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 <crypto/hash.h> 22 #include <crypto/sha.h> 23 #include <linux/syscalls.h> 24 #include <linux/vmalloc.h> 25 #include "kexec_internal.h" 26 27 /* 28 * Declare these symbols weak so that if architecture provides a purgatory, 29 * these will be overridden. 30 */ 31 char __weak kexec_purgatory[0]; 32 size_t __weak kexec_purgatory_size = 0; 33 34 static int kexec_calculate_store_digests(struct kimage *image); 35 36 static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len) 37 { 38 struct fd f = fdget(fd); 39 int ret; 40 struct kstat stat; 41 loff_t pos; 42 ssize_t bytes = 0; 43 44 if (!f.file) 45 return -EBADF; 46 47 ret = vfs_getattr(&f.file->f_path, &stat); 48 if (ret) 49 goto out; 50 51 if (stat.size > INT_MAX) { 52 ret = -EFBIG; 53 goto out; 54 } 55 56 /* Don't hand 0 to vmalloc, it whines. */ 57 if (stat.size == 0) { 58 ret = -EINVAL; 59 goto out; 60 } 61 62 *buf = vmalloc(stat.size); 63 if (!*buf) { 64 ret = -ENOMEM; 65 goto out; 66 } 67 68 pos = 0; 69 while (pos < stat.size) { 70 bytes = kernel_read(f.file, pos, (char *)(*buf) + pos, 71 stat.size - pos); 72 if (bytes < 0) { 73 vfree(*buf); 74 ret = bytes; 75 goto out; 76 } 77 78 if (bytes == 0) 79 break; 80 pos += bytes; 81 } 82 83 if (pos != stat.size) { 84 ret = -EBADF; 85 vfree(*buf); 86 goto out; 87 } 88 89 *buf_len = pos; 90 out: 91 fdput(f); 92 return ret; 93 } 94 95 /* Architectures can provide this probe function */ 96 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf, 97 unsigned long buf_len) 98 { 99 return -ENOEXEC; 100 } 101 102 void * __weak arch_kexec_kernel_image_load(struct kimage *image) 103 { 104 return ERR_PTR(-ENOEXEC); 105 } 106 107 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image) 108 { 109 return -EINVAL; 110 } 111 112 #ifdef CONFIG_KEXEC_VERIFY_SIG 113 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf, 114 unsigned long buf_len) 115 { 116 return -EKEYREJECTED; 117 } 118 #endif 119 120 /* Apply relocations of type RELA */ 121 int __weak 122 arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 123 unsigned int relsec) 124 { 125 pr_err("RELA relocation unsupported.\n"); 126 return -ENOEXEC; 127 } 128 129 /* Apply relocations of type REL */ 130 int __weak 131 arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 132 unsigned int relsec) 133 { 134 pr_err("REL relocation unsupported.\n"); 135 return -ENOEXEC; 136 } 137 138 /* 139 * Free up memory used by kernel, initrd, and command line. This is temporary 140 * memory allocation which is not needed any more after these buffers have 141 * been loaded into separate segments and have been copied elsewhere. 142 */ 143 void kimage_file_post_load_cleanup(struct kimage *image) 144 { 145 struct purgatory_info *pi = &image->purgatory_info; 146 147 vfree(image->kernel_buf); 148 image->kernel_buf = NULL; 149 150 vfree(image->initrd_buf); 151 image->initrd_buf = NULL; 152 153 kfree(image->cmdline_buf); 154 image->cmdline_buf = NULL; 155 156 vfree(pi->purgatory_buf); 157 pi->purgatory_buf = NULL; 158 159 vfree(pi->sechdrs); 160 pi->sechdrs = NULL; 161 162 /* See if architecture has anything to cleanup post load */ 163 arch_kimage_file_post_load_cleanup(image); 164 165 /* 166 * Above call should have called into bootloader to free up 167 * any data stored in kimage->image_loader_data. It should 168 * be ok now to free it up. 169 */ 170 kfree(image->image_loader_data); 171 image->image_loader_data = NULL; 172 } 173 174 /* 175 * In file mode list of segments is prepared by kernel. Copy relevant 176 * data from user space, do error checking, prepare segment list 177 */ 178 static int 179 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, 180 const char __user *cmdline_ptr, 181 unsigned long cmdline_len, unsigned flags) 182 { 183 int ret = 0; 184 void *ldata; 185 186 ret = copy_file_from_fd(kernel_fd, &image->kernel_buf, 187 &image->kernel_buf_len); 188 if (ret) 189 return ret; 190 191 /* Call arch image probe handlers */ 192 ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, 193 image->kernel_buf_len); 194 195 if (ret) 196 goto out; 197 198 #ifdef CONFIG_KEXEC_VERIFY_SIG 199 ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, 200 image->kernel_buf_len); 201 if (ret) { 202 pr_debug("kernel signature verification failed.\n"); 203 goto out; 204 } 205 pr_debug("kernel signature verification successful.\n"); 206 #endif 207 /* It is possible that there no initramfs is being loaded */ 208 if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { 209 ret = copy_file_from_fd(initrd_fd, &image->initrd_buf, 210 &image->initrd_buf_len); 211 if (ret) 212 goto out; 213 } 214 215 if (cmdline_len) { 216 image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL); 217 if (!image->cmdline_buf) { 218 ret = -ENOMEM; 219 goto out; 220 } 221 222 ret = copy_from_user(image->cmdline_buf, cmdline_ptr, 223 cmdline_len); 224 if (ret) { 225 ret = -EFAULT; 226 goto out; 227 } 228 229 image->cmdline_buf_len = cmdline_len; 230 231 /* command line should be a string with last byte null */ 232 if (image->cmdline_buf[cmdline_len - 1] != '\0') { 233 ret = -EINVAL; 234 goto out; 235 } 236 } 237 238 /* Call arch image load handlers */ 239 ldata = arch_kexec_kernel_image_load(image); 240 241 if (IS_ERR(ldata)) { 242 ret = PTR_ERR(ldata); 243 goto out; 244 } 245 246 image->image_loader_data = ldata; 247 out: 248 /* In case of error, free up all allocated memory in this function */ 249 if (ret) 250 kimage_file_post_load_cleanup(image); 251 return ret; 252 } 253 254 static int 255 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd, 256 int initrd_fd, const char __user *cmdline_ptr, 257 unsigned long cmdline_len, unsigned long flags) 258 { 259 int ret; 260 struct kimage *image; 261 bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH; 262 263 image = do_kimage_alloc_init(); 264 if (!image) 265 return -ENOMEM; 266 267 image->file_mode = 1; 268 269 if (kexec_on_panic) { 270 /* Enable special crash kernel control page alloc policy. */ 271 image->control_page = crashk_res.start; 272 image->type = KEXEC_TYPE_CRASH; 273 } 274 275 ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd, 276 cmdline_ptr, cmdline_len, flags); 277 if (ret) 278 goto out_free_image; 279 280 ret = sanity_check_segment_list(image); 281 if (ret) 282 goto out_free_post_load_bufs; 283 284 ret = -ENOMEM; 285 image->control_code_page = kimage_alloc_control_pages(image, 286 get_order(KEXEC_CONTROL_PAGE_SIZE)); 287 if (!image->control_code_page) { 288 pr_err("Could not allocate control_code_buffer\n"); 289 goto out_free_post_load_bufs; 290 } 291 292 if (!kexec_on_panic) { 293 image->swap_page = kimage_alloc_control_pages(image, 0); 294 if (!image->swap_page) { 295 pr_err("Could not allocate swap buffer\n"); 296 goto out_free_control_pages; 297 } 298 } 299 300 *rimage = image; 301 return 0; 302 out_free_control_pages: 303 kimage_free_page_list(&image->control_pages); 304 out_free_post_load_bufs: 305 kimage_file_post_load_cleanup(image); 306 out_free_image: 307 kfree(image); 308 return ret; 309 } 310 311 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, 312 unsigned long, cmdline_len, const char __user *, cmdline_ptr, 313 unsigned long, flags) 314 { 315 int ret = 0, i; 316 struct kimage **dest_image, *image; 317 318 /* We only trust the superuser with rebooting the system. */ 319 if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) 320 return -EPERM; 321 322 /* Make sure we have a legal set of flags */ 323 if (flags != (flags & KEXEC_FILE_FLAGS)) 324 return -EINVAL; 325 326 image = NULL; 327 328 if (!mutex_trylock(&kexec_mutex)) 329 return -EBUSY; 330 331 dest_image = &kexec_image; 332 if (flags & KEXEC_FILE_ON_CRASH) 333 dest_image = &kexec_crash_image; 334 335 if (flags & KEXEC_FILE_UNLOAD) 336 goto exchange; 337 338 /* 339 * In case of crash, new kernel gets loaded in reserved region. It is 340 * same memory where old crash kernel might be loaded. Free any 341 * current crash dump kernel before we corrupt it. 342 */ 343 if (flags & KEXEC_FILE_ON_CRASH) 344 kimage_free(xchg(&kexec_crash_image, NULL)); 345 346 ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr, 347 cmdline_len, flags); 348 if (ret) 349 goto out; 350 351 ret = machine_kexec_prepare(image); 352 if (ret) 353 goto out; 354 355 ret = kexec_calculate_store_digests(image); 356 if (ret) 357 goto out; 358 359 for (i = 0; i < image->nr_segments; i++) { 360 struct kexec_segment *ksegment; 361 362 ksegment = &image->segment[i]; 363 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n", 364 i, ksegment->buf, ksegment->bufsz, ksegment->mem, 365 ksegment->memsz); 366 367 ret = kimage_load_segment(image, &image->segment[i]); 368 if (ret) 369 goto out; 370 } 371 372 kimage_terminate(image); 373 374 /* 375 * Free up any temporary buffers allocated which are not needed 376 * after image has been loaded 377 */ 378 kimage_file_post_load_cleanup(image); 379 exchange: 380 image = xchg(dest_image, image); 381 out: 382 mutex_unlock(&kexec_mutex); 383 kimage_free(image); 384 return ret; 385 } 386 387 static int locate_mem_hole_top_down(unsigned long start, unsigned long end, 388 struct kexec_buf *kbuf) 389 { 390 struct kimage *image = kbuf->image; 391 unsigned long temp_start, temp_end; 392 393 temp_end = min(end, kbuf->buf_max); 394 temp_start = temp_end - kbuf->memsz; 395 396 do { 397 /* align down start */ 398 temp_start = temp_start & (~(kbuf->buf_align - 1)); 399 400 if (temp_start < start || temp_start < kbuf->buf_min) 401 return 0; 402 403 temp_end = temp_start + kbuf->memsz - 1; 404 405 /* 406 * Make sure this does not conflict with any of existing 407 * segments 408 */ 409 if (kimage_is_destination_range(image, temp_start, temp_end)) { 410 temp_start = temp_start - PAGE_SIZE; 411 continue; 412 } 413 414 /* We found a suitable memory range */ 415 break; 416 } while (1); 417 418 /* If we are here, we found a suitable memory range */ 419 kbuf->mem = temp_start; 420 421 /* Success, stop navigating through remaining System RAM ranges */ 422 return 1; 423 } 424 425 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, 426 struct kexec_buf *kbuf) 427 { 428 struct kimage *image = kbuf->image; 429 unsigned long temp_start, temp_end; 430 431 temp_start = max(start, kbuf->buf_min); 432 433 do { 434 temp_start = ALIGN(temp_start, kbuf->buf_align); 435 temp_end = temp_start + kbuf->memsz - 1; 436 437 if (temp_end > end || temp_end > kbuf->buf_max) 438 return 0; 439 /* 440 * Make sure this does not conflict with any of existing 441 * segments 442 */ 443 if (kimage_is_destination_range(image, temp_start, temp_end)) { 444 temp_start = temp_start + PAGE_SIZE; 445 continue; 446 } 447 448 /* We found a suitable memory range */ 449 break; 450 } while (1); 451 452 /* If we are here, we found a suitable memory range */ 453 kbuf->mem = temp_start; 454 455 /* Success, stop navigating through remaining System RAM ranges */ 456 return 1; 457 } 458 459 static int locate_mem_hole_callback(u64 start, u64 end, void *arg) 460 { 461 struct kexec_buf *kbuf = (struct kexec_buf *)arg; 462 unsigned long sz = end - start + 1; 463 464 /* Returning 0 will take to next memory range */ 465 if (sz < kbuf->memsz) 466 return 0; 467 468 if (end < kbuf->buf_min || start > kbuf->buf_max) 469 return 0; 470 471 /* 472 * Allocate memory top down with-in ram range. Otherwise bottom up 473 * allocation. 474 */ 475 if (kbuf->top_down) 476 return locate_mem_hole_top_down(start, end, kbuf); 477 return locate_mem_hole_bottom_up(start, end, kbuf); 478 } 479 480 /* 481 * Helper function for placing a buffer in a kexec segment. This assumes 482 * that kexec_mutex is held. 483 */ 484 int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz, 485 unsigned long memsz, unsigned long buf_align, 486 unsigned long buf_min, unsigned long buf_max, 487 bool top_down, unsigned long *load_addr) 488 { 489 490 struct kexec_segment *ksegment; 491 struct kexec_buf buf, *kbuf; 492 int ret; 493 494 /* Currently adding segment this way is allowed only in file mode */ 495 if (!image->file_mode) 496 return -EINVAL; 497 498 if (image->nr_segments >= KEXEC_SEGMENT_MAX) 499 return -EINVAL; 500 501 /* 502 * Make sure we are not trying to add buffer after allocating 503 * control pages. All segments need to be placed first before 504 * any control pages are allocated. As control page allocation 505 * logic goes through list of segments to make sure there are 506 * no destination overlaps. 507 */ 508 if (!list_empty(&image->control_pages)) { 509 WARN_ON(1); 510 return -EINVAL; 511 } 512 513 memset(&buf, 0, sizeof(struct kexec_buf)); 514 kbuf = &buf; 515 kbuf->image = image; 516 kbuf->buffer = buffer; 517 kbuf->bufsz = bufsz; 518 519 kbuf->memsz = ALIGN(memsz, PAGE_SIZE); 520 kbuf->buf_align = max(buf_align, PAGE_SIZE); 521 kbuf->buf_min = buf_min; 522 kbuf->buf_max = buf_max; 523 kbuf->top_down = top_down; 524 525 /* Walk the RAM ranges and allocate a suitable range for the buffer */ 526 if (image->type == KEXEC_TYPE_CRASH) 527 ret = walk_iomem_res("Crash kernel", 528 IORESOURCE_MEM | IORESOURCE_BUSY, 529 crashk_res.start, crashk_res.end, kbuf, 530 locate_mem_hole_callback); 531 else 532 ret = walk_system_ram_res(0, -1, kbuf, 533 locate_mem_hole_callback); 534 if (ret != 1) { 535 /* A suitable memory range could not be found for buffer */ 536 return -EADDRNOTAVAIL; 537 } 538 539 /* Found a suitable memory range */ 540 ksegment = &image->segment[image->nr_segments]; 541 ksegment->kbuf = kbuf->buffer; 542 ksegment->bufsz = kbuf->bufsz; 543 ksegment->mem = kbuf->mem; 544 ksegment->memsz = kbuf->memsz; 545 image->nr_segments++; 546 *load_addr = ksegment->mem; 547 return 0; 548 } 549 550 /* Calculate and store the digest of segments */ 551 static int kexec_calculate_store_digests(struct kimage *image) 552 { 553 struct crypto_shash *tfm; 554 struct shash_desc *desc; 555 int ret = 0, i, j, zero_buf_sz, sha_region_sz; 556 size_t desc_size, nullsz; 557 char *digest; 558 void *zero_buf; 559 struct kexec_sha_region *sha_regions; 560 struct purgatory_info *pi = &image->purgatory_info; 561 562 zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT); 563 zero_buf_sz = PAGE_SIZE; 564 565 tfm = crypto_alloc_shash("sha256", 0, 0); 566 if (IS_ERR(tfm)) { 567 ret = PTR_ERR(tfm); 568 goto out; 569 } 570 571 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); 572 desc = kzalloc(desc_size, GFP_KERNEL); 573 if (!desc) { 574 ret = -ENOMEM; 575 goto out_free_tfm; 576 } 577 578 sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region); 579 sha_regions = vzalloc(sha_region_sz); 580 if (!sha_regions) 581 goto out_free_desc; 582 583 desc->tfm = tfm; 584 desc->flags = 0; 585 586 ret = crypto_shash_init(desc); 587 if (ret < 0) 588 goto out_free_sha_regions; 589 590 digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL); 591 if (!digest) { 592 ret = -ENOMEM; 593 goto out_free_sha_regions; 594 } 595 596 for (j = i = 0; i < image->nr_segments; i++) { 597 struct kexec_segment *ksegment; 598 599 ksegment = &image->segment[i]; 600 /* 601 * Skip purgatory as it will be modified once we put digest 602 * info in purgatory. 603 */ 604 if (ksegment->kbuf == pi->purgatory_buf) 605 continue; 606 607 ret = crypto_shash_update(desc, ksegment->kbuf, 608 ksegment->bufsz); 609 if (ret) 610 break; 611 612 /* 613 * Assume rest of the buffer is filled with zero and 614 * update digest accordingly. 615 */ 616 nullsz = ksegment->memsz - ksegment->bufsz; 617 while (nullsz) { 618 unsigned long bytes = nullsz; 619 620 if (bytes > zero_buf_sz) 621 bytes = zero_buf_sz; 622 ret = crypto_shash_update(desc, zero_buf, bytes); 623 if (ret) 624 break; 625 nullsz -= bytes; 626 } 627 628 if (ret) 629 break; 630 631 sha_regions[j].start = ksegment->mem; 632 sha_regions[j].len = ksegment->memsz; 633 j++; 634 } 635 636 if (!ret) { 637 ret = crypto_shash_final(desc, digest); 638 if (ret) 639 goto out_free_digest; 640 ret = kexec_purgatory_get_set_symbol(image, "sha_regions", 641 sha_regions, sha_region_sz, 0); 642 if (ret) 643 goto out_free_digest; 644 645 ret = kexec_purgatory_get_set_symbol(image, "sha256_digest", 646 digest, SHA256_DIGEST_SIZE, 0); 647 if (ret) 648 goto out_free_digest; 649 } 650 651 out_free_digest: 652 kfree(digest); 653 out_free_sha_regions: 654 vfree(sha_regions); 655 out_free_desc: 656 kfree(desc); 657 out_free_tfm: 658 kfree(tfm); 659 out: 660 return ret; 661 } 662 663 /* Actually load purgatory. Lot of code taken from kexec-tools */ 664 static int __kexec_load_purgatory(struct kimage *image, unsigned long min, 665 unsigned long max, int top_down) 666 { 667 struct purgatory_info *pi = &image->purgatory_info; 668 unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad; 669 unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset; 670 unsigned char *buf_addr, *src; 671 int i, ret = 0, entry_sidx = -1; 672 const Elf_Shdr *sechdrs_c; 673 Elf_Shdr *sechdrs = NULL; 674 void *purgatory_buf = NULL; 675 676 /* 677 * sechdrs_c points to section headers in purgatory and are read 678 * only. No modifications allowed. 679 */ 680 sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff; 681 682 /* 683 * We can not modify sechdrs_c[] and its fields. It is read only. 684 * Copy it over to a local copy where one can store some temporary 685 * data and free it at the end. We need to modify ->sh_addr and 686 * ->sh_offset fields to keep track of permanent and temporary 687 * locations of sections. 688 */ 689 sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 690 if (!sechdrs) 691 return -ENOMEM; 692 693 memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 694 695 /* 696 * We seem to have multiple copies of sections. First copy is which 697 * is embedded in kernel in read only section. Some of these sections 698 * will be copied to a temporary buffer and relocated. And these 699 * sections will finally be copied to their final destination at 700 * segment load time. 701 * 702 * Use ->sh_offset to reflect section address in memory. It will 703 * point to original read only copy if section is not allocatable. 704 * Otherwise it will point to temporary copy which will be relocated. 705 * 706 * Use ->sh_addr to contain final address of the section where it 707 * will go during execution time. 708 */ 709 for (i = 0; i < pi->ehdr->e_shnum; i++) { 710 if (sechdrs[i].sh_type == SHT_NOBITS) 711 continue; 712 713 sechdrs[i].sh_offset = (unsigned long)pi->ehdr + 714 sechdrs[i].sh_offset; 715 } 716 717 /* 718 * Identify entry point section and make entry relative to section 719 * start. 720 */ 721 entry = pi->ehdr->e_entry; 722 for (i = 0; i < pi->ehdr->e_shnum; i++) { 723 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 724 continue; 725 726 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR)) 727 continue; 728 729 /* Make entry section relative */ 730 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry && 731 ((sechdrs[i].sh_addr + sechdrs[i].sh_size) > 732 pi->ehdr->e_entry)) { 733 entry_sidx = i; 734 entry -= sechdrs[i].sh_addr; 735 break; 736 } 737 } 738 739 /* Determine how much memory is needed to load relocatable object. */ 740 buf_align = 1; 741 bss_align = 1; 742 buf_sz = 0; 743 bss_sz = 0; 744 745 for (i = 0; i < pi->ehdr->e_shnum; i++) { 746 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 747 continue; 748 749 align = sechdrs[i].sh_addralign; 750 if (sechdrs[i].sh_type != SHT_NOBITS) { 751 if (buf_align < align) 752 buf_align = align; 753 buf_sz = ALIGN(buf_sz, align); 754 buf_sz += sechdrs[i].sh_size; 755 } else { 756 /* bss section */ 757 if (bss_align < align) 758 bss_align = align; 759 bss_sz = ALIGN(bss_sz, align); 760 bss_sz += sechdrs[i].sh_size; 761 } 762 } 763 764 /* Determine the bss padding required to align bss properly */ 765 bss_pad = 0; 766 if (buf_sz & (bss_align - 1)) 767 bss_pad = bss_align - (buf_sz & (bss_align - 1)); 768 769 memsz = buf_sz + bss_pad + bss_sz; 770 771 /* Allocate buffer for purgatory */ 772 purgatory_buf = vzalloc(buf_sz); 773 if (!purgatory_buf) { 774 ret = -ENOMEM; 775 goto out; 776 } 777 778 if (buf_align < bss_align) 779 buf_align = bss_align; 780 781 /* Add buffer to segment list */ 782 ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz, 783 buf_align, min, max, top_down, 784 &pi->purgatory_load_addr); 785 if (ret) 786 goto out; 787 788 /* Load SHF_ALLOC sections */ 789 buf_addr = purgatory_buf; 790 load_addr = curr_load_addr = pi->purgatory_load_addr; 791 bss_addr = load_addr + buf_sz + bss_pad; 792 793 for (i = 0; i < pi->ehdr->e_shnum; i++) { 794 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 795 continue; 796 797 align = sechdrs[i].sh_addralign; 798 if (sechdrs[i].sh_type != SHT_NOBITS) { 799 curr_load_addr = ALIGN(curr_load_addr, align); 800 offset = curr_load_addr - load_addr; 801 /* We already modifed ->sh_offset to keep src addr */ 802 src = (char *) sechdrs[i].sh_offset; 803 memcpy(buf_addr + offset, src, sechdrs[i].sh_size); 804 805 /* Store load address and source address of section */ 806 sechdrs[i].sh_addr = curr_load_addr; 807 808 /* 809 * This section got copied to temporary buffer. Update 810 * ->sh_offset accordingly. 811 */ 812 sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset); 813 814 /* Advance to the next address */ 815 curr_load_addr += sechdrs[i].sh_size; 816 } else { 817 bss_addr = ALIGN(bss_addr, align); 818 sechdrs[i].sh_addr = bss_addr; 819 bss_addr += sechdrs[i].sh_size; 820 } 821 } 822 823 /* Update entry point based on load address of text section */ 824 if (entry_sidx >= 0) 825 entry += sechdrs[entry_sidx].sh_addr; 826 827 /* Make kernel jump to purgatory after shutdown */ 828 image->start = entry; 829 830 /* Used later to get/set symbol values */ 831 pi->sechdrs = sechdrs; 832 833 /* 834 * Used later to identify which section is purgatory and skip it 835 * from checksumming. 836 */ 837 pi->purgatory_buf = purgatory_buf; 838 return ret; 839 out: 840 vfree(sechdrs); 841 vfree(purgatory_buf); 842 return ret; 843 } 844 845 static int kexec_apply_relocations(struct kimage *image) 846 { 847 int i, ret; 848 struct purgatory_info *pi = &image->purgatory_info; 849 Elf_Shdr *sechdrs = pi->sechdrs; 850 851 /* Apply relocations */ 852 for (i = 0; i < pi->ehdr->e_shnum; i++) { 853 Elf_Shdr *section, *symtab; 854 855 if (sechdrs[i].sh_type != SHT_RELA && 856 sechdrs[i].sh_type != SHT_REL) 857 continue; 858 859 /* 860 * For section of type SHT_RELA/SHT_REL, 861 * ->sh_link contains section header index of associated 862 * symbol table. And ->sh_info contains section header 863 * index of section to which relocations apply. 864 */ 865 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum || 866 sechdrs[i].sh_link >= pi->ehdr->e_shnum) 867 return -ENOEXEC; 868 869 section = &sechdrs[sechdrs[i].sh_info]; 870 symtab = &sechdrs[sechdrs[i].sh_link]; 871 872 if (!(section->sh_flags & SHF_ALLOC)) 873 continue; 874 875 /* 876 * symtab->sh_link contain section header index of associated 877 * string table. 878 */ 879 if (symtab->sh_link >= pi->ehdr->e_shnum) 880 /* Invalid section number? */ 881 continue; 882 883 /* 884 * Respective architecture needs to provide support for applying 885 * relocations of type SHT_RELA/SHT_REL. 886 */ 887 if (sechdrs[i].sh_type == SHT_RELA) 888 ret = arch_kexec_apply_relocations_add(pi->ehdr, 889 sechdrs, i); 890 else if (sechdrs[i].sh_type == SHT_REL) 891 ret = arch_kexec_apply_relocations(pi->ehdr, 892 sechdrs, i); 893 if (ret) 894 return ret; 895 } 896 897 return 0; 898 } 899 900 /* Load relocatable purgatory object and relocate it appropriately */ 901 int kexec_load_purgatory(struct kimage *image, unsigned long min, 902 unsigned long max, int top_down, 903 unsigned long *load_addr) 904 { 905 struct purgatory_info *pi = &image->purgatory_info; 906 int ret; 907 908 if (kexec_purgatory_size <= 0) 909 return -EINVAL; 910 911 if (kexec_purgatory_size < sizeof(Elf_Ehdr)) 912 return -ENOEXEC; 913 914 pi->ehdr = (Elf_Ehdr *)kexec_purgatory; 915 916 if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0 917 || pi->ehdr->e_type != ET_REL 918 || !elf_check_arch(pi->ehdr) 919 || pi->ehdr->e_shentsize != sizeof(Elf_Shdr)) 920 return -ENOEXEC; 921 922 if (pi->ehdr->e_shoff >= kexec_purgatory_size 923 || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) > 924 kexec_purgatory_size - pi->ehdr->e_shoff)) 925 return -ENOEXEC; 926 927 ret = __kexec_load_purgatory(image, min, max, top_down); 928 if (ret) 929 return ret; 930 931 ret = kexec_apply_relocations(image); 932 if (ret) 933 goto out; 934 935 *load_addr = pi->purgatory_load_addr; 936 return 0; 937 out: 938 vfree(pi->sechdrs); 939 vfree(pi->purgatory_buf); 940 return ret; 941 } 942 943 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, 944 const char *name) 945 { 946 Elf_Sym *syms; 947 Elf_Shdr *sechdrs; 948 Elf_Ehdr *ehdr; 949 int i, k; 950 const char *strtab; 951 952 if (!pi->sechdrs || !pi->ehdr) 953 return NULL; 954 955 sechdrs = pi->sechdrs; 956 ehdr = pi->ehdr; 957 958 for (i = 0; i < ehdr->e_shnum; i++) { 959 if (sechdrs[i].sh_type != SHT_SYMTAB) 960 continue; 961 962 if (sechdrs[i].sh_link >= ehdr->e_shnum) 963 /* Invalid strtab section number */ 964 continue; 965 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset; 966 syms = (Elf_Sym *)sechdrs[i].sh_offset; 967 968 /* Go through symbols for a match */ 969 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) { 970 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL) 971 continue; 972 973 if (strcmp(strtab + syms[k].st_name, name) != 0) 974 continue; 975 976 if (syms[k].st_shndx == SHN_UNDEF || 977 syms[k].st_shndx >= ehdr->e_shnum) { 978 pr_debug("Symbol: %s has bad section index %d.\n", 979 name, syms[k].st_shndx); 980 return NULL; 981 } 982 983 /* Found the symbol we are looking for */ 984 return &syms[k]; 985 } 986 } 987 988 return NULL; 989 } 990 991 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name) 992 { 993 struct purgatory_info *pi = &image->purgatory_info; 994 Elf_Sym *sym; 995 Elf_Shdr *sechdr; 996 997 sym = kexec_purgatory_find_symbol(pi, name); 998 if (!sym) 999 return ERR_PTR(-EINVAL); 1000 1001 sechdr = &pi->sechdrs[sym->st_shndx]; 1002 1003 /* 1004 * Returns the address where symbol will finally be loaded after 1005 * kexec_load_segment() 1006 */ 1007 return (void *)(sechdr->sh_addr + sym->st_value); 1008 } 1009 1010 /* 1011 * Get or set value of a symbol. If "get_value" is true, symbol value is 1012 * returned in buf otherwise symbol value is set based on value in buf. 1013 */ 1014 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, 1015 void *buf, unsigned int size, bool get_value) 1016 { 1017 Elf_Sym *sym; 1018 Elf_Shdr *sechdrs; 1019 struct purgatory_info *pi = &image->purgatory_info; 1020 char *sym_buf; 1021 1022 sym = kexec_purgatory_find_symbol(pi, name); 1023 if (!sym) 1024 return -EINVAL; 1025 1026 if (sym->st_size != size) { 1027 pr_err("symbol %s size mismatch: expected %lu actual %u\n", 1028 name, (unsigned long)sym->st_size, size); 1029 return -EINVAL; 1030 } 1031 1032 sechdrs = pi->sechdrs; 1033 1034 if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) { 1035 pr_err("symbol %s is in a bss section. Cannot %s\n", name, 1036 get_value ? "get" : "set"); 1037 return -EINVAL; 1038 } 1039 1040 sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset + 1041 sym->st_value; 1042 1043 if (get_value) 1044 memcpy((void *)buf, sym_buf, size); 1045 else 1046 memcpy((void *)sym_buf, buf, size); 1047 1048 return 0; 1049 } 1050