1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Filesystem parameter parser.
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
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>
16 static const struct constant_table bool_names[] = {
26 static const struct constant_table *
27 __lookup_constant(const struct constant_table *tbl, const char *name)
29 for ( ; tbl->name; tbl++)
30 if (strcmp(name, tbl->name) == 0)
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.
41 int lookup_constant(const struct constant_table *tbl, const char *name, int not_found)
43 const struct constant_table *p = __lookup_constant(tbl, name);
45 return p ? p->value : not_found;
47 EXPORT_SYMBOL(lookup_constant);
49 static inline bool is_flag(const struct fs_parameter_spec *p)
51 return p->type == fs_param_is_flag;
54 static const struct fs_parameter_spec *fs_lookup_key(
55 const struct fs_parameter_spec *desc,
56 struct fs_parameter *param, bool *negated)
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;
63 for (p = desc; p->name; p++) {
64 if (strcmp(p->name, name) != 0)
66 if (likely(is_flag(p) == 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)
75 if (!(p->flags & fs_param_neg_with_no))
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
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.
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.
103 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)
108 const struct fs_parameter_spec *p;
109 const struct constant_table *e;
110 int ret = -ENOPARAM, b;
114 p = fs_lookup_key(desc, param, &result->negated);
118 if (p->flags & fs_param_deprecated)
119 warn_plog(log, "Deprecated parameter '%s'", param->key);
121 /* Try to turn the type we were given into the type desired by the
122 * parameter and give an error if we can't.
125 case __fs_param_wasnt_defined:
127 case fs_param_is_flag:
128 if (param->type != fs_value_is_flag)
129 return inval_plog(log, "Unexpected value for '%s'",
131 result->boolean = !result->negated;
133 case fs_param_is_bool:
134 if (param->type != fs_value_is_string)
136 b = lookup_constant(bool_names, param->string, -1);
141 case fs_param_is_u32:
142 if (param->type != fs_value_is_string)
144 ret = kstrtouint(param->string, 0, &result->uint_32);
146 case fs_param_is_u32_octal:
147 if (param->type != fs_value_is_string)
149 ret = kstrtouint(param->string, 8, &result->uint_32);
151 case fs_param_is_u32_hex:
152 if (param->type != fs_value_is_string)
154 ret = kstrtouint(param->string, 16, &result->uint_32);
156 case fs_param_is_s32:
157 if (param->type != fs_value_is_string)
159 ret = kstrtoint(param->string, 0, &result->int_32);
161 case fs_param_is_u64:
162 if (param->type != fs_value_is_string)
164 ret = kstrtoull(param->string, 0, &result->uint_64);
166 case fs_param_is_enum:
167 if (param->type != fs_value_is_string)
169 e = __lookup_constant(p->data, param->string);
171 result->uint_32 = e->value;
175 case fs_param_is_string:
176 if (param->type != fs_value_is_string || !*param->string)
179 case fs_param_is_blob:
180 if (param->type != fs_value_is_blob)
183 case fs_param_is_fd: {
184 switch (param->type) {
185 case fs_value_is_string:
186 ret = kstrtouint(param->string, 0, &result->uint_32);
188 case fs_value_is_file:
189 result->uint_32 = param->dirfd;
195 if (result->uint_32 > INT_MAX)
199 case fs_param_is_blockdev:
200 case fs_param_is_path:
213 return inval_plog(log, "Bad value for '%s'", param->key);
215 EXPORT_SYMBOL(__fs_parse);
218 * fs_lookup_param - Look up a path referred to by a parameter
219 * @fc: The filesystem context to log errors through.
220 * @param: The parameter.
221 * @want_bdev: T if want a blockdev
222 * @_path: The result of the lookup
224 int fs_lookup_param(struct fs_context *fc,
225 struct fs_parameter *param,
230 unsigned int flags = 0;
234 switch (param->type) {
235 case fs_value_is_string:
236 f = getname_kernel(param->string);
241 case fs_value_is_filename:
246 return invalf(fc, "%s: not usable as path", param->key);
249 f->refcnt++; /* filename_lookup() drops our ref. */
250 ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
252 errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
257 !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
259 _path->dentry = NULL;
261 errorf(fc, "%s: Non-blockdev passed as '%s'",
262 param->key, f->name);
271 EXPORT_SYMBOL(fs_lookup_param);
273 #ifdef CONFIG_VALIDATE_FS_PARSER
275 * validate_constant_table - Validate a constant table
276 * @name: Name to use in reporting
277 * @tbl: The constant table to validate.
278 * @tbl_size: The size of the table.
279 * @low: The lowest permissible value.
280 * @high: The highest permissible value.
281 * @special: One special permissible value outside of the range.
283 bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
284 int low, int high, int special)
290 pr_warn("VALIDATE C-TBL: Empty\n");
294 for (i = 0; i < tbl_size; i++) {
296 pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
298 } else if (i > 0 && tbl[i - 1].name) {
299 int c = strcmp(tbl[i-1].name, tbl[i].name);
302 pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
307 pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
308 i, tbl[i-1].name, tbl[i].name);
313 if (tbl[i].value != special &&
314 (tbl[i].value < low || tbl[i].value > high)) {
315 pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
316 i, tbl[i].name, tbl[i].value, low, high);
325 * fs_validate_description - Validate a parameter description
326 * @desc: The parameter description to validate.
328 bool fs_validate_description(const char *name,
329 const struct fs_parameter_spec *desc)
331 const struct fs_parameter_spec *param, *p2;
334 pr_notice("*** VALIDATE %s ***\n", name);
336 for (param = desc; param->name; param++) {
337 enum fs_parameter_type t = param->type;
339 /* Check that the type is in range */
340 if (t == __fs_param_wasnt_defined ||
341 t >= nr__fs_parameter_type) {
342 pr_err("VALIDATE %s: PARAM[%s] Bad type %u\n",
343 name, param->name, t);
345 } else if (t == fs_param_is_enum) {
346 const struct constant_table *e = param->data;
347 if (!e || !e->name) {
348 pr_err("VALIDATE %s: PARAM[%s] enum with no values\n",
354 /* Check for duplicate parameter names */
355 for (p2 = desc; p2 < param; p2++) {
356 if (strcmp(param->name, p2->name) == 0) {
357 if (is_flag(param) != is_flag(p2))
359 pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
367 #endif /* CONFIG_VALIDATE_FS_PARSER */