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 #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/mutex.h> 18 #include <linux/list.h> 19 #include <crypto/hash.h> 20 #include <crypto/sha.h> 21 #include <linux/syscalls.h> 22 #include <linux/vmalloc.h> 23 #include "kexec_internal.h" 24 25 /* 26 * Declare these symbols weak so that if architecture provides a purgatory, 27 * these will be overridden. 28 */ 29 char __weak kexec_purgatory[0]; 30 size_t __weak kexec_purgatory_size = 0; 31 32 static int kexec_calculate_store_digests(struct kimage *image); 33 34 static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len) 35 { 36 struct fd f = fdget(fd); 37 int ret; 38 struct kstat stat; 39 loff_t pos; 40 ssize_t bytes = 0; 41 42 if (!f.file) 43 return -EBADF; 44 45 ret = vfs_getattr(&f.file->f_path, &stat); 46 if (ret) 47 goto out; 48 49 if (stat.size > INT_MAX) { 50 ret = -EFBIG; 51 goto out; 52 } 53 54 /* Don't hand 0 to vmalloc, it whines. */ 55 if (stat.size == 0) { 56 ret = -EINVAL; 57 goto out; 58 } 59 60 *buf = vmalloc(stat.size); 61 if (!*buf) { 62 ret = -ENOMEM; 63 goto out; 64 } 65 66 pos = 0; 67 while (pos < stat.size) { 68 bytes = kernel_read(f.file, pos, (char *)(*buf) + pos, 69 stat.size - pos); 70 if (bytes < 0) { 71 vfree(*buf); 72 ret = bytes; 73 goto out; 74 } 75 76 if (bytes == 0) 77 break; 78 pos += bytes; 79 } 80 81 if (pos != stat.size) { 82 ret = -EBADF; 83 vfree(*buf); 84 goto out; 85 } 86 87 *buf_len = pos; 88 out: 89 fdput(f); 90 return ret; 91 } 92 93 /* Architectures can provide this probe function */ 94 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf, 95 unsigned long buf_len) 96 { 97 return -ENOEXEC; 98 } 99 100 void * __weak arch_kexec_kernel_image_load(struct kimage *image) 101 { 102 return ERR_PTR(-ENOEXEC); 103 } 104 105 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image) 106 { 107 return -EINVAL; 108 } 109 110 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf, 111 unsigned long buf_len) 112 { 113 return -EKEYREJECTED; 114 } 115 116 /* Apply relocations of type RELA */ 117 int __weak 118 arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 119 unsigned int relsec) 120 { 121 pr_err("RELA relocation unsupported.\n"); 122 return -ENOEXEC; 123 } 124 125 /* Apply relocations of type REL */ 126 int __weak 127 arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 128 unsigned int relsec) 129 { 130 pr_err("REL relocation unsupported.\n"); 131 return -ENOEXEC; 132 } 133 134 /* 135 * Free up memory used by kernel, initrd, and command line. This is temporary 136 * memory allocation which is not needed any more after these buffers have 137 * been loaded into separate segments and have been copied elsewhere. 138 */ 139 void kimage_file_post_load_cleanup(struct kimage *image) 140 { 141 struct purgatory_info *pi = &image->purgatory_info; 142 143 vfree(image->kernel_buf); 144 image->kernel_buf = NULL; 145 146 vfree(image->initrd_buf); 147 image->initrd_buf = NULL; 148 149 kfree(image->cmdline_buf); 150 image->cmdline_buf = NULL; 151 152 vfree(pi->purgatory_buf); 153 pi->purgatory_buf = NULL; 154 155 vfree(pi->sechdrs); 156 pi->sechdrs = NULL; 157 158 /* See if architecture has anything to cleanup post load */ 159 arch_kimage_file_post_load_cleanup(image); 160 161 /* 162 * Above call should have called into bootloader to free up 163 * any data stored in kimage->image_loader_data. It should 164 * be ok now to free it up. 165 */ 166 kfree(image->image_loader_data); 167 image->image_loader_data = NULL; 168 } 169 170 /* 171 * In file mode list of segments is prepared by kernel. Copy relevant 172 * data from user space, do error checking, prepare segment list 173 */ 174 static int 175 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, 176 const char __user *cmdline_ptr, 177 unsigned long cmdline_len, unsigned flags) 178 { 179 int ret = 0; 180 void *ldata; 181 182 ret = copy_file_from_fd(kernel_fd, &image->kernel_buf, 183 &image->kernel_buf_len); 184 if (ret) 185 return ret; 186 187 /* Call arch image probe handlers */ 188 ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, 189 image->kernel_buf_len); 190 191 if (ret) 192 goto out; 193 194 #ifdef CONFIG_KEXEC_VERIFY_SIG 195 ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, 196 image->kernel_buf_len); 197 if (ret) { 198 pr_debug("kernel signature verification failed.\n"); 199 goto out; 200 } 201 pr_debug("kernel signature verification successful.\n"); 202 #endif 203 /* It is possible that there no initramfs is being loaded */ 204 if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { 205 ret = copy_file_from_fd(initrd_fd, &image->initrd_buf, 206 &image->initrd_buf_len); 207 if (ret) 208 goto out; 209 } 210 211 if (cmdline_len) { 212 image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL); 213 if (!image->cmdline_buf) { 214 ret = -ENOMEM; 215 goto out; 216 } 217 218 ret = copy_from_user(image->cmdline_buf, cmdline_ptr, 219 cmdline_len); 220 if (ret) { 221 ret = -EFAULT; 222 goto out; 223 } 224 225 image->cmdline_buf_len = cmdline_len; 226 227 /* command line should be a string with last byte null */ 228 if (image->cmdline_buf[cmdline_len - 1] != '\0') { 229 ret = -EINVAL; 230 goto out; 231 } 232 } 233 234 /* Call arch image load handlers */ 235 ldata = arch_kexec_kernel_image_load(image); 236 237 if (IS_ERR(ldata)) { 238 ret = PTR_ERR(ldata); 239 goto out; 240 } 241 242 image->image_loader_data = ldata; 243 out: 244 /* In case of error, free up all allocated memory in this function */ 245 if (ret) 246 kimage_file_post_load_cleanup(image); 247 return ret; 248 } 249 250 static int 251 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd, 252 int initrd_fd, const char __user *cmdline_ptr, 253 unsigned long cmdline_len, unsigned long flags) 254 { 255 int ret; 256 struct kimage *image; 257 bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH; 258 259 image = do_kimage_alloc_init(); 260 if (!image) 261 return -ENOMEM; 262 263 image->file_mode = 1; 264 265 if (kexec_on_panic) { 266 /* Enable special crash kernel control page alloc policy. */ 267 image->control_page = crashk_res.start; 268 image->type = KEXEC_TYPE_CRASH; 269 } 270 271 ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd, 272 cmdline_ptr, cmdline_len, flags); 273 if (ret) 274 goto out_free_image; 275 276 ret = sanity_check_segment_list(image); 277 if (ret) 278 goto out_free_post_load_bufs; 279 280 ret = -ENOMEM; 281 image->control_code_page = kimage_alloc_control_pages(image, 282 get_order(KEXEC_CONTROL_PAGE_SIZE)); 283 if (!image->control_code_page) { 284 pr_err("Could not allocate control_code_buffer\n"); 285 goto out_free_post_load_bufs; 286 } 287 288 if (!kexec_on_panic) { 289 image->swap_page = kimage_alloc_control_pages(image, 0); 290 if (!image->swap_page) { 291 pr_err("Could not allocate swap buffer\n"); 292 goto out_free_control_pages; 293 } 294 } 295 296 *rimage = image; 297 return 0; 298 out_free_control_pages: 299 kimage_free_page_list(&image->control_pages); 300 out_free_post_load_bufs: 301 kimage_file_post_load_cleanup(image); 302 out_free_image: 303 kfree(image); 304 return ret; 305 } 306 307 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, 308 unsigned long, cmdline_len, const char __user *, cmdline_ptr, 309 unsigned long, flags) 310 { 311 int ret = 0, i; 312 struct kimage **dest_image, *image; 313 314 /* We only trust the superuser with rebooting the system. */ 315 if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) 316 return -EPERM; 317 318 /* Make sure we have a legal set of flags */ 319 if (flags != (flags & KEXEC_FILE_FLAGS)) 320 return -EINVAL; 321 322 image = NULL; 323 324 if (!mutex_trylock(&kexec_mutex)) 325 return -EBUSY; 326 327 dest_image = &kexec_image; 328 if (flags & KEXEC_FILE_ON_CRASH) 329 dest_image = &kexec_crash_image; 330 331 if (flags & KEXEC_FILE_UNLOAD) 332 goto exchange; 333 334 /* 335 * In case of crash, new kernel gets loaded in reserved region. It is 336 * same memory where old crash kernel might be loaded. Free any 337 * current crash dump kernel before we corrupt it. 338 */ 339 if (flags & KEXEC_FILE_ON_CRASH) 340 kimage_free(xchg(&kexec_crash_image, NULL)); 341 342 ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr, 343 cmdline_len, flags); 344 if (ret) 345 goto out; 346 347 ret = machine_kexec_prepare(image); 348 if (ret) 349 goto out; 350 351 ret = kexec_calculate_store_digests(image); 352 if (ret) 353 goto out; 354 355 for (i = 0; i < image->nr_segments; i++) { 356 struct kexec_segment *ksegment; 357 358 ksegment = &image->segment[i]; 359 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n", 360 i, ksegment->buf, ksegment->bufsz, ksegment->mem, 361 ksegment->memsz); 362 363 ret = kimage_load_segment(image, &image->segment[i]); 364 if (ret) 365 goto out; 366 } 367 368 kimage_terminate(image); 369 370 /* 371 * Free up any temporary buffers allocated which are not needed 372 * after image has been loaded 373 */ 374 kimage_file_post_load_cleanup(image); 375 exchange: 376 image = xchg(dest_image, image); 377 out: 378 mutex_unlock(&kexec_mutex); 379 kimage_free(image); 380 return ret; 381 } 382 383 static int locate_mem_hole_top_down(unsigned long start, unsigned long end, 384 struct kexec_buf *kbuf) 385 { 386 struct kimage *image = kbuf->image; 387 unsigned long temp_start, temp_end; 388 389 temp_end = min(end, kbuf->buf_max); 390 temp_start = temp_end - kbuf->memsz; 391 392 do { 393 /* align down start */ 394 temp_start = temp_start & (~(kbuf->buf_align - 1)); 395 396 if (temp_start < start || temp_start < kbuf->buf_min) 397 return 0; 398 399 temp_end = temp_start + kbuf->memsz - 1; 400 401 /* 402 * Make sure this does not conflict with any of existing 403 * segments 404 */ 405 if (kimage_is_destination_range(image, temp_start, temp_end)) { 406 temp_start = temp_start - PAGE_SIZE; 407 continue; 408 } 409 410 /* We found a suitable memory range */ 411 break; 412 } while (1); 413 414 /* If we are here, we found a suitable memory range */ 415 kbuf->mem = temp_start; 416 417 /* Success, stop navigating through remaining System RAM ranges */ 418 return 1; 419 } 420 421 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, 422 struct kexec_buf *kbuf) 423 { 424 struct kimage *image = kbuf->image; 425 unsigned long temp_start, temp_end; 426 427 temp_start = max(start, kbuf->buf_min); 428 429 do { 430 temp_start = ALIGN(temp_start, kbuf->buf_align); 431 temp_end = temp_start + kbuf->memsz - 1; 432 433 if (temp_end > end || temp_end > kbuf->buf_max) 434 return 0; 435 /* 436 * Make sure this does not conflict with any of existing 437 * segments 438 */ 439 if (kimage_is_destination_range(image, temp_start, temp_end)) { 440 temp_start = temp_start + PAGE_SIZE; 441 continue; 442 } 443 444 /* We found a suitable memory range */ 445 break; 446 } while (1); 447 448 /* If we are here, we found a suitable memory range */ 449 kbuf->mem = temp_start; 450 451 /* Success, stop navigating through remaining System RAM ranges */ 452 return 1; 453 } 454 455 static int locate_mem_hole_callback(u64 start, u64 end, void *arg) 456 { 457 struct kexec_buf *kbuf = (struct kexec_buf *)arg; 458 unsigned long sz = end - start + 1; 459 460 /* Returning 0 will take to next memory range */ 461 if (sz < kbuf->memsz) 462 return 0; 463 464 if (end < kbuf->buf_min || start > kbuf->buf_max) 465 return 0; 466 467 /* 468 * Allocate memory top down with-in ram range. Otherwise bottom up 469 * allocation. 470 */ 471 if (kbuf->top_down) 472 return locate_mem_hole_top_down(start, end, kbuf); 473 return locate_mem_hole_bottom_up(start, end, kbuf); 474 } 475 476 /* 477 * Helper function for placing a buffer in a kexec segment. This assumes 478 * that kexec_mutex is held. 479 */ 480 int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz, 481 unsigned long memsz, unsigned long buf_align, 482 unsigned long buf_min, unsigned long buf_max, 483 bool top_down, unsigned long *load_addr) 484 { 485 486 struct kexec_segment *ksegment; 487 struct kexec_buf buf, *kbuf; 488 int ret; 489 490 /* Currently adding segment this way is allowed only in file mode */ 491 if (!image->file_mode) 492 return -EINVAL; 493 494 if (image->nr_segments >= KEXEC_SEGMENT_MAX) 495 return -EINVAL; 496 497 /* 498 * Make sure we are not trying to add buffer after allocating 499 * control pages. All segments need to be placed first before 500 * any control pages are allocated. As control page allocation 501 * logic goes through list of segments to make sure there are 502 * no destination overlaps. 503 */ 504 if (!list_empty(&image->control_pages)) { 505 WARN_ON(1); 506 return -EINVAL; 507 } 508 509 memset(&buf, 0, sizeof(struct kexec_buf)); 510 kbuf = &buf; 511 kbuf->image = image; 512 kbuf->buffer = buffer; 513 kbuf->bufsz = bufsz; 514 515 kbuf->memsz = ALIGN(memsz, PAGE_SIZE); 516 kbuf->buf_align = max(buf_align, PAGE_SIZE); 517 kbuf->buf_min = buf_min; 518 kbuf->buf_max = buf_max; 519 kbuf->top_down = top_down; 520 521 /* Walk the RAM ranges and allocate a suitable range for the buffer */ 522 if (image->type == KEXEC_TYPE_CRASH) 523 ret = walk_iomem_res("Crash kernel", 524 IORESOURCE_MEM | IORESOURCE_BUSY, 525 crashk_res.start, crashk_res.end, kbuf, 526 locate_mem_hole_callback); 527 else 528 ret = walk_system_ram_res(0, -1, kbuf, 529 locate_mem_hole_callback); 530 if (ret != 1) { 531 /* A suitable memory range could not be found for buffer */ 532 return -EADDRNOTAVAIL; 533 } 534 535 /* Found a suitable memory range */ 536 ksegment = &image->segment[image->nr_segments]; 537 ksegment->kbuf = kbuf->buffer; 538 ksegment->bufsz = kbuf->bufsz; 539 ksegment->mem = kbuf->mem; 540 ksegment->memsz = kbuf->memsz; 541 image->nr_segments++; 542 *load_addr = ksegment->mem; 543 return 0; 544 } 545 546 /* Calculate and store the digest of segments */ 547 static int kexec_calculate_store_digests(struct kimage *image) 548 { 549 struct crypto_shash *tfm; 550 struct shash_desc *desc; 551 int ret = 0, i, j, zero_buf_sz, sha_region_sz; 552 size_t desc_size, nullsz; 553 char *digest; 554 void *zero_buf; 555 struct kexec_sha_region *sha_regions; 556 struct purgatory_info *pi = &image->purgatory_info; 557 558 zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT); 559 zero_buf_sz = PAGE_SIZE; 560 561 tfm = crypto_alloc_shash("sha256", 0, 0); 562 if (IS_ERR(tfm)) { 563 ret = PTR_ERR(tfm); 564 goto out; 565 } 566 567 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); 568 desc = kzalloc(desc_size, GFP_KERNEL); 569 if (!desc) { 570 ret = -ENOMEM; 571 goto out_free_tfm; 572 } 573 574 sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region); 575 sha_regions = vzalloc(sha_region_sz); 576 if (!sha_regions) 577 goto out_free_desc; 578 579 desc->tfm = tfm; 580 desc->flags = 0; 581 582 ret = crypto_shash_init(desc); 583 if (ret < 0) 584 goto out_free_sha_regions; 585 586 digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL); 587 if (!digest) { 588 ret = -ENOMEM; 589 goto out_free_sha_regions; 590 } 591 592 for (j = i = 0; i < image->nr_segments; i++) { 593 struct kexec_segment *ksegment; 594 595 ksegment = &image->segment[i]; 596 /* 597 * Skip purgatory as it will be modified once we put digest 598 * info in purgatory. 599 */ 600 if (ksegment->kbuf == pi->purgatory_buf) 601 continue; 602 603 ret = crypto_shash_update(desc, ksegment->kbuf, 604 ksegment->bufsz); 605 if (ret) 606 break; 607 608 /* 609 * Assume rest of the buffer is filled with zero and 610 * update digest accordingly. 611 */ 612 nullsz = ksegment->memsz - ksegment->bufsz; 613 while (nullsz) { 614 unsigned long bytes = nullsz; 615 616 if (bytes > zero_buf_sz) 617 bytes = zero_buf_sz; 618 ret = crypto_shash_update(desc, zero_buf, bytes); 619 if (ret) 620 break; 621 nullsz -= bytes; 622 } 623 624 if (ret) 625 break; 626 627 sha_regions[j].start = ksegment->mem; 628 sha_regions[j].len = ksegment->memsz; 629 j++; 630 } 631 632 if (!ret) { 633 ret = crypto_shash_final(desc, digest); 634 if (ret) 635 goto out_free_digest; 636 ret = kexec_purgatory_get_set_symbol(image, "sha_regions", 637 sha_regions, sha_region_sz, 0); 638 if (ret) 639 goto out_free_digest; 640 641 ret = kexec_purgatory_get_set_symbol(image, "sha256_digest", 642 digest, SHA256_DIGEST_SIZE, 0); 643 if (ret) 644 goto out_free_digest; 645 } 646 647 out_free_digest: 648 kfree(digest); 649 out_free_sha_regions: 650 vfree(sha_regions); 651 out_free_desc: 652 kfree(desc); 653 out_free_tfm: 654 kfree(tfm); 655 out: 656 return ret; 657 } 658 659 /* Actually load purgatory. Lot of code taken from kexec-tools */ 660 static int __kexec_load_purgatory(struct kimage *image, unsigned long min, 661 unsigned long max, int top_down) 662 { 663 struct purgatory_info *pi = &image->purgatory_info; 664 unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad; 665 unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset; 666 unsigned char *buf_addr, *src; 667 int i, ret = 0, entry_sidx = -1; 668 const Elf_Shdr *sechdrs_c; 669 Elf_Shdr *sechdrs = NULL; 670 void *purgatory_buf = NULL; 671 672 /* 673 * sechdrs_c points to section headers in purgatory and are read 674 * only. No modifications allowed. 675 */ 676 sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff; 677 678 /* 679 * We can not modify sechdrs_c[] and its fields. It is read only. 680 * Copy it over to a local copy where one can store some temporary 681 * data and free it at the end. We need to modify ->sh_addr and 682 * ->sh_offset fields to keep track of permanent and temporary 683 * locations of sections. 684 */ 685 sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 686 if (!sechdrs) 687 return -ENOMEM; 688 689 memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 690 691 /* 692 * We seem to have multiple copies of sections. First copy is which 693 * is embedded in kernel in read only section. Some of these sections 694 * will be copied to a temporary buffer and relocated. And these 695 * sections will finally be copied to their final destination at 696 * segment load time. 697 * 698 * Use ->sh_offset to reflect section address in memory. It will 699 * point to original read only copy if section is not allocatable. 700 * Otherwise it will point to temporary copy which will be relocated. 701 * 702 * Use ->sh_addr to contain final address of the section where it 703 * will go during execution time. 704 */ 705 for (i = 0; i < pi->ehdr->e_shnum; i++) { 706 if (sechdrs[i].sh_type == SHT_NOBITS) 707 continue; 708 709 sechdrs[i].sh_offset = (unsigned long)pi->ehdr + 710 sechdrs[i].sh_offset; 711 } 712 713 /* 714 * Identify entry point section and make entry relative to section 715 * start. 716 */ 717 entry = pi->ehdr->e_entry; 718 for (i = 0; i < pi->ehdr->e_shnum; i++) { 719 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 720 continue; 721 722 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR)) 723 continue; 724 725 /* Make entry section relative */ 726 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry && 727 ((sechdrs[i].sh_addr + sechdrs[i].sh_size) > 728 pi->ehdr->e_entry)) { 729 entry_sidx = i; 730 entry -= sechdrs[i].sh_addr; 731 break; 732 } 733 } 734 735 /* Determine how much memory is needed to load relocatable object. */ 736 buf_align = 1; 737 bss_align = 1; 738 buf_sz = 0; 739 bss_sz = 0; 740 741 for (i = 0; i < pi->ehdr->e_shnum; i++) { 742 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 743 continue; 744 745 align = sechdrs[i].sh_addralign; 746 if (sechdrs[i].sh_type != SHT_NOBITS) { 747 if (buf_align < align) 748 buf_align = align; 749 buf_sz = ALIGN(buf_sz, align); 750 buf_sz += sechdrs[i].sh_size; 751 } else { 752 /* bss section */ 753 if (bss_align < align) 754 bss_align = align; 755 bss_sz = ALIGN(bss_sz, align); 756 bss_sz += sechdrs[i].sh_size; 757 } 758 } 759 760 /* Determine the bss padding required to align bss properly */ 761 bss_pad = 0; 762 if (buf_sz & (bss_align - 1)) 763 bss_pad = bss_align - (buf_sz & (bss_align - 1)); 764 765 memsz = buf_sz + bss_pad + bss_sz; 766 767 /* Allocate buffer for purgatory */ 768 purgatory_buf = vzalloc(buf_sz); 769 if (!purgatory_buf) { 770 ret = -ENOMEM; 771 goto out; 772 } 773 774 if (buf_align < bss_align) 775 buf_align = bss_align; 776 777 /* Add buffer to segment list */ 778 ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz, 779 buf_align, min, max, top_down, 780 &pi->purgatory_load_addr); 781 if (ret) 782 goto out; 783 784 /* Load SHF_ALLOC sections */ 785 buf_addr = purgatory_buf; 786 load_addr = curr_load_addr = pi->purgatory_load_addr; 787 bss_addr = load_addr + buf_sz + bss_pad; 788 789 for (i = 0; i < pi->ehdr->e_shnum; i++) { 790 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 791 continue; 792 793 align = sechdrs[i].sh_addralign; 794 if (sechdrs[i].sh_type != SHT_NOBITS) { 795 curr_load_addr = ALIGN(curr_load_addr, align); 796 offset = curr_load_addr - load_addr; 797 /* We already modifed ->sh_offset to keep src addr */ 798 src = (char *) sechdrs[i].sh_offset; 799 memcpy(buf_addr + offset, src, sechdrs[i].sh_size); 800 801 /* Store load address and source address of section */ 802 sechdrs[i].sh_addr = curr_load_addr; 803 804 /* 805 * This section got copied to temporary buffer. Update 806 * ->sh_offset accordingly. 807 */ 808 sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset); 809 810 /* Advance to the next address */ 811 curr_load_addr += sechdrs[i].sh_size; 812 } else { 813 bss_addr = ALIGN(bss_addr, align); 814 sechdrs[i].sh_addr = bss_addr; 815 bss_addr += sechdrs[i].sh_size; 816 } 817 } 818 819 /* Update entry point based on load address of text section */ 820 if (entry_sidx >= 0) 821 entry += sechdrs[entry_sidx].sh_addr; 822 823 /* Make kernel jump to purgatory after shutdown */ 824 image->start = entry; 825 826 /* Used later to get/set symbol values */ 827 pi->sechdrs = sechdrs; 828 829 /* 830 * Used later to identify which section is purgatory and skip it 831 * from checksumming. 832 */ 833 pi->purgatory_buf = purgatory_buf; 834 return ret; 835 out: 836 vfree(sechdrs); 837 vfree(purgatory_buf); 838 return ret; 839 } 840 841 static int kexec_apply_relocations(struct kimage *image) 842 { 843 int i, ret; 844 struct purgatory_info *pi = &image->purgatory_info; 845 Elf_Shdr *sechdrs = pi->sechdrs; 846 847 /* Apply relocations */ 848 for (i = 0; i < pi->ehdr->e_shnum; i++) { 849 Elf_Shdr *section, *symtab; 850 851 if (sechdrs[i].sh_type != SHT_RELA && 852 sechdrs[i].sh_type != SHT_REL) 853 continue; 854 855 /* 856 * For section of type SHT_RELA/SHT_REL, 857 * ->sh_link contains section header index of associated 858 * symbol table. And ->sh_info contains section header 859 * index of section to which relocations apply. 860 */ 861 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum || 862 sechdrs[i].sh_link >= pi->ehdr->e_shnum) 863 return -ENOEXEC; 864 865 section = &sechdrs[sechdrs[i].sh_info]; 866 symtab = &sechdrs[sechdrs[i].sh_link]; 867 868 if (!(section->sh_flags & SHF_ALLOC)) 869 continue; 870 871 /* 872 * symtab->sh_link contain section header index of associated 873 * string table. 874 */ 875 if (symtab->sh_link >= pi->ehdr->e_shnum) 876 /* Invalid section number? */ 877 continue; 878 879 /* 880 * Respective architecture needs to provide support for applying 881 * relocations of type SHT_RELA/SHT_REL. 882 */ 883 if (sechdrs[i].sh_type == SHT_RELA) 884 ret = arch_kexec_apply_relocations_add(pi->ehdr, 885 sechdrs, i); 886 else if (sechdrs[i].sh_type == SHT_REL) 887 ret = arch_kexec_apply_relocations(pi->ehdr, 888 sechdrs, i); 889 if (ret) 890 return ret; 891 } 892 893 return 0; 894 } 895 896 /* Load relocatable purgatory object and relocate it appropriately */ 897 int kexec_load_purgatory(struct kimage *image, unsigned long min, 898 unsigned long max, int top_down, 899 unsigned long *load_addr) 900 { 901 struct purgatory_info *pi = &image->purgatory_info; 902 int ret; 903 904 if (kexec_purgatory_size <= 0) 905 return -EINVAL; 906 907 if (kexec_purgatory_size < sizeof(Elf_Ehdr)) 908 return -ENOEXEC; 909 910 pi->ehdr = (Elf_Ehdr *)kexec_purgatory; 911 912 if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0 913 || pi->ehdr->e_type != ET_REL 914 || !elf_check_arch(pi->ehdr) 915 || pi->ehdr->e_shentsize != sizeof(Elf_Shdr)) 916 return -ENOEXEC; 917 918 if (pi->ehdr->e_shoff >= kexec_purgatory_size 919 || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) > 920 kexec_purgatory_size - pi->ehdr->e_shoff)) 921 return -ENOEXEC; 922 923 ret = __kexec_load_purgatory(image, min, max, top_down); 924 if (ret) 925 return ret; 926 927 ret = kexec_apply_relocations(image); 928 if (ret) 929 goto out; 930 931 *load_addr = pi->purgatory_load_addr; 932 return 0; 933 out: 934 vfree(pi->sechdrs); 935 vfree(pi->purgatory_buf); 936 return ret; 937 } 938 939 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, 940 const char *name) 941 { 942 Elf_Sym *syms; 943 Elf_Shdr *sechdrs; 944 Elf_Ehdr *ehdr; 945 int i, k; 946 const char *strtab; 947 948 if (!pi->sechdrs || !pi->ehdr) 949 return NULL; 950 951 sechdrs = pi->sechdrs; 952 ehdr = pi->ehdr; 953 954 for (i = 0; i < ehdr->e_shnum; i++) { 955 if (sechdrs[i].sh_type != SHT_SYMTAB) 956 continue; 957 958 if (sechdrs[i].sh_link >= ehdr->e_shnum) 959 /* Invalid strtab section number */ 960 continue; 961 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset; 962 syms = (Elf_Sym *)sechdrs[i].sh_offset; 963 964 /* Go through symbols for a match */ 965 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) { 966 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL) 967 continue; 968 969 if (strcmp(strtab + syms[k].st_name, name) != 0) 970 continue; 971 972 if (syms[k].st_shndx == SHN_UNDEF || 973 syms[k].st_shndx >= ehdr->e_shnum) { 974 pr_debug("Symbol: %s has bad section index %d.\n", 975 name, syms[k].st_shndx); 976 return NULL; 977 } 978 979 /* Found the symbol we are looking for */ 980 return &syms[k]; 981 } 982 } 983 984 return NULL; 985 } 986 987 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name) 988 { 989 struct purgatory_info *pi = &image->purgatory_info; 990 Elf_Sym *sym; 991 Elf_Shdr *sechdr; 992 993 sym = kexec_purgatory_find_symbol(pi, name); 994 if (!sym) 995 return ERR_PTR(-EINVAL); 996 997 sechdr = &pi->sechdrs[sym->st_shndx]; 998 999 /* 1000 * Returns the address where symbol will finally be loaded after 1001 * kexec_load_segment() 1002 */ 1003 return (void *)(sechdr->sh_addr + sym->st_value); 1004 } 1005 1006 /* 1007 * Get or set value of a symbol. If "get_value" is true, symbol value is 1008 * returned in buf otherwise symbol value is set based on value in buf. 1009 */ 1010 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, 1011 void *buf, unsigned int size, bool get_value) 1012 { 1013 Elf_Sym *sym; 1014 Elf_Shdr *sechdrs; 1015 struct purgatory_info *pi = &image->purgatory_info; 1016 char *sym_buf; 1017 1018 sym = kexec_purgatory_find_symbol(pi, name); 1019 if (!sym) 1020 return -EINVAL; 1021 1022 if (sym->st_size != size) { 1023 pr_err("symbol %s size mismatch: expected %lu actual %u\n", 1024 name, (unsigned long)sym->st_size, size); 1025 return -EINVAL; 1026 } 1027 1028 sechdrs = pi->sechdrs; 1029 1030 if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) { 1031 pr_err("symbol %s is in a bss section. Cannot %s\n", name, 1032 get_value ? "get" : "set"); 1033 return -EINVAL; 1034 } 1035 1036 sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset + 1037 sym->st_value; 1038 1039 if (get_value) 1040 memcpy((void *)buf, sym_buf, size); 1041 else 1042 memcpy((void *)sym_buf, buf, size); 1043 1044 return 0; 1045 } 1046