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.rst
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; /* LSM 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 enum fs_context_purpose purpose:8;
108 enum fs_context_phase phase:8; /* The phase the context is in */
109 bool need_free:1; /* Need to call ops->free() */
110 bool global:1; /* Goes into &init_user_ns */
111 bool oldapi:1; /* Coming from mount(2) */
112 bool exclusive:1; /* create new superblock, reject existing one */
113};
114
115struct fs_context_operations {
116 void (*free)(struct fs_context *fc);
117 int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
118 int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
119 int (*parse_monolithic)(struct fs_context *fc, void *data);
120 int (*get_tree)(struct fs_context *fc);
121 int (*reconfigure)(struct fs_context *fc);
122};
123
124/*
125 * fs_context manipulation functions.
126 */
127extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
128 unsigned int sb_flags);
129extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
130 unsigned int sb_flags,
131 unsigned int sb_flags_mask);
132extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
133 struct dentry *reference);
134
135extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
136extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
137extern int vfs_parse_fs_qstr(struct fs_context *fc, const char *key,
138 const struct qstr *value);
139static inline int vfs_parse_fs_string(struct fs_context *fc, const char *key,
140 const char *value)
141{
142 return vfs_parse_fs_qstr(fc, key, value: value ? &QSTR(value) : NULL);
143}
144int vfs_parse_monolithic_sep(struct fs_context *fc, void *data,
145 char *(*sep)(char **));
146extern int generic_parse_monolithic(struct fs_context *fc, void *data);
147extern int vfs_get_tree(struct fs_context *fc);
148extern void put_fs_context(struct fs_context *fc);
149extern int vfs_parse_fs_param_source(struct fs_context *fc,
150 struct fs_parameter *param);
151extern void fc_drop_locked(struct fs_context *fc);
152
153extern int get_tree_nodev(struct fs_context *fc,
154 int (*fill_super)(struct super_block *sb,
155 struct fs_context *fc));
156extern int get_tree_single(struct fs_context *fc,
157 int (*fill_super)(struct super_block *sb,
158 struct fs_context *fc));
159extern int get_tree_keyed(struct fs_context *fc,
160 int (*fill_super)(struct super_block *sb,
161 struct fs_context *fc),
162 void *key);
163
164int setup_bdev_super(struct super_block *sb, int sb_flags,
165 struct fs_context *fc);
166
167#define GET_TREE_BDEV_QUIET_LOOKUP 0x0001
168int get_tree_bdev_flags(struct fs_context *fc,
169 int (*fill_super)(struct super_block *sb,
170 struct fs_context *fc), unsigned int flags);
171
172extern int get_tree_bdev(struct fs_context *fc,
173 int (*fill_super)(struct super_block *sb,
174 struct fs_context *fc));
175
176extern const struct file_operations fscontext_fops;
177
178/*
179 * Mount error, warning and informational message logging. This structure is
180 * shareable between a mount and a subordinate mount.
181 */
182struct fc_log {
183 refcount_t usage;
184 u8 head; /* Insertion index in buffer[] */
185 u8 tail; /* Removal index in buffer[] */
186 u8 need_free; /* Mask of kfree'able items in buffer[] */
187 struct module *owner; /* Owner module for strings that don't then need freeing */
188 char *buffer[8];
189};
190
191extern __attribute__((format(printf, 4, 5)))
192void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...);
193
194#define __logfc(fc, l, fmt, ...) \
195 logfc((fc)->log.log, NULL, (l), (fmt), ## __VA_ARGS__)
196#define __plogp(p, prefix, l, fmt, ...) \
197 logfc((p)->log, (prefix), (l), (fmt), ## __VA_ARGS__)
198#define __plog(p, l, fmt, ...) __plogp(p, (p)->prefix, l, fmt, ## __VA_ARGS__)
199
200/**
201 * infof - Store supplementary informational message
202 * @fc: The context in which to log the informational message
203 * @fmt: The format string
204 *
205 * Store the supplementary informational message for the process if the process
206 * has enabled the facility.
207 */
208#define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__)
209#define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__)
210#define infofc(fc, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__)
211#define infofcp(fc, prefix, fmt, ...) \
212 __plogp((&(fc)->log), prefix, 'i', fmt, ## __VA_ARGS__)
213
214/**
215 * warnf - Store supplementary warning message
216 * @fc: The context in which to log the error message
217 * @fmt: The format string
218 *
219 * Store the supplementary warning message for the process if the process has
220 * enabled the facility.
221 */
222#define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__)
223#define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__)
224#define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__)
225#define warnfcp(fc, prefix, fmt, ...) \
226 __plogp((&(fc)->log), prefix, 'w', fmt, ## __VA_ARGS__)
227
228/**
229 * errorf - Store supplementary error message
230 * @fc: The context in which to log the error message
231 * @fmt: The format string
232 *
233 * Store the supplementary error message for the process if the process has
234 * enabled the facility.
235 */
236#define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__)
237#define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__)
238#define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__)
239#define errorfcp(fc, prefix, fmt, ...) \
240 __plogp((&(fc)->log), prefix, 'e', fmt, ## __VA_ARGS__)
241
242/**
243 * invalf - Store supplementary invalid argument error message
244 * @fc: The context in which to log the error message
245 * @fmt: The format string
246 *
247 * Store the supplementary error message for the process if the process has
248 * enabled the facility and return -EINVAL.
249 */
250#define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL)
251#define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL)
252#define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL)
253#define invalfcp(fc, prefix, fmt, ...) \
254 (errorfcp(fc, prefix, fmt, ## __VA_ARGS__), -EINVAL)
255
256#endif /* _LINUX_FS_CONTEXT_H */
257