elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2008, 2009 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 /* Random data provided by the kernel.  */
  88 void *_dl_random;
  89
  90 /* Get architecture specific initializer.  */
  91 #include <dl-procinfo.c>
  92
  93 /* We expect less than a second for relocation.  */
  94 #ifdef HP_SMALL_TIMING_AVAIL
  95 # undef HP_TIMING_AVAIL
  96 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
  97 #endif
  98
  99 /* Initial value of the CPU clock.  */
 100 #ifndef HP_TIMING_NONAVAIL
 101 hp_timing_t _dl_cpuclock_offset;
 102 #endif
 103
 104 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
 105
 106 size_t _dl_pagesize;
 107
 108 unsigned int _dl_osversion;
 109
 110 /* All known directories in sorted order.  */
 111 struct r_search_path_elem *_dl_all_dirs;
 112
 113 /* All directories after startup.  */
 114 struct r_search_path_elem *_dl_init_all_dirs;
 115
 116 /* The object to be initialized first.  */
 117 struct link_map *_dl_initfirst;
 118
 119 /* Descriptor to write debug messages to.  */
 120 int _dl_debug_fd = STDERR_FILENO;
 121
 122 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
 123
 124 ElfW(Phdr) *_dl_phdr;
 125 size_t _dl_phnum;
 126 uint64_t _dl_hwcap __attribute__ ((nocommon));
 127
 128 /* Prevailing state of the stack, PF_X indicating it's executable.  */
 129 ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X;
 130
 131 /* If loading a shared object requires that we make the stack executable
 132    when it was not, we do it by calling this function.
 133    It returns an errno code or zero on success.  */
 134 int (*_dl_make_stack_executable_hook) (void **) internal_function
 135   = _dl_make_stack_executable;
 136
 137
 138 /* Function in libpthread to wait for termination of lookups.  */
 139 void (*_dl_wait_lookup_done) (void);
 140
 141 struct dl_scope_free_list *_dl_scope_free_list;
 142
 143 #ifdef NEED_DL_SYSINFO
 144 /* Needed for improved syscall handling on at least x86/Linux.  */
 145 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 146 #endif
 147 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 148 /* Address of the ELF headers in the vsyscall page.  */
 149 const ElfW(Ehdr) *_dl_sysinfo_dso;
 150 #endif
 151
 152 /* During the program run we must not modify the global data of
 153    loaded shared object simultanously in two threads.  Therefore we
 154    protect `_dl_open' and `_dl_close' in dl-close.c.
 155
 156    This must be a recursive lock since the initializer function of
 157    the loaded object might as well require a call to this function.
 158    At this time it is not anymore a problem to modify the tables.  */
 159 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 160
 161
 162 #ifdef HAVE_AUX_VECTOR
 163 int _dl_clktck;
 164
 165 void
 166 internal_function
 167 _dl_aux_init (ElfW(auxv_t) *av)
 168 {
 169   int seen = 0;
 170   uid_t uid = 0;
 171   gid_t gid = 0;
 172
 173   for (; av->a_type != AT_NULL; ++av)
 174     switch (av->a_type)
 175       {
 176       case AT_PAGESZ:
 177         GLRO(dl_pagesize) = av->a_un.a_val;
 178         break;
 179       case AT_CLKTCK:
 180         GLRO(dl_clktck) = av->a_un.a_val;
 181         break;
 182       case AT_PHDR:
 183         GL(dl_phdr) = (void *) av->a_un.a_val;
 184         break;
 185       case AT_PHNUM:
 186         GL(dl_phnum) = av->a_un.a_val;
 187         break;
 188       case AT_HWCAP:
 189         GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
 190         break;
 191 #ifdef NEED_DL_SYSINFO
 192       case AT_SYSINFO:
 193         GL(dl_sysinfo) = av->a_un.a_val;
 194         break;
 195 #endif
 196 #if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
 197       case AT_SYSINFO_EHDR:
 198         GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
 199         break;
 200 #endif
 201       case AT_UID:
 202         uid ^= av->a_un.a_val;
 203         seen |= 1;
 204         break;
 205       case AT_EUID:
 206         uid ^= av->a_un.a_val;
 207         seen |= 2;
 208         break;
 209       case AT_GID:
 210         gid ^= av->a_un.a_val;
 211         seen |= 4;
 212         break;
 213       case AT_EGID:
 214         gid ^= av->a_un.a_val;
 215         seen |= 8;
 216         break;
 217       case AT_SECURE:
 218         seen = -1;
 219         __libc_enable_secure = av->a_un.a_val;
 220         __libc_enable_secure_decided = 1;
 221         break;
 222       case AT_RANDOM:
 223         _dl_random = (void *) av->a_un.a_val;
 224         break;
 225 # ifdef DL_PLATFORM_AUXV
 226       DL_PLATFORM_AUXV
 227 # endif
 228       }
 229   if (seen == 0xf)
 230     {
 231       __libc_enable_secure = uid != 0 || gid != 0;
 232       __libc_enable_secure_decided = 1;
 233     }
 234 }
 235 #endif
 236
 237
 238 void
 239 internal_function
 240 _dl_non_dynamic_init (void)
 241 {
 242   if (HP_TIMING_AVAIL)
 243     HP_TIMING_NOW (_dl_cpuclock_offset);
 244
 245   if (!_dl_pagesize)
 246     _dl_pagesize = __getpagesize ();
 247
 248   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 249
 250   /* Initialize the data structures for the search paths for shared
 251      objects.  */
 252   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 253
 254   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 255
 256   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 257
 258   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 259
 260   _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
 261   if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
 262     _dl_profile_output
 263       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
 264
 265   if (__libc_enable_secure)
 266     {
 267       static const char unsecure_envvars[] =
 268         UNSECURE_ENVVARS
 269 #ifdef EXTRA_UNSECURE_ENVVARS
 270         EXTRA_UNSECURE_ENVVARS
 271 #endif
 272         ;
 273       const char *cp = unsecure_envvars;
 274
 275       while (cp < unsecure_envvars + sizeof (unsecure_envvars))
 276         {
 277           __unsetenv (cp);
 278           cp = (const char *) __rawmemchr (cp, '\0') + 1;
 279         }
 280
 281       if (__access ("/etc/suid-debug", F_OK) != 0)
 282         __unsetenv ("MALLOC_CHECK_");
 283     }
 284
 285 #ifdef DL_PLATFORM_INIT
 286   DL_PLATFORM_INIT;
 287 #endif
 288
 289 #ifdef DL_OSVERSION_INIT
 290   DL_OSVERSION_INIT;
 291 #endif
 292
 293   /* Now determine the length of the platform string.  */
 294   if (_dl_platform != NULL)
 295     _dl_platformlen = strlen (_dl_platform);
 296
 297   /* Scan for a program header telling us the stack is nonexecutable.  */
 298   if (_dl_phdr != NULL)
 299     for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
 300       if (_dl_phdr[i].p_type == PT_GNU_STACK)
 301         {
 302           _dl_stack_flags = _dl_phdr[i].p_flags;
 303           break;
 304         }
 305 }
 306
 307
 308 const struct r_strlenpair *
 309 internal_function
 310 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 311                       size_t *max_capstrlen)
 312 {
 313   static struct r_strlenpair result;
 314   static char buf[1];
 315
 316   result.str = buf;     /* Does not really matter.  */
 317   result.len = 0;
 318
 319   *sz = 1;
 320   return &result;
 321 }
 322
 323
 324 #ifdef DL_SYSINFO_IMPLEMENTATION
 325 DL_SYSINFO_IMPLEMENTATION
 326 #endif