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 *
27 664 : __lookup_constant(const struct constant_table *tbl, const char *name)
28 : {
29 3652 : for ( ; tbl->name; tbl++)
30 2988 : if (strcmp(name, tbl->name) == 0)
31 0 : 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 : */
41 664 : int lookup_constant(const struct constant_table *tbl, const char *name, int not_found)
42 : {
43 664 : const struct constant_table *p = __lookup_constant(tbl, name);
44 :
45 664 : return p ? p->value : not_found;
46 : }
47 : EXPORT_SYMBOL(lookup_constant);
48 :
49 410 : static inline bool is_flag(const struct fs_parameter_spec *p)
50 : {
51 410 : return p->type == NULL;
52 : }
53 :
54 313 : static const struct fs_parameter_spec *fs_lookup_key(
55 : const struct fs_parameter_spec *desc,
56 : struct fs_parameter *param, bool *negated)
57 : {
58 313 : const struct fs_parameter_spec *p, *other = NULL;
59 313 : const char *name = param->key;
60 313 : bool want_flag = param->type == fs_value_is_flag;
61 :
62 313 : *negated = false;
63 2164 : for (p = desc; p->name; p++) {
64 2056 : if (strcmp(p->name, name) != 0)
65 1851 : continue;
66 205 : if (likely(is_flag(p) == want_flag))
67 205 : return p;
68 : other = p;
69 : }
70 108 : 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 : */
103 313 : 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 : {
108 313 : const struct fs_parameter_spec *p;
109 :
110 313 : result->uint_64 = 0;
111 :
112 313 : p = fs_lookup_key(desc, param, &result->negated);
113 313 : if (!p)
114 : return -ENOPARAM;
115 :
116 205 : 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 : */
122 205 : if (is_flag(p)) {
123 3 : if (param->type != fs_value_is_flag)
124 0 : return inval_plog(log, "Unexpected value for '%s'",
125 : param->key);
126 3 : result->boolean = !result->negated;
127 : } else {
128 202 : int ret = p->type(log, p, param, result);
129 202 : if (ret)
130 : return ret;
131 : }
132 205 : 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 0 : struct filename *f;
149 0 : unsigned int flags = 0;
150 0 : bool put_f;
151 0 : int ret;
152 :
153 0 : switch (param->type) {
154 0 : 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 0 : case fs_value_is_filename:
161 0 : f = param->name;
162 0 : put_f = false;
163 0 : break;
164 0 : default:
165 0 : return invalf(fc, "%s: not usable as path", param->key);
166 : }
167 :
168 0 : f->refcnt++; /* filename_lookup() drops our ref. */
169 0 : ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
170 0 : if (ret < 0) {
171 0 : errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
172 0 : goto out;
173 : }
174 :
175 0 : if (want_bdev &&
176 0 : !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
177 0 : path_put(_path);
178 0 : _path->dentry = NULL;
179 0 : _path->mnt = NULL;
180 0 : errorf(fc, "%s: Non-blockdev passed as '%s'",
181 : param->key, f->name);
182 0 : ret = -ENOTBLK;
183 : }
184 :
185 0 : out:
186 0 : if (put_f)
187 0 : putname(f);
188 : return ret;
189 : }
190 : EXPORT_SYMBOL(fs_lookup_param);
191 :
192 0 : static int fs_param_bad_value(struct p_log *log, struct fs_parameter *param)
193 : {
194 0 : return inval_plog(log, "Bad value for '%s'", param->key);
195 : }
196 :
197 0 : int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p,
198 : struct fs_parameter *param, struct fs_parse_result *result)
199 : {
200 0 : int b;
201 0 : if (param->type != fs_value_is_string)
202 0 : return fs_param_bad_value(log, param);
203 0 : b = lookup_constant(bool_names, param->string, -1);
204 0 : if (b == -1)
205 0 : return fs_param_bad_value(log, param);
206 0 : result->boolean = b;
207 0 : return 0;
208 : }
209 : EXPORT_SYMBOL(fs_param_is_bool);
210 :
211 105 : int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p,
212 : struct fs_parameter *param, struct fs_parse_result *result)
213 : {
214 105 : int base = (unsigned long)p->data;
215 210 : if (param->type != fs_value_is_string ||
216 105 : kstrtouint(param->string, base, &result->uint_32) < 0)
217 0 : return fs_param_bad_value(log, param);
218 : return 0;
219 : }
220 : EXPORT_SYMBOL(fs_param_is_u32);
221 :
222 0 : int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p,
223 : struct fs_parameter *param, struct fs_parse_result *result)
224 : {
225 0 : if (param->type != fs_value_is_string ||
226 0 : kstrtoint(param->string, 0, &result->int_32) < 0)
227 0 : return fs_param_bad_value(log, param);
228 : return 0;
229 : }
230 : EXPORT_SYMBOL(fs_param_is_s32);
231 :
232 0 : int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p,
233 : struct fs_parameter *param, struct fs_parse_result *result)
234 : {
235 0 : if (param->type != fs_value_is_string ||
236 0 : kstrtoull(param->string, 0, &result->uint_64) < 0)
237 0 : return fs_param_bad_value(log, param);
238 : return 0;
239 : }
240 : EXPORT_SYMBOL(fs_param_is_u64);
241 :
242 0 : int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p,
243 : struct fs_parameter *param, struct fs_parse_result *result)
244 : {
245 0 : const struct constant_table *c;
246 0 : if (param->type != fs_value_is_string)
247 0 : return fs_param_bad_value(log, param);
248 0 : c = __lookup_constant(p->data, param->string);
249 0 : if (!c)
250 0 : return fs_param_bad_value(log, param);
251 0 : result->uint_32 = c->value;
252 0 : return 0;
253 : }
254 : EXPORT_SYMBOL(fs_param_is_enum);
255 :
256 97 : int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p,
257 : struct fs_parameter *param, struct fs_parse_result *result)
258 : {
259 97 : if (param->type != fs_value_is_string || !*param->string)
260 0 : return fs_param_bad_value(log, param);
261 : return 0;
262 : }
263 : EXPORT_SYMBOL(fs_param_is_string);
264 :
265 0 : int fs_param_is_blob(struct p_log *log, const struct fs_parameter_spec *p,
266 : struct fs_parameter *param, struct fs_parse_result *result)
267 : {
268 0 : if (param->type != fs_value_is_blob)
269 0 : return fs_param_bad_value(log, param);
270 : return 0;
271 : }
272 : EXPORT_SYMBOL(fs_param_is_blob);
273 :
274 0 : int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p,
275 : struct fs_parameter *param, struct fs_parse_result *result)
276 : {
277 0 : switch (param->type) {
278 0 : case fs_value_is_string:
279 0 : if (kstrtouint(param->string, 0, &result->uint_32) < 0)
280 : break;
281 0 : if (result->uint_32 <= INT_MAX)
282 : return 0;
283 : break;
284 0 : case fs_value_is_file:
285 0 : result->uint_32 = param->dirfd;
286 0 : if (result->uint_32 <= INT_MAX)
287 : return 0;
288 : break;
289 : default:
290 : break;
291 : }
292 0 : return fs_param_bad_value(log, param);
293 : }
294 : EXPORT_SYMBOL(fs_param_is_fd);
295 :
296 0 : int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,
297 : struct fs_parameter *param, struct fs_parse_result *result)
298 : {
299 0 : return 0;
300 : }
301 : EXPORT_SYMBOL(fs_param_is_blockdev);
302 :
303 0 : int fs_param_is_path(struct p_log *log, const struct fs_parameter_spec *p,
304 : struct fs_parameter *param, struct fs_parse_result *result)
305 : {
306 0 : return 0;
307 : }
308 : EXPORT_SYMBOL(fs_param_is_path);
309 :
310 : #ifdef CONFIG_VALIDATE_FS_PARSER
311 : /**
312 : * validate_constant_table - Validate a constant table
313 : * @name: Name to use in reporting
314 : * @tbl: The constant table to validate.
315 : * @tbl_size: The size of the table.
316 : * @low: The lowest permissible value.
317 : * @high: The highest permissible value.
318 : * @special: One special permissible value outside of the range.
319 : */
320 : bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
321 : int low, int high, int special)
322 : {
323 : size_t i;
324 : bool good = true;
325 :
326 : if (tbl_size == 0) {
327 : pr_warn("VALIDATE C-TBL: Empty\n");
328 : return true;
329 : }
330 :
331 : for (i = 0; i < tbl_size; i++) {
332 : if (!tbl[i].name) {
333 : pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
334 : good = false;
335 : } else if (i > 0 && tbl[i - 1].name) {
336 : int c = strcmp(tbl[i-1].name, tbl[i].name);
337 :
338 : if (c == 0) {
339 : pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
340 : i, tbl[i].name);
341 : good = false;
342 : }
343 : if (c > 0) {
344 : pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
345 : i, tbl[i-1].name, tbl[i].name);
346 : good = false;
347 : }
348 : }
349 :
350 : if (tbl[i].value != special &&
351 : (tbl[i].value < low || tbl[i].value > high)) {
352 : pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
353 : i, tbl[i].name, tbl[i].value, low, high);
354 : good = false;
355 : }
356 : }
357 :
358 : return good;
359 : }
360 :
361 : /**
362 : * fs_validate_description - Validate a parameter description
363 : * @desc: The parameter description to validate.
364 : */
365 : bool fs_validate_description(const char *name,
366 : const struct fs_parameter_spec *desc)
367 : {
368 : const struct fs_parameter_spec *param, *p2;
369 : bool good = true;
370 :
371 : for (param = desc; param->name; param++) {
372 : /* Check for duplicate parameter names */
373 : for (p2 = desc; p2 < param; p2++) {
374 : if (strcmp(param->name, p2->name) == 0) {
375 : if (is_flag(param) != is_flag(p2))
376 : continue;
377 : pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
378 : name, param->name);
379 : good = false;
380 : }
381 : }
382 : }
383 : return good;
384 : }
385 : #endif /* CONFIG_VALIDATE_FS_PARSER */
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