| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * Code for looking up block devices in the early boot code before mounting the |
| 4 | * root file system. |
| 5 | */ |
| 6 | #include <linux/blkdev.h> |
| 7 | #include <linux/ctype.h> |
| 8 | |
| 9 | struct uuidcmp { |
| 10 | const char *uuid; |
| 11 | int len; |
| 12 | }; |
| 13 | |
| 14 | /** |
| 15 | * match_dev_by_uuid - callback for finding a partition using its uuid |
| 16 | * @dev: device passed in by the caller |
| 17 | * @data: opaque pointer to the desired struct uuidcmp to match |
| 18 | * |
| 19 | * Returns 1 if the device matches, and 0 otherwise. |
| 20 | */ |
| 21 | static int __init match_dev_by_uuid(struct device *dev, const void *data) |
| 22 | { |
| 23 | struct block_device *bdev = dev_to_bdev(dev); |
| 24 | const struct uuidcmp *cmp = data; |
| 25 | |
| 26 | if (!bdev->bd_meta_info || |
| 27 | strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len)) |
| 28 | return 0; |
| 29 | return 1; |
| 30 | } |
| 31 | |
| 32 | /** |
| 33 | * devt_from_partuuid - looks up the dev_t of a partition by its UUID |
| 34 | * @uuid_str: char array containing ascii UUID |
| 35 | * @devt: dev_t result |
| 36 | * |
| 37 | * The function will return the first partition which contains a matching |
| 38 | * UUID value in its partition_meta_info struct. This does not search |
| 39 | * by filesystem UUIDs. |
| 40 | * |
| 41 | * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be |
| 42 | * extracted and used as an offset from the partition identified by the UUID. |
| 43 | * |
| 44 | * Returns 0 on success or a negative error code on failure. |
| 45 | */ |
| 46 | static int __init devt_from_partuuid(const char *uuid_str, dev_t *devt) |
| 47 | { |
| 48 | struct uuidcmp cmp; |
| 49 | struct device *dev = NULL; |
| 50 | int offset = 0; |
| 51 | char *slash; |
| 52 | |
| 53 | cmp.uuid = uuid_str; |
| 54 | |
| 55 | slash = strchr(uuid_str, '/'); |
| 56 | /* Check for optional partition number offset attributes. */ |
| 57 | if (slash) { |
| 58 | char c = 0; |
| 59 | |
| 60 | /* Explicitly fail on poor PARTUUID syntax. */ |
| 61 | if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1) |
| 62 | goto out_invalid; |
| 63 | cmp.len = slash - uuid_str; |
| 64 | } else { |
| 65 | cmp.len = strlen(uuid_str); |
| 66 | } |
| 67 | |
| 68 | if (!cmp.len) |
| 69 | goto out_invalid; |
| 70 | |
| 71 | dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid); |
| 72 | if (!dev) |
| 73 | return -ENODEV; |
| 74 | |
| 75 | if (offset) { |
| 76 | /* |
| 77 | * Attempt to find the requested partition by adding an offset |
| 78 | * to the partition number found by UUID. |
| 79 | */ |
| 80 | *devt = part_devt(dev_to_disk(dev), |
| 81 | dev_to_bdev(dev)->bd_partno + offset); |
| 82 | } else { |
| 83 | *devt = dev->devt; |
| 84 | } |
| 85 | |
| 86 | put_device(dev); |
| 87 | return 0; |
| 88 | |
| 89 | out_invalid: |
| 90 | pr_err("VFS: PARTUUID= is invalid.\n" |
| 91 | "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n"); |
| 92 | return -EINVAL; |
| 93 | } |
| 94 | |
| 95 | /** |
| 96 | * match_dev_by_label - callback for finding a partition using its label |
| 97 | * @dev: device passed in by the caller |
| 98 | * @data: opaque pointer to the label to match |
| 99 | * |
| 100 | * Returns 1 if the device matches, and 0 otherwise. |
| 101 | */ |
| 102 | static int __init match_dev_by_label(struct device *dev, const void *data) |
| 103 | { |
| 104 | struct block_device *bdev = dev_to_bdev(dev); |
| 105 | const char *label = data; |
| 106 | |
| 107 | if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname)) |
| 108 | return 0; |
| 109 | return 1; |
| 110 | } |
| 111 | |
| 112 | static int __init devt_from_partlabel(const char *label, dev_t *devt) |
| 113 | { |
| 114 | struct device *dev; |
| 115 | |
| 116 | dev = class_find_device(&block_class, NULL, label, &match_dev_by_label); |
| 117 | if (!dev) |
| 118 | return -ENODEV; |
| 119 | *devt = dev->devt; |
| 120 | put_device(dev); |
| 121 | return 0; |
| 122 | } |
| 123 | |
| 124 | static dev_t __init blk_lookup_devt(const char *name, int partno) |
| 125 | { |
| 126 | dev_t devt = MKDEV(0, 0); |
| 127 | struct class_dev_iter iter; |
| 128 | struct device *dev; |
| 129 | |
| 130 | class_dev_iter_init(&iter, &block_class, NULL, &disk_type); |
| 131 | while ((dev = class_dev_iter_next(&iter))) { |
| 132 | struct gendisk *disk = dev_to_disk(dev); |
| 133 | |
| 134 | if (strcmp(dev_name(dev), name)) |
| 135 | continue; |
| 136 | |
| 137 | if (partno < disk->minors) { |
| 138 | /* We need to return the right devno, even |
| 139 | * if the partition doesn't exist yet. |
| 140 | */ |
| 141 | devt = MKDEV(MAJOR(dev->devt), |
| 142 | MINOR(dev->devt) + partno); |
| 143 | } else { |
| 144 | devt = part_devt(disk, partno); |
| 145 | if (devt) |
| 146 | break; |
| 147 | } |
| 148 | } |
| 149 | class_dev_iter_exit(&iter); |
| 150 | return devt; |
| 151 | } |
| 152 | |
| 153 | static int __init devt_from_devname(const char *name, dev_t *devt) |
| 154 | { |
| 155 | int part; |
| 156 | char s[32]; |
| 157 | char *p; |
| 158 | |
| 159 | if (strlen(name) > 31) |
| 160 | return -EINVAL; |
| 161 | strcpy(s, name); |
| 162 | for (p = s; *p; p++) { |
| 163 | if (*p == '/') |
| 164 | *p = '!'; |
| 165 | } |
| 166 | |
| 167 | *devt = blk_lookup_devt(s, 0); |
| 168 | if (*devt) |
| 169 | return 0; |
| 170 | |
| 171 | /* |
| 172 | * Try non-existent, but valid partition, which may only exist after |
| 173 | * opening the device, like partitioned md devices. |
| 174 | */ |
| 175 | while (p > s && isdigit(p[-1])) |
| 176 | p--; |
| 177 | if (p == s || !*p || *p == '0') |
| 178 | return -ENODEV; |
| 179 | |
| 180 | /* try disk name without <part number> */ |
| 181 | part = simple_strtoul(p, NULL, 10); |
| 182 | *p = '\0'; |
| 183 | *devt = blk_lookup_devt(s, part); |
| 184 | if (*devt) |
| 185 | return 0; |
| 186 | |
| 187 | /* try disk name without p<part number> */ |
| 188 | if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p') |
| 189 | return -ENODEV; |
| 190 | p[-1] = '\0'; |
| 191 | *devt = blk_lookup_devt(s, part); |
| 192 | if (*devt) |
| 193 | return 0; |
| 194 | return -ENODEV; |
| 195 | } |
| 196 | |
| 197 | static int __init devt_from_devnum(const char *name, dev_t *devt) |
| 198 | { |
| 199 | unsigned maj, min, offset; |
| 200 | char *p, dummy; |
| 201 | |
| 202 | if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 || |
| 203 | sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) { |
| 204 | *devt = MKDEV(maj, min); |
| 205 | if (maj != MAJOR(*devt) || min != MINOR(*devt)) |
| 206 | return -EINVAL; |
| 207 | } else { |
| 208 | *devt = new_decode_dev(simple_strtoul(name, &p, 16)); |
| 209 | if (*p) |
| 210 | return -EINVAL; |
| 211 | } |
| 212 | |
| 213 | return 0; |
| 214 | } |
| 215 | |
| 216 | /* |
| 217 | * Convert a name into device number. We accept the following variants: |
| 218 | * |
| 219 | * 1) <hex_major><hex_minor> device number in hexadecimal represents itself |
| 220 | * no leading 0x, for example b302. |
| 221 | * 3) /dev/<disk_name> represents the device number of disk |
| 222 | * 4) /dev/<disk_name><decimal> represents the device number |
| 223 | * of partition - device number of disk plus the partition number |
| 224 | * 5) /dev/<disk_name>p<decimal> - same as the above, that form is |
| 225 | * used when disk name of partitioned disk ends on a digit. |
| 226 | * 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the |
| 227 | * unique id of a partition if the partition table provides it. |
| 228 | * The UUID may be either an EFI/GPT UUID, or refer to an MSDOS |
| 229 | * partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero- |
| 230 | * filled hex representation of the 32-bit "NT disk signature", and PP |
| 231 | * is a zero-filled hex representation of the 1-based partition number. |
| 232 | * 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to |
| 233 | * a partition with a known unique id. |
| 234 | * 8) <major>:<minor> major and minor number of the device separated by |
| 235 | * a colon. |
| 236 | * 9) PARTLABEL=<name> with name being the GPT partition label. |
| 237 | * MSDOS partitions do not support labels! |
| 238 | * |
| 239 | * If name doesn't have fall into the categories above, we return (0,0). |
| 240 | * block_class is used to check if something is a disk name. If the disk |
| 241 | * name contains slashes, the device name has them replaced with |
| 242 | * bangs. |
| 243 | */ |
| 244 | int __init early_lookup_bdev(const char *name, dev_t *devt) |
| 245 | { |
| 246 | if (strncmp(name, "PARTUUID=", 9) == 0) |
| 247 | return devt_from_partuuid(name + 9, devt); |
| 248 | if (strncmp(name, "PARTLABEL=", 10) == 0) |
| 249 | return devt_from_partlabel(name + 10, devt); |
| 250 | if (strncmp(name, "/dev/", 5) == 0) |
| 251 | return devt_from_devname(name + 5, devt); |
| 252 | return devt_from_devnum(name, devt); |
| 253 | } |
| 254 | |
| 255 | static char __init *bdevt_str(dev_t devt, char *buf) |
| 256 | { |
| 257 | if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) { |
| 258 | char tbuf[BDEVT_SIZE]; |
| 259 | snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt)); |
| 260 | snprintf(buf, BDEVT_SIZE, "%-9s", tbuf); |
| 261 | } else |
| 262 | snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt)); |
| 263 | |
| 264 | return buf; |
| 265 | } |
| 266 | |
| 267 | /* |
| 268 | * print a full list of all partitions - intended for places where the root |
| 269 | * filesystem can't be mounted and thus to give the victim some idea of what |
| 270 | * went wrong |
| 271 | */ |
| 272 | void __init printk_all_partitions(void) |
| 273 | { |
| 274 | struct class_dev_iter iter; |
| 275 | struct device *dev; |
| 276 | |
| 277 | class_dev_iter_init(&iter, &block_class, NULL, &disk_type); |
| 278 | while ((dev = class_dev_iter_next(&iter))) { |
| 279 | struct gendisk *disk = dev_to_disk(dev); |
| 280 | struct block_device *part; |
| 281 | char devt_buf[BDEVT_SIZE]; |
| 282 | unsigned long idx; |
| 283 | |
| 284 | /* |
| 285 | * Don't show empty devices or things that have been |
| 286 | * suppressed |
| 287 | */ |
| 288 | if (get_capacity(disk) == 0 || (disk->flags & GENHD_FL_HIDDEN)) |
| 289 | continue; |
| 290 | |
| 291 | /* |
| 292 | * Note, unlike /proc/partitions, I am showing the numbers in |
| 293 | * hex - the same format as the root= option takes. |
| 294 | */ |
| 295 | rcu_read_lock(); |
| 296 | xa_for_each(&disk->part_tbl, idx, part) { |
| 297 | if (!bdev_nr_sectors(part)) |
| 298 | continue; |
| 299 | printk("%s%s %10llu %pg %s", |
| 300 | bdev_is_partition(part) ? " " : "", |
| 301 | bdevt_str(part->bd_dev, devt_buf), |
| 302 | bdev_nr_sectors(part) >> 1, part, |
| 303 | part->bd_meta_info ? |
| 304 | part->bd_meta_info->uuid : ""); |
| 305 | if (bdev_is_partition(part)) |
| 306 | printk("\n"); |
| 307 | else if (dev->parent && dev->parent->driver) |
| 308 | printk(" driver: %s\n", |
| 309 | dev->parent->driver->name); |
| 310 | else |
| 311 | printk(" (driver?)\n"); |
| 312 | } |
| 313 | rcu_read_unlock(); |
| 314 | } |
| 315 | class_dev_iter_exit(&iter); |
| 316 | } |