Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/boot/common/load_elf_obj.c
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1 /*- 2 * Copyright (c) 2004 Ian Dowse <iedowse@freebsd.org> 3 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org> 4 * Copyright (c) 1998 Peter Wemm <peter@freebsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD: releng/8.2/sys/boot/common/load_elf_obj.c 211585 2010-08-21 18:48:24Z avg $"); 31 32 #include <sys/param.h> 33 #include <sys/exec.h> 34 #include <sys/linker.h> 35 #include <sys/module.h> 36 #include <inttypes.h> 37 #include <string.h> 38 #include <machine/elf.h> 39 #include <stand.h> 40 #define FREEBSD_ELF 41 #include <link.h> 42 43 #include "bootstrap.h" 44 45 #define COPYOUT(s,d,l) archsw.arch_copyout((vm_offset_t)(s), d, l) 46 47 #if defined(__i386__) && __ELF_WORD_SIZE == 64 48 #undef ELF_TARG_CLASS 49 #undef ELF_TARG_MACH 50 #define ELF_TARG_CLASS ELFCLASS64 51 #define ELF_TARG_MACH EM_X86_64 52 #endif 53 54 typedef struct elf_file { 55 Elf_Ehdr hdr; 56 Elf_Shdr *e_shdr; 57 58 int symtabindex; /* Index of symbol table */ 59 int shstrindex; /* Index of section name string table */ 60 61 int fd; 62 vm_offset_t off; 63 } *elf_file_t; 64 65 static int __elfN(obj_loadimage)(struct preloaded_file *mp, elf_file_t ef, 66 u_int64_t loadaddr); 67 static int __elfN(obj_lookup_set)(struct preloaded_file *mp, elf_file_t ef, 68 const char *name, Elf_Addr *startp, Elf_Addr *stopp, int *countp); 69 static int __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef, 70 Elf_Addr p, void *val, size_t len); 71 static int __elfN(obj_parse_modmetadata)(struct preloaded_file *mp, 72 elf_file_t ef); 73 static Elf_Addr __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx); 74 75 const char *__elfN(obj_kerneltype) = "elf kernel"; 76 const char *__elfN(obj_moduletype) = "elf obj module"; 77 78 /* 79 * Attempt to load the file (file) as an ELF module. It will be stored at 80 * (dest), and a pointer to a module structure describing the loaded object 81 * will be saved in (result). 82 */ 83 int 84 __elfN(obj_loadfile)(char *filename, u_int64_t dest, 85 struct preloaded_file **result) 86 { 87 struct preloaded_file *fp, *kfp; 88 struct elf_file ef; 89 Elf_Ehdr *hdr; 90 int err; 91 ssize_t bytes_read; 92 93 fp = NULL; 94 bzero(&ef, sizeof(struct elf_file)); 95 96 /* 97 * Open the image, read and validate the ELF header 98 */ 99 if (filename == NULL) /* can't handle nameless */ 100 return(EFTYPE); 101 if ((ef.fd = open(filename, O_RDONLY)) == -1) 102 return(errno); 103 104 hdr = &ef.hdr; 105 bytes_read = read(ef.fd, hdr, sizeof(*hdr)); 106 if (bytes_read != sizeof(*hdr)) { 107 err = EFTYPE; /* could be EIO, but may be small file */ 108 goto oerr; 109 } 110 111 /* Is it ELF? */ 112 if (!IS_ELF(*hdr)) { 113 err = EFTYPE; 114 goto oerr; 115 } 116 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS || /* Layout ? */ 117 hdr->e_ident[EI_DATA] != ELF_TARG_DATA || 118 hdr->e_ident[EI_VERSION] != EV_CURRENT || /* Version ? */ 119 hdr->e_version != EV_CURRENT || 120 hdr->e_machine != ELF_TARG_MACH || /* Machine ? */ 121 hdr->e_type != ET_REL) { 122 err = EFTYPE; 123 goto oerr; 124 } 125 126 if (hdr->e_shnum * hdr->e_shentsize == 0 || hdr->e_shoff == 0 || 127 hdr->e_shentsize != sizeof(Elf_Shdr)) { 128 err = EFTYPE; 129 goto oerr; 130 } 131 132 kfp = file_findfile(NULL, NULL); 133 if (kfp == NULL) { 134 printf("elf" __XSTRING(__ELF_WORD_SIZE) 135 "_obj_loadfile: can't load module before kernel\n"); 136 err = EPERM; 137 goto oerr; 138 } 139 if (strcmp(__elfN(obj_kerneltype), kfp->f_type)) { 140 printf("elf" __XSTRING(__ELF_WORD_SIZE) 141 "_obj_loadfile: can't load module with kernel type '%s'\n", 142 kfp->f_type); 143 err = EPERM; 144 goto oerr; 145 } 146 147 /* Page-align the load address */ 148 dest = roundup(dest, PAGE_SIZE); 149 150 /* 151 * Ok, we think we should handle this. 152 */ 153 fp = file_alloc(); 154 if (fp == NULL) { 155 printf("elf" __XSTRING(__ELF_WORD_SIZE) 156 "_obj_loadfile: cannot allocate module info\n"); 157 err = EPERM; 158 goto out; 159 } 160 fp->f_name = strdup(filename); 161 fp->f_type = strdup(__elfN(obj_moduletype)); 162 163 printf("%s ", filename); 164 165 fp->f_size = __elfN(obj_loadimage)(fp, &ef, dest); 166 if (fp->f_size == 0 || fp->f_addr == 0) 167 goto ioerr; 168 169 /* save exec header as metadata */ 170 file_addmetadata(fp, MODINFOMD_ELFHDR, sizeof(*hdr), hdr); 171 172 /* Load OK, return module pointer */ 173 *result = (struct preloaded_file *)fp; 174 err = 0; 175 goto out; 176 177 ioerr: 178 err = EIO; 179 oerr: 180 file_discard(fp); 181 out: 182 close(ef.fd); 183 if (ef.e_shdr != NULL) 184 free(ef.e_shdr); 185 186 return(err); 187 } 188 189 /* 190 * With the file (fd) open on the image, and (ehdr) containing 191 * the Elf header, load the image at (off) 192 */ 193 static int 194 __elfN(obj_loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off) 195 { 196 Elf_Ehdr *hdr; 197 Elf_Shdr *shdr; 198 vm_offset_t firstaddr, lastaddr; 199 int i, nsym, res, ret, shdrbytes, symstrindex; 200 201 ret = 0; 202 firstaddr = lastaddr = (vm_offset_t)off; 203 hdr = &ef->hdr; 204 ef->off = (vm_offset_t)off; 205 206 /* Read in the section headers. */ 207 shdrbytes = hdr->e_shnum * hdr->e_shentsize; 208 shdr = alloc_pread(ef->fd, (off_t)hdr->e_shoff, shdrbytes); 209 if (shdr == NULL) { 210 printf("\nelf" __XSTRING(__ELF_WORD_SIZE) 211 "_obj_loadimage: read section headers failed\n"); 212 goto out; 213 } 214 ef->e_shdr = shdr; 215 216 /* 217 * Decide where to load everything, but don't read it yet. 218 * We store the load address as a non-zero sh_addr value. 219 * Start with the code/data and bss. 220 */ 221 for (i = 0; i < hdr->e_shnum; i++) 222 shdr[i].sh_addr = 0; 223 for (i = 0; i < hdr->e_shnum; i++) { 224 if (shdr[i].sh_size == 0) 225 continue; 226 switch (shdr[i].sh_type) { 227 case SHT_PROGBITS: 228 case SHT_NOBITS: 229 lastaddr = roundup(lastaddr, shdr[i].sh_addralign); 230 shdr[i].sh_addr = (Elf_Addr)lastaddr; 231 lastaddr += shdr[i].sh_size; 232 break; 233 } 234 } 235 236 /* Symbols. */ 237 nsym = 0; 238 for (i = 0; i < hdr->e_shnum; i++) { 239 switch (shdr[i].sh_type) { 240 case SHT_SYMTAB: 241 nsym++; 242 ef->symtabindex = i; 243 shdr[i].sh_addr = (Elf_Addr)lastaddr; 244 lastaddr += shdr[i].sh_size; 245 break; 246 } 247 } 248 if (nsym != 1) { 249 printf("\nelf" __XSTRING(__ELF_WORD_SIZE) 250 "_obj_loadimage: file has no valid symbol table\n"); 251 goto out; 252 } 253 lastaddr = roundup(lastaddr, shdr[ef->symtabindex].sh_addralign); 254 shdr[ef->symtabindex].sh_addr = (Elf_Addr)lastaddr; 255 lastaddr += shdr[ef->symtabindex].sh_size; 256 257 symstrindex = shdr[ef->symtabindex].sh_link; 258 if (symstrindex < 0 || symstrindex >= hdr->e_shnum || 259 shdr[symstrindex].sh_type != SHT_STRTAB) { 260 printf("\nelf" __XSTRING(__ELF_WORD_SIZE) 261 "_obj_loadimage: file has invalid symbol strings\n"); 262 goto out; 263 } 264 lastaddr = roundup(lastaddr, shdr[symstrindex].sh_addralign); 265 shdr[symstrindex].sh_addr = (Elf_Addr)lastaddr; 266 lastaddr += shdr[symstrindex].sh_size; 267 268 /* Section names. */ 269 if (hdr->e_shstrndx == 0 || hdr->e_shstrndx >= hdr->e_shnum || 270 shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) { 271 printf("\nelf" __XSTRING(__ELF_WORD_SIZE) 272 "_obj_loadimage: file has no section names\n"); 273 goto out; 274 } 275 ef->shstrindex = hdr->e_shstrndx; 276 lastaddr = roundup(lastaddr, shdr[ef->shstrindex].sh_addralign); 277 shdr[ef->shstrindex].sh_addr = (Elf_Addr)lastaddr; 278 lastaddr += shdr[ef->shstrindex].sh_size; 279 280 /* Relocation tables. */ 281 for (i = 0; i < hdr->e_shnum; i++) { 282 switch (shdr[i].sh_type) { 283 case SHT_REL: 284 case SHT_RELA: 285 lastaddr = roundup(lastaddr, shdr[i].sh_addralign); 286 shdr[i].sh_addr = (Elf_Addr)lastaddr; 287 lastaddr += shdr[i].sh_size; 288 break; 289 } 290 } 291 292 /* Clear the whole area, including bss regions. */ 293 kern_bzero(firstaddr, lastaddr - firstaddr); 294 295 /* Now read it all in. */ 296 for (i = 0; i < hdr->e_shnum; i++) { 297 if (shdr[i].sh_addr == 0 || shdr[i].sh_type == SHT_NOBITS) 298 continue; 299 if (kern_pread(ef->fd, (vm_offset_t)shdr[i].sh_addr, 300 shdr[i].sh_size, (off_t)shdr[i].sh_offset) != 0) { 301 printf("\nelf" __XSTRING(__ELF_WORD_SIZE) 302 "_obj_loadimage: read failed\n"); 303 goto out; 304 } 305 } 306 307 file_addmetadata(fp, MODINFOMD_SHDR, shdrbytes, shdr); 308 309 res = __elfN(obj_parse_modmetadata)(fp, ef); 310 if (res != 0) 311 goto out; 312 313 ret = lastaddr - firstaddr; 314 fp->f_addr = firstaddr; 315 316 printf("size 0x%lx at 0x%lx", (u_long)ret, (u_long)firstaddr); 317 318 out: 319 printf("\n"); 320 return ret; 321 } 322 323 #if defined(__i386__) && __ELF_WORD_SIZE == 64 324 struct mod_metadata64 { 325 int md_version; /* structure version MDTV_* */ 326 int md_type; /* type of entry MDT_* */ 327 u_int64_t md_data; /* specific data */ 328 u_int64_t md_cval; /* common string label */ 329 }; 330 #endif 331 332 int 333 __elfN(obj_parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef) 334 { 335 struct mod_metadata md; 336 #if defined(__i386__) && __ELF_WORD_SIZE == 64 337 struct mod_metadata64 md64; 338 #endif 339 struct mod_depend *mdepend; 340 struct mod_version mver; 341 char *s; 342 int error, modcnt, minfolen; 343 Elf_Addr v, p, p_stop; 344 345 if (__elfN(obj_lookup_set)(fp, ef, "modmetadata_set", &p, &p_stop, 346 &modcnt) != 0) 347 return ENOENT; 348 349 modcnt = 0; 350 while (p < p_stop) { 351 COPYOUT(p, &v, sizeof(v)); 352 error = __elfN(obj_reloc_ptr)(fp, ef, p, &v, sizeof(v)); 353 if (error != 0) 354 return (error); 355 #if defined(__i386__) && __ELF_WORD_SIZE == 64 356 COPYOUT(v, &md64, sizeof(md64)); 357 error = __elfN(obj_reloc_ptr)(fp, ef, v, &md64, sizeof(md64)); 358 if (error != 0) 359 return (error); 360 md.md_version = md64.md_version; 361 md.md_type = md64.md_type; 362 md.md_cval = (const char *)(uintptr_t)md64.md_cval; 363 md.md_data = (void *)(uintptr_t)md64.md_data; 364 #else 365 COPYOUT(v, &md, sizeof(md)); 366 error = __elfN(obj_reloc_ptr)(fp, ef, v, &md, sizeof(md)); 367 if (error != 0) 368 return (error); 369 #endif 370 p += sizeof(Elf_Addr); 371 switch(md.md_type) { 372 case MDT_DEPEND: 373 s = strdupout((vm_offset_t)md.md_cval); 374 minfolen = sizeof(*mdepend) + strlen(s) + 1; 375 mdepend = malloc(minfolen); 376 if (mdepend == NULL) 377 return ENOMEM; 378 COPYOUT((vm_offset_t)md.md_data, mdepend, 379 sizeof(*mdepend)); 380 strcpy((char*)(mdepend + 1), s); 381 free(s); 382 file_addmetadata(fp, MODINFOMD_DEPLIST, minfolen, 383 mdepend); 384 free(mdepend); 385 break; 386 case MDT_VERSION: 387 s = strdupout((vm_offset_t)md.md_cval); 388 COPYOUT((vm_offset_t)md.md_data, &mver, sizeof(mver)); 389 file_addmodule(fp, s, mver.mv_version, NULL); 390 free(s); 391 modcnt++; 392 break; 393 case MDT_MODULE: 394 break; 395 default: 396 printf("unknown type %d\n", md.md_type); 397 break; 398 } 399 } 400 return 0; 401 } 402 403 static int 404 __elfN(obj_lookup_set)(struct preloaded_file *fp, elf_file_t ef, 405 const char* name, Elf_Addr *startp, Elf_Addr *stopp, int *countp) 406 { 407 Elf_Ehdr *hdr; 408 Elf_Shdr *shdr; 409 char *p; 410 vm_offset_t shstrtab; 411 int i; 412 413 hdr = &ef->hdr; 414 shdr = ef->e_shdr; 415 shstrtab = shdr[ef->shstrindex].sh_addr; 416 417 for (i = 0; i < hdr->e_shnum; i++) { 418 if (shdr[i].sh_type != SHT_PROGBITS) 419 continue; 420 if (shdr[i].sh_name == 0) 421 continue; 422 p = strdupout(shstrtab + shdr[i].sh_name); 423 if (strncmp(p, "set_", 4) == 0 && strcmp(p + 4, name) == 0) { 424 *startp = shdr[i].sh_addr; 425 *stopp = shdr[i].sh_addr + shdr[i].sh_size; 426 *countp = (*stopp - *startp) / sizeof(Elf_Addr); 427 free(p); 428 return (0); 429 } 430 free(p); 431 } 432 433 return (ESRCH); 434 } 435 436 /* 437 * Apply any intra-module relocations to the value. p is the load address 438 * of the value and val/len is the value to be modified. This does NOT modify 439 * the image in-place, because this is done by kern_linker later on. 440 */ 441 static int 442 __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef, Elf_Addr p, 443 void *val, size_t len) 444 { 445 Elf_Ehdr *hdr; 446 Elf_Shdr *shdr; 447 Elf_Addr off = p; 448 Elf_Addr base; 449 Elf_Rela a, *abase; 450 Elf_Rel r, *rbase; 451 int error, i, j, nrel, nrela; 452 453 hdr = &ef->hdr; 454 shdr = ef->e_shdr; 455 456 for (i = 0; i < hdr->e_shnum; i++) { 457 if (shdr[i].sh_type != SHT_RELA && shdr[i].sh_type != SHT_REL) 458 continue; 459 base = shdr[shdr[i].sh_info].sh_addr; 460 if (base == 0 || shdr[i].sh_addr == 0) 461 continue; 462 if (off < base || off + len > base + 463 shdr[shdr[i].sh_info].sh_size) 464 continue; 465 466 switch (shdr[i].sh_type) { 467 case SHT_RELA: 468 abase = (Elf_Rela *)(intptr_t)shdr[i].sh_addr; 469 470 nrela = shdr[i].sh_size / sizeof(Elf_Rela); 471 for (j = 0; j < nrela; j++) { 472 COPYOUT(abase + j, &a, sizeof(a)); 473 474 error = __elfN(reloc)(ef, __elfN(obj_symaddr), 475 &a, ELF_RELOC_RELA, base, off, val, len); 476 if (error != 0) 477 return (error); 478 } 479 break; 480 case SHT_REL: 481 rbase = (Elf_Rel *)(intptr_t)shdr[i].sh_addr; 482 483 nrel = shdr[i].sh_size / sizeof(Elf_Rel); 484 for (j = 0; j < nrel; j++) { 485 COPYOUT(rbase + j, &r, sizeof(r)); 486 487 error = __elfN(reloc)(ef, __elfN(obj_symaddr), 488 &r, ELF_RELOC_REL, base, off, val, len); 489 if (error != 0) 490 return (error); 491 } 492 break; 493 } 494 } 495 return (0); 496 } 497 498 /* Look up the address of a specified symbol. */ 499 static Elf_Addr 500 __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx) 501 { 502 Elf_Sym sym; 503 Elf_Addr base; 504 int symcnt; 505 506 symcnt = ef->e_shdr[ef->symtabindex].sh_size / sizeof(Elf_Sym); 507 if (symidx >= symcnt) 508 return (0); 509 COPYOUT(ef->e_shdr[ef->symtabindex].sh_addr + symidx * sizeof(Elf_Sym), 510 &sym, sizeof(sym)); 511 if (sym.st_shndx == SHN_UNDEF || sym.st_shndx >= ef->hdr.e_shnum) 512 return (0); 513 base = ef->e_shdr[sym.st_shndx].sh_addr; 514 if (base == 0) 515 return (0); 516 return (base + sym.st_value); 517 }
Cache object: da3261d0f697b8eae60a5695725f8c53
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