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