Line data Source code
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 (dhowells@redhat.com)
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 : { "0", 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 *tbl, const char *name)
28 : {
29 90 : for ( ; tbl->name; tbl++)
30 90 : 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 : */
41 20 : int lookup_constant(const struct constant_table *tbl, const char *name, int not_found)
42 : {
43 20 : const struct constant_table *p = __lookup_constant(tbl, name);
44 :
45 20 : return p ? p->value : not_found;
46 : }
47 : EXPORT_SYMBOL(lookup_constant);
48 :
49 : static inline bool is_flag(const struct fs_parameter_spec *p)
50 : {
51 0 : return p->type == NULL;
52 : }
53 :
54 2 : static const struct fs_parameter_spec *fs_lookup_key(
55 : const struct fs_parameter_spec *desc,
56 : struct fs_parameter *param, bool *negated)
57 : {
58 2 : const struct fs_parameter_spec *p, *other = NULL;
59 2 : const char *name = param->key;
60 2 : bool want_flag = param->type == fs_value_is_flag;
61 :
62 2 : *negated = false;
63 6 : for (p = desc; p->name; p++) {
64 4 : if (strcmp(p->name, name) != 0)
65 4 : continue;
66 0 : if (likely(is_flag(p) == want_flag))
67 : return p;
68 : other = p;
69 : }
70 2 : if (want_flag) {
71 0 : if (name[0] == 'n' && name[1] == 'o' && name[2]) {
72 0 : for (p = desc; p->name; p++) {
73 0 : if (strcmp(p->name, name + 2) != 0)
74 0 : continue;
75 0 : if (!(p->flags & fs_param_neg_with_no))
76 0 : continue;
77 0 : *negated = true;
78 0 : return p;
79 : }
80 : }
81 : }
82 : return other;
83 : }
84 :
85 : /*
86 : * fs_parse - Parse a filesystem configuration parameter
87 : * @fc: 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 : */
103 2 : int __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 2 : result->uint_64 = 0;
111 :
112 2 : p = fs_lookup_key(desc, param, &result->negated);
113 2 : if (!p)
114 : return -ENOPARAM;
115 :
116 0 : if (p->flags & fs_param_deprecated)
117 0 : 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 0 : if (is_flag(p)) {
123 0 : if (param->type != fs_value_is_flag)
124 0 : return inval_plog(log, "Unexpected value for '%s'",
125 : param->key);
126 0 : result->boolean = !result->negated;
127 : } else {
128 0 : int ret = p->type(log, p, param, result);
129 0 : if (ret)
130 : return ret;
131 : }
132 0 : return p->opt;
133 : }
134 : EXPORT_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 : * @_path: The result of the lookup
142 : */
143 0 : int fs_lookup_param(struct fs_context *fc,
144 : struct fs_parameter *param,
145 : bool want_bdev,
146 : struct path *_path)
147 : {
148 : struct filename *f;
149 0 : unsigned int flags = 0;
150 : bool put_f;
151 : int ret;
152 :
153 0 : switch (param->type) {
154 : case fs_value_is_string:
155 0 : f = getname_kernel(param->string);
156 0 : if (IS_ERR(f))
157 0 : return PTR_ERR(f);
158 : put_f = true;
159 : break;
160 : case fs_value_is_filename:
161 0 : f = param->name;
162 0 : put_f = false;
163 0 : break;
164 : default:
165 0 : return invalf(fc, "%s: not usable as path", param->key);
166 : }
167 :
168 0 : ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
169 0 : if (ret < 0) {
170 0 : errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
171 0 : goto out;
172 : }
173 :
174 0 : if (want_bdev &&
175 0 : !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
176 0 : path_put(_path);
177 0 : _path->dentry = NULL;
178 0 : _path->mnt = NULL;
179 0 : errorf(fc, "%s: Non-blockdev passed as '%s'",
180 : param->key, f->name);
181 0 : ret = -ENOTBLK;
182 : }
183 :
184 : out:
185 0 : if (put_f)
186 0 : putname(f);
187 : return ret;
188 : }
189 : EXPORT_SYMBOL(fs_lookup_param);
190 :
191 : static int fs_param_bad_value(struct p_log *log, struct fs_parameter *param)
192 : {
193 0 : return inval_plog(log, "Bad value for '%s'", param->key);
194 : }
195 :
196 0 : int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p,
197 : struct fs_parameter *param, struct fs_parse_result *result)
198 : {
199 : int b;
200 0 : if (param->type != fs_value_is_string)
201 0 : return fs_param_bad_value(log, param);
202 0 : if (!*param->string && (p->flags & fs_param_can_be_empty))
203 : return 0;
204 0 : b = lookup_constant(bool_names, param->string, -1);
205 0 : if (b == -1)
206 0 : return fs_param_bad_value(log, param);
207 0 : result->boolean = b;
208 0 : return 0;
209 : }
210 : EXPORT_SYMBOL(fs_param_is_bool);
211 :
212 0 : int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p,
213 : struct fs_parameter *param, struct fs_parse_result *result)
214 : {
215 0 : int base = (unsigned long)p->data;
216 0 : if (param->type != fs_value_is_string)
217 0 : return fs_param_bad_value(log, param);
218 0 : if (!*param->string && (p->flags & fs_param_can_be_empty))
219 : return 0;
220 0 : if (kstrtouint(param->string, base, &result->uint_32) < 0)
221 0 : return fs_param_bad_value(log, param);
222 : return 0;
223 : }
224 : EXPORT_SYMBOL(fs_param_is_u32);
225 :
226 0 : int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p,
227 : struct fs_parameter *param, struct fs_parse_result *result)
228 : {
229 0 : if (param->type != fs_value_is_string)
230 0 : return fs_param_bad_value(log, param);
231 0 : if (!*param->string && (p->flags & fs_param_can_be_empty))
232 : return 0;
233 0 : if (kstrtoint(param->string, 0, &result->int_32) < 0)
234 0 : return fs_param_bad_value(log, param);
235 : return 0;
236 : }
237 : EXPORT_SYMBOL(fs_param_is_s32);
238 :
239 0 : int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p,
240 : struct fs_parameter *param, struct fs_parse_result *result)
241 : {
242 0 : if (param->type != fs_value_is_string)
243 0 : return fs_param_bad_value(log, param);
244 0 : if (!*param->string && (p->flags & fs_param_can_be_empty))
245 : return 0;
246 0 : if (kstrtoull(param->string, 0, &result->uint_64) < 0)
247 0 : return fs_param_bad_value(log, param);
248 : return 0;
249 : }
250 : EXPORT_SYMBOL(fs_param_is_u64);
251 :
252 0 : int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p,
253 : struct fs_parameter *param, struct fs_parse_result *result)
254 : {
255 : const struct constant_table *c;
256 0 : if (param->type != fs_value_is_string)
257 0 : return fs_param_bad_value(log, param);
258 0 : if (!*param->string && (p->flags & fs_param_can_be_empty))
259 : return 0;
260 0 : c = __lookup_constant(p->data, param->string);
261 0 : if (!c)
262 0 : return fs_param_bad_value(log, param);
263 0 : result->uint_32 = c->value;
264 0 : return 0;
265 : }
266 : EXPORT_SYMBOL(fs_param_is_enum);
267 :
268 0 : int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p,
269 : struct fs_parameter *param, struct fs_parse_result *result)
270 : {
271 0 : if (param->type != fs_value_is_string ||
272 0 : (!*param->string && !(p->flags & fs_param_can_be_empty)))
273 0 : return fs_param_bad_value(log, param);
274 : return 0;
275 : }
276 : EXPORT_SYMBOL(fs_param_is_string);
277 :
278 0 : int fs_param_is_blob(struct p_log *log, const struct fs_parameter_spec *p,
279 : struct fs_parameter *param, struct fs_parse_result *result)
280 : {
281 0 : if (param->type != fs_value_is_blob)
282 0 : return fs_param_bad_value(log, param);
283 : return 0;
284 : }
285 : EXPORT_SYMBOL(fs_param_is_blob);
286 :
287 0 : int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p,
288 : struct fs_parameter *param, struct fs_parse_result *result)
289 : {
290 0 : switch (param->type) {
291 : case fs_value_is_string:
292 0 : if ((!*param->string && !(p->flags & fs_param_can_be_empty)) ||
293 0 : kstrtouint(param->string, 0, &result->uint_32) < 0)
294 : break;
295 0 : if (result->uint_32 <= INT_MAX)
296 : return 0;
297 : break;
298 : case fs_value_is_file:
299 0 : result->uint_32 = param->dirfd;
300 0 : if (result->uint_32 <= INT_MAX)
301 : return 0;
302 : break;
303 : default:
304 : break;
305 : }
306 0 : return fs_param_bad_value(log, param);
307 : }
308 : EXPORT_SYMBOL(fs_param_is_fd);
309 :
310 0 : int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,
311 : struct fs_parameter *param, struct fs_parse_result *result)
312 : {
313 0 : return 0;
314 : }
315 : EXPORT_SYMBOL(fs_param_is_blockdev);
316 :
317 0 : int fs_param_is_path(struct p_log *log, const struct fs_parameter_spec *p,
318 : struct fs_parameter *param, struct fs_parse_result *result)
319 : {
320 0 : return 0;
321 : }
322 : EXPORT_SYMBOL(fs_param_is_path);
323 :
324 : #ifdef CONFIG_VALIDATE_FS_PARSER
325 : /**
326 : * validate_constant_table - Validate a constant table
327 : * @tbl: The constant table to validate.
328 : * @tbl_size: The size of the table.
329 : * @low: The lowest permissible value.
330 : * @high: The highest permissible value.
331 : * @special: One special permissible value outside of the range.
332 : */
333 : bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
334 : int low, int high, int special)
335 : {
336 : size_t i;
337 : bool good = true;
338 :
339 : if (tbl_size == 0) {
340 : pr_warn("VALIDATE C-TBL: Empty\n");
341 : return true;
342 : }
343 :
344 : for (i = 0; i < tbl_size; i++) {
345 : if (!tbl[i].name) {
346 : pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
347 : good = false;
348 : } else if (i > 0 && tbl[i - 1].name) {
349 : int c = strcmp(tbl[i-1].name, tbl[i].name);
350 :
351 : if (c == 0) {
352 : pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
353 : i, tbl[i].name);
354 : good = false;
355 : }
356 : if (c > 0) {
357 : pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
358 : i, tbl[i-1].name, tbl[i].name);
359 : good = false;
360 : }
361 : }
362 :
363 : if (tbl[i].value != special &&
364 : (tbl[i].value < low || tbl[i].value > high)) {
365 : pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
366 : i, tbl[i].name, tbl[i].value, low, high);
367 : good = false;
368 : }
369 : }
370 :
371 : return good;
372 : }
373 :
374 : /**
375 : * fs_validate_description - Validate a parameter description
376 : * @name: The parameter name to search for.
377 : * @desc: The parameter description to validate.
378 : */
379 : bool fs_validate_description(const char *name,
380 : const struct fs_parameter_spec *desc)
381 : {
382 : const struct fs_parameter_spec *param, *p2;
383 : bool good = true;
384 :
385 : for (param = desc; param->name; param++) {
386 : /* Check for duplicate parameter names */
387 : for (p2 = desc; p2 < param; p2++) {
388 : if (strcmp(param->name, p2->name) == 0) {
389 : if (is_flag(param) != is_flag(p2))
390 : continue;
391 : pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
392 : name, param->name);
393 : good = false;
394 : }
395 : }
396 : }
397 : return good;
398 : }
399 : #endif /* CONFIG_VALIDATE_FS_PARSER */
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