xref: /linux/include/linux/fs_parser.h (revision 2622f290417001b0440f4a48dc6978f5f1e12a56)
1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Filesystem parameter description and parser
3  *
4  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #ifndef _LINUX_FS_PARSER_H
9 #define _LINUX_FS_PARSER_H
10 
11 #include <linux/fs_context.h>
12 
13 struct path;
14 
15 struct constant_table {
16 	const char	*name;
17 	int		value;
18 };
19 
20 struct fs_parameter_spec;
21 struct fs_parse_result;
22 typedef int fs_param_type(struct p_log *,
23 			  const struct fs_parameter_spec *,
24 			  struct fs_parameter *,
25 			  struct fs_parse_result *);
26 /*
27  * The type of parameter expected.
28  */
29 fs_param_type fs_param_is_bool, fs_param_is_u32, fs_param_is_s32, fs_param_is_u64,
30 	fs_param_is_enum, fs_param_is_string, fs_param_is_blob, fs_param_is_blockdev,
31 	fs_param_is_path, fs_param_is_fd, fs_param_is_uid, fs_param_is_gid,
32 	fs_param_is_file_or_string;
33 
34 /*
35  * Specification of the type of value a parameter wants.
36  *
37  * Note that the fsparam_flag(), fsparam_string(), fsparam_u32(), ... macros
38  * should be used to generate elements of this type.
39  */
40 struct fs_parameter_spec {
41 	const char		*name;
42 	fs_param_type		*type;	/* The desired parameter type */
43 	u8			opt;	/* Option number (returned by fs_parse()) */
44 	unsigned short		flags;
45 #define fs_param_neg_with_no	0x0002	/* "noxxx" is negative param */
46 #define fs_param_can_be_empty	0x0004	/* "xxx=" is allowed */
47 #define fs_param_deprecated	0x0008	/* The param is deprecated */
48 	const void		*data;
49 };
50 
51 /*
52  * Result of parse.
53  */
54 struct fs_parse_result {
55 	bool			negated;	/* T if param was "noxxx" */
56 	union {
57 		bool		boolean;	/* For spec_bool */
58 		int		int_32;		/* For spec_s32/spec_enum */
59 		unsigned int	uint_32;	/* For spec_u32{,_octal,_hex}/spec_enum */
60 		u64		uint_64;	/* For spec_u64 */
61 		kuid_t		uid;
62 		kgid_t		gid;
63 	};
64 };
65 
66 extern int __fs_parse(struct p_log *log,
67 		    const struct fs_parameter_spec *desc,
68 		    struct fs_parameter *value,
69 		    struct fs_parse_result *result);
70 
fs_parse(struct fs_context * fc,const struct fs_parameter_spec * desc,struct fs_parameter * param,struct fs_parse_result * result)71 static inline int fs_parse(struct fs_context *fc,
72 	     const struct fs_parameter_spec *desc,
73 	     struct fs_parameter *param,
74 	     struct fs_parse_result *result)
75 {
76 	return __fs_parse(&fc->log, desc, param, result);
77 }
78 
79 extern int fs_lookup_param(struct fs_context *fc,
80 			   struct fs_parameter *param,
81 			   bool want_bdev,
82 			   unsigned int flags,
83 			   struct path *_path);
84 
85 extern int lookup_constant(const struct constant_table tbl[], const char *name, int not_found);
86 
87 extern const struct constant_table bool_names[];
88 
89 #ifdef CONFIG_VALIDATE_FS_PARSER
90 extern bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
91 				    int low, int high, int special);
92 extern bool fs_validate_description(const char *name,
93 				    const struct fs_parameter_spec *desc);
94 #else
validate_constant_table(const struct constant_table * tbl,size_t tbl_size,int low,int high,int special)95 static inline bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
96 					   int low, int high, int special)
97 { return true; }
fs_validate_description(const char * name,const struct fs_parameter_spec * desc)98 static inline bool fs_validate_description(const char *name,
99 					   const struct fs_parameter_spec *desc)
100 { return true; }
101 #endif
102 
103 /*
104  * Parameter type, name, index and flags element constructors.  Use as:
105  *
106  *  fsparam_xxxx("foo", Opt_foo)
107  *
108  * If existing helpers are not enough, direct use of __fsparam() would
109  * work, but any such case is probably a sign that new helper is needed.
110  * Helpers will remain stable; low-level implementation may change.
111  */
112 #define __fsparam(TYPE, NAME, OPT, FLAGS, DATA) \
113 	{ \
114 		.name = NAME, \
115 		.opt = OPT, \
116 		.type = TYPE, \
117 		.flags = FLAGS, \
118 		.data = DATA \
119 	}
120 
121 #define fsparam_flag(NAME, OPT)	__fsparam(NULL, NAME, OPT, 0, NULL)
122 #define fsparam_flag_no(NAME, OPT) \
123 			__fsparam(NULL, NAME, OPT, fs_param_neg_with_no, NULL)
124 #define fsparam_bool(NAME, OPT)	__fsparam(fs_param_is_bool, NAME, OPT, 0, NULL)
125 #define fsparam_u32(NAME, OPT)	__fsparam(fs_param_is_u32, NAME, OPT, 0, NULL)
126 #define fsparam_u32oct(NAME, OPT) \
127 			__fsparam(fs_param_is_u32, NAME, OPT, 0, (void *)8)
128 #define fsparam_u32hex(NAME, OPT) \
129 			__fsparam(fs_param_is_u32_hex, NAME, OPT, 0, (void *)16)
130 #define fsparam_s32(NAME, OPT)	__fsparam(fs_param_is_s32, NAME, OPT, 0, NULL)
131 #define fsparam_u64(NAME, OPT)	__fsparam(fs_param_is_u64, NAME, OPT, 0, NULL)
132 #define fsparam_enum(NAME, OPT, array)	__fsparam(fs_param_is_enum, NAME, OPT, 0, array)
133 #define fsparam_string(NAME, OPT) \
134 				__fsparam(fs_param_is_string, NAME, OPT, 0, NULL)
135 #define fsparam_blob(NAME, OPT)	__fsparam(fs_param_is_blob, NAME, OPT, 0, NULL)
136 #define fsparam_bdev(NAME, OPT)	__fsparam(fs_param_is_blockdev, NAME, OPT, 0, NULL)
137 #define fsparam_path(NAME, OPT)	__fsparam(fs_param_is_path, NAME, OPT, 0, NULL)
138 #define fsparam_fd(NAME, OPT)	__fsparam(fs_param_is_fd, NAME, OPT, 0, NULL)
139 #define fsparam_file_or_string(NAME, OPT) \
140 				__fsparam(fs_param_is_file_or_string, NAME, OPT, 0, NULL)
141 #define fsparam_uid(NAME, OPT) __fsparam(fs_param_is_uid, NAME, OPT, 0, NULL)
142 #define fsparam_gid(NAME, OPT) __fsparam(fs_param_is_gid, NAME, OPT, 0, NULL)
143 
144 /* String parameter that allows empty argument */
145 #define fsparam_string_empty(NAME, OPT) \
146 	__fsparam(fs_param_is_string, NAME, OPT, fs_param_can_be_empty, NULL)
147 
148 #endif /* _LINUX_FS_PARSER_H */
149