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 # ifdef DL_PLATFORM_AUXV
 215       DL_PLATFORM_AUXV
 216 # endif
 217       }
 218   if (seen == 0xf)
 219     {
 220       __libc_enable_secure = uid != 0 || gid != 0;
 221       __libc_enable_secure_decided = 1;
 222     }
 223 }
 224 #endif
 225
 226
 227 void
 228 internal_function
 229 _dl_non_dynamic_init (void)
 230 {
 231   if (HP_TIMING_AVAIL)
 232     HP_TIMING_NOW (_dl_cpuclock_offset);
 233
 234   if (!_dl_pagesize)
 235     _dl_pagesize = __getpagesize ();
 236
 237   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 238
 239   /* Initialize the data structures for the search paths for shared
 240      objects.  */
 241   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 242
 243   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 244
 245   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 246
 247   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 248
 249   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 250   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 251     _dl_profile_output
 252       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 253
 254   if (__libc_enable_secure)
 255     {
 256       static const char unsecure_envvars[] =
 257         UNSECURE_ENVVARS
 258 #ifdef EXTRA_UNSECURE_ENVVARS
 259         EXTRA_UNSECURE_ENVVARS
 260 #endif
 261         ;
 262       const char *cp = unsecure_envvars;
 263
 264       while (cp < unsecure_envvars + sizeof (unsecure_envvars))
 265         {
 266           __unsetenv (cp);
 267           cp = (const char *) __rawmemchr (cp, '\0') + 1;
 268         }
 269
 270       if (__access ("/etc/suid-debug", F_OK) != 0)
 271         __unsetenv ("MALLOC_CHECK_");
 272     }
 273
 274 #ifdef DL_PLATFORM_INIT
 275   DL_PLATFORM_INIT;
 276 #endif
 277
 278 #ifdef DL_OSVERSION_INIT
 279   DL_OSVERSION_INIT;
 280 #endif
 281
 282   /* Now determine the length of the platform string.  */
 283   if (_dl_platform != NULL)
 284     _dl_platformlen = strlen (_dl_platform);
 285
 286   /* Scan for a program header telling us the stack is nonexecutable.  */
 287   if (_dl_phdr != NULL)
 288     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 289       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 290         {
 291           _dl_stack_flags = _dl_phdr[i].p_flags;
 292           break;
 293         }
 294 }
 295
 296
 297 const struct r_strlenpair *
 298 internal_function
 299 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 300                       size_t *max_capstrlen)
 301 {
 302   static struct r_strlenpair result;
 303   static char buf[1];
 304
 305   result.str = buf;     /* Does not really matter.  */
 306   result.len = 0;
 307
 308   *sz = 1;
 309   return &result;
 310 }
 311
 312
 313 #ifdef DL_SYSINFO_IMPLEMENTATION
 314 DL_SYSINFO_IMPLEMENTATION
 315 #endif