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(__kvx__)
  18 #define MATCH_MACHINE(x) (x == EM_KVX)
  19 #define ELFCLASSM       ELFCLASS64
  20 #endif
  21
  22 #if defined(__aarch64__)
  23 #define MATCH_MACHINE(x) (x == EM_AARCH64)
  24 #define ELFCLASSM       ELFCLASS64
  25 #endif
  26
  27 #if defined(__alpha__)
  28 #define MATCH_MACHINE(x) (x == EM_ALPHA)
  29 #define ELFCLASSM       ELFCLASS64
  30 #endif
  31
  32 #if defined(__arc__)
  33 #define MATCH_MACHINE(x) (x == EM_ARCOMPACT || x == EM_ARCV2)
  34 #define ELFCLASSM      ELFCLASS32
  35 #endif
  36
  37 #if defined(__ARC64_ARCH32__)
  38 #define MATCH_MACHINE(x) (x == EM_ARCV3_32)
  39 #define ELFCLASSM      ELFCLASS32
  40 #endif
  41
  42 #if defined(__arm__) || defined(__thumb__)
  43 #define MATCH_MACHINE(x) (x == EM_ARM)
  44 #define ELFCLASSM       ELFCLASS32
  45 #endif
  46
  47 #if defined(__avr32__)
  48 #define MATCH_MACHINE(x) (x == EM_AVR32)
  49 #define ELFCLASSM      ELFCLASS32
  50 #endif
  51
  52 #if defined(__bfin__)
  53 #define MATCH_MACHINE(x) (x == EM_BLACKFIN)
  54 #define ELFCLASSM      ELFCLASS32
  55 #endif
  56
  57 #if defined(__TMS320C6X__)
  58 #define MATCH_MACHINE(x) (x == EM_TI_C6000)
  59 #define ELFCLASSM       ELFCLASS32
  60 #endif
  61
  62 #if defined(__cris__)
  63 #define MATCH_MACHINE(x) (x == EM_CRIS)
  64 #define ELFCLASSM       ELFCLASS32
  65 #endif
  66
  67 #if defined(__csky__)
  68 #define MATCH_MACHINE(x) (x == EM_MCORE)
  69 #define ELFCLASSM       ELFCLASS32
  70 #endif
  71
  72 #if defined(__frv__)
  73 #define MATCH_MACHINE(x) (x == EM_CYGNUS_FRV)
  74 #define ELFCLASSM       ELFCLASS32
  75 #endif
  76
  77 #if defined(__hppa__)
  78 #define MATCH_MACHINE(x) (x == EM_PARISC)
  79 #if defined(__LP64__)
  80 #define ELFCLASSM               ELFCLASS64
  81 #else
  82 #define ELFCLASSM               ELFCLASS32
  83 #endif
  84 #endif
  85
  86 #if defined(__i386__)
  87 #ifndef EM_486
  88 #define MATCH_MACHINE(x) (x == EM_386)
  89 #else
  90 #define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
  91 #endif
  92 #define ELFCLASSM       ELFCLASS32
  93 #endif
  94
  95 #if defined(__ia64__)
  96 #define MATCH_MACHINE(x) (x == EM_IA_64)
  97 #define ELFCLASSM       ELFCLASS64
  98 #endif
  99
 100 #if defined(__mc68000__)
 101 #define MATCH_MACHINE(x) (x == EM_68K)
 102 #define ELFCLASSM       ELFCLASS32
 103 #endif
 104
 105 #if defined(__metag__)
 106 #define MATCH_MACHINE(x) (x == EM_METAG)
 107 #define ELFCLASSM       ELFCLASS32
 108 #endif
 109
 110 #if defined(__microblaze__)
 111 #define MATCH_MACHINE(x) (x == EM_MICROBLAZE)
 112 #define ELFCLASSM       ELFCLASS32
 113 #endif
 114
 115 #if defined(__mips__)
 116 #define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
 117 #define ELFCLASSM       ELFCLASS32
 118 #endif
 119
 120 #if defined(__nds32__)
 121 #define MATCH_MACHINE(x) (x == EM_NDS32)
 122 #define ELFCLASSM       ELFCLASS32
 123 #endif
 124
 125 #if defined(__nios2__)
 126 #define MATCH_MACHINE(x) (x == EM_NIOS32)
 127 #define ELFCLASSM       ELFCLASS32
 128 #endif
 129
 130 #if defined(__powerpc__)
 131 #define MATCH_MACHINE(x) (x == EM_PPC)
 132 #define ELFCLASSM       ELFCLASS32
 133 #endif
 134
 135 #if defined(__riscv)
 136 #define MATCH_MACHINE(x) (x == EM_RISCV)
 137 #define ELFCLASSM       ELFCLASS64
 138 #endif
 139
 140 #if defined(__sh__)
 141 #define MATCH_MACHINE(x) (x == EM_SH)
 142 #define ELFCLASSM       ELFCLASS32
 143 #endif
 144
 145 #if defined(__sparc__)
 146 #define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
 147 #define ELFCLASSM    ELFCLASS32
 148 #endif
 149
 150 #if defined(__x86_64__)
 151 #define MATCH_MACHINE(x) (x == EM_X86_64)
 152 #define ELFCLASSM       ELFCLASS64
 153 #endif
 154
 155 #if defined(__xtensa__)
 156 #define MATCH_MACHINE(x) (x == EM_XTENSA)
 157 #define ELFCLASSM       ELFCLASS32
 158 #endif
 159
 160 #ifndef MATCH_MACHINE
 161 # ifdef __linux__
 162 #  include <asm/elf.h>
 163 # endif
 164 # ifdef ELF_ARCH
 165 #  define MATCH_MACHINE(x) (x == ELF_ARCH)
 166 # endif
 167 # ifdef ELF_CLASS
 168 #  define ELFCLASSM ELF_CLASS
 169 # endif
 170 #endif
 171 #ifndef MATCH_MACHINE
 172 # warning "You really should add a MATCH_MACHINE() macro for your architecture"
 173 #endif
 174
 175 #if UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE
 176 #define ELFDATAM        ELFDATA2LSB
 177 #elif UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG
 178 #define ELFDATAM        ELFDATA2MSB
 179 #endif
 180
 181 #define TRUSTED_LDSO    UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
 182
 183 struct library {
 184         char *name;
 185         int resolved;
 186         char *path;
 187         struct library *next;
 188 };
 189 static struct library *lib_list = NULL;
 190 static char not_found[] = "not found";
 191 static char *interp_name = NULL;
 192 static char *interp_dir = NULL;
 193 static int byteswap;
 194 static int interpreter_already_found = 0;
 195
 196 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
 197 {
 198         if (byteswap) {
 199                 return (bswap_32(value));
 200         } else {
 201                 return (value);
 202         }
 203 }
 204 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
 205 {
 206         if (byteswap) {
 207                 return (bswap_64(value));
 208         } else {
 209                 return (value);
 210         }
 211 }
 212
 213 #if __WORDSIZE == 64
 214 # define byteswap_to_host(x) byteswap64_to_host(x)
 215 #else
 216 # define byteswap_to_host(x) byteswap32_to_host(x)
 217 #endif
 218
 219 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
 220 {
 221         int j;
 222         ElfW(Shdr) *shdr;
 223         shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
 224         for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
 225                 if (key == byteswap32_to_host(shdr->sh_type)) {
 226                         return shdr;
 227                 }
 228         }
 229         return NULL;
 230 }
 231
 232 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
 233 {
 234         int j;
 235         ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
 236         for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
 237                 if (type == byteswap32_to_host(phdr->p_type)) {
 238                         return phdr;
 239                 }
 240         }
 241         return NULL;
 242 }
 243
 244 /* Returns value if return_val==1, ptr otherwise */
 245 static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
 246                        ElfW(Ehdr) *ehdr, int return_val)
 247 {
 248         ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
 249         unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
 250         for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
 251                 if (key == byteswap_to_host(dynp->d_tag)) {
 252                         if (return_val == 1)
 253                                 return (void *)byteswap_to_host(dynp->d_un.d_val);
 254                         else
 255                                 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
 256                 }
 257         }
 258         return NULL;
 259 }
 260
 261 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
 262 {
 263         ElfW(Dyn) *dyns;
 264
 265         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 266                 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
 267                         char *strtab;
 268                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 269                         return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 270                 }
 271         }
 272         return NULL;
 273 }
 274
 275 static int check_elf_header(ElfW(Ehdr) *const ehdr)
 276 {
 277         if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
 278          /* Use __WORDSIZE, not ELFCLASSM which depends on the host */
 279          || ehdr->e_ident[EI_CLASS] != (__WORDSIZE >> 5)
 280          || ehdr->e_ident[EI_VERSION] != EV_CURRENT
 281         ) {
 282                 return 1;
 283         }
 284
 285         /* Check if the target endianness matches the host's endianness */
 286         byteswap = !(ehdr->e_ident[5] == ELFDATAM);
 287
 288         /* Be very lazy, and only byteswap the stuff we use */
 289         if (byteswap) {
 290                 ehdr->e_type = bswap_16(ehdr->e_type);
 291                 ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
 292                 ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
 293                 ehdr->e_phnum = bswap_16(ehdr->e_phnum);
 294                 ehdr->e_shnum = bswap_16(ehdr->e_shnum);
 295         }
 296
 297         return 0;
 298 }
 299
 300 #ifdef __LDSO_CACHE_SUPPORT__
 301 static caddr_t cache_addr = NULL;
 302 static size_t cache_size = 0;
 303
 304 static int map_cache(void)
 305 {
 306         int fd;
 307         struct stat st;
 308         header_t *header;
 309         libentry_t *libent;
 310         int i, strtabsize;
 311
 312         if (cache_addr == (caddr_t) - 1)
 313                 return -1;
 314         else if (cache_addr != NULL)
 315                 return 0;
 316
 317         if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY)) < 0) {
 318                 fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
 319                 cache_addr = (caddr_t) - 1;     /* so we won't try again */
 320                 return -1;
 321         }
 322
 323         cache_size = st.st_size;
 324         cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
 325         close(fd);
 326         if (cache_addr == MAP_FAILED) {
 327                 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
 328                 return -1;
 329         }
 330
 331         header = (header_t *) cache_addr;
 332
 333         if (cache_size < sizeof(header_t)
 334             || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
 335             || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
 336             || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
 337             || cache_addr[cache_size - 1] != '\0')
 338         {
 339                 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 340                 goto fail;
 341         }
 342
 343         strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
 344         libent = (libentry_t *) & header[1];
 345
 346         for (i = 0; i < header->nlibs; i++) {
 347                 if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
 348                         fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 349                         goto fail;
 350                 }
 351         }
 352
 353         return 0;
 354
 355 fail:
 356         munmap(cache_addr, cache_size);
 357         cache_addr = (caddr_t) - 1;
 358         return -1;
 359 }
 360
 361 static int unmap_cache(void)
 362 {
 363         if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
 364                 return -1;
 365
 366 #if 1
 367         munmap(cache_addr, cache_size);
 368         cache_addr = NULL;
 369 #endif
 370
 371         return 0;
 372 }
 373 #else
 374 static __inline__ void map_cache(void)
 375 {
 376 }
 377 static __inline__ void unmap_cache(void)
 378 {
 379 }
 380 #endif
 381
 382 /* This function's behavior must exactly match that
 383  * in uClibc/ldso/ldso/dl-elf.c */
 384 static void search_for_named_library(char *name, char *result,
 385                                      const char *path_list)
 386 {
 387         int i, count = 1;
 388         char *path, *path_n;
 389         struct stat filestat;
 390
 391         /* We need a writable copy of this string */
 392         path = strdup(path_list);
 393         if (!path) {
 394                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 395                 exit(EXIT_FAILURE);
 396         }
 397         /* Eliminate all double //s */
 398         path_n = path;
 399         while ((path_n = strstr(path_n, "//"))) {
 400                 i = strlen(path_n);
 401                 memmove(path_n, path_n + 1, i - 1);
 402                 *(path_n + i - 1) = '\0';
 403         }
 404
 405         /* Replace colons with zeros in path_list and count them */
 406         for (i = strlen(path); i > 0; i--) {
 407                 if (path[i] == ':') {
 408                         path[i] = 0;
 409                         count++;
 410                 }
 411         }
 412         path_n = path;
 413         for (i = 0; i < count; i++) {
 414                 strcpy(result, path_n);
 415                 strcat(result, "/");
 416                 strcat(result, name);
 417                 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
 418                         free(path);
 419                         return;
 420                 }
 421                 path_n += (strlen(path_n) + 1);
 422         }
 423         free(path);
 424         *result = '\0';
 425 }
 426
 427 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
 428                                 int is_suid, struct library *lib)
 429 {
 430         char *buf;
 431         char *path;
 432         struct stat filestat;
 433
 434         /* If this is a fully resolved name, our job is easy */
 435         if (stat(lib->name, &filestat) == 0) {
 436                 lib->path = strdup(lib->name);
 437                 return;
 438         }
 439
 440         /* We need some elbow room here.  Make some room... */
 441         buf = malloc(1024);
 442         if (!buf) {
 443                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 444                 exit(EXIT_FAILURE);
 445         }
 446
 447         /* This function must match the behavior of _dl_load_shared_library
 448          * in readelflib1.c or things won't work out as expected... */
 449
 450         /* The ABI specifies that RPATH is searched first, so do that now.  */
 451         path = elf_find_rpath(ehdr, dynamic);
 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
 460         /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
 461          * Since this app doesn't actually run an executable I will skip
 462          * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
 463         if (is_suid == 1)
 464                 path = NULL;
 465         else
 466                 path = getenv("LD_LIBRARY_PATH");
 467         if (path) {
 468                 search_for_named_library(lib->name, buf, path);
 469                 if (*buf != '\0') {
 470                         lib->path = buf;
 471                         return;
 472                 }
 473         }
 474 #ifdef __LDSO_CACHE_SUPPORT__
 475         if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
 476                 int i;
 477                 header_t *header = (header_t *) cache_addr;
 478                 libentry_t *libent = (libentry_t *) & header[1];
 479                 char *strs = (char *)&libent[header->nlibs];
 480
 481                 for (i = 0; i < header->nlibs; i++) {
 482                         if ((libent[i].flags == LIB_ELF ||
 483                              libent[i].flags == LIB_ELF_LIBC0 ||
 484                              libent[i].flags == LIB_ELF_LIBC5) &&
 485                             strcmp(lib->name, strs + libent[i].sooffset) == 0)
 486                         {
 487                                 lib->path = strdup(strs + libent[i].liboffset);
 488                                 return;
 489                         }
 490                 }
 491         }
 492 #endif
 493
 494         /* Next look for libraries wherever the shared library
 495          * loader was installed -- this is usually where we
 496          * should find things... */
 497         if (interp_dir) {
 498                 search_for_named_library(lib->name, buf, interp_dir);
 499                 if (*buf != '\0') {
 500                         lib->path = buf;
 501                         return;
 502                 }
 503         }
 504
 505         /* Lastly, search the standard list of paths for the library.
 506            This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
 507         path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
 508 #ifndef __LDSO_CACHE_SUPPORT__
 509             ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
 510 #endif
 511             ;
 512         search_for_named_library(lib->name, buf, path);
 513         if (*buf != '\0') {
 514                 lib->path = buf;
 515         } else {
 516                 free(buf);
 517                 lib->path = not_found;
 518         }
 519 }
 520
 521 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
 522 {
 523         char *tmp, *tmp1, *tmp2;
 524         struct library *cur, *newlib = lib_list;
 525
 526         if (!s || !strlen(s))
 527                 return 1;
 528
 529         tmp = s;
 530         while (*tmp) {
 531                 if (*tmp == '/')
 532                         s = tmp + 1;
 533                 tmp++;
 534         }
 535
 536         /* We add ldso elsewhere */
 537         if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
 538                 int len = strlen(interp_dir);
 539                 if (strcmp(s, interp_name + 1 + len) == 0)
 540                         return 1;
 541         }
 542
 543         for (cur = lib_list; cur; cur = cur->next) {
 544                 /* Check if this library is already in the list */
 545                 tmp1 = tmp2 = cur->name;
 546                 if (!cur->name)
 547                         continue;
 548                 while (*tmp1) {
 549                         if (*tmp1 == '/')
 550                                 tmp2 = tmp1 + 1;
 551                         tmp1++;
 552                 }
 553                 if (strcmp(tmp2, s) == 0) {
 554                         /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
 555                         return 0;
 556                 }
 557         }
 558
 559         /* Ok, this lib needs to be added to the list */
 560         newlib = malloc(sizeof(struct library));
 561         if (!newlib)
 562                 return 1;
 563         newlib->name = malloc(strlen(s) + 1);
 564         strcpy(newlib->name, s);
 565         newlib->resolved = 0;
 566         newlib->path = NULL;
 567         newlib->next = NULL;
 568
 569         /* Now try and locate where this library might be living... */
 570         locate_library_file(ehdr, dynamic, is_setuid, newlib);
 571
 572         /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 573         if (!lib_list) {
 574                 lib_list = newlib;
 575         } else {
 576                 for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 577                 cur->next = newlib;
 578         }
 579         return 0;
 580 }
 581
 582 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
 583 {
 584         ElfW(Dyn) *dyns;
 585
 586         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 587                 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
 588                         char *strtab;
 589                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 590                         add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 591                 }
 592         }
 593 }
 594
 595 #ifdef __LDSO_LDD_SUPPORT__
 596 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
 597 {
 598         ElfW(Phdr) *phdr;
 599
 600         if (interpreter_already_found == 1)
 601                 return NULL;
 602         phdr = elf_find_phdr_type(PT_INTERP, ehdr);
 603         if (phdr) {
 604                 struct library *cur, *newlib = NULL;
 605                 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
 606
 607                 char *tmp, *tmp1;
 608                 interp_name = strdup(s);
 609                 interp_dir = strdup(s);
 610                 tmp = strrchr(interp_dir, '/');
 611                 if (tmp)
 612                         *tmp = '\0';
 613                 else {
 614                         free(interp_dir);
 615                         interp_dir = interp_name;
 616                 }
 617                 tmp1 = tmp = s;
 618                 while (*tmp) {
 619                         if (*tmp == '/')
 620                                 tmp1 = tmp + 1;
 621                         tmp++;
 622                 }
 623                 for (cur = lib_list; cur; cur = cur->next) {
 624                         /* Check if this library is already in the list */
 625                         if (!tmp1 || !cur->name)
 626                                 return NULL;
 627                         if (strcmp(cur->name, tmp1) == 0) {
 628                                 /*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
 629                                 newlib = cur;
 630                                 free(newlib->name);
 631                                 if (newlib->path != not_found) {
 632                                         free(newlib->path);
 633                                 }
 634                                 newlib->name = NULL;
 635                                 newlib->path = NULL;
 636                                 break;
 637                         }
 638                 }
 639                 if (newlib == NULL)
 640                         newlib = malloc(sizeof(struct library));
 641                 if (!newlib)
 642                         return NULL;
 643                 newlib->name = malloc(strlen(s) + 1);
 644                 strcpy(newlib->name, s);
 645                 newlib->path = strdup(newlib->name);
 646                 newlib->resolved = 1;
 647                 newlib->next = NULL;
 648
 649 #if 0
 650                 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 651                 if (!lib_list) {
 652                         lib_list = newlib;
 653                 } else {
 654                         for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 655                         cur->next = newlib;
 656                 }
 657 #endif
 658                 interpreter_already_found = 1;
 659                 return newlib;
 660         }
 661         return NULL;
 662 }
 663 #endif /* __LDSO_LDD_SUPPORT__ */
 664
 665 /* map the .so, and locate interesting pieces */
 666 /*
 667 #warning "There may be two warnings here about vfork() clobbering, ignore them"
 668 */
 669 static int find_dependencies(char *filename)
 670 {
 671         int is_suid = 0;
 672         FILE *thefile;
 673         struct stat statbuf;
 674         ElfW(Ehdr) *ehdr = NULL;
 675         ElfW(Shdr) *dynsec = NULL;
 676         ElfW(Dyn) *dynamic = NULL;
 677 #ifdef __LDSO_LDD_SUPPORT__
 678         struct library *interp;
 679 #endif
 680
 681         if (filename == not_found)
 682                 return 0;
 683
 684         if (!filename) {
 685                 fprintf(stderr, "No filename specified.\n");
 686                 return -1;
 687         }
 688         if (!(thefile = fopen(filename, "r"))) {
 689                 perror(filename);
 690                 return -1;
 691         }
 692         if (fstat(fileno(thefile), &statbuf) < 0) {
 693                 perror(filename);
 694                 fclose(thefile);
 695                 return -1;
 696         }
 697
 698         if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
 699                 goto foo;
 700
 701         if (!S_ISREG(statbuf.st_mode))
 702                 goto foo;
 703
 704         /* mmap the file to make reading stuff from it effortless */
 705         ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
 706         if (ehdr == MAP_FAILED) {
 707                 fclose(thefile);
 708                 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
 709                 return -1;
 710         }
 711
 712 foo:
 713         fclose(thefile);
 714
 715         /* Check if this looks like a legit ELF file */
 716         if (check_elf_header(ehdr)) {
 717                 fprintf(stderr, "%s: not an ELF file.\n", filename);
 718                 return -1;
 719         }
 720         /* Check if this is the right kind of ELF file */
 721         if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
 722                 fprintf(stderr, "%s: not a dynamic executable\n", filename);
 723                 return -1;
 724         }
 725         if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
 726                 if (statbuf.st_mode & S_ISUID)
 727                         is_suid = 1;
 728                 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
 729                         is_suid = 1;
 730                 /* FIXME */
 731                 if (is_suid)
 732                         fprintf(stderr, "%s: is setuid\n", filename);
 733         }
 734
 735         interpreter_already_found = 0;
 736 #ifdef __LDSO_LDD_SUPPORT__
 737         interp = find_elf_interpreter(ehdr);
 738
 739         if (interp
 740             && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
 741             && ehdr->e_ident[EI_CLASS] == ELFCLASSM
 742             && ehdr->e_ident[EI_DATA] == ELFDATAM
 743             && ehdr->e_ident[EI_VERSION] == EV_CURRENT
 744             && MATCH_MACHINE(ehdr->e_machine))
 745         {
 746                 struct stat st;
 747                 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
 748                         pid_t pid;
 749                         int status;
 750                         static const char *const environment[] = {
 751                                 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
 752                                 "SHELL=/bin/sh",
 753                                 "LD_TRACE_LOADED_OBJECTS=1",
 754                                 NULL
 755                         };
 756 # ifdef __LDSO_STANDALONE_SUPPORT__
 757                         char * lib_path = getenv("LD_LIBRARY_PATH");
 758
 759                         /* The 'extended' environment inclusing the LD_LIBRARY_PATH */
 760                         static char *ext_environment[ARRAY_SIZE(environment) + 1];
 761                         char **envp = (char **) environment;
 762
 763                         if (lib_path) {
 764                                 /*
 765                                  * If the LD_LIBRARY_PATH is set, it needs to include it
 766                                  * into the environment for the new process to be spawned
 767                                  */
 768                                 char ** eenvp = (char **) ext_environment;
 769
 770                                 /* Copy the N-1 environment's entries */
 771                                 while (*envp)
 772                                         *eenvp++=*envp++;
 773
 774                                 /* Make room for LD_LIBRARY_PATH */
 775                                 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
 776                                                                           + strlen(lib_path));
 777                                 strcpy(*eenvp, "LD_LIBRARY_PATH=");
 778                                 strcat(*eenvp, lib_path);
 779                                 lib_path = *eenvp;
 780                                 /* ext_environment[size] is already NULL */
 781
 782                                 /* Use the extended environment */
 783                                 envp = ext_environment;
 784                         }
 785                         if ((pid = vfork()) == 0) {
 786                                 /*
 787                                  * Force to use the standard dynamic linker in stand-alone mode.
 788                                  * It will fails at runtime if support is not actually available
 789                                  */
 790                                 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
 791                                 _exit(0xdead);
 792                         }
 793 # else
 794                         if ((pid = vfork()) == 0) {
 795                                 /* Cool, it looks like we should be able to actually
 796                                  * run this puppy.  Do so now... */
 797                                 execle(filename, filename, NULL, environment);
 798                                 _exit(0xdead);
 799                         }
 800 # endif
 801                         /* Wait till it returns */
 802                         waitpid(pid, &status, 0);
 803
 804 # ifdef __LDSO_STANDALONE_SUPPORT__
 805                         /* Do not leak */
 806                         free(lib_path);
 807 # endif
 808
 809                         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 810                                 return 1;
 811                         }
 812
 813                         /* If the exec failed, we fall through to trying to find
 814                          * all the needed libraries ourselves by rummaging about
 815                          * in the ELF headers... */
 816                 }
 817         }
 818 #endif
 819
 820         dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
 821         if (dynsec) {
 822                 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
 823                 find_needed_libraries(ehdr, dynamic, is_suid);
 824         }
 825
 826         return 0;
 827 }
 828
 829 int main(int argc, char **argv)
 830 {
 831         int multi = 0;
 832         int got_em_all = 1;
 833         char *filename = NULL;
 834         struct library *cur;
 835
 836         if (argc < 2) {
 837                 fprintf(stderr, "ldd: missing file arguments\n"
 838                                 "Try `ldd --help' for more information.\n");
 839                 exit(EXIT_FAILURE);
 840         }
 841         if (argc > 2)
 842                 multi++;
 843
 844         while (--argc > 0) {
 845                 ++argv;
 846
 847                 if (strcmp(*argv, "--") == 0) {
 848                         /* Ignore "--" */
 849                         continue;
 850                 }
 851
 852                 if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
 853                         fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
 854                                         "\t--help\t\tprint this help and exit\n");
 855                         exit(EXIT_SUCCESS);
 856                 }
 857
 858                 filename = *argv;
 859                 if (!filename) {
 860                         fprintf(stderr, "No filename specified.\n");
 861                         exit(EXIT_FAILURE);
 862                 }
 863
 864                 if (multi) {
 865                         printf("%s:\n", *argv);
 866                 }
 867
 868                 map_cache();
 869
 870                 if (find_dependencies(filename) != 0)
 871                         continue;
 872
 873                 while (got_em_all) {
 874                         got_em_all = 0;
 875                         /* Keep walking the list till everybody is resolved */
 876                         for (cur = lib_list; cur; cur = cur->next) {
 877                                 if (cur->resolved == 0 && cur->path) {
 878                                         got_em_all = 1;
 879                                         printf("checking sub-depends for '%s'\n", cur->path);
 880                                         find_dependencies(cur->path);
 881                                         cur->resolved = 1;
 882                                 }
 883                         }
 884                 }
 885
 886                 unmap_cache();
 887
 888                 /* Print the list */
 889                 got_em_all = 0;
 890                 for (cur = lib_list; cur; cur = cur->next) {
 891                         got_em_all = 1;
 892                         printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
 893                 }
 894                 if (interp_name && interpreter_already_found == 1)
 895                         printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
 896                 else
 897                         printf("\tnot a dynamic executable\n");
 898
 899                 for (cur = lib_list; cur; cur = cur->next) {
 900                         free(cur->name);
 901                         cur->name = NULL;
 902                         if (cur->path && cur->path != not_found) {
 903                                 free(cur->path);
 904                                 cur->path = NULL;
 905                         }
 906                 }
 907                 lib_list = NULL;
 908         }
 909
 910         return 0;
 911 }