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Linux/kernel/kexec_file.c

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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 <linux/ima.h>
 23 #include <crypto/hash.h>
 24 #include <crypto/sha.h>
 25 #include <linux/elf.h>
 26 #include <linux/elfcore.h>
 27 #include <linux/kernel.h>
 28 #include <linux/kexec.h>
 29 #include <linux/slab.h>
 30 #include <linux/syscalls.h>
 31 #include <linux/vmalloc.h>
 32 #include "kexec_internal.h"
 33 
 34 static int kexec_calculate_store_digests(struct kimage *image);
 35 
 36 /*
 37  * Currently this is the only default function that is exported as some
 38  * architectures need it to do additional handlings.
 39  * In the future, other default functions may be exported too if required.
 40  */
 41 int kexec_image_probe_default(struct kimage *image, void *buf,
 42                               unsigned long buf_len)
 43 {
 44         const struct kexec_file_ops * const *fops;
 45         int ret = -ENOEXEC;
 46 
 47         for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
 48                 ret = (*fops)->probe(buf, buf_len);
 49                 if (!ret) {
 50                         image->fops = *fops;
 51                         return ret;
 52                 }
 53         }
 54 
 55         return ret;
 56 }
 57 
 58 /* Architectures can provide this probe function */
 59 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
 60                                          unsigned long buf_len)
 61 {
 62         return kexec_image_probe_default(image, buf, buf_len);
 63 }
 64 
 65 static void *kexec_image_load_default(struct kimage *image)
 66 {
 67         if (!image->fops || !image->fops->load)
 68                 return ERR_PTR(-ENOEXEC);
 69 
 70         return image->fops->load(image, image->kernel_buf,
 71                                  image->kernel_buf_len, image->initrd_buf,
 72                                  image->initrd_buf_len, image->cmdline_buf,
 73                                  image->cmdline_buf_len);
 74 }
 75 
 76 void * __weak arch_kexec_kernel_image_load(struct kimage *image)
 77 {
 78         return kexec_image_load_default(image);
 79 }
 80 
 81 static int kexec_image_post_load_cleanup_default(struct kimage *image)
 82 {
 83         if (!image->fops || !image->fops->cleanup)
 84                 return 0;
 85 
 86         return image->fops->cleanup(image->image_loader_data);
 87 }
 88 
 89 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
 90 {
 91         return kexec_image_post_load_cleanup_default(image);
 92 }
 93 
 94 #ifdef CONFIG_KEXEC_VERIFY_SIG
 95 static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
 96                                           unsigned long buf_len)
 97 {
 98         if (!image->fops || !image->fops->verify_sig) {
 99                 pr_debug("kernel loader does not support signature verification.\n");
100                 return -EKEYREJECTED;
101         }
102 
103         return image->fops->verify_sig(buf, buf_len);
104 }
105 
106 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
107                                         unsigned long buf_len)
108 {
109         return kexec_image_verify_sig_default(image, buf, buf_len);
110 }
111 #endif
112 
113 /*
114  * arch_kexec_apply_relocations_add - apply relocations of type RELA
115  * @pi:         Purgatory to be relocated.
116  * @section:    Section relocations applying to.
117  * @relsec:     Section containing RELAs.
118  * @symtab:     Corresponding symtab.
119  *
120  * Return: 0 on success, negative errno on error.
121  */
122 int __weak
123 arch_kexec_apply_relocations_add(struct purgatory_info *pi, Elf_Shdr *section,
124                                  const Elf_Shdr *relsec, const Elf_Shdr *symtab)
125 {
126         pr_err("RELA relocation unsupported.\n");
127         return -ENOEXEC;
128 }
129 
130 /*
131  * arch_kexec_apply_relocations - apply relocations of type REL
132  * @pi:         Purgatory to be relocated.
133  * @section:    Section relocations applying to.
134  * @relsec:     Section containing RELs.
135  * @symtab:     Corresponding symtab.
136  *
137  * Return: 0 on success, negative errno on error.
138  */
139 int __weak
140 arch_kexec_apply_relocations(struct purgatory_info *pi, Elf_Shdr *section,
141                              const Elf_Shdr *relsec, const Elf_Shdr *symtab)
142 {
143         pr_err("REL relocation unsupported.\n");
144         return -ENOEXEC;
145 }
146 
147 /*
148  * Free up memory used by kernel, initrd, and command line. This is temporary
149  * memory allocation which is not needed any more after these buffers have
150  * been loaded into separate segments and have been copied elsewhere.
151  */
152 void kimage_file_post_load_cleanup(struct kimage *image)
153 {
154         struct purgatory_info *pi = &image->purgatory_info;
155 
156         vfree(image->kernel_buf);
157         image->kernel_buf = NULL;
158 
159         vfree(image->initrd_buf);
160         image->initrd_buf = NULL;
161 
162         kfree(image->cmdline_buf);
163         image->cmdline_buf = NULL;
164 
165         vfree(pi->purgatory_buf);
166         pi->purgatory_buf = NULL;
167 
168         vfree(pi->sechdrs);
169         pi->sechdrs = NULL;
170 
171         /* See if architecture has anything to cleanup post load */
172         arch_kimage_file_post_load_cleanup(image);
173 
174         /*
175          * Above call should have called into bootloader to free up
176          * any data stored in kimage->image_loader_data. It should
177          * be ok now to free it up.
178          */
179         kfree(image->image_loader_data);
180         image->image_loader_data = NULL;
181 }
182 
183 /*
184  * In file mode list of segments is prepared by kernel. Copy relevant
185  * data from user space, do error checking, prepare segment list
186  */
187 static int
188 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
189                              const char __user *cmdline_ptr,
190                              unsigned long cmdline_len, unsigned flags)
191 {
192         int ret = 0;
193         void *ldata;
194         loff_t size;
195 
196         ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
197                                        &size, INT_MAX, READING_KEXEC_IMAGE);
198         if (ret)
199                 return ret;
200         image->kernel_buf_len = size;
201 
202         /* IMA needs to pass the measurement list to the next kernel. */
203         ima_add_kexec_buffer(image);
204 
205         /* Call arch image probe handlers */
206         ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
207                                             image->kernel_buf_len);
208         if (ret)
209                 goto out;
210 
211 #ifdef CONFIG_KEXEC_VERIFY_SIG
212         ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
213                                            image->kernel_buf_len);
214         if (ret) {
215                 pr_debug("kernel signature verification failed.\n");
216                 goto out;
217         }
218         pr_debug("kernel signature verification successful.\n");
219 #endif
220         /* It is possible that there no initramfs is being loaded */
221         if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
222                 ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
223                                                &size, INT_MAX,
224                                                READING_KEXEC_INITRAMFS);
225                 if (ret)
226                         goto out;
227                 image->initrd_buf_len = size;
228         }
229 
230         if (cmdline_len) {
231                 image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
232                 if (IS_ERR(image->cmdline_buf)) {
233                         ret = PTR_ERR(image->cmdline_buf);
234                         image->cmdline_buf = NULL;
235                         goto out;
236                 }
237 
238                 image->cmdline_buf_len = cmdline_len;
239 
240                 /* command line should be a string with last byte null */
241                 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
242                         ret = -EINVAL;
243                         goto out;
244                 }
245         }
246 
247         /* Call arch image load handlers */
248         ldata = arch_kexec_kernel_image_load(image);
249 
250         if (IS_ERR(ldata)) {
251                 ret = PTR_ERR(ldata);
252                 goto out;
253         }
254 
255         image->image_loader_data = ldata;
256 out:
257         /* In case of error, free up all allocated memory in this function */
258         if (ret)
259                 kimage_file_post_load_cleanup(image);
260         return ret;
261 }
262 
263 static int
264 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
265                        int initrd_fd, const char __user *cmdline_ptr,
266                        unsigned long cmdline_len, unsigned long flags)
267 {
268         int ret;
269         struct kimage *image;
270         bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
271 
272         image = do_kimage_alloc_init();
273         if (!image)
274                 return -ENOMEM;
275 
276         image->file_mode = 1;
277 
278         if (kexec_on_panic) {
279                 /* Enable special crash kernel control page alloc policy. */
280                 image->control_page = crashk_res.start;
281                 image->type = KEXEC_TYPE_CRASH;
282         }
283 
284         ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
285                                            cmdline_ptr, cmdline_len, flags);
286         if (ret)
287                 goto out_free_image;
288 
289         ret = sanity_check_segment_list(image);
290         if (ret)
291                 goto out_free_post_load_bufs;
292 
293         ret = -ENOMEM;
294         image->control_code_page = kimage_alloc_control_pages(image,
295                                            get_order(KEXEC_CONTROL_PAGE_SIZE));
296         if (!image->control_code_page) {
297                 pr_err("Could not allocate control_code_buffer\n");
298                 goto out_free_post_load_bufs;
299         }
300 
301         if (!kexec_on_panic) {
302                 image->swap_page = kimage_alloc_control_pages(image, 0);
303                 if (!image->swap_page) {
304                         pr_err("Could not allocate swap buffer\n");
305                         goto out_free_control_pages;
306                 }
307         }
308 
309         *rimage = image;
310         return 0;
311 out_free_control_pages:
312         kimage_free_page_list(&image->control_pages);
313 out_free_post_load_bufs:
314         kimage_file_post_load_cleanup(image);
315 out_free_image:
316         kfree(image);
317         return ret;
318 }
319 
320 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
321                 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
322                 unsigned long, flags)
323 {
324         int ret = 0, i;
325         struct kimage **dest_image, *image;
326 
327         /* We only trust the superuser with rebooting the system. */
328         if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
329                 return -EPERM;
330 
331         /* Make sure we have a legal set of flags */
332         if (flags != (flags & KEXEC_FILE_FLAGS))
333                 return -EINVAL;
334 
335         image = NULL;
336 
337         if (!mutex_trylock(&kexec_mutex))
338                 return -EBUSY;
339 
340         dest_image = &kexec_image;
341         if (flags & KEXEC_FILE_ON_CRASH) {
342                 dest_image = &kexec_crash_image;
343                 if (kexec_crash_image)
344                         arch_kexec_unprotect_crashkres();
345         }
346 
347         if (flags & KEXEC_FILE_UNLOAD)
348                 goto exchange;
349 
350         /*
351          * In case of crash, new kernel gets loaded in reserved region. It is
352          * same memory where old crash kernel might be loaded. Free any
353          * current crash dump kernel before we corrupt it.
354          */
355         if (flags & KEXEC_FILE_ON_CRASH)
356                 kimage_free(xchg(&kexec_crash_image, NULL));
357 
358         ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
359                                      cmdline_len, flags);
360         if (ret)
361                 goto out;
362 
363         ret = machine_kexec_prepare(image);
364         if (ret)
365                 goto out;
366 
367         /*
368          * Some architecture(like S390) may touch the crash memory before
369          * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
370          */
371         ret = kimage_crash_copy_vmcoreinfo(image);
372         if (ret)
373                 goto out;
374 
375         ret = kexec_calculate_store_digests(image);
376         if (ret)
377                 goto out;
378 
379         for (i = 0; i < image->nr_segments; i++) {
380                 struct kexec_segment *ksegment;
381 
382                 ksegment = &image->segment[i];
383                 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
384                          i, ksegment->buf, ksegment->bufsz, ksegment->mem,
385                          ksegment->memsz);
386 
387                 ret = kimage_load_segment(image, &image->segment[i]);
388                 if (ret)
389                         goto out;
390         }
391 
392         kimage_terminate(image);
393 
394         /*
395          * Free up any temporary buffers allocated which are not needed
396          * after image has been loaded
397          */
398         kimage_file_post_load_cleanup(image);
399 exchange:
400         image = xchg(dest_image, image);
401 out:
402         if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
403                 arch_kexec_protect_crashkres();
404 
405         mutex_unlock(&kexec_mutex);
406         kimage_free(image);
407         return ret;
408 }
409 
410 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
411                                     struct kexec_buf *kbuf)
412 {
413         struct kimage *image = kbuf->image;
414         unsigned long temp_start, temp_end;
415 
416         temp_end = min(end, kbuf->buf_max);
417         temp_start = temp_end - kbuf->memsz;
418 
419         do {
420                 /* align down start */
421                 temp_start = temp_start & (~(kbuf->buf_align - 1));
422 
423                 if (temp_start < start || temp_start < kbuf->buf_min)
424                         return 0;
425 
426                 temp_end = temp_start + kbuf->memsz - 1;
427 
428                 /*
429                  * Make sure this does not conflict with any of existing
430                  * segments
431                  */
432                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
433                         temp_start = temp_start - PAGE_SIZE;
434                         continue;
435                 }
436 
437                 /* We found a suitable memory range */
438                 break;
439         } while (1);
440 
441         /* If we are here, we found a suitable memory range */
442         kbuf->mem = temp_start;
443 
444         /* Success, stop navigating through remaining System RAM ranges */
445         return 1;
446 }
447 
448 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
449                                      struct kexec_buf *kbuf)
450 {
451         struct kimage *image = kbuf->image;
452         unsigned long temp_start, temp_end;
453 
454         temp_start = max(start, kbuf->buf_min);
455 
456         do {
457                 temp_start = ALIGN(temp_start, kbuf->buf_align);
458                 temp_end = temp_start + kbuf->memsz - 1;
459 
460                 if (temp_end > end || temp_end > kbuf->buf_max)
461                         return 0;
462                 /*
463                  * Make sure this does not conflict with any of existing
464                  * segments
465                  */
466                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
467                         temp_start = temp_start + PAGE_SIZE;
468                         continue;
469                 }
470 
471                 /* We found a suitable memory range */
472                 break;
473         } while (1);
474 
475         /* If we are here, we found a suitable memory range */
476         kbuf->mem = temp_start;
477 
478         /* Success, stop navigating through remaining System RAM ranges */
479         return 1;
480 }
481 
482 static int locate_mem_hole_callback(struct resource *res, void *arg)
483 {
484         struct kexec_buf *kbuf = (struct kexec_buf *)arg;
485         u64 start = res->start, end = res->end;
486         unsigned long sz = end - start + 1;
487 
488         /* Returning 0 will take to next memory range */
489         if (sz < kbuf->memsz)
490                 return 0;
491 
492         if (end < kbuf->buf_min || start > kbuf->buf_max)
493                 return 0;
494 
495         /*
496          * Allocate memory top down with-in ram range. Otherwise bottom up
497          * allocation.
498          */
499         if (kbuf->top_down)
500                 return locate_mem_hole_top_down(start, end, kbuf);
501         return locate_mem_hole_bottom_up(start, end, kbuf);
502 }
503 
504 /**
505  * arch_kexec_walk_mem - call func(data) on free memory regions
506  * @kbuf:       Context info for the search. Also passed to @func.
507  * @func:       Function to call for each memory region.
508  *
509  * Return: The memory walk will stop when func returns a non-zero value
510  * and that value will be returned. If all free regions are visited without
511  * func returning non-zero, then zero will be returned.
512  */
513 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
514                                int (*func)(struct resource *, void *))
515 {
516         if (kbuf->image->type == KEXEC_TYPE_CRASH)
517                 return walk_iomem_res_desc(crashk_res.desc,
518                                            IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
519                                            crashk_res.start, crashk_res.end,
520                                            kbuf, func);
521         else
522                 return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
523 }
524 
525 /**
526  * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
527  * @kbuf:       Parameters for the memory search.
528  *
529  * On success, kbuf->mem will have the start address of the memory region found.
530  *
531  * Return: 0 on success, negative errno on error.
532  */
533 int kexec_locate_mem_hole(struct kexec_buf *kbuf)
534 {
535         int ret;
536 
537         ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
538 
539         return ret == 1 ? 0 : -EADDRNOTAVAIL;
540 }
541 
542 /**
543  * kexec_add_buffer - place a buffer in a kexec segment
544  * @kbuf:       Buffer contents and memory parameters.
545  *
546  * This function assumes that kexec_mutex is held.
547  * On successful return, @kbuf->mem will have the physical address of
548  * the buffer in memory.
549  *
550  * Return: 0 on success, negative errno on error.
551  */
552 int kexec_add_buffer(struct kexec_buf *kbuf)
553 {
554 
555         struct kexec_segment *ksegment;
556         int ret;
557 
558         /* Currently adding segment this way is allowed only in file mode */
559         if (!kbuf->image->file_mode)
560                 return -EINVAL;
561 
562         if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
563                 return -EINVAL;
564 
565         /*
566          * Make sure we are not trying to add buffer after allocating
567          * control pages. All segments need to be placed first before
568          * any control pages are allocated. As control page allocation
569          * logic goes through list of segments to make sure there are
570          * no destination overlaps.
571          */
572         if (!list_empty(&kbuf->image->control_pages)) {
573                 WARN_ON(1);
574                 return -EINVAL;
575         }
576 
577         /* Ensure minimum alignment needed for segments. */
578         kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
579         kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
580 
581         /* Walk the RAM ranges and allocate a suitable range for the buffer */
582         ret = kexec_locate_mem_hole(kbuf);
583         if (ret)
584                 return ret;
585 
586         /* Found a suitable memory range */
587         ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
588         ksegment->kbuf = kbuf->buffer;
589         ksegment->bufsz = kbuf->bufsz;
590         ksegment->mem = kbuf->mem;
591         ksegment->memsz = kbuf->memsz;
592         kbuf->image->nr_segments++;
593         return 0;
594 }
595 
596 /* Calculate and store the digest of segments */
597 static int kexec_calculate_store_digests(struct kimage *image)
598 {
599         struct crypto_shash *tfm;
600         struct shash_desc *desc;
601         int ret = 0, i, j, zero_buf_sz, sha_region_sz;
602         size_t desc_size, nullsz;
603         char *digest;
604         void *zero_buf;
605         struct kexec_sha_region *sha_regions;
606         struct purgatory_info *pi = &image->purgatory_info;
607 
608         if (!IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY))
609                 return 0;
610 
611         zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
612         zero_buf_sz = PAGE_SIZE;
613 
614         tfm = crypto_alloc_shash("sha256", 0, 0);
615         if (IS_ERR(tfm)) {
616                 ret = PTR_ERR(tfm);
617                 goto out;
618         }
619 
620         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
621         desc = kzalloc(desc_size, GFP_KERNEL);
622         if (!desc) {
623                 ret = -ENOMEM;
624                 goto out_free_tfm;
625         }
626 
627         sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
628         sha_regions = vzalloc(sha_region_sz);
629         if (!sha_regions)
630                 goto out_free_desc;
631 
632         desc->tfm   = tfm;
633         desc->flags = 0;
634 
635         ret = crypto_shash_init(desc);
636         if (ret < 0)
637                 goto out_free_sha_regions;
638 
639         digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
640         if (!digest) {
641                 ret = -ENOMEM;
642                 goto out_free_sha_regions;
643         }
644 
645         for (j = i = 0; i < image->nr_segments; i++) {
646                 struct kexec_segment *ksegment;
647 
648                 ksegment = &image->segment[i];
649                 /*
650                  * Skip purgatory as it will be modified once we put digest
651                  * info in purgatory.
652                  */
653                 if (ksegment->kbuf == pi->purgatory_buf)
654                         continue;
655 
656                 ret = crypto_shash_update(desc, ksegment->kbuf,
657                                           ksegment->bufsz);
658                 if (ret)
659                         break;
660 
661                 /*
662                  * Assume rest of the buffer is filled with zero and
663                  * update digest accordingly.
664                  */
665                 nullsz = ksegment->memsz - ksegment->bufsz;
666                 while (nullsz) {
667                         unsigned long bytes = nullsz;
668 
669                         if (bytes > zero_buf_sz)
670                                 bytes = zero_buf_sz;
671                         ret = crypto_shash_update(desc, zero_buf, bytes);
672                         if (ret)
673                                 break;
674                         nullsz -= bytes;
675                 }
676 
677                 if (ret)
678                         break;
679 
680                 sha_regions[j].start = ksegment->mem;
681                 sha_regions[j].len = ksegment->memsz;
682                 j++;
683         }
684 
685         if (!ret) {
686                 ret = crypto_shash_final(desc, digest);
687                 if (ret)
688                         goto out_free_digest;
689                 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
690                                                      sha_regions, sha_region_sz, 0);
691                 if (ret)
692                         goto out_free_digest;
693 
694                 ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
695                                                      digest, SHA256_DIGEST_SIZE, 0);
696                 if (ret)
697                         goto out_free_digest;
698         }
699 
700 out_free_digest:
701         kfree(digest);
702 out_free_sha_regions:
703         vfree(sha_regions);
704 out_free_desc:
705         kfree(desc);
706 out_free_tfm:
707         kfree(tfm);
708 out:
709         return ret;
710 }
711 
712 #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
713 /*
714  * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
715  * @pi:         Purgatory to be loaded.
716  * @kbuf:       Buffer to setup.
717  *
718  * Allocates the memory needed for the buffer. Caller is responsible to free
719  * the memory after use.
720  *
721  * Return: 0 on success, negative errno on error.
722  */
723 static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
724                                       struct kexec_buf *kbuf)
725 {
726         const Elf_Shdr *sechdrs;
727         unsigned long bss_align;
728         unsigned long bss_sz;
729         unsigned long align;
730         int i, ret;
731 
732         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
733         kbuf->buf_align = bss_align = 1;
734         kbuf->bufsz = bss_sz = 0;
735 
736         for (i = 0; i < pi->ehdr->e_shnum; i++) {
737                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
738                         continue;
739 
740                 align = sechdrs[i].sh_addralign;
741                 if (sechdrs[i].sh_type != SHT_NOBITS) {
742                         if (kbuf->buf_align < align)
743                                 kbuf->buf_align = align;
744                         kbuf->bufsz = ALIGN(kbuf->bufsz, align);
745                         kbuf->bufsz += sechdrs[i].sh_size;
746                 } else {
747                         if (bss_align < align)
748                                 bss_align = align;
749                         bss_sz = ALIGN(bss_sz, align);
750                         bss_sz += sechdrs[i].sh_size;
751                 }
752         }
753         kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
754         kbuf->memsz = kbuf->bufsz + bss_sz;
755         if (kbuf->buf_align < bss_align)
756                 kbuf->buf_align = bss_align;
757 
758         kbuf->buffer = vzalloc(kbuf->bufsz);
759         if (!kbuf->buffer)
760                 return -ENOMEM;
761         pi->purgatory_buf = kbuf->buffer;
762 
763         ret = kexec_add_buffer(kbuf);
764         if (ret)
765                 goto out;
766 
767         return 0;
768 out:
769         vfree(pi->purgatory_buf);
770         pi->purgatory_buf = NULL;
771         return ret;
772 }
773 
774 /*
775  * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
776  * @pi:         Purgatory to be loaded.
777  * @kbuf:       Buffer prepared to store purgatory.
778  *
779  * Allocates the memory needed for the buffer. Caller is responsible to free
780  * the memory after use.
781  *
782  * Return: 0 on success, negative errno on error.
783  */
784 static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
785                                          struct kexec_buf *kbuf)
786 {
787         unsigned long bss_addr;
788         unsigned long offset;
789         Elf_Shdr *sechdrs;
790         int i;
791 
792         /*
793          * The section headers in kexec_purgatory are read-only. In order to
794          * have them modifiable make a temporary copy.
795          */
796         sechdrs = vzalloc(array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum));
797         if (!sechdrs)
798                 return -ENOMEM;
799         memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
800                pi->ehdr->e_shnum * sizeof(Elf_Shdr));
801         pi->sechdrs = sechdrs;
802 
803         offset = 0;
804         bss_addr = kbuf->mem + kbuf->bufsz;
805         kbuf->image->start = pi->ehdr->e_entry;
806 
807         for (i = 0; i < pi->ehdr->e_shnum; i++) {
808                 unsigned long align;
809                 void *src, *dst;
810 
811                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
812                         continue;
813 
814                 align = sechdrs[i].sh_addralign;
815                 if (sechdrs[i].sh_type == SHT_NOBITS) {
816                         bss_addr = ALIGN(bss_addr, align);
817                         sechdrs[i].sh_addr = bss_addr;
818                         bss_addr += sechdrs[i].sh_size;
819                         continue;
820                 }
821 
822                 offset = ALIGN(offset, align);
823                 if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
824                     pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
825                     pi->ehdr->e_entry < (sechdrs[i].sh_addr
826                                          + sechdrs[i].sh_size)) {
827                         kbuf->image->start -= sechdrs[i].sh_addr;
828                         kbuf->image->start += kbuf->mem + offset;
829                 }
830 
831                 src = (void *)pi->ehdr + sechdrs[i].sh_offset;
832                 dst = pi->purgatory_buf + offset;
833                 memcpy(dst, src, sechdrs[i].sh_size);
834 
835                 sechdrs[i].sh_addr = kbuf->mem + offset;
836                 sechdrs[i].sh_offset = offset;
837                 offset += sechdrs[i].sh_size;
838         }
839 
840         return 0;
841 }
842 
843 static int kexec_apply_relocations(struct kimage *image)
844 {
845         int i, ret;
846         struct purgatory_info *pi = &image->purgatory_info;
847         const Elf_Shdr *sechdrs;
848 
849         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
850 
851         for (i = 0; i < pi->ehdr->e_shnum; i++) {
852                 const Elf_Shdr *relsec;
853                 const Elf_Shdr *symtab;
854                 Elf_Shdr *section;
855 
856                 relsec = sechdrs + i;
857 
858                 if (relsec->sh_type != SHT_RELA &&
859                     relsec->sh_type != SHT_REL)
860                         continue;
861 
862                 /*
863                  * For section of type SHT_RELA/SHT_REL,
864                  * ->sh_link contains section header index of associated
865                  * symbol table. And ->sh_info contains section header
866                  * index of section to which relocations apply.
867                  */
868                 if (relsec->sh_info >= pi->ehdr->e_shnum ||
869                     relsec->sh_link >= pi->ehdr->e_shnum)
870                         return -ENOEXEC;
871 
872                 section = pi->sechdrs + relsec->sh_info;
873                 symtab = sechdrs + relsec->sh_link;
874 
875                 if (!(section->sh_flags & SHF_ALLOC))
876                         continue;
877 
878                 /*
879                  * symtab->sh_link contain section header index of associated
880                  * string table.
881                  */
882                 if (symtab->sh_link >= pi->ehdr->e_shnum)
883                         /* Invalid section number? */
884                         continue;
885 
886                 /*
887                  * Respective architecture needs to provide support for applying
888                  * relocations of type SHT_RELA/SHT_REL.
889                  */
890                 if (relsec->sh_type == SHT_RELA)
891                         ret = arch_kexec_apply_relocations_add(pi, section,
892                                                                relsec, symtab);
893                 else if (relsec->sh_type == SHT_REL)
894                         ret = arch_kexec_apply_relocations(pi, section,
895                                                            relsec, symtab);
896                 if (ret)
897                         return ret;
898         }
899 
900         return 0;
901 }
902 
903 /*
904  * kexec_load_purgatory - Load and relocate the purgatory object.
905  * @image:      Image to add the purgatory to.
906  * @kbuf:       Memory parameters to use.
907  *
908  * Allocates the memory needed for image->purgatory_info.sechdrs and
909  * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
910  * to free the memory after use.
911  *
912  * Return: 0 on success, negative errno on error.
913  */
914 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
915 {
916         struct purgatory_info *pi = &image->purgatory_info;
917         int ret;
918 
919         if (kexec_purgatory_size <= 0)
920                 return -EINVAL;
921 
922         pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
923 
924         ret = kexec_purgatory_setup_kbuf(pi, kbuf);
925         if (ret)
926                 return ret;
927 
928         ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
929         if (ret)
930                 goto out_free_kbuf;
931 
932         ret = kexec_apply_relocations(image);
933         if (ret)
934                 goto out;
935 
936         return 0;
937 out:
938         vfree(pi->sechdrs);
939         pi->sechdrs = NULL;
940 out_free_kbuf:
941         vfree(pi->purgatory_buf);
942         pi->purgatory_buf = NULL;
943         return ret;
944 }
945 
946 /*
947  * kexec_purgatory_find_symbol - find a symbol in the purgatory
948  * @pi:         Purgatory to search in.
949  * @name:       Name of the symbol.
950  *
951  * Return: pointer to symbol in read-only symtab on success, NULL on error.
952  */
953 static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
954                                                   const char *name)
955 {
956         const Elf_Shdr *sechdrs;
957         const Elf_Ehdr *ehdr;
958         const Elf_Sym *syms;
959         const char *strtab;
960         int i, k;
961 
962         if (!pi->ehdr)
963                 return NULL;
964 
965         ehdr = pi->ehdr;
966         sechdrs = (void *)ehdr + ehdr->e_shoff;
967 
968         for (i = 0; i < ehdr->e_shnum; i++) {
969                 if (sechdrs[i].sh_type != SHT_SYMTAB)
970                         continue;
971 
972                 if (sechdrs[i].sh_link >= ehdr->e_shnum)
973                         /* Invalid strtab section number */
974                         continue;
975                 strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
976                 syms = (void *)ehdr + sechdrs[i].sh_offset;
977 
978                 /* Go through symbols for a match */
979                 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
980                         if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
981                                 continue;
982 
983                         if (strcmp(strtab + syms[k].st_name, name) != 0)
984                                 continue;
985 
986                         if (syms[k].st_shndx == SHN_UNDEF ||
987                             syms[k].st_shndx >= ehdr->e_shnum) {
988                                 pr_debug("Symbol: %s has bad section index %d.\n",
989                                                 name, syms[k].st_shndx);
990                                 return NULL;
991                         }
992 
993                         /* Found the symbol we are looking for */
994                         return &syms[k];
995                 }
996         }
997 
998         return NULL;
999 }
1000 
1001 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
1002 {
1003         struct purgatory_info *pi = &image->purgatory_info;
1004         const Elf_Sym *sym;
1005         Elf_Shdr *sechdr;
1006 
1007         sym = kexec_purgatory_find_symbol(pi, name);
1008         if (!sym)
1009                 return ERR_PTR(-EINVAL);
1010 
1011         sechdr = &pi->sechdrs[sym->st_shndx];
1012 
1013         /*
1014          * Returns the address where symbol will finally be loaded after
1015          * kexec_load_segment()
1016          */
1017         return (void *)(sechdr->sh_addr + sym->st_value);
1018 }
1019 
1020 /*
1021  * Get or set value of a symbol. If "get_value" is true, symbol value is
1022  * returned in buf otherwise symbol value is set based on value in buf.
1023  */
1024 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
1025                                    void *buf, unsigned int size, bool get_value)
1026 {
1027         struct purgatory_info *pi = &image->purgatory_info;
1028         const Elf_Sym *sym;
1029         Elf_Shdr *sec;
1030         char *sym_buf;
1031 
1032         sym = kexec_purgatory_find_symbol(pi, name);
1033         if (!sym)
1034                 return -EINVAL;
1035 
1036         if (sym->st_size != size) {
1037                 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1038                        name, (unsigned long)sym->st_size, size);
1039                 return -EINVAL;
1040         }
1041 
1042         sec = pi->sechdrs + sym->st_shndx;
1043 
1044         if (sec->sh_type == SHT_NOBITS) {
1045                 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1046                        get_value ? "get" : "set");
1047                 return -EINVAL;
1048         }
1049 
1050         sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
1051 
1052         if (get_value)
1053                 memcpy((void *)buf, sym_buf, size);
1054         else
1055                 memcpy((void *)sym_buf, buf, size);
1056 
1057         return 0;
1058 }
1059 #endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
1060 
1061 int crash_exclude_mem_range(struct crash_mem *mem,
1062                             unsigned long long mstart, unsigned long long mend)
1063 {
1064         int i, j;
1065         unsigned long long start, end;
1066         struct crash_mem_range temp_range = {0, 0};
1067 
1068         for (i = 0; i < mem->nr_ranges; i++) {
1069                 start = mem->ranges[i].start;
1070                 end = mem->ranges[i].end;
1071 
1072                 if (mstart > end || mend < start)
1073                         continue;
1074 
1075                 /* Truncate any area outside of range */
1076                 if (mstart < start)
1077                         mstart = start;
1078                 if (mend > end)
1079                         mend = end;
1080 
1081                 /* Found completely overlapping range */
1082                 if (mstart == start && mend == end) {
1083                         mem->ranges[i].start = 0;
1084                         mem->ranges[i].end = 0;
1085                         if (i < mem->nr_ranges - 1) {
1086                                 /* Shift rest of the ranges to left */
1087                                 for (j = i; j < mem->nr_ranges - 1; j++) {
1088                                         mem->ranges[j].start =
1089                                                 mem->ranges[j+1].start;
1090                                         mem->ranges[j].end =
1091                                                         mem->ranges[j+1].end;
1092                                 }
1093                         }
1094                         mem->nr_ranges--;
1095                         return 0;
1096                 }
1097 
1098                 if (mstart > start && mend < end) {
1099                         /* Split original range */
1100                         mem->ranges[i].end = mstart - 1;
1101                         temp_range.start = mend + 1;
1102                         temp_range.end = end;
1103                 } else if (mstart != start)
1104                         mem->ranges[i].end = mstart - 1;
1105                 else
1106                         mem->ranges[i].start = mend + 1;
1107                 break;
1108         }
1109 
1110         /* If a split happened, add the split to array */
1111         if (!temp_range.end)
1112                 return 0;
1113 
1114         /* Split happened */
1115         if (i == mem->max_nr_ranges - 1)
1116                 return -ENOMEM;
1117 
1118         /* Location where new range should go */
1119         j = i + 1;
1120         if (j < mem->nr_ranges) {
1121                 /* Move over all ranges one slot towards the end */
1122                 for (i = mem->nr_ranges - 1; i >= j; i--)
1123                         mem->ranges[i + 1] = mem->ranges[i];
1124         }
1125 
1126         mem->ranges[j].start = temp_range.start;
1127         mem->ranges[j].end = temp_range.end;
1128         mem->nr_ranges++;
1129         return 0;
1130 }
1131 
1132 int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
1133                           void **addr, unsigned long *sz)
1134 {
1135         Elf64_Ehdr *ehdr;
1136         Elf64_Phdr *phdr;
1137         unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
1138         unsigned char *buf;
1139         unsigned int cpu, i;
1140         unsigned long long notes_addr;
1141         unsigned long mstart, mend;
1142 
1143         /* extra phdr for vmcoreinfo elf note */
1144         nr_phdr = nr_cpus + 1;
1145         nr_phdr += mem->nr_ranges;
1146 
1147         /*
1148          * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
1149          * area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64).
1150          * I think this is required by tools like gdb. So same physical
1151          * memory will be mapped in two elf headers. One will contain kernel
1152          * text virtual addresses and other will have __va(physical) addresses.
1153          */
1154 
1155         nr_phdr++;
1156         elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
1157         elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
1158 
1159         buf = vzalloc(elf_sz);
1160         if (!buf)
1161                 return -ENOMEM;
1162 
1163         ehdr = (Elf64_Ehdr *)buf;
1164         phdr = (Elf64_Phdr *)(ehdr + 1);
1165         memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
1166         ehdr->e_ident[EI_CLASS] = ELFCLASS64;
1167         ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
1168         ehdr->e_ident[EI_VERSION] = EV_CURRENT;
1169         ehdr->e_ident[EI_OSABI] = ELF_OSABI;
1170         memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
1171         ehdr->e_type = ET_CORE;
1172         ehdr->e_machine = ELF_ARCH;
1173         ehdr->e_version = EV_CURRENT;
1174         ehdr->e_phoff = sizeof(Elf64_Ehdr);
1175         ehdr->e_ehsize = sizeof(Elf64_Ehdr);
1176         ehdr->e_phentsize = sizeof(Elf64_Phdr);
1177 
1178         /* Prepare one phdr of type PT_NOTE for each present cpu */
1179         for_each_present_cpu(cpu) {
1180                 phdr->p_type = PT_NOTE;
1181                 notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
1182                 phdr->p_offset = phdr->p_paddr = notes_addr;
1183                 phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
1184                 (ehdr->e_phnum)++;
1185                 phdr++;
1186         }
1187 
1188         /* Prepare one PT_NOTE header for vmcoreinfo */
1189         phdr->p_type = PT_NOTE;
1190         phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
1191         phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
1192         (ehdr->e_phnum)++;
1193         phdr++;
1194 
1195         /* Prepare PT_LOAD type program header for kernel text region */
1196         if (kernel_map) {
1197                 phdr->p_type = PT_LOAD;
1198                 phdr->p_flags = PF_R|PF_W|PF_X;
1199                 phdr->p_vaddr = (Elf64_Addr)_text;
1200                 phdr->p_filesz = phdr->p_memsz = _end - _text;
1201                 phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
1202                 ehdr->e_phnum++;
1203                 phdr++;
1204         }
1205 
1206         /* Go through all the ranges in mem->ranges[] and prepare phdr */
1207         for (i = 0; i < mem->nr_ranges; i++) {
1208                 mstart = mem->ranges[i].start;
1209                 mend = mem->ranges[i].end;
1210 
1211                 phdr->p_type = PT_LOAD;
1212                 phdr->p_flags = PF_R|PF_W|PF_X;
1213                 phdr->p_offset  = mstart;
1214 
1215                 phdr->p_paddr = mstart;
1216                 phdr->p_vaddr = (unsigned long long) __va(mstart);
1217                 phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
1218                 phdr->p_align = 0;
1219                 ehdr->e_phnum++;
1220                 phdr++;
1221                 pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
1222                         phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
1223                         ehdr->e_phnum, phdr->p_offset);
1224         }
1225 
1226         *addr = buf;
1227         *sz = elf_sz;
1228         return 0;
1229 }
1230 

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