1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright (c) 1988 AT&T 24 * All Rights Reserved 25 * 26 * 27 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 28 * Use is subject to license terms. 29 */ 30 #pragma ident "%Z%%M% %I% %E% SMI" 31 32 /* 33 * This file contains the functions responsible for opening the output file 34 * image, associating the appropriate input elf structures with the new image, 35 * and obtaining new elf structures to define the new image. 36 */ 37 #include <stdio.h> 38 #include <sys/stat.h> 39 #include <fcntl.h> 40 #include <link.h> 41 #include <errno.h> 42 #include <string.h> 43 #include <limits.h> 44 #include "msg.h" 45 #include "_libld.h" 46 #include <debug.h> 47 48 /* 49 * Open the output file and insure the correct access modes. 50 */ 51 uintptr_t 52 open_outfile(Ofl_desc * ofl) 53 { 54 mode_t mask, mode; 55 struct stat status; 56 int exists = 0; 57 58 /* 59 * Determine the required file mode from the type of output file we 60 * are creating. 61 */ 62 if (ofl->ofl_flags & (FLG_OF_EXEC | FLG_OF_SHAROBJ)) 63 mode = 0777; 64 else 65 mode = 0666; 66 67 /* 68 * Determine if the output file already exists. 69 */ 70 if (stat(ofl->ofl_name, &status) == 0) 71 exists++; 72 73 /* 74 * Open (or create) the output file name (ofl_fd acts as a global 75 * flag to ldexit() signifying whether the output file should be 76 * removed or not on error). 77 */ 78 if ((ofl->ofl_fd = open(ofl->ofl_name, O_RDWR | O_CREAT | O_TRUNC, 79 mode)) < 0) { 80 int err = errno; 81 82 eprintf(ERR_FATAL, MSG_INTL(MSG_SYS_OPEN), ofl->ofl_name, 83 strerror(err)); 84 return (S_ERROR); 85 } 86 87 /* 88 * If we've just created this file the modes will be fine, however if 89 * the file had already existed make sure the modes are correct. 90 */ 91 if (exists) { 92 /* 93 * If the output file is not a regular file, don't change the 94 * mode, or allow it to be deleted. This allows root users to 95 * specify /dev/null output file for verification links. 96 */ 97 if ((status.st_mode & S_IFMT) != S_IFREG) { 98 ofl->ofl_flags1 |= FLG_OF1_NONREG; 99 } else { 100 mask = umask(0); 101 (void) umask(mask); 102 (void) chmod(ofl->ofl_name, mode & ~mask); 103 } 104 } 105 106 return (1); 107 } 108 109 110 /* 111 * If we are creating a memory model we need to update the present memory image. 112 * First we need to call elf_update(ELF_C_NULL) which will calculate the offsets 113 * of each section and its associated data buffers. From this information we 114 * can then determine what padding is required. 115 * Two actions are necessary to convert the present disc image into a memory 116 * image: 117 * 118 * o Loadable segments must be padded so that the next segments virtual 119 * address and file offset are the same. 120 * 121 * o NOBITS sections must be converted into allocated, null filled sections. 122 */ 123 uintptr_t 124 pad_outfile(Ofl_desc * ofl) 125 { 126 Listnode * lnp1, * lnp2; 127 off_t offset; 128 Elf_Scn * oscn = 0; 129 Sg_desc * sgp; 130 Os_desc * osp; 131 Ehdr * ehdr; 132 133 /* 134 * Update all the elf structures. This will assign offsets to the 135 * section headers and data buffers as they relate to the new image. 136 */ 137 if (elf_update(ofl->ofl_welf, ELF_C_NULL) == -1) { 138 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_UPDATE), ofl->ofl_name); 139 return (S_ERROR); 140 } 141 if ((ehdr = elf_getehdr(ofl->ofl_welf)) == NULL) { 142 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR), ofl->ofl_name); 143 return (S_ERROR); 144 } 145 146 /* 147 * Initialize the offset by skipping the Elf header and program 148 * headers. 149 */ 150 offset = ehdr->e_phoff + (ehdr->e_phnum * ehdr->e_phentsize); 151 152 /* 153 * Traverse the segment list looking for loadable segments. 154 */ 155 for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) { 156 Phdr * phdr = &(sgp->sg_phdr); 157 158 /* 159 * If we've already processed a loadable segment, the `scn' 160 * variable will be initialized to the last section that was 161 * part of that segment. Add sufficient padding to this section 162 * to cause the next segments virtual address and file offset to 163 * be the same. 164 */ 165 if (oscn && (phdr->p_type == PT_LOAD)) { 166 Elf_Data * data; 167 size_t size; 168 169 size = (size_t)(S_ROUND(offset, phdr->p_align) - 170 offset); 171 172 if ((data = elf_newdata(oscn)) == NULL) { 173 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_NEWDATA), 174 ofl->ofl_name); 175 return (S_ERROR); 176 } 177 if ((data->d_buf = libld_calloc(size, 1)) == 0) 178 return (S_ERROR); 179 180 data->d_type = ELF_T_BYTE; 181 data->d_size = size; 182 data->d_align = 1; 183 data->d_version = ofl->ofl_libver; 184 } 185 186 /* 187 * Traverse the output sections for this segment calculating the 188 * offset of each section. Retain the final section descriptor 189 * as this will be where any padding buffer will be added. 190 */ 191 for (LIST_TRAVERSE(&(sgp->sg_osdescs), lnp2, osp)) { 192 Shdr * shdr = osp->os_shdr; 193 194 offset = (off_t)S_ROUND(offset, shdr->sh_addralign); 195 offset += shdr->sh_size; 196 197 /* 198 * If this is a NOBITS output section convert all of 199 * its associated input sections into real, null filled, 200 * data buffers, and change the section to PROGBITS. 201 */ 202 if (shdr->sh_type == SHT_NOBITS) 203 shdr->sh_type = SHT_PROGBITS; 204 } 205 206 /* 207 * If this is a loadable segment retain the last output section 208 * descriptor. This acts both as a flag that a loadable 209 * segment has been seen, and as the segment to which a padding 210 * buffer will be added. 211 */ 212 if (phdr->p_type == PT_LOAD) 213 oscn = osp->os_scn; 214 } 215 return (1); 216 } 217 218 219 /* 220 * Create the elf structures that allow the input data to be associated with the 221 * new image: 222 * 223 * o define the new elf image using elf_begin(), 224 * 225 * o obtain an elf header for the image, 226 * 227 * o traverse the input segments and create a program header array 228 * to define the required segments, 229 * 230 * o traverse the output sections for each segment assigning a new 231 * section descriptor and section header for each, 232 * 233 * o traverse the input sections associated with each output section 234 * and assign a new data descriptor to each (each output section 235 * becomes a linked list of input data buffers). 236 */ 237 uintptr_t 238 create_outfile(Ofl_desc * ofl) 239 { 240 Listnode * lnp1, * lnp2, * lnp3; 241 Sg_desc * sgp; 242 Os_desc * osp; 243 Is_desc * isp; 244 Elf_Scn * scn; 245 Shdr * shdr; 246 Word ptype, flags = ofl->ofl_flags; 247 size_t ndx = 0, fndx = 0; 248 Elf_Cmd cmd; 249 Boolean fixalign = FALSE; 250 int fd, nseg = 0, shidx = 0, dataidx = 0, ptloadidx = 0, 251 tlsidx = 0; 252 253 /* 254 * If FLG_OF1_NOHDR was set in map_parse() or FLG_OF1_VADDR was set, 255 * we need to do alignment adjustment. 256 */ 257 if (ofl->ofl_flags1 & (FLG_OF1_NOHDR | FLG_OF1_VADDR)) { 258 fixalign = TRUE; 259 } 260 261 if (flags & FLG_OF_MEMORY) { 262 cmd = ELF_C_IMAGE; 263 fd = 0; 264 } else { 265 fd = ofl->ofl_fd; 266 cmd = ELF_C_WRITE; 267 } 268 269 /* 270 * If there are any ordered section, handle them here. 271 */ 272 if ((ofl->ofl_ordered.head != NULL) && (sort_ordered(ofl) == S_ERROR)) 273 return (S_ERROR); 274 275 /* 276 * Tell the access library about our new temporary file. 277 */ 278 if ((ofl->ofl_welf = elf_begin(fd, cmd, 0)) == NULL) { 279 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_BEGIN), ofl->ofl_name); 280 return (S_ERROR); 281 } 282 283 /* 284 * Obtain a new Elf header. 285 */ 286 if ((ofl->ofl_ehdr = elf_newehdr(ofl->ofl_welf)) == NULL) { 287 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_NEWEHDR), ofl->ofl_name); 288 return (S_ERROR); 289 } 290 ofl->ofl_ehdr->e_machine = ofl->ofl_e_machine; 291 292 DBG_CALL(Dbg_util_nl()); 293 for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) { 294 /* 295 * Count the number of segments that will go in the program 296 * header table. If a segment is empty, ignore it. 297 */ 298 int frst = 0; 299 Phdr * phdr = &(sgp->sg_phdr); 300 301 ptype = phdr->p_type; 302 303 if (!(flags & FLG_OF_RELOBJ)) { 304 if (ptype == PT_PHDR) { 305 /* 306 * If we are generating an interp section (and 307 * thus an associated PT_INTERP program header 308 * entry) also generate a PT_PHDR program header 309 * entry. This allows the kernel to generate 310 * the appropriate aux vector entries to pass to 311 * the interpreter (refer to exec/elf/elf.c). 312 * Note that if an image was generated with an 313 * interp section, but no associated PT_PHDR 314 * program header entry, the kernel will simply 315 * pass the interpreter an open file descriptor 316 * when the image is executed). 317 */ 318 if (ofl->ofl_osinterp) 319 nseg++; 320 } else if (ptype == PT_INTERP) { 321 if (ofl->ofl_osinterp) 322 nseg++; 323 } else if (ptype == PT_DYNAMIC) { 324 if (flags & FLG_OF_DYNAMIC) 325 nseg++; 326 } else if (ptype == PT_TLS) { 327 if (ofl->ofl_ostlsseg.head) 328 nseg++; 329 #if (defined(__i386) || defined(__amd64)) && defined(_ELF64) 330 } else if (ptype == PT_SUNW_UNWIND) { 331 if (ofl->ofl_unwindhdr) 332 nseg++; 333 #endif 334 } else if (ptype == PT_SUNWBSS) { 335 if (ofl->ofl_issunwbss) 336 nseg++; 337 } else if (ptype == PT_SUNWSTACK) { 338 nseg++; 339 } else if (ptype == PT_SUNWDTRACE) { 340 if (ofl->ofl_dtracesym) 341 nseg++; 342 } else if (ptype == PT_SUNWCAP) { 343 if (ofl->ofl_oscap) 344 nseg++; 345 } else if ((sgp->sg_osdescs.head) || 346 (sgp->sg_flags & FLG_SG_EMPTY)) { 347 if (ptype != PT_NULL) 348 nseg++; 349 } 350 } 351 352 /* 353 * If the first loadable segment has the ?N flag, 354 * then ?N will be on. 355 */ 356 if ((ptype == PT_LOAD) && (ptloadidx == 0)) { 357 ptloadidx++; 358 if (sgp->sg_flags & FLG_SG_NOHDR) { 359 fixalign = TRUE; 360 ofl->ofl_flags1 |= FLG_OF1_NOHDR; 361 } 362 } 363 364 shidx = 0; 365 for (LIST_TRAVERSE(&(sgp->sg_osdescs), lnp2, osp)) { 366 shidx++; 367 368 /* 369 * Get a section descriptor for the section. 370 */ 371 if ((scn = elf_newscn(ofl->ofl_welf)) == NULL) { 372 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_NEWSCN), 373 ofl->ofl_name); 374 return (S_ERROR); 375 } 376 osp->os_scn = scn; 377 378 /* 379 * Get a new section header table entry and copy the 380 * pertinent information from the in-core descriptor. 381 * As we had originally allocated the section header 382 * (refer place_section()) we might as well free it up. 383 */ 384 if ((shdr = elf_getshdr(scn)) == NULL) { 385 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETSHDR), 386 ofl->ofl_name); 387 return (S_ERROR); 388 } 389 *shdr = *(osp->os_shdr); 390 391 if ((fixalign == TRUE) && (ptype == PT_LOAD) && 392 (shidx == 1)) 393 sgp->sg_fscn = scn; 394 395 osp->os_shdr = shdr; 396 397 /* 398 * Knock off the SHF_ORDERED & SHF_LINK_ORDER flags. 399 */ 400 osp->os_shdr->sh_flags &= ~ALL_SHF_ORDER; 401 402 /* 403 * If we are not building a RELOBJ - we strip 404 * off the SHF_GROUP flag (if present). 405 */ 406 if ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0) 407 osp->os_shdr->sh_flags &= ~SHF_GROUP; 408 409 dataidx = 0; 410 for (LIST_TRAVERSE(&(osp->os_isdescs), lnp3, isp)) { 411 Elf_Data * data; 412 Ifl_desc * ifl = isp->is_file; 413 414 /* 415 * At this point we know whether a section has 416 * been referenced. If it hasn't, and the whole 417 * file hasn't been referenced (which would have 418 * been caught in ignore_section_processing()), 419 * give a diagnostic (-D unused,detail) or 420 * discard the section if -zignore is in effect. 421 */ 422 if (ifl && 423 (((ifl->ifl_flags & FLG_IF_FILEREF) == 0) || 424 ((ptype == PT_LOAD) && 425 ((isp->is_flags & FLG_IS_SECTREF) == 0) && 426 (isp->is_shdr->sh_size > 0)))) { 427 if (ifl->ifl_flags & FLG_IF_IGNORE) { 428 isp->is_flags |= FLG_IS_DISCARD; 429 DBG_CALL(Dbg_unused_sec(isp)); 430 continue; 431 } else 432 DBG_CALL(Dbg_unused_sec(isp)); 433 } 434 435 dataidx++; 436 437 /* 438 * If this section provides no data, and isn't 439 * referenced, then it can be discarded as well. 440 * Note, if this is the first input section 441 * associated to an output section, let it 442 * through, there may be a legitimate reason why 443 * the user wants a null section. Discarding 444 * additional sections is intended to remove the 445 * empty clutter the compilers have a habit of 446 * creating. Don't provide an unused diagnostic 447 * as these sections aren't typically the users 448 * creation. 449 */ 450 if (ifl && dataidx && 451 ((isp->is_flags & FLG_IS_SECTREF) == 0) && 452 (isp->is_shdr->sh_size == 0)) { 453 isp->is_flags |= FLG_IS_DISCARD; 454 continue; 455 } 456 457 /* 458 * Create new output data buffers for each of 459 * the input data buffers, thus linking the new 460 * buffers to the new elf output structures. 461 * Simply make the new data buffers point to 462 * the old data. 463 */ 464 if ((data = elf_newdata(scn)) == NULL) { 465 eprintf(ERR_ELF, 466 MSG_INTL(MSG_ELF_NEWDATA), 467 ofl->ofl_name); 468 return (S_ERROR); 469 } 470 *data = *(isp->is_indata); 471 472 if ((fixalign == TRUE) && (ptype == PT_LOAD) && 473 (shidx == 1) && (dataidx == 1)) { 474 data->d_align = sgp->sg_addralign; 475 } 476 isp->is_indata = data; 477 478 /* 479 * Make sure that the first tls section is 480 * aligned on pointer size alignment. 481 */ 482 if ((tlsidx == 0) && 483 ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0) && 484 (isp->is_shdr->sh_flags & SHF_TLS)) { 485 data->d_align = lcm(M_WORD_ALIGN, 486 isp->is_shdr->sh_addralign); 487 tlsidx = 1; 488 } 489 490 #if defined(_ELF64) && defined(_ILP32) 491 /* 492 * 4106312, the 32-bit ELF64 version of ld 493 * needs to be able to create large .bss 494 * sections. The d_size member of Elf_Data 495 * only allows 32-bits in _ILP32, so we build 496 * multiple data-items that each fit into 32- 497 * bits. libelf (4106398) can summ these up 498 * into a 64-bit quantity. This only works 499 * for NOBITS sections which don't have any 500 * real data to maintain and don't require 501 * large file support. 502 */ 503 if (isp->is_shdr->sh_type == SHT_NOBITS) { 504 Xword sz = isp->is_shdr->sh_size; 505 506 while (sz >> 32) { 507 data->d_size = SIZE_MAX; 508 sz -= (Xword)SIZE_MAX; 509 if ((data = 510 elf_newdata(scn)) == NULL) 511 return (S_ERROR); 512 } 513 data->d_size = (size_t)sz; 514 } 515 #endif 516 517 /* 518 * If this segment requires rounding realign the 519 * first data buffer associated with the first 520 * section. 521 */ 522 if ((frst++ == 0) && 523 (sgp->sg_flags & FLG_SG_ROUND)) { 524 Xword align; 525 526 if (data->d_align) 527 align = (Xword) 528 S_ROUND(data->d_align, 529 sgp->sg_round); 530 else 531 align = sgp->sg_round; 532 533 data->d_align = (size_t)align; 534 } 535 } 536 537 /* 538 * Clear the szoutrels counter so that it can be used 539 * again in the building of relocs. See machrel.c. 540 */ 541 osp->os_szoutrels = 0; 542 } 543 } 544 545 /* 546 * Build an empty PHDR. 547 */ 548 if (nseg) { 549 if ((ofl->ofl_phdr = elf_newphdr(ofl->ofl_welf, 550 nseg)) == NULL) { 551 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_NEWPHDR), 552 ofl->ofl_name); 553 return (S_ERROR); 554 } 555 } 556 557 /* 558 * If we need to generate a memory model, pad the image. 559 */ 560 if (flags & FLG_OF_MEMORY) { 561 if (pad_outfile(ofl) == S_ERROR) 562 return (S_ERROR); 563 } 564 565 /* 566 * After all the basic input file processing, all data pointers are 567 * referencing two types of memory: 568 * 569 * o allocated memory, ie. elf structures, internal link 570 * editor structures, and any new sections that have been 571 * created. 572 * 573 * o original input file mmap'ed memory, ie. the actual data 574 * sections of the input file images. 575 * 576 * Up until now, the only memory modifications have been carried out on 577 * the allocated memory. Before carrying out any relocations, write the 578 * new output file image and reassign any necessary data pointers to the 579 * output files memory image. This insures that any relocation 580 * modifications are made to the output file image and not to the input 581 * file image, thus preventing the creation of dirty pages and reducing 582 * the overall swap space requirement. 583 * 584 * Write out the elf structure so as to create the new file image. 585 */ 586 if ((ofl->ofl_size = (size_t)elf_update(ofl->ofl_welf, 587 ELF_C_WRIMAGE)) == (size_t)-1) { 588 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_UPDATE), ofl->ofl_name); 589 return (S_ERROR); 590 } 591 592 /* 593 * Initialize the true `ofl' information with the memory images address 594 * and size. This will be used to write() out the image once any 595 * relocation processing has been completed. We also use this image 596 * information to setup a new Elf descriptor, which is used to obtain 597 * all the necessary elf pointers within the new output image. 598 */ 599 if ((ofl->ofl_elf = elf_begin(0, ELF_C_IMAGE, 600 ofl->ofl_welf)) == NULL) { 601 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_BEGIN), ofl->ofl_name); 602 return (S_ERROR); 603 } 604 if ((ofl->ofl_ehdr = elf_getehdr(ofl->ofl_elf)) == NULL) { 605 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR), ofl->ofl_name); 606 return (S_ERROR); 607 } 608 if (!(flags & FLG_OF_RELOBJ)) 609 if ((ofl->ofl_phdr = elf_getphdr(ofl->ofl_elf)) == NULL) { 610 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETPHDR), 611 ofl->ofl_name); 612 return (S_ERROR); 613 } 614 615 /* 616 * Reinitialize the section descriptors, section headers and obtain new 617 * output data buffer pointers (these will be used to perform any 618 * relocations). 619 */ 620 for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) { 621 Phdr * _phdr = &(sgp->sg_phdr); 622 Boolean recorded = FALSE; 623 624 for (LIST_TRAVERSE(&(sgp->sg_osdescs), lnp2, osp)) { 625 if ((osp->os_scn = elf_getscn(ofl->ofl_elf, ++ndx)) == 626 NULL) { 627 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETSCN), 628 ofl->ofl_name, ndx); 629 return (S_ERROR); 630 } 631 if ((osp->os_shdr = elf_getshdr(osp->os_scn)) == 632 NULL) { 633 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETSHDR), 634 ofl->ofl_name); 635 return (S_ERROR); 636 } 637 if ((fixalign == TRUE) && (sgp->sg_fscn != 0) && 638 (recorded == FALSE)) { 639 Elf_Scn *scn; 640 641 scn = sgp->sg_fscn; 642 if ((fndx = elf_ndxscn(scn)) == SHN_UNDEF) { 643 eprintf(ERR_ELF, 644 MSG_INTL(MSG_ELF_NDXSCN), 645 ofl->ofl_name); 646 return (S_ERROR); 647 } 648 if (ndx == fndx) { 649 sgp->sg_fscn = osp->os_scn; 650 recorded = TRUE; 651 } 652 } 653 654 if ((osp->os_outdata = 655 elf_getdata(osp->os_scn, NULL)) == NULL) { 656 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETDATA), 657 ofl->ofl_name); 658 return (S_ERROR); 659 } 660 661 /* 662 * If this section is part of a loadable segment insure 663 * that the segments alignment is appropriate. 664 */ 665 if (_phdr->p_type == PT_LOAD) { 666 _phdr->p_align = (Xword)lcm(_phdr->p_align, 667 osp->os_shdr->sh_addralign); 668 } 669 } 670 } 671 return (1); 672 } 673