xref: /linux/kernel/kexec_file.c (revision 76c0f27d063079ce2c6e7fa971a185a38905d844)
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 	kexec_file_dbg_print = false;
128 }
129 
130 #ifdef CONFIG_KEXEC_SIG
131 #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
kexec_kernel_verify_pe_sig(const char * kernel,unsigned long kernel_len)132 int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
133 {
134 	int ret;
135 
136 	ret = verify_pefile_signature(kernel, kernel_len,
137 				      VERIFY_USE_SECONDARY_KEYRING,
138 				      VERIFYING_KEXEC_PE_SIGNATURE);
139 	if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
140 		ret = verify_pefile_signature(kernel, kernel_len,
141 					      VERIFY_USE_PLATFORM_KEYRING,
142 					      VERIFYING_KEXEC_PE_SIGNATURE);
143 	}
144 	return ret;
145 }
146 #endif
147 
kexec_image_verify_sig(struct kimage * image,void * buf,unsigned long buf_len)148 static int kexec_image_verify_sig(struct kimage *image, void *buf,
149 				  unsigned long buf_len)
150 {
151 	if (!image->fops || !image->fops->verify_sig) {
152 		pr_debug("kernel loader does not support signature verification.\n");
153 		return -EKEYREJECTED;
154 	}
155 
156 	return image->fops->verify_sig(buf, buf_len);
157 }
158 
159 static int
kimage_validate_signature(struct kimage * image)160 kimage_validate_signature(struct kimage *image)
161 {
162 	int ret;
163 
164 	ret = kexec_image_verify_sig(image, image->kernel_buf,
165 				     image->kernel_buf_len);
166 	if (ret) {
167 
168 		if (sig_enforce) {
169 			pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
170 			return ret;
171 		}
172 
173 		/*
174 		 * If IMA is guaranteed to appraise a signature on the kexec
175 		 * image, permit it even if the kernel is otherwise locked
176 		 * down.
177 		 */
178 		if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
179 		    security_locked_down(LOCKDOWN_KEXEC))
180 			return -EPERM;
181 
182 		pr_debug("kernel signature verification failed (%d).\n", ret);
183 	}
184 
185 	return 0;
186 }
187 #endif
188 
189 /*
190  * In file mode list of segments is prepared by kernel. Copy relevant
191  * data from user space, do error checking, prepare segment list
192  */
193 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)194 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
195 			     const char __user *cmdline_ptr,
196 			     unsigned long cmdline_len, unsigned flags)
197 {
198 	ssize_t ret;
199 	void *ldata;
200 
201 	ret = kernel_read_file_from_fd(kernel_fd, 0, &image->kernel_buf,
202 				       KEXEC_FILE_SIZE_MAX, NULL,
203 				       READING_KEXEC_IMAGE);
204 	if (ret < 0)
205 		return ret;
206 	image->kernel_buf_len = ret;
207 	kexec_dprintk("kernel: %p kernel_size: %#lx\n",
208 		      image->kernel_buf, image->kernel_buf_len);
209 
210 	/* Call arch image probe handlers */
211 	ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
212 					    image->kernel_buf_len);
213 	if (ret)
214 		goto out;
215 
216 #ifdef CONFIG_KEXEC_SIG
217 	ret = kimage_validate_signature(image);
218 
219 	if (ret)
220 		goto out;
221 #endif
222 	/* It is possible that there no initramfs is being loaded */
223 	if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
224 		ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf,
225 					       KEXEC_FILE_SIZE_MAX, NULL,
226 					       READING_KEXEC_INITRAMFS);
227 		if (ret < 0)
228 			goto out;
229 		image->initrd_buf_len = ret;
230 		ret = 0;
231 	}
232 
233 	if (cmdline_len) {
234 		image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
235 		if (IS_ERR(image->cmdline_buf)) {
236 			ret = PTR_ERR(image->cmdline_buf);
237 			image->cmdline_buf = NULL;
238 			goto out;
239 		}
240 
241 		image->cmdline_buf_len = cmdline_len;
242 
243 		/* command line should be a string with last byte null */
244 		if (image->cmdline_buf[cmdline_len - 1] != '\0') {
245 			ret = -EINVAL;
246 			goto out;
247 		}
248 
249 		ima_kexec_cmdline(kernel_fd, image->cmdline_buf,
250 				  image->cmdline_buf_len - 1);
251 	}
252 
253 	/* IMA needs to pass the measurement list to the next kernel. */
254 	ima_add_kexec_buffer(image);
255 
256 	/* Call image load handler */
257 	ldata = kexec_image_load_default(image);
258 
259 	if (IS_ERR(ldata)) {
260 		ret = PTR_ERR(ldata);
261 		goto out;
262 	}
263 
264 	image->image_loader_data = ldata;
265 out:
266 	/* In case of error, free up all allocated memory in this function */
267 	if (ret)
268 		kimage_file_post_load_cleanup(image);
269 	return ret;
270 }
271 
272 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)273 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
274 		       int initrd_fd, const char __user *cmdline_ptr,
275 		       unsigned long cmdline_len, unsigned long flags)
276 {
277 	int ret;
278 	struct kimage *image;
279 	bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
280 
281 	image = do_kimage_alloc_init();
282 	if (!image)
283 		return -ENOMEM;
284 
285 	kexec_file_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
286 	image->file_mode = 1;
287 
288 #ifdef CONFIG_CRASH_DUMP
289 	if (kexec_on_panic) {
290 		/* Enable special crash kernel control page alloc policy. */
291 		image->control_page = crashk_res.start;
292 		image->type = KEXEC_TYPE_CRASH;
293 	}
294 #endif
295 
296 	ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
297 					   cmdline_ptr, cmdline_len, flags);
298 	if (ret)
299 		goto out_free_image;
300 
301 	ret = sanity_check_segment_list(image);
302 	if (ret)
303 		goto out_free_post_load_bufs;
304 
305 	ret = -ENOMEM;
306 	image->control_code_page = kimage_alloc_control_pages(image,
307 					   get_order(KEXEC_CONTROL_PAGE_SIZE));
308 	if (!image->control_code_page) {
309 		pr_err("Could not allocate control_code_buffer\n");
310 		goto out_free_post_load_bufs;
311 	}
312 
313 	if (!kexec_on_panic) {
314 		image->swap_page = kimage_alloc_control_pages(image, 0);
315 		if (!image->swap_page) {
316 			pr_err("Could not allocate swap buffer\n");
317 			goto out_free_control_pages;
318 		}
319 	}
320 
321 	*rimage = image;
322 	return 0;
323 out_free_control_pages:
324 	kimage_free_page_list(&image->control_pages);
325 out_free_post_load_bufs:
326 	kimage_file_post_load_cleanup(image);
327 out_free_image:
328 	kfree(image);
329 	return ret;
330 }
331 
SYSCALL_DEFINE5(kexec_file_load,int,kernel_fd,int,initrd_fd,unsigned long,cmdline_len,const char __user *,cmdline_ptr,unsigned long,flags)332 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
333 		unsigned long, cmdline_len, const char __user *, cmdline_ptr,
334 		unsigned long, flags)
335 {
336 	int image_type = (flags & KEXEC_FILE_ON_CRASH) ?
337 			 KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
338 	struct kimage **dest_image, *image;
339 	int ret = 0, i;
340 
341 	/* We only trust the superuser with rebooting the system. */
342 	if (!kexec_load_permitted(image_type))
343 		return -EPERM;
344 
345 	/* Make sure we have a legal set of flags */
346 	if (flags != (flags & KEXEC_FILE_FLAGS))
347 		return -EINVAL;
348 
349 	image = NULL;
350 
351 	if (!kexec_trylock())
352 		return -EBUSY;
353 
354 #ifdef CONFIG_CRASH_DUMP
355 	if (image_type == KEXEC_TYPE_CRASH) {
356 		dest_image = &kexec_crash_image;
357 		if (kexec_crash_image)
358 			arch_kexec_unprotect_crashkres();
359 	} else
360 #endif
361 		dest_image = &kexec_image;
362 
363 	if (flags & KEXEC_FILE_UNLOAD)
364 		goto exchange;
365 
366 	/*
367 	 * In case of crash, new kernel gets loaded in reserved region. It is
368 	 * same memory where old crash kernel might be loaded. Free any
369 	 * current crash dump kernel before we corrupt it.
370 	 */
371 	if (flags & KEXEC_FILE_ON_CRASH)
372 		kimage_free(xchg(&kexec_crash_image, NULL));
373 
374 	ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
375 				     cmdline_len, flags);
376 	if (ret)
377 		goto out;
378 
379 #ifdef CONFIG_CRASH_HOTPLUG
380 	if ((flags & KEXEC_FILE_ON_CRASH) && arch_crash_hotplug_support(image, flags))
381 		image->hotplug_support = 1;
382 #endif
383 
384 	ret = machine_kexec_prepare(image);
385 	if (ret)
386 		goto out;
387 
388 	/*
389 	 * Some architecture(like S390) may touch the crash memory before
390 	 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
391 	 */
392 	ret = kimage_crash_copy_vmcoreinfo(image);
393 	if (ret)
394 		goto out;
395 
396 	ret = kexec_calculate_store_digests(image);
397 	if (ret)
398 		goto out;
399 
400 	kexec_dprintk("nr_segments = %lu\n", image->nr_segments);
401 	for (i = 0; i < image->nr_segments; i++) {
402 		struct kexec_segment *ksegment;
403 
404 		ksegment = &image->segment[i];
405 		kexec_dprintk("segment[%d]: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
406 			      i, ksegment->buf, ksegment->bufsz, ksegment->mem,
407 			      ksegment->memsz);
408 
409 		ret = kimage_load_segment(image, &image->segment[i]);
410 		if (ret)
411 			goto out;
412 	}
413 
414 	kimage_terminate(image);
415 
416 	ret = machine_kexec_post_load(image);
417 	if (ret)
418 		goto out;
419 
420 	kexec_dprintk("kexec_file_load: type:%u, start:0x%lx head:0x%lx flags:0x%lx\n",
421 		      image->type, image->start, image->head, flags);
422 	/*
423 	 * Free up any temporary buffers allocated which are not needed
424 	 * after image has been loaded
425 	 */
426 	kimage_file_post_load_cleanup(image);
427 exchange:
428 	image = xchg(dest_image, image);
429 out:
430 #ifdef CONFIG_CRASH_DUMP
431 	if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
432 		arch_kexec_protect_crashkres();
433 #endif
434 
435 	kexec_unlock();
436 	kimage_free(image);
437 	return ret;
438 }
439 
locate_mem_hole_top_down(unsigned long start,unsigned long end,struct kexec_buf * kbuf)440 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
441 				    struct kexec_buf *kbuf)
442 {
443 	struct kimage *image = kbuf->image;
444 	unsigned long temp_start, temp_end;
445 
446 	temp_end = min(end, kbuf->buf_max);
447 	temp_start = temp_end - kbuf->memsz + 1;
448 
449 	do {
450 		/* align down start */
451 		temp_start = ALIGN_DOWN(temp_start, kbuf->buf_align);
452 
453 		if (temp_start < start || temp_start < kbuf->buf_min)
454 			return 0;
455 
456 		temp_end = temp_start + kbuf->memsz - 1;
457 
458 		/*
459 		 * Make sure this does not conflict with any of existing
460 		 * segments
461 		 */
462 		if (kimage_is_destination_range(image, temp_start, temp_end)) {
463 			temp_start = temp_start - PAGE_SIZE;
464 			continue;
465 		}
466 
467 		/* We found a suitable memory range */
468 		break;
469 	} while (1);
470 
471 	/* If we are here, we found a suitable memory range */
472 	kbuf->mem = temp_start;
473 
474 	/* Success, stop navigating through remaining System RAM ranges */
475 	return 1;
476 }
477 
locate_mem_hole_bottom_up(unsigned long start,unsigned long end,struct kexec_buf * kbuf)478 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
479 				     struct kexec_buf *kbuf)
480 {
481 	struct kimage *image = kbuf->image;
482 	unsigned long temp_start, temp_end;
483 
484 	temp_start = max(start, kbuf->buf_min);
485 
486 	do {
487 		temp_start = ALIGN(temp_start, kbuf->buf_align);
488 		temp_end = temp_start + kbuf->memsz - 1;
489 
490 		if (temp_end > end || temp_end > kbuf->buf_max)
491 			return 0;
492 		/*
493 		 * Make sure this does not conflict with any of existing
494 		 * segments
495 		 */
496 		if (kimage_is_destination_range(image, temp_start, temp_end)) {
497 			temp_start = temp_start + PAGE_SIZE;
498 			continue;
499 		}
500 
501 		/* We found a suitable memory range */
502 		break;
503 	} while (1);
504 
505 	/* If we are here, we found a suitable memory range */
506 	kbuf->mem = temp_start;
507 
508 	/* Success, stop navigating through remaining System RAM ranges */
509 	return 1;
510 }
511 
locate_mem_hole_callback(struct resource * res,void * arg)512 static int locate_mem_hole_callback(struct resource *res, void *arg)
513 {
514 	struct kexec_buf *kbuf = (struct kexec_buf *)arg;
515 	u64 start = res->start, end = res->end;
516 	unsigned long sz = end - start + 1;
517 
518 	/* Returning 0 will take to next memory range */
519 
520 	/* Don't use memory that will be detected and handled by a driver. */
521 	if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
522 		return 0;
523 
524 	if (sz < kbuf->memsz)
525 		return 0;
526 
527 	if (end < kbuf->buf_min || start > kbuf->buf_max)
528 		return 0;
529 
530 	/*
531 	 * Allocate memory top down with-in ram range. Otherwise bottom up
532 	 * allocation.
533 	 */
534 	if (kbuf->top_down)
535 		return locate_mem_hole_top_down(start, end, kbuf);
536 	return locate_mem_hole_bottom_up(start, end, kbuf);
537 }
538 
539 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
kexec_walk_memblock(struct kexec_buf * kbuf,int (* func)(struct resource *,void *))540 static int kexec_walk_memblock(struct kexec_buf *kbuf,
541 			       int (*func)(struct resource *, void *))
542 {
543 	int ret = 0;
544 	u64 i;
545 	phys_addr_t mstart, mend;
546 	struct resource res = { };
547 
548 #ifdef CONFIG_CRASH_DUMP
549 	if (kbuf->image->type == KEXEC_TYPE_CRASH)
550 		return func(&crashk_res, kbuf);
551 #endif
552 
553 	/*
554 	 * Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See
555 	 * IORESOURCE_SYSRAM_DRIVER_MANAGED handling in
556 	 * locate_mem_hole_callback().
557 	 */
558 	if (kbuf->top_down) {
559 		for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,
560 						&mstart, &mend, NULL) {
561 			/*
562 			 * In memblock, end points to the first byte after the
563 			 * range while in kexec, end points to the last byte
564 			 * in the range.
565 			 */
566 			res.start = mstart;
567 			res.end = mend - 1;
568 			ret = func(&res, kbuf);
569 			if (ret)
570 				break;
571 		}
572 	} else {
573 		for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
574 					&mstart, &mend, NULL) {
575 			/*
576 			 * In memblock, end points to the first byte after the
577 			 * range while in kexec, end points to the last byte
578 			 * in the range.
579 			 */
580 			res.start = mstart;
581 			res.end = mend - 1;
582 			ret = func(&res, kbuf);
583 			if (ret)
584 				break;
585 		}
586 	}
587 
588 	return ret;
589 }
590 #else
kexec_walk_memblock(struct kexec_buf * kbuf,int (* func)(struct resource *,void *))591 static int kexec_walk_memblock(struct kexec_buf *kbuf,
592 			       int (*func)(struct resource *, void *))
593 {
594 	return 0;
595 }
596 #endif
597 
598 /**
599  * kexec_walk_resources - call func(data) on free memory regions
600  * @kbuf:	Context info for the search. Also passed to @func.
601  * @func:	Function to call for each memory region.
602  *
603  * Return: The memory walk will stop when func returns a non-zero value
604  * and that value will be returned. If all free regions are visited without
605  * func returning non-zero, then zero will be returned.
606  */
kexec_walk_resources(struct kexec_buf * kbuf,int (* func)(struct resource *,void *))607 static int kexec_walk_resources(struct kexec_buf *kbuf,
608 				int (*func)(struct resource *, void *))
609 {
610 #ifdef CONFIG_CRASH_DUMP
611 	if (kbuf->image->type == KEXEC_TYPE_CRASH)
612 		return walk_iomem_res_desc(crashk_res.desc,
613 					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
614 					   crashk_res.start, crashk_res.end,
615 					   kbuf, func);
616 #endif
617 	if (kbuf->top_down)
618 		return walk_system_ram_res_rev(0, ULONG_MAX, kbuf, func);
619 	else
620 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
621 }
622 
623 /**
624  * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
625  * @kbuf:	Parameters for the memory search.
626  *
627  * On success, kbuf->mem will have the start address of the memory region found.
628  *
629  * Return: 0 on success, negative errno on error.
630  */
kexec_locate_mem_hole(struct kexec_buf * kbuf)631 int kexec_locate_mem_hole(struct kexec_buf *kbuf)
632 {
633 	int ret;
634 
635 	/* Arch knows where to place */
636 	if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
637 		return 0;
638 
639 	if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
640 		ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
641 	else
642 		ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);
643 
644 	return ret == 1 ? 0 : -EADDRNOTAVAIL;
645 }
646 
647 /**
648  * kexec_add_buffer - place a buffer in a kexec segment
649  * @kbuf:	Buffer contents and memory parameters.
650  *
651  * This function assumes that kexec_lock is held.
652  * On successful return, @kbuf->mem will have the physical address of
653  * the buffer in memory.
654  *
655  * Return: 0 on success, negative errno on error.
656  */
kexec_add_buffer(struct kexec_buf * kbuf)657 int kexec_add_buffer(struct kexec_buf *kbuf)
658 {
659 	struct kexec_segment *ksegment;
660 	int ret;
661 
662 	/* Currently adding segment this way is allowed only in file mode */
663 	if (!kbuf->image->file_mode)
664 		return -EINVAL;
665 
666 	if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
667 		return -EINVAL;
668 
669 	/*
670 	 * Make sure we are not trying to add buffer after allocating
671 	 * control pages. All segments need to be placed first before
672 	 * any control pages are allocated. As control page allocation
673 	 * logic goes through list of segments to make sure there are
674 	 * no destination overlaps.
675 	 */
676 	if (!list_empty(&kbuf->image->control_pages)) {
677 		WARN_ON(1);
678 		return -EINVAL;
679 	}
680 
681 	/* Ensure minimum alignment needed for segments. */
682 	kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
683 	kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
684 
685 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
686 	ret = arch_kexec_locate_mem_hole(kbuf);
687 	if (ret)
688 		return ret;
689 
690 	/* Found a suitable memory range */
691 	ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
692 	ksegment->kbuf = kbuf->buffer;
693 	ksegment->bufsz = kbuf->bufsz;
694 	ksegment->mem = kbuf->mem;
695 	ksegment->memsz = kbuf->memsz;
696 	kbuf->image->nr_segments++;
697 	return 0;
698 }
699 
700 /* Calculate and store the digest of segments */
kexec_calculate_store_digests(struct kimage * image)701 static int kexec_calculate_store_digests(struct kimage *image)
702 {
703 	struct crypto_shash *tfm;
704 	struct shash_desc *desc;
705 	int ret = 0, i, j, zero_buf_sz, sha_region_sz;
706 	size_t desc_size, nullsz;
707 	char *digest;
708 	void *zero_buf;
709 	struct kexec_sha_region *sha_regions;
710 	struct purgatory_info *pi = &image->purgatory_info;
711 
712 	if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY))
713 		return 0;
714 
715 	zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
716 	zero_buf_sz = PAGE_SIZE;
717 
718 	tfm = crypto_alloc_shash("sha256", 0, 0);
719 	if (IS_ERR(tfm)) {
720 		ret = PTR_ERR(tfm);
721 		goto out;
722 	}
723 
724 	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
725 	desc = kzalloc(desc_size, GFP_KERNEL);
726 	if (!desc) {
727 		ret = -ENOMEM;
728 		goto out_free_tfm;
729 	}
730 
731 	sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
732 	sha_regions = vzalloc(sha_region_sz);
733 	if (!sha_regions) {
734 		ret = -ENOMEM;
735 		goto out_free_desc;
736 	}
737 
738 	desc->tfm   = tfm;
739 
740 	ret = crypto_shash_init(desc);
741 	if (ret < 0)
742 		goto out_free_sha_regions;
743 
744 	digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
745 	if (!digest) {
746 		ret = -ENOMEM;
747 		goto out_free_sha_regions;
748 	}
749 
750 	for (j = i = 0; i < image->nr_segments; i++) {
751 		struct kexec_segment *ksegment;
752 
753 #ifdef CONFIG_CRASH_HOTPLUG
754 		/* Exclude elfcorehdr segment to allow future changes via hotplug */
755 		if (i == image->elfcorehdr_index)
756 			continue;
757 #endif
758 
759 		ksegment = &image->segment[i];
760 		/*
761 		 * Skip purgatory as it will be modified once we put digest
762 		 * info in purgatory.
763 		 */
764 		if (ksegment->kbuf == pi->purgatory_buf)
765 			continue;
766 
767 		ret = crypto_shash_update(desc, ksegment->kbuf,
768 					  ksegment->bufsz);
769 		if (ret)
770 			break;
771 
772 		/*
773 		 * Assume rest of the buffer is filled with zero and
774 		 * update digest accordingly.
775 		 */
776 		nullsz = ksegment->memsz - ksegment->bufsz;
777 		while (nullsz) {
778 			unsigned long bytes = nullsz;
779 
780 			if (bytes > zero_buf_sz)
781 				bytes = zero_buf_sz;
782 			ret = crypto_shash_update(desc, zero_buf, bytes);
783 			if (ret)
784 				break;
785 			nullsz -= bytes;
786 		}
787 
788 		if (ret)
789 			break;
790 
791 		sha_regions[j].start = ksegment->mem;
792 		sha_regions[j].len = ksegment->memsz;
793 		j++;
794 	}
795 
796 	if (!ret) {
797 		ret = crypto_shash_final(desc, digest);
798 		if (ret)
799 			goto out_free_digest;
800 		ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
801 						     sha_regions, sha_region_sz, 0);
802 		if (ret)
803 			goto out_free_digest;
804 
805 		ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
806 						     digest, SHA256_DIGEST_SIZE, 0);
807 		if (ret)
808 			goto out_free_digest;
809 	}
810 
811 out_free_digest:
812 	kfree(digest);
813 out_free_sha_regions:
814 	vfree(sha_regions);
815 out_free_desc:
816 	kfree(desc);
817 out_free_tfm:
818 	kfree(tfm);
819 out:
820 	return ret;
821 }
822 
823 #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
824 /*
825  * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
826  * @pi:		Purgatory to be loaded.
827  * @kbuf:	Buffer to setup.
828  *
829  * Allocates the memory needed for the buffer. Caller is responsible to free
830  * the memory after use.
831  *
832  * Return: 0 on success, negative errno on error.
833  */
kexec_purgatory_setup_kbuf(struct purgatory_info * pi,struct kexec_buf * kbuf)834 static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
835 				      struct kexec_buf *kbuf)
836 {
837 	const Elf_Shdr *sechdrs;
838 	unsigned long bss_align;
839 	unsigned long bss_sz;
840 	unsigned long align;
841 	int i, ret;
842 
843 	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
844 	kbuf->buf_align = bss_align = 1;
845 	kbuf->bufsz = bss_sz = 0;
846 
847 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
848 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
849 			continue;
850 
851 		align = sechdrs[i].sh_addralign;
852 		if (sechdrs[i].sh_type != SHT_NOBITS) {
853 			if (kbuf->buf_align < align)
854 				kbuf->buf_align = align;
855 			kbuf->bufsz = ALIGN(kbuf->bufsz, align);
856 			kbuf->bufsz += sechdrs[i].sh_size;
857 		} else {
858 			if (bss_align < align)
859 				bss_align = align;
860 			bss_sz = ALIGN(bss_sz, align);
861 			bss_sz += sechdrs[i].sh_size;
862 		}
863 	}
864 	kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
865 	kbuf->memsz = kbuf->bufsz + bss_sz;
866 	if (kbuf->buf_align < bss_align)
867 		kbuf->buf_align = bss_align;
868 
869 	kbuf->buffer = vzalloc(kbuf->bufsz);
870 	if (!kbuf->buffer)
871 		return -ENOMEM;
872 	pi->purgatory_buf = kbuf->buffer;
873 
874 	ret = kexec_add_buffer(kbuf);
875 	if (ret)
876 		goto out;
877 
878 	return 0;
879 out:
880 	vfree(pi->purgatory_buf);
881 	pi->purgatory_buf = NULL;
882 	return ret;
883 }
884 
885 /*
886  * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
887  * @pi:		Purgatory to be loaded.
888  * @kbuf:	Buffer prepared to store purgatory.
889  *
890  * Allocates the memory needed for the buffer. Caller is responsible to free
891  * the memory after use.
892  *
893  * Return: 0 on success, negative errno on error.
894  */
kexec_purgatory_setup_sechdrs(struct purgatory_info * pi,struct kexec_buf * kbuf)895 static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
896 					 struct kexec_buf *kbuf)
897 {
898 	unsigned long bss_addr;
899 	unsigned long offset;
900 	size_t sechdrs_size;
901 	Elf_Shdr *sechdrs;
902 	int i;
903 
904 	/*
905 	 * The section headers in kexec_purgatory are read-only. In order to
906 	 * have them modifiable make a temporary copy.
907 	 */
908 	sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
909 	sechdrs = vzalloc(sechdrs_size);
910 	if (!sechdrs)
911 		return -ENOMEM;
912 	memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
913 	pi->sechdrs = sechdrs;
914 
915 	offset = 0;
916 	bss_addr = kbuf->mem + kbuf->bufsz;
917 	kbuf->image->start = pi->ehdr->e_entry;
918 
919 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
920 		unsigned long align;
921 		void *src, *dst;
922 
923 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
924 			continue;
925 
926 		align = sechdrs[i].sh_addralign;
927 		if (sechdrs[i].sh_type == SHT_NOBITS) {
928 			bss_addr = ALIGN(bss_addr, align);
929 			sechdrs[i].sh_addr = bss_addr;
930 			bss_addr += sechdrs[i].sh_size;
931 			continue;
932 		}
933 
934 		offset = ALIGN(offset, align);
935 
936 		/*
937 		 * Check if the segment contains the entry point, if so,
938 		 * calculate the value of image->start based on it.
939 		 * If the compiler has produced more than one .text section
940 		 * (Eg: .text.hot), they are generally after the main .text
941 		 * section, and they shall not be used to calculate
942 		 * image->start. So do not re-calculate image->start if it
943 		 * is not set to the initial value, and warn the user so they
944 		 * have a chance to fix their purgatory's linker script.
945 		 */
946 		if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
947 		    pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
948 		    pi->ehdr->e_entry < (sechdrs[i].sh_addr
949 					 + sechdrs[i].sh_size) &&
950 		    !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) {
951 			kbuf->image->start -= sechdrs[i].sh_addr;
952 			kbuf->image->start += kbuf->mem + offset;
953 		}
954 
955 		src = (void *)pi->ehdr + sechdrs[i].sh_offset;
956 		dst = pi->purgatory_buf + offset;
957 		memcpy(dst, src, sechdrs[i].sh_size);
958 
959 		sechdrs[i].sh_addr = kbuf->mem + offset;
960 		sechdrs[i].sh_offset = offset;
961 		offset += sechdrs[i].sh_size;
962 	}
963 
964 	return 0;
965 }
966 
kexec_apply_relocations(struct kimage * image)967 static int kexec_apply_relocations(struct kimage *image)
968 {
969 	int i, ret;
970 	struct purgatory_info *pi = &image->purgatory_info;
971 	const Elf_Shdr *sechdrs;
972 
973 	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
974 
975 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
976 		const Elf_Shdr *relsec;
977 		const Elf_Shdr *symtab;
978 		Elf_Shdr *section;
979 
980 		relsec = sechdrs + i;
981 
982 		if (relsec->sh_type != SHT_RELA &&
983 		    relsec->sh_type != SHT_REL)
984 			continue;
985 
986 		/*
987 		 * For section of type SHT_RELA/SHT_REL,
988 		 * ->sh_link contains section header index of associated
989 		 * symbol table. And ->sh_info contains section header
990 		 * index of section to which relocations apply.
991 		 */
992 		if (relsec->sh_info >= pi->ehdr->e_shnum ||
993 		    relsec->sh_link >= pi->ehdr->e_shnum)
994 			return -ENOEXEC;
995 
996 		section = pi->sechdrs + relsec->sh_info;
997 		symtab = sechdrs + relsec->sh_link;
998 
999 		if (!(section->sh_flags & SHF_ALLOC))
1000 			continue;
1001 
1002 		/*
1003 		 * symtab->sh_link contain section header index of associated
1004 		 * string table.
1005 		 */
1006 		if (symtab->sh_link >= pi->ehdr->e_shnum)
1007 			/* Invalid section number? */
1008 			continue;
1009 
1010 		/*
1011 		 * Respective architecture needs to provide support for applying
1012 		 * relocations of type SHT_RELA/SHT_REL.
1013 		 */
1014 		if (relsec->sh_type == SHT_RELA)
1015 			ret = arch_kexec_apply_relocations_add(pi, section,
1016 							       relsec, symtab);
1017 		else if (relsec->sh_type == SHT_REL)
1018 			ret = arch_kexec_apply_relocations(pi, section,
1019 							   relsec, symtab);
1020 		if (ret)
1021 			return ret;
1022 	}
1023 
1024 	return 0;
1025 }
1026 
1027 /*
1028  * kexec_load_purgatory - Load and relocate the purgatory object.
1029  * @image:	Image to add the purgatory to.
1030  * @kbuf:	Memory parameters to use.
1031  *
1032  * Allocates the memory needed for image->purgatory_info.sechdrs and
1033  * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
1034  * to free the memory after use.
1035  *
1036  * Return: 0 on success, negative errno on error.
1037  */
kexec_load_purgatory(struct kimage * image,struct kexec_buf * kbuf)1038 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
1039 {
1040 	struct purgatory_info *pi = &image->purgatory_info;
1041 	int ret;
1042 
1043 	if (kexec_purgatory_size <= 0)
1044 		return -EINVAL;
1045 
1046 	pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
1047 
1048 	ret = kexec_purgatory_setup_kbuf(pi, kbuf);
1049 	if (ret)
1050 		return ret;
1051 
1052 	ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
1053 	if (ret)
1054 		goto out_free_kbuf;
1055 
1056 	ret = kexec_apply_relocations(image);
1057 	if (ret)
1058 		goto out;
1059 
1060 	return 0;
1061 out:
1062 	vfree(pi->sechdrs);
1063 	pi->sechdrs = NULL;
1064 out_free_kbuf:
1065 	vfree(pi->purgatory_buf);
1066 	pi->purgatory_buf = NULL;
1067 	return ret;
1068 }
1069 
1070 /*
1071  * kexec_purgatory_find_symbol - find a symbol in the purgatory
1072  * @pi:		Purgatory to search in.
1073  * @name:	Name of the symbol.
1074  *
1075  * Return: pointer to symbol in read-only symtab on success, NULL on error.
1076  */
kexec_purgatory_find_symbol(struct purgatory_info * pi,const char * name)1077 static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
1078 						  const char *name)
1079 {
1080 	const Elf_Shdr *sechdrs;
1081 	const Elf_Ehdr *ehdr;
1082 	const Elf_Sym *syms;
1083 	const char *strtab;
1084 	int i, k;
1085 
1086 	if (!pi->ehdr)
1087 		return NULL;
1088 
1089 	ehdr = pi->ehdr;
1090 	sechdrs = (void *)ehdr + ehdr->e_shoff;
1091 
1092 	for (i = 0; i < ehdr->e_shnum; i++) {
1093 		if (sechdrs[i].sh_type != SHT_SYMTAB)
1094 			continue;
1095 
1096 		if (sechdrs[i].sh_link >= ehdr->e_shnum)
1097 			/* Invalid strtab section number */
1098 			continue;
1099 		strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
1100 		syms = (void *)ehdr + sechdrs[i].sh_offset;
1101 
1102 		/* Go through symbols for a match */
1103 		for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
1104 			if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
1105 				continue;
1106 
1107 			if (strcmp(strtab + syms[k].st_name, name) != 0)
1108 				continue;
1109 
1110 			if (syms[k].st_shndx == SHN_UNDEF ||
1111 			    syms[k].st_shndx >= ehdr->e_shnum) {
1112 				pr_debug("Symbol: %s has bad section index %d.\n",
1113 						name, syms[k].st_shndx);
1114 				return NULL;
1115 			}
1116 
1117 			/* Found the symbol we are looking for */
1118 			return &syms[k];
1119 		}
1120 	}
1121 
1122 	return NULL;
1123 }
1124 
kexec_purgatory_get_symbol_addr(struct kimage * image,const char * name)1125 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
1126 {
1127 	struct purgatory_info *pi = &image->purgatory_info;
1128 	const Elf_Sym *sym;
1129 	Elf_Shdr *sechdr;
1130 
1131 	sym = kexec_purgatory_find_symbol(pi, name);
1132 	if (!sym)
1133 		return ERR_PTR(-EINVAL);
1134 
1135 	sechdr = &pi->sechdrs[sym->st_shndx];
1136 
1137 	/*
1138 	 * Returns the address where symbol will finally be loaded after
1139 	 * kexec_load_segment()
1140 	 */
1141 	return (void *)(sechdr->sh_addr + sym->st_value);
1142 }
1143 
1144 /*
1145  * Get or set value of a symbol. If "get_value" is true, symbol value is
1146  * returned in buf otherwise symbol value is set based on value in buf.
1147  */
kexec_purgatory_get_set_symbol(struct kimage * image,const char * name,void * buf,unsigned int size,bool get_value)1148 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
1149 				   void *buf, unsigned int size, bool get_value)
1150 {
1151 	struct purgatory_info *pi = &image->purgatory_info;
1152 	const Elf_Sym *sym;
1153 	Elf_Shdr *sec;
1154 	char *sym_buf;
1155 
1156 	sym = kexec_purgatory_find_symbol(pi, name);
1157 	if (!sym)
1158 		return -EINVAL;
1159 
1160 	if (sym->st_size != size) {
1161 		pr_err("symbol %s size mismatch: expected %lu actual %u\n",
1162 		       name, (unsigned long)sym->st_size, size);
1163 		return -EINVAL;
1164 	}
1165 
1166 	sec = pi->sechdrs + sym->st_shndx;
1167 
1168 	if (sec->sh_type == SHT_NOBITS) {
1169 		pr_err("symbol %s is in a bss section. Cannot %s\n", name,
1170 		       get_value ? "get" : "set");
1171 		return -EINVAL;
1172 	}
1173 
1174 	sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
1175 
1176 	if (get_value)
1177 		memcpy((void *)buf, sym_buf, size);
1178 	else
1179 		memcpy((void *)sym_buf, buf, size);
1180 
1181 	return 0;
1182 }
1183 #endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */
1184