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