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 */
fdt_find_and_del_mem_rsv(void * fdt,unsigned long start,unsigned long size)40 static 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 */
get_addr_size_cells(int * addr_cells,int * size_cells)75 static 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 */
do_get_kexec_buffer(const void * prop,int len,unsigned long * addr,size_t * size)101 static 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 */
ima_get_kexec_buffer(void ** addr,size_t * size)127 int __init ima_get_kexec_buffer(void **addr, size_t *size)
128 {
129 int ret, len;
130 unsigned long tmp_addr;
131 unsigned long start_pfn, end_pfn;
132 size_t tmp_size;
133 const void *prop;
134
135 prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
136 if (!prop)
137 return -ENOENT;
138
139 ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
140 if (ret)
141 return ret;
142
143 /* Do some sanity on the returned size for the ima-kexec buffer */
144 if (!tmp_size)
145 return -ENOENT;
146
147 /*
148 * Calculate the PFNs for the buffer and ensure
149 * they are with in addressable memory.
150 */
151 start_pfn = PHYS_PFN(tmp_addr);
152 end_pfn = PHYS_PFN(tmp_addr + tmp_size - 1);
153 if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn)) {
154 pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n",
155 tmp_addr, tmp_size);
156 return -EINVAL;
157 }
158
159 *addr = __va(tmp_addr);
160 *size = tmp_size;
161
162 return 0;
163 }
164
165 /**
166 * ima_free_kexec_buffer - free memory used by the IMA buffer
167 */
ima_free_kexec_buffer(void)168 int __init ima_free_kexec_buffer(void)
169 {
170 int ret;
171 unsigned long addr;
172 size_t size;
173 struct property *prop;
174
175 prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
176 if (!prop)
177 return -ENOENT;
178
179 ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
180 if (ret)
181 return ret;
182
183 ret = of_remove_property(of_chosen, prop);
184 if (ret)
185 return ret;
186
187 memblock_free_late(addr, size);
188 return 0;
189 }
190 #endif
191
192 /**
193 * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
194 *
195 * @fdt: Flattened Device Tree to update
196 * @chosen_node: Offset to the chosen node in the device tree
197 *
198 * The IMA measurement buffer is of no use to a subsequent kernel, so we always
199 * remove it from the device tree.
200 */
remove_ima_buffer(void * fdt,int chosen_node)201 static void remove_ima_buffer(void *fdt, int chosen_node)
202 {
203 int ret, len;
204 unsigned long addr;
205 size_t size;
206 const void *prop;
207
208 if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
209 return;
210
211 prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
212 if (!prop)
213 return;
214
215 ret = do_get_kexec_buffer(prop, len, &addr, &size);
216 fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
217 if (ret)
218 return;
219
220 ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
221 if (!ret)
222 pr_debug("Removed old IMA buffer reservation.\n");
223 }
224
225 #ifdef CONFIG_IMA_KEXEC
226 /**
227 * setup_ima_buffer - add IMA buffer information to the fdt
228 * @image: kexec image being loaded.
229 * @fdt: Flattened device tree for the next kernel.
230 * @chosen_node: Offset to the chosen node.
231 *
232 * Return: 0 on success, or negative errno on error.
233 */
setup_ima_buffer(const struct kimage * image,void * fdt,int chosen_node)234 static int setup_ima_buffer(const struct kimage *image, void *fdt,
235 int chosen_node)
236 {
237 int ret;
238
239 if (!image->ima_buffer_size)
240 return 0;
241
242 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
243 "linux,ima-kexec-buffer",
244 image->ima_buffer_addr,
245 image->ima_buffer_size);
246 if (ret < 0)
247 return -EINVAL;
248
249 ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
250 image->ima_buffer_size);
251 if (ret)
252 return -EINVAL;
253
254 pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
255 image->ima_buffer_addr, image->ima_buffer_size);
256
257 return 0;
258 }
259 #else /* CONFIG_IMA_KEXEC */
setup_ima_buffer(const struct kimage * image,void * fdt,int chosen_node)260 static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
261 int chosen_node)
262 {
263 return 0;
264 }
265 #endif /* CONFIG_IMA_KEXEC */
266
kho_add_chosen(const struct kimage * image,void * fdt,int chosen_node)267 static int kho_add_chosen(const struct kimage *image, void *fdt, int chosen_node)
268 {
269 int ret = 0;
270 #ifdef CONFIG_KEXEC_HANDOVER
271 phys_addr_t fdt_mem = 0;
272 phys_addr_t fdt_len = 0;
273 phys_addr_t scratch_mem = 0;
274 phys_addr_t scratch_len = 0;
275
276 ret = fdt_delprop(fdt, chosen_node, "linux,kho-fdt");
277 if (ret && ret != -FDT_ERR_NOTFOUND)
278 return ret;
279 ret = fdt_delprop(fdt, chosen_node, "linux,kho-scratch");
280 if (ret && ret != -FDT_ERR_NOTFOUND)
281 return ret;
282
283 if (!image->kho.fdt || !image->kho.scratch)
284 return 0;
285
286 fdt_mem = image->kho.fdt;
287 fdt_len = PAGE_SIZE;
288 scratch_mem = image->kho.scratch->mem;
289 scratch_len = image->kho.scratch->bufsz;
290
291 pr_debug("Adding kho metadata to DT");
292
293 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-fdt",
294 fdt_mem, fdt_len);
295 if (ret)
296 return ret;
297 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-scratch",
298 scratch_mem, scratch_len);
299
300 #endif /* CONFIG_KEXEC_HANDOVER */
301 return ret;
302 }
303
304 /*
305 * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
306 *
307 * @image: kexec image being loaded.
308 * @initrd_load_addr: Address where the next initrd will be loaded.
309 * @initrd_len: Size of the next initrd, or 0 if there will be none.
310 * @cmdline: Command line for the next kernel, or NULL if there will
311 * be none.
312 * @extra_fdt_size: Additional size for the new FDT buffer.
313 *
314 * Return: fdt on success, or NULL errno on error.
315 */
of_kexec_alloc_and_setup_fdt(const struct kimage * image,unsigned long initrd_load_addr,unsigned long initrd_len,const char * cmdline,size_t extra_fdt_size)316 void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
317 unsigned long initrd_load_addr,
318 unsigned long initrd_len,
319 const char *cmdline, size_t extra_fdt_size)
320 {
321 void *fdt;
322 int ret, chosen_node, len;
323 const void *prop;
324 size_t fdt_size;
325
326 fdt_size = fdt_totalsize(initial_boot_params) +
327 (cmdline ? strlen(cmdline) : 0) +
328 FDT_EXTRA_SPACE +
329 extra_fdt_size;
330 fdt = kvmalloc(fdt_size, GFP_KERNEL);
331 if (!fdt)
332 return NULL;
333
334 ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
335 if (ret < 0) {
336 pr_err("Error %d setting up the new device tree.\n", ret);
337 goto out;
338 }
339
340 /* Remove memory reservation for the current device tree. */
341 ret = fdt_find_and_del_mem_rsv(fdt, initial_boot_params_pa,
342 fdt_totalsize(initial_boot_params));
343 if (ret == -EINVAL) {
344 pr_err("Error removing memory reservation.\n");
345 goto out;
346 }
347
348 chosen_node = fdt_path_offset(fdt, "/chosen");
349 if (chosen_node == -FDT_ERR_NOTFOUND)
350 chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
351 "chosen");
352 if (chosen_node < 0) {
353 ret = chosen_node;
354 goto out;
355 }
356
357 ret = fdt_delprop(fdt, chosen_node, "linux,elfcorehdr");
358 if (ret && ret != -FDT_ERR_NOTFOUND)
359 goto out;
360 ret = fdt_delprop(fdt, chosen_node, "linux,usable-memory-range");
361 if (ret && ret != -FDT_ERR_NOTFOUND)
362 goto out;
363
364 /* Did we boot using an initrd? */
365 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", &len);
366 if (prop) {
367 u64 tmp_start, tmp_end, tmp_size;
368
369 tmp_start = of_read_number(prop, len / 4);
370
371 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", &len);
372 if (!prop) {
373 ret = -EINVAL;
374 goto out;
375 }
376
377 tmp_end = of_read_number(prop, len / 4);
378
379 /*
380 * kexec reserves exact initrd size, while firmware may
381 * reserve a multiple of PAGE_SIZE, so check for both.
382 */
383 tmp_size = tmp_end - tmp_start;
384 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
385 if (ret == -ENOENT)
386 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
387 round_up(tmp_size, PAGE_SIZE));
388 if (ret == -EINVAL)
389 goto out;
390 }
391
392 /* add initrd-* */
393 if (initrd_load_addr) {
394 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-start",
395 initrd_load_addr);
396 if (ret)
397 goto out;
398
399 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
400 initrd_load_addr + initrd_len);
401 if (ret)
402 goto out;
403
404 ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
405 if (ret)
406 goto out;
407
408 } else {
409 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-start");
410 if (ret && (ret != -FDT_ERR_NOTFOUND))
411 goto out;
412
413 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
414 if (ret && (ret != -FDT_ERR_NOTFOUND))
415 goto out;
416 }
417
418 if (image->type == KEXEC_TYPE_CRASH) {
419 /* add linux,elfcorehdr */
420 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
421 "linux,elfcorehdr", image->elf_load_addr,
422 image->elf_headers_sz);
423 if (ret)
424 goto out;
425
426 /*
427 * Avoid elfcorehdr from being stomped on in kdump kernel by
428 * setting up memory reserve map.
429 */
430 ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
431 image->elf_headers_sz);
432 if (ret)
433 goto out;
434
435 #ifdef CONFIG_CRASH_DUMP
436 /* add linux,usable-memory-range */
437 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
438 "linux,usable-memory-range", crashk_res.start,
439 crashk_res.end - crashk_res.start + 1);
440 if (ret)
441 goto out;
442
443 if (crashk_low_res.end) {
444 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
445 "linux,usable-memory-range",
446 crashk_low_res.start,
447 crashk_low_res.end - crashk_low_res.start + 1);
448 if (ret)
449 goto out;
450 }
451 #endif
452 }
453
454 /* Add kho metadata if this is a KHO image */
455 ret = kho_add_chosen(image, fdt, chosen_node);
456 if (ret)
457 goto out;
458
459 /* add bootargs */
460 if (cmdline) {
461 ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
462 if (ret)
463 goto out;
464 } else {
465 ret = fdt_delprop(fdt, chosen_node, "bootargs");
466 if (ret && (ret != -FDT_ERR_NOTFOUND))
467 goto out;
468 }
469
470 /* add kaslr-seed */
471 ret = fdt_delprop(fdt, chosen_node, "kaslr-seed");
472 if (ret == -FDT_ERR_NOTFOUND)
473 ret = 0;
474 else if (ret)
475 goto out;
476
477 if (rng_is_initialized()) {
478 u64 seed = get_random_u64();
479
480 ret = fdt_setprop_u64(fdt, chosen_node, "kaslr-seed", seed);
481 if (ret)
482 goto out;
483 } else {
484 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
485 "kaslr-seed");
486 }
487
488 /* add rng-seed */
489 if (rng_is_initialized()) {
490 void *rng_seed;
491
492 ret = fdt_setprop_placeholder(fdt, chosen_node, "rng-seed",
493 RNG_SEED_SIZE, &rng_seed);
494 if (ret)
495 goto out;
496 get_random_bytes(rng_seed, RNG_SEED_SIZE);
497 } else {
498 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
499 "rng-seed");
500 }
501
502 ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
503 if (ret)
504 goto out;
505
506 remove_ima_buffer(fdt, chosen_node);
507 ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
508
509 out:
510 if (ret) {
511 kvfree(fdt);
512 fdt = NULL;
513 }
514
515 return fdt;
516 }
517