elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2005, 2006, 2007, 2008 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 struct dl_scope_free_list *_dl_scope_free_list;
 139
 140 #ifdef NEED_DL_SYSINFO
 141 /* Needed for improved syscall handling on at least x86/Linux.  */
 142 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 143 #endif
 144 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 145 /* Address of the ELF headers in the vsyscall page.  */
 146 const ElfW(Ehdr) *_dl_sysinfo_dso;
 147 #endif
 148
 149 /* During the program run we must not modify the global data of
 150    loaded shared object simultanously in two threads.  Therefore we
 151    protect `_dl_open' and `_dl_close' in dl-close.c.
 152
 153    This must be a recursive lock since the initializer function of
 154    the loaded object might as well require a call to this function.
 155    At this time it is not anymore a problem to modify the tables.  */
 156 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 157
 158
 159 #ifdef HAVE_AUX_VECTOR
 160 int _dl_clktck;
 161
 162 void
 163 internal_function
 164 _dl_aux_init (ElfW(auxv_t) *av)
 165 {
 166   int seen = 0;
 167   uid_t uid = 0;
 168   gid_t gid = 0;
 169
 170   for (; av->a_type != AT_NULL; ++av)
 171     switch (av->a_type)
 172       {
 173       case AT_PAGESZ:
 174         GLRO(dl_pagesize) = av->a_un.a_val;
 175         break;
 176       case AT_CLKTCK:
 177         GLRO(dl_clktck) = av->a_un.a_val;
 178         break;
 179       case AT_PHDR:
 180         GL(dl_phdr) = (void *) av->a_un.a_val;
 181         break;
 182       case AT_PHNUM:
 183         GL(dl_phnum) = av->a_un.a_val;
 184         break;
 185       case AT_HWCAP:
 186         GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
 187         break;
 188 #ifdef NEED_DL_SYSINFO
 189       case AT_SYSINFO:
 190         GL(dl_sysinfo) = av->a_un.a_val;
 191         break;
 192 #endif
 193 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 194       case AT_SYSINFO_EHDR:
 195         GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
 196         break;
 197 #endif
 198       case AT_UID:
 199         uid ^= av->a_un.a_val;
 200         seen |= 1;
 201         break;
 202       case AT_EUID:
 203         uid ^= av->a_un.a_val;
 204         seen |= 2;
 205         break;
 206       case AT_GID:
 207         gid ^= av->a_un.a_val;
 208         seen |= 4;
 209         break;
 210       case AT_EGID:
 211         gid ^= av->a_un.a_val;
 212         seen |= 8;
 213         break;
 214       case AT_SECURE:
 215         seen = -1;
 216         __libc_enable_secure = av->a_un.a_val;
 217         __libc_enable_secure_decided = 1;
 218         break;
 219 # ifdef DL_PLATFORM_AUXV
 220       DL_PLATFORM_AUXV
 221 # endif
 222       }
 223   if (seen == 0xf)
 224     {
 225       __libc_enable_secure = uid != 0 || gid != 0;
 226       __libc_enable_secure_decided = 1;
 227     }
 228 }
 229 #endif
 230
 231
 232 void
 233 internal_function
 234 _dl_non_dynamic_init (void)
 235 {
 236   if (HP_TIMING_AVAIL)
 237     HP_TIMING_NOW (_dl_cpuclock_offset);
 238
 239   if (!_dl_pagesize)
 240     _dl_pagesize = __getpagesize ();
 241
 242   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 243
 244   /* Initialize the data structures for the search paths for shared
 245      objects.  */
 246   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 247
 248   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 249
 250   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 251
 252   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 253
 254   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 255   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 256     _dl_profile_output
 257       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 258
 259   if (__libc_enable_secure)
 260     {
 261       static const char unsecure_envvars[] =
 262         UNSECURE_ENVVARS
 263 #ifdef EXTRA_UNSECURE_ENVVARS
 264         EXTRA_UNSECURE_ENVVARS
 265 #endif
 266         ;
 267       const char *cp = unsecure_envvars;
 268
 269       while (cp < unsecure_envvars + sizeof (unsecure_envvars))
 270         {
 271           __unsetenv (cp);
 272           cp = (const char *) __rawmemchr (cp, '\0') + 1;
 273         }
 274
 275       if (__access ("/etc/suid-debug", F_OK) != 0)
 276         __unsetenv ("MALLOC_CHECK_");
 277     }
 278
 279 #ifdef DL_PLATFORM_INIT
 280   DL_PLATFORM_INIT;
 281 #endif
 282
 283 #ifdef DL_OSVERSION_INIT
 284   DL_OSVERSION_INIT;
 285 #endif
 286
 287   /* Now determine the length of the platform string.  */
 288   if (_dl_platform != NULL)
 289     _dl_platformlen = strlen (_dl_platform);
 290
 291   /* Scan for a program header telling us the stack is nonexecutable.  */
 292   if (_dl_phdr != NULL)
 293     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 294       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 295         {
 296           _dl_stack_flags = _dl_phdr[i].p_flags;
 297           break;
 298         }
 299 }
 300
 301
 302 const struct r_strlenpair *
 303 internal_function
 304 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 305                       size_t *max_capstrlen)
 306 {
 307   static struct r_strlenpair result;
 308   static char buf[1];
 309
 310   result.str = buf;     /* Does not really matter.  */
 311   result.len = 0;
 312
 313   *sz = 1;
 314   return &result;
 315 }
 316
 317
 318 #ifdef DL_SYSINFO_IMPLEMENTATION
 319 DL_SYSINFO_IMPLEMENTATION
 320 #endif