1 /* $NetBSD: map_object.c,v 1.52 2013/08/03 13:17:05 skrll Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt@3am-software.com> 6 * Copyright 2002 Charles M. Hannum <root@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 #include <sys/cdefs.h> 36 #ifndef lint 37 __RCSID("$NetBSD: map_object.c,v 1.52 2013/08/03 13:17:05 skrll Exp $"); 38 #endif /* not lint */ 39 40 #include <errno.h> 41 #include <stddef.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include <sys/stat.h> 46 #include <sys/types.h> 47 #include <sys/mman.h> 48 49 #include "debug.h" 50 #include "rtld.h" 51 52 #if defined(__minix) 53 #define MINIXVERBOSE 0 54 55 #if MINIXVERBOSE 56 #include <stdio.h> 57 #endif 58 59 #endif /* defined(__minix) */ 60 61 static int protflags(int); /* Elf flags -> mmap protection */ 62 63 #define EA_UNDEF (~(Elf_Addr)0) 64 65 /* 66 * Map a shared object into memory. The argument is a file descriptor, 67 * which must be open on the object and positioned at its beginning. 68 * 69 * The return value is a pointer to a newly-allocated Obj_Entry structure 70 * for the shared object. Returns NULL on failure. 71 */ 72 Obj_Entry * 73 _rtld_map_object(const char *path, int fd, const struct stat *sb) 74 { 75 Obj_Entry *obj; 76 Elf_Ehdr *ehdr; 77 Elf_Phdr *phdr; 78 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 79 Elf_Phdr *phtls; 80 #endif 81 size_t phsize; 82 Elf_Phdr *phlimit; 83 Elf_Phdr *segs[2]; 84 int nsegs; 85 caddr_t mapbase = MAP_FAILED; 86 size_t mapsize = 0; 87 int mapflags; 88 Elf_Off base_offset; 89 #ifdef MAP_ALIGNED 90 Elf_Addr base_alignment; 91 #endif 92 Elf_Addr base_vaddr; 93 Elf_Addr base_vlimit; 94 Elf_Addr text_vlimit; 95 int text_flags; 96 caddr_t base_addr; 97 Elf_Off data_offset; 98 Elf_Addr data_vaddr; 99 Elf_Addr data_vlimit; 100 int data_flags; 101 caddr_t data_addr; 102 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 103 Elf_Addr tls_vaddr = 0; /* Noise GCC */ 104 #endif 105 Elf_Addr phdr_vaddr; 106 size_t phdr_memsz; 107 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 108 caddr_t gap_addr; 109 size_t gap_size; 110 #endif 111 int i; 112 #ifdef RTLD_LOADER 113 Elf_Addr clear_vaddr; 114 caddr_t clear_addr; 115 size_t nclear; 116 #endif 117 #if defined(__minix) 118 Elf_Addr bsslen; 119 #endif /* defined(__minix) */ 120 121 if (sb != NULL && sb->st_size < (off_t)sizeof (Elf_Ehdr)) { 122 _rtld_error("%s: not ELF file (too short)", path); 123 return NULL; 124 } 125 126 obj = _rtld_obj_new(); 127 obj->path = xstrdup(path); 128 obj->pathlen = strlen(path); 129 if (sb != NULL) { 130 obj->dev = sb->st_dev; 131 obj->ino = sb->st_ino; 132 } 133 134 ehdr = mmap(NULL, _rtld_pagesz, PROT_READ, MAP_FILE | MAP_SHARED, fd, 135 (off_t)0); 136 obj->ehdr = ehdr; 137 if (ehdr == MAP_FAILED) { 138 #if defined(__minix) 139 return _rtld_map_object_fallback(path, fd, sb); 140 #else 141 _rtld_error("%s: read error: %s", path, xstrerror(errno)); 142 goto bad; 143 #endif 144 } 145 /* Make sure the file is valid */ 146 if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0) { 147 _rtld_error("%s: not ELF file (magic number bad)", path); 148 goto bad; 149 } 150 if (ehdr->e_ident[EI_CLASS] != ELFCLASS) { 151 _rtld_error("%s: invalid ELF class %x; expected %x", path, 152 ehdr->e_ident[EI_CLASS], ELFCLASS); 153 goto bad; 154 } 155 /* Elf_e_ident includes class */ 156 if (ehdr->e_ident[EI_VERSION] != EV_CURRENT || 157 ehdr->e_version != EV_CURRENT || 158 ehdr->e_ident[EI_DATA] != ELFDEFNNAME(MACHDEP_ENDIANNESS)) { 159 _rtld_error("%s: unsupported file version", path); 160 goto bad; 161 } 162 if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) { 163 _rtld_error("%s: unsupported file type", path); 164 goto bad; 165 } 166 switch (ehdr->e_machine) { 167 ELFDEFNNAME(MACHDEP_ID_CASES) 168 default: 169 _rtld_error("%s: unsupported machine", path); 170 goto bad; 171 } 172 173 /* 174 * We rely on the program header being in the first page. This is 175 * not strictly required by the ABI specification, but it seems to 176 * always true in practice. And, it simplifies things considerably. 177 */ 178 assert(ehdr->e_phentsize == sizeof(Elf_Phdr)); 179 assert(ehdr->e_phoff + ehdr->e_phnum * sizeof(Elf_Phdr) <= 180 _rtld_pagesz); 181 182 /* 183 * Scan the program header entries, and save key information. 184 * 185 * We rely on there being exactly two load segments, text and data, 186 * in that order. 187 */ 188 phdr = (Elf_Phdr *) ((caddr_t)ehdr + ehdr->e_phoff); 189 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 190 phtls = NULL; 191 #endif 192 phsize = ehdr->e_phnum * sizeof(phdr[0]); 193 obj->phdr = NULL; 194 phdr_vaddr = EA_UNDEF; 195 phdr_memsz = 0; 196 phlimit = phdr + ehdr->e_phnum; 197 nsegs = 0; 198 while (phdr < phlimit) { 199 switch (phdr->p_type) { 200 case PT_INTERP: 201 obj->interp = (void *)(uintptr_t)phdr->p_vaddr; 202 dbg(("%s: PT_INTERP %p", obj->path, obj->interp)); 203 break; 204 205 case PT_LOAD: 206 if (nsegs < 2) 207 segs[nsegs] = phdr; 208 ++nsegs; 209 210 dbg(("%s: %s %p phsize %" PRImemsz, obj->path, "PT_LOAD", 211 (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz)); 212 break; 213 214 case PT_PHDR: 215 phdr_vaddr = phdr->p_vaddr; 216 phdr_memsz = phdr->p_memsz; 217 dbg(("%s: %s %p phsize %" PRImemsz, obj->path, "PT_PHDR", 218 (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz)); 219 break; 220 221 case PT_DYNAMIC: 222 obj->dynamic = (void *)(uintptr_t)phdr->p_vaddr; 223 dbg(("%s: %s %p phsize %" PRImemsz, obj->path, "PT_DYNAMIC", 224 (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz)); 225 break; 226 227 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 228 case PT_TLS: 229 phtls = phdr; 230 dbg(("%s: %s %p phsize %" PRImemsz, obj->path, "PT_TLS", 231 (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz)); 232 break; 233 #endif 234 #ifdef __ARM_EABI__ 235 case PT_ARM_EXIDX: 236 obj->exidx_start = (void *)(uintptr_t)phdr->p_vaddr; 237 obj->exidx_sz = phdr->p_memsz; 238 break; 239 #endif 240 } 241 242 ++phdr; 243 } 244 phdr = (Elf_Phdr *) ((caddr_t)ehdr + ehdr->e_phoff); 245 obj->entry = (void *)(uintptr_t)ehdr->e_entry; 246 if (!obj->dynamic) { 247 _rtld_error("%s: not dynamically linked", path); 248 goto bad; 249 } 250 if (nsegs != 2) { 251 _rtld_error("%s: wrong number of segments (%d != 2)", path, 252 nsegs); 253 goto bad; 254 } 255 256 /* 257 * Map the entire address space of the object as a file 258 * region to stake out our contiguous region and establish a 259 * base for relocation. We use a file mapping so that 260 * the kernel will give us whatever alignment is appropriate 261 * for the platform we're running on. 262 * 263 * We map it using the text protection, map the data segment 264 * into the right place, then map an anon segment for the bss 265 * and unmap the gaps left by padding to alignment. 266 */ 267 268 #ifdef MAP_ALIGNED 269 base_alignment = segs[0]->p_align; 270 #endif 271 base_offset = round_down(segs[0]->p_offset); 272 base_vaddr = round_down(segs[0]->p_vaddr); 273 base_vlimit = round_up(segs[1]->p_vaddr + segs[1]->p_memsz); 274 text_vlimit = round_up(segs[0]->p_vaddr + segs[0]->p_memsz); 275 text_flags = protflags(segs[0]->p_flags); 276 data_offset = round_down(segs[1]->p_offset); 277 data_vaddr = round_down(segs[1]->p_vaddr); 278 data_vlimit = round_up(segs[1]->p_vaddr + segs[1]->p_filesz); 279 data_flags = protflags(segs[1]->p_flags); 280 #ifdef RTLD_LOADER 281 clear_vaddr = segs[1]->p_vaddr + segs[1]->p_filesz; 282 #endif 283 284 obj->textsize = text_vlimit - base_vaddr; 285 obj->vaddrbase = base_vaddr; 286 obj->isdynamic = ehdr->e_type == ET_DYN; 287 288 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 289 if (phtls != NULL) { 290 ++_rtld_tls_dtv_generation; 291 obj->tlsindex = ++_rtld_tls_max_index; 292 obj->tlssize = phtls->p_memsz; 293 obj->tlsalign = phtls->p_align; 294 obj->tlsinitsize = phtls->p_filesz; 295 tls_vaddr = phtls->p_vaddr; 296 } 297 #endif 298 299 obj->phdr_loaded = false; 300 for (i = 0; i < nsegs; i++) { 301 if (phdr_vaddr != EA_UNDEF && 302 segs[i]->p_vaddr <= phdr_vaddr && 303 segs[i]->p_memsz >= phdr_memsz) { 304 obj->phdr_loaded = true; 305 break; 306 } 307 if (segs[i]->p_offset <= ehdr->e_phoff && 308 segs[i]->p_memsz >= phsize) { 309 phdr_vaddr = segs[i]->p_vaddr + ehdr->e_phoff; 310 phdr_memsz = phsize; 311 obj->phdr_loaded = true; 312 break; 313 } 314 } 315 if (obj->phdr_loaded) { 316 obj->phdr = (void *)(uintptr_t)phdr_vaddr; 317 obj->phsize = phdr_memsz; 318 } else { 319 Elf_Phdr *buf; 320 buf = xmalloc(phsize); 321 if (buf == NULL) { 322 _rtld_error("%s: cannot allocate program header", path); 323 goto bad; 324 } 325 memcpy(buf, phdr, phsize); 326 obj->phdr = buf; 327 obj->phsize = phsize; 328 } 329 dbg(("%s: phdr %p phsize %zu (%s)", obj->path, obj->phdr, obj->phsize, 330 obj->phdr_loaded ? "loaded" : "allocated")); 331 332 /* Unmap header if it overlaps the first load section. */ 333 if (base_offset < _rtld_pagesz) { 334 munmap(ehdr, _rtld_pagesz); 335 obj->ehdr = MAP_FAILED; 336 } 337 338 /* 339 * Calculate log2 of the base section alignment. 340 */ 341 mapflags = 0; 342 #ifdef MAP_ALIGNED 343 if (base_alignment > _rtld_pagesz) { 344 unsigned int log2 = 0; 345 for (; base_alignment > 1; base_alignment >>= 1) 346 log2++; 347 mapflags = MAP_ALIGNED(log2); 348 } 349 #endif 350 351 #ifdef RTLD_LOADER 352 base_addr = obj->isdynamic ? NULL : (caddr_t)base_vaddr; 353 #else 354 base_addr = NULL; 355 #endif 356 mapsize = base_vlimit - base_vaddr; 357 mapbase = mmap(base_addr, mapsize, text_flags, 358 mapflags | MAP_FILE | MAP_PRIVATE, fd, base_offset); 359 if (mapbase == MAP_FAILED) { 360 _rtld_error("mmap of entire address space failed: %s", 361 xstrerror(errno)); 362 goto bad; 363 } 364 365 /* Overlay the data segment onto the proper region. */ 366 data_addr = mapbase + (data_vaddr - base_vaddr); 367 if (mmap(data_addr, data_vlimit - data_vaddr, data_flags, 368 MAP_FILE | MAP_PRIVATE | MAP_FIXED, fd, data_offset) == 369 MAP_FAILED) { 370 _rtld_error("mmap of data failed: %s", xstrerror(errno)); 371 goto bad; 372 } 373 374 /* Overlay the bss segment onto the proper region. */ 375 #if defined(__minix) 376 bsslen = base_vlimit - data_vlimit; 377 if (bsslen > 0 && 378 mmap(mapbase + data_vlimit - base_vaddr, bsslen, 379 #else 380 if (mmap(mapbase + data_vlimit - base_vaddr, base_vlimit - data_vlimit, 381 #endif /* defined(__minix) */ 382 data_flags, MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0) == 383 MAP_FAILED) { 384 _rtld_error("mmap of bss failed: %s", xstrerror(errno)); 385 goto bad; 386 } 387 388 /* Unmap the gap between the text and data. */ 389 #if !defined(__minix) 390 gap_addr = mapbase + round_up(text_vlimit - base_vaddr); 391 gap_size = data_addr - gap_addr; 392 if (gap_size != 0 && mprotect(gap_addr, gap_size, PROT_NONE) == -1) { 393 _rtld_error("mprotect of text -> data gap failed: %s", 394 xstrerror(errno)); 395 goto bad; 396 } 397 #endif /* !defined(__minix) */ 398 399 #ifdef RTLD_LOADER 400 /* Clear any BSS in the last page of the data segment. */ 401 clear_addr = mapbase + (clear_vaddr - base_vaddr); 402 if ((nclear = data_vlimit - clear_vaddr) > 0) 403 memset(clear_addr, 0, nclear); 404 405 /* Non-file portion of BSS mapped above. */ 406 #endif 407 408 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 409 if (phtls != NULL) 410 obj->tlsinit = mapbase + tls_vaddr; 411 #endif 412 413 obj->mapbase = mapbase; 414 obj->mapsize = mapsize; 415 obj->relocbase = mapbase - base_vaddr; 416 417 if (obj->dynamic) 418 obj->dynamic = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->dynamic); 419 if (obj->entry) 420 obj->entry = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->entry); 421 if (obj->interp) 422 obj->interp = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->interp); 423 if (obj->phdr_loaded) 424 obj->phdr = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->phdr); 425 #ifdef __ARM_EABI__ 426 if (obj->exidx_start) 427 obj->exidx_start = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->exidx_start); 428 #endif 429 430 return obj; 431 432 bad: 433 if (obj->ehdr != MAP_FAILED) 434 munmap(obj->ehdr, _rtld_pagesz); 435 if (mapbase != MAP_FAILED) 436 munmap(mapbase, mapsize); 437 _rtld_obj_free(obj); 438 return NULL; 439 } 440 441 void 442 _rtld_obj_free(Obj_Entry *obj) 443 { 444 Objlist_Entry *elm; 445 Name_Entry *entry; 446 447 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 448 if (obj->tls_done) 449 _rtld_tls_offset_free(obj); 450 #endif 451 xfree(obj->path); 452 while (obj->needed != NULL) { 453 Needed_Entry *needed = obj->needed; 454 obj->needed = needed->next; 455 xfree(needed); 456 } 457 while ((entry = SIMPLEQ_FIRST(&obj->names)) != NULL) { 458 SIMPLEQ_REMOVE_HEAD(&obj->names, link); 459 xfree(entry); 460 } 461 while ((elm = SIMPLEQ_FIRST(&obj->dldags)) != NULL) { 462 SIMPLEQ_REMOVE_HEAD(&obj->dldags, link); 463 xfree(elm); 464 } 465 while ((elm = SIMPLEQ_FIRST(&obj->dagmembers)) != NULL) { 466 SIMPLEQ_REMOVE_HEAD(&obj->dagmembers, link); 467 xfree(elm); 468 } 469 if (!obj->phdr_loaded) 470 xfree((void *)(uintptr_t)obj->phdr); 471 xfree(obj); 472 #ifdef COMBRELOC 473 _rtld_combreloc_reset(obj); 474 #endif 475 } 476 477 Obj_Entry * 478 _rtld_obj_new(void) 479 { 480 Obj_Entry *obj; 481 482 obj = CNEW(Obj_Entry); 483 SIMPLEQ_INIT(&obj->names); 484 SIMPLEQ_INIT(&obj->dldags); 485 SIMPLEQ_INIT(&obj->dagmembers); 486 return obj; 487 } 488 489 /* 490 * Given a set of ELF protection flags, return the corresponding protection 491 * flags for MMAP. 492 */ 493 static int 494 protflags(int elfflags) 495 { 496 int prot = 0; 497 498 if (elfflags & PF_R) 499 prot |= PROT_READ; 500 #ifdef RTLD_LOADER 501 if (elfflags & PF_W) 502 prot |= PROT_WRITE; 503 #endif 504 if (elfflags & PF_X) 505 prot |= PROT_EXEC; 506 #if defined(__minix) 507 /* Minix has to map it writable so we can do relocations 508 * as we don't have mprotect() yet. 509 */ 510 prot |= PROT_WRITE; 511 #endif /* defined(__minix) */ 512 return prot; 513 } 514