1/* Filesystem superblock creation and reconfiguration context.
2 *
3 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#ifndef _LINUX_FS_CONTEXT_H
13#define _LINUX_FS_CONTEXT_H
14
15#include <linux/kernel.h>
16#include <linux/errno.h>
17#include <linux/security.h>
18
19struct cred;
20struct dentry;
21struct file_operations;
22struct file_system_type;
23struct mnt_namespace;
24struct net;
25struct pid_namespace;
26struct super_block;
27struct user_namespace;
28struct vfsmount;
29struct path;
30
31enum fs_context_purpose {
32 FS_CONTEXT_FOR_MOUNT, /* New superblock for explicit mount */
33 FS_CONTEXT_FOR_SUBMOUNT, /* New superblock for automatic submount */
34 FS_CONTEXT_FOR_RECONFIGURE, /* Superblock reconfiguration (remount) */
35};
36
37/*
38 * Type of parameter value.
39 */
40enum fs_value_type {
41 fs_value_is_undefined,
42 fs_value_is_flag, /* Value not given a value */
43 fs_value_is_string, /* Value is a string */
44 fs_value_is_blob, /* Value is a binary blob */
45 fs_value_is_filename, /* Value is a filename* + dirfd */
46 fs_value_is_filename_empty, /* Value is a filename* + dirfd + AT_EMPTY_PATH */
47 fs_value_is_file, /* Value is a file* */
48};
49
50/*
51 * Configuration parameter.
52 */
53struct fs_parameter {
54 const char *key; /* Parameter name */
55 enum fs_value_type type:8; /* The type of value here */
56 union {
57 char *string;
58 void *blob;
59 struct filename *name;
60 struct file *file;
61 };
62 size_t size;
63 int dirfd;
64};
65
66/*
67 * Filesystem context for holding the parameters used in the creation or
68 * reconfiguration of a superblock.
69 *
70 * Superblock creation fills in ->root whereas reconfiguration begins with this
71 * already set.
72 *
73 * See Documentation/filesystems/mounting.txt
74 */
75struct fs_context {
76 const struct fs_context_operations *ops;
77 struct file_system_type *fs_type;
78 void *fs_private; /* The filesystem's context */
79 struct dentry *root; /* The root and superblock */
80 struct user_namespace *user_ns; /* The user namespace for this mount */
81 struct net *net_ns; /* The network namespace for this mount */
82 const struct cred *cred; /* The mounter's credentials */
83 const char *source; /* The source name (eg. dev path) */
84 const char *subtype; /* The subtype to set on the superblock */
85 void *security; /* Linux S&M options */
86 void *s_fs_info; /* Proposed s_fs_info */
87 unsigned int sb_flags; /* Proposed superblock flags (SB_*) */
88 unsigned int sb_flags_mask; /* Superblock flags that were changed */
89 unsigned int lsm_flags; /* Information flags from the fs to the LSM */
90 enum fs_context_purpose purpose:8;
91 bool need_free:1; /* Need to call ops->free() */
92 bool global:1; /* Goes into &init_user_ns */
93};
94
95struct fs_context_operations {
96 void (*free)(struct fs_context *fc);
97 int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
98 int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
99 int (*parse_monolithic)(struct fs_context *fc, void *data);
100 int (*get_tree)(struct fs_context *fc);
101 int (*reconfigure)(struct fs_context *fc);
102};
103
104/*
105 * fs_context manipulation functions.
106 */
107extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
108 unsigned int sb_flags);
109extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
110 unsigned int sb_flags,
111 unsigned int sb_flags_mask);
112extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
113 struct dentry *reference);
114
115extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
116extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
117extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
118 const char *value, size_t v_size);
119extern int generic_parse_monolithic(struct fs_context *fc, void *data);
120extern int vfs_get_tree(struct fs_context *fc);
121extern void put_fs_context(struct fs_context *fc);
122
123/*
124 * sget() wrapper to be called from the ->get_tree() op.
125 */
126enum vfs_get_super_keying {
127 vfs_get_single_super, /* Only one such superblock may exist */
128 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */
129 vfs_get_independent_super, /* Multiple independent superblocks may exist */
130};
131extern int vfs_get_super(struct fs_context *fc,
132 enum vfs_get_super_keying keying,
133 int (*fill_super)(struct super_block *sb,
134 struct fs_context *fc));
135
136extern const struct file_operations fscontext_fops;
137
138#ifdef CONFIG_PRINTK
139extern __attribute__((format(printf, 2, 3)))
140void logfc(struct fs_context *fc, const char *fmt, ...);
141#else
142static inline __attribute__((format(printf, 2, 3)))
143void logfc(struct fs_context *fc, const char *fmt, ...)
144{
145}
146#endif
147
148/**
149 * infof - Store supplementary informational message
150 * @fc: The context in which to log the informational message
151 * @fmt: The format string
152 *
153 * Store the supplementary informational message for the process if the process
154 * has enabled the facility.
155 */
156#define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); })
157
158/**
159 * warnf - Store supplementary warning message
160 * @fc: The context in which to log the error message
161 * @fmt: The format string
162 *
163 * Store the supplementary warning message for the process if the process has
164 * enabled the facility.
165 */
166#define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); })
167
168/**
169 * errorf - Store supplementary error message
170 * @fc: The context in which to log the error message
171 * @fmt: The format string
172 *
173 * Store the supplementary error message for the process if the process has
174 * enabled the facility.
175 */
176#define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); })
177
178/**
179 * invalf - Store supplementary invalid argument error message
180 * @fc: The context in which to log the error message
181 * @fmt: The format string
182 *
183 * Store the supplementary error message for the process if the process has
184 * enabled the facility and return -EINVAL.
185 */
186#define invalf(fc, fmt, ...) ({ errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; })
187
188#endif /* _LINUX_FS_CONTEXT_H */
189