kernel/kexec_file.c

   1 /*
   2  * kexec: kexec_file_load system call
   3  *
   4  * Copyright (C) 2014 Red Hat Inc.
   5  * Authors:
   6  *      Vivek Goyal <vgoyal@redhat.com>
   7  *
   8  * This source code is licensed under the GNU General Public License,
   9  * Version 2.  See the file COPYING for more details.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/capability.h>
  15 #include <linux/mm.h>
  16 #include <linux/file.h>
  17 #include <linux/slab.h>
  18 #include <linux/kexec.h>
  19 #include <linux/mutex.h>
  20 #include <linux/list.h>
  21 #include <crypto/hash.h>
  22 #include <crypto/sha.h>
  23 #include <linux/syscalls.h>
  24 #include <linux/vmalloc.h>
  25 #include "kexec_internal.h"
  26
  27 /*
  28  * Declare these symbols weak so that if architecture provides a purgatory,
  29  * these will be overridden.
  30  */
  31 char __weak kexec_purgatory[0];
  32 size_t __weak kexec_purgatory_size = 0;
  33
  34 static int kexec_calculate_store_digests(struct kimage *image);
  35
  36 static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len)
  37 {
  38         struct fd f = fdget(fd);
  39         int ret;
  40         struct kstat stat;
  41         loff_t pos;
  42         ssize_t bytes = 0;
  43
  44         if (!f.file)
  45                 return -EBADF;
  46
  47         ret = vfs_getattr(&f.file->f_path, &stat);
  48         if (ret)
  49                 goto out;
  50
  51         if (stat.size > INT_MAX) {
  52                 ret = -EFBIG;
  53                 goto out;
  54         }
  55
  56         /* Don't hand 0 to vmalloc, it whines. */
  57         if (stat.size == 0) {
  58                 ret = -EINVAL;
  59                 goto out;
  60         }
  61
  62         *buf = vmalloc(stat.size);
  63         if (!*buf) {
  64                 ret = -ENOMEM;
  65                 goto out;
  66         }
  67
  68         pos = 0;
  69         while (pos < stat.size) {
  70                 bytes = kernel_read(f.file, pos, (char *)(*buf) + pos,
  71                                     stat.size - pos);
  72                 if (bytes < 0) {
  73                         vfree(*buf);
  74                         ret = bytes;
  75                         goto out;
  76                 }
  77
  78                 if (bytes == 0)
  79                         break;
  80                 pos += bytes;
  81         }
  82
  83         if (pos != stat.size) {
  84                 ret = -EBADF;
  85                 vfree(*buf);
  86                 goto out;
  87         }
  88
  89         *buf_len = pos;
  90 out:
  91         fdput(f);
  92         return ret;
  93 }
  94
  95 /* Architectures can provide this probe function */
  96 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
  97                                          unsigned long buf_len)
  98 {
  99         return -ENOEXEC;
 100 }
 101
 102 void * __weak arch_kexec_kernel_image_load(struct kimage *image)
 103 {
 104         return ERR_PTR(-ENOEXEC);
 105 }
 106
 107 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
 108 {
 109         return -EINVAL;
 110 }
 111
 112 #ifdef CONFIG_KEXEC_VERIFY_SIG
 113 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
 114                                         unsigned long buf_len)
 115 {
 116         return -EKEYREJECTED;
 117 }
 118 #endif
 119
 120 /* Apply relocations of type RELA */
 121 int __weak
 122 arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 123                                  unsigned int relsec)
 124 {
 125         pr_err("RELA relocation unsupported.\n");
 126         return -ENOEXEC;
 127 }
 128
 129 /* Apply relocations of type REL */
 130 int __weak
 131 arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 132                              unsigned int relsec)
 133 {
 134         pr_err("REL relocation unsupported.\n");
 135         return -ENOEXEC;
 136 }
 137
 138 /*
 139  * Free up memory used by kernel, initrd, and command line. This is temporary
 140  * memory allocation which is not needed any more after these buffers have
 141  * been loaded into separate segments and have been copied elsewhere.
 142  */
 143 void kimage_file_post_load_cleanup(struct kimage *image)
 144 {
 145         struct purgatory_info *pi = &image->purgatory_info;
 146
 147         vfree(image->kernel_buf);
 148         image->kernel_buf = NULL;
 149
 150         vfree(image->initrd_buf);
 151         image->initrd_buf = NULL;
 152
 153         kfree(image->cmdline_buf);
 154         image->cmdline_buf = NULL;
 155
 156         vfree(pi->purgatory_buf);
 157         pi->purgatory_buf = NULL;
 158
 159         vfree(pi->sechdrs);
 160         pi->sechdrs = NULL;
 161
 162         /* See if architecture has anything to cleanup post load */
 163         arch_kimage_file_post_load_cleanup(image);
 164
 165         /*
 166          * Above call should have called into bootloader to free up
 167          * any data stored in kimage->image_loader_data. It should
 168          * be ok now to free it up.
 169          */
 170         kfree(image->image_loader_data);
 171         image->image_loader_data = NULL;
 172 }
 173
 174 /*
 175  * In file mode list of segments is prepared by kernel. Copy relevant
 176  * data from user space, do error checking, prepare segment list
 177  */
 178 static int
 179 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 180                              const char __user *cmdline_ptr,
 181                              unsigned long cmdline_len, unsigned flags)
 182 {
 183         int ret = 0;
 184         void *ldata;
 185
 186         ret = copy_file_from_fd(kernel_fd, &image->kernel_buf,
 187                                 &image->kernel_buf_len);
 188         if (ret)
 189                 return ret;
 190
 191         /* Call arch image probe handlers */
 192         ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
 193                                             image->kernel_buf_len);
 194
 195         if (ret)
 196                 goto out;
 197
 198 #ifdef CONFIG_KEXEC_VERIFY_SIG
 199         ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
 200                                            image->kernel_buf_len);
 201         if (ret) {
 202                 pr_debug("kernel signature verification failed.\n");
 203                 goto out;
 204         }
 205         pr_debug("kernel signature verification successful.\n");
 206 #endif
 207         /* It is possible that there no initramfs is being loaded */
 208         if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
 209                 ret = copy_file_from_fd(initrd_fd, &image->initrd_buf,
 210                                         &image->initrd_buf_len);
 211                 if (ret)
 212                         goto out;
 213         }
 214
 215         if (cmdline_len) {
 216                 image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL);
 217                 if (!image->cmdline_buf) {
 218                         ret = -ENOMEM;
 219                         goto out;
 220                 }
 221
 222                 ret = copy_from_user(image->cmdline_buf, cmdline_ptr,
 223                                      cmdline_len);
 224                 if (ret) {
 225                         ret = -EFAULT;
 226                         goto out;
 227                 }
 228
 229                 image->cmdline_buf_len = cmdline_len;
 230
 231                 /* command line should be a string with last byte null */
 232                 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
 233                         ret = -EINVAL;
 234                         goto out;
 235                 }
 236         }
 237
 238         /* Call arch image load handlers */
 239         ldata = arch_kexec_kernel_image_load(image);
 240
 241         if (IS_ERR(ldata)) {
 242                 ret = PTR_ERR(ldata);
 243                 goto out;
 244         }
 245
 246         image->image_loader_data = ldata;
 247 out:
 248         /* In case of error, free up all allocated memory in this function */
 249         if (ret)
 250                 kimage_file_post_load_cleanup(image);
 251         return ret;
 252 }
 253
 254 static int
 255 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
 256                        int initrd_fd, const char __user *cmdline_ptr,
 257                        unsigned long cmdline_len, unsigned long flags)
 258 {
 259         int ret;
 260         struct kimage *image;
 261         bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
 262
 263         image = do_kimage_alloc_init();
 264         if (!image)
 265                 return -ENOMEM;
 266
 267         image->file_mode = 1;
 268
 269         if (kexec_on_panic) {
 270                 /* Enable special crash kernel control page alloc policy. */
 271                 image->control_page = crashk_res.start;
 272                 image->type = KEXEC_TYPE_CRASH;
 273         }
 274
 275         ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
 276                                            cmdline_ptr, cmdline_len, flags);
 277         if (ret)
 278                 goto out_free_image;
 279
 280         ret = sanity_check_segment_list(image);
 281         if (ret)
 282                 goto out_free_post_load_bufs;
 283
 284         ret = -ENOMEM;
 285         image->control_code_page = kimage_alloc_control_pages(image,
 286                                            get_order(KEXEC_CONTROL_PAGE_SIZE));
 287         if (!image->control_code_page) {
 288                 pr_err("Could not allocate control_code_buffer\n");
 289                 goto out_free_post_load_bufs;
 290         }
 291
 292         if (!kexec_on_panic) {
 293                 image->swap_page = kimage_alloc_control_pages(image, 0);
 294                 if (!image->swap_page) {
 295                         pr_err("Could not allocate swap buffer\n");
 296                         goto out_free_control_pages;
 297                 }
 298         }
 299
 300         *rimage = image;
 301         return 0;
 302 out_free_control_pages:
 303         kimage_free_page_list(&image->control_pages);
 304 out_free_post_load_bufs:
 305         kimage_file_post_load_cleanup(image);
 306 out_free_image:
 307         kfree(image);
 308         return ret;
 309 }
 310
 311 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 312                 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
 313                 unsigned long, flags)
 314 {
 315         int ret = 0, i;
 316         struct kimage **dest_image, *image;
 317
 318         /* We only trust the superuser with rebooting the system. */
 319         if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 320                 return -EPERM;
 321
 322         /* Make sure we have a legal set of flags */
 323         if (flags != (flags & KEXEC_FILE_FLAGS))
 324                 return -EINVAL;
 325
 326         image = NULL;
 327
 328         if (!mutex_trylock(&kexec_mutex))
 329                 return -EBUSY;
 330
 331         dest_image = &kexec_image;
 332         if (flags & KEXEC_FILE_ON_CRASH)
 333                 dest_image = &kexec_crash_image;
 334
 335         if (flags & KEXEC_FILE_UNLOAD)
 336                 goto exchange;
 337
 338         /*
 339          * In case of crash, new kernel gets loaded in reserved region. It is
 340          * same memory where old crash kernel might be loaded. Free any
 341          * current crash dump kernel before we corrupt it.
 342          */
 343         if (flags & KEXEC_FILE_ON_CRASH)
 344                 kimage_free(xchg(&kexec_crash_image, NULL));
 345
 346         ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
 347                                      cmdline_len, flags);
 348         if (ret)
 349                 goto out;
 350
 351         ret = machine_kexec_prepare(image);
 352         if (ret)
 353                 goto out;
 354
 355         ret = kexec_calculate_store_digests(image);
 356         if (ret)
 357                 goto out;
 358
 359         for (i = 0; i < image->nr_segments; i++) {
 360                 struct kexec_segment *ksegment;
 361
 362                 ksegment = &image->segment[i];
 363                 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
 364                          i, ksegment->buf, ksegment->bufsz, ksegment->mem,
 365                          ksegment->memsz);
 366
 367                 ret = kimage_load_segment(image, &image->segment[i]);
 368                 if (ret)
 369                         goto out;
 370         }
 371
 372         kimage_terminate(image);
 373
 374         /*
 375          * Free up any temporary buffers allocated which are not needed
 376          * after image has been loaded
 377          */
 378         kimage_file_post_load_cleanup(image);
 379 exchange:
 380         image = xchg(dest_image, image);
 381 out:
 382         mutex_unlock(&kexec_mutex);
 383         kimage_free(image);
 384         return ret;
 385 }
 386
 387 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
 388                                     struct kexec_buf *kbuf)
 389 {
 390         struct kimage *image = kbuf->image;
 391         unsigned long temp_start, temp_end;
 392
 393         temp_end = min(end, kbuf->buf_max);
 394         temp_start = temp_end - kbuf->memsz;
 395
 396         do {
 397                 /* align down start */
 398                 temp_start = temp_start & (~(kbuf->buf_align - 1));
 399
 400                 if (temp_start < start || temp_start < kbuf->buf_min)
 401                         return 0;
 402
 403                 temp_end = temp_start + kbuf->memsz - 1;
 404
 405                 /*
 406                  * Make sure this does not conflict with any of existing
 407                  * segments
 408                  */
 409                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 410                         temp_start = temp_start - PAGE_SIZE;
 411                         continue;
 412                 }
 413
 414                 /* We found a suitable memory range */
 415                 break;
 416         } while (1);
 417
 418         /* If we are here, we found a suitable memory range */
 419         kbuf->mem = temp_start;
 420
 421         /* Success, stop navigating through remaining System RAM ranges */
 422         return 1;
 423 }
 424
 425 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
 426                                      struct kexec_buf *kbuf)
 427 {
 428         struct kimage *image = kbuf->image;
 429         unsigned long temp_start, temp_end;
 430
 431         temp_start = max(start, kbuf->buf_min);
 432
 433         do {
 434                 temp_start = ALIGN(temp_start, kbuf->buf_align);
 435                 temp_end = temp_start + kbuf->memsz - 1;
 436
 437                 if (temp_end > end || temp_end > kbuf->buf_max)
 438                         return 0;
 439                 /*
 440                  * Make sure this does not conflict with any of existing
 441                  * segments
 442                  */
 443                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 444                         temp_start = temp_start + PAGE_SIZE;
 445                         continue;
 446                 }
 447
 448                 /* We found a suitable memory range */
 449                 break;
 450         } while (1);
 451
 452         /* If we are here, we found a suitable memory range */
 453         kbuf->mem = temp_start;
 454
 455         /* Success, stop navigating through remaining System RAM ranges */
 456         return 1;
 457 }
 458
 459 static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
 460 {
 461         struct kexec_buf *kbuf = (struct kexec_buf *)arg;
 462         unsigned long sz = end - start + 1;
 463
 464         /* Returning 0 will take to next memory range */
 465         if (sz < kbuf->memsz)
 466                 return 0;
 467
 468         if (end < kbuf->buf_min || start > kbuf->buf_max)
 469                 return 0;
 470
 471         /*
 472          * Allocate memory top down with-in ram range. Otherwise bottom up
 473          * allocation.
 474          */
 475         if (kbuf->top_down)
 476                 return locate_mem_hole_top_down(start, end, kbuf);
 477         return locate_mem_hole_bottom_up(start, end, kbuf);
 478 }
 479
 480 /*
 481  * Helper function for placing a buffer in a kexec segment. This assumes
 482  * that kexec_mutex is held.
 483  */
 484 int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 485                      unsigned long memsz, unsigned long buf_align,
 486                      unsigned long buf_min, unsigned long buf_max,
 487                      bool top_down, unsigned long *load_addr)
 488 {
 489
 490         struct kexec_segment *ksegment;
 491         struct kexec_buf buf, *kbuf;
 492         int ret;
 493
 494         /* Currently adding segment this way is allowed only in file mode */
 495         if (!image->file_mode)
 496                 return -EINVAL;
 497
 498         if (image->nr_segments >= KEXEC_SEGMENT_MAX)
 499                 return -EINVAL;
 500
 501         /*
 502          * Make sure we are not trying to add buffer after allocating
 503          * control pages. All segments need to be placed first before
 504          * any control pages are allocated. As control page allocation
 505          * logic goes through list of segments to make sure there are
 506          * no destination overlaps.
 507          */
 508         if (!list_empty(&image->control_pages)) {
 509                 WARN_ON(1);
 510                 return -EINVAL;
 511         }
 512
 513         memset(&buf, 0, sizeof(struct kexec_buf));
 514         kbuf = &buf;
 515         kbuf->image = image;
 516         kbuf->buffer = buffer;
 517         kbuf->bufsz = bufsz;
 518
 519         kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
 520         kbuf->buf_align = max(buf_align, PAGE_SIZE);
 521         kbuf->buf_min = buf_min;
 522         kbuf->buf_max = buf_max;
 523         kbuf->top_down = top_down;
 524
 525         /* Walk the RAM ranges and allocate a suitable range for the buffer */
 526         if (image->type == KEXEC_TYPE_CRASH)
 527                 ret = walk_iomem_res("Crash kernel",
 528                                      IORESOURCE_MEM | IORESOURCE_BUSY,
 529                                      crashk_res.start, crashk_res.end, kbuf,
 530                                      locate_mem_hole_callback);
 531         else
 532                 ret = walk_system_ram_res(0, -1, kbuf,
 533                                           locate_mem_hole_callback);
 534         if (ret != 1) {
 535                 /* A suitable memory range could not be found for buffer */
 536                 return -EADDRNOTAVAIL;
 537         }
 538
 539         /* Found a suitable memory range */
 540         ksegment = &image->segment[image->nr_segments];
 541         ksegment->kbuf = kbuf->buffer;
 542         ksegment->bufsz = kbuf->bufsz;
 543         ksegment->mem = kbuf->mem;
 544         ksegment->memsz = kbuf->memsz;
 545         image->nr_segments++;
 546         *load_addr = ksegment->mem;
 547         return 0;
 548 }
 549
 550 /* Calculate and store the digest of segments */
 551 static int kexec_calculate_store_digests(struct kimage *image)
 552 {
 553         struct crypto_shash *tfm;
 554         struct shash_desc *desc;
 555         int ret = 0, i, j, zero_buf_sz, sha_region_sz;
 556         size_t desc_size, nullsz;
 557         char *digest;
 558         void *zero_buf;
 559         struct kexec_sha_region *sha_regions;
 560         struct purgatory_info *pi = &image->purgatory_info;
 561
 562         zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
 563         zero_buf_sz = PAGE_SIZE;
 564
 565         tfm = crypto_alloc_shash("sha256", 0, 0);
 566         if (IS_ERR(tfm)) {
 567                 ret = PTR_ERR(tfm);
 568                 goto out;
 569         }
 570
 571         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
 572         desc = kzalloc(desc_size, GFP_KERNEL);
 573         if (!desc) {
 574                 ret = -ENOMEM;
 575                 goto out_free_tfm;
 576         }
 577
 578         sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
 579         sha_regions = vzalloc(sha_region_sz);
 580         if (!sha_regions)
 581                 goto out_free_desc;
 582
 583         desc->tfm   = tfm;
 584         desc->flags = 0;
 585
 586         ret = crypto_shash_init(desc);
 587         if (ret < 0)
 588                 goto out_free_sha_regions;
 589
 590         digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
 591         if (!digest) {
 592                 ret = -ENOMEM;
 593                 goto out_free_sha_regions;
 594         }
 595
 596         for (j = i = 0; i < image->nr_segments; i++) {
 597                 struct kexec_segment *ksegment;
 598
 599                 ksegment = &image->segment[i];
 600                 /*
 601                  * Skip purgatory as it will be modified once we put digest
 602                  * info in purgatory.
 603                  */
 604                 if (ksegment->kbuf == pi->purgatory_buf)
 605                         continue;
 606
 607                 ret = crypto_shash_update(desc, ksegment->kbuf,
 608                                           ksegment->bufsz);
 609                 if (ret)
 610                         break;
 611
 612                 /*
 613                  * Assume rest of the buffer is filled with zero and
 614                  * update digest accordingly.
 615                  */
 616                 nullsz = ksegment->memsz - ksegment->bufsz;
 617                 while (nullsz) {
 618                         unsigned long bytes = nullsz;
 619
 620                         if (bytes > zero_buf_sz)
 621                                 bytes = zero_buf_sz;
 622                         ret = crypto_shash_update(desc, zero_buf, bytes);
 623                         if (ret)
 624                                 break;
 625                         nullsz -= bytes;
 626                 }
 627
 628                 if (ret)
 629                         break;
 630
 631                 sha_regions[j].start = ksegment->mem;
 632                 sha_regions[j].len = ksegment->memsz;
 633                 j++;
 634         }
 635
 636         if (!ret) {
 637                 ret = crypto_shash_final(desc, digest);
 638                 if (ret)
 639                         goto out_free_digest;
 640                 ret = kexec_purgatory_get_set_symbol(image, "sha_regions",
 641                                                 sha_regions, sha_region_sz, 0);
 642                 if (ret)
 643                         goto out_free_digest;
 644
 645                 ret = kexec_purgatory_get_set_symbol(image, "sha256_digest",
 646                                                 digest, SHA256_DIGEST_SIZE, 0);
 647                 if (ret)
 648                         goto out_free_digest;
 649         }
 650
 651 out_free_digest:
 652         kfree(digest);
 653 out_free_sha_regions:
 654         vfree(sha_regions);
 655 out_free_desc:
 656         kfree(desc);
 657 out_free_tfm:
 658         kfree(tfm);
 659 out:
 660         return ret;
 661 }
 662
 663 /* Actually load purgatory. Lot of code taken from kexec-tools */
 664 static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 665                                   unsigned long max, int top_down)
 666 {
 667         struct purgatory_info *pi = &image->purgatory_info;
 668         unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
 669         unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
 670         unsigned char *buf_addr, *src;
 671         int i, ret = 0, entry_sidx = -1;
 672         const Elf_Shdr *sechdrs_c;
 673         Elf_Shdr *sechdrs = NULL;
 674         void *purgatory_buf = NULL;
 675
 676         /*
 677          * sechdrs_c points to section headers in purgatory and are read
 678          * only. No modifications allowed.
 679          */
 680         sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
 681
 682         /*
 683          * We can not modify sechdrs_c[] and its fields. It is read only.
 684          * Copy it over to a local copy where one can store some temporary
 685          * data and free it at the end. We need to modify ->sh_addr and
 686          * ->sh_offset fields to keep track of permanent and temporary
 687          * locations of sections.
 688          */
 689         sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
 690         if (!sechdrs)
 691                 return -ENOMEM;
 692
 693         memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
 694
 695         /*
 696          * We seem to have multiple copies of sections. First copy is which
 697          * is embedded in kernel in read only section. Some of these sections
 698          * will be copied to a temporary buffer and relocated. And these
 699          * sections will finally be copied to their final destination at
 700          * segment load time.
 701          *
 702          * Use ->sh_offset to reflect section address in memory. It will
 703          * point to original read only copy if section is not allocatable.
 704          * Otherwise it will point to temporary copy which will be relocated.
 705          *
 706          * Use ->sh_addr to contain final address of the section where it
 707          * will go during execution time.
 708          */
 709         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 710                 if (sechdrs[i].sh_type == SHT_NOBITS)
 711                         continue;
 712
 713                 sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
 714                                                 sechdrs[i].sh_offset;
 715         }
 716
 717         /*
 718          * Identify entry point section and make entry relative to section
 719          * start.
 720          */
 721         entry = pi->ehdr->e_entry;
 722         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 723                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 724                         continue;
 725
 726                 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
 727                         continue;
 728
 729                 /* Make entry section relative */
 730                 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
 731                     ((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
 732                      pi->ehdr->e_entry)) {
 733                         entry_sidx = i;
 734                         entry -= sechdrs[i].sh_addr;
 735                         break;
 736                 }
 737         }
 738
 739         /* Determine how much memory is needed to load relocatable object. */
 740         buf_align = 1;
 741         bss_align = 1;
 742         buf_sz = 0;
 743         bss_sz = 0;
 744
 745         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 746                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 747                         continue;
 748
 749                 align = sechdrs[i].sh_addralign;
 750                 if (sechdrs[i].sh_type != SHT_NOBITS) {
 751                         if (buf_align < align)
 752                                 buf_align = align;
 753                         buf_sz = ALIGN(buf_sz, align);
 754                         buf_sz += sechdrs[i].sh_size;
 755                 } else {
 756                         /* bss section */
 757                         if (bss_align < align)
 758                                 bss_align = align;
 759                         bss_sz = ALIGN(bss_sz, align);
 760                         bss_sz += sechdrs[i].sh_size;
 761                 }
 762         }
 763
 764         /* Determine the bss padding required to align bss properly */
 765         bss_pad = 0;
 766         if (buf_sz & (bss_align - 1))
 767                 bss_pad = bss_align - (buf_sz & (bss_align - 1));
 768
 769         memsz = buf_sz + bss_pad + bss_sz;
 770
 771         /* Allocate buffer for purgatory */
 772         purgatory_buf = vzalloc(buf_sz);
 773         if (!purgatory_buf) {
 774                 ret = -ENOMEM;
 775                 goto out;
 776         }
 777
 778         if (buf_align < bss_align)
 779                 buf_align = bss_align;
 780
 781         /* Add buffer to segment list */
 782         ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
 783                                 buf_align, min, max, top_down,
 784                                 &pi->purgatory_load_addr);
 785         if (ret)
 786                 goto out;
 787
 788         /* Load SHF_ALLOC sections */
 789         buf_addr = purgatory_buf;
 790         load_addr = curr_load_addr = pi->purgatory_load_addr;
 791         bss_addr = load_addr + buf_sz + bss_pad;
 792
 793         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 794                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 795                         continue;
 796
 797                 align = sechdrs[i].sh_addralign;
 798                 if (sechdrs[i].sh_type != SHT_NOBITS) {
 799                         curr_load_addr = ALIGN(curr_load_addr, align);
 800                         offset = curr_load_addr - load_addr;
 801                         /* We already modifed ->sh_offset to keep src addr */
 802                         src = (char *) sechdrs[i].sh_offset;
 803                         memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
 804
 805                         /* Store load address and source address of section */
 806                         sechdrs[i].sh_addr = curr_load_addr;
 807
 808                         /*
 809                          * This section got copied to temporary buffer. Update
 810                          * ->sh_offset accordingly.
 811                          */
 812                         sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
 813
 814                         /* Advance to the next address */
 815                         curr_load_addr += sechdrs[i].sh_size;
 816                 } else {
 817                         bss_addr = ALIGN(bss_addr, align);
 818                         sechdrs[i].sh_addr = bss_addr;
 819                         bss_addr += sechdrs[i].sh_size;
 820                 }
 821         }
 822
 823         /* Update entry point based on load address of text section */
 824         if (entry_sidx >= 0)
 825                 entry += sechdrs[entry_sidx].sh_addr;
 826
 827         /* Make kernel jump to purgatory after shutdown */
 828         image->start = entry;
 829
 830         /* Used later to get/set symbol values */
 831         pi->sechdrs = sechdrs;
 832
 833         /*
 834          * Used later to identify which section is purgatory and skip it
 835          * from checksumming.
 836          */
 837         pi->purgatory_buf = purgatory_buf;
 838         return ret;
 839 out:
 840         vfree(sechdrs);
 841         vfree(purgatory_buf);
 842         return ret;
 843 }
 844
 845 static int kexec_apply_relocations(struct kimage *image)
 846 {
 847         int i, ret;
 848         struct purgatory_info *pi = &image->purgatory_info;
 849         Elf_Shdr *sechdrs = pi->sechdrs;
 850
 851         /* Apply relocations */
 852         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 853                 Elf_Shdr *section, *symtab;
 854
 855                 if (sechdrs[i].sh_type != SHT_RELA &&
 856                     sechdrs[i].sh_type != SHT_REL)
 857                         continue;
 858
 859                 /*
 860                  * For section of type SHT_RELA/SHT_REL,
 861                  * ->sh_link contains section header index of associated
 862                  * symbol table. And ->sh_info contains section header
 863                  * index of section to which relocations apply.
 864                  */
 865                 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
 866                     sechdrs[i].sh_link >= pi->ehdr->e_shnum)
 867                         return -ENOEXEC;
 868
 869                 section = &sechdrs[sechdrs[i].sh_info];
 870                 symtab = &sechdrs[sechdrs[i].sh_link];
 871
 872                 if (!(section->sh_flags & SHF_ALLOC))
 873                         continue;
 874
 875                 /*
 876                  * symtab->sh_link contain section header index of associated
 877                  * string table.
 878                  */
 879                 if (symtab->sh_link >= pi->ehdr->e_shnum)
 880                         /* Invalid section number? */
 881                         continue;
 882
 883                 /*
 884                  * Respective architecture needs to provide support for applying
 885                  * relocations of type SHT_RELA/SHT_REL.
 886                  */
 887                 if (sechdrs[i].sh_type == SHT_RELA)
 888                         ret = arch_kexec_apply_relocations_add(pi->ehdr,
 889                                                                sechdrs, i);
 890                 else if (sechdrs[i].sh_type == SHT_REL)
 891                         ret = arch_kexec_apply_relocations(pi->ehdr,
 892                                                            sechdrs, i);
 893                 if (ret)
 894                         return ret;
 895         }
 896
 897         return 0;
 898 }
 899
 900 /* Load relocatable purgatory object and relocate it appropriately */
 901 int kexec_load_purgatory(struct kimage *image, unsigned long min,
 902                          unsigned long max, int top_down,
 903                          unsigned long *load_addr)
 904 {
 905         struct purgatory_info *pi = &image->purgatory_info;
 906         int ret;
 907
 908         if (kexec_purgatory_size <= 0)
 909                 return -EINVAL;
 910
 911         if (kexec_purgatory_size < sizeof(Elf_Ehdr))
 912                 return -ENOEXEC;
 913
 914         pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
 915
 916         if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
 917             || pi->ehdr->e_type != ET_REL
 918             || !elf_check_arch(pi->ehdr)
 919             || pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
 920                 return -ENOEXEC;
 921
 922         if (pi->ehdr->e_shoff >= kexec_purgatory_size
 923             || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
 924             kexec_purgatory_size - pi->ehdr->e_shoff))
 925                 return -ENOEXEC;
 926
 927         ret = __kexec_load_purgatory(image, min, max, top_down);
 928         if (ret)
 929                 return ret;
 930
 931         ret = kexec_apply_relocations(image);
 932         if (ret)
 933                 goto out;
 934
 935         *load_addr = pi->purgatory_load_addr;
 936         return 0;
 937 out:
 938         vfree(pi->sechdrs);
 939         vfree(pi->purgatory_buf);
 940         return ret;
 941 }
 942
 943 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
 944                                             const char *name)
 945 {
 946         Elf_Sym *syms;
 947         Elf_Shdr *sechdrs;
 948         Elf_Ehdr *ehdr;
 949         int i, k;
 950         const char *strtab;
 951
 952         if (!pi->sechdrs || !pi->ehdr)
 953                 return NULL;
 954
 955         sechdrs = pi->sechdrs;
 956         ehdr = pi->ehdr;
 957
 958         for (i = 0; i < ehdr->e_shnum; i++) {
 959                 if (sechdrs[i].sh_type != SHT_SYMTAB)
 960                         continue;
 961
 962                 if (sechdrs[i].sh_link >= ehdr->e_shnum)
 963                         /* Invalid strtab section number */
 964                         continue;
 965                 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
 966                 syms = (Elf_Sym *)sechdrs[i].sh_offset;
 967
 968                 /* Go through symbols for a match */
 969                 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
 970                         if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
 971                                 continue;
 972
 973                         if (strcmp(strtab + syms[k].st_name, name) != 0)
 974                                 continue;
 975
 976                         if (syms[k].st_shndx == SHN_UNDEF ||
 977                             syms[k].st_shndx >= ehdr->e_shnum) {
 978                                 pr_debug("Symbol: %s has bad section index %d.\n",
 979                                                 name, syms[k].st_shndx);
 980                                 return NULL;
 981                         }
 982
 983                         /* Found the symbol we are looking for */
 984                         return &syms[k];
 985                 }
 986         }
 987
 988         return NULL;
 989 }
 990
 991 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
 992 {
 993         struct purgatory_info *pi = &image->purgatory_info;
 994         Elf_Sym *sym;
 995         Elf_Shdr *sechdr;
 996
 997         sym = kexec_purgatory_find_symbol(pi, name);
 998         if (!sym)
 999                 return ERR_PTR(-EINVAL);
1000
1001         sechdr = &pi->sechdrs[sym->st_shndx];
1002
1003         /*
1004          * Returns the address where symbol will finally be loaded after
1005          * kexec_load_segment()
1006          */
1007         return (void *)(sechdr->sh_addr + sym->st_value);
1008 }
1009
1010 /*
1011  * Get or set value of a symbol. If "get_value" is true, symbol value is
1012  * returned in buf otherwise symbol value is set based on value in buf.
1013  */
1014 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
1015                                    void *buf, unsigned int size, bool get_value)
1016 {
1017         Elf_Sym *sym;
1018         Elf_Shdr *sechdrs;
1019         struct purgatory_info *pi = &image->purgatory_info;
1020         char *sym_buf;
1021
1022         sym = kexec_purgatory_find_symbol(pi, name);
1023         if (!sym)
1024                 return -EINVAL;
1025
1026         if (sym->st_size != size) {
1027                 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1028                        name, (unsigned long)sym->st_size, size);
1029                 return -EINVAL;
1030         }
1031
1032         sechdrs = pi->sechdrs;
1033
1034         if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
1035                 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1036                        get_value ? "get" : "set");
1037                 return -EINVAL;
1038         }
1039
1040         sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
1041                                         sym->st_value;
1042
1043         if (get_value)
1044                 memcpy((void *)buf, sym_buf, size);
1045         else
1046                 memcpy((void *)sym_buf, buf, size);
1047
1048         return 0;
1049 }