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