elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2005, 2006, 2007 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 <dl-procinfo.h>
  33 #include <unsecvars.h>
  34 #include <hp-timing.h>
  35
  36 extern char *__progname;
  37 char **_dl_argv = &__progname;  /* This is checked for some error messages.  */
  38
  39 /* Name of the architecture.  */
  40 const char *_dl_platform;
  41 size_t _dl_platformlen;
  42
  43 int _dl_debug_mask;
  44 int _dl_lazy;
  45 ElfW(Addr) _dl_use_load_bias = -2;
  46 int _dl_dynamic_weak;
  47
  48 /* If nonzero print warnings about problematic situations.  */
  49 int _dl_verbose;
  50
  51 /* We never do profiling.  */
  52 const char *_dl_profile;
  53 const char *_dl_profile_output;
  54
  55 /* Names of shared object for which the RUNPATHs and RPATHs should be
  56    ignored.  */
  57 const char *_dl_inhibit_rpath;
  58
  59 /* The map for the object we will profile.  */
  60 struct link_map *_dl_profile_map;
  61
  62 /* This is the address of the last stack address ever used.  */
  63 void *__libc_stack_end;
  64
  65 /* Path where the binary is found.  */
  66 const char *_dl_origin_path;
  67
  68 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  69 int _dl_bind_not;
  70
  71 /* Namespace information.  */
  72 struct link_namespaces _dl_ns[DL_NNS];
  73
  74 /* Incremented whenever something may have been added to dl_loaded. */
  75 unsigned long long _dl_load_adds;
  76
  77 /* Fake scope.  In dynamically linked binaries this is the scope of the
  78    main application but here we don't have something like this.  So
  79    create a fake scope containing nothing.  */
  80 struct r_scope_elem _dl_initial_searchlist;
  81
  82 #ifndef HAVE_INLINED_SYSCALLS
  83 /* Nonzero during startup.  */
  84 int _dl_starting_up = 1;
  85 #endif
  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 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
 102
 103 size_t _dl_pagesize;
 104
 105 unsigned int _dl_osversion;
 106
 107 /* All known directories in sorted order.  */
 108 struct r_search_path_elem *_dl_all_dirs;
 109
 110 /* All directories after startup.  */
 111 struct r_search_path_elem *_dl_init_all_dirs;
 112
 113 /* The object to be initialized first.  */
 114 struct link_map *_dl_initfirst;
 115
 116 /* Descriptor to write debug messages to.  */
 117 int _dl_debug_fd = STDERR_FILENO;
 118
 119 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
 120
 121 ElfW(Phdr) *_dl_phdr;
 122 size_t _dl_phnum;
 123 uint64_t _dl_hwcap __attribute__ ((nocommon));
 124
 125 /* Prevailing state of the stack, PF_X indicating it's executable.  */
 126 ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X;
 127
 128 /* If loading a shared object requires that we make the stack executable
 129    when it was not, we do it by calling this function.
 130    It returns an errno code or zero on success.  */
 131 int (*_dl_make_stack_executable_hook) (void **) internal_function
 132   = _dl_make_stack_executable;
 133
 134
 135 /* Function in libpthread to wait for termination of lookups.  */
 136 void (*_dl_wait_lookup_done) (void);
 137
 138 #ifdef NEED_DL_SYSINFO
 139 /* Needed for improved syscall handling on at least x86/Linux.  */
 140 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 141 #endif
 142 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 143 /* Address of the ELF headers in the vsyscall page.  */
 144 const ElfW(Ehdr) *_dl_sysinfo_dso;
 145 #endif
 146
 147 /* During the program run we must not modify the global data of
 148    loaded shared object simultanously in two threads.  Therefore we
 149    protect `_dl_open' and `_dl_close' in dl-close.c.
 150
 151    This must be a recursive lock since the initializer function of
 152    the loaded object might as well require a call to this function.
 153    At this time it is not anymore a problem to modify the tables.  */
 154 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 155
 156
 157 #ifdef HAVE_AUX_VECTOR
 158 int _dl_clktck;
 159
 160 void
 161 internal_function
 162 _dl_aux_init (ElfW(auxv_t) *av)
 163 {
 164   int seen = 0;
 165   uid_t uid = 0;
 166   gid_t gid = 0;
 167
 168   for (; av->a_type != AT_NULL; ++av)
 169     switch (av->a_type)
 170       {
 171       case AT_PAGESZ:
 172         GLRO(dl_pagesize) = av->a_un.a_val;
 173         break;
 174       case AT_CLKTCK:
 175         GLRO(dl_clktck) = av->a_un.a_val;
 176         break;
 177       case AT_PHDR:
 178         GL(dl_phdr) = (void *) av->a_un.a_val;
 179         break;
 180       case AT_PHNUM:
 181         GL(dl_phnum) = av->a_un.a_val;
 182         break;
 183       case AT_HWCAP:
 184         GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
 185         break;
 186 #ifdef NEED_DL_SYSINFO
 187       case AT_SYSINFO:
 188         GL(dl_sysinfo) = av->a_un.a_val;
 189         break;
 190 #endif
 191 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 192       case AT_SYSINFO_EHDR:
 193         GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
 194         break;
 195 #endif
 196       case AT_UID:
 197         uid ^= av->a_un.a_val;
 198         seen |= 1;
 199         break;
 200       case AT_EUID:
 201         uid ^= av->a_un.a_val;
 202         seen |= 2;
 203         break;
 204       case AT_GID:
 205         gid ^= av->a_un.a_val;
 206         seen |= 4;
 207         break;
 208       case AT_EGID:
 209         gid ^= av->a_un.a_val;
 210         seen |= 8;
 211         break;
 212       case AT_SECURE:
 213         seen = -1;
 214         __libc_enable_secure = av->a_un.a_val;
 215         __libc_enable_secure_decided = 1;
 216         break;
 217 # ifdef DL_PLATFORM_AUXV
 218       DL_PLATFORM_AUXV
 219 # endif
 220       }
 221   if (seen == 0xf)
 222     {
 223       __libc_enable_secure = uid != 0 || gid != 0;
 224       __libc_enable_secure_decided = 1;
 225     }
 226 }
 227 #endif
 228
 229
 230 void
 231 internal_function
 232 _dl_non_dynamic_init (void)
 233 {
 234   if (HP_TIMING_AVAIL)
 235     HP_TIMING_NOW (_dl_cpuclock_offset);
 236
 237   if (!_dl_pagesize)
 238     _dl_pagesize = __getpagesize ();
 239
 240   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 241
 242   /* Initialize the data structures for the search paths for shared
 243      objects.  */
 244   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 245
 246   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 247
 248   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 249
 250   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 251
 252   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 253   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 254     _dl_profile_output
 255       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 256
 257   if (__libc_enable_secure)
 258     {
 259       static const char unsecure_envvars[] =
 260         UNSECURE_ENVVARS
 261 #ifdef EXTRA_UNSECURE_ENVVARS
 262         EXTRA_UNSECURE_ENVVARS
 263 #endif
 264         ;
 265       const char *cp = unsecure_envvars;
 266
 267       while (cp < unsecure_envvars + sizeof (unsecure_envvars))
 268         {
 269           __unsetenv (cp);
 270           cp = (const char *) __rawmemchr (cp, '\0') + 1;
 271         }
 272
 273       if (__access ("/etc/suid-debug", F_OK) != 0)
 274         __unsetenv ("MALLOC_CHECK_");
 275     }
 276
 277 #ifdef DL_PLATFORM_INIT
 278   DL_PLATFORM_INIT;
 279 #endif
 280
 281 #ifdef DL_OSVERSION_INIT
 282   DL_OSVERSION_INIT;
 283 #endif
 284
 285   /* Now determine the length of the platform string.  */
 286   if (_dl_platform != NULL)
 287     _dl_platformlen = strlen (_dl_platform);
 288
 289   /* Scan for a program header telling us the stack is nonexecutable.  */
 290   if (_dl_phdr != NULL)
 291     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 292       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 293         {
 294           _dl_stack_flags = _dl_phdr[i].p_flags;
 295           break;
 296         }
 297 }
 298
 299
 300 const struct r_strlenpair *
 301 internal_function
 302 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 303                       size_t *max_capstrlen)
 304 {
 305   static struct r_strlenpair result;
 306   static char buf[1];
 307
 308   result.str = buf;     /* Does not really matter.  */
 309   result.len = 0;
 310
 311   *sz = 1;
 312   return &result;
 313 }
 314
 315
 316 #ifdef DL_SYSINFO_IMPLEMENTATION
 317 DL_SYSINFO_IMPLEMENTATION
 318 #endif