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 info = &state->parts[slot].info;
241
242 strscpy(info->volname, subpart->name, sizeof(info->volname));
243
244 snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
245 strlcat(state->pp_buf, tmp, PAGE_SIZE);
246
247 state->parts[slot].has_info = true;
248
249 return 0;
250 }
251
252 static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
253 struct parsed_partitions *state)
254 {
255 sector_t from = 0;
256 struct cmdline_subpart *subpart;
257 int slot = 1;
258
259 for (subpart = parts->subpart; subpart;
260 subpart = subpart->next_subpart, slot++) {
261 if (subpart->from == (sector_t)(~0ULL))
262 subpart->from = from;
263 else
264 from = subpart->from;
265
266 if (from >= disk_size)
267 break;
268
269 if (subpart->size > (disk_size - from))
270 subpart->size = disk_size - from;
271
272 from += subpart->size;
273
274 if (add_part(slot, subpart, state))
275 break;
276 }
277
278 return slot;
279 }
280
281 static int __init cmdline_parts_setup(char *s)
282 {
283 cmdline = s;
284 return 1;
285 }
286 __setup("blkdevparts=", cmdline_parts_setup);
287
288 static bool has_overlaps(sector_t from, sector_t size,
289 sector_t from2, sector_t size2)
290 {
291 sector_t end = from + size;
292 sector_t end2 = from2 + size2;
293
294 if (from >= from2 && from < end2)
295 return true;
296
297 if (end > from2 && end <= end2)
298 return true;
299
300 if (from2 >= from && from2 < end)
301 return true;
302
303 if (end2 > from && end2 <= end)
304 return true;
305
306 return false;
307 }
308
309 static inline void overlaps_warns_header(void)
310 {
311 pr_warn("Overlapping partitions are used in command line partitions.");
312 pr_warn("Don't use filesystems on overlapping partitions:");
313 }
314
315 static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
316 {
317 int i;
318 bool header = true;
319
320 for (; slot < state->limit && state->parts[slot].has_info; slot++) {
321 for (i = slot+1; i < state->limit && state->parts[i].has_info;
322 i++) {
323 if (has_overlaps(state->parts[slot].from,
324 state->parts[slot].size,
325 state->parts[i].from,
326 state->parts[i].size)) {
327 if (header) {
328 header = false;
329 overlaps_warns_header();
330 }
331 pr_warn("%s[%llu,%llu] overlaps with "
332 "%s[%llu,%llu].",
333 state->parts[slot].info.volname,
334 (u64)state->parts[slot].from << 9,
335 (u64)state->parts[slot].size << 9,
336 state->parts[i].info.volname,
337 (u64)state->parts[i].from << 9,
338 (u64)state->parts[i].size << 9);
339 }
340 }
341 }
342 }
343
344 /*
345 * Purpose: allocate cmdline partitions.
346 * Returns:
347 * -1 if unable to read the partition table
348 * 0 if this isn't our partition table
349 * 1 if successful
350 */
351 int cmdline_partition(struct parsed_partitions *state)
352 {
353 sector_t disk_size;
354 struct cmdline_parts *parts;
355
356 if (cmdline) {
357 if (bdev_parts)
358 cmdline_parts_free(&bdev_parts);
359
360 if (cmdline_parts_parse(&bdev_parts, cmdline)) {
361 cmdline = NULL;
362 return -1;
363 }
364 cmdline = NULL;
365 }
366
367 if (!bdev_parts)
368 return 0;
369
370 parts = cmdline_parts_find(bdev_parts, state->disk->disk_name);
371 if (!parts)
372 return 0;
373
374 disk_size = get_capacity(state->disk) << 9;
375
376 cmdline_parts_set(parts, disk_size, state);
377 cmdline_parts_verifier(1, state);
378
379 strlcat(state->pp_buf, "\n", PAGE_SIZE);
380
381 return 1;
382 }
383
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