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path: root/kernel/kexec_file.c (plain)
blob: 037c321c56188f9fbb35193072f08052d6e4771f
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 */
32char __weak kexec_purgatory[0];
33size_t __weak kexec_purgatory_size = 0;
34
35static int kexec_calculate_store_digests(struct kimage *image);
36
37/* Architectures can provide this probe function */
38int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
39 unsigned long buf_len)
40{
41 return -ENOEXEC;
42}
43
44void * __weak arch_kexec_kernel_image_load(struct kimage *image)
45{
46 return ERR_PTR(-ENOEXEC);
47}
48
49int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
50{
51 return -EINVAL;
52}
53
54#ifdef CONFIG_KEXEC_VERIFY_SIG
55int __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 */
63int __weak
64arch_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 */
72int __weak
73arch_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 */
85void 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 */
120static int
121kimage_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;
192out:
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
199static int
200kimage_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;
247out_free_control_pages:
248 kimage_free_page_list(&image->control_pages);
249out_free_post_load_bufs:
250 kimage_file_post_load_cleanup(image);
251out_free_image:
252 kfree(image);
253 return ret;
254}
255
256SYSCALL_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);
327exchange:
328 image = xchg(dest_image, image);
329out:
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
338static 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
376static 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
410static 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 */
435int 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 */
502static 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
602out_free_digest:
603 kfree(digest);
604out_free_sha_regions:
605 vfree(sha_regions);
606out_free_desc:
607 kfree(desc);
608out_free_tfm:
609 kfree(tfm);
610out:
611 return ret;
612}
613
614/* Actually load purgatory. Lot of code taken from kexec-tools */
615static 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;
790out:
791 vfree(sechdrs);
792 vfree(purgatory_buf);
793 return ret;
794}
795
796static 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 */
852int 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;
888out:
889 vfree(pi->sechdrs);
890 pi->sechdrs = NULL;
891
892 vfree(pi->purgatory_buf);
893 pi->purgatory_buf = NULL;
894 return ret;
895}
896
897static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
898 const char *name)
899{
900 Elf_Sym *syms;
901 Elf_Shdr *sechdrs;
902 Elf_Ehdr *ehdr;
903 int i, k;
904 const char *strtab;
905
906 if (!pi->sechdrs || !pi->ehdr)
907 return NULL;
908
909 sechdrs = pi->sechdrs;
910 ehdr = pi->ehdr;
911
912 for (i = 0; i < ehdr->e_shnum; i++) {
913 if (sechdrs[i].sh_type != SHT_SYMTAB)
914 continue;
915
916 if (sechdrs[i].sh_link >= ehdr->e_shnum)
917 /* Invalid strtab section number */
918 continue;
919 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
920 syms = (Elf_Sym *)sechdrs[i].sh_offset;
921
922 /* Go through symbols for a match */
923 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
924 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
925 continue;
926
927 if (strcmp(strtab + syms[k].st_name, name) != 0)
928 continue;
929
930 if (syms[k].st_shndx == SHN_UNDEF ||
931 syms[k].st_shndx >= ehdr->e_shnum) {
932 pr_debug("Symbol: %s has bad section index %d.\n",
933 name, syms[k].st_shndx);
934 return NULL;
935 }
936
937 /* Found the symbol we are looking for */
938 return &syms[k];
939 }
940 }
941
942 return NULL;
943}
944
945void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
946{
947 struct purgatory_info *pi = &image->purgatory_info;
948 Elf_Sym *sym;
949 Elf_Shdr *sechdr;
950
951 sym = kexec_purgatory_find_symbol(pi, name);
952 if (!sym)
953 return ERR_PTR(-EINVAL);
954
955 sechdr = &pi->sechdrs[sym->st_shndx];
956
957 /*
958 * Returns the address where symbol will finally be loaded after
959 * kexec_load_segment()
960 */
961 return (void *)(sechdr->sh_addr + sym->st_value);
962}
963
964/*
965 * Get or set value of a symbol. If "get_value" is true, symbol value is
966 * returned in buf otherwise symbol value is set based on value in buf.
967 */
968int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
969 void *buf, unsigned int size, bool get_value)
970{
971 Elf_Sym *sym;
972 Elf_Shdr *sechdrs;
973 struct purgatory_info *pi = &image->purgatory_info;
974 char *sym_buf;
975
976 sym = kexec_purgatory_find_symbol(pi, name);
977 if (!sym)
978 return -EINVAL;
979
980 if (sym->st_size != size) {
981 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
982 name, (unsigned long)sym->st_size, size);
983 return -EINVAL;
984 }
985
986 sechdrs = pi->sechdrs;
987
988 if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
989 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
990 get_value ? "get" : "set");
991 return -EINVAL;
992 }
993
994 sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
995 sym->st_value;
996
997 if (get_value)
998 memcpy((void *)buf, sym_buf, size);
999 else
1000 memcpy((void *)sym_buf, buf, size);
1001
1002 return 0;
1003}
1004
generated by cgit at 2024-05-18 13:29:05 (GMT)