block/partitions/cmdline.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013 HUAWEI
   4  * Author: Cai Zhiyong <caizhiyong@huawei.com>
   5  *
   6  * Read block device partition table from the command line.
   7  * Typically used for fixed block (eMMC) embedded devices.
   8  * It has no MBR, so saves storage space. Bootloader can be easily accessed
   9  * by absolute address of data on the block device.
  10  * Users can easily change the partition.
  11  *
  12  * The format for the command line is just like mtdparts.
  13  *
  14  * For further information, see "Documentation/block/cmdline-partition.rst"
  15  *
  16  */
  17 #include <linux/blkdev.h>
  18 #include <linux/fs.h>
  19 #include <linux/slab.h>
  20 #include "check.h"
  21
  22
  23 /* partition flags */
  24 #define PF_RDONLY                   0x01 /* Device is read only */
  25 #define PF_POWERUP_LOCK             0x02 /* Always locked after reset */
  26
  27 struct cmdline_subpart {
  28         char name[BDEVNAME_SIZE]; /* partition name, such as 'rootfs' */
  29         sector_t from;
  30         sector_t size;
  31         int flags;
  32         struct cmdline_subpart *next_subpart;
  33 };
  34
  35 struct cmdline_parts {
  36         char name[BDEVNAME_SIZE]; /* block device, such as 'mmcblk0' */
  37         unsigned int nr_subparts;
  38         struct cmdline_subpart *subpart;
  39         struct cmdline_parts *next_parts;
  40 };
  41
  42 static int parse_subpart(struct cmdline_subpart **subpart, char *partdef)
  43 {
  44         int ret = 0;
  45         struct cmdline_subpart *new_subpart;
  46
  47         *subpart = NULL;
  48
  49         new_subpart = kzalloc(sizeof(struct cmdline_subpart), GFP_KERNEL);
  50         if (!new_subpart)
  51                 return -ENOMEM;
  52
  53         if (*partdef == '-') {
  54                 new_subpart->size = (sector_t)(~0ULL);
  55                 partdef++;
  56         } else {
  57                 new_subpart->size = (sector_t)memparse(partdef, &partdef);
  58                 if (new_subpart->size < (sector_t)PAGE_SIZE) {
  59                         pr_warn("cmdline partition size is invalid.");
  60                         ret = -EINVAL;
  61                         goto fail;
  62                 }
  63         }
  64
  65         if (*partdef == '@') {
  66                 partdef++;
  67                 new_subpart->from = (sector_t)memparse(partdef, &partdef);
  68         } else {
  69                 new_subpart->from = (sector_t)(~0ULL);
  70         }
  71
  72         if (*partdef == '(') {
  73                 partdef++;
  74                 char *next = strsep(&partdef, ")");
  75
  76                 if (!next) {
  77                         pr_warn("cmdline partition format is invalid.");
  78                         ret = -EINVAL;
  79                         goto fail;
  80                 }
  81
  82                 strscpy(new_subpart->name, next, sizeof(new_subpart->name));
  83         } else
  84                 new_subpart->name[0] = '\0';
  85
  86         new_subpart->flags = 0;
  87
  88         if (!strncmp(partdef, "ro", 2)) {
  89                 new_subpart->flags |= PF_RDONLY;
  90                 partdef += 2;
  91         }
  92
  93         if (!strncmp(partdef, "lk", 2)) {
  94                 new_subpart->flags |= PF_POWERUP_LOCK;
  95                 partdef += 2;
  96         }
  97
  98         *subpart = new_subpart;
  99         return 0;
 100 fail:
 101         kfree(new_subpart);
 102         return ret;
 103 }
 104
 105 static void free_subpart(struct cmdline_parts *parts)
 106 {
 107         struct cmdline_subpart *subpart;
 108
 109         while (parts->subpart) {
 110                 subpart = parts->subpart;
 111                 parts->subpart = subpart->next_subpart;
 112                 kfree(subpart);
 113         }
 114 }
 115
 116 static int parse_parts(struct cmdline_parts **parts, char *bdevdef)
 117 {
 118         int ret = -EINVAL;
 119         char *next;
 120         struct cmdline_subpart **next_subpart;
 121         struct cmdline_parts *newparts;
 122
 123         *parts = NULL;
 124
 125         newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
 126         if (!newparts)
 127                 return -ENOMEM;
 128
 129         next = strsep(&bdevdef, ":");
 130         if (!next) {
 131                 pr_warn("cmdline partition has no block device.");
 132                 goto fail;
 133         }
 134
 135         strscpy(newparts->name, next, sizeof(newparts->name));
 136         newparts->nr_subparts = 0;
 137
 138         next_subpart = &newparts->subpart;
 139
 140         while ((next = strsep(&bdevdef, ","))) {
 141                 ret = parse_subpart(next_subpart, next);
 142                 if (ret)
 143                         goto fail;
 144
 145                 newparts->nr_subparts++;
 146                 next_subpart = &(*next_subpart)->next_subpart;
 147         }
 148
 149         if (!newparts->subpart) {
 150                 pr_warn("cmdline partition has no valid partition.");
 151                 ret = -EINVAL;
 152                 goto fail;
 153         }
 154
 155         *parts = newparts;
 156
 157         return 0;
 158 fail:
 159         free_subpart(newparts);
 160         kfree(newparts);
 161         return ret;
 162 }
 163
 164 static void cmdline_parts_free(struct cmdline_parts **parts)
 165 {
 166         struct cmdline_parts *next_parts;
 167
 168         while (*parts) {
 169                 next_parts = (*parts)->next_parts;
 170                 free_subpart(*parts);
 171                 kfree(*parts);
 172                 *parts = next_parts;
 173         }
 174 }
 175
 176 static int cmdline_parts_parse(struct cmdline_parts **parts,
 177                 const char *cmdline)
 178 {
 179         int ret;
 180         char *buf;
 181         char *pbuf;
 182         char *next;
 183         struct cmdline_parts **next_parts;
 184
 185         *parts = NULL;
 186
 187         pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
 188         if (!buf)
 189                 return -ENOMEM;
 190
 191         next_parts = parts;
 192
 193         while ((next = strsep(&pbuf, ";"))) {
 194                 ret = parse_parts(next_parts, next);
 195                 if (ret)
 196                         goto fail;
 197
 198                 next_parts = &(*next_parts)->next_parts;
 199         }
 200
 201         if (!*parts) {
 202                 pr_warn("cmdline partition has no valid partition.");
 203                 ret = -EINVAL;
 204                 goto fail;
 205         }
 206
 207         ret = 0;
 208 done:
 209         kfree(buf);
 210         return ret;
 211
 212 fail:
 213         cmdline_parts_free(parts);
 214         goto done;
 215 }
 216
 217 static struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
 218                                          const char *bdev)
 219 {
 220         while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
 221                 parts = parts->next_parts;
 222         return parts;
 223 }
 224
 225 static char *cmdline;
 226 static struct cmdline_parts *bdev_parts;
 227
 228 static int add_part(int slot, struct cmdline_subpart *subpart,
 229                 struct parsed_partitions *state)
 230 {
 231         struct partition_meta_info *info;
 232         char tmp[sizeof(info->volname) + 4];
 233
 234         if (slot >= state->limit)
 235                 return 1;
 236
 237         put_partition(state, slot, subpart->from >> 9,
 238                       subpart->size >> 9);
 239
 240         if (subpart->flags & PF_RDONLY)
 241                 state->parts[slot].flags |= ADDPART_FLAG_READONLY;
 242
 243         info = &state->parts[slot].info;
 244
 245         strscpy(info->volname, subpart->name, sizeof(info->volname));
 246
 247         snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
 248         strlcat(state->pp_buf, tmp, PAGE_SIZE);
 249
 250         state->parts[slot].has_info = true;
 251
 252         return 0;
 253 }
 254
 255 static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
 256                 struct parsed_partitions *state)
 257 {
 258         sector_t from = 0;
 259         struct cmdline_subpart *subpart;
 260         int slot = 1;
 261
 262         for (subpart = parts->subpart; subpart;
 263              subpart = subpart->next_subpart, slot++) {
 264                 if (subpart->from == (sector_t)(~0ULL))
 265                         subpart->from = from;
 266                 else
 267                         from = subpart->from;
 268
 269                 if (from >= disk_size)
 270                         break;
 271
 272                 if (subpart->size > (disk_size - from))
 273                         subpart->size = disk_size - from;
 274
 275                 from += subpart->size;
 276
 277                 if (add_part(slot, subpart, state))
 278                         break;
 279         }
 280
 281         return slot;
 282 }
 283
 284 static int __init cmdline_parts_setup(char *s)
 285 {
 286         cmdline = s;
 287         return 1;
 288 }
 289 __setup("blkdevparts=", cmdline_parts_setup);
 290
 291 static bool has_overlaps(sector_t from, sector_t size,
 292                          sector_t from2, sector_t size2)
 293 {
 294         sector_t end = from + size;
 295         sector_t end2 = from2 + size2;
 296
 297         if (from >= from2 && from < end2)
 298                 return true;
 299
 300         if (end > from2 && end <= end2)
 301                 return true;
 302
 303         if (from2 >= from && from2 < end)
 304                 return true;
 305
 306         if (end2 > from && end2 <= end)
 307                 return true;
 308
 309         return false;
 310 }
 311
 312 static inline void overlaps_warns_header(void)
 313 {
 314         pr_warn("Overlapping partitions are used in command line partitions.");
 315         pr_warn("Don't use filesystems on overlapping partitions:");
 316 }
 317
 318 static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
 319 {
 320         int i;
 321         bool header = true;
 322
 323         for (; slot < state->limit && state->parts[slot].has_info; slot++) {
 324                 for (i = slot+1; i < state->limit && state->parts[i].has_info;
 325                      i++) {
 326                         if (has_overlaps(state->parts[slot].from,
 327                                          state->parts[slot].size,
 328                                          state->parts[i].from,
 329                                          state->parts[i].size)) {
 330                                 if (header) {
 331                                         header = false;
 332                                         overlaps_warns_header();
 333                                 }
 334                                 pr_warn("%s[%llu,%llu] overlaps with "
 335                                         "%s[%llu,%llu].",
 336                                         state->parts[slot].info.volname,
 337                                         (u64)state->parts[slot].from << 9,
 338                                         (u64)state->parts[slot].size << 9,
 339                                         state->parts[i].info.volname,
 340                                         (u64)state->parts[i].from << 9,
 341                                         (u64)state->parts[i].size << 9);
 342                         }
 343                 }
 344         }
 345 }
 346
 347 /*
 348  * Purpose: allocate cmdline partitions.
 349  * Returns:
 350  * -1 if unable to read the partition table
 351  *  0 if this isn't our partition table
 352  *  1 if successful
 353  */
 354 int cmdline_partition(struct parsed_partitions *state)
 355 {
 356         sector_t disk_size;
 357         struct cmdline_parts *parts;
 358
 359         if (cmdline) {
 360                 if (bdev_parts)
 361                         cmdline_parts_free(&bdev_parts);
 362
 363                 if (cmdline_parts_parse(&bdev_parts, cmdline)) {
 364                         cmdline = NULL;
 365                         return -1;
 366                 }
 367                 cmdline = NULL;
 368         }
 369
 370         if (!bdev_parts)
 371                 return 0;
 372
 373         parts = cmdline_parts_find(bdev_parts, state->disk->disk_name);
 374         if (!parts)
 375                 return 0;
 376
 377         disk_size = get_capacity(state->disk) << 9;
 378
 379         cmdline_parts_set(parts, disk_size, state);
 380         cmdline_parts_verifier(1, state);
 381
 382         strlcat(state->pp_buf, "\n", PAGE_SIZE);
 383
 384         return 1;
 385 }