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 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_keyed(struct fs_context *fc,
160 int (*fill_super)(struct super_block *sb,
161 struct fs_context *fc),
162 void *key);
163
164 int setup_bdev_super(struct super_block *sb, int sb_flags,
165 struct fs_context *fc);
166
167 #define GET_TREE_BDEV_QUIET_LOOKUP 0x0001
168 int 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
172 extern int get_tree_bdev(struct fs_context *fc,
173 int (*fill_super)(struct super_block *sb,
174 struct fs_context *fc));
175
176 extern 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 */
182 struct 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
191 extern __attribute__((format(printf, 4, 5)))
192 void 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