xref: /linux/block/partitions/cmdline.c (revision 90d32e92011eaae8e70a9169b4e7acf4ca8f9d3a) 
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