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/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         unsigned long start_pfn, end_pfn;
 132         size_t tmp_size;
 133         const void *prop;
 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 __init ima_free_kexec_buffer(void)
 169 {
 170         int ret;
 171         unsigned long addr;
 172         size_t size;
 173         struct property *prop;
 174
 175         prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
 176         if (!prop)
 177                 return -ENOENT;
 178
 179         ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
 180         if (ret)
 181                 return ret;
 182
 183         ret = of_remove_property(of_chosen, prop);
 184         if (ret)
 185                 return ret;
 186
 187         memblock_free_late(addr, size);
 188         return 0;
 189 }
 190 #endif
 191
 192 /**
 193  * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
 194  *
 195  * @fdt: Flattened Device Tree to update
 196  * @chosen_node: Offset to the chosen node in the device tree
 197  *
 198  * The IMA measurement buffer is of no use to a subsequent kernel, so we always
 199  * remove it from the device tree.
 200  */
 201 static void remove_ima_buffer(void *fdt, int chosen_node)
 202 {
 203         int ret, len;
 204         unsigned long addr;
 205         size_t size;
 206         const void *prop;
 207
 208         if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
 209                 return;
 210
 211         prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
 212         if (!prop)
 213                 return;
 214
 215         ret = do_get_kexec_buffer(prop, len, &addr, &size);
 216         fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
 217         if (ret)
 218                 return;
 219
 220         ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
 221         if (!ret)
 222                 pr_debug("Removed old IMA buffer reservation.\n");
 223 }
 224
 225 #ifdef CONFIG_IMA_KEXEC
 226 /**
 227  * setup_ima_buffer - add IMA buffer information to the fdt
 228  * @image:              kexec image being loaded.
 229  * @fdt:                Flattened device tree for the next kernel.
 230  * @chosen_node:        Offset to the chosen node.
 231  *
 232  * Return: 0 on success, or negative errno on error.
 233  */
 234 static int setup_ima_buffer(const struct kimage *image, void *fdt,
 235                             int chosen_node)
 236 {
 237         int ret;
 238
 239         if (!image->ima_buffer_size)
 240                 return 0;
 241
 242         ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 243                                        "linux,ima-kexec-buffer",
 244                                        image->ima_buffer_addr,
 245                                        image->ima_buffer_size);
 246         if (ret < 0)
 247                 return -EINVAL;
 248
 249         ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
 250                               image->ima_buffer_size);
 251         if (ret)
 252                 return -EINVAL;
 253
 254         pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
 255                  image->ima_buffer_addr, image->ima_buffer_size);
 256
 257         return 0;
 258 }
 259 #else /* CONFIG_IMA_KEXEC */
 260 static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
 261                                    int chosen_node)
 262 {
 263         return 0;
 264 }
 265 #endif /* CONFIG_IMA_KEXEC */
 266
 267 /*
 268  * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
 269  *
 270  * @image:              kexec image being loaded.
 271  * @initrd_load_addr:   Address where the next initrd will be loaded.
 272  * @initrd_len:         Size of the next initrd, or 0 if there will be none.
 273  * @cmdline:            Command line for the next kernel, or NULL if there will
 274  *                      be none.
 275  * @extra_fdt_size:     Additional size for the new FDT buffer.
 276  *
 277  * Return: fdt on success, or NULL errno on error.
 278  */
 279 void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
 280                                    unsigned long initrd_load_addr,
 281                                    unsigned long initrd_len,
 282                                    const char *cmdline, size_t extra_fdt_size)
 283 {
 284         void *fdt;
 285         int ret, chosen_node, len;
 286         const void *prop;
 287         size_t fdt_size;
 288
 289         fdt_size = fdt_totalsize(initial_boot_params) +
 290                    (cmdline ? strlen(cmdline) : 0) +
 291                    FDT_EXTRA_SPACE +
 292                    extra_fdt_size;
 293         fdt = kvmalloc(fdt_size, GFP_KERNEL);
 294         if (!fdt)
 295                 return NULL;
 296
 297         ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
 298         if (ret < 0) {
 299                 pr_err("Error %d setting up the new device tree.\n", ret);
 300                 goto out;
 301         }
 302
 303         /* Remove memory reservation for the current device tree. */
 304         ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params),
 305                                        fdt_totalsize(initial_boot_params));
 306         if (ret == -EINVAL) {
 307                 pr_err("Error removing memory reservation.\n");
 308                 goto out;
 309         }
 310
 311         chosen_node = fdt_path_offset(fdt, "/chosen");
 312         if (chosen_node == -FDT_ERR_NOTFOUND)
 313                 chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
 314                                               "chosen");
 315         if (chosen_node < 0) {
 316                 ret = chosen_node;
 317                 goto out;
 318         }
 319
 320         ret = fdt_delprop(fdt, chosen_node, "linux,elfcorehdr");
 321         if (ret && ret != -FDT_ERR_NOTFOUND)
 322                 goto out;
 323         ret = fdt_delprop(fdt, chosen_node, "linux,usable-memory-range");
 324         if (ret && ret != -FDT_ERR_NOTFOUND)
 325                 goto out;
 326
 327         /* Did we boot using an initrd? */
 328         prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", &len);
 329         if (prop) {
 330                 u64 tmp_start, tmp_end, tmp_size;
 331
 332                 tmp_start = of_read_number(prop, len / 4);
 333
 334                 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", &len);
 335                 if (!prop) {
 336                         ret = -EINVAL;
 337                         goto out;
 338                 }
 339
 340                 tmp_end = of_read_number(prop, len / 4);
 341
 342                 /*
 343                  * kexec reserves exact initrd size, while firmware may
 344                  * reserve a multiple of PAGE_SIZE, so check for both.
 345                  */
 346                 tmp_size = tmp_end - tmp_start;
 347                 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
 348                 if (ret == -ENOENT)
 349                         ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
 350                                                        round_up(tmp_size, PAGE_SIZE));
 351                 if (ret == -EINVAL)
 352                         goto out;
 353         }
 354
 355         /* add initrd-* */
 356         if (initrd_load_addr) {
 357                 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-start",
 358                                       initrd_load_addr);
 359                 if (ret)
 360                         goto out;
 361
 362                 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
 363                                       initrd_load_addr + initrd_len);
 364                 if (ret)
 365                         goto out;
 366
 367                 ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
 368                 if (ret)
 369                         goto out;
 370
 371         } else {
 372                 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-start");
 373                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 374                         goto out;
 375
 376                 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
 377                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 378                         goto out;
 379         }
 380
 381         if (image->type == KEXEC_TYPE_CRASH) {
 382                 /* add linux,elfcorehdr */
 383                 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 384                                 "linux,elfcorehdr", image->elf_load_addr,
 385                                 image->elf_headers_sz);
 386                 if (ret)
 387                         goto out;
 388
 389                 /*
 390                  * Avoid elfcorehdr from being stomped on in kdump kernel by
 391                  * setting up memory reserve map.
 392                  */
 393                 ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
 394                                       image->elf_headers_sz);
 395                 if (ret)
 396                         goto out;
 397
 398                 /* add linux,usable-memory-range */
 399                 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 400                                 "linux,usable-memory-range", crashk_res.start,
 401                                 crashk_res.end - crashk_res.start + 1);
 402                 if (ret)
 403                         goto out;
 404
 405                 if (crashk_low_res.end) {
 406                         ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 407                                         "linux,usable-memory-range",
 408                                         crashk_low_res.start,
 409                                         crashk_low_res.end - crashk_low_res.start + 1);
 410                         if (ret)
 411                                 goto out;
 412                 }
 413         }
 414
 415         /* add bootargs */
 416         if (cmdline) {
 417                 ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
 418                 if (ret)
 419                         goto out;
 420         } else {
 421                 ret = fdt_delprop(fdt, chosen_node, "bootargs");
 422                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 423                         goto out;
 424         }
 425
 426         /* add kaslr-seed */
 427         ret = fdt_delprop(fdt, chosen_node, "kaslr-seed");
 428         if (ret == -FDT_ERR_NOTFOUND)
 429                 ret = 0;
 430         else if (ret)
 431                 goto out;
 432
 433         if (rng_is_initialized()) {
 434                 u64 seed = get_random_u64();
 435
 436                 ret = fdt_setprop_u64(fdt, chosen_node, "kaslr-seed", seed);
 437                 if (ret)
 438                         goto out;
 439         } else {
 440                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 441                           "kaslr-seed");
 442         }
 443
 444         /* add rng-seed */
 445         if (rng_is_initialized()) {
 446                 void *rng_seed;
 447
 448                 ret = fdt_setprop_placeholder(fdt, chosen_node, "rng-seed",
 449                                 RNG_SEED_SIZE, &rng_seed);
 450                 if (ret)
 451                         goto out;
 452                 get_random_bytes(rng_seed, RNG_SEED_SIZE);
 453         } else {
 454                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 455                           "rng-seed");
 456         }
 457
 458         ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
 459         if (ret)
 460                 goto out;
 461
 462         remove_ima_buffer(fdt, chosen_node);
 463         ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
 464
 465 out:
 466         if (ret) {
 467                 kvfree(fdt);
 468                 fdt = NULL;
 469         }
 470
 471         return fdt;
 472 }