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