1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Filesystem superblock creation and reconfiguration context.
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
8 #ifndef _LINUX_FS_CONTEXT_H
9 #define _LINUX_FS_CONTEXT_H
11 #include <linux/kernel.h>
12 #include <linux/refcount.h>
13 #include <linux/errno.h>
14 #include <linux/security.h>
15 #include <linux/mutex.h>
19 struct file_operations;
20 struct file_system_type;
25 struct user_namespace;
29 enum fs_context_purpose {
30 FS_CONTEXT_FOR_MOUNT, /* New superblock for explicit mount */
31 FS_CONTEXT_FOR_SUBMOUNT, /* New superblock for automatic submount */
32 FS_CONTEXT_FOR_RECONFIGURE, /* Superblock reconfiguration (remount) */
36 * Userspace usage phase for fsopen/fspick.
38 enum fs_context_phase {
39 FS_CONTEXT_CREATE_PARAMS, /* Loading params for sb creation */
40 FS_CONTEXT_CREATING, /* A superblock is being created */
41 FS_CONTEXT_AWAITING_MOUNT, /* Superblock created, awaiting fsmount() */
42 FS_CONTEXT_AWAITING_RECONF, /* Awaiting initialisation for reconfiguration */
43 FS_CONTEXT_RECONF_PARAMS, /* Loading params for reconfiguration */
44 FS_CONTEXT_RECONFIGURING, /* Reconfiguring the superblock */
45 FS_CONTEXT_FAILED, /* Failed to correctly transition a context */
49 * Type of parameter value.
52 fs_value_is_undefined,
53 fs_value_is_flag, /* Value not given a value */
54 fs_value_is_string, /* Value is a string */
55 fs_value_is_blob, /* Value is a binary blob */
56 fs_value_is_filename, /* Value is a filename* + dirfd */
57 fs_value_is_filename_empty, /* Value is a filename* + dirfd + AT_EMPTY_PATH */
58 fs_value_is_file, /* Value is a file* */
62 * Configuration parameter.
65 const char *key; /* Parameter name */
66 enum fs_value_type type:8; /* The type of value here */
70 struct filename *name;
78 * Filesystem context for holding the parameters used in the creation or
79 * reconfiguration of a superblock.
81 * Superblock creation fills in ->root whereas reconfiguration begins with this
84 * See Documentation/filesystems/mount_api.txt
87 const struct fs_context_operations *ops;
88 struct mutex uapi_mutex; /* Userspace access mutex */
89 struct file_system_type *fs_type;
90 void *fs_private; /* The filesystem's context */
92 struct dentry *root; /* The root and superblock */
93 struct user_namespace *user_ns; /* The user namespace for this mount */
94 struct net *net_ns; /* The network namespace for this mount */
95 const struct cred *cred; /* The mounter's credentials */
96 struct fc_log *log; /* Logging buffer */
97 const char *source; /* The source name (eg. dev path) */
98 const char *subtype; /* The subtype to set on the superblock */
99 void *security; /* Linux S&M options */
100 void *s_fs_info; /* Proposed s_fs_info */
101 unsigned int sb_flags; /* Proposed superblock flags (SB_*) */
102 unsigned int sb_flags_mask; /* Superblock flags that were changed */
103 unsigned int s_iflags; /* OR'd with sb->s_iflags */
104 unsigned int lsm_flags; /* Information flags from the fs to the LSM */
105 enum fs_context_purpose purpose:8;
106 enum fs_context_phase phase:8; /* The phase the context is in */
107 bool need_free:1; /* Need to call ops->free() */
108 bool global:1; /* Goes into &init_user_ns */
111 struct fs_context_operations {
112 void (*free)(struct fs_context *fc);
113 int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
114 int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
115 int (*parse_monolithic)(struct fs_context *fc, void *data);
116 int (*get_tree)(struct fs_context *fc);
117 int (*reconfigure)(struct fs_context *fc);
121 * fs_context manipulation functions.
123 extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
124 unsigned int sb_flags);
125 extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
126 unsigned int sb_flags,
127 unsigned int sb_flags_mask);
128 extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
129 struct dentry *reference);
131 extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
132 extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
133 extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
134 const char *value, size_t v_size);
135 extern int generic_parse_monolithic(struct fs_context *fc, void *data);
136 extern int vfs_get_tree(struct fs_context *fc);
137 extern void put_fs_context(struct fs_context *fc);
140 * sget() wrappers to be called from the ->get_tree() op.
142 enum vfs_get_super_keying {
143 vfs_get_single_super, /* Only one such superblock may exist */
144 vfs_get_single_reconf_super, /* As above, but reconfigure if it exists */
145 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */
146 vfs_get_independent_super, /* Multiple independent superblocks may exist */
148 extern int vfs_get_super(struct fs_context *fc,
149 enum vfs_get_super_keying keying,
150 int (*fill_super)(struct super_block *sb,
151 struct fs_context *fc));
153 extern int get_tree_nodev(struct fs_context *fc,
154 int (*fill_super)(struct super_block *sb,
155 struct fs_context *fc));
156 extern int get_tree_single(struct fs_context *fc,
157 int (*fill_super)(struct super_block *sb,
158 struct fs_context *fc));
159 extern int get_tree_single_reconf(struct fs_context *fc,
160 int (*fill_super)(struct super_block *sb,
161 struct fs_context *fc));
162 extern int get_tree_keyed(struct fs_context *fc,
163 int (*fill_super)(struct super_block *sb,
164 struct fs_context *fc),
167 extern int get_tree_bdev(struct fs_context *fc,
168 int (*fill_super)(struct super_block *sb,
169 struct fs_context *fc));
171 extern const struct file_operations fscontext_fops;
174 * Mount error, warning and informational message logging. This structure is
175 * shareable between a mount and a subordinate mount.
179 u8 head; /* Insertion index in buffer[] */
180 u8 tail; /* Removal index in buffer[] */
181 u8 need_free; /* Mask of kfree'able items in buffer[] */
182 struct module *owner; /* Owner module for strings that don't then need freeing */
186 extern __attribute__((format(printf, 2, 3)))
187 void logfc(struct fs_context *fc, const char *fmt, ...);
190 * infof - Store supplementary informational message
191 * @fc: The context in which to log the informational message
192 * @fmt: The format string
194 * Store the supplementary informational message for the process if the process
195 * has enabled the facility.
197 #define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); })
200 * warnf - Store supplementary warning message
201 * @fc: The context in which to log the error message
202 * @fmt: The format string
204 * Store the supplementary warning message for the process if the process has
205 * enabled the facility.
207 #define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); })
210 * errorf - Store supplementary error message
211 * @fc: The context in which to log the error message
212 * @fmt: The format string
214 * Store the supplementary error message for the process if the process has
215 * enabled the facility.
217 #define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); })
220 * invalf - Store supplementary invalid argument error message
221 * @fc: The context in which to log the error message
222 * @fmt: The format string
224 * Store the supplementary error message for the process if the process has
225 * enabled the facility and return -EINVAL.
227 #define invalf(fc, fmt, ...) ({ errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; })
229 #endif /* _LINUX_FS_CONTEXT_H */