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_string(struct fs_context *fc, const char *key, |
138 | const char *value, size_t v_size); |
139 | int vfs_parse_monolithic_sep(struct fs_context *fc, void *data, |
140 | char *(*sep)(char **)); |
141 | extern int generic_parse_monolithic(struct fs_context *fc, void *data); |
142 | extern int vfs_get_tree(struct fs_context *fc); |
143 | extern void put_fs_context(struct fs_context *fc); |
144 | extern int vfs_parse_fs_param_source(struct fs_context *fc, |
145 | struct fs_parameter *param); |
146 | extern void fc_drop_locked(struct fs_context *fc); |
147 | int reconfigure_single(struct super_block *s, |
148 | int flags, void *data); |
149 | |
150 | extern int get_tree_nodev(struct fs_context *fc, |
151 | int (*fill_super)(struct super_block *sb, |
152 | struct fs_context *fc)); |
153 | extern int get_tree_single(struct fs_context *fc, |
154 | int (*fill_super)(struct super_block *sb, |
155 | struct fs_context *fc)); |
156 | extern int get_tree_keyed(struct fs_context *fc, |
157 | int (*fill_super)(struct super_block *sb, |
158 | struct fs_context *fc), |
159 | void *key); |
160 | |
161 | int setup_bdev_super(struct super_block *sb, int sb_flags, |
162 | struct fs_context *fc); |
163 | extern int get_tree_bdev(struct fs_context *fc, |
164 | int (*fill_super)(struct super_block *sb, |
165 | struct fs_context *fc)); |
166 | |
167 | extern const struct file_operations fscontext_fops; |
168 | |
169 | /* |
170 | * Mount error, warning and informational message logging. This structure is |
171 | * shareable between a mount and a subordinate mount. |
172 | */ |
173 | struct fc_log { |
174 | refcount_t usage; |
175 | u8 head; /* Insertion index in buffer[] */ |
176 | u8 tail; /* Removal index in buffer[] */ |
177 | u8 need_free; /* Mask of kfree'able items in buffer[] */ |
178 | struct module *owner; /* Owner module for strings that don't then need freeing */ |
179 | char *buffer[8]; |
180 | }; |
181 | |
182 | extern __attribute__((format(printf, 4, 5))) |
183 | void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...); |
184 | |
185 | #define __logfc(fc, l, fmt, ...) logfc((fc)->log.log, NULL, \ |
186 | l, fmt, ## __VA_ARGS__) |
187 | #define __plog(p, l, fmt, ...) logfc((p)->log, (p)->prefix, \ |
188 | l, fmt, ## __VA_ARGS__) |
189 | /** |
190 | * infof - Store supplementary informational message |
191 | * @fc: The context in which to log the informational message |
192 | * @fmt: The format string |
193 | * |
194 | * Store the supplementary informational message for the process if the process |
195 | * has enabled the facility. |
196 | */ |
197 | #define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__) |
198 | #define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__) |
199 | #define infofc(p, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__) |
200 | |
201 | /** |
202 | * warnf - Store supplementary warning message |
203 | * @fc: The context in which to log the error message |
204 | * @fmt: The format string |
205 | * |
206 | * Store the supplementary warning message for the process if the process has |
207 | * enabled the facility. |
208 | */ |
209 | #define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__) |
210 | #define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__) |
211 | #define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__) |
212 | |
213 | /** |
214 | * errorf - Store supplementary error message |
215 | * @fc: The context in which to log the error message |
216 | * @fmt: The format string |
217 | * |
218 | * Store the supplementary error message for the process if the process has |
219 | * enabled the facility. |
220 | */ |
221 | #define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__) |
222 | #define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__) |
223 | #define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__) |
224 | |
225 | /** |
226 | * invalf - Store supplementary invalid argument error message |
227 | * @fc: The context in which to log the error message |
228 | * @fmt: The format string |
229 | * |
230 | * Store the supplementary error message for the process if the process has |
231 | * enabled the facility and return -EINVAL. |
232 | */ |
233 | #define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL) |
234 | #define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL) |
235 | #define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL) |
236 | |
237 | #endif /* _LINUX_FS_CONTEXT_H */ |
238 | |