utils/ldd.c

   1 /*
   2  * A small little ldd implementation for uClibc
   3  *
   4  * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
   5  *
   6  * Several functions in this file (specifically, elf_find_section_type(),
   7  * elf_find_phdr_type(), and elf_find_dynamic(), were stolen from elflib.c from
   8  * elfvector (http://www.BitWagon.com/elfvector.html) by John F. Reiser
   9  * <jreiser@BitWagon.com>, which is copyright 2000 BitWagon Software LLC
  10  * (GPL2).
  11  *
  12  * Licensed under GPLv2 or later
  13  */
  14
  15 #include "porting.h"
  16
  17 #if defined(__aarch64__)
  18 #define MATCH_MACHINE(x) (x == EM_AARCH64)
  19 #define ELFCLASSM       ELFCLASS64
  20 #endif
  21
  22 #if defined(__alpha__)
  23 #define MATCH_MACHINE(x) (x == EM_ALPHA)
  24 #define ELFCLASSM       ELFCLASS64
  25 #endif
  26
  27 #if defined(__arc__)
  28 #define MATCH_MACHINE(x) (x == EM_ARCOMPACT)
  29 #define ELFCLASSM      ELFCLASS32
  30 #endif
  31
  32 #if defined(__arm__) || defined(__thumb__)
  33 #define MATCH_MACHINE(x) (x == EM_ARM)
  34 #define ELFCLASSM       ELFCLASS32
  35 #endif
  36
  37 #if defined(__avr32__)
  38 #define MATCH_MACHINE(x) (x == EM_AVR32)
  39 #define ELFCLASSM      ELFCLASS32
  40 #endif
  41
  42 #if defined(__bfin__)
  43 #define MATCH_MACHINE(x) (x == EM_BLACKFIN)
  44 #define ELFCLASSM      ELFCLASS32
  45 #endif
  46
  47 #if defined(__TMS320C6X__)
  48 #define MATCH_MACHINE(x) (x == EM_TI_C6000)
  49 #define ELFCLASSM       ELFCLASS32
  50 #endif
  51
  52 #if defined(__cris__)
  53 #define MATCH_MACHINE(x) (x == EM_CRIS)
  54 #define ELFCLASSM       ELFCLASS32
  55 #endif
  56
  57 #if defined(__csky__)
  58 #define MATCH_MACHINE(x) (x == EM_MCORE)
  59 #define ELFCLASSM       ELFCLASS32
  60 #endif
  61
  62 #if defined(__frv__)
  63 #define MATCH_MACHINE(x) (x == EM_CYGNUS_FRV)
  64 #define ELFCLASSM       ELFCLASS32
  65 #endif
  66
  67 #if defined(__hppa__)
  68 #define MATCH_MACHINE(x) (x == EM_PARISC)
  69 #if defined(__LP64__)
  70 #define ELFCLASSM               ELFCLASS64
  71 #else
  72 #define ELFCLASSM               ELFCLASS32
  73 #endif
  74 #endif
  75
  76 #if defined(__i386__)
  77 #ifndef EM_486
  78 #define MATCH_MACHINE(x) (x == EM_386)
  79 #else
  80 #define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
  81 #endif
  82 #define ELFCLASSM       ELFCLASS32
  83 #endif
  84
  85 #if defined(__ia64__)
  86 #define MATCH_MACHINE(x) (x == EM_IA_64)
  87 #define ELFCLASSM       ELFCLASS64
  88 #endif
  89
  90 #if defined(__mc68000__)
  91 #define MATCH_MACHINE(x) (x == EM_68K)
  92 #define ELFCLASSM       ELFCLASS32
  93 #endif
  94
  95 #if defined(__metag__)
  96 #define MATCH_MACHINE(x) (x == EM_METAG)
  97 #define ELFCLASSM       ELFCLASS32
  98 #endif
  99
 100 #if defined(__microblaze__)
 101 #define MATCH_MACHINE(x) (x == EM_MICROBLAZE)
 102 #define ELFCLASSM       ELFCLASS32
 103 #endif
 104
 105 #if defined(__mips__)
 106 #define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
 107 #define ELFCLASSM       ELFCLASS32
 108 #endif
 109
 110 #if defined(__nds32__)
 111 #define MATCH_MACHINE(x) (x == EM_NDS32)
 112 #define ELFCLASSM       ELFCLASS32
 113 #endif
 114
 115 #if defined(__nios2__)
 116 #define MATCH_MACHINE(x) (x == EM_NIOS32)
 117 #define ELFCLASSM       ELFCLASS32
 118 #endif
 119
 120 #if defined(__powerpc__)
 121 #define MATCH_MACHINE(x) (x == EM_PPC)
 122 #define ELFCLASSM       ELFCLASS32
 123 #endif
 124
 125 #if defined(__sh__)
 126 #define MATCH_MACHINE(x) (x == EM_SH)
 127 #define ELFCLASSM       ELFCLASS32
 128 #endif
 129
 130 #if defined(__sparc__)
 131 #define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
 132 #define ELFCLASSM    ELFCLASS32
 133 #endif
 134
 135 #if defined(__x86_64__)
 136 #define MATCH_MACHINE(x) (x == EM_X86_64)
 137 #define ELFCLASSM       ELFCLASS64
 138 #endif
 139
 140 #if defined(__xtensa__)
 141 #define MATCH_MACHINE(x) (x == EM_XTENSA)
 142 #define ELFCLASSM       ELFCLASS32
 143 #endif
 144
 145 #ifndef MATCH_MACHINE
 146 # ifdef __linux__
 147 #  include <asm/elf.h>
 148 # endif
 149 # ifdef ELF_ARCH
 150 #  define MATCH_MACHINE(x) (x == ELF_ARCH)
 151 # endif
 152 # ifdef ELF_CLASS
 153 #  define ELFCLASSM ELF_CLASS
 154 # endif
 155 #endif
 156 #ifndef MATCH_MACHINE
 157 # warning "You really should add a MATCH_MACHINE() macro for your architecture"
 158 #endif
 159
 160 #if UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE
 161 #define ELFDATAM        ELFDATA2LSB
 162 #elif UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG
 163 #define ELFDATAM        ELFDATA2MSB
 164 #endif
 165
 166 #define TRUSTED_LDSO    UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
 167
 168 struct library {
 169         char *name;
 170         int resolved;
 171         char *path;
 172         struct library *next;
 173 };
 174 static struct library *lib_list = NULL;
 175 static char not_found[] = "not found";
 176 static char *interp_name = NULL;
 177 static char *interp_dir = NULL;
 178 static int byteswap;
 179 static int interpreter_already_found = 0;
 180
 181 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
 182 {
 183         if (byteswap) {
 184                 return (bswap_32(value));
 185         } else {
 186                 return (value);
 187         }
 188 }
 189 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
 190 {
 191         if (byteswap) {
 192                 return (bswap_64(value));
 193         } else {
 194                 return (value);
 195         }
 196 }
 197
 198 #if __WORDSIZE == 64
 199 # define byteswap_to_host(x) byteswap64_to_host(x)
 200 #else
 201 # define byteswap_to_host(x) byteswap32_to_host(x)
 202 #endif
 203
 204 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
 205 {
 206         int j;
 207         ElfW(Shdr) *shdr;
 208         shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
 209         for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
 210                 if (key == byteswap32_to_host(shdr->sh_type)) {
 211                         return shdr;
 212                 }
 213         }
 214         return NULL;
 215 }
 216
 217 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
 218 {
 219         int j;
 220         ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
 221         for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
 222                 if (type == byteswap32_to_host(phdr->p_type)) {
 223                         return phdr;
 224                 }
 225         }
 226         return NULL;
 227 }
 228
 229 /* Returns value if return_val==1, ptr otherwise */
 230 static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
 231                        ElfW(Ehdr) *ehdr, int return_val)
 232 {
 233         ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
 234         unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
 235         for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
 236                 if (key == byteswap_to_host(dynp->d_tag)) {
 237                         if (return_val == 1)
 238                                 return (void *)byteswap_to_host(dynp->d_un.d_val);
 239                         else
 240                                 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
 241                 }
 242         }
 243         return NULL;
 244 }
 245
 246 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
 247 {
 248         ElfW(Dyn) *dyns;
 249
 250         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 251                 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
 252                         char *strtab;
 253                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 254                         return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 255                 }
 256         }
 257         return NULL;
 258 }
 259
 260 static int check_elf_header(ElfW(Ehdr) *const ehdr)
 261 {
 262         if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
 263          /* Use __WORDSIZE, not ELFCLASSM which depends on the host */
 264          || ehdr->e_ident[EI_CLASS] != (__WORDSIZE >> 5)
 265          || ehdr->e_ident[EI_VERSION] != EV_CURRENT
 266         ) {
 267                 return 1;
 268         }
 269
 270         /* Check if the target endianness matches the host's endianness */
 271         byteswap = !(ehdr->e_ident[5] == ELFDATAM);
 272
 273         /* Be very lazy, and only byteswap the stuff we use */
 274         if (byteswap) {
 275                 ehdr->e_type = bswap_16(ehdr->e_type);
 276                 ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
 277                 ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
 278                 ehdr->e_phnum = bswap_16(ehdr->e_phnum);
 279                 ehdr->e_shnum = bswap_16(ehdr->e_shnum);
 280         }
 281
 282         return 0;
 283 }
 284
 285 #ifdef __LDSO_CACHE_SUPPORT__
 286 static caddr_t cache_addr = NULL;
 287 static size_t cache_size = 0;
 288
 289 static int map_cache(void)
 290 {
 291         int fd;
 292         struct stat st;
 293         header_t *header;
 294         libentry_t *libent;
 295         int i, strtabsize;
 296
 297         if (cache_addr == (caddr_t) - 1)
 298                 return -1;
 299         else if (cache_addr != NULL)
 300                 return 0;
 301
 302         if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY)) < 0) {
 303                 fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
 304                 cache_addr = (caddr_t) - 1;     /* so we won't try again */
 305                 return -1;
 306         }
 307
 308         cache_size = st.st_size;
 309         cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
 310         close(fd);
 311         if (cache_addr == MAP_FAILED) {
 312                 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
 313                 return -1;
 314         }
 315
 316         header = (header_t *) cache_addr;
 317
 318         if (cache_size < sizeof(header_t)
 319             || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
 320             || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
 321             || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
 322             || cache_addr[cache_size - 1] != '\0')
 323         {
 324                 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 325                 goto fail;
 326         }
 327
 328         strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
 329         libent = (libentry_t *) & header[1];
 330
 331         for (i = 0; i < header->nlibs; i++) {
 332                 if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
 333                         fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 334                         goto fail;
 335                 }
 336         }
 337
 338         return 0;
 339
 340 fail:
 341         munmap(cache_addr, cache_size);
 342         cache_addr = (caddr_t) - 1;
 343         return -1;
 344 }
 345
 346 static int unmap_cache(void)
 347 {
 348         if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
 349                 return -1;
 350
 351 #if 1
 352         munmap(cache_addr, cache_size);
 353         cache_addr = NULL;
 354 #endif
 355
 356         return 0;
 357 }
 358 #else
 359 static __inline__ void map_cache(void)
 360 {
 361 }
 362 static __inline__ void unmap_cache(void)
 363 {
 364 }
 365 #endif
 366
 367 /* This function's behavior must exactly match that
 368  * in uClibc/ldso/ldso/dl-elf.c */
 369 static void search_for_named_library(char *name, char *result,
 370                                      const char *path_list)
 371 {
 372         int i, count = 1;
 373         char *path, *path_n;
 374         struct stat filestat;
 375
 376         /* We need a writable copy of this string */
 377         path = strdup(path_list);
 378         if (!path) {
 379                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 380                 exit(EXIT_FAILURE);
 381         }
 382         /* Eliminate all double //s */
 383         path_n = path;
 384         while ((path_n = strstr(path_n, "//"))) {
 385                 i = strlen(path_n);
 386                 memmove(path_n, path_n + 1, i - 1);
 387                 *(path_n + i - 1) = '\0';
 388         }
 389
 390         /* Replace colons with zeros in path_list and count them */
 391         for (i = strlen(path); i > 0; i--) {
 392                 if (path[i] == ':') {
 393                         path[i] = 0;
 394                         count++;
 395                 }
 396         }
 397         path_n = path;
 398         for (i = 0; i < count; i++) {
 399                 strcpy(result, path_n);
 400                 strcat(result, "/");
 401                 strcat(result, name);
 402                 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
 403                         free(path);
 404                         return;
 405                 }
 406                 path_n += (strlen(path_n) + 1);
 407         }
 408         free(path);
 409         *result = '\0';
 410 }
 411
 412 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
 413                                 int is_suid, struct library *lib)
 414 {
 415         char *buf;
 416         char *path;
 417         struct stat filestat;
 418
 419         /* If this is a fully resolved name, our job is easy */
 420         if (stat(lib->name, &filestat) == 0) {
 421                 lib->path = strdup(lib->name);
 422                 return;
 423         }
 424
 425         /* We need some elbow room here.  Make some room... */
 426         buf = malloc(1024);
 427         if (!buf) {
 428                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 429                 exit(EXIT_FAILURE);
 430         }
 431
 432         /* This function must match the behavior of _dl_load_shared_library
 433          * in readelflib1.c or things won't work out as expected... */
 434
 435         /* The ABI specifies that RPATH is searched first, so do that now.  */
 436         path = elf_find_rpath(ehdr, dynamic);
 437         if (path) {
 438                 search_for_named_library(lib->name, buf, path);
 439                 if (*buf != '\0') {
 440                         lib->path = buf;
 441                         return;
 442                 }
 443         }
 444
 445         /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
 446          * Since this app doesn't actually run an executable I will skip
 447          * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
 448         if (is_suid == 1)
 449                 path = NULL;
 450         else
 451                 path = getenv("LD_LIBRARY_PATH");
 452         if (path) {
 453                 search_for_named_library(lib->name, buf, path);
 454                 if (*buf != '\0') {
 455                         lib->path = buf;
 456                         return;
 457                 }
 458         }
 459 #ifdef __LDSO_CACHE_SUPPORT__
 460         if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
 461                 int i;
 462                 header_t *header = (header_t *) cache_addr;
 463                 libentry_t *libent = (libentry_t *) & header[1];
 464                 char *strs = (char *)&libent[header->nlibs];
 465
 466                 for (i = 0; i < header->nlibs; i++) {
 467                         if ((libent[i].flags == LIB_ELF ||
 468                              libent[i].flags == LIB_ELF_LIBC0 ||
 469                              libent[i].flags == LIB_ELF_LIBC5) &&
 470                             strcmp(lib->name, strs + libent[i].sooffset) == 0)
 471                         {
 472                                 lib->path = strdup(strs + libent[i].liboffset);
 473                                 return;
 474                         }
 475                 }
 476         }
 477 #endif
 478
 479         /* Next look for libraries wherever the shared library
 480          * loader was installed -- this is usually where we
 481          * should find things... */
 482         if (interp_dir) {
 483                 search_for_named_library(lib->name, buf, interp_dir);
 484                 if (*buf != '\0') {
 485                         lib->path = buf;
 486                         return;
 487                 }
 488         }
 489
 490         /* Lastly, search the standard list of paths for the library.
 491            This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
 492         path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
 493 #ifndef __LDSO_CACHE_SUPPORT__
 494             ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
 495 #endif
 496             ;
 497         search_for_named_library(lib->name, buf, path);
 498         if (*buf != '\0') {
 499                 lib->path = buf;
 500         } else {
 501                 free(buf);
 502                 lib->path = not_found;
 503         }
 504 }
 505
 506 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
 507 {
 508         char *tmp, *tmp1, *tmp2;
 509         struct library *cur, *newlib = lib_list;
 510
 511         if (!s || !strlen(s))
 512                 return 1;
 513
 514         tmp = s;
 515         while (*tmp) {
 516                 if (*tmp == '/')
 517                         s = tmp + 1;
 518                 tmp++;
 519         }
 520
 521         /* We add ldso elsewhere */
 522         if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
 523                 int len = strlen(interp_dir);
 524                 if (strcmp(s, interp_name + 1 + len) == 0)
 525                         return 1;
 526         }
 527
 528         for (cur = lib_list; cur; cur = cur->next) {
 529                 /* Check if this library is already in the list */
 530                 tmp1 = tmp2 = cur->name;
 531                 if (!cur->name)
 532                         continue;
 533                 while (*tmp1) {
 534                         if (*tmp1 == '/')
 535                                 tmp2 = tmp1 + 1;
 536                         tmp1++;
 537                 }
 538                 if (strcmp(tmp2, s) == 0) {
 539                         /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
 540                         return 0;
 541                 }
 542         }
 543
 544         /* Ok, this lib needs to be added to the list */
 545         newlib = malloc(sizeof(struct library));
 546         if (!newlib)
 547                 return 1;
 548         newlib->name = malloc(strlen(s) + 1);
 549         strcpy(newlib->name, s);
 550         newlib->resolved = 0;
 551         newlib->path = NULL;
 552         newlib->next = NULL;
 553
 554         /* Now try and locate where this library might be living... */
 555         locate_library_file(ehdr, dynamic, is_setuid, newlib);
 556
 557         /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 558         if (!lib_list) {
 559                 lib_list = newlib;
 560         } else {
 561                 for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 562                 cur->next = newlib;
 563         }
 564         return 0;
 565 }
 566
 567 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
 568 {
 569         ElfW(Dyn) *dyns;
 570
 571         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 572                 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
 573                         char *strtab;
 574                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 575                         add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 576                 }
 577         }
 578 }
 579
 580 #ifdef __LDSO_LDD_SUPPORT__
 581 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
 582 {
 583         ElfW(Phdr) *phdr;
 584
 585         if (interpreter_already_found == 1)
 586                 return NULL;
 587         phdr = elf_find_phdr_type(PT_INTERP, ehdr);
 588         if (phdr) {
 589                 struct library *cur, *newlib = NULL;
 590                 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
 591
 592                 char *tmp, *tmp1;
 593                 interp_name = strdup(s);
 594                 interp_dir = strdup(s);
 595                 tmp = strrchr(interp_dir, '/');
 596                 if (tmp)
 597                         *tmp = '\0';
 598                 else {
 599                         free(interp_dir);
 600                         interp_dir = interp_name;
 601                 }
 602                 tmp1 = tmp = s;
 603                 while (*tmp) {
 604                         if (*tmp == '/')
 605                                 tmp1 = tmp + 1;
 606                         tmp++;
 607                 }
 608                 for (cur = lib_list; cur; cur = cur->next) {
 609                         /* Check if this library is already in the list */
 610                         if (!tmp1 || !cur->name)
 611                                 return NULL;
 612                         if (strcmp(cur->name, tmp1) == 0) {
 613                                 /*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
 614                                 newlib = cur;
 615                                 free(newlib->name);
 616                                 if (newlib->path != not_found) {
 617                                         free(newlib->path);
 618                                 }
 619                                 newlib->name = NULL;
 620                                 newlib->path = NULL;
 621                                 break;
 622                         }
 623                 }
 624                 if (newlib == NULL)
 625                         newlib = malloc(sizeof(struct library));
 626                 if (!newlib)
 627                         return NULL;
 628                 newlib->name = malloc(strlen(s) + 1);
 629                 strcpy(newlib->name, s);
 630                 newlib->path = strdup(newlib->name);
 631                 newlib->resolved = 1;
 632                 newlib->next = NULL;
 633
 634 #if 0
 635                 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 636                 if (!lib_list) {
 637                         lib_list = newlib;
 638                 } else {
 639                         for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 640                         cur->next = newlib;
 641                 }
 642 #endif
 643                 interpreter_already_found = 1;
 644                 return newlib;
 645         }
 646         return NULL;
 647 }
 648 #endif /* __LDSO_LDD_SUPPORT__ */
 649
 650 /* map the .so, and locate interesting pieces */
 651 /*
 652 #warning "There may be two warnings here about vfork() clobbering, ignore them"
 653 */
 654 static int find_dependencies(char *filename)
 655 {
 656         int is_suid = 0;
 657         FILE *thefile;
 658         struct stat statbuf;
 659         ElfW(Ehdr) *ehdr = NULL;
 660         ElfW(Shdr) *dynsec = NULL;
 661         ElfW(Dyn) *dynamic = NULL;
 662 #ifdef __LDSO_LDD_SUPPORT__
 663         struct library *interp;
 664 #endif
 665
 666         if (filename == not_found)
 667                 return 0;
 668
 669         if (!filename) {
 670                 fprintf(stderr, "No filename specified.\n");
 671                 return -1;
 672         }
 673         if (!(thefile = fopen(filename, "r"))) {
 674                 perror(filename);
 675                 return -1;
 676         }
 677         if (fstat(fileno(thefile), &statbuf) < 0) {
 678                 perror(filename);
 679                 fclose(thefile);
 680                 return -1;
 681         }
 682
 683         if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
 684                 goto foo;
 685
 686         if (!S_ISREG(statbuf.st_mode))
 687                 goto foo;
 688
 689         /* mmap the file to make reading stuff from it effortless */
 690         ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
 691         if (ehdr == MAP_FAILED) {
 692                 fclose(thefile);
 693                 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
 694                 return -1;
 695         }
 696
 697 foo:
 698         fclose(thefile);
 699
 700         /* Check if this looks like a legit ELF file */
 701         if (check_elf_header(ehdr)) {
 702                 fprintf(stderr, "%s: not an ELF file.\n", filename);
 703                 return -1;
 704         }
 705         /* Check if this is the right kind of ELF file */
 706         if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
 707                 fprintf(stderr, "%s: not a dynamic executable\n", filename);
 708                 return -1;
 709         }
 710         if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
 711                 if (statbuf.st_mode & S_ISUID)
 712                         is_suid = 1;
 713                 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
 714                         is_suid = 1;
 715                 /* FIXME */
 716                 if (is_suid)
 717                         fprintf(stderr, "%s: is setuid\n", filename);
 718         }
 719
 720         interpreter_already_found = 0;
 721 #ifdef __LDSO_LDD_SUPPORT__
 722         interp = find_elf_interpreter(ehdr);
 723
 724         if (interp
 725             && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
 726             && ehdr->e_ident[EI_CLASS] == ELFCLASSM
 727             && ehdr->e_ident[EI_DATA] == ELFDATAM
 728             && ehdr->e_ident[EI_VERSION] == EV_CURRENT
 729             && MATCH_MACHINE(ehdr->e_machine))
 730         {
 731                 struct stat st;
 732                 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
 733                         pid_t pid;
 734                         int status;
 735                         static const char *const environment[] = {
 736                                 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
 737                                 "SHELL=/bin/sh",
 738                                 "LD_TRACE_LOADED_OBJECTS=1",
 739                                 NULL
 740                         };
 741 # ifdef __LDSO_STANDALONE_SUPPORT__
 742                         char * lib_path = getenv("LD_LIBRARY_PATH");
 743
 744                         /* The 'extended' environment inclusing the LD_LIBRARY_PATH */
 745                         static char *ext_environment[ARRAY_SIZE(environment) + 1];
 746                         char **envp = (char **) environment;
 747
 748                         if (lib_path) {
 749                                 /*
 750                                  * If the LD_LIBRARY_PATH is set, it needs to include it
 751                                  * into the environment for the new process to be spawned
 752                                  */
 753                                 char ** eenvp = (char **) ext_environment;
 754
 755                                 /* Copy the N-1 environment's entries */
 756                                 while (*envp)
 757                                         *eenvp++=*envp++;
 758
 759                                 /* Make room for LD_LIBRARY_PATH */
 760                                 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
 761                                                                           + strlen(lib_path));
 762                                 strcpy(*eenvp, "LD_LIBRARY_PATH=");
 763                                 strcat(*eenvp, lib_path);
 764                                 lib_path = *eenvp;
 765                                 /* ext_environment[size] is already NULL */
 766
 767                                 /* Use the extended environment */
 768                                 envp = ext_environment;
 769                         }
 770                         if ((pid = vfork()) == 0) {
 771                                 /*
 772                                  * Force to use the standard dynamic linker in stand-alone mode.
 773                                  * It will fails at runtime if support is not actually available
 774                                  */
 775                                 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
 776                                 _exit(0xdead);
 777                         }
 778 # else
 779                         if ((pid = vfork()) == 0) {
 780                                 /* Cool, it looks like we should be able to actually
 781                                  * run this puppy.  Do so now... */
 782                                 execle(filename, filename, NULL, environment);
 783                                 _exit(0xdead);
 784                         }
 785 # endif
 786                         /* Wait till it returns */
 787                         waitpid(pid, &status, 0);
 788
 789 # ifdef __LDSO_STANDALONE_SUPPORT__
 790                         /* Do not leak */
 791                         free(lib_path);
 792 # endif
 793
 794                         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 795                                 return 1;
 796                         }
 797
 798                         /* If the exec failed, we fall through to trying to find
 799                          * all the needed libraries ourselves by rummaging about
 800                          * in the ELF headers... */
 801                 }
 802         }
 803 #endif
 804
 805         dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
 806         if (dynsec) {
 807                 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
 808                 find_needed_libraries(ehdr, dynamic, is_suid);
 809         }
 810
 811         return 0;
 812 }
 813
 814 int main(int argc, char **argv)
 815 {
 816         int multi = 0;
 817         int got_em_all = 1;
 818         char *filename = NULL;
 819         struct library *cur;
 820
 821         if (argc < 2) {
 822                 fprintf(stderr, "ldd: missing file arguments\n"
 823                                 "Try `ldd --help' for more information.\n");
 824                 exit(EXIT_FAILURE);
 825         }
 826         if (argc > 2)
 827                 multi++;
 828
 829         while (--argc > 0) {
 830                 ++argv;
 831
 832                 if (strcmp(*argv, "--") == 0) {
 833                         /* Ignore "--" */
 834                         continue;
 835                 }
 836
 837                 if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
 838                         fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
 839                                         "\t--help\t\tprint this help and exit\n");
 840                         exit(EXIT_SUCCESS);
 841                 }
 842
 843                 filename = *argv;
 844                 if (!filename) {
 845                         fprintf(stderr, "No filename specified.\n");
 846                         exit(EXIT_FAILURE);
 847                 }
 848
 849                 if (multi) {
 850                         printf("%s:\n", *argv);
 851                 }
 852
 853                 map_cache();
 854
 855                 if (find_dependencies(filename) != 0)
 856                         continue;
 857
 858                 while (got_em_all) {
 859                         got_em_all = 0;
 860                         /* Keep walking the list till everybody is resolved */
 861                         for (cur = lib_list; cur; cur = cur->next) {
 862                                 if (cur->resolved == 0 && cur->path) {
 863                                         got_em_all = 1;
 864                                         printf("checking sub-depends for '%s'\n", cur->path);
 865                                         find_dependencies(cur->path);
 866                                         cur->resolved = 1;
 867                                 }
 868                         }
 869                 }
 870
 871                 unmap_cache();
 872
 873                 /* Print the list */
 874                 got_em_all = 0;
 875                 for (cur = lib_list; cur; cur = cur->next) {
 876                         got_em_all = 1;
 877                         printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
 878                 }
 879                 if (interp_name && interpreter_already_found == 1)
 880                         printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
 881                 else
 882                         printf("\tnot a dynamic executable\n");
 883
 884                 for (cur = lib_list; cur; cur = cur->next) {
 885                         free(cur->name);
 886                         cur->name = NULL;
 887                         if (cur->path && cur->path != not_found) {
 888                                 free(cur->path);
 889                                 cur->path = NULL;
 890                         }
 891                 }
 892                 lib_list = NULL;
 893         }
 894
 895         return 0;
 896 }