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 <linux/ima.h> 23 #include <crypto/hash.h> 24 #include <crypto/sha.h> 25 #include <linux/syscalls.h> 26 #include <linux/vmalloc.h> 27 #include "kexec_internal.h" 28 29 /* 30 * Declare these symbols weak so that if architecture provides a purgatory, 31 * these will be overridden. 32 */ 33 char __weak kexec_purgatory[0]; 34 size_t __weak kexec_purgatory_size = 0; 35 36 static int kexec_calculate_store_digests(struct kimage *image); 37 38 /* Architectures can provide this probe function */ 39 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf, 40 unsigned long buf_len) 41 { 42 return -ENOEXEC; 43 } 44 45 void * __weak arch_kexec_kernel_image_load(struct kimage *image) 46 { 47 return ERR_PTR(-ENOEXEC); 48 } 49 50 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image) 51 { 52 return -EINVAL; 53 } 54 55 #ifdef CONFIG_KEXEC_VERIFY_SIG 56 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf, 57 unsigned long buf_len) 58 { 59 return -EKEYREJECTED; 60 } 61 #endif 62 63 /* Apply relocations of type RELA */ 64 int __weak 65 arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 66 unsigned int relsec) 67 { 68 pr_err("RELA relocation unsupported.\n"); 69 return -ENOEXEC; 70 } 71 72 /* Apply relocations of type REL */ 73 int __weak 74 arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 75 unsigned int relsec) 76 { 77 pr_err("REL relocation unsupported.\n"); 78 return -ENOEXEC; 79 } 80 81 /* 82 * Free up memory used by kernel, initrd, and command line. This is temporary 83 * memory allocation which is not needed any more after these buffers have 84 * been loaded into separate segments and have been copied elsewhere. 85 */ 86 void kimage_file_post_load_cleanup(struct kimage *image) 87 { 88 struct purgatory_info *pi = &image->purgatory_info; 89 90 vfree(image->kernel_buf); 91 image->kernel_buf = NULL; 92 93 vfree(image->initrd_buf); 94 image->initrd_buf = NULL; 95 96 kfree(image->cmdline_buf); 97 image->cmdline_buf = NULL; 98 99 vfree(pi->purgatory_buf); 100 pi->purgatory_buf = NULL; 101 102 vfree(pi->sechdrs); 103 pi->sechdrs = NULL; 104 105 /* See if architecture has anything to cleanup post load */ 106 arch_kimage_file_post_load_cleanup(image); 107 108 /* 109 * Above call should have called into bootloader to free up 110 * any data stored in kimage->image_loader_data. It should 111 * be ok now to free it up. 112 */ 113 kfree(image->image_loader_data); 114 image->image_loader_data = NULL; 115 } 116 117 /* 118 * In file mode list of segments is prepared by kernel. Copy relevant 119 * data from user space, do error checking, prepare segment list 120 */ 121 static int 122 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, 123 const char __user *cmdline_ptr, 124 unsigned long cmdline_len, unsigned flags) 125 { 126 int ret = 0; 127 void *ldata; 128 loff_t size; 129 130 ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf, 131 &size, INT_MAX, READING_KEXEC_IMAGE); 132 if (ret) 133 return ret; 134 image->kernel_buf_len = size; 135 136 /* IMA needs to pass the measurement list to the next kernel. */ 137 ima_add_kexec_buffer(image); 138 139 /* Call arch image probe handlers */ 140 ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, 141 image->kernel_buf_len); 142 if (ret) 143 goto out; 144 145 #ifdef CONFIG_KEXEC_VERIFY_SIG 146 ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, 147 image->kernel_buf_len); 148 if (ret) { 149 pr_debug("kernel signature verification failed.\n"); 150 goto out; 151 } 152 pr_debug("kernel signature verification successful.\n"); 153 #endif 154 /* It is possible that there no initramfs is being loaded */ 155 if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { 156 ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf, 157 &size, INT_MAX, 158 READING_KEXEC_INITRAMFS); 159 if (ret) 160 goto out; 161 image->initrd_buf_len = size; 162 } 163 164 if (cmdline_len) { 165 image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL); 166 if (!image->cmdline_buf) { 167 ret = -ENOMEM; 168 goto out; 169 } 170 171 ret = copy_from_user(image->cmdline_buf, cmdline_ptr, 172 cmdline_len); 173 if (ret) { 174 ret = -EFAULT; 175 goto out; 176 } 177 178 image->cmdline_buf_len = cmdline_len; 179 180 /* command line should be a string with last byte null */ 181 if (image->cmdline_buf[cmdline_len - 1] != '\0') { 182 ret = -EINVAL; 183 goto out; 184 } 185 } 186 187 /* Call arch image load handlers */ 188 ldata = arch_kexec_kernel_image_load(image); 189 190 if (IS_ERR(ldata)) { 191 ret = PTR_ERR(ldata); 192 goto out; 193 } 194 195 image->image_loader_data = ldata; 196 out: 197 /* In case of error, free up all allocated memory in this function */ 198 if (ret) 199 kimage_file_post_load_cleanup(image); 200 return ret; 201 } 202 203 static int 204 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd, 205 int initrd_fd, const char __user *cmdline_ptr, 206 unsigned long cmdline_len, unsigned long flags) 207 { 208 int ret; 209 struct kimage *image; 210 bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH; 211 212 image = do_kimage_alloc_init(); 213 if (!image) 214 return -ENOMEM; 215 216 image->file_mode = 1; 217 218 if (kexec_on_panic) { 219 /* Enable special crash kernel control page alloc policy. */ 220 image->control_page = crashk_res.start; 221 image->type = KEXEC_TYPE_CRASH; 222 } 223 224 ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd, 225 cmdline_ptr, cmdline_len, flags); 226 if (ret) 227 goto out_free_image; 228 229 ret = sanity_check_segment_list(image); 230 if (ret) 231 goto out_free_post_load_bufs; 232 233 ret = -ENOMEM; 234 image->control_code_page = kimage_alloc_control_pages(image, 235 get_order(KEXEC_CONTROL_PAGE_SIZE)); 236 if (!image->control_code_page) { 237 pr_err("Could not allocate control_code_buffer\n"); 238 goto out_free_post_load_bufs; 239 } 240 241 if (!kexec_on_panic) { 242 image->swap_page = kimage_alloc_control_pages(image, 0); 243 if (!image->swap_page) { 244 pr_err("Could not allocate swap buffer\n"); 245 goto out_free_control_pages; 246 } 247 } 248 249 *rimage = image; 250 return 0; 251 out_free_control_pages: 252 kimage_free_page_list(&image->control_pages); 253 out_free_post_load_bufs: 254 kimage_file_post_load_cleanup(image); 255 out_free_image: 256 kfree(image); 257 return ret; 258 } 259 260 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, 261 unsigned long, cmdline_len, const char __user *, cmdline_ptr, 262 unsigned long, flags) 263 { 264 int ret = 0, i; 265 struct kimage **dest_image, *image; 266 267 /* We only trust the superuser with rebooting the system. */ 268 if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) 269 return -EPERM; 270 271 /* Make sure we have a legal set of flags */ 272 if (flags != (flags & KEXEC_FILE_FLAGS)) 273 return -EINVAL; 274 275 image = NULL; 276 277 if (!mutex_trylock(&kexec_mutex)) 278 return -EBUSY; 279 280 dest_image = &kexec_image; 281 if (flags & KEXEC_FILE_ON_CRASH) { 282 dest_image = &kexec_crash_image; 283 if (kexec_crash_image) 284 arch_kexec_unprotect_crashkres(); 285 } 286 287 if (flags & KEXEC_FILE_UNLOAD) 288 goto exchange; 289 290 /* 291 * In case of crash, new kernel gets loaded in reserved region. It is 292 * same memory where old crash kernel might be loaded. Free any 293 * current crash dump kernel before we corrupt it. 294 */ 295 if (flags & KEXEC_FILE_ON_CRASH) 296 kimage_free(xchg(&kexec_crash_image, NULL)); 297 298 ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr, 299 cmdline_len, flags); 300 if (ret) 301 goto out; 302 303 ret = machine_kexec_prepare(image); 304 if (ret) 305 goto out; 306 307 ret = kexec_calculate_store_digests(image); 308 if (ret) 309 goto out; 310 311 for (i = 0; i < image->nr_segments; i++) { 312 struct kexec_segment *ksegment; 313 314 ksegment = &image->segment[i]; 315 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n", 316 i, ksegment->buf, ksegment->bufsz, ksegment->mem, 317 ksegment->memsz); 318 319 ret = kimage_load_segment(image, &image->segment[i]); 320 if (ret) 321 goto out; 322 } 323 324 kimage_terminate(image); 325 326 /* 327 * Free up any temporary buffers allocated which are not needed 328 * after image has been loaded 329 */ 330 kimage_file_post_load_cleanup(image); 331 exchange: 332 image = xchg(dest_image, image); 333 out: 334 if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image) 335 arch_kexec_protect_crashkres(); 336 337 mutex_unlock(&kexec_mutex); 338 kimage_free(image); 339 return ret; 340 } 341 342 static int locate_mem_hole_top_down(unsigned long start, unsigned long end, 343 struct kexec_buf *kbuf) 344 { 345 struct kimage *image = kbuf->image; 346 unsigned long temp_start, temp_end; 347 348 temp_end = min(end, kbuf->buf_max); 349 temp_start = temp_end - kbuf->memsz; 350 351 do { 352 /* align down start */ 353 temp_start = temp_start & (~(kbuf->buf_align - 1)); 354 355 if (temp_start < start || temp_start < kbuf->buf_min) 356 return 0; 357 358 temp_end = temp_start + kbuf->memsz - 1; 359 360 /* 361 * Make sure this does not conflict with any of existing 362 * segments 363 */ 364 if (kimage_is_destination_range(image, temp_start, temp_end)) { 365 temp_start = temp_start - PAGE_SIZE; 366 continue; 367 } 368 369 /* We found a suitable memory range */ 370 break; 371 } while (1); 372 373 /* If we are here, we found a suitable memory range */ 374 kbuf->mem = temp_start; 375 376 /* Success, stop navigating through remaining System RAM ranges */ 377 return 1; 378 } 379 380 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, 381 struct kexec_buf *kbuf) 382 { 383 struct kimage *image = kbuf->image; 384 unsigned long temp_start, temp_end; 385 386 temp_start = max(start, kbuf->buf_min); 387 388 do { 389 temp_start = ALIGN(temp_start, kbuf->buf_align); 390 temp_end = temp_start + kbuf->memsz - 1; 391 392 if (temp_end > end || temp_end > kbuf->buf_max) 393 return 0; 394 /* 395 * Make sure this does not conflict with any of existing 396 * segments 397 */ 398 if (kimage_is_destination_range(image, temp_start, temp_end)) { 399 temp_start = temp_start + PAGE_SIZE; 400 continue; 401 } 402 403 /* We found a suitable memory range */ 404 break; 405 } while (1); 406 407 /* If we are here, we found a suitable memory range */ 408 kbuf->mem = temp_start; 409 410 /* Success, stop navigating through remaining System RAM ranges */ 411 return 1; 412 } 413 414 static int locate_mem_hole_callback(u64 start, u64 end, void *arg) 415 { 416 struct kexec_buf *kbuf = (struct kexec_buf *)arg; 417 unsigned long sz = end - start + 1; 418 419 /* Returning 0 will take to next memory range */ 420 if (sz < kbuf->memsz) 421 return 0; 422 423 if (end < kbuf->buf_min || start > kbuf->buf_max) 424 return 0; 425 426 /* 427 * Allocate memory top down with-in ram range. Otherwise bottom up 428 * allocation. 429 */ 430 if (kbuf->top_down) 431 return locate_mem_hole_top_down(start, end, kbuf); 432 return locate_mem_hole_bottom_up(start, end, kbuf); 433 } 434 435 /** 436 * arch_kexec_walk_mem - call func(data) on free memory regions 437 * @kbuf: Context info for the search. Also passed to @func. 438 * @func: Function to call for each memory region. 439 * 440 * Return: The memory walk will stop when func returns a non-zero value 441 * and that value will be returned. If all free regions are visited without 442 * func returning non-zero, then zero will be returned. 443 */ 444 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf, 445 int (*func)(u64, u64, void *)) 446 { 447 if (kbuf->image->type == KEXEC_TYPE_CRASH) 448 return walk_iomem_res_desc(crashk_res.desc, 449 IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY, 450 crashk_res.start, crashk_res.end, 451 kbuf, func); 452 else 453 return walk_system_ram_res(0, ULONG_MAX, kbuf, func); 454 } 455 456 /** 457 * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel 458 * @kbuf: Parameters for the memory search. 459 * 460 * On success, kbuf->mem will have the start address of the memory region found. 461 * 462 * Return: 0 on success, negative errno on error. 463 */ 464 int kexec_locate_mem_hole(struct kexec_buf *kbuf) 465 { 466 int ret; 467 468 ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback); 469 470 return ret == 1 ? 0 : -EADDRNOTAVAIL; 471 } 472 473 /** 474 * kexec_add_buffer - place a buffer in a kexec segment 475 * @kbuf: Buffer contents and memory parameters. 476 * 477 * This function assumes that kexec_mutex is held. 478 * On successful return, @kbuf->mem will have the physical address of 479 * the buffer in memory. 480 * 481 * Return: 0 on success, negative errno on error. 482 */ 483 int kexec_add_buffer(struct kexec_buf *kbuf) 484 { 485 486 struct kexec_segment *ksegment; 487 int ret; 488 489 /* Currently adding segment this way is allowed only in file mode */ 490 if (!kbuf->image->file_mode) 491 return -EINVAL; 492 493 if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX) 494 return -EINVAL; 495 496 /* 497 * Make sure we are not trying to add buffer after allocating 498 * control pages. All segments need to be placed first before 499 * any control pages are allocated. As control page allocation 500 * logic goes through list of segments to make sure there are 501 * no destination overlaps. 502 */ 503 if (!list_empty(&kbuf->image->control_pages)) { 504 WARN_ON(1); 505 return -EINVAL; 506 } 507 508 /* Ensure minimum alignment needed for segments. */ 509 kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE); 510 kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE); 511 512 /* Walk the RAM ranges and allocate a suitable range for the buffer */ 513 ret = kexec_locate_mem_hole(kbuf); 514 if (ret) 515 return ret; 516 517 /* Found a suitable memory range */ 518 ksegment = &kbuf->image->segment[kbuf->image->nr_segments]; 519 ksegment->kbuf = kbuf->buffer; 520 ksegment->bufsz = kbuf->bufsz; 521 ksegment->mem = kbuf->mem; 522 ksegment->memsz = kbuf->memsz; 523 kbuf->image->nr_segments++; 524 return 0; 525 } 526 527 /* Calculate and store the digest of segments */ 528 static int kexec_calculate_store_digests(struct kimage *image) 529 { 530 struct crypto_shash *tfm; 531 struct shash_desc *desc; 532 int ret = 0, i, j, zero_buf_sz, sha_region_sz; 533 size_t desc_size, nullsz; 534 char *digest; 535 void *zero_buf; 536 struct kexec_sha_region *sha_regions; 537 struct purgatory_info *pi = &image->purgatory_info; 538 539 zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT); 540 zero_buf_sz = PAGE_SIZE; 541 542 tfm = crypto_alloc_shash("sha256", 0, 0); 543 if (IS_ERR(tfm)) { 544 ret = PTR_ERR(tfm); 545 goto out; 546 } 547 548 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); 549 desc = kzalloc(desc_size, GFP_KERNEL); 550 if (!desc) { 551 ret = -ENOMEM; 552 goto out_free_tfm; 553 } 554 555 sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region); 556 sha_regions = vzalloc(sha_region_sz); 557 if (!sha_regions) 558 goto out_free_desc; 559 560 desc->tfm = tfm; 561 desc->flags = 0; 562 563 ret = crypto_shash_init(desc); 564 if (ret < 0) 565 goto out_free_sha_regions; 566 567 digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL); 568 if (!digest) { 569 ret = -ENOMEM; 570 goto out_free_sha_regions; 571 } 572 573 for (j = i = 0; i < image->nr_segments; i++) { 574 struct kexec_segment *ksegment; 575 576 ksegment = &image->segment[i]; 577 /* 578 * Skip purgatory as it will be modified once we put digest 579 * info in purgatory. 580 */ 581 if (ksegment->kbuf == pi->purgatory_buf) 582 continue; 583 584 ret = crypto_shash_update(desc, ksegment->kbuf, 585 ksegment->bufsz); 586 if (ret) 587 break; 588 589 /* 590 * Assume rest of the buffer is filled with zero and 591 * update digest accordingly. 592 */ 593 nullsz = ksegment->memsz - ksegment->bufsz; 594 while (nullsz) { 595 unsigned long bytes = nullsz; 596 597 if (bytes > zero_buf_sz) 598 bytes = zero_buf_sz; 599 ret = crypto_shash_update(desc, zero_buf, bytes); 600 if (ret) 601 break; 602 nullsz -= bytes; 603 } 604 605 if (ret) 606 break; 607 608 sha_regions[j].start = ksegment->mem; 609 sha_regions[j].len = ksegment->memsz; 610 j++; 611 } 612 613 if (!ret) { 614 ret = crypto_shash_final(desc, digest); 615 if (ret) 616 goto out_free_digest; 617 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions", 618 sha_regions, sha_region_sz, 0); 619 if (ret) 620 goto out_free_digest; 621 622 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest", 623 digest, SHA256_DIGEST_SIZE, 0); 624 if (ret) 625 goto out_free_digest; 626 } 627 628 out_free_digest: 629 kfree(digest); 630 out_free_sha_regions: 631 vfree(sha_regions); 632 out_free_desc: 633 kfree(desc); 634 out_free_tfm: 635 kfree(tfm); 636 out: 637 return ret; 638 } 639 640 /* Actually load purgatory. Lot of code taken from kexec-tools */ 641 static int __kexec_load_purgatory(struct kimage *image, unsigned long min, 642 unsigned long max, int top_down) 643 { 644 struct purgatory_info *pi = &image->purgatory_info; 645 unsigned long align, bss_align, bss_sz, bss_pad; 646 unsigned long entry, load_addr, curr_load_addr, bss_addr, offset; 647 unsigned char *buf_addr, *src; 648 int i, ret = 0, entry_sidx = -1; 649 const Elf_Shdr *sechdrs_c; 650 Elf_Shdr *sechdrs = NULL; 651 struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1, 652 .buf_min = min, .buf_max = max, 653 .top_down = top_down }; 654 655 /* 656 * sechdrs_c points to section headers in purgatory and are read 657 * only. No modifications allowed. 658 */ 659 sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff; 660 661 /* 662 * We can not modify sechdrs_c[] and its fields. It is read only. 663 * Copy it over to a local copy where one can store some temporary 664 * data and free it at the end. We need to modify ->sh_addr and 665 * ->sh_offset fields to keep track of permanent and temporary 666 * locations of sections. 667 */ 668 sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 669 if (!sechdrs) 670 return -ENOMEM; 671 672 memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 673 674 /* 675 * We seem to have multiple copies of sections. First copy is which 676 * is embedded in kernel in read only section. Some of these sections 677 * will be copied to a temporary buffer and relocated. And these 678 * sections will finally be copied to their final destination at 679 * segment load time. 680 * 681 * Use ->sh_offset to reflect section address in memory. It will 682 * point to original read only copy if section is not allocatable. 683 * Otherwise it will point to temporary copy which will be relocated. 684 * 685 * Use ->sh_addr to contain final address of the section where it 686 * will go during execution time. 687 */ 688 for (i = 0; i < pi->ehdr->e_shnum; i++) { 689 if (sechdrs[i].sh_type == SHT_NOBITS) 690 continue; 691 692 sechdrs[i].sh_offset = (unsigned long)pi->ehdr + 693 sechdrs[i].sh_offset; 694 } 695 696 /* 697 * Identify entry point section and make entry relative to section 698 * start. 699 */ 700 entry = pi->ehdr->e_entry; 701 for (i = 0; i < pi->ehdr->e_shnum; i++) { 702 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 703 continue; 704 705 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR)) 706 continue; 707 708 /* Make entry section relative */ 709 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry && 710 ((sechdrs[i].sh_addr + sechdrs[i].sh_size) > 711 pi->ehdr->e_entry)) { 712 entry_sidx = i; 713 entry -= sechdrs[i].sh_addr; 714 break; 715 } 716 } 717 718 /* Determine how much memory is needed to load relocatable object. */ 719 bss_align = 1; 720 bss_sz = 0; 721 722 for (i = 0; i < pi->ehdr->e_shnum; i++) { 723 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 724 continue; 725 726 align = sechdrs[i].sh_addralign; 727 if (sechdrs[i].sh_type != SHT_NOBITS) { 728 if (kbuf.buf_align < align) 729 kbuf.buf_align = align; 730 kbuf.bufsz = ALIGN(kbuf.bufsz, align); 731 kbuf.bufsz += sechdrs[i].sh_size; 732 } else { 733 /* bss section */ 734 if (bss_align < align) 735 bss_align = align; 736 bss_sz = ALIGN(bss_sz, align); 737 bss_sz += sechdrs[i].sh_size; 738 } 739 } 740 741 /* Determine the bss padding required to align bss properly */ 742 bss_pad = 0; 743 if (kbuf.bufsz & (bss_align - 1)) 744 bss_pad = bss_align - (kbuf.bufsz & (bss_align - 1)); 745 746 kbuf.memsz = kbuf.bufsz + bss_pad + bss_sz; 747 748 /* Allocate buffer for purgatory */ 749 kbuf.buffer = vzalloc(kbuf.bufsz); 750 if (!kbuf.buffer) { 751 ret = -ENOMEM; 752 goto out; 753 } 754 755 if (kbuf.buf_align < bss_align) 756 kbuf.buf_align = bss_align; 757 758 /* Add buffer to segment list */ 759 ret = kexec_add_buffer(&kbuf); 760 if (ret) 761 goto out; 762 pi->purgatory_load_addr = kbuf.mem; 763 764 /* Load SHF_ALLOC sections */ 765 buf_addr = kbuf.buffer; 766 load_addr = curr_load_addr = pi->purgatory_load_addr; 767 bss_addr = load_addr + kbuf.bufsz + bss_pad; 768 769 for (i = 0; i < pi->ehdr->e_shnum; i++) { 770 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 771 continue; 772 773 align = sechdrs[i].sh_addralign; 774 if (sechdrs[i].sh_type != SHT_NOBITS) { 775 curr_load_addr = ALIGN(curr_load_addr, align); 776 offset = curr_load_addr - load_addr; 777 /* We already modifed ->sh_offset to keep src addr */ 778 src = (char *) sechdrs[i].sh_offset; 779 memcpy(buf_addr + offset, src, sechdrs[i].sh_size); 780 781 /* Store load address and source address of section */ 782 sechdrs[i].sh_addr = curr_load_addr; 783 784 /* 785 * This section got copied to temporary buffer. Update 786 * ->sh_offset accordingly. 787 */ 788 sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset); 789 790 /* Advance to the next address */ 791 curr_load_addr += sechdrs[i].sh_size; 792 } else { 793 bss_addr = ALIGN(bss_addr, align); 794 sechdrs[i].sh_addr = bss_addr; 795 bss_addr += sechdrs[i].sh_size; 796 } 797 } 798 799 /* Update entry point based on load address of text section */ 800 if (entry_sidx >= 0) 801 entry += sechdrs[entry_sidx].sh_addr; 802 803 /* Make kernel jump to purgatory after shutdown */ 804 image->start = entry; 805 806 /* Used later to get/set symbol values */ 807 pi->sechdrs = sechdrs; 808 809 /* 810 * Used later to identify which section is purgatory and skip it 811 * from checksumming. 812 */ 813 pi->purgatory_buf = kbuf.buffer; 814 return ret; 815 out: 816 vfree(sechdrs); 817 vfree(kbuf.buffer); 818 return ret; 819 } 820 821 static int kexec_apply_relocations(struct kimage *image) 822 { 823 int i, ret; 824 struct purgatory_info *pi = &image->purgatory_info; 825 Elf_Shdr *sechdrs = pi->sechdrs; 826 827 /* Apply relocations */ 828 for (i = 0; i < pi->ehdr->e_shnum; i++) { 829 Elf_Shdr *section, *symtab; 830 831 if (sechdrs[i].sh_type != SHT_RELA && 832 sechdrs[i].sh_type != SHT_REL) 833 continue; 834 835 /* 836 * For section of type SHT_RELA/SHT_REL, 837 * ->sh_link contains section header index of associated 838 * symbol table. And ->sh_info contains section header 839 * index of section to which relocations apply. 840 */ 841 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum || 842 sechdrs[i].sh_link >= pi->ehdr->e_shnum) 843 return -ENOEXEC; 844 845 section = &sechdrs[sechdrs[i].sh_info]; 846 symtab = &sechdrs[sechdrs[i].sh_link]; 847 848 if (!(section->sh_flags & SHF_ALLOC)) 849 continue; 850 851 /* 852 * symtab->sh_link contain section header index of associated 853 * string table. 854 */ 855 if (symtab->sh_link >= pi->ehdr->e_shnum) 856 /* Invalid section number? */ 857 continue; 858 859 /* 860 * Respective architecture needs to provide support for applying 861 * relocations of type SHT_RELA/SHT_REL. 862 */ 863 if (sechdrs[i].sh_type == SHT_RELA) 864 ret = arch_kexec_apply_relocations_add(pi->ehdr, 865 sechdrs, i); 866 else if (sechdrs[i].sh_type == SHT_REL) 867 ret = arch_kexec_apply_relocations(pi->ehdr, 868 sechdrs, i); 869 if (ret) 870 return ret; 871 } 872 873 return 0; 874 } 875 876 /* Load relocatable purgatory object and relocate it appropriately */ 877 int kexec_load_purgatory(struct kimage *image, unsigned long min, 878 unsigned long max, int top_down, 879 unsigned long *load_addr) 880 { 881 struct purgatory_info *pi = &image->purgatory_info; 882 int ret; 883 884 if (kexec_purgatory_size <= 0) 885 return -EINVAL; 886 887 if (kexec_purgatory_size < sizeof(Elf_Ehdr)) 888 return -ENOEXEC; 889 890 pi->ehdr = (Elf_Ehdr *)kexec_purgatory; 891 892 if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0 893 || pi->ehdr->e_type != ET_REL 894 || !elf_check_arch(pi->ehdr) 895 || pi->ehdr->e_shentsize != sizeof(Elf_Shdr)) 896 return -ENOEXEC; 897 898 if (pi->ehdr->e_shoff >= kexec_purgatory_size 899 || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) > 900 kexec_purgatory_size - pi->ehdr->e_shoff)) 901 return -ENOEXEC; 902 903 ret = __kexec_load_purgatory(image, min, max, top_down); 904 if (ret) 905 return ret; 906 907 ret = kexec_apply_relocations(image); 908 if (ret) 909 goto out; 910 911 *load_addr = pi->purgatory_load_addr; 912 return 0; 913 out: 914 vfree(pi->sechdrs); 915 pi->sechdrs = NULL; 916 917 vfree(pi->purgatory_buf); 918 pi->purgatory_buf = NULL; 919 return ret; 920 } 921 922 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, 923 const char *name) 924 { 925 Elf_Sym *syms; 926 Elf_Shdr *sechdrs; 927 Elf_Ehdr *ehdr; 928 int i, k; 929 const char *strtab; 930 931 if (!pi->sechdrs || !pi->ehdr) 932 return NULL; 933 934 sechdrs = pi->sechdrs; 935 ehdr = pi->ehdr; 936 937 for (i = 0; i < ehdr->e_shnum; i++) { 938 if (sechdrs[i].sh_type != SHT_SYMTAB) 939 continue; 940 941 if (sechdrs[i].sh_link >= ehdr->e_shnum) 942 /* Invalid strtab section number */ 943 continue; 944 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset; 945 syms = (Elf_Sym *)sechdrs[i].sh_offset; 946 947 /* Go through symbols for a match */ 948 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) { 949 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL) 950 continue; 951 952 if (strcmp(strtab + syms[k].st_name, name) != 0) 953 continue; 954 955 if (syms[k].st_shndx == SHN_UNDEF || 956 syms[k].st_shndx >= ehdr->e_shnum) { 957 pr_debug("Symbol: %s has bad section index %d.\n", 958 name, syms[k].st_shndx); 959 return NULL; 960 } 961 962 /* Found the symbol we are looking for */ 963 return &syms[k]; 964 } 965 } 966 967 return NULL; 968 } 969 970 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name) 971 { 972 struct purgatory_info *pi = &image->purgatory_info; 973 Elf_Sym *sym; 974 Elf_Shdr *sechdr; 975 976 sym = kexec_purgatory_find_symbol(pi, name); 977 if (!sym) 978 return ERR_PTR(-EINVAL); 979 980 sechdr = &pi->sechdrs[sym->st_shndx]; 981 982 /* 983 * Returns the address where symbol will finally be loaded after 984 * kexec_load_segment() 985 */ 986 return (void *)(sechdr->sh_addr + sym->st_value); 987 } 988 989 /* 990 * Get or set value of a symbol. If "get_value" is true, symbol value is 991 * returned in buf otherwise symbol value is set based on value in buf. 992 */ 993 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, 994 void *buf, unsigned int size, bool get_value) 995 { 996 Elf_Sym *sym; 997 Elf_Shdr *sechdrs; 998 struct purgatory_info *pi = &image->purgatory_info; 999 char *sym_buf; 1000 1001 sym = kexec_purgatory_find_symbol(pi, name); 1002 if (!sym) 1003 return -EINVAL; 1004 1005 if (sym->st_size != size) { 1006 pr_err("symbol %s size mismatch: expected %lu actual %u\n", 1007 name, (unsigned long)sym->st_size, size); 1008 return -EINVAL; 1009 } 1010 1011 sechdrs = pi->sechdrs; 1012 1013 if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) { 1014 pr_err("symbol %s is in a bss section. Cannot %s\n", name, 1015 get_value ? "get" : "set"); 1016 return -EINVAL; 1017 } 1018 1019 sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset + 1020 sym->st_value; 1021 1022 if (get_value) 1023 memcpy((void *)buf, sym_buf, size); 1024 else 1025 memcpy((void *)sym_buf, buf, size); 1026 1027 return 0; 1028 } 1029