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 */ 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 */ 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 */ 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 */ 124 int ima_get_kexec_buffer(void **addr, size_t *size) 125 { 126 int ret, len; 127 unsigned long tmp_addr; 128 size_t tmp_size; 129 const void *prop; 130 131 if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC)) 132 return -ENOTSUPP; 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 *addr = __va(tmp_addr); 143 *size = tmp_size; 144 145 return 0; 146 } 147 148 /** 149 * ima_free_kexec_buffer - free memory used by the IMA buffer 150 */ 151 int ima_free_kexec_buffer(void) 152 { 153 int ret; 154 unsigned long addr; 155 size_t size; 156 struct property *prop; 157 158 if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC)) 159 return -ENOTSUPP; 160 161 prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL); 162 if (!prop) 163 return -ENOENT; 164 165 ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size); 166 if (ret) 167 return ret; 168 169 ret = of_remove_property(of_chosen, prop); 170 if (ret) 171 return ret; 172 173 return memblock_free(addr, size); 174 175 } 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 } 390 391 /* add bootargs */ 392 if (cmdline) { 393 ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline); 394 if (ret) 395 goto out; 396 } else { 397 ret = fdt_delprop(fdt, chosen_node, "bootargs"); 398 if (ret && (ret != -FDT_ERR_NOTFOUND)) 399 goto out; 400 } 401 402 /* add kaslr-seed */ 403 ret = fdt_delprop(fdt, chosen_node, "kaslr-seed"); 404 if (ret == -FDT_ERR_NOTFOUND) 405 ret = 0; 406 else if (ret) 407 goto out; 408 409 if (rng_is_initialized()) { 410 u64 seed = get_random_u64(); 411 412 ret = fdt_setprop_u64(fdt, chosen_node, "kaslr-seed", seed); 413 if (ret) 414 goto out; 415 } else { 416 pr_notice("RNG is not initialised: omitting \"%s\" property\n", 417 "kaslr-seed"); 418 } 419 420 /* add rng-seed */ 421 if (rng_is_initialized()) { 422 void *rng_seed; 423 424 ret = fdt_setprop_placeholder(fdt, chosen_node, "rng-seed", 425 RNG_SEED_SIZE, &rng_seed); 426 if (ret) 427 goto out; 428 get_random_bytes(rng_seed, RNG_SEED_SIZE); 429 } else { 430 pr_notice("RNG is not initialised: omitting \"%s\" property\n", 431 "rng-seed"); 432 } 433 434 ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0); 435 if (ret) 436 goto out; 437 438 remove_ima_buffer(fdt, chosen_node); 439 ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen")); 440 441 out: 442 if (ret) { 443 kvfree(fdt); 444 fdt = NULL; 445 } 446 447 return fdt; 448 } 449