elf/get-dynamic-info.h

   1 /* Read the dynamic section at DYN and fill in INFO with indices DT_*.
   2    Copyright (C) 2012-2020 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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* This file is included multiple times and therefore lacks a header
  20    file inclusion guard.  */
  21
  22 #include <assert.h>
  23 #include <libc-diag.h>
  24
  25 #ifndef RESOLVE_MAP
  26 static
  27 #else
  28 auto
  29 #endif
  30 inline void __attribute__ ((unused, always_inline))
  31 elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
  32 {
  33   ElfW(Dyn) *dyn = l->l_ld;
  34   ElfW(Dyn) **info;
  35 #if __ELF_NATIVE_CLASS == 32
  36   typedef Elf32_Word d_tag_utype;
  37 #elif __ELF_NATIVE_CLASS == 64
  38   typedef Elf64_Xword d_tag_utype;
  39 #endif
  40
  41 #if !defined RTLD_BOOTSTRAP && !defined STATIC_PIE_BOOTSTRAP
  42   if (dyn == NULL)
  43     return;
  44 #endif
  45
  46   info = l->l_info;
  47
  48   while (dyn->d_tag != DT_NULL)
  49     {
  50       if ((d_tag_utype) dyn->d_tag < DT_NUM)
  51         info[dyn->d_tag] = dyn;
  52       else if (dyn->d_tag >= DT_LOPROC
  53                && dyn->d_tag < DT_LOPROC + DT_THISPROCNUM)
  54         {
  55           /* This does not violate the array bounds of l->l_info, but
  56              gcc 4.6 on sparc somehow does not see this.  */
  57           DIAG_PUSH_NEEDS_COMMENT;
  58           DIAG_IGNORE_NEEDS_COMMENT (4.6,
  59                                      "-Warray-bounds");
  60           info[dyn->d_tag - DT_LOPROC + DT_NUM] = dyn;
  61           DIAG_POP_NEEDS_COMMENT;
  62         }
  63       else if ((d_tag_utype) DT_VERSIONTAGIDX (dyn->d_tag) < DT_VERSIONTAGNUM)
  64         info[VERSYMIDX (dyn->d_tag)] = dyn;
  65       else if ((d_tag_utype) DT_EXTRATAGIDX (dyn->d_tag) < DT_EXTRANUM)
  66         info[DT_EXTRATAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
  67              + DT_VERSIONTAGNUM] = dyn;
  68       else if ((d_tag_utype) DT_VALTAGIDX (dyn->d_tag) < DT_VALNUM)
  69         info[DT_VALTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
  70              + DT_VERSIONTAGNUM + DT_EXTRANUM] = dyn;
  71       else if ((d_tag_utype) DT_ADDRTAGIDX (dyn->d_tag) < DT_ADDRNUM)
  72         info[DT_ADDRTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
  73              + DT_VERSIONTAGNUM + DT_EXTRANUM + DT_VALNUM] = dyn;
  74       ++dyn;
  75     }
  76
  77 #define DL_RO_DYN_TEMP_CNT      8
  78
  79 #ifndef DL_RO_DYN_SECTION
  80   /* Don't adjust .dynamic unnecessarily.  */
  81   if (l->l_addr != 0)
  82     {
  83       ElfW(Addr) l_addr = l->l_addr;
  84       int cnt = 0;
  85
  86 # define ADJUST_DYN_INFO(tag) \
  87       do                                                                      \
  88         if (info[tag] != NULL)                                                \
  89           {                                                                   \
  90             if (temp)                                                         \
  91               {                                                               \
  92                 temp[cnt].d_tag = info[tag]->d_tag;                           \
  93                 temp[cnt].d_un.d_ptr = info[tag]->d_un.d_ptr + l_addr;        \
  94                 info[tag] = temp + cnt++;                                     \
  95               }                                                               \
  96             else                                                              \
  97               info[tag]->d_un.d_ptr += l_addr;                                \
  98           }                                                                   \
  99       while (0)
 100
 101       ADJUST_DYN_INFO (DT_HASH);
 102       ADJUST_DYN_INFO (DT_PLTGOT);
 103       ADJUST_DYN_INFO (DT_STRTAB);
 104       ADJUST_DYN_INFO (DT_SYMTAB);
 105 # if ! ELF_MACHINE_NO_RELA
 106       ADJUST_DYN_INFO (DT_RELA);
 107 # endif
 108 # if ! ELF_MACHINE_NO_REL
 109       ADJUST_DYN_INFO (DT_REL);
 110 # endif
 111       ADJUST_DYN_INFO (DT_JMPREL);
 112       ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM));
 113       ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH));
 114 # undef ADJUST_DYN_INFO
 115       assert (cnt <= DL_RO_DYN_TEMP_CNT);
 116     }
 117 #endif
 118   if (info[DT_PLTREL] != NULL)
 119     {
 120 #if ELF_MACHINE_NO_RELA
 121       assert (info[DT_PLTREL]->d_un.d_val == DT_REL);
 122 #elif ELF_MACHINE_NO_REL
 123       assert (info[DT_PLTREL]->d_un.d_val == DT_RELA);
 124 #else
 125       assert (info[DT_PLTREL]->d_un.d_val == DT_REL
 126               || info[DT_PLTREL]->d_un.d_val == DT_RELA);
 127 #endif
 128     }
 129 #if ! ELF_MACHINE_NO_RELA
 130   if (info[DT_RELA] != NULL)
 131     assert (info[DT_RELAENT]->d_un.d_val == sizeof (ElfW(Rela)));
 132 # endif
 133 # if ! ELF_MACHINE_NO_REL
 134   if (info[DT_REL] != NULL)
 135     assert (info[DT_RELENT]->d_un.d_val == sizeof (ElfW(Rel)));
 136 #endif
 137 #ifdef RTLD_BOOTSTRAP
 138   /* Only the bind now flags are allowed.  */
 139   assert (info[VERSYMIDX (DT_FLAGS_1)] == NULL
 140           || (info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val & ~DF_1_NOW) == 0);
 141   /* Flags must not be set for ld.so.  */
 142   assert (info[DT_FLAGS] == NULL
 143           || (info[DT_FLAGS]->d_un.d_val & ~DF_BIND_NOW) == 0);
 144 #endif
 145 #if defined RTLD_BOOTSTRAP || defined STATIC_PIE_BOOTSTRAP
 146   assert (info[DT_RUNPATH] == NULL);
 147   assert (info[DT_RPATH] == NULL);
 148 #else
 149   if (info[DT_FLAGS] != NULL)
 150     {
 151       /* Flags are used.  Translate to the old form where available.
 152          Since these l_info entries are only tested for NULL pointers it
 153          is ok if they point to the DT_FLAGS entry.  */
 154       l->l_flags = info[DT_FLAGS]->d_un.d_val;
 155
 156       if (l->l_flags & DF_SYMBOLIC)
 157         info[DT_SYMBOLIC] = info[DT_FLAGS];
 158       if (l->l_flags & DF_TEXTREL)
 159         info[DT_TEXTREL] = info[DT_FLAGS];
 160       if (l->l_flags & DF_BIND_NOW)
 161         info[DT_BIND_NOW] = info[DT_FLAGS];
 162     }
 163   if (info[VERSYMIDX (DT_FLAGS_1)] != NULL)
 164     {
 165       l->l_flags_1 = info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val;
 166       if (l->l_flags_1 & DF_1_NODELETE)
 167         l->l_nodelete_pending = true;
 168
 169       /* Only DT_1_SUPPORTED_MASK bits are supported, and we would like
 170          to assert this, but we can't. Users have been setting
 171          unsupported DF_1_* flags for a long time and glibc has ignored
 172          them. Therefore to avoid breaking existing applications the
 173          best we can do is add a warning during debugging with the
 174          intent of notifying the user of the problem.  */
 175       if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0)
 176           && l->l_flags_1 & ~DT_1_SUPPORTED_MASK)
 177         _dl_debug_printf ("\nWARNING: Unsupported flag value(s) of 0x%x in DT_FLAGS_1.\n",
 178                           l->l_flags_1 & ~DT_1_SUPPORTED_MASK);
 179
 180       if (l->l_flags_1 & DF_1_NOW)
 181         info[DT_BIND_NOW] = info[VERSYMIDX (DT_FLAGS_1)];
 182     }
 183   if (info[DT_RUNPATH] != NULL)
 184     /* If both RUNPATH and RPATH are given, the latter is ignored.  */
 185     info[DT_RPATH] = NULL;
 186 #endif
 187 }