linux/kernel/kexec_file.c
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   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 */
  32char __weak kexec_purgatory[0];
  33size_t __weak kexec_purgatory_size = 0;
  34
  35static int kexec_calculate_store_digests(struct kimage *image);
  36
  37/* Architectures can provide this probe function */
  38int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
  39                                         unsigned long buf_len)
  40{
  41        return -ENOEXEC;
  42}
  43
  44void * __weak arch_kexec_kernel_image_load(struct kimage *image)
  45{
  46        return ERR_PTR(-ENOEXEC);
  47}
  48
  49int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
  50{
  51        return -EINVAL;
  52}
  53
  54#ifdef CONFIG_KEXEC_VERIFY_SIG
  55int __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 */
  63int __weak
  64arch_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 */
  72int __weak
  73arch_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 */
  85void 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 */
 120static int
 121kimage_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;
 192out:
 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
 199static int
 200kimage_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;
 247out_free_control_pages:
 248        kimage_free_page_list(&image->control_pages);
 249out_free_post_load_bufs:
 250        kimage_file_post_load_cleanup(image);
 251out_free_image:
 252        kfree(image);
 253        return ret;
 254}
 255
 256SYSCALL_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);
 327exchange:
 328        image = xchg(dest_image, image);
 329out:
 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
 338static 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
 376static 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
 410static 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 */
 435int 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 */
 502static 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
 602out_free_digest:
 603        kfree(digest);
 604out_free_sha_regions:
 605        vfree(sha_regions);
 606out_free_desc:
 607        kfree(desc);
 608out_free_tfm:
 609        kfree(tfm);
 610out:
 611        return ret;
 612}
 613
 614/* Actually load purgatory. Lot of code taken from kexec-tools */
 615static 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;
 790out:
 791        vfree(sechdrs);
 792        vfree(purgatory_buf);
 793        return ret;
 794}
 795
 796static 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 */
 852int 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;
 888out:
 889        vfree(pi->sechdrs);
 890        pi->sechdrs = NULL;
 891
 892        vfree(pi->purgatory_buf);
 893        pi->purgatory_buf = NULL;
 894        return ret;
 895}
 896
 897static 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
 945void *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 */
 968int 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}
1004