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