xref: /openbmc/linux/kernel/kexec_file.c (revision c318a4bb)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * kexec: kexec_file_load system call
4  *
5  * Copyright (C) 2014 Red Hat Inc.
6  * Authors:
7  *      Vivek Goyal <vgoyal@redhat.com>
8  */
9 
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 
12 #include <linux/capability.h>
13 #include <linux/mm.h>
14 #include <linux/file.h>
15 #include <linux/slab.h>
16 #include <linux/kexec.h>
17 #include <linux/memblock.h>
18 #include <linux/mutex.h>
19 #include <linux/list.h>
20 #include <linux/fs.h>
21 #include <linux/ima.h>
22 #include <crypto/hash.h>
23 #include <crypto/sha2.h>
24 #include <linux/elf.h>
25 #include <linux/elfcore.h>
26 #include <linux/kernel.h>
27 #include <linux/kernel_read_file.h>
28 #include <linux/syscalls.h>
29 #include <linux/vmalloc.h>
30 #include "kexec_internal.h"
31 
32 #ifdef CONFIG_KEXEC_SIG
33 static bool sig_enforce = IS_ENABLED(CONFIG_KEXEC_SIG_FORCE);
34 
set_kexec_sig_enforced(void)35 void set_kexec_sig_enforced(void)
36 {
37 	sig_enforce = true;
38 }
39 #endif
40 
41 static int kexec_calculate_store_digests(struct kimage *image);
42 
43 /* Maximum size in bytes for kernel/initrd files. */
44 #define KEXEC_FILE_SIZE_MAX	min_t(s64, 4LL << 30, SSIZE_MAX)
45 
46 /*
47  * Currently this is the only default function that is exported as some
48  * architectures need it to do additional handlings.
49  * In the future, other default functions may be exported too if required.
50  */
kexec_image_probe_default(struct kimage * image,void * buf,unsigned long buf_len)51 int kexec_image_probe_default(struct kimage *image, void *buf,
52 			      unsigned long buf_len)
53 {
54 	const struct kexec_file_ops * const *fops;
55 	int ret = -ENOEXEC;
56 
57 	for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
58 		ret = (*fops)->probe(buf, buf_len);
59 		if (!ret) {
60 			image->fops = *fops;
61 			return ret;
62 		}
63 	}
64 
65 	return ret;
66 }
67 
kexec_image_load_default(struct kimage * image)68 static void *kexec_image_load_default(struct kimage *image)
69 {
70 	if (!image->fops || !image->fops->load)
71 		return ERR_PTR(-ENOEXEC);
72 
73 	return image->fops->load(image, image->kernel_buf,
74 				 image->kernel_buf_len, image->initrd_buf,
75 				 image->initrd_buf_len, image->cmdline_buf,
76 				 image->cmdline_buf_len);
77 }
78 
kexec_image_post_load_cleanup_default(struct kimage * image)79 int kexec_image_post_load_cleanup_default(struct kimage *image)
80 {
81 	if (!image->fops || !image->fops->cleanup)
82 		return 0;
83 
84 	return image->fops->cleanup(image->image_loader_data);
85 }
86 
87 /*
88  * Free up memory used by kernel, initrd, and command line. This is temporary
89  * memory allocation which is not needed any more after these buffers have
90  * been loaded into separate segments and have been copied elsewhere.
91  */
kimage_file_post_load_cleanup(struct kimage * image)92 void kimage_file_post_load_cleanup(struct kimage *image)
93 {
94 	struct purgatory_info *pi = &image->purgatory_info;
95 
96 	vfree(image->kernel_buf);
97 	image->kernel_buf = NULL;
98 
99 	vfree(image->initrd_buf);
100 	image->initrd_buf = NULL;
101 
102 	kfree(image->cmdline_buf);
103 	image->cmdline_buf = NULL;
104 
105 	vfree(pi->purgatory_buf);
106 	pi->purgatory_buf = NULL;
107 
108 	vfree(pi->sechdrs);
109 	pi->sechdrs = NULL;
110 
111 #ifdef CONFIG_IMA_KEXEC
112 	vfree(image->ima_buffer);
113 	image->ima_buffer = NULL;
114 #endif /* CONFIG_IMA_KEXEC */
115 
116 	/* See if architecture has anything to cleanup post load */
117 	arch_kimage_file_post_load_cleanup(image);
118 
119 	/*
120 	 * Above call should have called into bootloader to free up
121 	 * any data stored in kimage->image_loader_data. It should
122 	 * be ok now to free it up.
123 	 */
124 	kfree(image->image_loader_data);
125 	image->image_loader_data = NULL;
126 }
127 
128 #ifdef CONFIG_KEXEC_SIG
129 #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
kexec_kernel_verify_pe_sig(const char * kernel,unsigned long kernel_len)130 int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
131 {
132 	int ret;
133 
134 	ret = verify_pefile_signature(kernel, kernel_len,
135 				      VERIFY_USE_SECONDARY_KEYRING,
136 				      VERIFYING_KEXEC_PE_SIGNATURE);
137 	if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
138 		ret = verify_pefile_signature(kernel, kernel_len,
139 					      VERIFY_USE_PLATFORM_KEYRING,
140 					      VERIFYING_KEXEC_PE_SIGNATURE);
141 	}
142 	return ret;
143 }
144 #endif
145 
kexec_image_verify_sig(struct kimage * image,void * buf,unsigned long buf_len)146 static int kexec_image_verify_sig(struct kimage *image, void *buf,
147 				  unsigned long buf_len)
148 {
149 	if (!image->fops || !image->fops->verify_sig) {
150 		pr_debug("kernel loader does not support signature verification.\n");
151 		return -EKEYREJECTED;
152 	}
153 
154 	return image->fops->verify_sig(buf, buf_len);
155 }
156 
157 static int
kimage_validate_signature(struct kimage * image)158 kimage_validate_signature(struct kimage *image)
159 {
160 	int ret;
161 
162 	ret = kexec_image_verify_sig(image, image->kernel_buf,
163 				     image->kernel_buf_len);
164 	if (ret) {
165 
166 		if (sig_enforce) {
167 			pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
168 			return ret;
169 		}
170 
171 		/*
172 		 * If IMA is guaranteed to appraise a signature on the kexec
173 		 * image, permit it even if the kernel is otherwise locked
174 		 * down.
175 		 */
176 		if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
177 		    security_locked_down(LOCKDOWN_KEXEC))
178 			return -EPERM;
179 
180 		pr_debug("kernel signature verification failed (%d).\n", ret);
181 	}
182 
183 	return 0;
184 }
185 #endif
186 
187 /*
188  * In file mode list of segments is prepared by kernel. Copy relevant
189  * data from user space, do error checking, prepare segment list
190  */
191 static int
kimage_file_prepare_segments(struct kimage * image,int kernel_fd,int initrd_fd,const char __user * cmdline_ptr,unsigned long cmdline_len,unsigned flags)192 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
193 			     const char __user *cmdline_ptr,
194 			     unsigned long cmdline_len, unsigned flags)
195 {
196 	ssize_t ret;
197 	void *ldata;
198 
199 	ret = kernel_read_file_from_fd(kernel_fd, 0, &image->kernel_buf,
200 				       KEXEC_FILE_SIZE_MAX, NULL,
201 				       READING_KEXEC_IMAGE);
202 	if (ret < 0)
203 		return ret;
204 	image->kernel_buf_len = ret;
205 
206 	/* Call arch image probe handlers */
207 	ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
208 					    image->kernel_buf_len);
209 	if (ret)
210 		goto out;
211 
212 #ifdef CONFIG_KEXEC_SIG
213 	ret = kimage_validate_signature(image);
214 
215 	if (ret)
216 		goto out;
217 #endif
218 	/* It is possible that there no initramfs is being loaded */
219 	if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
220 		ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf,
221 					       KEXEC_FILE_SIZE_MAX, NULL,
222 					       READING_KEXEC_INITRAMFS);
223 		if (ret < 0)
224 			goto out;
225 		image->initrd_buf_len = ret;
226 		ret = 0;
227 	}
228 
229 	if (cmdline_len) {
230 		image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
231 		if (IS_ERR(image->cmdline_buf)) {
232 			ret = PTR_ERR(image->cmdline_buf);
233 			image->cmdline_buf = NULL;
234 			goto out;
235 		}
236 
237 		image->cmdline_buf_len = cmdline_len;
238 
239 		/* command line should be a string with last byte null */
240 		if (image->cmdline_buf[cmdline_len - 1] != '\0') {
241 			ret = -EINVAL;
242 			goto out;
243 		}
244 
245 		ima_kexec_cmdline(kernel_fd, image->cmdline_buf,
246 				  image->cmdline_buf_len - 1);
247 	}
248 
249 	/* IMA needs to pass the measurement list to the next kernel. */
250 	ima_add_kexec_buffer(image);
251 
252 	/* Call image load handler */
253 	ldata = kexec_image_load_default(image);
254 
255 	if (IS_ERR(ldata)) {
256 		ret = PTR_ERR(ldata);
257 		goto out;
258 	}
259 
260 	image->image_loader_data = ldata;
261 out:
262 	/* In case of error, free up all allocated memory in this function */
263 	if (ret)
264 		kimage_file_post_load_cleanup(image);
265 	return ret;
266 }
267 
268 static int
kimage_file_alloc_init(struct kimage ** rimage,int kernel_fd,int initrd_fd,const char __user * cmdline_ptr,unsigned long cmdline_len,unsigned long flags)269 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
270 		       int initrd_fd, const char __user *cmdline_ptr,
271 		       unsigned long cmdline_len, unsigned long flags)
272 {
273 	int ret;
274 	struct kimage *image;
275 	bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
276 
277 	image = do_kimage_alloc_init();
278 	if (!image)
279 		return -ENOMEM;
280 
281 	image->file_mode = 1;
282 
283 	if (kexec_on_panic) {
284 		/* Enable special crash kernel control page alloc policy. */
285 		image->control_page = crashk_res.start;
286 		image->type = KEXEC_TYPE_CRASH;
287 	}
288 
289 	ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
290 					   cmdline_ptr, cmdline_len, flags);
291 	if (ret)
292 		goto out_free_image;
293 
294 	ret = sanity_check_segment_list(image);
295 	if (ret)
296 		goto out_free_post_load_bufs;
297 
298 	ret = -ENOMEM;
299 	image->control_code_page = kimage_alloc_control_pages(image,
300 					   get_order(KEXEC_CONTROL_PAGE_SIZE));
301 	if (!image->control_code_page) {
302 		pr_err("Could not allocate control_code_buffer\n");
303 		goto out_free_post_load_bufs;
304 	}
305 
306 	if (!kexec_on_panic) {
307 		image->swap_page = kimage_alloc_control_pages(image, 0);
308 		if (!image->swap_page) {
309 			pr_err("Could not allocate swap buffer\n");
310 			goto out_free_control_pages;
311 		}
312 	}
313 
314 	*rimage = image;
315 	return 0;
316 out_free_control_pages:
317 	kimage_free_page_list(&image->control_pages);
318 out_free_post_load_bufs:
319 	kimage_file_post_load_cleanup(image);
320 out_free_image:
321 	kfree(image);
322 	return ret;
323 }
324 
SYSCALL_DEFINE5(kexec_file_load,int,kernel_fd,int,initrd_fd,unsigned long,cmdline_len,const char __user *,cmdline_ptr,unsigned long,flags)325 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
326 		unsigned long, cmdline_len, const char __user *, cmdline_ptr,
327 		unsigned long, flags)
328 {
329 	int image_type = (flags & KEXEC_FILE_ON_CRASH) ?
330 			 KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
331 	struct kimage **dest_image, *image;
332 	int ret = 0, i;
333 
334 	/* We only trust the superuser with rebooting the system. */
335 	if (!kexec_load_permitted(image_type))
336 		return -EPERM;
337 
338 	/* Make sure we have a legal set of flags */
339 	if (flags != (flags & KEXEC_FILE_FLAGS))
340 		return -EINVAL;
341 
342 	image = NULL;
343 
344 	if (!kexec_trylock())
345 		return -EBUSY;
346 
347 	if (image_type == KEXEC_TYPE_CRASH) {
348 		dest_image = &kexec_crash_image;
349 		if (kexec_crash_image)
350 			arch_kexec_unprotect_crashkres();
351 	} else {
352 		dest_image = &kexec_image;
353 	}
354 
355 	if (flags & KEXEC_FILE_UNLOAD)
356 		goto exchange;
357 
358 	/*
359 	 * In case of crash, new kernel gets loaded in reserved region. It is
360 	 * same memory where old crash kernel might be loaded. Free any
361 	 * current crash dump kernel before we corrupt it.
362 	 */
363 	if (flags & KEXEC_FILE_ON_CRASH)
364 		kimage_free(xchg(&kexec_crash_image, NULL));
365 
366 	ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
367 				     cmdline_len, flags);
368 	if (ret)
369 		goto out;
370 
371 	ret = machine_kexec_prepare(image);
372 	if (ret)
373 		goto out;
374 
375 	/*
376 	 * Some architecture(like S390) may touch the crash memory before
377 	 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
378 	 */
379 	ret = kimage_crash_copy_vmcoreinfo(image);
380 	if (ret)
381 		goto out;
382 
383 	ret = kexec_calculate_store_digests(image);
384 	if (ret)
385 		goto out;
386 
387 	for (i = 0; i < image->nr_segments; i++) {
388 		struct kexec_segment *ksegment;
389 
390 		ksegment = &image->segment[i];
391 		pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
392 			 i, ksegment->buf, ksegment->bufsz, ksegment->mem,
393 			 ksegment->memsz);
394 
395 		ret = kimage_load_segment(image, &image->segment[i]);
396 		if (ret)
397 			goto out;
398 	}
399 
400 	kimage_terminate(image);
401 
402 	ret = machine_kexec_post_load(image);
403 	if (ret)
404 		goto out;
405 
406 	/*
407 	 * Free up any temporary buffers allocated which are not needed
408 	 * after image has been loaded
409 	 */
410 	kimage_file_post_load_cleanup(image);
411 exchange:
412 	image = xchg(dest_image, image);
413 out:
414 	if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
415 		arch_kexec_protect_crashkres();
416 
417 	kexec_unlock();
418 	kimage_free(image);
419 	return ret;
420 }
421 
locate_mem_hole_top_down(unsigned long start,unsigned long end,struct kexec_buf * kbuf)422 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
423 				    struct kexec_buf *kbuf)
424 {
425 	struct kimage *image = kbuf->image;
426 	unsigned long temp_start, temp_end;
427 
428 	temp_end = min(end, kbuf->buf_max);
429 	temp_start = temp_end - kbuf->memsz;
430 
431 	do {
432 		/* align down start */
433 		temp_start = temp_start & (~(kbuf->buf_align - 1));
434 
435 		if (temp_start < start || temp_start < kbuf->buf_min)
436 			return 0;
437 
438 		temp_end = temp_start + kbuf->memsz - 1;
439 
440 		/*
441 		 * Make sure this does not conflict with any of existing
442 		 * segments
443 		 */
444 		if (kimage_is_destination_range(image, temp_start, temp_end)) {
445 			temp_start = temp_start - PAGE_SIZE;
446 			continue;
447 		}
448 
449 		/* We found a suitable memory range */
450 		break;
451 	} while (1);
452 
453 	/* If we are here, we found a suitable memory range */
454 	kbuf->mem = temp_start;
455 
456 	/* Success, stop navigating through remaining System RAM ranges */
457 	return 1;
458 }
459 
locate_mem_hole_bottom_up(unsigned long start,unsigned long end,struct kexec_buf * kbuf)460 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
461 				     struct kexec_buf *kbuf)
462 {
463 	struct kimage *image = kbuf->image;
464 	unsigned long temp_start, temp_end;
465 
466 	temp_start = max(start, kbuf->buf_min);
467 
468 	do {
469 		temp_start = ALIGN(temp_start, kbuf->buf_align);
470 		temp_end = temp_start + kbuf->memsz - 1;
471 
472 		if (temp_end > end || temp_end > kbuf->buf_max)
473 			return 0;
474 		/*
475 		 * Make sure this does not conflict with any of existing
476 		 * segments
477 		 */
478 		if (kimage_is_destination_range(image, temp_start, temp_end)) {
479 			temp_start = temp_start + PAGE_SIZE;
480 			continue;
481 		}
482 
483 		/* We found a suitable memory range */
484 		break;
485 	} while (1);
486 
487 	/* If we are here, we found a suitable memory range */
488 	kbuf->mem = temp_start;
489 
490 	/* Success, stop navigating through remaining System RAM ranges */
491 	return 1;
492 }
493 
locate_mem_hole_callback(struct resource * res,void * arg)494 static int locate_mem_hole_callback(struct resource *res, void *arg)
495 {
496 	struct kexec_buf *kbuf = (struct kexec_buf *)arg;
497 	u64 start = res->start, end = res->end;
498 	unsigned long sz = end - start + 1;
499 
500 	/* Returning 0 will take to next memory range */
501 
502 	/* Don't use memory that will be detected and handled by a driver. */
503 	if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
504 		return 0;
505 
506 	if (sz < kbuf->memsz)
507 		return 0;
508 
509 	if (end < kbuf->buf_min || start > kbuf->buf_max)
510 		return 0;
511 
512 	/*
513 	 * Allocate memory top down with-in ram range. Otherwise bottom up
514 	 * allocation.
515 	 */
516 	if (kbuf->top_down)
517 		return locate_mem_hole_top_down(start, end, kbuf);
518 	return locate_mem_hole_bottom_up(start, end, kbuf);
519 }
520 
521 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
kexec_walk_memblock(struct kexec_buf * kbuf,int (* func)(struct resource *,void *))522 static int kexec_walk_memblock(struct kexec_buf *kbuf,
523 			       int (*func)(struct resource *, void *))
524 {
525 	int ret = 0;
526 	u64 i;
527 	phys_addr_t mstart, mend;
528 	struct resource res = { };
529 
530 	if (kbuf->image->type == KEXEC_TYPE_CRASH)
531 		return func(&crashk_res, kbuf);
532 
533 	/*
534 	 * Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See
535 	 * IORESOURCE_SYSRAM_DRIVER_MANAGED handling in
536 	 * locate_mem_hole_callback().
537 	 */
538 	if (kbuf->top_down) {
539 		for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,
540 						&mstart, &mend, NULL) {
541 			/*
542 			 * In memblock, end points to the first byte after the
543 			 * range while in kexec, end points to the last byte
544 			 * in the range.
545 			 */
546 			res.start = mstart;
547 			res.end = mend - 1;
548 			ret = func(&res, kbuf);
549 			if (ret)
550 				break;
551 		}
552 	} else {
553 		for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
554 					&mstart, &mend, NULL) {
555 			/*
556 			 * In memblock, end points to the first byte after the
557 			 * range while in kexec, end points to the last byte
558 			 * in the range.
559 			 */
560 			res.start = mstart;
561 			res.end = mend - 1;
562 			ret = func(&res, kbuf);
563 			if (ret)
564 				break;
565 		}
566 	}
567 
568 	return ret;
569 }
570 #else
kexec_walk_memblock(struct kexec_buf * kbuf,int (* func)(struct resource *,void *))571 static int kexec_walk_memblock(struct kexec_buf *kbuf,
572 			       int (*func)(struct resource *, void *))
573 {
574 	return 0;
575 }
576 #endif
577 
578 /**
579  * kexec_walk_resources - call func(data) on free memory regions
580  * @kbuf:	Context info for the search. Also passed to @func.
581  * @func:	Function to call for each memory region.
582  *
583  * Return: The memory walk will stop when func returns a non-zero value
584  * and that value will be returned. If all free regions are visited without
585  * func returning non-zero, then zero will be returned.
586  */
kexec_walk_resources(struct kexec_buf * kbuf,int (* func)(struct resource *,void *))587 static int kexec_walk_resources(struct kexec_buf *kbuf,
588 				int (*func)(struct resource *, void *))
589 {
590 	if (kbuf->image->type == KEXEC_TYPE_CRASH)
591 		return walk_iomem_res_desc(crashk_res.desc,
592 					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
593 					   crashk_res.start, crashk_res.end,
594 					   kbuf, func);
595 	else
596 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
597 }
598 
599 /**
600  * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
601  * @kbuf:	Parameters for the memory search.
602  *
603  * On success, kbuf->mem will have the start address of the memory region found.
604  *
605  * Return: 0 on success, negative errno on error.
606  */
kexec_locate_mem_hole(struct kexec_buf * kbuf)607 int kexec_locate_mem_hole(struct kexec_buf *kbuf)
608 {
609 	int ret;
610 
611 	/* Arch knows where to place */
612 	if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
613 		return 0;
614 
615 	if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
616 		ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
617 	else
618 		ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);
619 
620 	return ret == 1 ? 0 : -EADDRNOTAVAIL;
621 }
622 
623 /**
624  * kexec_add_buffer - place a buffer in a kexec segment
625  * @kbuf:	Buffer contents and memory parameters.
626  *
627  * This function assumes that kexec_lock is held.
628  * On successful return, @kbuf->mem will have the physical address of
629  * the buffer in memory.
630  *
631  * Return: 0 on success, negative errno on error.
632  */
kexec_add_buffer(struct kexec_buf * kbuf)633 int kexec_add_buffer(struct kexec_buf *kbuf)
634 {
635 	struct kexec_segment *ksegment;
636 	int ret;
637 
638 	/* Currently adding segment this way is allowed only in file mode */
639 	if (!kbuf->image->file_mode)
640 		return -EINVAL;
641 
642 	if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
643 		return -EINVAL;
644 
645 	/*
646 	 * Make sure we are not trying to add buffer after allocating
647 	 * control pages. All segments need to be placed first before
648 	 * any control pages are allocated. As control page allocation
649 	 * logic goes through list of segments to make sure there are
650 	 * no destination overlaps.
651 	 */
652 	if (!list_empty(&kbuf->image->control_pages)) {
653 		WARN_ON(1);
654 		return -EINVAL;
655 	}
656 
657 	/* Ensure minimum alignment needed for segments. */
658 	kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
659 	kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
660 
661 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
662 	ret = arch_kexec_locate_mem_hole(kbuf);
663 	if (ret)
664 		return ret;
665 
666 	/* Found a suitable memory range */
667 	ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
668 	ksegment->kbuf = kbuf->buffer;
669 	ksegment->bufsz = kbuf->bufsz;
670 	ksegment->mem = kbuf->mem;
671 	ksegment->memsz = kbuf->memsz;
672 	kbuf->image->nr_segments++;
673 	return 0;
674 }
675 
676 /* Calculate and store the digest of segments */
kexec_calculate_store_digests(struct kimage * image)677 static int kexec_calculate_store_digests(struct kimage *image)
678 {
679 	struct crypto_shash *tfm;
680 	struct shash_desc *desc;
681 	int ret = 0, i, j, zero_buf_sz, sha_region_sz;
682 	size_t desc_size, nullsz;
683 	char *digest;
684 	void *zero_buf;
685 	struct kexec_sha_region *sha_regions;
686 	struct purgatory_info *pi = &image->purgatory_info;
687 
688 	if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY))
689 		return 0;
690 
691 	zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
692 	zero_buf_sz = PAGE_SIZE;
693 
694 	tfm = crypto_alloc_shash("sha256", 0, 0);
695 	if (IS_ERR(tfm)) {
696 		ret = PTR_ERR(tfm);
697 		goto out;
698 	}
699 
700 	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
701 	desc = kzalloc(desc_size, GFP_KERNEL);
702 	if (!desc) {
703 		ret = -ENOMEM;
704 		goto out_free_tfm;
705 	}
706 
707 	sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
708 	sha_regions = vzalloc(sha_region_sz);
709 	if (!sha_regions) {
710 		ret = -ENOMEM;
711 		goto out_free_desc;
712 	}
713 
714 	desc->tfm   = tfm;
715 
716 	ret = crypto_shash_init(desc);
717 	if (ret < 0)
718 		goto out_free_sha_regions;
719 
720 	digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
721 	if (!digest) {
722 		ret = -ENOMEM;
723 		goto out_free_sha_regions;
724 	}
725 
726 	for (j = i = 0; i < image->nr_segments; i++) {
727 		struct kexec_segment *ksegment;
728 
729 #ifdef CONFIG_CRASH_HOTPLUG
730 		/* Exclude elfcorehdr segment to allow future changes via hotplug */
731 		if (i == image->elfcorehdr_index)
732 			continue;
733 #endif
734 
735 		ksegment = &image->segment[i];
736 		/*
737 		 * Skip purgatory as it will be modified once we put digest
738 		 * info in purgatory.
739 		 */
740 		if (ksegment->kbuf == pi->purgatory_buf)
741 			continue;
742 
743 		ret = crypto_shash_update(desc, ksegment->kbuf,
744 					  ksegment->bufsz);
745 		if (ret)
746 			break;
747 
748 		/*
749 		 * Assume rest of the buffer is filled with zero and
750 		 * update digest accordingly.
751 		 */
752 		nullsz = ksegment->memsz - ksegment->bufsz;
753 		while (nullsz) {
754 			unsigned long bytes = nullsz;
755 
756 			if (bytes > zero_buf_sz)
757 				bytes = zero_buf_sz;
758 			ret = crypto_shash_update(desc, zero_buf, bytes);
759 			if (ret)
760 				break;
761 			nullsz -= bytes;
762 		}
763 
764 		if (ret)
765 			break;
766 
767 		sha_regions[j].start = ksegment->mem;
768 		sha_regions[j].len = ksegment->memsz;
769 		j++;
770 	}
771 
772 	if (!ret) {
773 		ret = crypto_shash_final(desc, digest);
774 		if (ret)
775 			goto out_free_digest;
776 		ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
777 						     sha_regions, sha_region_sz, 0);
778 		if (ret)
779 			goto out_free_digest;
780 
781 		ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
782 						     digest, SHA256_DIGEST_SIZE, 0);
783 		if (ret)
784 			goto out_free_digest;
785 	}
786 
787 out_free_digest:
788 	kfree(digest);
789 out_free_sha_regions:
790 	vfree(sha_regions);
791 out_free_desc:
792 	kfree(desc);
793 out_free_tfm:
794 	kfree(tfm);
795 out:
796 	return ret;
797 }
798 
799 #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
800 /*
801  * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
802  * @pi:		Purgatory to be loaded.
803  * @kbuf:	Buffer to setup.
804  *
805  * Allocates the memory needed for the buffer. Caller is responsible to free
806  * the memory after use.
807  *
808  * Return: 0 on success, negative errno on error.
809  */
kexec_purgatory_setup_kbuf(struct purgatory_info * pi,struct kexec_buf * kbuf)810 static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
811 				      struct kexec_buf *kbuf)
812 {
813 	const Elf_Shdr *sechdrs;
814 	unsigned long bss_align;
815 	unsigned long bss_sz;
816 	unsigned long align;
817 	int i, ret;
818 
819 	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
820 	kbuf->buf_align = bss_align = 1;
821 	kbuf->bufsz = bss_sz = 0;
822 
823 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
824 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
825 			continue;
826 
827 		align = sechdrs[i].sh_addralign;
828 		if (sechdrs[i].sh_type != SHT_NOBITS) {
829 			if (kbuf->buf_align < align)
830 				kbuf->buf_align = align;
831 			kbuf->bufsz = ALIGN(kbuf->bufsz, align);
832 			kbuf->bufsz += sechdrs[i].sh_size;
833 		} else {
834 			if (bss_align < align)
835 				bss_align = align;
836 			bss_sz = ALIGN(bss_sz, align);
837 			bss_sz += sechdrs[i].sh_size;
838 		}
839 	}
840 	kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
841 	kbuf->memsz = kbuf->bufsz + bss_sz;
842 	if (kbuf->buf_align < bss_align)
843 		kbuf->buf_align = bss_align;
844 
845 	kbuf->buffer = vzalloc(kbuf->bufsz);
846 	if (!kbuf->buffer)
847 		return -ENOMEM;
848 	pi->purgatory_buf = kbuf->buffer;
849 
850 	ret = kexec_add_buffer(kbuf);
851 	if (ret)
852 		goto out;
853 
854 	return 0;
855 out:
856 	vfree(pi->purgatory_buf);
857 	pi->purgatory_buf = NULL;
858 	return ret;
859 }
860 
861 /*
862  * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
863  * @pi:		Purgatory to be loaded.
864  * @kbuf:	Buffer prepared to store purgatory.
865  *
866  * Allocates the memory needed for the buffer. Caller is responsible to free
867  * the memory after use.
868  *
869  * Return: 0 on success, negative errno on error.
870  */
kexec_purgatory_setup_sechdrs(struct purgatory_info * pi,struct kexec_buf * kbuf)871 static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
872 					 struct kexec_buf *kbuf)
873 {
874 	unsigned long bss_addr;
875 	unsigned long offset;
876 	size_t sechdrs_size;
877 	Elf_Shdr *sechdrs;
878 	int i;
879 
880 	/*
881 	 * The section headers in kexec_purgatory are read-only. In order to
882 	 * have them modifiable make a temporary copy.
883 	 */
884 	sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
885 	sechdrs = vzalloc(sechdrs_size);
886 	if (!sechdrs)
887 		return -ENOMEM;
888 	memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
889 	pi->sechdrs = sechdrs;
890 
891 	offset = 0;
892 	bss_addr = kbuf->mem + kbuf->bufsz;
893 	kbuf->image->start = pi->ehdr->e_entry;
894 
895 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
896 		unsigned long align;
897 		void *src, *dst;
898 
899 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
900 			continue;
901 
902 		align = sechdrs[i].sh_addralign;
903 		if (sechdrs[i].sh_type == SHT_NOBITS) {
904 			bss_addr = ALIGN(bss_addr, align);
905 			sechdrs[i].sh_addr = bss_addr;
906 			bss_addr += sechdrs[i].sh_size;
907 			continue;
908 		}
909 
910 		offset = ALIGN(offset, align);
911 
912 		/*
913 		 * Check if the segment contains the entry point, if so,
914 		 * calculate the value of image->start based on it.
915 		 * If the compiler has produced more than one .text section
916 		 * (Eg: .text.hot), they are generally after the main .text
917 		 * section, and they shall not be used to calculate
918 		 * image->start. So do not re-calculate image->start if it
919 		 * is not set to the initial value, and warn the user so they
920 		 * have a chance to fix their purgatory's linker script.
921 		 */
922 		if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
923 		    pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
924 		    pi->ehdr->e_entry < (sechdrs[i].sh_addr
925 					 + sechdrs[i].sh_size) &&
926 		    !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) {
927 			kbuf->image->start -= sechdrs[i].sh_addr;
928 			kbuf->image->start += kbuf->mem + offset;
929 		}
930 
931 		src = (void *)pi->ehdr + sechdrs[i].sh_offset;
932 		dst = pi->purgatory_buf + offset;
933 		memcpy(dst, src, sechdrs[i].sh_size);
934 
935 		sechdrs[i].sh_addr = kbuf->mem + offset;
936 		sechdrs[i].sh_offset = offset;
937 		offset += sechdrs[i].sh_size;
938 	}
939 
940 	return 0;
941 }
942 
kexec_apply_relocations(struct kimage * image)943 static int kexec_apply_relocations(struct kimage *image)
944 {
945 	int i, ret;
946 	struct purgatory_info *pi = &image->purgatory_info;
947 	const Elf_Shdr *sechdrs;
948 
949 	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
950 
951 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
952 		const Elf_Shdr *relsec;
953 		const Elf_Shdr *symtab;
954 		Elf_Shdr *section;
955 
956 		relsec = sechdrs + i;
957 
958 		if (relsec->sh_type != SHT_RELA &&
959 		    relsec->sh_type != SHT_REL)
960 			continue;
961 
962 		/*
963 		 * For section of type SHT_RELA/SHT_REL,
964 		 * ->sh_link contains section header index of associated
965 		 * symbol table. And ->sh_info contains section header
966 		 * index of section to which relocations apply.
967 		 */
968 		if (relsec->sh_info >= pi->ehdr->e_shnum ||
969 		    relsec->sh_link >= pi->ehdr->e_shnum)
970 			return -ENOEXEC;
971 
972 		section = pi->sechdrs + relsec->sh_info;
973 		symtab = sechdrs + relsec->sh_link;
974 
975 		if (!(section->sh_flags & SHF_ALLOC))
976 			continue;
977 
978 		/*
979 		 * symtab->sh_link contain section header index of associated
980 		 * string table.
981 		 */
982 		if (symtab->sh_link >= pi->ehdr->e_shnum)
983 			/* Invalid section number? */
984 			continue;
985 
986 		/*
987 		 * Respective architecture needs to provide support for applying
988 		 * relocations of type SHT_RELA/SHT_REL.
989 		 */
990 		if (relsec->sh_type == SHT_RELA)
991 			ret = arch_kexec_apply_relocations_add(pi, section,
992 							       relsec, symtab);
993 		else if (relsec->sh_type == SHT_REL)
994 			ret = arch_kexec_apply_relocations(pi, section,
995 							   relsec, symtab);
996 		if (ret)
997 			return ret;
998 	}
999 
1000 	return 0;
1001 }
1002 
1003 /*
1004  * kexec_load_purgatory - Load and relocate the purgatory object.
1005  * @image:	Image to add the purgatory to.
1006  * @kbuf:	Memory parameters to use.
1007  *
1008  * Allocates the memory needed for image->purgatory_info.sechdrs and
1009  * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
1010  * to free the memory after use.
1011  *
1012  * Return: 0 on success, negative errno on error.
1013  */
kexec_load_purgatory(struct kimage * image,struct kexec_buf * kbuf)1014 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
1015 {
1016 	struct purgatory_info *pi = &image->purgatory_info;
1017 	int ret;
1018 
1019 	if (kexec_purgatory_size <= 0)
1020 		return -EINVAL;
1021 
1022 	pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
1023 
1024 	ret = kexec_purgatory_setup_kbuf(pi, kbuf);
1025 	if (ret)
1026 		return ret;
1027 
1028 	ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
1029 	if (ret)
1030 		goto out_free_kbuf;
1031 
1032 	ret = kexec_apply_relocations(image);
1033 	if (ret)
1034 		goto out;
1035 
1036 	return 0;
1037 out:
1038 	vfree(pi->sechdrs);
1039 	pi->sechdrs = NULL;
1040 out_free_kbuf:
1041 	vfree(pi->purgatory_buf);
1042 	pi->purgatory_buf = NULL;
1043 	return ret;
1044 }
1045 
1046 /*
1047  * kexec_purgatory_find_symbol - find a symbol in the purgatory
1048  * @pi:		Purgatory to search in.
1049  * @name:	Name of the symbol.
1050  *
1051  * Return: pointer to symbol in read-only symtab on success, NULL on error.
1052  */
kexec_purgatory_find_symbol(struct purgatory_info * pi,const char * name)1053 static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
1054 						  const char *name)
1055 {
1056 	const Elf_Shdr *sechdrs;
1057 	const Elf_Ehdr *ehdr;
1058 	const Elf_Sym *syms;
1059 	const char *strtab;
1060 	int i, k;
1061 
1062 	if (!pi->ehdr)
1063 		return NULL;
1064 
1065 	ehdr = pi->ehdr;
1066 	sechdrs = (void *)ehdr + ehdr->e_shoff;
1067 
1068 	for (i = 0; i < ehdr->e_shnum; i++) {
1069 		if (sechdrs[i].sh_type != SHT_SYMTAB)
1070 			continue;
1071 
1072 		if (sechdrs[i].sh_link >= ehdr->e_shnum)
1073 			/* Invalid strtab section number */
1074 			continue;
1075 		strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
1076 		syms = (void *)ehdr + sechdrs[i].sh_offset;
1077 
1078 		/* Go through symbols for a match */
1079 		for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
1080 			if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
1081 				continue;
1082 
1083 			if (strcmp(strtab + syms[k].st_name, name) != 0)
1084 				continue;
1085 
1086 			if (syms[k].st_shndx == SHN_UNDEF ||
1087 			    syms[k].st_shndx >= ehdr->e_shnum) {
1088 				pr_debug("Symbol: %s has bad section index %d.\n",
1089 						name, syms[k].st_shndx);
1090 				return NULL;
1091 			}
1092 
1093 			/* Found the symbol we are looking for */
1094 			return &syms[k];
1095 		}
1096 	}
1097 
1098 	return NULL;
1099 }
1100 
kexec_purgatory_get_symbol_addr(struct kimage * image,const char * name)1101 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
1102 {
1103 	struct purgatory_info *pi = &image->purgatory_info;
1104 	const Elf_Sym *sym;
1105 	Elf_Shdr *sechdr;
1106 
1107 	sym = kexec_purgatory_find_symbol(pi, name);
1108 	if (!sym)
1109 		return ERR_PTR(-EINVAL);
1110 
1111 	sechdr = &pi->sechdrs[sym->st_shndx];
1112 
1113 	/*
1114 	 * Returns the address where symbol will finally be loaded after
1115 	 * kexec_load_segment()
1116 	 */
1117 	return (void *)(sechdr->sh_addr + sym->st_value);
1118 }
1119 
1120 /*
1121  * Get or set value of a symbol. If "get_value" is true, symbol value is
1122  * returned in buf otherwise symbol value is set based on value in buf.
1123  */
kexec_purgatory_get_set_symbol(struct kimage * image,const char * name,void * buf,unsigned int size,bool get_value)1124 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
1125 				   void *buf, unsigned int size, bool get_value)
1126 {
1127 	struct purgatory_info *pi = &image->purgatory_info;
1128 	const Elf_Sym *sym;
1129 	Elf_Shdr *sec;
1130 	char *sym_buf;
1131 
1132 	sym = kexec_purgatory_find_symbol(pi, name);
1133 	if (!sym)
1134 		return -EINVAL;
1135 
1136 	if (sym->st_size != size) {
1137 		pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1138 		       name, (unsigned long)sym->st_size, size);
1139 		return -EINVAL;
1140 	}
1141 
1142 	sec = pi->sechdrs + sym->st_shndx;
1143 
1144 	if (sec->sh_type == SHT_NOBITS) {
1145 		pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1146 		       get_value ? "get" : "set");
1147 		return -EINVAL;
1148 	}
1149 
1150 	sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
1151 
1152 	if (get_value)
1153 		memcpy((void *)buf, sym_buf, size);
1154 	else
1155 		memcpy((void *)sym_buf, buf, size);
1156 
1157 	return 0;
1158 }
1159 #endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */
1160