fs_parser.h

  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
 13struct path;
 14
 15struct constant_table {
 16	const char	*name;
 17	int		value;
 18};
 19
 20struct fs_parameter_spec;
 21struct fs_parse_result;
 22typedef 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 */
 29fs_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 */
 40struct 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 */
 54struct 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
 66extern 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
 71static 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
 79extern 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
 85extern int lookup_constant(const struct constant_table tbl[], const char *name, int not_found);
 86
 87extern const struct constant_table bool_names[];
 88
 89#ifdef CONFIG_VALIDATE_FS_PARSER
 90extern bool fs_validate_description(const char *name,
 91				    const struct fs_parameter_spec *desc);
 92#else
 93static inline bool fs_validate_description(const char *name,
 94					   const struct fs_parameter_spec *desc)
 95{ return true; }
 96#endif
 97
 98/*
 99 * Parameter type, name, index and flags element constructors.  Use as:
100 *
101 *  fsparam_xxxx("foo", Opt_foo)
102 *
103 * If existing helpers are not enough, direct use of __fsparam() would
104 * work, but any such case is probably a sign that new helper is needed.
105 * Helpers will remain stable; low-level implementation may change.
106 */
107#define __fsparam(TYPE, NAME, OPT, FLAGS, DATA) \
108	{ \
109		.name = NAME, \
110		.opt = OPT, \
111		.type = TYPE, \
112		.flags = FLAGS, \
113		.data = DATA \
114	}
115
116#define fsparam_flag(NAME, OPT)	__fsparam(NULL, NAME, OPT, 0, NULL)
117#define fsparam_flag_no(NAME, OPT) \
118			__fsparam(NULL, NAME, OPT, fs_param_neg_with_no, NULL)
119#define fsparam_bool(NAME, OPT)	__fsparam(fs_param_is_bool, NAME, OPT, 0, NULL)
120#define fsparam_u32(NAME, OPT)	__fsparam(fs_param_is_u32, NAME, OPT, 0, NULL)
121#define fsparam_u32oct(NAME, OPT) \
122			__fsparam(fs_param_is_u32, NAME, OPT, 0, (void *)8)
123#define fsparam_u32hex(NAME, OPT) \
124			__fsparam(fs_param_is_u32, NAME, OPT, 0, (void *)16)
125#define fsparam_s32(NAME, OPT)	__fsparam(fs_param_is_s32, NAME, OPT, 0, NULL)
126#define fsparam_u64(NAME, OPT)	__fsparam(fs_param_is_u64, NAME, OPT, 0, NULL)
127#define fsparam_enum(NAME, OPT, array)	__fsparam(fs_param_is_enum, NAME, OPT, 0, array)
128#define fsparam_string(NAME, OPT) \
129				__fsparam(fs_param_is_string, NAME, OPT, 0, NULL)
130#define fsparam_blob(NAME, OPT)	__fsparam(fs_param_is_blob, NAME, OPT, 0, NULL)
131#define fsparam_bdev(NAME, OPT)	__fsparam(fs_param_is_blockdev, NAME, OPT, 0, NULL)
132#define fsparam_path(NAME, OPT)	__fsparam(fs_param_is_path, NAME, OPT, 0, NULL)
133#define fsparam_fd(NAME, OPT)	__fsparam(fs_param_is_fd, NAME, OPT, 0, NULL)
134#define fsparam_file_or_string(NAME, OPT) \
135				__fsparam(fs_param_is_file_or_string, 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 */