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 const struct fs_parameter_spec *fs_lookup_key(
50 const struct fs_parameter_spec *desc,
53 const struct fs_parameter_spec *p;
57 for (p = desc; p->name; p++)
58 if (strcmp(p->name, name) == 0)
65 * fs_parse - Parse a filesystem configuration parameter
66 * @fc: The filesystem context to log errors through.
67 * @desc: The parameter description to use.
68 * @param: The parameter.
69 * @result: Where to place the result of the parse
71 * Parse a filesystem configuration parameter and attempt a conversion for a
72 * simple parameter for which this is requested. If successful, the determined
73 * parameter ID is placed into @result->key, the desired type is indicated in
74 * @result->t and any converted value is placed into an appropriate member of
75 * the union in @result.
77 * The function returns the parameter number if the parameter was matched,
78 * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that
79 * unknown parameters are okay and -EINVAL if there was a conversion issue or
80 * the parameter wasn't recognised and unknowns aren't okay.
82 int __fs_parse(struct p_log *log,
83 const struct fs_parameter_spec *desc,
84 struct fs_parameter *param,
85 struct fs_parse_result *result)
87 const struct fs_parameter_spec *p;
88 const struct constant_table *e;
89 int ret = -ENOPARAM, b;
91 result->negated = false;
94 p = fs_lookup_key(desc, param->key);
96 /* If we didn't find something that looks like "noxxx", see if
97 * "xxx" takes the "no"-form negative - but only if there
100 if (param->type != fs_value_is_flag)
101 goto unknown_parameter;
102 if (param->key[0] != 'n' || param->key[1] != 'o' || !param->key[2])
103 goto unknown_parameter;
105 p = fs_lookup_key(desc, param->key + 2);
107 goto unknown_parameter;
108 if (!(p->flags & fs_param_neg_with_no))
109 goto unknown_parameter;
110 result->boolean = false;
111 result->negated = true;
114 if (p->flags & fs_param_deprecated)
115 warn_plog(log, "Deprecated parameter '%s'", param->key);
120 /* Certain parameter types only take a string and convert it. */
122 case __fs_param_wasnt_defined:
124 case fs_param_is_u32:
125 case fs_param_is_u32_octal:
126 case fs_param_is_u32_hex:
127 case fs_param_is_s32:
128 case fs_param_is_u64:
129 case fs_param_is_enum:
130 case fs_param_is_string:
131 if (param->type == fs_value_is_string) {
132 if (p->flags & fs_param_v_optional)
138 if (param->type == fs_value_is_flag) {
139 if (p->flags & fs_param_v_optional)
147 /* Try to turn the type we were given into the type desired by the
148 * parameter and give an error if we can't.
151 case fs_param_is_flag:
152 if (param->type != fs_value_is_flag)
153 return inval_plog(log, "Unexpected value for '%s'",
155 result->boolean = true;
158 case fs_param_is_bool:
159 switch (param->type) {
160 case fs_value_is_flag:
161 result->boolean = true;
163 case fs_value_is_string:
164 if (param->size == 0) {
165 result->boolean = true;
168 b = lookup_constant(bool_names, param->string, -1);
177 case fs_param_is_u32:
178 ret = kstrtouint(param->string, 0, &result->uint_32);
180 case fs_param_is_u32_octal:
181 ret = kstrtouint(param->string, 8, &result->uint_32);
183 case fs_param_is_u32_hex:
184 ret = kstrtouint(param->string, 16, &result->uint_32);
186 case fs_param_is_s32:
187 ret = kstrtoint(param->string, 0, &result->int_32);
189 case fs_param_is_u64:
190 ret = kstrtoull(param->string, 0, &result->uint_64);
193 case fs_param_is_enum:
194 e = __lookup_constant(p->data, param->string);
196 result->uint_32 = e->value;
201 case fs_param_is_string:
203 case fs_param_is_blob:
204 if (param->type != fs_value_is_blob)
208 case fs_param_is_fd: {
209 switch (param->type) {
210 case fs_value_is_string:
211 ret = kstrtouint(param->string, 0, &result->uint_32);
213 case fs_value_is_file:
214 result->uint_32 = param->dirfd;
220 if (result->uint_32 > INT_MAX)
225 case fs_param_is_blockdev:
226 case fs_param_is_path:
239 return inval_plog(log, "Bad value for '%s'", param->key);
243 EXPORT_SYMBOL(__fs_parse);
246 * fs_lookup_param - Look up a path referred to by a parameter
247 * @fc: The filesystem context to log errors through.
248 * @param: The parameter.
249 * @want_bdev: T if want a blockdev
250 * @_path: The result of the lookup
252 int fs_lookup_param(struct fs_context *fc,
253 struct fs_parameter *param,
258 unsigned int flags = 0;
262 switch (param->type) {
263 case fs_value_is_string:
264 f = getname_kernel(param->string);
269 case fs_value_is_filename:
274 return invalf(fc, "%s: not usable as path", param->key);
277 f->refcnt++; /* filename_lookup() drops our ref. */
278 ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
280 errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
285 !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
287 _path->dentry = NULL;
289 errorf(fc, "%s: Non-blockdev passed as '%s'",
290 param->key, f->name);
299 EXPORT_SYMBOL(fs_lookup_param);
301 #ifdef CONFIG_VALIDATE_FS_PARSER
303 * validate_constant_table - Validate a constant table
304 * @name: Name to use in reporting
305 * @tbl: The constant table to validate.
306 * @tbl_size: The size of the table.
307 * @low: The lowest permissible value.
308 * @high: The highest permissible value.
309 * @special: One special permissible value outside of the range.
311 bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
312 int low, int high, int special)
318 pr_warn("VALIDATE C-TBL: Empty\n");
322 for (i = 0; i < tbl_size; i++) {
324 pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
326 } else if (i > 0 && tbl[i - 1].name) {
327 int c = strcmp(tbl[i-1].name, tbl[i].name);
330 pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
335 pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
336 i, tbl[i-1].name, tbl[i].name);
341 if (tbl[i].value != special &&
342 (tbl[i].value < low || tbl[i].value > high)) {
343 pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
344 i, tbl[i].name, tbl[i].value, low, high);
353 * fs_validate_description - Validate a parameter description
354 * @desc: The parameter description to validate.
356 bool fs_validate_description(const char *name,
357 const struct fs_parameter_spec *desc)
359 const struct fs_parameter_spec *param, *p2;
362 pr_notice("*** VALIDATE %s ***\n", name);
364 for (param = desc; param->name; param++) {
365 enum fs_parameter_type t = param->type;
367 /* Check that the type is in range */
368 if (t == __fs_param_wasnt_defined ||
369 t >= nr__fs_parameter_type) {
370 pr_err("VALIDATE %s: PARAM[%s] Bad type %u\n",
371 name, param->name, t);
373 } else if (t == fs_param_is_enum) {
374 const struct constant_table *e = param->data;
375 if (!e || !e->name) {
376 pr_err("VALIDATE %s: PARAM[%s] enum with no values\n",
382 /* Check for duplicate parameter names */
383 for (p2 = desc; p2 < param; p2++) {
384 if (strcmp(param->name, p2->name) == 0) {
385 pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
393 #endif /* CONFIG_VALIDATE_FS_PARSER */