == ef->ddbsymtab) 1101 return ENOENT; 1102 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) { 1103 symval->name = ef->ddbstrtab + es->st_name; 1104 symval->value = (caddr_t) ef->address + es->st_value; 1105 symval->size = es->st_size; 1106 return 0; 1107 } 1108 return ENOENT; 1109 } 1110 1111 static int 1112 link_elf_search_symbol(linker_file_t lf, caddr_t value, 1113 c_linker_sym_t* sym, long* diffp) 1114 { 1115 elf_file_t ef = (elf_file_t) lf; 1116 u_long off = (uintptr_t) (void *) value; 1117 u_long diff = off; 1118 u_long st_value; 1119 const Elf_Sym* es; 1120 const Elf_Sym* best = 0; 1121 int i; 1122 1123 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 1124 if (es->st_name == 0) 1125 continue; 1126 st_value = es->st_value + (uintptr_t) (void *) ef->address; 1127 if (off >= st_value) { 1128 if (off - st_value < diff) { 1129 diff = off - st_value; 1130 best = es; 1131 if (diff == 0) 1132 break; 1133 } else if (off - st_value == diff) { 1134 best = es; 1135 } 1136 } 1137 } 1138 if (best == 0) 1139 *diffp = off; 1140 else 1141 *diffp = diff; 1142 *sym = (c_linker_sym_t) best; 1143 1144 return 0; 1145 } 1146 1147 /* 1148 * Look up a linker set on an ELF system. 1149 */ 1150 static int 1151 link_elf_lookup_set(linker_file_t lf, const char *name, 1152 void ***startp, void ***stopp, int *countp) 1153 { 1154 c_linker_sym_t sym; 1155 linker_symval_t symval; 1156 char *setsym; 1157 void **start, **stop; 1158 int len, error = 0, count; 1159 1160 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1161 setsym = malloc(len, M_LINKER, M_WAITOK); 1162 if (setsym == NULL) 1163 return ENOMEM; 1164 1165 /* get address of first entry */ 1166 snprintf(setsym, len, "%s%s", "__start_set_", name); 1167 error = link_elf_lookup_symbol(lf, setsym, &sym); 1168 if (error) 1169 goto out; 1170 link_elf_symbol_values(lf, sym, &symval); 1171 if (symval.value == 0) { 1172 error = ESRCH; 1173 goto out; 1174 } 1175 start = (void **)symval.value; 1176 1177 /* get address of last entry */ 1178 snprintf(setsym, len, "%s%s", "__stop_set_", name); 1179 error = link_elf_lookup_symbol(lf, setsym, &sym); 1180 if (error) 1181 goto out; 1182 link_elf_symbol_values(lf, sym, &symval); 1183 if (symval.value == 0) { 1184 error = ESRCH; 1185 goto out; 1186 } 1187 stop = (void **)symval.value; 1188 1189 /* and the number of entries */ 1190 count = stop - start; 1191 1192 /* and copy out */ 1193 if (startp) 1194 *startp = start; 1195 if (stopp) 1196 *stopp = stop; 1197 if (countp) 1198 *countp = count; 1199 1200 out: 1201 free(setsym, M_LINKER); 1202 return error; 1203 } 1204 1205 static int 1206 link_elf_each_function_name(linker_file_t file, 1207 int (*callback)(const char *, void *), void *opaque) { 1208 elf_file_t ef = (elf_file_t)file; 1209 const Elf_Sym* symp; 1210 int i, error; 1211 1212 /* Exhaustive search */ 1213 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 1214 if (symp->st_value != 0 && 1215 ELF_ST_TYPE(symp->st_info) == STT_FUNC) { 1216 error = callback(ef->ddbstrtab + symp->st_name, opaque); 1217 if (error) 1218 return (error); 1219 } 1220 } 1221 return (0); 1222 } 1223 1224 #ifdef __ia64__ 1225 /* 1226 * Each KLD has its own GP. The GP value for each load module is given by 1227 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but 1228 * don't have direct access to the ELF file structure. The link_elf_get_gp() 1229 * function returns the GP given a pointer to a generic linker file struct. 1230 */ 1231 Elf_Addr 1232 link_elf_get_gp(linker_file_t lf) 1233 { 1234 elf_file_t ef = (elf_file_t)lf; 1235 return (Elf_Addr)ef->got; 1236 } 1237 #endif 1238 1239 const Elf_Sym * 1240 elf_get_sym(linker_file_t lf, Elf_Size symidx) 1241 { 1242 elf_file_t ef = (elf_file_t)lf; 1243 1244 if (symidx >= ef->nchains) 1245 return (NULL); 1246 return (ef->symtab + symidx); 1247 } 1248 1249 const char * 1250 elf_get_symname(linker_file_t lf, Elf_Size symidx) 1251 { 1252 elf_file_t ef = (elf_file_t)lf; 1253 const Elf_Sym *sym; 1254 1255 if (symidx >= ef->nchains) 1256 return (NULL); 1257 sym = ef->symtab + symidx; 1258 return (ef->strtab + sym->st_name); 1259 } 1260 1261 /* 1262 * Symbol lookup function that can be used when the symbol index is known (ie 1263 * in relocations). It uses the symbol index instead of doing a fully fledged 1264 * hash table based lookup when such is valid. For example for local symbols. 1265 * This is not only more efficient, it's also more correct. It's not always 1266 * the case that the symbol can be found through the hash table. 1267 */ 1268 static Elf_Addr 1269 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps) 1270 { 1271 elf_file_t ef = (elf_file_t)lf; 1272 const Elf_Sym *sym; 1273 const char *symbol; 1274 1275 /* Don't even try to lookup the symbol if the index is bogus. */ 1276 if (symidx >= ef->nchains) 1277 return (0); 1278 1279 sym = ef->symtab + symidx; 1280 1281 /* 1282 * Don't do a full lookup when the symbol is local. It may even 1283 * fail because it may not be found through the hash table. 1284 */ 1285 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1286 /* Force lookup failure when we have an insanity. */ 1287 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1288 return (0); 1289 return ((Elf_Addr)ef->address + sym->st_value); 1290 } 1291 1292 /* 1293 * XXX we can avoid doing a hash table based lookup for global 1294 * symbols as well. This however is not always valid, so we'll 1295 * just do it the hard way for now. Performance tweaks can 1296 * always be added. 1297 */ 1298 1299 symbol = ef->strtab + sym->st_name; 1300 1301 /* Force a lookup failure if the symbol name is bogus. */ 1302 if (*symbol == 0) 1303 return (0); 1304 1305 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps)); 1306 } 1307 1308 static void 1309 link_elf_reloc_local(linker_file_t lf) 1310 { 1311 const Elf_Rel *rellim; 1312 const Elf_Rel *rel; 1313 const Elf_Rela *relalim; 1314 const Elf_Rela *rela; 1315 elf_file_t ef = (elf_file_t)lf; 1316 1317 /* Perform relocations without addend if there are any: */ 1318 if ((rel = ef->rel) != NULL) { 1319 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1320 while (rel < rellim) { 1321 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1322 elf_lookup); 1323 rel++; 1324 } 1325 } 1326 1327 /* Perform relocations with addend if there are any: */ 1328 if ((rela = ef->rela) != NULL) { 1329 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1330 while (rela < relalim) { 1331 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1332 elf_lookup); 1333 rela++; 1334 } 1335 } 1336 } 1337