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/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 }