utils/ldd.c

   1 /*
   2  * A small little ldd implementation for uClibc
   3  *
   4  * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
   5  *
   6  * Several functions in this file (specifically, elf_find_section_type(),
   7  * elf_find_phdr_type(), and elf_find_dynamic(), were stolen from elflib.c from
   8  * elfvector (http://www.BitWagon.com/elfvector.html) by John F. Reiser
   9  * <jreiser@BitWagon.com>, which is copyright 2000 BitWagon Software LLC
  10  * (GPL2).
  11  *
  12  * Licensed under GPLv2 or later
  13  */
  14
  15 #include "porting.h"
  16
  17 #if defined(__aarch64__)
  18 #define MATCH_MACHINE(x) (x == EM_AARCH64)
  19 #define ELFCLASSM       ELFCLASS64
  20 #endif
  21
  22 #if defined(__alpha__)
  23 #define MATCH_MACHINE(x) (x == EM_ALPHA)
  24 #define ELFCLASSM       ELFCLASS64
  25 #endif
  26
  27 #if defined(__arc__)
  28 #define MATCH_MACHINE(x) (x == EM_ARCOMPACT)
  29 #define ELFCLASSM      ELFCLASS32
  30 #endif
  31
  32 #if defined(__arm__) || defined(__thumb__)
  33 #define MATCH_MACHINE(x) (x == EM_ARM)
  34 #define ELFCLASSM       ELFCLASS32
  35 #endif
  36
  37 #if defined(__avr32__)
  38 #define MATCH_MACHINE(x) (x == EM_AVR32)
  39 #define ELFCLASSM      ELFCLASS32
  40 #endif
  41
  42 #if defined(__bfin__)
  43 #define MATCH_MACHINE(x) (x == EM_BLACKFIN)
  44 #define ELFCLASSM      ELFCLASS32
  45 #endif
  46
  47 #if defined(__TMS320C6X__)
  48 #define MATCH_MACHINE(x) (x == EM_TI_C6000)
  49 #define ELFCLASSM       ELFCLASS32
  50 #endif
  51
  52 #if defined(__cris__)
  53 #define MATCH_MACHINE(x) (x == EM_CRIS)
  54 #define ELFCLASSM       ELFCLASS32
  55 #endif
  56
  57 #if defined(__csky__)
  58 #define MATCH_MACHINE(x) (x == EM_MCORE)
  59 #define ELFCLASSM       ELFCLASS32
  60 #endif
  61
  62 #if defined(__frv__)
  63 #define MATCH_MACHINE(x) (x == EM_CYGNUS_FRV)
  64 #define ELFCLASSM       ELFCLASS32
  65 #endif
  66
  67 #if defined(__hppa__)
  68 #define MATCH_MACHINE(x) (x == EM_PARISC)
  69 #if defined(__LP64__)
  70 #define ELFCLASSM               ELFCLASS64
  71 #else
  72 #define ELFCLASSM               ELFCLASS32
  73 #endif
  74 #endif
  75
  76 #if defined(__i386__)
  77 #ifndef EM_486
  78 #define MATCH_MACHINE(x) (x == EM_386)
  79 #else
  80 #define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
  81 #endif
  82 #define ELFCLASSM       ELFCLASS32
  83 #endif
  84
  85 #if defined(__ia64__)
  86 #define MATCH_MACHINE(x) (x == EM_IA_64)
  87 #define ELFCLASSM       ELFCLASS64
  88 #endif
  89
  90 #if defined(__mc68000__)
  91 #define MATCH_MACHINE(x) (x == EM_68K)
  92 #define ELFCLASSM       ELFCLASS32
  93 #endif
  94
  95 #if defined(__metag__)
  96 #define MATCH_MACHINE(x) (x == EM_METAG)
  97 #define ELFCLASSM       ELFCLASS32
  98 #endif
  99
 100 #if defined(__microblaze__)
 101 #define MATCH_MACHINE(x) (x == EM_MICROBLAZE)
 102 #define ELFCLASSM       ELFCLASS32
 103 #endif
 104
 105 #if defined(__mips__)
 106 #define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
 107 #define ELFCLASSM       ELFCLASS32
 108 #endif
 109
 110 #if defined(__nds32__)
 111 #define MATCH_MACHINE(x) (x == EM_NDS32)
 112 #define ELFCLASSM       ELFCLASS32
 113 #endif
 114
 115 #if defined(__nios2__)
 116 #define MATCH_MACHINE(x) (x == EM_NIOS32)
 117 #define ELFCLASSM       ELFCLASS32
 118 #endif
 119
 120 #if defined(__powerpc__)
 121 #define MATCH_MACHINE(x) (x == EM_PPC)
 122 #define ELFCLASSM       ELFCLASS32
 123 #endif
 124
 125 #if defined(__riscv)
 126 #define MATCH_MACHINE(x) (x == EM_RISCV)
 127 #define ELFCLASSM       ELFCLASS64
 128 #endif
 129
 130 #if defined(__sh__)
 131 #define MATCH_MACHINE(x) (x == EM_SH)
 132 #define ELFCLASSM       ELFCLASS32
 133 #endif
 134
 135 #if defined(__sparc__)
 136 #define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS)
 137 #define ELFCLASSM    ELFCLASS32
 138 #endif
 139
 140 #if defined(__x86_64__)
 141 #define MATCH_MACHINE(x) (x == EM_X86_64)
 142 #define ELFCLASSM       ELFCLASS64
 143 #endif
 144
 145 #if defined(__xtensa__)
 146 #define MATCH_MACHINE(x) (x == EM_XTENSA)
 147 #define ELFCLASSM       ELFCLASS32
 148 #endif
 149
 150 #ifndef MATCH_MACHINE
 151 # ifdef __linux__
 152 #  include <asm/elf.h>
 153 # endif
 154 # ifdef ELF_ARCH
 155 #  define MATCH_MACHINE(x) (x == ELF_ARCH)
 156 # endif
 157 # ifdef ELF_CLASS
 158 #  define ELFCLASSM ELF_CLASS
 159 # endif
 160 #endif
 161 #ifndef MATCH_MACHINE
 162 # warning "You really should add a MATCH_MACHINE() macro for your architecture"
 163 #endif
 164
 165 #if UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_LITTLE
 166 #define ELFDATAM        ELFDATA2LSB
 167 #elif UCLIBC_ENDIAN_HOST == UCLIBC_ENDIAN_BIG
 168 #define ELFDATAM        ELFDATA2MSB
 169 #endif
 170
 171 #define TRUSTED_LDSO    UCLIBC_RUNTIME_PREFIX "lib/" UCLIBC_LDSO
 172
 173 struct library {
 174         char *name;
 175         int resolved;
 176         char *path;
 177         struct library *next;
 178 };
 179 static struct library *lib_list = NULL;
 180 static char not_found[] = "not found";
 181 static char *interp_name = NULL;
 182 static char *interp_dir = NULL;
 183 static int byteswap;
 184 static int interpreter_already_found = 0;
 185
 186 static __inline__ uint32_t byteswap32_to_host(uint32_t value)
 187 {
 188         if (byteswap) {
 189                 return (bswap_32(value));
 190         } else {
 191                 return (value);
 192         }
 193 }
 194 static __inline__ uint64_t byteswap64_to_host(uint64_t value)
 195 {
 196         if (byteswap) {
 197                 return (bswap_64(value));
 198         } else {
 199                 return (value);
 200         }
 201 }
 202
 203 #if __WORDSIZE == 64
 204 # define byteswap_to_host(x) byteswap64_to_host(x)
 205 #else
 206 # define byteswap_to_host(x) byteswap32_to_host(x)
 207 #endif
 208
 209 static ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr)
 210 {
 211         int j;
 212         ElfW(Shdr) *shdr;
 213         shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr);
 214         for (j = ehdr->e_shnum; --j >= 0; ++shdr) {
 215                 if (key == byteswap32_to_host(shdr->sh_type)) {
 216                         return shdr;
 217                 }
 218         }
 219         return NULL;
 220 }
 221
 222 static ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr)
 223 {
 224         int j;
 225         ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr);
 226         for (j = ehdr->e_phnum; --j >= 0; ++phdr) {
 227                 if (type == byteswap32_to_host(phdr->p_type)) {
 228                         return phdr;
 229                 }
 230         }
 231         return NULL;
 232 }
 233
 234 /* Returns value if return_val==1, ptr otherwise */
 235 static void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp,
 236                        ElfW(Ehdr) *ehdr, int return_val)
 237 {
 238         ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr);
 239         unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset);
 240         for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) {
 241                 if (key == byteswap_to_host(dynp->d_tag)) {
 242                         if (return_val == 1)
 243                                 return (void *)byteswap_to_host(dynp->d_un.d_val);
 244                         else
 245                                 return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr);
 246                 }
 247         }
 248         return NULL;
 249 }
 250
 251 static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic)
 252 {
 253         ElfW(Dyn) *dyns;
 254
 255         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 256                 if (DT_RPATH == byteswap_to_host(dyns->d_tag)) {
 257                         char *strtab;
 258                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 259                         return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 260                 }
 261         }
 262         return NULL;
 263 }
 264
 265 static int check_elf_header(ElfW(Ehdr) *const ehdr)
 266 {
 267         if (!ehdr || *(uint32_t*)ehdr != ELFMAG_U32
 268          /* Use __WORDSIZE, not ELFCLASSM which depends on the host */
 269          || ehdr->e_ident[EI_CLASS] != (__WORDSIZE >> 5)
 270          || ehdr->e_ident[EI_VERSION] != EV_CURRENT
 271         ) {
 272                 return 1;
 273         }
 274
 275         /* Check if the target endianness matches the host's endianness */
 276         byteswap = !(ehdr->e_ident[5] == ELFDATAM);
 277
 278         /* Be very lazy, and only byteswap the stuff we use */
 279         if (byteswap) {
 280                 ehdr->e_type = bswap_16(ehdr->e_type);
 281                 ehdr->e_phoff = byteswap_to_host(ehdr->e_phoff);
 282                 ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff);
 283                 ehdr->e_phnum = bswap_16(ehdr->e_phnum);
 284                 ehdr->e_shnum = bswap_16(ehdr->e_shnum);
 285         }
 286
 287         return 0;
 288 }
 289
 290 #ifdef __LDSO_CACHE_SUPPORT__
 291 static caddr_t cache_addr = NULL;
 292 static size_t cache_size = 0;
 293
 294 static int map_cache(void)
 295 {
 296         int fd;
 297         struct stat st;
 298         header_t *header;
 299         libentry_t *libent;
 300         int i, strtabsize;
 301
 302         if (cache_addr == (caddr_t) - 1)
 303                 return -1;
 304         else if (cache_addr != NULL)
 305                 return 0;
 306
 307         if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY)) < 0) {
 308                 fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE);
 309                 cache_addr = (caddr_t) - 1;     /* so we won't try again */
 310                 return -1;
 311         }
 312
 313         cache_size = st.st_size;
 314         cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0);
 315         close(fd);
 316         if (cache_addr == MAP_FAILED) {
 317                 fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE);
 318                 return -1;
 319         }
 320
 321         header = (header_t *) cache_addr;
 322
 323         if (cache_size < sizeof(header_t)
 324             || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
 325             || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
 326             || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t))
 327             || cache_addr[cache_size - 1] != '\0')
 328         {
 329                 fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 330                 goto fail;
 331         }
 332
 333         strtabsize = cache_size - sizeof(header_t) - header->nlibs * sizeof(libentry_t);
 334         libent = (libentry_t *) & header[1];
 335
 336         for (i = 0; i < header->nlibs; i++) {
 337                 if (libent[i].sooffset >= strtabsize || libent[i].liboffset >= strtabsize) {
 338                         fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE);
 339                         goto fail;
 340                 }
 341         }
 342
 343         return 0;
 344
 345 fail:
 346         munmap(cache_addr, cache_size);
 347         cache_addr = (caddr_t) - 1;
 348         return -1;
 349 }
 350
 351 static int unmap_cache(void)
 352 {
 353         if (cache_addr == NULL || cache_addr == (caddr_t) - 1)
 354                 return -1;
 355
 356 #if 1
 357         munmap(cache_addr, cache_size);
 358         cache_addr = NULL;
 359 #endif
 360
 361         return 0;
 362 }
 363 #else
 364 static __inline__ void map_cache(void)
 365 {
 366 }
 367 static __inline__ void unmap_cache(void)
 368 {
 369 }
 370 #endif
 371
 372 /* This function's behavior must exactly match that
 373  * in uClibc/ldso/ldso/dl-elf.c */
 374 static void search_for_named_library(char *name, char *result,
 375                                      const char *path_list)
 376 {
 377         int i, count = 1;
 378         char *path, *path_n;
 379         struct stat filestat;
 380
 381         /* We need a writable copy of this string */
 382         path = strdup(path_list);
 383         if (!path) {
 384                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 385                 exit(EXIT_FAILURE);
 386         }
 387         /* Eliminate all double //s */
 388         path_n = path;
 389         while ((path_n = strstr(path_n, "//"))) {
 390                 i = strlen(path_n);
 391                 memmove(path_n, path_n + 1, i - 1);
 392                 *(path_n + i - 1) = '\0';
 393         }
 394
 395         /* Replace colons with zeros in path_list and count them */
 396         for (i = strlen(path); i > 0; i--) {
 397                 if (path[i] == ':') {
 398                         path[i] = 0;
 399                         count++;
 400                 }
 401         }
 402         path_n = path;
 403         for (i = 0; i < count; i++) {
 404                 strcpy(result, path_n);
 405                 strcat(result, "/");
 406                 strcat(result, name);
 407                 if (stat(result, &filestat) == 0 && filestat.st_mode & S_IRUSR) {
 408                         free(path);
 409                         return;
 410                 }
 411                 path_n += (strlen(path_n) + 1);
 412         }
 413         free(path);
 414         *result = '\0';
 415 }
 416
 417 static void locate_library_file(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic,
 418                                 int is_suid, struct library *lib)
 419 {
 420         char *buf;
 421         char *path;
 422         struct stat filestat;
 423
 424         /* If this is a fully resolved name, our job is easy */
 425         if (stat(lib->name, &filestat) == 0) {
 426                 lib->path = strdup(lib->name);
 427                 return;
 428         }
 429
 430         /* We need some elbow room here.  Make some room... */
 431         buf = malloc(1024);
 432         if (!buf) {
 433                 fprintf(stderr, "%s: Out of memory!\n", __func__);
 434                 exit(EXIT_FAILURE);
 435         }
 436
 437         /* This function must match the behavior of _dl_load_shared_library
 438          * in readelflib1.c or things won't work out as expected... */
 439
 440         /* The ABI specifies that RPATH is searched first, so do that now.  */
 441         path = elf_find_rpath(ehdr, dynamic);
 442         if (path) {
 443                 search_for_named_library(lib->name, buf, path);
 444                 if (*buf != '\0') {
 445                         lib->path = buf;
 446                         return;
 447                 }
 448         }
 449
 450         /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed.
 451          * Since this app doesn't actually run an executable I will skip
 452          * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */
 453         if (is_suid == 1)
 454                 path = NULL;
 455         else
 456                 path = getenv("LD_LIBRARY_PATH");
 457         if (path) {
 458                 search_for_named_library(lib->name, buf, path);
 459                 if (*buf != '\0') {
 460                         lib->path = buf;
 461                         return;
 462                 }
 463         }
 464 #ifdef __LDSO_CACHE_SUPPORT__
 465         if (cache_addr != NULL && cache_addr != (caddr_t) - 1) {
 466                 int i;
 467                 header_t *header = (header_t *) cache_addr;
 468                 libentry_t *libent = (libentry_t *) & header[1];
 469                 char *strs = (char *)&libent[header->nlibs];
 470
 471                 for (i = 0; i < header->nlibs; i++) {
 472                         if ((libent[i].flags == LIB_ELF ||
 473                              libent[i].flags == LIB_ELF_LIBC0 ||
 474                              libent[i].flags == LIB_ELF_LIBC5) &&
 475                             strcmp(lib->name, strs + libent[i].sooffset) == 0)
 476                         {
 477                                 lib->path = strdup(strs + libent[i].liboffset);
 478                                 return;
 479                         }
 480                 }
 481         }
 482 #endif
 483
 484         /* Next look for libraries wherever the shared library
 485          * loader was installed -- this is usually where we
 486          * should find things... */
 487         if (interp_dir) {
 488                 search_for_named_library(lib->name, buf, interp_dir);
 489                 if (*buf != '\0') {
 490                         lib->path = buf;
 491                         return;
 492                 }
 493         }
 494
 495         /* Lastly, search the standard list of paths for the library.
 496            This list must exactly match the list in uClibc/ldso/ldso/dl-elf.c */
 497         path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib"
 498 #ifndef __LDSO_CACHE_SUPPORT__
 499             ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
 500 #endif
 501             ;
 502         search_for_named_library(lib->name, buf, path);
 503         if (*buf != '\0') {
 504                 lib->path = buf;
 505         } else {
 506                 free(buf);
 507                 lib->path = not_found;
 508         }
 509 }
 510
 511 static int add_library(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid, char *s)
 512 {
 513         char *tmp, *tmp1, *tmp2;
 514         struct library *cur, *newlib = lib_list;
 515
 516         if (!s || !strlen(s))
 517                 return 1;
 518
 519         tmp = s;
 520         while (*tmp) {
 521                 if (*tmp == '/')
 522                         s = tmp + 1;
 523                 tmp++;
 524         }
 525
 526         /* We add ldso elsewhere */
 527         if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) {
 528                 int len = strlen(interp_dir);
 529                 if (strcmp(s, interp_name + 1 + len) == 0)
 530                         return 1;
 531         }
 532
 533         for (cur = lib_list; cur; cur = cur->next) {
 534                 /* Check if this library is already in the list */
 535                 tmp1 = tmp2 = cur->name;
 536                 if (!cur->name)
 537                         continue;
 538                 while (*tmp1) {
 539                         if (*tmp1 == '/')
 540                                 tmp2 = tmp1 + 1;
 541                         tmp1++;
 542                 }
 543                 if (strcmp(tmp2, s) == 0) {
 544                         /*printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); */
 545                         return 0;
 546                 }
 547         }
 548
 549         /* Ok, this lib needs to be added to the list */
 550         newlib = malloc(sizeof(struct library));
 551         if (!newlib)
 552                 return 1;
 553         newlib->name = malloc(strlen(s) + 1);
 554         strcpy(newlib->name, s);
 555         newlib->resolved = 0;
 556         newlib->path = NULL;
 557         newlib->next = NULL;
 558
 559         /* Now try and locate where this library might be living... */
 560         locate_library_file(ehdr, dynamic, is_setuid, newlib);
 561
 562         /*printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 563         if (!lib_list) {
 564                 lib_list = newlib;
 565         } else {
 566                 for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 567                 cur->next = newlib;
 568         }
 569         return 0;
 570 }
 571
 572 static void find_needed_libraries(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid)
 573 {
 574         ElfW(Dyn) *dyns;
 575
 576         for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) {
 577                 if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) {
 578                         char *strtab;
 579                         strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);
 580                         add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val));
 581                 }
 582         }
 583 }
 584
 585 #ifdef __LDSO_LDD_SUPPORT__
 586 static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr)
 587 {
 588         ElfW(Phdr) *phdr;
 589
 590         if (interpreter_already_found == 1)
 591                 return NULL;
 592         phdr = elf_find_phdr_type(PT_INTERP, ehdr);
 593         if (phdr) {
 594                 struct library *cur, *newlib = NULL;
 595                 char *s = (char *)ehdr + byteswap_to_host(phdr->p_offset);
 596
 597                 char *tmp, *tmp1;
 598                 interp_name = strdup(s);
 599                 interp_dir = strdup(s);
 600                 tmp = strrchr(interp_dir, '/');
 601                 if (tmp)
 602                         *tmp = '\0';
 603                 else {
 604                         free(interp_dir);
 605                         interp_dir = interp_name;
 606                 }
 607                 tmp1 = tmp = s;
 608                 while (*tmp) {
 609                         if (*tmp == '/')
 610                                 tmp1 = tmp + 1;
 611                         tmp++;
 612                 }
 613                 for (cur = lib_list; cur; cur = cur->next) {
 614                         /* Check if this library is already in the list */
 615                         if (!tmp1 || !cur->name)
 616                                 return NULL;
 617                         if (strcmp(cur->name, tmp1) == 0) {
 618                                 /*printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); */
 619                                 newlib = cur;
 620                                 free(newlib->name);
 621                                 if (newlib->path != not_found) {
 622                                         free(newlib->path);
 623                                 }
 624                                 newlib->name = NULL;
 625                                 newlib->path = NULL;
 626                                 break;
 627                         }
 628                 }
 629                 if (newlib == NULL)
 630                         newlib = malloc(sizeof(struct library));
 631                 if (!newlib)
 632                         return NULL;
 633                 newlib->name = malloc(strlen(s) + 1);
 634                 strcpy(newlib->name, s);
 635                 newlib->path = strdup(newlib->name);
 636                 newlib->resolved = 1;
 637                 newlib->next = NULL;
 638
 639 #if 0
 640                 /*printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); */
 641                 if (!lib_list) {
 642                         lib_list = newlib;
 643                 } else {
 644                         for (cur = lib_list; cur->next; cur = cur->next) ;      /* nothing */
 645                         cur->next = newlib;
 646                 }
 647 #endif
 648                 interpreter_already_found = 1;
 649                 return newlib;
 650         }
 651         return NULL;
 652 }
 653 #endif /* __LDSO_LDD_SUPPORT__ */
 654
 655 /* map the .so, and locate interesting pieces */
 656 /*
 657 #warning "There may be two warnings here about vfork() clobbering, ignore them"
 658 */
 659 static int find_dependencies(char *filename)
 660 {
 661         int is_suid = 0;
 662         FILE *thefile;
 663         struct stat statbuf;
 664         ElfW(Ehdr) *ehdr = NULL;
 665         ElfW(Shdr) *dynsec = NULL;
 666         ElfW(Dyn) *dynamic = NULL;
 667 #ifdef __LDSO_LDD_SUPPORT__
 668         struct library *interp;
 669 #endif
 670
 671         if (filename == not_found)
 672                 return 0;
 673
 674         if (!filename) {
 675                 fprintf(stderr, "No filename specified.\n");
 676                 return -1;
 677         }
 678         if (!(thefile = fopen(filename, "r"))) {
 679                 perror(filename);
 680                 return -1;
 681         }
 682         if (fstat(fileno(thefile), &statbuf) < 0) {
 683                 perror(filename);
 684                 fclose(thefile);
 685                 return -1;
 686         }
 687
 688         if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr)))
 689                 goto foo;
 690
 691         if (!S_ISREG(statbuf.st_mode))
 692                 goto foo;
 693
 694         /* mmap the file to make reading stuff from it effortless */
 695         ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0);
 696         if (ehdr == MAP_FAILED) {
 697                 fclose(thefile);
 698                 fprintf(stderr, "mmap(%s) failed: %s\n", filename, strerror(errno));
 699                 return -1;
 700         }
 701
 702 foo:
 703         fclose(thefile);
 704
 705         /* Check if this looks like a legit ELF file */
 706         if (check_elf_header(ehdr)) {
 707                 fprintf(stderr, "%s: not an ELF file.\n", filename);
 708                 return -1;
 709         }
 710         /* Check if this is the right kind of ELF file */
 711         if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
 712                 fprintf(stderr, "%s: not a dynamic executable\n", filename);
 713                 return -1;
 714         }
 715         if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) {
 716                 if (statbuf.st_mode & S_ISUID)
 717                         is_suid = 1;
 718                 if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
 719                         is_suid = 1;
 720                 /* FIXME */
 721                 if (is_suid)
 722                         fprintf(stderr, "%s: is setuid\n", filename);
 723         }
 724
 725         interpreter_already_found = 0;
 726 #ifdef __LDSO_LDD_SUPPORT__
 727         interp = find_elf_interpreter(ehdr);
 728
 729         if (interp
 730             && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN)
 731             && ehdr->e_ident[EI_CLASS] == ELFCLASSM
 732             && ehdr->e_ident[EI_DATA] == ELFDATAM
 733             && ehdr->e_ident[EI_VERSION] == EV_CURRENT
 734             && MATCH_MACHINE(ehdr->e_machine))
 735         {
 736                 struct stat st;
 737                 if (stat(interp->path, &st) == 0 && S_ISREG(st.st_mode)) {
 738                         pid_t pid;
 739                         int status;
 740                         static const char *const environment[] = {
 741                                 "PATH=/usr/bin:/bin:/usr/sbin:/sbin",
 742                                 "SHELL=/bin/sh",
 743                                 "LD_TRACE_LOADED_OBJECTS=1",
 744                                 NULL
 745                         };
 746 # ifdef __LDSO_STANDALONE_SUPPORT__
 747                         char * lib_path = getenv("LD_LIBRARY_PATH");
 748
 749                         /* The 'extended' environment inclusing the LD_LIBRARY_PATH */
 750                         static char *ext_environment[ARRAY_SIZE(environment) + 1];
 751                         char **envp = (char **) environment;
 752
 753                         if (lib_path) {
 754                                 /*
 755                                  * If the LD_LIBRARY_PATH is set, it needs to include it
 756                                  * into the environment for the new process to be spawned
 757                                  */
 758                                 char ** eenvp = (char **) ext_environment;
 759
 760                                 /* Copy the N-1 environment's entries */
 761                                 while (*envp)
 762                                         *eenvp++=*envp++;
 763
 764                                 /* Make room for LD_LIBRARY_PATH */
 765                                 *eenvp = (char *) malloc(sizeof("LD_LIBRARY_PATH=")
 766                                                                           + strlen(lib_path));
 767                                 strcpy(*eenvp, "LD_LIBRARY_PATH=");
 768                                 strcat(*eenvp, lib_path);
 769                                 lib_path = *eenvp;
 770                                 /* ext_environment[size] is already NULL */
 771
 772                                 /* Use the extended environment */
 773                                 envp = ext_environment;
 774                         }
 775                         if ((pid = vfork()) == 0) {
 776                                 /*
 777                                  * Force to use the standard dynamic linker in stand-alone mode.
 778                                  * It will fails at runtime if support is not actually available
 779                                  */
 780                                 execle(TRUSTED_LDSO, TRUSTED_LDSO, filename, NULL, envp);
 781                                 _exit(0xdead);
 782                         }
 783 # else
 784                         if ((pid = vfork()) == 0) {
 785                                 /* Cool, it looks like we should be able to actually
 786                                  * run this puppy.  Do so now... */
 787                                 execle(filename, filename, NULL, environment);
 788                                 _exit(0xdead);
 789                         }
 790 # endif
 791                         /* Wait till it returns */
 792                         waitpid(pid, &status, 0);
 793
 794 # ifdef __LDSO_STANDALONE_SUPPORT__
 795                         /* Do not leak */
 796                         free(lib_path);
 797 # endif
 798
 799                         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 800                                 return 1;
 801                         }
 802
 803                         /* If the exec failed, we fall through to trying to find
 804                          * all the needed libraries ourselves by rummaging about
 805                          * in the ELF headers... */
 806                 }
 807         }
 808 #endif
 809
 810         dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
 811         if (dynsec) {
 812                 dynamic = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr);
 813                 find_needed_libraries(ehdr, dynamic, is_suid);
 814         }
 815
 816         return 0;
 817 }
 818
 819 int main(int argc, char **argv)
 820 {
 821         int multi = 0;
 822         int got_em_all = 1;
 823         char *filename = NULL;
 824         struct library *cur;
 825
 826         if (argc < 2) {
 827                 fprintf(stderr, "ldd: missing file arguments\n"
 828                                 "Try `ldd --help' for more information.\n");
 829                 exit(EXIT_FAILURE);
 830         }
 831         if (argc > 2)
 832                 multi++;
 833
 834         while (--argc > 0) {
 835                 ++argv;
 836
 837                 if (strcmp(*argv, "--") == 0) {
 838                         /* Ignore "--" */
 839                         continue;
 840                 }
 841
 842                 if (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0) {
 843                         fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"
 844                                         "\t--help\t\tprint this help and exit\n");
 845                         exit(EXIT_SUCCESS);
 846                 }
 847
 848                 filename = *argv;
 849                 if (!filename) {
 850                         fprintf(stderr, "No filename specified.\n");
 851                         exit(EXIT_FAILURE);
 852                 }
 853
 854                 if (multi) {
 855                         printf("%s:\n", *argv);
 856                 }
 857
 858                 map_cache();
 859
 860                 if (find_dependencies(filename) != 0)
 861                         continue;
 862
 863                 while (got_em_all) {
 864                         got_em_all = 0;
 865                         /* Keep walking the list till everybody is resolved */
 866                         for (cur = lib_list; cur; cur = cur->next) {
 867                                 if (cur->resolved == 0 && cur->path) {
 868                                         got_em_all = 1;
 869                                         printf("checking sub-depends for '%s'\n", cur->path);
 870                                         find_dependencies(cur->path);
 871                                         cur->resolved = 1;
 872                                 }
 873                         }
 874                 }
 875
 876                 unmap_cache();
 877
 878                 /* Print the list */
 879                 got_em_all = 0;
 880                 for (cur = lib_list; cur; cur = cur->next) {
 881                         got_em_all = 1;
 882                         printf("\t%s => %s (0x00000000)\n", cur->name, cur->path);
 883                 }
 884                 if (interp_name && interpreter_already_found == 1)
 885                         printf("\t%s => %s (0x00000000)\n", interp_name, interp_name);
 886                 else
 887                         printf("\tnot a dynamic executable\n");
 888
 889                 for (cur = lib_list; cur; cur = cur->next) {
 890                         free(cur->name);
 891                         cur->name = NULL;
 892                         if (cur->path && cur->path != not_found) {
 893                                 free(cur->path);
 894                                 cur->path = NULL;
 895                         }
 896                 }
 897                 lib_list = NULL;
 898         }
 899
 900         return 0;
 901 }