usr.bin/crunch/crunchide/exec_elf32.c

   1 /*
   2  * Copyright (c) 1997 Christopher G. Demetriou.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. All advertising materials mentioning features or use of this software
  13  *    must display the following acknowledgement:
  14  *      This product includes software developed by Christopher G. Demetriou
  15  *      for the NetBSD Project.
  16  * 4. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #ifndef ELFSIZE
  32 #define ELFSIZE         32
  33 #endif
  34
  35 #include <sys/types.h>
  36 #include <sys/endian.h>
  37 #include <sys/stat.h>
  38
  39 #include <errno.h>
  40 #include <limits.h>
  41 #include <stddef.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <unistd.h>
  46
  47 #include "extern.h"
  48
  49 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
  50     (defined(NLIST_ELF64) && (ELFSIZE == 64))
  51
  52 #define __ELF_WORD_SIZE ELFSIZE
  53 #if (ELFSIZE == 32)
  54 #include <sys/elf32.h>
  55 #define xewtoh(x)       ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
  56 #define htoxew(x)       ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
  57 #define wewtoh(x)       ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
  58 #define htowew(x)       ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
  59 #elif (ELFSIZE == 64)
  60 #include <sys/elf64.h>
  61 #define xewtoh(x)       ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x))
  62 #define htoxew(x)       ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x))
  63 /* elf64 Elf64_Word are 32 bits */
  64 #define wewtoh(x)       ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
  65 #define htowew(x)       ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
  66 #endif
  67 #include <sys/elf_generic.h>
  68
  69 #define CONCAT(x,y)     __CONCAT(x,y)
  70 #define ELFNAME(x)      CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x)))
  71 #define ELFNAME2(x,y)   CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y))))
  72 #define ELFNAMEEND(x)   CONCAT(x,CONCAT(_elf,ELFSIZE))
  73 #define ELFDEFNNAME(x)  CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x)))
  74
  75 #define xe16toh(x)      ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x))
  76 #define xe32toh(x)      ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
  77 #define htoxe32(x)      ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
  78
  79 struct shlayout {
  80         Elf_Shdr *shdr;
  81         void *bufp;
  82 };
  83
  84 static ssize_t
  85 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn)
  86 {
  87         ssize_t rv;
  88
  89         if (lseek(fd, off, SEEK_SET) != off) {
  90                 perror(fn);
  91                 return -1;
  92         }
  93         if ((size_t)(rv = read(fd, buf, size)) != size) {
  94                 fprintf(stderr, "%s: read error: %s\n", fn,
  95                     rv == -1 ? strerror(errno) : "short read");
  96                 return -1;
  97         }
  98         return size;
  99 }
 100
 101 static ssize_t
 102 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn)
 103 {
 104         ssize_t rv;
 105
 106         if (lseek(fd, off, SEEK_SET) != off) {
 107                 perror(fn);
 108                 return -1;
 109         }
 110         if ((size_t)(rv = write(fd, buf, size)) != size) {
 111                 fprintf(stderr, "%s: write error: %s\n", fn,
 112                     rv == -1 ? strerror(errno) : "short write");
 113                 return -1;
 114         }
 115         return size;
 116 }
 117
 118 static void *
 119 xmalloc(size_t size, const char *fn, const char *use)
 120 {
 121         void *rv;
 122
 123         rv = malloc(size);
 124         if (rv == NULL)
 125                 fprintf(stderr, "%s: out of memory (allocating for %s)\n",
 126                     fn, use);
 127         return (rv);
 128 }
 129
 130 static void *
 131 xrealloc(void *ptr, size_t size, const char *fn, const char *use)
 132 {
 133         void *rv;
 134
 135         rv = realloc(ptr, size);
 136         if (rv == NULL) {
 137                 free(ptr);
 138                 fprintf(stderr, "%s: out of memory (reallocating for %s)\n",
 139                     fn, use);
 140         }
 141         return (rv);
 142 }
 143
 144 int
 145 ELFNAMEEND(check)(int fd, const char *fn)
 146 {
 147         Elf_Ehdr eh;
 148         struct stat sb;
 149         unsigned char data;
 150
 151         /*
 152          * Check the header to maek sure it's an ELF file (of the
 153          * appropriate size).
 154          */
 155         if (fstat(fd, &sb) == -1)
 156                 return 0;
 157         if (sb.st_size < (off_t)(sizeof eh))
 158                 return 0;
 159         if (read(fd, &eh, sizeof eh) != sizeof eh)
 160                 return 0;
 161
 162         if (IS_ELF(eh) == 0)
 163                 return 0;
 164
 165         data = eh.e_ident[EI_DATA];
 166
 167         switch (xe16toh(eh.e_machine)) {
 168         case EM_386: break;
 169         case EM_ALPHA: break;
 170 #ifndef EM_AARCH64
 171 #define EM_AARCH64      183
 172 #endif
 173         case EM_AARCH64: break;
 174 #ifndef EM_ARM
 175 #define EM_ARM          40
 176 #endif
 177         case EM_ARM: break;
 178 #ifndef EM_MIPS
 179 #define EM_MIPS         8
 180 #endif
 181 #ifndef EM_MIPS_RS4_BE          /* same as EM_MIPS_RS3_LE */
 182 #define EM_MIPS_RS4_BE  10
 183 #endif
 184         case EM_MIPS: break;
 185         case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break;
 186 #ifndef EM_PPC
 187 #define EM_PPC          20
 188 #endif
 189         case EM_PPC: break;
 190 #ifndef EM_PPC64
 191 #define EM_PPC64        21
 192 #endif
 193         case EM_PPC64: break;
 194 #ifndef EM_SPARCV9
 195 #define EM_SPARCV9      43
 196 #endif
 197         case EM_SPARCV9: break;
 198 #ifndef EM_X86_64
 199 #define EM_X86_64       62
 200 #endif
 201         case EM_X86_64: break;
 202 /*        ELFDEFNNAME(MACHDEP_ID_CASES) */
 203
 204         default:
 205                 return 0;
 206         }
 207
 208         return 1;
 209 }
 210
 211 /*
 212  * This function 'hides' (some of) ELF executable file's symbols.
 213  * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>".
 214  * Symbols in the global keep list, or which are marked as being undefined,
 215  * are left alone.
 216  *
 217  * An old version of this code shuffled various tables around, turning
 218  * global symbols to be hidden into local symbols.  That lost on the
 219  * mips, because CALL16 relocs must reference global symbols, and, if
 220  * those symbols were being hidden, they were no longer global.
 221  *
 222  * The new renaming behaviour doesn't take global symbols out of the
 223  * namespace.  However, it's ... unlikely that there will ever be
 224  * any collisions in practice because of the new method.
 225  */
 226 int
 227 ELFNAMEEND(hide)(int fd, const char *fn)
 228 {
 229         Elf_Ehdr ehdr;
 230         struct shlayout *layoutp = NULL;
 231         Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr;
 232         Elf_Shdr shdrshdr;
 233         Elf_Sym *symtabp = NULL;
 234         char *shstrtabp = NULL, *strtabp = NULL;
 235         Elf_Size nsyms, ewi;
 236         Elf_Off off;
 237         ssize_t shdrsize;
 238         int rv, i, weird, l, m, r, strtabidx;
 239         size_t nstrtab_size, nstrtab_nextoff, fn_size, size;
 240         char *nstrtabp = NULL;
 241         unsigned char data;
 242         const char *weirdreason = NULL;
 243         void *buf;
 244         Elf_Half shnum;
 245
 246         rv = 0;
 247         if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr)
 248                 goto bad;
 249
 250         data = ehdr.e_ident[EI_DATA];
 251         shnum = xe16toh(ehdr.e_shnum);
 252
 253         shdrsize = shnum * xe16toh(ehdr.e_shentsize);
 254         if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL)
 255                 goto bad;
 256         if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) !=
 257             shdrsize)
 258                 goto bad;
 259
 260         symtabshdr = strtabshdr = shstrtabshdr = NULL;
 261         weird = 0;
 262         for (i = 0; i < shnum; i++) {
 263                 switch (xe32toh(shdrp[i].sh_type)) {
 264                 case SHT_SYMTAB:
 265                         if (symtabshdr != NULL) {
 266                                 weird = 1;
 267                                 weirdreason = "multiple symbol tables";
 268                         }
 269                         symtabshdr = &shdrp[i];
 270                         strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)];
 271                         break;
 272                 case SHT_STRTAB:
 273                         if (i == xe16toh(ehdr.e_shstrndx))
 274                                 shstrtabshdr = &shdrp[i];
 275                         break;
 276                 }
 277         }
 278         if (symtabshdr == NULL)
 279                 goto out;
 280         if (strtabshdr == NULL) {
 281                 weird = 1;
 282                 weirdreason = "string table does not exist";
 283         }
 284         if (shstrtabshdr == NULL) {
 285                 weird = 1;
 286                 weirdreason = "section header string table does not exist";
 287         }
 288         if (weirdreason == NULL)
 289                 weirdreason = "unsupported";
 290         if (weird) {
 291                 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason);
 292                 goto bad;
 293         }
 294
 295         /*
 296          * sort section layout table by offset
 297          */
 298         layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout),
 299             fn, "layout table");
 300         if (layoutp == NULL)
 301                 goto bad;
 302
 303         /* add a pseudo entry to represent the section header table */
 304         shdrshdr.sh_offset = ehdr.e_shoff;
 305         shdrshdr.sh_size = htoxew(shdrsize);
 306         shdrshdr.sh_addralign = htoxew(ELFSIZE / 8);
 307         layoutp[shnum].shdr = &shdrshdr;
 308
 309         /* insert and sort normal section headers */
 310         for (i = shnum; i-- != 0;) {
 311                 l = i + 1;
 312                 r = shnum;
 313                 while (l <= r) {
 314                         m = ( l + r) / 2;
 315                         if (xewtoh(shdrp[i].sh_offset) >
 316                             xewtoh(layoutp[m].shdr->sh_offset))
 317                                 l = m + 1;
 318                         else
 319                                 r = m - 1;
 320                 }
 321
 322                 if (r != i) {
 323                         memmove(&layoutp[i], &layoutp[i + 1],
 324                             sizeof(struct shlayout) * (r - i));
 325                 }
 326
 327                 layoutp[r].shdr = &shdrp[i];
 328                 layoutp[r].bufp = NULL;
 329         }
 330         ++shnum;
 331
 332         /*
 333          * load up everything we need
 334          */
 335
 336         /* load section string table for debug use */
 337         if ((shstrtabp = xmalloc(xewtoh(shstrtabshdr->sh_size), fn,
 338             "section string table")) == NULL)
 339                 goto bad;
 340         if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset),
 341             xewtoh(shstrtabshdr->sh_size), fn) != xewtoh(shstrtabshdr->sh_size))
 342                 goto bad;
 343
 344         /* we need symtab, strtab, and everything behind strtab */
 345         strtabidx = INT_MAX;
 346         for (i = 0; i < shnum; i++) {
 347                 if (layoutp[i].shdr == &shdrshdr) {
 348                         /* not load section header again */
 349                         layoutp[i].bufp = shdrp;
 350                         continue;
 351                 }
 352                 if (layoutp[i].shdr == shstrtabshdr) {
 353                         /* not load section string table again */
 354                         layoutp[i].bufp = shstrtabp;
 355                         continue;
 356                 }
 357
 358                 if (layoutp[i].shdr == strtabshdr)
 359                         strtabidx = i;
 360                 if (layoutp[i].shdr == symtabshdr || i >= strtabidx) {
 361                         off = xewtoh(layoutp[i].shdr->sh_offset);
 362                         size = xewtoh(layoutp[i].shdr->sh_size);
 363                         layoutp[i].bufp = xmalloc(size, fn,
 364                             shstrtabp + xewtoh(layoutp[i].shdr->sh_name));
 365                         if (layoutp[i].bufp == NULL)
 366                                 goto bad;
 367                         if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) !=
 368                             size)
 369                                 goto bad;
 370
 371                         /* set symbol table and string table */
 372                         if (layoutp[i].shdr == symtabshdr)
 373                                 symtabp = layoutp[i].bufp;
 374                         else if (layoutp[i].shdr == strtabshdr)
 375                                 strtabp = layoutp[i].bufp;
 376                 }
 377         }
 378
 379         nstrtab_size = 256;
 380         nstrtabp = xmalloc(nstrtab_size, fn, "new string table");
 381         if (nstrtabp == NULL)
 382                 goto bad;
 383         nstrtab_nextoff = 0;
 384
 385         fn_size = strlen(fn);
 386
 387         /* Prepare data structures for symbol movement. */
 388         nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize);
 389
 390         /* move symbols, making them local */
 391         for (ewi = 0; ewi < nsyms; ewi++) {
 392                 Elf_Sym *sp = &symtabp[ewi];
 393                 const char *symname = strtabp + xe32toh(sp->st_name);
 394                 size_t newent_len;
 395                 /*
 396                  * make sure there's size for the next entry, even if it's
 397                  * as large as it can be.
 398                  *
 399                  * "_$$hide$$ <filename> <symname><NUL>" ->
 400                  *    9 + 3 + sizes of fn and sym name
 401                  */
 402                 while ((nstrtab_size - nstrtab_nextoff) <
 403                     strlen(symname) + fn_size + 12) {
 404                         nstrtab_size *= 2;
 405                         nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn,
 406                             "new string table");
 407                         if (nstrtabp == NULL)
 408                                 goto bad;
 409                 }
 410
 411                 sp->st_name = htowew(nstrtab_nextoff);
 412
 413                 /* if it's a keeper or is undefined, don't rename it. */
 414                 if (in_keep_list(symname) ||
 415                     (xe16toh(sp->st_shndx) == SHN_UNDEF)) {
 416                         newent_len = sprintf(nstrtabp + nstrtab_nextoff,
 417                             "%s", symname) + 1;
 418                 } else {
 419                         newent_len = sprintf(nstrtabp + nstrtab_nextoff,
 420                             "_$$hide$$ %s %s", fn, symname) + 1;
 421                 }
 422                 nstrtab_nextoff += newent_len;
 423         }
 424         strtabshdr->sh_size = htoxew(nstrtab_nextoff);
 425
 426         /*
 427          * update section header table in ascending order of offset
 428          */
 429         for (i = strtabidx + 1; i < shnum; i++) {
 430                 Elf_Off off, align;
 431                 off = xewtoh(layoutp[i - 1].shdr->sh_offset) +
 432                     xewtoh(layoutp[i - 1].shdr->sh_size);
 433                 align = xewtoh(layoutp[i].shdr->sh_addralign);
 434                 off = (off + (align - 1)) & ~(align - 1);
 435                 layoutp[i].shdr->sh_offset = htoxew(off);
 436         }
 437
 438         /*
 439          * write data to the file in descending order of offset
 440          */
 441         for (i = shnum; i-- != 0;) {
 442                 if (layoutp[i].shdr == strtabshdr) {
 443                         /* new string table */
 444                         buf = nstrtabp;
 445                 } else
 446                         buf = layoutp[i].bufp;
 447
 448                 if (layoutp[i].shdr == &shdrshdr ||
 449                     layoutp[i].shdr == symtabshdr || i >= strtabidx) {
 450                         if (buf == NULL)
 451                                 goto bad;
 452
 453                         /*
 454                          * update the offset of section header table in elf
 455                          * header if needed.
 456                          */
 457                         if (layoutp[i].shdr == &shdrshdr &&
 458                             ehdr.e_shoff != shdrshdr.sh_offset) {
 459                                 ehdr.e_shoff = shdrshdr.sh_offset;
 460                                 off = offsetof(Elf_Ehdr, e_shoff);
 461                                 size = sizeof(Elf_Off);
 462                                 if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size,
 463                                     fn) != size)
 464                                         goto bad;
 465                         }
 466
 467                         off = xewtoh(layoutp[i].shdr->sh_offset);
 468                         size = xewtoh(layoutp[i].shdr->sh_size);
 469                         if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size)
 470                                 goto bad;
 471                 }
 472         }
 473
 474 out:
 475         if (layoutp != NULL) {
 476                 for (i = 0; i < shnum; i++) {
 477                         if (layoutp[i].bufp != NULL)
 478                                 free(layoutp[i].bufp);
 479                 }
 480                 free(layoutp);
 481         }
 482         free(nstrtabp);
 483         return (rv);
 484
 485 bad:
 486         rv = 1;
 487         goto out;
 488 }
 489
 490 #endif /* include this size of ELF */