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; /* 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 bool oldapi:1; /* Coming from mount(2) */ 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 extern int generic_parse_monolithic(struct fs_context *fc, void *data); 140 extern int vfs_get_tree(struct fs_context *fc); 141 extern void put_fs_context(struct fs_context *fc); 142 extern int vfs_parse_fs_param_source(struct fs_context *fc, 143 struct fs_parameter *param); 144 extern void fc_drop_locked(struct fs_context *fc); 145 146 /* 147 * sget() wrappers to be called from the ->get_tree() op. 148 */ 149 enum vfs_get_super_keying { 150 vfs_get_single_super, /* Only one such superblock may exist */ 151 vfs_get_single_reconf_super, /* As above, but reconfigure if it exists */ 152 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */ 153 vfs_get_independent_super, /* Multiple independent superblocks may exist */ 154 }; 155 extern int vfs_get_super(struct fs_context *fc, 156 enum vfs_get_super_keying keying, 157 int (*fill_super)(struct super_block *sb, 158 struct fs_context *fc)); 159 160 extern int get_tree_nodev(struct fs_context *fc, 161 int (*fill_super)(struct super_block *sb, 162 struct fs_context *fc)); 163 extern int get_tree_single(struct fs_context *fc, 164 int (*fill_super)(struct super_block *sb, 165 struct fs_context *fc)); 166 extern int get_tree_single_reconf(struct fs_context *fc, 167 int (*fill_super)(struct super_block *sb, 168 struct fs_context *fc)); 169 extern int get_tree_keyed(struct fs_context *fc, 170 int (*fill_super)(struct super_block *sb, 171 struct fs_context *fc), 172 void *key); 173 174 extern int get_tree_bdev(struct fs_context *fc, 175 int (*fill_super)(struct super_block *sb, 176 struct fs_context *fc)); 177 178 extern const struct file_operations fscontext_fops; 179 180 /* 181 * Mount error, warning and informational message logging. This structure is 182 * shareable between a mount and a subordinate mount. 183 */ 184 struct fc_log { 185 refcount_t usage; 186 u8 head; /* Insertion index in buffer[] */ 187 u8 tail; /* Removal index in buffer[] */ 188 u8 need_free; /* Mask of kfree'able items in buffer[] */ 189 struct module *owner; /* Owner module for strings that don't then need freeing */ 190 char *buffer[8]; 191 }; 192 193 extern __attribute__((format(printf, 4, 5))) 194 void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...); 195 196 #define __logfc(fc, l, fmt, ...) logfc((fc)->log.log, NULL, \ 197 l, fmt, ## __VA_ARGS__) 198 #define __plog(p, l, fmt, ...) logfc((p)->log, (p)->prefix, \ 199 l, fmt, ## __VA_ARGS__) 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(p, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__) 211 212 /** 213 * warnf - Store supplementary warning message 214 * @fc: The context in which to log the error message 215 * @fmt: The format string 216 * 217 * Store the supplementary warning message for the process if the process has 218 * enabled the facility. 219 */ 220 #define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__) 221 #define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__) 222 #define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__) 223 224 /** 225 * errorf - Store supplementary error message 226 * @fc: The context in which to log the error message 227 * @fmt: The format string 228 * 229 * Store the supplementary error message for the process if the process has 230 * enabled the facility. 231 */ 232 #define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__) 233 #define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__) 234 #define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__) 235 236 /** 237 * invalf - Store supplementary invalid argument error message 238 * @fc: The context in which to log the error message 239 * @fmt: The format string 240 * 241 * Store the supplementary error message for the process if the process has 242 * enabled the facility and return -EINVAL. 243 */ 244 #define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL) 245 #define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL) 246 #define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL) 247 248 #endif /* _LINUX_FS_CONTEXT_H */ 249
