1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * lib/parser.c - simple parser for mount, etc. options.
4 */
5
6 #include <linux/ctype.h>
7 #include <linux/types.h>
8 #include <linux/export.h>
9 #include <linux/kstrtox.h>
10 #include <linux/parser.h>
11 #include <linux/slab.h>
12 #include <linux/string.h>
13
14 /**
15 * match_one - Determines if a string matches a simple pattern
16 * @s: the string to examine for presence of the pattern
17 * @p: the string containing the pattern
18 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
19 * locations.
20 *
21 * Description: Determines if the pattern @p is present in string @s. Can only
22 * match extremely simple token=arg style patterns. If the pattern is found,
23 * the location(s) of the arguments will be returned in the @args array.
24 */
match_one(char * s,const char * p,substring_t args[])25 static int match_one(char *s, const char *p, substring_t args[])
26 {
27 char *meta;
28 int argc = 0;
29
30 if (!p)
31 return 1;
32
33 while(1) {
34 int len = -1;
35 meta = strchr(p, '%');
36 if (!meta)
37 return strcmp(p, s) == 0;
38
39 if (strncmp(p, s, meta-p))
40 return 0;
41
42 s += meta - p;
43 p = meta + 1;
44
45 if (isdigit(*p))
46 len = simple_strtoul(p, (char **) &p, 10);
47 else if (*p == '%') {
48 if (*s++ != '%')
49 return 0;
50 p++;
51 continue;
52 }
53
54 if (argc >= MAX_OPT_ARGS)
55 return 0;
56
57 args[argc].from = s;
58 switch (*p++) {
59 case 's': {
60 size_t str_len = strlen(s);
61
62 if (str_len == 0)
63 return 0;
64 if (len == -1 || len > str_len)
65 len = str_len;
66 args[argc].to = s + len;
67 break;
68 }
69 case 'd':
70 simple_strtol(s, &args[argc].to, 0);
71 goto num;
72 case 'u':
73 simple_strtoul(s, &args[argc].to, 0);
74 goto num;
75 case 'o':
76 simple_strtoul(s, &args[argc].to, 8);
77 goto num;
78 case 'x':
79 simple_strtoul(s, &args[argc].to, 16);
80 num:
81 if (args[argc].to == args[argc].from)
82 return 0;
83 break;
84 default:
85 return 0;
86 }
87 s = args[argc].to;
88 argc++;
89 }
90 }
91
92 /**
93 * match_token - Find a token (and optional args) in a string
94 * @s: the string to examine for token/argument pairs
95 * @table: match_table_t describing the set of allowed option tokens and the
96 * arguments that may be associated with them. Must be terminated with a
97 * &struct match_token whose pattern is set to the NULL pointer.
98 * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
99 * locations.
100 *
101 * Description: Detects which if any of a set of token strings has been passed
102 * to it. Tokens can include up to %MAX_OPT_ARGS instances of basic c-style
103 * format identifiers which will be taken into account when matching the
104 * tokens, and whose locations will be returned in the @args array.
105 */
match_token(char * s,const match_table_t table,substring_t args[])106 int match_token(char *s, const match_table_t table, substring_t args[])
107 {
108 const struct match_token *p;
109
110 for (p = table; !match_one(s, p->pattern, args) ; p++)
111 ;
112
113 return p->token;
114 }
115 EXPORT_SYMBOL(match_token);
116
117 /**
118 * match_number - scan a number in the given base from a substring_t
119 * @s: substring to be scanned
120 * @result: resulting integer on success
121 * @base: base to use when converting string
122 *
123 * Description: Given a &substring_t and a base, attempts to parse the substring
124 * as a number in that base.
125 *
126 * Return: On success, sets @result to the integer represented by the
127 * string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
128 */
match_number(substring_t * s,int * result,int base)129 static int match_number(substring_t *s, int *result, int base)
130 {
131 char *endp;
132 char *buf;
133 int ret;
134 long val;
135
136 buf = match_strdup(s);
137 if (!buf)
138 return -ENOMEM;
139
140 ret = 0;
141 val = simple_strtol(buf, &endp, base);
142 if (endp == buf)
143 ret = -EINVAL;
144 else if (val < (long)INT_MIN || val > (long)INT_MAX)
145 ret = -ERANGE;
146 else
147 *result = (int) val;
148 kfree(buf);
149 return ret;
150 }
151
152 /**
153 * match_u64int - scan a number in the given base from a substring_t
154 * @s: substring to be scanned
155 * @result: resulting u64 on success
156 * @base: base to use when converting string
157 *
158 * Description: Given a &substring_t and a base, attempts to parse the substring
159 * as a number in that base.
160 *
161 * Return: On success, sets @result to the integer represented by the
162 * string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
163 */
match_u64int(substring_t * s,u64 * result,int base)164 static int match_u64int(substring_t *s, u64 *result, int base)
165 {
166 char *buf;
167 int ret;
168 u64 val;
169
170 buf = match_strdup(s);
171 if (!buf)
172 return -ENOMEM;
173
174 ret = kstrtoull(buf, base, &val);
175 if (!ret)
176 *result = val;
177 kfree(buf);
178 return ret;
179 }
180
181 /**
182 * match_int - scan a decimal representation of an integer from a substring_t
183 * @s: substring_t to be scanned
184 * @result: resulting integer on success
185 *
186 * Description: Attempts to parse the &substring_t @s as a decimal integer.
187 *
188 * Return: On success, sets @result to the integer represented by the string
189 * and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
190 */
match_int(substring_t * s,int * result)191 int match_int(substring_t *s, int *result)
192 {
193 return match_number(s, result, 0);
194 }
195 EXPORT_SYMBOL(match_int);
196
197 /**
198 * match_uint - scan a decimal representation of an integer from a substring_t
199 * @s: substring_t to be scanned
200 * @result: resulting integer on success
201 *
202 * Description: Attempts to parse the &substring_t @s as a decimal integer.
203 *
204 * Return: On success, sets @result to the integer represented by the string
205 * and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
206 */
match_uint(substring_t * s,unsigned int * result)207 int match_uint(substring_t *s, unsigned int *result)
208 {
209 int err = -ENOMEM;
210 char *buf = match_strdup(s);
211
212 if (buf) {
213 err = kstrtouint(buf, 10, result);
214 kfree(buf);
215 }
216 return err;
217 }
218 EXPORT_SYMBOL(match_uint);
219
220 /**
221 * match_u64 - scan a decimal representation of a u64 from
222 * a substring_t
223 * @s: substring_t to be scanned
224 * @result: resulting unsigned long long on success
225 *
226 * Description: Attempts to parse the &substring_t @s as a long decimal
227 * integer.
228 *
229 * Return: On success, sets @result to the integer represented by the string
230 * and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
231 */
match_u64(substring_t * s,u64 * result)232 int match_u64(substring_t *s, u64 *result)
233 {
234 return match_u64int(s, result, 0);
235 }
236 EXPORT_SYMBOL(match_u64);
237
238 /**
239 * match_octal - scan an octal representation of an integer from a substring_t
240 * @s: substring_t to be scanned
241 * @result: resulting integer on success
242 *
243 * Description: Attempts to parse the &substring_t @s as an octal integer.
244 *
245 * Return: On success, sets @result to the integer represented by the string
246 * and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
247 */
match_octal(substring_t * s,int * result)248 int match_octal(substring_t *s, int *result)
249 {
250 return match_number(s, result, 8);
251 }
252 EXPORT_SYMBOL(match_octal);
253
254 /**
255 * match_hex - scan a hex representation of an integer from a substring_t
256 * @s: substring_t to be scanned
257 * @result: resulting integer on success
258 *
259 * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
260 *
261 * Return: On success, sets @result to the integer represented by the string
262 * and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
263 */
match_hex(substring_t * s,int * result)264 int match_hex(substring_t *s, int *result)
265 {
266 return match_number(s, result, 16);
267 }
268 EXPORT_SYMBOL(match_hex);
269
270 /**
271 * match_wildcard - parse if a string matches given wildcard pattern
272 * @pattern: wildcard pattern
273 * @str: the string to be parsed
274 *
275 * Description: Parse the string @str to check if matches wildcard
276 * pattern @pattern. The pattern may contain two types of wildcards:
277 * '*' - matches zero or more characters
278 * '?' - matches one character
279 *
280 * Return: If the @str matches the @pattern, return true, else return false.
281 */
match_wildcard(const char * pattern,const char * str)282 bool match_wildcard(const char *pattern, const char *str)
283 {
284 const char *s = str;
285 const char *p = pattern;
286 bool star = false;
287
288 while (*s) {
289 switch (*p) {
290 case '?':
291 s++;
292 p++;
293 break;
294 case '*':
295 star = true;
296 str = s;
297 if (!*++p)
298 return true;
299 pattern = p;
300 break;
301 default:
302 if (*s == *p) {
303 s++;
304 p++;
305 } else {
306 if (!star)
307 return false;
308 str++;
309 s = str;
310 p = pattern;
311 }
312 break;
313 }
314 }
315
316 if (*p == '*')
317 ++p;
318 return !*p;
319 }
320 EXPORT_SYMBOL(match_wildcard);
321
322 /**
323 * match_strlcpy - Copy the characters from a substring_t to a sized buffer
324 * @dest: where to copy to
325 * @src: &substring_t to copy
326 * @size: size of destination buffer
327 *
328 * Description: Copy the characters in &substring_t @src to the
329 * c-style string @dest. Copy no more than @size - 1 characters, plus
330 * the terminating NUL.
331 *
332 * Return: length of @src.
333 */
match_strlcpy(char * dest,const substring_t * src,size_t size)334 size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
335 {
336 size_t ret = src->to - src->from;
337
338 if (size) {
339 size_t len = ret >= size ? size - 1 : ret;
340 memcpy(dest, src->from, len);
341 dest[len] = '\0';
342 }
343 return ret;
344 }
345 EXPORT_SYMBOL(match_strlcpy);
346
347 /**
348 * match_strdup - allocate a new string with the contents of a substring_t
349 * @s: &substring_t to copy
350 *
351 * Description: Allocates and returns a string filled with the contents of
352 * the &substring_t @s. The caller is responsible for freeing the returned
353 * string with kfree().
354 *
355 * Return: the address of the newly allocated NUL-terminated string or
356 * %NULL on error.
357 */
match_strdup(const substring_t * s)358 char *match_strdup(const substring_t *s)
359 {
360 return kmemdup_nul(s->from, s->to - s->from, GFP_KERNEL);
361 }
362 EXPORT_SYMBOL(match_strdup);
363