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/slab.h> 20 #include <linux/types.h> 21 22 #define RNG_SEED_SIZE 128 23 24 /* 25 * Additional space needed for the FDT buffer so that we can add initrd, 26 * bootargs, kaslr-seed, rng-seed, useable-memory-range and elfcorehdr. 27 */ 28 #define FDT_EXTRA_SPACE 0x1000 29 30 /** 31 * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size 32 * 33 * @fdt: Flattened device tree for the current kernel. 34 * @start: Starting address of the reserved memory. 35 * @size: Size of the reserved memory. 36 * 37 * Return: 0 on success, or negative errno on error. 38 */ 39 static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size) 40 { 41 int i, ret, num_rsvs = fdt_num_mem_rsv(fdt); 42 43 for (i = 0; i < num_rsvs; i++) { 44 u64 rsv_start, rsv_size; 45 46 ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size); 47 if (ret) { 48 pr_err("Malformed device tree.\n"); 49 return -EINVAL; 50 } 51 52 if (rsv_start == start && rsv_size == size) { 53 ret = fdt_del_mem_rsv(fdt, i); 54 if (ret) { 55 pr_err("Error deleting device tree reservation.\n"); 56 return -EINVAL; 57 } 58 59 return 0; 60 } 61 } 62 63 return -ENOENT; 64 } 65 66 /** 67 * get_addr_size_cells - Get address and size of root node 68 * 69 * @addr_cells: Return address of the root node 70 * @size_cells: Return size of the root node 71 * 72 * Return: 0 on success, or negative errno on error. 73 */ 74 static int get_addr_size_cells(int *addr_cells, int *size_cells) 75 { 76 struct device_node *root; 77 78 root = of_find_node_by_path("/"); 79 if (!root) 80 return -EINVAL; 81 82 *addr_cells = of_n_addr_cells(root); 83 *size_cells = of_n_size_cells(root); 84 85 of_node_put(root); 86 87 return 0; 88 } 89 90 /** 91 * do_get_kexec_buffer - Get address and size of device tree property 92 * 93 * @prop: Device tree property 94 * @len: Size of @prop 95 * @addr: Return address of the node 96 * @size: Return size of the node 97 * 98 * Return: 0 on success, or negative errno on error. 99 */ 100 static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr, 101 size_t *size) 102 { 103 int ret, addr_cells, size_cells; 104 105 ret = get_addr_size_cells(&addr_cells, &size_cells); 106 if (ret) 107 return ret; 108 109 if (len < 4 * (addr_cells + size_cells)) 110 return -ENOENT; 111 112 *addr = of_read_number(prop, addr_cells); 113 *size = of_read_number(prop + 4 * addr_cells, size_cells); 114 115 return 0; 116 } 117 118 /** 119 * ima_get_kexec_buffer - get IMA buffer from the previous kernel 120 * @addr: On successful return, set to point to the buffer contents. 121 * @size: On successful return, set to the buffer size. 122 * 123 * Return: 0 on success, negative errno on error. 124 */ 125 int ima_get_kexec_buffer(void **addr, size_t *size) 126 { 127 int ret, len; 128 unsigned long tmp_addr; 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 *addr = __va(tmp_addr); 144 *size = tmp_size; 145 146 return 0; 147 } 148 149 /** 150 * ima_free_kexec_buffer - free memory used by the IMA buffer 151 */ 152 int ima_free_kexec_buffer(void) 153 { 154 int ret; 155 unsigned long addr; 156 size_t size; 157 struct property *prop; 158 159 if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC)) 160 return -ENOTSUPP; 161 162 prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL); 163 if (!prop) 164 return -ENOENT; 165 166 ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size); 167 if (ret) 168 return ret; 169 170 ret = of_remove_property(of_chosen, prop); 171 if (ret) 172 return ret; 173 174 return memblock_phys_free(addr, size); 175 } 176 177 /** 178 * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt 179 * 180 * @fdt: Flattened Device Tree to update 181 * @chosen_node: Offset to the chosen node in the device tree 182 * 183 * The IMA measurement buffer is of no use to a subsequent kernel, so we always 184 * remove it from the device tree. 185 */ 186 static void remove_ima_buffer(void *fdt, int chosen_node) 187 { 188 int ret, len; 189 unsigned long addr; 190 size_t size; 191 const void *prop; 192 193 if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC)) 194 return; 195 196 prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len); 197 if (!prop) 198 return; 199 200 ret = do_get_kexec_buffer(prop, len, &addr, &size); 201 fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer"); 202 if (ret) 203 return; 204 205 ret = fdt_find_and_del_mem_rsv(fdt, addr, size); 206 if (!ret) 207 pr_debug("Removed old IMA buffer reservation.\n"); 208 } 209 210 #ifdef CONFIG_IMA_KEXEC 211 /** 212 * setup_ima_buffer - add IMA buffer information to the fdt 213 * @image: kexec image being loaded. 214 * @fdt: Flattened device tree for the next kernel. 215 * @chosen_node: Offset to the chosen node. 216 * 217 * Return: 0 on success, or negative errno on error. 218 */ 219 static int setup_ima_buffer(const struct kimage *image, void *fdt, 220 int chosen_node) 221 { 222 int ret; 223 224 if (!image->ima_buffer_size) 225 return 0; 226 227 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, 228 "linux,ima-kexec-buffer", 229 image->ima_buffer_addr, 230 image->ima_buffer_size); 231 if (ret < 0) 232 return -EINVAL; 233 234 ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr, 235 image->ima_buffer_size); 236 if (ret) 237 return -EINVAL; 238 239 pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n", 240 image->ima_buffer_addr, image->ima_buffer_size); 241 242 return 0; 243 } 244 #else /* CONFIG_IMA_KEXEC */ 245 static inline int setup_ima_buffer(const struct kimage *image, void *fdt, 246 int chosen_node) 247 { 248 return 0; 249 } 250 #endif /* CONFIG_IMA_KEXEC */ 251 252 /* 253 * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree 254 * 255 * @image: kexec image being loaded. 256 * @initrd_load_addr: Address where the next initrd will be loaded. 257 * @initrd_len: Size of the next initrd, or 0 if there will be none. 258 * @cmdline: Command line for the next kernel, or NULL if there will 259 * be none. 260 * @extra_fdt_size: Additional size for the new FDT buffer. 261 * 262 * Return: fdt on success, or NULL errno on error. 263 */ 264 void *of_kexec_alloc_and_setup_fdt(const struct kimage *image, 265 unsigned long initrd_load_addr, 266 unsigned long initrd_len, 267 const char *cmdline, size_t extra_fdt_size) 268 { 269 void *fdt; 270 int ret, chosen_node; 271 const void *prop; 272 size_t fdt_size; 273 274 fdt_size = fdt_totalsize(initial_boot_params) + 275 (cmdline ? strlen(cmdline) : 0) + 276 FDT_EXTRA_SPACE + 277 extra_fdt_size; 278 fdt = kvmalloc(fdt_size, GFP_KERNEL); 279 if (!fdt) 280 return NULL; 281 282 ret = fdt_open_into(initial_boot_params, fdt, fdt_size); 283 if (ret < 0) { 284 pr_err("Error %d setting up the new device tree.\n", ret); 285 goto out; 286 } 287 288 /* Remove memory reservation for the current device tree. */ 289 ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params), 290 fdt_totalsize(initial_boot_params)); 291 if (ret == -EINVAL) { 292 pr_err("Error removing memory reservation.\n"); 293 goto out; 294 } 295 296 chosen_node = fdt_path_offset(fdt, "/chosen"); 297 if (chosen_node == -FDT_ERR_NOTFOUND) 298 chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"), 299 "chosen"); 300 if (chosen_node < 0) { 301 ret = chosen_node; 302 goto out; 303 } 304 305 ret = fdt_delprop(fdt, chosen_node, "linux,elfcorehdr"); 306 if (ret && ret != -FDT_ERR_NOTFOUND) 307 goto out; 308 ret = fdt_delprop(fdt, chosen_node, "linux,usable-memory-range"); 309 if (ret && ret != -FDT_ERR_NOTFOUND) 310 goto out; 311 312 /* Did we boot using an initrd? */ 313 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL); 314 if (prop) { 315 u64 tmp_start, tmp_end, tmp_size; 316 317 tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop)); 318 319 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL); 320 if (!prop) { 321 ret = -EINVAL; 322 goto out; 323 } 324 325 tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop)); 326 327 /* 328 * kexec reserves exact initrd size, while firmware may 329 * reserve a multiple of PAGE_SIZE, so check for both. 330 */ 331 tmp_size = tmp_end - tmp_start; 332 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size); 333 if (ret == -ENOENT) 334 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, 335 round_up(tmp_size, PAGE_SIZE)); 336 if (ret == -EINVAL) 337 goto out; 338 } 339 340 /* add initrd-* */ 341 if (initrd_load_addr) { 342 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-start", 343 initrd_load_addr); 344 if (ret) 345 goto out; 346 347 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end", 348 initrd_load_addr + initrd_len); 349 if (ret) 350 goto out; 351 352 ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len); 353 if (ret) 354 goto out; 355 356 } else { 357 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-start"); 358 if (ret && (ret != -FDT_ERR_NOTFOUND)) 359 goto out; 360 361 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end"); 362 if (ret && (ret != -FDT_ERR_NOTFOUND)) 363 goto out; 364 } 365 366 if (image->type == KEXEC_TYPE_CRASH) { 367 /* add linux,elfcorehdr */ 368 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, 369 "linux,elfcorehdr", image->elf_load_addr, 370 image->elf_headers_sz); 371 if (ret) 372 goto out; 373 374 /* 375 * Avoid elfcorehdr from being stomped on in kdump kernel by 376 * setting up memory reserve map. 377 */ 378 ret = fdt_add_mem_rsv(fdt, image->elf_load_addr, 379 image->elf_headers_sz); 380 if (ret) 381 goto out; 382 383 /* add linux,usable-memory-range */ 384 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, 385 "linux,usable-memory-range", crashk_res.start, 386 crashk_res.end - crashk_res.start + 1); 387 if (ret) 388 goto out; 389 390 if (crashk_low_res.end) { 391 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, 392 "linux,usable-memory-range", 393 crashk_low_res.start, 394 crashk_low_res.end - crashk_low_res.start + 1); 395 if (ret) 396 goto out; 397 } 398 } 399 400 /* add bootargs */ 401 if (cmdline) { 402 ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline); 403 if (ret) 404 goto out; 405 } else { 406 ret = fdt_delprop(fdt, chosen_node, "bootargs"); 407 if (ret && (ret != -FDT_ERR_NOTFOUND)) 408 goto out; 409 } 410 411 /* add kaslr-seed */ 412 ret = fdt_delprop(fdt, chosen_node, "kaslr-seed"); 413 if (ret == -FDT_ERR_NOTFOUND) 414 ret = 0; 415 else if (ret) 416 goto out; 417 418 if (rng_is_initialized()) { 419 u64 seed = get_random_u64(); 420 421 ret = fdt_setprop_u64(fdt, chosen_node, "kaslr-seed", seed); 422 if (ret) 423 goto out; 424 } else { 425 pr_notice("RNG is not initialised: omitting \"%s\" property\n", 426 "kaslr-seed"); 427 } 428 429 /* add rng-seed */ 430 if (rng_is_initialized()) { 431 void *rng_seed; 432 433 ret = fdt_setprop_placeholder(fdt, chosen_node, "rng-seed", 434 RNG_SEED_SIZE, &rng_seed); 435 if (ret) 436 goto out; 437 get_random_bytes(rng_seed, RNG_SEED_SIZE); 438 } else { 439 pr_notice("RNG is not initialised: omitting \"%s\" property\n", 440 "rng-seed"); 441 } 442 443 ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0); 444 if (ret) 445 goto out; 446 447 remove_ima_buffer(fdt, chosen_node); 448 ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen")); 449 450 out: 451 if (ret) { 452 kvfree(fdt); 453 fdt = NULL; 454 } 455 456 return fdt; 457 } 458