Line data Source code
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 0 : static int __init match_dev_by_uuid(struct device *dev, const void *data)
22 : {
23 0 : struct block_device *bdev = dev_to_bdev(dev);
24 0 : const struct uuidcmp *cmp = data;
25 :
26 0 : if (!bdev->bd_meta_info ||
27 0 : 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 0 : static int __init devt_from_partuuid(const char *uuid_str, dev_t *devt)
47 : {
48 : struct uuidcmp cmp;
49 0 : struct device *dev = NULL;
50 0 : int offset = 0;
51 : char *slash;
52 :
53 0 : cmp.uuid = uuid_str;
54 :
55 0 : slash = strchr(uuid_str, '/');
56 : /* Check for optional partition number offset attributes. */
57 0 : if (slash) {
58 0 : char c = 0;
59 :
60 : /* Explicitly fail on poor PARTUUID syntax. */
61 0 : if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
62 : goto out_invalid;
63 0 : cmp.len = slash - uuid_str;
64 : } else {
65 0 : cmp.len = strlen(uuid_str);
66 : }
67 :
68 0 : if (!cmp.len)
69 : goto out_invalid;
70 :
71 0 : dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
72 0 : if (!dev)
73 : return -ENODEV;
74 :
75 0 : if (offset) {
76 : /*
77 : * Attempt to find the requested partition by adding an offset
78 : * to the partition number found by UUID.
79 : */
80 0 : *devt = part_devt(dev_to_disk(dev),
81 0 : dev_to_bdev(dev)->bd_partno + offset);
82 : } else {
83 0 : *devt = dev->devt;
84 : }
85 :
86 0 : put_device(dev);
87 0 : return 0;
88 :
89 : out_invalid:
90 0 : pr_err("VFS: PARTUUID= is invalid.\n"
91 : "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
92 0 : 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 0 : static int __init match_dev_by_label(struct device *dev, const void *data)
103 : {
104 0 : struct block_device *bdev = dev_to_bdev(dev);
105 0 : const char *label = data;
106 :
107 0 : if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
108 : return 0;
109 : return 1;
110 : }
111 :
112 0 : static int __init devt_from_partlabel(const char *label, dev_t *devt)
113 : {
114 : struct device *dev;
115 :
116 0 : dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
117 0 : if (!dev)
118 : return -ENODEV;
119 0 : *devt = dev->devt;
120 0 : put_device(dev);
121 0 : return 0;
122 : }
123 :
124 0 : static dev_t __init blk_lookup_devt(const char *name, int partno)
125 : {
126 0 : dev_t devt = MKDEV(0, 0);
127 : struct class_dev_iter iter;
128 : struct device *dev;
129 :
130 0 : class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
131 0 : while ((dev = class_dev_iter_next(&iter))) {
132 0 : struct gendisk *disk = dev_to_disk(dev);
133 :
134 0 : if (strcmp(dev_name(dev), name))
135 0 : continue;
136 :
137 0 : if (partno < disk->minors) {
138 : /* We need to return the right devno, even
139 : * if the partition doesn't exist yet.
140 : */
141 0 : devt = MKDEV(MAJOR(dev->devt),
142 : MINOR(dev->devt) + partno);
143 : } else {
144 0 : devt = part_devt(disk, partno);
145 0 : if (devt)
146 : break;
147 : }
148 : }
149 0 : class_dev_iter_exit(&iter);
150 0 : return devt;
151 : }
152 :
153 0 : 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 0 : if (strlen(name) > 31)
160 : return -EINVAL;
161 0 : strcpy(s, name);
162 0 : for (p = s; *p; p++) {
163 0 : if (*p == '/')
164 0 : *p = '!';
165 : }
166 :
167 0 : *devt = blk_lookup_devt(s, 0);
168 0 : 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 0 : while (p > s && isdigit(p[-1]))
176 0 : p--;
177 0 : if (p == s || !*p || *p == '0')
178 : return -ENODEV;
179 :
180 : /* try disk name without <part number> */
181 0 : part = simple_strtoul(p, NULL, 10);
182 0 : *p = '\0';
183 0 : *devt = blk_lookup_devt(s, part);
184 0 : if (*devt)
185 : return 0;
186 :
187 : /* try disk name without p<part number> */
188 0 : if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
189 : return -ENODEV;
190 0 : p[-1] = '\0';
191 0 : *devt = blk_lookup_devt(s, part);
192 0 : if (*devt)
193 : return 0;
194 0 : return -ENODEV;
195 : }
196 :
197 0 : static int __init devt_from_devnum(const char *name, dev_t *devt)
198 : {
199 : unsigned maj, min, offset;
200 : char *p, dummy;
201 :
202 0 : if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
203 0 : sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
204 0 : *devt = MKDEV(maj, min);
205 0 : if (maj != MAJOR(*devt) || min != MINOR(*devt))
206 : return -EINVAL;
207 : } else {
208 0 : *devt = new_decode_dev(simple_strtoul(name, &p, 16));
209 0 : 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 0 : int __init early_lookup_bdev(const char *name, dev_t *devt)
245 : {
246 0 : if (strncmp(name, "PARTUUID=", 9) == 0)
247 0 : return devt_from_partuuid(name + 9, devt);
248 0 : if (strncmp(name, "PARTLABEL=", 10) == 0)
249 0 : return devt_from_partlabel(name + 10, devt);
250 0 : if (strncmp(name, "/dev/", 5) == 0)
251 0 : return devt_from_devname(name + 5, devt);
252 0 : return devt_from_devnum(name, devt);
253 : }
254 :
255 0 : static char __init *bdevt_str(dev_t devt, char *buf)
256 : {
257 0 : if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
258 : char tbuf[BDEVT_SIZE];
259 0 : snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
260 0 : snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
261 : } else
262 0 : snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
263 :
264 0 : 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 0 : void __init printk_all_partitions(void)
273 : {
274 : struct class_dev_iter iter;
275 : struct device *dev;
276 :
277 0 : class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
278 0 : while ((dev = class_dev_iter_next(&iter))) {
279 0 : 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 0 : if (get_capacity(disk) == 0 || (disk->flags & GENHD_FL_HIDDEN))
289 0 : 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 0 : xa_for_each(&disk->part_tbl, idx, part) {
297 0 : if (!bdev_nr_sectors(part))
298 0 : continue;
299 0 : 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 0 : if (bdev_is_partition(part))
306 0 : printk("\n");
307 0 : else if (dev->parent && dev->parent->driver)
308 0 : printk(" driver: %s\n",
309 : dev->parent->driver->name);
310 : else
311 0 : printk(" (driver?)\n");
312 : }
313 : rcu_read_unlock();
314 : }
315 0 : class_dev_iter_exit(&iter);
316 0 : }
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