1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 2000, Boris Popov 5 * Copyright (c) 1998-2000 Doug Rabson 6 * Copyright (c) 2004 Peter Wemm 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 Boris Popov. 20 * 4. Neither the name of the author nor the names of any co-contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <sys/param.h> 38 39 #include <err.h> 40 #include <errno.h> 41 #include <gelf.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 46 #include "ef.h" 47 48 typedef struct { 49 GElf_Addr addr; 50 GElf_Off offset; 51 GElf_Off size; 52 int flags; 53 int sec; /* Original section */ 54 char *name; 55 } Elf_progent; 56 57 typedef struct { 58 GElf_Rel *rel; 59 long nrel; 60 int sec; 61 } Elf_relent; 62 63 typedef struct { 64 GElf_Rela *rela; 65 long nrela; 66 int sec; 67 } Elf_relaent; 68 69 struct ef_file { 70 char *ef_name; 71 struct elf_file *ef_efile; 72 73 Elf_progent *progtab; 74 int nprogtab; 75 76 Elf_relaent *relatab; 77 int nrela; 78 79 Elf_relent *reltab; 80 int nrel; 81 82 GElf_Sym *ddbsymtab; /* The symbol table we are using */ 83 size_t ddbsymcnt; /* Number of symbols */ 84 caddr_t ddbstrtab; /* String table */ 85 long ddbstrcnt; /* number of bytes in string table */ 86 87 caddr_t shstrtab; /* Section name string table */ 88 long shstrcnt; /* number of bytes in string table */ 89 90 int ef_verbose; 91 }; 92 93 static void ef_obj_close(elf_file_t ef); 94 95 static int ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address, 96 size_t len, void *dest); 97 static int ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address, 98 size_t len, char *dest); 99 100 static GElf_Addr ef_obj_symaddr(elf_file_t ef, GElf_Size symidx); 101 static int ef_obj_lookup_set(elf_file_t ef, const char *name, 102 GElf_Addr *startp, GElf_Addr *stopp, long *countp); 103 static int ef_obj_lookup_symbol(elf_file_t ef, const char *name, 104 GElf_Sym **sym); 105 106 static struct elf_file_ops ef_obj_file_ops = { 107 .close = ef_obj_close, 108 .seg_read_rel = ef_obj_seg_read_rel, 109 .seg_read_string = ef_obj_seg_read_string, 110 .symaddr = ef_obj_symaddr, 111 .lookup_set = ef_obj_lookup_set, 112 }; 113 114 static GElf_Off 115 ef_obj_get_offset(elf_file_t ef, GElf_Addr addr) 116 { 117 Elf_progent *pt; 118 int i; 119 120 for (i = 0; i < ef->nprogtab; i++) { 121 pt = &ef->progtab[i]; 122 if (pt->offset == (GElf_Off)-1) 123 continue; 124 if (addr >= pt->addr && addr < pt->addr + pt->size) 125 return (pt->offset + (addr - pt->addr)); 126 } 127 return (0); 128 } 129 130 static int 131 ef_obj_lookup_symbol(elf_file_t ef, const char *name, GElf_Sym **sym) 132 { 133 GElf_Sym *symp; 134 const char *strp; 135 int i; 136 137 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 138 strp = ef->ddbstrtab + symp->st_name; 139 if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) { 140 *sym = symp; 141 return (0); 142 } 143 } 144 return (ENOENT); 145 } 146 147 static int 148 ef_obj_lookup_set(elf_file_t ef, const char *name, GElf_Addr *startp, 149 GElf_Addr *stopp, long *countp) 150 { 151 int i; 152 153 for (i = 0; i < ef->nprogtab; i++) { 154 if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) && 155 strcmp(ef->progtab[i].name + 4, name) == 0) { 156 *startp = ef->progtab[i].addr; 157 *stopp = ef->progtab[i].addr + ef->progtab[i].size; 158 *countp = (*stopp - *startp) / 159 elf_pointer_size(ef->ef_efile); 160 return (0); 161 } 162 } 163 return (ESRCH); 164 } 165 166 static GElf_Addr 167 ef_obj_symaddr(elf_file_t ef, GElf_Size symidx) 168 { 169 const GElf_Sym *sym; 170 171 if (symidx >= ef->ddbsymcnt) 172 return (0); 173 sym = ef->ddbsymtab + symidx; 174 175 if (sym->st_shndx != SHN_UNDEF) 176 return (sym->st_value); 177 return (0); 178 } 179 180 static int 181 ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address, size_t len, void *dest) 182 { 183 GElf_Off secofs; 184 GElf_Rel *r; 185 GElf_Rela *a; 186 GElf_Addr secbase, dataoff; 187 int error, i, sec; 188 189 /* Find out which section contains the data. */ 190 sec = -1; 191 for (i = 0; i < ef->nprogtab; i++) { 192 if (address < ef->progtab[i].addr) 193 continue; 194 195 dataoff = address - ef->progtab[i].addr; 196 if (dataoff + len > ef->progtab[i].size) 197 continue; 198 199 sec = ef->progtab[i].sec; 200 secbase = ef->progtab[i].addr; 201 secofs = ef->progtab[i].offset; 202 break; 203 } 204 205 if (sec == -1) { 206 if (ef->ef_verbose) 207 warnx("ef_obj_seg_read_rel(%s): bad address (%jx)", 208 ef->ef_name, (uintmax_t)address); 209 return (EFAULT); 210 } 211 212 if (secofs == (GElf_Off)-1) { 213 memset(dest, 0, len); 214 } else { 215 error = elf_read_raw_data(ef->ef_efile, secofs + dataoff, dest, 216 len); 217 if (error != 0) 218 return (error); 219 } 220 221 /* Now do the relocations. */ 222 for (i = 0; i < ef->nrel; i++) { 223 if (ef->reltab[i].sec != sec) 224 continue; 225 for (r = ef->reltab[i].rel; 226 r < &ef->reltab[i].rel[ef->reltab[i].nrel]; r++) { 227 error = elf_reloc(ef->ef_efile, r, ELF_T_REL, secbase, 228 address, len, dest); 229 if (error != 0) 230 return (error); 231 } 232 } 233 for (i = 0; i < ef->nrela; i++) { 234 if (ef->relatab[i].sec != sec) 235 continue; 236 for (a = ef->relatab[i].rela; 237 a < &ef->relatab[i].rela[ef->relatab[i].nrela]; a++) { 238 error = elf_reloc(ef->ef_efile, a, ELF_T_RELA, secbase, 239 address, len, dest); 240 if (error != 0) 241 return (error); 242 } 243 } 244 return (0); 245 } 246 247 static int 248 ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address, size_t len, char *dest) 249 { 250 GElf_Off ofs; 251 int error; 252 253 ofs = ef_obj_get_offset(ef, address); 254 if (ofs == 0) { 255 if (ef->ef_verbose) 256 warnx("ef_obj_seg_read_string(%s): bad address (%jx)", 257 ef->ef_name, (uintmax_t)address); 258 return (EFAULT); 259 } 260 261 error = elf_read_raw_data(ef->ef_efile, ofs, dest, len); 262 if (error != 0) 263 return (error); 264 if (strnlen(dest, len) == len) 265 return (EFAULT); 266 267 return (0); 268 } 269 270 int 271 ef_obj_open(struct elf_file *efile, int verbose) 272 { 273 elf_file_t ef; 274 GElf_Ehdr *hdr; 275 GElf_Shdr *shdr; 276 GElf_Sym *es; 277 GElf_Addr mapbase; 278 size_t i, nshdr; 279 int error, pb, ra, rl; 280 int j, nsym, symstrindex, symtabindex; 281 282 hdr = &efile->ef_hdr; 283 if (hdr->e_type != ET_REL || hdr->e_shnum == 0 || hdr->e_shoff == 0 || 284 hdr->e_shentsize != elf_object_size(efile, ELF_T_SHDR)) 285 return (EFTYPE); 286 287 ef = calloc(1, sizeof(*ef)); 288 if (ef == NULL) 289 return (errno); 290 291 efile->ef_ef = ef; 292 efile->ef_ops = &ef_obj_file_ops; 293 294 ef->ef_verbose = verbose; 295 ef->ef_name = strdup(efile->ef_filename); 296 ef->ef_efile = efile; 297 298 error = elf_read_shdrs(efile, &nshdr, &shdr); 299 if (error != 0) { 300 shdr = NULL; 301 goto out; 302 } 303 304 /* Scan the section headers for information and table sizing. */ 305 nsym = 0; 306 symtabindex = -1; 307 symstrindex = -1; 308 for (i = 0; i < nshdr; i++) { 309 switch (shdr[i].sh_type) { 310 case SHT_PROGBITS: 311 case SHT_NOBITS: 312 ef->nprogtab++; 313 break; 314 case SHT_SYMTAB: 315 nsym++; 316 symtabindex = i; 317 symstrindex = shdr[i].sh_link; 318 break; 319 case SHT_REL: 320 ef->nrel++; 321 break; 322 case SHT_RELA: 323 ef->nrela++; 324 break; 325 case SHT_STRTAB: 326 break; 327 } 328 } 329 330 if (ef->nprogtab == 0) { 331 warnx("%s: file has no contents", ef->ef_name); 332 goto out; 333 } 334 if (nsym != 1) { 335 warnx("%s: file has no valid symbol table", ef->ef_name); 336 goto out; 337 } 338 if (symstrindex < 0 || symstrindex > nshdr || 339 shdr[symstrindex].sh_type != SHT_STRTAB) { 340 warnx("%s: file has invalid symbol strings", ef->ef_name); 341 goto out; 342 } 343 344 /* Allocate space for tracking the load chunks */ 345 if (ef->nprogtab != 0) 346 ef->progtab = calloc(ef->nprogtab, sizeof(*ef->progtab)); 347 if (ef->nrel != 0) 348 ef->reltab = calloc(ef->nrel, sizeof(*ef->reltab)); 349 if (ef->nrela != 0) 350 ef->relatab = calloc(ef->nrela, sizeof(*ef->relatab)); 351 if ((ef->nprogtab != 0 && ef->progtab == NULL) || 352 (ef->nrel != 0 && ef->reltab == NULL) || 353 (ef->nrela != 0 && ef->relatab == NULL)) { 354 printf("malloc failed\n"); 355 error = ENOMEM; 356 goto out; 357 } 358 359 if (elf_read_symbols(efile, symtabindex, &ef->ddbsymcnt, 360 &ef->ddbsymtab) != 0) { 361 printf("elf_read_symbols failed\n"); 362 goto out; 363 } 364 365 if (elf_read_string_table(efile, &shdr[symstrindex], &ef->ddbstrcnt, 366 &ef->ddbstrtab) != 0) { 367 printf("elf_read_string_table failed\n"); 368 goto out; 369 } 370 371 /* Do we have a string table for the section names? */ 372 if (hdr->e_shstrndx != 0 && 373 shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) { 374 if (elf_read_string_table(efile, &shdr[hdr->e_shstrndx], 375 &ef->shstrcnt, &ef->shstrtab) != 0) { 376 printf("elf_read_string_table failed\n"); 377 goto out; 378 } 379 } 380 381 /* 382 * Now allocate address space for code/data(progbits) and 383 * bss(nobits) and allocate space for and load relocs. 384 */ 385 pb = 0; 386 rl = 0; 387 ra = 0; 388 mapbase = 0; 389 for (i = 0; i < nshdr; i++) { 390 switch (shdr[i].sh_type) { 391 case SHT_PROGBITS: 392 case SHT_NOBITS: 393 mapbase = roundup2(mapbase, shdr[i].sh_addralign); 394 ef->progtab[pb].addr = mapbase; 395 if (shdr[i].sh_type == SHT_PROGBITS) { 396 ef->progtab[pb].name = "<<PROGBITS>>"; 397 ef->progtab[pb].offset = shdr[i].sh_offset; 398 } else { 399 ef->progtab[pb].name = "<<NOBITS>>"; 400 ef->progtab[pb].offset = (GElf_Off)-1; 401 } 402 ef->progtab[pb].size = shdr[i].sh_size; 403 ef->progtab[pb].sec = i; 404 if (ef->shstrtab && shdr[i].sh_name != 0) 405 ef->progtab[pb].name = 406 ef->shstrtab + shdr[i].sh_name; 407 408 /* Update all symbol values with the offset. */ 409 for (j = 0; j < ef->ddbsymcnt; j++) { 410 es = &ef->ddbsymtab[j]; 411 if (es->st_shndx != i) 412 continue; 413 es->st_value += ef->progtab[pb].addr; 414 } 415 mapbase += shdr[i].sh_size; 416 pb++; 417 break; 418 case SHT_REL: 419 ef->reltab[rl].sec = shdr[i].sh_info; 420 if (elf_read_rel(efile, i, &ef->reltab[rl].nrel, 421 &ef->reltab[rl].rel) != 0) { 422 printf("elf_read_rel failed\n"); 423 goto out; 424 } 425 rl++; 426 break; 427 case SHT_RELA: 428 ef->relatab[ra].sec = shdr[i].sh_info; 429 if (elf_read_rela(efile, i, &ef->relatab[ra].nrela, 430 &ef->relatab[ra].rela) != 0) { 431 printf("elf_read_rela failed\n"); 432 goto out; 433 } 434 ra++; 435 break; 436 } 437 } 438 error = 0; 439 out: 440 free(shdr); 441 if (error != 0) 442 ef_obj_close(ef); 443 return (error); 444 } 445 446 static void 447 ef_obj_close(elf_file_t ef) 448 { 449 int i; 450 451 if (ef->ef_name) 452 free(ef->ef_name); 453 if (ef->nprogtab != 0) 454 free(ef->progtab); 455 if (ef->nrel != 0) { 456 for (i = 0; i < ef->nrel; i++) 457 if (ef->reltab[i].rel != NULL) 458 free(ef->reltab[i].rel); 459 free(ef->reltab); 460 } 461 if (ef->nrela != 0) { 462 for (i = 0; i < ef->nrela; i++) 463 if (ef->relatab[i].rela != NULL) 464 free(ef->relatab[i].rela); 465 free(ef->relatab); 466 } 467 if (ef->ddbsymtab != NULL) 468 free(ef->ddbsymtab); 469 if (ef->ddbstrtab != NULL) 470 free(ef->ddbstrtab); 471 if (ef->shstrtab != NULL) 472 free(ef->shstrtab); 473 ef->ef_efile->ef_ops = NULL; 474 ef->ef_efile->ef_ef = NULL; 475 free(ef); 476 } 477