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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 <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
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)
472		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);
476	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}