kernel/kexec_file.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * kexec: kexec_file_load system call
   4  *
   5  * Copyright (C) 2014 Red Hat Inc.
   6  * Authors:
   7  *      Vivek Goyal <vgoyal@redhat.com>
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/capability.h>
  13 #include <linux/mm.h>
  14 #include <linux/file.h>
  15 #include <linux/slab.h>
  16 #include <linux/kexec.h>
  17 #include <linux/memblock.h>
  18 #include <linux/mutex.h>
  19 #include <linux/list.h>
  20 #include <linux/fs.h>
  21 #include <linux/ima.h>
  22 #include <crypto/hash.h>
  23 #include <crypto/sha2.h>
  24 #include <linux/elf.h>
  25 #include <linux/elfcore.h>
  26 #include <linux/kernel.h>
  27 #include <linux/kernel_read_file.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/vmalloc.h>
  30 #include "kexec_internal.h"
  31
  32 #ifdef CONFIG_KEXEC_SIG
  33 static bool sig_enforce = IS_ENABLED(CONFIG_KEXEC_SIG_FORCE);
  34
  35 void set_kexec_sig_enforced(void)
  36 {
  37         sig_enforce = true;
  38 }
  39 #endif
  40
  41 static int kexec_calculate_store_digests(struct kimage *image);
  42
  43 /* Maximum size in bytes for kernel/initrd files. */
  44 #define KEXEC_FILE_SIZE_MAX     min_t(s64, 4LL << 30, SSIZE_MAX)
  45
  46 /*
  47  * Currently this is the only default function that is exported as some
  48  * architectures need it to do additional handlings.
  49  * In the future, other default functions may be exported too if required.
  50  */
  51 int kexec_image_probe_default(struct kimage *image, void *buf,
  52                               unsigned long buf_len)
  53 {
  54         const struct kexec_file_ops * const *fops;
  55         int ret = -ENOEXEC;
  56
  57         for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
  58                 ret = (*fops)->probe(buf, buf_len);
  59                 if (!ret) {
  60                         image->fops = *fops;
  61                         return ret;
  62                 }
  63         }
  64
  65         return ret;
  66 }
  67
  68 static void *kexec_image_load_default(struct kimage *image)
  69 {
  70         if (!image->fops || !image->fops->load)
  71                 return ERR_PTR(-ENOEXEC);
  72
  73         return image->fops->load(image, image->kernel_buf,
  74                                  image->kernel_buf_len, image->initrd_buf,
  75                                  image->initrd_buf_len, image->cmdline_buf,
  76                                  image->cmdline_buf_len);
  77 }
  78
  79 int kexec_image_post_load_cleanup_default(struct kimage *image)
  80 {
  81         if (!image->fops || !image->fops->cleanup)
  82                 return 0;
  83
  84         return image->fops->cleanup(image->image_loader_data);
  85 }
  86
  87 /*
  88  * Free up memory used by kernel, initrd, and command line. This is temporary
  89  * memory allocation which is not needed any more after these buffers have
  90  * been loaded into separate segments and have been copied elsewhere.
  91  */
  92 void kimage_file_post_load_cleanup(struct kimage *image)
  93 {
  94         struct purgatory_info *pi = &image->purgatory_info;
  95
  96         vfree(image->kernel_buf);
  97         image->kernel_buf = NULL;
  98
  99         vfree(image->initrd_buf);
 100         image->initrd_buf = NULL;
 101
 102         kfree(image->cmdline_buf);
 103         image->cmdline_buf = NULL;
 104
 105         vfree(pi->purgatory_buf);
 106         pi->purgatory_buf = NULL;
 107
 108         vfree(pi->sechdrs);
 109         pi->sechdrs = NULL;
 110
 111 #ifdef CONFIG_IMA_KEXEC
 112         vfree(image->ima_buffer);
 113         image->ima_buffer = NULL;
 114 #endif /* CONFIG_IMA_KEXEC */
 115
 116         /* See if architecture has anything to cleanup post load */
 117         arch_kimage_file_post_load_cleanup(image);
 118
 119         /*
 120          * Above call should have called into bootloader to free up
 121          * any data stored in kimage->image_loader_data. It should
 122          * be ok now to free it up.
 123          */
 124         kfree(image->image_loader_data);
 125         image->image_loader_data = NULL;
 126 }
 127
 128 #ifdef CONFIG_KEXEC_SIG
 129 #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
 130 int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
 131 {
 132         int ret;
 133
 134         ret = verify_pefile_signature(kernel, kernel_len,
 135                                       VERIFY_USE_SECONDARY_KEYRING,
 136                                       VERIFYING_KEXEC_PE_SIGNATURE);
 137         if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
 138                 ret = verify_pefile_signature(kernel, kernel_len,
 139                                               VERIFY_USE_PLATFORM_KEYRING,
 140                                               VERIFYING_KEXEC_PE_SIGNATURE);
 141         }
 142         return ret;
 143 }
 144 #endif
 145
 146 static int kexec_image_verify_sig(struct kimage *image, void *buf,
 147                                   unsigned long buf_len)
 148 {
 149         if (!image->fops || !image->fops->verify_sig) {
 150                 pr_debug("kernel loader does not support signature verification.\n");
 151                 return -EKEYREJECTED;
 152         }
 153
 154         return image->fops->verify_sig(buf, buf_len);
 155 }
 156
 157 static int
 158 kimage_validate_signature(struct kimage *image)
 159 {
 160         int ret;
 161
 162         ret = kexec_image_verify_sig(image, image->kernel_buf,
 163                                      image->kernel_buf_len);
 164         if (ret) {
 165
 166                 if (sig_enforce) {
 167                         pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
 168                         return ret;
 169                 }
 170
 171                 /*
 172                  * If IMA is guaranteed to appraise a signature on the kexec
 173                  * image, permit it even if the kernel is otherwise locked
 174                  * down.
 175                  */
 176                 if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
 177                     security_locked_down(LOCKDOWN_KEXEC))
 178                         return -EPERM;
 179
 180                 pr_debug("kernel signature verification failed (%d).\n", ret);
 181         }
 182
 183         return 0;
 184 }
 185 #endif
 186
 187 /*
 188  * In file mode list of segments is prepared by kernel. Copy relevant
 189  * data from user space, do error checking, prepare segment list
 190  */
 191 static int
 192 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 193                              const char __user *cmdline_ptr,
 194                              unsigned long cmdline_len, unsigned flags)
 195 {
 196         ssize_t ret;
 197         void *ldata;
 198
 199         ret = kernel_read_file_from_fd(kernel_fd, 0, &image->kernel_buf,
 200                                        KEXEC_FILE_SIZE_MAX, NULL,
 201                                        READING_KEXEC_IMAGE);
 202         if (ret < 0)
 203                 return ret;
 204         image->kernel_buf_len = ret;
 205
 206         /* Call arch image probe handlers */
 207         ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
 208                                             image->kernel_buf_len);
 209         if (ret)
 210                 goto out;
 211
 212 #ifdef CONFIG_KEXEC_SIG
 213         ret = kimage_validate_signature(image);
 214
 215         if (ret)
 216                 goto out;
 217 #endif
 218         /* It is possible that there no initramfs is being loaded */
 219         if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
 220                 ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf,
 221                                                KEXEC_FILE_SIZE_MAX, NULL,
 222                                                READING_KEXEC_INITRAMFS);
 223                 if (ret < 0)
 224                         goto out;
 225                 image->initrd_buf_len = ret;
 226                 ret = 0;
 227         }
 228
 229         if (cmdline_len) {
 230                 image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
 231                 if (IS_ERR(image->cmdline_buf)) {
 232                         ret = PTR_ERR(image->cmdline_buf);
 233                         image->cmdline_buf = NULL;
 234                         goto out;
 235                 }
 236
 237                 image->cmdline_buf_len = cmdline_len;
 238
 239                 /* command line should be a string with last byte null */
 240                 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
 241                         ret = -EINVAL;
 242                         goto out;
 243                 }
 244
 245                 ima_kexec_cmdline(kernel_fd, image->cmdline_buf,
 246                                   image->cmdline_buf_len - 1);
 247         }
 248
 249         /* IMA needs to pass the measurement list to the next kernel. */
 250         ima_add_kexec_buffer(image);
 251
 252         /* Call image load handler */
 253         ldata = kexec_image_load_default(image);
 254
 255         if (IS_ERR(ldata)) {
 256                 ret = PTR_ERR(ldata);
 257                 goto out;
 258         }
 259
 260         image->image_loader_data = ldata;
 261 out:
 262         /* In case of error, free up all allocated memory in this function */
 263         if (ret)
 264                 kimage_file_post_load_cleanup(image);
 265         return ret;
 266 }
 267
 268 static int
 269 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
 270                        int initrd_fd, const char __user *cmdline_ptr,
 271                        unsigned long cmdline_len, unsigned long flags)
 272 {
 273         int ret;
 274         struct kimage *image;
 275         bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
 276
 277         image = do_kimage_alloc_init();
 278         if (!image)
 279                 return -ENOMEM;
 280
 281         image->file_mode = 1;
 282
 283         if (kexec_on_panic) {
 284                 /* Enable special crash kernel control page alloc policy. */
 285                 image->control_page = crashk_res.start;
 286                 image->type = KEXEC_TYPE_CRASH;
 287         }
 288
 289         ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
 290                                            cmdline_ptr, cmdline_len, flags);
 291         if (ret)
 292                 goto out_free_image;
 293
 294         ret = sanity_check_segment_list(image);
 295         if (ret)
 296                 goto out_free_post_load_bufs;
 297
 298         ret = -ENOMEM;
 299         image->control_code_page = kimage_alloc_control_pages(image,
 300                                            get_order(KEXEC_CONTROL_PAGE_SIZE));
 301         if (!image->control_code_page) {
 302                 pr_err("Could not allocate control_code_buffer\n");
 303                 goto out_free_post_load_bufs;
 304         }
 305
 306         if (!kexec_on_panic) {
 307                 image->swap_page = kimage_alloc_control_pages(image, 0);
 308                 if (!image->swap_page) {
 309                         pr_err("Could not allocate swap buffer\n");
 310                         goto out_free_control_pages;
 311                 }
 312         }
 313
 314         *rimage = image;
 315         return 0;
 316 out_free_control_pages:
 317         kimage_free_page_list(&image->control_pages);
 318 out_free_post_load_bufs:
 319         kimage_file_post_load_cleanup(image);
 320 out_free_image:
 321         kfree(image);
 322         return ret;
 323 }
 324
 325 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 326                 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
 327                 unsigned long, flags)
 328 {
 329         int image_type = (flags & KEXEC_FILE_ON_CRASH) ?
 330                          KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
 331         struct kimage **dest_image, *image;
 332         int ret = 0, i;
 333
 334         /* We only trust the superuser with rebooting the system. */
 335         if (!kexec_load_permitted(image_type))
 336                 return -EPERM;
 337
 338         /* Make sure we have a legal set of flags */
 339         if (flags != (flags & KEXEC_FILE_FLAGS))
 340                 return -EINVAL;
 341
 342         image = NULL;
 343
 344         if (!kexec_trylock())
 345                 return -EBUSY;
 346
 347         if (image_type == KEXEC_TYPE_CRASH) {
 348                 dest_image = &kexec_crash_image;
 349                 if (kexec_crash_image)
 350                         arch_kexec_unprotect_crashkres();
 351         } else {
 352                 dest_image = &kexec_image;
 353         }
 354
 355         if (flags & KEXEC_FILE_UNLOAD)
 356                 goto exchange;
 357
 358         /*
 359          * In case of crash, new kernel gets loaded in reserved region. It is
 360          * same memory where old crash kernel might be loaded. Free any
 361          * current crash dump kernel before we corrupt it.
 362          */
 363         if (flags & KEXEC_FILE_ON_CRASH)
 364                 kimage_free(xchg(&kexec_crash_image, NULL));
 365
 366         ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
 367                                      cmdline_len, flags);
 368         if (ret)
 369                 goto out;
 370
 371         ret = machine_kexec_prepare(image);
 372         if (ret)
 373                 goto out;
 374
 375         /*
 376          * Some architecture(like S390) may touch the crash memory before
 377          * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
 378          */
 379         ret = kimage_crash_copy_vmcoreinfo(image);
 380         if (ret)
 381                 goto out;
 382
 383         ret = kexec_calculate_store_digests(image);
 384         if (ret)
 385                 goto out;
 386
 387         for (i = 0; i < image->nr_segments; i++) {
 388                 struct kexec_segment *ksegment;
 389
 390                 ksegment = &image->segment[i];
 391                 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
 392                          i, ksegment->buf, ksegment->bufsz, ksegment->mem,
 393                          ksegment->memsz);
 394
 395                 ret = kimage_load_segment(image, &image->segment[i]);
 396                 if (ret)
 397                         goto out;
 398         }
 399
 400         kimage_terminate(image);
 401
 402         ret = machine_kexec_post_load(image);
 403         if (ret)
 404                 goto out;
 405
 406         /*
 407          * Free up any temporary buffers allocated which are not needed
 408          * after image has been loaded
 409          */
 410         kimage_file_post_load_cleanup(image);
 411 exchange:
 412         image = xchg(dest_image, image);
 413 out:
 414         if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
 415                 arch_kexec_protect_crashkres();
 416
 417         kexec_unlock();
 418         kimage_free(image);
 419         return ret;
 420 }
 421
 422 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
 423                                     struct kexec_buf *kbuf)
 424 {
 425         struct kimage *image = kbuf->image;
 426         unsigned long temp_start, temp_end;
 427
 428         temp_end = min(end, kbuf->buf_max);
 429         temp_start = temp_end - kbuf->memsz;
 430
 431         do {
 432                 /* align down start */
 433                 temp_start = temp_start & (~(kbuf->buf_align - 1));
 434
 435                 if (temp_start < start || temp_start < kbuf->buf_min)
 436                         return 0;
 437
 438                 temp_end = temp_start + kbuf->memsz - 1;
 439
 440                 /*
 441                  * Make sure this does not conflict with any of existing
 442                  * segments
 443                  */
 444                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 445                         temp_start = temp_start - PAGE_SIZE;
 446                         continue;
 447                 }
 448
 449                 /* We found a suitable memory range */
 450                 break;
 451         } while (1);
 452
 453         /* If we are here, we found a suitable memory range */
 454         kbuf->mem = temp_start;
 455
 456         /* Success, stop navigating through remaining System RAM ranges */
 457         return 1;
 458 }
 459
 460 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
 461                                      struct kexec_buf *kbuf)
 462 {
 463         struct kimage *image = kbuf->image;
 464         unsigned long temp_start, temp_end;
 465
 466         temp_start = max(start, kbuf->buf_min);
 467
 468         do {
 469                 temp_start = ALIGN(temp_start, kbuf->buf_align);
 470                 temp_end = temp_start + kbuf->memsz - 1;
 471
 472                 if (temp_end > end || temp_end > kbuf->buf_max)
 473                         return 0;
 474                 /*
 475                  * Make sure this does not conflict with any of existing
 476                  * segments
 477                  */
 478                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 479                         temp_start = temp_start + PAGE_SIZE;
 480                         continue;
 481                 }
 482
 483                 /* We found a suitable memory range */
 484                 break;
 485         } while (1);
 486
 487         /* If we are here, we found a suitable memory range */
 488         kbuf->mem = temp_start;
 489
 490         /* Success, stop navigating through remaining System RAM ranges */
 491         return 1;
 492 }
 493
 494 static int locate_mem_hole_callback(struct resource *res, void *arg)
 495 {
 496         struct kexec_buf *kbuf = (struct kexec_buf *)arg;
 497         u64 start = res->start, end = res->end;
 498         unsigned long sz = end - start + 1;
 499
 500         /* Returning 0 will take to next memory range */
 501
 502         /* Don't use memory that will be detected and handled by a driver. */
 503         if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
 504                 return 0;
 505
 506         if (sz < kbuf->memsz)
 507                 return 0;
 508
 509         if (end < kbuf->buf_min || start > kbuf->buf_max)
 510                 return 0;
 511
 512         /*
 513          * Allocate memory top down with-in ram range. Otherwise bottom up
 514          * allocation.
 515          */
 516         if (kbuf->top_down)
 517                 return locate_mem_hole_top_down(start, end, kbuf);
 518         return locate_mem_hole_bottom_up(start, end, kbuf);
 519 }
 520
 521 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
 522 static int kexec_walk_memblock(struct kexec_buf *kbuf,
 523                                int (*func)(struct resource *, void *))
 524 {
 525         int ret = 0;
 526         u64 i;
 527         phys_addr_t mstart, mend;
 528         struct resource res = { };
 529
 530         if (kbuf->image->type == KEXEC_TYPE_CRASH)
 531                 return func(&crashk_res, kbuf);
 532
 533         /*
 534          * Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See
 535          * IORESOURCE_SYSRAM_DRIVER_MANAGED handling in
 536          * locate_mem_hole_callback().
 537          */
 538         if (kbuf->top_down) {
 539                 for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,
 540                                                 &mstart, &mend, NULL) {
 541                         /*
 542                          * In memblock, end points to the first byte after the
 543                          * range while in kexec, end points to the last byte
 544                          * in the range.
 545                          */
 546                         res.start = mstart;
 547                         res.end = mend - 1;
 548                         ret = func(&res, kbuf);
 549                         if (ret)
 550                                 break;
 551                 }
 552         } else {
 553                 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
 554                                         &mstart, &mend, NULL) {
 555                         /*
 556                          * In memblock, end points to the first byte after the
 557                          * range while in kexec, end points to the last byte
 558                          * in the range.
 559                          */
 560                         res.start = mstart;
 561                         res.end = mend - 1;
 562                         ret = func(&res, kbuf);
 563                         if (ret)
 564                                 break;
 565                 }
 566         }
 567
 568         return ret;
 569 }
 570 #else
 571 static int kexec_walk_memblock(struct kexec_buf *kbuf,
 572                                int (*func)(struct resource *, void *))
 573 {
 574         return 0;
 575 }
 576 #endif
 577
 578 /**
 579  * kexec_walk_resources - call func(data) on free memory regions
 580  * @kbuf:       Context info for the search. Also passed to @func.
 581  * @func:       Function to call for each memory region.
 582  *
 583  * Return: The memory walk will stop when func returns a non-zero value
 584  * and that value will be returned. If all free regions are visited without
 585  * func returning non-zero, then zero will be returned.
 586  */
 587 static int kexec_walk_resources(struct kexec_buf *kbuf,
 588                                 int (*func)(struct resource *, void *))
 589 {
 590         if (kbuf->image->type == KEXEC_TYPE_CRASH)
 591                 return walk_iomem_res_desc(crashk_res.desc,
 592                                            IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
 593                                            crashk_res.start, crashk_res.end,
 594                                            kbuf, func);
 595         else
 596                 return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 597 }
 598
 599 /**
 600  * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
 601  * @kbuf:       Parameters for the memory search.
 602  *
 603  * On success, kbuf->mem will have the start address of the memory region found.
 604  *
 605  * Return: 0 on success, negative errno on error.
 606  */
 607 int kexec_locate_mem_hole(struct kexec_buf *kbuf)
 608 {
 609         int ret;
 610
 611         /* Arch knows where to place */
 612         if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
 613                 return 0;
 614
 615         if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
 616                 ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
 617         else
 618                 ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);
 619
 620         return ret == 1 ? 0 : -EADDRNOTAVAIL;
 621 }
 622
 623 /**
 624  * kexec_add_buffer - place a buffer in a kexec segment
 625  * @kbuf:       Buffer contents and memory parameters.
 626  *
 627  * This function assumes that kexec_mutex is held.
 628  * On successful return, @kbuf->mem will have the physical address of
 629  * the buffer in memory.
 630  *
 631  * Return: 0 on success, negative errno on error.
 632  */
 633 int kexec_add_buffer(struct kexec_buf *kbuf)
 634 {
 635         struct kexec_segment *ksegment;
 636         int ret;
 637
 638         /* Currently adding segment this way is allowed only in file mode */
 639         if (!kbuf->image->file_mode)
 640                 return -EINVAL;
 641
 642         if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
 643                 return -EINVAL;
 644
 645         /*
 646          * Make sure we are not trying to add buffer after allocating
 647          * control pages. All segments need to be placed first before
 648          * any control pages are allocated. As control page allocation
 649          * logic goes through list of segments to make sure there are
 650          * no destination overlaps.
 651          */
 652         if (!list_empty(&kbuf->image->control_pages)) {
 653                 WARN_ON(1);
 654                 return -EINVAL;
 655         }
 656
 657         /* Ensure minimum alignment needed for segments. */
 658         kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
 659         kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
 660
 661         /* Walk the RAM ranges and allocate a suitable range for the buffer */
 662         ret = arch_kexec_locate_mem_hole(kbuf);
 663         if (ret)
 664                 return ret;
 665
 666         /* Found a suitable memory range */
 667         ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
 668         ksegment->kbuf = kbuf->buffer;
 669         ksegment->bufsz = kbuf->bufsz;
 670         ksegment->mem = kbuf->mem;
 671         ksegment->memsz = kbuf->memsz;
 672         kbuf->image->nr_segments++;
 673         return 0;
 674 }
 675
 676 /* Calculate and store the digest of segments */
 677 static int kexec_calculate_store_digests(struct kimage *image)
 678 {
 679         struct crypto_shash *tfm;
 680         struct shash_desc *desc;
 681         int ret = 0, i, j, zero_buf_sz, sha_region_sz;
 682         size_t desc_size, nullsz;
 683         char *digest;
 684         void *zero_buf;
 685         struct kexec_sha_region *sha_regions;
 686         struct purgatory_info *pi = &image->purgatory_info;
 687
 688         if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY))
 689                 return 0;
 690
 691         zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
 692         zero_buf_sz = PAGE_SIZE;
 693
 694         tfm = crypto_alloc_shash("sha256", 0, 0);
 695         if (IS_ERR(tfm)) {
 696                 ret = PTR_ERR(tfm);
 697                 goto out;
 698         }
 699
 700         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
 701         desc = kzalloc(desc_size, GFP_KERNEL);
 702         if (!desc) {
 703                 ret = -ENOMEM;
 704                 goto out_free_tfm;
 705         }
 706
 707         sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
 708         sha_regions = vzalloc(sha_region_sz);
 709         if (!sha_regions) {
 710                 ret = -ENOMEM;
 711                 goto out_free_desc;
 712         }
 713
 714         desc->tfm   = tfm;
 715
 716         ret = crypto_shash_init(desc);
 717         if (ret < 0)
 718                 goto out_free_sha_regions;
 719
 720         digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
 721         if (!digest) {
 722                 ret = -ENOMEM;
 723                 goto out_free_sha_regions;
 724         }
 725
 726         for (j = i = 0; i < image->nr_segments; i++) {
 727                 struct kexec_segment *ksegment;
 728
 729 #ifdef CONFIG_CRASH_HOTPLUG
 730                 /* Exclude elfcorehdr segment to allow future changes via hotplug */
 731                 if (j == image->elfcorehdr_index)
 732                         continue;
 733 #endif
 734
 735                 ksegment = &image->segment[i];
 736                 /*
 737                  * Skip purgatory as it will be modified once we put digest
 738                  * info in purgatory.
 739                  */
 740                 if (ksegment->kbuf == pi->purgatory_buf)
 741                         continue;
 742
 743                 ret = crypto_shash_update(desc, ksegment->kbuf,
 744                                           ksegment->bufsz);
 745                 if (ret)
 746                         break;
 747
 748                 /*
 749                  * Assume rest of the buffer is filled with zero and
 750                  * update digest accordingly.
 751                  */
 752                 nullsz = ksegment->memsz - ksegment->bufsz;
 753                 while (nullsz) {
 754                         unsigned long bytes = nullsz;
 755
 756                         if (bytes > zero_buf_sz)
 757                                 bytes = zero_buf_sz;
 758                         ret = crypto_shash_update(desc, zero_buf, bytes);
 759                         if (ret)
 760                                 break;
 761                         nullsz -= bytes;
 762                 }
 763
 764                 if (ret)
 765                         break;
 766
 767                 sha_regions[j].start = ksegment->mem;
 768                 sha_regions[j].len = ksegment->memsz;
 769                 j++;
 770         }
 771
 772         if (!ret) {
 773                 ret = crypto_shash_final(desc, digest);
 774                 if (ret)
 775                         goto out_free_digest;
 776                 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
 777                                                      sha_regions, sha_region_sz, 0);
 778                 if (ret)
 779                         goto out_free_digest;
 780
 781                 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
 782                                                      digest, SHA256_DIGEST_SIZE, 0);
 783                 if (ret)
 784                         goto out_free_digest;
 785         }
 786
 787 out_free_digest:
 788         kfree(digest);
 789 out_free_sha_regions:
 790         vfree(sha_regions);
 791 out_free_desc:
 792         kfree(desc);
 793 out_free_tfm:
 794         kfree(tfm);
 795 out:
 796         return ret;
 797 }
 798
 799 #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
 800 /*
 801  * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
 802  * @pi:         Purgatory to be loaded.
 803  * @kbuf:       Buffer to setup.
 804  *
 805  * Allocates the memory needed for the buffer. Caller is responsible to free
 806  * the memory after use.
 807  *
 808  * Return: 0 on success, negative errno on error.
 809  */
 810 static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
 811                                       struct kexec_buf *kbuf)
 812 {
 813         const Elf_Shdr *sechdrs;
 814         unsigned long bss_align;
 815         unsigned long bss_sz;
 816         unsigned long align;
 817         int i, ret;
 818
 819         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 820         kbuf->buf_align = bss_align = 1;
 821         kbuf->bufsz = bss_sz = 0;
 822
 823         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 824                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 825                         continue;
 826
 827                 align = sechdrs[i].sh_addralign;
 828                 if (sechdrs[i].sh_type != SHT_NOBITS) {
 829                         if (kbuf->buf_align < align)
 830                                 kbuf->buf_align = align;
 831                         kbuf->bufsz = ALIGN(kbuf->bufsz, align);
 832                         kbuf->bufsz += sechdrs[i].sh_size;
 833                 } else {
 834                         if (bss_align < align)
 835                                 bss_align = align;
 836                         bss_sz = ALIGN(bss_sz, align);
 837                         bss_sz += sechdrs[i].sh_size;
 838                 }
 839         }
 840         kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
 841         kbuf->memsz = kbuf->bufsz + bss_sz;
 842         if (kbuf->buf_align < bss_align)
 843                 kbuf->buf_align = bss_align;
 844
 845         kbuf->buffer = vzalloc(kbuf->bufsz);
 846         if (!kbuf->buffer)
 847                 return -ENOMEM;
 848         pi->purgatory_buf = kbuf->buffer;
 849
 850         ret = kexec_add_buffer(kbuf);
 851         if (ret)
 852                 goto out;
 853
 854         return 0;
 855 out:
 856         vfree(pi->purgatory_buf);
 857         pi->purgatory_buf = NULL;
 858         return ret;
 859 }
 860
 861 /*
 862  * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
 863  * @pi:         Purgatory to be loaded.
 864  * @kbuf:       Buffer prepared to store purgatory.
 865  *
 866  * Allocates the memory needed for the buffer. Caller is responsible to free
 867  * the memory after use.
 868  *
 869  * Return: 0 on success, negative errno on error.
 870  */
 871 static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
 872                                          struct kexec_buf *kbuf)
 873 {
 874         unsigned long bss_addr;
 875         unsigned long offset;
 876         size_t sechdrs_size;
 877         Elf_Shdr *sechdrs;
 878         int i;
 879
 880         /*
 881          * The section headers in kexec_purgatory are read-only. In order to
 882          * have them modifiable make a temporary copy.
 883          */
 884         sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
 885         sechdrs = vzalloc(sechdrs_size);
 886         if (!sechdrs)
 887                 return -ENOMEM;
 888         memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
 889         pi->sechdrs = sechdrs;
 890
 891         offset = 0;
 892         bss_addr = kbuf->mem + kbuf->bufsz;
 893         kbuf->image->start = pi->ehdr->e_entry;
 894
 895         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 896                 unsigned long align;
 897                 void *src, *dst;
 898
 899                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 900                         continue;
 901
 902                 align = sechdrs[i].sh_addralign;
 903                 if (sechdrs[i].sh_type == SHT_NOBITS) {
 904                         bss_addr = ALIGN(bss_addr, align);
 905                         sechdrs[i].sh_addr = bss_addr;
 906                         bss_addr += sechdrs[i].sh_size;
 907                         continue;
 908                 }
 909
 910                 offset = ALIGN(offset, align);
 911
 912                 /*
 913                  * Check if the segment contains the entry point, if so,
 914                  * calculate the value of image->start based on it.
 915                  * If the compiler has produced more than one .text section
 916                  * (Eg: .text.hot), they are generally after the main .text
 917                  * section, and they shall not be used to calculate
 918                  * image->start. So do not re-calculate image->start if it
 919                  * is not set to the initial value, and warn the user so they
 920                  * have a chance to fix their purgatory's linker script.
 921                  */
 922                 if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
 923                     pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
 924                     pi->ehdr->e_entry < (sechdrs[i].sh_addr
 925                                          + sechdrs[i].sh_size) &&
 926                     !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) {
 927                         kbuf->image->start -= sechdrs[i].sh_addr;
 928                         kbuf->image->start += kbuf->mem + offset;
 929                 }
 930
 931                 src = (void *)pi->ehdr + sechdrs[i].sh_offset;
 932                 dst = pi->purgatory_buf + offset;
 933                 memcpy(dst, src, sechdrs[i].sh_size);
 934
 935                 sechdrs[i].sh_addr = kbuf->mem + offset;
 936                 sechdrs[i].sh_offset = offset;
 937                 offset += sechdrs[i].sh_size;
 938         }
 939
 940         return 0;
 941 }
 942
 943 static int kexec_apply_relocations(struct kimage *image)
 944 {
 945         int i, ret;
 946         struct purgatory_info *pi = &image->purgatory_info;
 947         const Elf_Shdr *sechdrs;
 948
 949         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 950
 951         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 952                 const Elf_Shdr *relsec;
 953                 const Elf_Shdr *symtab;
 954                 Elf_Shdr *section;
 955
 956                 relsec = sechdrs + i;
 957
 958                 if (relsec->sh_type != SHT_RELA &&
 959                     relsec->sh_type != SHT_REL)
 960                         continue;
 961
 962                 /*
 963                  * For section of type SHT_RELA/SHT_REL,
 964                  * ->sh_link contains section header index of associated
 965                  * symbol table. And ->sh_info contains section header
 966                  * index of section to which relocations apply.
 967                  */
 968                 if (relsec->sh_info >= pi->ehdr->e_shnum ||
 969                     relsec->sh_link >= pi->ehdr->e_shnum)
 970                         return -ENOEXEC;
 971
 972                 section = pi->sechdrs + relsec->sh_info;
 973                 symtab = sechdrs + relsec->sh_link;
 974
 975                 if (!(section->sh_flags & SHF_ALLOC))
 976                         continue;
 977
 978                 /*
 979                  * symtab->sh_link contain section header index of associated
 980                  * string table.
 981                  */
 982                 if (symtab->sh_link >= pi->ehdr->e_shnum)
 983                         /* Invalid section number? */
 984                         continue;
 985
 986                 /*
 987                  * Respective architecture needs to provide support for applying
 988                  * relocations of type SHT_RELA/SHT_REL.
 989                  */
 990                 if (relsec->sh_type == SHT_RELA)
 991                         ret = arch_kexec_apply_relocations_add(pi, section,
 992                                                                relsec, symtab);
 993                 else if (relsec->sh_type == SHT_REL)
 994                         ret = arch_kexec_apply_relocations(pi, section,
 995                                                            relsec, symtab);
 996                 if (ret)
 997                         return ret;
 998         }
 999
1000         return 0;
1001 }
1002
1003 /*
1004  * kexec_load_purgatory - Load and relocate the purgatory object.
1005  * @image:      Image to add the purgatory to.
1006  * @kbuf:       Memory parameters to use.
1007  *
1008  * Allocates the memory needed for image->purgatory_info.sechdrs and
1009  * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
1010  * to free the memory after use.
1011  *
1012  * Return: 0 on success, negative errno on error.
1013  */
1014 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
1015 {
1016         struct purgatory_info *pi = &image->purgatory_info;
1017         int ret;
1018
1019         if (kexec_purgatory_size <= 0)
1020                 return -EINVAL;
1021
1022         pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
1023
1024         ret = kexec_purgatory_setup_kbuf(pi, kbuf);
1025         if (ret)
1026                 return ret;
1027
1028         ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
1029         if (ret)
1030                 goto out_free_kbuf;
1031
1032         ret = kexec_apply_relocations(image);
1033         if (ret)
1034                 goto out;
1035
1036         return 0;
1037 out:
1038         vfree(pi->sechdrs);
1039         pi->sechdrs = NULL;
1040 out_free_kbuf:
1041         vfree(pi->purgatory_buf);
1042         pi->purgatory_buf = NULL;
1043         return ret;
1044 }
1045
1046 /*
1047  * kexec_purgatory_find_symbol - find a symbol in the purgatory
1048  * @pi:         Purgatory to search in.
1049  * @name:       Name of the symbol.
1050  *
1051  * Return: pointer to symbol in read-only symtab on success, NULL on error.
1052  */
1053 static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
1054                                                   const char *name)
1055 {
1056         const Elf_Shdr *sechdrs;
1057         const Elf_Ehdr *ehdr;
1058         const Elf_Sym *syms;
1059         const char *strtab;
1060         int i, k;
1061
1062         if (!pi->ehdr)
1063                 return NULL;
1064
1065         ehdr = pi->ehdr;
1066         sechdrs = (void *)ehdr + ehdr->e_shoff;
1067
1068         for (i = 0; i < ehdr->e_shnum; i++) {
1069                 if (sechdrs[i].sh_type != SHT_SYMTAB)
1070                         continue;
1071
1072                 if (sechdrs[i].sh_link >= ehdr->e_shnum)
1073                         /* Invalid strtab section number */
1074                         continue;
1075                 strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
1076                 syms = (void *)ehdr + sechdrs[i].sh_offset;
1077
1078                 /* Go through symbols for a match */
1079                 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
1080                         if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
1081                                 continue;
1082
1083                         if (strcmp(strtab + syms[k].st_name, name) != 0)
1084                                 continue;
1085
1086                         if (syms[k].st_shndx == SHN_UNDEF ||
1087                             syms[k].st_shndx >= ehdr->e_shnum) {
1088                                 pr_debug("Symbol: %s has bad section index %d.\n",
1089                                                 name, syms[k].st_shndx);
1090                                 return NULL;
1091                         }
1092
1093                         /* Found the symbol we are looking for */
1094                         return &syms[k];
1095                 }
1096         }
1097
1098         return NULL;
1099 }
1100
1101 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
1102 {
1103         struct purgatory_info *pi = &image->purgatory_info;
1104         const Elf_Sym *sym;
1105         Elf_Shdr *sechdr;
1106
1107         sym = kexec_purgatory_find_symbol(pi, name);
1108         if (!sym)
1109                 return ERR_PTR(-EINVAL);
1110
1111         sechdr = &pi->sechdrs[sym->st_shndx];
1112
1113         /*
1114          * Returns the address where symbol will finally be loaded after
1115          * kexec_load_segment()
1116          */
1117         return (void *)(sechdr->sh_addr + sym->st_value);
1118 }
1119
1120 /*
1121  * Get or set value of a symbol. If "get_value" is true, symbol value is
1122  * returned in buf otherwise symbol value is set based on value in buf.
1123  */
1124 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
1125                                    void *buf, unsigned int size, bool get_value)
1126 {
1127         struct purgatory_info *pi = &image->purgatory_info;
1128         const Elf_Sym *sym;
1129         Elf_Shdr *sec;
1130         char *sym_buf;
1131
1132         sym = kexec_purgatory_find_symbol(pi, name);
1133         if (!sym)
1134                 return -EINVAL;
1135
1136         if (sym->st_size != size) {
1137                 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1138                        name, (unsigned long)sym->st_size, size);
1139                 return -EINVAL;
1140         }
1141
1142         sec = pi->sechdrs + sym->st_shndx;
1143
1144         if (sec->sh_type == SHT_NOBITS) {
1145                 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1146                        get_value ? "get" : "set");
1147                 return -EINVAL;
1148         }
1149
1150         sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
1151
1152         if (get_value)
1153                 memcpy((void *)buf, sym_buf, size);
1154         else
1155                 memcpy((void *)sym_buf, buf, size);
1156
1157         return 0;
1158 }
1159 #endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */