libkmod/libkmod-elf.c

   1 /*
   2  * libkmod - interface to kernel module operations
   3  *
   4  * Copyright (C) 2011-2013  ProFUSION embedded systems
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <assert.h>
  21 #include <elf.h>
  22 #include <errno.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25
  26 #include <shared/util.h>
  27
  28 #include "libkmod.h"
  29 #include "libkmod-internal.h"
  30
  31 enum kmod_elf_class {
  32         KMOD_ELF_32 = (1 << 1),
  33         KMOD_ELF_64 = (1 << 2),
  34         KMOD_ELF_LSB = (1 << 3),
  35         KMOD_ELF_MSB = (1 << 4)
  36 };
  37
  38 /* as defined in module-init-tools */
  39 struct kmod_modversion32 {
  40         uint32_t crc;
  41         char name[64 - sizeof(uint32_t)];
  42 };
  43
  44 struct kmod_modversion64 {
  45         uint64_t crc;
  46         char name[64 - sizeof(uint64_t)];
  47 };
  48
  49 struct kmod_elf {
  50         const uint8_t *memory;
  51         uint8_t *changed;
  52         uint64_t size;
  53         enum kmod_elf_class class;
  54         struct kmod_elf_header {
  55                 struct {
  56                         uint64_t offset;
  57                         uint16_t count;
  58                         uint16_t entry_size;
  59                 } section;
  60                 struct {
  61                         uint16_t section; /* index of the strings section */
  62                         uint64_t size;
  63                         uint64_t offset;
  64                         uint32_t nameoff; /* offset in strings itself */
  65                 } strings;
  66                 uint16_t machine;
  67         } header;
  68 };
  69
  70 //#define ENABLE_ELFDBG 1
  71
  72 #if defined(ENABLE_LOGGING) && defined(ENABLE_ELFDBG)
  73 #define ELFDBG(elf, ...)                        \
  74         _elf_dbg(elf, __FILE__, __LINE__, __func__, __VA_ARGS__);
  75
  76 static inline void _elf_dbg(const struct kmod_elf *elf, const char *fname, unsigned line, const char *func, const char *fmt, ...)
  77 {
  78         va_list args;
  79
  80         fprintf(stderr, "ELFDBG-%d%c: %s:%u %s() ",
  81                 (elf->class & KMOD_ELF_32) ? 32 : 64,
  82                 (elf->class & KMOD_ELF_MSB) ? 'M' : 'L',
  83                 fname, line, func);
  84         va_start(args, fmt);
  85         vfprintf(stderr, fmt, args);
  86         va_end(args);
  87 }
  88 #else
  89 #define ELFDBG(elf, ...)
  90 #endif
  91
  92
  93 static int elf_identify(const void *memory, uint64_t size)
  94 {
  95         const uint8_t *p = memory;
  96         int class = 0;
  97
  98         if (size <= EI_NIDENT || memcmp(p, ELFMAG, SELFMAG) != 0)
  99                 return -ENOEXEC;
 100
 101         switch (p[EI_CLASS]) {
 102         case ELFCLASS32:
 103                 if (size <= sizeof(Elf32_Ehdr))
 104                         return -EINVAL;
 105                 class |= KMOD_ELF_32;
 106                 break;
 107         case ELFCLASS64:
 108                 if (size <= sizeof(Elf64_Ehdr))
 109                         return -EINVAL;
 110                 class |= KMOD_ELF_64;
 111                 break;
 112         default:
 113                 return -EINVAL;
 114         }
 115
 116         switch (p[EI_DATA]) {
 117         case ELFDATA2LSB:
 118                 class |= KMOD_ELF_LSB;
 119                 break;
 120         case ELFDATA2MSB:
 121                 class |= KMOD_ELF_MSB;
 122                 break;
 123         default:
 124                 return -EINVAL;
 125         }
 126
 127         return class;
 128 }
 129
 130 static inline uint64_t elf_get_uint(const struct kmod_elf *elf, uint64_t offset, uint16_t size)
 131 {
 132         const uint8_t *p;
 133         uint64_t ret = 0;
 134         size_t i;
 135
 136         assert(size <= sizeof(uint64_t));
 137         assert(offset + size <= elf->size);
 138         if (offset + size > elf->size) {
 139                 ELFDBG(elf, "out of bounds: %"PRIu64" + %"PRIu16" = %"PRIu64"> %"PRIu64" (ELF size)\n",
 140                        offset, size, offset + size, elf->size);
 141                 return (uint64_t)-1;
 142         }
 143
 144         p = elf->memory + offset;
 145         if (elf->class & KMOD_ELF_MSB) {
 146                 for (i = 0; i < size; i++)
 147                         ret = (ret << 8) | p[i];
 148         } else {
 149                 for (i = 1; i <= size; i++)
 150                         ret = (ret << 8) | p[size - i];
 151         }
 152
 153         ELFDBG(elf, "size=%"PRIu16" offset=%"PRIu64" value=%"PRIu64"\n",
 154                size, offset, ret);
 155
 156         return ret;
 157 }
 158
 159 static inline int elf_set_uint(struct kmod_elf *elf, uint64_t offset, uint64_t size, uint64_t value)
 160 {
 161         uint8_t *p;
 162         size_t i;
 163
 164         ELFDBG(elf, "size=%"PRIu16" offset=%"PRIu64" value=%"PRIu64" write memory=%p\n",
 165                size, offset, value, elf->changed);
 166
 167         assert(size <= sizeof(uint64_t));
 168         assert(offset + size <= elf->size);
 169         if (offset + size > elf->size) {
 170                 ELFDBG(elf, "out of bounds: %"PRIu64" + %"PRIu16" = %"PRIu64"> %"PRIu64" (ELF size)\n",
 171                        offset, size, offset + size, elf->size);
 172                 return -1;
 173         }
 174
 175         if (elf->changed == NULL) {
 176                 elf->changed = malloc(elf->size);
 177                 if (elf->changed == NULL)
 178                         return -errno;
 179                 memcpy(elf->changed, elf->memory, elf->size);
 180                 elf->memory = elf->changed;
 181                 ELFDBG(elf, "copied memory to allow writing.\n");
 182         }
 183
 184         p = elf->changed + offset;
 185         if (elf->class & KMOD_ELF_MSB) {
 186                 for (i = 1; i <= size; i++) {
 187                         p[size - i] = value & 0xff;
 188                         value = (value & 0xffffffffffffff00) >> 8;
 189                 }
 190         } else {
 191                 for (i = 0; i < size; i++) {
 192                         p[i] = value & 0xff;
 193                         value = (value & 0xffffffffffffff00) >> 8;
 194                 }
 195         }
 196
 197         return 0;
 198 }
 199
 200 static inline const void *elf_get_mem(const struct kmod_elf *elf, uint64_t offset)
 201 {
 202         assert(offset < elf->size);
 203         if (offset >= elf->size) {
 204                 ELFDBG(elf, "out-of-bounds: %"PRIu64" >= %"PRIu64" (ELF size)\n",
 205                        offset, elf->size);
 206                 return NULL;
 207         }
 208         return elf->memory + offset;
 209 }
 210
 211 static inline const void *elf_get_section_header(const struct kmod_elf *elf, uint16_t idx)
 212 {
 213         assert(idx != SHN_UNDEF);
 214         assert(idx < elf->header.section.count);
 215         if (idx == SHN_UNDEF || idx >= elf->header.section.count) {
 216                 ELFDBG(elf, "invalid section number: %"PRIu16", last=%"PRIu16"\n",
 217                        idx, elf->header.section.count);
 218                 return NULL;
 219         }
 220         return elf_get_mem(elf, elf->header.section.offset +
 221                            (uint64_t)(idx * elf->header.section.entry_size));
 222 }
 223
 224 static inline int elf_get_section_info(const struct kmod_elf *elf, uint16_t idx, uint64_t *offset, uint64_t *size, uint32_t *nameoff)
 225 {
 226         const uint8_t *p = elf_get_section_header(elf, idx);
 227         uint64_t min_size, off = p - elf->memory;
 228
 229         if (p == NULL) {
 230                 ELFDBG(elf, "no section at %"PRIu16"\n", idx);
 231                 *offset = 0;
 232                 *size = 0;
 233                 *nameoff = 0;
 234                 return -EINVAL;
 235         }
 236
 237 #define READV(field) \
 238         elf_get_uint(elf, off + offsetof(typeof(*hdr), field), sizeof(hdr->field))
 239
 240         if (elf->class & KMOD_ELF_32) {
 241                 const Elf32_Shdr *hdr _unused_ = (const Elf32_Shdr *)p;
 242                 *size = READV(sh_size);
 243                 *offset = READV(sh_offset);
 244                 *nameoff = READV(sh_name);
 245         } else {
 246                 const Elf64_Shdr *hdr _unused_ = (const Elf64_Shdr *)p;
 247                 *size = READV(sh_size);
 248                 *offset = READV(sh_offset);
 249                 *nameoff = READV(sh_name);
 250         }
 251 #undef READV
 252
 253         if (addu64_overflow(*offset, *size, &min_size)
 254             || min_size > elf->size) {
 255                 ELFDBG(elf, "out-of-bounds: %"PRIu64" >= %"PRIu64" (ELF size)\n",
 256                        min_size, elf->size);
 257                 return -EINVAL;
 258         }
 259
 260         ELFDBG(elf, "section=%"PRIu16" is: offset=%"PRIu64" size=%"PRIu64" nameoff=%"PRIu32"\n",
 261                idx, *offset, *size, *nameoff);
 262
 263         return 0;
 264 }
 265
 266 static const char *elf_get_strings_section(const struct kmod_elf *elf, uint64_t *size)
 267 {
 268         *size = elf->header.strings.size;
 269         return elf_get_mem(elf, elf->header.strings.offset);
 270 }
 271
 272 struct kmod_elf *kmod_elf_new(const void *memory, off_t size)
 273 {
 274         struct kmod_elf *elf;
 275         uint64_t min_size;
 276         size_t shdrs_size, shdr_size;
 277         int class;
 278
 279         assert_cc(sizeof(uint16_t) == sizeof(Elf32_Half));
 280         assert_cc(sizeof(uint16_t) == sizeof(Elf64_Half));
 281         assert_cc(sizeof(uint32_t) == sizeof(Elf32_Word));
 282         assert_cc(sizeof(uint32_t) == sizeof(Elf64_Word));
 283
 284         class = elf_identify(memory, size);
 285         if (class < 0) {
 286                 errno = -class;
 287                 return NULL;
 288         }
 289
 290         elf = malloc(sizeof(struct kmod_elf));
 291         if (elf == NULL) {
 292                 return NULL;
 293         }
 294
 295         elf->memory = memory;
 296         elf->changed = NULL;
 297         elf->size = size;
 298         elf->class = class;
 299
 300 #define READV(field) \
 301         elf_get_uint(elf, offsetof(typeof(*hdr), field), sizeof(hdr->field))
 302
 303 #define LOAD_HEADER                                             \
 304         elf->header.section.offset = READV(e_shoff);            \
 305         elf->header.section.count = READV(e_shnum);             \
 306         elf->header.section.entry_size = READV(e_shentsize);    \
 307         elf->header.strings.section = READV(e_shstrndx);        \
 308         elf->header.machine = READV(e_machine)
 309         if (elf->class & KMOD_ELF_32) {
 310                 const Elf32_Ehdr *hdr _unused_ = elf_get_mem(elf, 0);
 311                 LOAD_HEADER;
 312                 shdr_size = sizeof(Elf32_Shdr);
 313         } else {
 314                 const Elf64_Ehdr *hdr _unused_ = elf_get_mem(elf, 0);
 315                 LOAD_HEADER;
 316                 shdr_size = sizeof(Elf64_Shdr);
 317         }
 318 #undef LOAD_HEADER
 319 #undef READV
 320
 321         ELFDBG(elf, "section: offset=%"PRIu64" count=%"PRIu16" entry_size=%"PRIu16" strings index=%"PRIu16"\n",
 322                elf->header.section.offset,
 323                elf->header.section.count,
 324                elf->header.section.entry_size,
 325                elf->header.strings.section);
 326
 327         if (elf->header.section.entry_size != shdr_size) {
 328                 ELFDBG(elf, "unexpected section entry size: %"PRIu16", expected %"PRIu16"\n",
 329                        elf->header.section.entry_size, shdr_size);
 330                 goto invalid;
 331         }
 332         shdrs_size = shdr_size * elf->header.section.count;
 333         if (addu64_overflow(shdrs_size, elf->header.section.offset, &min_size)
 334             || min_size > elf->size) {
 335                 ELFDBG(elf, "file is too short to hold sections\n");
 336                 goto invalid;
 337         }
 338
 339         if (elf_get_section_info(elf, elf->header.strings.section,
 340                                         &elf->header.strings.offset,
 341                                         &elf->header.strings.size,
 342                                         &elf->header.strings.nameoff) < 0) {
 343                 ELFDBG(elf, "could not get strings section\n");
 344                 goto invalid;
 345         } else {
 346                 uint64_t slen;
 347                 const char *s = elf_get_strings_section(elf, &slen);
 348                 if (slen == 0 || s[slen - 1] != '\0') {
 349                         ELFDBG(elf, "strings section does not ends with \\0\n");
 350                         goto invalid;
 351                 }
 352         }
 353
 354         return elf;
 355
 356 invalid:
 357         free(elf);
 358         errno = EINVAL;
 359         return NULL;
 360 }
 361
 362 void kmod_elf_unref(struct kmod_elf *elf)
 363 {
 364         free(elf->changed);
 365         free(elf);
 366 }
 367
 368 const void *kmod_elf_get_memory(const struct kmod_elf *elf)
 369 {
 370         return elf->memory;
 371 }
 372
 373 static int elf_find_section(const struct kmod_elf *elf, const char *section)
 374 {
 375         uint64_t nameslen;
 376         const char *names = elf_get_strings_section(elf, &nameslen);
 377         uint16_t i;
 378
 379         for (i = 1; i < elf->header.section.count; i++) {
 380                 uint64_t off, size;
 381                 uint32_t nameoff;
 382                 const char *n;
 383                 int err = elf_get_section_info(elf, i, &off, &size, &nameoff);
 384                 if (err < 0)
 385                         continue;
 386                 if (nameoff >= nameslen)
 387                         continue;
 388                 n = names + nameoff;
 389                 if (!streq(section, n))
 390                         continue;
 391
 392                 return i;
 393         }
 394
 395         return -ENOENT;
 396 }
 397
 398 int kmod_elf_get_section(const struct kmod_elf *elf, const char *section, const void **buf, uint64_t *buf_size)
 399 {
 400         uint64_t nameslen;
 401         const char *names = elf_get_strings_section(elf, &nameslen);
 402         uint16_t i;
 403
 404         *buf = NULL;
 405         *buf_size = 0;
 406
 407         for (i = 1; i < elf->header.section.count; i++) {
 408                 uint64_t off, size;
 409                 uint32_t nameoff;
 410                 const char *n;
 411                 int err = elf_get_section_info(elf, i, &off, &size, &nameoff);
 412                 if (err < 0)
 413                         continue;
 414                 if (nameoff >= nameslen)
 415                         continue;
 416                 n = names + nameoff;
 417                 if (!streq(section, n))
 418                         continue;
 419
 420                 *buf = elf_get_mem(elf, off);
 421                 *buf_size = size;
 422                 return 0;
 423         }
 424
 425         return -ENOENT;
 426 }
 427
 428 /* array will be allocated with strings in a single malloc, just free *array */
 429 int kmod_elf_get_strings(const struct kmod_elf *elf, const char *section, char ***array)
 430 {
 431         size_t i, j, count;
 432         uint64_t size;
 433         const void *buf;
 434         const char *strings;
 435         char *s, **a;
 436         int err;
 437
 438         *array = NULL;
 439
 440         err = kmod_elf_get_section(elf, section, &buf, &size);
 441         if (err < 0)
 442                 return err;
 443
 444         strings = buf;
 445         if (strings == NULL || size == 0)
 446                 return 0;
 447
 448         /* skip zero padding */
 449         while (strings[0] == '\0' && size > 1) {
 450                 strings++;
 451                 size--;
 452         }
 453
 454         if (size <= 1)
 455                 return 0;
 456
 457         for (i = 0, count = 0; i < size; ) {
 458                 if (strings[i] != '\0') {
 459                         i++;
 460                         continue;
 461                 }
 462
 463                 while (strings[i] == '\0' && i < size)
 464                         i++;
 465
 466                 count++;
 467         }
 468
 469         if (strings[i - 1] != '\0')
 470                 count++;
 471
 472         *array = a = malloc(size + 1 + sizeof(char *) * (count + 1));
 473         if (*array == NULL)
 474                 return -errno;
 475
 476         s = (char *)(a + count + 1);
 477         memcpy(s, strings, size);
 478
 479         /* make sure the last string is NULL-terminated */
 480         s[size] = '\0';
 481         a[count] = NULL;
 482         a[0] = s;
 483
 484         for (i = 0, j = 1; j < count && i < size; ) {
 485                 if (s[i] != '\0') {
 486                         i++;
 487                         continue;
 488                 }
 489
 490                 while (strings[i] == '\0' && i < size)
 491                         i++;
 492
 493                 a[j] = &s[i];
 494                 j++;
 495         }
 496
 497         return count;
 498 }
 499
 500 /* array will be allocated with strings in a single malloc, just free *array */
 501 int kmod_elf_get_modversions(const struct kmod_elf *elf, struct kmod_modversion **array)
 502 {
 503         size_t off, offcrc, slen;
 504         uint64_t size;
 505         struct kmod_modversion *a;
 506         const void *buf;
 507         char *itr;
 508         int i, count, err;
 509 #define MODVERSION_SEC_SIZE (sizeof(struct kmod_modversion64))
 510
 511         assert_cc(sizeof(struct kmod_modversion64) ==
 512                                         sizeof(struct kmod_modversion32));
 513
 514         if (elf->class & KMOD_ELF_32)
 515                 offcrc = sizeof(uint32_t);
 516         else
 517                 offcrc = sizeof(uint64_t);
 518
 519         *array = NULL;
 520
 521         err = kmod_elf_get_section(elf, "__versions", &buf, &size);
 522         if (err < 0)
 523                 return err;
 524
 525         if (buf == NULL || size == 0)
 526                 return 0;
 527
 528         if (size % MODVERSION_SEC_SIZE != 0)
 529                 return -EINVAL;
 530
 531         count = size / MODVERSION_SEC_SIZE;
 532
 533         off = (const uint8_t *)buf - elf->memory;
 534         slen = 0;
 535
 536         for (i = 0; i < count; i++, off += MODVERSION_SEC_SIZE) {
 537                 const char *symbol = elf_get_mem(elf, off + offcrc);
 538
 539                 if (symbol[0] == '.')
 540                         symbol++;
 541
 542                 slen += strlen(symbol) + 1;
 543         }
 544
 545         *array = a = malloc(sizeof(struct kmod_modversion) * count + slen);
 546         if (*array == NULL)
 547                 return -errno;
 548
 549         itr = (char *)(a + count);
 550         off = (const uint8_t *)buf - elf->memory;
 551
 552         for (i = 0; i < count; i++, off += MODVERSION_SEC_SIZE) {
 553                 uint64_t crc = elf_get_uint(elf, off, offcrc);
 554                 const char *symbol = elf_get_mem(elf, off + offcrc);
 555                 size_t symbollen;
 556
 557                 if (symbol[0] == '.')
 558                         symbol++;
 559
 560                 a[i].crc = crc;
 561                 a[i].bind = KMOD_SYMBOL_UNDEF;
 562                 a[i].symbol = itr;
 563                 symbollen = strlen(symbol) + 1;
 564                 memcpy(itr, symbol, symbollen);
 565                 itr += symbollen;
 566         }
 567
 568         return count;
 569 }
 570
 571 int kmod_elf_strip_section(struct kmod_elf *elf, const char *section)
 572 {
 573         uint64_t off, size;
 574         const void *buf;
 575         int idx = elf_find_section(elf, section);
 576         uint64_t val;
 577
 578         if (idx < 0)
 579                 return idx;
 580
 581         buf = elf_get_section_header(elf, idx);
 582         off = (const uint8_t *)buf - elf->memory;
 583
 584         if (elf->class & KMOD_ELF_32) {
 585                 off += offsetof(Elf32_Shdr, sh_flags);
 586                 size = sizeof(((Elf32_Shdr *)buf)->sh_flags);
 587         } else {
 588                 off += offsetof(Elf64_Shdr, sh_flags);
 589                 size = sizeof(((Elf64_Shdr *)buf)->sh_flags);
 590         }
 591
 592         val = elf_get_uint(elf, off, size);
 593         val &= ~(uint64_t)SHF_ALLOC;
 594
 595         return elf_set_uint(elf, off, size, val);
 596 }
 597
 598 int kmod_elf_strip_vermagic(struct kmod_elf *elf)
 599 {
 600         uint64_t i, size;
 601         const void *buf;
 602         const char *strings;
 603         int err;
 604
 605         err = kmod_elf_get_section(elf, ".modinfo", &buf, &size);
 606         if (err < 0)
 607                 return err;
 608         strings = buf;
 609         if (strings == NULL || size == 0)
 610                 return 0;
 611
 612         /* skip zero padding */
 613         while (strings[0] == '\0' && size > 1) {
 614                 strings++;
 615                 size--;
 616         }
 617         if (size <= 1)
 618                 return 0;
 619
 620         for (i = 0; i < size; i++) {
 621                 const char *s;
 622                 size_t off, len;
 623
 624                 if (strings[i] == '\0')
 625                         continue;
 626                 if (i + 1 >= size)
 627                         continue;
 628
 629                 s = strings + i;
 630                 len = sizeof("vermagic=") - 1;
 631                 if (i + len >= size)
 632                         continue;
 633                 if (strncmp(s, "vermagic=", len) != 0) {
 634                         i += strlen(s);
 635                         continue;
 636                 }
 637                 off = (const uint8_t *)s - elf->memory;
 638
 639                 if (elf->changed == NULL) {
 640                         elf->changed = malloc(elf->size);
 641                         if (elf->changed == NULL)
 642                                 return -errno;
 643                         memcpy(elf->changed, elf->memory, elf->size);
 644                         elf->memory = elf->changed;
 645                         ELFDBG(elf, "copied memory to allow writing.\n");
 646                 }
 647
 648                 len = strlen(s);
 649                 ELFDBG(elf, "clear .modinfo vermagic \"%s\" (%zd bytes)\n",
 650                        s, len);
 651                 memset(elf->changed + off, '\0', len);
 652                 return 0;
 653         }
 654
 655         ELFDBG(elf, "no vermagic found in .modinfo\n");
 656         return -ENOENT;
 657 }
 658
 659
 660 static int kmod_elf_get_symbols_symtab(const struct kmod_elf *elf, struct kmod_modversion **array)
 661 {
 662         uint64_t i, last, size;
 663         const void *buf;
 664         const char *strings;
 665         char *itr;
 666         struct kmod_modversion *a;
 667         int count, err;
 668
 669         *array = NULL;
 670
 671         err = kmod_elf_get_section(elf, "__ksymtab_strings", &buf, &size);
 672         if (err < 0)
 673                 return err;
 674         strings = buf;
 675         if (strings == NULL || size == 0)
 676                 return 0;
 677
 678         /* skip zero padding */
 679         while (strings[0] == '\0' && size > 1) {
 680                 strings++;
 681                 size--;
 682         }
 683         if (size <= 1)
 684                 return 0;
 685
 686         last = 0;
 687         for (i = 0, count = 0; i < size; i++) {
 688                 if (strings[i] == '\0') {
 689                         if (last == i) {
 690                                 last = i + 1;
 691                                 continue;
 692                         }
 693                         count++;
 694                         last = i + 1;
 695                 }
 696         }
 697         if (strings[i - 1] != '\0')
 698                 count++;
 699
 700         *array = a = malloc(size + 1 + sizeof(struct kmod_modversion) * count);
 701         if (*array == NULL)
 702                 return -errno;
 703
 704         itr = (char *)(a + count);
 705         last = 0;
 706         for (i = 0, count = 0; i < size; i++) {
 707                 if (strings[i] == '\0') {
 708                         size_t slen = i - last;
 709                         if (last == i) {
 710                                 last = i + 1;
 711                                 continue;
 712                         }
 713                         a[count].crc = 0;
 714                         a[count].bind = KMOD_SYMBOL_GLOBAL;
 715                         a[count].symbol = itr;
 716                         memcpy(itr, strings + last, slen);
 717                         itr[slen] = '\0';
 718                         itr += slen + 1;
 719                         count++;
 720                         last = i + 1;
 721                 }
 722         }
 723         if (strings[i - 1] != '\0') {
 724                 size_t slen = i - last;
 725                 a[count].crc = 0;
 726                 a[count].bind = KMOD_SYMBOL_GLOBAL;
 727                 a[count].symbol = itr;
 728                 memcpy(itr, strings + last, slen);
 729                 itr[slen] = '\0';
 730                 count++;
 731         }
 732
 733         return count;
 734 }
 735
 736 static inline uint8_t kmod_symbol_bind_from_elf(uint8_t elf_value)
 737 {
 738         switch (elf_value) {
 739         case STB_LOCAL:
 740                 return KMOD_SYMBOL_LOCAL;
 741         case STB_GLOBAL:
 742                 return KMOD_SYMBOL_GLOBAL;
 743         case STB_WEAK:
 744                 return KMOD_SYMBOL_WEAK;
 745         default:
 746                 return KMOD_SYMBOL_NONE;
 747         }
 748 }
 749
 750 static uint64_t kmod_elf_resolve_crc(const struct kmod_elf *elf, uint64_t crc, uint16_t shndx)
 751 {
 752         int err;
 753         uint64_t off, size;
 754         uint32_t nameoff;
 755
 756         if (shndx == SHN_ABS || shndx == SHN_UNDEF)
 757                 return crc;
 758
 759         err = elf_get_section_info(elf, shndx, &off, &size, &nameoff);
 760         if (err < 0) {
 761                 ELFDBG("Cound not find section index %"PRIu16" for crc", shndx);
 762                 return (uint64_t)-1;
 763         }
 764
 765         if (crc > (size - sizeof(uint32_t))) {
 766                 ELFDBG("CRC offset %"PRIu64" is too big, section %"PRIu16" size is %"PRIu64"\n",
 767                        crc, shndx, size);
 768                 return (uint64_t)-1;
 769         }
 770
 771         crc = elf_get_uint(elf, off + crc, sizeof(uint32_t));
 772         return crc;
 773 }
 774
 775 /* array will be allocated with strings in a single malloc, just free *array */
 776 int kmod_elf_get_symbols(const struct kmod_elf *elf, struct kmod_modversion **array)
 777 {
 778         static const char crc_str[] = "__crc_";
 779         static const size_t crc_strlen = sizeof(crc_str) - 1;
 780         uint64_t strtablen, symtablen, str_off, sym_off;
 781         const void *strtab, *symtab;
 782         struct kmod_modversion *a;
 783         char *itr;
 784         size_t slen, symlen;
 785         int i, count, symcount, err;
 786
 787         err = kmod_elf_get_section(elf, ".strtab", &strtab, &strtablen);
 788         if (err < 0) {
 789                 ELFDBG(elf, "no .strtab found.\n");
 790                 goto fallback;
 791         }
 792
 793         err = kmod_elf_get_section(elf, ".symtab", &symtab, &symtablen);
 794         if (err < 0) {
 795                 ELFDBG(elf, "no .symtab found.\n");
 796                 goto fallback;
 797         }
 798
 799         if (elf->class & KMOD_ELF_32)
 800                 symlen = sizeof(Elf32_Sym);
 801         else
 802                 symlen = sizeof(Elf64_Sym);
 803
 804         if (symtablen % symlen != 0) {
 805                 ELFDBG(elf, "unexpected .symtab of length %"PRIu64", not multiple of %"PRIu64" as expected.\n", symtablen, symlen);
 806                 goto fallback;
 807         }
 808
 809         symcount = symtablen / symlen;
 810         count = 0;
 811         slen = 0;
 812         str_off = (const uint8_t *)strtab - elf->memory;
 813         sym_off = (const uint8_t *)symtab - elf->memory + symlen;
 814         for (i = 1; i < symcount; i++, sym_off += symlen) {
 815                 const char *name;
 816                 uint32_t name_off;
 817
 818 #define READV(field)                                                    \
 819                 elf_get_uint(elf, sym_off + offsetof(typeof(*s), field),\
 820                              sizeof(s->field))
 821                 if (elf->class & KMOD_ELF_32) {
 822                         Elf32_Sym *s;
 823                         name_off = READV(st_name);
 824                 } else {
 825                         Elf64_Sym *s;
 826                         name_off = READV(st_name);
 827                 }
 828 #undef READV
 829                 if (name_off >= strtablen) {
 830                         ELFDBG(elf, ".strtab is %"PRIu64" bytes, but .symtab entry %d wants to access offset %"PRIu32".\n", strtablen, i, name_off);
 831                         goto fallback;
 832                 }
 833
 834                 name = elf_get_mem(elf, str_off + name_off);
 835
 836                 if (strncmp(name, crc_str, crc_strlen) != 0)
 837                         continue;
 838                 slen += strlen(name + crc_strlen) + 1;
 839                 count++;
 840         }
 841
 842         if (count == 0)
 843                 goto fallback;
 844
 845         *array = a = malloc(sizeof(struct kmod_modversion) * count + slen);
 846         if (*array == NULL)
 847                 return -errno;
 848
 849         itr = (char *)(a + count);
 850         count = 0;
 851         str_off = (const uint8_t *)strtab - elf->memory;
 852         sym_off = (const uint8_t *)symtab - elf->memory + symlen;
 853         for (i = 1; i < symcount; i++, sym_off += symlen) {
 854                 const char *name;
 855                 uint32_t name_off;
 856                 uint64_t crc;
 857                 uint8_t info, bind;
 858                 uint16_t shndx;
 859
 860 #define READV(field)                                                    \
 861                 elf_get_uint(elf, sym_off + offsetof(typeof(*s), field),\
 862                              sizeof(s->field))
 863                 if (elf->class & KMOD_ELF_32) {
 864                         Elf32_Sym *s;
 865                         name_off = READV(st_name);
 866                         crc = READV(st_value);
 867                         info = READV(st_info);
 868                         shndx = READV(st_shndx);
 869                 } else {
 870                         Elf64_Sym *s;
 871                         name_off = READV(st_name);
 872                         crc = READV(st_value);
 873                         info = READV(st_info);
 874                         shndx = READV(st_shndx);
 875                 }
 876 #undef READV
 877                 name = elf_get_mem(elf, str_off + name_off);
 878                 if (strncmp(name, crc_str, crc_strlen) != 0)
 879                         continue;
 880                 name += crc_strlen;
 881
 882                 if (elf->class & KMOD_ELF_32)
 883                         bind = ELF32_ST_BIND(info);
 884                 else
 885                         bind = ELF64_ST_BIND(info);
 886
 887                 a[count].crc = kmod_elf_resolve_crc(elf, crc, shndx);
 888                 a[count].bind = kmod_symbol_bind_from_elf(bind);
 889                 a[count].symbol = itr;
 890                 slen = strlen(name);
 891                 memcpy(itr, name, slen);
 892                 itr[slen] = '\0';
 893                 itr += slen + 1;
 894                 count++;
 895         }
 896         return count;
 897
 898 fallback:
 899         ELFDBG(elf, "Falling back to __ksymtab_strings!\n");
 900         return kmod_elf_get_symbols_symtab(elf, array);
 901 }
 902
 903 static int kmod_elf_crc_find(const struct kmod_elf *elf, const void *versions, uint64_t versionslen, const char *name, uint64_t *crc)
 904 {
 905         size_t verlen, crclen, off;
 906         uint64_t i;
 907
 908         if (elf->class & KMOD_ELF_32) {
 909                 struct kmod_modversion32 *mv;
 910                 verlen = sizeof(*mv);
 911                 crclen = sizeof(mv->crc);
 912         } else {
 913                 struct kmod_modversion64 *mv;
 914                 verlen = sizeof(*mv);
 915                 crclen = sizeof(mv->crc);
 916         }
 917
 918         off = (const uint8_t *)versions - elf->memory;
 919         for (i = 0; i < versionslen; i += verlen) {
 920                 const char *symbol = elf_get_mem(elf, off + i + crclen);
 921                 if (!streq(name, symbol))
 922                         continue;
 923                 *crc = elf_get_uint(elf, off + i, crclen);
 924                 return i / verlen;
 925         }
 926
 927         ELFDBG(elf, "could not find crc for symbol '%s'\n", name);
 928         *crc = 0;
 929         return -1;
 930 }
 931
 932 /* from module-init-tools:elfops_core.c */
 933 #ifndef STT_REGISTER
 934 #define STT_REGISTER    13              /* Global register reserved to app. */
 935 #endif
 936
 937 /* array will be allocated with strings in a single malloc, just free *array */
 938 int kmod_elf_get_dependency_symbols(const struct kmod_elf *elf, struct kmod_modversion **array)
 939 {
 940         uint64_t versionslen, strtablen, symtablen, str_off, sym_off, ver_off;
 941         const void *versions, *strtab, *symtab;
 942         struct kmod_modversion *a;
 943         char *itr;
 944         size_t slen, verlen, symlen, crclen;
 945         int i, count, symcount, vercount, err;
 946         bool handle_register_symbols;
 947         uint8_t *visited_versions;
 948         uint64_t *symcrcs;
 949
 950         err = kmod_elf_get_section(elf, "__versions", &versions, &versionslen);
 951         if (err < 0) {
 952                 versions = NULL;
 953                 versionslen = 0;
 954                 verlen = 0;
 955                 crclen = 0;
 956         } else {
 957                 if (elf->class & KMOD_ELF_32) {
 958                         struct kmod_modversion32 *mv;
 959                         verlen = sizeof(*mv);
 960                         crclen = sizeof(mv->crc);
 961                 } else {
 962                         struct kmod_modversion64 *mv;
 963                         verlen = sizeof(*mv);
 964                         crclen = sizeof(mv->crc);
 965                 }
 966                 if (versionslen % verlen != 0) {
 967                         ELFDBG(elf, "unexpected __versions of length %"PRIu64", not multiple of %zd as expected.\n", versionslen, verlen);
 968                         versions = NULL;
 969                         versionslen = 0;
 970                 }
 971         }
 972
 973         err = kmod_elf_get_section(elf, ".strtab", &strtab, &strtablen);
 974         if (err < 0) {
 975                 ELFDBG(elf, "no .strtab found.\n");
 976                 return -EINVAL;
 977         }
 978
 979         err = kmod_elf_get_section(elf, ".symtab", &symtab, &symtablen);
 980         if (err < 0) {
 981                 ELFDBG(elf, "no .symtab found.\n");
 982                 return -EINVAL;
 983         }
 984
 985         if (elf->class & KMOD_ELF_32)
 986                 symlen = sizeof(Elf32_Sym);
 987         else
 988                 symlen = sizeof(Elf64_Sym);
 989
 990         if (symtablen % symlen != 0) {
 991                 ELFDBG(elf, "unexpected .symtab of length %"PRIu64", not multiple of %"PRIu64" as expected.\n", symtablen, symlen);
 992                 return -EINVAL;
 993         }
 994
 995         if (versionslen == 0) {
 996                 vercount = 0;
 997                 visited_versions = NULL;
 998         } else {
 999                 vercount = versionslen / verlen;
1000                 visited_versions = calloc(vercount, sizeof(uint8_t));
1001                 if (visited_versions == NULL)
1002                         return -ENOMEM;
1003         }
1004
1005         handle_register_symbols = (elf->header.machine == EM_SPARC ||
1006                                    elf->header.machine == EM_SPARCV9);
1007
1008         symcount = symtablen / symlen;
1009         count = 0;
1010         slen = 0;
1011         str_off = (const uint8_t *)strtab - elf->memory;
1012         sym_off = (const uint8_t *)symtab - elf->memory + symlen;
1013
1014         symcrcs = calloc(symcount, sizeof(uint64_t));
1015         if (symcrcs == NULL) {
1016                 free(visited_versions);
1017                 return -ENOMEM;
1018         }
1019
1020         for (i = 1; i < symcount; i++, sym_off += symlen) {
1021                 const char *name;
1022                 uint64_t crc;
1023                 uint32_t name_off;
1024                 uint16_t secidx;
1025                 uint8_t info;
1026                 int idx;
1027
1028 #define READV(field)                                                    \
1029                 elf_get_uint(elf, sym_off + offsetof(typeof(*s), field),\
1030                              sizeof(s->field))
1031                 if (elf->class & KMOD_ELF_32) {
1032                         Elf32_Sym *s;
1033                         name_off = READV(st_name);
1034                         secidx = READV(st_shndx);
1035                         info = READV(st_info);
1036                 } else {
1037                         Elf64_Sym *s;
1038                         name_off = READV(st_name);
1039                         secidx = READV(st_shndx);
1040                         info = READV(st_info);
1041                 }
1042 #undef READV
1043                 if (secidx != SHN_UNDEF)
1044                         continue;
1045
1046                 if (handle_register_symbols) {
1047                         uint8_t type;
1048                         if (elf->class & KMOD_ELF_32)
1049                                 type = ELF32_ST_TYPE(info);
1050                         else
1051                                 type = ELF64_ST_TYPE(info);
1052
1053                         /* Not really undefined: sparc gcc 3.3 creates
1054                          * U references when you have global asm
1055                          * variables, to avoid anyone else misusing
1056                          * them.
1057                          */
1058                         if (type == STT_REGISTER)
1059                                 continue;
1060                 }
1061
1062                 if (name_off >= strtablen) {
1063                         ELFDBG(elf, ".strtab is %"PRIu64" bytes, but .symtab entry %d wants to access offset %"PRIu32".\n", strtablen, i, name_off);
1064                         free(visited_versions);
1065                         free(symcrcs);
1066                         return -EINVAL;
1067                 }
1068
1069                 name = elf_get_mem(elf, str_off + name_off);
1070                 if (name[0] == '\0') {
1071                         ELFDBG(elf, "empty symbol name at index %"PRIu64"\n", i);
1072                         continue;
1073                 }
1074
1075                 slen += strlen(name) + 1;
1076                 count++;
1077
1078                 idx = kmod_elf_crc_find(elf, versions, versionslen, name, &crc);
1079                 if (idx >= 0 && visited_versions != NULL)
1080                         visited_versions[idx] = 1;
1081                 symcrcs[i] = crc;
1082         }
1083
1084         if (visited_versions != NULL) {
1085                 /* module_layout/struct_module are not visited, but needed */
1086                 ver_off = (const uint8_t *)versions - elf->memory;
1087                 for (i = 0; i < vercount; i++) {
1088                         if (visited_versions[i] == 0) {
1089                                 const char *name;
1090                                 name = elf_get_mem(elf, ver_off + i * verlen + crclen);
1091                                 slen += strlen(name) + 1;
1092
1093                                 count++;
1094                         }
1095                 }
1096         }
1097
1098         if (count == 0) {
1099                 free(visited_versions);
1100                 free(symcrcs);
1101                 *array = NULL;
1102                 return 0;
1103         }
1104
1105         *array = a = malloc(sizeof(struct kmod_modversion) * count + slen);
1106         if (*array == NULL) {
1107                 free(visited_versions);
1108                 free(symcrcs);
1109                 return -errno;
1110         }
1111
1112         itr = (char *)(a + count);
1113         count = 0;
1114         str_off = (const uint8_t *)strtab - elf->memory;
1115         sym_off = (const uint8_t *)symtab - elf->memory + symlen;
1116         for (i = 1; i < symcount; i++, sym_off += symlen) {
1117                 const char *name;
1118                 uint64_t crc;
1119                 uint32_t name_off;
1120                 uint16_t secidx;
1121                 uint8_t info, bind;
1122
1123 #define READV(field)                                                    \
1124                 elf_get_uint(elf, sym_off + offsetof(typeof(*s), field),\
1125                              sizeof(s->field))
1126                 if (elf->class & KMOD_ELF_32) {
1127                         Elf32_Sym *s;
1128                         name_off = READV(st_name);
1129                         secidx = READV(st_shndx);
1130                         info = READV(st_info);
1131                 } else {
1132                         Elf64_Sym *s;
1133                         name_off = READV(st_name);
1134                         secidx = READV(st_shndx);
1135                         info = READV(st_info);
1136                 }
1137 #undef READV
1138                 if (secidx != SHN_UNDEF)
1139                         continue;
1140
1141                 if (handle_register_symbols) {
1142                         uint8_t type;
1143                         if (elf->class & KMOD_ELF_32)
1144                                 type = ELF32_ST_TYPE(info);
1145                         else
1146                                 type = ELF64_ST_TYPE(info);
1147
1148                         /* Not really undefined: sparc gcc 3.3 creates
1149                          * U references when you have global asm
1150                          * variables, to avoid anyone else misusing
1151                          * them.
1152                          */
1153                         if (type == STT_REGISTER)
1154                                 continue;
1155                 }
1156
1157                 name = elf_get_mem(elf, str_off + name_off);
1158                 if (name[0] == '\0') {
1159                         ELFDBG(elf, "empty symbol name at index %"PRIu64"\n", i);
1160                         continue;
1161                 }
1162
1163                 if (elf->class & KMOD_ELF_32)
1164                         bind = ELF32_ST_BIND(info);
1165                 else
1166                         bind = ELF64_ST_BIND(info);
1167                 if (bind == STB_WEAK)
1168                         bind = KMOD_SYMBOL_WEAK;
1169                 else
1170                         bind = KMOD_SYMBOL_UNDEF;
1171
1172                 slen = strlen(name);
1173                 crc = symcrcs[i];
1174
1175                 a[count].crc = crc;
1176                 a[count].bind = bind;
1177                 a[count].symbol = itr;
1178                 memcpy(itr, name, slen);
1179                 itr[slen] = '\0';
1180                 itr += slen + 1;
1181
1182                 count++;
1183         }
1184
1185         free(symcrcs);
1186
1187         if (visited_versions == NULL)
1188                 return count;
1189
1190         /* add unvisited (module_layout/struct_module) */
1191         ver_off = (const uint8_t *)versions - elf->memory;
1192         for (i = 0; i < vercount; i++) {
1193                 const char *name;
1194                 uint64_t crc;
1195
1196                 if (visited_versions[i] != 0)
1197                         continue;
1198
1199                 name = elf_get_mem(elf, ver_off + i * verlen + crclen);
1200                 slen = strlen(name);
1201                 crc = elf_get_uint(elf, ver_off + i * verlen, crclen);
1202
1203                 a[count].crc = crc;
1204                 a[count].bind = KMOD_SYMBOL_UNDEF;
1205                 a[count].symbol = itr;
1206                 memcpy(itr, name, slen);
1207                 itr[slen] = '\0';
1208                 itr += slen + 1;
1209
1210                 count++;
1211         }
1212         free(visited_versions);
1213         return count;
1214 }