contrib/elftoolchain/elfcopy/segments.c

   1 /*-
   2  * Copyright (c) 2007-2010,2012 Kai Wang
   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
  27 #include <sys/queue.h>
  28 #include <err.h>
  29 #include <gelf.h>
  30 #include <stdint.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34
  35 #include "elfcopy.h"
  36
  37 ELFTC_VCSID("$Id: segments.c 3449 2016-05-03 13:59:29Z emaste $");
  38
  39 static void     insert_to_inseg_list(struct segment *seg, struct section *sec);
  40
  41 /*
  42  * elfcopy's segment handling is relatively simpler and less powerful than
  43  * libbfd. Program headers are modified or copied from input to output objects,
  44  * but never re-generated. As a result, if the input object has incorrect
  45  * program headers, the output object's program headers will remain incorrect
  46  * or become even worse.
  47  */
  48
  49 /*
  50  * Check whether a section is "loadable". If so, add it to the
  51  * corresponding segment list(s) and return 1.
  52  */
  53 int
  54 add_to_inseg_list(struct elfcopy *ecp, struct section *s)
  55 {
  56         struct segment  *seg;
  57         int              loadable;
  58
  59         if (ecp->ophnum == 0)
  60                 return (0);
  61
  62         /*
  63          * Segment is a different view of an ELF object. One segment can
  64          * contain one or more sections, and one section can be included
  65          * in one or more segments, or not included in any segment at all.
  66          * We call those sections which can be found in one or more segments
  67          * "loadable" sections, and call the rest "unloadable" sections.
  68          * We keep track of "loadable" sections in their containing
  69          * segment(s)' v_sec queue. These information are later used to
  70          * recalculate the extents of segments, when sections are removed,
  71          * for example.
  72          */
  73         loadable = 0;
  74         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
  75                 if (s->off < seg->off || (s->vma < seg->vaddr && !s->pseudo))
  76                         continue;
  77                 if (s->off + s->sz > seg->off + seg->fsz &&
  78                     s->type != SHT_NOBITS)
  79                         continue;
  80                 if (s->vma + s->sz > seg->vaddr + seg->msz)
  81                         continue;
  82
  83                 insert_to_inseg_list(seg, s);
  84                 if (seg->type == PT_LOAD)
  85                         s->seg = seg;
  86                 else if (seg->type == PT_TLS)
  87                         s->seg_tls = seg;
  88                 if (s->pseudo)
  89                         s->vma = seg->vaddr + (s->off - seg->off);
  90                 if (seg->paddr > 0)
  91                         s->lma = seg->paddr + (s->off - seg->off);
  92                 else
  93                         s->lma = 0;
  94                 loadable = 1;
  95         }
  96
  97         return (loadable);
  98 }
  99
 100 void
 101 adjust_addr(struct elfcopy *ecp)
 102 {
 103         struct section *s, *s0;
 104         struct segment *seg;
 105         struct sec_action *sac;
 106         uint64_t dl, vma, lma, start, end;
 107         int found, i;
 108
 109         /*
 110          * Apply VMA and global LMA changes in the first iteration.
 111          */
 112         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 113
 114                 /* Only adjust loadable section's address. */
 115                 if (!s->loadable)
 116                         continue;
 117
 118                 /* Apply global VMA adjustment. */
 119                 if (ecp->change_addr != 0)
 120                         s->vma += ecp->change_addr;
 121
 122                 /* Apply global LMA adjustment. */
 123                 if (ecp->change_addr != 0 && s->seg != NULL &&
 124                     s->seg->paddr > 0)
 125                         s->lma += ecp->change_addr;
 126         }
 127
 128         /*
 129          * Apply sections VMA change in the second iteration.
 130          */
 131         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 132
 133                 if (!s->loadable)
 134                         continue;
 135
 136                 /*
 137                  * Check if there is a VMA change request for this
 138                  * section.
 139                  */
 140                 sac = lookup_sec_act(ecp, s->name, 0);
 141                 if (sac == NULL)
 142                         continue;
 143                 vma = s->vma;
 144                 if (sac->setvma)
 145                         vma = sac->vma;
 146                 if (sac->vma_adjust != 0)
 147                         vma += sac->vma_adjust;
 148                 if (vma == s->vma)
 149                         continue;
 150
 151                 /*
 152                  * No need to make segment adjustment if the section doesn't
 153                  * belong to any segment.
 154                  */
 155                 if (s->seg == NULL) {
 156                         s->vma = vma;
 157                         continue;
 158                 }
 159
 160                 /*
 161                  * Check if the VMA change is viable.
 162                  *
 163                  * 1. Check if the new VMA is properly aligned accroding to
 164                  *    section alignment.
 165                  *
 166                  * 2. Compute the new extent of segment that contains this
 167                  *    section, make sure it doesn't overlap with other
 168                  *    segments.
 169                  */
 170 #ifdef  DEBUG
 171                 printf("VMA for section %s: %#jx\n", s->name, vma);
 172 #endif
 173
 174                 if (vma % s->align != 0)
 175                         errx(EXIT_FAILURE, "The VMA %#jx for "
 176                             "section %s is not aligned to %ju",
 177                             (uintmax_t) vma, s->name, (uintmax_t) s->align);
 178
 179                 if (vma < s->vma) {
 180                         /* Move section to lower address. */
 181                         if (vma < s->vma - s->seg->vaddr)
 182                                 errx(EXIT_FAILURE, "Not enough space to move "
 183                                     "section %s VMA to %#jx", s->name,
 184                                     (uintmax_t) vma);
 185                         start = vma - (s->vma - s->seg->vaddr);
 186                         if (s == s->seg->v_sec[s->seg->nsec - 1])
 187                                 end = start + s->seg->msz;
 188                         else
 189                                 end = s->seg->vaddr + s->seg->msz;
 190                 } else {
 191                         /* Move section to upper address. */
 192                         if (s == s->seg->v_sec[0])
 193                                 start = vma;
 194                         else
 195                                 start = s->seg->vaddr;
 196                         end = vma + (s->seg->vaddr + s->seg->msz - s->vma);
 197                         if (end < start)
 198                                 errx(EXIT_FAILURE, "Not enough space to move "
 199                                     "section %s VMA to %#jx", s->name,
 200                                     (uintmax_t) vma);
 201                 }
 202
 203 #ifdef  DEBUG
 204                 printf("new extent for segment containing %s: (%#jx,%#jx)\n",
 205                     s->name, start, end);
 206 #endif
 207
 208                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 209                         if (seg == s->seg || seg->type != PT_LOAD)
 210                                 continue;
 211                         if (start > seg->vaddr + seg->msz)
 212                                 continue;
 213                         if (end < seg->vaddr)
 214                                 continue;
 215                         errx(EXIT_FAILURE, "The extent of segment containing "
 216                             "section %s overlaps with segment(%#jx,%#jx)",
 217                             s->name, (uintmax_t) seg->vaddr,
 218                             (uintmax_t) (seg->vaddr + seg->msz));
 219                 }
 220
 221                 /*
 222                  * Update section VMA and file offset.
 223                  */
 224
 225                 if (vma < s->vma) {
 226                         /*
 227                          * To move a section to lower VMA, we decrease
 228                          * the VMA of the section and all the sections that
 229                          * are before it, and we increase the file offsets
 230                          * of all the sections that are after it.
 231                          */
 232                         dl = s->vma - vma;
 233                         for (i = 0; i < s->seg->nsec; i++) {
 234                                 s0 = s->seg->v_sec[i];
 235                                 s0->vma -= dl;
 236 #ifdef  DEBUG
 237                                 printf("section %s VMA set to %#jx\n",
 238                                     s0->name, (uintmax_t) s0->vma);
 239 #endif
 240                                 if (s0 == s)
 241                                         break;
 242                         }
 243                         for (i = i + 1; i < s->seg->nsec; i++) {
 244                                 s0 = s->seg->v_sec[i];
 245                                 s0->off += dl;
 246 #ifdef  DEBUG
 247                                 printf("section %s offset set to %#jx\n",
 248                                     s0->name, (uintmax_t) s0->off);
 249 #endif
 250                         }
 251                 } else {
 252                         /*
 253                          * To move a section to upper VMA, we increase
 254                          * the VMA of the section and all the sections that
 255                          * are after it, and we increase the their file
 256                          * offsets too unless the section in question
 257                          * is the first in its containing segment.
 258                          */
 259                         dl = vma - s->vma;
 260                         for (i = 0; i < s->seg->nsec; i++)
 261                                 if (s->seg->v_sec[i] == s)
 262                                         break;
 263                         if (i >= s->seg->nsec)
 264                                 errx(EXIT_FAILURE, "Internal: section `%s' not"
 265                                     " found in its containing segement",
 266                                     s->name);
 267                         for (; i < s->seg->nsec; i++) {
 268                                 s0 = s->seg->v_sec[i];
 269                                 s0->vma += dl;
 270 #ifdef  DEBUG
 271                                 printf("section %s VMA set to %#jx\n",
 272                                     s0->name, (uintmax_t) s0->lma);
 273 #endif
 274                                 if (s != s->seg->v_sec[0]) {
 275                                         s0->off += dl;
 276 #ifdef  DEBUG
 277                                         printf("section %s offset set to %#jx\n",
 278                                             s0->name, (uintmax_t) s0->off);
 279 #endif
 280                                 }
 281                         }
 282                 }
 283         }
 284
 285         /*
 286          * Apply load address padding.
 287          */
 288
 289         if (ecp->pad_to != 0) {
 290
 291                 /*
 292                  * Find the section with highest VMA.
 293                  */
 294                 s = NULL;
 295                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 296                         if (seg->type != PT_LOAD)
 297                                 continue;
 298                         for (i = seg->nsec - 1; i >= 0; i--)
 299                                 if (seg->v_sec[i]->type != SHT_NOBITS)
 300                                         break;
 301                         if (i < 0)
 302                                 continue;
 303                         if (s == NULL)
 304                                 s = seg->v_sec[i];
 305                         else {
 306                                 s0 = seg->v_sec[i];
 307                                 if (s0->vma > s->vma)
 308                                         s = s0;
 309                         }
 310                 }
 311
 312                 if (s == NULL)
 313                         goto adjust_lma;
 314
 315                 /* No need to pad if the pad_to address is lower. */
 316                 if (ecp->pad_to <= s->vma + s->sz)
 317                         goto adjust_lma;
 318
 319                 s->pad_sz = ecp->pad_to - (s->vma + s->sz);
 320 #ifdef  DEBUG
 321                 printf("pad section %s VMA to address %#jx by %#jx\n", s->name,
 322                     (uintmax_t) ecp->pad_to, (uintmax_t) s->pad_sz);
 323 #endif
 324         }
 325
 326
 327 adjust_lma:
 328
 329         /*
 330          * Apply sections LMA change in the third iteration.
 331          */
 332         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 333
 334                 /*
 335                  * Only loadable section that's inside a segment can have
 336                  * LMA adjusted. Also, if LMA of the containing segment is
 337                  * set to 0, it probably means we should ignore the LMA.
 338                  */
 339                 if (!s->loadable || s->seg == NULL || s->seg->paddr == 0)
 340                         continue;
 341
 342                 /*
 343                  * Check if there is a LMA change request for this
 344                  * section.
 345                  */
 346                 sac = lookup_sec_act(ecp, s->name, 0);
 347                 if (sac == NULL)
 348                         continue;
 349                 if (!sac->setlma && sac->lma_adjust == 0)
 350                         continue;
 351                 lma = s->lma;
 352                 if (sac->setlma)
 353                         lma = sac->lma;
 354                 if (sac->lma_adjust != 0)
 355                         lma += sac->lma_adjust;
 356                 if (lma == s->lma)
 357                         continue;
 358
 359 #ifdef  DEBUG
 360                 printf("LMA for section %s: %#jx\n", s->name, lma);
 361 #endif
 362
 363                 /* Check alignment. */
 364                 if (lma % s->align != 0)
 365                         errx(EXIT_FAILURE, "The LMA %#jx for "
 366                             "section %s is not aligned to %ju",
 367                             (uintmax_t) lma, s->name, (uintmax_t) s->align);
 368
 369                 /*
 370                  * Update section LMA.
 371                  */
 372
 373                 if (lma < s->lma) {
 374                         /*
 375                          * To move a section to lower LMA, we decrease
 376                          * the LMA of the section and all the sections that
 377                          * are before it.
 378                          */
 379                         dl = s->lma - lma;
 380                         for (i = 0; i < s->seg->nsec; i++) {
 381                                 s0 = s->seg->v_sec[i];
 382                                 s0->lma -= dl;
 383 #ifdef  DEBUG
 384                                 printf("section %s LMA set to %#jx\n",
 385                                     s0->name, (uintmax_t) s0->lma);
 386 #endif
 387                                 if (s0 == s)
 388                                         break;
 389                         }
 390                 } else {
 391                         /*
 392                          * To move a section to upper LMA, we increase
 393                          * the LMA of the section and all the sections that
 394                          * are after it.
 395                          */
 396                         dl = lma - s->lma;
 397                         for (i = 0; i < s->seg->nsec; i++)
 398                                 if (s->seg->v_sec[i] == s)
 399                                         break;
 400                         if (i >= s->seg->nsec)
 401                                 errx(EXIT_FAILURE, "Internal: section `%s' not"
 402                                     " found in its containing segement",
 403                                     s->name);
 404                         for (; i < s->seg->nsec; i++) {
 405                                 s0 = s->seg->v_sec[i];
 406                                 s0->lma += dl;
 407 #ifdef  DEBUG
 408                                 printf("section %s LMA set to %#jx\n",
 409                                     s0->name, (uintmax_t) s0->lma);
 410 #endif
 411                         }
 412                 }
 413         }
 414
 415         /*
 416          * Issue a warning if there are VMA/LMA adjust requests for
 417          * some nonexistent sections.
 418          */
 419         if ((ecp->flags & NO_CHANGE_WARN) == 0) {
 420                 STAILQ_FOREACH(sac, &ecp->v_sac, sac_list) {
 421                         if (!sac->setvma && !sac->setlma &&
 422                             !sac->vma_adjust && !sac->lma_adjust)
 423                                 continue;
 424                         found = 0;
 425                         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 426                                 if (s->pseudo || s->name == NULL)
 427                                         continue;
 428                                 if (!strcmp(s->name, sac->name)) {
 429                                         found = 1;
 430                                         break;
 431                                 }
 432                         }
 433                         if (!found)
 434                                 warnx("cannot find section `%s'", sac->name);
 435                 }
 436         }
 437 }
 438
 439 static void
 440 insert_to_inseg_list(struct segment *seg, struct section *sec)
 441 {
 442         struct section *s;
 443         int i;
 444
 445         seg->nsec++;
 446         seg->v_sec = realloc(seg->v_sec, seg->nsec * sizeof(*seg->v_sec));
 447         if (seg->v_sec == NULL)
 448                 err(EXIT_FAILURE, "realloc failed");
 449
 450         /*
 451          * Sort the section in order of offset.
 452          */
 453
 454         for (i = seg->nsec - 1; i > 0; i--) {
 455                 s = seg->v_sec[i - 1];
 456                 if (sec->off >= s->off) {
 457                         seg->v_sec[i] = sec;
 458                         break;
 459                 } else
 460                         seg->v_sec[i] = s;
 461         }
 462         if (i == 0)
 463                 seg->v_sec[0] = sec;
 464 }
 465
 466 void
 467 setup_phdr(struct elfcopy *ecp)
 468 {
 469         struct segment  *seg;
 470         GElf_Phdr        iphdr;
 471         size_t           iphnum, i;
 472
 473         if (elf_getphnum(ecp->ein, &iphnum) == 0)
 474                 errx(EXIT_FAILURE, "elf_getphnum failed: %s",
 475                     elf_errmsg(-1));
 476
 477         ecp->ophnum = ecp->iphnum = iphnum;
 478         if (iphnum == 0)
 479                 return;
 480
 481         /* If --only-keep-debug is specified, discard all program headers. */
 482         if (ecp->strip == STRIP_NONDEBUG) {
 483                 ecp->ophnum = 0;
 484                 return;
 485         }
 486
 487         for (i = 0; i < iphnum; i++) {
 488                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 489                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 490                             elf_errmsg(-1));
 491                 if ((seg = calloc(1, sizeof(*seg))) == NULL)
 492                         err(EXIT_FAILURE, "calloc failed");
 493                 seg->vaddr      = iphdr.p_vaddr;
 494                 seg->paddr      = iphdr.p_paddr;
 495                 seg->off        = iphdr.p_offset;
 496                 seg->fsz        = iphdr.p_filesz;
 497                 seg->msz        = iphdr.p_memsz;
 498                 seg->type       = iphdr.p_type;
 499                 STAILQ_INSERT_TAIL(&ecp->v_seg, seg, seg_list);
 500         }
 501 }
 502
 503 void
 504 copy_phdr(struct elfcopy *ecp)
 505 {
 506         struct segment  *seg;
 507         struct section  *s;
 508         GElf_Phdr        iphdr, ophdr;
 509         int              i;
 510
 511         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 512                 if (seg->type == PT_PHDR) {
 513                         if (!TAILQ_EMPTY(&ecp->v_sec)) {
 514                                 s = TAILQ_FIRST(&ecp->v_sec);
 515                                 if (s->pseudo) {
 516                                         seg->vaddr = s->vma +
 517                                             gelf_fsize(ecp->eout, ELF_T_EHDR,
 518                                                 1, EV_CURRENT);
 519                                         seg->paddr = s->lma +
 520                                             gelf_fsize(ecp->eout, ELF_T_EHDR,
 521                                                 1, EV_CURRENT);
 522                                 }
 523                         }
 524                         seg->fsz = seg->msz = gelf_fsize(ecp->eout, ELF_T_PHDR,
 525                             ecp->ophnum, EV_CURRENT);
 526                         continue;
 527                 }
 528
 529                 if (seg->nsec > 0) {
 530                         s = seg->v_sec[0];
 531                         seg->vaddr = s->vma;
 532                         seg->paddr = s->lma;
 533                 }
 534
 535                 seg->fsz = seg->msz = 0;
 536                 for (i = 0; i < seg->nsec; i++) {
 537                         s = seg->v_sec[i];
 538                         seg->msz = s->vma + s->sz - seg->vaddr;
 539                         if (s->type != SHT_NOBITS)
 540                                 seg->fsz = s->off + s->sz - seg->off;
 541                 }
 542         }
 543
 544         /*
 545          * Allocate space for program headers, note that libelf keep
 546          * track of the number in internal variable, and a call to
 547          * elf_update is needed to update e_phnum of ehdr.
 548          */
 549         if (gelf_newphdr(ecp->eout, ecp->ophnum) == NULL)
 550                 errx(EXIT_FAILURE, "gelf_newphdr() failed: %s",
 551                     elf_errmsg(-1));
 552
 553         /*
 554          * This elf_update() call is to update the e_phnum field in
 555          * ehdr. It's necessary because later we will call gelf_getphdr(),
 556          * which does sanity check by comparing ndx argument with e_phnum.
 557          */
 558         if (elf_update(ecp->eout, ELF_C_NULL) < 0)
 559                 errx(EXIT_FAILURE, "elf_update() failed: %s", elf_errmsg(-1));
 560
 561         /*
 562          * iphnum == ophnum, since we don't remove program headers even if
 563          * they no longer contain sections.
 564          */
 565         i = 0;
 566         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 567                 if (i >= ecp->iphnum)
 568                         break;
 569                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 570                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 571                             elf_errmsg(-1));
 572                 if (gelf_getphdr(ecp->eout, i, &ophdr) != &ophdr)
 573                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 574                             elf_errmsg(-1));
 575
 576                 ophdr.p_type = iphdr.p_type;
 577                 ophdr.p_vaddr = seg->vaddr;
 578                 ophdr.p_paddr = seg->paddr;
 579                 ophdr.p_flags = iphdr.p_flags;
 580                 ophdr.p_align = iphdr.p_align;
 581                 ophdr.p_offset = seg->off;
 582                 ophdr.p_filesz = seg->fsz;
 583                 ophdr.p_memsz = seg->msz;
 584                 if (!gelf_update_phdr(ecp->eout, i, &ophdr))
 585                         errx(EXIT_FAILURE, "gelf_update_phdr failed: %s",
 586                             elf_errmsg(-1));
 587
 588                 i++;
 589         }
 590 }