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