elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2005, 2006 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 #ifdef NEED_DL_SYSINFO
 136 /* Needed for improved syscall handling on at least x86/Linux.  */
 137 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 138 #endif
 139 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 140 /* Address of the ELF headers in the vsyscall page.  */
 141 const ElfW(Ehdr) *_dl_sysinfo_dso;
 142 #endif
 143
 144 /* During the program run we must not modify the global data of
 145    loaded shared object simultanously in two threads.  Therefore we
 146    protect `_dl_open' and `_dl_close' in dl-close.c.
 147
 148    This must be a recursive lock since the initializer function of
 149    the loaded object might as well require a call to this function.
 150    At this time it is not anymore a problem to modify the tables.  */
 151 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 152
 153
 154 #ifdef HAVE_AUX_VECTOR
 155 int _dl_clktck;
 156
 157 void
 158 internal_function
 159 _dl_aux_init (ElfW(auxv_t) *av)
 160 {
 161   int seen = 0;
 162   uid_t uid = 0;
 163   gid_t gid = 0;
 164
 165   for (; av->a_type != AT_NULL; ++av)
 166     switch (av->a_type)
 167       {
 168       case AT_PAGESZ:
 169         GLRO(dl_pagesize) = av->a_un.a_val;
 170         break;
 171       case AT_CLKTCK:
 172         GLRO(dl_clktck) = av->a_un.a_val;
 173         break;
 174       case AT_PHDR:
 175         GL(dl_phdr) = (void *) av->a_un.a_val;
 176         break;
 177       case AT_PHNUM:
 178         GL(dl_phnum) = av->a_un.a_val;
 179         break;
 180       case AT_HWCAP:
 181         GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
 182         break;
 183 #ifdef NEED_DL_SYSINFO
 184       case AT_SYSINFO:
 185         GL(dl_sysinfo) = av->a_un.a_val;
 186         break;
 187 #endif
 188 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 189       case AT_SYSINFO_EHDR:
 190         GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
 191         break;
 192 #endif
 193       case AT_UID:
 194         uid ^= av->a_un.a_val;
 195         seen |= 1;
 196         break;
 197       case AT_EUID:
 198         uid ^= av->a_un.a_val;
 199         seen |= 2;
 200         break;
 201       case AT_GID:
 202         gid ^= av->a_un.a_val;
 203         seen |= 4;
 204         break;
 205       case AT_EGID:
 206         gid ^= av->a_un.a_val;
 207         seen |= 8;
 208         break;
 209       case AT_SECURE:
 210         seen = -1;
 211         __libc_enable_secure = av->a_un.a_val;
 212         __libc_enable_secure_decided = 1;
 213         break;
 214       }
 215   if (seen == 0xf)
 216     {
 217       __libc_enable_secure = uid != 0 || gid != 0;
 218       __libc_enable_secure_decided = 1;
 219     }
 220 }
 221 #endif
 222
 223
 224 void
 225 internal_function
 226 _dl_non_dynamic_init (void)
 227 {
 228   if (HP_TIMING_AVAIL)
 229     HP_TIMING_NOW (_dl_cpuclock_offset);
 230
 231   if (!_dl_pagesize)
 232     _dl_pagesize = __getpagesize ();
 233
 234   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 235
 236   /* Initialize the data structures for the search paths for shared
 237      objects.  */
 238   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 239
 240   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 241
 242   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 243
 244   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 245
 246   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 247   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 248     _dl_profile_output
 249       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 250
 251   if (__libc_enable_secure)
 252     {
 253       static const char unsecure_envvars[] =
 254         UNSECURE_ENVVARS
 255 #ifdef EXTRA_UNSECURE_ENVVARS
 256         EXTRA_UNSECURE_ENVVARS
 257 #endif
 258         ;
 259       const char *cp = unsecure_envvars;
 260
 261       while (cp < unsecure_envvars + sizeof (unsecure_envvars))
 262         {
 263           __unsetenv (cp);
 264           cp = (const char *) __rawmemchr (cp, '\0') + 1;
 265         }
 266
 267       if (__access ("/etc/suid-debug", F_OK) != 0)
 268         __unsetenv ("MALLOC_CHECK_");
 269     }
 270
 271 #ifdef DL_PLATFORM_INIT
 272   DL_PLATFORM_INIT;
 273 #endif
 274
 275 #ifdef DL_OSVERSION_INIT
 276   DL_OSVERSION_INIT;
 277 #endif
 278
 279   /* Now determine the length of the platform string.  */
 280   if (_dl_platform != NULL)
 281     _dl_platformlen = strlen (_dl_platform);
 282
 283   /* Scan for a program header telling us the stack is nonexecutable.  */
 284   if (_dl_phdr != NULL)
 285     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 286       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 287         {
 288           _dl_stack_flags = _dl_phdr[i].p_flags;
 289           break;
 290         }
 291 }
 292
 293
 294 const struct r_strlenpair *
 295 internal_function
 296 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 297                       size_t *max_capstrlen)
 298 {
 299   static struct r_strlenpair result;
 300   static char buf[1];
 301
 302   result.str = buf;     /* Does not really matter.  */
 303   result.len = 0;
 304
 305   *sz = 1;
 306   return &result;
 307 }
 308
 309
 310 #ifdef DL_SYSINFO_IMPLEMENTATION
 311 DL_SYSINFO_IMPLEMENTATION
 312 #endif