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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Filesystem parameter parser.
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells ([email protected])
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
16static const struct constant_table bool_names[] = {
17 { "0", false },
18 { "1", true },
19 { "false", false },
20 { "no", false },
21 { "true", true },
22 { "yes", true },
23 { },
24};
25
26static const struct constant_table *
27__lookup_constant(const struct constant_table *tbl, const char *name)
28{
29 for ( ; tbl->name; tbl++)
30 if (strcmp(name, tbl->name) == 0)
31 return tbl;
32 return NULL;
33}
34
35/**
36 * lookup_constant - Look up a constant by name in an ordered table
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 is not found.
40 */
41int lookup_constant(const struct constant_table *tbl, const char *name, int not_found)
42{
43 const struct constant_table *p = __lookup_constant(tbl, name);
44
45 return p ? p->value : not_found;
46}
47EXPORT_SYMBOL(lookup_constant);
48
49static inline bool is_flag(const struct fs_parameter_spec *p)
50{
51 return p->type == NULL;
52}
53
54static const struct fs_parameter_spec *fs_lookup_key(
55 const struct fs_parameter_spec *desc,
56 struct fs_parameter *param, bool *negated)
57{
58 const struct fs_parameter_spec *p, *other = NULL;
59 const char *name = param->key;
60 bool want_flag = param->type == fs_value_is_flag;
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_flag))
67 return p;
68 other = p;
69 }
70 if (want_flag) {
71 if (name[0] == 'n' && name[1] == 'o' && name[2]) {
72 for (p = desc; p->name; p++) {
73 if (strcmp(p->name, name + 2) != 0)
74 continue;
75 if (!(p->flags & fs_param_neg_with_no))
76 continue;
77 *negated = true;
78 return p;
79 }
80 }
81 }
82 return other;
83}
84
85/*
86 * __fs_parse - Parse a filesystem configuration parameter
87 * @log: The filesystem context to log errors through.
88 * @desc: The parameter description to use.
89 * @param: The parameter.
90 * @result: Where to place the result of the parse
91 *
92 * Parse a filesystem configuration parameter and attempt a conversion for a
93 * simple parameter for which this is requested. If successful, the determined
94 * parameter ID is placed into @result->key, the desired type is indicated in
95 * @result->t and any converted value is placed into an appropriate member of
96 * the union in @result.
97 *
98 * The function returns the parameter number if the parameter was matched,
99 * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that
100 * unknown parameters are okay and -EINVAL if there was a conversion issue or
101 * the parameter wasn't recognised and unknowns aren't okay.
102 */
103int __fs_parse(struct p_log *log,
104 const struct fs_parameter_spec *desc,
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->negated);
113 if (!p)
114 return -ENOPARAM;
115
116 if (p->flags & fs_param_deprecated)
117 warn_plog(log, "Deprecated parameter '%s'", param->key);
118
119 /* Try to turn the type we were given into the type desired by the
120 * parameter and give an error if we can't.
121 */
122 if (is_flag(p)) {
123 if (param->type != fs_value_is_flag)
124 return inval_plog(log, "Unexpected value for '%s'",
125 param->key);
126 result->boolean = !result->negated;
127 } else {
128 int ret = p->type(log, p, param, result);
129 if (ret)
130 return ret;
131 }
132 return p->opt;
133}
134EXPORT_SYMBOL(__fs_parse);
135
136/**
137 * fs_lookup_param - Look up a path referred to by a parameter
138 * @fc: The filesystem context to log errors through.
139 * @param: The parameter.
140 * @want_bdev: T if want a blockdev
141 * @flags: Pathwalk flags passed to filename_lookup()
142 * @_path: The result of the lookup
143 */
144int 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->string);
157 if (IS_ERR(f))
158 return PTR_ERR(f);
159 param->dirfd = AT_FDCWD;
160 put_f = true;
161 break;
162 case fs_value_is_filename:
163 f = param->name;
164 put_f = false;
165 break;
166 default:
167 return invalf(fc, "%s: not usable as path", param->key);
168 }
169
170 ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
171 if (ret < 0) {
172 errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
173 goto out;
174 }
175
176 if (want_bdev &&
177 !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
178 path_put(_path);
179 _path->dentry = NULL;
180 _path->mnt = NULL;
181 errorf(fc, "%s: Non-blockdev passed as '%s'",
182 param->key, f->name);
183 ret = -ENOTBLK;
184 }
185
186out:
187 if (put_f)
188 putname(f);
189 return ret;
190}
191EXPORT_SYMBOL(fs_lookup_param);
192
193static int fs_param_bad_value(struct p_log *log, struct fs_parameter *param)
194{
195 return inval_plog(log, "Bad value for '%s'", param->key);
196}
197
198int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p,
199 struct fs_parameter *param, struct fs_parse_result *result)
200{
201 int b;
202 if (param->type != fs_value_is_string)
203 return fs_param_bad_value(log, param);
204 if (!*param->string && (p->flags & fs_param_can_be_empty))
205 return 0;
206 b = lookup_constant(bool_names, param->string, -1);
207 if (b == -1)
208 return fs_param_bad_value(log, param);
209 result->boolean = b;
210 return 0;
211}
212EXPORT_SYMBOL(fs_param_is_bool);
213
214int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p,
215 struct fs_parameter *param, struct fs_parse_result *result)
216{
217 int base = (unsigned long)p->data;
218 if (param->type != fs_value_is_string)
219 return fs_param_bad_value(log, param);
220 if (!*param->string && (p->flags & fs_param_can_be_empty))
221 return 0;
222 if (kstrtouint(param->string, base, &result->uint_32) < 0)
223 return fs_param_bad_value(log, param);
224 return 0;
225}
226EXPORT_SYMBOL(fs_param_is_u32);
227
228int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p,
229 struct fs_parameter *param, struct fs_parse_result *result)
230{
231 if (param->type != fs_value_is_string)
232 return fs_param_bad_value(log, param);
233 if (!*param->string && (p->flags & fs_param_can_be_empty))
234 return 0;
235 if (kstrtoint(param->string, 0, &result->int_32) < 0)
236 return fs_param_bad_value(log, param);
237 return 0;
238}
239EXPORT_SYMBOL(fs_param_is_s32);
240
241int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p,
242 struct fs_parameter *param, struct fs_parse_result *result)
243{
244 if (param->type != fs_value_is_string)
245 return fs_param_bad_value(log, param);
246 if (!*param->string && (p->flags & fs_param_can_be_empty))
247 return 0;
248 if (kstrtoull(param->string, 0, &result->uint_64) < 0)
249 return fs_param_bad_value(log, param);
250 return 0;
251}
252EXPORT_SYMBOL(fs_param_is_u64);
253
254int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p,
255 struct fs_parameter *param, struct fs_parse_result *result)
256{
257 const struct constant_table *c;
258 if (param->type != fs_value_is_string)
259 return fs_param_bad_value(log, param);
260 if (!*param->string && (p->flags & fs_param_can_be_empty))
261 return 0;
262 c = __lookup_constant(p->data, param->string);
263 if (!c)
264 return fs_param_bad_value(log, param);
265 result->uint_32 = c->value;
266 return 0;
267}
268EXPORT_SYMBOL(fs_param_is_enum);
269
270int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p,
271 struct fs_parameter *param, struct fs_parse_result *result)
272{
273 if (param->type != fs_value_is_string ||
274 (!*param->string && !(p->flags & fs_param_can_be_empty)))
275 return fs_param_bad_value(log, param);
276 return 0;
277}
278EXPORT_SYMBOL(fs_param_is_string);
279
280int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p,
281 struct fs_parameter *param, struct fs_parse_result *result)
282{
283 switch (param->type) {
284 case fs_value_is_string:
285 if ((!*param->string && !(p->flags & fs_param_can_be_empty)) ||
286 kstrtouint(param->string, 0, &result->uint_32) < 0)
287 break;
288 if (result->uint_32 <= INT_MAX)
289 return 0;
290 break;
291 case fs_value_is_file:
292 result->uint_32 = param->dirfd;
293 if (result->uint_32 <= INT_MAX)
294 return 0;
295 break;
296 default:
297 break;
298 }
299 return fs_param_bad_value(log, param);
300}
301EXPORT_SYMBOL(fs_param_is_fd);
302
303int fs_param_is_file_or_string(struct p_log *log,
304 const struct fs_parameter_spec *p,
305 struct fs_parameter *param,
306 struct fs_parse_result *result)
307{
308 switch (param->type) {
309 case fs_value_is_string:
310 return fs_param_is_string(log, p, param, result);
311 case fs_value_is_file:
312 result->uint_32 = param->dirfd;
313 if (result->uint_32 <= INT_MAX)
314 return 0;
315 break;
316 default:
317 break;
318 }
319 return fs_param_bad_value(log, param);
320}
321EXPORT_SYMBOL(fs_param_is_file_or_string);
322
323int fs_param_is_uid(struct p_log *log, const struct fs_parameter_spec *p,
324 struct fs_parameter *param, struct fs_parse_result *result)
325{
326 kuid_t uid;
327
328 if (fs_param_is_u32(log, p, param, result) != 0)
329 return fs_param_bad_value(log, param);
330
331 uid = make_kuid(current_user_ns(), result->uint_32);
332 if (!uid_valid(uid))
333 return inval_plog(log, "Invalid uid '%s'", param->string);
334
335 result->uid = uid;
336 return 0;
337}
338EXPORT_SYMBOL(fs_param_is_uid);
339
340int fs_param_is_gid(struct p_log *log, const struct fs_parameter_spec *p,
341 struct fs_parameter *param, struct fs_parse_result *result)
342{
343 kgid_t gid;
344
345 if (fs_param_is_u32(log, p, param, result) != 0)
346 return fs_param_bad_value(log, param);
347
348 gid = make_kgid(current_user_ns(), result->uint_32);
349 if (!gid_valid(gid))
350 return inval_plog(log, "Invalid gid '%s'", param->string);
351
352 result->gid = gid;
353 return 0;
354}
355EXPORT_SYMBOL(fs_param_is_gid);
356
357int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,
358 struct fs_parameter *param, struct fs_parse_result *result)
359{
360 return 0;
361}
362EXPORT_SYMBOL(fs_param_is_blockdev);
363
364#ifdef CONFIG_VALIDATE_FS_PARSER
365/**
366 * fs_validate_description - Validate a parameter specification array
367 * @name: Owner name of the parameter specification array
368 * @desc: The parameter specification array to validate.
369 */
370bool fs_validate_description(const char *name,
371 const struct fs_parameter_spec *desc)
372{
373 const struct fs_parameter_spec *param, *p2;
374 bool good = true;
375
376 for (param = desc; param->name; param++) {
377 /* Check for duplicate parameter names */
378 for (p2 = desc; p2 < param; p2++) {
379 if (strcmp(param->name, p2->name) == 0) {
380 if (is_flag(param) != is_flag(p2))
381 continue;
382 pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
383 name, param->name);
384 good = false;
385 }
386 }
387 }
388 return good;
389}
390#endif /* CONFIG_VALIDATE_FS_PARSER */