headers.c revision 1.57
1 /* $NetBSD: headers.c,v 1.57 2014/08/26 12:14:14 joerg Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 6 * Copyright 2002 Charles M. Hannum <root (at) ihack.net> 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. 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 by John Polstra. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 /* 36 * Dynamic linker for ELF. 37 * 38 * John Polstra <jdp (at) polstra.com>. 39 */ 40 41 #include <sys/cdefs.h> 42 #ifndef lint 43 __RCSID("$NetBSD: headers.c,v 1.57 2014/08/26 12:14:14 joerg Exp $"); 44 #endif /* not lint */ 45 46 #include <err.h> 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <stdarg.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 #include <sys/types.h> 55 #include <sys/mman.h> 56 #include <sys/bitops.h> 57 #include <dirent.h> 58 59 #include "debug.h" 60 #include "rtld.h" 61 62 /* 63 * Process a shared object's DYNAMIC section, and save the important 64 * information in its Obj_Entry structure. 65 */ 66 void 67 _rtld_digest_dynamic(const char *execname, Obj_Entry *obj) 68 { 69 Elf_Dyn *dynp; 70 Needed_Entry **needed_tail = &obj->needed; 71 const Elf_Dyn *dyn_soname = NULL; 72 const Elf_Dyn *dyn_rpath = NULL; 73 bool use_pltrel = false; 74 bool use_pltrela = false; 75 Elf_Addr relsz = 0, relasz = 0; 76 Elf_Addr pltrel = 0, pltrelsz = 0; 77 Elf_Addr init = 0, fini = 0; 78 79 dbg(("headers: digesting PT_DYNAMIC at %p", obj->dynamic)); 80 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; ++dynp) { 81 dbg((" d_tag %ld at %p", (long)dynp->d_tag, dynp)); 82 switch (dynp->d_tag) { 83 84 case DT_REL: 85 obj->rel = (const Elf_Rel *) 86 (obj->relocbase + dynp->d_un.d_ptr); 87 break; 88 89 case DT_RELSZ: 90 relsz = dynp->d_un.d_val; 91 break; 92 93 case DT_RELENT: 94 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 95 break; 96 97 case DT_JMPREL: 98 pltrel = dynp->d_un.d_ptr; 99 break; 100 101 case DT_PLTRELSZ: 102 pltrelsz = dynp->d_un.d_val; 103 break; 104 105 case DT_RELA: 106 obj->rela = (const Elf_Rela *) 107 (obj->relocbase + dynp->d_un.d_ptr); 108 break; 109 110 case DT_RELASZ: 111 relasz = dynp->d_un.d_val; 112 break; 113 114 case DT_RELAENT: 115 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 116 break; 117 118 case DT_PLTREL: 119 use_pltrel = dynp->d_un.d_val == DT_REL; 120 use_pltrela = dynp->d_un.d_val == DT_RELA; 121 assert(use_pltrel || use_pltrela); 122 break; 123 124 case DT_SYMTAB: 125 obj->symtab = (const Elf_Sym *) 126 (obj->relocbase + dynp->d_un.d_ptr); 127 break; 128 129 case DT_SYMENT: 130 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 131 break; 132 133 case DT_STRTAB: 134 obj->strtab = (const char *) 135 (obj->relocbase + dynp->d_un.d_ptr); 136 break; 137 138 case DT_STRSZ: 139 obj->strsize = dynp->d_un.d_val; 140 break; 141 142 case DT_VERNEED: 143 obj->verneed = (const Elf_Verneed *) 144 (obj->relocbase + dynp->d_un.d_ptr); 145 break; 146 147 case DT_VERNEEDNUM: 148 obj->verneednum = dynp->d_un.d_val; 149 break; 150 151 case DT_VERDEF: 152 obj->verdef = (const Elf_Verdef *) 153 (obj->relocbase + dynp->d_un.d_ptr); 154 break; 155 156 case DT_VERDEFNUM: 157 obj->verdefnum = dynp->d_un.d_val; 158 break; 159 160 case DT_VERSYM: 161 obj->versyms = (const Elf_Versym *) 162 (obj->relocbase + dynp->d_un.d_ptr); 163 break; 164 165 case DT_HASH: 166 { 167 const Elf_Symindx *hashtab = (const Elf_Symindx *) 168 (obj->relocbase + dynp->d_un.d_ptr); 169 170 if (hashtab[0] > UINT32_MAX) 171 obj->nbuckets = UINT32_MAX; 172 else 173 obj->nbuckets = hashtab[0]; 174 obj->nchains = hashtab[1]; 175 obj->buckets = hashtab + 2; 176 obj->chains = obj->buckets + obj->nbuckets; 177 /* 178 * Should really be in _rtld_relocate_objects, 179 * but _rtld_symlook_obj might be used before. 180 */ 181 if (obj->nbuckets) { 182 fast_divide32_prepare(obj->nbuckets, 183 &obj->nbuckets_m, 184 &obj->nbuckets_s1, 185 &obj->nbuckets_s2); 186 } 187 } 188 break; 189 190 case DT_NEEDED: 191 { 192 Needed_Entry *nep = NEW(Needed_Entry); 193 194 nep->name = dynp->d_un.d_val; 195 nep->obj = NULL; 196 nep->next = NULL; 197 198 *needed_tail = nep; 199 needed_tail = &nep->next; 200 } 201 break; 202 203 case DT_PLTGOT: 204 obj->pltgot = (Elf_Addr *) 205 (obj->relocbase + dynp->d_un.d_ptr); 206 break; 207 208 case DT_TEXTREL: 209 obj->textrel = true; 210 break; 211 212 case DT_SYMBOLIC: 213 obj->symbolic = true; 214 break; 215 216 case DT_RPATH: 217 /* 218 * We have to wait until later to process this, because 219 * we might not have gotten the address of the string 220 * table yet. 221 */ 222 dyn_rpath = dynp; 223 break; 224 225 case DT_SONAME: 226 dyn_soname = dynp; 227 break; 228 229 case DT_INIT: 230 init = dynp->d_un.d_ptr; 231 break; 232 233 #ifdef HAVE_INITFINI_ARRAY 234 case DT_INIT_ARRAY: 235 obj->init_array = (Elf_Addr *)obj->relocbase + dynp->d_un.d_ptr; 236 dbg(("headers: DT_INIT_ARRAY at %p", 237 obj->init_array)); 238 break; 239 240 case DT_INIT_ARRAYSZ: 241 obj->init_arraysz = dynp->d_un.d_val / sizeof(fptr_t); 242 dbg(("headers: DT_INIT_ARRAYZ %zu", 243 obj->init_arraysz)); 244 break; 245 #endif 246 247 case DT_FINI: 248 fini = dynp->d_un.d_ptr; 249 break; 250 251 #ifdef HAVE_INITFINI_ARRAY 252 case DT_FINI_ARRAY: 253 obj->fini_array = 254 (Elf_Addr *)(obj->relocbase + dynp->d_un.d_ptr); 255 dbg(("headers: DT_FINI_ARRAY at %p", 256 obj->fini_array)); 257 break; 258 259 case DT_FINI_ARRAYSZ: 260 obj->fini_arraysz = dynp->d_un.d_val / sizeof(fptr_t); 261 dbg(("headers: DT_FINI_ARRAYZ %zu", 262 obj->fini_arraysz)); 263 break; 264 #endif 265 266 /* 267 * Don't process DT_DEBUG on MIPS as the dynamic section 268 * is mapped read-only. DT_MIPS_RLD_MAP is used instead. 269 * XXX: n32/n64 may use DT_DEBUG, not sure yet. 270 */ 271 #ifndef __mips__ 272 case DT_DEBUG: 273 #ifdef RTLD_LOADER 274 dynp->d_un.d_ptr = (Elf_Addr)&_rtld_debug; 275 #endif 276 break; 277 #endif 278 279 #ifdef __mips__ 280 case DT_MIPS_LOCAL_GOTNO: 281 obj->local_gotno = dynp->d_un.d_val; 282 break; 283 284 case DT_MIPS_SYMTABNO: 285 obj->symtabno = dynp->d_un.d_val; 286 break; 287 288 case DT_MIPS_GOTSYM: 289 obj->gotsym = dynp->d_un.d_val; 290 break; 291 292 case DT_MIPS_RLD_MAP: 293 #ifdef RTLD_LOADER 294 *((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) 295 &_rtld_debug; 296 #endif 297 break; 298 #endif 299 #ifdef __powerpc__ 300 #ifdef _LP64 301 case DT_PPC64_GLINK: 302 obj->glink = (Elf_Addr)(uintptr_t)obj->relocbase + dynp->d_un.d_ptr; 303 break; 304 #else 305 case DT_PPC_GOT: 306 obj->gotptr = (Elf_Addr *)(obj->relocbase + dynp->d_un.d_ptr); 307 break; 308 #endif 309 #endif 310 case DT_FLAGS_1: 311 obj->z_now = 312 ((dynp->d_un.d_val & DF_1_BIND_NOW) != 0); 313 obj->z_nodelete = 314 ((dynp->d_un.d_val & DF_1_NODELETE) != 0); 315 obj->z_initfirst = 316 ((dynp->d_un.d_val & DF_1_INITFIRST) != 0); 317 obj->z_noopen = 318 ((dynp->d_un.d_val & DF_1_NOOPEN) != 0); 319 break; 320 } 321 } 322 323 obj->rellim = (const Elf_Rel *)((const uint8_t *)obj->rel + relsz); 324 obj->relalim = (const Elf_Rela *)((const uint8_t *)obj->rela + relasz); 325 if (use_pltrel) { 326 obj->pltrel = (const Elf_Rel *)(obj->relocbase + pltrel); 327 obj->pltrellim = (const Elf_Rel *)(obj->relocbase + pltrel + pltrelsz); 328 obj->pltrelalim = 0; 329 /* On PPC and SPARC, at least, REL(A)SZ may include JMPREL. 330 Trim rel(a)lim to save time later. */ 331 if (obj->rellim && obj->pltrel && 332 obj->rellim > obj->pltrel && 333 obj->rellim <= obj->pltrellim) 334 obj->rellim = obj->pltrel; 335 } else if (use_pltrela) { 336 obj->pltrela = (const Elf_Rela *)(obj->relocbase + pltrel); 337 obj->pltrellim = 0; 338 obj->pltrelalim = (const Elf_Rela *)(obj->relocbase + pltrel + pltrelsz); 339 /* On PPC and SPARC, at least, REL(A)SZ may include JMPREL. 340 Trim rel(a)lim to save time later. */ 341 if (obj->relalim && obj->pltrela && 342 obj->relalim > obj->pltrela && 343 obj->relalim <= obj->pltrelalim) 344 obj->relalim = obj->pltrela; 345 } 346 347 #ifdef RTLD_LOADER 348 if (init != 0) 349 obj->init = (Elf_Addr) obj->relocbase + init; 350 if (fini != 0) 351 obj->fini = (Elf_Addr) obj->relocbase + fini; 352 #endif 353 354 if (dyn_rpath != NULL) { 355 _rtld_add_paths(execname, &obj->rpaths, obj->strtab + 356 dyn_rpath->d_un.d_val); 357 } 358 if (dyn_soname != NULL) { 359 _rtld_object_add_name(obj, obj->strtab + 360 dyn_soname->d_un.d_val); 361 } 362 } 363 364 /* 365 * Process a shared object's program header. This is used only for the 366 * main program, when the kernel has already loaded the main program 367 * into memory before calling the dynamic linker. It creates and 368 * returns an Obj_Entry structure. 369 */ 370 Obj_Entry * 371 _rtld_digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry) 372 { 373 Obj_Entry *obj; 374 const Elf_Phdr *phlimit = phdr + phnum; 375 const Elf_Phdr *ph; 376 int nsegs = 0; 377 Elf_Addr vaddr; 378 379 obj = _rtld_obj_new(); 380 381 for (ph = phdr; ph < phlimit; ++ph) { 382 if (ph->p_type != PT_PHDR) 383 continue; 384 385 obj->phdr = (void *)(uintptr_t)ph->p_vaddr; 386 obj->phsize = ph->p_memsz; 387 obj->relocbase = (caddr_t)((uintptr_t)phdr - (uintptr_t)ph->p_vaddr); 388 dbg(("headers: phdr %p (%p) phsize %zu relocbase %p", 389 obj->phdr, phdr, obj->phsize, obj->relocbase)); 390 break; 391 } 392 393 for (ph = phdr; ph < phlimit; ++ph) { 394 vaddr = (Elf_Addr)(uintptr_t)(obj->relocbase + ph->p_vaddr); 395 switch (ph->p_type) { 396 397 case PT_INTERP: 398 obj->interp = (const char *)(uintptr_t)vaddr; 399 dbg(("headers: %s %p phsize %" PRImemsz, 400 "PT_INTERP", (void *)(uintptr_t)vaddr, 401 ph->p_memsz)); 402 break; 403 404 case PT_LOAD: 405 assert(nsegs < 2); 406 if (nsegs == 0) { /* First load segment */ 407 obj->vaddrbase = round_down(vaddr); 408 obj->mapbase = (caddr_t)(uintptr_t)obj->vaddrbase; 409 obj->textsize = round_up(vaddr + ph->p_memsz) - 410 obj->vaddrbase; 411 } else { /* Last load segment */ 412 obj->mapsize = round_up(vaddr + ph->p_memsz) - 413 obj->vaddrbase; 414 } 415 ++nsegs; 416 dbg(("headers: %s %p phsize %" PRImemsz, 417 "PT_LOAD", (void *)(uintptr_t)vaddr, 418 ph->p_memsz)); 419 break; 420 421 case PT_DYNAMIC: 422 obj->dynamic = (Elf_Dyn *)(uintptr_t)vaddr; 423 dbg(("headers: %s %p phsize %" PRImemsz, 424 "PT_DYNAMIC", (void *)(uintptr_t)vaddr, 425 ph->p_memsz)); 426 break; 427 428 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 429 case PT_TLS: 430 obj->tlsindex = 1; 431 obj->tlssize = ph->p_memsz; 432 obj->tlsalign = ph->p_align; 433 obj->tlsinitsize = ph->p_filesz; 434 obj->tlsinit = (void *)(uintptr_t)ph->p_vaddr; 435 dbg(("headers: %s %p phsize %" PRImemsz, 436 "PT_TLS", (void *)(uintptr_t)vaddr, 437 ph->p_memsz)); 438 break; 439 #endif 440 #ifdef __ARM_EABI__ 441 case PT_ARM_EXIDX: 442 obj->exidx_start = (void *)(uintptr_t)vaddr; 443 obj->exidx_sz = ph->p_memsz; 444 dbg(("headers: %s %p phsize %" PRImemsz, 445 "PT_ARM_EXIDX", (void *)(uintptr_t)vaddr, 446 ph->p_memsz)); 447 break; 448 #endif 449 } 450 } 451 assert(nsegs == 2); 452 453 obj->entry = entry; 454 return obj; 455 } 456
Indexes created Wed Oct 15 16:09:53 GMT 2025