1// SPDX-License-Identifier: GPL-2.0
  2
  3/*
  4 * dm-init.c
  5 * Copyright (C) 2017 The Chromium OS Authors <chromium-os-dev@chromium.org>
  6 *
  7 * This file is released under the GPLv2.
  8 */
  9
 10#include <linux/ctype.h>
 11#include <linux/device.h>
 12#include <linux/device-mapper.h>
 13#include <linux/init.h>
 14#include <linux/list.h>
 15#include <linux/moduleparam.h>
 16
 17#define DM_MSG_PREFIX "init"
 18#define DM_MAX_DEVICES 256
 19#define DM_MAX_TARGETS 256
 20#define DM_MAX_STR_SIZE 4096
 21
 22static char *create;
 23
 24/*
 25 * Format: dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+]
 26 * Table format: <start_sector> <num_sectors> <target_type> <target_args>
 27 *
 28 * See Documentation/admin-guide/device-mapper/dm-init.rst for dm-mod.create="..." format
 29 * details.
 30 */
 31
 32struct dm_device {
 33	struct dm_ioctl dmi;
 34	struct dm_target_spec *table[DM_MAX_TARGETS];
 35	char *target_args_array[DM_MAX_TARGETS];
 36	struct list_head list;
 37};
 38
 39static const char * const dm_allowed_targets[] __initconst = {
 40	"crypt",
 41	"delay",
 42	"linear",
 43	"snapshot-origin",
 44	"striped",
 45	"verity",
 46};
 47
 48static int __init dm_verify_target_type(const char *target)
 49{
 50	unsigned int i;
 51
 52	for (i = 0; i < ARRAY_SIZE(dm_allowed_targets); i++) {
 53		if (!strcmp(dm_allowed_targets[i], target))
 54			return 0;
 55	}
 56	return -EINVAL;
 57}
 58
 59static void __init dm_setup_cleanup(struct list_head *devices)
 60{
 61	struct dm_device *dev, *tmp;
 62	unsigned int i;
 63
 64	list_for_each_entry_safe(dev, tmp, devices, list) {
 65		list_del(&dev->list);
 66		for (i = 0; i < dev->dmi.target_count; i++) {
 67			kfree(dev->table[i]);
 68			kfree(dev->target_args_array[i]);
 69		}
 70		kfree(dev);
 71	}
 72}
 73
 74/**
 75 * str_field_delimit - delimit a string based on a separator char.
 76 * @str: the pointer to the string to delimit.
 77 * @separator: char that delimits the field
 78 *
 79 * Find a @separator and replace it by '\0'.
 80 * Remove leading and trailing spaces.
 81 * Return the remainder string after the @separator.
 82 */
 83static char __init *str_field_delimit(char **str, char separator)
 84{
 85	char *s;
 86
 87	/* TODO: add support for escaped characters */
 88	*str = skip_spaces(*str);
 89	s = strchr(*str, separator);
 90	/* Delimit the field and remove trailing spaces */
 91	if (s)
 92		*s = '\0';
 93	*str = strim(*str);
 94	return s ? ++s : NULL;
 95}
 96
 97/**
 98 * dm_parse_table_entry - parse a table entry
 99 * @dev: device to store the parsed information.
100 * @str: the pointer to a string with the format:
101 *	<start_sector> <num_sectors> <target_type> <target_args>[, ...]
102 *
103 * Return the remainder string after the table entry, i.e, after the comma which
104 * delimits the entry or NULL if reached the end of the string.
105 */
106static char __init *dm_parse_table_entry(struct dm_device *dev, char *str)
107{
108	const unsigned int n = dev->dmi.target_count - 1;
109	struct dm_target_spec *sp;
110	unsigned int i;
111	/* fields:  */
112	char *field[4];
113	char *next;
114
115	field[0] = str;
116	/* Delimit first 3 fields that are separated by space */
117	for (i = 0; i < ARRAY_SIZE(field) - 1; i++) {
118		field[i + 1] = str_field_delimit(&field[i], ' ');
119		if (!field[i + 1])
120			return ERR_PTR(-EINVAL);
121	}
122	/* Delimit last field that can be terminated by comma */
123	next = str_field_delimit(&field[i], ',');
124
125	sp = kzalloc(sizeof(*sp), GFP_KERNEL);
126	if (!sp)
127		return ERR_PTR(-ENOMEM);
128	dev->table[n] = sp;
129
130	/* start_sector */
131	if (kstrtoull(field[0], 0, &sp->sector_start))
132		return ERR_PTR(-EINVAL);
133	/* num_sector */
134	if (kstrtoull(field[1], 0, &sp->length))
135		return ERR_PTR(-EINVAL);
136	/* target_type */
137	strscpy(sp->target_type, field[2], sizeof(sp->target_type));
138	if (dm_verify_target_type(sp->target_type)) {
139		DMERR("invalid type \"%s\"", sp->target_type);
140		return ERR_PTR(-EINVAL);
141	}
142	/* target_args */
143	dev->target_args_array[n] = kstrndup(field[3], DM_MAX_STR_SIZE,
144					     GFP_KERNEL);
145	if (!dev->target_args_array[n])
146		return ERR_PTR(-ENOMEM);
147
148	return next;
149}
150
151/**
152 * dm_parse_table - parse "dm-mod.create=" table field
153 * @dev: device to store the parsed information.
154 * @str: the pointer to a string with the format:
155 *	<table>[,<table>+]
156 */
157static int __init dm_parse_table(struct dm_device *dev, char *str)
158{
159	char *table_entry = str;
160
161	while (table_entry) {
162		DMDEBUG("parsing table \"%s\"", str);
163		if (++dev->dmi.target_count > DM_MAX_TARGETS) {
164			DMERR("too many targets %u > %d",
165			      dev->dmi.target_count, DM_MAX_TARGETS);
166			return -EINVAL;
167		}
168		table_entry = dm_parse_table_entry(dev, table_entry);
169		if (IS_ERR(table_entry)) {
170			DMERR("couldn't parse table");
171			return PTR_ERR(table_entry);
172		}
173	}
174
175	return 0;
176}
177
178/**
179 * dm_parse_device_entry - parse a device entry
180 * @dev: device to store the parsed information.
181 * @str: the pointer to a string with the format:
182 *	name,uuid,minor,flags,table[; ...]
183 *
184 * Return the remainder string after the table entry, i.e, after the semi-colon
185 * which delimits the entry or NULL if reached the end of the string.
186 */
187static char __init *dm_parse_device_entry(struct dm_device *dev, char *str)
188{
189	/* There are 5 fields: name,uuid,minor,flags,table; */
190	char *field[5];
191	unsigned int i;
192	char *next;
193
194	field[0] = str;
195	/* Delimit first 4 fields that are separated by comma */
196	for (i = 0; i < ARRAY_SIZE(field) - 1; i++) {
197		field[i+1] = str_field_delimit(&field[i], ',');
198		if (!field[i+1])
199			return ERR_PTR(-EINVAL);
200	}
201	/* Delimit last field that can be delimited by semi-colon */
202	next = str_field_delimit(&field[i], ';');
203
204	/* name */
205	strscpy(dev->dmi.name, field[0], sizeof(dev->dmi.name));
206	/* uuid */
207	strscpy(dev->dmi.uuid, field[1], sizeof(dev->dmi.uuid));
208	/* minor */
209	if (strlen(field[2])) {
210		if (kstrtoull(field[2], 0, &dev->dmi.dev))
211			return ERR_PTR(-EINVAL);
212		dev->dmi.flags |= DM_PERSISTENT_DEV_FLAG;
213	}
214	/* flags */
215	if (!strcmp(field[3], "ro"))
216		dev->dmi.flags |= DM_READONLY_FLAG;
217	else if (strcmp(field[3], "rw"))
218		return ERR_PTR(-EINVAL);
219	/* table */
220	if (dm_parse_table(dev, field[4]))
221		return ERR_PTR(-EINVAL);
222
223	return next;
224}
225
226/**
227 * dm_parse_devices - parse "dm-mod.create=" argument
228 * @devices: list of struct dm_device to store the parsed information.
229 * @str: the pointer to a string with the format:
230 *	<device>[;<device>+]
231 */
232static int __init dm_parse_devices(struct list_head *devices, char *str)
233{
234	unsigned long ndev = 0;
235	struct dm_device *dev;
236	char *device = str;
237
238	DMDEBUG("parsing \"%s\"", str);
239	while (device) {
240		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
241		if (!dev)
242			return -ENOMEM;
243		list_add_tail(&dev->list, devices);
244
245		if (++ndev > DM_MAX_DEVICES) {
246			DMERR("too many devices %lu > %d",
247			      ndev, DM_MAX_DEVICES);
248			return -EINVAL;
249		}
250
251		device = dm_parse_device_entry(dev, device);
252		if (IS_ERR(device)) {
253			DMERR("couldn't parse device");
254			return PTR_ERR(device);
255		}
256	}
257
258	return 0;
259}
260
261/**
262 * dm_init_init - parse "dm-mod.create=" argument and configure drivers
263 */
264static int __init dm_init_init(void)
265{
266	struct dm_device *dev;
267	LIST_HEAD(devices);
268	char *str;
269	int r;
270
271	if (!create)
272		return 0;
273
274	if (strlen(create) >= DM_MAX_STR_SIZE) {
275		DMERR("Argument is too big. Limit is %d", DM_MAX_STR_SIZE);
276		return -EINVAL;
277	}
278	str = kstrndup(create, DM_MAX_STR_SIZE, GFP_KERNEL);
279	if (!str)
280		return -ENOMEM;
281
282	r = dm_parse_devices(&devices, str);
283	if (r)
284		goto out;
285
286	DMINFO("waiting for all devices to be available before creating mapped devices");
287	wait_for_device_probe();
288
289	list_for_each_entry(dev, &devices, list) {
290		if (dm_early_create(&dev->dmi, dev->table,
291				    dev->target_args_array))
292			break;
293	}
294out:
295	kfree(str);
296	dm_setup_cleanup(&devices);
297	return r;
298}
299
300late_initcall(dm_init_init);
301
302module_param(create, charp, 0);
303MODULE_PARM_DESC(create, "Create a mapped device in early boot");