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