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 /* 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 unsigned long int _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 /* Address of the ELF headers in the vsyscall page.  */
 140 const ElfW(Ehdr) *_dl_sysinfo_dso;
 141 #endif
 142
 143 /* During the program run we must not modify the global data of
 144    loaded shared object simultanously in two threads.  Therefore we
 145    protect `_dl_open' and `_dl_close' in dl-close.c.
 146
 147    This must be a recursive lock since the initializer function of
 148    the loaded object might as well require a call to this function.
 149    At this time it is not anymore a problem to modify the tables.  */
 150 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 151
 152
 153 #ifdef HAVE_AUX_VECTOR
 154 int _dl_clktck;
 155
 156 void
 157 internal_function
 158 _dl_aux_init (ElfW(auxv_t) *av)
 159 {
 160   int seen = 0;
 161   uid_t uid = 0;
 162   gid_t gid = 0;
 163
 164   for (; av->a_type != AT_NULL; ++av)
 165     switch (av->a_type)
 166       {
 167       case AT_PAGESZ:
 168         GLRO(dl_pagesize) = av->a_un.a_val;
 169         break;
 170       case AT_CLKTCK:
 171         GLRO(dl_clktck) = av->a_un.a_val;
 172         break;
 173       case AT_PHDR:
 174         GL(dl_phdr) = av->a_un.a_ptr;
 175         break;
 176       case AT_PHNUM:
 177         GL(dl_phnum) = av->a_un.a_val;
 178         break;
 179       case AT_HWCAP:
 180         GLRO(dl_hwcap) = av->a_un.a_val;
 181         break;
 182 #ifdef NEED_DL_SYSINFO
 183       case AT_SYSINFO:
 184         GL(dl_sysinfo) = av->a_un.a_val;
 185         break;
 186 #endif
 187       case AT_UID:
 188         uid ^= av->a_un.a_val;
 189         seen |= 1;
 190         break;
 191       case AT_EUID:
 192         uid ^= av->a_un.a_val;
 193         seen |= 2;
 194         break;
 195       case AT_GID:
 196         gid ^= av->a_un.a_val;
 197         seen |= 4;
 198         break;
 199       case AT_EGID:
 200         gid ^= av->a_un.a_val;
 201         seen |= 8;
 202         break;
 203       case AT_SECURE:
 204         seen = -1;
 205         __libc_enable_secure = av->a_un.a_val;
 206         __libc_enable_secure_decided = 1;
 207         break;
 208       }
 209   if (seen == 0xf)
 210     {
 211       __libc_enable_secure = uid != 0 || gid != 0;
 212       __libc_enable_secure_decided = 1;
 213     }
 214 }
 215 #endif
 216
 217
 218 void
 219 internal_function
 220 _dl_non_dynamic_init (void)
 221 {
 222   if (HP_TIMING_AVAIL)
 223     HP_TIMING_NOW (_dl_cpuclock_offset);
 224
 225   if (!_dl_pagesize)
 226     _dl_pagesize = __getpagesize ();
 227
 228   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 229
 230   /* Initialize the data structures for the search paths for shared
 231      objects.  */
 232   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 233
 234   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 235
 236   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 237
 238   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 239
 240   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 241   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 242     _dl_profile_output
 243       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 244
 245   if (__libc_enable_secure)
 246     {
 247       static const char unsecure_envvars[] =
 248         UNSECURE_ENVVARS
 249 #ifdef EXTRA_UNSECURE_ENVVARS
 250         EXTRA_UNSECURE_ENVVARS
 251 #endif
 252         ;
 253       const char *cp = unsecure_envvars;
 254
 255       while (cp < unsecure_envvars + sizeof (unsecure_envvars))
 256         {
 257           __unsetenv (cp);
 258           cp = (const char *) __rawmemchr (cp, '\0') + 1;
 259         }
 260
 261       if (__access ("/etc/suid-debug", F_OK) != 0)
 262         __unsetenv ("MALLOC_CHECK_");
 263     }
 264
 265 #ifdef DL_PLATFORM_INIT
 266   DL_PLATFORM_INIT;
 267 #endif
 268
 269 #ifdef DL_OSVERSION_INIT
 270   DL_OSVERSION_INIT;
 271 #endif
 272
 273   /* Now determine the length of the platform string.  */
 274   if (_dl_platform != NULL)
 275     _dl_platformlen = strlen (_dl_platform);
 276
 277   /* Scan for a program header telling us the stack is nonexecutable.  */
 278   if (_dl_phdr != NULL)
 279     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 280       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 281         {
 282           _dl_stack_flags = _dl_phdr[i].p_flags;
 283           break;
 284         }
 285 }
 286
 287
 288 const struct r_strlenpair *
 289 internal_function
 290 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 291                       size_t *max_capstrlen)
 292 {
 293   static struct r_strlenpair result;
 294   static char buf[1];
 295
 296   result.str = buf;     /* Does not really matter.  */
 297   result.len = 0;
 298
 299   *sz = 1;
 300   return &result;
 301 }
 302
 303
 304 #ifdef DL_SYSINFO_IMPLEMENTATION
 305 DL_SYSINFO_IMPLEMENTATION
 306 #endif