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         kexec_file_dbg_print = false;
 128 }
 129
 130 #ifdef CONFIG_KEXEC_SIG
 131 #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
 132 int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
 133 {
 134         int ret;
 135
 136         ret = verify_pefile_signature(kernel, kernel_len,
 137                                       VERIFY_USE_SECONDARY_KEYRING,
 138                                       VERIFYING_KEXEC_PE_SIGNATURE);
 139         if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
 140                 ret = verify_pefile_signature(kernel, kernel_len,
 141                                               VERIFY_USE_PLATFORM_KEYRING,
 142                                               VERIFYING_KEXEC_PE_SIGNATURE);
 143         }
 144         return ret;
 145 }
 146 #endif
 147
 148 static int kexec_image_verify_sig(struct kimage *image, void *buf,
 149                                   unsigned long buf_len)
 150 {
 151         if (!image->fops || !image->fops->verify_sig) {
 152                 pr_debug("kernel loader does not support signature verification.\n");
 153                 return -EKEYREJECTED;
 154         }
 155
 156         return image->fops->verify_sig(buf, buf_len);
 157 }
 158
 159 static int
 160 kimage_validate_signature(struct kimage *image)
 161 {
 162         int ret;
 163
 164         ret = kexec_image_verify_sig(image, image->kernel_buf,
 165                                      image->kernel_buf_len);
 166         if (ret) {
 167
 168                 if (sig_enforce) {
 169                         pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
 170                         return ret;
 171                 }
 172
 173                 /*
 174                  * If IMA is guaranteed to appraise a signature on the kexec
 175                  * image, permit it even if the kernel is otherwise locked
 176                  * down.
 177                  */
 178                 if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
 179                     security_locked_down(LOCKDOWN_KEXEC))
 180                         return -EPERM;
 181
 182                 pr_debug("kernel signature verification failed (%d).\n", ret);
 183         }
 184
 185         return 0;
 186 }
 187 #endif
 188
 189 /*
 190  * In file mode list of segments is prepared by kernel. Copy relevant
 191  * data from user space, do error checking, prepare segment list
 192  */
 193 static int
 194 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 195                              const char __user *cmdline_ptr,
 196                              unsigned long cmdline_len, unsigned flags)
 197 {
 198         ssize_t ret;
 199         void *ldata;
 200
 201         ret = kernel_read_file_from_fd(kernel_fd, 0, &image->kernel_buf,
 202                                        KEXEC_FILE_SIZE_MAX, NULL,
 203                                        READING_KEXEC_IMAGE);
 204         if (ret < 0)
 205                 return ret;
 206         image->kernel_buf_len = ret;
 207         kexec_dprintk("kernel: %p kernel_size: %#lx\n",
 208                       image->kernel_buf, image->kernel_buf_len);
 209
 210         /* Call arch image probe handlers */
 211         ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
 212                                             image->kernel_buf_len);
 213         if (ret)
 214                 goto out;
 215
 216 #ifdef CONFIG_KEXEC_SIG
 217         ret = kimage_validate_signature(image);
 218
 219         if (ret)
 220                 goto out;
 221 #endif
 222         /* It is possible that there no initramfs is being loaded */
 223         if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
 224                 ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf,
 225                                                KEXEC_FILE_SIZE_MAX, NULL,
 226                                                READING_KEXEC_INITRAMFS);
 227                 if (ret < 0)
 228                         goto out;
 229                 image->initrd_buf_len = ret;
 230                 ret = 0;
 231         }
 232
 233         if (cmdline_len) {
 234                 image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
 235                 if (IS_ERR(image->cmdline_buf)) {
 236                         ret = PTR_ERR(image->cmdline_buf);
 237                         image->cmdline_buf = NULL;
 238                         goto out;
 239                 }
 240
 241                 image->cmdline_buf_len = cmdline_len;
 242
 243                 /* command line should be a string with last byte null */
 244                 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
 245                         ret = -EINVAL;
 246                         goto out;
 247                 }
 248
 249                 ima_kexec_cmdline(kernel_fd, image->cmdline_buf,
 250                                   image->cmdline_buf_len - 1);
 251         }
 252
 253         /* IMA needs to pass the measurement list to the next kernel. */
 254         ima_add_kexec_buffer(image);
 255
 256         /* Call image load handler */
 257         ldata = kexec_image_load_default(image);
 258
 259         if (IS_ERR(ldata)) {
 260                 ret = PTR_ERR(ldata);
 261                 goto out;
 262         }
 263
 264         image->image_loader_data = ldata;
 265 out:
 266         /* In case of error, free up all allocated memory in this function */
 267         if (ret)
 268                 kimage_file_post_load_cleanup(image);
 269         return ret;
 270 }
 271
 272 static int
 273 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
 274                        int initrd_fd, const char __user *cmdline_ptr,
 275                        unsigned long cmdline_len, unsigned long flags)
 276 {
 277         int ret;
 278         struct kimage *image;
 279         bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
 280
 281         image = do_kimage_alloc_init();
 282         if (!image)
 283                 return -ENOMEM;
 284
 285         kexec_file_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
 286         image->file_mode = 1;
 287
 288 #ifdef CONFIG_CRASH_DUMP
 289         if (kexec_on_panic) {
 290                 /* Enable special crash kernel control page alloc policy. */
 291                 image->control_page = crashk_res.start;
 292                 image->type = KEXEC_TYPE_CRASH;
 293         }
 294 #endif
 295
 296         ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
 297                                            cmdline_ptr, cmdline_len, flags);
 298         if (ret)
 299                 goto out_free_image;
 300
 301         ret = sanity_check_segment_list(image);
 302         if (ret)
 303                 goto out_free_post_load_bufs;
 304
 305         ret = -ENOMEM;
 306         image->control_code_page = kimage_alloc_control_pages(image,
 307                                            get_order(KEXEC_CONTROL_PAGE_SIZE));
 308         if (!image->control_code_page) {
 309                 pr_err("Could not allocate control_code_buffer\n");
 310                 goto out_free_post_load_bufs;
 311         }
 312
 313         if (!kexec_on_panic) {
 314                 image->swap_page = kimage_alloc_control_pages(image, 0);
 315                 if (!image->swap_page) {
 316                         pr_err("Could not allocate swap buffer\n");
 317                         goto out_free_control_pages;
 318                 }
 319         }
 320
 321         *rimage = image;
 322         return 0;
 323 out_free_control_pages:
 324         kimage_free_page_list(&image->control_pages);
 325 out_free_post_load_bufs:
 326         kimage_file_post_load_cleanup(image);
 327 out_free_image:
 328         kfree(image);
 329         return ret;
 330 }
 331
 332 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 333                 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
 334                 unsigned long, flags)
 335 {
 336         int image_type = (flags & KEXEC_FILE_ON_CRASH) ?
 337                          KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
 338         struct kimage **dest_image, *image;
 339         int ret = 0, i;
 340
 341         /* We only trust the superuser with rebooting the system. */
 342         if (!kexec_load_permitted(image_type))
 343                 return -EPERM;
 344
 345         /* Make sure we have a legal set of flags */
 346         if (flags != (flags & KEXEC_FILE_FLAGS))
 347                 return -EINVAL;
 348
 349         image = NULL;
 350
 351         if (!kexec_trylock())
 352                 return -EBUSY;
 353
 354 #ifdef CONFIG_CRASH_DUMP
 355         if (image_type == KEXEC_TYPE_CRASH) {
 356                 dest_image = &kexec_crash_image;
 357                 if (kexec_crash_image)
 358                         arch_kexec_unprotect_crashkres();
 359         } else
 360 #endif
 361                 dest_image = &kexec_image;
 362
 363         if (flags & KEXEC_FILE_UNLOAD)
 364                 goto exchange;
 365
 366         /*
 367          * In case of crash, new kernel gets loaded in reserved region. It is
 368          * same memory where old crash kernel might be loaded. Free any
 369          * current crash dump kernel before we corrupt it.
 370          */
 371         if (flags & KEXEC_FILE_ON_CRASH)
 372                 kimage_free(xchg(&kexec_crash_image, NULL));
 373
 374         ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
 375                                      cmdline_len, flags);
 376         if (ret)
 377                 goto out;
 378
 379 #ifdef CONFIG_CRASH_HOTPLUG
 380         if ((flags & KEXEC_FILE_ON_CRASH) && arch_crash_hotplug_support(image, flags))
 381                 image->hotplug_support = 1;
 382 #endif
 383
 384         ret = machine_kexec_prepare(image);
 385         if (ret)
 386                 goto out;
 387
 388         /*
 389          * Some architecture(like S390) may touch the crash memory before
 390          * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
 391          */
 392         ret = kimage_crash_copy_vmcoreinfo(image);
 393         if (ret)
 394                 goto out;
 395
 396         ret = kexec_calculate_store_digests(image);
 397         if (ret)
 398                 goto out;
 399
 400         kexec_dprintk("nr_segments = %lu\n", image->nr_segments);
 401         for (i = 0; i < image->nr_segments; i++) {
 402                 struct kexec_segment *ksegment;
 403
 404                 ksegment = &image->segment[i];
 405                 kexec_dprintk("segment[%d]: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
 406                               i, ksegment->buf, ksegment->bufsz, ksegment->mem,
 407                               ksegment->memsz);
 408
 409                 ret = kimage_load_segment(image, &image->segment[i]);
 410                 if (ret)
 411                         goto out;
 412         }
 413
 414         kimage_terminate(image);
 415
 416         ret = machine_kexec_post_load(image);
 417         if (ret)
 418                 goto out;
 419
 420         kexec_dprintk("kexec_file_load: type:%u, start:0x%lx head:0x%lx flags:0x%lx\n",
 421                       image->type, image->start, image->head, flags);
 422         /*
 423          * Free up any temporary buffers allocated which are not needed
 424          * after image has been loaded
 425          */
 426         kimage_file_post_load_cleanup(image);
 427 exchange:
 428         image = xchg(dest_image, image);
 429 out:
 430 #ifdef CONFIG_CRASH_DUMP
 431         if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
 432                 arch_kexec_protect_crashkres();
 433 #endif
 434
 435         kexec_unlock();
 436         kimage_free(image);
 437         return ret;
 438 }
 439
 440 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
 441                                     struct kexec_buf *kbuf)
 442 {
 443         struct kimage *image = kbuf->image;
 444         unsigned long temp_start, temp_end;
 445
 446         temp_end = min(end, kbuf->buf_max);
 447         temp_start = temp_end - kbuf->memsz + 1;
 448
 449         do {
 450                 /* align down start */
 451                 temp_start = ALIGN_DOWN(temp_start, kbuf->buf_align);
 452
 453                 if (temp_start < start || temp_start < kbuf->buf_min)
 454                         return 0;
 455
 456                 temp_end = temp_start + kbuf->memsz - 1;
 457
 458                 /*
 459                  * Make sure this does not conflict with any of existing
 460                  * segments
 461                  */
 462                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 463                         temp_start = temp_start - PAGE_SIZE;
 464                         continue;
 465                 }
 466
 467                 /* We found a suitable memory range */
 468                 break;
 469         } while (1);
 470
 471         /* If we are here, we found a suitable memory range */
 472         kbuf->mem = temp_start;
 473
 474         /* Success, stop navigating through remaining System RAM ranges */
 475         return 1;
 476 }
 477
 478 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
 479                                      struct kexec_buf *kbuf)
 480 {
 481         struct kimage *image = kbuf->image;
 482         unsigned long temp_start, temp_end;
 483
 484         temp_start = max(start, kbuf->buf_min);
 485
 486         do {
 487                 temp_start = ALIGN(temp_start, kbuf->buf_align);
 488                 temp_end = temp_start + kbuf->memsz - 1;
 489
 490                 if (temp_end > end || temp_end > kbuf->buf_max)
 491                         return 0;
 492                 /*
 493                  * Make sure this does not conflict with any of existing
 494                  * segments
 495                  */
 496                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
 497                         temp_start = temp_start + PAGE_SIZE;
 498                         continue;
 499                 }
 500
 501                 /* We found a suitable memory range */
 502                 break;
 503         } while (1);
 504
 505         /* If we are here, we found a suitable memory range */
 506         kbuf->mem = temp_start;
 507
 508         /* Success, stop navigating through remaining System RAM ranges */
 509         return 1;
 510 }
 511
 512 static int locate_mem_hole_callback(struct resource *res, void *arg)
 513 {
 514         struct kexec_buf *kbuf = (struct kexec_buf *)arg;
 515         u64 start = res->start, end = res->end;
 516         unsigned long sz = end - start + 1;
 517
 518         /* Returning 0 will take to next memory range */
 519
 520         /* Don't use memory that will be detected and handled by a driver. */
 521         if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
 522                 return 0;
 523
 524         if (sz < kbuf->memsz)
 525                 return 0;
 526
 527         if (end < kbuf->buf_min || start > kbuf->buf_max)
 528                 return 0;
 529
 530         /*
 531          * Allocate memory top down with-in ram range. Otherwise bottom up
 532          * allocation.
 533          */
 534         if (kbuf->top_down)
 535                 return locate_mem_hole_top_down(start, end, kbuf);
 536         return locate_mem_hole_bottom_up(start, end, kbuf);
 537 }
 538
 539 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
 540 static int kexec_walk_memblock(struct kexec_buf *kbuf,
 541                                int (*func)(struct resource *, void *))
 542 {
 543         int ret = 0;
 544         u64 i;
 545         phys_addr_t mstart, mend;
 546         struct resource res = { };
 547
 548 #ifdef CONFIG_CRASH_DUMP
 549         if (kbuf->image->type == KEXEC_TYPE_CRASH)
 550                 return func(&crashk_res, kbuf);
 551 #endif
 552
 553         /*
 554          * Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See
 555          * IORESOURCE_SYSRAM_DRIVER_MANAGED handling in
 556          * locate_mem_hole_callback().
 557          */
 558         if (kbuf->top_down) {
 559                 for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,
 560                                                 &mstart, &mend, NULL) {
 561                         /*
 562                          * In memblock, end points to the first byte after the
 563                          * range while in kexec, end points to the last byte
 564                          * in the range.
 565                          */
 566                         res.start = mstart;
 567                         res.end = mend - 1;
 568                         ret = func(&res, kbuf);
 569                         if (ret)
 570                                 break;
 571                 }
 572         } else {
 573                 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
 574                                         &mstart, &mend, NULL) {
 575                         /*
 576                          * In memblock, end points to the first byte after the
 577                          * range while in kexec, end points to the last byte
 578                          * in the range.
 579                          */
 580                         res.start = mstart;
 581                         res.end = mend - 1;
 582                         ret = func(&res, kbuf);
 583                         if (ret)
 584                                 break;
 585                 }
 586         }
 587
 588         return ret;
 589 }
 590 #else
 591 static int kexec_walk_memblock(struct kexec_buf *kbuf,
 592                                int (*func)(struct resource *, void *))
 593 {
 594         return 0;
 595 }
 596 #endif
 597
 598 /**
 599  * kexec_walk_resources - call func(data) on free memory regions
 600  * @kbuf:       Context info for the search. Also passed to @func.
 601  * @func:       Function to call for each memory region.
 602  *
 603  * Return: The memory walk will stop when func returns a non-zero value
 604  * and that value will be returned. If all free regions are visited without
 605  * func returning non-zero, then zero will be returned.
 606  */
 607 static int kexec_walk_resources(struct kexec_buf *kbuf,
 608                                 int (*func)(struct resource *, void *))
 609 {
 610 #ifdef CONFIG_CRASH_DUMP
 611         if (kbuf->image->type == KEXEC_TYPE_CRASH)
 612                 return walk_iomem_res_desc(crashk_res.desc,
 613                                            IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
 614                                            crashk_res.start, crashk_res.end,
 615                                            kbuf, func);
 616 #endif
 617         if (kbuf->top_down)
 618                 return walk_system_ram_res_rev(0, ULONG_MAX, kbuf, func);
 619         else
 620                 return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 621 }
 622
 623 /**
 624  * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
 625  * @kbuf:       Parameters for the memory search.
 626  *
 627  * On success, kbuf->mem will have the start address of the memory region found.
 628  *
 629  * Return: 0 on success, negative errno on error.
 630  */
 631 int kexec_locate_mem_hole(struct kexec_buf *kbuf)
 632 {
 633         int ret;
 634
 635         /* Arch knows where to place */
 636         if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
 637                 return 0;
 638
 639         if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
 640                 ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
 641         else
 642                 ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);
 643
 644         return ret == 1 ? 0 : -EADDRNOTAVAIL;
 645 }
 646
 647 /**
 648  * kexec_add_buffer - place a buffer in a kexec segment
 649  * @kbuf:       Buffer contents and memory parameters.
 650  *
 651  * This function assumes that kexec_lock is held.
 652  * On successful return, @kbuf->mem will have the physical address of
 653  * the buffer in memory.
 654  *
 655  * Return: 0 on success, negative errno on error.
 656  */
 657 int kexec_add_buffer(struct kexec_buf *kbuf)
 658 {
 659         struct kexec_segment *ksegment;
 660         int ret;
 661
 662         /* Currently adding segment this way is allowed only in file mode */
 663         if (!kbuf->image->file_mode)
 664                 return -EINVAL;
 665
 666         if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
 667                 return -EINVAL;
 668
 669         /*
 670          * Make sure we are not trying to add buffer after allocating
 671          * control pages. All segments need to be placed first before
 672          * any control pages are allocated. As control page allocation
 673          * logic goes through list of segments to make sure there are
 674          * no destination overlaps.
 675          */
 676         if (!list_empty(&kbuf->image->control_pages)) {
 677                 WARN_ON(1);
 678                 return -EINVAL;
 679         }
 680
 681         /* Ensure minimum alignment needed for segments. */
 682         kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
 683         kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
 684
 685         /* Walk the RAM ranges and allocate a suitable range for the buffer */
 686         ret = arch_kexec_locate_mem_hole(kbuf);
 687         if (ret)
 688                 return ret;
 689
 690         /* Found a suitable memory range */
 691         ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
 692         ksegment->kbuf = kbuf->buffer;
 693         ksegment->bufsz = kbuf->bufsz;
 694         ksegment->mem = kbuf->mem;
 695         ksegment->memsz = kbuf->memsz;
 696         kbuf->image->nr_segments++;
 697         return 0;
 698 }
 699
 700 /* Calculate and store the digest of segments */
 701 static int kexec_calculate_store_digests(struct kimage *image)
 702 {
 703         struct crypto_shash *tfm;
 704         struct shash_desc *desc;
 705         int ret = 0, i, j, zero_buf_sz, sha_region_sz;
 706         size_t desc_size, nullsz;
 707         char *digest;
 708         void *zero_buf;
 709         struct kexec_sha_region *sha_regions;
 710         struct purgatory_info *pi = &image->purgatory_info;
 711
 712         if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY))
 713                 return 0;
 714
 715         zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
 716         zero_buf_sz = PAGE_SIZE;
 717
 718         tfm = crypto_alloc_shash("sha256", 0, 0);
 719         if (IS_ERR(tfm)) {
 720                 ret = PTR_ERR(tfm);
 721                 goto out;
 722         }
 723
 724         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
 725         desc = kzalloc(desc_size, GFP_KERNEL);
 726         if (!desc) {
 727                 ret = -ENOMEM;
 728                 goto out_free_tfm;
 729         }
 730
 731         sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
 732         sha_regions = vzalloc(sha_region_sz);
 733         if (!sha_regions) {
 734                 ret = -ENOMEM;
 735                 goto out_free_desc;
 736         }
 737
 738         desc->tfm   = tfm;
 739
 740         ret = crypto_shash_init(desc);
 741         if (ret < 0)
 742                 goto out_free_sha_regions;
 743
 744         digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
 745         if (!digest) {
 746                 ret = -ENOMEM;
 747                 goto out_free_sha_regions;
 748         }
 749
 750         for (j = i = 0; i < image->nr_segments; i++) {
 751                 struct kexec_segment *ksegment;
 752
 753 #ifdef CONFIG_CRASH_HOTPLUG
 754                 /* Exclude elfcorehdr segment to allow future changes via hotplug */
 755                 if (j == image->elfcorehdr_index)
 756                         continue;
 757 #endif
 758
 759                 ksegment = &image->segment[i];
 760                 /*
 761                  * Skip purgatory as it will be modified once we put digest
 762                  * info in purgatory.
 763                  */
 764                 if (ksegment->kbuf == pi->purgatory_buf)
 765                         continue;
 766
 767                 ret = crypto_shash_update(desc, ksegment->kbuf,
 768                                           ksegment->bufsz);
 769                 if (ret)
 770                         break;
 771
 772                 /*
 773                  * Assume rest of the buffer is filled with zero and
 774                  * update digest accordingly.
 775                  */
 776                 nullsz = ksegment->memsz - ksegment->bufsz;
 777                 while (nullsz) {
 778                         unsigned long bytes = nullsz;
 779
 780                         if (bytes > zero_buf_sz)
 781                                 bytes = zero_buf_sz;
 782                         ret = crypto_shash_update(desc, zero_buf, bytes);
 783                         if (ret)
 784                                 break;
 785                         nullsz -= bytes;
 786                 }
 787
 788                 if (ret)
 789                         break;
 790
 791                 sha_regions[j].start = ksegment->mem;
 792                 sha_regions[j].len = ksegment->memsz;
 793                 j++;
 794         }
 795
 796         if (!ret) {
 797                 ret = crypto_shash_final(desc, digest);
 798                 if (ret)
 799                         goto out_free_digest;
 800                 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
 801                                                      sha_regions, sha_region_sz, 0);
 802                 if (ret)
 803                         goto out_free_digest;
 804
 805                 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
 806                                                      digest, SHA256_DIGEST_SIZE, 0);
 807                 if (ret)
 808                         goto out_free_digest;
 809         }
 810
 811 out_free_digest:
 812         kfree(digest);
 813 out_free_sha_regions:
 814         vfree(sha_regions);
 815 out_free_desc:
 816         kfree(desc);
 817 out_free_tfm:
 818         kfree(tfm);
 819 out:
 820         return ret;
 821 }
 822
 823 #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
 824 /*
 825  * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
 826  * @pi:         Purgatory to be loaded.
 827  * @kbuf:       Buffer to setup.
 828  *
 829  * Allocates the memory needed for the buffer. Caller is responsible to free
 830  * the memory after use.
 831  *
 832  * Return: 0 on success, negative errno on error.
 833  */
 834 static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
 835                                       struct kexec_buf *kbuf)
 836 {
 837         const Elf_Shdr *sechdrs;
 838         unsigned long bss_align;
 839         unsigned long bss_sz;
 840         unsigned long align;
 841         int i, ret;
 842
 843         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 844         kbuf->buf_align = bss_align = 1;
 845         kbuf->bufsz = bss_sz = 0;
 846
 847         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 848                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 849                         continue;
 850
 851                 align = sechdrs[i].sh_addralign;
 852                 if (sechdrs[i].sh_type != SHT_NOBITS) {
 853                         if (kbuf->buf_align < align)
 854                                 kbuf->buf_align = align;
 855                         kbuf->bufsz = ALIGN(kbuf->bufsz, align);
 856                         kbuf->bufsz += sechdrs[i].sh_size;
 857                 } else {
 858                         if (bss_align < align)
 859                                 bss_align = align;
 860                         bss_sz = ALIGN(bss_sz, align);
 861                         bss_sz += sechdrs[i].sh_size;
 862                 }
 863         }
 864         kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
 865         kbuf->memsz = kbuf->bufsz + bss_sz;
 866         if (kbuf->buf_align < bss_align)
 867                 kbuf->buf_align = bss_align;
 868
 869         kbuf->buffer = vzalloc(kbuf->bufsz);
 870         if (!kbuf->buffer)
 871                 return -ENOMEM;
 872         pi->purgatory_buf = kbuf->buffer;
 873
 874         ret = kexec_add_buffer(kbuf);
 875         if (ret)
 876                 goto out;
 877
 878         return 0;
 879 out:
 880         vfree(pi->purgatory_buf);
 881         pi->purgatory_buf = NULL;
 882         return ret;
 883 }
 884
 885 /*
 886  * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
 887  * @pi:         Purgatory to be loaded.
 888  * @kbuf:       Buffer prepared to store purgatory.
 889  *
 890  * Allocates the memory needed for the buffer. Caller is responsible to free
 891  * the memory after use.
 892  *
 893  * Return: 0 on success, negative errno on error.
 894  */
 895 static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
 896                                          struct kexec_buf *kbuf)
 897 {
 898         unsigned long bss_addr;
 899         unsigned long offset;
 900         size_t sechdrs_size;
 901         Elf_Shdr *sechdrs;
 902         int i;
 903
 904         /*
 905          * The section headers in kexec_purgatory are read-only. In order to
 906          * have them modifiable make a temporary copy.
 907          */
 908         sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
 909         sechdrs = vzalloc(sechdrs_size);
 910         if (!sechdrs)
 911                 return -ENOMEM;
 912         memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
 913         pi->sechdrs = sechdrs;
 914
 915         offset = 0;
 916         bss_addr = kbuf->mem + kbuf->bufsz;
 917         kbuf->image->start = pi->ehdr->e_entry;
 918
 919         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 920                 unsigned long align;
 921                 void *src, *dst;
 922
 923                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 924                         continue;
 925
 926                 align = sechdrs[i].sh_addralign;
 927                 if (sechdrs[i].sh_type == SHT_NOBITS) {
 928                         bss_addr = ALIGN(bss_addr, align);
 929                         sechdrs[i].sh_addr = bss_addr;
 930                         bss_addr += sechdrs[i].sh_size;
 931                         continue;
 932                 }
 933
 934                 offset = ALIGN(offset, align);
 935
 936                 /*
 937                  * Check if the segment contains the entry point, if so,
 938                  * calculate the value of image->start based on it.
 939                  * If the compiler has produced more than one .text section
 940                  * (Eg: .text.hot), they are generally after the main .text
 941                  * section, and they shall not be used to calculate
 942                  * image->start. So do not re-calculate image->start if it
 943                  * is not set to the initial value, and warn the user so they
 944                  * have a chance to fix their purgatory's linker script.
 945                  */
 946                 if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
 947                     pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
 948                     pi->ehdr->e_entry < (sechdrs[i].sh_addr
 949                                          + sechdrs[i].sh_size) &&
 950                     !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) {
 951                         kbuf->image->start -= sechdrs[i].sh_addr;
 952                         kbuf->image->start += kbuf->mem + offset;
 953                 }
 954
 955                 src = (void *)pi->ehdr + sechdrs[i].sh_offset;
 956                 dst = pi->purgatory_buf + offset;
 957                 memcpy(dst, src, sechdrs[i].sh_size);
 958
 959                 sechdrs[i].sh_addr = kbuf->mem + offset;
 960                 sechdrs[i].sh_offset = offset;
 961                 offset += sechdrs[i].sh_size;
 962         }
 963
 964         return 0;
 965 }
 966
 967 static int kexec_apply_relocations(struct kimage *image)
 968 {
 969         int i, ret;
 970         struct purgatory_info *pi = &image->purgatory_info;
 971         const Elf_Shdr *sechdrs;
 972
 973         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 974
 975         for (i = 0; i < pi->ehdr->e_shnum; i++) {
 976                 const Elf_Shdr *relsec;
 977                 const Elf_Shdr *symtab;
 978                 Elf_Shdr *section;
 979
 980                 relsec = sechdrs + i;
 981
 982                 if (relsec->sh_type != SHT_RELA &&
 983                     relsec->sh_type != SHT_REL)
 984                         continue;
 985
 986                 /*
 987                  * For section of type SHT_RELA/SHT_REL,
 988                  * ->sh_link contains section header index of associated
 989                  * symbol table. And ->sh_info contains section header
 990                  * index of section to which relocations apply.
 991                  */
 992                 if (relsec->sh_info >= pi->ehdr->e_shnum ||
 993                     relsec->sh_link >= pi->ehdr->e_shnum)
 994                         return -ENOEXEC;
 995
 996                 section = pi->sechdrs + relsec->sh_info;
 997                 symtab = sechdrs + relsec->sh_link;
 998
 999                 if (!(section->sh_flags & SHF_ALLOC))
1000                         continue;
1001
1002                 /*
1003                  * symtab->sh_link contain section header index of associated
1004                  * string table.
1005                  */
1006                 if (symtab->sh_link >= pi->ehdr->e_shnum)
1007                         /* Invalid section number? */
1008                         continue;
1009
1010                 /*
1011                  * Respective architecture needs to provide support for applying
1012                  * relocations of type SHT_RELA/SHT_REL.
1013                  */
1014                 if (relsec->sh_type == SHT_RELA)
1015                         ret = arch_kexec_apply_relocations_add(pi, section,
1016                                                                relsec, symtab);
1017                 else if (relsec->sh_type == SHT_REL)
1018                         ret = arch_kexec_apply_relocations(pi, section,
1019                                                            relsec, symtab);
1020                 if (ret)
1021                         return ret;
1022         }
1023
1024         return 0;
1025 }
1026
1027 /*
1028  * kexec_load_purgatory - Load and relocate the purgatory object.
1029  * @image:      Image to add the purgatory to.
1030  * @kbuf:       Memory parameters to use.
1031  *
1032  * Allocates the memory needed for image->purgatory_info.sechdrs and
1033  * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
1034  * to free the memory after use.
1035  *
1036  * Return: 0 on success, negative errno on error.
1037  */
1038 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
1039 {
1040         struct purgatory_info *pi = &image->purgatory_info;
1041         int ret;
1042
1043         if (kexec_purgatory_size <= 0)
1044                 return -EINVAL;
1045
1046         pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
1047
1048         ret = kexec_purgatory_setup_kbuf(pi, kbuf);
1049         if (ret)
1050                 return ret;
1051
1052         ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
1053         if (ret)
1054                 goto out_free_kbuf;
1055
1056         ret = kexec_apply_relocations(image);
1057         if (ret)
1058                 goto out;
1059
1060         return 0;
1061 out:
1062         vfree(pi->sechdrs);
1063         pi->sechdrs = NULL;
1064 out_free_kbuf:
1065         vfree(pi->purgatory_buf);
1066         pi->purgatory_buf = NULL;
1067         return ret;
1068 }
1069
1070 /*
1071  * kexec_purgatory_find_symbol - find a symbol in the purgatory
1072  * @pi:         Purgatory to search in.
1073  * @name:       Name of the symbol.
1074  *
1075  * Return: pointer to symbol in read-only symtab on success, NULL on error.
1076  */
1077 static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
1078                                                   const char *name)
1079 {
1080         const Elf_Shdr *sechdrs;
1081         const Elf_Ehdr *ehdr;
1082         const Elf_Sym *syms;
1083         const char *strtab;
1084         int i, k;
1085
1086         if (!pi->ehdr)
1087                 return NULL;
1088
1089         ehdr = pi->ehdr;
1090         sechdrs = (void *)ehdr + ehdr->e_shoff;
1091
1092         for (i = 0; i < ehdr->e_shnum; i++) {
1093                 if (sechdrs[i].sh_type != SHT_SYMTAB)
1094                         continue;
1095
1096                 if (sechdrs[i].sh_link >= ehdr->e_shnum)
1097                         /* Invalid strtab section number */
1098                         continue;
1099                 strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
1100                 syms = (void *)ehdr + sechdrs[i].sh_offset;
1101
1102                 /* Go through symbols for a match */
1103                 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
1104                         if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
1105                                 continue;
1106
1107                         if (strcmp(strtab + syms[k].st_name, name) != 0)
1108                                 continue;
1109
1110                         if (syms[k].st_shndx == SHN_UNDEF ||
1111                             syms[k].st_shndx >= ehdr->e_shnum) {
1112                                 pr_debug("Symbol: %s has bad section index %d.\n",
1113                                                 name, syms[k].st_shndx);
1114                                 return NULL;
1115                         }
1116
1117                         /* Found the symbol we are looking for */
1118                         return &syms[k];
1119                 }
1120         }
1121
1122         return NULL;
1123 }
1124
1125 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
1126 {
1127         struct purgatory_info *pi = &image->purgatory_info;
1128         const Elf_Sym *sym;
1129         Elf_Shdr *sechdr;
1130
1131         sym = kexec_purgatory_find_symbol(pi, name);
1132         if (!sym)
1133                 return ERR_PTR(-EINVAL);
1134
1135         sechdr = &pi->sechdrs[sym->st_shndx];
1136
1137         /*
1138          * Returns the address where symbol will finally be loaded after
1139          * kexec_load_segment()
1140          */
1141         return (void *)(sechdr->sh_addr + sym->st_value);
1142 }
1143
1144 /*
1145  * Get or set value of a symbol. If "get_value" is true, symbol value is
1146  * returned in buf otherwise symbol value is set based on value in buf.
1147  */
1148 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
1149                                    void *buf, unsigned int size, bool get_value)
1150 {
1151         struct purgatory_info *pi = &image->purgatory_info;
1152         const Elf_Sym *sym;
1153         Elf_Shdr *sec;
1154         char *sym_buf;
1155
1156         sym = kexec_purgatory_find_symbol(pi, name);
1157         if (!sym)
1158                 return -EINVAL;
1159
1160         if (sym->st_size != size) {
1161                 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1162                        name, (unsigned long)sym->st_size, size);
1163                 return -EINVAL;
1164         }
1165
1166         sec = pi->sechdrs + sym->st_shndx;
1167
1168         if (sec->sh_type == SHT_NOBITS) {
1169                 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1170                        get_value ? "get" : "set");
1171                 return -EINVAL;
1172         }
1173
1174         sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
1175
1176         if (get_value)
1177                 memcpy((void *)buf, sym_buf, size);
1178         else
1179                 memcpy((void *)sym_buf, buf, size);
1180
1181         return 0;
1182 }
1183 #endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */