kexec.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2020 Arm Limited
  4 *
  5 * Based on arch/arm64/kernel/machine_kexec_file.c:
  6 *  Copyright (C) 2018 Linaro Limited
  7 *
  8 * And arch/powerpc/kexec/file_load.c:
  9 *  Copyright (C) 2016  IBM Corporation
 10 */
 11
 12#include <linux/ima.h>
 13#include <linux/kernel.h>
 14#include <linux/kexec.h>
 15#include <linux/memblock.h>
 16#include <linux/libfdt.h>
 17#include <linux/of.h>
 18#include <linux/of_fdt.h>
 19#include <linux/random.h>
 20#include <linux/slab.h>
 21#include <linux/types.h>
 22
 23#define RNG_SEED_SIZE		128
 24
 25/*
 26 * Additional space needed for the FDT buffer so that we can add initrd,
 27 * bootargs, kaslr-seed, rng-seed, useable-memory-range and elfcorehdr.
 28 */
 29#define FDT_EXTRA_SPACE 0x1000
 30
 31/**
 32 * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size
 33 *
 34 * @fdt:	Flattened device tree for the current kernel.
 35 * @start:	Starting address of the reserved memory.
 36 * @size:	Size of the reserved memory.
 37 *
 38 * Return: 0 on success, or negative errno on error.
 39 */
 40static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size)
 41{
 42	int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
 43
 44	for (i = 0; i < num_rsvs; i++) {
 45		u64 rsv_start, rsv_size;
 46
 47		ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
 48		if (ret) {
 49			pr_err("Malformed device tree.\n");
 50			return -EINVAL;
 51		}
 52
 53		if (rsv_start == start && rsv_size == size) {
 54			ret = fdt_del_mem_rsv(fdt, i);
 55			if (ret) {
 56				pr_err("Error deleting device tree reservation.\n");
 57				return -EINVAL;
 58			}
 59
 60			return 0;
 61		}
 62	}
 63
 64	return -ENOENT;
 65}
 66
 67/**
 68 * get_addr_size_cells - Get address and size of root node
 69 *
 70 * @addr_cells: Return address of the root node
 71 * @size_cells: Return size of the root node
 72 *
 73 * Return: 0 on success, or negative errno on error.
 74 */
 75static int get_addr_size_cells(int *addr_cells, int *size_cells)
 76{
 77	struct device_node *root;
 78
 79	root = of_find_node_by_path("/");
 80	if (!root)
 81		return -EINVAL;
 82
 83	*addr_cells = of_n_addr_cells(root);
 84	*size_cells = of_n_size_cells(root);
 85
 86	of_node_put(root);
 87
 88	return 0;
 89}
 90
 91/**
 92 * do_get_kexec_buffer - Get address and size of device tree property
 93 *
 94 * @prop: Device tree property
 95 * @len: Size of @prop
 96 * @addr: Return address of the node
 97 * @size: Return size of the node
 98 *
 99 * Return: 0 on success, or negative errno on error.
100 */
101static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
102			       size_t *size)
103{
104	int ret, addr_cells, size_cells;
105
106	ret = get_addr_size_cells(&addr_cells, &size_cells);
107	if (ret)
108		return ret;
109
110	if (len < 4 * (addr_cells + size_cells))
111		return -ENOENT;
112
113	*addr = of_read_number(prop, addr_cells);
114	*size = of_read_number(prop + 4 * addr_cells, size_cells);
115
116	return 0;
117}
118
119#ifdef CONFIG_HAVE_IMA_KEXEC
120/**
121 * ima_get_kexec_buffer - get IMA buffer from the previous kernel
122 * @addr:	On successful return, set to point to the buffer contents.
123 * @size:	On successful return, set to the buffer size.
124 *
125 * Return: 0 on success, negative errno on error.
126 */
127int __init ima_get_kexec_buffer(void **addr, size_t *size)
128{
129	int ret, len;
130	unsigned long tmp_addr;
131	size_t tmp_size;
132	const void *prop;
133
134	prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
135	if (!prop)
136		return -ENOENT;
137
138	ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
139	if (ret)
140		return ret;
141
142	/* Do some sanity on the returned size for the ima-kexec buffer */
143	if (!tmp_size)
144		return -ENOENT;
145
146	ret = ima_validate_range(tmp_addr, tmp_size);
147	if (ret)
148		return ret;
149
150	*addr = __va(tmp_addr);
151	*size = tmp_size;
152
153	return 0;
154}
155
156/**
157 * ima_free_kexec_buffer - free memory used by the IMA buffer
158 */
159int __init ima_free_kexec_buffer(void)
160{
161	int ret;
162	unsigned long addr;
163	size_t size;
164	struct property *prop;
165
166	prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
167	if (!prop)
168		return -ENOENT;
169
170	ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
171	if (ret)
172		return ret;
173
174	ret = of_remove_property(of_chosen, prop);
175	if (ret)
176		return ret;
177
178	memblock_free_late(addr, size);
179	return 0;
180}
181#endif
182
183/**
184 * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
185 *
186 * @fdt: Flattened Device Tree to update
187 * @chosen_node: Offset to the chosen node in the device tree
188 *
189 * The IMA measurement buffer is of no use to a subsequent kernel, so we always
190 * remove it from the device tree.
191 */
192static void remove_ima_buffer(void *fdt, int chosen_node)
193{
194	int ret, len;
195	unsigned long addr;
196	size_t size;
197	const void *prop;
198
199	if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
200		return;
201
202	prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
203	if (!prop)
204		return;
205
206	ret = do_get_kexec_buffer(prop, len, &addr, &size);
207	fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
208	if (ret)
209		return;
210
211	ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
212	if (!ret)
213		pr_debug("Removed old IMA buffer reservation.\n");
214}
215
216#ifdef CONFIG_IMA_KEXEC
217/**
218 * setup_ima_buffer - add IMA buffer information to the fdt
219 * @image:		kexec image being loaded.
220 * @fdt:		Flattened device tree for the next kernel.
221 * @chosen_node:	Offset to the chosen node.
222 *
223 * Return: 0 on success, or negative errno on error.
224 */
225static int setup_ima_buffer(const struct kimage *image, void *fdt,
226			    int chosen_node)
227{
228	int ret;
229
230	if (!image->ima_buffer_size)
231		return 0;
232
233	ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
234				       "linux,ima-kexec-buffer",
235				       image->ima_buffer_addr,
236				       image->ima_buffer_size);
237	if (ret < 0)
238		return -EINVAL;
239
240	ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
241			      image->ima_buffer_size);
242	if (ret)
243		return -EINVAL;
244
245	pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
246		 image->ima_buffer_addr, image->ima_buffer_size);
247
248	return 0;
249}
250#else /* CONFIG_IMA_KEXEC */
251static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
252				   int chosen_node)
253{
254	return 0;
255}
256#endif /* CONFIG_IMA_KEXEC */
257
258static int kho_add_chosen(const struct kimage *image, void *fdt, int chosen_node)
259{
260	int ret = 0;
261#ifdef CONFIG_KEXEC_HANDOVER
262	phys_addr_t fdt_mem = 0;
263	phys_addr_t fdt_len = 0;
264	phys_addr_t scratch_mem = 0;
265	phys_addr_t scratch_len = 0;
266
267	ret = fdt_delprop(fdt, chosen_node, "linux,kho-fdt");
268	if (ret && ret != -FDT_ERR_NOTFOUND)
269		return ret;
270	ret = fdt_delprop(fdt, chosen_node, "linux,kho-scratch");
271	if (ret && ret != -FDT_ERR_NOTFOUND)
272		return ret;
273
274	if (!image->kho.fdt || !image->kho.scratch)
275		return 0;
276
277	fdt_mem = image->kho.fdt;
278	fdt_len = PAGE_SIZE;
279	scratch_mem = image->kho.scratch->mem;
280	scratch_len = image->kho.scratch->bufsz;
281
282	pr_debug("Adding kho metadata to DT");
283
284	ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-fdt",
285				       fdt_mem, fdt_len);
286	if (ret)
287		return ret;
288	ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-scratch",
289				       scratch_mem, scratch_len);
290
291#endif /* CONFIG_KEXEC_HANDOVER */
292	return ret;
293}
294
295/*
296 * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
297 *
298 * @image:		kexec image being loaded.
299 * @initrd_load_addr:	Address where the next initrd will be loaded.
300 * @initrd_len:		Size of the next initrd, or 0 if there will be none.
301 * @cmdline:		Command line for the next kernel, or NULL if there will
302 *			be none.
303 * @extra_fdt_size:	Additional size for the new FDT buffer.
304 *
305 * Return: fdt on success, or NULL errno on error.
306 */
307void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
308				   unsigned long initrd_load_addr,
309				   unsigned long initrd_len,
310				   const char *cmdline, size_t extra_fdt_size)
311{
312	void *fdt;
313	int ret, chosen_node, len;
314	const void *prop;
315	size_t fdt_size;
316
317	fdt_size = fdt_totalsize(initial_boot_params) +
318		   (cmdline ? strlen(cmdline) : 0) +
319		   FDT_EXTRA_SPACE +
320		   extra_fdt_size;
321	fdt = kvmalloc(fdt_size, GFP_KERNEL);
322	if (!fdt)
323		return NULL;
324
325	ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
326	if (ret < 0) {
327		pr_err("Error %d setting up the new device tree.\n", ret);
328		goto out;
329	}
330
331	/* Remove memory reservation for the current device tree. */
332	ret = fdt_find_and_del_mem_rsv(fdt, initial_boot_params_pa,
333				       fdt_totalsize(initial_boot_params));
334	if (ret == -EINVAL) {
335		pr_err("Error removing memory reservation.\n");
336		goto out;
337	}
338
339	chosen_node = fdt_path_offset(fdt, "/chosen");
340	if (chosen_node == -FDT_ERR_NOTFOUND)
341		chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
342					      "chosen");
343	if (chosen_node < 0) {
344		ret = chosen_node;
345		goto out;
346	}
347
348	ret = fdt_delprop(fdt, chosen_node, "linux,elfcorehdr");
349	if (ret && ret != -FDT_ERR_NOTFOUND)
350		goto out;
351	ret = fdt_delprop(fdt, chosen_node, "linux,usable-memory-range");
352	if (ret && ret != -FDT_ERR_NOTFOUND)
353		goto out;
354
355	/* Did we boot using an initrd? */
356	prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", &len);
357	if (prop) {
358		u64 tmp_start, tmp_end, tmp_size;
359
360		tmp_start = of_read_number(prop, len / 4);
361
362		prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", &len);
363		if (!prop) {
364			ret = -EINVAL;
365			goto out;
366		}
367
368		tmp_end = of_read_number(prop, len / 4);
369
370		/*
371		 * kexec reserves exact initrd size, while firmware may
372		 * reserve a multiple of PAGE_SIZE, so check for both.
373		 */
374		tmp_size = tmp_end - tmp_start;
375		ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
376		if (ret == -ENOENT)
377			ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
378						       round_up(tmp_size, PAGE_SIZE));
379		if (ret == -EINVAL)
380			goto out;
381	}
382
383	/* add initrd-* */
384	if (initrd_load_addr) {
385		ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-start",
386				      initrd_load_addr);
387		if (ret)
388			goto out;
389
390		ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
391				      initrd_load_addr + initrd_len);
392		if (ret)
393			goto out;
394
395		ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
396		if (ret)
397			goto out;
398
399	} else {
400		ret = fdt_delprop(fdt, chosen_node, "linux,initrd-start");
401		if (ret && (ret != -FDT_ERR_NOTFOUND))
402			goto out;
403
404		ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
405		if (ret && (ret != -FDT_ERR_NOTFOUND))
406			goto out;
407	}
408
409	if (image->type == KEXEC_TYPE_CRASH) {
410		/* add linux,elfcorehdr */
411		ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
412				"linux,elfcorehdr", image->elf_load_addr,
413				image->elf_headers_sz);
414		if (ret)
415			goto out;
416
417		/*
418		 * Avoid elfcorehdr from being stomped on in kdump kernel by
419		 * setting up memory reserve map.
420		 */
421		ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
422				      image->elf_headers_sz);
423		if (ret)
424			goto out;
425
426#ifdef CONFIG_CRASH_DUMP
427		/* add linux,usable-memory-range */
428		ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
429				"linux,usable-memory-range", crashk_res.start,
430				crashk_res.end - crashk_res.start + 1);
431		if (ret)
432			goto out;
433
434		if (crashk_low_res.end) {
435			ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
436					"linux,usable-memory-range",
437					crashk_low_res.start,
438					crashk_low_res.end - crashk_low_res.start + 1);
439			if (ret)
440				goto out;
441		}
442#endif
443	}
444
445	/* Add kho metadata if this is a KHO image */
446	ret = kho_add_chosen(image, fdt, chosen_node);
447	if (ret)
448		goto out;
449
450	/* add bootargs */
451	if (cmdline) {
452		ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
453		if (ret)
454			goto out;
455	} else {
456		ret = fdt_delprop(fdt, chosen_node, "bootargs");
457		if (ret && (ret != -FDT_ERR_NOTFOUND))
458			goto out;
459	}
460
461	/* add kaslr-seed */
462	ret = fdt_delprop(fdt, chosen_node, "kaslr-seed");
463	if (ret == -FDT_ERR_NOTFOUND)
464		ret = 0;
465	else if (ret)
466		goto out;
467
468	if (rng_is_initialized()) {
469		u64 seed = get_random_u64();
470
471		ret = fdt_setprop_u64(fdt, chosen_node, "kaslr-seed", seed);
472		if (ret)
473			goto out;
474	} else {
475		pr_notice("RNG is not initialised: omitting \"%s\" property\n",
476			  "kaslr-seed");
477	}
478
479	/* add rng-seed */
480	if (rng_is_initialized()) {
481		void *rng_seed;
482
483		ret = fdt_setprop_placeholder(fdt, chosen_node, "rng-seed",
484				RNG_SEED_SIZE, &rng_seed);
485		if (ret)
486			goto out;
487		get_random_bytes(rng_seed, RNG_SEED_SIZE);
488	} else {
489		pr_notice("RNG is not initialised: omitting \"%s\" property\n",
490			  "rng-seed");
491	}
492
493	ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
494	if (ret)
495		goto out;
496
497	remove_ima_buffer(fdt, chosen_node);
498	ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
499
500out:
501	if (ret) {
502		kvfree(fdt);
503		fdt = NULL;
504	}
505
506	return fdt;
507}