drivers/of/kexec.c

   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         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  */
 168 int 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         return memblock_free(addr, size);
 191
 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  */
 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  */
 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 */
 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  */
 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;
 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", NULL);
 331         if (prop) {
 332                 u64 tmp_start, tmp_end, tmp_size;
 333
 334                 tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
 335
 336                 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
 337                 if (!prop) {
 338                         ret = -EINVAL;
 339                         goto out;
 340                 }
 341
 342                 tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
 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 }