lib/libkldelf/ef_obj.c

   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, bool see_local);
 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     bool see_local)
 134 {
 135         GElf_Sym *symp;
 136         const char *strp;
 137         int i;
 138
 139         for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
 140                 strp = ef->ddbstrtab + symp->st_name;
 141                 if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) {
 142                         if (see_local ||
 143                             GELF_ST_BIND(symp->st_info) != STB_LOCAL) {
 144                                 *sym = symp;
 145                                 return (0);
 146                         }
 147                 }
 148         }
 149         return (ENOENT);
 150 }
 151
 152 static int
 153 ef_obj_lookup_set(elf_file_t ef, const char *name, GElf_Addr *startp,
 154     GElf_Addr *stopp, long *countp)
 155 {
 156         int i;
 157
 158         for (i = 0; i < ef->nprogtab; i++) {
 159                 if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) &&
 160                     strcmp(ef->progtab[i].name + 4, name) == 0) {
 161                         *startp = ef->progtab[i].addr;
 162                         *stopp = ef->progtab[i].addr + ef->progtab[i].size;
 163                         *countp = (*stopp - *startp) /
 164                             elf_pointer_size(ef->ef_efile);
 165                         return (0);
 166                 }
 167         }
 168         return (ESRCH);
 169 }
 170
 171 static GElf_Addr
 172 ef_obj_symaddr(elf_file_t ef, GElf_Size symidx)
 173 {
 174         const GElf_Sym *sym;
 175
 176         if (symidx >= ef->ddbsymcnt)
 177                 return (0);
 178         sym = ef->ddbsymtab + symidx;
 179
 180         if (sym->st_shndx != SHN_UNDEF)
 181                 return (sym->st_value);
 182         return (0);
 183 }
 184
 185 static int
 186 ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address, size_t len, void *dest)
 187 {
 188         GElf_Off secofs;
 189         GElf_Rel *r;
 190         GElf_Rela *a;
 191         GElf_Addr secbase, dataoff;
 192         int error, i, sec;
 193
 194         /* Find out which section contains the data. */
 195         sec = -1;
 196         for (i = 0; i < ef->nprogtab; i++) {
 197                 if (address < ef->progtab[i].addr)
 198                         continue;
 199
 200                 dataoff = address - ef->progtab[i].addr;
 201                 if (dataoff + len > ef->progtab[i].size)
 202                         continue;
 203
 204                 sec = ef->progtab[i].sec;
 205                 secbase = ef->progtab[i].addr;
 206                 secofs = ef->progtab[i].offset;
 207                 break;
 208         }
 209
 210         if (sec == -1) {
 211                 if (ef->ef_verbose)
 212                         warnx("ef_obj_seg_read_rel(%s): bad address (%jx)",
 213                             ef->ef_name, (uintmax_t)address);
 214                 return (EFAULT);
 215         }
 216
 217         if (secofs == (GElf_Off)-1) {
 218                 memset(dest, 0, len);
 219         } else {
 220                 error = elf_read_raw_data(ef->ef_efile, secofs + dataoff, dest,
 221                     len);
 222                 if (error != 0)
 223                         return (error);
 224         }
 225
 226         /* Now do the relocations. */
 227         for (i = 0; i < ef->nrel; i++) {
 228                 if (ef->reltab[i].sec != sec)
 229                         continue;
 230                 for (r = ef->reltab[i].rel;
 231                      r < &ef->reltab[i].rel[ef->reltab[i].nrel]; r++) {
 232                         error = elf_reloc(ef->ef_efile, r, ELF_T_REL, secbase,
 233                             address, len, dest);
 234                         if (error != 0)
 235                                 return (error);
 236                 }
 237         }
 238         for (i = 0; i < ef->nrela; i++) {
 239                 if (ef->relatab[i].sec != sec)
 240                         continue;
 241                 for (a = ef->relatab[i].rela;
 242                      a < &ef->relatab[i].rela[ef->relatab[i].nrela]; a++) {
 243                         error = elf_reloc(ef->ef_efile, a, ELF_T_RELA, secbase,
 244                             address, len, dest);
 245                         if (error != 0)
 246                                 return (error);
 247                 }
 248         }
 249         return (0);
 250 }
 251
 252 static int
 253 ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address, size_t len, char *dest)
 254 {
 255         GElf_Off ofs;
 256
 257         ofs = ef_obj_get_offset(ef, address);
 258         if (ofs == 0) {
 259                 if (ef->ef_verbose)
 260                         warnx("ef_obj_seg_read_string(%s): bad address (%jx)",
 261                             ef->ef_name, (uintmax_t)address);
 262                 return (EFAULT);
 263         }
 264
 265         return (elf_read_raw_string(ef->ef_efile, ofs, dest, len));
 266 }
 267
 268 int
 269 ef_obj_open(struct elf_file *efile, int verbose)
 270 {
 271         elf_file_t ef;
 272         GElf_Ehdr *hdr;
 273         GElf_Shdr *shdr;
 274         GElf_Sym *es;
 275         GElf_Addr mapbase;
 276         size_t i, nshdr;
 277         int error, pb, ra, rl;
 278         int j, nsym, symstrindex, symtabindex;
 279
 280         hdr = &efile->ef_hdr;
 281         if (hdr->e_type != ET_REL || hdr->e_shnum == 0 || hdr->e_shoff == 0 ||
 282             hdr->e_shentsize != elf_object_size(efile, ELF_T_SHDR))
 283                 return (EFTYPE);
 284
 285         ef = calloc(1, sizeof(*ef));
 286         if (ef == NULL)
 287                 return (errno);
 288
 289         efile->ef_ef = ef;
 290         efile->ef_ops = &ef_obj_file_ops;
 291
 292         ef->ef_verbose = verbose;
 293         ef->ef_name = strdup(efile->ef_filename);
 294         ef->ef_efile = efile;
 295
 296         error = elf_read_shdrs(efile, &nshdr, &shdr);
 297         if (error != 0) {
 298                 shdr = NULL;
 299                 goto out;
 300         }
 301
 302         /* Scan the section headers for information and table sizing. */
 303         nsym = 0;
 304         symtabindex = -1;
 305         symstrindex = -1;
 306         for (i = 0; i < nshdr; i++) {
 307                 switch (shdr[i].sh_type) {
 308                 case SHT_PROGBITS:
 309                 case SHT_NOBITS:
 310                         ef->nprogtab++;
 311                         break;
 312                 case SHT_SYMTAB:
 313                         nsym++;
 314                         symtabindex = i;
 315                         symstrindex = shdr[i].sh_link;
 316                         break;
 317                 case SHT_REL:
 318                         ef->nrel++;
 319                         break;
 320                 case SHT_RELA:
 321                         ef->nrela++;
 322                         break;
 323                 case SHT_STRTAB:
 324                         break;
 325                 }
 326         }
 327
 328         if (ef->nprogtab == 0) {
 329                 warnx("%s: file has no contents", ef->ef_name);
 330                 goto out;
 331         }
 332         if (nsym != 1) {
 333                 warnx("%s: file has no valid symbol table", ef->ef_name);
 334                 goto out;
 335         }
 336         if (symstrindex < 0 || symstrindex > nshdr ||
 337             shdr[symstrindex].sh_type != SHT_STRTAB) {
 338                 warnx("%s: file has invalid symbol strings", ef->ef_name);
 339                 goto out;
 340         }
 341
 342         /* Allocate space for tracking the load chunks */
 343         if (ef->nprogtab != 0)
 344                 ef->progtab = calloc(ef->nprogtab, sizeof(*ef->progtab));
 345         if (ef->nrel != 0)
 346                 ef->reltab = calloc(ef->nrel, sizeof(*ef->reltab));
 347         if (ef->nrela != 0)
 348                 ef->relatab = calloc(ef->nrela, sizeof(*ef->relatab));
 349         if ((ef->nprogtab != 0 && ef->progtab == NULL) ||
 350             (ef->nrel != 0 && ef->reltab == NULL) ||
 351             (ef->nrela != 0 && ef->relatab == NULL)) {
 352                 warnx("malloc failed");
 353                 error = ENOMEM;
 354                 goto out;
 355         }
 356
 357         if (elf_read_symbols(efile, symtabindex, &ef->ddbsymcnt,
 358             &ef->ddbsymtab) != 0) {
 359                 warnx("elf_read_symbols failed");
 360                 goto out;
 361         }
 362
 363         if (elf_read_string_table(efile, &shdr[symstrindex], &ef->ddbstrcnt,
 364             &ef->ddbstrtab) != 0) {
 365                 warnx("elf_read_string_table failed");
 366                 goto out;
 367         }
 368
 369         /* Do we have a string table for the section names?  */
 370         if (hdr->e_shstrndx != 0 &&
 371             shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) {
 372                 if (elf_read_string_table(efile, &shdr[hdr->e_shstrndx],
 373                     &ef->shstrcnt, &ef->shstrtab) != 0) {
 374                         warnx("elf_read_string_table failed");
 375                         goto out;
 376                 }
 377         }
 378
 379         /*
 380          * Now allocate address space for code/data(progbits) and
 381          * bss(nobits) and allocate space for and load relocs.
 382          */
 383         pb = 0;
 384         rl = 0;
 385         ra = 0;
 386         mapbase = 0;
 387         for (i = 0; i < nshdr; i++) {
 388                 switch (shdr[i].sh_type) {
 389                 case SHT_PROGBITS:
 390                 case SHT_NOBITS:
 391                         mapbase = roundup2(mapbase, shdr[i].sh_addralign);
 392                         ef->progtab[pb].addr = mapbase;
 393                         if (shdr[i].sh_type == SHT_PROGBITS) {
 394                                 ef->progtab[pb].name = "<<PROGBITS>>";
 395                                 ef->progtab[pb].offset = shdr[i].sh_offset;
 396                         } else {
 397                                 ef->progtab[pb].name = "<<NOBITS>>";
 398                                 ef->progtab[pb].offset = (GElf_Off)-1;
 399                         }
 400                         ef->progtab[pb].size = shdr[i].sh_size;
 401                         ef->progtab[pb].sec = i;
 402                         if (ef->shstrtab && shdr[i].sh_name != 0)
 403                                 ef->progtab[pb].name =
 404                                     ef->shstrtab + shdr[i].sh_name;
 405
 406                         /* Update all symbol values with the offset. */
 407                         for (j = 0; j < ef->ddbsymcnt; j++) {
 408                                 es = &ef->ddbsymtab[j];
 409                                 if (es->st_shndx != i)
 410                                         continue;
 411                                 es->st_value += ef->progtab[pb].addr;
 412                         }
 413                         mapbase += shdr[i].sh_size;
 414                         pb++;
 415                         break;
 416                 case SHT_REL:
 417                         ef->reltab[rl].sec = shdr[i].sh_info;
 418                         if (elf_read_rel(efile, i, &ef->reltab[rl].nrel,
 419                             &ef->reltab[rl].rel) != 0) {
 420                                 warnx("elf_read_rel failed");
 421                                 goto out;
 422                         }
 423                         rl++;
 424                         break;
 425                 case SHT_RELA:
 426                         ef->relatab[ra].sec = shdr[i].sh_info;
 427                         if (elf_read_rela(efile, i, &ef->relatab[ra].nrela,
 428                             &ef->relatab[ra].rela) != 0) {
 429                                 warnx("elf_read_rela failed");
 430                                 goto out;
 431                         }
 432                         ra++;
 433                         break;
 434                 }
 435         }
 436         error = 0;
 437 out:
 438         free(shdr);
 439         if (error != 0)
 440                 ef_obj_close(ef);
 441         return (error);
 442 }
 443
 444 static void
 445 ef_obj_close(elf_file_t ef)
 446 {
 447         int i;
 448
 449         if (ef->ef_name)
 450                 free(ef->ef_name);
 451         if (ef->nprogtab != 0)
 452                 free(ef->progtab);
 453         if (ef->nrel != 0) {
 454                 for (i = 0; i < ef->nrel; i++)
 455                         if (ef->reltab[i].rel != NULL)
 456                                 free(ef->reltab[i].rel);
 457                 free(ef->reltab);
 458         }
 459         if (ef->nrela != 0) {
 460                 for (i = 0; i < ef->nrela; i++)
 461                         if (ef->relatab[i].rela != NULL)
 462                                 free(ef->relatab[i].rela);
 463                 free(ef->relatab);
 464         }
 465         if (ef->ddbsymtab != NULL)
 466                 free(ef->ddbsymtab);
 467         if (ef->ddbstrtab != NULL)
 468                 free(ef->ddbstrtab);
 469         if (ef->shstrtab != NULL)
 470                 free(ef->shstrtab);
 471         ef->ef_efile->ef_ops = NULL;
 472         ef->ef_efile->ef_ef = NULL;
 473         free(ef);
 474 }