elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2002, 2003, 2004 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 ElfW(Addr) _dl_use_load_bias = -2;
  45 int _dl_dynamic_weak;
  46
  47 /* If nonzero print warnings about problematic situations.  */
  48 int _dl_verbose;
  49
  50 /* We never do profiling.  */
  51 const char *_dl_profile;
  52 const char *_dl_profile_output;
  53
  54 /* Names of shared object for which the RUNPATHs and RPATHs should be
  55    ignored.  */
  56 const char *_dl_inhibit_rpath;
  57
  58 /* The map for the object we will profile.  */
  59 struct link_map *_dl_profile_map;
  60
  61 /* This is the address of the last stack address ever used.  */
  62 void *__libc_stack_end;
  63
  64 /* Path where the binary is found.  */
  65 const char *_dl_origin_path;
  66
  67 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  68 int _dl_bind_not;
  69
  70 /* Initially empty list of loaded objects.  */
  71 struct link_map *_dl_loaded;
  72 /* Number of object in the _dl_loaded list.  */
  73 unsigned int _dl_nloaded;
  74
  75 /* Incremented whenever something may have been added to dl_loaded. */
  76 unsigned long long _dl_load_adds;
  77
  78 /* Fake scope.  In dynamically linked binaries this is the scope of the
  79    main application but here we don't have something like this.  So
  80    create a fake scope containing nothing.  */
  81 struct r_scope_elem _dl_initial_searchlist;
  82 /* Variable which can be used in lookup to process the global scope.  */
  83 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
  84 /* This is a global pointer to this structure which is public.  It is
  85    used by dlopen/dlclose to add and remove objects from what is regarded
  86    to be the global scope.  */
  87 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
  88
  89 /* Nonzero during startup.  */
  90 int _dl_starting_up = 1;
  91
  92 /* Get architecture specific initializer.  */
  93 #include <dl-procinfo.c>
  94
  95 /* We expect less than a second for relocation.  */
  96 #ifdef HP_SMALL_TIMING_AVAIL
  97 # undef HP_TIMING_AVAIL
  98 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
  99 #endif
 100
 101 /* Initial value of the CPU clock.  */
 102 #ifndef HP_TIMING_NONAVAIL
 103 hp_timing_t _dl_cpuclock_offset;
 104 #endif
 105
 106 #ifdef USE_TLS
 107 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
 108 #endif
 109
 110 /* This is zero at program start to signal that the global scope map is
 111    allocated by rtld.  Later it keeps the size of the map.  It might be
 112    reset if in _dl_close if the last global object is removed.  */
 113 size_t _dl_global_scope_alloc;
 114
 115 size_t _dl_pagesize;
 116
 117 unsigned int _dl_osversion;
 118
 119 /* All known directories in sorted order.  */
 120 struct r_search_path_elem *_dl_all_dirs;
 121
 122 /* All directories after startup.  */
 123 struct r_search_path_elem *_dl_init_all_dirs;
 124
 125 /* The object to be initialized first.  */
 126 struct link_map *_dl_initfirst;
 127
 128 /* Descriptor to write debug messages to.  */
 129 int _dl_debug_fd = STDERR_FILENO;
 130
 131 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
 132
 133 ElfW(Phdr) *_dl_phdr;
 134 size_t _dl_phnum;
 135 unsigned long int _dl_hwcap __attribute__ ((nocommon));
 136
 137 /* Prevailing state of the stack, PF_X indicating it's executable.  */
 138 ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X;
 139
 140 /* If loading a shared object requires that we make the stack executable
 141    when it was not, we do it by calling this function.
 142    It returns an errno code or zero on success.  */
 143 int (*_dl_make_stack_executable_hook) (void **) internal_function
 144   = _dl_make_stack_executable;
 145
 146
 147 #ifdef NEED_DL_SYSINFO
 148 /* Needed for improved syscall handling on at least x86/Linux.  */
 149 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 150 /* Address of the ELF headers in the vsyscall page.  */
 151 const ElfW(Ehdr) *_dl_sysinfo_dso;
 152 #endif
 153
 154 /* During the program run we must not modify the global data of
 155    loaded shared object simultanously in two threads.  Therefore we
 156    protect `_dl_open' and `_dl_close' in dl-close.c.
 157
 158    This must be a recursive lock since the initializer function of
 159    the loaded object might as well require a call to this function.
 160    At this time it is not anymore a problem to modify the tables.  */
 161 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 162
 163
 164 #ifdef HAVE_AUX_VECTOR
 165 int _dl_clktck;
 166
 167 void
 168 internal_function
 169 _dl_aux_init (ElfW(auxv_t) *av)
 170 {
 171   int seen = 0;
 172   uid_t uid = 0;
 173   gid_t gid = 0;
 174
 175   for (; av->a_type != AT_NULL; ++av)
 176     switch (av->a_type)
 177       {
 178       case AT_PAGESZ:
 179         GLRO(dl_pagesize) = av->a_un.a_val;
 180         break;
 181       case AT_CLKTCK:
 182         GLRO(dl_clktck) = av->a_un.a_val;
 183         break;
 184       case AT_PHDR:
 185         GL(dl_phdr) = av->a_un.a_ptr;
 186         break;
 187       case AT_PHNUM:
 188         GL(dl_phnum) = av->a_un.a_val;
 189         break;
 190       case AT_HWCAP:
 191         GLRO(dl_hwcap) = av->a_un.a_val;
 192         break;
 193 #ifdef NEED_DL_SYSINFO
 194       case AT_SYSINFO:
 195         GL(dl_sysinfo) = av->a_un.a_val;
 196         break;
 197 #endif
 198       case AT_UID:
 199         uid ^= av->a_un.a_val;
 200         seen |= 1;
 201         break;
 202       case AT_EUID:
 203         uid ^= av->a_un.a_val;
 204         seen |= 2;
 205         break;
 206       case AT_GID:
 207         gid ^= av->a_un.a_val;
 208         seen |= 4;
 209         break;
 210       case AT_EGID:
 211         gid ^= av->a_un.a_val;
 212         seen |= 8;
 213         break;
 214       case AT_SECURE:
 215         seen = -1;
 216         __libc_enable_secure = av->a_un.a_val;
 217         __libc_enable_secure_decided = 1;
 218         break;
 219       }
 220   if (seen == 0xf)
 221     {
 222       __libc_enable_secure = uid != 0 || gid != 0;
 223       __libc_enable_secure_decided = 1;
 224     }
 225 }
 226 #endif
 227
 228
 229 void
 230 internal_function
 231 _dl_non_dynamic_init (void)
 232 {
 233   if (HP_TIMING_AVAIL)
 234     HP_TIMING_NOW (_dl_cpuclock_offset);
 235
 236   if (!_dl_pagesize)
 237     _dl_pagesize = __getpagesize ();
 238
 239   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 240
 241   /* Initialize the data structures for the search paths for shared
 242      objects.  */
 243   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 244
 245   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 246
 247   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 248
 249   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 250
 251   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 252   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 253     _dl_profile_output
 254       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 255
 256   if (__libc_enable_secure)
 257     {
 258       static const char *unsecure_envvars[] =
 259       {
 260         UNSECURE_ENVVARS,
 261 #ifdef EXTRA_UNSECURE_ENVVARS
 262         EXTRA_UNSECURE_ENVVARS
 263 #endif
 264       };
 265       size_t cnt;
 266
 267       for (cnt = 0;
 268            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 269            ++cnt)
 270         unsetenv (unsecure_envvars[cnt]);
 271
 272       if (__access ("/etc/suid-debug", F_OK) != 0)
 273         unsetenv ("MALLOC_CHECK_");
 274     }
 275
 276 #ifdef DL_PLATFORM_INIT
 277   DL_PLATFORM_INIT;
 278 #endif
 279
 280 #ifdef DL_OSVERSION_INIT
 281   DL_OSVERSION_INIT;
 282 #endif
 283
 284   /* Now determine the length of the platform string.  */
 285   if (_dl_platform != NULL)
 286     _dl_platformlen = strlen (_dl_platform);
 287
 288   /* Scan for a program header telling us the stack is nonexecutable.  */
 289   if (_dl_phdr != NULL)
 290     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 291       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 292         {
 293           _dl_stack_flags = _dl_phdr[i].p_flags;
 294           break;
 295         }
 296 }
 297
 298
 299 const struct r_strlenpair *
 300 internal_function
 301 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 302                       size_t *max_capstrlen)
 303 {
 304   static struct r_strlenpair result;
 305   static char buf[1];
 306
 307   result.str = buf;     /* Does not really matter.  */
 308   result.len = 0;
 309
 310   *sz = 1;
 311   return &result;
 312 }
 313
 314
 315 #ifdef DL_SYSINFO_IMPLEMENTATION
 316 DL_SYSINFO_IMPLEMENTATION
 317 #endif