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
27struct 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
35struct 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
42static 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(ptr: partdef, retptr: &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(ptr: partdef, retptr: &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;
100fail:
101 kfree(objp: new_subpart);
102 return ret;
103}
104
105static 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(objp: subpart);
113 }
114}
115
116static 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(subpart: next_subpart, partdef: 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;
158fail:
159 free_subpart(parts: newparts);
160 kfree(objp: newparts);
161 return ret;
162}
163
164static 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: *parts);
171 kfree(objp: *parts);
172 *parts = next_parts;
173 }
174}
175
176static 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(s: cmdline, GFP_KERNEL);
188 if (!buf)
189 return -ENOMEM;
190
191 next_parts = parts;
192
193 while ((next = strsep(&pbuf, ";"))) {
194 ret = parse_parts(parts: next_parts, bdevdef: 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;
208done:
209 kfree(objp: buf);
210 return ret;
211
212fail:
213 cmdline_parts_free(parts);
214 goto done;
215}
216
217static 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
225static char *cmdline;
226static struct cmdline_parts *bdev_parts;
227
228static 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(p: state, n: slot, from: subpart->from >> 9,
238 size: subpart->size >> 9);
239
240 if (subpart->flags & PF_RDONLY)
241 state->parts[slot].flags |= ADDPART_FLAG_READONLY;
242
243 info = &state->parts[slot].info;
244
245 strscpy(info->volname, subpart->name, sizeof(info->volname));
246
247 snprintf(buf: tmp, size: sizeof(tmp), fmt: "(%s)", info->volname);
248 strlcat(p: state->pp_buf, q: tmp, PAGE_SIZE);
249
250 state->parts[slot].has_info = true;
251
252 return 0;
253}
254
255static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
256 struct parsed_partitions *state)
257{
258 sector_t from = 0;
259 struct cmdline_subpart *subpart;
260 int slot = 1;
261
262 for (subpart = parts->subpart; subpart;
263 subpart = subpart->next_subpart, slot++) {
264 if (subpart->from == (sector_t)(~0ULL))
265 subpart->from = from;
266 else
267 from = subpart->from;
268
269 if (from >= disk_size)
270 break;
271
272 if (subpart->size > (disk_size - from))
273 subpart->size = disk_size - from;
274
275 from += subpart->size;
276
277 if (add_part(slot, subpart, state))
278 break;
279 }
280
281 return slot;
282}
283
284static int __init cmdline_parts_setup(char *s)
285{
286 cmdline = s;
287 return 1;
288}
289__setup("blkdevparts=", cmdline_parts_setup);
290
291static bool has_overlaps(sector_t from, sector_t size,
292 sector_t from2, sector_t size2)
293{
294 sector_t end = from + size;
295 sector_t end2 = from2 + size2;
296
297 if (from >= from2 && from < end2)
298 return true;
299
300 if (end > from2 && end <= end2)
301 return true;
302
303 if (from2 >= from && from2 < end)
304 return true;
305
306 if (end2 > from && end2 <= end)
307 return true;
308
309 return false;
310}
311
312static inline void overlaps_warns_header(void)
313{
314 pr_warn("Overlapping partitions are used in command line partitions.");
315 pr_warn("Don't use filesystems on overlapping partitions:");
316}
317
318static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
319{
320 int i;
321 bool header = true;
322
323 for (; slot < state->limit && state->parts[slot].has_info; slot++) {
324 for (i = slot+1; i < state->limit && state->parts[i].has_info;
325 i++) {
326 if (has_overlaps(from: state->parts[slot].from,
327 size: state->parts[slot].size,
328 from2: state->parts[i].from,
329 size2: state->parts[i].size)) {
330 if (header) {
331 header = false;
332 overlaps_warns_header();
333 }
334 pr_warn("%s[%llu,%llu] overlaps with "
335 "%s[%llu,%llu].",
336 state->parts[slot].info.volname,
337 (u64)state->parts[slot].from << 9,
338 (u64)state->parts[slot].size << 9,
339 state->parts[i].info.volname,
340 (u64)state->parts[i].from << 9,
341 (u64)state->parts[i].size << 9);
342 }
343 }
344 }
345}
346
347/*
348 * Purpose: allocate cmdline partitions.
349 * Returns:
350 * -1 if unable to read the partition table
351 * 0 if this isn't our partition table
352 * 1 if successful
353 */
354int cmdline_partition(struct parsed_partitions *state)
355{
356 sector_t disk_size;
357 struct cmdline_parts *parts;
358
359 if (cmdline) {
360 if (bdev_parts)
361 cmdline_parts_free(parts: &bdev_parts);
362
363 if (cmdline_parts_parse(parts: &bdev_parts, cmdline)) {
364 cmdline = NULL;
365 return -1;
366 }
367 cmdline = NULL;
368 }
369
370 if (!bdev_parts)
371 return 0;
372
373 parts = cmdline_parts_find(parts: bdev_parts, bdev: state->disk->disk_name);
374 if (!parts)
375 return 0;
376
377 disk_size = get_capacity(disk: state->disk) << 9;
378
379 cmdline_parts_set(parts, disk_size, state);
380 cmdline_parts_verifier(slot: 1, state);
381
382 strlcat(p: state->pp_buf, q: "\n", PAGE_SIZE);
383
384 return 1;
385}
386

source code of linux/block/partitions/cmdline.c