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 static int kexec_calculate_store_digests(struct kimage *image); 30 31 /* Architectures can provide this probe function */ 32 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf, 33 unsigned long buf_len) 34 { 35 return -ENOEXEC; 36 } 37 38 void * __weak arch_kexec_kernel_image_load(struct kimage *image) 39 { 40 return ERR_PTR(-ENOEXEC); 41 } 42 43 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image) 44 { 45 return -EINVAL; 46 } 47 48 #ifdef CONFIG_KEXEC_VERIFY_SIG 49 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf, 50 unsigned long buf_len) 51 { 52 return -EKEYREJECTED; 53 } 54 #endif 55 56 /* Apply relocations of type RELA */ 57 int __weak 58 arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 59 unsigned int relsec) 60 { 61 pr_err("RELA relocation unsupported.\n"); 62 return -ENOEXEC; 63 } 64 65 /* Apply relocations of type REL */ 66 int __weak 67 arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 68 unsigned int relsec) 69 { 70 pr_err("REL relocation unsupported.\n"); 71 return -ENOEXEC; 72 } 73 74 /* 75 * Free up memory used by kernel, initrd, and command line. This is temporary 76 * memory allocation which is not needed any more after these buffers have 77 * been loaded into separate segments and have been copied elsewhere. 78 */ 79 void kimage_file_post_load_cleanup(struct kimage *image) 80 { 81 struct purgatory_info *pi = &image->purgatory_info; 82 83 vfree(image->kernel_buf); 84 image->kernel_buf = NULL; 85 86 vfree(image->initrd_buf); 87 image->initrd_buf = NULL; 88 89 kfree(image->cmdline_buf); 90 image->cmdline_buf = NULL; 91 92 vfree(pi->purgatory_buf); 93 pi->purgatory_buf = NULL; 94 95 vfree(pi->sechdrs); 96 pi->sechdrs = NULL; 97 98 /* See if architecture has anything to cleanup post load */ 99 arch_kimage_file_post_load_cleanup(image); 100 101 /* 102 * Above call should have called into bootloader to free up 103 * any data stored in kimage->image_loader_data. It should 104 * be ok now to free it up. 105 */ 106 kfree(image->image_loader_data); 107 image->image_loader_data = NULL; 108 } 109 110 /* 111 * In file mode list of segments is prepared by kernel. Copy relevant 112 * data from user space, do error checking, prepare segment list 113 */ 114 static int 115 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, 116 const char __user *cmdline_ptr, 117 unsigned long cmdline_len, unsigned flags) 118 { 119 int ret = 0; 120 void *ldata; 121 loff_t size; 122 123 ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf, 124 &size, INT_MAX, READING_KEXEC_IMAGE); 125 if (ret) 126 return ret; 127 image->kernel_buf_len = size; 128 129 /* IMA needs to pass the measurement list to the next kernel. */ 130 ima_add_kexec_buffer(image); 131 132 /* Call arch image probe handlers */ 133 ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, 134 image->kernel_buf_len); 135 if (ret) 136 goto out; 137 138 #ifdef CONFIG_KEXEC_VERIFY_SIG 139 ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, 140 image->kernel_buf_len); 141 if (ret) { 142 pr_debug("kernel signature verification failed.\n"); 143 goto out; 144 } 145 pr_debug("kernel signature verification successful.\n"); 146 #endif 147 /* It is possible that there no initramfs is being loaded */ 148 if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { 149 ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf, 150 &size, INT_MAX, 151 READING_KEXEC_INITRAMFS); 152 if (ret) 153 goto out; 154 image->initrd_buf_len = size; 155 } 156 157 if (cmdline_len) { 158 image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len); 159 if (IS_ERR(image->cmdline_buf)) { 160 ret = PTR_ERR(image->cmdline_buf); 161 image->cmdline_buf = NULL; 162 goto out; 163 } 164 165 image->cmdline_buf_len = cmdline_len; 166 167 /* command line should be a string with last byte null */ 168 if (image->cmdline_buf[cmdline_len - 1] != '\0') { 169 ret = -EINVAL; 170 goto out; 171 } 172 } 173 174 /* Call arch image load handlers */ 175 ldata = arch_kexec_kernel_image_load(image); 176 177 if (IS_ERR(ldata)) { 178 ret = PTR_ERR(ldata); 179 goto out; 180 } 181 182 image->image_loader_data = ldata; 183 out: 184 /* In case of error, free up all allocated memory in this function */ 185 if (ret) 186 kimage_file_post_load_cleanup(image); 187 return ret; 188 } 189 190 static int 191 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd, 192 int initrd_fd, const char __user *cmdline_ptr, 193 unsigned long cmdline_len, unsigned long flags) 194 { 195 int ret; 196 struct kimage *image; 197 bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH; 198 199 image = do_kimage_alloc_init(); 200 if (!image) 201 return -ENOMEM; 202 203 image->file_mode = 1; 204 205 if (kexec_on_panic) { 206 /* Enable special crash kernel control page alloc policy. */ 207 image->control_page = crashk_res.start; 208 image->type = KEXEC_TYPE_CRASH; 209 } 210 211 ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd, 212 cmdline_ptr, cmdline_len, flags); 213 if (ret) 214 goto out_free_image; 215 216 ret = sanity_check_segment_list(image); 217 if (ret) 218 goto out_free_post_load_bufs; 219 220 ret = -ENOMEM; 221 image->control_code_page = kimage_alloc_control_pages(image, 222 get_order(KEXEC_CONTROL_PAGE_SIZE)); 223 if (!image->control_code_page) { 224 pr_err("Could not allocate control_code_buffer\n"); 225 goto out_free_post_load_bufs; 226 } 227 228 if (!kexec_on_panic) { 229 image->swap_page = kimage_alloc_control_pages(image, 0); 230 if (!image->swap_page) { 231 pr_err("Could not allocate swap buffer\n"); 232 goto out_free_control_pages; 233 } 234 } 235 236 *rimage = image; 237 return 0; 238 out_free_control_pages: 239 kimage_free_page_list(&image->control_pages); 240 out_free_post_load_bufs: 241 kimage_file_post_load_cleanup(image); 242 out_free_image: 243 kfree(image); 244 return ret; 245 } 246 247 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, 248 unsigned long, cmdline_len, const char __user *, cmdline_ptr, 249 unsigned long, flags) 250 { 251 int ret = 0, i; 252 struct kimage **dest_image, *image; 253 254 /* We only trust the superuser with rebooting the system. */ 255 if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) 256 return -EPERM; 257 258 /* Make sure we have a legal set of flags */ 259 if (flags != (flags & KEXEC_FILE_FLAGS)) 260 return -EINVAL; 261 262 image = NULL; 263 264 if (!mutex_trylock(&kexec_mutex)) 265 return -EBUSY; 266 267 dest_image = &kexec_image; 268 if (flags & KEXEC_FILE_ON_CRASH) { 269 dest_image = &kexec_crash_image; 270 if (kexec_crash_image) 271 arch_kexec_unprotect_crashkres(); 272 } 273 274 if (flags & KEXEC_FILE_UNLOAD) 275 goto exchange; 276 277 /* 278 * In case of crash, new kernel gets loaded in reserved region. It is 279 * same memory where old crash kernel might be loaded. Free any 280 * current crash dump kernel before we corrupt it. 281 */ 282 if (flags & KEXEC_FILE_ON_CRASH) 283 kimage_free(xchg(&kexec_crash_image, NULL)); 284 285 ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr, 286 cmdline_len, flags); 287 if (ret) 288 goto out; 289 290 ret = machine_kexec_prepare(image); 291 if (ret) 292 goto out; 293 294 /* 295 * Some architecture(like S390) may touch the crash memory before 296 * machine_kexec_prepare(), we must copy vmcoreinfo data after it. 297 */ 298 ret = kimage_crash_copy_vmcoreinfo(image); 299 if (ret) 300 goto out; 301 302 ret = kexec_calculate_store_digests(image); 303 if (ret) 304 goto out; 305 306 for (i = 0; i < image->nr_segments; i++) { 307 struct kexec_segment *ksegment; 308 309 ksegment = &image->segment[i]; 310 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n", 311 i, ksegment->buf, ksegment->bufsz, ksegment->mem, 312 ksegment->memsz); 313 314 ret = kimage_load_segment(image, &image->segment[i]); 315 if (ret) 316 goto out; 317 } 318 319 kimage_terminate(image); 320 321 /* 322 * Free up any temporary buffers allocated which are not needed 323 * after image has been loaded 324 */ 325 kimage_file_post_load_cleanup(image); 326 exchange: 327 image = xchg(dest_image, image); 328 out: 329 if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image) 330 arch_kexec_protect_crashkres(); 331 332 mutex_unlock(&kexec_mutex); 333 kimage_free(image); 334 return ret; 335 } 336 337 static int locate_mem_hole_top_down(unsigned long start, unsigned long end, 338 struct kexec_buf *kbuf) 339 { 340 struct kimage *image = kbuf->image; 341 unsigned long temp_start, temp_end; 342 343 temp_end = min(end, kbuf->buf_max); 344 temp_start = temp_end - kbuf->memsz; 345 346 do { 347 /* align down start */ 348 temp_start = temp_start & (~(kbuf->buf_align - 1)); 349 350 if (temp_start < start || temp_start < kbuf->buf_min) 351 return 0; 352 353 temp_end = temp_start + kbuf->memsz - 1; 354 355 /* 356 * Make sure this does not conflict with any of existing 357 * segments 358 */ 359 if (kimage_is_destination_range(image, temp_start, temp_end)) { 360 temp_start = temp_start - PAGE_SIZE; 361 continue; 362 } 363 364 /* We found a suitable memory range */ 365 break; 366 } while (1); 367 368 /* If we are here, we found a suitable memory range */ 369 kbuf->mem = temp_start; 370 371 /* Success, stop navigating through remaining System RAM ranges */ 372 return 1; 373 } 374 375 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, 376 struct kexec_buf *kbuf) 377 { 378 struct kimage *image = kbuf->image; 379 unsigned long temp_start, temp_end; 380 381 temp_start = max(start, kbuf->buf_min); 382 383 do { 384 temp_start = ALIGN(temp_start, kbuf->buf_align); 385 temp_end = temp_start + kbuf->memsz - 1; 386 387 if (temp_end > end || temp_end > kbuf->buf_max) 388 return 0; 389 /* 390 * Make sure this does not conflict with any of existing 391 * segments 392 */ 393 if (kimage_is_destination_range(image, temp_start, temp_end)) { 394 temp_start = temp_start + PAGE_SIZE; 395 continue; 396 } 397 398 /* We found a suitable memory range */ 399 break; 400 } while (1); 401 402 /* If we are here, we found a suitable memory range */ 403 kbuf->mem = temp_start; 404 405 /* Success, stop navigating through remaining System RAM ranges */ 406 return 1; 407 } 408 409 static int locate_mem_hole_callback(struct resource *res, void *arg) 410 { 411 struct kexec_buf *kbuf = (struct kexec_buf *)arg; 412 u64 start = res->start, end = res->end; 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 * arch_kexec_walk_mem - call func(data) on free memory regions 433 * @kbuf: Context info for the search. Also passed to @func. 434 * @func: Function to call for each memory region. 435 * 436 * Return: The memory walk will stop when func returns a non-zero value 437 * and that value will be returned. If all free regions are visited without 438 * func returning non-zero, then zero will be returned. 439 */ 440 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf, 441 int (*func)(struct resource *, void *)) 442 { 443 if (kbuf->image->type == KEXEC_TYPE_CRASH) 444 return walk_iomem_res_desc(crashk_res.desc, 445 IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY, 446 crashk_res.start, crashk_res.end, 447 kbuf, func); 448 else 449 return walk_system_ram_res(0, ULONG_MAX, kbuf, func); 450 } 451 452 /** 453 * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel 454 * @kbuf: Parameters for the memory search. 455 * 456 * On success, kbuf->mem will have the start address of the memory region found. 457 * 458 * Return: 0 on success, negative errno on error. 459 */ 460 int kexec_locate_mem_hole(struct kexec_buf *kbuf) 461 { 462 int ret; 463 464 ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback); 465 466 return ret == 1 ? 0 : -EADDRNOTAVAIL; 467 } 468 469 /** 470 * kexec_add_buffer - place a buffer in a kexec segment 471 * @kbuf: Buffer contents and memory parameters. 472 * 473 * This function assumes that kexec_mutex is held. 474 * On successful return, @kbuf->mem will have the physical address of 475 * the buffer in memory. 476 * 477 * Return: 0 on success, negative errno on error. 478 */ 479 int kexec_add_buffer(struct kexec_buf *kbuf) 480 { 481 482 struct kexec_segment *ksegment; 483 int ret; 484 485 /* Currently adding segment this way is allowed only in file mode */ 486 if (!kbuf->image->file_mode) 487 return -EINVAL; 488 489 if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX) 490 return -EINVAL; 491 492 /* 493 * Make sure we are not trying to add buffer after allocating 494 * control pages. All segments need to be placed first before 495 * any control pages are allocated. As control page allocation 496 * logic goes through list of segments to make sure there are 497 * no destination overlaps. 498 */ 499 if (!list_empty(&kbuf->image->control_pages)) { 500 WARN_ON(1); 501 return -EINVAL; 502 } 503 504 /* Ensure minimum alignment needed for segments. */ 505 kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE); 506 kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE); 507 508 /* Walk the RAM ranges and allocate a suitable range for the buffer */ 509 ret = kexec_locate_mem_hole(kbuf); 510 if (ret) 511 return ret; 512 513 /* Found a suitable memory range */ 514 ksegment = &kbuf->image->segment[kbuf->image->nr_segments]; 515 ksegment->kbuf = kbuf->buffer; 516 ksegment->bufsz = kbuf->bufsz; 517 ksegment->mem = kbuf->mem; 518 ksegment->memsz = kbuf->memsz; 519 kbuf->image->nr_segments++; 520 return 0; 521 } 522 523 /* Calculate and store the digest of segments */ 524 static int kexec_calculate_store_digests(struct kimage *image) 525 { 526 struct crypto_shash *tfm; 527 struct shash_desc *desc; 528 int ret = 0, i, j, zero_buf_sz, sha_region_sz; 529 size_t desc_size, nullsz; 530 char *digest; 531 void *zero_buf; 532 struct kexec_sha_region *sha_regions; 533 struct purgatory_info *pi = &image->purgatory_info; 534 535 zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT); 536 zero_buf_sz = PAGE_SIZE; 537 538 tfm = crypto_alloc_shash("sha256", 0, 0); 539 if (IS_ERR(tfm)) { 540 ret = PTR_ERR(tfm); 541 goto out; 542 } 543 544 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); 545 desc = kzalloc(desc_size, GFP_KERNEL); 546 if (!desc) { 547 ret = -ENOMEM; 548 goto out_free_tfm; 549 } 550 551 sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region); 552 sha_regions = vzalloc(sha_region_sz); 553 if (!sha_regions) 554 goto out_free_desc; 555 556 desc->tfm = tfm; 557 desc->flags = 0; 558 559 ret = crypto_shash_init(desc); 560 if (ret < 0) 561 goto out_free_sha_regions; 562 563 digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL); 564 if (!digest) { 565 ret = -ENOMEM; 566 goto out_free_sha_regions; 567 } 568 569 for (j = i = 0; i < image->nr_segments; i++) { 570 struct kexec_segment *ksegment; 571 572 ksegment = &image->segment[i]; 573 /* 574 * Skip purgatory as it will be modified once we put digest 575 * info in purgatory. 576 */ 577 if (ksegment->kbuf == pi->purgatory_buf) 578 continue; 579 580 ret = crypto_shash_update(desc, ksegment->kbuf, 581 ksegment->bufsz); 582 if (ret) 583 break; 584 585 /* 586 * Assume rest of the buffer is filled with zero and 587 * update digest accordingly. 588 */ 589 nullsz = ksegment->memsz - ksegment->bufsz; 590 while (nullsz) { 591 unsigned long bytes = nullsz; 592 593 if (bytes > zero_buf_sz) 594 bytes = zero_buf_sz; 595 ret = crypto_shash_update(desc, zero_buf, bytes); 596 if (ret) 597 break; 598 nullsz -= bytes; 599 } 600 601 if (ret) 602 break; 603 604 sha_regions[j].start = ksegment->mem; 605 sha_regions[j].len = ksegment->memsz; 606 j++; 607 } 608 609 if (!ret) { 610 ret = crypto_shash_final(desc, digest); 611 if (ret) 612 goto out_free_digest; 613 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions", 614 sha_regions, sha_region_sz, 0); 615 if (ret) 616 goto out_free_digest; 617 618 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest", 619 digest, SHA256_DIGEST_SIZE, 0); 620 if (ret) 621 goto out_free_digest; 622 } 623 624 out_free_digest: 625 kfree(digest); 626 out_free_sha_regions: 627 vfree(sha_regions); 628 out_free_desc: 629 kfree(desc); 630 out_free_tfm: 631 kfree(tfm); 632 out: 633 return ret; 634 } 635 636 /* Actually load purgatory. Lot of code taken from kexec-tools */ 637 static int __kexec_load_purgatory(struct kimage *image, unsigned long min, 638 unsigned long max, int top_down) 639 { 640 struct purgatory_info *pi = &image->purgatory_info; 641 unsigned long align, bss_align, bss_sz, bss_pad; 642 unsigned long entry, load_addr, curr_load_addr, bss_addr, offset; 643 unsigned char *buf_addr, *src; 644 int i, ret = 0, entry_sidx = -1; 645 const Elf_Shdr *sechdrs_c; 646 Elf_Shdr *sechdrs = NULL; 647 struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1, 648 .buf_min = min, .buf_max = max, 649 .top_down = top_down }; 650 651 /* 652 * sechdrs_c points to section headers in purgatory and are read 653 * only. No modifications allowed. 654 */ 655 sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff; 656 657 /* 658 * We can not modify sechdrs_c[] and its fields. It is read only. 659 * Copy it over to a local copy where one can store some temporary 660 * data and free it at the end. We need to modify ->sh_addr and 661 * ->sh_offset fields to keep track of permanent and temporary 662 * locations of sections. 663 */ 664 sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 665 if (!sechdrs) 666 return -ENOMEM; 667 668 memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr)); 669 670 /* 671 * We seem to have multiple copies of sections. First copy is which 672 * is embedded in kernel in read only section. Some of these sections 673 * will be copied to a temporary buffer and relocated. And these 674 * sections will finally be copied to their final destination at 675 * segment load time. 676 * 677 * Use ->sh_offset to reflect section address in memory. It will 678 * point to original read only copy if section is not allocatable. 679 * Otherwise it will point to temporary copy which will be relocated. 680 * 681 * Use ->sh_addr to contain final address of the section where it 682 * will go during execution time. 683 */ 684 for (i = 0; i < pi->ehdr->e_shnum; i++) { 685 if (sechdrs[i].sh_type == SHT_NOBITS) 686 continue; 687 688 sechdrs[i].sh_offset = (unsigned long)pi->ehdr + 689 sechdrs[i].sh_offset; 690 } 691 692 /* 693 * Identify entry point section and make entry relative to section 694 * start. 695 */ 696 entry = pi->ehdr->e_entry; 697 for (i = 0; i < pi->ehdr->e_shnum; i++) { 698 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 699 continue; 700 701 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR)) 702 continue; 703 704 /* Make entry section relative */ 705 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry && 706 ((sechdrs[i].sh_addr + sechdrs[i].sh_size) > 707 pi->ehdr->e_entry)) { 708 entry_sidx = i; 709 entry -= sechdrs[i].sh_addr; 710 break; 711 } 712 } 713 714 /* Determine how much memory is needed to load relocatable object. */ 715 bss_align = 1; 716 bss_sz = 0; 717 718 for (i = 0; i < pi->ehdr->e_shnum; i++) { 719 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 720 continue; 721 722 align = sechdrs[i].sh_addralign; 723 if (sechdrs[i].sh_type != SHT_NOBITS) { 724 if (kbuf.buf_align < align) 725 kbuf.buf_align = align; 726 kbuf.bufsz = ALIGN(kbuf.bufsz, align); 727 kbuf.bufsz += sechdrs[i].sh_size; 728 } else { 729 /* bss section */ 730 if (bss_align < align) 731 bss_align = align; 732 bss_sz = ALIGN(bss_sz, align); 733 bss_sz += sechdrs[i].sh_size; 734 } 735 } 736 737 /* Determine the bss padding required to align bss properly */ 738 bss_pad = 0; 739 if (kbuf.bufsz & (bss_align - 1)) 740 bss_pad = bss_align - (kbuf.bufsz & (bss_align - 1)); 741 742 kbuf.memsz = kbuf.bufsz + bss_pad + bss_sz; 743 744 /* Allocate buffer for purgatory */ 745 kbuf.buffer = vzalloc(kbuf.bufsz); 746 if (!kbuf.buffer) { 747 ret = -ENOMEM; 748 goto out; 749 } 750 751 if (kbuf.buf_align < bss_align) 752 kbuf.buf_align = bss_align; 753 754 /* Add buffer to segment list */ 755 ret = kexec_add_buffer(&kbuf); 756 if (ret) 757 goto out; 758 pi->purgatory_load_addr = kbuf.mem; 759 760 /* Load SHF_ALLOC sections */ 761 buf_addr = kbuf.buffer; 762 load_addr = curr_load_addr = pi->purgatory_load_addr; 763 bss_addr = load_addr + kbuf.bufsz + bss_pad; 764 765 for (i = 0; i < pi->ehdr->e_shnum; i++) { 766 if (!(sechdrs[i].sh_flags & SHF_ALLOC)) 767 continue; 768 769 align = sechdrs[i].sh_addralign; 770 if (sechdrs[i].sh_type != SHT_NOBITS) { 771 curr_load_addr = ALIGN(curr_load_addr, align); 772 offset = curr_load_addr - load_addr; 773 /* We already modifed ->sh_offset to keep src addr */ 774 src = (char *) sechdrs[i].sh_offset; 775 memcpy(buf_addr + offset, src, sechdrs[i].sh_size); 776 777 /* Store load address and source address of section */ 778 sechdrs[i].sh_addr = curr_load_addr; 779 780 /* 781 * This section got copied to temporary buffer. Update 782 * ->sh_offset accordingly. 783 */ 784 sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset); 785 786 /* Advance to the next address */ 787 curr_load_addr += sechdrs[i].sh_size; 788 } else { 789 bss_addr = ALIGN(bss_addr, align); 790 sechdrs[i].sh_addr = bss_addr; 791 bss_addr += sechdrs[i].sh_size; 792 } 793 } 794 795 /* Update entry point based on load address of text section */ 796 if (entry_sidx >= 0) 797 entry += sechdrs[entry_sidx].sh_addr; 798 799 /* Make kernel jump to purgatory after shutdown */ 800 image->start = entry; 801 802 /* Used later to get/set symbol values */ 803 pi->sechdrs = sechdrs; 804 805 /* 806 * Used later to identify which section is purgatory and skip it 807 * from checksumming. 808 */ 809 pi->purgatory_buf = kbuf.buffer; 810 return ret; 811 out: 812 vfree(sechdrs); 813 vfree(kbuf.buffer); 814 return ret; 815 } 816 817 static int kexec_apply_relocations(struct kimage *image) 818 { 819 int i, ret; 820 struct purgatory_info *pi = &image->purgatory_info; 821 Elf_Shdr *sechdrs = pi->sechdrs; 822 823 /* Apply relocations */ 824 for (i = 0; i < pi->ehdr->e_shnum; i++) { 825 Elf_Shdr *section, *symtab; 826 827 if (sechdrs[i].sh_type != SHT_RELA && 828 sechdrs[i].sh_type != SHT_REL) 829 continue; 830 831 /* 832 * For section of type SHT_RELA/SHT_REL, 833 * ->sh_link contains section header index of associated 834 * symbol table. And ->sh_info contains section header 835 * index of section to which relocations apply. 836 */ 837 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum || 838 sechdrs[i].sh_link >= pi->ehdr->e_shnum) 839 return -ENOEXEC; 840 841 section = &sechdrs[sechdrs[i].sh_info]; 842 symtab = &sechdrs[sechdrs[i].sh_link]; 843 844 if (!(section->sh_flags & SHF_ALLOC)) 845 continue; 846 847 /* 848 * symtab->sh_link contain section header index of associated 849 * string table. 850 */ 851 if (symtab->sh_link >= pi->ehdr->e_shnum) 852 /* Invalid section number? */ 853 continue; 854 855 /* 856 * Respective architecture needs to provide support for applying 857 * relocations of type SHT_RELA/SHT_REL. 858 */ 859 if (sechdrs[i].sh_type == SHT_RELA) 860 ret = arch_kexec_apply_relocations_add(pi->ehdr, 861 sechdrs, i); 862 else if (sechdrs[i].sh_type == SHT_REL) 863 ret = arch_kexec_apply_relocations(pi->ehdr, 864 sechdrs, i); 865 if (ret) 866 return ret; 867 } 868 869 return 0; 870 } 871 872 /* Load relocatable purgatory object and relocate it appropriately */ 873 int kexec_load_purgatory(struct kimage *image, unsigned long min, 874 unsigned long max, int top_down, 875 unsigned long *load_addr) 876 { 877 struct purgatory_info *pi = &image->purgatory_info; 878 int ret; 879 880 if (kexec_purgatory_size <= 0) 881 return -EINVAL; 882 883 if (kexec_purgatory_size < sizeof(Elf_Ehdr)) 884 return -ENOEXEC; 885 886 pi->ehdr = (Elf_Ehdr *)kexec_purgatory; 887 888 if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0 889 || pi->ehdr->e_type != ET_REL 890 || !elf_check_arch(pi->ehdr) 891 || pi->ehdr->e_shentsize != sizeof(Elf_Shdr)) 892 return -ENOEXEC; 893 894 if (pi->ehdr->e_shoff >= kexec_purgatory_size 895 || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) > 896 kexec_purgatory_size - pi->ehdr->e_shoff)) 897 return -ENOEXEC; 898 899 ret = __kexec_load_purgatory(image, min, max, top_down); 900 if (ret) 901 return ret; 902 903 ret = kexec_apply_relocations(image); 904 if (ret) 905 goto out; 906 907 *load_addr = pi->purgatory_load_addr; 908 return 0; 909 out: 910 vfree(pi->sechdrs); 911 pi->sechdrs = NULL; 912 913 vfree(pi->purgatory_buf); 914 pi->purgatory_buf = NULL; 915 return ret; 916 } 917 918 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, 919 const char *name) 920 { 921 Elf_Sym *syms; 922 Elf_Shdr *sechdrs; 923 Elf_Ehdr *ehdr; 924 int i, k; 925 const char *strtab; 926 927 if (!pi->sechdrs || !pi->ehdr) 928 return NULL; 929 930 sechdrs = pi->sechdrs; 931 ehdr = pi->ehdr; 932 933 for (i = 0; i < ehdr->e_shnum; i++) { 934 if (sechdrs[i].sh_type != SHT_SYMTAB) 935 continue; 936 937 if (sechdrs[i].sh_link >= ehdr->e_shnum) 938 /* Invalid strtab section number */ 939 continue; 940 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset; 941 syms = (Elf_Sym *)sechdrs[i].sh_offset; 942 943 /* Go through symbols for a match */ 944 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) { 945 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL) 946 continue; 947 948 if (strcmp(strtab + syms[k].st_name, name) != 0) 949 continue; 950 951 if (syms[k].st_shndx == SHN_UNDEF || 952 syms[k].st_shndx >= ehdr->e_shnum) { 953 pr_debug("Symbol: %s has bad section index %d.\n", 954 name, syms[k].st_shndx); 955 return NULL; 956 } 957 958 /* Found the symbol we are looking for */ 959 return &syms[k]; 960 } 961 } 962 963 return NULL; 964 } 965 966 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name) 967 { 968 struct purgatory_info *pi = &image->purgatory_info; 969 Elf_Sym *sym; 970 Elf_Shdr *sechdr; 971 972 sym = kexec_purgatory_find_symbol(pi, name); 973 if (!sym) 974 return ERR_PTR(-EINVAL); 975 976 sechdr = &pi->sechdrs[sym->st_shndx]; 977 978 /* 979 * Returns the address where symbol will finally be loaded after 980 * kexec_load_segment() 981 */ 982 return (void *)(sechdr->sh_addr + sym->st_value); 983 } 984 985 /* 986 * Get or set value of a symbol. If "get_value" is true, symbol value is 987 * returned in buf otherwise symbol value is set based on value in buf. 988 */ 989 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, 990 void *buf, unsigned int size, bool get_value) 991 { 992 Elf_Sym *sym; 993 Elf_Shdr *sechdrs; 994 struct purgatory_info *pi = &image->purgatory_info; 995 char *sym_buf; 996 997 sym = kexec_purgatory_find_symbol(pi, name); 998 if (!sym) 999 return -EINVAL; 1000 1001 if (sym->st_size != size) { 1002 pr_err("symbol %s size mismatch: expected %lu actual %u\n", 1003 name, (unsigned long)sym->st_size, size); 1004 return -EINVAL; 1005 } 1006 1007 sechdrs = pi->sechdrs; 1008 1009 if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) { 1010 pr_err("symbol %s is in a bss section. Cannot %s\n", name, 1011 get_value ? "get" : "set"); 1012 return -EINVAL; 1013 } 1014 1015 sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset + 1016 sym->st_value; 1017 1018 if (get_value) 1019 memcpy((void *)buf, sym_buf, size); 1020 else 1021 memcpy((void *)sym_buf, buf, size); 1022 1023 return 0; 1024 } 1025