1 /*- 2 * Copyright 1996, 1997, 1998, 1999 John D. Polstra. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 * 25 * $FreeBSD$ 26 */ 27 28 /* 29 * Dynamic linker for ELF. 30 * 31 * John Polstra <jdp@polstra.com>. 32 */ 33 34 #include <sys/param.h> 35 #include <sys/mman.h> 36 #include <machine/sysarch.h> 37 38 #include <dlfcn.h> 39 #include <err.h> 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <stdarg.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 48 #include "debug.h" 49 #include "rtld.h" 50 51 /* 52 * Process the special R_X86_64_COPY relocations in the main program. These 53 * copy data from a shared object into a region in the main program's BSS 54 * segment. 55 * 56 * Returns 0 on success, -1 on failure. 57 */ 58 int 59 do_copy_relocations(Obj_Entry *dstobj) 60 { 61 const Elf_Rela *relalim; 62 const Elf_Rela *rela; 63 64 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */ 65 66 relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize); 67 for (rela = dstobj->rela; rela < relalim; rela++) { 68 if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) { 69 void *dstaddr; 70 const Elf_Sym *dstsym; 71 const char *name; 72 unsigned long hash; 73 size_t size; 74 const void *srcaddr; 75 const Elf_Sym *srcsym; 76 Obj_Entry *srcobj; 77 const Ver_Entry *ve; 78 79 dstaddr = (void *) (dstobj->relocbase + rela->r_offset); 80 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 81 name = dstobj->strtab + dstsym->st_name; 82 hash = elf_hash(name); 83 size = dstsym->st_size; 84 ve = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); 85 86 for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) 87 if ((srcsym = symlook_obj(name, hash, srcobj, ve, 0)) != NULL) 88 break; 89 90 if (srcobj == NULL) { 91 _rtld_error("Undefined symbol \"%s\" referenced from COPY" 92 " relocation in %s", name, dstobj->path); 93 return -1; 94 } 95 96 srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value); 97 memcpy(dstaddr, srcaddr, size); 98 } 99 } 100 101 return 0; 102 } 103 104 /* Initialize the special GOT entries. */ 105 void 106 init_pltgot(Obj_Entry *obj) 107 { 108 if (obj->pltgot != NULL) { 109 obj->pltgot[1] = (Elf_Addr) obj; 110 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 111 } 112 } 113 114 /* Process the non-PLT relocations. */ 115 int 116 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld) 117 { 118 const Elf_Rela *relalim; 119 const Elf_Rela *rela; 120 SymCache *cache; 121 int bytes = obj->nchains * sizeof(SymCache); 122 int r = -1; 123 124 /* 125 * The dynamic loader may be called from a thread, we have 126 * limited amounts of stack available so we cannot use alloca(). 127 */ 128 cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0); 129 if (cache == MAP_FAILED) 130 cache = NULL; 131 132 relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize); 133 for (rela = obj->rela; rela < relalim; rela++) { 134 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 135 Elf32_Addr *where32 = (Elf32_Addr *)where; 136 137 switch (ELF_R_TYPE(rela->r_info)) { 138 139 case R_X86_64_NONE: 140 break; 141 142 case R_X86_64_64: 143 { 144 const Elf_Sym *def; 145 const Obj_Entry *defobj; 146 147 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 148 false, cache); 149 if (def == NULL) 150 goto done; 151 152 *where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend); 153 } 154 break; 155 156 case R_X86_64_PC32: 157 /* 158 * I don't think the dynamic linker should ever see this 159 * type of relocation. But the binutils-2.6 tools sometimes 160 * generate it. 161 */ 162 { 163 const Elf_Sym *def; 164 const Obj_Entry *defobj; 165 166 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 167 false, cache); 168 if (def == NULL) 169 goto done; 170 171 *where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase + 172 def->st_value + rela->r_addend - (Elf_Addr) where); 173 } 174 break; 175 /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */ 176 177 case R_X86_64_COPY: 178 /* 179 * These are deferred until all other relocations have 180 * been done. All we do here is make sure that the COPY 181 * relocation is not in a shared library. They are allowed 182 * only in executable files. 183 */ 184 if (!obj->mainprog) { 185 _rtld_error("%s: Unexpected R_X86_64_COPY relocation" 186 " in shared library", obj->path); 187 goto done; 188 } 189 break; 190 191 case R_X86_64_GLOB_DAT: 192 { 193 const Elf_Sym *def; 194 const Obj_Entry *defobj; 195 196 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 197 false, cache); 198 if (def == NULL) 199 goto done; 200 201 *where = (Elf_Addr) (defobj->relocbase + def->st_value); 202 } 203 break; 204 205 case R_X86_64_TPOFF64: 206 { 207 const Elf_Sym *def; 208 const Obj_Entry *defobj; 209 210 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 211 false, cache); 212 if (def == NULL) 213 goto done; 214 215 /* 216 * We lazily allocate offsets for static TLS as we 217 * see the first relocation that references the 218 * TLS block. This allows us to support (small 219 * amounts of) static TLS in dynamically loaded 220 * modules. If we run out of space, we generate an 221 * error. 222 */ 223 if (!defobj->tls_done) { 224 if (!allocate_tls_offset((Obj_Entry*) defobj)) { 225 _rtld_error("%s: No space available for static " 226 "Thread Local Storage", obj->path); 227 goto done; 228 } 229 } 230 231 *where = (Elf_Addr) (def->st_value - defobj->tlsoffset + 232 rela->r_addend); 233 } 234 break; 235 236 case R_X86_64_TPOFF32: 237 { 238 const Elf_Sym *def; 239 const Obj_Entry *defobj; 240 241 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 242 false, cache); 243 if (def == NULL) 244 goto done; 245 246 /* 247 * We lazily allocate offsets for static TLS as we 248 * see the first relocation that references the 249 * TLS block. This allows us to support (small 250 * amounts of) static TLS in dynamically loaded 251 * modules. If we run out of space, we generate an 252 * error. 253 */ 254 if (!defobj->tls_done) { 255 if (!allocate_tls_offset((Obj_Entry*) defobj)) { 256 _rtld_error("%s: No space available for static " 257 "Thread Local Storage", obj->path); 258 goto done; 259 } 260 } 261 262 *where32 = (Elf32_Addr) (def->st_value - 263 defobj->tlsoffset + 264 rela->r_addend); 265 } 266 break; 267 268 case R_X86_64_DTPMOD64: 269 { 270 const Elf_Sym *def; 271 const Obj_Entry *defobj; 272 273 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 274 false, cache); 275 if (def == NULL) 276 goto done; 277 278 *where += (Elf_Addr) defobj->tlsindex; 279 } 280 break; 281 282 case R_X86_64_DTPOFF64: 283 { 284 const Elf_Sym *def; 285 const Obj_Entry *defobj; 286 287 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 288 false, cache); 289 if (def == NULL) 290 goto done; 291 292 *where += (Elf_Addr) (def->st_value + rela->r_addend); 293 } 294 break; 295 296 case R_X86_64_DTPOFF32: 297 { 298 const Elf_Sym *def; 299 const Obj_Entry *defobj; 300 301 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 302 false, cache); 303 if (def == NULL) 304 goto done; 305 306 *where32 += (Elf32_Addr) (def->st_value + rela->r_addend); 307 } 308 break; 309 310 case R_X86_64_RELATIVE: 311 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 312 break; 313 314 /* missing: R_X86_64_GOTPCREL, R_X86_64_32, R_X86_64_32S, R_X86_64_16, R_X86_64_PC16, R_X86_64_8, R_X86_64_PC8 */ 315 316 default: 317 _rtld_error("%s: Unsupported relocation type %u" 318 " in non-PLT relocations\n", obj->path, 319 (unsigned int)ELF_R_TYPE(rela->r_info)); 320 goto done; 321 } 322 } 323 r = 0; 324 done: 325 if (cache) 326 munmap(cache, bytes); 327 return(r); 328 } 329 330 /* Process the PLT relocations. */ 331 int 332 reloc_plt(Obj_Entry *obj) 333 { 334 const Elf_Rela *relalim; 335 const Elf_Rela *rela; 336 337 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); 338 for (rela = obj->pltrela; rela < relalim; rela++) { 339 Elf_Addr *where; 340 341 assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT); 342 343 /* Relocate the GOT slot pointing into the PLT. */ 344 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 345 *where += (Elf_Addr)obj->relocbase; 346 } 347 return 0; 348 } 349 350 /* Relocate the jump slots in an object. */ 351 int 352 reloc_jmpslots(Obj_Entry *obj) 353 { 354 const Elf_Rela *relalim; 355 const Elf_Rela *rela; 356 357 if (obj->jmpslots_done) 358 return 0; 359 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); 360 for (rela = obj->pltrela; rela < relalim; rela++) { 361 Elf_Addr *where, target; 362 const Elf_Sym *def; 363 const Obj_Entry *defobj; 364 365 assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT); 366 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 367 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL); 368 if (def == NULL) 369 return -1; 370 target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); 371 reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela); 372 } 373 obj->jmpslots_done = true; 374 return 0; 375 } 376 377 void 378 allocate_initial_tls(Obj_Entry *objs) 379 { 380 /* 381 * Fix the size of the static TLS block by using the maximum 382 * offset allocated so far and adding a bit for dynamic modules to 383 * use. 384 */ 385 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA; 386 amd64_set_fsbase(allocate_tls(objs, 0, 387 3*sizeof(Elf_Addr), sizeof(Elf_Addr))); 388 } 389 390 void *__tls_get_addr(tls_index *ti) 391 { 392 Elf_Addr** segbase; 393 Elf_Addr* dtv; 394 395 __asm __volatile("movq %%fs:0, %0" : "=r" (segbase)); 396 dtv = segbase[1]; 397 398 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset); 399 } 400