1 // SPDX-License-Identifier: GPL-2.0-or-later 1
2 /* Filesystem parameter parser.
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights
5 * Written by David Howells (dhowells@redhat.c
6 */
7
8 #include <linux/export.h>
9 #include <linux/fs_context.h>
10 #include <linux/fs_parser.h>
11 #include <linux/slab.h>
12 #include <linux/security.h>
13 #include <linux/namei.h>
14 #include "internal.h"
15
16 static const struct constant_table bool_names[
17 { "", false },
18 { "1", true },
19 { "false", false },
20 { "no", false },
21 { "true", true },
22 { "yes", true },
23 { },
24 };
25
26 static const struct constant_table *
27 __lookup_constant(const struct constant_table
28 {
29 for ( ; tbl->name; tbl++)
30 if (strcmp(name, tbl->name) ==
31 return tbl;
32 return NULL;
33 }
34
35 /**
36 * lookup_constant - Look up a constant by nam
37 * @tbl: The table of constants to search.
38 * @name: The name to look up.
39 * @not_found: The value to return if the name
40 */
41 int lookup_constant(const struct constant_tabl
42 {
43 const struct constant_table *p = __loo
44
45 return p ? p->value : not_found;
46 }
47 EXPORT_SYMBOL(lookup_constant);
48
49 static inline bool is_flag(const struct fs_par
50 {
51 return p->type == NULL;
52 }
53
54 static const struct fs_parameter_spec *fs_look
55 const struct fs_parameter_spec *desc,
56 struct fs_parameter *param, bool *nega
57 {
58 const struct fs_parameter_spec *p, *ot
59 const char *name = param->key;
60 bool want_flag = param->type == fs_val
61
62 *negated = false;
63 for (p = desc; p->name; p++) {
64 if (strcmp(p->name, name) != 0
65 continue;
66 if (likely(is_flag(p) == want_
67 return p;
68 other = p;
69 }
70 if (want_flag) {
71 if (name[0] == 'n' && name[1]
72 for (p = desc; p->name
73 if (strcmp(p->
74 contin
75 if (!(p->flags
76 contin
77 *negated = tru
78 return p;
79 }
80 }
81 }
82 return other;
83 }
84
85 /*
86 * __fs_parse - Parse a filesystem configurati
87 * @log: The filesystem context to log errors
88 * @desc: The parameter description to use.
89 * @param: The parameter.
90 * @result: Where to place the result of the p
91 *
92 * Parse a filesystem configuration parameter
93 * simple parameter for which this is requeste
94 * parameter ID is placed into @result->key, t
95 * @result->t and any converted value is place
96 * the union in @result.
97 *
98 * The function returns the parameter number i
99 * -ENOPARAM if it wasn't matched and @desc->i
100 * unknown parameters are okay and -EINVAL if
101 * the parameter wasn't recognised and unknown
102 */
103 int __fs_parse(struct p_log *log,
104 const struct fs_parameter_spec *d
105 struct fs_parameter *param,
106 struct fs_parse_result *result)
107 {
108 const struct fs_parameter_spec *p;
109
110 result->uint_64 = 0;
111
112 p = fs_lookup_key(desc, param, &result
113 if (!p)
114 return -ENOPARAM;
115
116 if (p->flags & fs_param_deprecated)
117 warn_plog(log, "Deprecated par
118
119 /* Try to turn the type we were given
120 * parameter and give an error if we c
121 */
122 if (is_flag(p)) {
123 if (param->type != fs_value_is
124 return inval_plog(log,
125 param->k
126 result->boolean = !result->neg
127 } else {
128 int ret = p->type(log, p, para
129 if (ret)
130 return ret;
131 }
132 return p->opt;
133 }
134 EXPORT_SYMBOL(__fs_parse);
135
136 /**
137 * fs_lookup_param - Look up a path referred t
138 * @fc: The filesystem context to log errors t
139 * @param: The parameter.
140 * @want_bdev: T if want a blockdev
141 * @flags: Pathwalk flags passed to filename_l
142 * @_path: The result of the lookup
143 */
144 int fs_lookup_param(struct fs_context *fc,
145 struct fs_parameter *param
146 bool want_bdev,
147 unsigned int flags,
148 struct path *_path)
149 {
150 struct filename *f;
151 bool put_f;
152 int ret;
153
154 switch (param->type) {
155 case fs_value_is_string:
156 f = getname_kernel(param->stri
157 if (IS_ERR(f))
158 return PTR_ERR(f);
159 put_f = true;
160 break;
161 case fs_value_is_filename:
162 f = param->name;
163 put_f = false;
164 break;
165 default:
166 return invalf(fc, "%s: not usa
167 }
168
169 ret = filename_lookup(param->dirfd, f,
170 if (ret < 0) {
171 errorf(fc, "%s: Lookup failure
172 goto out;
173 }
174
175 if (want_bdev &&
176 !S_ISBLK(d_backing_inode(_path->de
177 path_put(_path);
178 _path->dentry = NULL;
179 _path->mnt = NULL;
180 errorf(fc, "%s: Non-blockdev p
181 param->key, f->name);
182 ret = -ENOTBLK;
183 }
184
185 out:
186 if (put_f)
187 putname(f);
188 return ret;
189 }
190 EXPORT_SYMBOL(fs_lookup_param);
191
192 static int fs_param_bad_value(struct p_log *lo
193 {
194 return inval_plog(log, "Bad value for
195 }
196
197 int fs_param_is_bool(struct p_log *log, const
198 struct fs_parameter *para
199 {
200 int b;
201 if (param->type != fs_value_is_string)
202 return fs_param_bad_value(log,
203 if (!*param->string && (p->flags & fs_
204 return 0;
205 b = lookup_constant(bool_names, param-
206 if (b == -1)
207 return fs_param_bad_value(log,
208 result->boolean = b;
209 return 0;
210 }
211 EXPORT_SYMBOL(fs_param_is_bool);
212
213 int fs_param_is_u32(struct p_log *log, const s
214 struct fs_parameter *param
215 {
216 int base = (unsigned long)p->data;
217 if (param->type != fs_value_is_string)
218 return fs_param_bad_value(log,
219 if (!*param->string && (p->flags & fs_
220 return 0;
221 if (kstrtouint(param->string, base, &r
222 return fs_param_bad_value(log,
223 return 0;
224 }
225 EXPORT_SYMBOL(fs_param_is_u32);
226
227 int fs_param_is_s32(struct p_log *log, const s
228 struct fs_parameter *param
229 {
230 if (param->type != fs_value_is_string)
231 return fs_param_bad_value(log,
232 if (!*param->string && (p->flags & fs_
233 return 0;
234 if (kstrtoint(param->string, 0, &resul
235 return fs_param_bad_value(log,
236 return 0;
237 }
238 EXPORT_SYMBOL(fs_param_is_s32);
239
240 int fs_param_is_u64(struct p_log *log, const s
241 struct fs_parameter *param
242 {
243 if (param->type != fs_value_is_string)
244 return fs_param_bad_value(log,
245 if (!*param->string && (p->flags & fs_
246 return 0;
247 if (kstrtoull(param->string, 0, &resul
248 return fs_param_bad_value(log,
249 return 0;
250 }
251 EXPORT_SYMBOL(fs_param_is_u64);
252
253 int fs_param_is_enum(struct p_log *log, const
254 struct fs_parameter *para
255 {
256 const struct constant_table *c;
257 if (param->type != fs_value_is_string)
258 return fs_param_bad_value(log,
259 if (!*param->string && (p->flags & fs_
260 return 0;
261 c = __lookup_constant(p->data, param->
262 if (!c)
263 return fs_param_bad_value(log,
264 result->uint_32 = c->value;
265 return 0;
266 }
267 EXPORT_SYMBOL(fs_param_is_enum);
268
269 int fs_param_is_string(struct p_log *log, cons
270 struct fs_parameter *pa
271 {
272 if (param->type != fs_value_is_string
273 (!*param->string && !(p->flags & f
274 return fs_param_bad_value(log,
275 return 0;
276 }
277 EXPORT_SYMBOL(fs_param_is_string);
278
279 int fs_param_is_blob(struct p_log *log, const
280 struct fs_parameter *para
281 {
282 if (param->type != fs_value_is_blob)
283 return fs_param_bad_value(log,
284 return 0;
285 }
286 EXPORT_SYMBOL(fs_param_is_blob);
287
288 int fs_param_is_fd(struct p_log *log, const st
289 struct fs_parameter *param,
290 {
291 switch (param->type) {
292 case fs_value_is_string:
293 if ((!*param->string && !(p->f
294 kstrtouint(param->string,
295 break;
296 if (result->uint_32 <= INT_MAX
297 return 0;
298 break;
299 case fs_value_is_file:
300 result->uint_32 = param->dirfd
301 if (result->uint_32 <= INT_MAX
302 return 0;
303 break;
304 default:
305 break;
306 }
307 return fs_param_bad_value(log, param);
308 }
309 EXPORT_SYMBOL(fs_param_is_fd);
310
311 int fs_param_is_uid(struct p_log *log, const s
312 struct fs_parameter *param
313 {
314 kuid_t uid;
315
316 if (fs_param_is_u32(log, p, param, res
317 return fs_param_bad_value(log,
318
319 uid = make_kuid(current_user_ns(), res
320 if (!uid_valid(uid))
321 return inval_plog(log, "Invali
322
323 result->uid = uid;
324 return 0;
325 }
326 EXPORT_SYMBOL(fs_param_is_uid);
327
328 int fs_param_is_gid(struct p_log *log, const s
329 struct fs_parameter *param
330 {
331 kgid_t gid;
332
333 if (fs_param_is_u32(log, p, param, res
334 return fs_param_bad_value(log,
335
336 gid = make_kgid(current_user_ns(), res
337 if (!gid_valid(gid))
338 return inval_plog(log, "Invali
339
340 result->gid = gid;
341 return 0;
342 }
343 EXPORT_SYMBOL(fs_param_is_gid);
344
345 int fs_param_is_blockdev(struct p_log *log, co
346 struct fs_parameter *param,
347 {
348 return 0;
349 }
350 EXPORT_SYMBOL(fs_param_is_blockdev);
351
352 int fs_param_is_path(struct p_log *log, const
353 struct fs_parameter *para
354 {
355 return 0;
356 }
357 EXPORT_SYMBOL(fs_param_is_path);
358
359 #ifdef CONFIG_VALIDATE_FS_PARSER
360 /**
361 * validate_constant_table - Validate a consta
362 * @tbl: The constant table to validate.
363 * @tbl_size: The size of the table.
364 * @low: The lowest permissible value.
365 * @high: The highest permissible value.
366 * @special: One special permissible value out
367 */
368 bool validate_constant_table(const struct cons
369 int low, int high
370 {
371 size_t i;
372 bool good = true;
373
374 if (tbl_size == 0) {
375 pr_warn("VALIDATE C-TBL: Empty
376 return true;
377 }
378
379 for (i = 0; i < tbl_size; i++) {
380 if (!tbl[i].name) {
381 pr_err("VALIDATE C-TBL
382 good = false;
383 } else if (i > 0 && tbl[i - 1]
384 int c = strcmp(tbl[i-1
385
386 if (c == 0) {
387 pr_err("VALIDA
388 i, tbl[
389 good = false;
390 }
391 if (c > 0) {
392 pr_err("VALIDA
393 i, tbl[
394 good = false;
395 }
396 }
397
398 if (tbl[i].value != special &&
399 (tbl[i].value < low || tbl
400 pr_err("VALIDATE C-TBL
401 i, tbl[i].name,
402 good = false;
403 }
404 }
405
406 return good;
407 }
408
409 /**
410 * fs_validate_description - Validate a parame
411 * @name: The parameter name to search for.
412 * @desc: The parameter description to validat
413 */
414 bool fs_validate_description(const char *name,
415 const struct fs_parameter_spec *desc)
416 {
417 const struct fs_parameter_spec *param,
418 bool good = true;
419
420 for (param = desc; param->name; param+
421 /* Check for duplicate paramet
422 for (p2 = desc; p2 < param; p2
423 if (strcmp(param->name
424 if (is_flag(pa
425 contin
426 pr_err("VALIDA
427 name, p
428 good = false;
429 }
430 }
431 }
432 return good;
433 }
434 #endif /* CONFIG_VALIDATE_FS_PARSER */
435
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