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 1.10 2003/11/20 22:07:33 dillon 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 #ifdef __ELF__ 132 Elf_Dyn *dp; 133 caddr_t modptr, baseptr, sizeptr; 134 elf_file_t ef; 135 char *modname; 136 #endif 137 138 #if ELF_TARG_CLASS == ELFCLASS32 139 linker_add_class("elf32", NULL, &link_elf_class_ops); 140 #else 141 linker_add_class("elf64", NULL, &link_elf_class_ops); 142 #endif 143 144 #ifdef __ELF__ 145 dp = (Elf_Dyn*) &_DYNAMIC; 146 if (dp) { 147 ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT); 148 if (ef == NULL) 149 panic("link_elf_init: Can't create linker structures for kernel"); 150 bzero(ef, sizeof(*ef)); 151 152 ef->address = 0; 153 #ifdef SPARSE_MAPPING 154 ef->object = 0; 155 #endif 156 ef->dynamic = dp; 157 modname = NULL; 158 modptr = preload_search_by_type("elf kernel"); 159 if (modptr) 160 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 161 if (modname == NULL) 162 modname = "kernel"; 163 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 164 if (linker_kernel_file == NULL) 165 panic("link_elf_init: Can't create linker structures for kernel"); 166 parse_dynamic(linker_kernel_file); 167 linker_kernel_file->address = (caddr_t) KERNBASE; 168 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 169 170 if (modptr) { 171 ef->modptr = modptr; 172 baseptr = preload_search_info(modptr, MODINFO_ADDR); 173 if (baseptr) 174 linker_kernel_file->address = *(caddr_t *)baseptr; 175 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 176 if (sizeptr) 177 linker_kernel_file->size = *(size_t *)sizeptr; 178 } 179 (void)parse_module_symbols(linker_kernel_file); 180 linker_current_file = linker_kernel_file; 181 linker_kernel_file->flags |= LINKER_FILE_LINKED; 182 } 183 #endif 184 } 185 186 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 187 188 static int 189 parse_module_symbols(linker_file_t lf) 190 { 191 elf_file_t ef = lf->priv; 192 caddr_t pointer; 193 caddr_t ssym, esym, base; 194 caddr_t strtab; 195 int strcnt; 196 Elf_Sym* symtab; 197 int symcnt; 198 199 if (ef->modptr == NULL) 200 return 0; 201 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 202 if (pointer == NULL) 203 return 0; 204 ssym = *(caddr_t *)pointer; 205 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 206 if (pointer == NULL) 207 return 0; 208 esym = *(caddr_t *)pointer; 209 210 base = ssym; 211 212 symcnt = *(long *)base; 213 base += sizeof(long); 214 symtab = (Elf_Sym *)base; 215 base += roundup(symcnt, sizeof(long)); 216 217 if (base > esym || base < ssym) { 218 printf("Symbols are corrupt!\n"); 219 return EINVAL; 220 } 221 222 strcnt = *(long *)base; 223 base += sizeof(long); 224 strtab = base; 225 base += roundup(strcnt, sizeof(long)); 226 227 if (base > esym || base < ssym) { 228 printf("Symbols are corrupt!\n"); 229 return EINVAL; 230 } 231 232 ef->ddbsymtab = symtab; 233 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 234 ef->ddbstrtab = strtab; 235 ef->ddbstrcnt = strcnt; 236 237 return 0; 238 } 239 240 static int 241 parse_dynamic(linker_file_t lf) 242 { 243 elf_file_t ef = lf->priv; 244 const Elf_Dyn *dp; 245 int plttype = DT_REL; 246 247 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 248 switch (dp->d_tag) { 249 case DT_HASH: 250 { 251 /* From src/libexec/rtld-elf/rtld.c */ 252 const Elf_Off *hashtab = (const Elf_Off *) 253 (ef->address + dp->d_un.d_ptr); 254 ef->nbuckets = hashtab[0]; 255 ef->nchains = hashtab[1]; 256 ef->buckets = hashtab + 2; 257 ef->chains = ef->buckets + ef->nbuckets; 258 break; 259 } 260 case DT_STRTAB: 261 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 262 break; 263 case DT_STRSZ: 264 ef->strsz = dp->d_un.d_val; 265 break; 266 case DT_SYMTAB: 267 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 268 break; 269 case DT_SYMENT: 270 if (dp->d_un.d_val != sizeof(Elf_Sym)) 271 return ENOEXEC; 272 break; 273 case DT_PLTGOT: 274 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 275 break; 276 case DT_REL: 277 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 278 break; 279 case DT_RELSZ: 280 ef->relsize = dp->d_un.d_val; 281 break; 282 case DT_RELENT: 283 if (dp->d_un.d_val != sizeof(Elf_Rel)) 284 return ENOEXEC; 285 break; 286 case DT_JMPREL: 287 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 288 break; 289 case DT_PLTRELSZ: 290 ef->pltrelsize = dp->d_un.d_val; 291 break; 292 case DT_RELA: 293 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 294 break; 295 case DT_RELASZ: 296 ef->relasize = dp->d_un.d_val; 297 break; 298 case DT_RELAENT: 299 if (dp->d_un.d_val != sizeof(Elf_Rela)) 300 return ENOEXEC; 301 break; 302 case DT_PLTREL: 303 plttype = dp->d_un.d_val; 304 if (plttype != DT_REL && plttype != DT_RELA) 305 return ENOEXEC; 306 break; 307 } 308 } 309 310 if (plttype == DT_RELA) { 311 ef->pltrela = (const Elf_Rela *) ef->pltrel; 312 ef->pltrel = NULL; 313 ef->pltrelasize = ef->pltrelsize; 314 ef->pltrelsize = 0; 315 } 316 317 ef->ddbsymtab = ef->symtab; 318 ef->ddbsymcnt = ef->nchains; 319 ef->ddbstrtab = ef->strtab; 320 ef->ddbstrcnt = ef->strsz; 321 322 return 0; 323 } 324 325 static void 326 link_elf_error(const char *s) 327 { 328 printf("kldload: %s\n", s); 329 } 330 331 static int 332 link_elf_load_module(const char *filename, linker_file_t *result) 333 { 334 caddr_t modptr, baseptr, sizeptr, dynptr; 335 char *type; 336 elf_file_t ef; 337 linker_file_t lf; 338 int error; 339 vm_offset_t dp; 340 341 /* 342 * Look to see if we have the module preloaded. 343 */ 344 modptr = preload_search_by_name(filename); 345 if (modptr == NULL) 346 return (link_elf_load_file(filename, result)); 347 348 /* It's preloaded, check we can handle it and collect information */ 349 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 350 baseptr = preload_search_info(modptr, MODINFO_ADDR); 351 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 352 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 353 if (type == NULL || strcmp(type, "elf module") != 0) 354 return (EFTYPE); 355 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 356 return (EINVAL); 357 358 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 359 if (ef == NULL) 360 return (ENOMEM); 361 bzero(ef, sizeof(*ef)); 362 ef->modptr = modptr; 363 ef->address = *(caddr_t *)baseptr; 364 #ifdef SPARSE_MAPPING 365 ef->object = 0; 366 #endif 367 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 368 ef->dynamic = (Elf_Dyn *)dp; 369 lf = linker_make_file(filename, ef, &link_elf_module_ops); 370 if (lf == NULL) { 371 free(ef, M_LINKER); 372 return ENOMEM; 373 } 374 lf->address = ef->address; 375 lf->size = *(size_t *)sizeptr; 376 377 error = parse_dynamic(lf); 378 if (error) { 379 linker_file_unload(lf); 380 return error; 381 } 382 error = load_dependancies(lf); 383 if (error) { 384 linker_file_unload(lf); 385 return error; 386 } 387 error = relocate_file(lf); 388 if (error) { 389 linker_file_unload(lf); 390 return error; 391 } 392 (void)parse_module_symbols(lf); 393 lf->flags |= LINKER_FILE_LINKED; 394 *result = lf; 395 return (0); 396 } 397 398 static int 399 link_elf_load_file(const char* filename, linker_file_t* result) 400 { 401 struct nameidata nd; 402 struct thread *td = curthread; /* XXX */ 403 struct proc *p = td->td_proc; 404 Elf_Ehdr *hdr; 405 caddr_t firstpage; 406 int nbytes, i; 407 Elf_Phdr *phdr; 408 Elf_Phdr *phlimit; 409 Elf_Phdr *segs[2]; 410 int nsegs; 411 Elf_Phdr *phdyn; 412 Elf_Phdr *phphdr; 413 caddr_t mapbase; 414 size_t mapsize; 415 Elf_Off base_offset; 416 Elf_Addr base_vaddr; 417 Elf_Addr base_vlimit; 418 int error = 0; 419 int resid; 420 elf_file_t ef; 421 linker_file_t lf; 422 char *pathname; 423 Elf_Shdr *shdr; 424 int symtabindex; 425 int symstrindex; 426 int symcnt; 427 int strcnt; 428 429 KKASSERT(p != NULL); 430 if (p->p_ucred == NULL) { 431 printf("link_elf_load_file: cannot load '%s' from filesystem" 432 " this early\n", filename); 433 return ENOENT; 434 } 435 shdr = NULL; 436 lf = NULL; 437 pathname = linker_search_path(filename); 438 if (pathname == NULL) 439 return ENOENT; 440 441 NDINIT(&nd, NAMEI_LOOKUP, CNP_FOLLOW, UIO_SYSSPACE, pathname, td); 442 error = vn_open(&nd, FREAD, 0); 443 free(pathname, M_LINKER); 444 if (error) 445 return error; 446 NDFREE(&nd, NDF_ONLY_PNBUF); 447 448 /* 449 * Read the elf header from the file. 450 */ 451 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK); 452 if (firstpage == NULL) { 453 error = ENOMEM; 454 goto out; 455 } 456 hdr = (Elf_Ehdr *)firstpage; 457 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0, 458 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 459 nbytes = PAGE_SIZE - resid; 460 if (error) 461 goto out; 462 463 if (!IS_ELF(*hdr)) { 464 error = ENOEXEC; 465 goto out; 466 } 467 468 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 469 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 470 link_elf_error("Unsupported file layout"); 471 error = ENOEXEC; 472 goto out; 473 } 474 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 475 || hdr->e_version != EV_CURRENT) { 476 link_elf_error("Unsupported file version"); 477 error = ENOEXEC; 478 goto out; 479 } 480 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 481 link_elf_error("Unsupported file type"); 482 error = ENOEXEC; 483 goto out; 484 } 485 if (hdr->e_machine != ELF_TARG_MACH) { 486 link_elf_error("Unsupported machine"); 487 error = ENOEXEC; 488 goto out; 489 } 490 491 /* 492 * We rely on the program header being in the first page. This is 493 * not strictly required by the ABI specification, but it seems to 494 * always true in practice. And, it simplifies things considerably. 495 */ 496 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 497 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 498 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 499 link_elf_error("Unreadable program headers"); 500 501 /* 502 * Scan the program header entries, and save key information. 503 * 504 * We rely on there being exactly two load segments, text and data, 505 * in that order. 506 */ 507 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 508 phlimit = phdr + hdr->e_phnum; 509 nsegs = 0; 510 phdyn = NULL; 511 phphdr = NULL; 512 while (phdr < phlimit) { 513 switch (phdr->p_type) { 514 515 case PT_LOAD: 516 if (nsegs == 2) { 517 link_elf_error("Too many sections"); 518 error = ENOEXEC; 519 goto out; 520 } 521 segs[nsegs] = phdr; 522 ++nsegs; 523 break; 524 525 case PT_PHDR: 526 phphdr = phdr; 527 break; 528 529 case PT_DYNAMIC: 530 phdyn = phdr; 531 break; 532 } 533 534 ++phdr; 535 } 536 if (phdyn == NULL) { 537 link_elf_error("Object is not dynamically-linked"); 538 error = ENOEXEC; 539 goto out; 540 } 541 542 /* 543 * Allocate the entire address space of the object, to stake out our 544 * contiguous region, and to establish the base address for relocation. 545 */ 546 base_offset = trunc_page(segs[0]->p_offset); 547 base_vaddr = trunc_page(segs[0]->p_vaddr); 548 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 549 mapsize = base_vlimit - base_vaddr; 550 551 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 552 bzero(ef, sizeof(*ef)); 553 #ifdef SPARSE_MAPPING 554 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 555 if (ef->object == NULL) { 556 free(ef, M_LINKER); 557 error = ENOMEM; 558 goto out; 559 } 560 vm_object_reference(ef->object); 561 ef->address = (caddr_t) vm_map_min(kernel_map); 562 error = vm_map_find(kernel_map, ef->object, 0, 563 (vm_offset_t *) &ef->address, 564 mapsize, 1, 565 VM_PROT_ALL, VM_PROT_ALL, 0); 566 if (error) { 567 vm_object_deallocate(ef->object); 568 free(ef, M_LINKER); 569 goto out; 570 } 571 #else 572 ef->address = malloc(mapsize, M_LINKER, M_WAITOK); 573 #endif 574 mapbase = ef->address; 575 576 /* 577 * Read the text and data sections and zero the bss. 578 */ 579 for (i = 0; i < 2; i++) { 580 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 581 error = vn_rdwr(UIO_READ, nd.ni_vp, 582 segbase, segs[i]->p_filesz, segs[i]->p_offset, 583 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 584 if (error) { 585 #ifdef SPARSE_MAPPING 586 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 587 (vm_offset_t) ef->address 588 + (ef->object->size << PAGE_SHIFT)); 589 vm_object_deallocate(ef->object); 590 #else 591 free(ef->address, M_LINKER); 592 #endif 593 free(ef, M_LINKER); 594 goto out; 595 } 596 bzero(segbase + segs[i]->p_filesz, 597 segs[i]->p_memsz - segs[i]->p_filesz); 598 599 #ifdef SPARSE_MAPPING 600 /* 601 * Wire down the pages 602 */ 603 vm_map_wire(kernel_map, 604 (vm_offset_t) segbase, 605 (vm_offset_t) segbase + segs[i]->p_memsz, 606 FALSE); 607 #endif 608 } 609 610 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 611 612 lf = linker_make_file(filename, ef, &link_elf_file_ops); 613 if (lf == NULL) { 614 #ifdef SPARSE_MAPPING 615 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 616 (vm_offset_t) ef->address 617 + (ef->object->size << PAGE_SHIFT)); 618 vm_object_deallocate(ef->object); 619 #else 620 free(ef->address, M_LINKER); 621 #endif 622 free(ef, M_LINKER); 623 error = ENOMEM; 624 goto out; 625 } 626 lf->address = ef->address; 627 lf->size = mapsize; 628 629 error = parse_dynamic(lf); 630 if (error) 631 goto out; 632 error = load_dependancies(lf); 633 if (error) 634 goto out; 635 error = relocate_file(lf); 636 if (error) 637 goto out; 638 639 /* Try and load the symbol table if it's present. (you can strip it!) */ 640 nbytes = hdr->e_shnum * hdr->e_shentsize; 641 if (nbytes == 0 || hdr->e_shoff == 0) 642 goto nosyms; 643 shdr = malloc(nbytes, M_LINKER, M_WAITOK); 644 if (shdr == NULL) { 645 error = ENOMEM; 646 goto out; 647 } 648 bzero(shdr, nbytes); 649 error = vn_rdwr(UIO_READ, nd.ni_vp, 650 (caddr_t)shdr, nbytes, hdr->e_shoff, 651 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 652 if (error) 653 goto out; 654 symtabindex = -1; 655 symstrindex = -1; 656 for (i = 0; i < hdr->e_shnum; i++) { 657 if (shdr[i].sh_type == SHT_SYMTAB) { 658 symtabindex = i; 659 symstrindex = shdr[i].sh_link; 660 } 661 } 662 if (symtabindex < 0 || symstrindex < 0) 663 goto nosyms; 664 665 symcnt = shdr[symtabindex].sh_size; 666 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK); 667 strcnt = shdr[symstrindex].sh_size; 668 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK); 669 670 if (ef->symbase == NULL || ef->strbase == NULL) { 671 error = ENOMEM; 672 goto out; 673 } 674 error = vn_rdwr(UIO_READ, nd.ni_vp, 675 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 676 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 677 if (error) 678 goto out; 679 error = vn_rdwr(UIO_READ, nd.ni_vp, 680 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 681 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td); 682 if (error) 683 goto out; 684 685 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 686 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 687 ef->ddbstrcnt = strcnt; 688 ef->ddbstrtab = ef->strbase; 689 690 lf->flags |= LINKER_FILE_LINKED; 691 692 nosyms: 693 694 *result = lf; 695 696 out: 697 if (error && lf) 698 linker_file_unload(lf); 699 if (shdr) 700 free(shdr, M_LINKER); 701 if (firstpage) 702 free(firstpage, M_LINKER); 703 VOP_UNLOCK(nd.ni_vp, 0, td); 704 vn_close(nd.ni_vp, FREAD, td); 705 706 return error; 707 } 708 709 static void 710 link_elf_unload_file(linker_file_t file) 711 { 712 elf_file_t ef = file->priv; 713 714 if (ef) { 715 #ifdef SPARSE_MAPPING 716 if (ef->object) { 717 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 718 (vm_offset_t) ef->address 719 + (ef->object->size << PAGE_SHIFT)); 720 vm_object_deallocate(ef->object); 721 } 722 #else 723 if (ef->address) 724 free(ef->address, M_LINKER); 725 #endif 726 if (ef->symbase) 727 free(ef->symbase, M_LINKER); 728 if (ef->strbase) 729 free(ef->strbase, M_LINKER); 730 free(ef, M_LINKER); 731 } 732 } 733 734 static void 735 link_elf_unload_module(linker_file_t file) 736 { 737 elf_file_t ef = file->priv; 738 739 if (ef) 740 free(ef, M_LINKER); 741 if (file->filename) 742 preload_delete_name(file->filename); 743 } 744 745 static int 746 load_dependancies(linker_file_t lf) 747 { 748 elf_file_t ef = lf->priv; 749 linker_file_t lfdep; 750 char* name; 751 const Elf_Dyn *dp; 752 int error = 0; 753 754 /* 755 * All files are dependant on /kernel. 756 */ 757 if (linker_kernel_file) { 758 linker_kernel_file->refs++; 759 linker_file_add_dependancy(lf, linker_kernel_file); 760 } 761 762 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 763 if (dp->d_tag == DT_NEEDED) { 764 name = ef->strtab + dp->d_un.d_val; 765 766 error = linker_load_file(name, &lfdep); 767 if (error) 768 goto out; 769 error = linker_file_add_dependancy(lf, lfdep); 770 if (error) 771 goto out; 772 } 773 } 774 775 out: 776 return error; 777 } 778 779 static const char * 780 symbol_name(elf_file_t ef, Elf_Word r_info) 781 { 782 const Elf_Sym *ref; 783 784 if (ELF_R_SYM(r_info)) { 785 ref = ef->symtab + ELF_R_SYM(r_info); 786 return ef->strtab + ref->st_name; 787 } else 788 return NULL; 789 } 790 791 static int 792 relocate_file(linker_file_t lf) 793 { 794 elf_file_t ef = lf->priv; 795 const Elf_Rel *rellim; 796 const Elf_Rel *rel; 797 const Elf_Rela *relalim; 798 const Elf_Rela *rela; 799 const char *symname; 800 801 /* Perform relocations without addend if there are any: */ 802 rel = ef->rel; 803 if (rel) { 804 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 805 while (rel < rellim) { 806 symname = symbol_name(ef, rel->r_info); 807 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 808 printf("link_elf: symbol %s undefined\n", symname); 809 return ENOENT; 810 } 811 rel++; 812 } 813 } 814 815 /* Perform relocations with addend if there are any: */ 816 rela = ef->rela; 817 if (rela) { 818 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 819 while (rela < relalim) { 820 symname = symbol_name(ef, rela->r_info); 821 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 822 printf("link_elf: symbol %s undefined\n", symname); 823 return ENOENT; 824 } 825 rela++; 826 } 827 } 828 829 /* Perform PLT relocations without addend if there are any: */ 830 rel = ef->pltrel; 831 if (rel) { 832 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 833 while (rel < rellim) { 834 symname = symbol_name(ef, rel->r_info); 835 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 836 printf("link_elf: symbol %s undefined\n", symname); 837 return ENOENT; 838 } 839 rel++; 840 } 841 } 842 843 /* Perform relocations with addend if there are any: */ 844 rela = ef->pltrela; 845 if (rela) { 846 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 847 while (rela < relalim) { 848 symname = symbol_name(ef, rela->r_info); 849 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 850 printf("link_elf: symbol %s undefined\n", symname); 851 return ENOENT; 852 } 853 rela++; 854 } 855 } 856 857 return 0; 858 } 859 860 /* 861 * Hash function for symbol table lookup. Don't even think about changing 862 * this. It is specified by the System V ABI. 863 */ 864 static unsigned long 865 elf_hash(const char *name) 866 { 867 const unsigned char *p = (const unsigned char *) name; 868 unsigned long h = 0; 869 unsigned long g; 870 871 while (*p != '\0') { 872 h = (h << 4) + *p++; 873 if ((g = h & 0xf0000000) != 0) 874 h ^= g >> 24; 875 h &= ~g; 876 } 877 return h; 878 } 879 880 int 881 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 882 { 883 elf_file_t ef = lf->priv; 884 unsigned long symnum; 885 const Elf_Sym* symp; 886 const char *strp; 887 unsigned long hash; 888 int i; 889 890 /* First, search hashed global symbols */ 891 hash = elf_hash(name); 892 symnum = ef->buckets[hash % ef->nbuckets]; 893 894 while (symnum != STN_UNDEF) { 895 if (symnum >= ef->nchains) { 896 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 897 return ENOENT; 898 } 899 900 symp = ef->symtab + symnum; 901 if (symp->st_name == 0) { 902 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 903 return ENOENT; 904 } 905 906 strp = ef->strtab + symp->st_name; 907 908 if (strcmp(name, strp) == 0) { 909 if (symp->st_shndx != SHN_UNDEF || 910 (symp->st_value != 0 && 911 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 912 ) { 913 *sym = (c_linker_sym_t) symp; 914 return 0; 915 } else { 916 return ENOENT; 917 } 918 } 919 920 symnum = ef->chains[symnum]; 921 } 922 923 /* If we have not found it, look at the full table (if loaded) */ 924 if (ef->symtab == ef->ddbsymtab) 925 return ENOENT; 926 927 /* Exhaustive search */ 928 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 929 strp = ef->ddbstrtab + symp->st_name; 930 if (strcmp(name, strp) == 0) { 931 if (symp->st_shndx != SHN_UNDEF || 932 (symp->st_value != 0 && 933 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 934 *sym = (c_linker_sym_t) symp; 935 return 0; 936 } else { 937 return ENOENT; 938 } 939 } 940 } 941 return ENOENT; 942 } 943 944 static int 945 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 946 { 947 elf_file_t ef = lf->priv; 948 const Elf_Sym* es = (const Elf_Sym*) sym; 949 950 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 951 symval->name = ef->strtab + es->st_name; 952 symval->value = (caddr_t) ef->address + es->st_value; 953 symval->size = es->st_size; 954 return 0; 955 } 956 if (ef->symtab == ef->ddbsymtab) 957 return ENOENT; 958 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 959 symval->name = ef->ddbstrtab + es->st_name; 960 symval->value = (caddr_t) ef->address + es->st_value; 961 symval->size = es->st_size; 962 return 0; 963 } 964 return ENOENT; 965 } 966 967 static int 968 link_elf_search_symbol(linker_file_t lf, caddr_t value, 969 c_linker_sym_t* sym, long* diffp) 970 { 971 elf_file_t ef = lf->priv; 972 u_long off = (uintptr_t) (void *) value; 973 u_long diff = off; 974 u_long st_value; 975 const Elf_Sym* es; 976 const Elf_Sym* best = 0; 977 int i; 978 979 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 980 if (es->st_name == 0) 981 continue; 982 st_value = es->st_value + (uintptr_t) (void *) ef->address; 983 if (off >= st_value) { 984 if (off - st_value < diff) { 985 diff = off - st_value; 986 best = es; 987 if (diff == 0) 988 break; 989 } else if (off - st_value == diff) { 990 best = es; 991 } 992 } 993 } 994 if (best == 0) 995 *diffp = off; 996 else 997 *diffp = diff; 998 *sym = (c_linker_sym_t) best; 999 1000 return 0; 1001 } 1002 1003 /* 1004 * Look up a linker set on an ELF system. 1005 */ 1006 static int 1007 link_elf_lookup_set(linker_file_t lf, const char *name, 1008 void ***startp, void ***stopp, int *countp) 1009 { 1010 c_linker_sym_t sym; 1011 linker_symval_t symval; 1012 char *setsym; 1013 void **start, **stop; 1014 int len, error = 0, count; 1015 1016 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1017 setsym = malloc(len, M_LINKER, M_WAITOK); 1018 if (setsym == NULL) 1019 return ENOMEM; 1020 1021 /* get address of first entry */ 1022 snprintf(setsym, len, "%s%s", "__start_set_", name); 1023 error = link_elf_lookup_symbol(lf, setsym, &sym); 1024 if (error) 1025 goto out; 1026 link_elf_symbol_values(lf, sym, &symval); 1027 if (symval.value == 0) { 1028 error = ESRCH; 1029 goto out; 1030 } 1031 start = (void **)symval.value; 1032 1033 /* get address of last entry */ 1034 snprintf(setsym, len, "%s%s", "__stop_set_", name); 1035 error = link_elf_lookup_symbol(lf, setsym, &sym); 1036 if (error) 1037 goto out; 1038 link_elf_symbol_values(lf, sym, &symval); 1039 if (symval.value == 0) { 1040 error = ESRCH; 1041 goto out; 1042 } 1043 stop = (void **)symval.value; 1044 1045 /* and the number of entries */ 1046 count = stop - start; 1047 1048 /* and copy out */ 1049 if (startp) 1050 *startp = start; 1051 if (stopp) 1052 *stopp = stop; 1053 if (countp) 1054 *countp = count; 1055 1056 out: 1057 free(setsym, M_LINKER); 1058 return error; 1059 } 1060 1061