projects/linux·blob v4.15 · refs

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1/*
2 * kexec: kexec_file_load system call
3 *
4 * Copyright (C) 2014 Red Hat Inc.
5 * Authors:
6 * Vivek Goyal <[email protected]>
7 *
8 * This source code is licensed under the GNU General Public License,
9 * Version 2. See the file COPYING for more details.
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/capability.h>
15#include <linux/mm.h>
16#include <linux/file.h>
17#include <linux/slab.h>
18#include <linux/kexec.h>
19#include <linux/mutex.h>
20#include <linux/list.h>
21#include <linux/fs.h>
22#include <linux/ima.h>
23#include <crypto/hash.h>
24#include <crypto/sha.h>
25#include <linux/syscalls.h>
26#include <linux/vmalloc.h>
27#include "kexec_internal.h"
28
29static int kexec_calculate_store_digests(struct kimage *image);
30
31/* Architectures can provide this probe function */
32int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
33 unsigned long buf_len)
34{
35 return -ENOEXEC;
36}
37
38void * __weak arch_kexec_kernel_image_load(struct kimage *image)
39{
40 return ERR_PTR(-ENOEXEC);
41}
42
43int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
44{
45 return -EINVAL;
46}
47
48#ifdef CONFIG_KEXEC_VERIFY_SIG
49int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
50 unsigned long buf_len)
51{
52 return -EKEYREJECTED;
53}
54#endif
55
56/* Apply relocations of type RELA */
57int __weak
58arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
59 unsigned int relsec)
60{
61 pr_err("RELA relocation unsupported.\n");
62 return -ENOEXEC;
63}
64
65/* Apply relocations of type REL */
66int __weak
67arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
68 unsigned int relsec)
69{
70 pr_err("REL relocation unsupported.\n");
71 return -ENOEXEC;
72}
73
74/*
75 * Free up memory used by kernel, initrd, and command line. This is temporary
76 * memory allocation which is not needed any more after these buffers have
77 * been loaded into separate segments and have been copied elsewhere.
78 */
79void kimage_file_post_load_cleanup(struct kimage *image)
80{
81 struct purgatory_info *pi = &image->purgatory_info;
82
83 vfree(image->kernel_buf);
84 image->kernel_buf = NULL;
85
86 vfree(image->initrd_buf);
87 image->initrd_buf = NULL;
88
89 kfree(image->cmdline_buf);
90 image->cmdline_buf = NULL;
91
92 vfree(pi->purgatory_buf);
93 pi->purgatory_buf = NULL;
94
95 vfree(pi->sechdrs);
96 pi->sechdrs = NULL;
97
98 /* See if architecture has anything to cleanup post load */
99 arch_kimage_file_post_load_cleanup(image);
100
101 /*
102 * Above call should have called into bootloader to free up
103 * any data stored in kimage->image_loader_data. It should
104 * be ok now to free it up.
105 */
106 kfree(image->image_loader_data);
107 image->image_loader_data = NULL;
108}
109
110/*
111 * In file mode list of segments is prepared by kernel. Copy relevant
112 * data from user space, do error checking, prepare segment list
113 */
114static int
115kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
116 const char __user *cmdline_ptr,
117 unsigned long cmdline_len, unsigned flags)
118{
119 int ret = 0;
120 void *ldata;
121 loff_t size;
122
123 ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
124 &size, INT_MAX, READING_KEXEC_IMAGE);
125 if (ret)
126 return ret;
127 image->kernel_buf_len = size;
128
129 /* IMA needs to pass the measurement list to the next kernel. */
130 ima_add_kexec_buffer(image);
131
132 /* Call arch image probe handlers */
133 ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
134 image->kernel_buf_len);
135 if (ret)
136 goto out;
137
138#ifdef CONFIG_KEXEC_VERIFY_SIG
139 ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
140 image->kernel_buf_len);
141 if (ret) {
142 pr_debug("kernel signature verification failed.\n");
143 goto out;
144 }
145 pr_debug("kernel signature verification successful.\n");
146#endif
147 /* It is possible that there no initramfs is being loaded */
148 if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
149 ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
150 &size, INT_MAX,
151 READING_KEXEC_INITRAMFS);
152 if (ret)
153 goto out;
154 image->initrd_buf_len = size;
155 }
156
157 if (cmdline_len) {
158 image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
159 if (IS_ERR(image->cmdline_buf)) {
160 ret = PTR_ERR(image->cmdline_buf);
161 image->cmdline_buf = NULL;
162 goto out;
163 }
164
165 image->cmdline_buf_len = cmdline_len;
166
167 /* command line should be a string with last byte null */
168 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
169 ret = -EINVAL;
170 goto out;
171 }
172 }
173
174 /* Call arch image load handlers */
175 ldata = arch_kexec_kernel_image_load(image);
176
177 if (IS_ERR(ldata)) {
178 ret = PTR_ERR(ldata);
179 goto out;
180 }
181
182 image->image_loader_data = ldata;
183out:
184 /* In case of error, free up all allocated memory in this function */
185 if (ret)
186 kimage_file_post_load_cleanup(image);
187 return ret;
188}
189
190static int
191kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
192 int initrd_fd, const char __user *cmdline_ptr,
193 unsigned long cmdline_len, unsigned long flags)
194{
195 int ret;
196 struct kimage *image;
197 bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
198
199 image = do_kimage_alloc_init();
200 if (!image)
201 return -ENOMEM;
202
203 image->file_mode = 1;
204
205 if (kexec_on_panic) {
206 /* Enable special crash kernel control page alloc policy. */
207 image->control_page = crashk_res.start;
208 image->type = KEXEC_TYPE_CRASH;
209 }
210
211 ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
212 cmdline_ptr, cmdline_len, flags);
213 if (ret)
214 goto out_free_image;
215
216 ret = sanity_check_segment_list(image);
217 if (ret)
218 goto out_free_post_load_bufs;
219
220 ret = -ENOMEM;
221 image->control_code_page = kimage_alloc_control_pages(image,
222 get_order(KEXEC_CONTROL_PAGE_SIZE));
223 if (!image->control_code_page) {
224 pr_err("Could not allocate control_code_buffer\n");
225 goto out_free_post_load_bufs;
226 }
227
228 if (!kexec_on_panic) {
229 image->swap_page = kimage_alloc_control_pages(image, 0);
230 if (!image->swap_page) {
231 pr_err("Could not allocate swap buffer\n");
232 goto out_free_control_pages;
233 }
234 }
235
236 *rimage = image;
237 return 0;
238out_free_control_pages:
239 kimage_free_page_list(&image->control_pages);
240out_free_post_load_bufs:
241 kimage_file_post_load_cleanup(image);
242out_free_image:
243 kfree(image);
244 return ret;
245}
246
247SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
248 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
249 unsigned long, flags)
250{
251 int ret = 0, i;
252 struct kimage **dest_image, *image;
253
254 /* We only trust the superuser with rebooting the system. */
255 if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
256 return -EPERM;
257
258 /* Make sure we have a legal set of flags */
259 if (flags != (flags & KEXEC_FILE_FLAGS))
260 return -EINVAL;
261
262 image = NULL;
263
264 if (!mutex_trylock(&kexec_mutex))
265 return -EBUSY;
266
267 dest_image = &kexec_image;
268 if (flags & KEXEC_FILE_ON_CRASH) {
269 dest_image = &kexec_crash_image;
270 if (kexec_crash_image)
271 arch_kexec_unprotect_crashkres();
272 }
273
274 if (flags & KEXEC_FILE_UNLOAD)
275 goto exchange;
276
277 /*
278 * In case of crash, new kernel gets loaded in reserved region. It is
279 * same memory where old crash kernel might be loaded. Free any
280 * current crash dump kernel before we corrupt it.
281 */
282 if (flags & KEXEC_FILE_ON_CRASH)
283 kimage_free(xchg(&kexec_crash_image, NULL));
284
285 ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
286 cmdline_len, flags);
287 if (ret)
288 goto out;
289
290 ret = machine_kexec_prepare(image);
291 if (ret)
292 goto out;
293
294 /*
295 * Some architecture(like S390) may touch the crash memory before
296 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
297 */
298 ret = kimage_crash_copy_vmcoreinfo(image);
299 if (ret)
300 goto out;
301
302 ret = kexec_calculate_store_digests(image);
303 if (ret)
304 goto out;
305
306 for (i = 0; i < image->nr_segments; i++) {
307 struct kexec_segment *ksegment;
308
309 ksegment = &image->segment[i];
310 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
311 i, ksegment->buf, ksegment->bufsz, ksegment->mem,
312 ksegment->memsz);
313
314 ret = kimage_load_segment(image, &image->segment[i]);
315 if (ret)
316 goto out;
317 }
318
319 kimage_terminate(image);
320
321 /*
322 * Free up any temporary buffers allocated which are not needed
323 * after image has been loaded
324 */
325 kimage_file_post_load_cleanup(image);
326exchange:
327 image = xchg(dest_image, image);
328out:
329 if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
330 arch_kexec_protect_crashkres();
331
332 mutex_unlock(&kexec_mutex);
333 kimage_free(image);
334 return ret;
335}
336
337static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
338 struct kexec_buf *kbuf)
339{
340 struct kimage *image = kbuf->image;
341 unsigned long temp_start, temp_end;
342
343 temp_end = min(end, kbuf->buf_max);
344 temp_start = temp_end - kbuf->memsz;
345
346 do {
347 /* align down start */
348 temp_start = temp_start & (~(kbuf->buf_align - 1));
349
350 if (temp_start < start || temp_start < kbuf->buf_min)
351 return 0;
352
353 temp_end = temp_start + kbuf->memsz - 1;
354
355 /*
356 * Make sure this does not conflict with any of existing
357 * segments
358 */
359 if (kimage_is_destination_range(image, temp_start, temp_end)) {
360 temp_start = temp_start - PAGE_SIZE;
361 continue;
362 }
363
364 /* We found a suitable memory range */
365 break;
366 } while (1);
367
368 /* If we are here, we found a suitable memory range */
369 kbuf->mem = temp_start;
370
371 /* Success, stop navigating through remaining System RAM ranges */
372 return 1;
373}
374
375static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
376 struct kexec_buf *kbuf)
377{
378 struct kimage *image = kbuf->image;
379 unsigned long temp_start, temp_end;
380
381 temp_start = max(start, kbuf->buf_min);
382
383 do {
384 temp_start = ALIGN(temp_start, kbuf->buf_align);
385 temp_end = temp_start + kbuf->memsz - 1;
386
387 if (temp_end > end || temp_end > kbuf->buf_max)
388 return 0;
389 /*
390 * Make sure this does not conflict with any of existing
391 * segments
392 */
393 if (kimage_is_destination_range(image, temp_start, temp_end)) {
394 temp_start = temp_start + PAGE_SIZE;
395 continue;
396 }
397
398 /* We found a suitable memory range */
399 break;
400 } while (1);
401
402 /* If we are here, we found a suitable memory range */
403 kbuf->mem = temp_start;
404
405 /* Success, stop navigating through remaining System RAM ranges */
406 return 1;
407}
408
409static int locate_mem_hole_callback(struct resource *res, void *arg)
410{
411 struct kexec_buf *kbuf = (struct kexec_buf *)arg;
412 u64 start = res->start, end = res->end;
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 * arch_kexec_walk_mem - call func(data) on free memory regions
433 * @kbuf: Context info for the search. Also passed to @func.
434 * @func: Function to call for each memory region.
435 *
436 * Return: The memory walk will stop when func returns a non-zero value
437 * and that value will be returned. If all free regions are visited without
438 * func returning non-zero, then zero will be returned.
439 */
440int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
441 int (*func)(struct resource *, void *))
442{
443 if (kbuf->image->type == KEXEC_TYPE_CRASH)
444 return walk_iomem_res_desc(crashk_res.desc,
445 IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
446 crashk_res.start, crashk_res.end,
447 kbuf, func);
448 else
449 return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
450}
451
452/**
453 * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
454 * @kbuf: Parameters for the memory search.
455 *
456 * On success, kbuf->mem will have the start address of the memory region found.
457 *
458 * Return: 0 on success, negative errno on error.
459 */
460int kexec_locate_mem_hole(struct kexec_buf *kbuf)
461{
462 int ret;
463
464 ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
465
466 return ret == 1 ? 0 : -EADDRNOTAVAIL;
467}
468
469/**
470 * kexec_add_buffer - place a buffer in a kexec segment
471 * @kbuf: Buffer contents and memory parameters.
472 *
473 * This function assumes that kexec_mutex is held.
474 * On successful return, @kbuf->mem will have the physical address of
475 * the buffer in memory.
476 *
477 * Return: 0 on success, negative errno on error.
478 */
479int kexec_add_buffer(struct kexec_buf *kbuf)
480{
481
482 struct kexec_segment *ksegment;
483 int ret;
484
485 /* Currently adding segment this way is allowed only in file mode */
486 if (!kbuf->image->file_mode)
487 return -EINVAL;
488
489 if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
490 return -EINVAL;
491
492 /*
493 * Make sure we are not trying to add buffer after allocating
494 * control pages. All segments need to be placed first before
495 * any control pages are allocated. As control page allocation
496 * logic goes through list of segments to make sure there are
497 * no destination overlaps.
498 */
499 if (!list_empty(&kbuf->image->control_pages)) {
500 WARN_ON(1);
501 return -EINVAL;
502 }
503
504 /* Ensure minimum alignment needed for segments. */
505 kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
506 kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
507
508 /* Walk the RAM ranges and allocate a suitable range for the buffer */
509 ret = kexec_locate_mem_hole(kbuf);
510 if (ret)
511 return ret;
512
513 /* Found a suitable memory range */
514 ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
515 ksegment->kbuf = kbuf->buffer;
516 ksegment->bufsz = kbuf->bufsz;
517 ksegment->mem = kbuf->mem;
518 ksegment->memsz = kbuf->memsz;
519 kbuf->image->nr_segments++;
520 return 0;
521}
522
523/* Calculate and store the digest of segments */
524static int kexec_calculate_store_digests(struct kimage *image)
525{
526 struct crypto_shash *tfm;
527 struct shash_desc *desc;
528 int ret = 0, i, j, zero_buf_sz, sha_region_sz;
529 size_t desc_size, nullsz;
530 char *digest;
531 void *zero_buf;
532 struct kexec_sha_region *sha_regions;
533 struct purgatory_info *pi = &image->purgatory_info;
534
535 zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
536 zero_buf_sz = PAGE_SIZE;
537
538 tfm = crypto_alloc_shash("sha256", 0, 0);
539 if (IS_ERR(tfm)) {
540 ret = PTR_ERR(tfm);
541 goto out;
542 }
543
544 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
545 desc = kzalloc(desc_size, GFP_KERNEL);
546 if (!desc) {
547 ret = -ENOMEM;
548 goto out_free_tfm;
549 }
550
551 sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
552 sha_regions = vzalloc(sha_region_sz);
553 if (!sha_regions)
554 goto out_free_desc;
555
556 desc->tfm = tfm;
557 desc->flags = 0;
558
559 ret = crypto_shash_init(desc);
560 if (ret < 0)
561 goto out_free_sha_regions;
562
563 digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
564 if (!digest) {
565 ret = -ENOMEM;
566 goto out_free_sha_regions;
567 }
568
569 for (j = i = 0; i < image->nr_segments; i++) {
570 struct kexec_segment *ksegment;
571
572 ksegment = &image->segment[i];
573 /*
574 * Skip purgatory as it will be modified once we put digest
575 * info in purgatory.
576 */
577 if (ksegment->kbuf == pi->purgatory_buf)
578 continue;
579
580 ret = crypto_shash_update(desc, ksegment->kbuf,
581 ksegment->bufsz);
582 if (ret)
583 break;
584
585 /*
586 * Assume rest of the buffer is filled with zero and
587 * update digest accordingly.
588 */
589 nullsz = ksegment->memsz - ksegment->bufsz;
590 while (nullsz) {
591 unsigned long bytes = nullsz;
592
593 if (bytes > zero_buf_sz)
594 bytes = zero_buf_sz;
595 ret = crypto_shash_update(desc, zero_buf, bytes);
596 if (ret)
597 break;
598 nullsz -= bytes;
599 }
600
601 if (ret)
602 break;
603
604 sha_regions[j].start = ksegment->mem;
605 sha_regions[j].len = ksegment->memsz;
606 j++;
607 }
608
609 if (!ret) {
610 ret = crypto_shash_final(desc, digest);
611 if (ret)
612 goto out_free_digest;
613 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
614 sha_regions, sha_region_sz, 0);
615 if (ret)
616 goto out_free_digest;
617
618 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
619 digest, SHA256_DIGEST_SIZE, 0);
620 if (ret)
621 goto out_free_digest;
622 }
623
624out_free_digest:
625 kfree(digest);
626out_free_sha_regions:
627 vfree(sha_regions);
628out_free_desc:
629 kfree(desc);
630out_free_tfm:
631 kfree(tfm);
632out:
633 return ret;
634}
635
636/* Actually load purgatory. Lot of code taken from kexec-tools */
637static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
638 unsigned long max, int top_down)
639{
640 struct purgatory_info *pi = &image->purgatory_info;
641 unsigned long align, bss_align, bss_sz, bss_pad;
642 unsigned long entry, load_addr, curr_load_addr, bss_addr, offset;
643 unsigned char *buf_addr, *src;
644 int i, ret = 0, entry_sidx = -1;
645 const Elf_Shdr *sechdrs_c;
646 Elf_Shdr *sechdrs = NULL;
647 struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1,
648 .buf_min = min, .buf_max = max,
649 .top_down = top_down };
650
651 /*
652 * sechdrs_c points to section headers in purgatory and are read
653 * only. No modifications allowed.
654 */
655 sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
656
657 /*
658 * We can not modify sechdrs_c[] and its fields. It is read only.
659 * Copy it over to a local copy where one can store some temporary
660 * data and free it at the end. We need to modify ->sh_addr and
661 * ->sh_offset fields to keep track of permanent and temporary
662 * locations of sections.
663 */
664 sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
665 if (!sechdrs)
666 return -ENOMEM;
667
668 memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
669
670 /*
671 * We seem to have multiple copies of sections. First copy is which
672 * is embedded in kernel in read only section. Some of these sections
673 * will be copied to a temporary buffer and relocated. And these
674 * sections will finally be copied to their final destination at
675 * segment load time.
676 *
677 * Use ->sh_offset to reflect section address in memory. It will
678 * point to original read only copy if section is not allocatable.
679 * Otherwise it will point to temporary copy which will be relocated.
680 *
681 * Use ->sh_addr to contain final address of the section where it
682 * will go during execution time.
683 */
684 for (i = 0; i < pi->ehdr->e_shnum; i++) {
685 if (sechdrs[i].sh_type == SHT_NOBITS)
686 continue;
687
688 sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
689 sechdrs[i].sh_offset;
690 }
691
692 /*
693 * Identify entry point section and make entry relative to section
694 * start.
695 */
696 entry = pi->ehdr->e_entry;
697 for (i = 0; i < pi->ehdr->e_shnum; i++) {
698 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
699 continue;
700
701 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
702 continue;
703
704 /* Make entry section relative */
705 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
706 ((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
707 pi->ehdr->e_entry)) {
708 entry_sidx = i;
709 entry -= sechdrs[i].sh_addr;
710 break;
711 }
712 }
713
714 /* Determine how much memory is needed to load relocatable object. */
715 bss_align = 1;
716 bss_sz = 0;
717
718 for (i = 0; i < pi->ehdr->e_shnum; i++) {
719 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
720 continue;
721
722 align = sechdrs[i].sh_addralign;
723 if (sechdrs[i].sh_type != SHT_NOBITS) {
724 if (kbuf.buf_align < align)
725 kbuf.buf_align = align;
726 kbuf.bufsz = ALIGN(kbuf.bufsz, align);
727 kbuf.bufsz += sechdrs[i].sh_size;
728 } else {
729 /* bss section */
730 if (bss_align < align)
731 bss_align = align;
732 bss_sz = ALIGN(bss_sz, align);
733 bss_sz += sechdrs[i].sh_size;
734 }
735 }
736
737 /* Determine the bss padding required to align bss properly */
738 bss_pad = 0;
739 if (kbuf.bufsz & (bss_align - 1))
740 bss_pad = bss_align - (kbuf.bufsz & (bss_align - 1));
741
742 kbuf.memsz = kbuf.bufsz + bss_pad + bss_sz;
743
744 /* Allocate buffer for purgatory */
745 kbuf.buffer = vzalloc(kbuf.bufsz);
746 if (!kbuf.buffer) {
747 ret = -ENOMEM;
748 goto out;
749 }
750
751 if (kbuf.buf_align < bss_align)
752 kbuf.buf_align = bss_align;
753
754 /* Add buffer to segment list */
755 ret = kexec_add_buffer(&kbuf);
756 if (ret)
757 goto out;
758 pi->purgatory_load_addr = kbuf.mem;
759
760 /* Load SHF_ALLOC sections */
761 buf_addr = kbuf.buffer;
762 load_addr = curr_load_addr = pi->purgatory_load_addr;
763 bss_addr = load_addr + kbuf.bufsz + bss_pad;
764
765 for (i = 0; i < pi->ehdr->e_shnum; i++) {
766 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
767 continue;
768
769 align = sechdrs[i].sh_addralign;
770 if (sechdrs[i].sh_type != SHT_NOBITS) {
771 curr_load_addr = ALIGN(curr_load_addr, align);
772 offset = curr_load_addr - load_addr;
773 /* We already modifed ->sh_offset to keep src addr */
774 src = (char *) sechdrs[i].sh_offset;
775 memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
776
777 /* Store load address and source address of section */
778 sechdrs[i].sh_addr = curr_load_addr;
779
780 /*
781 * This section got copied to temporary buffer. Update
782 * ->sh_offset accordingly.
783 */
784 sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
785
786 /* Advance to the next address */
787 curr_load_addr += sechdrs[i].sh_size;
788 } else {
789 bss_addr = ALIGN(bss_addr, align);
790 sechdrs[i].sh_addr = bss_addr;
791 bss_addr += sechdrs[i].sh_size;
792 }
793 }
794
795 /* Update entry point based on load address of text section */
796 if (entry_sidx >= 0)
797 entry += sechdrs[entry_sidx].sh_addr;
798
799 /* Make kernel jump to purgatory after shutdown */
800 image->start = entry;
801
802 /* Used later to get/set symbol values */
803 pi->sechdrs = sechdrs;
804
805 /*
806 * Used later to identify which section is purgatory and skip it
807 * from checksumming.
808 */
809 pi->purgatory_buf = kbuf.buffer;
810 return ret;
811out:
812 vfree(sechdrs);
813 vfree(kbuf.buffer);
814 return ret;
815}
816
817static int kexec_apply_relocations(struct kimage *image)
818{
819 int i, ret;
820 struct purgatory_info *pi = &image->purgatory_info;
821 Elf_Shdr *sechdrs = pi->sechdrs;
822
823 /* Apply relocations */
824 for (i = 0; i < pi->ehdr->e_shnum; i++) {
825 Elf_Shdr *section, *symtab;
826
827 if (sechdrs[i].sh_type != SHT_RELA &&
828 sechdrs[i].sh_type != SHT_REL)
829 continue;
830
831 /*
832 * For section of type SHT_RELA/SHT_REL,
833 * ->sh_link contains section header index of associated
834 * symbol table. And ->sh_info contains section header
835 * index of section to which relocations apply.
836 */
837 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
838 sechdrs[i].sh_link >= pi->ehdr->e_shnum)
839 return -ENOEXEC;
840
841 section = &sechdrs[sechdrs[i].sh_info];
842 symtab = &sechdrs[sechdrs[i].sh_link];
843
844 if (!(section->sh_flags & SHF_ALLOC))
845 continue;
846
847 /*
848 * symtab->sh_link contain section header index of associated
849 * string table.
850 */
851 if (symtab->sh_link >= pi->ehdr->e_shnum)
852 /* Invalid section number? */
853 continue;
854
855 /*
856 * Respective architecture needs to provide support for applying
857 * relocations of type SHT_RELA/SHT_REL.
858 */
859 if (sechdrs[i].sh_type == SHT_RELA)
860 ret = arch_kexec_apply_relocations_add(pi->ehdr,
861 sechdrs, i);
862 else if (sechdrs[i].sh_type == SHT_REL)
863 ret = arch_kexec_apply_relocations(pi->ehdr,
864 sechdrs, i);
865 if (ret)
866 return ret;
867 }
868
869 return 0;
870}
871
872/* Load relocatable purgatory object and relocate it appropriately */
873int kexec_load_purgatory(struct kimage *image, unsigned long min,
874 unsigned long max, int top_down,
875 unsigned long *load_addr)
876{
877 struct purgatory_info *pi = &image->purgatory_info;
878 int ret;
879
880 if (kexec_purgatory_size <= 0)
881 return -EINVAL;
882
883 if (kexec_purgatory_size < sizeof(Elf_Ehdr))
884 return -ENOEXEC;
885
886 pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
887
888 if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
889 || pi->ehdr->e_type != ET_REL
890 || !elf_check_arch(pi->ehdr)
891 || pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
892 return -ENOEXEC;
893
894 if (pi->ehdr->e_shoff >= kexec_purgatory_size
895 || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
896 kexec_purgatory_size - pi->ehdr->e_shoff))
897 return -ENOEXEC;
898
899 ret = __kexec_load_purgatory(image, min, max, top_down);
900 if (ret)
901 return ret;
902
903 ret = kexec_apply_relocations(image);
904 if (ret)
905 goto out;
906
907 *load_addr = pi->purgatory_load_addr;
908 return 0;
909out:
910 vfree(pi->sechdrs);
911 pi->sechdrs = NULL;
912
913 vfree(pi->purgatory_buf);
914 pi->purgatory_buf = NULL;
915 return ret;
916}
917
918static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
919 const char *name)
920{
921 Elf_Sym *syms;
922 Elf_Shdr *sechdrs;
923 Elf_Ehdr *ehdr;
924 int i, k;
925 const char *strtab;
926
927 if (!pi->sechdrs || !pi->ehdr)
928 return NULL;
929
930 sechdrs = pi->sechdrs;
931 ehdr = pi->ehdr;
932
933 for (i = 0; i < ehdr->e_shnum; i++) {
934 if (sechdrs[i].sh_type != SHT_SYMTAB)
935 continue;
936
937 if (sechdrs[i].sh_link >= ehdr->e_shnum)
938 /* Invalid strtab section number */
939 continue;
940 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
941 syms = (Elf_Sym *)sechdrs[i].sh_offset;
942
943 /* Go through symbols for a match */
944 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
945 if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
946 continue;
947
948 if (strcmp(strtab + syms[k].st_name, name) != 0)
949 continue;
950
951 if (syms[k].st_shndx == SHN_UNDEF ||
952 syms[k].st_shndx >= ehdr->e_shnum) {
953 pr_debug("Symbol: %s has bad section index %d.\n",
954 name, syms[k].st_shndx);
955 return NULL;
956 }
957
958 /* Found the symbol we are looking for */
959 return &syms[k];
960 }
961 }
962
963 return NULL;
964}
965
966void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
967{
968 struct purgatory_info *pi = &image->purgatory_info;
969 Elf_Sym *sym;
970 Elf_Shdr *sechdr;
971
972 sym = kexec_purgatory_find_symbol(pi, name);
973 if (!sym)
974 return ERR_PTR(-EINVAL);
975
976 sechdr = &pi->sechdrs[sym->st_shndx];
977
978 /*
979 * Returns the address where symbol will finally be loaded after
980 * kexec_load_segment()
981 */
982 return (void *)(sechdr->sh_addr + sym->st_value);
983}
984
985/*
986 * Get or set value of a symbol. If "get_value" is true, symbol value is
987 * returned in buf otherwise symbol value is set based on value in buf.
988 */
989int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
990 void *buf, unsigned int size, bool get_value)
991{
992 Elf_Sym *sym;
993 Elf_Shdr *sechdrs;
994 struct purgatory_info *pi = &image->purgatory_info;
995 char *sym_buf;
996
997 sym = kexec_purgatory_find_symbol(pi, name);
998 if (!sym)
999 return -EINVAL;
1000
1001 if (sym->st_size != size) {
1002 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1003 name, (unsigned long)sym->st_size, size);
1004 return -EINVAL;
1005 }
1006
1007 sechdrs = pi->sechdrs;
1008
1009 if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
1010 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1011 get_value ? "get" : "set");
1012 return -EINVAL;
1013 }
1014
1015 sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
1016 sym->st_value;
1017
1018 if (get_value)
1019 memcpy((void *)buf, sym_buf, size);
1020 else
1021 memcpy((void *)sym_buf, buf, size);
1022
1023 return 0;
1024}