blob: c72d2ff5896e9f37e21c789d45d7b2cc058be9f0 [file] [log] [blame]
Dave Younga43cac02015-09-09 15:38:51 -07001/*
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
Minfei Huangde90a6b2015-11-06 16:32:45 -080012#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
Dave Younga43cac02015-09-09 15:38:51 -070014#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>
Mimi Zoharb804def2016-01-14 20:59:14 -050021#include <linux/fs.h>
Dave Younga43cac02015-09-09 15:38:51 -070022#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
Dave Younga43cac02015-09-09 15:38:51 -070037/* 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
Xunlei Pang978e30c2016-01-20 15:00:36 -080054#ifdef CONFIG_KEXEC_VERIFY_SIG
Dave Younga43cac02015-09-09 15:38:51 -070055int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
56 unsigned long buf_len)
57{
58 return -EKEYREJECTED;
59}
Xunlei Pang978e30c2016-01-20 15:00:36 -080060#endif
Dave Younga43cac02015-09-09 15:38:51 -070061
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;
Mimi Zoharb804def2016-01-14 20:59:14 -0500127 loff_t size;
Dave Younga43cac02015-09-09 15:38:51 -0700128
Mimi Zoharb804def2016-01-14 20:59:14 -0500129 ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
130 &size, INT_MAX, READING_KEXEC_IMAGE);
Dave Younga43cac02015-09-09 15:38:51 -0700131 if (ret)
132 return ret;
Mimi Zoharb804def2016-01-14 20:59:14 -0500133 image->kernel_buf_len = size;
Dave Younga43cac02015-09-09 15:38:51 -0700134
135 /* Call arch image probe handlers */
136 ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
137 image->kernel_buf_len);
Dave Younga43cac02015-09-09 15:38:51 -0700138 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)) {
Mimi Zoharb804def2016-01-14 20:59:14 -0500152 ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
153 &size, INT_MAX,
154 READING_KEXEC_INITRAMFS);
Dave Younga43cac02015-09-09 15:38:51 -0700155 if (ret)
156 goto out;
Mimi Zoharb804def2016-01-14 20:59:14 -0500157 image->initrd_buf_len = size;
Dave Younga43cac02015-09-09 15:38:51 -0700158 }
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
280 if (flags & KEXEC_FILE_UNLOAD)
281 goto exchange;
282
283 /*
284 * In case of crash, new kernel gets loaded in reserved region. It is
285 * same memory where old crash kernel might be loaded. Free any
286 * current crash dump kernel before we corrupt it.
287 */
288 if (flags & KEXEC_FILE_ON_CRASH)
289 kimage_free(xchg(&kexec_crash_image, NULL));
290
291 ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
292 cmdline_len, flags);
293 if (ret)
294 goto out;
295
296 ret = machine_kexec_prepare(image);
297 if (ret)
298 goto out;
299
300 ret = kexec_calculate_store_digests(image);
301 if (ret)
302 goto out;
303
304 for (i = 0; i < image->nr_segments; i++) {
305 struct kexec_segment *ksegment;
306
307 ksegment = &image->segment[i];
308 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
309 i, ksegment->buf, ksegment->bufsz, ksegment->mem,
310 ksegment->memsz);
311
312 ret = kimage_load_segment(image, &image->segment[i]);
313 if (ret)
314 goto out;
315 }
316
317 kimage_terminate(image);
318
319 /*
320 * Free up any temporary buffers allocated which are not needed
321 * after image has been loaded
322 */
323 kimage_file_post_load_cleanup(image);
324exchange:
325 image = xchg(dest_image, image);
326out:
327 mutex_unlock(&kexec_mutex);
328 kimage_free(image);
329 return ret;
330}
331
332static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
333 struct kexec_buf *kbuf)
334{
335 struct kimage *image = kbuf->image;
336 unsigned long temp_start, temp_end;
337
338 temp_end = min(end, kbuf->buf_max);
339 temp_start = temp_end - kbuf->memsz;
340
341 do {
342 /* align down start */
343 temp_start = temp_start & (~(kbuf->buf_align - 1));
344
345 if (temp_start < start || temp_start < kbuf->buf_min)
346 return 0;
347
348 temp_end = temp_start + kbuf->memsz - 1;
349
350 /*
351 * Make sure this does not conflict with any of existing
352 * segments
353 */
354 if (kimage_is_destination_range(image, temp_start, temp_end)) {
355 temp_start = temp_start - PAGE_SIZE;
356 continue;
357 }
358
359 /* We found a suitable memory range */
360 break;
361 } while (1);
362
363 /* If we are here, we found a suitable memory range */
364 kbuf->mem = temp_start;
365
366 /* Success, stop navigating through remaining System RAM ranges */
367 return 1;
368}
369
370static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
371 struct kexec_buf *kbuf)
372{
373 struct kimage *image = kbuf->image;
374 unsigned long temp_start, temp_end;
375
376 temp_start = max(start, kbuf->buf_min);
377
378 do {
379 temp_start = ALIGN(temp_start, kbuf->buf_align);
380 temp_end = temp_start + kbuf->memsz - 1;
381
382 if (temp_end > end || temp_end > kbuf->buf_max)
383 return 0;
384 /*
385 * Make sure this does not conflict with any of existing
386 * segments
387 */
388 if (kimage_is_destination_range(image, temp_start, temp_end)) {
389 temp_start = temp_start + PAGE_SIZE;
390 continue;
391 }
392
393 /* We found a suitable memory range */
394 break;
395 } while (1);
396
397 /* If we are here, we found a suitable memory range */
398 kbuf->mem = temp_start;
399
400 /* Success, stop navigating through remaining System RAM ranges */
401 return 1;
402}
403
404static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
405{
406 struct kexec_buf *kbuf = (struct kexec_buf *)arg;
407 unsigned long sz = end - start + 1;
408
409 /* Returning 0 will take to next memory range */
410 if (sz < kbuf->memsz)
411 return 0;
412
413 if (end < kbuf->buf_min || start > kbuf->buf_max)
414 return 0;
415
416 /*
417 * Allocate memory top down with-in ram range. Otherwise bottom up
418 * allocation.
419 */
420 if (kbuf->top_down)
421 return locate_mem_hole_top_down(start, end, kbuf);
422 return locate_mem_hole_bottom_up(start, end, kbuf);
423}
424
425/*
426 * Helper function for placing a buffer in a kexec segment. This assumes
427 * that kexec_mutex is held.
428 */
429int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
430 unsigned long memsz, unsigned long buf_align,
431 unsigned long buf_min, unsigned long buf_max,
432 bool top_down, unsigned long *load_addr)
433{
434
435 struct kexec_segment *ksegment;
436 struct kexec_buf buf, *kbuf;
437 int ret;
438
439 /* Currently adding segment this way is allowed only in file mode */
440 if (!image->file_mode)
441 return -EINVAL;
442
443 if (image->nr_segments >= KEXEC_SEGMENT_MAX)
444 return -EINVAL;
445
446 /*
447 * Make sure we are not trying to add buffer after allocating
448 * control pages. All segments need to be placed first before
449 * any control pages are allocated. As control page allocation
450 * logic goes through list of segments to make sure there are
451 * no destination overlaps.
452 */
453 if (!list_empty(&image->control_pages)) {
454 WARN_ON(1);
455 return -EINVAL;
456 }
457
458 memset(&buf, 0, sizeof(struct kexec_buf));
459 kbuf = &buf;
460 kbuf->image = image;
461 kbuf->buffer = buffer;
462 kbuf->bufsz = bufsz;
463
464 kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
465 kbuf->buf_align = max(buf_align, PAGE_SIZE);
466 kbuf->buf_min = buf_min;
467 kbuf->buf_max = buf_max;
468 kbuf->top_down = top_down;
469
470 /* Walk the RAM ranges and allocate a suitable range for the buffer */
471 if (image->type == KEXEC_TYPE_CRASH)
Toshi Kanif0f47112016-01-26 21:57:30 +0100472 ret = walk_iomem_res_desc(crashk_res.desc,
473 IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
474 crashk_res.start, crashk_res.end, kbuf,
475 locate_mem_hole_callback);
Dave Younga43cac02015-09-09 15:38:51 -0700476 else
477 ret = walk_system_ram_res(0, -1, kbuf,
478 locate_mem_hole_callback);
479 if (ret != 1) {
480 /* A suitable memory range could not be found for buffer */
481 return -EADDRNOTAVAIL;
482 }
483
484 /* Found a suitable memory range */
485 ksegment = &image->segment[image->nr_segments];
486 ksegment->kbuf = kbuf->buffer;
487 ksegment->bufsz = kbuf->bufsz;
488 ksegment->mem = kbuf->mem;
489 ksegment->memsz = kbuf->memsz;
490 image->nr_segments++;
491 *load_addr = ksegment->mem;
492 return 0;
493}
494
495/* Calculate and store the digest of segments */
496static int kexec_calculate_store_digests(struct kimage *image)
497{
498 struct crypto_shash *tfm;
499 struct shash_desc *desc;
500 int ret = 0, i, j, zero_buf_sz, sha_region_sz;
501 size_t desc_size, nullsz;
502 char *digest;
503 void *zero_buf;
504 struct kexec_sha_region *sha_regions;
505 struct purgatory_info *pi = &image->purgatory_info;
506
507 zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
508 zero_buf_sz = PAGE_SIZE;
509
510 tfm = crypto_alloc_shash("sha256", 0, 0);
511 if (IS_ERR(tfm)) {
512 ret = PTR_ERR(tfm);
513 goto out;
514 }
515
516 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
517 desc = kzalloc(desc_size, GFP_KERNEL);
518 if (!desc) {
519 ret = -ENOMEM;
520 goto out_free_tfm;
521 }
522
523 sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
524 sha_regions = vzalloc(sha_region_sz);
525 if (!sha_regions)
526 goto out_free_desc;
527
528 desc->tfm = tfm;
529 desc->flags = 0;
530
531 ret = crypto_shash_init(desc);
532 if (ret < 0)
533 goto out_free_sha_regions;
534
535 digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
536 if (!digest) {
537 ret = -ENOMEM;
538 goto out_free_sha_regions;
539 }
540
541 for (j = i = 0; i < image->nr_segments; i++) {
542 struct kexec_segment *ksegment;
543
544 ksegment = &image->segment[i];
545 /*
546 * Skip purgatory as it will be modified once we put digest
547 * info in purgatory.
548 */
549 if (ksegment->kbuf == pi->purgatory_buf)
550 continue;
551
552 ret = crypto_shash_update(desc, ksegment->kbuf,
553 ksegment->bufsz);
554 if (ret)
555 break;
556
557 /*
558 * Assume rest of the buffer is filled with zero and
559 * update digest accordingly.
560 */
561 nullsz = ksegment->memsz - ksegment->bufsz;
562 while (nullsz) {
563 unsigned long bytes = nullsz;
564
565 if (bytes > zero_buf_sz)
566 bytes = zero_buf_sz;
567 ret = crypto_shash_update(desc, zero_buf, bytes);
568 if (ret)
569 break;
570 nullsz -= bytes;
571 }
572
573 if (ret)
574 break;
575
576 sha_regions[j].start = ksegment->mem;
577 sha_regions[j].len = ksegment->memsz;
578 j++;
579 }
580
581 if (!ret) {
582 ret = crypto_shash_final(desc, digest);
583 if (ret)
584 goto out_free_digest;
585 ret = kexec_purgatory_get_set_symbol(image, "sha_regions",
586 sha_regions, sha_region_sz, 0);
587 if (ret)
588 goto out_free_digest;
589
590 ret = kexec_purgatory_get_set_symbol(image, "sha256_digest",
591 digest, SHA256_DIGEST_SIZE, 0);
592 if (ret)
593 goto out_free_digest;
594 }
595
596out_free_digest:
597 kfree(digest);
598out_free_sha_regions:
599 vfree(sha_regions);
600out_free_desc:
601 kfree(desc);
602out_free_tfm:
603 kfree(tfm);
604out:
605 return ret;
606}
607
608/* Actually load purgatory. Lot of code taken from kexec-tools */
609static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
610 unsigned long max, int top_down)
611{
612 struct purgatory_info *pi = &image->purgatory_info;
613 unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
614 unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
615 unsigned char *buf_addr, *src;
616 int i, ret = 0, entry_sidx = -1;
617 const Elf_Shdr *sechdrs_c;
618 Elf_Shdr *sechdrs = NULL;
619 void *purgatory_buf = NULL;
620
621 /*
622 * sechdrs_c points to section headers in purgatory and are read
623 * only. No modifications allowed.
624 */
625 sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
626
627 /*
628 * We can not modify sechdrs_c[] and its fields. It is read only.
629 * Copy it over to a local copy where one can store some temporary
630 * data and free it at the end. We need to modify ->sh_addr and
631 * ->sh_offset fields to keep track of permanent and temporary
632 * locations of sections.
633 */
634 sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
635 if (!sechdrs)
636 return -ENOMEM;
637
638 memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
639
640 /*
641 * We seem to have multiple copies of sections. First copy is which
642 * is embedded in kernel in read only section. Some of these sections
643 * will be copied to a temporary buffer and relocated. And these
644 * sections will finally be copied to their final destination at
645 * segment load time.
646 *
647 * Use ->sh_offset to reflect section address in memory. It will
648 * point to original read only copy if section is not allocatable.
649 * Otherwise it will point to temporary copy which will be relocated.
650 *
651 * Use ->sh_addr to contain final address of the section where it
652 * will go during execution time.
653 */
654 for (i = 0; i < pi->ehdr->e_shnum; i++) {
655 if (sechdrs[i].sh_type == SHT_NOBITS)
656 continue;
657
658 sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
659 sechdrs[i].sh_offset;
660 }
661
662 /*
663 * Identify entry point section and make entry relative to section
664 * start.
665 */
666 entry = pi->ehdr->e_entry;
667 for (i = 0; i < pi->ehdr->e_shnum; i++) {
668 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
669 continue;
670
671 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
672 continue;
673
674 /* Make entry section relative */
675 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
676 ((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
677 pi->ehdr->e_entry)) {
678 entry_sidx = i;
679 entry -= sechdrs[i].sh_addr;
680 break;
681 }
682 }
683
684 /* Determine how much memory is needed to load relocatable object. */
685 buf_align = 1;
686 bss_align = 1;
687 buf_sz = 0;
688 bss_sz = 0;
689
690 for (i = 0; i < pi->ehdr->e_shnum; i++) {
691 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
692 continue;
693
694 align = sechdrs[i].sh_addralign;
695 if (sechdrs[i].sh_type != SHT_NOBITS) {
696 if (buf_align < align)
697 buf_align = align;
698 buf_sz = ALIGN(buf_sz, align);
699 buf_sz += sechdrs[i].sh_size;
700 } else {
701 /* bss section */
702 if (bss_align < align)
703 bss_align = align;
704 bss_sz = ALIGN(bss_sz, align);
705 bss_sz += sechdrs[i].sh_size;
706 }
707 }
708
709 /* Determine the bss padding required to align bss properly */
710 bss_pad = 0;
711 if (buf_sz & (bss_align - 1))
712 bss_pad = bss_align - (buf_sz & (bss_align - 1));
713
714 memsz = buf_sz + bss_pad + bss_sz;
715
716 /* Allocate buffer for purgatory */
717 purgatory_buf = vzalloc(buf_sz);
718 if (!purgatory_buf) {
719 ret = -ENOMEM;
720 goto out;
721 }
722
723 if (buf_align < bss_align)
724 buf_align = bss_align;
725
726 /* Add buffer to segment list */
727 ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
728 buf_align, min, max, top_down,
729 &pi->purgatory_load_addr);
730 if (ret)
731 goto out;
732
733 /* Load SHF_ALLOC sections */
734 buf_addr = purgatory_buf;
735 load_addr = curr_load_addr = pi->purgatory_load_addr;
736 bss_addr = load_addr + buf_sz + bss_pad;
737
738 for (i = 0; i < pi->ehdr->e_shnum; i++) {
739 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
740 continue;
741
742 align = sechdrs[i].sh_addralign;
743 if (sechdrs[i].sh_type != SHT_NOBITS) {
744 curr_load_addr = ALIGN(curr_load_addr, align);
745 offset = curr_load_addr - load_addr;
746 /* We already modifed ->sh_offset to keep src addr */
747 src = (char *) sechdrs[i].sh_offset;
748 memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
749
750 /* Store load address and source address of section */
751 sechdrs[i].sh_addr = curr_load_addr;
752
753 /*
754 * This section got copied to temporary buffer. Update
755 * ->sh_offset accordingly.
756 */
757 sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
758
759 /* Advance to the next address */
760 curr_load_addr += sechdrs[i].sh_size;
761 } else {
762 bss_addr = ALIGN(bss_addr, align);
763 sechdrs[i].sh_addr = bss_addr;
764 bss_addr += sechdrs[i].sh_size;
765 }
766 }
767
768 /* Update entry point based on load address of text section */
769 if (entry_sidx >= 0)
770 entry += sechdrs[entry_sidx].sh_addr;
771
772 /* Make kernel jump to purgatory after shutdown */
773 image->start = entry;
774
775 /* Used later to get/set symbol values */
776 pi->sechdrs = sechdrs;
777
778 /*
779 * Used later to identify which section is purgatory and skip it
780 * from checksumming.
781 */
782 pi->purgatory_buf = purgatory_buf;
783 return ret;
784out:
785 vfree(sechdrs);
786 vfree(purgatory_buf);
787 return ret;
788}
789
790static int kexec_apply_relocations(struct kimage *image)
791{
792 int i, ret;
793 struct purgatory_info *pi = &image->purgatory_info;
794 Elf_Shdr *sechdrs = pi->sechdrs;
795
796 /* Apply relocations */
797 for (i = 0; i < pi->ehdr->e_shnum; i++) {
798 Elf_Shdr *section, *symtab;
799
800 if (sechdrs[i].sh_type != SHT_RELA &&
801 sechdrs[i].sh_type != SHT_REL)
802 continue;
803
804 /*
805 * For section of type SHT_RELA/SHT_REL,
806 * ->sh_link contains section header index of associated
807 * symbol table. And ->sh_info contains section header
808 * index of section to which relocations apply.
809 */
810 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
811 sechdrs[i].sh_link >= pi->ehdr->e_shnum)
812 return -ENOEXEC;
813
814 section = &sechdrs[sechdrs[i].sh_info];
815 symtab = &sechdrs[sechdrs[i].sh_link];
816
817 if (!(section->sh_flags & SHF_ALLOC))
818 continue;
819
820 /*
821 * symtab->sh_link contain section header index of associated
822 * string table.
823 */
824 if (symtab->sh_link >= pi->ehdr->e_shnum)
825 /* Invalid section number? */
826 continue;
827
828 /*
829 * Respective architecture needs to provide support for applying
830 * relocations of type SHT_RELA/SHT_REL.
831 */
832 if (sechdrs[i].sh_type == SHT_RELA)
833 ret = arch_kexec_apply_relocations_add(pi->ehdr,
834 sechdrs, i);
835 else if (sechdrs[i].sh_type == SHT_REL)
836 ret = arch_kexec_apply_relocations(pi->ehdr,
837 sechdrs, i);
838 if (ret)
839 return ret;
840 }
841
842 return 0;
843}
844
845/* Load relocatable purgatory object and relocate it appropriately */
846int kexec_load_purgatory(struct kimage *image, unsigned long min,
847 unsigned long max, int top_down,
848 unsigned long *load_addr)
849{
850 struct purgatory_info *pi = &image->purgatory_info;
851 int ret;
852
853 if (kexec_purgatory_size <= 0)
854 return -EINVAL;
855
856 if (kexec_purgatory_size < sizeof(Elf_Ehdr))
857 return -ENOEXEC;
858
859 pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
860
861 if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
862 || pi->ehdr->e_type != ET_REL
863 || !elf_check_arch(pi->ehdr)
864 || pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
865 return -ENOEXEC;
866
867 if (pi->ehdr->e_shoff >= kexec_purgatory_size
868 || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
869 kexec_purgatory_size - pi->ehdr->e_shoff))
870 return -ENOEXEC;
871
872 ret = __kexec_load_purgatory(image, min, max, top_down);
873 if (ret)
874 return ret;
875
876 ret = kexec_apply_relocations(image);
877 if (ret)
878 goto out;
879
880 *load_addr = pi->purgatory_load_addr;
881 return 0;
882out:
883 vfree(pi->sechdrs);
884 vfree(pi->purgatory_buf);
885 return ret;
886}
887
888static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
889 const char *name)
890{
891 Elf_Sym *syms;
892 Elf_Shdr *sechdrs;
893 Elf_Ehdr *ehdr;
894 int i, k;
895 const char *strtab;
896
897 if (!pi->sechdrs || !pi->ehdr)
898 return NULL;
899
900 sechdrs = pi->sechdrs;
901 ehdr = pi->ehdr;
902
903 for (i = 0; i < ehdr->e_shnum; i++) {
904 if (sechdrs[i].sh_type != SHT_SYMTAB)
905 continue;
906
907 if (sechdrs[i].sh_link >= ehdr->e_shnum)
908 /* Invalid strtab section number */
909 continue;
910 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
911 syms = (Elf_Sym *)sechdrs[i].sh_offset;
912
913 /* Go through symbols for a match */
914 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
915 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
916 continue;
917
918 if (strcmp(strtab + syms[k].st_name, name) != 0)
919 continue;
920
921 if (syms[k].st_shndx == SHN_UNDEF ||
922 syms[k].st_shndx >= ehdr->e_shnum) {
923 pr_debug("Symbol: %s has bad section index %d.\n",
924 name, syms[k].st_shndx);
925 return NULL;
926 }
927
928 /* Found the symbol we are looking for */
929 return &syms[k];
930 }
931 }
932
933 return NULL;
934}
935
936void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
937{
938 struct purgatory_info *pi = &image->purgatory_info;
939 Elf_Sym *sym;
940 Elf_Shdr *sechdr;
941
942 sym = kexec_purgatory_find_symbol(pi, name);
943 if (!sym)
944 return ERR_PTR(-EINVAL);
945
946 sechdr = &pi->sechdrs[sym->st_shndx];
947
948 /*
949 * Returns the address where symbol will finally be loaded after
950 * kexec_load_segment()
951 */
952 return (void *)(sechdr->sh_addr + sym->st_value);
953}
954
955/*
956 * Get or set value of a symbol. If "get_value" is true, symbol value is
957 * returned in buf otherwise symbol value is set based on value in buf.
958 */
959int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
960 void *buf, unsigned int size, bool get_value)
961{
962 Elf_Sym *sym;
963 Elf_Shdr *sechdrs;
964 struct purgatory_info *pi = &image->purgatory_info;
965 char *sym_buf;
966
967 sym = kexec_purgatory_find_symbol(pi, name);
968 if (!sym)
969 return -EINVAL;
970
971 if (sym->st_size != size) {
972 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
973 name, (unsigned long)sym->st_size, size);
974 return -EINVAL;
975 }
976
977 sechdrs = pi->sechdrs;
978
979 if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
980 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
981 get_value ? "get" : "set");
982 return -EINVAL;
983 }
984
985 sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
986 sym->st_value;
987
988 if (get_value)
989 memcpy((void *)buf, sym_buf, size);
990 else
991 memcpy((void *)sym_buf, buf, size);
992
993 return 0;
994}