summaryrefslogtreecommitdiff
path: root/fs/fs_parser.c
blob: edb3712dcfa5805aa60364bd0c794c257ae04734 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
// SPDX-License-Identifier: GPL-2.0-or-later
/* Filesystem parameter parser.
 *
 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/export.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/slab.h>
#include <linux/security.h>
#include <linux/namei.h>
#include "internal.h"

static const struct constant_table bool_names[] = {
	{ "0",		false },
	{ "1",		true },
	{ "false",	false },
	{ "no",		false },
	{ "true",	true },
	{ "yes",	true },
	{ },
};

static const struct constant_table *
__lookup_constant(const struct constant_table *tbl, const char *name)
{
	for ( ; tbl->name; tbl++)
		if (strcmp(name, tbl->name) == 0)
			return tbl;
	return NULL;
}

/**
 * lookup_constant - Look up a constant by name in an ordered table
 * @tbl: The table of constants to search.
 * @name: The name to look up.
 * @not_found: The value to return if the name is not found.
 */
int lookup_constant(const struct constant_table *tbl, const char *name, int not_found)
{
	const struct constant_table *p = __lookup_constant(tbl, name);

	return p ? p->value : not_found;
}
EXPORT_SYMBOL(lookup_constant);

static inline bool is_flag(const struct fs_parameter_spec *p)
{
	return p->type == NULL;
}

static const struct fs_parameter_spec *fs_lookup_key(
	const struct fs_parameter_spec *desc,
	struct fs_parameter *param, bool *negated)
{
	const struct fs_parameter_spec *p, *other = NULL;
	const char *name = param->key;
	bool want_flag = param->type == fs_value_is_flag;

	*negated = false;
	for (p = desc; p->name; p++) {
		if (strcmp(p->name, name) != 0)
			continue;
		if (likely(is_flag(p) == want_flag))
			return p;
		other = p;
	}
	if (want_flag) {
		if (name[0] == 'n' && name[1] == 'o' && name[2]) {
			for (p = desc; p->name; p++) {
				if (strcmp(p->name, name + 2) != 0)
					continue;
				if (!(p->flags & fs_param_neg_with_no))
					continue;
				*negated = true;
				return p;
			}
		}
	}
	return other;
}

/*
 * fs_parse - Parse a filesystem configuration parameter
 * @fc: The filesystem context to log errors through.
 * @desc: The parameter description to use.
 * @param: The parameter.
 * @result: Where to place the result of the parse
 *
 * Parse a filesystem configuration parameter and attempt a conversion for a
 * simple parameter for which this is requested.  If successful, the determined
 * parameter ID is placed into @result->key, the desired type is indicated in
 * @result->t and any converted value is placed into an appropriate member of
 * the union in @result.
 *
 * The function returns the parameter number if the parameter was matched,
 * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that
 * unknown parameters are okay and -EINVAL if there was a conversion issue or
 * the parameter wasn't recognised and unknowns aren't okay.
 */
int __fs_parse(struct p_log *log,
	     const struct fs_parameter_spec *desc,
	     struct fs_parameter *param,
	     struct fs_parse_result *result)
{
	const struct fs_parameter_spec *p;

	result->uint_64 = 0;

	p = fs_lookup_key(desc, param, &result->negated);
	if (!p)
		return -ENOPARAM;

	if (p->flags & fs_param_deprecated)
		warn_plog(log, "Deprecated parameter '%s'", param->key);

	/* Try to turn the type we were given into the type desired by the
	 * parameter and give an error if we can't.
	 */
	if (is_flag(p)) {
		if (param->type != fs_value_is_flag)
			return inval_plog(log, "Unexpected value for '%s'",
				      param->key);
		result->boolean = !result->negated;
	} else  {
		int ret = p->type(log, p, param, result);
		if (ret)
			return ret;
	}
	return p->opt;
}
EXPORT_SYMBOL(__fs_parse);

/**
 * fs_lookup_param - Look up a path referred to by a parameter
 * @fc: The filesystem context to log errors through.
 * @param: The parameter.
 * @want_bdev: T if want a blockdev
 * @flags: Pathwalk flags passed to filename_lookup()
 * @_path: The result of the lookup
 */
int fs_lookup_param(struct fs_context *fc,
		    struct fs_parameter *param,
		    bool want_bdev,
		    unsigned int flags,
		    struct path *_path)
{
	struct filename *f;
	bool put_f;
	int ret;

	switch (param->type) {
	case fs_value_is_string:
		f = getname_kernel(param->string);
		if (IS_ERR(f))
			return PTR_ERR(f);
		put_f = true;
		break;
	case fs_value_is_filename:
		f = param->name;
		put_f = false;
		break;
	default:
		return invalf(fc, "%s: not usable as path", param->key);
	}

	ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
	if (ret < 0) {
		errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
		goto out;
	}

	if (want_bdev &&
	    !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
		path_put(_path);
		_path->dentry = NULL;
		_path->mnt = NULL;
		errorf(fc, "%s: Non-blockdev passed as '%s'",
		       param->key, f->name);
		ret = -ENOTBLK;
	}

out:
	if (put_f)
		putname(f);
	return ret;
}
EXPORT_SYMBOL(fs_lookup_param);

static int fs_param_bad_value(struct p_log *log, struct fs_parameter *param)
{
	return inval_plog(log, "Bad value for '%s'", param->key);
}

int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p,
		     struct fs_parameter *param, struct fs_parse_result *result)
{
	int b;
	if (param->type != fs_value_is_string)
		return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
		return 0;
	b = lookup_constant(bool_names, param->string, -1);
	if (b == -1)
		return fs_param_bad_value(log, param);
	result->boolean = b;
	return 0;
}
EXPORT_SYMBOL(fs_param_is_bool);

int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p,
		    struct fs_parameter *param, struct fs_parse_result *result)
{
	int base = (unsigned long)p->data;
	if (param->type != fs_value_is_string)
		return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
		return 0;
	if (kstrtouint(param->string, base, &result->uint_32) < 0)
		return fs_param_bad_value(log, param);
	return 0;
}
EXPORT_SYMBOL(fs_param_is_u32);

int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p,
		    struct fs_parameter *param, struct fs_parse_result *result)
{
	if (param->type != fs_value_is_string)
		return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
		return 0;
	if (kstrtoint(param->string, 0, &result->int_32) < 0)
		return fs_param_bad_value(log, param);
	return 0;
}
EXPORT_SYMBOL(fs_param_is_s32);

int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p,
		    struct fs_parameter *param, struct fs_parse_result *result)
{
	if (param->type != fs_value_is_string)
		return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
		return 0;
	if (kstrtoull(param->string, 0, &result->uint_64) < 0)
		return fs_param_bad_value(log, param);
	return 0;
}
EXPORT_SYMBOL(fs_param_is_u64);

int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p,
		     struct fs_parameter *param, struct fs_parse_result *result)
{
	const struct constant_table *c;
	if (param->type != fs_value_is_string)
		return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
		return 0;
	c = __lookup_constant(p->data, param->string);
	if (!c)
		return fs_param_bad_value(log, param);
	result->uint_32 = c->value;
	return 0;
}
EXPORT_SYMBOL(fs_param_is_enum);

int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p,
		       struct fs_parameter *param, struct fs_parse_result *result)
{
	if (param->type != fs_value_is_string ||
	    (!*param->string && !(p->flags & fs_param_can_be_empty)))
		return fs_param_bad_value(log, param);
	return 0;
}
EXPORT_SYMBOL(fs_param_is_string);

int fs_param_is_blob(struct p_log *log, const struct fs_parameter_spec *p,
		     struct fs_parameter *param, struct fs_parse_result *result)
{
	if (param->type != fs_value_is_blob)
		return fs_param_bad_value(log, param);
	return 0;
}
EXPORT_SYMBOL(fs_param_is_blob);

int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p,
		  struct fs_parameter *param, struct fs_parse_result *result)
{
	switch (param->type) {
	case fs_value_is_string:
		if ((!*param->string && !(p->flags & fs_param_can_be_empty)) ||
		    kstrtouint(param->string, 0, &result->uint_32) < 0)
			break;
		if (result->uint_32 <= INT_MAX)
			return 0;
		break;
	case fs_value_is_file:
		result->uint_32 = param->dirfd;
		if (result->uint_32 <= INT_MAX)
			return 0;
		break;
	default:
		break;
	}
	return fs_param_bad_value(log, param);
}
EXPORT_SYMBOL(fs_param_is_fd);

int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,
		  struct fs_parameter *param, struct fs_parse_result *result)
{
	return 0;
}
EXPORT_SYMBOL(fs_param_is_blockdev);

int fs_param_is_path(struct p_log *log, const struct fs_parameter_spec *p,
		     struct fs_parameter *param, struct fs_parse_result *result)
{
	return 0;
}
EXPORT_SYMBOL(fs_param_is_path);

#ifdef CONFIG_VALIDATE_FS_PARSER
/**
 * validate_constant_table - Validate a constant table
 * @tbl: The constant table to validate.
 * @tbl_size: The size of the table.
 * @low: The lowest permissible value.
 * @high: The highest permissible value.
 * @special: One special permissible value outside of the range.
 */
bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
			     int low, int high, int special)
{
	size_t i;
	bool good = true;

	if (tbl_size == 0) {
		pr_warn("VALIDATE C-TBL: Empty\n");
		return true;
	}

	for (i = 0; i < tbl_size; i++) {
		if (!tbl[i].name) {
			pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
			good = false;
		} else if (i > 0 && tbl[i - 1].name) {
			int c = strcmp(tbl[i-1].name, tbl[i].name);

			if (c == 0) {
				pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
				       i, tbl[i].name);
				good = false;
			}
			if (c > 0) {
				pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
				       i, tbl[i-1].name, tbl[i].name);
				good = false;
			}
		}

		if (tbl[i].value != special &&
		    (tbl[i].value < low || tbl[i].value > high)) {
			pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
			       i, tbl[i].name, tbl[i].value, low, high);
			good = false;
		}
	}

	return good;
}

/**
 * fs_validate_description - Validate a parameter description
 * @name: The parameter name to search for.
 * @desc: The parameter description to validate.
 */
bool fs_validate_description(const char *name,
	const struct fs_parameter_spec *desc)
{
	const struct fs_parameter_spec *param, *p2;
	bool good = true;

	for (param = desc; param->name; param++) {
		/* Check for duplicate parameter names */
		for (p2 = desc; p2 < param; p2++) {
			if (strcmp(param->name, p2->name) == 0) {
				if (is_flag(param) != is_flag(p2))
					continue;
				pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
				       name, param->name);
				good = false;
			}
		}
	}
	return good;
}
#endif /* CONFIG_VALIDATE_FS_PARSER */