ldso/ldso/x86_64/elfinterp.c

   1 /* x86_64 ELF shared library loader suppport
   2  *
   3  * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
   4  *                              David Engel, Hongjiu Lu and Mitch D'Souza
   5  * Copyright (C) 2001-2004 Erik Andersen
   6  *
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. The name of the above contributors may not be
  15  *    used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 #include "ldso.h"
  32
  33 /* Program to load an ELF binary on a linux system, and run it.
  34    References to symbols in sharable libraries can be resolved by either
  35    an ELF sharable library or a linux style of shared library. */
  36
  37 extern int _dl_linux_resolve(void);
  38
  39 unsigned long
  40 _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
  41 {
  42         ELF_RELOC *this_reloc;
  43         char *strtab;
  44         ElfW(Sym) *symtab;
  45         int symtab_index;
  46         char *rel_addr;
  47         char *new_addr;
  48         char **got_addr;
  49         ElfW(Addr) instr_addr;
  50         char *symname;
  51
  52         rel_addr = (char *)tpnt->dynamic_info[DT_JMPREL];
  53         this_reloc = (ELF_RELOC *)(rel_addr + reloc_entry);
  54         symtab_index = ELF_R_SYM(this_reloc->r_info);
  55
  56         symtab = (ElfW(Sym) *)tpnt->dynamic_info[DT_SYMTAB];
  57         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
  58         symname = strtab + symtab[symtab_index].st_name;
  59
  60         /* Address of the jump instruction to fix up. */
  61         instr_addr = (this_reloc->r_offset + tpnt->loadaddr);
  62         got_addr = (char **)instr_addr;
  63
  64         /* Get the address of the GOT entry. */
  65         new_addr = _dl_find_hash(symname, &_dl_loaded_modules->symbol_scope, tpnt, ELF_RTYPE_CLASS_PLT, NULL);
  66         if (unlikely(!new_addr)) {
  67                 _dl_dprintf(2, "%s: Can't resolve symbol '%s'\n", _dl_progname, symname);
  68                 _dl_exit(1);
  69         }
  70
  71 #if defined (__SUPPORT_LD_DEBUG__)
  72         if ((unsigned long)got_addr < 0x40000000) {
  73                 if (_dl_debug_bindings) {
  74                         _dl_dprintf(_dl_debug_file, "\nresolve function: %s", symname);
  75                         if (_dl_debug_detail)
  76                                 _dl_dprintf(_dl_debug_file,
  77                                             "\tpatched: %x ==> %x @ %x\n",
  78                                             *got_addr, new_addr, got_addr);
  79                 }
  80         }
  81         if (!_dl_debug_nofixups)
  82 #endif
  83                 *got_addr = new_addr;
  84
  85         return (unsigned long)new_addr;
  86 }
  87
  88 static int
  89 _dl_parse(struct elf_resolve *tpnt, struct r_scope_elem *scope,
  90           unsigned long rel_addr, unsigned long rel_size,
  91           int (*reloc_fnc)(struct elf_resolve *tpnt, struct r_scope_elem *scope,
  92                            ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab))
  93 {
  94         unsigned int i;
  95         char *strtab;
  96         ElfW(Sym) *symtab;
  97         ELF_RELOC *rpnt;
  98         int symtab_index;
  99
 100         /* Parse the relocation information. */
 101         rpnt = (ELF_RELOC *)rel_addr;
 102         rel_size /= sizeof(ELF_RELOC);
 103
 104         symtab = (ElfW(Sym) *)tpnt->dynamic_info[DT_SYMTAB];
 105         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
 106
 107         for (i = 0; i < rel_size; i++, rpnt++) {
 108                 int res;
 109
 110                 symtab_index = ELF_R_SYM(rpnt->r_info);
 111
 112                 debug_sym(symtab, strtab, symtab_index);
 113                 debug_reloc(symtab, strtab, rpnt);
 114
 115                 res = reloc_fnc(tpnt, scope, rpnt, symtab, strtab);
 116
 117                 if (res == 0)
 118                         continue;
 119
 120                 _dl_dprintf(2, "\n%s: ", _dl_progname);
 121
 122                 if (symtab_index)
 123                         _dl_dprintf(2, "symbol '%s': ",
 124                                     strtab + symtab[symtab_index].st_name);
 125
 126                 if (unlikely(res < 0)) {
 127                         int reloc_type = ELF_R_TYPE(rpnt->r_info);
 128                         _dl_dprintf(2, "can't handle reloc type "
 129                                     "%x\n", reloc_type);
 130                         _dl_exit(-res);
 131                 } else if (unlikely(res > 0)) {
 132                         _dl_dprintf(2, "can't resolve symbol\n");
 133                         return res;
 134                 }
 135         }
 136
 137         return 0;
 138 }
 139
 140 static int
 141 _dl_do_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
 142              ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 143 {
 144         int reloc_type;
 145         int symtab_index;
 146         char *symname;
 147 #if defined USE_TLS && USE_TLS
 148         struct elf_resolve *tls_tpnt;
 149 #endif
 150         struct symbol_ref sym_ref;
 151         ElfW(Addr) *reloc_addr;
 152         ElfW(Addr) symbol_addr;
 153 #if defined (__SUPPORT_LD_DEBUG__)
 154         ElfW(Addr) old_val;
 155 #endif
 156
 157         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
 158         reloc_type = ELF_R_TYPE(rpnt->r_info);
 159         symtab_index = ELF_R_SYM(rpnt->r_info);
 160         sym_ref.sym = &symtab[symtab_index];
 161         sym_ref.tpnt = NULL;
 162         symbol_addr = 0;
 163         symname = strtab + sym_ref.sym->st_name;
 164
 165         if (symtab_index) {
 166                 symbol_addr = (ElfW(Addr))_dl_find_hash(symname, scope, tpnt,
 167                                 elf_machine_type_class(reloc_type), &sym_ref);
 168                 /*
 169                  * We want to allow undefined references to weak symbols - this
 170                  * might have been intentional.  We should not be linking local
 171                  * symbols here, so all bases should be covered.
 172                  */
 173                 if (unlikely(!symbol_addr && (ELF_ST_TYPE(sym_ref.sym->st_info) != STT_TLS)
 174                                         && (ELF_ST_BIND(sym_ref.sym->st_info) != STB_WEAK))) {
 175                         /* This may be non-fatal if called from dlopen. */
 176                         return 1;
 177                 }
 178                 if (_dl_trace_prelink) {
 179                         _dl_debug_lookup (symname, tpnt, &symtab[symtab_index],
 180                                                 &sym_ref, elf_machine_type_class(reloc_type));
 181                 }
 182 #if defined USE_TLS && USE_TLS
 183                 tls_tpnt = sym_ref.tpnt;
 184 #endif
 185         } else {
 186                 /* Relocs against STN_UNDEF are usually treated as using a
 187                  * symbol value of zero, and using the module containing the
 188                  * reloc itself. */
 189                 symbol_addr = sym_ref.sym->st_value;
 190 #if defined USE_TLS && USE_TLS
 191                 tls_tpnt = tpnt;
 192 #endif
 193         }
 194
 195 #if defined (__SUPPORT_LD_DEBUG__)
 196         old_val = *reloc_addr;
 197 #endif
 198
 199         switch (reloc_type) {
 200                 case R_X86_64_NONE:
 201                         break;
 202
 203                 case R_X86_64_64:
 204                         *reloc_addr = symbol_addr + rpnt->r_addend;
 205                         break;
 206
 207                 case R_X86_64_PC32:
 208                         *reloc_addr = symbol_addr + rpnt->r_addend - rpnt->r_offset;
 209                         break;
 210
 211                 case R_X86_64_GLOB_DAT:
 212                 case R_X86_64_JUMP_SLOT:
 213                         *reloc_addr = symbol_addr + rpnt->r_addend;
 214                         break;
 215
 216                 /* handled by elf_machine_relative()
 217                 case R_X86_64_RELATIVE:
 218                         *reloc_addr = map->l_addr + rpnt->r_addend;
 219                         break;
 220                 */
 221 #if defined USE_TLS && USE_TLS
 222                 case R_X86_64_DTPMOD64:
 223                         *reloc_addr = tls_tpnt->l_tls_modid;
 224                         break;
 225                 case R_X86_64_DTPOFF64:
 226                         /* During relocation all TLS symbols are defined and used.
 227                          * Therefore the offset is already correct.  */
 228                         *reloc_addr = symbol_addr + rpnt->r_addend;
 229                         break;
 230                 case R_X86_64_TPOFF64:
 231                         /* The offset is negative, forward from the thread pointer.
 232                          * We know the offset of the object the symbol is contained in.
 233                          * It is a negative value which will be added to the
 234                          * thread pointer.  */
 235                         CHECK_STATIC_TLS ((struct link_map *) tls_tpnt);
 236                         *reloc_addr = symbol_addr - tls_tpnt->l_tls_offset + rpnt->r_addend;
 237                         break;
 238 #endif
 239                 case R_X86_64_32:
 240                         *(unsigned int *) reloc_addr = symbol_addr + rpnt->r_addend;
 241                         /* XXX: should check for overflow eh ? */
 242                         break;
 243
 244                 case R_X86_64_COPY:
 245                         if (symbol_addr) {
 246 #if defined (__SUPPORT_LD_DEBUG__)
 247                                 if (_dl_debug_move)
 248                                         _dl_dprintf(_dl_debug_file,
 249                                                     "\t%s move %d bytes from %x to %x\n",
 250                                                     symname, sym_ref.sym->st_size,
 251                                                     symbol_addr, reloc_addr);
 252 #endif
 253
 254                                 _dl_memcpy((char *)reloc_addr,
 255                                            (char *)symbol_addr,
 256                                            sym_ref.sym->st_size);
 257                         }
 258 #if defined (__SUPPORT_LD_DEBUG__)
 259                         else
 260                                 _dl_dprintf(_dl_debug_file, "no symbol_addr to copy !?\n");
 261 #endif
 262                         break;
 263
 264                 default:
 265                         return -1;      /* Calls _dl_exit(1). */
 266         }
 267
 268 #if defined (__SUPPORT_LD_DEBUG__)
 269         if (_dl_debug_reloc && _dl_debug_detail)
 270                 _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
 271                             old_val, *reloc_addr, reloc_addr);
 272 #endif
 273
 274         return 0;
 275 }
 276
 277 static int
 278 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
 279                   ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 280 {
 281         int reloc_type;
 282         ElfW(Addr) *reloc_addr;
 283 #if defined (__SUPPORT_LD_DEBUG__)
 284         ElfW(Addr) old_val;
 285 #endif
 286
 287         (void)scope;
 288         (void)strtab;
 289
 290         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + rpnt->r_offset);
 291         reloc_type = ELF_R_TYPE(rpnt->r_info);
 292
 293 #if defined (__SUPPORT_LD_DEBUG__)
 294         old_val = *reloc_addr;
 295 #endif
 296
 297         switch (reloc_type) {
 298                 case R_X86_64_NONE:
 299                         break;
 300                 case R_X86_64_JUMP_SLOT:
 301                         *reloc_addr += (unsigned long)tpnt->loadaddr;
 302                         break;
 303                 default:
 304                         _dl_exit(1);
 305         }
 306
 307 #if defined (__SUPPORT_LD_DEBUG__)
 308         if (_dl_debug_reloc && _dl_debug_detail)
 309                 _dl_dprintf(_dl_debug_file, "\tpatched_lazy: %x ==> %x @ %x\n",
 310                             old_val, *reloc_addr, reloc_addr);
 311 #endif
 312
 313         return 0;
 314 }
 315
 316 void
 317 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
 318                                       unsigned long rel_addr,
 319                                       unsigned long rel_size)
 320 {
 321         (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
 322 }
 323
 324 int
 325 _dl_parse_relocation_information(struct dyn_elf *rpnt,
 326                                  struct r_scope_elem *scope,
 327                                  unsigned long rel_addr,
 328                                  unsigned long rel_size)
 329 {
 330         return _dl_parse(rpnt->dyn, scope, rel_addr, rel_size, _dl_do_reloc);
 331 }