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                 if (kexec_crash_image)
 280                         arch_kexec_unprotect_crashkres();
 281         }
 282
 283         if (flags & KEXEC_FILE_UNLOAD)
 284                 goto exchange;
 285
 286         /*
 287          * In case of crash, new kernel gets loaded in reserved region. It is
 288          * same memory where old crash kernel might be loaded. Free any
 289          * current crash dump kernel before we corrupt it.
 290          */
 291         if (flags & KEXEC_FILE_ON_CRASH)
 292                 kimage_free(xchg(&kexec_crash_image, NULL));
 293
 294         ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
 295                                      cmdline_len, flags);
 296         if (ret)
 297                 goto out;
 298
 299         ret = machine_kexec_prepare(image);
 300         if (ret)
 301                 goto out;
 302
 303         ret = kexec_calculate_store_digests(image);
 304         if (ret)
 305                 goto out;
 306
 307         for (i = 0; i < image->nr_segments; i++) {
 308                 struct kexec_segment *ksegment;
 309
 310                 ksegment = &image->segment[i];
 311                 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
 312                          i, ksegment->buf, ksegment->bufsz, ksegment->mem,
 313                          ksegment->memsz);
 314
 315                 ret = kimage_load_segment(image, &image->segment[i]);
 316                 if (ret)
 317                         goto out;
 318         }
 319
 320         kimage_terminate(image);
 321
 322         /*
 323          * Free up any temporary buffers allocated which are not needed
 324          * after image has been loaded
 325          */
 326         kimage_file_post_load_cleanup(image);
 327 exchange:
 328         image = xchg(dest_image, image);
 329 out:
 330         if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
 331                 arch_kexec_protect_crashkres();
 332
 333         mutex_unlock(&kexec_mutex);
 334         kimage_free(image);
 335         return ret;
 336 }
 337
 338 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
 339                                     struct kexec_buf *kbuf)
 340 {
 341         struct kimage *image = kbuf->image;
 342         unsigned long temp_start, temp_end;
 343
 344         temp_end = min(end, kbuf->buf_max);
 345         temp_start = temp_end - kbuf->memsz;
 346
 347         do {
 348                 /* align down start */
 349                 temp_start = temp_start & (~(kbuf->buf_align - 1));
 350
 351                 if (temp_start < start || temp_start < kbuf->buf_min)
 352                         return 0;
 353
 354                 temp_end = temp_start + kbuf->memsz - 1;
 355
 356                 /*
 357                  * Make sure this does not conflict with any of existing
 358                  * segments
 359                  */
 360                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 361                         temp_start = temp_start - PAGE_SIZE;
 362                         continue;
 363                 }
 364
 365                 /* We found a suitable memory range */
 366                 break;
 367         } while (1);
 368
 369         /* If we are here, we found a suitable memory range */
 370         kbuf->mem = temp_start;
 371
 372         /* Success, stop navigating through remaining System RAM ranges */
 373         return 1;
 374 }
 375
 376 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
 377                                      struct kexec_buf *kbuf)
 378 {
 379         struct kimage *image = kbuf->image;
 380         unsigned long temp_start, temp_end;
 381
 382         temp_start = max(start, kbuf->buf_min);
 383
 384         do {
 385                 temp_start = ALIGN(temp_start, kbuf->buf_align);
 386                 temp_end = temp_start + kbuf->memsz - 1;
 387
 388                 if (temp_end > end || temp_end > kbuf->buf_max)
 389                         return 0;
 390                 /*
 391                  * Make sure this does not conflict with any of existing
 392                  * segments
 393                  */
 394                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 395                         temp_start = temp_start + PAGE_SIZE;
 396                         continue;
 397                 }
 398
 399                 /* We found a suitable memory range */
 400                 break;
 401         } while (1);
 402
 403         /* If we are here, we found a suitable memory range */
 404         kbuf->mem = temp_start;
 405
 406         /* Success, stop navigating through remaining System RAM ranges */
 407         return 1;
 408 }
 409
 410 static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
 411 {
 412         struct kexec_buf *kbuf = (struct kexec_buf *)arg;
 413         unsigned long sz = end - start + 1;
 414
 415         /* Returning 0 will take to next memory range */
 416         if (sz < kbuf->memsz)
 417                 return 0;
 418
 419         if (end < kbuf->buf_min || start > kbuf->buf_max)
 420                 return 0;
 421
 422         /*
 423          * Allocate memory top down with-in ram range. Otherwise bottom up
 424          * allocation.
 425          */
 426         if (kbuf->top_down)
 427                 return locate_mem_hole_top_down(start, end, kbuf);
 428         return locate_mem_hole_bottom_up(start, end, kbuf);
 429 }
 430
 431 /*
 432  * Helper function for placing a buffer in a kexec segment. This assumes
 433  * that kexec_mutex is held.
 434  */
 435 int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 436                      unsigned long memsz, unsigned long buf_align,
 437                      unsigned long buf_min, unsigned long buf_max,
 438                      bool top_down, unsigned long *load_addr)
 439 {
 440
 441         struct kexec_segment *ksegment;
 442         struct kexec_buf buf, *kbuf;
 443         int ret;
 444
 445         /* Currently adding segment this way is allowed only in file mode */
 446         if (!image->file_mode)
 447                 return -EINVAL;
 448
 449         if (image->nr_segments >= KEXEC_SEGMENT_MAX)
 450                 return -EINVAL;
 451
 452         /*
 453          * Make sure we are not trying to add buffer after allocating
 454          * control pages. All segments need to be placed first before
 455          * any control pages are allocated. As control page allocation
 456          * logic goes through list of segments to make sure there are
 457          * no destination overlaps.
 458          */
 459         if (!list_empty(&image->control_pages)) {
 460                 WARN_ON(1);
 461                 return -EINVAL;
 462         }
 463
 464         memset(&buf, 0, sizeof(struct kexec_buf));
 465         kbuf = &buf;
 466         kbuf->image = image;
 467         kbuf->buffer = buffer;
 468         kbuf->bufsz = bufsz;
 469
 470         kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
 471         kbuf->buf_align = max(buf_align, PAGE_SIZE);
 472         kbuf->buf_min = buf_min;
 473         kbuf->buf_max = buf_max;
 474         kbuf->top_down = top_down;
 475
 476         /* Walk the RAM ranges and allocate a suitable range for the buffer */
 477         if (image->type == KEXEC_TYPE_CRASH)
 478                 ret = walk_iomem_res_desc(crashk_res.desc,
 479                                 IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
 480                                 crashk_res.start, crashk_res.end, kbuf,
 481                                 locate_mem_hole_callback);
 482         else
 483                 ret = walk_system_ram_res(0, -1, kbuf,
 484                                           locate_mem_hole_callback);
 485         if (ret != 1) {
 486                 /* A suitable memory range could not be found for buffer */
 487                 return -EADDRNOTAVAIL;
 488         }
 489
 490         /* Found a suitable memory range */
 491         ksegment = &image->segment[image->nr_segments];
 492         ksegment->kbuf = kbuf->buffer;
 493         ksegment->bufsz = kbuf->bufsz;
 494         ksegment->mem = kbuf->mem;
 495         ksegment->memsz = kbuf->memsz;
 496         image->nr_segments++;
 497         *load_addr = ksegment->mem;
 498         return 0;
 499 }
 500
 501 /* Calculate and store the digest of segments */
 502 static int kexec_calculate_store_digests(struct kimage *image)
 503 {
 504         struct crypto_shash *tfm;
 505         struct shash_desc *desc;
 506         int ret = 0, i, j, zero_buf_sz, sha_region_sz;
 507         size_t desc_size, nullsz;
 508         char *digest;
 509         void *zero_buf;
 510         struct kexec_sha_region *sha_regions;
 511         struct purgatory_info *pi = &image->purgatory_info;
 512
 513         zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
 514         zero_buf_sz = PAGE_SIZE;
 515
 516         tfm = crypto_alloc_shash("sha256", 0, 0);
 517         if (IS_ERR(tfm)) {
 518                 ret = PTR_ERR(tfm);
 519                 goto out;
 520         }
 521
 522         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
 523         desc = kzalloc(desc_size, GFP_KERNEL);
 524         if (!desc) {
 525                 ret = -ENOMEM;
 526                 goto out_free_tfm;
 527         }
 528
 529         sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
 530         sha_regions = vzalloc(sha_region_sz);
 531         if (!sha_regions)
 532                 goto out_free_desc;
 533
 534         desc->tfm   = tfm;
 535         desc->flags = 0;
 536
 537         ret = crypto_shash_init(desc);
 538         if (ret < 0)
 539                 goto out_free_sha_regions;
 540
 541         digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
 542         if (!digest) {
 543                 ret = -ENOMEM;
 544                 goto out_free_sha_regions;
 545         }
 546
 547         for (j = i = 0; i < image->nr_segments; i++) {
 548                 struct kexec_segment *ksegment;
 549
 550                 ksegment = &image->segment[i];
 551                 /*
 552                  * Skip purgatory as it will be modified once we put digest
 553                  * info in purgatory.
 554                  */
 555                 if (ksegment->kbuf == pi->purgatory_buf)
 556                         continue;
 557
 558                 ret = crypto_shash_update(desc, ksegment->kbuf,
 559                                           ksegment->bufsz);
 560                 if (ret)
 561                         break;
 562
 563                 /*
 564                  * Assume rest of the buffer is filled with zero and
 565                  * update digest accordingly.
 566                  */
 567                 nullsz = ksegment->memsz - ksegment->bufsz;
 568                 while (nullsz) {
 569                         unsigned long bytes = nullsz;
 570
 571                         if (bytes > zero_buf_sz)
 572                                 bytes = zero_buf_sz;
 573                         ret = crypto_shash_update(desc, zero_buf, bytes);
 574                         if (ret)
 575                                 break;
 576                         nullsz -= bytes;
 577                 }
 578
 579                 if (ret)
 580                         break;
 581
 582                 sha_regions[j].start = ksegment->mem;
 583                 sha_regions[j].len = ksegment->memsz;
 584                 j++;
 585         }
 586
 587         if (!ret) {
 588                 ret = crypto_shash_final(desc, digest);
 589                 if (ret)
 590                         goto out_free_digest;
 591                 ret = kexec_purgatory_get_set_symbol(image, "sha_regions",
 592                                                 sha_regions, sha_region_sz, 0);
 593                 if (ret)
 594                         goto out_free_digest;
 595
 596                 ret = kexec_purgatory_get_set_symbol(image, "sha256_digest",
 597                                                 digest, SHA256_DIGEST_SIZE, 0);
 598                 if (ret)
 599                         goto out_free_digest;
 600         }
 601
 602 out_free_digest:
 603         kfree(digest);
 604 out_free_sha_regions:
 605         vfree(sha_regions);
 606 out_free_desc:
 607         kfree(desc);
 608 out_free_tfm:
 609         kfree(tfm);
 610 out:
 611         return ret;
 612 }
 613
 614 /* Actually load purgatory. Lot of code taken from kexec-tools */
 615 static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 616                                   unsigned long max, int top_down)
 617 {
 618         struct purgatory_info *pi = &image->purgatory_info;
 619         unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
 620         unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
 621         unsigned char *buf_addr, *src;
 622         int i, ret = 0, entry_sidx = -1;
 623         const Elf_Shdr *sechdrs_c;
 624         Elf_Shdr *sechdrs = NULL;
 625         void *purgatory_buf = NULL;
 626
 627         /*
 628          * sechdrs_c points to section headers in purgatory and are read
 629          * only. No modifications allowed.
 630          */
 631         sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
 632
 633         /*
 634          * We can not modify sechdrs_c[] and its fields. It is read only.
 635          * Copy it over to a local copy where one can store some temporary
 636          * data and free it at the end. We need to modify ->sh_addr and
 637          * ->sh_offset fields to keep track of permanent and temporary
 638          * locations of sections.
 639          */
 640         sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
 641         if (!sechdrs)
 642                 return -ENOMEM;
 643
 644         memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
 645
 646         /*
 647          * We seem to have multiple copies of sections. First copy is which
 648          * is embedded in kernel in read only section. Some of these sections
 649          * will be copied to a temporary buffer and relocated. And these
 650          * sections will finally be copied to their final destination at
 651          * segment load time.
 652          *
 653          * Use ->sh_offset to reflect section address in memory. It will
 654          * point to original read only copy if section is not allocatable.
 655          * Otherwise it will point to temporary copy which will be relocated.
 656          *
 657          * Use ->sh_addr to contain final address of the section where it
 658          * will go during execution time.
 659          */
 660         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 661                 if (sechdrs[i].sh_type == SHT_NOBITS)
 662                         continue;
 663
 664                 sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
 665                                                 sechdrs[i].sh_offset;
 666         }
 667
 668         /*
 669          * Identify entry point section and make entry relative to section
 670          * start.
 671          */
 672         entry = pi->ehdr->e_entry;
 673         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 674                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 675                         continue;
 676
 677                 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
 678                         continue;
 679
 680                 /* Make entry section relative */
 681                 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
 682                     ((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
 683                      pi->ehdr->e_entry)) {
 684                         entry_sidx = i;
 685                         entry -= sechdrs[i].sh_addr;
 686                         break;
 687                 }
 688         }
 689
 690         /* Determine how much memory is needed to load relocatable object. */
 691         buf_align = 1;
 692         bss_align = 1;
 693         buf_sz = 0;
 694         bss_sz = 0;
 695
 696         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 697                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 698                         continue;
 699
 700                 align = sechdrs[i].sh_addralign;
 701                 if (sechdrs[i].sh_type != SHT_NOBITS) {
 702                         if (buf_align < align)
 703                                 buf_align = align;
 704                         buf_sz = ALIGN(buf_sz, align);
 705                         buf_sz += sechdrs[i].sh_size;
 706                 } else {
 707                         /* bss section */
 708                         if (bss_align < align)
 709                                 bss_align = align;
 710                         bss_sz = ALIGN(bss_sz, align);
 711                         bss_sz += sechdrs[i].sh_size;
 712                 }
 713         }
 714
 715         /* Determine the bss padding required to align bss properly */
 716         bss_pad = 0;
 717         if (buf_sz & (bss_align - 1))
 718                 bss_pad = bss_align - (buf_sz & (bss_align - 1));
 719
 720         memsz = buf_sz + bss_pad + bss_sz;
 721
 722         /* Allocate buffer for purgatory */
 723         purgatory_buf = vzalloc(buf_sz);
 724         if (!purgatory_buf) {
 725                 ret = -ENOMEM;
 726                 goto out;
 727         }
 728
 729         if (buf_align < bss_align)
 730                 buf_align = bss_align;
 731
 732         /* Add buffer to segment list */
 733         ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
 734                                 buf_align, min, max, top_down,
 735                                 &pi->purgatory_load_addr);
 736         if (ret)
 737                 goto out;
 738
 739         /* Load SHF_ALLOC sections */
 740         buf_addr = purgatory_buf;
 741         load_addr = curr_load_addr = pi->purgatory_load_addr;
 742         bss_addr = load_addr + buf_sz + bss_pad;
 743
 744         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 745                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 746                         continue;
 747
 748                 align = sechdrs[i].sh_addralign;
 749                 if (sechdrs[i].sh_type != SHT_NOBITS) {
 750                         curr_load_addr = ALIGN(curr_load_addr, align);
 751                         offset = curr_load_addr - load_addr;
 752                         /* We already modifed ->sh_offset to keep src addr */
 753                         src = (char *) sechdrs[i].sh_offset;
 754                         memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
 755
 756                         /* Store load address and source address of section */
 757                         sechdrs[i].sh_addr = curr_load_addr;
 758
 759                         /*
 760                          * This section got copied to temporary buffer. Update
 761                          * ->sh_offset accordingly.
 762                          */
 763                         sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
 764
 765                         /* Advance to the next address */
 766                         curr_load_addr += sechdrs[i].sh_size;
 767                 } else {
 768                         bss_addr = ALIGN(bss_addr, align);
 769                         sechdrs[i].sh_addr = bss_addr;
 770                         bss_addr += sechdrs[i].sh_size;
 771                 }
 772         }
 773
 774         /* Update entry point based on load address of text section */
 775         if (entry_sidx >= 0)
 776                 entry += sechdrs[entry_sidx].sh_addr;
 777
 778         /* Make kernel jump to purgatory after shutdown */
 779         image->start = entry;
 780
 781         /* Used later to get/set symbol values */
 782         pi->sechdrs = sechdrs;
 783
 784         /*
 785          * Used later to identify which section is purgatory and skip it
 786          * from checksumming.
 787          */
 788         pi->purgatory_buf = purgatory_buf;
 789         return ret;
 790 out:
 791         vfree(sechdrs);
 792         vfree(purgatory_buf);
 793         return ret;
 794 }
 795
 796 static int kexec_apply_relocations(struct kimage *image)
 797 {
 798         int i, ret;
 799         struct purgatory_info *pi = &image->purgatory_info;
 800         Elf_Shdr *sechdrs = pi->sechdrs;
 801
 802         /* Apply relocations */
 803         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 804                 Elf_Shdr *section, *symtab;
 805
 806                 if (sechdrs[i].sh_type != SHT_RELA &&
 807                     sechdrs[i].sh_type != SHT_REL)
 808                         continue;
 809
 810                 /*
 811                  * For section of type SHT_RELA/SHT_REL,
 812                  * ->sh_link contains section header index of associated
 813                  * symbol table. And ->sh_info contains section header
 814                  * index of section to which relocations apply.
 815                  */
 816                 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
 817                     sechdrs[i].sh_link >= pi->ehdr->e_shnum)
 818                         return -ENOEXEC;
 819
 820                 section = &sechdrs[sechdrs[i].sh_info];
 821                 symtab = &sechdrs[sechdrs[i].sh_link];
 822
 823                 if (!(section->sh_flags & SHF_ALLOC))
 824                         continue;
 825
 826                 /*
 827                  * symtab->sh_link contain section header index of associated
 828                  * string table.
 829                  */
 830                 if (symtab->sh_link >= pi->ehdr->e_shnum)
 831                         /* Invalid section number? */
 832                         continue;
 833
 834                 /*
 835                  * Respective architecture needs to provide support for applying
 836                  * relocations of type SHT_RELA/SHT_REL.
 837                  */
 838                 if (sechdrs[i].sh_type == SHT_RELA)
 839                         ret = arch_kexec_apply_relocations_add(pi->ehdr,
 840                                                                sechdrs, i);
 841                 else if (sechdrs[i].sh_type == SHT_REL)
 842                         ret = arch_kexec_apply_relocations(pi->ehdr,
 843                                                            sechdrs, i);
 844                 if (ret)
 845                         return ret;
 846         }
 847
 848         return 0;
 849 }
 850
 851 /* Load relocatable purgatory object and relocate it appropriately */
 852 int kexec_load_purgatory(struct kimage *image, unsigned long min,
 853                          unsigned long max, int top_down,
 854                          unsigned long *load_addr)
 855 {
 856         struct purgatory_info *pi = &image->purgatory_info;
 857         int ret;
 858
 859         if (kexec_purgatory_size <= 0)
 860                 return -EINVAL;
 861
 862         if (kexec_purgatory_size < sizeof(Elf_Ehdr))
 863                 return -ENOEXEC;
 864
 865         pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
 866
 867         if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
 868             || pi->ehdr->e_type != ET_REL
 869             || !elf_check_arch(pi->ehdr)
 870             || pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
 871                 return -ENOEXEC;
 872
 873         if (pi->ehdr->e_shoff >= kexec_purgatory_size
 874             || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
 875             kexec_purgatory_size - pi->ehdr->e_shoff))
 876                 return -ENOEXEC;
 877
 878         ret = __kexec_load_purgatory(image, min, max, top_down);
 879         if (ret)
 880                 return ret;
 881
 882         ret = kexec_apply_relocations(image);
 883         if (ret)
 884                 goto out;
 885
 886         *load_addr = pi->purgatory_load_addr;
 887         return 0;
 888 out:
 889         vfree(pi->sechdrs);
 890         pi->sechdrs = NULL;
 891
 892         vfree(pi->purgatory_buf);
 893         pi->purgatory_buf = NULL;
 894         return ret;
 895 }
 896
 897 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
 898                                             const char *name)
 899 {
 900         Elf_Sym *syms;
 901         Elf_Shdr *sechdrs;
 902         Elf_Ehdr *ehdr;
 903         int i, k;
 904         const char *strtab;
 905
 906         if (!pi->sechdrs || !pi->ehdr)
 907                 return NULL;
 908
 909         sechdrs = pi->sechdrs;
 910         ehdr = pi->ehdr;
 911
 912         for (i = 0; i < ehdr->e_shnum; i++) {
 913                 if (sechdrs[i].sh_type != SHT_SYMTAB)
 914                         continue;
 915
 916                 if (sechdrs[i].sh_link >= ehdr->e_shnum)
 917                         /* Invalid strtab section number */
 918                         continue;
 919                 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
 920                 syms = (Elf_Sym *)sechdrs[i].sh_offset;
 921
 922                 /* Go through symbols for a match */
 923                 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
 924                         if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
 925                                 continue;
 926
 927                         if (strcmp(strtab + syms[k].st_name, name) != 0)
 928                                 continue;
 929
 930                         if (syms[k].st_shndx == SHN_UNDEF ||
 931                             syms[k].st_shndx >= ehdr->e_shnum) {
 932                                 pr_debug("Symbol: %s has bad section index %d.\n",
 933                                                 name, syms[k].st_shndx);
 934                                 return NULL;
 935                         }
 936
 937                         /* Found the symbol we are looking for */
 938                         return &syms[k];
 939                 }
 940         }
 941
 942         return NULL;
 943 }
 944
 945 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
 946 {
 947         struct purgatory_info *pi = &image->purgatory_info;
 948         Elf_Sym *sym;
 949         Elf_Shdr *sechdr;
 950
 951         sym = kexec_purgatory_find_symbol(pi, name);
 952         if (!sym)
 953                 return ERR_PTR(-EINVAL);
 954
 955         sechdr = &pi->sechdrs[sym->st_shndx];
 956
 957         /*
 958          * Returns the address where symbol will finally be loaded after
 959          * kexec_load_segment()
 960          */
 961         return (void *)(sechdr->sh_addr + sym->st_value);
 962 }
 963
 964 /*
 965  * Get or set value of a symbol. If "get_value" is true, symbol value is
 966  * returned in buf otherwise symbol value is set based on value in buf.
 967  */
 968 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
 969                                    void *buf, unsigned int size, bool get_value)
 970 {
 971         Elf_Sym *sym;
 972         Elf_Shdr *sechdrs;
 973         struct purgatory_info *pi = &image->purgatory_info;
 974         char *sym_buf;
 975
 976         sym = kexec_purgatory_find_symbol(pi, name);
 977         if (!sym)
 978                 return -EINVAL;
 979
 980         if (sym->st_size != size) {
 981                 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
 982                        name, (unsigned long)sym->st_size, size);
 983                 return -EINVAL;
 984         }
 985
 986         sechdrs = pi->sechdrs;
 987
 988         if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
 989                 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
 990                        get_value ? "get" : "set");
 991                 return -EINVAL;
 992         }
 993
 994         sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
 995                                         sym->st_value;
 996
 997         if (get_value)
 998                 memcpy((void *)buf, sym_buf, size);
 999         else
1000                 memcpy((void *)sym_buf, buf, size);
1001
1002         return 0;
1003 }