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 2005 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 Elf_Data * tlsdata = 0; 246 Shdr * shdr; 247 Word flags = ofl->ofl_flags; 248 size_t ndx = 0, fndx = 0; 249 Elf_Cmd cmd; 250 Boolean fixalign = FALSE; 251 int fd, nseg = 0, shidx = 0, dataidx = 0, ptloadidx = 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 int frst = 0; 295 Phdr *phdr = &(sgp->sg_phdr); 296 Word ptype = phdr->p_type; 297 298 /* 299 * Count the number of segments that will go in the program 300 * header table. If a segment is empty, ignore it. 301 */ 302 if (!(flags & FLG_OF_RELOBJ)) { 303 if (ptype == PT_PHDR) { 304 /* 305 * If we are generating an interp section (and 306 * thus an associated PT_INTERP program header 307 * entry) also generate a PT_PHDR program header 308 * entry. This allows the kernel to generate 309 * the appropriate aux vector entries to pass to 310 * the interpreter (refer to exec/elf/elf.c). 311 * Note that if an image was generated with an 312 * interp section, but no associated PT_PHDR 313 * program header entry, the kernel will simply 314 * pass the interpreter an open file descriptor 315 * when the image is executed). 316 */ 317 if (ofl->ofl_osinterp) 318 nseg++; 319 } else if (ptype == PT_INTERP) { 320 if (ofl->ofl_osinterp) 321 nseg++; 322 } else if (ptype == PT_DYNAMIC) { 323 if (flags & FLG_OF_DYNAMIC) 324 nseg++; 325 } else if (ptype == PT_TLS) { 326 if (flags & FLG_OF_TLSPHDR) 327 nseg++; 328 #if (defined(__i386) || defined(__amd64)) && defined(_ELF64) 329 } else if (ptype == PT_SUNW_UNWIND) { 330 if (ofl->ofl_unwindhdr) 331 nseg++; 332 #endif 333 } else if (ptype == PT_SUNWBSS) { 334 if (ofl->ofl_issunwbss) 335 nseg++; 336 } else if (ptype == PT_SUNWSTACK) { 337 nseg++; 338 } else if (ptype == PT_SUNWDTRACE) { 339 if (ofl->ofl_dtracesym) 340 nseg++; 341 } else if (ptype == PT_SUNWCAP) { 342 if (ofl->ofl_oscap) 343 nseg++; 344 } else if ((sgp->sg_osdescs.head) || 345 (sgp->sg_flags & FLG_SG_EMPTY)) { 346 if (ptype != PT_NULL) 347 nseg++; 348 } 349 } 350 351 /* 352 * If the first loadable segment has the ?N flag, 353 * then ?N will be on. 354 */ 355 if ((ptype == PT_LOAD) && (ptloadidx == 0)) { 356 ptloadidx++; 357 if (sgp->sg_flags & FLG_SG_NOHDR) { 358 fixalign = TRUE; 359 ofl->ofl_flags1 |= FLG_OF1_NOHDR; 360 } 361 } 362 363 shidx = 0; 364 for (LIST_TRAVERSE(&(sgp->sg_osdescs), lnp2, osp)) { 365 shidx++; 366 367 /* 368 * Get a section descriptor for the section. 369 */ 370 if ((scn = elf_newscn(ofl->ofl_welf)) == NULL) { 371 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_NEWSCN), 372 ofl->ofl_name); 373 return (S_ERROR); 374 } 375 osp->os_scn = scn; 376 377 /* 378 * Get a new section header table entry and copy the 379 * pertinent information from the in-core descriptor. 380 * As we had originally allocated the section header 381 * (refer place_section()) we might as well free it up. 382 */ 383 if ((shdr = elf_getshdr(scn)) == NULL) { 384 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETSHDR), 385 ofl->ofl_name); 386 return (S_ERROR); 387 } 388 *shdr = *(osp->os_shdr); 389 390 if ((fixalign == TRUE) && (ptype == PT_LOAD) && 391 (shidx == 1)) 392 sgp->sg_fscn = scn; 393 394 osp->os_shdr = shdr; 395 396 /* 397 * Knock off the SHF_ORDERED & SHF_LINK_ORDER flags. 398 */ 399 osp->os_shdr->sh_flags &= ~ALL_SHF_ORDER; 400 401 /* 402 * If we are not building a RELOBJ - we strip 403 * off the SHF_GROUP flag (if present). 404 */ 405 if ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0) 406 osp->os_shdr->sh_flags &= ~SHF_GROUP; 407 408 /* 409 * If this is a TLS section, save it so that the PT_TLS 410 * program header information can be established after 411 * the output image has been initialy created. At this 412 * point, all TLS input sections are ordered as they 413 * will appear in the output image. 414 */ 415 if ((ofl->ofl_flags & FLG_OF_TLSPHDR) && 416 (osp->os_shdr->sh_flags & SHF_TLS)) { 417 if (list_appendc(&ofl->ofl_ostlsseg, osp) == 0) 418 return (S_ERROR); 419 } 420 421 dataidx = 0; 422 for (LIST_TRAVERSE(&(osp->os_isdescs), lnp3, isp)) { 423 Elf_Data * data; 424 Ifl_desc * ifl = isp->is_file; 425 426 /* 427 * At this point we know whether a section has 428 * been referenced. If it hasn't, and the whole 429 * file hasn't been referenced (which would have 430 * been caught in ignore_section_processing()), 431 * give a diagnostic (-D unused,detail) or 432 * discard the section if -zignore is in effect. 433 */ 434 if (ifl && 435 (((ifl->ifl_flags & FLG_IF_FILEREF) == 0) || 436 ((ptype == PT_LOAD) && 437 ((isp->is_flags & FLG_IS_SECTREF) == 0) && 438 (isp->is_shdr->sh_size > 0)))) { 439 if (ifl->ifl_flags & FLG_IF_IGNORE) { 440 isp->is_flags |= FLG_IS_DISCARD; 441 DBG_CALL(Dbg_unused_sec(isp)); 442 continue; 443 } else 444 DBG_CALL(Dbg_unused_sec(isp)); 445 } 446 447 dataidx++; 448 449 /* 450 * If this section provides no data, and isn't 451 * referenced, then it can be discarded as well. 452 * Note, if this is the first input section 453 * associated to an output section, let it 454 * through, there may be a legitimate reason why 455 * the user wants a null section. Discarding 456 * additional sections is intended to remove the 457 * empty clutter the compilers have a habit of 458 * creating. Don't provide an unused diagnostic 459 * as these sections aren't typically the users 460 * creation. 461 */ 462 if (ifl && dataidx && 463 ((isp->is_flags & FLG_IS_SECTREF) == 0) && 464 (isp->is_shdr->sh_size == 0)) { 465 isp->is_flags |= FLG_IS_DISCARD; 466 continue; 467 } 468 469 /* 470 * Create new output data buffers for each of 471 * the input data buffers, thus linking the new 472 * buffers to the new elf output structures. 473 * Simply make the new data buffers point to 474 * the old data. 475 */ 476 if ((data = elf_newdata(scn)) == NULL) { 477 eprintf(ERR_ELF, 478 MSG_INTL(MSG_ELF_NEWDATA), 479 ofl->ofl_name); 480 return (S_ERROR); 481 } 482 *data = *(isp->is_indata); 483 484 if ((fixalign == TRUE) && (ptype == PT_LOAD) && 485 (shidx == 1) && (dataidx == 1)) { 486 data->d_align = sgp->sg_addralign; 487 } 488 isp->is_indata = data; 489 490 /* 491 * Save the first TLS data buffer, as this is 492 * the start of the TLS segment. Realign this 493 * buffer based on the alignment requirements 494 * of all the TLS input sections. 495 */ 496 if ((ofl->ofl_flags & FLG_OF_TLSPHDR) && 497 (isp->is_shdr->sh_flags & SHF_TLS)) { 498 if (tlsdata == 0) 499 tlsdata = data; 500 tlsdata->d_align = lcm(tlsdata->d_align, 501 isp->is_shdr->sh_addralign); 502 } 503 504 #if defined(_ELF64) && defined(_ILP32) 505 /* 506 * 4106312, the 32-bit ELF64 version of ld 507 * needs to be able to create large .bss 508 * sections. The d_size member of Elf_Data 509 * only allows 32-bits in _ILP32, so we build 510 * multiple data-items that each fit into 32- 511 * bits. libelf (4106398) can summ these up 512 * into a 64-bit quantity. This only works 513 * for NOBITS sections which don't have any 514 * real data to maintain and don't require 515 * large file support. 516 */ 517 if (isp->is_shdr->sh_type == SHT_NOBITS) { 518 Xword sz = isp->is_shdr->sh_size; 519 520 while (sz >> 32) { 521 data->d_size = SIZE_MAX; 522 sz -= (Xword)SIZE_MAX; 523 if ((data = 524 elf_newdata(scn)) == NULL) 525 return (S_ERROR); 526 } 527 data->d_size = (size_t)sz; 528 } 529 #endif 530 531 /* 532 * If this segment requires rounding realign the 533 * first data buffer associated with the first 534 * section. 535 */ 536 if ((frst++ == 0) && 537 (sgp->sg_flags & FLG_SG_ROUND)) { 538 Xword align; 539 540 if (data->d_align) 541 align = (Xword) 542 S_ROUND(data->d_align, 543 sgp->sg_round); 544 else 545 align = sgp->sg_round; 546 547 data->d_align = (size_t)align; 548 } 549 } 550 551 /* 552 * Clear the szoutrels counter so that it can be used 553 * again in the building of relocs. See machrel.c. 554 */ 555 osp->os_szoutrels = 0; 556 } 557 } 558 559 /* 560 * Build an empty PHDR. 561 */ 562 if (nseg) { 563 if ((ofl->ofl_phdr = elf_newphdr(ofl->ofl_welf, 564 nseg)) == NULL) { 565 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_NEWPHDR), 566 ofl->ofl_name); 567 return (S_ERROR); 568 } 569 } 570 571 /* 572 * If we need to generate a memory model, pad the image. 573 */ 574 if (flags & FLG_OF_MEMORY) { 575 if (pad_outfile(ofl) == S_ERROR) 576 return (S_ERROR); 577 } 578 579 /* 580 * After all the basic input file processing, all data pointers are 581 * referencing two types of memory: 582 * 583 * o allocated memory, ie. elf structures, internal link 584 * editor structures, and any new sections that have been 585 * created. 586 * 587 * o original input file mmap'ed memory, ie. the actual data 588 * sections of the input file images. 589 * 590 * Up until now, the only memory modifications have been carried out on 591 * the allocated memory. Before carrying out any relocations, write the 592 * new output file image and reassign any necessary data pointers to the 593 * output files memory image. This insures that any relocation 594 * modifications are made to the output file image and not to the input 595 * file image, thus preventing the creation of dirty pages and reducing 596 * the overall swap space requirement. 597 * 598 * Write out the elf structure so as to create the new file image. 599 */ 600 if ((ofl->ofl_size = (size_t)elf_update(ofl->ofl_welf, 601 ELF_C_WRIMAGE)) == (size_t)-1) { 602 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_UPDATE), ofl->ofl_name); 603 return (S_ERROR); 604 } 605 606 /* 607 * Initialize the true `ofl' information with the memory images address 608 * and size. This will be used to write() out the image once any 609 * relocation processing has been completed. We also use this image 610 * information to setup a new Elf descriptor, which is used to obtain 611 * all the necessary elf pointers within the new output image. 612 */ 613 if ((ofl->ofl_elf = elf_begin(0, ELF_C_IMAGE, 614 ofl->ofl_welf)) == NULL) { 615 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_BEGIN), ofl->ofl_name); 616 return (S_ERROR); 617 } 618 if ((ofl->ofl_ehdr = elf_getehdr(ofl->ofl_elf)) == NULL) { 619 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR), ofl->ofl_name); 620 return (S_ERROR); 621 } 622 if (!(flags & FLG_OF_RELOBJ)) 623 if ((ofl->ofl_phdr = elf_getphdr(ofl->ofl_elf)) == NULL) { 624 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETPHDR), 625 ofl->ofl_name); 626 return (S_ERROR); 627 } 628 629 /* 630 * Reinitialize the section descriptors, section headers and obtain new 631 * output data buffer pointers (these will be used to perform any 632 * relocations). 633 */ 634 for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) { 635 Phdr * _phdr = &(sgp->sg_phdr); 636 Boolean recorded = FALSE; 637 638 for (LIST_TRAVERSE(&(sgp->sg_osdescs), lnp2, osp)) { 639 if ((osp->os_scn = elf_getscn(ofl->ofl_elf, ++ndx)) == 640 NULL) { 641 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETSCN), 642 ofl->ofl_name, ndx); 643 return (S_ERROR); 644 } 645 if ((osp->os_shdr = elf_getshdr(osp->os_scn)) == 646 NULL) { 647 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETSHDR), 648 ofl->ofl_name); 649 return (S_ERROR); 650 } 651 if ((fixalign == TRUE) && (sgp->sg_fscn != 0) && 652 (recorded == FALSE)) { 653 Elf_Scn *scn; 654 655 scn = sgp->sg_fscn; 656 if ((fndx = elf_ndxscn(scn)) == SHN_UNDEF) { 657 eprintf(ERR_ELF, 658 MSG_INTL(MSG_ELF_NDXSCN), 659 ofl->ofl_name); 660 return (S_ERROR); 661 } 662 if (ndx == fndx) { 663 sgp->sg_fscn = osp->os_scn; 664 recorded = TRUE; 665 } 666 } 667 668 if ((osp->os_outdata = 669 elf_getdata(osp->os_scn, NULL)) == NULL) { 670 eprintf(ERR_ELF, MSG_INTL(MSG_ELF_GETDATA), 671 ofl->ofl_name); 672 return (S_ERROR); 673 } 674 675 /* 676 * If this section is part of a loadable segment insure 677 * that the segments alignment is appropriate. 678 */ 679 if (_phdr->p_type == PT_LOAD) { 680 _phdr->p_align = (Xword)lcm(_phdr->p_align, 681 osp->os_shdr->sh_addralign); 682 } 683 } 684 } 685 return (1); 686 } 687