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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/* Filesystem superblock creation and reconfiguration context.
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_CONTEXT_H
9#define _LINUX_FS_CONTEXT_H
10
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>
16
17struct cred;
18struct dentry;
19struct file_operations;
20struct file_system_type;
21struct mnt_namespace;
22struct net;
23struct pid_namespace;
24struct super_block;
25struct user_namespace;
26struct vfsmount;
27struct path;
28
29enum 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) */
33};
34
35/*
36 * Userspace usage phase for fsopen/fspick.
37 */
38enum 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 */
46};
47
48/*
49 * Type of parameter value.
50 */
51enum fs_value_type {
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_file, /* Value is a file* */
58};
59
60/*
61 * Configuration parameter.
62 */
63struct fs_parameter {
64 const char *key; /* Parameter name */
65 enum fs_value_type type:8; /* The type of value here */
66 union {
67 char *string;
68 void *blob;
69 struct filename *name;
70 struct file *file;
71 };
72 size_t size;
73 int dirfd;
74};
75
76struct p_log {
77 const char *prefix;
78 struct fc_log *log;
79};
80
81/*
82 * Filesystem context for holding the parameters used in the creation or
83 * reconfiguration of a superblock.
84 *
85 * Superblock creation fills in ->root whereas reconfiguration begins with this
86 * already set.
87 *
88 * See Documentation/filesystems/mount_api.txt
89 */
90struct fs_context {
91 const struct fs_context_operations *ops;
92 struct mutex uapi_mutex; /* Userspace access mutex */
93 struct file_system_type *fs_type;
94 void *fs_private; /* The filesystem's context */
95 void *sget_key;
96 struct dentry *root; /* The root and superblock */
97 struct user_namespace *user_ns; /* The user namespace for this mount */
98 struct net *net_ns; /* The network namespace for this mount */
99 const struct cred *cred; /* The mounter's credentials */
100 struct p_log log; /* Logging buffer */
101 const char *source; /* The source name (eg. dev path) */
102 void *security; /* Linux S&M options */
103 void *s_fs_info; /* Proposed s_fs_info */
104 unsigned int sb_flags; /* Proposed superblock flags (SB_*) */
105 unsigned int sb_flags_mask; /* Superblock flags that were changed */
106 unsigned int s_iflags; /* OR'd with sb->s_iflags */
107 unsigned int lsm_flags; /* Information flags from the fs to the LSM */
108 enum fs_context_purpose purpose:8;
109 enum fs_context_phase phase:8; /* The phase the context is in */
110 bool need_free:1; /* Need to call ops->free() */
111 bool global:1; /* Goes into &init_user_ns */
112};
113
114struct fs_context_operations {
115 void (*free)(struct fs_context *fc);
116 int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
117 int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
118 int (*parse_monolithic)(struct fs_context *fc, void *data);
119 int (*get_tree)(struct fs_context *fc);
120 int (*reconfigure)(struct fs_context *fc);
121};
122
123/*
124 * fs_context manipulation functions.
125 */
126extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
127 unsigned int sb_flags);
128extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
129 unsigned int sb_flags,
130 unsigned int sb_flags_mask);
131extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
132 struct dentry *reference);
133
134extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
135extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
136extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
137 const char *value, size_t v_size);
138extern int generic_parse_monolithic(struct fs_context *fc, void *data);
139extern int vfs_get_tree(struct fs_context *fc);
140extern void put_fs_context(struct fs_context *fc);
141
142/*
143 * sget() wrappers to be called from the ->get_tree() op.
144 */
145enum vfs_get_super_keying {
146 vfs_get_single_super, /* Only one such superblock may exist */
147 vfs_get_single_reconf_super, /* As above, but reconfigure if it exists */
148 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */
149 vfs_get_independent_super, /* Multiple independent superblocks may exist */
150};
151extern int vfs_get_super(struct fs_context *fc,
152 enum vfs_get_super_keying keying,
153 int (*fill_super)(struct super_block *sb,
154 struct fs_context *fc));
155
156extern int get_tree_nodev(struct fs_context *fc,
157 int (*fill_super)(struct super_block *sb,
158 struct fs_context *fc));
159extern int get_tree_single(struct fs_context *fc,
160 int (*fill_super)(struct super_block *sb,
161 struct fs_context *fc));
162extern int get_tree_single_reconf(struct fs_context *fc,
163 int (*fill_super)(struct super_block *sb,
164 struct fs_context *fc));
165extern int get_tree_keyed(struct fs_context *fc,
166 int (*fill_super)(struct super_block *sb,
167 struct fs_context *fc),
168 void *key);
169
170extern int get_tree_bdev(struct fs_context *fc,
171 int (*fill_super)(struct super_block *sb,
172 struct fs_context *fc));
173
174extern const struct file_operations fscontext_fops;
175
176/*
177 * Mount error, warning and informational message logging. This structure is
178 * shareable between a mount and a subordinate mount.
179 */
180struct fc_log {
181 refcount_t usage;
182 u8 head; /* Insertion index in buffer[] */
183 u8 tail; /* Removal index in buffer[] */
184 u8 need_free; /* Mask of kfree'able items in buffer[] */
185 struct module *owner; /* Owner module for strings that don't then need freeing */
186 char *buffer[8];
187};
188
189extern __attribute__((format(printf, 4, 5)))
190void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...);
191
192#define __logfc(fc, l, fmt, ...) logfc((fc)->log.log, NULL, \
193 l, fmt, ## __VA_ARGS__)
194#define __plog(p, l, fmt, ...) logfc((p)->log, (p)->prefix, \
195 l, fmt, ## __VA_ARGS__)
196/**
197 * infof - Store supplementary informational message
198 * @fc: The context in which to log the informational message
199 * @fmt: The format string
200 *
201 * Store the supplementary informational message for the process if the process
202 * has enabled the facility.
203 */
204#define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__)
205#define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__)
206#define infofc(p, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__)
207
208/**
209 * warnf - Store supplementary warning message
210 * @fc: The context in which to log the error message
211 * @fmt: The format string
212 *
213 * Store the supplementary warning message for the process if the process has
214 * enabled the facility.
215 */
216#define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__)
217#define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__)
218#define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__)
219
220/**
221 * errorf - Store supplementary error message
222 * @fc: The context in which to log the error message
223 * @fmt: The format string
224 *
225 * Store the supplementary error message for the process if the process has
226 * enabled the facility.
227 */
228#define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__)
229#define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__)
230#define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__)
231
232/**
233 * invalf - Store supplementary invalid argument error message
234 * @fc: The context in which to log the error message
235 * @fmt: The format string
236 *
237 * Store the supplementary error message for the process if the process has
238 * enabled the facility and return -EINVAL.
239 */
240#define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL)
241#define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL)
242#define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL)
243
244#endif /* _LINUX_FS_CONTEXT_H */