1 /* $NetBSD: mdreloc.c,v 1.50 2025/04/16 18:10:46 riastradh Exp $ */ 2 3 /* 4 * Copyright (c) 2001 Wasabi Systems, Inc. 5 * All rights reserved. 6 * 7 * Written by Frank van der Linden for Wasabi Systems, Inc. 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. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed for the NetBSD Project by 20 * Wasabi Systems, Inc. 21 * 4. The name of Wasabi Systems, Inc. may not be used to endorse 22 * or promote products derived from this software without specific prior 23 * written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC 29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35 * POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 /* 39 * Copyright 1996 John D. Polstra. 40 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 41 * All rights reserved. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. All advertising materials mentioning features or use of this software 52 * must display the following acknowledgement: 53 * This product includes software developed by John Polstra. 54 * 4. The name of the author may not be used to endorse or promote products 55 * derived from this software without specific prior written permission. 56 * 57 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 58 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 59 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 60 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 61 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 62 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 63 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 64 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 65 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 66 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 67 */ 68 69 /* 70 * amd64 ELF relocations. 71 * 72 * References: 73 * 74 * [AMD64psABI] System V Application Binary Interface: AMD64 75 * Architecture Processor Supplement, Draft Version 0.99.6, 76 * 2013-10-07. 77 * https://web.archive.org/web/20160801075146/http://www.x86-64.org/documentation/abi.pdf 78 * Source code: https://gitlab.com/x86-psABIs/x86-64-ABI 79 */ 80 81 #include <sys/cdefs.h> 82 #ifndef lint 83 __RCSID("$NetBSD: mdreloc.c,v 1.50 2025/04/16 18:10:46 riastradh Exp $"); 84 #endif /* not lint */ 85 86 #include <sys/types.h> 87 #include <sys/mman.h> 88 #include <errno.h> 89 #include <fcntl.h> 90 #include <stdarg.h> 91 #include <stdio.h> 92 #include <stdlib.h> 93 #include <string.h> 94 #include <unistd.h> 95 #include <elf.h> 96 97 #include "debug.h" 98 #include "rtld.h" 99 100 void _rtld_bind_start(void); 101 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 102 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 103 static inline int _rtld_relocate_plt_object(const Obj_Entry *, 104 const Elf_Rela *, Elf_Addr *); 105 106 #define rdbg_symname(obj, rela) \ 107 ((obj)->strtab + (obj)->symtab[ELF_R_SYM((rela)->r_info)].st_name) 108 109 void 110 _rtld_setup_pltgot(const Obj_Entry *obj) 111 { 112 obj->pltgot[1] = (Elf_Addr) obj; 113 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 114 } 115 116 void 117 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 118 { 119 const Elf_Rela *rela = 0, *relalim; 120 Elf_Addr relasz = 0; 121 Elf_Addr *where; 122 123 for (; dynp->d_tag != DT_NULL; dynp++) { 124 switch (dynp->d_tag) { 125 case DT_RELA: 126 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 127 break; 128 case DT_RELASZ: 129 relasz = dynp->d_un.d_val; 130 break; 131 } 132 } 133 /* 134 * Assume only 64-bit relocations here, which should always 135 * be true for the dynamic linker. 136 */ 137 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 138 for (; rela < relalim; rela++) { 139 where = (Elf_Addr *)(relocbase + rela->r_offset); 140 *where = (Elf_Addr)(relocbase + rela->r_addend); 141 } 142 } 143 144 int 145 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 146 { 147 const Elf_Rela *rela; 148 const Elf_Sym *def = NULL; 149 const Obj_Entry *defobj = NULL; 150 unsigned long last_symnum = ULONG_MAX; 151 152 for (rela = obj->rela; rela < obj->relalim; rela++) { 153 Elf64_Addr *where64; 154 Elf32_Addr *where32; 155 Elf64_Addr tmp64; 156 Elf32_Addr tmp32; 157 unsigned long symnum; 158 159 where64 = (Elf64_Addr *)(obj->relocbase + rela->r_offset); 160 where32 = (Elf32_Addr *)where64; 161 162 switch (ELF_R_TYPE(rela->r_info)) { 163 case R_TYPE(32): /* word32 S + A, truncate */ 164 case R_TYPE(32S): /* word32 S + A, signed truncate */ 165 case R_TYPE(GOT32): /* word32 G + A (XXX can we see these?) */ 166 case R_TYPE(64): /* word64 S + A */ 167 case R_TYPE(PC32): /* word32 S + A - P */ 168 case R_TYPE(GLOB_DAT): /* word64 S */ 169 case R_TYPE(TPOFF64): 170 case R_TYPE(DTPMOD64): 171 case R_TYPE(DTPOFF64): 172 symnum = ELF_R_SYM(rela->r_info); 173 if (last_symnum != symnum) { 174 last_symnum = symnum; 175 def = _rtld_find_symdef(symnum, obj, &defobj, 176 false); 177 if (def == NULL) 178 return -1; 179 } 180 break; 181 default: 182 break; 183 } 184 185 switch (ELF_R_TYPE(rela->r_info)) { 186 case R_TYPE(NONE): 187 break; 188 189 case R_TYPE(32): /* word32 S + A, truncate */ 190 case R_TYPE(32S): /* word32 S + A, signed truncate */ 191 case R_TYPE(GOT32): /* word32 G + A (XXX can we see these?) */ 192 tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + 193 def->st_value + rela->r_addend); 194 195 if (*where32 != tmp32) 196 *where32 = tmp32; 197 rdbg(("32/32S %s in %s --> %p in %s", 198 rdbg_symname(obj, rela), 199 obj->path, (void *)(uintptr_t)*where32, 200 defobj->path)); 201 break; 202 case R_TYPE(64): /* word64 S + A */ 203 tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value + 204 rela->r_addend); 205 206 if (*where64 != tmp64) 207 *where64 = tmp64; 208 rdbg(("64 %s in %s --> %p in %s", 209 rdbg_symname(obj, rela), 210 obj->path, (void *)*where64, defobj->path)); 211 break; 212 case R_TYPE(PC32): /* word32 S + A - P */ 213 tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + 214 def->st_value + rela->r_addend - 215 (Elf64_Addr)where64); 216 if (*where32 != tmp32) 217 *where32 = tmp32; 218 rdbg(("PC32 %s in %s --> %p in %s", 219 rdbg_symname(obj, rela), 220 obj->path, (void *)(unsigned long)*where32, 221 defobj->path)); 222 break; 223 case R_TYPE(GLOB_DAT): /* word64 S */ 224 tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value); 225 226 if (*where64 != tmp64) 227 *where64 = tmp64; 228 rdbg(("64 %s in %s --> %p in %s", 229 rdbg_symname(obj, rela), 230 obj->path, (void *)*where64, defobj->path)); 231 break; 232 case R_TYPE(RELATIVE): /* word64 B + A */ 233 tmp64 = (Elf64_Addr)(obj->relocbase + rela->r_addend); 234 if (*where64 != tmp64) 235 *where64 = tmp64; 236 rdbg(("RELATIVE in %s --> %p", obj->path, 237 (void *)*where64)); 238 break; 239 240 case R_TYPE(TPOFF64): 241 if (!defobj->tls_static && 242 _rtld_tls_offset_allocate(__UNCONST(defobj))) 243 return -1; 244 245 *where64 = (Elf64_Addr)(def->st_value - 246 defobj->tlsoffset + rela->r_addend); 247 248 rdbg(("TPOFF64 %s in %s --> %p", 249 rdbg_symname(obj, rela), 250 obj->path, (void *)*where64)); 251 252 break; 253 254 case R_TYPE(DTPMOD64): 255 *where64 = (Elf64_Addr)defobj->tlsindex; 256 257 rdbg(("DTPMOD64 %s in %s --> %p", 258 rdbg_symname(obj, rela), 259 obj->path, (void *)*where64)); 260 261 break; 262 263 case R_TYPE(DTPOFF64): 264 *where64 = (Elf64_Addr)(def->st_value + rela->r_addend); 265 266 rdbg(("DTPOFF64 %s in %s --> %p", 267 rdbg_symname(obj, rela), 268 obj->path, (void *)*where64)); 269 270 break; 271 272 case R_TYPE(COPY): 273 rdbg(("COPY")); 274 break; 275 276 case R_TYPE(IRELATIVE): 277 /* IFUNC relocations are handled in _rtld_call_ifunc */ 278 if (obj->ifunc_remaining_nonplt == 0) { 279 obj->ifunc_remaining_nonplt = 280 obj->relalim - rela; 281 } 282 break; 283 284 default: 285 rdbg(("sym = %lu, type = %lu, offset = %p, " 286 "addend = %p, contents = %p, symbol = %s", 287 (u_long)ELF_R_SYM(rela->r_info), 288 (u_long)ELF_R_TYPE(rela->r_info), 289 (void *)rela->r_offset, (void *)rela->r_addend, 290 (void *)*where64, rdbg_symname(obj, rela))); 291 _rtld_error("%s: Unsupported relocation type %ld " 292 "in non-PLT relocations", 293 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 294 return -1; 295 } 296 } 297 return 0; 298 } 299 300 int 301 _rtld_relocate_plt_lazy(Obj_Entry *obj) 302 { 303 const Elf_Rela *rela; 304 305 for (rela = obj->pltrelalim; rela-- > obj->pltrela; ) { 306 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 307 308 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT) || 309 ELF_R_TYPE(rela->r_info) == R_TYPE(IRELATIVE)); 310 311 if (ELF_R_TYPE(rela->r_info) == R_TYPE(IRELATIVE)) 312 obj->ifunc_remaining = obj->pltrelalim - rela; 313 314 /* Just relocate the GOT slots pointing into the PLT */ 315 *where += (Elf_Addr)obj->relocbase; 316 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 317 } 318 319 return 0; 320 } 321 322 static inline int 323 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) 324 { 325 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 326 Elf_Addr new_value; 327 const Elf_Sym *def; 328 const Obj_Entry *defobj; 329 unsigned long info = rela->r_info; 330 331 if (ELF_R_TYPE(info) == R_TYPE(IRELATIVE)) 332 return 0; 333 334 assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT)); 335 336 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 337 if (__predict_false(def == NULL)) 338 return -1; 339 if (__predict_false(def == &_rtld_sym_zero)) 340 return 0; 341 342 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 343 if (tp == NULL) 344 return 0; 345 new_value = _rtld_resolve_ifunc(defobj, def); 346 } else { 347 new_value = (Elf_Addr)(defobj->relocbase + def->st_value + 348 rela->r_addend); 349 } 350 351 rdbg(("bind now/fixup in %s --> old=%p new=%p", 352 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 353 if (*where != new_value) 354 *where = new_value; 355 356 if (tp) 357 *tp = new_value - rela->r_addend; 358 359 return 0; 360 } 361 362 caddr_t 363 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 364 { 365 const Elf_Rela *rela = obj->pltrela + reloff; 366 Elf_Addr new_value; 367 int error; 368 369 new_value = 0; /* XXX GCC4 */ 370 371 _rtld_shared_enter(); 372 error = _rtld_relocate_plt_object(obj, rela, &new_value); 373 if (error) 374 _rtld_die(); 375 _rtld_shared_exit(); 376 377 return (caddr_t)new_value; 378 } 379 380 int 381 _rtld_relocate_plt_objects(const Obj_Entry *obj) 382 { 383 const Elf_Rela *rela; 384 385 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) 386 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 387 return -1; 388 389 return 0; 390 } 391
Indexes created Tue Sep 30 17:09:57 GMT 2025