| 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 <sys/tls.h> |
| 37 | |
| 38 | #include <machine/sysarch.h> |
| 39 | #include <machine/tls.h> |
| 40 | |
| 41 | #include <dlfcn.h> |
| 42 | #include <err.h> |
| 43 | #include <errno.h> |
| 44 | #include <fcntl.h> |
| 45 | #include <stdarg.h> |
| 46 | #include <stdio.h> |
| 47 | #include <stdlib.h> |
| 48 | #include <string.h> |
| 49 | #include <unistd.h> |
| 50 | |
| 51 | #include "debug.h" |
| 52 | #include "rtld.h" |
| 53 | |
| 54 | /* |
| 55 | * Process the special R_X86_64_COPY relocations in the main program. These |
| 56 | * copy data from a shared object into a region in the main program's BSS |
| 57 | * segment. |
| 58 | * |
| 59 | * Returns 0 on success, -1 on failure. |
| 60 | */ |
| 61 | int |
| 62 | do_copy_relocations(Obj_Entry *dstobj) |
| 63 | { |
| 64 | const Elf_Rela *relalim; |
| 65 | const Elf_Rela *rela; |
| 66 | |
| 67 | assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */ |
| 68 | |
| 69 | relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize); |
| 70 | for (rela = dstobj->rela; rela < relalim; rela++) { |
| 71 | if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) { |
| 72 | void *dstaddr; |
| 73 | const Elf_Sym *dstsym; |
| 74 | const char *name; |
| 75 | size_t size; |
| 76 | const void *srcaddr; |
| 77 | const Elf_Sym *srcsym; |
| 78 | const Obj_Entry *srcobj, *defobj; |
| 79 | SymLook req; |
| 80 | int res; |
| 81 | |
| 82 | dstaddr = (void *) (dstobj->relocbase + rela->r_offset); |
| 83 | dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); |
| 84 | name = dstobj->strtab + dstsym->st_name; |
| 85 | size = dstsym->st_size; |
| 86 | symlook_init(&req, name); |
| 87 | req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); |
| 88 | |
| 89 | for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) { |
| 90 | res = symlook_obj(&req, srcobj); |
| 91 | if (res == 0) { |
| 92 | srcsym = req.sym_out; |
| 93 | defobj = req.defobj_out; |
| 94 | break; |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | if (srcobj == NULL) { |
| 99 | _rtld_error("Undefined symbol \"%s\" referenced from COPY" |
| 100 | " relocation in %s", name, dstobj->path); |
| 101 | return -1; |
| 102 | } |
| 103 | |
| 104 | srcaddr = (const void *) (defobj->relocbase + srcsym->st_value); |
| 105 | memcpy(dstaddr, srcaddr, size); |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | return 0; |
| 110 | } |
| 111 | |
| 112 | /* Initialize the special GOT entries. */ |
| 113 | void |
| 114 | init_pltgot(Obj_Entry *obj) |
| 115 | { |
| 116 | if (obj->pltgot != NULL) { |
| 117 | obj->pltgot[1] = (Elf_Addr) obj; |
| 118 | obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; |
| 119 | } |
| 120 | } |
| 121 | |
| 122 | /* Process the non-PLT relocations. */ |
| 123 | int |
| 124 | reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, RtldLockState *lockstate) |
| 125 | { |
| 126 | const Elf_Rela *relalim; |
| 127 | const Elf_Rela *rela; |
| 128 | SymCache *cache; |
| 129 | int r = -1; |
| 130 | |
| 131 | /* |
| 132 | * The dynamic loader may be called from a thread, we have |
| 133 | * limited amounts of stack available so we cannot use alloca(). |
| 134 | */ |
| 135 | if (obj != obj_rtld) { |
| 136 | cache = calloc(obj->nchains, sizeof(SymCache)); |
| 137 | /* No need to check for NULL here */ |
| 138 | } else |
| 139 | cache = NULL; |
| 140 | |
| 141 | relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize); |
| 142 | for (rela = obj->rela; rela < relalim; rela++) { |
| 143 | Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset); |
| 144 | Elf32_Addr *where32 = (Elf32_Addr *)where; |
| 145 | |
| 146 | switch (ELF_R_TYPE(rela->r_info)) { |
| 147 | |
| 148 | case R_X86_64_NONE: |
| 149 | break; |
| 150 | |
| 151 | case R_X86_64_64: |
| 152 | { |
| 153 | const Elf_Sym *def; |
| 154 | const Obj_Entry *defobj; |
| 155 | |
| 156 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 157 | false, cache, lockstate); |
| 158 | if (def == NULL) |
| 159 | goto done; |
| 160 | |
| 161 | *where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend); |
| 162 | } |
| 163 | break; |
| 164 | |
| 165 | case R_X86_64_PC32: |
| 166 | /* |
| 167 | * I don't think the dynamic linker should ever see this |
| 168 | * type of relocation. But the binutils-2.6 tools sometimes |
| 169 | * generate it. |
| 170 | */ |
| 171 | { |
| 172 | const Elf_Sym *def; |
| 173 | const Obj_Entry *defobj; |
| 174 | |
| 175 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 176 | false, cache, lockstate); |
| 177 | if (def == NULL) |
| 178 | goto done; |
| 179 | |
| 180 | *where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase + |
| 181 | def->st_value + rela->r_addend - (Elf_Addr) where); |
| 182 | } |
| 183 | break; |
| 184 | /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */ |
| 185 | |
| 186 | case R_X86_64_COPY: |
| 187 | /* |
| 188 | * These are deferred until all other relocations have |
| 189 | * been done. All we do here is make sure that the COPY |
| 190 | * relocation is not in a shared library. They are allowed |
| 191 | * only in executable files. |
| 192 | */ |
| 193 | if (!obj->mainprog) { |
| 194 | _rtld_error("%s: Unexpected R_X86_64_COPY relocation" |
| 195 | " in shared library", obj->path); |
| 196 | goto done; |
| 197 | } |
| 198 | break; |
| 199 | |
| 200 | case R_X86_64_GLOB_DAT: |
| 201 | { |
| 202 | const Elf_Sym *def; |
| 203 | const Obj_Entry *defobj; |
| 204 | |
| 205 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 206 | false, cache, lockstate); |
| 207 | if (def == NULL) |
| 208 | goto done; |
| 209 | |
| 210 | *where = (Elf_Addr) (defobj->relocbase + def->st_value); |
| 211 | } |
| 212 | break; |
| 213 | |
| 214 | case R_X86_64_TPOFF64: |
| 215 | { |
| 216 | const Elf_Sym *def; |
| 217 | const Obj_Entry *defobj; |
| 218 | |
| 219 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 220 | false, cache, lockstate); |
| 221 | if (def == NULL) |
| 222 | goto done; |
| 223 | |
| 224 | /* |
| 225 | * We lazily allocate offsets for static TLS as we |
| 226 | * see the first relocation that references the |
| 227 | * TLS block. This allows us to support (small |
| 228 | * amounts of) static TLS in dynamically loaded |
| 229 | * modules. If we run out of space, we generate an |
| 230 | * error. |
| 231 | */ |
| 232 | if (!defobj->tls_done) { |
| 233 | if (!allocate_tls_offset((Obj_Entry*) defobj)) { |
| 234 | _rtld_error("%s: No space available for static " |
| 235 | "Thread Local Storage", obj->path); |
| 236 | goto done; |
| 237 | } |
| 238 | } |
| 239 | |
| 240 | *where = (Elf_Addr) (def->st_value - defobj->tlsoffset + |
| 241 | rela->r_addend); |
| 242 | } |
| 243 | break; |
| 244 | |
| 245 | case R_X86_64_TPOFF32: |
| 246 | { |
| 247 | const Elf_Sym *def; |
| 248 | const Obj_Entry *defobj; |
| 249 | |
| 250 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 251 | false, cache, lockstate); |
| 252 | if (def == NULL) |
| 253 | goto done; |
| 254 | |
| 255 | /* |
| 256 | * We lazily allocate offsets for static TLS as we |
| 257 | * see the first relocation that references the |
| 258 | * TLS block. This allows us to support (small |
| 259 | * amounts of) static TLS in dynamically loaded |
| 260 | * modules. If we run out of space, we generate an |
| 261 | * error. |
| 262 | */ |
| 263 | if (!defobj->tls_done) { |
| 264 | if (!allocate_tls_offset((Obj_Entry*) defobj)) { |
| 265 | _rtld_error("%s: No space available for static " |
| 266 | "Thread Local Storage", obj->path); |
| 267 | goto done; |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | *where32 = (Elf32_Addr) (def->st_value - |
| 272 | defobj->tlsoffset + |
| 273 | rela->r_addend); |
| 274 | } |
| 275 | break; |
| 276 | |
| 277 | case R_X86_64_DTPMOD64: |
| 278 | { |
| 279 | const Elf_Sym *def; |
| 280 | const Obj_Entry *defobj; |
| 281 | |
| 282 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 283 | false, cache, lockstate); |
| 284 | if (def == NULL) |
| 285 | goto done; |
| 286 | |
| 287 | *where += (Elf_Addr) defobj->tlsindex; |
| 288 | } |
| 289 | break; |
| 290 | |
| 291 | case R_X86_64_DTPOFF64: |
| 292 | { |
| 293 | const Elf_Sym *def; |
| 294 | const Obj_Entry *defobj; |
| 295 | |
| 296 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 297 | false, cache, lockstate); |
| 298 | if (def == NULL) |
| 299 | goto done; |
| 300 | |
| 301 | *where += (Elf_Addr) (def->st_value + rela->r_addend); |
| 302 | } |
| 303 | break; |
| 304 | |
| 305 | case R_X86_64_DTPOFF32: |
| 306 | { |
| 307 | const Elf_Sym *def; |
| 308 | const Obj_Entry *defobj; |
| 309 | |
| 310 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, |
| 311 | false, cache, lockstate); |
| 312 | if (def == NULL) |
| 313 | goto done; |
| 314 | |
| 315 | *where32 += (Elf32_Addr) (def->st_value + rela->r_addend); |
| 316 | } |
| 317 | break; |
| 318 | |
| 319 | case R_X86_64_RELATIVE: |
| 320 | *where = (Elf_Addr)(obj->relocbase + rela->r_addend); |
| 321 | break; |
| 322 | |
| 323 | /* 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 */ |
| 324 | |
| 325 | default: |
| 326 | _rtld_error("%s: Unsupported relocation type %u" |
| 327 | " in non-PLT relocations\n", obj->path, |
| 328 | (unsigned int)ELF_R_TYPE(rela->r_info)); |
| 329 | goto done; |
| 330 | } |
| 331 | } |
| 332 | r = 0; |
| 333 | done: |
| 334 | if (cache != NULL) |
| 335 | free(cache); |
| 336 | return(r); |
| 337 | } |
| 338 | |
| 339 | /* Process the PLT relocations. */ |
| 340 | int |
| 341 | reloc_plt(Obj_Entry *obj) |
| 342 | { |
| 343 | const Elf_Rela *relalim; |
| 344 | const Elf_Rela *rela; |
| 345 | |
| 346 | relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); |
| 347 | for (rela = obj->pltrela; rela < relalim; rela++) { |
| 348 | Elf_Addr *where; |
| 349 | |
| 350 | switch(ELF_R_TYPE(rela->r_info)) { |
| 351 | case R_X86_64_JMP_SLOT: |
| 352 | /* Relocate the GOT slot pointing into the PLT. */ |
| 353 | where = (Elf_Addr *)(obj->relocbase + rela->r_offset); |
| 354 | *where += (Elf_Addr)obj->relocbase; |
| 355 | break; |
| 356 | |
| 357 | default: |
| 358 | _rtld_error("Unknown relocation type %x in PLT", |
| 359 | (unsigned int)ELF_R_TYPE(rela->r_info)); |
| 360 | return (-1); |
| 361 | } |
| 362 | } |
| 363 | return 0; |
| 364 | } |
| 365 | |
| 366 | /* Relocate the jump slots in an object. */ |
| 367 | int |
| 368 | reloc_jmpslots(Obj_Entry *obj, RtldLockState *lockstate) |
| 369 | { |
| 370 | const Elf_Rela *relalim; |
| 371 | const Elf_Rela *rela; |
| 372 | |
| 373 | if (obj->jmpslots_done) |
| 374 | return 0; |
| 375 | relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); |
| 376 | for (rela = obj->pltrela; rela < relalim; rela++) { |
| 377 | Elf_Addr *where, target; |
| 378 | const Elf_Sym *def; |
| 379 | const Obj_Entry *defobj; |
| 380 | |
| 381 | switch (ELF_R_TYPE(rela->r_info)) { |
| 382 | case R_X86_64_JMP_SLOT: |
| 383 | where = (Elf_Addr *)(obj->relocbase + rela->r_offset); |
| 384 | def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL, |
| 385 | lockstate); |
| 386 | if (def == NULL) |
| 387 | return (-1); |
| 388 | target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); |
| 389 | reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela); |
| 390 | break; |
| 391 | |
| 392 | default: |
| 393 | _rtld_error("Unknown relocation type %x in PLT", |
| 394 | (unsigned int)ELF_R_TYPE(rela->r_info)); |
| 395 | return (-1); |
| 396 | } |
| 397 | } |
| 398 | obj->jmpslots_done = true; |
| 399 | return 0; |
| 400 | } |
| 401 | |
| 402 | void *__tls_get_addr(tls_index *ti) |
| 403 | { |
| 404 | struct tls_tcb *tcb; |
| 405 | |
| 406 | tcb = tls_get_tcb(); |
| 407 | return tls_get_addr_common((Elf_Addr **)&tcb->tcb_dtv, ti->ti_module, ti->ti_offset); |
| 408 | } |
| 409 | |
| 410 | void * |
| 411 | __tls_get_addr_tcb(struct tls_tcb *tcb, tls_index *ti) |
| 412 | { |
| 413 | return tls_get_addr_common((Elf_Addr **)&tcb->tcb_dtv, ti->ti_module, ti->ti_offset); |
| 414 | } |