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
17 struct cred;
18 struct dentry;
19 struct file_operations;
20 struct file_system_type;
21 struct mnt_namespace;
22 struct net;
23 struct pid_namespace;
24 struct super_block;
25 struct user_namespace;
26 struct vfsmount;
27 struct path;
28
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) */
33 };
34
35 /*
36 * Userspace usage phase for fsopen/fspick.
37 */
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 */
46 };
47
48 /*
49 * Type of parameter value.
50 */
51 enum 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 */
63 struct 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
76 struct 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 */
90 struct 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
115 struct 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 */
127 extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
128 unsigned int sb_flags);
129 extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
130 unsigned int sb_flags,
131 unsigned int sb_flags_mask);
132 extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
133 struct dentry *reference);
134
135 extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
136 extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
137 extern int vfs_parse_fs_qstr(struct fs_context *fc, const char *key,
138 const struct qstr *value);
vfs_parse_fs_string(struct fs_context * fc,const char * key,const char * value)139 static 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 ? &QSTR(value) : NULL);
143 }
144 int vfs_parse_monolithic_sep(struct fs_context *fc, void *data,
145 char *(*sep)(char **));
146 extern int generic_parse_monolithic(struct fs_context *fc, void *data);
147 extern int vfs_get_tree(struct fs_context *fc);
148 extern void put_fs_context(struct fs_context *fc);
149 extern int vfs_parse_fs_param_source(struct fs_context *fc,
150 struct fs_parameter *param);
151 extern void fc_drop_locked(struct fs_context *fc);
152
153 int get_tree_super(struct fs_context *fc,
154 int (*test)(struct super_block *, struct fs_context *),
155 int (*fill_super)(struct super_block *sb,
156 struct fs_context *fc));
157 extern int get_tree_nodev(struct fs_context *fc,
158 int (*fill_super)(struct super_block *sb,
159 struct fs_context *fc));
160 extern int get_tree_single(struct fs_context *fc,
161 int (*fill_super)(struct super_block *sb,
162 struct fs_context *fc));
163 extern int get_tree_keyed(struct fs_context *fc,
164 int (*fill_super)(struct super_block *sb,
165 struct fs_context *fc),
166 void *key);
167
168 int setup_bdev_super(struct super_block *sb, int sb_flags,
169 struct fs_context *fc);
170
171 #define GET_TREE_BDEV_QUIET_LOOKUP 0x0001
172 int get_tree_bdev_flags(struct fs_context *fc,
173 int (*fill_super)(struct super_block *sb,
174 struct fs_context *fc), unsigned int flags);
175
176 extern int get_tree_bdev(struct fs_context *fc,
177 int (*fill_super)(struct super_block *sb,
178 struct fs_context *fc));
179
180 extern const struct file_operations fscontext_fops;
181
182 /*
183 * Mount error, warning and informational message logging. This structure is
184 * shareable between a mount and a subordinate mount.
185 */
186 struct fc_log {
187 refcount_t usage;
188 u8 head; /* Insertion index in buffer[] */
189 u8 tail; /* Removal index in buffer[] */
190 u8 need_free; /* Mask of kfree'able items in buffer[] */
191 struct module *owner; /* Owner module for strings that don't then need freeing */
192 char *buffer[8];
193 };
194
195 extern __attribute__((format(printf, 4, 5)))
196 void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...);
197
198 #define __logfc(fc, l, fmt, ...) \
199 logfc((fc)->log.log, NULL, (l), (fmt), ## __VA_ARGS__)
200 #define __plogp(p, prefix, l, fmt, ...) \
201 logfc((p)->log, (prefix), (l), (fmt), ## __VA_ARGS__)
202 #define __plog(p, l, fmt, ...) __plogp(p, (p)->prefix, l, fmt, ## __VA_ARGS__)
203
204 /**
205 * infof - Store supplementary informational message
206 * @fc: The context in which to log the informational message
207 * @fmt: The format string
208 *
209 * Store the supplementary informational message for the process if the process
210 * has enabled the facility.
211 */
212 #define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__)
213 #define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__)
214 #define infofc(fc, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__)
215 #define infofcp(fc, prefix, fmt, ...) \
216 __plogp((&(fc)->log), prefix, 'i', fmt, ## __VA_ARGS__)
217
218 /**
219 * warnf - Store supplementary warning message
220 * @fc: The context in which to log the error message
221 * @fmt: The format string
222 *
223 * Store the supplementary warning message for the process if the process has
224 * enabled the facility.
225 */
226 #define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__)
227 #define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__)
228 #define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__)
229 #define warnfcp(fc, prefix, fmt, ...) \
230 __plogp((&(fc)->log), prefix, 'w', fmt, ## __VA_ARGS__)
231
232 /**
233 * errorf - Store supplementary 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.
239 */
240 #define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__)
241 #define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__)
242 #define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__)
243 #define errorfcp(fc, prefix, fmt, ...) \
244 __plogp((&(fc)->log), prefix, 'e', fmt, ## __VA_ARGS__)
245
246 /**
247 * invalf - Store supplementary invalid argument error message
248 * @fc: The context in which to log the error message
249 * @fmt: The format string
250 *
251 * Store the supplementary error message for the process if the process has
252 * enabled the facility and return -EINVAL.
253 */
254 #define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL)
255 #define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL)
256 #define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL)
257 #define invalfcp(fc, prefix, fmt, ...) \
258 (errorfcp(fc, prefix, fmt, ## __VA_ARGS__), -EINVAL)
259
260 #endif /* _LINUX_FS_CONTEXT_H */
261