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
parse_subpart(struct cmdline_subpart ** subpart,char * partdef)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 int length;
74 char *next = strchr(++partdef, ')');
75
76 if (!next) {
77 pr_warn("cmdline partition format is invalid.");
78 ret = -EINVAL;
79 goto fail;
80 }
81
82 length = min_t(int, next - partdef,
83 sizeof(new_subpart->name) - 1);
84 strncpy(new_subpart->name, partdef, length);
85 new_subpart->name[length] = '\0';
86
87 partdef = ++next;
88 } else
89 new_subpart->name[0] = '\0';
90
91 new_subpart->flags = 0;
92
93 if (!strncmp(partdef, "ro", 2)) {
94 new_subpart->flags |= PF_RDONLY;
95 partdef += 2;
96 }
97
98 if (!strncmp(partdef, "lk", 2)) {
99 new_subpart->flags |= PF_POWERUP_LOCK;
100 partdef += 2;
101 }
102
103 *subpart = new_subpart;
104 return 0;
105 fail:
106 kfree(new_subpart);
107 return ret;
108 }
109
free_subpart(struct cmdline_parts * parts)110 static void free_subpart(struct cmdline_parts *parts)
111 {
112 struct cmdline_subpart *subpart;
113
114 while (parts->subpart) {
115 subpart = parts->subpart;
116 parts->subpart = subpart->next_subpart;
117 kfree(subpart);
118 }
119 }
120
parse_parts(struct cmdline_parts ** parts,const char * bdevdef)121 static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
122 {
123 int ret = -EINVAL;
124 char *next;
125 int length;
126 struct cmdline_subpart **next_subpart;
127 struct cmdline_parts *newparts;
128 char buf[BDEVNAME_SIZE + 32 + 4];
129
130 *parts = NULL;
131
132 newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
133 if (!newparts)
134 return -ENOMEM;
135
136 next = strchr(bdevdef, ':');
137 if (!next) {
138 pr_warn("cmdline partition has no block device.");
139 goto fail;
140 }
141
142 length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
143 strncpy(newparts->name, bdevdef, length);
144 newparts->name[length] = '\0';
145 newparts->nr_subparts = 0;
146
147 next_subpart = &newparts->subpart;
148
149 while (next && *(++next)) {
150 bdevdef = next;
151 next = strchr(bdevdef, ',');
152
153 length = (!next) ? (sizeof(buf) - 1) :
154 min_t(int, next - bdevdef, sizeof(buf) - 1);
155
156 strncpy(buf, bdevdef, length);
157 buf[length] = '\0';
158
159 ret = parse_subpart(next_subpart, buf);
160 if (ret)
161 goto fail;
162
163 newparts->nr_subparts++;
164 next_subpart = &(*next_subpart)->next_subpart;
165 }
166
167 if (!newparts->subpart) {
168 pr_warn("cmdline partition has no valid partition.");
169 ret = -EINVAL;
170 goto fail;
171 }
172
173 *parts = newparts;
174
175 return 0;
176 fail:
177 free_subpart(newparts);
178 kfree(newparts);
179 return ret;
180 }
181
cmdline_parts_free(struct cmdline_parts ** parts)182 static void cmdline_parts_free(struct cmdline_parts **parts)
183 {
184 struct cmdline_parts *next_parts;
185
186 while (*parts) {
187 next_parts = (*parts)->next_parts;
188 free_subpart(*parts);
189 kfree(*parts);
190 *parts = next_parts;
191 }
192 }
193
cmdline_parts_parse(struct cmdline_parts ** parts,const char * cmdline)194 static int cmdline_parts_parse(struct cmdline_parts **parts,
195 const char *cmdline)
196 {
197 int ret;
198 char *buf;
199 char *pbuf;
200 char *next;
201 struct cmdline_parts **next_parts;
202
203 *parts = NULL;
204
205 next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
206 if (!buf)
207 return -ENOMEM;
208
209 next_parts = parts;
210
211 while (next && *pbuf) {
212 next = strchr(pbuf, ';');
213 if (next)
214 *next = '\0';
215
216 ret = parse_parts(next_parts, pbuf);
217 if (ret)
218 goto fail;
219
220 if (next)
221 pbuf = ++next;
222
223 next_parts = &(*next_parts)->next_parts;
224 }
225
226 if (!*parts) {
227 pr_warn("cmdline partition has no valid partition.");
228 ret = -EINVAL;
229 goto fail;
230 }
231
232 ret = 0;
233 done:
234 kfree(buf);
235 return ret;
236
237 fail:
238 cmdline_parts_free(parts);
239 goto done;
240 }
241
cmdline_parts_find(struct cmdline_parts * parts,const char * bdev)242 static struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
243 const char *bdev)
244 {
245 while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
246 parts = parts->next_parts;
247 return parts;
248 }
249
250 static char *cmdline;
251 static struct cmdline_parts *bdev_parts;
252
add_part(int slot,struct cmdline_subpart * subpart,struct parsed_partitions * state)253 static int add_part(int slot, struct cmdline_subpart *subpart,
254 struct parsed_partitions *state)
255 {
256 int label_min;
257 struct partition_meta_info *info;
258 char tmp[sizeof(info->volname) + 4];
259
260 if (slot >= state->limit)
261 return 1;
262
263 put_partition(state, slot, subpart->from >> 9,
264 subpart->size >> 9);
265
266 info = &state->parts[slot].info;
267
268 label_min = min_t(int, sizeof(info->volname) - 1,
269 sizeof(subpart->name));
270 strncpy(info->volname, subpart->name, label_min);
271 info->volname[label_min] = '\0';
272
273 snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
274 strlcat(state->pp_buf, tmp, PAGE_SIZE);
275
276 state->parts[slot].has_info = true;
277
278 return 0;
279 }
280
cmdline_parts_set(struct cmdline_parts * parts,sector_t disk_size,struct parsed_partitions * state)281 static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
282 struct parsed_partitions *state)
283 {
284 sector_t from = 0;
285 struct cmdline_subpart *subpart;
286 int slot = 1;
287
288 for (subpart = parts->subpart; subpart;
289 subpart = subpart->next_subpart, slot++) {
290 if (subpart->from == (sector_t)(~0ULL))
291 subpart->from = from;
292 else
293 from = subpart->from;
294
295 if (from >= disk_size)
296 break;
297
298 if (subpart->size > (disk_size - from))
299 subpart->size = disk_size - from;
300
301 from += subpart->size;
302
303 if (add_part(slot, subpart, state))
304 break;
305 }
306
307 return slot;
308 }
309
cmdline_parts_setup(char * s)310 static int __init cmdline_parts_setup(char *s)
311 {
312 cmdline = s;
313 return 1;
314 }
315 __setup("blkdevparts=", cmdline_parts_setup);
316
has_overlaps(sector_t from,sector_t size,sector_t from2,sector_t size2)317 static bool has_overlaps(sector_t from, sector_t size,
318 sector_t from2, sector_t size2)
319 {
320 sector_t end = from + size;
321 sector_t end2 = from2 + size2;
322
323 if (from >= from2 && from < end2)
324 return true;
325
326 if (end > from2 && end <= end2)
327 return true;
328
329 if (from2 >= from && from2 < end)
330 return true;
331
332 if (end2 > from && end2 <= end)
333 return true;
334
335 return false;
336 }
337
overlaps_warns_header(void)338 static inline void overlaps_warns_header(void)
339 {
340 pr_warn("Overlapping partitions are used in command line partitions.");
341 pr_warn("Don't use filesystems on overlapping partitions:");
342 }
343
cmdline_parts_verifier(int slot,struct parsed_partitions * state)344 static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
345 {
346 int i;
347 bool header = true;
348
349 for (; slot < state->limit && state->parts[slot].has_info; slot++) {
350 for (i = slot+1; i < state->limit && state->parts[i].has_info;
351 i++) {
352 if (has_overlaps(state->parts[slot].from,
353 state->parts[slot].size,
354 state->parts[i].from,
355 state->parts[i].size)) {
356 if (header) {
357 header = false;
358 overlaps_warns_header();
359 }
360 pr_warn("%s[%llu,%llu] overlaps with "
361 "%s[%llu,%llu].",
362 state->parts[slot].info.volname,
363 (u64)state->parts[slot].from << 9,
364 (u64)state->parts[slot].size << 9,
365 state->parts[i].info.volname,
366 (u64)state->parts[i].from << 9,
367 (u64)state->parts[i].size << 9);
368 }
369 }
370 }
371 }
372
373 /*
374 * Purpose: allocate cmdline partitions.
375 * Returns:
376 * -1 if unable to read the partition table
377 * 0 if this isn't our partition table
378 * 1 if successful
379 */
cmdline_partition(struct parsed_partitions * state)380 int cmdline_partition(struct parsed_partitions *state)
381 {
382 sector_t disk_size;
383 struct cmdline_parts *parts;
384
385 if (cmdline) {
386 if (bdev_parts)
387 cmdline_parts_free(&bdev_parts);
388
389 if (cmdline_parts_parse(&bdev_parts, cmdline)) {
390 cmdline = NULL;
391 return -1;
392 }
393 cmdline = NULL;
394 }
395
396 if (!bdev_parts)
397 return 0;
398
399 parts = cmdline_parts_find(bdev_parts, state->disk->disk_name);
400 if (!parts)
401 return 0;
402
403 disk_size = get_capacity(state->disk) << 9;
404
405 cmdline_parts_set(parts, disk_size, state);
406 cmdline_parts_verifier(1, state);
407
408 strlcat(state->pp_buf, "\n", PAGE_SIZE);
409
410 return 1;
411 }
412
