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 1.25 2006/12/28 21:24:01 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/nlookup.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 static struct linker_class_ops link_elf_class_ops = { 67 link_elf_load_module, 68 }; 69 70 static struct linker_file_ops link_elf_file_ops = { 71 link_elf_lookup_symbol, 72 link_elf_symbol_values, 73 link_elf_search_symbol, 74 link_elf_unload_file, 75 link_elf_lookup_set 76 }; 77 78 static struct linker_file_ops link_elf_module_ops = { 79 link_elf_lookup_symbol, 80 link_elf_symbol_values, 81 link_elf_search_symbol, 82 link_elf_unload_module, 83 link_elf_lookup_set 84 }; 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 = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO); 145 ef->address = 0; 146 #ifdef SPARSE_MAPPING 147 ef->object = 0; 148 #endif 149 ef->dynamic = dp; 150 modname = NULL; 151 modptr = preload_search_by_type("elf kernel"); 152 if (modptr) 153 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 154 if (modname == NULL) 155 modname = "kernel"; 156 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 157 if (linker_kernel_file == NULL) 158 panic("link_elf_init: Can't create linker structures for kernel"); 159 parse_dynamic(linker_kernel_file); 160 linker_kernel_file->address = (caddr_t) KERNBASE; 161 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 162 163 if (modptr) { 164 ef->modptr = modptr; 165 baseptr = preload_search_info(modptr, MODINFO_ADDR); 166 if (baseptr) 167 linker_kernel_file->address = *(caddr_t *)baseptr; 168 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 169 if (sizeptr) 170 linker_kernel_file->size = *(size_t *)sizeptr; 171 } 172 parse_module_symbols(linker_kernel_file); 173 linker_current_file = linker_kernel_file; 174 linker_kernel_file->flags |= LINKER_FILE_LINKED; 175 } 176 } 177 178 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 179 180 static int 181 parse_module_symbols(linker_file_t lf) 182 { 183 elf_file_t ef = lf->priv; 184 caddr_t pointer; 185 caddr_t ssym, esym, base; 186 caddr_t strtab; 187 int strcnt; 188 Elf_Sym* symtab; 189 int symcnt; 190 191 if (ef->modptr == NULL) 192 return 0; 193 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 194 if (pointer == NULL) 195 return 0; 196 ssym = *(caddr_t *)pointer; 197 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 198 if (pointer == NULL) 199 return 0; 200 esym = *(caddr_t *)pointer; 201 202 base = ssym; 203 204 symcnt = *(long *)base; 205 base += sizeof(long); 206 symtab = (Elf_Sym *)base; 207 base += roundup(symcnt, sizeof(long)); 208 209 if (base > esym || base < ssym) { 210 kprintf("Symbols are corrupt!\n"); 211 return EINVAL; 212 } 213 214 strcnt = *(long *)base; 215 base += sizeof(long); 216 strtab = base; 217 base += roundup(strcnt, sizeof(long)); 218 219 if (base > esym || base < ssym) { 220 kprintf("Symbols are corrupt!\n"); 221 return EINVAL; 222 } 223 224 ef->ddbsymtab = symtab; 225 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 226 ef->ddbstrtab = strtab; 227 ef->ddbstrcnt = strcnt; 228 229 return 0; 230 } 231 232 static int 233 parse_dynamic(linker_file_t lf) 234 { 235 elf_file_t ef = lf->priv; 236 const Elf_Dyn *dp; 237 int plttype = DT_REL; 238 239 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 240 switch (dp->d_tag) { 241 case DT_HASH: 242 { 243 /* From src/libexec/rtld-elf/rtld.c */ 244 const Elf_Off *hashtab = (const Elf_Off *) 245 (ef->address + dp->d_un.d_ptr); 246 ef->nbuckets = hashtab[0]; 247 ef->nchains = hashtab[1]; 248 ef->buckets = hashtab + 2; 249 ef->chains = ef->buckets + ef->nbuckets; 250 break; 251 } 252 case DT_STRTAB: 253 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 254 break; 255 case DT_STRSZ: 256 ef->strsz = dp->d_un.d_val; 257 break; 258 case DT_SYMTAB: 259 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 260 break; 261 case DT_SYMENT: 262 if (dp->d_un.d_val != sizeof(Elf_Sym)) 263 return ENOEXEC; 264 break; 265 case DT_PLTGOT: 266 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 267 break; 268 case DT_REL: 269 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 270 break; 271 case DT_RELSZ: 272 ef->relsize = dp->d_un.d_val; 273 break; 274 case DT_RELENT: 275 if (dp->d_un.d_val != sizeof(Elf_Rel)) 276 return ENOEXEC; 277 break; 278 case DT_JMPREL: 279 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 280 break; 281 case DT_PLTRELSZ: 282 ef->pltrelsize = dp->d_un.d_val; 283 break; 284 case DT_RELA: 285 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 286 break; 287 case DT_RELASZ: 288 ef->relasize = dp->d_un.d_val; 289 break; 290 case DT_RELAENT: 291 if (dp->d_un.d_val != sizeof(Elf_Rela)) 292 return ENOEXEC; 293 break; 294 case DT_PLTREL: 295 plttype = dp->d_un.d_val; 296 if (plttype != DT_REL && plttype != DT_RELA) 297 return ENOEXEC; 298 break; 299 } 300 } 301 302 if (plttype == DT_RELA) { 303 ef->pltrela = (const Elf_Rela *) ef->pltrel; 304 ef->pltrel = NULL; 305 ef->pltrelasize = ef->pltrelsize; 306 ef->pltrelsize = 0; 307 } 308 309 ef->ddbsymtab = ef->symtab; 310 ef->ddbsymcnt = ef->nchains; 311 ef->ddbstrtab = ef->strtab; 312 ef->ddbstrcnt = ef->strsz; 313 314 return 0; 315 } 316 317 static void 318 link_elf_error(const char *s) 319 { 320 kprintf("kldload: %s\n", s); 321 } 322 323 static int 324 link_elf_load_module(const char *filename, linker_file_t *result) 325 { 326 caddr_t modptr, baseptr, sizeptr, dynptr; 327 char *type; 328 elf_file_t ef; 329 linker_file_t lf; 330 int error; 331 vm_offset_t dp; 332 333 /* 334 * Look to see if we have the module preloaded. 335 */ 336 modptr = preload_search_by_name(filename); 337 if (modptr == NULL) 338 return (link_elf_load_file(filename, result)); 339 340 /* It's preloaded, check we can handle it and collect information */ 341 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 342 baseptr = preload_search_info(modptr, MODINFO_ADDR); 343 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 344 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 345 if (type == NULL || strcmp(type, "elf module") != 0) 346 return (EFTYPE); 347 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 348 return (EINVAL); 349 350 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 351 if (ef == NULL) 352 return (ENOMEM); 353 ef->modptr = modptr; 354 ef->address = *(caddr_t *)baseptr; 355 #ifdef SPARSE_MAPPING 356 ef->object = 0; 357 #endif 358 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 359 ef->dynamic = (Elf_Dyn *)dp; 360 lf = linker_make_file(filename, ef, &link_elf_module_ops); 361 if (lf == NULL) { 362 kfree(ef, M_LINKER); 363 return ENOMEM; 364 } 365 lf->address = ef->address; 366 lf->size = *(size_t *)sizeptr; 367 368 error = parse_dynamic(lf); 369 if (error) { 370 linker_file_unload(lf); 371 return error; 372 } 373 error = load_dependancies(lf); 374 if (error) { 375 linker_file_unload(lf); 376 return error; 377 } 378 error = relocate_file(lf); 379 if (error) { 380 linker_file_unload(lf); 381 return error; 382 } 383 parse_module_symbols(lf); 384 lf->flags |= LINKER_FILE_LINKED; 385 *result = lf; 386 return (0); 387 } 388 389 static int 390 link_elf_load_file(const char* filename, linker_file_t* result) 391 { 392 struct nlookupdata nd; 393 struct thread *td = curthread; /* XXX */ 394 struct proc *p = td->td_proc; 395 struct vnode *vp; 396 Elf_Ehdr *hdr; 397 caddr_t firstpage; 398 int nbytes, i; 399 Elf_Phdr *phdr; 400 Elf_Phdr *phlimit; 401 Elf_Phdr *segs[2]; 402 int nsegs; 403 Elf_Phdr *phdyn; 404 Elf_Phdr *phphdr; 405 caddr_t mapbase; 406 size_t mapsize; 407 Elf_Off base_offset; 408 Elf_Addr base_vaddr; 409 Elf_Addr base_vlimit; 410 int error = 0; 411 int resid; 412 elf_file_t ef; 413 linker_file_t lf; 414 char *pathname; 415 Elf_Shdr *shdr; 416 int symtabindex; 417 int symstrindex; 418 int symcnt; 419 int strcnt; 420 421 KKASSERT(p != NULL); 422 if (p->p_ucred == NULL) { 423 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 424 " this early\n", filename); 425 return ENOENT; 426 } 427 shdr = NULL; 428 lf = NULL; 429 pathname = linker_search_path(filename); 430 if (pathname == NULL) 431 return ENOENT; 432 433 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 434 if (error == 0) 435 error = vn_open(&nd, NULL, FREAD, 0); 436 kfree(pathname, M_LINKER); 437 if (error) { 438 nlookup_done(&nd); 439 return error; 440 } 441 vp = nd.nl_open_vp; 442 nd.nl_open_vp = NULL; 443 nlookup_done(&nd); 444 445 /* 446 * Read the elf header from the file. 447 */ 448 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 449 if (firstpage == NULL) { 450 error = ENOMEM; 451 goto out; 452 } 453 hdr = (Elf_Ehdr *)firstpage; 454 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 455 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 456 nbytes = PAGE_SIZE - resid; 457 if (error) 458 goto out; 459 460 if (!IS_ELF(*hdr)) { 461 error = ENOEXEC; 462 goto out; 463 } 464 465 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 466 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 467 link_elf_error("Unsupported file layout"); 468 error = ENOEXEC; 469 goto out; 470 } 471 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 472 || hdr->e_version != EV_CURRENT) { 473 link_elf_error("Unsupported file version"); 474 error = ENOEXEC; 475 goto out; 476 } 477 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 478 link_elf_error("Unsupported file type"); 479 error = ENOEXEC; 480 goto out; 481 } 482 if (hdr->e_machine != ELF_TARG_MACH) { 483 link_elf_error("Unsupported machine"); 484 error = ENOEXEC; 485 goto out; 486 } 487 488 /* 489 * We rely on the program header being in the first page. This is 490 * not strictly required by the ABI specification, but it seems to 491 * always true in practice. And, it simplifies things considerably. 492 */ 493 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 494 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 495 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 496 link_elf_error("Unreadable program headers"); 497 498 /* 499 * Scan the program header entries, and save key information. 500 * 501 * We rely on there being exactly two load segments, text and data, 502 * in that order. 503 */ 504 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 505 phlimit = phdr + hdr->e_phnum; 506 nsegs = 0; 507 phdyn = NULL; 508 phphdr = NULL; 509 while (phdr < phlimit) { 510 switch (phdr->p_type) { 511 512 case PT_LOAD: 513 if (nsegs == 2) { 514 link_elf_error("Too many sections"); 515 error = ENOEXEC; 516 goto out; 517 } 518 segs[nsegs] = phdr; 519 ++nsegs; 520 break; 521 522 case PT_PHDR: 523 phphdr = phdr; 524 break; 525 526 case PT_DYNAMIC: 527 phdyn = phdr; 528 break; 529 } 530 531 ++phdr; 532 } 533 if (phdyn == NULL) { 534 link_elf_error("Object is not dynamically-linked"); 535 error = ENOEXEC; 536 goto out; 537 } 538 539 /* 540 * Allocate the entire address space of the object, to stake out our 541 * contiguous region, and to establish the base address for relocation. 542 */ 543 base_offset = trunc_page(segs[0]->p_offset); 544 base_vaddr = trunc_page(segs[0]->p_vaddr); 545 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 546 mapsize = base_vlimit - base_vaddr; 547 548 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 549 #ifdef SPARSE_MAPPING 550 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 551 if (ef->object == NULL) { 552 kfree(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, mapsize, 560 1, 561 VM_MAPTYPE_NORMAL, 562 VM_PROT_ALL, VM_PROT_ALL, 563 0); 564 if (error) { 565 vm_object_deallocate(ef->object); 566 kfree(ef, M_LINKER); 567 goto out; 568 } 569 #else 570 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 571 #endif 572 mapbase = ef->address; 573 574 /* 575 * Read the text and data sections and zero the bss. 576 */ 577 for (i = 0; i < 2; i++) { 578 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 579 error = vn_rdwr(UIO_READ, vp, 580 segbase, segs[i]->p_filesz, segs[i]->p_offset, 581 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 582 if (error) { 583 #ifdef SPARSE_MAPPING 584 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 585 (vm_offset_t) ef->address 586 + (ef->object->size << PAGE_SHIFT)); 587 vm_object_deallocate(ef->object); 588 #else 589 kfree(ef->address, M_LINKER); 590 #endif 591 kfree(ef, M_LINKER); 592 goto out; 593 } 594 bzero(segbase + segs[i]->p_filesz, 595 segs[i]->p_memsz - segs[i]->p_filesz); 596 597 #ifdef SPARSE_MAPPING 598 /* 599 * Wire down the pages 600 */ 601 vm_map_wire(&kernel_map, 602 (vm_offset_t) segbase, 603 (vm_offset_t) segbase + segs[i]->p_memsz, 604 0); 605 #endif 606 } 607 608 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 609 610 lf = linker_make_file(filename, ef, &link_elf_file_ops); 611 if (lf == NULL) { 612 #ifdef SPARSE_MAPPING 613 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 614 (vm_offset_t) ef->address 615 + (ef->object->size << PAGE_SHIFT)); 616 vm_object_deallocate(ef->object); 617 #else 618 kfree(ef->address, M_LINKER); 619 #endif 620 kfree(ef, M_LINKER); 621 error = ENOMEM; 622 goto out; 623 } 624 lf->address = ef->address; 625 lf->size = mapsize; 626 627 error = parse_dynamic(lf); 628 if (error) 629 goto out; 630 error = load_dependancies(lf); 631 if (error) 632 goto out; 633 error = relocate_file(lf); 634 if (error) 635 goto out; 636 637 /* Try and load the symbol table if it's present. (you can strip it!) */ 638 nbytes = hdr->e_shnum * hdr->e_shentsize; 639 if (nbytes == 0 || hdr->e_shoff == 0) 640 goto nosyms; 641 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 642 if (shdr == NULL) { 643 error = ENOMEM; 644 goto out; 645 } 646 error = vn_rdwr(UIO_READ, vp, 647 (caddr_t)shdr, nbytes, hdr->e_shoff, 648 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 649 if (error) 650 goto out; 651 symtabindex = -1; 652 symstrindex = -1; 653 for (i = 0; i < hdr->e_shnum; i++) { 654 if (shdr[i].sh_type == SHT_SYMTAB) { 655 symtabindex = i; 656 symstrindex = shdr[i].sh_link; 657 } 658 } 659 if (symtabindex < 0 || symstrindex < 0) 660 goto nosyms; 661 662 symcnt = shdr[symtabindex].sh_size; 663 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 664 strcnt = shdr[symstrindex].sh_size; 665 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 666 667 if (ef->symbase == NULL || ef->strbase == NULL) { 668 error = ENOMEM; 669 goto out; 670 } 671 error = vn_rdwr(UIO_READ, vp, 672 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 673 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 674 if (error) 675 goto out; 676 error = vn_rdwr(UIO_READ, vp, 677 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 678 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 679 if (error) 680 goto out; 681 682 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 683 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 684 ef->ddbstrcnt = strcnt; 685 ef->ddbstrtab = ef->strbase; 686 687 lf->flags |= LINKER_FILE_LINKED; 688 689 nosyms: 690 691 *result = lf; 692 693 out: 694 if (error && lf) 695 linker_file_unload(lf); 696 if (shdr) 697 kfree(shdr, M_LINKER); 698 if (firstpage) 699 kfree(firstpage, M_LINKER); 700 vn_unlock(vp); 701 vn_close(vp, FREAD); 702 703 return error; 704 } 705 706 static void 707 link_elf_unload_file(linker_file_t file) 708 { 709 elf_file_t ef = file->priv; 710 711 if (ef) { 712 #ifdef SPARSE_MAPPING 713 if (ef->object) { 714 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 715 (vm_offset_t) ef->address 716 + (ef->object->size << PAGE_SHIFT)); 717 vm_object_deallocate(ef->object); 718 } 719 #else 720 if (ef->address) 721 kfree(ef->address, M_LINKER); 722 #endif 723 if (ef->symbase) 724 kfree(ef->symbase, M_LINKER); 725 if (ef->strbase) 726 kfree(ef->strbase, M_LINKER); 727 kfree(ef, M_LINKER); 728 } 729 } 730 731 static void 732 link_elf_unload_module(linker_file_t file) 733 { 734 elf_file_t ef = file->priv; 735 736 if (ef) 737 kfree(ef, M_LINKER); 738 if (file->filename) 739 preload_delete_name(file->filename); 740 } 741 742 static int 743 load_dependancies(linker_file_t lf) 744 { 745 elf_file_t ef = lf->priv; 746 linker_file_t lfdep; 747 char* name; 748 const Elf_Dyn *dp; 749 int error = 0; 750 751 /* 752 * All files are dependant on /kernel. 753 */ 754 if (linker_kernel_file) { 755 linker_kernel_file->refs++; 756 linker_file_add_dependancy(lf, linker_kernel_file); 757 } 758 759 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 760 if (dp->d_tag == DT_NEEDED) { 761 name = ef->strtab + dp->d_un.d_val; 762 763 error = linker_load_file(name, &lfdep); 764 if (error) 765 goto out; 766 error = linker_file_add_dependancy(lf, lfdep); 767 if (error) 768 goto out; 769 } 770 } 771 772 out: 773 return error; 774 } 775 776 static const char * 777 symbol_name(elf_file_t ef, Elf_Word r_info) 778 { 779 const Elf_Sym *ref; 780 781 if (ELF_R_SYM(r_info)) { 782 ref = ef->symtab + ELF_R_SYM(r_info); 783 return ef->strtab + ref->st_name; 784 } else 785 return NULL; 786 } 787 788 static int 789 relocate_file(linker_file_t lf) 790 { 791 elf_file_t ef = lf->priv; 792 const Elf_Rel *rellim; 793 const Elf_Rel *rel; 794 const Elf_Rela *relalim; 795 const Elf_Rela *rela; 796 const char *symname; 797 798 /* Perform relocations without addend if there are any: */ 799 rel = ef->rel; 800 if (rel) { 801 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 802 while (rel < rellim) { 803 symname = symbol_name(ef, rel->r_info); 804 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 805 kprintf("link_elf: symbol %s undefined\n", symname); 806 return ENOENT; 807 } 808 rel++; 809 } 810 } 811 812 /* Perform relocations with addend if there are any: */ 813 rela = ef->rela; 814 if (rela) { 815 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 816 while (rela < relalim) { 817 symname = symbol_name(ef, rela->r_info); 818 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 819 kprintf("link_elf: symbol %s undefined\n", symname); 820 return ENOENT; 821 } 822 rela++; 823 } 824 } 825 826 /* Perform PLT relocations without addend if there are any: */ 827 rel = ef->pltrel; 828 if (rel) { 829 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 830 while (rel < rellim) { 831 symname = symbol_name(ef, rel->r_info); 832 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 833 kprintf("link_elf: symbol %s undefined\n", symname); 834 return ENOENT; 835 } 836 rel++; 837 } 838 } 839 840 /* Perform relocations with addend if there are any: */ 841 rela = ef->pltrela; 842 if (rela) { 843 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 844 while (rela < relalim) { 845 symname = symbol_name(ef, rela->r_info); 846 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 847 kprintf("link_elf: symbol %s undefined\n", symname); 848 return ENOENT; 849 } 850 rela++; 851 } 852 } 853 854 return 0; 855 } 856 857 /* 858 * Hash function for symbol table lookup. Don't even think about changing 859 * this. It is specified by the System V ABI. 860 */ 861 static unsigned long 862 elf_hash(const char *name) 863 { 864 const unsigned char *p = (const unsigned char *) name; 865 unsigned long h = 0; 866 unsigned long g; 867 868 while (*p != '\0') { 869 h = (h << 4) + *p++; 870 if ((g = h & 0xf0000000) != 0) 871 h ^= g >> 24; 872 h &= ~g; 873 } 874 return h; 875 } 876 877 int 878 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 879 { 880 elf_file_t ef = lf->priv; 881 unsigned long symnum; 882 const Elf_Sym* symp; 883 const char *strp; 884 unsigned long hash; 885 int i; 886 887 /* First, search hashed global symbols */ 888 hash = elf_hash(name); 889 symnum = ef->buckets[hash % ef->nbuckets]; 890 891 while (symnum != STN_UNDEF) { 892 if (symnum >= ef->nchains) { 893 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 894 return ENOENT; 895 } 896 897 symp = ef->symtab + symnum; 898 if (symp->st_name == 0) { 899 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 900 return ENOENT; 901 } 902 903 strp = ef->strtab + symp->st_name; 904 905 if (strcmp(name, strp) == 0) { 906 if (symp->st_shndx != SHN_UNDEF || 907 (symp->st_value != 0 && 908 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 909 ) { 910 *sym = (c_linker_sym_t) symp; 911 return 0; 912 } else { 913 return ENOENT; 914 } 915 } 916 917 symnum = ef->chains[symnum]; 918 } 919 920 /* If we have not found it, look at the full table (if loaded) */ 921 if (ef->symtab == ef->ddbsymtab) 922 return ENOENT; 923 924 /* Exhaustive search */ 925 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 926 strp = ef->ddbstrtab + symp->st_name; 927 if (strcmp(name, strp) == 0) { 928 if (symp->st_shndx != SHN_UNDEF || 929 (symp->st_value != 0 && 930 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 931 *sym = (c_linker_sym_t) symp; 932 return 0; 933 } else { 934 return ENOENT; 935 } 936 } 937 } 938 return ENOENT; 939 } 940 941 static int 942 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 943 { 944 elf_file_t ef = lf->priv; 945 const Elf_Sym* es = (const Elf_Sym*) sym; 946 947 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 948 symval->name = ef->strtab + es->st_name; 949 symval->value = (caddr_t) ef->address + es->st_value; 950 symval->size = es->st_size; 951 return 0; 952 } 953 if (ef->symtab == ef->ddbsymtab) 954 return ENOENT; 955 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 956 symval->name = ef->ddbstrtab + es->st_name; 957 symval->value = (caddr_t) ef->address + es->st_value; 958 symval->size = es->st_size; 959 return 0; 960 } 961 return ENOENT; 962 } 963 964 static int 965 link_elf_search_symbol(linker_file_t lf, caddr_t value, 966 c_linker_sym_t* sym, long* diffp) 967 { 968 elf_file_t ef = lf->priv; 969 u_long off = (uintptr_t) (void *) value; 970 u_long diff = off; 971 u_long st_value; 972 const Elf_Sym* es; 973 const Elf_Sym* best = 0; 974 int i; 975 976 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 977 if (es->st_name == 0) 978 continue; 979 st_value = es->st_value + (uintptr_t) (void *) ef->address; 980 if (off >= st_value) { 981 if (off - st_value < diff) { 982 diff = off - st_value; 983 best = es; 984 if (diff == 0) 985 break; 986 } else if (off - st_value == diff) { 987 best = es; 988 } 989 } 990 } 991 if (best == 0) 992 *diffp = off; 993 else 994 *diffp = diff; 995 *sym = (c_linker_sym_t) best; 996 997 return 0; 998 } 999 1000 /* 1001 * Look up a linker set on an ELF system. 1002 */ 1003 static int 1004 link_elf_lookup_set(linker_file_t lf, const char *name, 1005 void ***startp, void ***stopp, int *countp) 1006 { 1007 c_linker_sym_t sym; 1008 linker_symval_t symval; 1009 char *setsym; 1010 void **start, **stop; 1011 int len, error = 0, count; 1012 1013 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1014 setsym = kmalloc(len, M_LINKER, M_WAITOK); 1015 if (setsym == NULL) 1016 return ENOMEM; 1017 1018 /* get address of first entry */ 1019 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 1020 error = link_elf_lookup_symbol(lf, setsym, &sym); 1021 if (error) 1022 goto out; 1023 link_elf_symbol_values(lf, sym, &symval); 1024 if (symval.value == 0) { 1025 error = ESRCH; 1026 goto out; 1027 } 1028 start = (void **)symval.value; 1029 1030 /* get address of last entry */ 1031 ksnprintf(setsym, len, "%s%s", "__stop_set_", name); 1032 error = link_elf_lookup_symbol(lf, setsym, &sym); 1033 if (error) 1034 goto out; 1035 link_elf_symbol_values(lf, sym, &symval); 1036 if (symval.value == 0) { 1037 error = ESRCH; 1038 goto out; 1039 } 1040 stop = (void **)symval.value; 1041 1042 /* and the number of entries */ 1043 count = stop - start; 1044 1045 /* and copy out */ 1046 if (startp) 1047 *startp = start; 1048 if (stopp) 1049 *stopp = stop; 1050 if (countp) 1051 *countp = count; 1052 1053 out: 1054 kfree(setsym, M_LINKER); 1055 return error; 1056 } 1057 1058