317 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Code for looking up block devices in the early boot code before mounting the4 * 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 uuid16 * @dev: device passed in by the caller17 * @data: opaque pointer to the desired struct uuidcmp to match18 *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 UUID34 * @uuid_str: char array containing ascii UUID35 * @devt: dev_t result36 *37 * The function will return the first partition which contains a matching38 * UUID value in its partition_meta_info struct. This does not search39 * by filesystem UUIDs.40 *41 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be42 * 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 offset78 * to the partition number found by UUID.79 */80 *devt = part_devt(dev_to_disk(dev),81 bdev_partno(dev_to_bdev(dev)) + 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 label97 * @dev: device passed in by the caller98 * @data: opaque pointer to the label to match99 *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, even139 * 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 after173 * 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 itself220 * no leading 0x, for example b302.221 * 3) /dev/<disk_name> represents the device number of disk222 * 4) /dev/<disk_name><decimal> represents the device number223 * of partition - device number of disk plus the partition number224 * 5) /dev/<disk_name>p<decimal> - same as the above, that form is225 * used when disk name of partitioned disk ends on a digit.226 * 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the227 * 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 MSDOS229 * partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-230 * filled hex representation of the 32-bit "NT disk signature", and PP231 * is a zero-filled hex representation of the 1-based partition number.232 * 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to233 * a partition with a known unique id.234 * 8) <major>:<minor> major and minor number of the device separated by235 * 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 disk241 * name contains slashes, the device name has them replaced with242 * 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 } else262 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 root269 * filesystem can't be mounted and thus to give the victim some idea of what270 * went wrong271 */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 been286 * suppressed287 */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 in293 * 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 else311 printk(" (driver?)\n");312 }313 rcu_read_unlock();314 }315 class_dev_iter_exit(&iter);316}317