xref: /linux/block/partitions/cmdline.c (revision 1553a1c48281243359a9529a10ddb551f3b967ab) 
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 		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 		strscpy(new_subpart->name, partdef, length);
85 
86 		partdef = ++next;
87 	} else
88 		new_subpart->name[0] = '\0';
89 
90 	new_subpart->flags = 0;
91 
92 	if (!strncmp(partdef, "ro", 2)) {
93 		new_subpart->flags |= PF_RDONLY;
94 		partdef += 2;
95 	}
96 
97 	if (!strncmp(partdef, "lk", 2)) {
98 		new_subpart->flags |= PF_POWERUP_LOCK;
99 		partdef += 2;
100 	}
101 
102 	*subpart = new_subpart;
103 	return 0;
104 fail:
105 	kfree(new_subpart);
106 	return ret;
107 }
108 
109 static void free_subpart(struct cmdline_parts *parts)
110 {
111 	struct cmdline_subpart *subpart;
112 
113 	while (parts->subpart) {
114 		subpart = parts->subpart;
115 		parts->subpart = subpart->next_subpart;
116 		kfree(subpart);
117 	}
118 }
119 
120 static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
121 {
122 	int ret = -EINVAL;
123 	char *next;
124 	int length;
125 	struct cmdline_subpart **next_subpart;
126 	struct cmdline_parts *newparts;
127 	char buf[BDEVNAME_SIZE + 32 + 4];
128 
129 	*parts = NULL;
130 
131 	newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
132 	if (!newparts)
133 		return -ENOMEM;
134 
135 	next = strchr(bdevdef, ':');
136 	if (!next) {
137 		pr_warn("cmdline partition has no block device.");
138 		goto fail;
139 	}
140 
141 	length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
142 	strscpy(newparts->name, bdevdef, length);
143 	newparts->nr_subparts = 0;
144 
145 	next_subpart = &newparts->subpart;
146 
147 	while (next && *(++next)) {
148 		bdevdef = next;
149 		next = strchr(bdevdef, ',');
150 
151 		length = (!next) ? (sizeof(buf) - 1) :
152 			min_t(int, next - bdevdef, sizeof(buf) - 1);
153 
154 		strscpy(buf, bdevdef, length);
155 
156 		ret = parse_subpart(next_subpart, buf);
157 		if (ret)
158 			goto fail;
159 
160 		newparts->nr_subparts++;
161 		next_subpart = &(*next_subpart)->next_subpart;
162 	}
163 
164 	if (!newparts->subpart) {
165 		pr_warn("cmdline partition has no valid partition.");
166 		ret = -EINVAL;
167 		goto fail;
168 	}
169 
170 	*parts = newparts;
171 
172 	return 0;
173 fail:
174 	free_subpart(newparts);
175 	kfree(newparts);
176 	return ret;
177 }
178 
179 static void cmdline_parts_free(struct cmdline_parts **parts)
180 {
181 	struct cmdline_parts *next_parts;
182 
183 	while (*parts) {
184 		next_parts = (*parts)->next_parts;
185 		free_subpart(*parts);
186 		kfree(*parts);
187 		*parts = next_parts;
188 	}
189 }
190 
191 static int cmdline_parts_parse(struct cmdline_parts **parts,
192 		const char *cmdline)
193 {
194 	int ret;
195 	char *buf;
196 	char *pbuf;
197 	char *next;
198 	struct cmdline_parts **next_parts;
199 
200 	*parts = NULL;
201 
202 	next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
203 	if (!buf)
204 		return -ENOMEM;
205 
206 	next_parts = parts;
207 
208 	while (next && *pbuf) {
209 		next = strchr(pbuf, ';');
210 		if (next)
211 			*next = '\0';
212 
213 		ret = parse_parts(next_parts, pbuf);
214 		if (ret)
215 			goto fail;
216 
217 		if (next)
218 			pbuf = ++next;
219 
220 		next_parts = &(*next_parts)->next_parts;
221 	}
222 
223 	if (!*parts) {
224 		pr_warn("cmdline partition has no valid partition.");
225 		ret = -EINVAL;
226 		goto fail;
227 	}
228 
229 	ret = 0;
230 done:
231 	kfree(buf);
232 	return ret;
233 
234 fail:
235 	cmdline_parts_free(parts);
236 	goto done;
237 }
238 
239 static struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
240 					 const char *bdev)
241 {
242 	while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
243 		parts = parts->next_parts;
244 	return parts;
245 }
246 
247 static char *cmdline;
248 static struct cmdline_parts *bdev_parts;
249 
250 static int add_part(int slot, struct cmdline_subpart *subpart,
251 		struct parsed_partitions *state)
252 {
253 	int label_min;
254 	struct partition_meta_info *info;
255 	char tmp[sizeof(info->volname) + 4];
256 
257 	if (slot >= state->limit)
258 		return 1;
259 
260 	put_partition(state, slot, subpart->from >> 9,
261 		      subpart->size >> 9);
262 
263 	info = &state->parts[slot].info;
264 
265 	label_min = min_t(int, sizeof(info->volname) - 1,
266 			  sizeof(subpart->name));
267 	strscpy(info->volname, subpart->name, label_min);
268 
269 	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
270 	strlcat(state->pp_buf, tmp, PAGE_SIZE);
271 
272 	state->parts[slot].has_info = true;
273 
274 	return 0;
275 }
276 
277 static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
278 		struct parsed_partitions *state)
279 {
280 	sector_t from = 0;
281 	struct cmdline_subpart *subpart;
282 	int slot = 1;
283 
284 	for (subpart = parts->subpart; subpart;
285 	     subpart = subpart->next_subpart, slot++) {
286 		if (subpart->from == (sector_t)(~0ULL))
287 			subpart->from = from;
288 		else
289 			from = subpart->from;
290 
291 		if (from >= disk_size)
292 			break;
293 
294 		if (subpart->size > (disk_size - from))
295 			subpart->size = disk_size - from;
296 
297 		from += subpart->size;
298 
299 		if (add_part(slot, subpart, state))
300 			break;
301 	}
302 
303 	return slot;
304 }
305 
306 static int __init cmdline_parts_setup(char *s)
307 {
308 	cmdline = s;
309 	return 1;
310 }
311 __setup("blkdevparts=", cmdline_parts_setup);
312 
313 static bool has_overlaps(sector_t from, sector_t size,
314 			 sector_t from2, sector_t size2)
315 {
316 	sector_t end = from + size;
317 	sector_t end2 = from2 + size2;
318 
319 	if (from >= from2 && from < end2)
320 		return true;
321 
322 	if (end > from2 && end <= end2)
323 		return true;
324 
325 	if (from2 >= from && from2 < end)
326 		return true;
327 
328 	if (end2 > from && end2 <= end)
329 		return true;
330 
331 	return false;
332 }
333 
334 static inline void overlaps_warns_header(void)
335 {
336 	pr_warn("Overlapping partitions are used in command line partitions.");
337 	pr_warn("Don't use filesystems on overlapping partitions:");
338 }
339 
340 static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
341 {
342 	int i;
343 	bool header = true;
344 
345 	for (; slot < state->limit && state->parts[slot].has_info; slot++) {
346 		for (i = slot+1; i < state->limit && state->parts[i].has_info;
347 		     i++) {
348 			if (has_overlaps(state->parts[slot].from,
349 					 state->parts[slot].size,
350 					 state->parts[i].from,
351 					 state->parts[i].size)) {
352 				if (header) {
353 					header = false;
354 					overlaps_warns_header();
355 				}
356 				pr_warn("%s[%llu,%llu] overlaps with "
357 					"%s[%llu,%llu].",
358 					state->parts[slot].info.volname,
359 					(u64)state->parts[slot].from << 9,
360 					(u64)state->parts[slot].size << 9,
361 					state->parts[i].info.volname,
362 					(u64)state->parts[i].from << 9,
363 					(u64)state->parts[i].size << 9);
364 			}
365 		}
366 	}
367 }
368 
369 /*
370  * Purpose: allocate cmdline partitions.
371  * Returns:
372  * -1 if unable to read the partition table
373  *  0 if this isn't our partition table
374  *  1 if successful
375  */
376 int cmdline_partition(struct parsed_partitions *state)
377 {
378 	sector_t disk_size;
379 	struct cmdline_parts *parts;
380 
381 	if (cmdline) {
382 		if (bdev_parts)
383 			cmdline_parts_free(&bdev_parts);
384 
385 		if (cmdline_parts_parse(&bdev_parts, cmdline)) {
386 			cmdline = NULL;
387 			return -1;
388 		}
389 		cmdline = NULL;
390 	}
391 
392 	if (!bdev_parts)
393 		return 0;
394 
395 	parts = cmdline_parts_find(bdev_parts, state->disk->disk_name);
396 	if (!parts)
397 		return 0;
398 
399 	disk_size = get_capacity(state->disk) << 9;
400 
401 	cmdline_parts_set(parts, disk_size, state);
402 	cmdline_parts_verifier(1, state);
403 
404 	strlcat(state->pp_buf, "\n", PAGE_SIZE);
405 
406 	return 1;
407 }
408