1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kexec: kexec_file_load system call
4 *
5 * Copyright (C) 2014 Red Hat Inc.
6 * Authors:
7 * Vivek Goyal <vgoyal@redhat.com>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/capability.h>
13#include <linux/mm.h>
14#include <linux/file.h>
15#include <linux/slab.h>
16#include <linux/kexec.h>
17#include <linux/memblock.h>
18#include <linux/mutex.h>
19#include <linux/list.h>
20#include <linux/fs.h>
21#include <linux/ima.h>
22#include <crypto/hash.h>
23#include <crypto/sha2.h>
24#include <linux/elf.h>
25#include <linux/elfcore.h>
26#include <linux/kernel.h>
27#include <linux/kernel_read_file.h>
28#include <linux/syscalls.h>
29#include <linux/vmalloc.h>
30#include "kexec_internal.h"
31
32#ifdef CONFIG_KEXEC_SIG
33static bool sig_enforce = IS_ENABLED(CONFIG_KEXEC_SIG_FORCE);
34
35void set_kexec_sig_enforced(void)
36{
37 sig_enforce = true;
38}
39#endif
40
41static int kexec_calculate_store_digests(struct kimage *image);
42
43/* Maximum size in bytes for kernel/initrd files. */
44#define KEXEC_FILE_SIZE_MAX min_t(s64, 4LL << 30, SSIZE_MAX)
45
46/*
47 * Currently this is the only default function that is exported as some
48 * architectures need it to do additional handlings.
49 * In the future, other default functions may be exported too if required.
50 */
51int kexec_image_probe_default(struct kimage *image, void *buf,
52 unsigned long buf_len)
53{
54 const struct kexec_file_ops * const *fops;
55 int ret = -ENOEXEC;
56
57 for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
58 ret = (*fops)->probe(buf, buf_len);
59 if (!ret) {
60 image->fops = *fops;
61 return ret;
62 }
63 }
64
65 return ret;
66}
67
68static void *kexec_image_load_default(struct kimage *image)
69{
70 if (!image->fops || !image->fops->load)
71 return ERR_PTR(error: -ENOEXEC);
72
73 return image->fops->load(image, image->kernel_buf,
74 image->kernel_buf_len, image->initrd_buf,
75 image->initrd_buf_len, image->cmdline_buf,
76 image->cmdline_buf_len);
77}
78
79int kexec_image_post_load_cleanup_default(struct kimage *image)
80{
81 if (!image->fops || !image->fops->cleanup)
82 return 0;
83
84 return image->fops->cleanup(image->image_loader_data);
85}
86
87/*
88 * Free up memory used by kernel, initrd, and command line. This is temporary
89 * memory allocation which is not needed any more after these buffers have
90 * been loaded into separate segments and have been copied elsewhere.
91 */
92void kimage_file_post_load_cleanup(struct kimage *image)
93{
94 struct purgatory_info *pi = &image->purgatory_info;
95
96 vfree(addr: image->kernel_buf);
97 image->kernel_buf = NULL;
98
99 vfree(addr: image->initrd_buf);
100 image->initrd_buf = NULL;
101
102 kfree(objp: image->cmdline_buf);
103 image->cmdline_buf = NULL;
104
105 vfree(addr: pi->purgatory_buf);
106 pi->purgatory_buf = NULL;
107
108 vfree(addr: pi->sechdrs);
109 pi->sechdrs = NULL;
110
111#ifdef CONFIG_IMA_KEXEC
112 vfree(addr: image->ima_buffer);
113 image->ima_buffer = NULL;
114#endif /* CONFIG_IMA_KEXEC */
115
116 /* See if architecture has anything to cleanup post load */
117 arch_kimage_file_post_load_cleanup(image);
118
119 /*
120 * Above call should have called into bootloader to free up
121 * any data stored in kimage->image_loader_data. It should
122 * be ok now to free it up.
123 */
124 kfree(objp: image->image_loader_data);
125 image->image_loader_data = NULL;
126}
127
128#ifdef CONFIG_KEXEC_SIG
129#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
130int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
131{
132 int ret;
133
134 ret = verify_pefile_signature(pebuf: kernel, pelen: kernel_len,
135 VERIFY_USE_SECONDARY_KEYRING,
136 usage: VERIFYING_KEXEC_PE_SIGNATURE);
137 if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
138 ret = verify_pefile_signature(pebuf: kernel, pelen: kernel_len,
139 VERIFY_USE_PLATFORM_KEYRING,
140 usage: VERIFYING_KEXEC_PE_SIGNATURE);
141 }
142 return ret;
143}
144#endif
145
146static int kexec_image_verify_sig(struct kimage *image, void *buf,
147 unsigned long buf_len)
148{
149 if (!image->fops || !image->fops->verify_sig) {
150 pr_debug("kernel loader does not support signature verification.\n");
151 return -EKEYREJECTED;
152 }
153
154 return image->fops->verify_sig(buf, buf_len);
155}
156
157static int
158kimage_validate_signature(struct kimage *image)
159{
160 int ret;
161
162 ret = kexec_image_verify_sig(image, buf: image->kernel_buf,
163 buf_len: image->kernel_buf_len);
164 if (ret) {
165
166 if (sig_enforce) {
167 pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
168 return ret;
169 }
170
171 /*
172 * If IMA is guaranteed to appraise a signature on the kexec
173 * image, permit it even if the kernel is otherwise locked
174 * down.
175 */
176 if (!ima_appraise_signature(func: READING_KEXEC_IMAGE) &&
177 security_locked_down(what: LOCKDOWN_KEXEC))
178 return -EPERM;
179
180 pr_debug("kernel signature verification failed (%d).\n", ret);
181 }
182
183 return 0;
184}
185#endif
186
187/*
188 * In file mode list of segments is prepared by kernel. Copy relevant
189 * data from user space, do error checking, prepare segment list
190 */
191static int
192kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
193 const char __user *cmdline_ptr,
194 unsigned long cmdline_len, unsigned flags)
195{
196 ssize_t ret;
197 void *ldata;
198
199 ret = kernel_read_file_from_fd(fd: kernel_fd, offset: 0, buf: &image->kernel_buf,
200 KEXEC_FILE_SIZE_MAX, NULL,
201 id: READING_KEXEC_IMAGE);
202 if (ret < 0)
203 return ret;
204 image->kernel_buf_len = ret;
205
206 /* Call arch image probe handlers */
207 ret = arch_kexec_kernel_image_probe(image, buf: image->kernel_buf,
208 buf_len: image->kernel_buf_len);
209 if (ret)
210 goto out;
211
212#ifdef CONFIG_KEXEC_SIG
213 ret = kimage_validate_signature(image);
214
215 if (ret)
216 goto out;
217#endif
218 /* It is possible that there no initramfs is being loaded */
219 if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
220 ret = kernel_read_file_from_fd(fd: initrd_fd, offset: 0, buf: &image->initrd_buf,
221 KEXEC_FILE_SIZE_MAX, NULL,
222 id: READING_KEXEC_INITRAMFS);
223 if (ret < 0)
224 goto out;
225 image->initrd_buf_len = ret;
226 ret = 0;
227 }
228
229 if (cmdline_len) {
230 image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
231 if (IS_ERR(ptr: image->cmdline_buf)) {
232 ret = PTR_ERR(ptr: image->cmdline_buf);
233 image->cmdline_buf = NULL;
234 goto out;
235 }
236
237 image->cmdline_buf_len = cmdline_len;
238
239 /* command line should be a string with last byte null */
240 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
241 ret = -EINVAL;
242 goto out;
243 }
244
245 ima_kexec_cmdline(kernel_fd, buf: image->cmdline_buf,
246 size: image->cmdline_buf_len - 1);
247 }
248
249 /* IMA needs to pass the measurement list to the next kernel. */
250 ima_add_kexec_buffer(image);
251
252 /* Call image load handler */
253 ldata = kexec_image_load_default(image);
254
255 if (IS_ERR(ptr: ldata)) {
256 ret = PTR_ERR(ptr: ldata);
257 goto out;
258 }
259
260 image->image_loader_data = ldata;
261out:
262 /* In case of error, free up all allocated memory in this function */
263 if (ret)
264 kimage_file_post_load_cleanup(image);
265 return ret;
266}
267
268static int
269kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
270 int initrd_fd, const char __user *cmdline_ptr,
271 unsigned long cmdline_len, unsigned long flags)
272{
273 int ret;
274 struct kimage *image;
275 bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
276
277 image = do_kimage_alloc_init();
278 if (!image)
279 return -ENOMEM;
280
281 image->file_mode = 1;
282
283 if (kexec_on_panic) {
284 /* Enable special crash kernel control page alloc policy. */
285 image->control_page = crashk_res.start;
286 image->type = KEXEC_TYPE_CRASH;
287 }
288
289 ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
290 cmdline_ptr, cmdline_len, flags);
291 if (ret)
292 goto out_free_image;
293
294 ret = sanity_check_segment_list(image);
295 if (ret)
296 goto out_free_post_load_bufs;
297
298 ret = -ENOMEM;
299 image->control_code_page = kimage_alloc_control_pages(image,
300 order: get_order(KEXEC_CONTROL_PAGE_SIZE));
301 if (!image->control_code_page) {
302 pr_err("Could not allocate control_code_buffer\n");
303 goto out_free_post_load_bufs;
304 }
305
306 if (!kexec_on_panic) {
307 image->swap_page = kimage_alloc_control_pages(image, order: 0);
308 if (!image->swap_page) {
309 pr_err("Could not allocate swap buffer\n");
310 goto out_free_control_pages;
311 }
312 }
313
314 *rimage = image;
315 return 0;
316out_free_control_pages:
317 kimage_free_page_list(list: &image->control_pages);
318out_free_post_load_bufs:
319 kimage_file_post_load_cleanup(image);
320out_free_image:
321 kfree(objp: image);
322 return ret;
323}
324
325SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
326 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
327 unsigned long, flags)
328{
329 int image_type = (flags & KEXEC_FILE_ON_CRASH) ?
330 KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
331 struct kimage **dest_image, *image;
332 int ret = 0, i;
333
334 /* We only trust the superuser with rebooting the system. */
335 if (!kexec_load_permitted(kexec_image_type: image_type))
336 return -EPERM;
337
338 /* Make sure we have a legal set of flags */
339 if (flags != (flags & KEXEC_FILE_FLAGS))
340 return -EINVAL;
341
342 image = NULL;
343
344 if (!kexec_trylock())
345 return -EBUSY;
346
347 if (image_type == KEXEC_TYPE_CRASH) {
348 dest_image = &kexec_crash_image;
349 if (kexec_crash_image)
350 arch_kexec_unprotect_crashkres();
351 } else {
352 dest_image = &kexec_image;
353 }
354
355 if (flags & KEXEC_FILE_UNLOAD)
356 goto exchange;
357
358 /*
359 * In case of crash, new kernel gets loaded in reserved region. It is
360 * same memory where old crash kernel might be loaded. Free any
361 * current crash dump kernel before we corrupt it.
362 */
363 if (flags & KEXEC_FILE_ON_CRASH)
364 kimage_free(xchg(&kexec_crash_image, NULL));
365
366 ret = kimage_file_alloc_init(rimage: &image, kernel_fd, initrd_fd, cmdline_ptr,
367 cmdline_len, flags);
368 if (ret)
369 goto out;
370
371 ret = machine_kexec_prepare(image);
372 if (ret)
373 goto out;
374
375 /*
376 * Some architecture(like S390) may touch the crash memory before
377 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
378 */
379 ret = kimage_crash_copy_vmcoreinfo(image);
380 if (ret)
381 goto out;
382
383 ret = kexec_calculate_store_digests(image);
384 if (ret)
385 goto out;
386
387 for (i = 0; i < image->nr_segments; i++) {
388 struct kexec_segment *ksegment;
389
390 ksegment = &image->segment[i];
391 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
392 i, ksegment->buf, ksegment->bufsz, ksegment->mem,
393 ksegment->memsz);
394
395 ret = kimage_load_segment(image, segment: &image->segment[i]);
396 if (ret)
397 goto out;
398 }
399
400 kimage_terminate(image);
401
402 ret = machine_kexec_post_load(image);
403 if (ret)
404 goto out;
405
406 /*
407 * Free up any temporary buffers allocated which are not needed
408 * after image has been loaded
409 */
410 kimage_file_post_load_cleanup(image);
411exchange:
412 image = xchg(dest_image, image);
413out:
414 if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
415 arch_kexec_protect_crashkres();
416
417 kexec_unlock();
418 kimage_free(image);
419 return ret;
420}
421
422static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
423 struct kexec_buf *kbuf)
424{
425 struct kimage *image = kbuf->image;
426 unsigned long temp_start, temp_end;
427
428 temp_end = min(end, kbuf->buf_max);
429 temp_start = temp_end - kbuf->memsz;
430
431 do {
432 /* align down start */
433 temp_start = temp_start & (~(kbuf->buf_align - 1));
434
435 if (temp_start < start || temp_start < kbuf->buf_min)
436 return 0;
437
438 temp_end = temp_start + kbuf->memsz - 1;
439
440 /*
441 * Make sure this does not conflict with any of existing
442 * segments
443 */
444 if (kimage_is_destination_range(image, start: temp_start, end: temp_end)) {
445 temp_start = temp_start - PAGE_SIZE;
446 continue;
447 }
448
449 /* We found a suitable memory range */
450 break;
451 } while (1);
452
453 /* If we are here, we found a suitable memory range */
454 kbuf->mem = temp_start;
455
456 /* Success, stop navigating through remaining System RAM ranges */
457 return 1;
458}
459
460static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
461 struct kexec_buf *kbuf)
462{
463 struct kimage *image = kbuf->image;
464 unsigned long temp_start, temp_end;
465
466 temp_start = max(start, kbuf->buf_min);
467
468 do {
469 temp_start = ALIGN(temp_start, kbuf->buf_align);
470 temp_end = temp_start + kbuf->memsz - 1;
471
472 if (temp_end > end || temp_end > kbuf->buf_max)
473 return 0;
474 /*
475 * Make sure this does not conflict with any of existing
476 * segments
477 */
478 if (kimage_is_destination_range(image, start: temp_start, end: temp_end)) {
479 temp_start = temp_start + PAGE_SIZE;
480 continue;
481 }
482
483 /* We found a suitable memory range */
484 break;
485 } while (1);
486
487 /* If we are here, we found a suitable memory range */
488 kbuf->mem = temp_start;
489
490 /* Success, stop navigating through remaining System RAM ranges */
491 return 1;
492}
493
494static int locate_mem_hole_callback(struct resource *res, void *arg)
495{
496 struct kexec_buf *kbuf = (struct kexec_buf *)arg;
497 u64 start = res->start, end = res->end;
498 unsigned long sz = end - start + 1;
499
500 /* Returning 0 will take to next memory range */
501
502 /* Don't use memory that will be detected and handled by a driver. */
503 if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
504 return 0;
505
506 if (sz < kbuf->memsz)
507 return 0;
508
509 if (end < kbuf->buf_min || start > kbuf->buf_max)
510 return 0;
511
512 /*
513 * Allocate memory top down with-in ram range. Otherwise bottom up
514 * allocation.
515 */
516 if (kbuf->top_down)
517 return locate_mem_hole_top_down(start, end, kbuf);
518 return locate_mem_hole_bottom_up(start, end, kbuf);
519}
520
521#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
522static int kexec_walk_memblock(struct kexec_buf *kbuf,
523 int (*func)(struct resource *, void *))
524{
525 int ret = 0;
526 u64 i;
527 phys_addr_t mstart, mend;
528 struct resource res = { };
529
530 if (kbuf->image->type == KEXEC_TYPE_CRASH)
531 return func(&crashk_res, kbuf);
532
533 /*
534 * Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See
535 * IORESOURCE_SYSRAM_DRIVER_MANAGED handling in
536 * locate_mem_hole_callback().
537 */
538 if (kbuf->top_down) {
539 for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,
540 &mstart, &mend, NULL) {
541 /*
542 * In memblock, end points to the first byte after the
543 * range while in kexec, end points to the last byte
544 * in the range.
545 */
546 res.start = mstart;
547 res.end = mend - 1;
548 ret = func(&res, kbuf);
549 if (ret)
550 break;
551 }
552 } else {
553 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
554 &mstart, &mend, NULL) {
555 /*
556 * In memblock, end points to the first byte after the
557 * range while in kexec, end points to the last byte
558 * in the range.
559 */
560 res.start = mstart;
561 res.end = mend - 1;
562 ret = func(&res, kbuf);
563 if (ret)
564 break;
565 }
566 }
567
568 return ret;
569}
570#else
571static int kexec_walk_memblock(struct kexec_buf *kbuf,
572 int (*func)(struct resource *, void *))
573{
574 return 0;
575}
576#endif
577
578/**
579 * kexec_walk_resources - call func(data) on free memory regions
580 * @kbuf: Context info for the search. Also passed to @func.
581 * @func: Function to call for each memory region.
582 *
583 * Return: The memory walk will stop when func returns a non-zero value
584 * and that value will be returned. If all free regions are visited without
585 * func returning non-zero, then zero will be returned.
586 */
587static int kexec_walk_resources(struct kexec_buf *kbuf,
588 int (*func)(struct resource *, void *))
589{
590 if (kbuf->image->type == KEXEC_TYPE_CRASH)
591 return walk_iomem_res_desc(desc: crashk_res.desc,
592 IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
593 start: crashk_res.start, end: crashk_res.end,
594 arg: kbuf, func);
595 else
596 return walk_system_ram_res(start: 0, ULONG_MAX, arg: kbuf, func);
597}
598
599/**
600 * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
601 * @kbuf: Parameters for the memory search.
602 *
603 * On success, kbuf->mem will have the start address of the memory region found.
604 *
605 * Return: 0 on success, negative errno on error.
606 */
607int kexec_locate_mem_hole(struct kexec_buf *kbuf)
608{
609 int ret;
610
611 /* Arch knows where to place */
612 if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
613 return 0;
614
615 if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
616 ret = kexec_walk_resources(kbuf, func: locate_mem_hole_callback);
617 else
618 ret = kexec_walk_memblock(kbuf, func: locate_mem_hole_callback);
619
620 return ret == 1 ? 0 : -EADDRNOTAVAIL;
621}
622
623/**
624 * kexec_add_buffer - place a buffer in a kexec segment
625 * @kbuf: Buffer contents and memory parameters.
626 *
627 * This function assumes that kexec_lock is held.
628 * On successful return, @kbuf->mem will have the physical address of
629 * the buffer in memory.
630 *
631 * Return: 0 on success, negative errno on error.
632 */
633int kexec_add_buffer(struct kexec_buf *kbuf)
634{
635 struct kexec_segment *ksegment;
636 int ret;
637
638 /* Currently adding segment this way is allowed only in file mode */
639 if (!kbuf->image->file_mode)
640 return -EINVAL;
641
642 if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
643 return -EINVAL;
644
645 /*
646 * Make sure we are not trying to add buffer after allocating
647 * control pages. All segments need to be placed first before
648 * any control pages are allocated. As control page allocation
649 * logic goes through list of segments to make sure there are
650 * no destination overlaps.
651 */
652 if (!list_empty(head: &kbuf->image->control_pages)) {
653 WARN_ON(1);
654 return -EINVAL;
655 }
656
657 /* Ensure minimum alignment needed for segments. */
658 kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
659 kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
660
661 /* Walk the RAM ranges and allocate a suitable range for the buffer */
662 ret = arch_kexec_locate_mem_hole(kbuf);
663 if (ret)
664 return ret;
665
666 /* Found a suitable memory range */
667 ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
668 ksegment->kbuf = kbuf->buffer;
669 ksegment->bufsz = kbuf->bufsz;
670 ksegment->mem = kbuf->mem;
671 ksegment->memsz = kbuf->memsz;
672 kbuf->image->nr_segments++;
673 return 0;
674}
675
676/* Calculate and store the digest of segments */
677static int kexec_calculate_store_digests(struct kimage *image)
678{
679 struct crypto_shash *tfm;
680 struct shash_desc *desc;
681 int ret = 0, i, j, zero_buf_sz, sha_region_sz;
682 size_t desc_size, nullsz;
683 char *digest;
684 void *zero_buf;
685 struct kexec_sha_region *sha_regions;
686 struct purgatory_info *pi = &image->purgatory_info;
687
688 if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY))
689 return 0;
690
691 zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
692 zero_buf_sz = PAGE_SIZE;
693
694 tfm = crypto_alloc_shash(alg_name: "sha256", type: 0, mask: 0);
695 if (IS_ERR(ptr: tfm)) {
696 ret = PTR_ERR(ptr: tfm);
697 goto out;
698 }
699
700 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
701 desc = kzalloc(size: desc_size, GFP_KERNEL);
702 if (!desc) {
703 ret = -ENOMEM;
704 goto out_free_tfm;
705 }
706
707 sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
708 sha_regions = vzalloc(size: sha_region_sz);
709 if (!sha_regions) {
710 ret = -ENOMEM;
711 goto out_free_desc;
712 }
713
714 desc->tfm = tfm;
715
716 ret = crypto_shash_init(desc);
717 if (ret < 0)
718 goto out_free_sha_regions;
719
720 digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
721 if (!digest) {
722 ret = -ENOMEM;
723 goto out_free_sha_regions;
724 }
725
726 for (j = i = 0; i < image->nr_segments; i++) {
727 struct kexec_segment *ksegment;
728
729#ifdef CONFIG_CRASH_HOTPLUG
730 /* Exclude elfcorehdr segment to allow future changes via hotplug */
731 if (j == image->elfcorehdr_index)
732 continue;
733#endif
734
735 ksegment = &image->segment[i];
736 /*
737 * Skip purgatory as it will be modified once we put digest
738 * info in purgatory.
739 */
740 if (ksegment->kbuf == pi->purgatory_buf)
741 continue;
742
743 ret = crypto_shash_update(desc, data: ksegment->kbuf,
744 len: ksegment->bufsz);
745 if (ret)
746 break;
747
748 /*
749 * Assume rest of the buffer is filled with zero and
750 * update digest accordingly.
751 */
752 nullsz = ksegment->memsz - ksegment->bufsz;
753 while (nullsz) {
754 unsigned long bytes = nullsz;
755
756 if (bytes > zero_buf_sz)
757 bytes = zero_buf_sz;
758 ret = crypto_shash_update(desc, data: zero_buf, len: bytes);
759 if (ret)
760 break;
761 nullsz -= bytes;
762 }
763
764 if (ret)
765 break;
766
767 sha_regions[j].start = ksegment->mem;
768 sha_regions[j].len = ksegment->memsz;
769 j++;
770 }
771
772 if (!ret) {
773 ret = crypto_shash_final(desc, out: digest);
774 if (ret)
775 goto out_free_digest;
776 ret = kexec_purgatory_get_set_symbol(image, name: "purgatory_sha_regions",
777 buf: sha_regions, size: sha_region_sz, get_value: 0);
778 if (ret)
779 goto out_free_digest;
780
781 ret = kexec_purgatory_get_set_symbol(image, name: "purgatory_sha256_digest",
782 buf: digest, SHA256_DIGEST_SIZE, get_value: 0);
783 if (ret)
784 goto out_free_digest;
785 }
786
787out_free_digest:
788 kfree(objp: digest);
789out_free_sha_regions:
790 vfree(addr: sha_regions);
791out_free_desc:
792 kfree(objp: desc);
793out_free_tfm:
794 kfree(objp: tfm);
795out:
796 return ret;
797}
798
799#ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
800/*
801 * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
802 * @pi: Purgatory to be loaded.
803 * @kbuf: Buffer to setup.
804 *
805 * Allocates the memory needed for the buffer. Caller is responsible to free
806 * the memory after use.
807 *
808 * Return: 0 on success, negative errno on error.
809 */
810static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
811 struct kexec_buf *kbuf)
812{
813 const Elf_Shdr *sechdrs;
814 unsigned long bss_align;
815 unsigned long bss_sz;
816 unsigned long align;
817 int i, ret;
818
819 sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
820 kbuf->buf_align = bss_align = 1;
821 kbuf->bufsz = bss_sz = 0;
822
823 for (i = 0; i < pi->ehdr->e_shnum; i++) {
824 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
825 continue;
826
827 align = sechdrs[i].sh_addralign;
828 if (sechdrs[i].sh_type != SHT_NOBITS) {
829 if (kbuf->buf_align < align)
830 kbuf->buf_align = align;
831 kbuf->bufsz = ALIGN(kbuf->bufsz, align);
832 kbuf->bufsz += sechdrs[i].sh_size;
833 } else {
834 if (bss_align < align)
835 bss_align = align;
836 bss_sz = ALIGN(bss_sz, align);
837 bss_sz += sechdrs[i].sh_size;
838 }
839 }
840 kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
841 kbuf->memsz = kbuf->bufsz + bss_sz;
842 if (kbuf->buf_align < bss_align)
843 kbuf->buf_align = bss_align;
844
845 kbuf->buffer = vzalloc(size: kbuf->bufsz);
846 if (!kbuf->buffer)
847 return -ENOMEM;
848 pi->purgatory_buf = kbuf->buffer;
849
850 ret = kexec_add_buffer(kbuf);
851 if (ret)
852 goto out;
853
854 return 0;
855out:
856 vfree(addr: pi->purgatory_buf);
857 pi->purgatory_buf = NULL;
858 return ret;
859}
860
861/*
862 * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
863 * @pi: Purgatory to be loaded.
864 * @kbuf: Buffer prepared to store purgatory.
865 *
866 * Allocates the memory needed for the buffer. Caller is responsible to free
867 * the memory after use.
868 *
869 * Return: 0 on success, negative errno on error.
870 */
871static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
872 struct kexec_buf *kbuf)
873{
874 unsigned long bss_addr;
875 unsigned long offset;
876 size_t sechdrs_size;
877 Elf_Shdr *sechdrs;
878 int i;
879
880 /*
881 * The section headers in kexec_purgatory are read-only. In order to
882 * have them modifiable make a temporary copy.
883 */
884 sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
885 sechdrs = vzalloc(size: sechdrs_size);
886 if (!sechdrs)
887 return -ENOMEM;
888 memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
889 pi->sechdrs = sechdrs;
890
891 offset = 0;
892 bss_addr = kbuf->mem + kbuf->bufsz;
893 kbuf->image->start = pi->ehdr->e_entry;
894
895 for (i = 0; i < pi->ehdr->e_shnum; i++) {
896 unsigned long align;
897 void *src, *dst;
898
899 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
900 continue;
901
902 align = sechdrs[i].sh_addralign;
903 if (sechdrs[i].sh_type == SHT_NOBITS) {
904 bss_addr = ALIGN(bss_addr, align);
905 sechdrs[i].sh_addr = bss_addr;
906 bss_addr += sechdrs[i].sh_size;
907 continue;
908 }
909
910 offset = ALIGN(offset, align);
911
912 /*
913 * Check if the segment contains the entry point, if so,
914 * calculate the value of image->start based on it.
915 * If the compiler has produced more than one .text section
916 * (Eg: .text.hot), they are generally after the main .text
917 * section, and they shall not be used to calculate
918 * image->start. So do not re-calculate image->start if it
919 * is not set to the initial value, and warn the user so they
920 * have a chance to fix their purgatory's linker script.
921 */
922 if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
923 pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
924 pi->ehdr->e_entry < (sechdrs[i].sh_addr
925 + sechdrs[i].sh_size) &&
926 !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) {
927 kbuf->image->start -= sechdrs[i].sh_addr;
928 kbuf->image->start += kbuf->mem + offset;
929 }
930
931 src = (void *)pi->ehdr + sechdrs[i].sh_offset;
932 dst = pi->purgatory_buf + offset;
933 memcpy(dst, src, sechdrs[i].sh_size);
934
935 sechdrs[i].sh_addr = kbuf->mem + offset;
936 sechdrs[i].sh_offset = offset;
937 offset += sechdrs[i].sh_size;
938 }
939
940 return 0;
941}
942
943static int kexec_apply_relocations(struct kimage *image)
944{
945 int i, ret;
946 struct purgatory_info *pi = &image->purgatory_info;
947 const Elf_Shdr *sechdrs;
948
949 sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
950
951 for (i = 0; i < pi->ehdr->e_shnum; i++) {
952 const Elf_Shdr *relsec;
953 const Elf_Shdr *symtab;
954 Elf_Shdr *section;
955
956 relsec = sechdrs + i;
957
958 if (relsec->sh_type != SHT_RELA &&
959 relsec->sh_type != SHT_REL)
960 continue;
961
962 /*
963 * For section of type SHT_RELA/SHT_REL,
964 * ->sh_link contains section header index of associated
965 * symbol table. And ->sh_info contains section header
966 * index of section to which relocations apply.
967 */
968 if (relsec->sh_info >= pi->ehdr->e_shnum ||
969 relsec->sh_link >= pi->ehdr->e_shnum)
970 return -ENOEXEC;
971
972 section = pi->sechdrs + relsec->sh_info;
973 symtab = sechdrs + relsec->sh_link;
974
975 if (!(section->sh_flags & SHF_ALLOC))
976 continue;
977
978 /*
979 * symtab->sh_link contain section header index of associated
980 * string table.
981 */
982 if (symtab->sh_link >= pi->ehdr->e_shnum)
983 /* Invalid section number? */
984 continue;
985
986 /*
987 * Respective architecture needs to provide support for applying
988 * relocations of type SHT_RELA/SHT_REL.
989 */
990 if (relsec->sh_type == SHT_RELA)
991 ret = arch_kexec_apply_relocations_add(pi, section,
992 relsec, symtab);
993 else if (relsec->sh_type == SHT_REL)
994 ret = arch_kexec_apply_relocations(pi, section,
995 relsec, symtab);
996 if (ret)
997 return ret;
998 }
999
1000 return 0;
1001}
1002
1003/*
1004 * kexec_load_purgatory - Load and relocate the purgatory object.
1005 * @image: Image to add the purgatory to.
1006 * @kbuf: Memory parameters to use.
1007 *
1008 * Allocates the memory needed for image->purgatory_info.sechdrs and
1009 * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
1010 * to free the memory after use.
1011 *
1012 * Return: 0 on success, negative errno on error.
1013 */
1014int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
1015{
1016 struct purgatory_info *pi = &image->purgatory_info;
1017 int ret;
1018
1019 if (kexec_purgatory_size <= 0)
1020 return -EINVAL;
1021
1022 pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
1023
1024 ret = kexec_purgatory_setup_kbuf(pi, kbuf);
1025 if (ret)
1026 return ret;
1027
1028 ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
1029 if (ret)
1030 goto out_free_kbuf;
1031
1032 ret = kexec_apply_relocations(image);
1033 if (ret)
1034 goto out;
1035
1036 return 0;
1037out:
1038 vfree(addr: pi->sechdrs);
1039 pi->sechdrs = NULL;
1040out_free_kbuf:
1041 vfree(addr: pi->purgatory_buf);
1042 pi->purgatory_buf = NULL;
1043 return ret;
1044}
1045
1046/*
1047 * kexec_purgatory_find_symbol - find a symbol in the purgatory
1048 * @pi: Purgatory to search in.
1049 * @name: Name of the symbol.
1050 *
1051 * Return: pointer to symbol in read-only symtab on success, NULL on error.
1052 */
1053static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
1054 const char *name)
1055{
1056 const Elf_Shdr *sechdrs;
1057 const Elf_Ehdr *ehdr;
1058 const Elf_Sym *syms;
1059 const char *strtab;
1060 int i, k;
1061
1062 if (!pi->ehdr)
1063 return NULL;
1064
1065 ehdr = pi->ehdr;
1066 sechdrs = (void *)ehdr + ehdr->e_shoff;
1067
1068 for (i = 0; i < ehdr->e_shnum; i++) {
1069 if (sechdrs[i].sh_type != SHT_SYMTAB)
1070 continue;
1071
1072 if (sechdrs[i].sh_link >= ehdr->e_shnum)
1073 /* Invalid strtab section number */
1074 continue;
1075 strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
1076 syms = (void *)ehdr + sechdrs[i].sh_offset;
1077
1078 /* Go through symbols for a match */
1079 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
1080 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
1081 continue;
1082
1083 if (strcmp(strtab + syms[k].st_name, name) != 0)
1084 continue;
1085
1086 if (syms[k].st_shndx == SHN_UNDEF ||
1087 syms[k].st_shndx >= ehdr->e_shnum) {
1088 pr_debug("Symbol: %s has bad section index %d.\n",
1089 name, syms[k].st_shndx);
1090 return NULL;
1091 }
1092
1093 /* Found the symbol we are looking for */
1094 return &syms[k];
1095 }
1096 }
1097
1098 return NULL;
1099}
1100
1101void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
1102{
1103 struct purgatory_info *pi = &image->purgatory_info;
1104 const Elf_Sym *sym;
1105 Elf_Shdr *sechdr;
1106
1107 sym = kexec_purgatory_find_symbol(pi, name);
1108 if (!sym)
1109 return ERR_PTR(error: -EINVAL);
1110
1111 sechdr = &pi->sechdrs[sym->st_shndx];
1112
1113 /*
1114 * Returns the address where symbol will finally be loaded after
1115 * kexec_load_segment()
1116 */
1117 return (void *)(sechdr->sh_addr + sym->st_value);
1118}
1119
1120/*
1121 * Get or set value of a symbol. If "get_value" is true, symbol value is
1122 * returned in buf otherwise symbol value is set based on value in buf.
1123 */
1124int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
1125 void *buf, unsigned int size, bool get_value)
1126{
1127 struct purgatory_info *pi = &image->purgatory_info;
1128 const Elf_Sym *sym;
1129 Elf_Shdr *sec;
1130 char *sym_buf;
1131
1132 sym = kexec_purgatory_find_symbol(pi, name);
1133 if (!sym)
1134 return -EINVAL;
1135
1136 if (sym->st_size != size) {
1137 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1138 name, (unsigned long)sym->st_size, size);
1139 return -EINVAL;
1140 }
1141
1142 sec = pi->sechdrs + sym->st_shndx;
1143
1144 if (sec->sh_type == SHT_NOBITS) {
1145 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1146 get_value ? "get" : "set");
1147 return -EINVAL;
1148 }
1149
1150 sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
1151
1152 if (get_value)
1153 memcpy((void *)buf, sym_buf, size);
1154 else
1155 memcpy((void *)sym_buf, buf, size);
1156
1157 return 0;
1158}
1159#endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */
1160

source code of linux/kernel/kexec_file.c