1 /*- 2 * Copyright (c) 1998 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 * $FreeBSD: src/sys/kern/link_elf.c,v 1.24 1999/12/24 15:33:36 bde Exp $ 27 * $DragonFly: src/sys/kern/link_elf.c,v 1.13 2004/03/20 16:27:41 drhodus Exp $ 28 */ 29 30 #include <sys/param.h> 31 #include <sys/kernel.h> 32 #include <sys/systm.h> 33 #include <sys/malloc.h> 34 #include <sys/proc.h> 35 #include <sys/namei.h> 36 #include <sys/fcntl.h> 37 #include <sys/vnode.h> 38 #include <sys/linker.h> 39 #include <machine/elf.h> 40 41 #include <vm/vm.h> 42 #include <vm/vm_param.h> 43 #include <vm/vm_zone.h> 44 #include <sys/lock.h> 45 #ifdef SPARSE_MAPPING 46 #include <vm/vm_object.h> 47 #include <vm/vm_kern.h> 48 #include <vm/vm_extern.h> 49 #endif 50 #include <vm/pmap.h> 51 #include <vm/vm_map.h> 52 53 static int link_elf_load_module(const char*, linker_file_t*); 54 static int link_elf_load_file(const char*, linker_file_t*); 55 static int link_elf_lookup_symbol(linker_file_t, const char*, 56 c_linker_sym_t*); 57 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 58 static int link_elf_search_symbol(linker_file_t, caddr_t value, 59 c_linker_sym_t* sym, long* diffp); 60 61 static void link_elf_unload_file(linker_file_t); 62 static void link_elf_unload_module(linker_file_t); 63 static int link_elf_lookup_set(linker_file_t, const char *, 64 void ***, void ***, int *); 65 66 67 static struct linker_class_ops link_elf_class_ops = { 68 link_elf_load_module, 69 }; 70 71 static struct linker_file_ops link_elf_file_ops = { 72 link_elf_lookup_symbol, 73 link_elf_symbol_values, 74 link_elf_search_symbol, 75 link_elf_unload_file, 76 link_elf_lookup_set 77 }; 78 79 static struct linker_file_ops link_elf_module_ops = { 80 link_elf_lookup_symbol, 81 link_elf_symbol_values, 82 link_elf_search_symbol, 83 link_elf_unload_module, 84 link_elf_lookup_set 85 }; 86 typedef struct elf_file { 87 caddr_t address; /* Relocation address */ 88 #ifdef SPARSE_MAPPING 89 vm_object_t object; /* VM object to hold file pages */ 90 #endif 91 const Elf_Dyn* dynamic; /* Symbol table etc. */ 92 Elf_Off nbuckets; /* DT_HASH info */ 93 Elf_Off nchains; 94 const Elf_Off* buckets; 95 const Elf_Off* chains; 96 caddr_t hash; 97 caddr_t strtab; /* DT_STRTAB */ 98 int strsz; /* DT_STRSZ */ 99 const Elf_Sym* symtab; /* DT_SYMTAB */ 100 Elf_Addr* got; /* DT_PLTGOT */ 101 const Elf_Rel* pltrel; /* DT_JMPREL */ 102 int pltrelsize; /* DT_PLTRELSZ */ 103 const Elf_Rela* pltrela; /* DT_JMPREL */ 104 int pltrelasize; /* DT_PLTRELSZ */ 105 const Elf_Rel* rel; /* DT_REL */ 106 int relsize; /* DT_RELSZ */ 107 const Elf_Rela* rela; /* DT_RELA */ 108 int relasize; /* DT_RELASZ */ 109 caddr_t modptr; 110 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 111 long ddbsymcnt; /* Number of symbols */ 112 caddr_t ddbstrtab; /* String table */ 113 long ddbstrcnt; /* number of bytes in string table */ 114 caddr_t symbase; /* malloc'ed symbold base */ 115 caddr_t strbase; /* malloc'ed string base */ 116 } *elf_file_t; 117 118 static int parse_dynamic(linker_file_t lf); 119 static int load_dependancies(linker_file_t lf); 120 static int relocate_file(linker_file_t lf); 121 static int parse_module_symbols(linker_file_t lf); 122 123 /* 124 * The kernel symbol table starts here. 125 */ 126 extern struct _dynamic _DYNAMIC; 127 128 static void 129 link_elf_init(void* arg) 130 { 131 Elf_Dyn *dp; 132 caddr_t modptr, baseptr, sizeptr; 133 elf_file_t ef; 134 char *modname; 135 136 #if ELF_TARG_CLASS == ELFCLASS32 137 linker_add_class("elf32", NULL, &link_elf_class_ops); 138 #else 139 linker_add_class("elf64", NULL, &link_elf_class_ops); 140 #endif 141 142 dp = (Elf_Dyn*) &_DYNAMIC; 143 if (dp) { 144 ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT); 145 if (ef == NULL) 146 panic("link_elf_init: Can't create linker structures for kernel"); 147 bzero(ef, sizeof(*ef)); 148 149 ef->address = 0; 150 #ifdef SPARSE_MAPPING 151 ef->object = 0; 152 #endif 153 ef->dynamic = dp; 154 modname = NULL; 155 modptr = preload_search_by_type("elf kernel"); 156 if (modptr) 157 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 158 if (modname == NULL) 159 modname = "kernel"; 160 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 161 if (linker_kernel_file == NULL) 162 panic("link_elf_init: Can't create linker structures for kernel"); 163 parse_dynamic(linker_kernel_file); 164 linker_kernel_file->address = (caddr_t) KERNBASE; 165 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 166 167 if (modptr) { 168 ef->modptr = modptr; 169 baseptr = preload_search_info(modptr, MODINFO_ADDR); 170 if (baseptr) 171 linker_kernel_file->address = *(caddr_t *)baseptr; 172 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 173 if (sizeptr) 174 linker_kernel_file->size = *(size_t *)sizeptr; 175 } 176 (void)parse_module_symbols(linker_kernel_file); 177 linker_current_file = linker_kernel_file; 178 linker_kernel_file->flags |= LINKER_FILE_LINKED; 179 } 180 } 181 182 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 183 184 static int 185 parse_module_symbols(linker_file_t lf) 186 { 187 elf_file_t ef = lf->priv; 188 caddr_t pointer; 189 caddr_t ssym, esym, base; 190 caddr_t strtab; 191 int strcnt; 192 Elf_Sym* symtab; 193 int symcnt; 194 195 if (ef->modptr == NULL) 196 return 0; 197 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 198 if (pointer == NULL) 199 return 0; 200 ssym = *(caddr_t *)pointer; 201 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 202 if (pointer == NULL) 203 return 0; 204 esym = *(caddr_t *)pointer; 205 206 base = ssym; 207 208 symcnt = *(long *)base; 209 base += sizeof(long); 210 symtab = (Elf_Sym *)base; 211 base += roundup(symcnt, sizeof(long)); 212 213 if (base > esym || base < ssym) { 214 printf("Symbols are corrupt!\n"); 215 return EINVAL; 216 } 217 218 strcnt = *(long *)base; 219 base += sizeof(long); 220 strtab = base; 221 base += roundup(strcnt, sizeof(long)); 222 223 if (base > esym || base < ssym) { 224 printf("Symbols are corrupt!\n"); 225 return EINVAL; 226 } 227 228 ef->ddbsymtab = symtab; 229 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 230 ef->ddbstrtab = strtab; 231 ef->ddbstrcnt = strcnt; 232 233 return 0; 234 } 235 236 static int 237 parse_dynamic(linker_file_t lf) 238 { 239 elf_file_t ef = lf->priv; 240 const Elf_Dyn *dp; 241 int plttype = DT_REL; 242 243 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 244 switch (dp->d_tag) { 245 case DT_HASH: 246 { 247 /* From src/libexec/rtld-elf/rtld.c */ 248 const Elf_Off *hashtab = (const Elf_Off *) 249 (ef->address + dp->d_un.d_ptr); 250 ef->nbuckets = hashtab[0]; 251 ef->nchains = hashtab[1]; 252 ef->buckets = hashtab + 2; 253 ef->chains = ef->buckets + ef->nbuckets; 254 break; 255 } 256 case DT_STRTAB: 257 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 258 break; 259 case DT_STRSZ: 260 ef->strsz = dp->d_un.d_val; 261 break; 262 case DT_SYMTAB: 263 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 264 break; 265 case DT_SYMENT: 266 if (dp->d_un.d_val != sizeof(Elf_Sym)) 267 return ENOEXEC; 268 break; 269 case DT_PLTGOT: 270 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 271 break; 272 case DT_REL: 273 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 274 break; 275 case DT_RELSZ: 276 ef->relsize = dp->d_un.d_val; 277 break; 278 case DT_RELENT: 279 if (dp->d_un.d_val != sizeof(Elf_Rel)) 280 return ENOEXEC; 281 break; 282 case DT_JMPREL: 283 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 284 break; 285 case DT_PLTRELSZ: 286 ef->pltrelsize = dp->d_un.d_val; 287 break; 288 case DT_RELA: 289 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 290 break; 291 case DT_RELASZ: 292 ef->relasize = dp->d_un.d_val; 293 break; 294 case DT_RELAENT: 295 if (dp->d_un.d_val != sizeof(Elf_Rela)) 296 return ENOEXEC; 297 break; 298 case DT_PLTREL: 299 plttype = dp->d_un.d_val; 300 if (plttype != DT_REL && plttype != DT_RELA) 301 return ENOEXEC; 302 break; 303 } 304 } 305 306 if (plttype == DT_RELA) { 307 ef->pltrela = (const Elf_Rela *) ef->pltrel; 308 ef->pltrel = NULL; 309 ef->pltrelasize = ef->pltrelsize; 310 ef->pltrelsize = 0; 311 } 312 313 ef->ddbsymtab = ef->symtab; 314 ef->ddbsymcnt = ef->nchains; 315 ef->ddbstrtab = ef->strtab; 316 ef->ddbstrcnt = ef->strsz; 317 318 return 0; 319 } 320 321 static void 322 link_elf_error(const char *s) 323 { 324 printf("kldload: %s\n", s); 325 } 326 327 static int 328 link_elf_load_module(const char *filename, linker_file_t *result) 329 { 330 caddr_t modptr, baseptr, sizeptr, dynptr; 331 char *type; 332 elf_file_t ef; 333 linker_file_t lf; 334 int error; 335 vm_offset_t dp; 336 337 /* 338 * Look to see if we have the module preloaded. 339 */ 340 modptr = preload_search_by_name(filename); 341 if (modptr == NULL) 342 return (link_elf_load_file(filename, result)); 343 344 /* It's preloaded, check we can handle it and collect information */ 345 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 346 baseptr = preload_search_info(modptr, MODINFO_ADDR); 347 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 348 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 349 if (type == NULL || strcmp(type, "elf module") != 0) 350 return (EFTYPE); 351 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 352 return (EINVAL); 353 354 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 355 if (ef == NULL) 356 return (ENOMEM); 357 bzero(ef, sizeof(*ef)); 358 ef->modptr = modptr; 359 ef->address = *(caddr_t *)baseptr; 360 #ifdef SPARSE_MAPPING 361 ef->object = 0; 362 #endif 363 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 364 ef->dynamic = (Elf_Dyn *)dp; 365 lf = linker_make_file(filename, ef, &link_elf_module_ops); 366 if (lf == NULL) { 367 free(ef, M_LINKER); 368 return ENOMEM; 369 } 370 lf->address = ef->address; 371 lf->size = *(size_t *)sizeptr; 372 373 error = parse_dynamic(lf); 374 if (error) { 375 linker_file_unload(lf); 376 return error; 377 } 378 error = load_dependancies(lf); 379 if (error) { 380 linker_file_unload(lf); 381 return error; 382 } 383 error = relocate_file(lf); 384 if (error) { 385 linker_file_unload(lf); 386 return error; 387 } 388 (void)parse_module_symbols(lf); 389 lf->flags |= LINKER_FILE_LINKED; 390 *result = lf; 391 return (0); 392 } 393 394 static int 395 link_elf_load_file(const char* filename, linker_file_t* result) 396 { 397 struct nameidata nd; 398 struct thread *td = curthread; /* XXX */ 399 struct proc *p = td->td_proc; 400 Elf_Ehdr *hdr; 401 caddr_t firstpage; 402 int nbytes, i; 403 Elf_Phdr *phdr; 404 Elf_Phdr *phlimit; 405 Elf_Phdr *segs[2]; 406 int nsegs; 407 Elf_Phdr *phdyn; 408 Elf_Phdr *phphdr; 409 caddr_t mapbase; 410 size_t mapsize; 411 Elf_Off base_offset; 412 Elf_Addr base_vaddr; 413 Elf_Addr base_vlimit; 414 int error = 0; 415 int resid; 416 elf_file_t ef; 417 linker_file_t lf; 418 char *pathname; 419 Elf_Shdr *shdr; 420 int symtabindex; 421 int symstrindex; 422 int symcnt; 423 int strcnt; 424 425 KKASSERT(p != NULL); 426 if (p->p_ucred == NULL) { 427 printf("link_elf_load_file: cannot load '%s' from filesystem" 428 " this early\n", filename); 429 return ENOENT; 430 } 431 shdr = NULL; 432 lf = NULL; 433 pathname = linker_search_path(filename); 434 if (pathname == NULL) 435 return ENOENT; 436 437 NDINIT(&nd, NAMEI_LOOKUP, CNP_FOLLOW, UIO_SYSSPACE, pathname, td); 438 error = vn_open(&nd, FREAD, 0); 439 free(pathname, M_LINKER); 440 if (error) 441 return error; 442 NDFREE(&nd, NDF_ONLY_PNBUF); 443 444 /* 445 * Read the elf header from the file. 446 */ 447 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK); 448 if (firstpage == NULL) { 449 error = ENOMEM; 450 goto out; 451 } 452 hdr = (Elf_Ehdr *)firstpage; 453 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0, 454 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 455 nbytes = PAGE_SIZE - resid; 456 if (error) 457 goto out; 458 459 if (!IS_ELF(*hdr)) { 460 error = ENOEXEC; 461 goto out; 462 } 463 464 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 465 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 466 link_elf_error("Unsupported file layout"); 467 error = ENOEXEC; 468 goto out; 469 } 470 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 471 || hdr->e_version != EV_CURRENT) { 472 link_elf_error("Unsupported file version"); 473 error = ENOEXEC; 474 goto out; 475 } 476 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 477 link_elf_error("Unsupported file type"); 478 error = ENOEXEC; 479 goto out; 480 } 481 if (hdr->e_machine != ELF_TARG_MACH) { 482 link_elf_error("Unsupported machine"); 483 error = ENOEXEC; 484 goto out; 485 } 486 487 /* 488 * We rely on the program header being in the first page. This is 489 * not strictly required by the ABI specification, but it seems to 490 * always true in practice. And, it simplifies things considerably. 491 */ 492 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 493 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 494 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 495 link_elf_error("Unreadable program headers"); 496 497 /* 498 * Scan the program header entries, and save key information. 499 * 500 * We rely on there being exactly two load segments, text and data, 501 * in that order. 502 */ 503 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 504 phlimit = phdr + hdr->e_phnum; 505 nsegs = 0; 506 phdyn = NULL; 507 phphdr = NULL; 508 while (phdr < phlimit) { 509 switch (phdr->p_type) { 510 511 case PT_LOAD: 512 if (nsegs == 2) { 513 link_elf_error("Too many sections"); 514 error = ENOEXEC; 515 goto out; 516 } 517 segs[nsegs] = phdr; 518 ++nsegs; 519 break; 520 521 case PT_PHDR: 522 phphdr = phdr; 523 break; 524 525 case PT_DYNAMIC: 526 phdyn = phdr; 527 break; 528 } 529 530 ++phdr; 531 } 532 if (phdyn == NULL) { 533 link_elf_error("Object is not dynamically-linked"); 534 error = ENOEXEC; 535 goto out; 536 } 537 538 /* 539 * Allocate the entire address space of the object, to stake out our 540 * contiguous region, and to establish the base address for relocation. 541 */ 542 base_offset = trunc_page(segs[0]->p_offset); 543 base_vaddr = trunc_page(segs[0]->p_vaddr); 544 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 545 mapsize = base_vlimit - base_vaddr; 546 547 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 548 bzero(ef, sizeof(*ef)); 549 #ifdef SPARSE_MAPPING 550 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 551 if (ef->object == NULL) { 552 free(ef, M_LINKER); 553 error = ENOMEM; 554 goto out; 555 } 556 vm_object_reference(ef->object); 557 ef->address = (caddr_t) vm_map_min(kernel_map); 558 error = vm_map_find(kernel_map, ef->object, 0, 559 (vm_offset_t *) &ef->address, 560 mapsize, 1, 561 VM_PROT_ALL, VM_PROT_ALL, 0); 562 if (error) { 563 vm_object_deallocate(ef->object); 564 free(ef, M_LINKER); 565 goto out; 566 } 567 #else 568 ef->address = malloc(mapsize, M_LINKER, M_WAITOK); 569 #endif 570 mapbase = ef->address; 571 572 /* 573 * Read the text and data sections and zero the bss. 574 */ 575 for (i = 0; i < 2; i++) { 576 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 577 error = vn_rdwr(UIO_READ, nd.ni_vp, 578 segbase, segs[i]->p_filesz, segs[i]->p_offset, 579 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 580 if (error) { 581 #ifdef SPARSE_MAPPING 582 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 583 (vm_offset_t) ef->address 584 + (ef->object->size << PAGE_SHIFT)); 585 vm_object_deallocate(ef->object); 586 #else 587 free(ef->address, M_LINKER); 588 #endif 589 free(ef, M_LINKER); 590 goto out; 591 } 592 bzero(segbase + segs[i]->p_filesz, 593 segs[i]->p_memsz - segs[i]->p_filesz); 594 595 #ifdef SPARSE_MAPPING 596 /* 597 * Wire down the pages 598 */ 599 vm_map_wire(kernel_map, 600 (vm_offset_t) segbase, 601 (vm_offset_t) segbase + segs[i]->p_memsz, 602 0); 603 #endif 604 } 605 606 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 607 608 lf = linker_make_file(filename, ef, &link_elf_file_ops); 609 if (lf == NULL) { 610 #ifdef SPARSE_MAPPING 611 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 612 (vm_offset_t) ef->address 613 + (ef->object->size << PAGE_SHIFT)); 614 vm_object_deallocate(ef->object); 615 #else 616 free(ef->address, M_LINKER); 617 #endif 618 free(ef, M_LINKER); 619 error = ENOMEM; 620 goto out; 621 } 622 lf->address = ef->address; 623 lf->size = mapsize; 624 625 error = parse_dynamic(lf); 626 if (error) 627 goto out; 628 error = load_dependancies(lf); 629 if (error) 630 goto out; 631 error = relocate_file(lf); 632 if (error) 633 goto out; 634 635 /* Try and load the symbol table if it's present. (you can strip it!) */ 636 nbytes = hdr->e_shnum * hdr->e_shentsize; 637 if (nbytes == 0 || hdr->e_shoff == 0) 638 goto nosyms; 639 shdr = malloc(nbytes, M_LINKER, M_WAITOK); 640 if (shdr == NULL) { 641 error = ENOMEM; 642 goto out; 643 } 644 bzero(shdr, nbytes); 645 error = vn_rdwr(UIO_READ, nd.ni_vp, 646 (caddr_t)shdr, nbytes, hdr->e_shoff, 647 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 648 if (error) 649 goto out; 650 symtabindex = -1; 651 symstrindex = -1; 652 for (i = 0; i < hdr->e_shnum; i++) { 653 if (shdr[i].sh_type == SHT_SYMTAB) { 654 symtabindex = i; 655 symstrindex = shdr[i].sh_link; 656 } 657 } 658 if (symtabindex < 0 || symstrindex < 0) 659 goto nosyms; 660 661 symcnt = shdr[symtabindex].sh_size; 662 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK); 663 strcnt = shdr[symstrindex].sh_size; 664 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK); 665 666 if (ef->symbase == NULL || ef->strbase == NULL) { 667 error = ENOMEM; 668 goto out; 669 } 670 error = vn_rdwr(UIO_READ, nd.ni_vp, 671 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 672 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 673 if (error) 674 goto out; 675 error = vn_rdwr(UIO_READ, nd.ni_vp, 676 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 677 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 678 if (error) 679 goto out; 680 681 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 682 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 683 ef->ddbstrcnt = strcnt; 684 ef->ddbstrtab = ef->strbase; 685 686 lf->flags |= LINKER_FILE_LINKED; 687 688 nosyms: 689 690 *result = lf; 691 692 out: 693 if (error && lf) 694 linker_file_unload(lf); 695 if (shdr) 696 free(shdr, M_LINKER); 697 if (firstpage) 698 free(firstpage, M_LINKER); 699 VOP_UNLOCK(nd.ni_vp, NULL, 0, td); 700 vn_close(nd.ni_vp, FREAD, td); 701 702 return error; 703 } 704 705 static void 706 link_elf_unload_file(linker_file_t file) 707 { 708 elf_file_t ef = file->priv; 709 710 if (ef) { 711 #ifdef SPARSE_MAPPING 712 if (ef->object) { 713 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 714 (vm_offset_t) ef->address 715 + (ef->object->size << PAGE_SHIFT)); 716 vm_object_deallocate(ef->object); 717 } 718 #else 719 if (ef->address) 720 free(ef->address, M_LINKER); 721 #endif 722 if (ef->symbase) 723 free(ef->symbase, M_LINKER); 724 if (ef->strbase) 725 free(ef->strbase, M_LINKER); 726 free(ef, M_LINKER); 727 } 728 } 729 730 static void 731 link_elf_unload_module(linker_file_t file) 732 { 733 elf_file_t ef = file->priv; 734 735 if (ef) 736 free(ef, M_LINKER); 737 if (file->filename) 738 preload_delete_name(file->filename); 739 } 740 741 static int 742 load_dependancies(linker_file_t lf) 743 { 744 elf_file_t ef = lf->priv; 745 linker_file_t lfdep; 746 char* name; 747 const Elf_Dyn *dp; 748 int error = 0; 749 750 /* 751 * All files are dependant on /kernel. 752 */ 753 if (linker_kernel_file) { 754 linker_kernel_file->refs++; 755 linker_file_add_dependancy(lf, linker_kernel_file); 756 } 757 758 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 759 if (dp->d_tag == DT_NEEDED) { 760 name = ef->strtab + dp->d_un.d_val; 761 762 error = linker_load_file(name, &lfdep); 763 if (error) 764 goto out; 765 error = linker_file_add_dependancy(lf, lfdep); 766 if (error) 767 goto out; 768 } 769 } 770 771 out: 772 return error; 773 } 774 775 static const char * 776 symbol_name(elf_file_t ef, Elf_Word r_info) 777 { 778 const Elf_Sym *ref; 779 780 if (ELF_R_SYM(r_info)) { 781 ref = ef->symtab + ELF_R_SYM(r_info); 782 return ef->strtab + ref->st_name; 783 } else 784 return NULL; 785 } 786 787 static int 788 relocate_file(linker_file_t lf) 789 { 790 elf_file_t ef = lf->priv; 791 const Elf_Rel *rellim; 792 const Elf_Rel *rel; 793 const Elf_Rela *relalim; 794 const Elf_Rela *rela; 795 const char *symname; 796 797 /* Perform relocations without addend if there are any: */ 798 rel = ef->rel; 799 if (rel) { 800 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 801 while (rel < rellim) { 802 symname = symbol_name(ef, rel->r_info); 803 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 804 printf("link_elf: symbol %s undefined\n", symname); 805 return ENOENT; 806 } 807 rel++; 808 } 809 } 810 811 /* Perform relocations with addend if there are any: */ 812 rela = ef->rela; 813 if (rela) { 814 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 815 while (rela < relalim) { 816 symname = symbol_name(ef, rela->r_info); 817 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 818 printf("link_elf: symbol %s undefined\n", symname); 819 return ENOENT; 820 } 821 rela++; 822 } 823 } 824 825 /* Perform PLT relocations without addend if there are any: */ 826 rel = ef->pltrel; 827 if (rel) { 828 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 829 while (rel < rellim) { 830 symname = symbol_name(ef, rel->r_info); 831 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 832 printf("link_elf: symbol %s undefined\n", symname); 833 return ENOENT; 834 } 835 rel++; 836 } 837 } 838 839 /* Perform relocations with addend if there are any: */ 840 rela = ef->pltrela; 841 if (rela) { 842 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 843 while (rela < relalim) { 844 symname = symbol_name(ef, rela->r_info); 845 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 846 printf("link_elf: symbol %s undefined\n", symname); 847 return ENOENT; 848 } 849 rela++; 850 } 851 } 852 853 return 0; 854 } 855 856 /* 857 * Hash function for symbol table lookup. Don't even think about changing 858 * this. It is specified by the System V ABI. 859 */ 860 static unsigned long 861 elf_hash(const char *name) 862 { 863 const unsigned char *p = (const unsigned char *) name; 864 unsigned long h = 0; 865 unsigned long g; 866 867 while (*p != '\0') { 868 h = (h << 4) + *p++; 869 if ((g = h & 0xf0000000) != 0) 870 h ^= g >> 24; 871 h &= ~g; 872 } 873 return h; 874 } 875 876 int 877 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 878 { 879 elf_file_t ef = lf->priv; 880 unsigned long symnum; 881 const Elf_Sym* symp; 882 const char *strp; 883 unsigned long hash; 884 int i; 885 886 /* First, search hashed global symbols */ 887 hash = elf_hash(name); 888 symnum = ef->buckets[hash % ef->nbuckets]; 889 890 while (symnum != STN_UNDEF) { 891 if (symnum >= ef->nchains) { 892 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 893 return ENOENT; 894 } 895 896 symp = ef->symtab + symnum; 897 if (symp->st_name == 0) { 898 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 899 return ENOENT; 900 } 901 902 strp = ef->strtab + symp->st_name; 903 904 if (strcmp(name, strp) == 0) { 905 if (symp->st_shndx != SHN_UNDEF || 906 (symp->st_value != 0 && 907 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 908 ) { 909 *sym = (c_linker_sym_t) symp; 910 return 0; 911 } else { 912 return ENOENT; 913 } 914 } 915 916 symnum = ef->chains[symnum]; 917 } 918 919 /* If we have not found it, look at the full table (if loaded) */ 920 if (ef->symtab == ef->ddbsymtab) 921 return ENOENT; 922 923 /* Exhaustive search */ 924 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 925 strp = ef->ddbstrtab + symp->st_name; 926 if (strcmp(name, strp) == 0) { 927 if (symp->st_shndx != SHN_UNDEF || 928 (symp->st_value != 0 && 929 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 930 *sym = (c_linker_sym_t) symp; 931 return 0; 932 } else { 933 return ENOENT; 934 } 935 } 936 } 937 return ENOENT; 938 } 939 940 static int 941 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 942 { 943 elf_file_t ef = lf->priv; 944 const Elf_Sym* es = (const Elf_Sym*) sym; 945 946 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 947 symval->name = ef->strtab + es->st_name; 948 symval->value = (caddr_t) ef->address + es->st_value; 949 symval->size = es->st_size; 950 return 0; 951 } 952 if (ef->symtab == ef->ddbsymtab) 953 return ENOENT; 954 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 955 symval->name = ef->ddbstrtab + es->st_name; 956 symval->value = (caddr_t) ef->address + es->st_value; 957 symval->size = es->st_size; 958 return 0; 959 } 960 return ENOENT; 961 } 962 963 static int 964 link_elf_search_symbol(linker_file_t lf, caddr_t value, 965 c_linker_sym_t* sym, long* diffp) 966 { 967 elf_file_t ef = lf->priv; 968 u_long off = (uintptr_t) (void *) value; 969 u_long diff = off; 970 u_long st_value; 971 const Elf_Sym* es; 972 const Elf_Sym* best = 0; 973 int i; 974 975 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 976 if (es->st_name == 0) 977 continue; 978 st_value = es->st_value + (uintptr_t) (void *) ef->address; 979 if (off >= st_value) { 980 if (off - st_value < diff) { 981 diff = off - st_value; 982 best = es; 983 if (diff == 0) 984 break; 985 } else if (off - st_value == diff) { 986 best = es; 987 } 988 } 989 } 990 if (best == 0) 991 *diffp = off; 992 else 993 *diffp = diff; 994 *sym = (c_linker_sym_t) best; 995 996 return 0; 997 } 998 999 /* 1000 * Look up a linker set on an ELF system. 1001 */ 1002 static int 1003 link_elf_lookup_set(linker_file_t lf, const char *name, 1004 void ***startp, void ***stopp, int *countp) 1005 { 1006 c_linker_sym_t sym; 1007 linker_symval_t symval; 1008 char *setsym; 1009 void **start, **stop; 1010 int len, error = 0, count; 1011 1012 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1013 setsym = malloc(len, M_LINKER, M_WAITOK); 1014 if (setsym == NULL) 1015 return ENOMEM; 1016 1017 /* get address of first entry */ 1018 snprintf(setsym, len, "%s%s", "__start_set_", name); 1019 error = link_elf_lookup_symbol(lf, setsym, &sym); 1020 if (error) 1021 goto out; 1022 link_elf_symbol_values(lf, sym, &symval); 1023 if (symval.value == 0) { 1024 error = ESRCH; 1025 goto out; 1026 } 1027 start = (void **)symval.value; 1028 1029 /* get address of last entry */ 1030 snprintf(setsym, len, "%s%s", "__stop_set_", name); 1031 error = link_elf_lookup_symbol(lf, setsym, &sym); 1032 if (error) 1033 goto out; 1034 link_elf_symbol_values(lf, sym, &symval); 1035 if (symval.value == 0) { 1036 error = ESRCH; 1037 goto out; 1038 } 1039 stop = (void **)symval.value; 1040 1041 /* and the number of entries */ 1042 count = stop - start; 1043 1044 /* and copy out */ 1045 if (startp) 1046 *startp = start; 1047 if (stopp) 1048 *stopp = stop; 1049 if (countp) 1050 *countp = count; 1051 1052 out: 1053 free(setsym, M_LINKER); 1054 return error; 1055 } 1056 1057