elf/do-rel.h

   1 /* Do relocations for ELF dynamic linking.
   2    Copyright (C) 1995-2023 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 #include <ldsodefs.h>
  20
  21 /* This file may be included twice, to define both
  22    `elf_dynamic_do_rel' and `elf_dynamic_do_rela'.  */
  23
  24 #ifdef DO_RELA
  25 # define elf_dynamic_do_Rel             elf_dynamic_do_Rela
  26 # define Rel                            Rela
  27 # define elf_machine_rel                elf_machine_rela
  28 # define elf_machine_rel_relative       elf_machine_rela_relative
  29 #endif
  30
  31 #ifndef DO_ELF_MACHINE_REL_RELATIVE
  32 # define DO_ELF_MACHINE_REL_RELATIVE(map, l_addr, relative) \
  33   elf_machine_rel_relative (l_addr, relative,                                 \
  34                             (void *) (l_addr + relative->r_offset))
  35 #endif
  36
  37 /* Perform the relocations in MAP on the running program image as specified
  38    by RELTAG, SZTAG.  If LAZY is nonzero, this is the first pass on PLT
  39    relocations; they should be set up to call _dl_runtime_resolve, rather
  40    than fully resolved now.  */
  41
  42 static inline void __attribute__ ((always_inline))
  43 elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[],
  44                     ElfW(Addr) reladdr, ElfW(Addr) relsize,
  45                     __typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative,
  46                     int lazy, int skip_ifunc)
  47 {
  48   const ElfW(Rel) *relative = (const void *) reladdr;
  49   const ElfW(Rel) *r = relative + nrelative;
  50   const ElfW(Rel) *end = (const void *) (reladdr + relsize);
  51   ElfW(Addr) l_addr = map->l_addr;
  52   const ElfW(Sym) *const symtab
  53       = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
  54
  55 #ifdef RTLD_BOOTSTRAP
  56   for (; relative < r; ++relative)
  57     DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative);
  58
  59   const ElfW (Half) *const version
  60       = (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
  61   for (; r < end; ++r)
  62     {
  63       ElfW (Half) ndx = version[ELFW (R_SYM) (r->r_info)] & 0x7fff;
  64       const ElfW (Sym) *sym = &symtab[ELFW (R_SYM) (r->r_info)];
  65       void *const r_addr_arg = (void *) (l_addr + r->r_offset);
  66       const struct r_found_version *rversion = &map->l_versions[ndx];
  67
  68       elf_machine_rel (map, scope, r, sym, rversion, r_addr_arg, skip_ifunc);
  69     }
  70 #else /* !RTLD_BOOTSTRAP */
  71 # if defined ELF_MACHINE_IRELATIVE
  72   const ElfW(Rel) *r2 = NULL;
  73   const ElfW(Rel) *end2 = NULL;
  74 # endif
  75
  76 #if !defined DO_RELA || !defined ELF_MACHINE_PLT_REL
  77   /* We never bind lazily during ld.so bootstrap.  Unfortunately gcc is
  78      not clever enough to see through all the function calls to realize
  79      that.  */
  80   if (lazy)
  81     {
  82       /* Doing lazy PLT relocations; they need very little info.  */
  83       for (; r < end; ++r)
  84 # ifdef ELF_MACHINE_IRELATIVE
  85         if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
  86           {
  87             if (r2 == NULL)
  88               r2 = r;
  89             end2 = r;
  90           }
  91         else
  92 # endif
  93           elf_machine_lazy_rel (map, scope, l_addr, r, skip_ifunc);
  94
  95 # ifdef ELF_MACHINE_IRELATIVE
  96       if (r2 != NULL)
  97         for (; r2 <= end2; ++r2)
  98           if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
  99             elf_machine_lazy_rel (map, scope, l_addr, r2, skip_ifunc);
 100 # endif
 101     }
 102   else
 103 #endif
 104     {
 105       /* This is defined in rtld.c, but nowhere in the static libc.a; make
 106          the reference weak so static programs can still link.  This
 107          declaration cannot be done when compiling rtld.c (i.e. #ifdef
 108          RTLD_BOOTSTRAP) because rtld.c contains the common defn for
 109          _dl_rtld_map, which is incompatible with a weak decl in the same
 110          file.  */
 111 # ifndef SHARED
 112       weak_extern (GL(dl_rtld_map));
 113 # endif
 114       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
 115 # if !defined DO_RELA || defined ELF_MACHINE_REL_RELATIVE
 116         /* Rela platforms get the offset from r_addend and this must
 117            be copied in the relocation address.  Therefore we can skip
 118            the relative relocations only if this is for rel
 119            relocations or rela relocations if they are computed as
 120            memory_loc += l_addr...  */
 121         if (l_addr != 0)
 122 # endif
 123           for (; relative < r; ++relative)
 124             DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative);
 125
 126       if (map->l_info[VERSYMIDX (DT_VERSYM)])
 127         {
 128           const ElfW(Half) *const version =
 129             (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
 130
 131           for (; r < end; ++r)
 132             {
 133               ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)] & 0x7fff;
 134               const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (r->r_info)];
 135               void *const r_addr_arg = (void *) (l_addr + r->r_offset);
 136               const struct r_found_version *rversion = &map->l_versions[ndx];
 137 #if defined ELF_MACHINE_IRELATIVE
 138               if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
 139                 {
 140                   if (r2 == NULL)
 141                     r2 = r;
 142                   end2 = r;
 143                   continue;
 144                 }
 145 #endif
 146
 147               elf_machine_rel (map, scope, r, sym, rversion, r_addr_arg,
 148                                skip_ifunc);
 149 #if defined SHARED
 150               if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_JMP_SLOT
 151                   && GLRO(dl_naudit) > 0)
 152                 {
 153                   struct link_map *sym_map
 154                     = RESOLVE_MAP (map, scope, &sym, rversion,
 155                                    ELF_MACHINE_JMP_SLOT);
 156                   if (sym != NULL)
 157                     _dl_audit_symbind (map, NULL, sym, r_addr_arg, sym_map);
 158                 }
 159 #endif
 160             }
 161
 162 #if defined ELF_MACHINE_IRELATIVE
 163           if (r2 != NULL)
 164             for (; r2 <= end2; ++r2)
 165               if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
 166                 {
 167                   ElfW(Half) ndx
 168                     = version[ELFW(R_SYM) (r2->r_info)] & 0x7fff;
 169                   elf_machine_rel (map, scope, r2,
 170                                    &symtab[ELFW(R_SYM) (r2->r_info)],
 171                                    &map->l_versions[ndx],
 172                                    (void *) (l_addr + r2->r_offset),
 173                                    skip_ifunc);
 174                 }
 175 #endif
 176         }
 177       else
 178         {
 179           for (; r < end; ++r)
 180             {
 181               const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (r->r_info)];
 182               void *const r_addr_arg = (void *) (l_addr + r->r_offset);
 183 # ifdef ELF_MACHINE_IRELATIVE
 184               if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
 185                 {
 186                   if (r2 == NULL)
 187                     r2 = r;
 188                   end2 = r;
 189                   continue;
 190                 }
 191 # endif
 192               elf_machine_rel (map, scope, r, sym, NULL, r_addr_arg,
 193                                skip_ifunc);
 194 # if defined SHARED
 195               if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_JMP_SLOT
 196                   && GLRO(dl_naudit) > 0)
 197                 {
 198                   struct link_map *sym_map
 199                     = RESOLVE_MAP (map, scope, &sym,
 200                                    (struct r_found_version *) NULL,
 201                                    ELF_MACHINE_JMP_SLOT);
 202                   if (sym != NULL)
 203                     _dl_audit_symbind (map, NULL , sym,r_addr_arg, sym_map);
 204                 }
 205 # endif
 206             }
 207
 208 # ifdef ELF_MACHINE_IRELATIVE
 209           if (r2 != NULL)
 210             for (; r2 <= end2; ++r2)
 211               if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
 212                 elf_machine_rel (map, scope, r2, &symtab[ELFW(R_SYM) (r2->r_info)],
 213                                  NULL, (void *) (l_addr + r2->r_offset),
 214                                  skip_ifunc);
 215 # endif
 216         }
 217     }
 218 #endif /* !RTLD_BOOTSTRAP */
 219 }
 220
 221 #undef elf_dynamic_do_Rel
 222 #undef Rel
 223 #undef elf_machine_rel
 224 #undef elf_machine_rel_relative
 225 #undef DO_ELF_MACHINE_REL_RELATIVE
 226 #undef DO_RELA