elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2002, 2003, 2004, 2005 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 /* Namespace information.  */
  71 struct link_namespaces _dl_ns[DL_NNS];
  72
  73 /* Incremented whenever something may have been added to dl_loaded. */
  74 unsigned long long _dl_load_adds;
  75
  76 /* Fake scope.  In dynamically linked binaries this is the scope of the
  77    main application but here we don't have something like this.  So
  78    create a fake scope containing nothing.  */
  79 struct r_scope_elem _dl_initial_searchlist;
  80
  81 #ifndef HAVE_INLINED_SYSCALLS
  82 /* Nonzero during startup.  */
  83 int _dl_starting_up = 1;
  84 #endif
  85
  86 /* Get architecture specific initializer.  */
  87 #include <dl-procinfo.c>
  88
  89 /* We expect less than a second for relocation.  */
  90 #ifdef HP_SMALL_TIMING_AVAIL
  91 # undef HP_TIMING_AVAIL
  92 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
  93 #endif
  94
  95 /* Initial value of the CPU clock.  */
  96 #ifndef HP_TIMING_NONAVAIL
  97 hp_timing_t _dl_cpuclock_offset;
  98 #endif
  99
 100 #ifdef USE_TLS
 101 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
 102 #endif
 103
 104 size_t _dl_pagesize;
 105
 106 unsigned int _dl_osversion;
 107
 108 /* All known directories in sorted order.  */
 109 struct r_search_path_elem *_dl_all_dirs;
 110
 111 /* All directories after startup.  */
 112 struct r_search_path_elem *_dl_init_all_dirs;
 113
 114 /* The object to be initialized first.  */
 115 struct link_map *_dl_initfirst;
 116
 117 /* Descriptor to write debug messages to.  */
 118 int _dl_debug_fd = STDERR_FILENO;
 119
 120 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
 121
 122 ElfW(Phdr) *_dl_phdr;
 123 size_t _dl_phnum;
 124 uint64_t _dl_hwcap __attribute__ ((nocommon));
 125
 126 /* Prevailing state of the stack, PF_X indicating it's executable.  */
 127 ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X;
 128
 129 /* If loading a shared object requires that we make the stack executable
 130    when it was not, we do it by calling this function.
 131    It returns an errno code or zero on success.  */
 132 int (*_dl_make_stack_executable_hook) (void **) internal_function
 133   = _dl_make_stack_executable;
 134
 135
 136 #ifdef NEED_DL_SYSINFO
 137 /* Needed for improved syscall handling on at least x86/Linux.  */
 138 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 139 #endif
 140 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 141 /* Address of the ELF headers in the vsyscall page.  */
 142 const ElfW(Ehdr) *_dl_sysinfo_dso;
 143 #endif
 144
 145 /* During the program run we must not modify the global data of
 146    loaded shared object simultanously in two threads.  Therefore we
 147    protect `_dl_open' and `_dl_close' in dl-close.c.
 148
 149    This must be a recursive lock since the initializer function of
 150    the loaded object might as well require a call to this function.
 151    At this time it is not anymore a problem to modify the tables.  */
 152 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 153
 154
 155 #ifdef HAVE_AUX_VECTOR
 156 int _dl_clktck;
 157
 158 void
 159 internal_function
 160 _dl_aux_init (ElfW(auxv_t) *av)
 161 {
 162   int seen = 0;
 163   uid_t uid = 0;
 164   gid_t gid = 0;
 165
 166   for (; av->a_type != AT_NULL; ++av)
 167     switch (av->a_type)
 168       {
 169       case AT_PAGESZ:
 170         GLRO(dl_pagesize) = av->a_un.a_val;
 171         break;
 172       case AT_CLKTCK:
 173         GLRO(dl_clktck) = av->a_un.a_val;
 174         break;
 175       case AT_PHDR:
 176         GL(dl_phdr) = (void *) av->a_un.a_val;
 177         break;
 178       case AT_PHNUM:
 179         GL(dl_phnum) = av->a_un.a_val;
 180         break;
 181       case AT_HWCAP:
 182         GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
 183         break;
 184 #ifdef NEED_DL_SYSINFO
 185       case AT_SYSINFO:
 186         GL(dl_sysinfo) = av->a_un.a_val;
 187         break;
 188 #endif
 189 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 190       case AT_SYSINFO_EHDR:
 191         GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
 192         break;
 193 #endif
 194       case AT_UID:
 195         uid ^= av->a_un.a_val;
 196         seen |= 1;
 197         break;
 198       case AT_EUID:
 199         uid ^= av->a_un.a_val;
 200         seen |= 2;
 201         break;
 202       case AT_GID:
 203         gid ^= av->a_un.a_val;
 204         seen |= 4;
 205         break;
 206       case AT_EGID:
 207         gid ^= av->a_un.a_val;
 208         seen |= 8;
 209         break;
 210       case AT_SECURE:
 211         seen = -1;
 212         __libc_enable_secure = av->a_un.a_val;
 213         __libc_enable_secure_decided = 1;
 214         break;
 215       }
 216   if (seen == 0xf)
 217     {
 218       __libc_enable_secure = uid != 0 || gid != 0;
 219       __libc_enable_secure_decided = 1;
 220     }
 221 }
 222 #endif
 223
 224
 225 void
 226 internal_function
 227 _dl_non_dynamic_init (void)
 228 {
 229   if (HP_TIMING_AVAIL)
 230     HP_TIMING_NOW (_dl_cpuclock_offset);
 231
 232   if (!_dl_pagesize)
 233     _dl_pagesize = __getpagesize ();
 234
 235   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 236
 237   /* Initialize the data structures for the search paths for shared
 238      objects.  */
 239   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 240
 241   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 242
 243   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 244
 245   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 246
 247   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 248   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 249     _dl_profile_output
 250       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 251
 252   if (__libc_enable_secure)
 253     {
 254       static const char unsecure_envvars[] =
 255         UNSECURE_ENVVARS
 256 #ifdef EXTRA_UNSECURE_ENVVARS
 257         EXTRA_UNSECURE_ENVVARS
 258 #endif
 259         ;
 260       const char *cp = unsecure_envvars;
 261
 262       while (cp < unsecure_envvars + sizeof (unsecure_envvars))
 263         {
 264           __unsetenv (cp);
 265           cp = (const char *) __rawmemchr (cp, '\0') + 1;
 266         }
 267
 268       if (__access ("/etc/suid-debug", F_OK) != 0)
 269         __unsetenv ("MALLOC_CHECK_");
 270     }
 271
 272 #ifdef DL_PLATFORM_INIT
 273   DL_PLATFORM_INIT;
 274 #endif
 275
 276 #ifdef DL_OSVERSION_INIT
 277   DL_OSVERSION_INIT;
 278 #endif
 279
 280   /* Now determine the length of the platform string.  */
 281   if (_dl_platform != NULL)
 282     _dl_platformlen = strlen (_dl_platform);
 283
 284   /* Scan for a program header telling us the stack is nonexecutable.  */
 285   if (_dl_phdr != NULL)
 286     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 287       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 288         {
 289           _dl_stack_flags = _dl_phdr[i].p_flags;
 290           break;
 291         }
 292 }
 293
 294
 295 const struct r_strlenpair *
 296 internal_function
 297 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 298                       size_t *max_capstrlen)
 299 {
 300   static struct r_strlenpair result;
 301   static char buf[1];
 302
 303   result.str = buf;     /* Does not really matter.  */
 304   result.len = 0;
 305
 306   *sz = 1;
 307   return &result;
 308 }
 309
 310
 311 #ifdef DL_SYSINFO_IMPLEMENTATION
 312 DL_SYSINFO_IMPLEMENTATION
 313 #endif