1 /*- 2 * Copyright (c) 2015-2017 Ruslan Bukin <br@bsdpad.com> 3 * All rights reserved. 4 * 5 * This software was developed by SRI International and the University of 6 * Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237 7 * ("CTSRD"), as part of the DARPA CRASH research programme. 8 * 9 * This software was developed by the University of Cambridge Computer 10 * Laboratory as part of the CTSRD Project, with support from the UK Higher 11 * Education Innovation Fund (HEIF). 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/types.h> 36 37 #include <stdlib.h> 38 39 #include "debug.h" 40 #include "rtld.h" 41 #include "rtld_printf.h" 42 43 /* 44 * It is possible for the compiler to emit relocations for unaligned data. 45 * We handle this situation with these inlines. 46 */ 47 #define RELOC_ALIGNED_P(x) \ 48 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 49 50 uint64_t 51 set_gp(Obj_Entry *obj) 52 { 53 uint64_t old; 54 SymLook req; 55 uint64_t gp; 56 int res; 57 58 __asm __volatile("mv %0, gp" : "=r"(old)); 59 60 symlook_init(&req, "__global_pointer$"); 61 req.ventry = NULL; 62 req.flags = SYMLOOK_EARLY; 63 res = symlook_obj(&req, obj); 64 65 if (res == 0) { 66 gp = req.sym_out->st_value; 67 __asm __volatile("mv gp, %0" :: "r"(gp)); 68 } 69 70 return (old); 71 } 72 73 void 74 init_pltgot(Obj_Entry *obj) 75 { 76 77 if (obj->pltgot != NULL) { 78 obj->pltgot[0] = (Elf_Addr)&_rtld_bind_start; 79 obj->pltgot[1] = (Elf_Addr)obj; 80 } 81 } 82 83 int 84 do_copy_relocations(Obj_Entry *dstobj) 85 { 86 const Obj_Entry *srcobj, *defobj; 87 const Elf_Rela *relalim; 88 const Elf_Rela *rela; 89 const Elf_Sym *srcsym; 90 const Elf_Sym *dstsym; 91 const void *srcaddr; 92 const char *name; 93 void *dstaddr; 94 SymLook req; 95 size_t size; 96 int res; 97 98 /* 99 * COPY relocs are invalid outside of the main program 100 */ 101 assert(dstobj->mainprog); 102 103 relalim = (const Elf_Rela *)((const char *)dstobj->rela + 104 dstobj->relasize); 105 for (rela = dstobj->rela; rela < relalim; rela++) { 106 if (ELF_R_TYPE(rela->r_info) != R_RISCV_COPY) 107 continue; 108 109 dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 110 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 111 name = dstobj->strtab + dstsym->st_name; 112 size = dstsym->st_size; 113 114 symlook_init(&req, name); 115 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); 116 req.flags = SYMLOOK_EARLY; 117 118 for (srcobj = globallist_next(dstobj); srcobj != NULL; 119 srcobj = globallist_next(srcobj)) { 120 res = symlook_obj(&req, srcobj); 121 if (res == 0) { 122 srcsym = req.sym_out; 123 defobj = req.defobj_out; 124 break; 125 } 126 } 127 if (srcobj == NULL) { 128 _rtld_error( 129 "Undefined symbol \"%s\" referenced from COPY relocation in %s", 130 name, dstobj->path); 131 return (-1); 132 } 133 134 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value); 135 memcpy(dstaddr, srcaddr, size); 136 } 137 138 return (0); 139 } 140 141 /* 142 * Process the PLT relocations. 143 */ 144 int 145 reloc_plt(Obj_Entry *obj, int flags __unused, RtldLockState *lockstate __unused) 146 { 147 const Elf_Rela *relalim; 148 const Elf_Rela *rela; 149 150 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 151 obj->pltrelasize); 152 for (rela = obj->pltrela; rela < relalim; rela++) { 153 Elf_Addr *where; 154 155 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 156 157 switch (ELF_R_TYPE(rela->r_info)) { 158 case R_RISCV_JUMP_SLOT: 159 *where += (Elf_Addr)obj->relocbase; 160 break; 161 case R_RISCV_IRELATIVE: 162 obj->irelative = true; 163 break; 164 default: 165 _rtld_error("Unknown relocation type %u in PLT", 166 (unsigned int)ELF_R_TYPE(rela->r_info)); 167 return (-1); 168 } 169 } 170 171 return (0); 172 } 173 174 /* 175 * LD_BIND_NOW was set - force relocation for all jump slots 176 */ 177 int 178 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) 179 { 180 const Obj_Entry *defobj; 181 const Elf_Rela *relalim; 182 const Elf_Rela *rela; 183 const Elf_Sym *def; 184 185 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 186 obj->pltrelasize); 187 for (rela = obj->pltrela; rela < relalim; rela++) { 188 Elf_Addr *where; 189 190 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 191 switch(ELF_R_TYPE(rela->r_info)) { 192 case R_RISCV_JUMP_SLOT: 193 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 194 &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); 195 if (def == NULL) { 196 dbg("reloc_jmpslots: sym not found"); 197 return (-1); 198 } 199 200 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 201 obj->gnu_ifunc = true; 202 continue; 203 } 204 205 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 206 break; 207 default: 208 _rtld_error("Unknown relocation type %x in jmpslot", 209 (unsigned int)ELF_R_TYPE(rela->r_info)); 210 return (-1); 211 } 212 } 213 214 return (0); 215 } 216 217 static void 218 reloc_iresolve_one(Obj_Entry *obj, const Elf_Rela *rela, 219 RtldLockState *lockstate) 220 { 221 Elf_Addr *where, target, *ptr; 222 223 ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend); 224 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 225 lock_release(rtld_bind_lock, lockstate); 226 target = call_ifunc_resolver(ptr); 227 wlock_acquire(rtld_bind_lock, lockstate); 228 *where = target; 229 } 230 231 int 232 reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 233 { 234 const Elf_Rela *relalim; 235 const Elf_Rela *rela; 236 237 if (!obj->irelative) 238 return (0); 239 240 obj->irelative = false; 241 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 242 obj->pltrelasize); 243 for (rela = obj->pltrela; rela < relalim; rela++) { 244 if (ELF_R_TYPE(rela->r_info) == R_RISCV_IRELATIVE) 245 reloc_iresolve_one(obj, rela, lockstate); 246 } 247 return (0); 248 } 249 250 int 251 reloc_iresolve_nonplt(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 252 { 253 const Elf_Rela *relalim; 254 const Elf_Rela *rela; 255 256 if (!obj->irelative_nonplt) 257 return (0); 258 259 obj->irelative_nonplt = false; 260 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 261 for (rela = obj->rela; rela < relalim; rela++) { 262 if (ELF_R_TYPE(rela->r_info) == R_RISCV_IRELATIVE) 263 reloc_iresolve_one(obj, rela, lockstate); 264 } 265 return (0); 266 } 267 268 int 269 reloc_gnu_ifunc(Obj_Entry *obj, int flags, 270 struct Struct_RtldLockState *lockstate) 271 { 272 const Elf_Rela *relalim; 273 const Elf_Rela *rela; 274 Elf_Addr *where, target; 275 const Elf_Sym *def; 276 const Obj_Entry *defobj; 277 278 if (!obj->gnu_ifunc) 279 return (0); 280 281 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 282 for (rela = obj->pltrela; rela < relalim; rela++) { 283 if (ELF_R_TYPE(rela->r_info) == R_RISCV_JUMP_SLOT) { 284 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 285 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 286 SYMLOOK_IN_PLT | flags, NULL, lockstate); 287 if (def == NULL) 288 return (-1); 289 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC) 290 continue; 291 292 lock_release(rtld_bind_lock, lockstate); 293 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); 294 wlock_acquire(rtld_bind_lock, lockstate); 295 reloc_jmpslot(where, target, defobj, obj, 296 (const Elf_Rel *)rela); 297 } 298 } 299 obj->gnu_ifunc = false; 300 return (0); 301 } 302 303 Elf_Addr 304 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, 305 const Obj_Entry *defobj __unused, const Obj_Entry *obj __unused, 306 const Elf_Rel *rel) 307 { 308 309 assert(ELF_R_TYPE(rel->r_info) == R_RISCV_JUMP_SLOT || 310 ELF_R_TYPE(rel->r_info) == R_RISCV_IRELATIVE); 311 312 if (*where != target && !ld_bind_not) 313 *where = target; 314 return (target); 315 } 316 317 /* 318 * Process non-PLT relocations 319 */ 320 int 321 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, 322 RtldLockState *lockstate) 323 { 324 const Obj_Entry *defobj; 325 const Elf_Rela *relalim; 326 const Elf_Rela *rela; 327 const Elf_Sym *def; 328 SymCache *cache; 329 Elf_Addr *where, symval; 330 unsigned long symnum; 331 332 /* 333 * The dynamic loader may be called from a thread, we have 334 * limited amounts of stack available so we cannot use alloca(). 335 */ 336 if (obj == obj_rtld) 337 cache = NULL; 338 else 339 cache = calloc(obj->dynsymcount, sizeof(SymCache)); 340 /* No need to check for NULL here */ 341 342 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 343 for (rela = obj->rela; rela < relalim; rela++) { 344 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 345 symnum = ELF_R_SYM(rela->r_info); 346 347 switch (ELF_R_TYPE(rela->r_info)) { 348 case R_RISCV_JUMP_SLOT: 349 /* This will be handled by the plt/jmpslot routines */ 350 break; 351 case R_RISCV_NONE: 352 break; 353 case R_RISCV_64: 354 def = find_symdef(symnum, obj, &defobj, flags, cache, 355 lockstate); 356 if (def == NULL) 357 return (-1); 358 359 /* 360 * If symbol is IFUNC, only perform relocation 361 * when caller allowed it by passing 362 * SYMLOOK_IFUNC flag. Skip the relocations 363 * otherwise. 364 */ 365 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 366 if ((flags & SYMLOOK_IFUNC) == 0) { 367 obj->non_plt_gnu_ifunc = true; 368 continue; 369 } 370 symval = (Elf_Addr)rtld_resolve_ifunc(defobj, 371 def); 372 } else { 373 if ((flags & SYMLOOK_IFUNC) != 0) 374 continue; 375 symval = (Elf_Addr)(defobj->relocbase + 376 def->st_value); 377 } 378 379 *where = symval + rela->r_addend; 380 break; 381 case R_RISCV_TLS_DTPMOD64: 382 def = find_symdef(symnum, obj, &defobj, flags, cache, 383 lockstate); 384 if (def == NULL) 385 return -1; 386 387 *where += (Elf_Addr)defobj->tlsindex; 388 break; 389 case R_RISCV_COPY: 390 /* 391 * These are deferred until all other relocations have 392 * been done. All we do here is make sure that the 393 * COPY relocation is not in a shared library. They 394 * are allowed only in executable files. 395 */ 396 if (!obj->mainprog) { 397 _rtld_error("%s: Unexpected R_RISCV_COPY " 398 "relocation in shared library", obj->path); 399 return (-1); 400 } 401 break; 402 case R_RISCV_TLS_DTPREL64: 403 def = find_symdef(symnum, obj, &defobj, flags, cache, 404 lockstate); 405 if (def == NULL) 406 return (-1); 407 /* 408 * We lazily allocate offsets for static TLS as we 409 * see the first relocation that references the 410 * TLS block. This allows us to support (small 411 * amounts of) static TLS in dynamically loaded 412 * modules. If we run out of space, we generate an 413 * error. 414 */ 415 if (!defobj->tls_static) { 416 if (!allocate_tls_offset( 417 __DECONST(Obj_Entry *, defobj))) { 418 _rtld_error( 419 "%s: No space available for static " 420 "Thread Local Storage", obj->path); 421 return (-1); 422 } 423 } 424 425 *where += (Elf_Addr)(def->st_value + rela->r_addend 426 - TLS_DTV_OFFSET); 427 break; 428 case R_RISCV_TLS_TPREL64: 429 def = find_symdef(symnum, obj, &defobj, flags, cache, 430 lockstate); 431 if (def == NULL) 432 return (-1); 433 434 /* 435 * We lazily allocate offsets for static TLS as we 436 * see the first relocation that references the 437 * TLS block. This allows us to support (small 438 * amounts of) static TLS in dynamically loaded 439 * modules. If we run out of space, we generate an 440 * error. 441 */ 442 if (!defobj->tls_static) { 443 if (!allocate_tls_offset( 444 __DECONST(Obj_Entry *, defobj))) { 445 _rtld_error( 446 "%s: No space available for static " 447 "Thread Local Storage", obj->path); 448 return (-1); 449 } 450 } 451 452 *where = (def->st_value + rela->r_addend + 453 defobj->tlsoffset - TLS_TP_OFFSET - TLS_TCB_SIZE); 454 break; 455 case R_RISCV_RELATIVE: 456 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 457 break; 458 case R_RISCV_IRELATIVE: 459 obj->irelative_nonplt = true; 460 break; 461 default: 462 rtld_printf("%s: Unhandled relocation %lu\n", 463 obj->path, ELF_R_TYPE(rela->r_info)); 464 return (-1); 465 } 466 } 467 468 return (0); 469 } 470 471 unsigned long elf_hwcap; 472 473 void 474 ifunc_init(Elf_Auxinfo *aux_info[__min_size(AT_COUNT)]) 475 { 476 if (aux_info[AT_HWCAP] != NULL) 477 elf_hwcap = aux_info[AT_HWCAP]->a_un.a_val; 478 } 479 480 void 481 allocate_initial_tls(Obj_Entry *objs) 482 { 483 484 /* 485 * Fix the size of the static TLS block by using the maximum 486 * offset allocated so far and adding a bit for dynamic modules to 487 * use. 488 */ 489 tls_static_space = tls_last_offset + tls_last_size + 490 ld_static_tls_extra; 491 492 _tcb_set(allocate_tls(objs, NULL, TLS_TCB_SIZE, TLS_TCB_ALIGN)); 493 } 494 495 void * 496 __tls_get_addr(tls_index* ti) 497 { 498 uintptr_t **dtvp; 499 void *p; 500 501 dtvp = &_tcb_get()->tcb_dtv; 502 p = tls_get_addr_common(dtvp, ti->ti_module, ti->ti_offset); 503 504 return ((char*)p + TLS_DTV_OFFSET); 505 } 506