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 9struct 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 */ 21static 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 */ 46static 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 89out_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 */ 102static 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 112static 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 124static 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 153static 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 197static 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 */ 244int __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 255static 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 */ 272void __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} 317