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 */ 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 */ 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 */ 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 */ 127 int __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 */ 159 int __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 */ 192 static 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 */ 225 static 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 */ 251 static 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 */ 257 258 static 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 */ 307 void *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")); 499 500 out: 501 if (ret) { 502 kvfree(fdt); 503 fdt = NULL; 504 } 505 506 return fdt; 507 } 508