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