elf_update.c revision 210326
10SN/A/*- 22362SN/A * Copyright (c) 2006-2008 Joseph Koshy 30SN/A * All rights reserved. 40SN/A * 50SN/A * Redistribution and use in source and binary forms, with or without 60SN/A * modification, are permitted provided that the following conditions 72362SN/A * are met: 80SN/A * 1. Redistributions of source code must retain the above copyright 92362SN/A * notice, this list of conditions and the following disclaimer. 100SN/A * 2. Redistributions in binary form must reproduce the above copyright 110SN/A * notice, this list of conditions and the following disclaimer in the 120SN/A * documentation and/or other materials provided with the distribution. 130SN/A * 140SN/A * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 150SN/A * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 160SN/A * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 170SN/A * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 180SN/A * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 190SN/A * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 200SN/A * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 212362SN/A * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 222362SN/A * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 232362SN/A * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 240SN/A * SUCH DAMAGE. 250SN/A */ 260SN/A 270SN/A#include <sys/cdefs.h> 280SN/A__FBSDID("$FreeBSD: head/lib/libelf/elf_update.c 210326 2010-07-21 09:20:40Z kaiw $"); 290SN/A 300SN/A#include <sys/mman.h> 311245SN/A#include <sys/param.h> 3211407Ssherman 330SN/A#include <assert.h> 341245SN/A#include <errno.h> 350SN/A#include <gelf.h> 360SN/A#include <libelf.h> 370SN/A#include <stdlib.h> 380SN/A#include <string.h> 390SN/A#include <unistd.h> 400SN/A 410SN/A#include "_libelf.h" 420SN/A 430SN/A/* 440SN/A * Update the internal data structures associated with an ELF object. 450SN/A * Returns the size in bytes the ELF object would occupy in its file 460SN/A * representation. 470SN/A * 480SN/A * After a successful call to this function, the following structures 490SN/A * are updated: 500SN/A * 510SN/A * - The ELF header is updated. 521245SN/A * - All sections are sorted in order of ascending addresses and their 531245SN/A * section header table entries updated. An error is signalled 541245SN/A * if an overlap was detected among sections. 551245SN/A * - All data descriptors associated with a section are sorted in order 561245SN/A * of ascending addresses. Overlaps, if detected, are signalled as 570SN/A * errors. Other sanity checks for alignments, section types etc. are 580SN/A * made. 590SN/A * 601245SN/A * After a resync_elf() successfully returns, the ELF descriptor is 610SN/A * ready for being handed over to _libelf_write_elf(). 620SN/A * 631245SN/A * File alignments: 641245SN/A * PHDR - Addr 651245SN/A * SHDR - Addr 660SN/A * 671245SN/A * XXX: how do we handle 'flags'. 681245SN/A */ 690SN/A 701245SN/A/* 711245SN/A * Compute the extents of a section, by looking at the data 721245SN/A * descriptors associated with it. The function returns zero if an 731245SN/A * error was detected. `*rc' holds the maximum file extent seen so 741245SN/A * far. 751245SN/A */ 760SN/Astatic int 771245SN/A_libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t *rc) 781245SN/A{ 791245SN/A int ec; 801245SN/A Elf_Data *d, *td; 811245SN/A unsigned int elftype; 821245SN/A uint32_t sh_type; 830SN/A uint64_t d_align; 841245SN/A uint64_t sh_align, sh_entsize, sh_offset, sh_size; 851245SN/A uint64_t scn_size, scn_alignment; 861245SN/A 871245SN/A /* 881245SN/A * We need to recompute library private data structures if one 891245SN/A * or more of the following is true: 901245SN/A * - The underlying Shdr structure has been marked `dirty'. Significant 911245SN/A * fields include: `sh_offset', `sh_type', `sh_size', `sh_addralign'. 920SN/A * - The Elf_Data structures part of this section have been marked 930SN/A * `dirty'. Affected members include `d_align', `d_offset', `d_type', 94 * and `d_size'. 95 * - The section as a whole is `dirty', e.g., it has been allocated 96 * using elf_newscn(), or if a new Elf_Data structure was added using 97 * elf_newdata(). 98 * 99 * Each of these conditions would result in the ELF_F_DIRTY bit being 100 * set on the section descriptor's `s_flags' field. 101 */ 102 103 ec = e->e_class; 104 105 if (ec == ELFCLASS32) { 106 sh_type = s->s_shdr.s_shdr32.sh_type; 107 sh_align = (uint64_t) s->s_shdr.s_shdr32.sh_addralign; 108 sh_entsize = (uint64_t) s->s_shdr.s_shdr32.sh_entsize; 109 sh_offset = (uint64_t) s->s_shdr.s_shdr32.sh_offset; 110 sh_size = (uint64_t) s->s_shdr.s_shdr32.sh_size; 111 } else { 112 sh_type = s->s_shdr.s_shdr64.sh_type; 113 sh_align = s->s_shdr.s_shdr64.sh_addralign; 114 sh_entsize = s->s_shdr.s_shdr64.sh_entsize; 115 sh_offset = s->s_shdr.s_shdr64.sh_offset; 116 sh_size = s->s_shdr.s_shdr64.sh_size; 117 } 118 119 if (sh_type == SHT_NULL || sh_type == SHT_NOBITS) 120 return (1); 121 122 if ((s->s_flags & ELF_F_DIRTY) == 0) { 123 if ((size_t) *rc < sh_offset + sh_size) 124 *rc = sh_offset + sh_size; 125 return (1); 126 } 127 128 elftype = _libelf_xlate_shtype(sh_type); 129 if (elftype > ELF_T_LAST) { 130 LIBELF_SET_ERROR(SECTION, 0); 131 return (0); 132 } 133 134 /* 135 * Compute the extent of the data descriptors associated with 136 * this section. 137 */ 138 scn_alignment = 0; 139 if (sh_align == 0) 140 sh_align = _libelf_falign(elftype, ec); 141 142 /* Compute the section alignment. */ 143 STAILQ_FOREACH(d, &s->s_data, d_next) { 144 if (d->d_type != elftype) { 145 LIBELF_SET_ERROR(DATA, 0); 146 return (0); 147 } 148 if (d->d_version != e->e_version) { 149 LIBELF_SET_ERROR(VERSION, 0); 150 return (0); 151 } 152 if ((d_align = d->d_align) % sh_align) { 153 LIBELF_SET_ERROR(LAYOUT, 0); 154 return (0); 155 } 156 if (d_align == 0 || (d_align & (d_align - 1))) { 157 LIBELF_SET_ERROR(DATA, 0); 158 return (0); 159 } 160 if (d_align > scn_alignment) 161 scn_alignment = d_align; 162 } 163 164 scn_size = 0L; 165 166 STAILQ_FOREACH_SAFE(d, &s->s_data, d_next, td) { 167 if (e->e_flags & ELF_F_LAYOUT) { 168 if ((uint64_t) d->d_off + d->d_size > scn_size) 169 scn_size = d->d_off + d->d_size; 170 } else { 171 scn_size = roundup2(scn_size, scn_alignment); 172 d->d_off = scn_size; 173 scn_size += d->d_size; 174 } 175 } 176 177 /* 178 * If the application is requesting full control over the layout 179 * of the section, check its values for sanity. 180 */ 181 if (e->e_flags & ELF_F_LAYOUT) { 182 if (scn_alignment > sh_align || sh_offset % sh_align || 183 sh_size < scn_size) { 184 LIBELF_SET_ERROR(LAYOUT, 0); 185 return (0); 186 } 187 } else { 188 /* 189 * Otherwise compute the values in the section header. 190 */ 191 192 if (scn_alignment > sh_align) 193 sh_align = scn_alignment; 194 195 /* 196 * If the section entry size is zero, try and fill in an 197 * appropriate entry size. Per the elf(5) manual page 198 * sections without fixed-size entries should have their 199 * 'sh_entsize' field set to zero. 200 */ 201 if (sh_entsize == 0 && 202 (sh_entsize = _libelf_fsize(elftype, ec, e->e_version, 203 (size_t) 1)) == 1) 204 sh_entsize = 0; 205 206 sh_size = scn_size; 207 sh_offset = roundup(*rc, sh_align); 208 209 if (ec == ELFCLASS32) { 210 s->s_shdr.s_shdr32.sh_addralign = (uint32_t) sh_align; 211 s->s_shdr.s_shdr32.sh_entsize = (uint32_t) sh_entsize; 212 s->s_shdr.s_shdr32.sh_offset = (uint32_t) sh_offset; 213 s->s_shdr.s_shdr32.sh_size = (uint32_t) sh_size; 214 } else { 215 s->s_shdr.s_shdr64.sh_addralign = sh_align; 216 s->s_shdr.s_shdr64.sh_entsize = sh_entsize; 217 s->s_shdr.s_shdr64.sh_offset = sh_offset; 218 s->s_shdr.s_shdr64.sh_size = sh_size; 219 } 220 } 221 222 if ((size_t) *rc < sh_offset + sh_size) 223 *rc = sh_offset + sh_size; 224 225 s->s_size = sh_size; 226 s->s_offset = sh_offset; 227 return (1); 228} 229 230 231/* 232 * Insert a section in ascending order in the list 233 */ 234 235static int 236_libelf_insert_section(Elf *e, Elf_Scn *s) 237{ 238 Elf_Scn *t, *prevt; 239 uint64_t smax, smin, tmax, tmin; 240 241 smin = s->s_offset; 242 smax = smin + s->s_size; 243 244 prevt = NULL; 245 STAILQ_FOREACH(t, &e->e_u.e_elf.e_scn, s_next) { 246 tmin = t->s_offset; 247 tmax = tmin + t->s_size; 248 249 if (tmax <= smin) { 250 /* 251 * 't' lies entirely before 's': ...| t |...| s |... 252 */ 253 prevt = t; 254 continue; 255 } else if (smax <= tmin) 256 /* 257 * 's' lies entirely before 't', and after 'prevt': 258 * ...| prevt |...| s |...| t |... 259 */ 260 break; 261 else { /* 's' and 't' overlap. */ 262 LIBELF_SET_ERROR(LAYOUT, 0); 263 return (0); 264 } 265 } 266 267 if (prevt) 268 STAILQ_INSERT_AFTER(&e->e_u.e_elf.e_scn, prevt, s, s_next); 269 else 270 STAILQ_INSERT_HEAD(&e->e_u.e_elf.e_scn, s, s_next); 271 return (1); 272} 273 274static off_t 275_libelf_resync_sections(Elf *e, off_t rc) 276{ 277 int ec; 278 off_t nrc; 279 size_t sh_type, shdr_start, shdr_end; 280 Elf_Scn *s, *ts; 281 282 ec = e->e_class; 283 284 /* 285 * Make a pass through sections, computing the extent of each 286 * section. Order in increasing order of addresses. 287 */ 288 289 nrc = rc; 290 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) 291 if (_libelf_compute_section_extents(e, s, &nrc) == 0) 292 return ((off_t) -1); 293 294 STAILQ_FOREACH_SAFE(s, &e->e_u.e_elf.e_scn, s_next, ts) { 295 if (ec == ELFCLASS32) 296 sh_type = s->s_shdr.s_shdr32.sh_type; 297 else 298 sh_type = s->s_shdr.s_shdr64.sh_type; 299 300 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL) 301 continue; 302 303 if (s->s_offset < (uint64_t) rc) { 304 if (s->s_offset + s->s_size < (uint64_t) rc) { 305 /* 306 * Try insert this section in the 307 * correct place in the list, 308 * detecting overlaps if any. 309 */ 310 STAILQ_REMOVE(&e->e_u.e_elf.e_scn, s, _Elf_Scn, 311 s_next); 312 if (_libelf_insert_section(e, s) == 0) 313 return ((off_t) -1); 314 } else { 315 LIBELF_SET_ERROR(LAYOUT, 0); 316 return ((off_t) -1); 317 } 318 } else 319 rc = s->s_offset + s->s_size; 320 } 321 322 /* 323 * If the application is controlling file layout, check for an 324 * overlap between this section's extents and the SHDR table. 325 */ 326 if (e->e_flags & ELF_F_LAYOUT) { 327 328 if (e->e_class == ELFCLASS32) 329 shdr_start = e->e_u.e_elf.e_ehdr.e_ehdr32->e_shoff; 330 else 331 shdr_start = e->e_u.e_elf.e_ehdr.e_ehdr64->e_shoff; 332 333 shdr_end = shdr_start + _libelf_fsize(ELF_T_SHDR, e->e_class, 334 e->e_version, e->e_u.e_elf.e_nscn); 335 336 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) { 337 if (s->s_offset >= shdr_end || 338 s->s_offset + s->s_size <= shdr_start) 339 continue; 340 LIBELF_SET_ERROR(LAYOUT, 0); 341 return ((off_t) -1); 342 } 343 } 344 345 assert(nrc == rc); 346 347 return (rc); 348} 349 350static off_t 351_libelf_resync_elf(Elf *e) 352{ 353 int ec, eh_class, eh_type; 354 unsigned int eh_byteorder, eh_version; 355 size_t align, fsz; 356 size_t phnum, shnum; 357 off_t rc, phoff, shoff; 358 void *ehdr; 359 Elf32_Ehdr *eh32; 360 Elf64_Ehdr *eh64; 361 362 rc = 0; 363 364 ec = e->e_class; 365 366 assert(ec == ELFCLASS32 || ec == ELFCLASS64); 367 368 /* 369 * Prepare the EHDR. 370 */ 371 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) 372 return ((off_t) -1); 373 374 eh32 = ehdr; 375 eh64 = ehdr; 376 377 if (ec == ELFCLASS32) { 378 eh_byteorder = eh32->e_ident[EI_DATA]; 379 eh_class = eh32->e_ident[EI_CLASS]; 380 phoff = (uint64_t) eh32->e_phoff; 381 shoff = (uint64_t) eh32->e_shoff; 382 eh_type = eh32->e_type; 383 eh_version = eh32->e_version; 384 } else { 385 eh_byteorder = eh64->e_ident[EI_DATA]; 386 eh_class = eh64->e_ident[EI_CLASS]; 387 phoff = eh64->e_phoff; 388 shoff = eh64->e_shoff; 389 eh_type = eh64->e_type; 390 eh_version = eh64->e_version; 391 } 392 393 if (eh_version == EV_NONE) 394 eh_version = EV_CURRENT; 395 396 if (eh_version != e->e_version) { /* always EV_CURRENT */ 397 LIBELF_SET_ERROR(VERSION, 0); 398 return ((off_t) -1); 399 } 400 401 if (eh_class != e->e_class) { 402 LIBELF_SET_ERROR(CLASS, 0); 403 return ((off_t) -1); 404 } 405 406 if (e->e_cmd != ELF_C_WRITE && eh_byteorder != e->e_byteorder) { 407 LIBELF_SET_ERROR(HEADER, 0); 408 return ((off_t) -1); 409 } 410 411 shnum = e->e_u.e_elf.e_nscn; 412 phnum = e->e_u.e_elf.e_nphdr; 413 414 e->e_byteorder = eh_byteorder; 415 416#define INITIALIZE_EHDR(E,EC,V) do { \ 417 (E)->e_ident[EI_MAG0] = ELFMAG0; \ 418 (E)->e_ident[EI_MAG1] = ELFMAG1; \ 419 (E)->e_ident[EI_MAG2] = ELFMAG2; \ 420 (E)->e_ident[EI_MAG3] = ELFMAG3; \ 421 (E)->e_ident[EI_CLASS] = (EC); \ 422 (E)->e_ident[EI_VERSION] = (V); \ 423 (E)->e_ehsize = _libelf_fsize(ELF_T_EHDR, (EC), (V), \ 424 (size_t) 1); \ 425 (E)->e_phentsize = (phnum == 0) ? 0 : _libelf_fsize( \ 426 ELF_T_PHDR, (EC), (V), (size_t) 1); \ 427 (E)->e_shentsize = _libelf_fsize(ELF_T_SHDR, (EC), (V), \ 428 (size_t) 1); \ 429 } while (0) 430 431 if (ec == ELFCLASS32) 432 INITIALIZE_EHDR(eh32, ec, eh_version); 433 else 434 INITIALIZE_EHDR(eh64, ec, eh_version); 435 436 (void) elf_flagehdr(e, ELF_C_SET, ELF_F_DIRTY); 437 438 rc += _libelf_fsize(ELF_T_EHDR, ec, eh_version, (size_t) 1); 439 440 /* 441 * Compute the layout the program header table, if one is 442 * present. The program header table needs to be aligned to a 443 * `natural' boundary. 444 */ 445 if (phnum) { 446 fsz = _libelf_fsize(ELF_T_PHDR, ec, eh_version, phnum); 447 align = _libelf_falign(ELF_T_PHDR, ec); 448 449 if (e->e_flags & ELF_F_LAYOUT) { 450 /* 451 * Check offsets for sanity. 452 */ 453 if (rc > phoff) { 454 LIBELF_SET_ERROR(HEADER, 0); 455 return ((off_t) -1); 456 } 457 458 if (phoff % align) { 459 LIBELF_SET_ERROR(LAYOUT, 0); 460 return ((off_t) -1); 461 } 462 463 } else 464 phoff = roundup(rc, align); 465 466 rc = phoff + fsz; 467 } else 468 phoff = 0; 469 470 /* 471 * Compute the layout of the sections associated with the 472 * file. 473 */ 474 475 if ((rc = _libelf_resync_sections(e, rc)) < 0) 476 return ((off_t) -1); 477 478 /* 479 * Compute the space taken up by the section header table, if 480 * one is needed. If ELF_F_LAYOUT is asserted, the 481 * application may have placed the section header table in 482 * between existing sections, so the net size of the file need 483 * not increase due to the presence of the section header 484 * table. 485 */ 486 if (shnum) { 487 fsz = _libelf_fsize(ELF_T_SHDR, ec, eh_version, (size_t) 1); 488 align = _libelf_falign(ELF_T_SHDR, ec); 489 490 if (e->e_flags & ELF_F_LAYOUT) { 491 if (shoff % align) { 492 LIBELF_SET_ERROR(LAYOUT, 0); 493 return ((off_t) -1); 494 } 495 } else 496 shoff = roundup(rc, align); 497 498 if (shoff + fsz * shnum > (size_t) rc) 499 rc = shoff + fsz * shnum; 500 } else 501 shoff = 0; 502 503 /* 504 * Set the fields of the Executable Header that could potentially use 505 * extended numbering. 506 */ 507 _libelf_setphnum(e, ehdr, ec, phnum); 508 _libelf_setshnum(e, ehdr, ec, shnum); 509 510 /* 511 * Update the `e_phoff' and `e_shoff' fields if the library is 512 * doing the layout. 513 */ 514 if ((e->e_flags & ELF_F_LAYOUT) == 0) { 515 if (ec == ELFCLASS32) { 516 eh32->e_phoff = (uint32_t) phoff; 517 eh32->e_shoff = (uint32_t) shoff; 518 } else { 519 eh64->e_phoff = (uint64_t) phoff; 520 eh64->e_shoff = (uint64_t) shoff; 521 } 522 } 523 524 return (rc); 525} 526 527/* 528 * Write out the contents of a section. 529 */ 530 531static off_t 532_libelf_write_scn(Elf *e, char *nf, Elf_Scn *s, off_t rc) 533{ 534 int ec; 535 size_t fsz, msz, nobjects; 536 uint32_t sh_type; 537 uint64_t sh_off; 538 int elftype; 539 Elf_Data *d, dst; 540 541 if ((ec = e->e_class) == ELFCLASS32) 542 sh_type = s->s_shdr.s_shdr32.sh_type; 543 else 544 sh_type = s->s_shdr.s_shdr64.sh_type; 545 546 /* 547 * Ignore sections that do not allocate space in the file. 548 */ 549 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL) 550 return (rc); 551 552 553 elftype = _libelf_xlate_shtype(sh_type); 554 assert(elftype >= ELF_T_FIRST && elftype <= ELF_T_LAST); 555 556 msz = _libelf_msize(elftype, ec, e->e_version); 557 558 sh_off = s->s_offset; 559 assert(sh_off % _libelf_falign(elftype, ec) == 0); 560 561 /* 562 * If the section has a `rawdata' descriptor, and the section 563 * contents have not been modified, use its contents directly. 564 * The `s_rawoff' member contains the offset into the original 565 * file, while `s_offset' contains its new location in the 566 * destination. 567 */ 568 569 if (STAILQ_EMPTY(&s->s_data)) { 570 571 if ((d = elf_rawdata(s, NULL)) == NULL) 572 return ((off_t) -1); 573 574 STAILQ_FOREACH(d, &s->s_rawdata, d_next) { 575 if ((uint64_t) rc < sh_off + d->d_off) 576 (void) memset(nf + rc, 577 LIBELF_PRIVATE(fillchar), sh_off + 578 d->d_off - rc); 579 rc = sh_off + d->d_off; 580 581 assert(d->d_buf != NULL); 582 assert(d->d_type == ELF_T_BYTE); 583 assert(d->d_version == e->e_version); 584 585 (void) memcpy(nf + rc, 586 e->e_rawfile + s->s_rawoff + d->d_off, d->d_size); 587 588 rc += d->d_size; 589 } 590 591 return (rc); 592 } 593 594 /* 595 * Iterate over the set of data descriptors for this section. 596 * The prior call to _libelf_resync_elf() would have setup the 597 * descriptors for this step. 598 */ 599 600 dst.d_version = e->e_version; 601 602 STAILQ_FOREACH(d, &s->s_data, d_next) { 603 604 if ((uint64_t) rc < sh_off + d->d_off) 605 (void) memset(nf + rc, 606 LIBELF_PRIVATE(fillchar), sh_off + d->d_off - rc); 607 608 rc = sh_off + d->d_off; 609 610 assert(d->d_buf != NULL); 611 assert(d->d_type == (Elf_Type) elftype); 612 assert(d->d_version == e->e_version); 613 assert(d->d_size % msz == 0); 614 615 nobjects = d->d_size / msz; 616 617 fsz = _libelf_fsize(elftype, ec, e->e_version, nobjects); 618 619 dst.d_buf = nf + rc; 620 dst.d_size = fsz; 621 622 if (_libelf_xlate(&dst, d, e->e_byteorder, ec, ELF_TOFILE) == 623 NULL) 624 return ((off_t) -1); 625 626 rc += fsz; 627 } 628 629 return ((off_t) rc); 630} 631 632/* 633 * Write out the file image. 634 * 635 * The original file could have been mapped in with an ELF_C_RDWR 636 * command and the application could have added new content or 637 * re-arranged its sections before calling elf_update(). Consequently 638 * its not safe to work `in place' on the original file. So we 639 * malloc() the required space for the updated ELF object and build 640 * the object there and write it out to the underlying file at the 641 * end. Note that the application may have opened the underlying file 642 * in ELF_C_RDWR and only retrieved/modified a few sections. We take 643 * care to avoid translating file sections unnecessarily. 644 * 645 * Gaps in the coverage of the file by the file's sections will be 646 * filled with the fill character set by elf_fill(3). 647 */ 648 649static off_t 650_libelf_write_elf(Elf *e, off_t newsize) 651{ 652 int ec; 653 off_t maxrc, rc; 654 size_t fsz, msz, phnum, shnum; 655 uint64_t phoff, shoff; 656 void *ehdr; 657 char *newfile; 658 Elf_Data dst, src; 659 Elf_Scn *scn, *tscn; 660 Elf32_Ehdr *eh32; 661 Elf64_Ehdr *eh64; 662 663 assert(e->e_kind == ELF_K_ELF); 664 assert(e->e_cmd != ELF_C_READ); 665 assert(e->e_fd >= 0); 666 667 if ((newfile = malloc((size_t) newsize)) == NULL) { 668 LIBELF_SET_ERROR(RESOURCE, errno); 669 return ((off_t) -1); 670 } 671 672 ec = e->e_class; 673 674 ehdr = _libelf_ehdr(e, ec, 0); 675 assert(ehdr != NULL); 676 677 phnum = e->e_u.e_elf.e_nphdr; 678 679 if (ec == ELFCLASS32) { 680 eh32 = (Elf32_Ehdr *) ehdr; 681 682 phoff = (uint64_t) eh32->e_phoff; 683 shnum = eh32->e_shnum; 684 shoff = (uint64_t) eh32->e_shoff; 685 } else { 686 eh64 = (Elf64_Ehdr *) ehdr; 687 688 phoff = eh64->e_phoff; 689 shnum = eh64->e_shnum; 690 shoff = eh64->e_shoff; 691 } 692 693 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); 694 msz = _libelf_msize(ELF_T_EHDR, ec, e->e_version); 695 696 (void) memset(&dst, 0, sizeof(dst)); 697 (void) memset(&src, 0, sizeof(src)); 698 699 src.d_buf = ehdr; 700 src.d_size = msz; 701 src.d_type = ELF_T_EHDR; 702 src.d_version = dst.d_version = e->e_version; 703 704 rc = 0; 705 706 dst.d_buf = newfile + rc; 707 dst.d_size = fsz; 708 709 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) == 710 NULL) 711 goto error; 712 713 rc += fsz; 714 715 /* 716 * Write the program header table if present. 717 */ 718 719 if (phnum != 0 && phoff != 0) { 720 assert((unsigned) rc <= phoff); 721 722 fsz = _libelf_fsize(ELF_T_PHDR, ec, e->e_version, phnum); 723 724 assert(phoff % _libelf_falign(ELF_T_PHDR, ec) == 0); 725 assert(fsz > 0); 726 727 src.d_version = dst.d_version = e->e_version; 728 src.d_type = ELF_T_PHDR; 729 730 if (ec == ELFCLASS32) 731 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr32; 732 else 733 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr64; 734 735 src.d_size = phnum * _libelf_msize(ELF_T_PHDR, ec, 736 e->e_version); 737 738 dst.d_size = fsz; 739 740 if ((uint64_t) rc < phoff) 741 (void) memset(newfile + rc, 742 LIBELF_PRIVATE(fillchar), phoff - rc); 743 744 dst.d_buf = newfile + rc; 745 746 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) == 747 NULL) 748 goto error; 749 750 rc = phoff + fsz; 751 } 752 753 /* 754 * Write out individual sections. 755 */ 756 757 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) 758 if ((rc = _libelf_write_scn(e, newfile, scn, rc)) < 0) 759 goto error; 760 761 /* 762 * Write out the section header table, if required. Note that 763 * if flag ELF_F_LAYOUT has been set the section header table 764 * could reside in between byte ranges mapped by section 765 * descriptors. 766 */ 767 if (shnum != 0 && shoff != 0) { 768 if ((uint64_t) rc < shoff) 769 (void) memset(newfile + rc, 770 LIBELF_PRIVATE(fillchar), shoff - rc); 771 772 maxrc = rc; 773 rc = shoff; 774 775 assert(rc % _libelf_falign(ELF_T_SHDR, ec) == 0); 776 777 src.d_type = ELF_T_SHDR; 778 src.d_size = _libelf_msize(ELF_T_SHDR, ec, e->e_version); 779 src.d_version = dst.d_version = e->e_version; 780 781 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1); 782 783 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) { 784 if (ec == ELFCLASS32) 785 src.d_buf = &scn->s_shdr.s_shdr32; 786 else 787 src.d_buf = &scn->s_shdr.s_shdr64; 788 789 dst.d_size = fsz; 790 dst.d_buf = newfile + rc + scn->s_ndx * fsz; 791 792 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, 793 ELF_TOFILE) != &dst) 794 goto error; 795 } 796 797 rc += e->e_u.e_elf.e_nscn * fsz; 798 if (maxrc > rc) 799 rc = maxrc; 800 } 801 802 assert(rc == newsize); 803 804 /* 805 * Write out the constructed contents and remap the file in 806 * read-only. 807 */ 808 809 if (e->e_rawfile && munmap(e->e_rawfile, e->e_rawsize) < 0) { 810 LIBELF_SET_ERROR(IO, errno); 811 goto error; 812 } 813 814 if (write(e->e_fd, newfile, (size_t) newsize) != newsize || 815 lseek(e->e_fd, (off_t) 0, SEEK_SET) < 0) { 816 LIBELF_SET_ERROR(IO, errno); 817 goto error; 818 } 819 820 if (e->e_cmd != ELF_C_WRITE) { 821 if ((e->e_rawfile = mmap(NULL, (size_t) newsize, PROT_READ, 822 MAP_PRIVATE, e->e_fd, (off_t) 0)) == MAP_FAILED) { 823 LIBELF_SET_ERROR(IO, errno); 824 goto error; 825 } 826 e->e_rawsize = newsize; 827 } 828 829 /* 830 * Reset flags, remove existing section descriptors and 831 * {E,P}HDR pointers so that a subsequent elf_get{e,p}hdr() 832 * and elf_getscn() will function correctly. 833 */ 834 835 e->e_flags &= ~ELF_F_DIRTY; 836 837 STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next, tscn) 838 _libelf_release_scn(scn); 839 840 if (ec == ELFCLASS32) { 841 free(e->e_u.e_elf.e_ehdr.e_ehdr32); 842 if (e->e_u.e_elf.e_phdr.e_phdr32) 843 free(e->e_u.e_elf.e_phdr.e_phdr32); 844 845 e->e_u.e_elf.e_ehdr.e_ehdr32 = NULL; 846 e->e_u.e_elf.e_phdr.e_phdr32 = NULL; 847 } else { 848 free(e->e_u.e_elf.e_ehdr.e_ehdr64); 849 if (e->e_u.e_elf.e_phdr.e_phdr64) 850 free(e->e_u.e_elf.e_phdr.e_phdr64); 851 852 e->e_u.e_elf.e_ehdr.e_ehdr64 = NULL; 853 e->e_u.e_elf.e_phdr.e_phdr64 = NULL; 854 } 855 856 return (rc); 857 858 error: 859 if (newfile) 860 free(newfile); 861 return ((off_t) -1); 862} 863 864off_t 865elf_update(Elf *e, Elf_Cmd c) 866{ 867 int ec; 868 off_t rc; 869 870 rc = (off_t) -1; 871 872 if (e == NULL || e->e_kind != ELF_K_ELF || 873 (c != ELF_C_NULL && c != ELF_C_WRITE)) { 874 LIBELF_SET_ERROR(ARGUMENT, 0); 875 return (rc); 876 } 877 878 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) { 879 LIBELF_SET_ERROR(CLASS, 0); 880 return (rc); 881 } 882 883 if (e->e_version == EV_NONE) 884 e->e_version = EV_CURRENT; 885 886 if (c == ELF_C_WRITE && e->e_cmd == ELF_C_READ) { 887 LIBELF_SET_ERROR(MODE, 0); 888 return (rc); 889 } 890 891 if ((rc = _libelf_resync_elf(e)) < 0) 892 return (rc); 893 894 if (c == ELF_C_NULL) 895 return (rc); 896 897 if (e->e_cmd == ELF_C_READ) { 898 /* 899 * This descriptor was opened in read-only mode or by 900 * elf_memory(). 901 */ 902 if (e->e_fd) 903 LIBELF_SET_ERROR(MODE, 0); 904 else 905 LIBELF_SET_ERROR(ARGUMENT, 0); 906 return ((off_t) -1); 907 } 908 909 if (e->e_fd < 0) { 910 LIBELF_SET_ERROR(SEQUENCE, 0); 911 return ((off_t) -1); 912 } 913 914 return (_libelf_write_elf(e, rc)); 915} 916