xref: /openbmc/linux/block/partitions/cmdline.c (revision d28a1de5) 
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 		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 
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 
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 
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 
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 
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 
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 
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 
310 static int __init cmdline_parts_setup(char *s)
311 {
312 	cmdline = s;
313 	return 1;
314 }
315 __setup("blkdevparts=", cmdline_parts_setup);
316 
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 
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 
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  */
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