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