utils/ldd.c

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