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 "kldelf.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 .lookup_symbol = ef_obj_lookup_symbol, 113 }; 114 115 static GElf_Off 116 ef_obj_get_offset(elf_file_t ef, GElf_Addr addr) 117 { 118 Elf_progent *pt; 119 int i; 120 121 for (i = 0; i < ef->nprogtab; i++) { 122 pt = &ef->progtab[i]; 123 if (pt->offset == (GElf_Off)-1) 124 continue; 125 if (addr >= pt->addr && addr < pt->addr + pt->size) 126 return (pt->offset + (addr - pt->addr)); 127 } 128 return (0); 129 } 130 131 static int 132 ef_obj_lookup_symbol(elf_file_t ef, const char *name, GElf_Sym **sym) 133 { 134 GElf_Sym *symp; 135 const char *strp; 136 int i; 137 138 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 139 strp = ef->ddbstrtab + symp->st_name; 140 if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) { 141 *sym = symp; 142 return (0); 143 } 144 } 145 return (ENOENT); 146 } 147 148 static int 149 ef_obj_lookup_set(elf_file_t ef, const char *name, GElf_Addr *startp, 150 GElf_Addr *stopp, long *countp) 151 { 152 int i; 153 154 for (i = 0; i < ef->nprogtab; i++) { 155 if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) && 156 strcmp(ef->progtab[i].name + 4, name) == 0) { 157 *startp = ef->progtab[i].addr; 158 *stopp = ef->progtab[i].addr + ef->progtab[i].size; 159 *countp = (*stopp - *startp) / 160 elf_pointer_size(ef->ef_efile); 161 return (0); 162 } 163 } 164 return (ESRCH); 165 } 166 167 static GElf_Addr 168 ef_obj_symaddr(elf_file_t ef, GElf_Size symidx) 169 { 170 const GElf_Sym *sym; 171 172 if (symidx >= ef->ddbsymcnt) 173 return (0); 174 sym = ef->ddbsymtab + symidx; 175 176 if (sym->st_shndx != SHN_UNDEF) 177 return (sym->st_value); 178 return (0); 179 } 180 181 static int 182 ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address, size_t len, void *dest) 183 { 184 GElf_Off secofs; 185 GElf_Rel *r; 186 GElf_Rela *a; 187 GElf_Addr secbase, dataoff; 188 int error, i, sec; 189 190 /* Find out which section contains the data. */ 191 sec = -1; 192 for (i = 0; i < ef->nprogtab; i++) { 193 if (address < ef->progtab[i].addr) 194 continue; 195 196 dataoff = address - ef->progtab[i].addr; 197 if (dataoff + len > ef->progtab[i].size) 198 continue; 199 200 sec = ef->progtab[i].sec; 201 secbase = ef->progtab[i].addr; 202 secofs = ef->progtab[i].offset; 203 break; 204 } 205 206 if (sec == -1) { 207 if (ef->ef_verbose) 208 warnx("ef_obj_seg_read_rel(%s): bad address (%jx)", 209 ef->ef_name, (uintmax_t)address); 210 return (EFAULT); 211 } 212 213 if (secofs == (GElf_Off)-1) { 214 memset(dest, 0, len); 215 } else { 216 error = elf_read_raw_data(ef->ef_efile, secofs + dataoff, dest, 217 len); 218 if (error != 0) 219 return (error); 220 } 221 222 /* Now do the relocations. */ 223 for (i = 0; i < ef->nrel; i++) { 224 if (ef->reltab[i].sec != sec) 225 continue; 226 for (r = ef->reltab[i].rel; 227 r < &ef->reltab[i].rel[ef->reltab[i].nrel]; r++) { 228 error = elf_reloc(ef->ef_efile, r, ELF_T_REL, secbase, 229 address, len, dest); 230 if (error != 0) 231 return (error); 232 } 233 } 234 for (i = 0; i < ef->nrela; i++) { 235 if (ef->relatab[i].sec != sec) 236 continue; 237 for (a = ef->relatab[i].rela; 238 a < &ef->relatab[i].rela[ef->relatab[i].nrela]; a++) { 239 error = elf_reloc(ef->ef_efile, a, ELF_T_RELA, secbase, 240 address, len, dest); 241 if (error != 0) 242 return (error); 243 } 244 } 245 return (0); 246 } 247 248 static int 249 ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address, size_t len, char *dest) 250 { 251 GElf_Off ofs; 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 return (elf_read_raw_string(ef->ef_efile, ofs, dest, len)); 262 } 263 264 int 265 ef_obj_open(struct elf_file *efile, int verbose) 266 { 267 elf_file_t ef; 268 GElf_Ehdr *hdr; 269 GElf_Shdr *shdr; 270 GElf_Sym *es; 271 GElf_Addr mapbase; 272 size_t i, nshdr; 273 int error, pb, ra, rl; 274 int j, nsym, symstrindex, symtabindex; 275 276 hdr = &efile->ef_hdr; 277 if (hdr->e_type != ET_REL || hdr->e_shnum == 0 || hdr->e_shoff == 0 || 278 hdr->e_shentsize != elf_object_size(efile, ELF_T_SHDR)) 279 return (EFTYPE); 280 281 ef = calloc(1, sizeof(*ef)); 282 if (ef == NULL) 283 return (errno); 284 285 efile->ef_ef = ef; 286 efile->ef_ops = &ef_obj_file_ops; 287 288 ef->ef_verbose = verbose; 289 ef->ef_name = strdup(efile->ef_filename); 290 ef->ef_efile = efile; 291 292 error = elf_read_shdrs(efile, &nshdr, &shdr); 293 if (error != 0) { 294 shdr = NULL; 295 goto out; 296 } 297 298 /* Scan the section headers for information and table sizing. */ 299 nsym = 0; 300 symtabindex = -1; 301 symstrindex = -1; 302 for (i = 0; i < nshdr; i++) { 303 switch (shdr[i].sh_type) { 304 case SHT_PROGBITS: 305 case SHT_NOBITS: 306 ef->nprogtab++; 307 break; 308 case SHT_SYMTAB: 309 nsym++; 310 symtabindex = i; 311 symstrindex = shdr[i].sh_link; 312 break; 313 case SHT_REL: 314 ef->nrel++; 315 break; 316 case SHT_RELA: 317 ef->nrela++; 318 break; 319 case SHT_STRTAB: 320 break; 321 } 322 } 323 324 if (ef->nprogtab == 0) { 325 warnx("%s: file has no contents", ef->ef_name); 326 goto out; 327 } 328 if (nsym != 1) { 329 warnx("%s: file has no valid symbol table", ef->ef_name); 330 goto out; 331 } 332 if (symstrindex < 0 || symstrindex > nshdr || 333 shdr[symstrindex].sh_type != SHT_STRTAB) { 334 warnx("%s: file has invalid symbol strings", ef->ef_name); 335 goto out; 336 } 337 338 /* Allocate space for tracking the load chunks */ 339 if (ef->nprogtab != 0) 340 ef->progtab = calloc(ef->nprogtab, sizeof(*ef->progtab)); 341 if (ef->nrel != 0) 342 ef->reltab = calloc(ef->nrel, sizeof(*ef->reltab)); 343 if (ef->nrela != 0) 344 ef->relatab = calloc(ef->nrela, sizeof(*ef->relatab)); 345 if ((ef->nprogtab != 0 && ef->progtab == NULL) || 346 (ef->nrel != 0 && ef->reltab == NULL) || 347 (ef->nrela != 0 && ef->relatab == NULL)) { 348 warnx("malloc failed"); 349 error = ENOMEM; 350 goto out; 351 } 352 353 if (elf_read_symbols(efile, symtabindex, &ef->ddbsymcnt, 354 &ef->ddbsymtab) != 0) { 355 warnx("elf_read_symbols failed"); 356 goto out; 357 } 358 359 if (elf_read_string_table(efile, &shdr[symstrindex], &ef->ddbstrcnt, 360 &ef->ddbstrtab) != 0) { 361 warnx("elf_read_string_table failed"); 362 goto out; 363 } 364 365 /* Do we have a string table for the section names? */ 366 if (hdr->e_shstrndx != 0 && 367 shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) { 368 if (elf_read_string_table(efile, &shdr[hdr->e_shstrndx], 369 &ef->shstrcnt, &ef->shstrtab) != 0) { 370 warnx("elf_read_string_table failed"); 371 goto out; 372 } 373 } 374 375 /* 376 * Now allocate address space for code/data(progbits) and 377 * bss(nobits) and allocate space for and load relocs. 378 */ 379 pb = 0; 380 rl = 0; 381 ra = 0; 382 mapbase = 0; 383 for (i = 0; i < nshdr; i++) { 384 switch (shdr[i].sh_type) { 385 case SHT_PROGBITS: 386 case SHT_NOBITS: 387 mapbase = roundup2(mapbase, shdr[i].sh_addralign); 388 ef->progtab[pb].addr = mapbase; 389 if (shdr[i].sh_type == SHT_PROGBITS) { 390 ef->progtab[pb].name = "<<PROGBITS>>"; 391 ef->progtab[pb].offset = shdr[i].sh_offset; 392 } else { 393 ef->progtab[pb].name = "<<NOBITS>>"; 394 ef->progtab[pb].offset = (GElf_Off)-1; 395 } 396 ef->progtab[pb].size = shdr[i].sh_size; 397 ef->progtab[pb].sec = i; 398 if (ef->shstrtab && shdr[i].sh_name != 0) 399 ef->progtab[pb].name = 400 ef->shstrtab + shdr[i].sh_name; 401 402 /* Update all symbol values with the offset. */ 403 for (j = 0; j < ef->ddbsymcnt; j++) { 404 es = &ef->ddbsymtab[j]; 405 if (es->st_shndx != i) 406 continue; 407 es->st_value += ef->progtab[pb].addr; 408 } 409 mapbase += shdr[i].sh_size; 410 pb++; 411 break; 412 case SHT_REL: 413 ef->reltab[rl].sec = shdr[i].sh_info; 414 if (elf_read_rel(efile, i, &ef->reltab[rl].nrel, 415 &ef->reltab[rl].rel) != 0) { 416 warnx("elf_read_rel failed"); 417 goto out; 418 } 419 rl++; 420 break; 421 case SHT_RELA: 422 ef->relatab[ra].sec = shdr[i].sh_info; 423 if (elf_read_rela(efile, i, &ef->relatab[ra].nrela, 424 &ef->relatab[ra].rela) != 0) { 425 warnx("elf_read_rela failed"); 426 goto out; 427 } 428 ra++; 429 break; 430 } 431 } 432 error = 0; 433 out: 434 free(shdr); 435 if (error != 0) 436 ef_obj_close(ef); 437 return (error); 438 } 439 440 static void 441 ef_obj_close(elf_file_t ef) 442 { 443 int i; 444 445 if (ef->ef_name) 446 free(ef->ef_name); 447 if (ef->nprogtab != 0) 448 free(ef->progtab); 449 if (ef->nrel != 0) { 450 for (i = 0; i < ef->nrel; i++) 451 if (ef->reltab[i].rel != NULL) 452 free(ef->reltab[i].rel); 453 free(ef->reltab); 454 } 455 if (ef->nrela != 0) { 456 for (i = 0; i < ef->nrela; i++) 457 if (ef->relatab[i].rela != NULL) 458 free(ef->relatab[i].rela); 459 free(ef->relatab); 460 } 461 if (ef->ddbsymtab != NULL) 462 free(ef->ddbsymtab); 463 if (ef->ddbstrtab != NULL) 464 free(ef->ddbstrtab); 465 if (ef->shstrtab != NULL) 466 free(ef->shstrtab); 467 ef->ef_efile->ef_ops = NULL; 468 ef->ef_efile->ef_ef = NULL; 469 free(ef); 470 } 471