elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2002, 2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 /* This file defines some things that for the dynamic linker are defined in
  21    rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking.  */
  22
  23 #include <errno.h>
  24 #include <libintl.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <ldsodefs.h>
  28 #include <dl-machine.h>
  29 #include <bits/libc-lock.h>
  30 #include <dl-cache.h>
  31 #include <dl-librecon.h>
  32 #include <unsecvars.h>
  33 #include <hp-timing.h>
  34
  35 extern char *__progname;
  36 char **_dl_argv = &__progname;  /* This is checked for some error messages.  */
  37
  38 /* Name of the architecture.  */
  39 const char *_dl_platform;
  40 size_t _dl_platformlen;
  41
  42 int _dl_debug_mask;
  43 int _dl_lazy;
  44 int _dl_dynamic_weak;
  45
  46 /* If nonzero print warnings about problematic situations.  */
  47 int _dl_verbose;
  48
  49 /* We never do profiling.  */
  50 const char *_dl_profile;
  51
  52 /* Names of shared object for which the RUNPATHs and RPATHs should be
  53    ignored.  */
  54 const char *_dl_inhibit_rpath;
  55
  56 /* The map for the object we will profile.  */
  57 struct link_map *_dl_profile_map;
  58
  59 /* This is the address of the last stack address ever used.  */
  60 void *__libc_stack_end;
  61
  62 /* Path where the binary is found.  */
  63 const char *_dl_origin_path;
  64
  65 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  66 int _dl_bind_not;
  67
  68 /* Initially empty list of loaded objects.  */
  69 struct link_map *_dl_loaded;
  70 /* Number of object in the _dl_loaded list.  */
  71 unsigned int _dl_nloaded;
  72
  73 /* Fake scope.  In dynamically linked binaries this is the scope of the
  74    main application but here we don't have something like this.  So
  75    create a fake scope containing nothing.  */
  76 struct r_scope_elem _dl_initial_searchlist;
  77 /* Variable which can be used in lookup to process the global scope.  */
  78 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
  79 /* This is a global pointer to this structure which is public.  It is
  80    used by dlopen/dlclose to add and remove objects from what is regarded
  81    to be the global scope.  */
  82 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
  83
  84 /* Nonzero during startup.  */
  85 int _dl_starting_up = 1;
  86
  87 /* Get architecture specific initializer.  */
  88 #include <dl-procinfo.c>
  89
  90 /* We expect less than a second for relocation.  */
  91 #ifdef HP_SMALL_TIMING_AVAIL
  92 # undef HP_TIMING_AVAIL
  93 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
  94 #endif
  95
  96 /* Initial value of the CPU clock.  */
  97 #ifndef HP_TIMING_NONAVAIL
  98 hp_timing_t _dl_cpuclock_offset;
  99 #endif
 100
 101 #ifdef USE_TLS
 102 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
 103 #endif
 104
 105 /* This is zero at program start to signal that the global scope map is
 106    allocated by rtld.  Later it keeps the size of the map.  It might be
 107    reset if in _dl_close if the last global object is removed.  */
 108 size_t _dl_global_scope_alloc;
 109
 110 size_t _dl_pagesize;
 111
 112 unsigned int _dl_osversion;
 113
 114 /* All known directories in sorted order.  */
 115 struct r_search_path_elem *_dl_all_dirs;
 116
 117 /* All directories after startup.  */
 118 struct r_search_path_elem *_dl_init_all_dirs;
 119
 120 /* The object to be initialized first.  */
 121 struct link_map *_dl_initfirst;
 122
 123 /* Descriptor to write debug messages to.  */
 124 int _dl_debug_fd = STDERR_FILENO;
 125
 126 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
 127
 128 ElfW(Phdr) *_dl_phdr;
 129 size_t _dl_phnum;
 130 unsigned long int _dl_hwcap __attribute__ ((nocommon));
 131
 132 #ifdef NEED_DL_SYSINFO
 133 /* Needed for improved syscall handling on at least x86/Linux.  */
 134 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 135 /* Address of the ELF headers in the vsyscall page.  */
 136 const ElfW(Ehdr) *_dl_sysinfo_dso;
 137 #endif
 138
 139 /* During the program run we must not modify the global data of
 140    loaded shared object simultanously in two threads.  Therefore we
 141    protect `_dl_open' and `_dl_close' in dl-close.c.
 142
 143    This must be a recursive lock since the initializer function of
 144    the loaded object might as well require a call to this function.
 145    At this time it is not anymore a problem to modify the tables.  */
 146 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 147
 148
 149 #ifdef HAVE_AUX_VECTOR
 150 int _dl_clktck;
 151
 152 void
 153 internal_function
 154 _dl_aux_init (ElfW(auxv_t) *av)
 155 {
 156   int seen = 0;
 157   uid_t uid = 0;
 158   gid_t gid = 0;
 159
 160   for (; av->a_type != AT_NULL; ++av)
 161     switch (av->a_type)
 162       {
 163       case AT_PAGESZ:
 164         GL(dl_pagesize) = av->a_un.a_val;
 165         break;
 166       case AT_CLKTCK:
 167         GL(dl_clktck) = av->a_un.a_val;
 168         break;
 169       case AT_PHDR:
 170         GL(dl_phdr) = av->a_un.a_ptr;
 171         break;
 172       case AT_PHNUM:
 173         GL(dl_phnum) = av->a_un.a_val;
 174         break;
 175       case AT_HWCAP:
 176         GL(dl_hwcap) = av->a_un.a_val;
 177         break;
 178 #ifdef NEED_DL_SYSINFO
 179       case AT_SYSINFO:
 180         GL(dl_sysinfo) = av->a_un.a_val;
 181         break;
 182 #endif
 183       case AT_UID:
 184         uid ^= av->a_un.a_val;
 185         seen |= 1;
 186         break;
 187       case AT_EUID:
 188         uid ^= av->a_un.a_val;
 189         seen |= 2;
 190         break;
 191       case AT_GID:
 192         gid ^= av->a_un.a_val;
 193         seen |= 4;
 194         break;
 195       case AT_EGID:
 196         gid ^= av->a_un.a_val;
 197         seen |= 8;
 198         break;
 199       case AT_SECURE:
 200         seen = -1;
 201         __libc_enable_secure = av->a_un.a_val;
 202         __libc_enable_secure_decided = 1;
 203         break;
 204       }
 205   if (seen == 0xf)
 206     {
 207       __libc_enable_secure = uid != 0 || gid != 0;
 208       __libc_enable_secure_decided = 1;
 209     }
 210 }
 211 #endif
 212
 213
 214 void
 215 internal_function
 216 _dl_non_dynamic_init (void)
 217 {
 218   if (HP_TIMING_AVAIL)
 219     HP_TIMING_NOW (_dl_cpuclock_offset);
 220
 221   if (!_dl_pagesize)
 222     _dl_pagesize = __getpagesize ();
 223
 224   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 225
 226   /* Initialize the data structures for the search paths for shared
 227      objects.  */
 228   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 229
 230   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 231
 232   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 233
 234   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 235
 236   if (__libc_enable_secure)
 237     {
 238       static const char *unsecure_envvars[] =
 239       {
 240         UNSECURE_ENVVARS,
 241 #ifdef EXTRA_UNSECURE_ENVVARS
 242         EXTRA_UNSECURE_ENVVARS
 243 #endif
 244       };
 245       size_t cnt;
 246
 247       for (cnt = 0;
 248            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 249            ++cnt)
 250         unsetenv (unsecure_envvars[cnt]);
 251
 252       if (__access ("/etc/suid-debug", F_OK) != 0)
 253         unsetenv ("MALLOC_CHECK_");
 254     }
 255
 256 #ifdef DL_PLATFORM_INIT
 257   DL_PLATFORM_INIT;
 258 #endif
 259
 260 #ifdef DL_OSVERSION_INIT
 261   DL_OSVERSION_INIT;
 262 #endif
 263
 264   /* Now determine the length of the platform string.  */
 265   if (_dl_platform != NULL)
 266     _dl_platformlen = strlen (_dl_platform);
 267 }
 268
 269
 270 const struct r_strlenpair *
 271 internal_function
 272 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 273                       size_t *max_capstrlen)
 274 {
 275   static struct r_strlenpair result;
 276   static char buf[1];
 277
 278   result.str = buf;     /* Does not really matter.  */
 279   result.len = 0;
 280
 281   *sz = 1;
 282   return &result;
 283 }
 284
 285
 286 #ifdef DL_SYSINFO_IMPLEMENTATION
 287 DL_SYSINFO_IMPLEMENTATION
 288 #endif