Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/kernel/kexec_file.c

  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/syscalls.h>
 26 #include <linux/vmalloc.h>
 27 #include "kexec_internal.h"
 28 
 29 /*
 30  * Declare these symbols weak so that if architecture provides a purgatory,
 31  * these will be overridden.
 32  */
 33 char __weak kexec_purgatory[0];
 34 size_t __weak kexec_purgatory_size = 0;
 35 
 36 static int kexec_calculate_store_digests(struct kimage *image);
 37 
 38 /* Architectures can provide this probe function */
 39 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
 40                                          unsigned long buf_len)
 41 {
 42         return -ENOEXEC;
 43 }
 44 
 45 void * __weak arch_kexec_kernel_image_load(struct kimage *image)
 46 {
 47         return ERR_PTR(-ENOEXEC);
 48 }
 49 
 50 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
 51 {
 52         return -EINVAL;
 53 }
 54 
 55 #ifdef CONFIG_KEXEC_VERIFY_SIG
 56 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
 57                                         unsigned long buf_len)
 58 {
 59         return -EKEYREJECTED;
 60 }
 61 #endif
 62 
 63 /* Apply relocations of type RELA */
 64 int __weak
 65 arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 66                                  unsigned int relsec)
 67 {
 68         pr_err("RELA relocation unsupported.\n");
 69         return -ENOEXEC;
 70 }
 71 
 72 /* Apply relocations of type REL */
 73 int __weak
 74 arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 75                              unsigned int relsec)
 76 {
 77         pr_err("REL relocation unsupported.\n");
 78         return -ENOEXEC;
 79 }
 80 
 81 /*
 82  * Free up memory used by kernel, initrd, and command line. This is temporary
 83  * memory allocation which is not needed any more after these buffers have
 84  * been loaded into separate segments and have been copied elsewhere.
 85  */
 86 void kimage_file_post_load_cleanup(struct kimage *image)
 87 {
 88         struct purgatory_info *pi = &image->purgatory_info;
 89 
 90         vfree(image->kernel_buf);
 91         image->kernel_buf = NULL;
 92 
 93         vfree(image->initrd_buf);
 94         image->initrd_buf = NULL;
 95 
 96         kfree(image->cmdline_buf);
 97         image->cmdline_buf = NULL;
 98 
 99         vfree(pi->purgatory_buf);
100         pi->purgatory_buf = NULL;
101 
102         vfree(pi->sechdrs);
103         pi->sechdrs = NULL;
104 
105         /* See if architecture has anything to cleanup post load */
106         arch_kimage_file_post_load_cleanup(image);
107 
108         /*
109          * Above call should have called into bootloader to free up
110          * any data stored in kimage->image_loader_data. It should
111          * be ok now to free it up.
112          */
113         kfree(image->image_loader_data);
114         image->image_loader_data = NULL;
115 }
116 
117 /*
118  * In file mode list of segments is prepared by kernel. Copy relevant
119  * data from user space, do error checking, prepare segment list
120  */
121 static int
122 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
123                              const char __user *cmdline_ptr,
124                              unsigned long cmdline_len, unsigned flags)
125 {
126         int ret = 0;
127         void *ldata;
128         loff_t size;
129 
130         ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
131                                        &size, INT_MAX, READING_KEXEC_IMAGE);
132         if (ret)
133                 return ret;
134         image->kernel_buf_len = size;
135 
136         /* IMA needs to pass the measurement list to the next kernel. */
137         ima_add_kexec_buffer(image);
138 
139         /* Call arch image probe handlers */
140         ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
141                                             image->kernel_buf_len);
142         if (ret)
143                 goto out;
144 
145 #ifdef CONFIG_KEXEC_VERIFY_SIG
146         ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
147                                            image->kernel_buf_len);
148         if (ret) {
149                 pr_debug("kernel signature verification failed.\n");
150                 goto out;
151         }
152         pr_debug("kernel signature verification successful.\n");
153 #endif
154         /* It is possible that there no initramfs is being loaded */
155         if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
156                 ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
157                                                &size, INT_MAX,
158                                                READING_KEXEC_INITRAMFS);
159                 if (ret)
160                         goto out;
161                 image->initrd_buf_len = size;
162         }
163 
164         if (cmdline_len) {
165                 image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL);
166                 if (!image->cmdline_buf) {
167                         ret = -ENOMEM;
168                         goto out;
169                 }
170 
171                 ret = copy_from_user(image->cmdline_buf, cmdline_ptr,
172                                      cmdline_len);
173                 if (ret) {
174                         ret = -EFAULT;
175                         goto out;
176                 }
177 
178                 image->cmdline_buf_len = cmdline_len;
179 
180                 /* command line should be a string with last byte null */
181                 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
182                         ret = -EINVAL;
183                         goto out;
184                 }
185         }
186 
187         /* Call arch image load handlers */
188         ldata = arch_kexec_kernel_image_load(image);
189 
190         if (IS_ERR(ldata)) {
191                 ret = PTR_ERR(ldata);
192                 goto out;
193         }
194 
195         image->image_loader_data = ldata;
196 out:
197         /* In case of error, free up all allocated memory in this function */
198         if (ret)
199                 kimage_file_post_load_cleanup(image);
200         return ret;
201 }
202 
203 static int
204 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
205                        int initrd_fd, const char __user *cmdline_ptr,
206                        unsigned long cmdline_len, unsigned long flags)
207 {
208         int ret;
209         struct kimage *image;
210         bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
211 
212         image = do_kimage_alloc_init();
213         if (!image)
214                 return -ENOMEM;
215 
216         image->file_mode = 1;
217 
218         if (kexec_on_panic) {
219                 /* Enable special crash kernel control page alloc policy. */
220                 image->control_page = crashk_res.start;
221                 image->type = KEXEC_TYPE_CRASH;
222         }
223 
224         ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
225                                            cmdline_ptr, cmdline_len, flags);
226         if (ret)
227                 goto out_free_image;
228 
229         ret = sanity_check_segment_list(image);
230         if (ret)
231                 goto out_free_post_load_bufs;
232 
233         ret = -ENOMEM;
234         image->control_code_page = kimage_alloc_control_pages(image,
235                                            get_order(KEXEC_CONTROL_PAGE_SIZE));
236         if (!image->control_code_page) {
237                 pr_err("Could not allocate control_code_buffer\n");
238                 goto out_free_post_load_bufs;
239         }
240 
241         if (!kexec_on_panic) {
242                 image->swap_page = kimage_alloc_control_pages(image, 0);
243                 if (!image->swap_page) {
244                         pr_err("Could not allocate swap buffer\n");
245                         goto out_free_control_pages;
246                 }
247         }
248 
249         *rimage = image;
250         return 0;
251 out_free_control_pages:
252         kimage_free_page_list(&image->control_pages);
253 out_free_post_load_bufs:
254         kimage_file_post_load_cleanup(image);
255 out_free_image:
256         kfree(image);
257         return ret;
258 }
259 
260 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
261                 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
262                 unsigned long, flags)
263 {
264         int ret = 0, i;
265         struct kimage **dest_image, *image;
266 
267         /* We only trust the superuser with rebooting the system. */
268         if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
269                 return -EPERM;
270 
271         /* Make sure we have a legal set of flags */
272         if (flags != (flags & KEXEC_FILE_FLAGS))
273                 return -EINVAL;
274 
275         image = NULL;
276 
277         if (!mutex_trylock(&kexec_mutex))
278                 return -EBUSY;
279 
280         dest_image = &kexec_image;
281         if (flags & KEXEC_FILE_ON_CRASH) {
282                 dest_image = &kexec_crash_image;
283                 if (kexec_crash_image)
284                         arch_kexec_unprotect_crashkres();
285         }
286 
287         if (flags & KEXEC_FILE_UNLOAD)
288                 goto exchange;
289 
290         /*
291          * In case of crash, new kernel gets loaded in reserved region. It is
292          * same memory where old crash kernel might be loaded. Free any
293          * current crash dump kernel before we corrupt it.
294          */
295         if (flags & KEXEC_FILE_ON_CRASH)
296                 kimage_free(xchg(&kexec_crash_image, NULL));
297 
298         ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
299                                      cmdline_len, flags);
300         if (ret)
301                 goto out;
302 
303         ret = machine_kexec_prepare(image);
304         if (ret)
305                 goto out;
306 
307         ret = kexec_calculate_store_digests(image);
308         if (ret)
309                 goto out;
310 
311         for (i = 0; i < image->nr_segments; i++) {
312                 struct kexec_segment *ksegment;
313 
314                 ksegment = &image->segment[i];
315                 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
316                          i, ksegment->buf, ksegment->bufsz, ksegment->mem,
317                          ksegment->memsz);
318 
319                 ret = kimage_load_segment(image, &image->segment[i]);
320                 if (ret)
321                         goto out;
322         }
323 
324         kimage_terminate(image);
325 
326         /*
327          * Free up any temporary buffers allocated which are not needed
328          * after image has been loaded
329          */
330         kimage_file_post_load_cleanup(image);
331 exchange:
332         image = xchg(dest_image, image);
333 out:
334         if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
335                 arch_kexec_protect_crashkres();
336 
337         mutex_unlock(&kexec_mutex);
338         kimage_free(image);
339         return ret;
340 }
341 
342 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
343                                     struct kexec_buf *kbuf)
344 {
345         struct kimage *image = kbuf->image;
346         unsigned long temp_start, temp_end;
347 
348         temp_end = min(end, kbuf->buf_max);
349         temp_start = temp_end - kbuf->memsz;
350 
351         do {
352                 /* align down start */
353                 temp_start = temp_start & (~(kbuf->buf_align - 1));
354 
355                 if (temp_start < start || temp_start < kbuf->buf_min)
356                         return 0;
357 
358                 temp_end = temp_start + kbuf->memsz - 1;
359 
360                 /*
361                  * Make sure this does not conflict with any of existing
362                  * segments
363                  */
364                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
365                         temp_start = temp_start - PAGE_SIZE;
366                         continue;
367                 }
368 
369                 /* We found a suitable memory range */
370                 break;
371         } while (1);
372 
373         /* If we are here, we found a suitable memory range */
374         kbuf->mem = temp_start;
375 
376         /* Success, stop navigating through remaining System RAM ranges */
377         return 1;
378 }
379 
380 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
381                                      struct kexec_buf *kbuf)
382 {
383         struct kimage *image = kbuf->image;
384         unsigned long temp_start, temp_end;
385 
386         temp_start = max(start, kbuf->buf_min);
387 
388         do {
389                 temp_start = ALIGN(temp_start, kbuf->buf_align);
390                 temp_end = temp_start + kbuf->memsz - 1;
391 
392                 if (temp_end > end || temp_end > kbuf->buf_max)
393                         return 0;
394                 /*
395                  * Make sure this does not conflict with any of existing
396                  * segments
397                  */
398                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
399                         temp_start = temp_start + PAGE_SIZE;
400                         continue;
401                 }
402 
403                 /* We found a suitable memory range */
404                 break;
405         } while (1);
406 
407         /* If we are here, we found a suitable memory range */
408         kbuf->mem = temp_start;
409 
410         /* Success, stop navigating through remaining System RAM ranges */
411         return 1;
412 }
413 
414 static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
415 {
416         struct kexec_buf *kbuf = (struct kexec_buf *)arg;
417         unsigned long sz = end - start + 1;
418 
419         /* Returning 0 will take to next memory range */
420         if (sz < kbuf->memsz)
421                 return 0;
422 
423         if (end < kbuf->buf_min || start > kbuf->buf_max)
424                 return 0;
425 
426         /*
427          * Allocate memory top down with-in ram range. Otherwise bottom up
428          * allocation.
429          */
430         if (kbuf->top_down)
431                 return locate_mem_hole_top_down(start, end, kbuf);
432         return locate_mem_hole_bottom_up(start, end, kbuf);
433 }
434 
435 /**
436  * arch_kexec_walk_mem - call func(data) on free memory regions
437  * @kbuf:       Context info for the search. Also passed to @func.
438  * @func:       Function to call for each memory region.
439  *
440  * Return: The memory walk will stop when func returns a non-zero value
441  * and that value will be returned. If all free regions are visited without
442  * func returning non-zero, then zero will be returned.
443  */
444 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
445                                int (*func)(u64, u64, void *))
446 {
447         if (kbuf->image->type == KEXEC_TYPE_CRASH)
448                 return walk_iomem_res_desc(crashk_res.desc,
449                                            IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
450                                            crashk_res.start, crashk_res.end,
451                                            kbuf, func);
452         else
453                 return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
454 }
455 
456 /**
457  * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
458  * @kbuf:       Parameters for the memory search.
459  *
460  * On success, kbuf->mem will have the start address of the memory region found.
461  *
462  * Return: 0 on success, negative errno on error.
463  */
464 int kexec_locate_mem_hole(struct kexec_buf *kbuf)
465 {
466         int ret;
467 
468         ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
469 
470         return ret == 1 ? 0 : -EADDRNOTAVAIL;
471 }
472 
473 /**
474  * kexec_add_buffer - place a buffer in a kexec segment
475  * @kbuf:       Buffer contents and memory parameters.
476  *
477  * This function assumes that kexec_mutex is held.
478  * On successful return, @kbuf->mem will have the physical address of
479  * the buffer in memory.
480  *
481  * Return: 0 on success, negative errno on error.
482  */
483 int kexec_add_buffer(struct kexec_buf *kbuf)
484 {
485 
486         struct kexec_segment *ksegment;
487         int ret;
488 
489         /* Currently adding segment this way is allowed only in file mode */
490         if (!kbuf->image->file_mode)
491                 return -EINVAL;
492 
493         if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
494                 return -EINVAL;
495 
496         /*
497          * Make sure we are not trying to add buffer after allocating
498          * control pages. All segments need to be placed first before
499          * any control pages are allocated. As control page allocation
500          * logic goes through list of segments to make sure there are
501          * no destination overlaps.
502          */
503         if (!list_empty(&kbuf->image->control_pages)) {
504                 WARN_ON(1);
505                 return -EINVAL;
506         }
507 
508         /* Ensure minimum alignment needed for segments. */
509         kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
510         kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
511 
512         /* Walk the RAM ranges and allocate a suitable range for the buffer */
513         ret = kexec_locate_mem_hole(kbuf);
514         if (ret)
515                 return ret;
516 
517         /* Found a suitable memory range */
518         ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
519         ksegment->kbuf = kbuf->buffer;
520         ksegment->bufsz = kbuf->bufsz;
521         ksegment->mem = kbuf->mem;
522         ksegment->memsz = kbuf->memsz;
523         kbuf->image->nr_segments++;
524         return 0;
525 }
526 
527 /* Calculate and store the digest of segments */
528 static int kexec_calculate_store_digests(struct kimage *image)
529 {
530         struct crypto_shash *tfm;
531         struct shash_desc *desc;
532         int ret = 0, i, j, zero_buf_sz, sha_region_sz;
533         size_t desc_size, nullsz;
534         char *digest;
535         void *zero_buf;
536         struct kexec_sha_region *sha_regions;
537         struct purgatory_info *pi = &image->purgatory_info;
538 
539         zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
540         zero_buf_sz = PAGE_SIZE;
541 
542         tfm = crypto_alloc_shash("sha256", 0, 0);
543         if (IS_ERR(tfm)) {
544                 ret = PTR_ERR(tfm);
545                 goto out;
546         }
547 
548         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
549         desc = kzalloc(desc_size, GFP_KERNEL);
550         if (!desc) {
551                 ret = -ENOMEM;
552                 goto out_free_tfm;
553         }
554 
555         sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
556         sha_regions = vzalloc(sha_region_sz);
557         if (!sha_regions)
558                 goto out_free_desc;
559 
560         desc->tfm   = tfm;
561         desc->flags = 0;
562 
563         ret = crypto_shash_init(desc);
564         if (ret < 0)
565                 goto out_free_sha_regions;
566 
567         digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
568         if (!digest) {
569                 ret = -ENOMEM;
570                 goto out_free_sha_regions;
571         }
572 
573         for (j = i = 0; i < image->nr_segments; i++) {
574                 struct kexec_segment *ksegment;
575 
576                 ksegment = &image->segment[i];
577                 /*
578                  * Skip purgatory as it will be modified once we put digest
579                  * info in purgatory.
580                  */
581                 if (ksegment->kbuf == pi->purgatory_buf)
582                         continue;
583 
584                 ret = crypto_shash_update(desc, ksegment->kbuf,
585                                           ksegment->bufsz);
586                 if (ret)
587                         break;
588 
589                 /*
590                  * Assume rest of the buffer is filled with zero and
591                  * update digest accordingly.
592                  */
593                 nullsz = ksegment->memsz - ksegment->bufsz;
594                 while (nullsz) {
595                         unsigned long bytes = nullsz;
596 
597                         if (bytes > zero_buf_sz)
598                                 bytes = zero_buf_sz;
599                         ret = crypto_shash_update(desc, zero_buf, bytes);
600                         if (ret)
601                                 break;
602                         nullsz -= bytes;
603                 }
604 
605                 if (ret)
606                         break;
607 
608                 sha_regions[j].start = ksegment->mem;
609                 sha_regions[j].len = ksegment->memsz;
610                 j++;
611         }
612 
613         if (!ret) {
614                 ret = crypto_shash_final(desc, digest);
615                 if (ret)
616                         goto out_free_digest;
617                 ret = kexec_purgatory_get_set_symbol(image, "sha_regions",
618                                                 sha_regions, sha_region_sz, 0);
619                 if (ret)
620                         goto out_free_digest;
621 
622                 ret = kexec_purgatory_get_set_symbol(image, "sha256_digest",
623                                                 digest, SHA256_DIGEST_SIZE, 0);
624                 if (ret)
625                         goto out_free_digest;
626         }
627 
628 out_free_digest:
629         kfree(digest);
630 out_free_sha_regions:
631         vfree(sha_regions);
632 out_free_desc:
633         kfree(desc);
634 out_free_tfm:
635         kfree(tfm);
636 out:
637         return ret;
638 }
639 
640 /* Actually load purgatory. Lot of code taken from kexec-tools */
641 static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
642                                   unsigned long max, int top_down)
643 {
644         struct purgatory_info *pi = &image->purgatory_info;
645         unsigned long align, bss_align, bss_sz, bss_pad;
646         unsigned long entry, load_addr, curr_load_addr, bss_addr, offset;
647         unsigned char *buf_addr, *src;
648         int i, ret = 0, entry_sidx = -1;
649         const Elf_Shdr *sechdrs_c;
650         Elf_Shdr *sechdrs = NULL;
651         struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1,
652                                   .buf_min = min, .buf_max = max,
653                                   .top_down = top_down };
654 
655         /*
656          * sechdrs_c points to section headers in purgatory and are read
657          * only. No modifications allowed.
658          */
659         sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
660 
661         /*
662          * We can not modify sechdrs_c[] and its fields. It is read only.
663          * Copy it over to a local copy where one can store some temporary
664          * data and free it at the end. We need to modify ->sh_addr and
665          * ->sh_offset fields to keep track of permanent and temporary
666          * locations of sections.
667          */
668         sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
669         if (!sechdrs)
670                 return -ENOMEM;
671 
672         memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
673 
674         /*
675          * We seem to have multiple copies of sections. First copy is which
676          * is embedded in kernel in read only section. Some of these sections
677          * will be copied to a temporary buffer and relocated. And these
678          * sections will finally be copied to their final destination at
679          * segment load time.
680          *
681          * Use ->sh_offset to reflect section address in memory. It will
682          * point to original read only copy if section is not allocatable.
683          * Otherwise it will point to temporary copy which will be relocated.
684          *
685          * Use ->sh_addr to contain final address of the section where it
686          * will go during execution time.
687          */
688         for (i = 0; i < pi->ehdr->e_shnum; i++) {
689                 if (sechdrs[i].sh_type == SHT_NOBITS)
690                         continue;
691 
692                 sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
693                                                 sechdrs[i].sh_offset;
694         }
695 
696         /*
697          * Identify entry point section and make entry relative to section
698          * start.
699          */
700         entry = pi->ehdr->e_entry;
701         for (i = 0; i < pi->ehdr->e_shnum; i++) {
702                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
703                         continue;
704 
705                 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
706                         continue;
707 
708                 /* Make entry section relative */
709                 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
710                     ((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
711                      pi->ehdr->e_entry)) {
712                         entry_sidx = i;
713                         entry -= sechdrs[i].sh_addr;
714                         break;
715                 }
716         }
717 
718         /* Determine how much memory is needed to load relocatable object. */
719         bss_align = 1;
720         bss_sz = 0;
721 
722         for (i = 0; i < pi->ehdr->e_shnum; i++) {
723                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
724                         continue;
725 
726                 align = sechdrs[i].sh_addralign;
727                 if (sechdrs[i].sh_type != SHT_NOBITS) {
728                         if (kbuf.buf_align < align)
729                                 kbuf.buf_align = align;
730                         kbuf.bufsz = ALIGN(kbuf.bufsz, align);
731                         kbuf.bufsz += sechdrs[i].sh_size;
732                 } else {
733                         /* bss section */
734                         if (bss_align < align)
735                                 bss_align = align;
736                         bss_sz = ALIGN(bss_sz, align);
737                         bss_sz += sechdrs[i].sh_size;
738                 }
739         }
740 
741         /* Determine the bss padding required to align bss properly */
742         bss_pad = 0;
743         if (kbuf.bufsz & (bss_align - 1))
744                 bss_pad = bss_align - (kbuf.bufsz & (bss_align - 1));
745 
746         kbuf.memsz = kbuf.bufsz + bss_pad + bss_sz;
747 
748         /* Allocate buffer for purgatory */
749         kbuf.buffer = vzalloc(kbuf.bufsz);
750         if (!kbuf.buffer) {
751                 ret = -ENOMEM;
752                 goto out;
753         }
754 
755         if (kbuf.buf_align < bss_align)
756                 kbuf.buf_align = bss_align;
757 
758         /* Add buffer to segment list */
759         ret = kexec_add_buffer(&kbuf);
760         if (ret)
761                 goto out;
762         pi->purgatory_load_addr = kbuf.mem;
763 
764         /* Load SHF_ALLOC sections */
765         buf_addr = kbuf.buffer;
766         load_addr = curr_load_addr = pi->purgatory_load_addr;
767         bss_addr = load_addr + kbuf.bufsz + bss_pad;
768 
769         for (i = 0; i < pi->ehdr->e_shnum; i++) {
770                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
771                         continue;
772 
773                 align = sechdrs[i].sh_addralign;
774                 if (sechdrs[i].sh_type != SHT_NOBITS) {
775                         curr_load_addr = ALIGN(curr_load_addr, align);
776                         offset = curr_load_addr - load_addr;
777                         /* We already modifed ->sh_offset to keep src addr */
778                         src = (char *) sechdrs[i].sh_offset;
779                         memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
780 
781                         /* Store load address and source address of section */
782                         sechdrs[i].sh_addr = curr_load_addr;
783 
784                         /*
785                          * This section got copied to temporary buffer. Update
786                          * ->sh_offset accordingly.
787                          */
788                         sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
789 
790                         /* Advance to the next address */
791                         curr_load_addr += sechdrs[i].sh_size;
792                 } else {
793                         bss_addr = ALIGN(bss_addr, align);
794                         sechdrs[i].sh_addr = bss_addr;
795                         bss_addr += sechdrs[i].sh_size;
796                 }
797         }
798 
799         /* Update entry point based on load address of text section */
800         if (entry_sidx >= 0)
801                 entry += sechdrs[entry_sidx].sh_addr;
802 
803         /* Make kernel jump to purgatory after shutdown */
804         image->start = entry;
805 
806         /* Used later to get/set symbol values */
807         pi->sechdrs = sechdrs;
808 
809         /*
810          * Used later to identify which section is purgatory and skip it
811          * from checksumming.
812          */
813         pi->purgatory_buf = kbuf.buffer;
814         return ret;
815 out:
816         vfree(sechdrs);
817         vfree(kbuf.buffer);
818         return ret;
819 }
820 
821 static int kexec_apply_relocations(struct kimage *image)
822 {
823         int i, ret;
824         struct purgatory_info *pi = &image->purgatory_info;
825         Elf_Shdr *sechdrs = pi->sechdrs;
826 
827         /* Apply relocations */
828         for (i = 0; i < pi->ehdr->e_shnum; i++) {
829                 Elf_Shdr *section, *symtab;
830 
831                 if (sechdrs[i].sh_type != SHT_RELA &&
832                     sechdrs[i].sh_type != SHT_REL)
833                         continue;
834 
835                 /*
836                  * For section of type SHT_RELA/SHT_REL,
837                  * ->sh_link contains section header index of associated
838                  * symbol table. And ->sh_info contains section header
839                  * index of section to which relocations apply.
840                  */
841                 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
842                     sechdrs[i].sh_link >= pi->ehdr->e_shnum)
843                         return -ENOEXEC;
844 
845                 section = &sechdrs[sechdrs[i].sh_info];
846                 symtab = &sechdrs[sechdrs[i].sh_link];
847 
848                 if (!(section->sh_flags & SHF_ALLOC))
849                         continue;
850 
851                 /*
852                  * symtab->sh_link contain section header index of associated
853                  * string table.
854                  */
855                 if (symtab->sh_link >= pi->ehdr->e_shnum)
856                         /* Invalid section number? */
857                         continue;
858 
859                 /*
860                  * Respective architecture needs to provide support for applying
861                  * relocations of type SHT_RELA/SHT_REL.
862                  */
863                 if (sechdrs[i].sh_type == SHT_RELA)
864                         ret = arch_kexec_apply_relocations_add(pi->ehdr,
865                                                                sechdrs, i);
866                 else if (sechdrs[i].sh_type == SHT_REL)
867                         ret = arch_kexec_apply_relocations(pi->ehdr,
868                                                            sechdrs, i);
869                 if (ret)
870                         return ret;
871         }
872 
873         return 0;
874 }
875 
876 /* Load relocatable purgatory object and relocate it appropriately */
877 int kexec_load_purgatory(struct kimage *image, unsigned long min,
878                          unsigned long max, int top_down,
879                          unsigned long *load_addr)
880 {
881         struct purgatory_info *pi = &image->purgatory_info;
882         int ret;
883 
884         if (kexec_purgatory_size <= 0)
885                 return -EINVAL;
886 
887         if (kexec_purgatory_size < sizeof(Elf_Ehdr))
888                 return -ENOEXEC;
889 
890         pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
891 
892         if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
893             || pi->ehdr->e_type != ET_REL
894             || !elf_check_arch(pi->ehdr)
895             || pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
896                 return -ENOEXEC;
897 
898         if (pi->ehdr->e_shoff >= kexec_purgatory_size
899             || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
900             kexec_purgatory_size - pi->ehdr->e_shoff))
901                 return -ENOEXEC;
902 
903         ret = __kexec_load_purgatory(image, min, max, top_down);
904         if (ret)
905                 return ret;
906 
907         ret = kexec_apply_relocations(image);
908         if (ret)
909                 goto out;
910 
911         *load_addr = pi->purgatory_load_addr;
912         return 0;
913 out:
914         vfree(pi->sechdrs);
915         pi->sechdrs = NULL;
916 
917         vfree(pi->purgatory_buf);
918         pi->purgatory_buf = NULL;
919         return ret;
920 }
921 
922 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
923                                             const char *name)
924 {
925         Elf_Sym *syms;
926         Elf_Shdr *sechdrs;
927         Elf_Ehdr *ehdr;
928         int i, k;
929         const char *strtab;
930 
931         if (!pi->sechdrs || !pi->ehdr)
932                 return NULL;
933 
934         sechdrs = pi->sechdrs;
935         ehdr = pi->ehdr;
936 
937         for (i = 0; i < ehdr->e_shnum; i++) {
938                 if (sechdrs[i].sh_type != SHT_SYMTAB)
939                         continue;
940 
941                 if (sechdrs[i].sh_link >= ehdr->e_shnum)
942                         /* Invalid strtab section number */
943                         continue;
944                 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
945                 syms = (Elf_Sym *)sechdrs[i].sh_offset;
946 
947                 /* Go through symbols for a match */
948                 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
949                         if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
950                                 continue;
951 
952                         if (strcmp(strtab + syms[k].st_name, name) != 0)
953                                 continue;
954 
955                         if (syms[k].st_shndx == SHN_UNDEF ||
956                             syms[k].st_shndx >= ehdr->e_shnum) {
957                                 pr_debug("Symbol: %s has bad section index %d.\n",
958                                                 name, syms[k].st_shndx);
959                                 return NULL;
960                         }
961 
962                         /* Found the symbol we are looking for */
963                         return &syms[k];
964                 }
965         }
966 
967         return NULL;
968 }
969 
970 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
971 {
972         struct purgatory_info *pi = &image->purgatory_info;
973         Elf_Sym *sym;
974         Elf_Shdr *sechdr;
975 
976         sym = kexec_purgatory_find_symbol(pi, name);
977         if (!sym)
978                 return ERR_PTR(-EINVAL);
979 
980         sechdr = &pi->sechdrs[sym->st_shndx];
981 
982         /*
983          * Returns the address where symbol will finally be loaded after
984          * kexec_load_segment()
985          */
986         return (void *)(sechdr->sh_addr + sym->st_value);
987 }
988 
989 /*
990  * Get or set value of a symbol. If "get_value" is true, symbol value is
991  * returned in buf otherwise symbol value is set based on value in buf.
992  */
993 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
994                                    void *buf, unsigned int size, bool get_value)
995 {
996         Elf_Sym *sym;
997         Elf_Shdr *sechdrs;
998         struct purgatory_info *pi = &image->purgatory_info;
999         char *sym_buf;
1000 
1001         sym = kexec_purgatory_find_symbol(pi, name);
1002         if (!sym)
1003                 return -EINVAL;
1004 
1005         if (sym->st_size != size) {
1006                 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1007                        name, (unsigned long)sym->st_size, size);
1008                 return -EINVAL;
1009         }
1010 
1011         sechdrs = pi->sechdrs;
1012 
1013         if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
1014                 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1015                        get_value ? "get" : "set");
1016                 return -EINVAL;
1017         }
1018 
1019         sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
1020                                         sym->st_value;
1021 
1022         if (get_value)
1023                 memcpy((void *)buf, sym_buf, size);
1024         else
1025                 memcpy((void *)sym_buf, buf, size);
1026 
1027         return 0;
1028 }
1029 

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